thread.cpp revision 7331:110ec5963eb1
1/* 2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26#include "classfile/classLoader.hpp" 27#include "classfile/javaClasses.hpp" 28#include "classfile/systemDictionary.hpp" 29#include "classfile/vmSymbols.hpp" 30#include "code/codeCache.hpp" 31#include "code/scopeDesc.hpp" 32#include "compiler/compileBroker.hpp" 33#include "interpreter/interpreter.hpp" 34#include "interpreter/linkResolver.hpp" 35#include "interpreter/oopMapCache.hpp" 36#include "jvmtifiles/jvmtiEnv.hpp" 37#include "memory/gcLocker.inline.hpp" 38#include "memory/metaspaceShared.hpp" 39#include "memory/oopFactory.hpp" 40#include "memory/universe.inline.hpp" 41#include "oops/instanceKlass.hpp" 42#include "oops/objArrayOop.hpp" 43#include "oops/oop.inline.hpp" 44#include "oops/symbol.hpp" 45#include "prims/jvm_misc.hpp" 46#include "prims/jvmtiExport.hpp" 47#include "prims/jvmtiThreadState.hpp" 48#include "prims/privilegedStack.hpp" 49#include "runtime/arguments.hpp" 50#include "runtime/atomic.inline.hpp" 51#include "runtime/biasedLocking.hpp" 52#include "runtime/deoptimization.hpp" 53#include "runtime/fprofiler.hpp" 54#include "runtime/frame.inline.hpp" 55#include "runtime/init.hpp" 56#include "runtime/interfaceSupport.hpp" 57#include "runtime/java.hpp" 58#include "runtime/javaCalls.hpp" 59#include "runtime/jniPeriodicChecker.hpp" 60#include "runtime/memprofiler.hpp" 61#include "runtime/mutexLocker.hpp" 62#include "runtime/objectMonitor.hpp" 63#include "runtime/orderAccess.inline.hpp" 64#include "runtime/osThread.hpp" 65#include "runtime/safepoint.hpp" 66#include "runtime/sharedRuntime.hpp" 67#include "runtime/statSampler.hpp" 68#include "runtime/stubRoutines.hpp" 69#include "runtime/sweeper.hpp" 70#include "runtime/task.hpp" 71#include "runtime/thread.inline.hpp" 72#include "runtime/threadCritical.hpp" 73#include "runtime/threadLocalStorage.hpp" 74#include "runtime/vframe.hpp" 75#include "runtime/vframeArray.hpp" 76#include "runtime/vframe_hp.hpp" 77#include "runtime/vmThread.hpp" 78#include "runtime/vm_operations.hpp" 79#include "runtime/vm_version.hpp" 80#include "services/attachListener.hpp" 81#include "services/management.hpp" 82#include "services/memTracker.hpp" 83#include "services/threadService.hpp" 84#include "trace/tracing.hpp" 85#include "trace/traceMacros.hpp" 86#include "utilities/defaultStream.hpp" 87#include "utilities/dtrace.hpp" 88#include "utilities/events.hpp" 89#include "utilities/preserveException.hpp" 90#include "utilities/macros.hpp" 91#if INCLUDE_ALL_GCS 92#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 93#include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 94#include "gc_implementation/parallelScavenge/pcTasks.hpp" 95#endif // INCLUDE_ALL_GCS 96#ifdef COMPILER1 97#include "c1/c1_Compiler.hpp" 98#endif 99#ifdef COMPILER2 100#include "opto/c2compiler.hpp" 101#include "opto/idealGraphPrinter.hpp" 102#endif 103#if INCLUDE_RTM_OPT 104#include "runtime/rtmLocking.hpp" 105#endif 106 107PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 108 109#ifdef DTRACE_ENABLED 110 111// Only bother with this argument setup if dtrace is available 112 113 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 114 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 115 116 #define DTRACE_THREAD_PROBE(probe, javathread) \ 117 { \ 118 ResourceMark rm(this); \ 119 int len = 0; \ 120 const char* name = (javathread)->get_thread_name(); \ 121 len = strlen(name); \ 122 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 123 (char *) name, len, \ 124 java_lang_Thread::thread_id((javathread)->threadObj()), \ 125 (uintptr_t) (javathread)->osthread()->thread_id(), \ 126 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 127 } 128 129#else // ndef DTRACE_ENABLED 130 131 #define DTRACE_THREAD_PROBE(probe, javathread) 132 133#endif // ndef DTRACE_ENABLED 134 135 136// Class hierarchy 137// - Thread 138// - VMThread 139// - WatcherThread 140// - ConcurrentMarkSweepThread 141// - JavaThread 142// - CompilerThread 143 144// ======= Thread ======== 145// Support for forcing alignment of thread objects for biased locking 146void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 147 if (UseBiasedLocking) { 148 const int alignment = markOopDesc::biased_lock_alignment; 149 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 150 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 151 : AllocateHeap(aligned_size, flags, CURRENT_PC, 152 AllocFailStrategy::RETURN_NULL); 153 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 154 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 155 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 156 "JavaThread alignment code overflowed allocated storage"); 157 if (TraceBiasedLocking) { 158 if (aligned_addr != real_malloc_addr) { 159 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 160 real_malloc_addr, aligned_addr); 161 } 162 } 163 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 164 return aligned_addr; 165 } else { 166 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 167 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 168 } 169} 170 171void Thread::operator delete(void* p) { 172 if (UseBiasedLocking) { 173 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 174 FreeHeap(real_malloc_addr, mtThread); 175 } else { 176 FreeHeap(p, mtThread); 177 } 178} 179 180 181// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 182// JavaThread 183 184 185Thread::Thread() { 186 // stack and get_thread 187 set_stack_base(NULL); 188 set_stack_size(0); 189 set_self_raw_id(0); 190 set_lgrp_id(-1); 191 192 // allocated data structures 193 set_osthread(NULL); 194 set_resource_area(new (mtThread)ResourceArea()); 195 DEBUG_ONLY(_current_resource_mark = NULL;) 196 set_handle_area(new (mtThread) HandleArea(NULL)); 197 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 198 set_active_handles(NULL); 199 set_free_handle_block(NULL); 200 set_last_handle_mark(NULL); 201 202 // This initial value ==> never claimed. 203 _oops_do_parity = 0; 204 205 _metadata_on_stack_buffer = NULL; 206 207 // the handle mark links itself to last_handle_mark 208 new HandleMark(this); 209 210 // plain initialization 211 debug_only(_owned_locks = NULL;) 212 debug_only(_allow_allocation_count = 0;) 213 NOT_PRODUCT(_allow_safepoint_count = 0;) 214 NOT_PRODUCT(_skip_gcalot = false;) 215 _jvmti_env_iteration_count = 0; 216 set_allocated_bytes(0); 217 _vm_operation_started_count = 0; 218 _vm_operation_completed_count = 0; 219 _current_pending_monitor = NULL; 220 _current_pending_monitor_is_from_java = true; 221 _current_waiting_monitor = NULL; 222 _num_nested_signal = 0; 223 omFreeList = NULL; 224 omFreeCount = 0; 225 omFreeProvision = 32; 226 omInUseList = NULL; 227 omInUseCount = 0; 228 229#ifdef ASSERT 230 _visited_for_critical_count = false; 231#endif 232 233 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 234 _suspend_flags = 0; 235 236 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 237 _hashStateX = os::random(); 238 _hashStateY = 842502087; 239 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 240 _hashStateW = 273326509; 241 242 _OnTrap = 0; 243 _schedctl = NULL; 244 _Stalled = 0; 245 _TypeTag = 0x2BAD; 246 247 // Many of the following fields are effectively final - immutable 248 // Note that nascent threads can't use the Native Monitor-Mutex 249 // construct until the _MutexEvent is initialized ... 250 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 251 // we might instead use a stack of ParkEvents that we could provision on-demand. 252 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 253 // and ::Release() 254 _ParkEvent = ParkEvent::Allocate(this); 255 _SleepEvent = ParkEvent::Allocate(this); 256 _MutexEvent = ParkEvent::Allocate(this); 257 _MuxEvent = ParkEvent::Allocate(this); 258 259#ifdef CHECK_UNHANDLED_OOPS 260 if (CheckUnhandledOops) { 261 _unhandled_oops = new UnhandledOops(this); 262 } 263#endif // CHECK_UNHANDLED_OOPS 264#ifdef ASSERT 265 if (UseBiasedLocking) { 266 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 267 assert(this == _real_malloc_address || 268 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 269 "bug in forced alignment of thread objects"); 270 } 271#endif // ASSERT 272} 273 274void Thread::initialize_thread_local_storage() { 275 // Note: Make sure this method only calls 276 // non-blocking operations. Otherwise, it might not work 277 // with the thread-startup/safepoint interaction. 278 279 // During Java thread startup, safepoint code should allow this 280 // method to complete because it may need to allocate memory to 281 // store information for the new thread. 282 283 // initialize structure dependent on thread local storage 284 ThreadLocalStorage::set_thread(this); 285} 286 287void Thread::record_stack_base_and_size() { 288 set_stack_base(os::current_stack_base()); 289 set_stack_size(os::current_stack_size()); 290 if (is_Java_thread()) { 291 ((JavaThread*) this)->set_stack_overflow_limit(); 292 } 293 // CR 7190089: on Solaris, primordial thread's stack is adjusted 294 // in initialize_thread(). Without the adjustment, stack size is 295 // incorrect if stack is set to unlimited (ulimit -s unlimited). 296 // So far, only Solaris has real implementation of initialize_thread(). 297 // 298 // set up any platform-specific state. 299 os::initialize_thread(this); 300 301#if INCLUDE_NMT 302 // record thread's native stack, stack grows downward 303 address stack_low_addr = stack_base() - stack_size(); 304 MemTracker::record_thread_stack(stack_low_addr, stack_size()); 305#endif // INCLUDE_NMT 306} 307 308 309Thread::~Thread() { 310 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 311 ObjectSynchronizer::omFlush(this); 312 313 EVENT_THREAD_DESTRUCT(this); 314 315 // stack_base can be NULL if the thread is never started or exited before 316 // record_stack_base_and_size called. Although, we would like to ensure 317 // that all started threads do call record_stack_base_and_size(), there is 318 // not proper way to enforce that. 319#if INCLUDE_NMT 320 if (_stack_base != NULL) { 321 address low_stack_addr = stack_base() - stack_size(); 322 MemTracker::release_thread_stack(low_stack_addr, stack_size()); 323#ifdef ASSERT 324 set_stack_base(NULL); 325#endif 326 } 327#endif // INCLUDE_NMT 328 329 // deallocate data structures 330 delete resource_area(); 331 // since the handle marks are using the handle area, we have to deallocated the root 332 // handle mark before deallocating the thread's handle area, 333 assert(last_handle_mark() != NULL, "check we have an element"); 334 delete last_handle_mark(); 335 assert(last_handle_mark() == NULL, "check we have reached the end"); 336 337 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 338 // We NULL out the fields for good hygiene. 339 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 340 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 341 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 342 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 343 344 delete handle_area(); 345 delete metadata_handles(); 346 347 // osthread() can be NULL, if creation of thread failed. 348 if (osthread() != NULL) os::free_thread(osthread()); 349 350 delete _SR_lock; 351 352 // clear thread local storage if the Thread is deleting itself 353 if (this == Thread::current()) { 354 ThreadLocalStorage::set_thread(NULL); 355 } else { 356 // In the case where we're not the current thread, invalidate all the 357 // caches in case some code tries to get the current thread or the 358 // thread that was destroyed, and gets stale information. 359 ThreadLocalStorage::invalidate_all(); 360 } 361 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 362} 363 364// NOTE: dummy function for assertion purpose. 365void Thread::run() { 366 ShouldNotReachHere(); 367} 368 369#ifdef ASSERT 370// Private method to check for dangling thread pointer 371void check_for_dangling_thread_pointer(Thread *thread) { 372 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 373 "possibility of dangling Thread pointer"); 374} 375#endif 376 377 378#ifndef PRODUCT 379// Tracing method for basic thread operations 380void Thread::trace(const char* msg, const Thread* const thread) { 381 if (!TraceThreadEvents) return; 382 ResourceMark rm; 383 ThreadCritical tc; 384 const char *name = "non-Java thread"; 385 int prio = -1; 386 if (thread->is_Java_thread() 387 && !thread->is_Compiler_thread()) { 388 // The Threads_lock must be held to get information about 389 // this thread but may not be in some situations when 390 // tracing thread events. 391 bool release_Threads_lock = false; 392 if (!Threads_lock->owned_by_self()) { 393 Threads_lock->lock(); 394 release_Threads_lock = true; 395 } 396 JavaThread* jt = (JavaThread *)thread; 397 name = (char *)jt->get_thread_name(); 398 oop thread_oop = jt->threadObj(); 399 if (thread_oop != NULL) { 400 prio = java_lang_Thread::priority(thread_oop); 401 } 402 if (release_Threads_lock) { 403 Threads_lock->unlock(); 404 } 405 } 406 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 407} 408#endif 409 410 411ThreadPriority Thread::get_priority(const Thread* const thread) { 412 trace("get priority", thread); 413 ThreadPriority priority; 414 // Can return an error! 415 (void)os::get_priority(thread, priority); 416 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 417 return priority; 418} 419 420void Thread::set_priority(Thread* thread, ThreadPriority priority) { 421 trace("set priority", thread); 422 debug_only(check_for_dangling_thread_pointer(thread);) 423 // Can return an error! 424 (void)os::set_priority(thread, priority); 425} 426 427 428void Thread::start(Thread* thread) { 429 trace("start", thread); 430 // Start is different from resume in that its safety is guaranteed by context or 431 // being called from a Java method synchronized on the Thread object. 432 if (!DisableStartThread) { 433 if (thread->is_Java_thread()) { 434 // Initialize the thread state to RUNNABLE before starting this thread. 435 // Can not set it after the thread started because we do not know the 436 // exact thread state at that time. It could be in MONITOR_WAIT or 437 // in SLEEPING or some other state. 438 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 439 java_lang_Thread::RUNNABLE); 440 } 441 os::start_thread(thread); 442 } 443} 444 445// Enqueue a VM_Operation to do the job for us - sometime later 446void Thread::send_async_exception(oop java_thread, oop java_throwable) { 447 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 448 VMThread::execute(vm_stop); 449} 450 451 452// Check if an external suspend request has completed (or has been 453// cancelled). Returns true if the thread is externally suspended and 454// false otherwise. 455// 456// The bits parameter returns information about the code path through 457// the routine. Useful for debugging: 458// 459// set in is_ext_suspend_completed(): 460// 0x00000001 - routine was entered 461// 0x00000010 - routine return false at end 462// 0x00000100 - thread exited (return false) 463// 0x00000200 - suspend request cancelled (return false) 464// 0x00000400 - thread suspended (return true) 465// 0x00001000 - thread is in a suspend equivalent state (return true) 466// 0x00002000 - thread is native and walkable (return true) 467// 0x00004000 - thread is native_trans and walkable (needed retry) 468// 469// set in wait_for_ext_suspend_completion(): 470// 0x00010000 - routine was entered 471// 0x00020000 - suspend request cancelled before loop (return false) 472// 0x00040000 - thread suspended before loop (return true) 473// 0x00080000 - suspend request cancelled in loop (return false) 474// 0x00100000 - thread suspended in loop (return true) 475// 0x00200000 - suspend not completed during retry loop (return false) 476 477// Helper class for tracing suspend wait debug bits. 478// 479// 0x00000100 indicates that the target thread exited before it could 480// self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 481// 0x00080000 each indicate a cancelled suspend request so they don't 482// count as wait failures either. 483#define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 484 485class TraceSuspendDebugBits : public StackObj { 486 private: 487 JavaThread * jt; 488 bool is_wait; 489 bool called_by_wait; // meaningful when !is_wait 490 uint32_t * bits; 491 492 public: 493 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 494 uint32_t *_bits) { 495 jt = _jt; 496 is_wait = _is_wait; 497 called_by_wait = _called_by_wait; 498 bits = _bits; 499 } 500 501 ~TraceSuspendDebugBits() { 502 if (!is_wait) { 503#if 1 504 // By default, don't trace bits for is_ext_suspend_completed() calls. 505 // That trace is very chatty. 506 return; 507#else 508 if (!called_by_wait) { 509 // If tracing for is_ext_suspend_completed() is enabled, then only 510 // trace calls to it from wait_for_ext_suspend_completion() 511 return; 512 } 513#endif 514 } 515 516 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 517 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 518 MutexLocker ml(Threads_lock); // needed for get_thread_name() 519 ResourceMark rm; 520 521 tty->print_cr( 522 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 523 jt->get_thread_name(), *bits); 524 525 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 526 } 527 } 528 } 529}; 530#undef DEBUG_FALSE_BITS 531 532 533bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 534 uint32_t *bits) { 535 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 536 537 bool did_trans_retry = false; // only do thread_in_native_trans retry once 538 bool do_trans_retry; // flag to force the retry 539 540 *bits |= 0x00000001; 541 542 do { 543 do_trans_retry = false; 544 545 if (is_exiting()) { 546 // Thread is in the process of exiting. This is always checked 547 // first to reduce the risk of dereferencing a freed JavaThread. 548 *bits |= 0x00000100; 549 return false; 550 } 551 552 if (!is_external_suspend()) { 553 // Suspend request is cancelled. This is always checked before 554 // is_ext_suspended() to reduce the risk of a rogue resume 555 // confusing the thread that made the suspend request. 556 *bits |= 0x00000200; 557 return false; 558 } 559 560 if (is_ext_suspended()) { 561 // thread is suspended 562 *bits |= 0x00000400; 563 return true; 564 } 565 566 // Now that we no longer do hard suspends of threads running 567 // native code, the target thread can be changing thread state 568 // while we are in this routine: 569 // 570 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 571 // 572 // We save a copy of the thread state as observed at this moment 573 // and make our decision about suspend completeness based on the 574 // copy. This closes the race where the thread state is seen as 575 // _thread_in_native_trans in the if-thread_blocked check, but is 576 // seen as _thread_blocked in if-thread_in_native_trans check. 577 JavaThreadState save_state = thread_state(); 578 579 if (save_state == _thread_blocked && is_suspend_equivalent()) { 580 // If the thread's state is _thread_blocked and this blocking 581 // condition is known to be equivalent to a suspend, then we can 582 // consider the thread to be externally suspended. This means that 583 // the code that sets _thread_blocked has been modified to do 584 // self-suspension if the blocking condition releases. We also 585 // used to check for CONDVAR_WAIT here, but that is now covered by 586 // the _thread_blocked with self-suspension check. 587 // 588 // Return true since we wouldn't be here unless there was still an 589 // external suspend request. 590 *bits |= 0x00001000; 591 return true; 592 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 593 // Threads running native code will self-suspend on native==>VM/Java 594 // transitions. If its stack is walkable (should always be the case 595 // unless this function is called before the actual java_suspend() 596 // call), then the wait is done. 597 *bits |= 0x00002000; 598 return true; 599 } else if (!called_by_wait && !did_trans_retry && 600 save_state == _thread_in_native_trans && 601 frame_anchor()->walkable()) { 602 // The thread is transitioning from thread_in_native to another 603 // thread state. check_safepoint_and_suspend_for_native_trans() 604 // will force the thread to self-suspend. If it hasn't gotten 605 // there yet we may have caught the thread in-between the native 606 // code check above and the self-suspend. Lucky us. If we were 607 // called by wait_for_ext_suspend_completion(), then it 608 // will be doing the retries so we don't have to. 609 // 610 // Since we use the saved thread state in the if-statement above, 611 // there is a chance that the thread has already transitioned to 612 // _thread_blocked by the time we get here. In that case, we will 613 // make a single unnecessary pass through the logic below. This 614 // doesn't hurt anything since we still do the trans retry. 615 616 *bits |= 0x00004000; 617 618 // Once the thread leaves thread_in_native_trans for another 619 // thread state, we break out of this retry loop. We shouldn't 620 // need this flag to prevent us from getting back here, but 621 // sometimes paranoia is good. 622 did_trans_retry = true; 623 624 // We wait for the thread to transition to a more usable state. 625 for (int i = 1; i <= SuspendRetryCount; i++) { 626 // We used to do an "os::yield_all(i)" call here with the intention 627 // that yielding would increase on each retry. However, the parameter 628 // is ignored on Linux which means the yield didn't scale up. Waiting 629 // on the SR_lock below provides a much more predictable scale up for 630 // the delay. It also provides a simple/direct point to check for any 631 // safepoint requests from the VMThread 632 633 // temporarily drops SR_lock while doing wait with safepoint check 634 // (if we're a JavaThread - the WatcherThread can also call this) 635 // and increase delay with each retry 636 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 637 638 // check the actual thread state instead of what we saved above 639 if (thread_state() != _thread_in_native_trans) { 640 // the thread has transitioned to another thread state so 641 // try all the checks (except this one) one more time. 642 do_trans_retry = true; 643 break; 644 } 645 } // end retry loop 646 647 648 } 649 } while (do_trans_retry); 650 651 *bits |= 0x00000010; 652 return false; 653} 654 655// Wait for an external suspend request to complete (or be cancelled). 656// Returns true if the thread is externally suspended and false otherwise. 657// 658bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 659 uint32_t *bits) { 660 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 661 false /* !called_by_wait */, bits); 662 663 // local flag copies to minimize SR_lock hold time 664 bool is_suspended; 665 bool pending; 666 uint32_t reset_bits; 667 668 // set a marker so is_ext_suspend_completed() knows we are the caller 669 *bits |= 0x00010000; 670 671 // We use reset_bits to reinitialize the bits value at the top of 672 // each retry loop. This allows the caller to make use of any 673 // unused bits for their own marking purposes. 674 reset_bits = *bits; 675 676 { 677 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 678 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 679 delay, bits); 680 pending = is_external_suspend(); 681 } 682 // must release SR_lock to allow suspension to complete 683 684 if (!pending) { 685 // A cancelled suspend request is the only false return from 686 // is_ext_suspend_completed() that keeps us from entering the 687 // retry loop. 688 *bits |= 0x00020000; 689 return false; 690 } 691 692 if (is_suspended) { 693 *bits |= 0x00040000; 694 return true; 695 } 696 697 for (int i = 1; i <= retries; i++) { 698 *bits = reset_bits; // reinit to only track last retry 699 700 // We used to do an "os::yield_all(i)" call here with the intention 701 // that yielding would increase on each retry. However, the parameter 702 // is ignored on Linux which means the yield didn't scale up. Waiting 703 // on the SR_lock below provides a much more predictable scale up for 704 // the delay. It also provides a simple/direct point to check for any 705 // safepoint requests from the VMThread 706 707 { 708 MutexLocker ml(SR_lock()); 709 // wait with safepoint check (if we're a JavaThread - the WatcherThread 710 // can also call this) and increase delay with each retry 711 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 712 713 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 714 delay, bits); 715 716 // It is possible for the external suspend request to be cancelled 717 // (by a resume) before the actual suspend operation is completed. 718 // Refresh our local copy to see if we still need to wait. 719 pending = is_external_suspend(); 720 } 721 722 if (!pending) { 723 // A cancelled suspend request is the only false return from 724 // is_ext_suspend_completed() that keeps us from staying in the 725 // retry loop. 726 *bits |= 0x00080000; 727 return false; 728 } 729 730 if (is_suspended) { 731 *bits |= 0x00100000; 732 return true; 733 } 734 } // end retry loop 735 736 // thread did not suspend after all our retries 737 *bits |= 0x00200000; 738 return false; 739} 740 741#ifndef PRODUCT 742void JavaThread::record_jump(address target, address instr, const char* file, 743 int line) { 744 745 // This should not need to be atomic as the only way for simultaneous 746 // updates is via interrupts. Even then this should be rare or non-existent 747 // and we don't care that much anyway. 748 749 int index = _jmp_ring_index; 750 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 751 _jmp_ring[index]._target = (intptr_t) target; 752 _jmp_ring[index]._instruction = (intptr_t) instr; 753 _jmp_ring[index]._file = file; 754 _jmp_ring[index]._line = line; 755} 756#endif // PRODUCT 757 758// Called by flat profiler 759// Callers have already called wait_for_ext_suspend_completion 760// The assertion for that is currently too complex to put here: 761bool JavaThread::profile_last_Java_frame(frame* _fr) { 762 bool gotframe = false; 763 // self suspension saves needed state. 764 if (has_last_Java_frame() && _anchor.walkable()) { 765 *_fr = pd_last_frame(); 766 gotframe = true; 767 } 768 return gotframe; 769} 770 771void Thread::interrupt(Thread* thread) { 772 trace("interrupt", thread); 773 debug_only(check_for_dangling_thread_pointer(thread);) 774 os::interrupt(thread); 775} 776 777bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 778 trace("is_interrupted", thread); 779 debug_only(check_for_dangling_thread_pointer(thread);) 780 // Note: If clear_interrupted==false, this simply fetches and 781 // returns the value of the field osthread()->interrupted(). 782 return os::is_interrupted(thread, clear_interrupted); 783} 784 785 786// GC Support 787bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 788 jint thread_parity = _oops_do_parity; 789 if (thread_parity != strong_roots_parity) { 790 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 791 if (res == thread_parity) { 792 return true; 793 } else { 794 guarantee(res == strong_roots_parity, "Or else what?"); 795 assert(SharedHeap::heap()->workers()->active_workers() > 0, 796 "Should only fail when parallel."); 797 return false; 798 } 799 } 800 assert(SharedHeap::heap()->workers()->active_workers() > 0, 801 "Should only fail when parallel."); 802 return false; 803} 804 805void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 806 active_handles()->oops_do(f); 807 // Do oop for ThreadShadow 808 f->do_oop((oop*)&_pending_exception); 809 handle_area()->oops_do(f); 810} 811 812void Thread::nmethods_do(CodeBlobClosure* cf) { 813 // no nmethods in a generic thread... 814} 815 816void Thread::metadata_do(void f(Metadata*)) { 817 if (metadata_handles() != NULL) { 818 for (int i = 0; i< metadata_handles()->length(); i++) { 819 f(metadata_handles()->at(i)); 820 } 821 } 822} 823 824void Thread::print_on(outputStream* st) const { 825 // get_priority assumes osthread initialized 826 if (osthread() != NULL) { 827 int os_prio; 828 if (os::get_native_priority(this, &os_prio) == OS_OK) { 829 st->print("os_prio=%d ", os_prio); 830 } 831 st->print("tid=" INTPTR_FORMAT " ", this); 832 ext().print_on(st); 833 osthread()->print_on(st); 834 } 835 debug_only(if (WizardMode) print_owned_locks_on(st);) 836} 837 838// Thread::print_on_error() is called by fatal error handler. Don't use 839// any lock or allocate memory. 840void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 841 if (is_VM_thread()) st->print("VMThread"); 842 else if (is_Compiler_thread()) st->print("CompilerThread"); 843 else if (is_Java_thread()) st->print("JavaThread"); 844 else if (is_GC_task_thread()) st->print("GCTaskThread"); 845 else if (is_Watcher_thread()) st->print("WatcherThread"); 846 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 847 else st->print("Thread"); 848 849 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 850 _stack_base - _stack_size, _stack_base); 851 852 if (osthread()) { 853 st->print(" [id=%d]", osthread()->thread_id()); 854 } 855} 856 857#ifdef ASSERT 858void Thread::print_owned_locks_on(outputStream* st) const { 859 Monitor *cur = _owned_locks; 860 if (cur == NULL) { 861 st->print(" (no locks) "); 862 } else { 863 st->print_cr(" Locks owned:"); 864 while (cur) { 865 cur->print_on(st); 866 cur = cur->next(); 867 } 868 } 869} 870 871static int ref_use_count = 0; 872 873bool Thread::owns_locks_but_compiled_lock() const { 874 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 875 if (cur != Compile_lock) return true; 876 } 877 return false; 878} 879 880 881#endif 882 883#ifndef PRODUCT 884 885// The flag: potential_vm_operation notifies if this particular safepoint state could potential 886// invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 887// no threads which allow_vm_block's are held 888void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 889 // Check if current thread is allowed to block at a safepoint 890 if (!(_allow_safepoint_count == 0)) { 891 fatal("Possible safepoint reached by thread that does not allow it"); 892 } 893 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 894 fatal("LEAF method calling lock?"); 895 } 896 897#ifdef ASSERT 898 if (potential_vm_operation && is_Java_thread() 899 && !Universe::is_bootstrapping()) { 900 // Make sure we do not hold any locks that the VM thread also uses. 901 // This could potentially lead to deadlocks 902 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 903 // Threads_lock is special, since the safepoint synchronization will not start before this is 904 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 905 // since it is used to transfer control between JavaThreads and the VMThread 906 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 907 if ((cur->allow_vm_block() && 908 cur != Threads_lock && 909 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 910 cur != VMOperationRequest_lock && 911 cur != VMOperationQueue_lock) || 912 cur->rank() == Mutex::special) { 913 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name())); 914 } 915 } 916 } 917 918 if (GCALotAtAllSafepoints) { 919 // We could enter a safepoint here and thus have a gc 920 InterfaceSupport::check_gc_alot(); 921 } 922#endif 923} 924#endif 925 926bool Thread::is_in_stack(address adr) const { 927 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 928 address end = os::current_stack_pointer(); 929 // Allow non Java threads to call this without stack_base 930 if (_stack_base == NULL) return true; 931 if (stack_base() >= adr && adr >= end) return true; 932 933 return false; 934} 935 936 937bool Thread::is_in_usable_stack(address adr) const { 938 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0; 939 size_t usable_stack_size = _stack_size - stack_guard_size; 940 941 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 942} 943 944 945// We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 946// However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 947// used for compilation in the future. If that change is made, the need for these methods 948// should be revisited, and they should be removed if possible. 949 950bool Thread::is_lock_owned(address adr) const { 951 return on_local_stack(adr); 952} 953 954bool Thread::set_as_starting_thread() { 955 // NOTE: this must be called inside the main thread. 956 return os::create_main_thread((JavaThread*)this); 957} 958 959static void initialize_class(Symbol* class_name, TRAPS) { 960 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 961 InstanceKlass::cast(klass)->initialize(CHECK); 962} 963 964 965// Creates the initial ThreadGroup 966static Handle create_initial_thread_group(TRAPS) { 967 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 968 instanceKlassHandle klass (THREAD, k); 969 970 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 971 { 972 JavaValue result(T_VOID); 973 JavaCalls::call_special(&result, 974 system_instance, 975 klass, 976 vmSymbols::object_initializer_name(), 977 vmSymbols::void_method_signature(), 978 CHECK_NH); 979 } 980 Universe::set_system_thread_group(system_instance()); 981 982 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 983 { 984 JavaValue result(T_VOID); 985 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 986 JavaCalls::call_special(&result, 987 main_instance, 988 klass, 989 vmSymbols::object_initializer_name(), 990 vmSymbols::threadgroup_string_void_signature(), 991 system_instance, 992 string, 993 CHECK_NH); 994 } 995 return main_instance; 996} 997 998// Creates the initial Thread 999static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1000 TRAPS) { 1001 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1002 instanceKlassHandle klass (THREAD, k); 1003 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 1004 1005 java_lang_Thread::set_thread(thread_oop(), thread); 1006 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1007 thread->set_threadObj(thread_oop()); 1008 1009 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1010 1011 JavaValue result(T_VOID); 1012 JavaCalls::call_special(&result, thread_oop, 1013 klass, 1014 vmSymbols::object_initializer_name(), 1015 vmSymbols::threadgroup_string_void_signature(), 1016 thread_group, 1017 string, 1018 CHECK_NULL); 1019 return thread_oop(); 1020} 1021 1022static void call_initializeSystemClass(TRAPS) { 1023 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1024 instanceKlassHandle klass (THREAD, k); 1025 1026 JavaValue result(T_VOID); 1027 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 1028 vmSymbols::void_method_signature(), CHECK); 1029} 1030 1031char java_runtime_name[128] = ""; 1032char java_runtime_version[128] = ""; 1033 1034// extract the JRE name from sun.misc.Version.java_runtime_name 1035static const char* get_java_runtime_name(TRAPS) { 1036 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1037 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1038 fieldDescriptor fd; 1039 bool found = k != NULL && 1040 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1041 vmSymbols::string_signature(), &fd); 1042 if (found) { 1043 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1044 if (name_oop == NULL) { 1045 return NULL; 1046 } 1047 const char* name = java_lang_String::as_utf8_string(name_oop, 1048 java_runtime_name, 1049 sizeof(java_runtime_name)); 1050 return name; 1051 } else { 1052 return NULL; 1053 } 1054} 1055 1056// extract the JRE version from sun.misc.Version.java_runtime_version 1057static const char* get_java_runtime_version(TRAPS) { 1058 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1059 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1060 fieldDescriptor fd; 1061 bool found = k != NULL && 1062 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1063 vmSymbols::string_signature(), &fd); 1064 if (found) { 1065 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1066 if (name_oop == NULL) { 1067 return NULL; 1068 } 1069 const char* name = java_lang_String::as_utf8_string(name_oop, 1070 java_runtime_version, 1071 sizeof(java_runtime_version)); 1072 return name; 1073 } else { 1074 return NULL; 1075 } 1076} 1077 1078// General purpose hook into Java code, run once when the VM is initialized. 1079// The Java library method itself may be changed independently from the VM. 1080static void call_postVMInitHook(TRAPS) { 1081 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1082 instanceKlassHandle klass (THREAD, k); 1083 if (klass.not_null()) { 1084 JavaValue result(T_VOID); 1085 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1086 vmSymbols::void_method_signature(), 1087 CHECK); 1088 } 1089} 1090 1091static void reset_vm_info_property(TRAPS) { 1092 // the vm info string 1093 ResourceMark rm(THREAD); 1094 const char *vm_info = VM_Version::vm_info_string(); 1095 1096 // java.lang.System class 1097 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1098 instanceKlassHandle klass (THREAD, k); 1099 1100 // setProperty arguments 1101 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1102 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1103 1104 // return value 1105 JavaValue r(T_OBJECT); 1106 1107 // public static String setProperty(String key, String value); 1108 JavaCalls::call_static(&r, 1109 klass, 1110 vmSymbols::setProperty_name(), 1111 vmSymbols::string_string_string_signature(), 1112 key_str, 1113 value_str, 1114 CHECK); 1115} 1116 1117 1118void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, 1119 bool daemon, TRAPS) { 1120 assert(thread_group.not_null(), "thread group should be specified"); 1121 assert(threadObj() == NULL, "should only create Java thread object once"); 1122 1123 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1124 instanceKlassHandle klass (THREAD, k); 1125 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1126 1127 java_lang_Thread::set_thread(thread_oop(), this); 1128 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1129 set_threadObj(thread_oop()); 1130 1131 JavaValue result(T_VOID); 1132 if (thread_name != NULL) { 1133 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1134 // Thread gets assigned specified name and null target 1135 JavaCalls::call_special(&result, 1136 thread_oop, 1137 klass, 1138 vmSymbols::object_initializer_name(), 1139 vmSymbols::threadgroup_string_void_signature(), 1140 thread_group, // Argument 1 1141 name, // Argument 2 1142 THREAD); 1143 } else { 1144 // Thread gets assigned name "Thread-nnn" and null target 1145 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1146 JavaCalls::call_special(&result, 1147 thread_oop, 1148 klass, 1149 vmSymbols::object_initializer_name(), 1150 vmSymbols::threadgroup_runnable_void_signature(), 1151 thread_group, // Argument 1 1152 Handle(), // Argument 2 1153 THREAD); 1154 } 1155 1156 1157 if (daemon) { 1158 java_lang_Thread::set_daemon(thread_oop()); 1159 } 1160 1161 if (HAS_PENDING_EXCEPTION) { 1162 return; 1163 } 1164 1165 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1166 Handle threadObj(this, this->threadObj()); 1167 1168 JavaCalls::call_special(&result, 1169 thread_group, 1170 group, 1171 vmSymbols::add_method_name(), 1172 vmSymbols::thread_void_signature(), 1173 threadObj, // Arg 1 1174 THREAD); 1175 1176 1177} 1178 1179// NamedThread -- non-JavaThread subclasses with multiple 1180// uniquely named instances should derive from this. 1181NamedThread::NamedThread() : Thread() { 1182 _name = NULL; 1183 _processed_thread = NULL; 1184} 1185 1186NamedThread::~NamedThread() { 1187 if (_name != NULL) { 1188 FREE_C_HEAP_ARRAY(char, _name, mtThread); 1189 _name = NULL; 1190 } 1191} 1192 1193void NamedThread::set_name(const char* format, ...) { 1194 guarantee(_name == NULL, "Only get to set name once."); 1195 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1196 guarantee(_name != NULL, "alloc failure"); 1197 va_list ap; 1198 va_start(ap, format); 1199 jio_vsnprintf(_name, max_name_len, format, ap); 1200 va_end(ap); 1201} 1202 1203void NamedThread::print_on(outputStream* st) const { 1204 st->print("\"%s\" ", name()); 1205 Thread::print_on(st); 1206 st->cr(); 1207} 1208 1209 1210// ======= WatcherThread ======== 1211 1212// The watcher thread exists to simulate timer interrupts. It should 1213// be replaced by an abstraction over whatever native support for 1214// timer interrupts exists on the platform. 1215 1216WatcherThread* WatcherThread::_watcher_thread = NULL; 1217bool WatcherThread::_startable = false; 1218volatile bool WatcherThread::_should_terminate = false; 1219 1220WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1221 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1222 if (os::create_thread(this, os::watcher_thread)) { 1223 _watcher_thread = this; 1224 1225 // Set the watcher thread to the highest OS priority which should not be 1226 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1227 // is created. The only normal thread using this priority is the reference 1228 // handler thread, which runs for very short intervals only. 1229 // If the VMThread's priority is not lower than the WatcherThread profiling 1230 // will be inaccurate. 1231 os::set_priority(this, MaxPriority); 1232 if (!DisableStartThread) { 1233 os::start_thread(this); 1234 } 1235 } 1236} 1237 1238int WatcherThread::sleep() const { 1239 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1240 1241 // remaining will be zero if there are no tasks, 1242 // causing the WatcherThread to sleep until a task is 1243 // enrolled 1244 int remaining = PeriodicTask::time_to_wait(); 1245 int time_slept = 0; 1246 1247 // we expect this to timeout - we only ever get unparked when 1248 // we should terminate or when a new task has been enrolled 1249 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1250 1251 jlong time_before_loop = os::javaTimeNanos(); 1252 1253 for (;;) { 1254 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining); 1255 jlong now = os::javaTimeNanos(); 1256 1257 if (remaining == 0) { 1258 // if we didn't have any tasks we could have waited for a long time 1259 // consider the time_slept zero and reset time_before_loop 1260 time_slept = 0; 1261 time_before_loop = now; 1262 } else { 1263 // need to recalculate since we might have new tasks in _tasks 1264 time_slept = (int) ((now - time_before_loop) / 1000000); 1265 } 1266 1267 // Change to task list or spurious wakeup of some kind 1268 if (timedout || _should_terminate) { 1269 break; 1270 } 1271 1272 remaining = PeriodicTask::time_to_wait(); 1273 if (remaining == 0) { 1274 // Last task was just disenrolled so loop around and wait until 1275 // another task gets enrolled 1276 continue; 1277 } 1278 1279 remaining -= time_slept; 1280 if (remaining <= 0) { 1281 break; 1282 } 1283 } 1284 1285 return time_slept; 1286} 1287 1288void WatcherThread::run() { 1289 assert(this == watcher_thread(), "just checking"); 1290 1291 this->record_stack_base_and_size(); 1292 this->initialize_thread_local_storage(); 1293 this->set_native_thread_name(this->name()); 1294 this->set_active_handles(JNIHandleBlock::allocate_block()); 1295 while (!_should_terminate) { 1296 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1297 assert(watcher_thread() == this, "thread consistency check"); 1298 1299 // Calculate how long it'll be until the next PeriodicTask work 1300 // should be done, and sleep that amount of time. 1301 int time_waited = sleep(); 1302 1303 if (is_error_reported()) { 1304 // A fatal error has happened, the error handler(VMError::report_and_die) 1305 // should abort JVM after creating an error log file. However in some 1306 // rare cases, the error handler itself might deadlock. Here we try to 1307 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1308 // 1309 // This code is in WatcherThread because WatcherThread wakes up 1310 // periodically so the fatal error handler doesn't need to do anything; 1311 // also because the WatcherThread is less likely to crash than other 1312 // threads. 1313 1314 for (;;) { 1315 if (!ShowMessageBoxOnError 1316 && (OnError == NULL || OnError[0] == '\0') 1317 && Arguments::abort_hook() == NULL) { 1318 os::sleep(this, 2 * 60 * 1000, false); 1319 fdStream err(defaultStream::output_fd()); 1320 err.print_raw_cr("# [ timer expired, abort... ]"); 1321 // skip atexit/vm_exit/vm_abort hooks 1322 os::die(); 1323 } 1324 1325 // Wake up 5 seconds later, the fatal handler may reset OnError or 1326 // ShowMessageBoxOnError when it is ready to abort. 1327 os::sleep(this, 5 * 1000, false); 1328 } 1329 } 1330 1331 PeriodicTask::real_time_tick(time_waited); 1332 } 1333 1334 // Signal that it is terminated 1335 { 1336 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1337 _watcher_thread = NULL; 1338 Terminator_lock->notify(); 1339 } 1340 1341 // Thread destructor usually does this.. 1342 ThreadLocalStorage::set_thread(NULL); 1343} 1344 1345void WatcherThread::start() { 1346 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1347 1348 if (watcher_thread() == NULL && _startable) { 1349 _should_terminate = false; 1350 // Create the single instance of WatcherThread 1351 new WatcherThread(); 1352 } 1353} 1354 1355void WatcherThread::make_startable() { 1356 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1357 _startable = true; 1358} 1359 1360void WatcherThread::stop() { 1361 // Get the PeriodicTask_lock if we can. If we cannot, then the 1362 // WatcherThread is using it and we don't want to block on that lock 1363 // here because that might cause a safepoint deadlock depending on 1364 // what the current WatcherThread tasks are doing. 1365 bool have_lock = PeriodicTask_lock->try_lock(); 1366 1367 _should_terminate = true; 1368 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1369 1370 if (have_lock) { 1371 WatcherThread* watcher = watcher_thread(); 1372 if (watcher != NULL) { 1373 // If we managed to get the lock, then we should unpark the 1374 // WatcherThread so that it can see we want it to stop. 1375 watcher->unpark(); 1376 } 1377 1378 PeriodicTask_lock->unlock(); 1379 } 1380 1381 // it is ok to take late safepoints here, if needed 1382 MutexLocker mu(Terminator_lock); 1383 1384 while (watcher_thread() != NULL) { 1385 // This wait should make safepoint checks, wait without a timeout, 1386 // and wait as a suspend-equivalent condition. 1387 // 1388 // Note: If the FlatProfiler is running, then this thread is waiting 1389 // for the WatcherThread to terminate and the WatcherThread, via the 1390 // FlatProfiler task, is waiting for the external suspend request on 1391 // this thread to complete. wait_for_ext_suspend_completion() will 1392 // eventually timeout, but that takes time. Making this wait a 1393 // suspend-equivalent condition solves that timeout problem. 1394 // 1395 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1396 Mutex::_as_suspend_equivalent_flag); 1397 } 1398} 1399 1400void WatcherThread::unpark() { 1401 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() 1402 ? NULL 1403 : PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1404 PeriodicTask_lock->notify(); 1405} 1406 1407void WatcherThread::print_on(outputStream* st) const { 1408 st->print("\"%s\" ", name()); 1409 Thread::print_on(st); 1410 st->cr(); 1411} 1412 1413// ======= JavaThread ======== 1414 1415// A JavaThread is a normal Java thread 1416 1417void JavaThread::initialize() { 1418 // Initialize fields 1419 1420 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids) 1421 set_claimed_par_id(UINT_MAX); 1422 1423 set_saved_exception_pc(NULL); 1424 set_threadObj(NULL); 1425 _anchor.clear(); 1426 set_entry_point(NULL); 1427 set_jni_functions(jni_functions()); 1428 set_callee_target(NULL); 1429 set_vm_result(NULL); 1430 set_vm_result_2(NULL); 1431 set_vframe_array_head(NULL); 1432 set_vframe_array_last(NULL); 1433 set_deferred_locals(NULL); 1434 set_deopt_mark(NULL); 1435 set_deopt_nmethod(NULL); 1436 clear_must_deopt_id(); 1437 set_monitor_chunks(NULL); 1438 set_next(NULL); 1439 set_thread_state(_thread_new); 1440 _terminated = _not_terminated; 1441 _privileged_stack_top = NULL; 1442 _array_for_gc = NULL; 1443 _suspend_equivalent = false; 1444 _in_deopt_handler = 0; 1445 _doing_unsafe_access = false; 1446 _stack_guard_state = stack_guard_unused; 1447 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1448 _exception_pc = 0; 1449 _exception_handler_pc = 0; 1450 _is_method_handle_return = 0; 1451 _jvmti_thread_state= NULL; 1452 _should_post_on_exceptions_flag = JNI_FALSE; 1453 _jvmti_get_loaded_classes_closure = NULL; 1454 _interp_only_mode = 0; 1455 _special_runtime_exit_condition = _no_async_condition; 1456 _pending_async_exception = NULL; 1457 _thread_stat = NULL; 1458 _thread_stat = new ThreadStatistics(); 1459 _blocked_on_compilation = false; 1460 _jni_active_critical = 0; 1461 _pending_jni_exception_check_fn = NULL; 1462 _do_not_unlock_if_synchronized = false; 1463 _cached_monitor_info = NULL; 1464 _parker = Parker::Allocate(this); 1465 1466#ifndef PRODUCT 1467 _jmp_ring_index = 0; 1468 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1469 record_jump(NULL, NULL, NULL, 0); 1470 } 1471#endif // PRODUCT 1472 1473 set_thread_profiler(NULL); 1474 if (FlatProfiler::is_active()) { 1475 // This is where we would decide to either give each thread it's own profiler 1476 // or use one global one from FlatProfiler, 1477 // or up to some count of the number of profiled threads, etc. 1478 ThreadProfiler* pp = new ThreadProfiler(); 1479 pp->engage(); 1480 set_thread_profiler(pp); 1481 } 1482 1483 // Setup safepoint state info for this thread 1484 ThreadSafepointState::create(this); 1485 1486 debug_only(_java_call_counter = 0); 1487 1488 // JVMTI PopFrame support 1489 _popframe_condition = popframe_inactive; 1490 _popframe_preserved_args = NULL; 1491 _popframe_preserved_args_size = 0; 1492 1493 pd_initialize(); 1494} 1495 1496#if INCLUDE_ALL_GCS 1497SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1498DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1499#endif // INCLUDE_ALL_GCS 1500 1501JavaThread::JavaThread(bool is_attaching_via_jni) : 1502 Thread() 1503#if INCLUDE_ALL_GCS 1504 , _satb_mark_queue(&_satb_mark_queue_set), 1505 _dirty_card_queue(&_dirty_card_queue_set) 1506#endif // INCLUDE_ALL_GCS 1507{ 1508 initialize(); 1509 if (is_attaching_via_jni) { 1510 _jni_attach_state = _attaching_via_jni; 1511 } else { 1512 _jni_attach_state = _not_attaching_via_jni; 1513 } 1514 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1515} 1516 1517bool JavaThread::reguard_stack(address cur_sp) { 1518 if (_stack_guard_state != stack_guard_yellow_disabled) { 1519 return true; // Stack already guarded or guard pages not needed. 1520 } 1521 1522 if (register_stack_overflow()) { 1523 // For those architectures which have separate register and 1524 // memory stacks, we must check the register stack to see if 1525 // it has overflowed. 1526 return false; 1527 } 1528 1529 // Java code never executes within the yellow zone: the latter is only 1530 // there to provoke an exception during stack banging. If java code 1531 // is executing there, either StackShadowPages should be larger, or 1532 // some exception code in c1, c2 or the interpreter isn't unwinding 1533 // when it should. 1534 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1535 1536 enable_stack_yellow_zone(); 1537 return true; 1538} 1539 1540bool JavaThread::reguard_stack(void) { 1541 return reguard_stack(os::current_stack_pointer()); 1542} 1543 1544 1545void JavaThread::block_if_vm_exited() { 1546 if (_terminated == _vm_exited) { 1547 // _vm_exited is set at safepoint, and Threads_lock is never released 1548 // we will block here forever 1549 Threads_lock->lock_without_safepoint_check(); 1550 ShouldNotReachHere(); 1551 } 1552} 1553 1554 1555// Remove this ifdef when C1 is ported to the compiler interface. 1556static void compiler_thread_entry(JavaThread* thread, TRAPS); 1557static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1558 1559JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1560 Thread() 1561#if INCLUDE_ALL_GCS 1562 , _satb_mark_queue(&_satb_mark_queue_set), 1563 _dirty_card_queue(&_dirty_card_queue_set) 1564#endif // INCLUDE_ALL_GCS 1565{ 1566 if (TraceThreadEvents) { 1567 tty->print_cr("creating thread %p", this); 1568 } 1569 initialize(); 1570 _jni_attach_state = _not_attaching_via_jni; 1571 set_entry_point(entry_point); 1572 // Create the native thread itself. 1573 // %note runtime_23 1574 os::ThreadType thr_type = os::java_thread; 1575 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1576 os::java_thread; 1577 os::create_thread(this, thr_type, stack_sz); 1578 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1579 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1580 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1581 // the exception consists of creating the exception object & initializing it, initialization 1582 // will leave the VM via a JavaCall and then all locks must be unlocked). 1583 // 1584 // The thread is still suspended when we reach here. Thread must be explicit started 1585 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1586 // by calling Threads:add. The reason why this is not done here, is because the thread 1587 // object must be fully initialized (take a look at JVM_Start) 1588} 1589 1590JavaThread::~JavaThread() { 1591 if (TraceThreadEvents) { 1592 tty->print_cr("terminate thread %p", this); 1593 } 1594 1595 // JSR166 -- return the parker to the free list 1596 Parker::Release(_parker); 1597 _parker = NULL; 1598 1599 // Free any remaining previous UnrollBlock 1600 vframeArray* old_array = vframe_array_last(); 1601 1602 if (old_array != NULL) { 1603 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1604 old_array->set_unroll_block(NULL); 1605 delete old_info; 1606 delete old_array; 1607 } 1608 1609 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1610 if (deferred != NULL) { 1611 // This can only happen if thread is destroyed before deoptimization occurs. 1612 assert(deferred->length() != 0, "empty array!"); 1613 do { 1614 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1615 deferred->remove_at(0); 1616 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1617 delete dlv; 1618 } while (deferred->length() != 0); 1619 delete deferred; 1620 } 1621 1622 // All Java related clean up happens in exit 1623 ThreadSafepointState::destroy(this); 1624 if (_thread_profiler != NULL) delete _thread_profiler; 1625 if (_thread_stat != NULL) delete _thread_stat; 1626} 1627 1628 1629// The first routine called by a new Java thread 1630void JavaThread::run() { 1631 // initialize thread-local alloc buffer related fields 1632 this->initialize_tlab(); 1633 1634 // used to test validity of stack trace backs 1635 this->record_base_of_stack_pointer(); 1636 1637 // Record real stack base and size. 1638 this->record_stack_base_and_size(); 1639 1640 // Initialize thread local storage; set before calling MutexLocker 1641 this->initialize_thread_local_storage(); 1642 1643 this->create_stack_guard_pages(); 1644 1645 this->cache_global_variables(); 1646 1647 // Thread is now sufficient initialized to be handled by the safepoint code as being 1648 // in the VM. Change thread state from _thread_new to _thread_in_vm 1649 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1650 1651 assert(JavaThread::current() == this, "sanity check"); 1652 assert(!Thread::current()->owns_locks(), "sanity check"); 1653 1654 DTRACE_THREAD_PROBE(start, this); 1655 1656 // This operation might block. We call that after all safepoint checks for a new thread has 1657 // been completed. 1658 this->set_active_handles(JNIHandleBlock::allocate_block()); 1659 1660 if (JvmtiExport::should_post_thread_life()) { 1661 JvmtiExport::post_thread_start(this); 1662 } 1663 1664 EventThreadStart event; 1665 if (event.should_commit()) { 1666 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1667 event.commit(); 1668 } 1669 1670 // We call another function to do the rest so we are sure that the stack addresses used 1671 // from there will be lower than the stack base just computed 1672 thread_main_inner(); 1673 1674 // Note, thread is no longer valid at this point! 1675} 1676 1677 1678void JavaThread::thread_main_inner() { 1679 assert(JavaThread::current() == this, "sanity check"); 1680 assert(this->threadObj() != NULL, "just checking"); 1681 1682 // Execute thread entry point unless this thread has a pending exception 1683 // or has been stopped before starting. 1684 // Note: Due to JVM_StopThread we can have pending exceptions already! 1685 if (!this->has_pending_exception() && 1686 !java_lang_Thread::is_stillborn(this->threadObj())) { 1687 { 1688 ResourceMark rm(this); 1689 this->set_native_thread_name(this->get_thread_name()); 1690 } 1691 HandleMark hm(this); 1692 this->entry_point()(this, this); 1693 } 1694 1695 DTRACE_THREAD_PROBE(stop, this); 1696 1697 this->exit(false); 1698 delete this; 1699} 1700 1701 1702static void ensure_join(JavaThread* thread) { 1703 // We do not need to grap the Threads_lock, since we are operating on ourself. 1704 Handle threadObj(thread, thread->threadObj()); 1705 assert(threadObj.not_null(), "java thread object must exist"); 1706 ObjectLocker lock(threadObj, thread); 1707 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1708 thread->clear_pending_exception(); 1709 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1710 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1711 // Clear the native thread instance - this makes isAlive return false and allows the join() 1712 // to complete once we've done the notify_all below 1713 java_lang_Thread::set_thread(threadObj(), NULL); 1714 lock.notify_all(thread); 1715 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1716 thread->clear_pending_exception(); 1717} 1718 1719 1720// For any new cleanup additions, please check to see if they need to be applied to 1721// cleanup_failed_attach_current_thread as well. 1722void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1723 assert(this == JavaThread::current(), "thread consistency check"); 1724 1725 HandleMark hm(this); 1726 Handle uncaught_exception(this, this->pending_exception()); 1727 this->clear_pending_exception(); 1728 Handle threadObj(this, this->threadObj()); 1729 assert(threadObj.not_null(), "Java thread object should be created"); 1730 1731 if (get_thread_profiler() != NULL) { 1732 get_thread_profiler()->disengage(); 1733 ResourceMark rm; 1734 get_thread_profiler()->print(get_thread_name()); 1735 } 1736 1737 1738 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1739 { 1740 EXCEPTION_MARK; 1741 1742 CLEAR_PENDING_EXCEPTION; 1743 } 1744 if (!destroy_vm) { 1745 if (uncaught_exception.not_null()) { 1746 EXCEPTION_MARK; 1747 // Call method Thread.dispatchUncaughtException(). 1748 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1749 JavaValue result(T_VOID); 1750 JavaCalls::call_virtual(&result, 1751 threadObj, thread_klass, 1752 vmSymbols::dispatchUncaughtException_name(), 1753 vmSymbols::throwable_void_signature(), 1754 uncaught_exception, 1755 THREAD); 1756 if (HAS_PENDING_EXCEPTION) { 1757 ResourceMark rm(this); 1758 jio_fprintf(defaultStream::error_stream(), 1759 "\nException: %s thrown from the UncaughtExceptionHandler" 1760 " in thread \"%s\"\n", 1761 pending_exception()->klass()->external_name(), 1762 get_thread_name()); 1763 CLEAR_PENDING_EXCEPTION; 1764 } 1765 } 1766 1767 // Called before the java thread exit since we want to read info 1768 // from java_lang_Thread object 1769 EventThreadEnd event; 1770 if (event.should_commit()) { 1771 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1772 event.commit(); 1773 } 1774 1775 // Call after last event on thread 1776 EVENT_THREAD_EXIT(this); 1777 1778 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1779 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1780 // is deprecated anyhow. 1781 if (!is_Compiler_thread()) { 1782 int count = 3; 1783 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1784 EXCEPTION_MARK; 1785 JavaValue result(T_VOID); 1786 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1787 JavaCalls::call_virtual(&result, 1788 threadObj, thread_klass, 1789 vmSymbols::exit_method_name(), 1790 vmSymbols::void_method_signature(), 1791 THREAD); 1792 CLEAR_PENDING_EXCEPTION; 1793 } 1794 } 1795 // notify JVMTI 1796 if (JvmtiExport::should_post_thread_life()) { 1797 JvmtiExport::post_thread_end(this); 1798 } 1799 1800 // We have notified the agents that we are exiting, before we go on, 1801 // we must check for a pending external suspend request and honor it 1802 // in order to not surprise the thread that made the suspend request. 1803 while (true) { 1804 { 1805 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1806 if (!is_external_suspend()) { 1807 set_terminated(_thread_exiting); 1808 ThreadService::current_thread_exiting(this); 1809 break; 1810 } 1811 // Implied else: 1812 // Things get a little tricky here. We have a pending external 1813 // suspend request, but we are holding the SR_lock so we 1814 // can't just self-suspend. So we temporarily drop the lock 1815 // and then self-suspend. 1816 } 1817 1818 ThreadBlockInVM tbivm(this); 1819 java_suspend_self(); 1820 1821 // We're done with this suspend request, but we have to loop around 1822 // and check again. Eventually we will get SR_lock without a pending 1823 // external suspend request and will be able to mark ourselves as 1824 // exiting. 1825 } 1826 // no more external suspends are allowed at this point 1827 } else { 1828 // before_exit() has already posted JVMTI THREAD_END events 1829 } 1830 1831 // Notify waiters on thread object. This has to be done after exit() is called 1832 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1833 // group should have the destroyed bit set before waiters are notified). 1834 ensure_join(this); 1835 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1836 1837 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1838 // held by this thread must be released. A detach operation must only 1839 // get here if there are no Java frames on the stack. Therefore, any 1840 // owned monitors at this point MUST be JNI-acquired monitors which are 1841 // pre-inflated and in the monitor cache. 1842 // 1843 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1844 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1845 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1846 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1847 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1848 } 1849 1850 // These things needs to be done while we are still a Java Thread. Make sure that thread 1851 // is in a consistent state, in case GC happens 1852 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1853 1854 if (active_handles() != NULL) { 1855 JNIHandleBlock* block = active_handles(); 1856 set_active_handles(NULL); 1857 JNIHandleBlock::release_block(block); 1858 } 1859 1860 if (free_handle_block() != NULL) { 1861 JNIHandleBlock* block = free_handle_block(); 1862 set_free_handle_block(NULL); 1863 JNIHandleBlock::release_block(block); 1864 } 1865 1866 // These have to be removed while this is still a valid thread. 1867 remove_stack_guard_pages(); 1868 1869 if (UseTLAB) { 1870 tlab().make_parsable(true); // retire TLAB 1871 } 1872 1873 if (JvmtiEnv::environments_might_exist()) { 1874 JvmtiExport::cleanup_thread(this); 1875 } 1876 1877 // We must flush any deferred card marks before removing a thread from 1878 // the list of active threads. 1879 Universe::heap()->flush_deferred_store_barrier(this); 1880 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1881 1882#if INCLUDE_ALL_GCS 1883 // We must flush the G1-related buffers before removing a thread 1884 // from the list of active threads. We must do this after any deferred 1885 // card marks have been flushed (above) so that any entries that are 1886 // added to the thread's dirty card queue as a result are not lost. 1887 if (UseG1GC) { 1888 flush_barrier_queues(); 1889 } 1890#endif // INCLUDE_ALL_GCS 1891 1892 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1893 Threads::remove(this); 1894} 1895 1896#if INCLUDE_ALL_GCS 1897// Flush G1-related queues. 1898void JavaThread::flush_barrier_queues() { 1899 satb_mark_queue().flush(); 1900 dirty_card_queue().flush(); 1901} 1902 1903void JavaThread::initialize_queues() { 1904 assert(!SafepointSynchronize::is_at_safepoint(), 1905 "we should not be at a safepoint"); 1906 1907 ObjPtrQueue& satb_queue = satb_mark_queue(); 1908 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1909 // The SATB queue should have been constructed with its active 1910 // field set to false. 1911 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1912 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1913 // If we are creating the thread during a marking cycle, we should 1914 // set the active field of the SATB queue to true. 1915 if (satb_queue_set.is_active()) { 1916 satb_queue.set_active(true); 1917 } 1918 1919 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1920 // The dirty card queue should have been constructed with its 1921 // active field set to true. 1922 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1923} 1924#endif // INCLUDE_ALL_GCS 1925 1926void JavaThread::cleanup_failed_attach_current_thread() { 1927 if (get_thread_profiler() != NULL) { 1928 get_thread_profiler()->disengage(); 1929 ResourceMark rm; 1930 get_thread_profiler()->print(get_thread_name()); 1931 } 1932 1933 if (active_handles() != NULL) { 1934 JNIHandleBlock* block = active_handles(); 1935 set_active_handles(NULL); 1936 JNIHandleBlock::release_block(block); 1937 } 1938 1939 if (free_handle_block() != NULL) { 1940 JNIHandleBlock* block = free_handle_block(); 1941 set_free_handle_block(NULL); 1942 JNIHandleBlock::release_block(block); 1943 } 1944 1945 // These have to be removed while this is still a valid thread. 1946 remove_stack_guard_pages(); 1947 1948 if (UseTLAB) { 1949 tlab().make_parsable(true); // retire TLAB, if any 1950 } 1951 1952#if INCLUDE_ALL_GCS 1953 if (UseG1GC) { 1954 flush_barrier_queues(); 1955 } 1956#endif // INCLUDE_ALL_GCS 1957 1958 Threads::remove(this); 1959 delete this; 1960} 1961 1962 1963 1964 1965JavaThread* JavaThread::active() { 1966 Thread* thread = ThreadLocalStorage::thread(); 1967 assert(thread != NULL, "just checking"); 1968 if (thread->is_Java_thread()) { 1969 return (JavaThread*) thread; 1970 } else { 1971 assert(thread->is_VM_thread(), "this must be a vm thread"); 1972 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1973 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1974 assert(ret->is_Java_thread(), "must be a Java thread"); 1975 return ret; 1976 } 1977} 1978 1979bool JavaThread::is_lock_owned(address adr) const { 1980 if (Thread::is_lock_owned(adr)) return true; 1981 1982 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1983 if (chunk->contains(adr)) return true; 1984 } 1985 1986 return false; 1987} 1988 1989 1990void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1991 chunk->set_next(monitor_chunks()); 1992 set_monitor_chunks(chunk); 1993} 1994 1995void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1996 guarantee(monitor_chunks() != NULL, "must be non empty"); 1997 if (monitor_chunks() == chunk) { 1998 set_monitor_chunks(chunk->next()); 1999 } else { 2000 MonitorChunk* prev = monitor_chunks(); 2001 while (prev->next() != chunk) prev = prev->next(); 2002 prev->set_next(chunk->next()); 2003 } 2004} 2005 2006// JVM support. 2007 2008// Note: this function shouldn't block if it's called in 2009// _thread_in_native_trans state (such as from 2010// check_special_condition_for_native_trans()). 2011void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2012 2013 if (has_last_Java_frame() && has_async_condition()) { 2014 // If we are at a polling page safepoint (not a poll return) 2015 // then we must defer async exception because live registers 2016 // will be clobbered by the exception path. Poll return is 2017 // ok because the call we a returning from already collides 2018 // with exception handling registers and so there is no issue. 2019 // (The exception handling path kills call result registers but 2020 // this is ok since the exception kills the result anyway). 2021 2022 if (is_at_poll_safepoint()) { 2023 // if the code we are returning to has deoptimized we must defer 2024 // the exception otherwise live registers get clobbered on the 2025 // exception path before deoptimization is able to retrieve them. 2026 // 2027 RegisterMap map(this, false); 2028 frame caller_fr = last_frame().sender(&map); 2029 assert(caller_fr.is_compiled_frame(), "what?"); 2030 if (caller_fr.is_deoptimized_frame()) { 2031 if (TraceExceptions) { 2032 ResourceMark rm; 2033 tty->print_cr("deferred async exception at compiled safepoint"); 2034 } 2035 return; 2036 } 2037 } 2038 } 2039 2040 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2041 if (condition == _no_async_condition) { 2042 // Conditions have changed since has_special_runtime_exit_condition() 2043 // was called: 2044 // - if we were here only because of an external suspend request, 2045 // then that was taken care of above (or cancelled) so we are done 2046 // - if we were here because of another async request, then it has 2047 // been cleared between the has_special_runtime_exit_condition() 2048 // and now so again we are done 2049 return; 2050 } 2051 2052 // Check for pending async. exception 2053 if (_pending_async_exception != NULL) { 2054 // Only overwrite an already pending exception, if it is not a threadDeath. 2055 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2056 2057 // We cannot call Exceptions::_throw(...) here because we cannot block 2058 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2059 2060 if (TraceExceptions) { 2061 ResourceMark rm; 2062 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 2063 if (has_last_Java_frame()) { 2064 frame f = last_frame(); 2065 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 2066 } 2067 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2068 } 2069 _pending_async_exception = NULL; 2070 clear_has_async_exception(); 2071 } 2072 } 2073 2074 if (check_unsafe_error && 2075 condition == _async_unsafe_access_error && !has_pending_exception()) { 2076 condition = _no_async_condition; // done 2077 switch (thread_state()) { 2078 case _thread_in_vm: { 2079 JavaThread* THREAD = this; 2080 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2081 } 2082 case _thread_in_native: { 2083 ThreadInVMfromNative tiv(this); 2084 JavaThread* THREAD = this; 2085 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2086 } 2087 case _thread_in_Java: { 2088 ThreadInVMfromJava tiv(this); 2089 JavaThread* THREAD = this; 2090 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2091 } 2092 default: 2093 ShouldNotReachHere(); 2094 } 2095 } 2096 2097 assert(condition == _no_async_condition || has_pending_exception() || 2098 (!check_unsafe_error && condition == _async_unsafe_access_error), 2099 "must have handled the async condition, if no exception"); 2100} 2101 2102void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2103 // 2104 // Check for pending external suspend. Internal suspend requests do 2105 // not use handle_special_runtime_exit_condition(). 2106 // If JNIEnv proxies are allowed, don't self-suspend if the target 2107 // thread is not the current thread. In older versions of jdbx, jdbx 2108 // threads could call into the VM with another thread's JNIEnv so we 2109 // can be here operating on behalf of a suspended thread (4432884). 2110 bool do_self_suspend = is_external_suspend_with_lock(); 2111 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2112 // 2113 // Because thread is external suspended the safepoint code will count 2114 // thread as at a safepoint. This can be odd because we can be here 2115 // as _thread_in_Java which would normally transition to _thread_blocked 2116 // at a safepoint. We would like to mark the thread as _thread_blocked 2117 // before calling java_suspend_self like all other callers of it but 2118 // we must then observe proper safepoint protocol. (We can't leave 2119 // _thread_blocked with a safepoint in progress). However we can be 2120 // here as _thread_in_native_trans so we can't use a normal transition 2121 // constructor/destructor pair because they assert on that type of 2122 // transition. We could do something like: 2123 // 2124 // JavaThreadState state = thread_state(); 2125 // set_thread_state(_thread_in_vm); 2126 // { 2127 // ThreadBlockInVM tbivm(this); 2128 // java_suspend_self() 2129 // } 2130 // set_thread_state(_thread_in_vm_trans); 2131 // if (safepoint) block; 2132 // set_thread_state(state); 2133 // 2134 // but that is pretty messy. Instead we just go with the way the 2135 // code has worked before and note that this is the only path to 2136 // java_suspend_self that doesn't put the thread in _thread_blocked 2137 // mode. 2138 2139 frame_anchor()->make_walkable(this); 2140 java_suspend_self(); 2141 2142 // We might be here for reasons in addition to the self-suspend request 2143 // so check for other async requests. 2144 } 2145 2146 if (check_asyncs) { 2147 check_and_handle_async_exceptions(); 2148 } 2149} 2150 2151void JavaThread::send_thread_stop(oop java_throwable) { 2152 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2153 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2154 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2155 2156 // Do not throw asynchronous exceptions against the compiler thread 2157 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2158 if (is_Compiler_thread()) return; 2159 2160 { 2161 // Actually throw the Throwable against the target Thread - however 2162 // only if there is no thread death exception installed already. 2163 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2164 // If the topmost frame is a runtime stub, then we are calling into 2165 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2166 // must deoptimize the caller before continuing, as the compiled exception handler table 2167 // may not be valid 2168 if (has_last_Java_frame()) { 2169 frame f = last_frame(); 2170 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2171 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2172 RegisterMap reg_map(this, UseBiasedLocking); 2173 frame compiled_frame = f.sender(®_map); 2174 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2175 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2176 } 2177 } 2178 } 2179 2180 // Set async. pending exception in thread. 2181 set_pending_async_exception(java_throwable); 2182 2183 if (TraceExceptions) { 2184 ResourceMark rm; 2185 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2186 } 2187 // for AbortVMOnException flag 2188 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name())); 2189 } 2190 } 2191 2192 2193 // Interrupt thread so it will wake up from a potential wait() 2194 Thread::interrupt(this); 2195} 2196 2197// External suspension mechanism. 2198// 2199// Tell the VM to suspend a thread when ever it knows that it does not hold on 2200// to any VM_locks and it is at a transition 2201// Self-suspension will happen on the transition out of the vm. 2202// Catch "this" coming in from JNIEnv pointers when the thread has been freed 2203// 2204// Guarantees on return: 2205// + Target thread will not execute any new bytecode (that's why we need to 2206// force a safepoint) 2207// + Target thread will not enter any new monitors 2208// 2209void JavaThread::java_suspend() { 2210 { MutexLocker mu(Threads_lock); 2211 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2212 return; 2213 } 2214 } 2215 2216 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2217 if (!is_external_suspend()) { 2218 // a racing resume has cancelled us; bail out now 2219 return; 2220 } 2221 2222 // suspend is done 2223 uint32_t debug_bits = 0; 2224 // Warning: is_ext_suspend_completed() may temporarily drop the 2225 // SR_lock to allow the thread to reach a stable thread state if 2226 // it is currently in a transient thread state. 2227 if (is_ext_suspend_completed(false /* !called_by_wait */, 2228 SuspendRetryDelay, &debug_bits)) { 2229 return; 2230 } 2231 } 2232 2233 VM_ForceSafepoint vm_suspend; 2234 VMThread::execute(&vm_suspend); 2235} 2236 2237// Part II of external suspension. 2238// A JavaThread self suspends when it detects a pending external suspend 2239// request. This is usually on transitions. It is also done in places 2240// where continuing to the next transition would surprise the caller, 2241// e.g., monitor entry. 2242// 2243// Returns the number of times that the thread self-suspended. 2244// 2245// Note: DO NOT call java_suspend_self() when you just want to block current 2246// thread. java_suspend_self() is the second stage of cooperative 2247// suspension for external suspend requests and should only be used 2248// to complete an external suspend request. 2249// 2250int JavaThread::java_suspend_self() { 2251 int ret = 0; 2252 2253 // we are in the process of exiting so don't suspend 2254 if (is_exiting()) { 2255 clear_external_suspend(); 2256 return ret; 2257 } 2258 2259 assert(_anchor.walkable() || 2260 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2261 "must have walkable stack"); 2262 2263 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2264 2265 assert(!this->is_ext_suspended(), 2266 "a thread trying to self-suspend should not already be suspended"); 2267 2268 if (this->is_suspend_equivalent()) { 2269 // If we are self-suspending as a result of the lifting of a 2270 // suspend equivalent condition, then the suspend_equivalent 2271 // flag is not cleared until we set the ext_suspended flag so 2272 // that wait_for_ext_suspend_completion() returns consistent 2273 // results. 2274 this->clear_suspend_equivalent(); 2275 } 2276 2277 // A racing resume may have cancelled us before we grabbed SR_lock 2278 // above. Or another external suspend request could be waiting for us 2279 // by the time we return from SR_lock()->wait(). The thread 2280 // that requested the suspension may already be trying to walk our 2281 // stack and if we return now, we can change the stack out from under 2282 // it. This would be a "bad thing (TM)" and cause the stack walker 2283 // to crash. We stay self-suspended until there are no more pending 2284 // external suspend requests. 2285 while (is_external_suspend()) { 2286 ret++; 2287 this->set_ext_suspended(); 2288 2289 // _ext_suspended flag is cleared by java_resume() 2290 while (is_ext_suspended()) { 2291 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2292 } 2293 } 2294 2295 return ret; 2296} 2297 2298#ifdef ASSERT 2299// verify the JavaThread has not yet been published in the Threads::list, and 2300// hence doesn't need protection from concurrent access at this stage 2301void JavaThread::verify_not_published() { 2302 if (!Threads_lock->owned_by_self()) { 2303 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2304 assert(!Threads::includes(this), 2305 "java thread shouldn't have been published yet!"); 2306 } else { 2307 assert(!Threads::includes(this), 2308 "java thread shouldn't have been published yet!"); 2309 } 2310} 2311#endif 2312 2313// Slow path when the native==>VM/Java barriers detect a safepoint is in 2314// progress or when _suspend_flags is non-zero. 2315// Current thread needs to self-suspend if there is a suspend request and/or 2316// block if a safepoint is in progress. 2317// Async exception ISN'T checked. 2318// Note only the ThreadInVMfromNative transition can call this function 2319// directly and when thread state is _thread_in_native_trans 2320void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2321 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2322 2323 JavaThread *curJT = JavaThread::current(); 2324 bool do_self_suspend = thread->is_external_suspend(); 2325 2326 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2327 2328 // If JNIEnv proxies are allowed, don't self-suspend if the target 2329 // thread is not the current thread. In older versions of jdbx, jdbx 2330 // threads could call into the VM with another thread's JNIEnv so we 2331 // can be here operating on behalf of a suspended thread (4432884). 2332 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2333 JavaThreadState state = thread->thread_state(); 2334 2335 // We mark this thread_blocked state as a suspend-equivalent so 2336 // that a caller to is_ext_suspend_completed() won't be confused. 2337 // The suspend-equivalent state is cleared by java_suspend_self(). 2338 thread->set_suspend_equivalent(); 2339 2340 // If the safepoint code sees the _thread_in_native_trans state, it will 2341 // wait until the thread changes to other thread state. There is no 2342 // guarantee on how soon we can obtain the SR_lock and complete the 2343 // self-suspend request. It would be a bad idea to let safepoint wait for 2344 // too long. Temporarily change the state to _thread_blocked to 2345 // let the VM thread know that this thread is ready for GC. The problem 2346 // of changing thread state is that safepoint could happen just after 2347 // java_suspend_self() returns after being resumed, and VM thread will 2348 // see the _thread_blocked state. We must check for safepoint 2349 // after restoring the state and make sure we won't leave while a safepoint 2350 // is in progress. 2351 thread->set_thread_state(_thread_blocked); 2352 thread->java_suspend_self(); 2353 thread->set_thread_state(state); 2354 // Make sure new state is seen by VM thread 2355 if (os::is_MP()) { 2356 if (UseMembar) { 2357 // Force a fence between the write above and read below 2358 OrderAccess::fence(); 2359 } else { 2360 // Must use this rather than serialization page in particular on Windows 2361 InterfaceSupport::serialize_memory(thread); 2362 } 2363 } 2364 } 2365 2366 if (SafepointSynchronize::do_call_back()) { 2367 // If we are safepointing, then block the caller which may not be 2368 // the same as the target thread (see above). 2369 SafepointSynchronize::block(curJT); 2370 } 2371 2372 if (thread->is_deopt_suspend()) { 2373 thread->clear_deopt_suspend(); 2374 RegisterMap map(thread, false); 2375 frame f = thread->last_frame(); 2376 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2377 f = f.sender(&map); 2378 } 2379 if (f.id() == thread->must_deopt_id()) { 2380 thread->clear_must_deopt_id(); 2381 f.deoptimize(thread); 2382 } else { 2383 fatal("missed deoptimization!"); 2384 } 2385 } 2386} 2387 2388// Slow path when the native==>VM/Java barriers detect a safepoint is in 2389// progress or when _suspend_flags is non-zero. 2390// Current thread needs to self-suspend if there is a suspend request and/or 2391// block if a safepoint is in progress. 2392// Also check for pending async exception (not including unsafe access error). 2393// Note only the native==>VM/Java barriers can call this function and when 2394// thread state is _thread_in_native_trans. 2395void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2396 check_safepoint_and_suspend_for_native_trans(thread); 2397 2398 if (thread->has_async_exception()) { 2399 // We are in _thread_in_native_trans state, don't handle unsafe 2400 // access error since that may block. 2401 thread->check_and_handle_async_exceptions(false); 2402 } 2403} 2404 2405// This is a variant of the normal 2406// check_special_condition_for_native_trans with slightly different 2407// semantics for use by critical native wrappers. It does all the 2408// normal checks but also performs the transition back into 2409// thread_in_Java state. This is required so that critical natives 2410// can potentially block and perform a GC if they are the last thread 2411// exiting the GC_locker. 2412void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2413 check_special_condition_for_native_trans(thread); 2414 2415 // Finish the transition 2416 thread->set_thread_state(_thread_in_Java); 2417 2418 if (thread->do_critical_native_unlock()) { 2419 ThreadInVMfromJavaNoAsyncException tiv(thread); 2420 GC_locker::unlock_critical(thread); 2421 thread->clear_critical_native_unlock(); 2422 } 2423} 2424 2425// We need to guarantee the Threads_lock here, since resumes are not 2426// allowed during safepoint synchronization 2427// Can only resume from an external suspension 2428void JavaThread::java_resume() { 2429 assert_locked_or_safepoint(Threads_lock); 2430 2431 // Sanity check: thread is gone, has started exiting or the thread 2432 // was not externally suspended. 2433 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2434 return; 2435 } 2436 2437 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2438 2439 clear_external_suspend(); 2440 2441 if (is_ext_suspended()) { 2442 clear_ext_suspended(); 2443 SR_lock()->notify_all(); 2444 } 2445} 2446 2447void JavaThread::create_stack_guard_pages() { 2448 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2449 address low_addr = stack_base() - stack_size(); 2450 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2451 2452 int allocate = os::allocate_stack_guard_pages(); 2453 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2454 2455 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2456 warning("Attempt to allocate stack guard pages failed."); 2457 return; 2458 } 2459 2460 if (os::guard_memory((char *) low_addr, len)) { 2461 _stack_guard_state = stack_guard_enabled; 2462 } else { 2463 warning("Attempt to protect stack guard pages failed."); 2464 if (os::uncommit_memory((char *) low_addr, len)) { 2465 warning("Attempt to deallocate stack guard pages failed."); 2466 } 2467 } 2468} 2469 2470void JavaThread::remove_stack_guard_pages() { 2471 assert(Thread::current() == this, "from different thread"); 2472 if (_stack_guard_state == stack_guard_unused) return; 2473 address low_addr = stack_base() - stack_size(); 2474 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2475 2476 if (os::allocate_stack_guard_pages()) { 2477 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2478 _stack_guard_state = stack_guard_unused; 2479 } else { 2480 warning("Attempt to deallocate stack guard pages failed."); 2481 } 2482 } else { 2483 if (_stack_guard_state == stack_guard_unused) return; 2484 if (os::unguard_memory((char *) low_addr, len)) { 2485 _stack_guard_state = stack_guard_unused; 2486 } else { 2487 warning("Attempt to unprotect stack guard pages failed."); 2488 } 2489 } 2490} 2491 2492void JavaThread::enable_stack_yellow_zone() { 2493 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2494 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2495 2496 // The base notation is from the stacks point of view, growing downward. 2497 // We need to adjust it to work correctly with guard_memory() 2498 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2499 2500 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2501 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2502 2503 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2504 _stack_guard_state = stack_guard_enabled; 2505 } else { 2506 warning("Attempt to guard stack yellow zone failed."); 2507 } 2508 enable_register_stack_guard(); 2509} 2510 2511void JavaThread::disable_stack_yellow_zone() { 2512 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2513 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2514 2515 // Simply return if called for a thread that does not use guard pages. 2516 if (_stack_guard_state == stack_guard_unused) return; 2517 2518 // The base notation is from the stacks point of view, growing downward. 2519 // We need to adjust it to work correctly with guard_memory() 2520 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2521 2522 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2523 _stack_guard_state = stack_guard_yellow_disabled; 2524 } else { 2525 warning("Attempt to unguard stack yellow zone failed."); 2526 } 2527 disable_register_stack_guard(); 2528} 2529 2530void JavaThread::enable_stack_red_zone() { 2531 // The base notation is from the stacks point of view, growing downward. 2532 // We need to adjust it to work correctly with guard_memory() 2533 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2534 address base = stack_red_zone_base() - stack_red_zone_size(); 2535 2536 guarantee(base < stack_base(), "Error calculating stack red zone"); 2537 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2538 2539 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2540 warning("Attempt to guard stack red zone failed."); 2541 } 2542} 2543 2544void JavaThread::disable_stack_red_zone() { 2545 // The base notation is from the stacks point of view, growing downward. 2546 // We need to adjust it to work correctly with guard_memory() 2547 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2548 address base = stack_red_zone_base() - stack_red_zone_size(); 2549 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2550 warning("Attempt to unguard stack red zone failed."); 2551 } 2552} 2553 2554void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2555 // ignore is there is no stack 2556 if (!has_last_Java_frame()) return; 2557 // traverse the stack frames. Starts from top frame. 2558 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2559 frame* fr = fst.current(); 2560 f(fr, fst.register_map()); 2561 } 2562} 2563 2564 2565#ifndef PRODUCT 2566// Deoptimization 2567// Function for testing deoptimization 2568void JavaThread::deoptimize() { 2569 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2570 StackFrameStream fst(this, UseBiasedLocking); 2571 bool deopt = false; // Dump stack only if a deopt actually happens. 2572 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2573 // Iterate over all frames in the thread and deoptimize 2574 for (; !fst.is_done(); fst.next()) { 2575 if (fst.current()->can_be_deoptimized()) { 2576 2577 if (only_at) { 2578 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2579 // consists of comma or carriage return separated numbers so 2580 // search for the current bci in that string. 2581 address pc = fst.current()->pc(); 2582 nmethod* nm = (nmethod*) fst.current()->cb(); 2583 ScopeDesc* sd = nm->scope_desc_at(pc); 2584 char buffer[8]; 2585 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2586 size_t len = strlen(buffer); 2587 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2588 while (found != NULL) { 2589 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2590 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2591 // Check that the bci found is bracketed by terminators. 2592 break; 2593 } 2594 found = strstr(found + 1, buffer); 2595 } 2596 if (!found) { 2597 continue; 2598 } 2599 } 2600 2601 if (DebugDeoptimization && !deopt) { 2602 deopt = true; // One-time only print before deopt 2603 tty->print_cr("[BEFORE Deoptimization]"); 2604 trace_frames(); 2605 trace_stack(); 2606 } 2607 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2608 } 2609 } 2610 2611 if (DebugDeoptimization && deopt) { 2612 tty->print_cr("[AFTER Deoptimization]"); 2613 trace_frames(); 2614 } 2615} 2616 2617 2618// Make zombies 2619void JavaThread::make_zombies() { 2620 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2621 if (fst.current()->can_be_deoptimized()) { 2622 // it is a Java nmethod 2623 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2624 nm->make_not_entrant(); 2625 } 2626 } 2627} 2628#endif // PRODUCT 2629 2630 2631void JavaThread::deoptimized_wrt_marked_nmethods() { 2632 if (!has_last_Java_frame()) return; 2633 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2634 StackFrameStream fst(this, UseBiasedLocking); 2635 for (; !fst.is_done(); fst.next()) { 2636 if (fst.current()->should_be_deoptimized()) { 2637 if (LogCompilation && xtty != NULL) { 2638 nmethod* nm = fst.current()->cb()->as_nmethod_or_null(); 2639 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'", 2640 this->name(), nm != NULL ? nm->compile_id() : -1); 2641 } 2642 2643 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2644 } 2645 } 2646} 2647 2648 2649// If the caller is a NamedThread, then remember, in the current scope, 2650// the given JavaThread in its _processed_thread field. 2651class RememberProcessedThread: public StackObj { 2652 NamedThread* _cur_thr; 2653 public: 2654 RememberProcessedThread(JavaThread* jthr) { 2655 Thread* thread = Thread::current(); 2656 if (thread->is_Named_thread()) { 2657 _cur_thr = (NamedThread *)thread; 2658 _cur_thr->set_processed_thread(jthr); 2659 } else { 2660 _cur_thr = NULL; 2661 } 2662 } 2663 2664 ~RememberProcessedThread() { 2665 if (_cur_thr) { 2666 _cur_thr->set_processed_thread(NULL); 2667 } 2668 } 2669}; 2670 2671void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2672 // Verify that the deferred card marks have been flushed. 2673 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2674 2675 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2676 // since there may be more than one thread using each ThreadProfiler. 2677 2678 // Traverse the GCHandles 2679 Thread::oops_do(f, cld_f, cf); 2680 2681 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2682 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2683 2684 if (has_last_Java_frame()) { 2685 // Record JavaThread to GC thread 2686 RememberProcessedThread rpt(this); 2687 2688 // Traverse the privileged stack 2689 if (_privileged_stack_top != NULL) { 2690 _privileged_stack_top->oops_do(f); 2691 } 2692 2693 // traverse the registered growable array 2694 if (_array_for_gc != NULL) { 2695 for (int index = 0; index < _array_for_gc->length(); index++) { 2696 f->do_oop(_array_for_gc->adr_at(index)); 2697 } 2698 } 2699 2700 // Traverse the monitor chunks 2701 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2702 chunk->oops_do(f); 2703 } 2704 2705 // Traverse the execution stack 2706 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2707 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2708 } 2709 } 2710 2711 // callee_target is never live across a gc point so NULL it here should 2712 // it still contain a methdOop. 2713 2714 set_callee_target(NULL); 2715 2716 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2717 // If we have deferred set_locals there might be oops waiting to be 2718 // written 2719 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2720 if (list != NULL) { 2721 for (int i = 0; i < list->length(); i++) { 2722 list->at(i)->oops_do(f); 2723 } 2724 } 2725 2726 // Traverse instance variables at the end since the GC may be moving things 2727 // around using this function 2728 f->do_oop((oop*) &_threadObj); 2729 f->do_oop((oop*) &_vm_result); 2730 f->do_oop((oop*) &_exception_oop); 2731 f->do_oop((oop*) &_pending_async_exception); 2732 2733 if (jvmti_thread_state() != NULL) { 2734 jvmti_thread_state()->oops_do(f); 2735 } 2736} 2737 2738void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2739 Thread::nmethods_do(cf); // (super method is a no-op) 2740 2741 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2742 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2743 2744 if (has_last_Java_frame()) { 2745 // Traverse the execution stack 2746 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2747 fst.current()->nmethods_do(cf); 2748 } 2749 } 2750} 2751 2752void JavaThread::metadata_do(void f(Metadata*)) { 2753 Thread::metadata_do(f); 2754 if (has_last_Java_frame()) { 2755 // Traverse the execution stack to call f() on the methods in the stack 2756 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2757 fst.current()->metadata_do(f); 2758 } 2759 } else if (is_Compiler_thread()) { 2760 // need to walk ciMetadata in current compile tasks to keep alive. 2761 CompilerThread* ct = (CompilerThread*)this; 2762 if (ct->env() != NULL) { 2763 ct->env()->metadata_do(f); 2764 } 2765 } 2766} 2767 2768// Printing 2769const char* _get_thread_state_name(JavaThreadState _thread_state) { 2770 switch (_thread_state) { 2771 case _thread_uninitialized: return "_thread_uninitialized"; 2772 case _thread_new: return "_thread_new"; 2773 case _thread_new_trans: return "_thread_new_trans"; 2774 case _thread_in_native: return "_thread_in_native"; 2775 case _thread_in_native_trans: return "_thread_in_native_trans"; 2776 case _thread_in_vm: return "_thread_in_vm"; 2777 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2778 case _thread_in_Java: return "_thread_in_Java"; 2779 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2780 case _thread_blocked: return "_thread_blocked"; 2781 case _thread_blocked_trans: return "_thread_blocked_trans"; 2782 default: return "unknown thread state"; 2783 } 2784} 2785 2786#ifndef PRODUCT 2787void JavaThread::print_thread_state_on(outputStream *st) const { 2788 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2789}; 2790void JavaThread::print_thread_state() const { 2791 print_thread_state_on(tty); 2792} 2793#endif // PRODUCT 2794 2795// Called by Threads::print() for VM_PrintThreads operation 2796void JavaThread::print_on(outputStream *st) const { 2797 st->print("\"%s\" ", get_thread_name()); 2798 oop thread_oop = threadObj(); 2799 if (thread_oop != NULL) { 2800 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2801 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2802 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2803 } 2804 Thread::print_on(st); 2805 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2806 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2807 if (thread_oop != NULL) { 2808 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2809 } 2810#ifndef PRODUCT 2811 print_thread_state_on(st); 2812 _safepoint_state->print_on(st); 2813#endif // PRODUCT 2814} 2815 2816// Called by fatal error handler. The difference between this and 2817// JavaThread::print() is that we can't grab lock or allocate memory. 2818void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2819 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2820 oop thread_obj = threadObj(); 2821 if (thread_obj != NULL) { 2822 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2823 } 2824 st->print(" ["); 2825 st->print("%s", _get_thread_state_name(_thread_state)); 2826 if (osthread()) { 2827 st->print(", id=%d", osthread()->thread_id()); 2828 } 2829 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2830 _stack_base - _stack_size, _stack_base); 2831 st->print("]"); 2832 return; 2833} 2834 2835// Verification 2836 2837static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2838 2839void JavaThread::verify() { 2840 // Verify oops in the thread. 2841 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2842 2843 // Verify the stack frames. 2844 frames_do(frame_verify); 2845} 2846 2847// CR 6300358 (sub-CR 2137150) 2848// Most callers of this method assume that it can't return NULL but a 2849// thread may not have a name whilst it is in the process of attaching to 2850// the VM - see CR 6412693, and there are places where a JavaThread can be 2851// seen prior to having it's threadObj set (eg JNI attaching threads and 2852// if vm exit occurs during initialization). These cases can all be accounted 2853// for such that this method never returns NULL. 2854const char* JavaThread::get_thread_name() const { 2855#ifdef ASSERT 2856 // early safepoints can hit while current thread does not yet have TLS 2857 if (!SafepointSynchronize::is_at_safepoint()) { 2858 Thread *cur = Thread::current(); 2859 if (!(cur->is_Java_thread() && cur == this)) { 2860 // Current JavaThreads are allowed to get their own name without 2861 // the Threads_lock. 2862 assert_locked_or_safepoint(Threads_lock); 2863 } 2864 } 2865#endif // ASSERT 2866 return get_thread_name_string(); 2867} 2868 2869// Returns a non-NULL representation of this thread's name, or a suitable 2870// descriptive string if there is no set name 2871const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2872 const char* name_str; 2873 oop thread_obj = threadObj(); 2874 if (thread_obj != NULL) { 2875 typeArrayOop name = java_lang_Thread::name(thread_obj); 2876 if (name != NULL) { 2877 if (buf == NULL) { 2878 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2879 name->length()); 2880 } else { 2881 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2882 name->length(), buf, buflen); 2883 } 2884 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2885 name_str = "<no-name - thread is attaching>"; 2886 } else { 2887 name_str = Thread::name(); 2888 } 2889 } else { 2890 name_str = Thread::name(); 2891 } 2892 assert(name_str != NULL, "unexpected NULL thread name"); 2893 return name_str; 2894} 2895 2896 2897const char* JavaThread::get_threadgroup_name() const { 2898 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2899 oop thread_obj = threadObj(); 2900 if (thread_obj != NULL) { 2901 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2902 if (thread_group != NULL) { 2903 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2904 // ThreadGroup.name can be null 2905 if (name != NULL) { 2906 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2907 return str; 2908 } 2909 } 2910 } 2911 return NULL; 2912} 2913 2914const char* JavaThread::get_parent_name() const { 2915 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2916 oop thread_obj = threadObj(); 2917 if (thread_obj != NULL) { 2918 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2919 if (thread_group != NULL) { 2920 oop parent = java_lang_ThreadGroup::parent(thread_group); 2921 if (parent != NULL) { 2922 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2923 // ThreadGroup.name can be null 2924 if (name != NULL) { 2925 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2926 return str; 2927 } 2928 } 2929 } 2930 } 2931 return NULL; 2932} 2933 2934ThreadPriority JavaThread::java_priority() const { 2935 oop thr_oop = threadObj(); 2936 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2937 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2938 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2939 return priority; 2940} 2941 2942void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2943 2944 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2945 // Link Java Thread object <-> C++ Thread 2946 2947 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2948 // and put it into a new Handle. The Handle "thread_oop" can then 2949 // be used to pass the C++ thread object to other methods. 2950 2951 // Set the Java level thread object (jthread) field of the 2952 // new thread (a JavaThread *) to C++ thread object using the 2953 // "thread_oop" handle. 2954 2955 // Set the thread field (a JavaThread *) of the 2956 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2957 2958 Handle thread_oop(Thread::current(), 2959 JNIHandles::resolve_non_null(jni_thread)); 2960 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 2961 "must be initialized"); 2962 set_threadObj(thread_oop()); 2963 java_lang_Thread::set_thread(thread_oop(), this); 2964 2965 if (prio == NoPriority) { 2966 prio = java_lang_Thread::priority(thread_oop()); 2967 assert(prio != NoPriority, "A valid priority should be present"); 2968 } 2969 2970 // Push the Java priority down to the native thread; needs Threads_lock 2971 Thread::set_priority(this, prio); 2972 2973 prepare_ext(); 2974 2975 // Add the new thread to the Threads list and set it in motion. 2976 // We must have threads lock in order to call Threads::add. 2977 // It is crucial that we do not block before the thread is 2978 // added to the Threads list for if a GC happens, then the java_thread oop 2979 // will not be visited by GC. 2980 Threads::add(this); 2981} 2982 2983oop JavaThread::current_park_blocker() { 2984 // Support for JSR-166 locks 2985 oop thread_oop = threadObj(); 2986 if (thread_oop != NULL && 2987 JDK_Version::current().supports_thread_park_blocker()) { 2988 return java_lang_Thread::park_blocker(thread_oop); 2989 } 2990 return NULL; 2991} 2992 2993 2994void JavaThread::print_stack_on(outputStream* st) { 2995 if (!has_last_Java_frame()) return; 2996 ResourceMark rm; 2997 HandleMark hm; 2998 2999 RegisterMap reg_map(this); 3000 vframe* start_vf = last_java_vframe(®_map); 3001 int count = 0; 3002 for (vframe* f = start_vf; f; f = f->sender()) { 3003 if (f->is_java_frame()) { 3004 javaVFrame* jvf = javaVFrame::cast(f); 3005 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3006 3007 // Print out lock information 3008 if (JavaMonitorsInStackTrace) { 3009 jvf->print_lock_info_on(st, count); 3010 } 3011 } else { 3012 // Ignore non-Java frames 3013 } 3014 3015 // Bail-out case for too deep stacks 3016 count++; 3017 if (MaxJavaStackTraceDepth == count) return; 3018 } 3019} 3020 3021 3022// JVMTI PopFrame support 3023void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3024 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3025 if (in_bytes(size_in_bytes) != 0) { 3026 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3027 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3028 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3029 } 3030} 3031 3032void* JavaThread::popframe_preserved_args() { 3033 return _popframe_preserved_args; 3034} 3035 3036ByteSize JavaThread::popframe_preserved_args_size() { 3037 return in_ByteSize(_popframe_preserved_args_size); 3038} 3039 3040WordSize JavaThread::popframe_preserved_args_size_in_words() { 3041 int sz = in_bytes(popframe_preserved_args_size()); 3042 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3043 return in_WordSize(sz / wordSize); 3044} 3045 3046void JavaThread::popframe_free_preserved_args() { 3047 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3048 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread); 3049 _popframe_preserved_args = NULL; 3050 _popframe_preserved_args_size = 0; 3051} 3052 3053#ifndef PRODUCT 3054 3055void JavaThread::trace_frames() { 3056 tty->print_cr("[Describe stack]"); 3057 int frame_no = 1; 3058 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3059 tty->print(" %d. ", frame_no++); 3060 fst.current()->print_value_on(tty, this); 3061 tty->cr(); 3062 } 3063} 3064 3065class PrintAndVerifyOopClosure: public OopClosure { 3066 protected: 3067 template <class T> inline void do_oop_work(T* p) { 3068 oop obj = oopDesc::load_decode_heap_oop(p); 3069 if (obj == NULL) return; 3070 tty->print(INTPTR_FORMAT ": ", p); 3071 if (obj->is_oop_or_null()) { 3072 if (obj->is_objArray()) { 3073 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 3074 } else { 3075 obj->print(); 3076 } 3077 } else { 3078 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 3079 } 3080 tty->cr(); 3081 } 3082 public: 3083 virtual void do_oop(oop* p) { do_oop_work(p); } 3084 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3085}; 3086 3087 3088static void oops_print(frame* f, const RegisterMap *map) { 3089 PrintAndVerifyOopClosure print; 3090 f->print_value(); 3091 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3092} 3093 3094// Print our all the locations that contain oops and whether they are 3095// valid or not. This useful when trying to find the oldest frame 3096// where an oop has gone bad since the frame walk is from youngest to 3097// oldest. 3098void JavaThread::trace_oops() { 3099 tty->print_cr("[Trace oops]"); 3100 frames_do(oops_print); 3101} 3102 3103 3104#ifdef ASSERT 3105// Print or validate the layout of stack frames 3106void JavaThread::print_frame_layout(int depth, bool validate_only) { 3107 ResourceMark rm; 3108 PRESERVE_EXCEPTION_MARK; 3109 FrameValues values; 3110 int frame_no = 0; 3111 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3112 fst.current()->describe(values, ++frame_no); 3113 if (depth == frame_no) break; 3114 } 3115 if (validate_only) { 3116 values.validate(); 3117 } else { 3118 tty->print_cr("[Describe stack layout]"); 3119 values.print(this); 3120 } 3121} 3122#endif 3123 3124void JavaThread::trace_stack_from(vframe* start_vf) { 3125 ResourceMark rm; 3126 int vframe_no = 1; 3127 for (vframe* f = start_vf; f; f = f->sender()) { 3128 if (f->is_java_frame()) { 3129 javaVFrame::cast(f)->print_activation(vframe_no++); 3130 } else { 3131 f->print(); 3132 } 3133 if (vframe_no > StackPrintLimit) { 3134 tty->print_cr("...<more frames>..."); 3135 return; 3136 } 3137 } 3138} 3139 3140 3141void JavaThread::trace_stack() { 3142 if (!has_last_Java_frame()) return; 3143 ResourceMark rm; 3144 HandleMark hm; 3145 RegisterMap reg_map(this); 3146 trace_stack_from(last_java_vframe(®_map)); 3147} 3148 3149 3150#endif // PRODUCT 3151 3152 3153javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3154 assert(reg_map != NULL, "a map must be given"); 3155 frame f = last_frame(); 3156 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3157 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3158 } 3159 return NULL; 3160} 3161 3162 3163Klass* JavaThread::security_get_caller_class(int depth) { 3164 vframeStream vfst(this); 3165 vfst.security_get_caller_frame(depth); 3166 if (!vfst.at_end()) { 3167 return vfst.method()->method_holder(); 3168 } 3169 return NULL; 3170} 3171 3172static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3173 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3174 CompileBroker::compiler_thread_loop(); 3175} 3176 3177static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3178 NMethodSweeper::sweeper_loop(); 3179} 3180 3181// Create a CompilerThread 3182CompilerThread::CompilerThread(CompileQueue* queue, 3183 CompilerCounters* counters) 3184 : JavaThread(&compiler_thread_entry) { 3185 _env = NULL; 3186 _log = NULL; 3187 _task = NULL; 3188 _queue = queue; 3189 _counters = counters; 3190 _buffer_blob = NULL; 3191 _compiler = NULL; 3192 3193#ifndef PRODUCT 3194 _ideal_graph_printer = NULL; 3195#endif 3196} 3197 3198// Create sweeper thread 3199CodeCacheSweeperThread::CodeCacheSweeperThread() 3200: JavaThread(&sweeper_thread_entry) { 3201 _scanned_nmethod = NULL; 3202} 3203void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3204 JavaThread::oops_do(f, cld_f, cf); 3205 if (_scanned_nmethod != NULL && cf != NULL) { 3206 // Safepoints can occur when the sweeper is scanning an nmethod so 3207 // process it here to make sure it isn't unloaded in the middle of 3208 // a scan. 3209 cf->do_code_blob(_scanned_nmethod); 3210 } 3211} 3212 3213 3214// ======= Threads ======== 3215 3216// The Threads class links together all active threads, and provides 3217// operations over all threads. It is protected by its own Mutex 3218// lock, which is also used in other contexts to protect thread 3219// operations from having the thread being operated on from exiting 3220// and going away unexpectedly (e.g., safepoint synchronization) 3221 3222JavaThread* Threads::_thread_list = NULL; 3223int Threads::_number_of_threads = 0; 3224int Threads::_number_of_non_daemon_threads = 0; 3225int Threads::_return_code = 0; 3226size_t JavaThread::_stack_size_at_create = 0; 3227#ifdef ASSERT 3228bool Threads::_vm_complete = false; 3229#endif 3230 3231// All JavaThreads 3232#define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3233 3234// All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3235void Threads::threads_do(ThreadClosure* tc) { 3236 assert_locked_or_safepoint(Threads_lock); 3237 // ALL_JAVA_THREADS iterates through all JavaThreads 3238 ALL_JAVA_THREADS(p) { 3239 tc->do_thread(p); 3240 } 3241 // Someday we could have a table or list of all non-JavaThreads. 3242 // For now, just manually iterate through them. 3243 tc->do_thread(VMThread::vm_thread()); 3244 Universe::heap()->gc_threads_do(tc); 3245 WatcherThread *wt = WatcherThread::watcher_thread(); 3246 // Strictly speaking, the following NULL check isn't sufficient to make sure 3247 // the data for WatcherThread is still valid upon being examined. However, 3248 // considering that WatchThread terminates when the VM is on the way to 3249 // exit at safepoint, the chance of the above is extremely small. The right 3250 // way to prevent termination of WatcherThread would be to acquire 3251 // Terminator_lock, but we can't do that without violating the lock rank 3252 // checking in some cases. 3253 if (wt != NULL) { 3254 tc->do_thread(wt); 3255 } 3256 3257 // If CompilerThreads ever become non-JavaThreads, add them here 3258} 3259 3260 3261void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3262 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3263 3264 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3265 create_vm_init_libraries(); 3266 } 3267 3268 initialize_class(vmSymbols::java_lang_String(), CHECK); 3269 3270 // Initialize java_lang.System (needed before creating the thread) 3271 initialize_class(vmSymbols::java_lang_System(), CHECK); 3272 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3273 Handle thread_group = create_initial_thread_group(CHECK); 3274 Universe::set_main_thread_group(thread_group()); 3275 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3276 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3277 main_thread->set_threadObj(thread_object); 3278 // Set thread status to running since main thread has 3279 // been started and running. 3280 java_lang_Thread::set_thread_status(thread_object, 3281 java_lang_Thread::RUNNABLE); 3282 3283 // The VM creates & returns objects of this class. Make sure it's initialized. 3284 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3285 3286 // The VM preresolves methods to these classes. Make sure that they get initialized 3287 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3288 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3289 call_initializeSystemClass(CHECK); 3290 3291 // get the Java runtime name after java.lang.System is initialized 3292 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3293 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3294 3295 // an instance of OutOfMemory exception has been allocated earlier 3296 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3297 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3298 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3299 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3300 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3301 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3302 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3303 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3304} 3305 3306void Threads::initialize_jsr292_core_classes(TRAPS) { 3307 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3308 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3309 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3310} 3311 3312jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3313 extern void JDK_Version_init(); 3314 3315 // Check version 3316 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3317 3318 // Initialize the output stream module 3319 ostream_init(); 3320 3321 // Process java launcher properties. 3322 Arguments::process_sun_java_launcher_properties(args); 3323 3324 // Initialize the os module before using TLS 3325 os::init(); 3326 3327 // Initialize system properties. 3328 Arguments::init_system_properties(); 3329 3330 // So that JDK version can be used as a discriminator when parsing arguments 3331 JDK_Version_init(); 3332 3333 // Update/Initialize System properties after JDK version number is known 3334 Arguments::init_version_specific_system_properties(); 3335 3336 // Parse arguments 3337 jint parse_result = Arguments::parse(args); 3338 if (parse_result != JNI_OK) return parse_result; 3339 3340 os::init_before_ergo(); 3341 3342 jint ergo_result = Arguments::apply_ergo(); 3343 if (ergo_result != JNI_OK) return ergo_result; 3344 3345 if (PauseAtStartup) { 3346 os::pause(); 3347 } 3348 3349 HOTSPOT_VM_INIT_BEGIN(); 3350 3351 // Record VM creation timing statistics 3352 TraceVmCreationTime create_vm_timer; 3353 create_vm_timer.start(); 3354 3355 // Timing (must come after argument parsing) 3356 TraceTime timer("Create VM", TraceStartupTime); 3357 3358 // Initialize the os module after parsing the args 3359 jint os_init_2_result = os::init_2(); 3360 if (os_init_2_result != JNI_OK) return os_init_2_result; 3361 3362 jint adjust_after_os_result = Arguments::adjust_after_os(); 3363 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3364 3365 // initialize TLS 3366 ThreadLocalStorage::init(); 3367 3368 // Initialize output stream logging 3369 ostream_init_log(); 3370 3371 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3372 // Must be before create_vm_init_agents() 3373 if (Arguments::init_libraries_at_startup()) { 3374 convert_vm_init_libraries_to_agents(); 3375 } 3376 3377 // Launch -agentlib/-agentpath and converted -Xrun agents 3378 if (Arguments::init_agents_at_startup()) { 3379 create_vm_init_agents(); 3380 } 3381 3382 // Initialize Threads state 3383 _thread_list = NULL; 3384 _number_of_threads = 0; 3385 _number_of_non_daemon_threads = 0; 3386 3387 // Initialize global data structures and create system classes in heap 3388 vm_init_globals(); 3389 3390 // Attach the main thread to this os thread 3391 JavaThread* main_thread = new JavaThread(); 3392 main_thread->set_thread_state(_thread_in_vm); 3393 // must do this before set_active_handles and initialize_thread_local_storage 3394 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3395 // change the stack size recorded here to one based on the java thread 3396 // stacksize. This adjusted size is what is used to figure the placement 3397 // of the guard pages. 3398 main_thread->record_stack_base_and_size(); 3399 main_thread->initialize_thread_local_storage(); 3400 3401 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3402 3403 if (!main_thread->set_as_starting_thread()) { 3404 vm_shutdown_during_initialization( 3405 "Failed necessary internal allocation. Out of swap space"); 3406 delete main_thread; 3407 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3408 return JNI_ENOMEM; 3409 } 3410 3411 // Enable guard page *after* os::create_main_thread(), otherwise it would 3412 // crash Linux VM, see notes in os_linux.cpp. 3413 main_thread->create_stack_guard_pages(); 3414 3415 // Initialize Java-Level synchronization subsystem 3416 ObjectMonitor::Initialize(); 3417 3418 // Initialize global modules 3419 jint status = init_globals(); 3420 if (status != JNI_OK) { 3421 delete main_thread; 3422 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3423 return status; 3424 } 3425 3426 // Should be done after the heap is fully created 3427 main_thread->cache_global_variables(); 3428 3429 HandleMark hm; 3430 3431 { MutexLocker mu(Threads_lock); 3432 Threads::add(main_thread); 3433 } 3434 3435 // Any JVMTI raw monitors entered in onload will transition into 3436 // real raw monitor. VM is setup enough here for raw monitor enter. 3437 JvmtiExport::transition_pending_onload_raw_monitors(); 3438 3439 // Create the VMThread 3440 { TraceTime timer("Start VMThread", TraceStartupTime); 3441 VMThread::create(); 3442 Thread* vmthread = VMThread::vm_thread(); 3443 3444 if (!os::create_thread(vmthread, os::vm_thread)) { 3445 vm_exit_during_initialization("Cannot create VM thread. " 3446 "Out of system resources."); 3447 } 3448 3449 // Wait for the VM thread to become ready, and VMThread::run to initialize 3450 // Monitors can have spurious returns, must always check another state flag 3451 { 3452 MutexLocker ml(Notify_lock); 3453 os::start_thread(vmthread); 3454 while (vmthread->active_handles() == NULL) { 3455 Notify_lock->wait(); 3456 } 3457 } 3458 } 3459 3460 assert(Universe::is_fully_initialized(), "not initialized"); 3461 if (VerifyDuringStartup) { 3462 // Make sure we're starting with a clean slate. 3463 VM_Verify verify_op; 3464 VMThread::execute(&verify_op); 3465 } 3466 3467 Thread* THREAD = Thread::current(); 3468 3469 // At this point, the Universe is initialized, but we have not executed 3470 // any byte code. Now is a good time (the only time) to dump out the 3471 // internal state of the JVM for sharing. 3472 if (DumpSharedSpaces) { 3473 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3474 ShouldNotReachHere(); 3475 } 3476 3477 // Always call even when there are not JVMTI environments yet, since environments 3478 // may be attached late and JVMTI must track phases of VM execution 3479 JvmtiExport::enter_start_phase(); 3480 3481 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3482 JvmtiExport::post_vm_start(); 3483 3484 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3485 3486 // We need this for ClassDataSharing - the initial vm.info property is set 3487 // with the default value of CDS "sharing" which may be reset through 3488 // command line options. 3489 reset_vm_info_property(CHECK_JNI_ERR); 3490 3491 quicken_jni_functions(); 3492 3493 // Must be run after init_ft which initializes ft_enabled 3494 if (TRACE_INITIALIZE() != JNI_OK) { 3495 vm_exit_during_initialization("Failed to initialize tracing backend"); 3496 } 3497 3498 // Set flag that basic initialization has completed. Used by exceptions and various 3499 // debug stuff, that does not work until all basic classes have been initialized. 3500 set_init_completed(); 3501 3502 Metaspace::post_initialize(); 3503 3504 HOTSPOT_VM_INIT_END(); 3505 3506 // record VM initialization completion time 3507#if INCLUDE_MANAGEMENT 3508 Management::record_vm_init_completed(); 3509#endif // INCLUDE_MANAGEMENT 3510 3511 // Compute system loader. Note that this has to occur after set_init_completed, since 3512 // valid exceptions may be thrown in the process. 3513 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3514 // set_init_completed has just been called, causing exceptions not to be shortcut 3515 // anymore. We call vm_exit_during_initialization directly instead. 3516 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR); 3517 3518#if INCLUDE_ALL_GCS 3519 // Support for ConcurrentMarkSweep. This should be cleaned up 3520 // and better encapsulated. The ugly nested if test would go away 3521 // once things are properly refactored. XXX YSR 3522 if (UseConcMarkSweepGC || UseG1GC) { 3523 if (UseConcMarkSweepGC) { 3524 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3525 } else { 3526 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3527 } 3528 } 3529#endif // INCLUDE_ALL_GCS 3530 3531 // Always call even when there are not JVMTI environments yet, since environments 3532 // may be attached late and JVMTI must track phases of VM execution 3533 JvmtiExport::enter_live_phase(); 3534 3535 // Signal Dispatcher needs to be started before VMInit event is posted 3536 os::signal_init(); 3537 3538 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3539 if (!DisableAttachMechanism) { 3540 AttachListener::vm_start(); 3541 if (StartAttachListener || AttachListener::init_at_startup()) { 3542 AttachListener::init(); 3543 } 3544 } 3545 3546 // Launch -Xrun agents 3547 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3548 // back-end can launch with -Xdebug -Xrunjdwp. 3549 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3550 create_vm_init_libraries(); 3551 } 3552 3553 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3554 JvmtiExport::post_vm_initialized(); 3555 3556 if (TRACE_START() != JNI_OK) { 3557 vm_exit_during_initialization("Failed to start tracing backend."); 3558 } 3559 3560 if (CleanChunkPoolAsync) { 3561 Chunk::start_chunk_pool_cleaner_task(); 3562 } 3563 3564 // initialize compiler(s) 3565#if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) 3566 CompileBroker::compilation_init(); 3567#endif 3568 3569 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3570 // It is done after compilers are initialized, because otherwise compilations of 3571 // signature polymorphic MH intrinsics can be missed 3572 // (see SystemDictionary::find_method_handle_intrinsic). 3573 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3574 3575#if INCLUDE_MANAGEMENT 3576 Management::initialize(THREAD); 3577 3578 if (HAS_PENDING_EXCEPTION) { 3579 // management agent fails to start possibly due to 3580 // configuration problem and is responsible for printing 3581 // stack trace if appropriate. Simply exit VM. 3582 vm_exit(1); 3583 } 3584#endif // INCLUDE_MANAGEMENT 3585 3586 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3587 if (MemProfiling) MemProfiler::engage(); 3588 StatSampler::engage(); 3589 if (CheckJNICalls) JniPeriodicChecker::engage(); 3590 3591 BiasedLocking::init(); 3592 3593#if INCLUDE_RTM_OPT 3594 RTMLockingCounters::init(); 3595#endif 3596 3597 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3598 call_postVMInitHook(THREAD); 3599 // The Java side of PostVMInitHook.run must deal with all 3600 // exceptions and provide means of diagnosis. 3601 if (HAS_PENDING_EXCEPTION) { 3602 CLEAR_PENDING_EXCEPTION; 3603 } 3604 } 3605 3606 { 3607 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 3608 // Make sure the watcher thread can be started by WatcherThread::start() 3609 // or by dynamic enrollment. 3610 WatcherThread::make_startable(); 3611 // Start up the WatcherThread if there are any periodic tasks 3612 // NOTE: All PeriodicTasks should be registered by now. If they 3613 // aren't, late joiners might appear to start slowly (we might 3614 // take a while to process their first tick). 3615 if (PeriodicTask::num_tasks() > 0) { 3616 WatcherThread::start(); 3617 } 3618 } 3619 3620 // Give os specific code one last chance to start 3621 os::init_3(); 3622 3623 create_vm_timer.end(); 3624#ifdef ASSERT 3625 _vm_complete = true; 3626#endif 3627 return JNI_OK; 3628} 3629 3630// type for the Agent_OnLoad and JVM_OnLoad entry points 3631extern "C" { 3632 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3633} 3634// Find a command line agent library and return its entry point for 3635// -agentlib: -agentpath: -Xrun 3636// num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3637static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3638 const char *on_load_symbols[], 3639 size_t num_symbol_entries) { 3640 OnLoadEntry_t on_load_entry = NULL; 3641 void *library = NULL; 3642 3643 if (!agent->valid()) { 3644 char buffer[JVM_MAXPATHLEN]; 3645 char ebuf[1024] = ""; 3646 const char *name = agent->name(); 3647 const char *msg = "Could not find agent library "; 3648 3649 // First check to see if agent is statically linked into executable 3650 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3651 library = agent->os_lib(); 3652 } else if (agent->is_absolute_path()) { 3653 library = os::dll_load(name, ebuf, sizeof ebuf); 3654 if (library == NULL) { 3655 const char *sub_msg = " in absolute path, with error: "; 3656 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3657 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3658 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3659 // If we can't find the agent, exit. 3660 vm_exit_during_initialization(buf, NULL); 3661 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3662 } 3663 } else { 3664 // Try to load the agent from the standard dll directory 3665 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3666 name)) { 3667 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3668 } 3669 if (library == NULL) { // Try the local directory 3670 char ns[1] = {0}; 3671 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3672 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3673 } 3674 if (library == NULL) { 3675 const char *sub_msg = " on the library path, with error: "; 3676 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3677 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3678 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3679 // If we can't find the agent, exit. 3680 vm_exit_during_initialization(buf, NULL); 3681 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3682 } 3683 } 3684 } 3685 agent->set_os_lib(library); 3686 agent->set_valid(); 3687 } 3688 3689 // Find the OnLoad function. 3690 on_load_entry = 3691 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3692 false, 3693 on_load_symbols, 3694 num_symbol_entries)); 3695 return on_load_entry; 3696} 3697 3698// Find the JVM_OnLoad entry point 3699static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3700 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3701 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3702} 3703 3704// Find the Agent_OnLoad entry point 3705static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3706 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3707 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3708} 3709 3710// For backwards compatibility with -Xrun 3711// Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3712// treated like -agentpath: 3713// Must be called before agent libraries are created 3714void Threads::convert_vm_init_libraries_to_agents() { 3715 AgentLibrary* agent; 3716 AgentLibrary* next; 3717 3718 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3719 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3720 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3721 3722 // If there is an JVM_OnLoad function it will get called later, 3723 // otherwise see if there is an Agent_OnLoad 3724 if (on_load_entry == NULL) { 3725 on_load_entry = lookup_agent_on_load(agent); 3726 if (on_load_entry != NULL) { 3727 // switch it to the agent list -- so that Agent_OnLoad will be called, 3728 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3729 Arguments::convert_library_to_agent(agent); 3730 } else { 3731 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3732 } 3733 } 3734 } 3735} 3736 3737// Create agents for -agentlib: -agentpath: and converted -Xrun 3738// Invokes Agent_OnLoad 3739// Called very early -- before JavaThreads exist 3740void Threads::create_vm_init_agents() { 3741 extern struct JavaVM_ main_vm; 3742 AgentLibrary* agent; 3743 3744 JvmtiExport::enter_onload_phase(); 3745 3746 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3747 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3748 3749 if (on_load_entry != NULL) { 3750 // Invoke the Agent_OnLoad function 3751 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3752 if (err != JNI_OK) { 3753 vm_exit_during_initialization("agent library failed to init", agent->name()); 3754 } 3755 } else { 3756 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3757 } 3758 } 3759 JvmtiExport::enter_primordial_phase(); 3760} 3761 3762extern "C" { 3763 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3764} 3765 3766void Threads::shutdown_vm_agents() { 3767 // Send any Agent_OnUnload notifications 3768 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3769 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3770 extern struct JavaVM_ main_vm; 3771 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3772 3773 // Find the Agent_OnUnload function. 3774 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3775 os::find_agent_function(agent, 3776 false, 3777 on_unload_symbols, 3778 num_symbol_entries)); 3779 3780 // Invoke the Agent_OnUnload function 3781 if (unload_entry != NULL) { 3782 JavaThread* thread = JavaThread::current(); 3783 ThreadToNativeFromVM ttn(thread); 3784 HandleMark hm(thread); 3785 (*unload_entry)(&main_vm); 3786 } 3787 } 3788} 3789 3790// Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3791// Invokes JVM_OnLoad 3792void Threads::create_vm_init_libraries() { 3793 extern struct JavaVM_ main_vm; 3794 AgentLibrary* agent; 3795 3796 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3797 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3798 3799 if (on_load_entry != NULL) { 3800 // Invoke the JVM_OnLoad function 3801 JavaThread* thread = JavaThread::current(); 3802 ThreadToNativeFromVM ttn(thread); 3803 HandleMark hm(thread); 3804 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3805 if (err != JNI_OK) { 3806 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3807 } 3808 } else { 3809 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3810 } 3811 } 3812} 3813 3814JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 3815 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 3816 3817 JavaThread* java_thread = NULL; 3818 // Sequential search for now. Need to do better optimization later. 3819 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 3820 oop tobj = thread->threadObj(); 3821 if (!thread->is_exiting() && 3822 tobj != NULL && 3823 java_tid == java_lang_Thread::thread_id(tobj)) { 3824 java_thread = thread; 3825 break; 3826 } 3827 } 3828 return java_thread; 3829} 3830 3831 3832// Last thread running calls java.lang.Shutdown.shutdown() 3833void JavaThread::invoke_shutdown_hooks() { 3834 HandleMark hm(this); 3835 3836 // We could get here with a pending exception, if so clear it now. 3837 if (this->has_pending_exception()) { 3838 this->clear_pending_exception(); 3839 } 3840 3841 EXCEPTION_MARK; 3842 Klass* k = 3843 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3844 THREAD); 3845 if (k != NULL) { 3846 // SystemDictionary::resolve_or_null will return null if there was 3847 // an exception. If we cannot load the Shutdown class, just don't 3848 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3849 // and finalizers (if runFinalizersOnExit is set) won't be run. 3850 // Note that if a shutdown hook was registered or runFinalizersOnExit 3851 // was called, the Shutdown class would have already been loaded 3852 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3853 instanceKlassHandle shutdown_klass (THREAD, k); 3854 JavaValue result(T_VOID); 3855 JavaCalls::call_static(&result, 3856 shutdown_klass, 3857 vmSymbols::shutdown_method_name(), 3858 vmSymbols::void_method_signature(), 3859 THREAD); 3860 } 3861 CLEAR_PENDING_EXCEPTION; 3862} 3863 3864// Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3865// the program falls off the end of main(). Another VM exit path is through 3866// vm_exit() when the program calls System.exit() to return a value or when 3867// there is a serious error in VM. The two shutdown paths are not exactly 3868// the same, but they share Shutdown.shutdown() at Java level and before_exit() 3869// and VM_Exit op at VM level. 3870// 3871// Shutdown sequence: 3872// + Shutdown native memory tracking if it is on 3873// + Wait until we are the last non-daemon thread to execute 3874// <-- every thing is still working at this moment --> 3875// + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3876// shutdown hooks, run finalizers if finalization-on-exit 3877// + Call before_exit(), prepare for VM exit 3878// > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3879// currently the only user of this mechanism is File.deleteOnExit()) 3880// > stop flat profiler, StatSampler, watcher thread, CMS threads, 3881// post thread end and vm death events to JVMTI, 3882// stop signal thread 3883// + Call JavaThread::exit(), it will: 3884// > release JNI handle blocks, remove stack guard pages 3885// > remove this thread from Threads list 3886// <-- no more Java code from this thread after this point --> 3887// + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3888// the compiler threads at safepoint 3889// <-- do not use anything that could get blocked by Safepoint --> 3890// + Disable tracing at JNI/JVM barriers 3891// + Set _vm_exited flag for threads that are still running native code 3892// + Delete this thread 3893// + Call exit_globals() 3894// > deletes tty 3895// > deletes PerfMemory resources 3896// + Return to caller 3897 3898bool Threads::destroy_vm() { 3899 JavaThread* thread = JavaThread::current(); 3900 3901#ifdef ASSERT 3902 _vm_complete = false; 3903#endif 3904 // Wait until we are the last non-daemon thread to execute 3905 { MutexLocker nu(Threads_lock); 3906 while (Threads::number_of_non_daemon_threads() > 1) 3907 // This wait should make safepoint checks, wait without a timeout, 3908 // and wait as a suspend-equivalent condition. 3909 // 3910 // Note: If the FlatProfiler is running and this thread is waiting 3911 // for another non-daemon thread to finish, then the FlatProfiler 3912 // is waiting for the external suspend request on this thread to 3913 // complete. wait_for_ext_suspend_completion() will eventually 3914 // timeout, but that takes time. Making this wait a suspend- 3915 // equivalent condition solves that timeout problem. 3916 // 3917 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3918 Mutex::_as_suspend_equivalent_flag); 3919 } 3920 3921 // Hang forever on exit if we are reporting an error. 3922 if (ShowMessageBoxOnError && is_error_reported()) { 3923 os::infinite_sleep(); 3924 } 3925 os::wait_for_keypress_at_exit(); 3926 3927 // run Java level shutdown hooks 3928 thread->invoke_shutdown_hooks(); 3929 3930 before_exit(thread); 3931 3932 thread->exit(true); 3933 3934 // Stop VM thread. 3935 { 3936 // 4945125 The vm thread comes to a safepoint during exit. 3937 // GC vm_operations can get caught at the safepoint, and the 3938 // heap is unparseable if they are caught. Grab the Heap_lock 3939 // to prevent this. The GC vm_operations will not be able to 3940 // queue until after the vm thread is dead. After this point, 3941 // we'll never emerge out of the safepoint before the VM exits. 3942 3943 MutexLocker ml(Heap_lock); 3944 3945 VMThread::wait_for_vm_thread_exit(); 3946 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3947 VMThread::destroy(); 3948 } 3949 3950 // clean up ideal graph printers 3951#if defined(COMPILER2) && !defined(PRODUCT) 3952 IdealGraphPrinter::clean_up(); 3953#endif 3954 3955 // Now, all Java threads are gone except daemon threads. Daemon threads 3956 // running Java code or in VM are stopped by the Safepoint. However, 3957 // daemon threads executing native code are still running. But they 3958 // will be stopped at native=>Java/VM barriers. Note that we can't 3959 // simply kill or suspend them, as it is inherently deadlock-prone. 3960 3961#ifndef PRODUCT 3962 // disable function tracing at JNI/JVM barriers 3963 TraceJNICalls = false; 3964 TraceJVMCalls = false; 3965 TraceRuntimeCalls = false; 3966#endif 3967 3968 VM_Exit::set_vm_exited(); 3969 3970 notify_vm_shutdown(); 3971 3972 delete thread; 3973 3974 // exit_globals() will delete tty 3975 exit_globals(); 3976 3977 return true; 3978} 3979 3980 3981jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3982 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3983 return is_supported_jni_version(version); 3984} 3985 3986 3987jboolean Threads::is_supported_jni_version(jint version) { 3988 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3989 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3990 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3991 if (version == JNI_VERSION_1_8) return JNI_TRUE; 3992 return JNI_FALSE; 3993} 3994 3995 3996void Threads::add(JavaThread* p, bool force_daemon) { 3997 // The threads lock must be owned at this point 3998 assert_locked_or_safepoint(Threads_lock); 3999 4000 // See the comment for this method in thread.hpp for its purpose and 4001 // why it is called here. 4002 p->initialize_queues(); 4003 p->set_next(_thread_list); 4004 _thread_list = p; 4005 _number_of_threads++; 4006 oop threadObj = p->threadObj(); 4007 bool daemon = true; 4008 // Bootstrapping problem: threadObj can be null for initial 4009 // JavaThread (or for threads attached via JNI) 4010 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4011 _number_of_non_daemon_threads++; 4012 daemon = false; 4013 } 4014 4015 ThreadService::add_thread(p, daemon); 4016 4017 // Possible GC point. 4018 Events::log(p, "Thread added: " INTPTR_FORMAT, p); 4019} 4020 4021void Threads::remove(JavaThread* p) { 4022 // Extra scope needed for Thread_lock, so we can check 4023 // that we do not remove thread without safepoint code notice 4024 { MutexLocker ml(Threads_lock); 4025 4026 assert(includes(p), "p must be present"); 4027 4028 JavaThread* current = _thread_list; 4029 JavaThread* prev = NULL; 4030 4031 while (current != p) { 4032 prev = current; 4033 current = current->next(); 4034 } 4035 4036 if (prev) { 4037 prev->set_next(current->next()); 4038 } else { 4039 _thread_list = p->next(); 4040 } 4041 _number_of_threads--; 4042 oop threadObj = p->threadObj(); 4043 bool daemon = true; 4044 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4045 _number_of_non_daemon_threads--; 4046 daemon = false; 4047 4048 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4049 // on destroy_vm will wake up. 4050 if (number_of_non_daemon_threads() == 1) { 4051 Threads_lock->notify_all(); 4052 } 4053 } 4054 ThreadService::remove_thread(p, daemon); 4055 4056 // Make sure that safepoint code disregard this thread. This is needed since 4057 // the thread might mess around with locks after this point. This can cause it 4058 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4059 // of this thread since it is removed from the queue. 4060 p->set_terminated_value(); 4061 } // unlock Threads_lock 4062 4063 // Since Events::log uses a lock, we grab it outside the Threads_lock 4064 Events::log(p, "Thread exited: " INTPTR_FORMAT, p); 4065} 4066 4067// Threads_lock must be held when this is called (or must be called during a safepoint) 4068bool Threads::includes(JavaThread* p) { 4069 assert(Threads_lock->is_locked(), "sanity check"); 4070 ALL_JAVA_THREADS(q) { 4071 if (q == p) { 4072 return true; 4073 } 4074 } 4075 return false; 4076} 4077 4078// Operations on the Threads list for GC. These are not explicitly locked, 4079// but the garbage collector must provide a safe context for them to run. 4080// In particular, these things should never be called when the Threads_lock 4081// is held by some other thread. (Note: the Safepoint abstraction also 4082// uses the Threads_lock to guarantee this property. It also makes sure that 4083// all threads gets blocked when exiting or starting). 4084 4085void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4086 ALL_JAVA_THREADS(p) { 4087 p->oops_do(f, cld_f, cf); 4088 } 4089 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4090} 4091 4092void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4093 // Introduce a mechanism allowing parallel threads to claim threads as 4094 // root groups. Overhead should be small enough to use all the time, 4095 // even in sequential code. 4096 SharedHeap* sh = SharedHeap::heap(); 4097 // Cannot yet substitute active_workers for n_par_threads 4098 // because of G1CollectedHeap::verify() use of 4099 // SharedHeap::process_roots(). n_par_threads == 0 will 4100 // turn off parallelism in process_roots while active_workers 4101 // is being used for parallelism elsewhere. 4102 bool is_par = sh->n_par_threads() > 0; 4103 assert(!is_par || 4104 (SharedHeap::heap()->n_par_threads() == 4105 SharedHeap::heap()->workers()->active_workers()), "Mismatch"); 4106 int cp = SharedHeap::heap()->strong_roots_parity(); 4107 ALL_JAVA_THREADS(p) { 4108 if (p->claim_oops_do(is_par, cp)) { 4109 p->oops_do(f, cld_f, cf); 4110 } 4111 } 4112 VMThread* vmt = VMThread::vm_thread(); 4113 if (vmt->claim_oops_do(is_par, cp)) { 4114 vmt->oops_do(f, cld_f, cf); 4115 } 4116} 4117 4118#if INCLUDE_ALL_GCS 4119// Used by ParallelScavenge 4120void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4121 ALL_JAVA_THREADS(p) { 4122 q->enqueue(new ThreadRootsTask(p)); 4123 } 4124 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4125} 4126 4127// Used by Parallel Old 4128void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4129 ALL_JAVA_THREADS(p) { 4130 q->enqueue(new ThreadRootsMarkingTask(p)); 4131 } 4132 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4133} 4134#endif // INCLUDE_ALL_GCS 4135 4136void Threads::nmethods_do(CodeBlobClosure* cf) { 4137 ALL_JAVA_THREADS(p) { 4138 p->nmethods_do(cf); 4139 } 4140 VMThread::vm_thread()->nmethods_do(cf); 4141} 4142 4143void Threads::metadata_do(void f(Metadata*)) { 4144 ALL_JAVA_THREADS(p) { 4145 p->metadata_do(f); 4146 } 4147} 4148 4149void Threads::deoptimized_wrt_marked_nmethods() { 4150 ALL_JAVA_THREADS(p) { 4151 p->deoptimized_wrt_marked_nmethods(); 4152 } 4153} 4154 4155 4156// Get count Java threads that are waiting to enter the specified monitor. 4157GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4158 address monitor, 4159 bool doLock) { 4160 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4161 "must grab Threads_lock or be at safepoint"); 4162 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4163 4164 int i = 0; 4165 { 4166 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4167 ALL_JAVA_THREADS(p) { 4168 if (p->is_Compiler_thread()) continue; 4169 4170 address pending = (address)p->current_pending_monitor(); 4171 if (pending == monitor) { // found a match 4172 if (i < count) result->append(p); // save the first count matches 4173 i++; 4174 } 4175 } 4176 } 4177 return result; 4178} 4179 4180 4181JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4182 bool doLock) { 4183 assert(doLock || 4184 Threads_lock->owned_by_self() || 4185 SafepointSynchronize::is_at_safepoint(), 4186 "must grab Threads_lock or be at safepoint"); 4187 4188 // NULL owner means not locked so we can skip the search 4189 if (owner == NULL) return NULL; 4190 4191 { 4192 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4193 ALL_JAVA_THREADS(p) { 4194 // first, see if owner is the address of a Java thread 4195 if (owner == (address)p) return p; 4196 } 4197 } 4198 // Cannot assert on lack of success here since this function may be 4199 // used by code that is trying to report useful problem information 4200 // like deadlock detection. 4201 if (UseHeavyMonitors) return NULL; 4202 4203 // If we didn't find a matching Java thread and we didn't force use of 4204 // heavyweight monitors, then the owner is the stack address of the 4205 // Lock Word in the owning Java thread's stack. 4206 // 4207 JavaThread* the_owner = NULL; 4208 { 4209 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4210 ALL_JAVA_THREADS(q) { 4211 if (q->is_lock_owned(owner)) { 4212 the_owner = q; 4213 break; 4214 } 4215 } 4216 } 4217 // cannot assert on lack of success here; see above comment 4218 return the_owner; 4219} 4220 4221// Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4222void Threads::print_on(outputStream* st, bool print_stacks, 4223 bool internal_format, bool print_concurrent_locks) { 4224 char buf[32]; 4225 st->print_cr("%s", os::local_time_string(buf, sizeof(buf))); 4226 4227 st->print_cr("Full thread dump %s (%s %s):", 4228 Abstract_VM_Version::vm_name(), 4229 Abstract_VM_Version::vm_release(), 4230 Abstract_VM_Version::vm_info_string()); 4231 st->cr(); 4232 4233#if INCLUDE_ALL_GCS 4234 // Dump concurrent locks 4235 ConcurrentLocksDump concurrent_locks; 4236 if (print_concurrent_locks) { 4237 concurrent_locks.dump_at_safepoint(); 4238 } 4239#endif // INCLUDE_ALL_GCS 4240 4241 ALL_JAVA_THREADS(p) { 4242 ResourceMark rm; 4243 p->print_on(st); 4244 if (print_stacks) { 4245 if (internal_format) { 4246 p->trace_stack(); 4247 } else { 4248 p->print_stack_on(st); 4249 } 4250 } 4251 st->cr(); 4252#if INCLUDE_ALL_GCS 4253 if (print_concurrent_locks) { 4254 concurrent_locks.print_locks_on(p, st); 4255 } 4256#endif // INCLUDE_ALL_GCS 4257 } 4258 4259 VMThread::vm_thread()->print_on(st); 4260 st->cr(); 4261 Universe::heap()->print_gc_threads_on(st); 4262 WatcherThread* wt = WatcherThread::watcher_thread(); 4263 if (wt != NULL) { 4264 wt->print_on(st); 4265 st->cr(); 4266 } 4267 CompileBroker::print_compiler_threads_on(st); 4268 st->flush(); 4269} 4270 4271// Threads::print_on_error() is called by fatal error handler. It's possible 4272// that VM is not at safepoint and/or current thread is inside signal handler. 4273// Don't print stack trace, as the stack may not be walkable. Don't allocate 4274// memory (even in resource area), it might deadlock the error handler. 4275void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4276 int buflen) { 4277 bool found_current = false; 4278 st->print_cr("Java Threads: ( => current thread )"); 4279 ALL_JAVA_THREADS(thread) { 4280 bool is_current = (current == thread); 4281 found_current = found_current || is_current; 4282 4283 st->print("%s", is_current ? "=>" : " "); 4284 4285 st->print(PTR_FORMAT, thread); 4286 st->print(" "); 4287 thread->print_on_error(st, buf, buflen); 4288 st->cr(); 4289 } 4290 st->cr(); 4291 4292 st->print_cr("Other Threads:"); 4293 if (VMThread::vm_thread()) { 4294 bool is_current = (current == VMThread::vm_thread()); 4295 found_current = found_current || is_current; 4296 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4297 4298 st->print(PTR_FORMAT, VMThread::vm_thread()); 4299 st->print(" "); 4300 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4301 st->cr(); 4302 } 4303 WatcherThread* wt = WatcherThread::watcher_thread(); 4304 if (wt != NULL) { 4305 bool is_current = (current == wt); 4306 found_current = found_current || is_current; 4307 st->print("%s", is_current ? "=>" : " "); 4308 4309 st->print(PTR_FORMAT, wt); 4310 st->print(" "); 4311 wt->print_on_error(st, buf, buflen); 4312 st->cr(); 4313 } 4314 if (!found_current) { 4315 st->cr(); 4316 st->print("=>" PTR_FORMAT " (exited) ", current); 4317 current->print_on_error(st, buf, buflen); 4318 st->cr(); 4319 } 4320} 4321 4322// Internal SpinLock and Mutex 4323// Based on ParkEvent 4324 4325// Ad-hoc mutual exclusion primitives: SpinLock and Mux 4326// 4327// We employ SpinLocks _only for low-contention, fixed-length 4328// short-duration critical sections where we're concerned 4329// about native mutex_t or HotSpot Mutex:: latency. 4330// The mux construct provides a spin-then-block mutual exclusion 4331// mechanism. 4332// 4333// Testing has shown that contention on the ListLock guarding gFreeList 4334// is common. If we implement ListLock as a simple SpinLock it's common 4335// for the JVM to devolve to yielding with little progress. This is true 4336// despite the fact that the critical sections protected by ListLock are 4337// extremely short. 4338// 4339// TODO-FIXME: ListLock should be of type SpinLock. 4340// We should make this a 1st-class type, integrated into the lock 4341// hierarchy as leaf-locks. Critically, the SpinLock structure 4342// should have sufficient padding to avoid false-sharing and excessive 4343// cache-coherency traffic. 4344 4345 4346typedef volatile int SpinLockT; 4347 4348void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4349 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4350 return; // normal fast-path return 4351 } 4352 4353 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4354 TEVENT(SpinAcquire - ctx); 4355 int ctr = 0; 4356 int Yields = 0; 4357 for (;;) { 4358 while (*adr != 0) { 4359 ++ctr; 4360 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4361 if (Yields > 5) { 4362 os::naked_short_sleep(1); 4363 } else { 4364 os::naked_yield(); 4365 ++Yields; 4366 } 4367 } else { 4368 SpinPause(); 4369 } 4370 } 4371 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4372 } 4373} 4374 4375void Thread::SpinRelease(volatile int * adr) { 4376 assert(*adr != 0, "invariant"); 4377 OrderAccess::fence(); // guarantee at least release consistency. 4378 // Roach-motel semantics. 4379 // It's safe if subsequent LDs and STs float "up" into the critical section, 4380 // but prior LDs and STs within the critical section can't be allowed 4381 // to reorder or float past the ST that releases the lock. 4382 // Loads and stores in the critical section - which appear in program 4383 // order before the store that releases the lock - must also appear 4384 // before the store that releases the lock in memory visibility order. 4385 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4386 // the ST of 0 into the lock-word which releases the lock, so fence 4387 // more than covers this on all platforms. 4388 *adr = 0; 4389} 4390 4391// muxAcquire and muxRelease: 4392// 4393// * muxAcquire and muxRelease support a single-word lock-word construct. 4394// The LSB of the word is set IFF the lock is held. 4395// The remainder of the word points to the head of a singly-linked list 4396// of threads blocked on the lock. 4397// 4398// * The current implementation of muxAcquire-muxRelease uses its own 4399// dedicated Thread._MuxEvent instance. If we're interested in 4400// minimizing the peak number of extant ParkEvent instances then 4401// we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4402// as certain invariants were satisfied. Specifically, care would need 4403// to be taken with regards to consuming unpark() "permits". 4404// A safe rule of thumb is that a thread would never call muxAcquire() 4405// if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4406// park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4407// consume an unpark() permit intended for monitorenter, for instance. 4408// One way around this would be to widen the restricted-range semaphore 4409// implemented in park(). Another alternative would be to provide 4410// multiple instances of the PlatformEvent() for each thread. One 4411// instance would be dedicated to muxAcquire-muxRelease, for instance. 4412// 4413// * Usage: 4414// -- Only as leaf locks 4415// -- for short-term locking only as muxAcquire does not perform 4416// thread state transitions. 4417// 4418// Alternatives: 4419// * We could implement muxAcquire and muxRelease with MCS or CLH locks 4420// but with parking or spin-then-park instead of pure spinning. 4421// * Use Taura-Oyama-Yonenzawa locks. 4422// * It's possible to construct a 1-0 lock if we encode the lockword as 4423// (List,LockByte). Acquire will CAS the full lockword while Release 4424// will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4425// acquiring threads use timers (ParkTimed) to detect and recover from 4426// the stranding window. Thread/Node structures must be aligned on 256-byte 4427// boundaries by using placement-new. 4428// * Augment MCS with advisory back-link fields maintained with CAS(). 4429// Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4430// The validity of the backlinks must be ratified before we trust the value. 4431// If the backlinks are invalid the exiting thread must back-track through the 4432// the forward links, which are always trustworthy. 4433// * Add a successor indication. The LockWord is currently encoded as 4434// (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4435// to provide the usual futile-wakeup optimization. 4436// See RTStt for details. 4437// * Consider schedctl.sc_nopreempt to cover the critical section. 4438// 4439 4440 4441typedef volatile intptr_t MutexT; // Mux Lock-word 4442enum MuxBits { LOCKBIT = 1 }; 4443 4444void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4445 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4446 if (w == 0) return; 4447 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4448 return; 4449 } 4450 4451 TEVENT(muxAcquire - Contention); 4452 ParkEvent * const Self = Thread::current()->_MuxEvent; 4453 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4454 for (;;) { 4455 int its = (os::is_MP() ? 100 : 0) + 1; 4456 4457 // Optional spin phase: spin-then-park strategy 4458 while (--its >= 0) { 4459 w = *Lock; 4460 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4461 return; 4462 } 4463 } 4464 4465 Self->reset(); 4466 Self->OnList = intptr_t(Lock); 4467 // The following fence() isn't _strictly necessary as the subsequent 4468 // CAS() both serializes execution and ratifies the fetched *Lock value. 4469 OrderAccess::fence(); 4470 for (;;) { 4471 w = *Lock; 4472 if ((w & LOCKBIT) == 0) { 4473 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4474 Self->OnList = 0; // hygiene - allows stronger asserts 4475 return; 4476 } 4477 continue; // Interference -- *Lock changed -- Just retry 4478 } 4479 assert(w & LOCKBIT, "invariant"); 4480 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4481 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4482 } 4483 4484 while (Self->OnList != 0) { 4485 Self->park(); 4486 } 4487 } 4488} 4489 4490void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4491 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4492 if (w == 0) return; 4493 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4494 return; 4495 } 4496 4497 TEVENT(muxAcquire - Contention); 4498 ParkEvent * ReleaseAfter = NULL; 4499 if (ev == NULL) { 4500 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4501 } 4502 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4503 for (;;) { 4504 guarantee(ev->OnList == 0, "invariant"); 4505 int its = (os::is_MP() ? 100 : 0) + 1; 4506 4507 // Optional spin phase: spin-then-park strategy 4508 while (--its >= 0) { 4509 w = *Lock; 4510 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4511 if (ReleaseAfter != NULL) { 4512 ParkEvent::Release(ReleaseAfter); 4513 } 4514 return; 4515 } 4516 } 4517 4518 ev->reset(); 4519 ev->OnList = intptr_t(Lock); 4520 // The following fence() isn't _strictly necessary as the subsequent 4521 // CAS() both serializes execution and ratifies the fetched *Lock value. 4522 OrderAccess::fence(); 4523 for (;;) { 4524 w = *Lock; 4525 if ((w & LOCKBIT) == 0) { 4526 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4527 ev->OnList = 0; 4528 // We call ::Release while holding the outer lock, thus 4529 // artificially lengthening the critical section. 4530 // Consider deferring the ::Release() until the subsequent unlock(), 4531 // after we've dropped the outer lock. 4532 if (ReleaseAfter != NULL) { 4533 ParkEvent::Release(ReleaseAfter); 4534 } 4535 return; 4536 } 4537 continue; // Interference -- *Lock changed -- Just retry 4538 } 4539 assert(w & LOCKBIT, "invariant"); 4540 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4541 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4542 } 4543 4544 while (ev->OnList != 0) { 4545 ev->park(); 4546 } 4547 } 4548} 4549 4550// Release() must extract a successor from the list and then wake that thread. 4551// It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4552// similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4553// Release() would : 4554// (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4555// (B) Extract a successor from the private list "in-hand" 4556// (C) attempt to CAS() the residual back into *Lock over null. 4557// If there were any newly arrived threads and the CAS() would fail. 4558// In that case Release() would detach the RATs, re-merge the list in-hand 4559// with the RATs and repeat as needed. Alternately, Release() might 4560// detach and extract a successor, but then pass the residual list to the wakee. 4561// The wakee would be responsible for reattaching and remerging before it 4562// competed for the lock. 4563// 4564// Both "pop" and DMR are immune from ABA corruption -- there can be 4565// multiple concurrent pushers, but only one popper or detacher. 4566// This implementation pops from the head of the list. This is unfair, 4567// but tends to provide excellent throughput as hot threads remain hot. 4568// (We wake recently run threads first). 4569// 4570// All paths through muxRelease() will execute a CAS. 4571// Release consistency -- We depend on the CAS in muxRelease() to provide full 4572// bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4573// executed within the critical section are complete and globally visible before the 4574// store (CAS) to the lock-word that releases the lock becomes globally visible. 4575void Thread::muxRelease(volatile intptr_t * Lock) { 4576 for (;;) { 4577 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4578 assert(w & LOCKBIT, "invariant"); 4579 if (w == LOCKBIT) return; 4580 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4581 assert(List != NULL, "invariant"); 4582 assert(List->OnList == intptr_t(Lock), "invariant"); 4583 ParkEvent * const nxt = List->ListNext; 4584 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4585 4586 // The following CAS() releases the lock and pops the head element. 4587 // The CAS() also ratifies the previously fetched lock-word value. 4588 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4589 continue; 4590 } 4591 List->OnList = 0; 4592 OrderAccess::fence(); 4593 List->unpark(); 4594 return; 4595 } 4596} 4597 4598 4599void Threads::verify() { 4600 ALL_JAVA_THREADS(p) { 4601 p->verify(); 4602 } 4603 VMThread* thread = VMThread::vm_thread(); 4604 if (thread != NULL) thread->verify(); 4605} 4606