thread.cpp revision 7051:0420e825bb3c
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/task.hpp" 70#include "runtime/thread.inline.hpp" 71#include "runtime/threadCritical.hpp" 72#include "runtime/threadLocalStorage.hpp" 73#include "runtime/vframe.hpp" 74#include "runtime/vframeArray.hpp" 75#include "runtime/vframe_hp.hpp" 76#include "runtime/vmThread.hpp" 77#include "runtime/vm_operations.hpp" 78#include "runtime/vm_version.hpp" 79#include "services/attachListener.hpp" 80#include "services/management.hpp" 81#include "services/memTracker.hpp" 82#include "services/threadService.hpp" 83#include "trace/tracing.hpp" 84#include "trace/traceMacros.hpp" 85#include "utilities/defaultStream.hpp" 86#include "utilities/dtrace.hpp" 87#include "utilities/events.hpp" 88#include "utilities/preserveException.hpp" 89#include "utilities/macros.hpp" 90#if INCLUDE_ALL_GCS 91#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 92#include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 93#include "gc_implementation/parallelScavenge/pcTasks.hpp" 94#endif // INCLUDE_ALL_GCS 95#ifdef COMPILER1 96#include "c1/c1_Compiler.hpp" 97#endif 98#ifdef COMPILER2 99#include "opto/c2compiler.hpp" 100#include "opto/idealGraphPrinter.hpp" 101#endif 102#if INCLUDE_RTM_OPT 103#include "runtime/rtmLocking.hpp" 104#endif 105 106PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 107 108#ifdef DTRACE_ENABLED 109 110// Only bother with this argument setup if dtrace is available 111 112 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 113 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 114 115 #define DTRACE_THREAD_PROBE(probe, javathread) \ 116 { \ 117 ResourceMark rm(this); \ 118 int len = 0; \ 119 const char* name = (javathread)->get_thread_name(); \ 120 len = strlen(name); \ 121 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 122 (char *) name, len, \ 123 java_lang_Thread::thread_id((javathread)->threadObj()), \ 124 (uintptr_t) (javathread)->osthread()->thread_id(), \ 125 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 126 } 127 128#else // ndef DTRACE_ENABLED 129 130 #define DTRACE_THREAD_PROBE(probe, javathread) 131 132#endif // ndef DTRACE_ENABLED 133 134 135// Class hierarchy 136// - Thread 137// - VMThread 138// - WatcherThread 139// - ConcurrentMarkSweepThread 140// - JavaThread 141// - CompilerThread 142 143// ======= Thread ======== 144// Support for forcing alignment of thread objects for biased locking 145void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 146 if (UseBiasedLocking) { 147 const int alignment = markOopDesc::biased_lock_alignment; 148 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 149 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 150 : AllocateHeap(aligned_size, flags, CURRENT_PC, 151 AllocFailStrategy::RETURN_NULL); 152 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 153 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 154 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 155 "JavaThread alignment code overflowed allocated storage"); 156 if (TraceBiasedLocking) { 157 if (aligned_addr != real_malloc_addr) { 158 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 159 real_malloc_addr, aligned_addr); 160 } 161 } 162 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 163 return aligned_addr; 164 } else { 165 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 166 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 167 } 168} 169 170void Thread::operator delete(void* p) { 171 if (UseBiasedLocking) { 172 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 173 FreeHeap(real_malloc_addr, mtThread); 174 } else { 175 FreeHeap(p, mtThread); 176 } 177} 178 179 180// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 181// JavaThread 182 183 184Thread::Thread() { 185 // stack and get_thread 186 set_stack_base(NULL); 187 set_stack_size(0); 188 set_self_raw_id(0); 189 set_lgrp_id(-1); 190 191 // allocated data structures 192 set_osthread(NULL); 193 set_resource_area(new (mtThread)ResourceArea()); 194 DEBUG_ONLY(_current_resource_mark = NULL;) 195 set_handle_area(new (mtThread) HandleArea(NULL)); 196 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 197 set_active_handles(NULL); 198 set_free_handle_block(NULL); 199 set_last_handle_mark(NULL); 200 201 // This initial value ==> never claimed. 202 _oops_do_parity = 0; 203 204 // the handle mark links itself to last_handle_mark 205 new HandleMark(this); 206 207 // plain initialization 208 debug_only(_owned_locks = NULL;) 209 debug_only(_allow_allocation_count = 0;) 210 NOT_PRODUCT(_allow_safepoint_count = 0;) 211 NOT_PRODUCT(_skip_gcalot = false;) 212 _jvmti_env_iteration_count = 0; 213 set_allocated_bytes(0); 214 _vm_operation_started_count = 0; 215 _vm_operation_completed_count = 0; 216 _current_pending_monitor = NULL; 217 _current_pending_monitor_is_from_java = true; 218 _current_waiting_monitor = NULL; 219 _num_nested_signal = 0; 220 omFreeList = NULL; 221 omFreeCount = 0; 222 omFreeProvision = 32; 223 omInUseList = NULL; 224 omInUseCount = 0; 225 226#ifdef ASSERT 227 _visited_for_critical_count = false; 228#endif 229 230 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 231 _suspend_flags = 0; 232 233 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 234 _hashStateX = os::random(); 235 _hashStateY = 842502087; 236 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 237 _hashStateW = 273326509; 238 239 _OnTrap = 0; 240 _schedctl = NULL; 241 _Stalled = 0; 242 _TypeTag = 0x2BAD; 243 244 // Many of the following fields are effectively final - immutable 245 // Note that nascent threads can't use the Native Monitor-Mutex 246 // construct until the _MutexEvent is initialized ... 247 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 248 // we might instead use a stack of ParkEvents that we could provision on-demand. 249 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 250 // and ::Release() 251 _ParkEvent = ParkEvent::Allocate(this); 252 _SleepEvent = ParkEvent::Allocate(this); 253 _MutexEvent = ParkEvent::Allocate(this); 254 _MuxEvent = ParkEvent::Allocate(this); 255 256#ifdef CHECK_UNHANDLED_OOPS 257 if (CheckUnhandledOops) { 258 _unhandled_oops = new UnhandledOops(this); 259 } 260#endif // CHECK_UNHANDLED_OOPS 261#ifdef ASSERT 262 if (UseBiasedLocking) { 263 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 264 assert(this == _real_malloc_address || 265 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 266 "bug in forced alignment of thread objects"); 267 } 268#endif // ASSERT 269} 270 271void Thread::initialize_thread_local_storage() { 272 // Note: Make sure this method only calls 273 // non-blocking operations. Otherwise, it might not work 274 // with the thread-startup/safepoint interaction. 275 276 // During Java thread startup, safepoint code should allow this 277 // method to complete because it may need to allocate memory to 278 // store information for the new thread. 279 280 // initialize structure dependent on thread local storage 281 ThreadLocalStorage::set_thread(this); 282} 283 284void Thread::record_stack_base_and_size() { 285 set_stack_base(os::current_stack_base()); 286 set_stack_size(os::current_stack_size()); 287 if (is_Java_thread()) { 288 ((JavaThread*) this)->set_stack_overflow_limit(); 289 } 290 // CR 7190089: on Solaris, primordial thread's stack is adjusted 291 // in initialize_thread(). Without the adjustment, stack size is 292 // incorrect if stack is set to unlimited (ulimit -s unlimited). 293 // So far, only Solaris has real implementation of initialize_thread(). 294 // 295 // set up any platform-specific state. 296 os::initialize_thread(this); 297 298#if INCLUDE_NMT 299 // record thread's native stack, stack grows downward 300 address stack_low_addr = stack_base() - stack_size(); 301 MemTracker::record_thread_stack(stack_low_addr, stack_size()); 302#endif // INCLUDE_NMT 303} 304 305 306Thread::~Thread() { 307 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 308 ObjectSynchronizer::omFlush(this); 309 310 EVENT_THREAD_DESTRUCT(this); 311 312 // stack_base can be NULL if the thread is never started or exited before 313 // record_stack_base_and_size called. Although, we would like to ensure 314 // that all started threads do call record_stack_base_and_size(), there is 315 // not proper way to enforce that. 316#if INCLUDE_NMT 317 if (_stack_base != NULL) { 318 address low_stack_addr = stack_base() - stack_size(); 319 MemTracker::release_thread_stack(low_stack_addr, stack_size()); 320#ifdef ASSERT 321 set_stack_base(NULL); 322#endif 323 } 324#endif // INCLUDE_NMT 325 326 // deallocate data structures 327 delete resource_area(); 328 // since the handle marks are using the handle area, we have to deallocated the root 329 // handle mark before deallocating the thread's handle area, 330 assert(last_handle_mark() != NULL, "check we have an element"); 331 delete last_handle_mark(); 332 assert(last_handle_mark() == NULL, "check we have reached the end"); 333 334 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 335 // We NULL out the fields for good hygiene. 336 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 337 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 338 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 339 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 340 341 delete handle_area(); 342 delete metadata_handles(); 343 344 // osthread() can be NULL, if creation of thread failed. 345 if (osthread() != NULL) os::free_thread(osthread()); 346 347 delete _SR_lock; 348 349 // clear thread local storage if the Thread is deleting itself 350 if (this == Thread::current()) { 351 ThreadLocalStorage::set_thread(NULL); 352 } else { 353 // In the case where we're not the current thread, invalidate all the 354 // caches in case some code tries to get the current thread or the 355 // thread that was destroyed, and gets stale information. 356 ThreadLocalStorage::invalidate_all(); 357 } 358 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 359} 360 361// NOTE: dummy function for assertion purpose. 362void Thread::run() { 363 ShouldNotReachHere(); 364} 365 366#ifdef ASSERT 367// Private method to check for dangling thread pointer 368void check_for_dangling_thread_pointer(Thread *thread) { 369 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 370 "possibility of dangling Thread pointer"); 371} 372#endif 373 374 375#ifndef PRODUCT 376// Tracing method for basic thread operations 377void Thread::trace(const char* msg, const Thread* const thread) { 378 if (!TraceThreadEvents) return; 379 ResourceMark rm; 380 ThreadCritical tc; 381 const char *name = "non-Java thread"; 382 int prio = -1; 383 if (thread->is_Java_thread() 384 && !thread->is_Compiler_thread()) { 385 // The Threads_lock must be held to get information about 386 // this thread but may not be in some situations when 387 // tracing thread events. 388 bool release_Threads_lock = false; 389 if (!Threads_lock->owned_by_self()) { 390 Threads_lock->lock(); 391 release_Threads_lock = true; 392 } 393 JavaThread* jt = (JavaThread *)thread; 394 name = (char *)jt->get_thread_name(); 395 oop thread_oop = jt->threadObj(); 396 if (thread_oop != NULL) { 397 prio = java_lang_Thread::priority(thread_oop); 398 } 399 if (release_Threads_lock) { 400 Threads_lock->unlock(); 401 } 402 } 403 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 404} 405#endif 406 407 408ThreadPriority Thread::get_priority(const Thread* const thread) { 409 trace("get priority", thread); 410 ThreadPriority priority; 411 // Can return an error! 412 (void)os::get_priority(thread, priority); 413 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 414 return priority; 415} 416 417void Thread::set_priority(Thread* thread, ThreadPriority priority) { 418 trace("set priority", thread); 419 debug_only(check_for_dangling_thread_pointer(thread);) 420 // Can return an error! 421 (void)os::set_priority(thread, priority); 422} 423 424 425void Thread::start(Thread* thread) { 426 trace("start", thread); 427 // Start is different from resume in that its safety is guaranteed by context or 428 // being called from a Java method synchronized on the Thread object. 429 if (!DisableStartThread) { 430 if (thread->is_Java_thread()) { 431 // Initialize the thread state to RUNNABLE before starting this thread. 432 // Can not set it after the thread started because we do not know the 433 // exact thread state at that time. It could be in MONITOR_WAIT or 434 // in SLEEPING or some other state. 435 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 436 java_lang_Thread::RUNNABLE); 437 } 438 os::start_thread(thread); 439 } 440} 441 442// Enqueue a VM_Operation to do the job for us - sometime later 443void Thread::send_async_exception(oop java_thread, oop java_throwable) { 444 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 445 VMThread::execute(vm_stop); 446} 447 448 449// Check if an external suspend request has completed (or has been 450// cancelled). Returns true if the thread is externally suspended and 451// false otherwise. 452// 453// The bits parameter returns information about the code path through 454// the routine. Useful for debugging: 455// 456// set in is_ext_suspend_completed(): 457// 0x00000001 - routine was entered 458// 0x00000010 - routine return false at end 459// 0x00000100 - thread exited (return false) 460// 0x00000200 - suspend request cancelled (return false) 461// 0x00000400 - thread suspended (return true) 462// 0x00001000 - thread is in a suspend equivalent state (return true) 463// 0x00002000 - thread is native and walkable (return true) 464// 0x00004000 - thread is native_trans and walkable (needed retry) 465// 466// set in wait_for_ext_suspend_completion(): 467// 0x00010000 - routine was entered 468// 0x00020000 - suspend request cancelled before loop (return false) 469// 0x00040000 - thread suspended before loop (return true) 470// 0x00080000 - suspend request cancelled in loop (return false) 471// 0x00100000 - thread suspended in loop (return true) 472// 0x00200000 - suspend not completed during retry loop (return false) 473 474// Helper class for tracing suspend wait debug bits. 475// 476// 0x00000100 indicates that the target thread exited before it could 477// self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 478// 0x00080000 each indicate a cancelled suspend request so they don't 479// count as wait failures either. 480#define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 481 482class TraceSuspendDebugBits : public StackObj { 483 private: 484 JavaThread * jt; 485 bool is_wait; 486 bool called_by_wait; // meaningful when !is_wait 487 uint32_t * bits; 488 489 public: 490 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 491 uint32_t *_bits) { 492 jt = _jt; 493 is_wait = _is_wait; 494 called_by_wait = _called_by_wait; 495 bits = _bits; 496 } 497 498 ~TraceSuspendDebugBits() { 499 if (!is_wait) { 500#if 1 501 // By default, don't trace bits for is_ext_suspend_completed() calls. 502 // That trace is very chatty. 503 return; 504#else 505 if (!called_by_wait) { 506 // If tracing for is_ext_suspend_completed() is enabled, then only 507 // trace calls to it from wait_for_ext_suspend_completion() 508 return; 509 } 510#endif 511 } 512 513 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 514 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 515 MutexLocker ml(Threads_lock); // needed for get_thread_name() 516 ResourceMark rm; 517 518 tty->print_cr( 519 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 520 jt->get_thread_name(), *bits); 521 522 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 523 } 524 } 525 } 526}; 527#undef DEBUG_FALSE_BITS 528 529 530bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 531 uint32_t *bits) { 532 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 533 534 bool did_trans_retry = false; // only do thread_in_native_trans retry once 535 bool do_trans_retry; // flag to force the retry 536 537 *bits |= 0x00000001; 538 539 do { 540 do_trans_retry = false; 541 542 if (is_exiting()) { 543 // Thread is in the process of exiting. This is always checked 544 // first to reduce the risk of dereferencing a freed JavaThread. 545 *bits |= 0x00000100; 546 return false; 547 } 548 549 if (!is_external_suspend()) { 550 // Suspend request is cancelled. This is always checked before 551 // is_ext_suspended() to reduce the risk of a rogue resume 552 // confusing the thread that made the suspend request. 553 *bits |= 0x00000200; 554 return false; 555 } 556 557 if (is_ext_suspended()) { 558 // thread is suspended 559 *bits |= 0x00000400; 560 return true; 561 } 562 563 // Now that we no longer do hard suspends of threads running 564 // native code, the target thread can be changing thread state 565 // while we are in this routine: 566 // 567 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 568 // 569 // We save a copy of the thread state as observed at this moment 570 // and make our decision about suspend completeness based on the 571 // copy. This closes the race where the thread state is seen as 572 // _thread_in_native_trans in the if-thread_blocked check, but is 573 // seen as _thread_blocked in if-thread_in_native_trans check. 574 JavaThreadState save_state = thread_state(); 575 576 if (save_state == _thread_blocked && is_suspend_equivalent()) { 577 // If the thread's state is _thread_blocked and this blocking 578 // condition is known to be equivalent to a suspend, then we can 579 // consider the thread to be externally suspended. This means that 580 // the code that sets _thread_blocked has been modified to do 581 // self-suspension if the blocking condition releases. We also 582 // used to check for CONDVAR_WAIT here, but that is now covered by 583 // the _thread_blocked with self-suspension check. 584 // 585 // Return true since we wouldn't be here unless there was still an 586 // external suspend request. 587 *bits |= 0x00001000; 588 return true; 589 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 590 // Threads running native code will self-suspend on native==>VM/Java 591 // transitions. If its stack is walkable (should always be the case 592 // unless this function is called before the actual java_suspend() 593 // call), then the wait is done. 594 *bits |= 0x00002000; 595 return true; 596 } else if (!called_by_wait && !did_trans_retry && 597 save_state == _thread_in_native_trans && 598 frame_anchor()->walkable()) { 599 // The thread is transitioning from thread_in_native to another 600 // thread state. check_safepoint_and_suspend_for_native_trans() 601 // will force the thread to self-suspend. If it hasn't gotten 602 // there yet we may have caught the thread in-between the native 603 // code check above and the self-suspend. Lucky us. If we were 604 // called by wait_for_ext_suspend_completion(), then it 605 // will be doing the retries so we don't have to. 606 // 607 // Since we use the saved thread state in the if-statement above, 608 // there is a chance that the thread has already transitioned to 609 // _thread_blocked by the time we get here. In that case, we will 610 // make a single unnecessary pass through the logic below. This 611 // doesn't hurt anything since we still do the trans retry. 612 613 *bits |= 0x00004000; 614 615 // Once the thread leaves thread_in_native_trans for another 616 // thread state, we break out of this retry loop. We shouldn't 617 // need this flag to prevent us from getting back here, but 618 // sometimes paranoia is good. 619 did_trans_retry = true; 620 621 // We wait for the thread to transition to a more usable state. 622 for (int i = 1; i <= SuspendRetryCount; i++) { 623 // We used to do an "os::yield_all(i)" call here with the intention 624 // that yielding would increase on each retry. However, the parameter 625 // is ignored on Linux which means the yield didn't scale up. Waiting 626 // on the SR_lock below provides a much more predictable scale up for 627 // the delay. It also provides a simple/direct point to check for any 628 // safepoint requests from the VMThread 629 630 // temporarily drops SR_lock while doing wait with safepoint check 631 // (if we're a JavaThread - the WatcherThread can also call this) 632 // and increase delay with each retry 633 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 634 635 // check the actual thread state instead of what we saved above 636 if (thread_state() != _thread_in_native_trans) { 637 // the thread has transitioned to another thread state so 638 // try all the checks (except this one) one more time. 639 do_trans_retry = true; 640 break; 641 } 642 } // end retry loop 643 644 645 } 646 } while (do_trans_retry); 647 648 *bits |= 0x00000010; 649 return false; 650} 651 652// Wait for an external suspend request to complete (or be cancelled). 653// Returns true if the thread is externally suspended and false otherwise. 654// 655bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 656 uint32_t *bits) { 657 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 658 false /* !called_by_wait */, bits); 659 660 // local flag copies to minimize SR_lock hold time 661 bool is_suspended; 662 bool pending; 663 uint32_t reset_bits; 664 665 // set a marker so is_ext_suspend_completed() knows we are the caller 666 *bits |= 0x00010000; 667 668 // We use reset_bits to reinitialize the bits value at the top of 669 // each retry loop. This allows the caller to make use of any 670 // unused bits for their own marking purposes. 671 reset_bits = *bits; 672 673 { 674 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 675 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 676 delay, bits); 677 pending = is_external_suspend(); 678 } 679 // must release SR_lock to allow suspension to complete 680 681 if (!pending) { 682 // A cancelled suspend request is the only false return from 683 // is_ext_suspend_completed() that keeps us from entering the 684 // retry loop. 685 *bits |= 0x00020000; 686 return false; 687 } 688 689 if (is_suspended) { 690 *bits |= 0x00040000; 691 return true; 692 } 693 694 for (int i = 1; i <= retries; i++) { 695 *bits = reset_bits; // reinit to only track last retry 696 697 // We used to do an "os::yield_all(i)" call here with the intention 698 // that yielding would increase on each retry. However, the parameter 699 // is ignored on Linux which means the yield didn't scale up. Waiting 700 // on the SR_lock below provides a much more predictable scale up for 701 // the delay. It also provides a simple/direct point to check for any 702 // safepoint requests from the VMThread 703 704 { 705 MutexLocker ml(SR_lock()); 706 // wait with safepoint check (if we're a JavaThread - the WatcherThread 707 // can also call this) and increase delay with each retry 708 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 709 710 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 711 delay, bits); 712 713 // It is possible for the external suspend request to be cancelled 714 // (by a resume) before the actual suspend operation is completed. 715 // Refresh our local copy to see if we still need to wait. 716 pending = is_external_suspend(); 717 } 718 719 if (!pending) { 720 // A cancelled suspend request is the only false return from 721 // is_ext_suspend_completed() that keeps us from staying in the 722 // retry loop. 723 *bits |= 0x00080000; 724 return false; 725 } 726 727 if (is_suspended) { 728 *bits |= 0x00100000; 729 return true; 730 } 731 } // end retry loop 732 733 // thread did not suspend after all our retries 734 *bits |= 0x00200000; 735 return false; 736} 737 738#ifndef PRODUCT 739void JavaThread::record_jump(address target, address instr, const char* file, 740 int line) { 741 742 // This should not need to be atomic as the only way for simultaneous 743 // updates is via interrupts. Even then this should be rare or non-existent 744 // and we don't care that much anyway. 745 746 int index = _jmp_ring_index; 747 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 748 _jmp_ring[index]._target = (intptr_t) target; 749 _jmp_ring[index]._instruction = (intptr_t) instr; 750 _jmp_ring[index]._file = file; 751 _jmp_ring[index]._line = line; 752} 753#endif // PRODUCT 754 755// Called by flat profiler 756// Callers have already called wait_for_ext_suspend_completion 757// The assertion for that is currently too complex to put here: 758bool JavaThread::profile_last_Java_frame(frame* _fr) { 759 bool gotframe = false; 760 // self suspension saves needed state. 761 if (has_last_Java_frame() && _anchor.walkable()) { 762 *_fr = pd_last_frame(); 763 gotframe = true; 764 } 765 return gotframe; 766} 767 768void Thread::interrupt(Thread* thread) { 769 trace("interrupt", thread); 770 debug_only(check_for_dangling_thread_pointer(thread);) 771 os::interrupt(thread); 772} 773 774bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 775 trace("is_interrupted", thread); 776 debug_only(check_for_dangling_thread_pointer(thread);) 777 // Note: If clear_interrupted==false, this simply fetches and 778 // returns the value of the field osthread()->interrupted(). 779 return os::is_interrupted(thread, clear_interrupted); 780} 781 782 783// GC Support 784bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 785 jint thread_parity = _oops_do_parity; 786 if (thread_parity != strong_roots_parity) { 787 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 788 if (res == thread_parity) { 789 return true; 790 } else { 791 guarantee(res == strong_roots_parity, "Or else what?"); 792 assert(SharedHeap::heap()->workers()->active_workers() > 0, 793 "Should only fail when parallel."); 794 return false; 795 } 796 } 797 assert(SharedHeap::heap()->workers()->active_workers() > 0, 798 "Should only fail when parallel."); 799 return false; 800} 801 802void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 803 active_handles()->oops_do(f); 804 // Do oop for ThreadShadow 805 f->do_oop((oop*)&_pending_exception); 806 handle_area()->oops_do(f); 807} 808 809void Thread::nmethods_do(CodeBlobClosure* cf) { 810 // no nmethods in a generic thread... 811} 812 813void Thread::metadata_do(void f(Metadata*)) { 814 if (metadata_handles() != NULL) { 815 for (int i = 0; i< metadata_handles()->length(); i++) { 816 f(metadata_handles()->at(i)); 817 } 818 } 819} 820 821void Thread::print_on(outputStream* st) const { 822 // get_priority assumes osthread initialized 823 if (osthread() != NULL) { 824 int os_prio; 825 if (os::get_native_priority(this, &os_prio) == OS_OK) { 826 st->print("os_prio=%d ", os_prio); 827 } 828 st->print("tid=" INTPTR_FORMAT " ", this); 829 osthread()->print_on(st); 830 } 831 debug_only(if (WizardMode) print_owned_locks_on(st);) 832} 833 834// Thread::print_on_error() is called by fatal error handler. Don't use 835// any lock or allocate memory. 836void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 837 if (is_VM_thread()) st->print("VMThread"); 838 else if (is_Compiler_thread()) st->print("CompilerThread"); 839 else if (is_Java_thread()) st->print("JavaThread"); 840 else if (is_GC_task_thread()) st->print("GCTaskThread"); 841 else if (is_Watcher_thread()) st->print("WatcherThread"); 842 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 843 else st->print("Thread"); 844 845 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 846 _stack_base - _stack_size, _stack_base); 847 848 if (osthread()) { 849 st->print(" [id=%d]", osthread()->thread_id()); 850 } 851} 852 853#ifdef ASSERT 854void Thread::print_owned_locks_on(outputStream* st) const { 855 Monitor *cur = _owned_locks; 856 if (cur == NULL) { 857 st->print(" (no locks) "); 858 } else { 859 st->print_cr(" Locks owned:"); 860 while (cur) { 861 cur->print_on(st); 862 cur = cur->next(); 863 } 864 } 865} 866 867static int ref_use_count = 0; 868 869bool Thread::owns_locks_but_compiled_lock() const { 870 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 871 if (cur != Compile_lock) return true; 872 } 873 return false; 874} 875 876 877#endif 878 879#ifndef PRODUCT 880 881// The flag: potential_vm_operation notifies if this particular safepoint state could potential 882// invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 883// no threads which allow_vm_block's are held 884void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 885 // Check if current thread is allowed to block at a safepoint 886 if (!(_allow_safepoint_count == 0)) { 887 fatal("Possible safepoint reached by thread that does not allow it"); 888 } 889 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 890 fatal("LEAF method calling lock?"); 891 } 892 893#ifdef ASSERT 894 if (potential_vm_operation && is_Java_thread() 895 && !Universe::is_bootstrapping()) { 896 // Make sure we do not hold any locks that the VM thread also uses. 897 // This could potentially lead to deadlocks 898 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 899 // Threads_lock is special, since the safepoint synchronization will not start before this is 900 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 901 // since it is used to transfer control between JavaThreads and the VMThread 902 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 903 if ((cur->allow_vm_block() && 904 cur != Threads_lock && 905 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 906 cur != VMOperationRequest_lock && 907 cur != VMOperationQueue_lock) || 908 cur->rank() == Mutex::special) { 909 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name())); 910 } 911 } 912 } 913 914 if (GCALotAtAllSafepoints) { 915 // We could enter a safepoint here and thus have a gc 916 InterfaceSupport::check_gc_alot(); 917 } 918#endif 919} 920#endif 921 922bool Thread::is_in_stack(address adr) const { 923 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 924 address end = os::current_stack_pointer(); 925 // Allow non Java threads to call this without stack_base 926 if (_stack_base == NULL) return true; 927 if (stack_base() >= adr && adr >= end) return true; 928 929 return false; 930} 931 932 933bool Thread::is_in_usable_stack(address adr) const { 934 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0; 935 size_t usable_stack_size = _stack_size - stack_guard_size; 936 937 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 938} 939 940 941// We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 942// However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 943// used for compilation in the future. If that change is made, the need for these methods 944// should be revisited, and they should be removed if possible. 945 946bool Thread::is_lock_owned(address adr) const { 947 return on_local_stack(adr); 948} 949 950bool Thread::set_as_starting_thread() { 951 // NOTE: this must be called inside the main thread. 952 return os::create_main_thread((JavaThread*)this); 953} 954 955static void initialize_class(Symbol* class_name, TRAPS) { 956 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 957 InstanceKlass::cast(klass)->initialize(CHECK); 958} 959 960 961// Creates the initial ThreadGroup 962static Handle create_initial_thread_group(TRAPS) { 963 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 964 instanceKlassHandle klass (THREAD, k); 965 966 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 967 { 968 JavaValue result(T_VOID); 969 JavaCalls::call_special(&result, 970 system_instance, 971 klass, 972 vmSymbols::object_initializer_name(), 973 vmSymbols::void_method_signature(), 974 CHECK_NH); 975 } 976 Universe::set_system_thread_group(system_instance()); 977 978 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 979 { 980 JavaValue result(T_VOID); 981 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 982 JavaCalls::call_special(&result, 983 main_instance, 984 klass, 985 vmSymbols::object_initializer_name(), 986 vmSymbols::threadgroup_string_void_signature(), 987 system_instance, 988 string, 989 CHECK_NH); 990 } 991 return main_instance; 992} 993 994// Creates the initial Thread 995static oop create_initial_thread(Handle thread_group, JavaThread* thread, 996 TRAPS) { 997 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 998 instanceKlassHandle klass (THREAD, k); 999 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 1000 1001 java_lang_Thread::set_thread(thread_oop(), thread); 1002 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1003 thread->set_threadObj(thread_oop()); 1004 1005 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1006 1007 JavaValue result(T_VOID); 1008 JavaCalls::call_special(&result, thread_oop, 1009 klass, 1010 vmSymbols::object_initializer_name(), 1011 vmSymbols::threadgroup_string_void_signature(), 1012 thread_group, 1013 string, 1014 CHECK_NULL); 1015 return thread_oop(); 1016} 1017 1018static void call_initializeSystemClass(TRAPS) { 1019 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1020 instanceKlassHandle klass (THREAD, k); 1021 1022 JavaValue result(T_VOID); 1023 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 1024 vmSymbols::void_method_signature(), CHECK); 1025} 1026 1027char java_runtime_name[128] = ""; 1028char java_runtime_version[128] = ""; 1029 1030// extract the JRE name from sun.misc.Version.java_runtime_name 1031static const char* get_java_runtime_name(TRAPS) { 1032 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1033 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1034 fieldDescriptor fd; 1035 bool found = k != NULL && 1036 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1037 vmSymbols::string_signature(), &fd); 1038 if (found) { 1039 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1040 if (name_oop == NULL) { 1041 return NULL; 1042 } 1043 const char* name = java_lang_String::as_utf8_string(name_oop, 1044 java_runtime_name, 1045 sizeof(java_runtime_name)); 1046 return name; 1047 } else { 1048 return NULL; 1049 } 1050} 1051 1052// extract the JRE version from sun.misc.Version.java_runtime_version 1053static const char* get_java_runtime_version(TRAPS) { 1054 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1055 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1056 fieldDescriptor fd; 1057 bool found = k != NULL && 1058 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1059 vmSymbols::string_signature(), &fd); 1060 if (found) { 1061 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1062 if (name_oop == NULL) { 1063 return NULL; 1064 } 1065 const char* name = java_lang_String::as_utf8_string(name_oop, 1066 java_runtime_version, 1067 sizeof(java_runtime_version)); 1068 return name; 1069 } else { 1070 return NULL; 1071 } 1072} 1073 1074// General purpose hook into Java code, run once when the VM is initialized. 1075// The Java library method itself may be changed independently from the VM. 1076static void call_postVMInitHook(TRAPS) { 1077 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1078 instanceKlassHandle klass (THREAD, k); 1079 if (klass.not_null()) { 1080 JavaValue result(T_VOID); 1081 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1082 vmSymbols::void_method_signature(), 1083 CHECK); 1084 } 1085} 1086 1087static void reset_vm_info_property(TRAPS) { 1088 // the vm info string 1089 ResourceMark rm(THREAD); 1090 const char *vm_info = VM_Version::vm_info_string(); 1091 1092 // java.lang.System class 1093 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1094 instanceKlassHandle klass (THREAD, k); 1095 1096 // setProperty arguments 1097 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1098 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1099 1100 // return value 1101 JavaValue r(T_OBJECT); 1102 1103 // public static String setProperty(String key, String value); 1104 JavaCalls::call_static(&r, 1105 klass, 1106 vmSymbols::setProperty_name(), 1107 vmSymbols::string_string_string_signature(), 1108 key_str, 1109 value_str, 1110 CHECK); 1111} 1112 1113 1114void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, 1115 bool daemon, TRAPS) { 1116 assert(thread_group.not_null(), "thread group should be specified"); 1117 assert(threadObj() == NULL, "should only create Java thread object once"); 1118 1119 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1120 instanceKlassHandle klass (THREAD, k); 1121 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1122 1123 java_lang_Thread::set_thread(thread_oop(), this); 1124 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1125 set_threadObj(thread_oop()); 1126 1127 JavaValue result(T_VOID); 1128 if (thread_name != NULL) { 1129 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1130 // Thread gets assigned specified name and null target 1131 JavaCalls::call_special(&result, 1132 thread_oop, 1133 klass, 1134 vmSymbols::object_initializer_name(), 1135 vmSymbols::threadgroup_string_void_signature(), 1136 thread_group, // Argument 1 1137 name, // Argument 2 1138 THREAD); 1139 } else { 1140 // Thread gets assigned name "Thread-nnn" and null target 1141 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1142 JavaCalls::call_special(&result, 1143 thread_oop, 1144 klass, 1145 vmSymbols::object_initializer_name(), 1146 vmSymbols::threadgroup_runnable_void_signature(), 1147 thread_group, // Argument 1 1148 Handle(), // Argument 2 1149 THREAD); 1150 } 1151 1152 1153 if (daemon) { 1154 java_lang_Thread::set_daemon(thread_oop()); 1155 } 1156 1157 if (HAS_PENDING_EXCEPTION) { 1158 return; 1159 } 1160 1161 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1162 Handle threadObj(this, this->threadObj()); 1163 1164 JavaCalls::call_special(&result, 1165 thread_group, 1166 group, 1167 vmSymbols::add_method_name(), 1168 vmSymbols::thread_void_signature(), 1169 threadObj, // Arg 1 1170 THREAD); 1171 1172 1173} 1174 1175// NamedThread -- non-JavaThread subclasses with multiple 1176// uniquely named instances should derive from this. 1177NamedThread::NamedThread() : Thread() { 1178 _name = NULL; 1179 _processed_thread = NULL; 1180} 1181 1182NamedThread::~NamedThread() { 1183 if (_name != NULL) { 1184 FREE_C_HEAP_ARRAY(char, _name, mtThread); 1185 _name = NULL; 1186 } 1187} 1188 1189void NamedThread::set_name(const char* format, ...) { 1190 guarantee(_name == NULL, "Only get to set name once."); 1191 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1192 guarantee(_name != NULL, "alloc failure"); 1193 va_list ap; 1194 va_start(ap, format); 1195 jio_vsnprintf(_name, max_name_len, format, ap); 1196 va_end(ap); 1197} 1198 1199void NamedThread::print_on(outputStream* st) const { 1200 st->print("\"%s\" ", name()); 1201 Thread::print_on(st); 1202 st->cr(); 1203} 1204 1205 1206// ======= WatcherThread ======== 1207 1208// The watcher thread exists to simulate timer interrupts. It should 1209// be replaced by an abstraction over whatever native support for 1210// timer interrupts exists on the platform. 1211 1212WatcherThread* WatcherThread::_watcher_thread = NULL; 1213bool WatcherThread::_startable = false; 1214volatile bool WatcherThread::_should_terminate = false; 1215 1216WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1217 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1218 if (os::create_thread(this, os::watcher_thread)) { 1219 _watcher_thread = this; 1220 1221 // Set the watcher thread to the highest OS priority which should not be 1222 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1223 // is created. The only normal thread using this priority is the reference 1224 // handler thread, which runs for very short intervals only. 1225 // If the VMThread's priority is not lower than the WatcherThread profiling 1226 // will be inaccurate. 1227 os::set_priority(this, MaxPriority); 1228 if (!DisableStartThread) { 1229 os::start_thread(this); 1230 } 1231 } 1232} 1233 1234int WatcherThread::sleep() const { 1235 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1236 1237 // remaining will be zero if there are no tasks, 1238 // causing the WatcherThread to sleep until a task is 1239 // enrolled 1240 int remaining = PeriodicTask::time_to_wait(); 1241 int time_slept = 0; 1242 1243 // we expect this to timeout - we only ever get unparked when 1244 // we should terminate or when a new task has been enrolled 1245 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1246 1247 jlong time_before_loop = os::javaTimeNanos(); 1248 1249 for (;;) { 1250 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining); 1251 jlong now = os::javaTimeNanos(); 1252 1253 if (remaining == 0) { 1254 // if we didn't have any tasks we could have waited for a long time 1255 // consider the time_slept zero and reset time_before_loop 1256 time_slept = 0; 1257 time_before_loop = now; 1258 } else { 1259 // need to recalculate since we might have new tasks in _tasks 1260 time_slept = (int) ((now - time_before_loop) / 1000000); 1261 } 1262 1263 // Change to task list or spurious wakeup of some kind 1264 if (timedout || _should_terminate) { 1265 break; 1266 } 1267 1268 remaining = PeriodicTask::time_to_wait(); 1269 if (remaining == 0) { 1270 // Last task was just disenrolled so loop around and wait until 1271 // another task gets enrolled 1272 continue; 1273 } 1274 1275 remaining -= time_slept; 1276 if (remaining <= 0) { 1277 break; 1278 } 1279 } 1280 1281 return time_slept; 1282} 1283 1284void WatcherThread::run() { 1285 assert(this == watcher_thread(), "just checking"); 1286 1287 this->record_stack_base_and_size(); 1288 this->initialize_thread_local_storage(); 1289 this->set_active_handles(JNIHandleBlock::allocate_block()); 1290 while (!_should_terminate) { 1291 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1292 assert(watcher_thread() == this, "thread consistency check"); 1293 1294 // Calculate how long it'll be until the next PeriodicTask work 1295 // should be done, and sleep that amount of time. 1296 int time_waited = sleep(); 1297 1298 if (is_error_reported()) { 1299 // A fatal error has happened, the error handler(VMError::report_and_die) 1300 // should abort JVM after creating an error log file. However in some 1301 // rare cases, the error handler itself might deadlock. Here we try to 1302 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1303 // 1304 // This code is in WatcherThread because WatcherThread wakes up 1305 // periodically so the fatal error handler doesn't need to do anything; 1306 // also because the WatcherThread is less likely to crash than other 1307 // threads. 1308 1309 for (;;) { 1310 if (!ShowMessageBoxOnError 1311 && (OnError == NULL || OnError[0] == '\0') 1312 && Arguments::abort_hook() == NULL) { 1313 os::sleep(this, 2 * 60 * 1000, false); 1314 fdStream err(defaultStream::output_fd()); 1315 err.print_raw_cr("# [ timer expired, abort... ]"); 1316 // skip atexit/vm_exit/vm_abort hooks 1317 os::die(); 1318 } 1319 1320 // Wake up 5 seconds later, the fatal handler may reset OnError or 1321 // ShowMessageBoxOnError when it is ready to abort. 1322 os::sleep(this, 5 * 1000, false); 1323 } 1324 } 1325 1326 PeriodicTask::real_time_tick(time_waited); 1327 } 1328 1329 // Signal that it is terminated 1330 { 1331 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1332 _watcher_thread = NULL; 1333 Terminator_lock->notify(); 1334 } 1335 1336 // Thread destructor usually does this.. 1337 ThreadLocalStorage::set_thread(NULL); 1338} 1339 1340void WatcherThread::start() { 1341 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1342 1343 if (watcher_thread() == NULL && _startable) { 1344 _should_terminate = false; 1345 // Create the single instance of WatcherThread 1346 new WatcherThread(); 1347 } 1348} 1349 1350void WatcherThread::make_startable() { 1351 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1352 _startable = true; 1353} 1354 1355void WatcherThread::stop() { 1356 // Get the PeriodicTask_lock if we can. If we cannot, then the 1357 // WatcherThread is using it and we don't want to block on that lock 1358 // here because that might cause a safepoint deadlock depending on 1359 // what the current WatcherThread tasks are doing. 1360 bool have_lock = PeriodicTask_lock->try_lock(); 1361 1362 _should_terminate = true; 1363 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1364 1365 if (have_lock) { 1366 WatcherThread* watcher = watcher_thread(); 1367 if (watcher != NULL) { 1368 // If we managed to get the lock, then we should unpark the 1369 // WatcherThread so that it can see we want it to stop. 1370 watcher->unpark(); 1371 } 1372 1373 PeriodicTask_lock->unlock(); 1374 } 1375 1376 // it is ok to take late safepoints here, if needed 1377 MutexLocker mu(Terminator_lock); 1378 1379 while (watcher_thread() != NULL) { 1380 // This wait should make safepoint checks, wait without a timeout, 1381 // and wait as a suspend-equivalent condition. 1382 // 1383 // Note: If the FlatProfiler is running, then this thread is waiting 1384 // for the WatcherThread to terminate and the WatcherThread, via the 1385 // FlatProfiler task, is waiting for the external suspend request on 1386 // this thread to complete. wait_for_ext_suspend_completion() will 1387 // eventually timeout, but that takes time. Making this wait a 1388 // suspend-equivalent condition solves that timeout problem. 1389 // 1390 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1391 Mutex::_as_suspend_equivalent_flag); 1392 } 1393} 1394 1395void WatcherThread::unpark() { 1396 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() 1397 ? NULL 1398 : PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1399 PeriodicTask_lock->notify(); 1400} 1401 1402void WatcherThread::print_on(outputStream* st) const { 1403 st->print("\"%s\" ", name()); 1404 Thread::print_on(st); 1405 st->cr(); 1406} 1407 1408// ======= JavaThread ======== 1409 1410// A JavaThread is a normal Java thread 1411 1412void JavaThread::initialize() { 1413 // Initialize fields 1414 1415 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids) 1416 set_claimed_par_id(UINT_MAX); 1417 1418 set_saved_exception_pc(NULL); 1419 set_threadObj(NULL); 1420 _anchor.clear(); 1421 set_entry_point(NULL); 1422 set_jni_functions(jni_functions()); 1423 set_callee_target(NULL); 1424 set_vm_result(NULL); 1425 set_vm_result_2(NULL); 1426 set_vframe_array_head(NULL); 1427 set_vframe_array_last(NULL); 1428 set_deferred_locals(NULL); 1429 set_deopt_mark(NULL); 1430 set_deopt_nmethod(NULL); 1431 clear_must_deopt_id(); 1432 set_monitor_chunks(NULL); 1433 set_next(NULL); 1434 set_thread_state(_thread_new); 1435 _terminated = _not_terminated; 1436 _privileged_stack_top = NULL; 1437 _array_for_gc = NULL; 1438 _suspend_equivalent = false; 1439 _in_deopt_handler = 0; 1440 _doing_unsafe_access = false; 1441 _stack_guard_state = stack_guard_unused; 1442 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1443 _exception_pc = 0; 1444 _exception_handler_pc = 0; 1445 _is_method_handle_return = 0; 1446 _jvmti_thread_state= NULL; 1447 _should_post_on_exceptions_flag = JNI_FALSE; 1448 _jvmti_get_loaded_classes_closure = NULL; 1449 _interp_only_mode = 0; 1450 _special_runtime_exit_condition = _no_async_condition; 1451 _pending_async_exception = NULL; 1452 _thread_stat = NULL; 1453 _thread_stat = new ThreadStatistics(); 1454 _blocked_on_compilation = false; 1455 _jni_active_critical = 0; 1456 _pending_jni_exception_check_fn = NULL; 1457 _do_not_unlock_if_synchronized = false; 1458 _cached_monitor_info = NULL; 1459 _parker = Parker::Allocate(this); 1460 1461#ifndef PRODUCT 1462 _jmp_ring_index = 0; 1463 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1464 record_jump(NULL, NULL, NULL, 0); 1465 } 1466#endif // PRODUCT 1467 1468 set_thread_profiler(NULL); 1469 if (FlatProfiler::is_active()) { 1470 // This is where we would decide to either give each thread it's own profiler 1471 // or use one global one from FlatProfiler, 1472 // or up to some count of the number of profiled threads, etc. 1473 ThreadProfiler* pp = new ThreadProfiler(); 1474 pp->engage(); 1475 set_thread_profiler(pp); 1476 } 1477 1478 // Setup safepoint state info for this thread 1479 ThreadSafepointState::create(this); 1480 1481 debug_only(_java_call_counter = 0); 1482 1483 // JVMTI PopFrame support 1484 _popframe_condition = popframe_inactive; 1485 _popframe_preserved_args = NULL; 1486 _popframe_preserved_args_size = 0; 1487 1488 pd_initialize(); 1489} 1490 1491#if INCLUDE_ALL_GCS 1492SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1493DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1494#endif // INCLUDE_ALL_GCS 1495 1496JavaThread::JavaThread(bool is_attaching_via_jni) : 1497 Thread() 1498#if INCLUDE_ALL_GCS 1499 , _satb_mark_queue(&_satb_mark_queue_set), 1500 _dirty_card_queue(&_dirty_card_queue_set) 1501#endif // INCLUDE_ALL_GCS 1502{ 1503 initialize(); 1504 if (is_attaching_via_jni) { 1505 _jni_attach_state = _attaching_via_jni; 1506 } else { 1507 _jni_attach_state = _not_attaching_via_jni; 1508 } 1509 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1510} 1511 1512bool JavaThread::reguard_stack(address cur_sp) { 1513 if (_stack_guard_state != stack_guard_yellow_disabled) { 1514 return true; // Stack already guarded or guard pages not needed. 1515 } 1516 1517 if (register_stack_overflow()) { 1518 // For those architectures which have separate register and 1519 // memory stacks, we must check the register stack to see if 1520 // it has overflowed. 1521 return false; 1522 } 1523 1524 // Java code never executes within the yellow zone: the latter is only 1525 // there to provoke an exception during stack banging. If java code 1526 // is executing there, either StackShadowPages should be larger, or 1527 // some exception code in c1, c2 or the interpreter isn't unwinding 1528 // when it should. 1529 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1530 1531 enable_stack_yellow_zone(); 1532 return true; 1533} 1534 1535bool JavaThread::reguard_stack(void) { 1536 return reguard_stack(os::current_stack_pointer()); 1537} 1538 1539 1540void JavaThread::block_if_vm_exited() { 1541 if (_terminated == _vm_exited) { 1542 // _vm_exited is set at safepoint, and Threads_lock is never released 1543 // we will block here forever 1544 Threads_lock->lock_without_safepoint_check(); 1545 ShouldNotReachHere(); 1546 } 1547} 1548 1549 1550// Remove this ifdef when C1 is ported to the compiler interface. 1551static void compiler_thread_entry(JavaThread* thread, TRAPS); 1552 1553JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1554 Thread() 1555#if INCLUDE_ALL_GCS 1556 , _satb_mark_queue(&_satb_mark_queue_set), 1557 _dirty_card_queue(&_dirty_card_queue_set) 1558#endif // INCLUDE_ALL_GCS 1559{ 1560 if (TraceThreadEvents) { 1561 tty->print_cr("creating thread %p", this); 1562 } 1563 initialize(); 1564 _jni_attach_state = _not_attaching_via_jni; 1565 set_entry_point(entry_point); 1566 // Create the native thread itself. 1567 // %note runtime_23 1568 os::ThreadType thr_type = os::java_thread; 1569 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1570 os::java_thread; 1571 os::create_thread(this, thr_type, stack_sz); 1572 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1573 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1574 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1575 // the exception consists of creating the exception object & initializing it, initialization 1576 // will leave the VM via a JavaCall and then all locks must be unlocked). 1577 // 1578 // The thread is still suspended when we reach here. Thread must be explicit started 1579 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1580 // by calling Threads:add. The reason why this is not done here, is because the thread 1581 // object must be fully initialized (take a look at JVM_Start) 1582} 1583 1584JavaThread::~JavaThread() { 1585 if (TraceThreadEvents) { 1586 tty->print_cr("terminate thread %p", this); 1587 } 1588 1589 // JSR166 -- return the parker to the free list 1590 Parker::Release(_parker); 1591 _parker = NULL; 1592 1593 // Free any remaining previous UnrollBlock 1594 vframeArray* old_array = vframe_array_last(); 1595 1596 if (old_array != NULL) { 1597 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1598 old_array->set_unroll_block(NULL); 1599 delete old_info; 1600 delete old_array; 1601 } 1602 1603 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1604 if (deferred != NULL) { 1605 // This can only happen if thread is destroyed before deoptimization occurs. 1606 assert(deferred->length() != 0, "empty array!"); 1607 do { 1608 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1609 deferred->remove_at(0); 1610 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1611 delete dlv; 1612 } while (deferred->length() != 0); 1613 delete deferred; 1614 } 1615 1616 // All Java related clean up happens in exit 1617 ThreadSafepointState::destroy(this); 1618 if (_thread_profiler != NULL) delete _thread_profiler; 1619 if (_thread_stat != NULL) delete _thread_stat; 1620} 1621 1622 1623// The first routine called by a new Java thread 1624void JavaThread::run() { 1625 // initialize thread-local alloc buffer related fields 1626 this->initialize_tlab(); 1627 1628 // used to test validity of stack trace backs 1629 this->record_base_of_stack_pointer(); 1630 1631 // Record real stack base and size. 1632 this->record_stack_base_and_size(); 1633 1634 // Initialize thread local storage; set before calling MutexLocker 1635 this->initialize_thread_local_storage(); 1636 1637 this->create_stack_guard_pages(); 1638 1639 this->cache_global_variables(); 1640 1641 // Thread is now sufficient initialized to be handled by the safepoint code as being 1642 // in the VM. Change thread state from _thread_new to _thread_in_vm 1643 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1644 1645 assert(JavaThread::current() == this, "sanity check"); 1646 assert(!Thread::current()->owns_locks(), "sanity check"); 1647 1648 DTRACE_THREAD_PROBE(start, this); 1649 1650 // This operation might block. We call that after all safepoint checks for a new thread has 1651 // been completed. 1652 this->set_active_handles(JNIHandleBlock::allocate_block()); 1653 1654 if (JvmtiExport::should_post_thread_life()) { 1655 JvmtiExport::post_thread_start(this); 1656 } 1657 1658 EventThreadStart event; 1659 if (event.should_commit()) { 1660 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1661 event.commit(); 1662 } 1663 1664 // We call another function to do the rest so we are sure that the stack addresses used 1665 // from there will be lower than the stack base just computed 1666 thread_main_inner(); 1667 1668 // Note, thread is no longer valid at this point! 1669} 1670 1671 1672void JavaThread::thread_main_inner() { 1673 assert(JavaThread::current() == this, "sanity check"); 1674 assert(this->threadObj() != NULL, "just checking"); 1675 1676 // Execute thread entry point unless this thread has a pending exception 1677 // or has been stopped before starting. 1678 // Note: Due to JVM_StopThread we can have pending exceptions already! 1679 if (!this->has_pending_exception() && 1680 !java_lang_Thread::is_stillborn(this->threadObj())) { 1681 { 1682 ResourceMark rm(this); 1683 this->set_native_thread_name(this->get_thread_name()); 1684 } 1685 HandleMark hm(this); 1686 this->entry_point()(this, this); 1687 } 1688 1689 DTRACE_THREAD_PROBE(stop, this); 1690 1691 this->exit(false); 1692 delete this; 1693} 1694 1695 1696static void ensure_join(JavaThread* thread) { 1697 // We do not need to grap the Threads_lock, since we are operating on ourself. 1698 Handle threadObj(thread, thread->threadObj()); 1699 assert(threadObj.not_null(), "java thread object must exist"); 1700 ObjectLocker lock(threadObj, thread); 1701 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1702 thread->clear_pending_exception(); 1703 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1704 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1705 // Clear the native thread instance - this makes isAlive return false and allows the join() 1706 // to complete once we've done the notify_all below 1707 java_lang_Thread::set_thread(threadObj(), NULL); 1708 lock.notify_all(thread); 1709 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1710 thread->clear_pending_exception(); 1711} 1712 1713 1714// For any new cleanup additions, please check to see if they need to be applied to 1715// cleanup_failed_attach_current_thread as well. 1716void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1717 assert(this == JavaThread::current(), "thread consistency check"); 1718 1719 HandleMark hm(this); 1720 Handle uncaught_exception(this, this->pending_exception()); 1721 this->clear_pending_exception(); 1722 Handle threadObj(this, this->threadObj()); 1723 assert(threadObj.not_null(), "Java thread object should be created"); 1724 1725 if (get_thread_profiler() != NULL) { 1726 get_thread_profiler()->disengage(); 1727 ResourceMark rm; 1728 get_thread_profiler()->print(get_thread_name()); 1729 } 1730 1731 1732 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1733 { 1734 EXCEPTION_MARK; 1735 1736 CLEAR_PENDING_EXCEPTION; 1737 } 1738 if (!destroy_vm) { 1739 if (uncaught_exception.not_null()) { 1740 EXCEPTION_MARK; 1741 // Call method Thread.dispatchUncaughtException(). 1742 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1743 JavaValue result(T_VOID); 1744 JavaCalls::call_virtual(&result, 1745 threadObj, thread_klass, 1746 vmSymbols::dispatchUncaughtException_name(), 1747 vmSymbols::throwable_void_signature(), 1748 uncaught_exception, 1749 THREAD); 1750 if (HAS_PENDING_EXCEPTION) { 1751 ResourceMark rm(this); 1752 jio_fprintf(defaultStream::error_stream(), 1753 "\nException: %s thrown from the UncaughtExceptionHandler" 1754 " in thread \"%s\"\n", 1755 pending_exception()->klass()->external_name(), 1756 get_thread_name()); 1757 CLEAR_PENDING_EXCEPTION; 1758 } 1759 } 1760 1761 // Called before the java thread exit since we want to read info 1762 // from java_lang_Thread object 1763 EventThreadEnd event; 1764 if (event.should_commit()) { 1765 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1766 event.commit(); 1767 } 1768 1769 // Call after last event on thread 1770 EVENT_THREAD_EXIT(this); 1771 1772 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1773 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1774 // is deprecated anyhow. 1775 if (!is_Compiler_thread()) { 1776 int count = 3; 1777 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1778 EXCEPTION_MARK; 1779 JavaValue result(T_VOID); 1780 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1781 JavaCalls::call_virtual(&result, 1782 threadObj, thread_klass, 1783 vmSymbols::exit_method_name(), 1784 vmSymbols::void_method_signature(), 1785 THREAD); 1786 CLEAR_PENDING_EXCEPTION; 1787 } 1788 } 1789 // notify JVMTI 1790 if (JvmtiExport::should_post_thread_life()) { 1791 JvmtiExport::post_thread_end(this); 1792 } 1793 1794 // We have notified the agents that we are exiting, before we go on, 1795 // we must check for a pending external suspend request and honor it 1796 // in order to not surprise the thread that made the suspend request. 1797 while (true) { 1798 { 1799 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1800 if (!is_external_suspend()) { 1801 set_terminated(_thread_exiting); 1802 ThreadService::current_thread_exiting(this); 1803 break; 1804 } 1805 // Implied else: 1806 // Things get a little tricky here. We have a pending external 1807 // suspend request, but we are holding the SR_lock so we 1808 // can't just self-suspend. So we temporarily drop the lock 1809 // and then self-suspend. 1810 } 1811 1812 ThreadBlockInVM tbivm(this); 1813 java_suspend_self(); 1814 1815 // We're done with this suspend request, but we have to loop around 1816 // and check again. Eventually we will get SR_lock without a pending 1817 // external suspend request and will be able to mark ourselves as 1818 // exiting. 1819 } 1820 // no more external suspends are allowed at this point 1821 } else { 1822 // before_exit() has already posted JVMTI THREAD_END events 1823 } 1824 1825 // Notify waiters on thread object. This has to be done after exit() is called 1826 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1827 // group should have the destroyed bit set before waiters are notified). 1828 ensure_join(this); 1829 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1830 1831 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1832 // held by this thread must be released. A detach operation must only 1833 // get here if there are no Java frames on the stack. Therefore, any 1834 // owned monitors at this point MUST be JNI-acquired monitors which are 1835 // pre-inflated and in the monitor cache. 1836 // 1837 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1838 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1839 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1840 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1841 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1842 } 1843 1844 // These things needs to be done while we are still a Java Thread. Make sure that thread 1845 // is in a consistent state, in case GC happens 1846 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1847 1848 if (active_handles() != NULL) { 1849 JNIHandleBlock* block = active_handles(); 1850 set_active_handles(NULL); 1851 JNIHandleBlock::release_block(block); 1852 } 1853 1854 if (free_handle_block() != NULL) { 1855 JNIHandleBlock* block = free_handle_block(); 1856 set_free_handle_block(NULL); 1857 JNIHandleBlock::release_block(block); 1858 } 1859 1860 // These have to be removed while this is still a valid thread. 1861 remove_stack_guard_pages(); 1862 1863 if (UseTLAB) { 1864 tlab().make_parsable(true); // retire TLAB 1865 } 1866 1867 if (JvmtiEnv::environments_might_exist()) { 1868 JvmtiExport::cleanup_thread(this); 1869 } 1870 1871 // We must flush any deferred card marks before removing a thread from 1872 // the list of active threads. 1873 Universe::heap()->flush_deferred_store_barrier(this); 1874 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1875 1876#if INCLUDE_ALL_GCS 1877 // We must flush the G1-related buffers before removing a thread 1878 // from the list of active threads. We must do this after any deferred 1879 // card marks have been flushed (above) so that any entries that are 1880 // added to the thread's dirty card queue as a result are not lost. 1881 if (UseG1GC) { 1882 flush_barrier_queues(); 1883 } 1884#endif // INCLUDE_ALL_GCS 1885 1886 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1887 Threads::remove(this); 1888} 1889 1890#if INCLUDE_ALL_GCS 1891// Flush G1-related queues. 1892void JavaThread::flush_barrier_queues() { 1893 satb_mark_queue().flush(); 1894 dirty_card_queue().flush(); 1895} 1896 1897void JavaThread::initialize_queues() { 1898 assert(!SafepointSynchronize::is_at_safepoint(), 1899 "we should not be at a safepoint"); 1900 1901 ObjPtrQueue& satb_queue = satb_mark_queue(); 1902 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1903 // The SATB queue should have been constructed with its active 1904 // field set to false. 1905 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1906 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1907 // If we are creating the thread during a marking cycle, we should 1908 // set the active field of the SATB queue to true. 1909 if (satb_queue_set.is_active()) { 1910 satb_queue.set_active(true); 1911 } 1912 1913 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1914 // The dirty card queue should have been constructed with its 1915 // active field set to true. 1916 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1917} 1918#endif // INCLUDE_ALL_GCS 1919 1920void JavaThread::cleanup_failed_attach_current_thread() { 1921 if (get_thread_profiler() != NULL) { 1922 get_thread_profiler()->disengage(); 1923 ResourceMark rm; 1924 get_thread_profiler()->print(get_thread_name()); 1925 } 1926 1927 if (active_handles() != NULL) { 1928 JNIHandleBlock* block = active_handles(); 1929 set_active_handles(NULL); 1930 JNIHandleBlock::release_block(block); 1931 } 1932 1933 if (free_handle_block() != NULL) { 1934 JNIHandleBlock* block = free_handle_block(); 1935 set_free_handle_block(NULL); 1936 JNIHandleBlock::release_block(block); 1937 } 1938 1939 // These have to be removed while this is still a valid thread. 1940 remove_stack_guard_pages(); 1941 1942 if (UseTLAB) { 1943 tlab().make_parsable(true); // retire TLAB, if any 1944 } 1945 1946#if INCLUDE_ALL_GCS 1947 if (UseG1GC) { 1948 flush_barrier_queues(); 1949 } 1950#endif // INCLUDE_ALL_GCS 1951 1952 Threads::remove(this); 1953 delete this; 1954} 1955 1956 1957 1958 1959JavaThread* JavaThread::active() { 1960 Thread* thread = ThreadLocalStorage::thread(); 1961 assert(thread != NULL, "just checking"); 1962 if (thread->is_Java_thread()) { 1963 return (JavaThread*) thread; 1964 } else { 1965 assert(thread->is_VM_thread(), "this must be a vm thread"); 1966 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1967 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1968 assert(ret->is_Java_thread(), "must be a Java thread"); 1969 return ret; 1970 } 1971} 1972 1973bool JavaThread::is_lock_owned(address adr) const { 1974 if (Thread::is_lock_owned(adr)) return true; 1975 1976 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1977 if (chunk->contains(adr)) return true; 1978 } 1979 1980 return false; 1981} 1982 1983 1984void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1985 chunk->set_next(monitor_chunks()); 1986 set_monitor_chunks(chunk); 1987} 1988 1989void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1990 guarantee(monitor_chunks() != NULL, "must be non empty"); 1991 if (monitor_chunks() == chunk) { 1992 set_monitor_chunks(chunk->next()); 1993 } else { 1994 MonitorChunk* prev = monitor_chunks(); 1995 while (prev->next() != chunk) prev = prev->next(); 1996 prev->set_next(chunk->next()); 1997 } 1998} 1999 2000// JVM support. 2001 2002// Note: this function shouldn't block if it's called in 2003// _thread_in_native_trans state (such as from 2004// check_special_condition_for_native_trans()). 2005void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2006 2007 if (has_last_Java_frame() && has_async_condition()) { 2008 // If we are at a polling page safepoint (not a poll return) 2009 // then we must defer async exception because live registers 2010 // will be clobbered by the exception path. Poll return is 2011 // ok because the call we a returning from already collides 2012 // with exception handling registers and so there is no issue. 2013 // (The exception handling path kills call result registers but 2014 // this is ok since the exception kills the result anyway). 2015 2016 if (is_at_poll_safepoint()) { 2017 // if the code we are returning to has deoptimized we must defer 2018 // the exception otherwise live registers get clobbered on the 2019 // exception path before deoptimization is able to retrieve them. 2020 // 2021 RegisterMap map(this, false); 2022 frame caller_fr = last_frame().sender(&map); 2023 assert(caller_fr.is_compiled_frame(), "what?"); 2024 if (caller_fr.is_deoptimized_frame()) { 2025 if (TraceExceptions) { 2026 ResourceMark rm; 2027 tty->print_cr("deferred async exception at compiled safepoint"); 2028 } 2029 return; 2030 } 2031 } 2032 } 2033 2034 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2035 if (condition == _no_async_condition) { 2036 // Conditions have changed since has_special_runtime_exit_condition() 2037 // was called: 2038 // - if we were here only because of an external suspend request, 2039 // then that was taken care of above (or cancelled) so we are done 2040 // - if we were here because of another async request, then it has 2041 // been cleared between the has_special_runtime_exit_condition() 2042 // and now so again we are done 2043 return; 2044 } 2045 2046 // Check for pending async. exception 2047 if (_pending_async_exception != NULL) { 2048 // Only overwrite an already pending exception, if it is not a threadDeath. 2049 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2050 2051 // We cannot call Exceptions::_throw(...) here because we cannot block 2052 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2053 2054 if (TraceExceptions) { 2055 ResourceMark rm; 2056 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 2057 if (has_last_Java_frame()) { 2058 frame f = last_frame(); 2059 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 2060 } 2061 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2062 } 2063 _pending_async_exception = NULL; 2064 clear_has_async_exception(); 2065 } 2066 } 2067 2068 if (check_unsafe_error && 2069 condition == _async_unsafe_access_error && !has_pending_exception()) { 2070 condition = _no_async_condition; // done 2071 switch (thread_state()) { 2072 case _thread_in_vm: { 2073 JavaThread* THREAD = this; 2074 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2075 } 2076 case _thread_in_native: { 2077 ThreadInVMfromNative tiv(this); 2078 JavaThread* THREAD = this; 2079 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2080 } 2081 case _thread_in_Java: { 2082 ThreadInVMfromJava tiv(this); 2083 JavaThread* THREAD = this; 2084 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2085 } 2086 default: 2087 ShouldNotReachHere(); 2088 } 2089 } 2090 2091 assert(condition == _no_async_condition || has_pending_exception() || 2092 (!check_unsafe_error && condition == _async_unsafe_access_error), 2093 "must have handled the async condition, if no exception"); 2094} 2095 2096void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2097 // 2098 // Check for pending external suspend. Internal suspend requests do 2099 // not use handle_special_runtime_exit_condition(). 2100 // If JNIEnv proxies are allowed, don't self-suspend if the target 2101 // thread is not the current thread. In older versions of jdbx, jdbx 2102 // threads could call into the VM with another thread's JNIEnv so we 2103 // can be here operating on behalf of a suspended thread (4432884). 2104 bool do_self_suspend = is_external_suspend_with_lock(); 2105 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2106 // 2107 // Because thread is external suspended the safepoint code will count 2108 // thread as at a safepoint. This can be odd because we can be here 2109 // as _thread_in_Java which would normally transition to _thread_blocked 2110 // at a safepoint. We would like to mark the thread as _thread_blocked 2111 // before calling java_suspend_self like all other callers of it but 2112 // we must then observe proper safepoint protocol. (We can't leave 2113 // _thread_blocked with a safepoint in progress). However we can be 2114 // here as _thread_in_native_trans so we can't use a normal transition 2115 // constructor/destructor pair because they assert on that type of 2116 // transition. We could do something like: 2117 // 2118 // JavaThreadState state = thread_state(); 2119 // set_thread_state(_thread_in_vm); 2120 // { 2121 // ThreadBlockInVM tbivm(this); 2122 // java_suspend_self() 2123 // } 2124 // set_thread_state(_thread_in_vm_trans); 2125 // if (safepoint) block; 2126 // set_thread_state(state); 2127 // 2128 // but that is pretty messy. Instead we just go with the way the 2129 // code has worked before and note that this is the only path to 2130 // java_suspend_self that doesn't put the thread in _thread_blocked 2131 // mode. 2132 2133 frame_anchor()->make_walkable(this); 2134 java_suspend_self(); 2135 2136 // We might be here for reasons in addition to the self-suspend request 2137 // so check for other async requests. 2138 } 2139 2140 if (check_asyncs) { 2141 check_and_handle_async_exceptions(); 2142 } 2143} 2144 2145void JavaThread::send_thread_stop(oop java_throwable) { 2146 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2147 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2148 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2149 2150 // Do not throw asynchronous exceptions against the compiler thread 2151 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2152 if (is_Compiler_thread()) return; 2153 2154 { 2155 // Actually throw the Throwable against the target Thread - however 2156 // only if there is no thread death exception installed already. 2157 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2158 // If the topmost frame is a runtime stub, then we are calling into 2159 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2160 // must deoptimize the caller before continuing, as the compiled exception handler table 2161 // may not be valid 2162 if (has_last_Java_frame()) { 2163 frame f = last_frame(); 2164 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2165 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2166 RegisterMap reg_map(this, UseBiasedLocking); 2167 frame compiled_frame = f.sender(®_map); 2168 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2169 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2170 } 2171 } 2172 } 2173 2174 // Set async. pending exception in thread. 2175 set_pending_async_exception(java_throwable); 2176 2177 if (TraceExceptions) { 2178 ResourceMark rm; 2179 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2180 } 2181 // for AbortVMOnException flag 2182 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name())); 2183 } 2184 } 2185 2186 2187 // Interrupt thread so it will wake up from a potential wait() 2188 Thread::interrupt(this); 2189} 2190 2191// External suspension mechanism. 2192// 2193// Tell the VM to suspend a thread when ever it knows that it does not hold on 2194// to any VM_locks and it is at a transition 2195// Self-suspension will happen on the transition out of the vm. 2196// Catch "this" coming in from JNIEnv pointers when the thread has been freed 2197// 2198// Guarantees on return: 2199// + Target thread will not execute any new bytecode (that's why we need to 2200// force a safepoint) 2201// + Target thread will not enter any new monitors 2202// 2203void JavaThread::java_suspend() { 2204 { MutexLocker mu(Threads_lock); 2205 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2206 return; 2207 } 2208 } 2209 2210 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2211 if (!is_external_suspend()) { 2212 // a racing resume has cancelled us; bail out now 2213 return; 2214 } 2215 2216 // suspend is done 2217 uint32_t debug_bits = 0; 2218 // Warning: is_ext_suspend_completed() may temporarily drop the 2219 // SR_lock to allow the thread to reach a stable thread state if 2220 // it is currently in a transient thread state. 2221 if (is_ext_suspend_completed(false /* !called_by_wait */, 2222 SuspendRetryDelay, &debug_bits)) { 2223 return; 2224 } 2225 } 2226 2227 VM_ForceSafepoint vm_suspend; 2228 VMThread::execute(&vm_suspend); 2229} 2230 2231// Part II of external suspension. 2232// A JavaThread self suspends when it detects a pending external suspend 2233// request. This is usually on transitions. It is also done in places 2234// where continuing to the next transition would surprise the caller, 2235// e.g., monitor entry. 2236// 2237// Returns the number of times that the thread self-suspended. 2238// 2239// Note: DO NOT call java_suspend_self() when you just want to block current 2240// thread. java_suspend_self() is the second stage of cooperative 2241// suspension for external suspend requests and should only be used 2242// to complete an external suspend request. 2243// 2244int JavaThread::java_suspend_self() { 2245 int ret = 0; 2246 2247 // we are in the process of exiting so don't suspend 2248 if (is_exiting()) { 2249 clear_external_suspend(); 2250 return ret; 2251 } 2252 2253 assert(_anchor.walkable() || 2254 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2255 "must have walkable stack"); 2256 2257 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2258 2259 assert(!this->is_ext_suspended(), 2260 "a thread trying to self-suspend should not already be suspended"); 2261 2262 if (this->is_suspend_equivalent()) { 2263 // If we are self-suspending as a result of the lifting of a 2264 // suspend equivalent condition, then the suspend_equivalent 2265 // flag is not cleared until we set the ext_suspended flag so 2266 // that wait_for_ext_suspend_completion() returns consistent 2267 // results. 2268 this->clear_suspend_equivalent(); 2269 } 2270 2271 // A racing resume may have cancelled us before we grabbed SR_lock 2272 // above. Or another external suspend request could be waiting for us 2273 // by the time we return from SR_lock()->wait(). The thread 2274 // that requested the suspension may already be trying to walk our 2275 // stack and if we return now, we can change the stack out from under 2276 // it. This would be a "bad thing (TM)" and cause the stack walker 2277 // to crash. We stay self-suspended until there are no more pending 2278 // external suspend requests. 2279 while (is_external_suspend()) { 2280 ret++; 2281 this->set_ext_suspended(); 2282 2283 // _ext_suspended flag is cleared by java_resume() 2284 while (is_ext_suspended()) { 2285 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2286 } 2287 } 2288 2289 return ret; 2290} 2291 2292#ifdef ASSERT 2293// verify the JavaThread has not yet been published in the Threads::list, and 2294// hence doesn't need protection from concurrent access at this stage 2295void JavaThread::verify_not_published() { 2296 if (!Threads_lock->owned_by_self()) { 2297 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2298 assert(!Threads::includes(this), 2299 "java thread shouldn't have been published yet!"); 2300 } else { 2301 assert(!Threads::includes(this), 2302 "java thread shouldn't have been published yet!"); 2303 } 2304} 2305#endif 2306 2307// Slow path when the native==>VM/Java barriers detect a safepoint is in 2308// progress or when _suspend_flags is non-zero. 2309// Current thread needs to self-suspend if there is a suspend request and/or 2310// block if a safepoint is in progress. 2311// Async exception ISN'T checked. 2312// Note only the ThreadInVMfromNative transition can call this function 2313// directly and when thread state is _thread_in_native_trans 2314void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2315 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2316 2317 JavaThread *curJT = JavaThread::current(); 2318 bool do_self_suspend = thread->is_external_suspend(); 2319 2320 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2321 2322 // If JNIEnv proxies are allowed, don't self-suspend if the target 2323 // thread is not the current thread. In older versions of jdbx, jdbx 2324 // threads could call into the VM with another thread's JNIEnv so we 2325 // can be here operating on behalf of a suspended thread (4432884). 2326 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2327 JavaThreadState state = thread->thread_state(); 2328 2329 // We mark this thread_blocked state as a suspend-equivalent so 2330 // that a caller to is_ext_suspend_completed() won't be confused. 2331 // The suspend-equivalent state is cleared by java_suspend_self(). 2332 thread->set_suspend_equivalent(); 2333 2334 // If the safepoint code sees the _thread_in_native_trans state, it will 2335 // wait until the thread changes to other thread state. There is no 2336 // guarantee on how soon we can obtain the SR_lock and complete the 2337 // self-suspend request. It would be a bad idea to let safepoint wait for 2338 // too long. Temporarily change the state to _thread_blocked to 2339 // let the VM thread know that this thread is ready for GC. The problem 2340 // of changing thread state is that safepoint could happen just after 2341 // java_suspend_self() returns after being resumed, and VM thread will 2342 // see the _thread_blocked state. We must check for safepoint 2343 // after restoring the state and make sure we won't leave while a safepoint 2344 // is in progress. 2345 thread->set_thread_state(_thread_blocked); 2346 thread->java_suspend_self(); 2347 thread->set_thread_state(state); 2348 // Make sure new state is seen by VM thread 2349 if (os::is_MP()) { 2350 if (UseMembar) { 2351 // Force a fence between the write above and read below 2352 OrderAccess::fence(); 2353 } else { 2354 // Must use this rather than serialization page in particular on Windows 2355 InterfaceSupport::serialize_memory(thread); 2356 } 2357 } 2358 } 2359 2360 if (SafepointSynchronize::do_call_back()) { 2361 // If we are safepointing, then block the caller which may not be 2362 // the same as the target thread (see above). 2363 SafepointSynchronize::block(curJT); 2364 } 2365 2366 if (thread->is_deopt_suspend()) { 2367 thread->clear_deopt_suspend(); 2368 RegisterMap map(thread, false); 2369 frame f = thread->last_frame(); 2370 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2371 f = f.sender(&map); 2372 } 2373 if (f.id() == thread->must_deopt_id()) { 2374 thread->clear_must_deopt_id(); 2375 f.deoptimize(thread); 2376 } else { 2377 fatal("missed deoptimization!"); 2378 } 2379 } 2380} 2381 2382// Slow path when the native==>VM/Java barriers detect a safepoint is in 2383// progress or when _suspend_flags is non-zero. 2384// Current thread needs to self-suspend if there is a suspend request and/or 2385// block if a safepoint is in progress. 2386// Also check for pending async exception (not including unsafe access error). 2387// Note only the native==>VM/Java barriers can call this function and when 2388// thread state is _thread_in_native_trans. 2389void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2390 check_safepoint_and_suspend_for_native_trans(thread); 2391 2392 if (thread->has_async_exception()) { 2393 // We are in _thread_in_native_trans state, don't handle unsafe 2394 // access error since that may block. 2395 thread->check_and_handle_async_exceptions(false); 2396 } 2397} 2398 2399// This is a variant of the normal 2400// check_special_condition_for_native_trans with slightly different 2401// semantics for use by critical native wrappers. It does all the 2402// normal checks but also performs the transition back into 2403// thread_in_Java state. This is required so that critical natives 2404// can potentially block and perform a GC if they are the last thread 2405// exiting the GC_locker. 2406void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2407 check_special_condition_for_native_trans(thread); 2408 2409 // Finish the transition 2410 thread->set_thread_state(_thread_in_Java); 2411 2412 if (thread->do_critical_native_unlock()) { 2413 ThreadInVMfromJavaNoAsyncException tiv(thread); 2414 GC_locker::unlock_critical(thread); 2415 thread->clear_critical_native_unlock(); 2416 } 2417} 2418 2419// We need to guarantee the Threads_lock here, since resumes are not 2420// allowed during safepoint synchronization 2421// Can only resume from an external suspension 2422void JavaThread::java_resume() { 2423 assert_locked_or_safepoint(Threads_lock); 2424 2425 // Sanity check: thread is gone, has started exiting or the thread 2426 // was not externally suspended. 2427 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2428 return; 2429 } 2430 2431 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2432 2433 clear_external_suspend(); 2434 2435 if (is_ext_suspended()) { 2436 clear_ext_suspended(); 2437 SR_lock()->notify_all(); 2438 } 2439} 2440 2441void JavaThread::create_stack_guard_pages() { 2442 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2443 address low_addr = stack_base() - stack_size(); 2444 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2445 2446 int allocate = os::allocate_stack_guard_pages(); 2447 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2448 2449 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2450 warning("Attempt to allocate stack guard pages failed."); 2451 return; 2452 } 2453 2454 if (os::guard_memory((char *) low_addr, len)) { 2455 _stack_guard_state = stack_guard_enabled; 2456 } else { 2457 warning("Attempt to protect stack guard pages failed."); 2458 if (os::uncommit_memory((char *) low_addr, len)) { 2459 warning("Attempt to deallocate stack guard pages failed."); 2460 } 2461 } 2462} 2463 2464void JavaThread::remove_stack_guard_pages() { 2465 assert(Thread::current() == this, "from different thread"); 2466 if (_stack_guard_state == stack_guard_unused) return; 2467 address low_addr = stack_base() - stack_size(); 2468 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2469 2470 if (os::allocate_stack_guard_pages()) { 2471 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2472 _stack_guard_state = stack_guard_unused; 2473 } else { 2474 warning("Attempt to deallocate stack guard pages failed."); 2475 } 2476 } else { 2477 if (_stack_guard_state == stack_guard_unused) return; 2478 if (os::unguard_memory((char *) low_addr, len)) { 2479 _stack_guard_state = stack_guard_unused; 2480 } else { 2481 warning("Attempt to unprotect stack guard pages failed."); 2482 } 2483 } 2484} 2485 2486void JavaThread::enable_stack_yellow_zone() { 2487 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2488 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2489 2490 // The base notation is from the stacks point of view, growing downward. 2491 // We need to adjust it to work correctly with guard_memory() 2492 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2493 2494 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2495 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2496 2497 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2498 _stack_guard_state = stack_guard_enabled; 2499 } else { 2500 warning("Attempt to guard stack yellow zone failed."); 2501 } 2502 enable_register_stack_guard(); 2503} 2504 2505void JavaThread::disable_stack_yellow_zone() { 2506 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2507 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2508 2509 // Simply return if called for a thread that does not use guard pages. 2510 if (_stack_guard_state == stack_guard_unused) return; 2511 2512 // The base notation is from the stacks point of view, growing downward. 2513 // We need to adjust it to work correctly with guard_memory() 2514 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2515 2516 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2517 _stack_guard_state = stack_guard_yellow_disabled; 2518 } else { 2519 warning("Attempt to unguard stack yellow zone failed."); 2520 } 2521 disable_register_stack_guard(); 2522} 2523 2524void JavaThread::enable_stack_red_zone() { 2525 // The base notation is from the stacks point of view, growing downward. 2526 // We need to adjust it to work correctly with guard_memory() 2527 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2528 address base = stack_red_zone_base() - stack_red_zone_size(); 2529 2530 guarantee(base < stack_base(), "Error calculating stack red zone"); 2531 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2532 2533 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2534 warning("Attempt to guard stack red zone failed."); 2535 } 2536} 2537 2538void JavaThread::disable_stack_red_zone() { 2539 // The base notation is from the stacks point of view, growing downward. 2540 // We need to adjust it to work correctly with guard_memory() 2541 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2542 address base = stack_red_zone_base() - stack_red_zone_size(); 2543 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2544 warning("Attempt to unguard stack red zone failed."); 2545 } 2546} 2547 2548void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2549 // ignore is there is no stack 2550 if (!has_last_Java_frame()) return; 2551 // traverse the stack frames. Starts from top frame. 2552 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2553 frame* fr = fst.current(); 2554 f(fr, fst.register_map()); 2555 } 2556} 2557 2558 2559#ifndef PRODUCT 2560// Deoptimization 2561// Function for testing deoptimization 2562void JavaThread::deoptimize() { 2563 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2564 StackFrameStream fst(this, UseBiasedLocking); 2565 bool deopt = false; // Dump stack only if a deopt actually happens. 2566 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2567 // Iterate over all frames in the thread and deoptimize 2568 for (; !fst.is_done(); fst.next()) { 2569 if (fst.current()->can_be_deoptimized()) { 2570 2571 if (only_at) { 2572 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2573 // consists of comma or carriage return separated numbers so 2574 // search for the current bci in that string. 2575 address pc = fst.current()->pc(); 2576 nmethod* nm = (nmethod*) fst.current()->cb(); 2577 ScopeDesc* sd = nm->scope_desc_at(pc); 2578 char buffer[8]; 2579 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2580 size_t len = strlen(buffer); 2581 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2582 while (found != NULL) { 2583 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2584 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2585 // Check that the bci found is bracketed by terminators. 2586 break; 2587 } 2588 found = strstr(found + 1, buffer); 2589 } 2590 if (!found) { 2591 continue; 2592 } 2593 } 2594 2595 if (DebugDeoptimization && !deopt) { 2596 deopt = true; // One-time only print before deopt 2597 tty->print_cr("[BEFORE Deoptimization]"); 2598 trace_frames(); 2599 trace_stack(); 2600 } 2601 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2602 } 2603 } 2604 2605 if (DebugDeoptimization && deopt) { 2606 tty->print_cr("[AFTER Deoptimization]"); 2607 trace_frames(); 2608 } 2609} 2610 2611 2612// Make zombies 2613void JavaThread::make_zombies() { 2614 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2615 if (fst.current()->can_be_deoptimized()) { 2616 // it is a Java nmethod 2617 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2618 nm->make_not_entrant(); 2619 } 2620 } 2621} 2622#endif // PRODUCT 2623 2624 2625void JavaThread::deoptimized_wrt_marked_nmethods() { 2626 if (!has_last_Java_frame()) return; 2627 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2628 StackFrameStream fst(this, UseBiasedLocking); 2629 for (; !fst.is_done(); fst.next()) { 2630 if (fst.current()->should_be_deoptimized()) { 2631 if (LogCompilation && xtty != NULL) { 2632 nmethod* nm = fst.current()->cb()->as_nmethod_or_null(); 2633 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'", 2634 this->name(), nm != NULL ? nm->compile_id() : -1); 2635 } 2636 2637 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2638 } 2639 } 2640} 2641 2642 2643// If the caller is a NamedThread, then remember, in the current scope, 2644// the given JavaThread in its _processed_thread field. 2645class RememberProcessedThread: public StackObj { 2646 NamedThread* _cur_thr; 2647 public: 2648 RememberProcessedThread(JavaThread* jthr) { 2649 Thread* thread = Thread::current(); 2650 if (thread->is_Named_thread()) { 2651 _cur_thr = (NamedThread *)thread; 2652 _cur_thr->set_processed_thread(jthr); 2653 } else { 2654 _cur_thr = NULL; 2655 } 2656 } 2657 2658 ~RememberProcessedThread() { 2659 if (_cur_thr) { 2660 _cur_thr->set_processed_thread(NULL); 2661 } 2662 } 2663}; 2664 2665void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2666 // Verify that the deferred card marks have been flushed. 2667 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2668 2669 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2670 // since there may be more than one thread using each ThreadProfiler. 2671 2672 // Traverse the GCHandles 2673 Thread::oops_do(f, cld_f, cf); 2674 2675 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2676 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2677 2678 if (has_last_Java_frame()) { 2679 // Record JavaThread to GC thread 2680 RememberProcessedThread rpt(this); 2681 2682 // Traverse the privileged stack 2683 if (_privileged_stack_top != NULL) { 2684 _privileged_stack_top->oops_do(f); 2685 } 2686 2687 // traverse the registered growable array 2688 if (_array_for_gc != NULL) { 2689 for (int index = 0; index < _array_for_gc->length(); index++) { 2690 f->do_oop(_array_for_gc->adr_at(index)); 2691 } 2692 } 2693 2694 // Traverse the monitor chunks 2695 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2696 chunk->oops_do(f); 2697 } 2698 2699 // Traverse the execution stack 2700 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2701 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2702 } 2703 } 2704 2705 // callee_target is never live across a gc point so NULL it here should 2706 // it still contain a methdOop. 2707 2708 set_callee_target(NULL); 2709 2710 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2711 // If we have deferred set_locals there might be oops waiting to be 2712 // written 2713 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2714 if (list != NULL) { 2715 for (int i = 0; i < list->length(); i++) { 2716 list->at(i)->oops_do(f); 2717 } 2718 } 2719 2720 // Traverse instance variables at the end since the GC may be moving things 2721 // around using this function 2722 f->do_oop((oop*) &_threadObj); 2723 f->do_oop((oop*) &_vm_result); 2724 f->do_oop((oop*) &_exception_oop); 2725 f->do_oop((oop*) &_pending_async_exception); 2726 2727 if (jvmti_thread_state() != NULL) { 2728 jvmti_thread_state()->oops_do(f); 2729 } 2730} 2731 2732void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2733 Thread::nmethods_do(cf); // (super method is a no-op) 2734 2735 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2736 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2737 2738 if (has_last_Java_frame()) { 2739 // Traverse the execution stack 2740 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2741 fst.current()->nmethods_do(cf); 2742 } 2743 } 2744} 2745 2746void JavaThread::metadata_do(void f(Metadata*)) { 2747 Thread::metadata_do(f); 2748 if (has_last_Java_frame()) { 2749 // Traverse the execution stack to call f() on the methods in the stack 2750 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2751 fst.current()->metadata_do(f); 2752 } 2753 } else if (is_Compiler_thread()) { 2754 // need to walk ciMetadata in current compile tasks to keep alive. 2755 CompilerThread* ct = (CompilerThread*)this; 2756 if (ct->env() != NULL) { 2757 ct->env()->metadata_do(f); 2758 } 2759 } 2760} 2761 2762// Printing 2763const char* _get_thread_state_name(JavaThreadState _thread_state) { 2764 switch (_thread_state) { 2765 case _thread_uninitialized: return "_thread_uninitialized"; 2766 case _thread_new: return "_thread_new"; 2767 case _thread_new_trans: return "_thread_new_trans"; 2768 case _thread_in_native: return "_thread_in_native"; 2769 case _thread_in_native_trans: return "_thread_in_native_trans"; 2770 case _thread_in_vm: return "_thread_in_vm"; 2771 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2772 case _thread_in_Java: return "_thread_in_Java"; 2773 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2774 case _thread_blocked: return "_thread_blocked"; 2775 case _thread_blocked_trans: return "_thread_blocked_trans"; 2776 default: return "unknown thread state"; 2777 } 2778} 2779 2780#ifndef PRODUCT 2781void JavaThread::print_thread_state_on(outputStream *st) const { 2782 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2783}; 2784void JavaThread::print_thread_state() const { 2785 print_thread_state_on(tty); 2786} 2787#endif // PRODUCT 2788 2789// Called by Threads::print() for VM_PrintThreads operation 2790void JavaThread::print_on(outputStream *st) const { 2791 st->print("\"%s\" ", get_thread_name()); 2792 oop thread_oop = threadObj(); 2793 if (thread_oop != NULL) { 2794 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2795 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2796 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2797 } 2798 Thread::print_on(st); 2799 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2800 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2801 if (thread_oop != NULL) { 2802 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2803 } 2804#ifndef PRODUCT 2805 print_thread_state_on(st); 2806 _safepoint_state->print_on(st); 2807#endif // PRODUCT 2808} 2809 2810// Called by fatal error handler. The difference between this and 2811// JavaThread::print() is that we can't grab lock or allocate memory. 2812void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2813 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2814 oop thread_obj = threadObj(); 2815 if (thread_obj != NULL) { 2816 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2817 } 2818 st->print(" ["); 2819 st->print("%s", _get_thread_state_name(_thread_state)); 2820 if (osthread()) { 2821 st->print(", id=%d", osthread()->thread_id()); 2822 } 2823 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2824 _stack_base - _stack_size, _stack_base); 2825 st->print("]"); 2826 return; 2827} 2828 2829// Verification 2830 2831static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2832 2833void JavaThread::verify() { 2834 // Verify oops in the thread. 2835 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2836 2837 // Verify the stack frames. 2838 frames_do(frame_verify); 2839} 2840 2841// CR 6300358 (sub-CR 2137150) 2842// Most callers of this method assume that it can't return NULL but a 2843// thread may not have a name whilst it is in the process of attaching to 2844// the VM - see CR 6412693, and there are places where a JavaThread can be 2845// seen prior to having it's threadObj set (eg JNI attaching threads and 2846// if vm exit occurs during initialization). These cases can all be accounted 2847// for such that this method never returns NULL. 2848const char* JavaThread::get_thread_name() const { 2849#ifdef ASSERT 2850 // early safepoints can hit while current thread does not yet have TLS 2851 if (!SafepointSynchronize::is_at_safepoint()) { 2852 Thread *cur = Thread::current(); 2853 if (!(cur->is_Java_thread() && cur == this)) { 2854 // Current JavaThreads are allowed to get their own name without 2855 // the Threads_lock. 2856 assert_locked_or_safepoint(Threads_lock); 2857 } 2858 } 2859#endif // ASSERT 2860 return get_thread_name_string(); 2861} 2862 2863// Returns a non-NULL representation of this thread's name, or a suitable 2864// descriptive string if there is no set name 2865const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2866 const char* name_str; 2867 oop thread_obj = threadObj(); 2868 if (thread_obj != NULL) { 2869 typeArrayOop name = java_lang_Thread::name(thread_obj); 2870 if (name != NULL) { 2871 if (buf == NULL) { 2872 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2873 name->length()); 2874 } else { 2875 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), 2876 name->length(), buf, buflen); 2877 } 2878 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2879 name_str = "<no-name - thread is attaching>"; 2880 } else { 2881 name_str = Thread::name(); 2882 } 2883 } else { 2884 name_str = Thread::name(); 2885 } 2886 assert(name_str != NULL, "unexpected NULL thread name"); 2887 return name_str; 2888} 2889 2890 2891const char* JavaThread::get_threadgroup_name() const { 2892 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2893 oop thread_obj = threadObj(); 2894 if (thread_obj != NULL) { 2895 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2896 if (thread_group != NULL) { 2897 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2898 // ThreadGroup.name can be null 2899 if (name != NULL) { 2900 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2901 return str; 2902 } 2903 } 2904 } 2905 return NULL; 2906} 2907 2908const char* JavaThread::get_parent_name() const { 2909 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2910 oop thread_obj = threadObj(); 2911 if (thread_obj != NULL) { 2912 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2913 if (thread_group != NULL) { 2914 oop parent = java_lang_ThreadGroup::parent(thread_group); 2915 if (parent != NULL) { 2916 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2917 // ThreadGroup.name can be null 2918 if (name != NULL) { 2919 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2920 return str; 2921 } 2922 } 2923 } 2924 } 2925 return NULL; 2926} 2927 2928ThreadPriority JavaThread::java_priority() const { 2929 oop thr_oop = threadObj(); 2930 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2931 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2932 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2933 return priority; 2934} 2935 2936void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2937 2938 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2939 // Link Java Thread object <-> C++ Thread 2940 2941 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2942 // and put it into a new Handle. The Handle "thread_oop" can then 2943 // be used to pass the C++ thread object to other methods. 2944 2945 // Set the Java level thread object (jthread) field of the 2946 // new thread (a JavaThread *) to C++ thread object using the 2947 // "thread_oop" handle. 2948 2949 // Set the thread field (a JavaThread *) of the 2950 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2951 2952 Handle thread_oop(Thread::current(), 2953 JNIHandles::resolve_non_null(jni_thread)); 2954 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 2955 "must be initialized"); 2956 set_threadObj(thread_oop()); 2957 java_lang_Thread::set_thread(thread_oop(), this); 2958 2959 if (prio == NoPriority) { 2960 prio = java_lang_Thread::priority(thread_oop()); 2961 assert(prio != NoPriority, "A valid priority should be present"); 2962 } 2963 2964 // Push the Java priority down to the native thread; needs Threads_lock 2965 Thread::set_priority(this, prio); 2966 2967 // Add the new thread to the Threads list and set it in motion. 2968 // We must have threads lock in order to call Threads::add. 2969 // It is crucial that we do not block before the thread is 2970 // added to the Threads list for if a GC happens, then the java_thread oop 2971 // will not be visited by GC. 2972 Threads::add(this); 2973} 2974 2975oop JavaThread::current_park_blocker() { 2976 // Support for JSR-166 locks 2977 oop thread_oop = threadObj(); 2978 if (thread_oop != NULL && 2979 JDK_Version::current().supports_thread_park_blocker()) { 2980 return java_lang_Thread::park_blocker(thread_oop); 2981 } 2982 return NULL; 2983} 2984 2985 2986void JavaThread::print_stack_on(outputStream* st) { 2987 if (!has_last_Java_frame()) return; 2988 ResourceMark rm; 2989 HandleMark hm; 2990 2991 RegisterMap reg_map(this); 2992 vframe* start_vf = last_java_vframe(®_map); 2993 int count = 0; 2994 for (vframe* f = start_vf; f; f = f->sender()) { 2995 if (f->is_java_frame()) { 2996 javaVFrame* jvf = javaVFrame::cast(f); 2997 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 2998 2999 // Print out lock information 3000 if (JavaMonitorsInStackTrace) { 3001 jvf->print_lock_info_on(st, count); 3002 } 3003 } else { 3004 // Ignore non-Java frames 3005 } 3006 3007 // Bail-out case for too deep stacks 3008 count++; 3009 if (MaxJavaStackTraceDepth == count) return; 3010 } 3011} 3012 3013 3014// JVMTI PopFrame support 3015void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3016 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3017 if (in_bytes(size_in_bytes) != 0) { 3018 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3019 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3020 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3021 } 3022} 3023 3024void* JavaThread::popframe_preserved_args() { 3025 return _popframe_preserved_args; 3026} 3027 3028ByteSize JavaThread::popframe_preserved_args_size() { 3029 return in_ByteSize(_popframe_preserved_args_size); 3030} 3031 3032WordSize JavaThread::popframe_preserved_args_size_in_words() { 3033 int sz = in_bytes(popframe_preserved_args_size()); 3034 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3035 return in_WordSize(sz / wordSize); 3036} 3037 3038void JavaThread::popframe_free_preserved_args() { 3039 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3040 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread); 3041 _popframe_preserved_args = NULL; 3042 _popframe_preserved_args_size = 0; 3043} 3044 3045#ifndef PRODUCT 3046 3047void JavaThread::trace_frames() { 3048 tty->print_cr("[Describe stack]"); 3049 int frame_no = 1; 3050 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3051 tty->print(" %d. ", frame_no++); 3052 fst.current()->print_value_on(tty, this); 3053 tty->cr(); 3054 } 3055} 3056 3057class PrintAndVerifyOopClosure: public OopClosure { 3058 protected: 3059 template <class T> inline void do_oop_work(T* p) { 3060 oop obj = oopDesc::load_decode_heap_oop(p); 3061 if (obj == NULL) return; 3062 tty->print(INTPTR_FORMAT ": ", p); 3063 if (obj->is_oop_or_null()) { 3064 if (obj->is_objArray()) { 3065 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 3066 } else { 3067 obj->print(); 3068 } 3069 } else { 3070 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 3071 } 3072 tty->cr(); 3073 } 3074 public: 3075 virtual void do_oop(oop* p) { do_oop_work(p); } 3076 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3077}; 3078 3079 3080static void oops_print(frame* f, const RegisterMap *map) { 3081 PrintAndVerifyOopClosure print; 3082 f->print_value(); 3083 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3084} 3085 3086// Print our all the locations that contain oops and whether they are 3087// valid or not. This useful when trying to find the oldest frame 3088// where an oop has gone bad since the frame walk is from youngest to 3089// oldest. 3090void JavaThread::trace_oops() { 3091 tty->print_cr("[Trace oops]"); 3092 frames_do(oops_print); 3093} 3094 3095 3096#ifdef ASSERT 3097// Print or validate the layout of stack frames 3098void JavaThread::print_frame_layout(int depth, bool validate_only) { 3099 ResourceMark rm; 3100 PRESERVE_EXCEPTION_MARK; 3101 FrameValues values; 3102 int frame_no = 0; 3103 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3104 fst.current()->describe(values, ++frame_no); 3105 if (depth == frame_no) break; 3106 } 3107 if (validate_only) { 3108 values.validate(); 3109 } else { 3110 tty->print_cr("[Describe stack layout]"); 3111 values.print(this); 3112 } 3113} 3114#endif 3115 3116void JavaThread::trace_stack_from(vframe* start_vf) { 3117 ResourceMark rm; 3118 int vframe_no = 1; 3119 for (vframe* f = start_vf; f; f = f->sender()) { 3120 if (f->is_java_frame()) { 3121 javaVFrame::cast(f)->print_activation(vframe_no++); 3122 } else { 3123 f->print(); 3124 } 3125 if (vframe_no > StackPrintLimit) { 3126 tty->print_cr("...<more frames>..."); 3127 return; 3128 } 3129 } 3130} 3131 3132 3133void JavaThread::trace_stack() { 3134 if (!has_last_Java_frame()) return; 3135 ResourceMark rm; 3136 HandleMark hm; 3137 RegisterMap reg_map(this); 3138 trace_stack_from(last_java_vframe(®_map)); 3139} 3140 3141 3142#endif // PRODUCT 3143 3144 3145javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3146 assert(reg_map != NULL, "a map must be given"); 3147 frame f = last_frame(); 3148 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3149 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3150 } 3151 return NULL; 3152} 3153 3154 3155Klass* JavaThread::security_get_caller_class(int depth) { 3156 vframeStream vfst(this); 3157 vfst.security_get_caller_frame(depth); 3158 if (!vfst.at_end()) { 3159 return vfst.method()->method_holder(); 3160 } 3161 return NULL; 3162} 3163 3164static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3165 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3166 CompileBroker::compiler_thread_loop(); 3167} 3168 3169// Create a CompilerThread 3170CompilerThread::CompilerThread(CompileQueue* queue, 3171 CompilerCounters* counters) 3172 : JavaThread(&compiler_thread_entry) { 3173 _env = NULL; 3174 _log = NULL; 3175 _task = NULL; 3176 _queue = queue; 3177 _counters = counters; 3178 _buffer_blob = NULL; 3179 _scanned_nmethod = NULL; 3180 _compiler = NULL; 3181 3182#ifndef PRODUCT 3183 _ideal_graph_printer = NULL; 3184#endif 3185} 3186 3187void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3188 JavaThread::oops_do(f, cld_f, cf); 3189 if (_scanned_nmethod != NULL && cf != NULL) { 3190 // Safepoints can occur when the sweeper is scanning an nmethod so 3191 // process it here to make sure it isn't unloaded in the middle of 3192 // a scan. 3193 cf->do_code_blob(_scanned_nmethod); 3194 } 3195} 3196 3197 3198// ======= Threads ======== 3199 3200// The Threads class links together all active threads, and provides 3201// operations over all threads. It is protected by its own Mutex 3202// lock, which is also used in other contexts to protect thread 3203// operations from having the thread being operated on from exiting 3204// and going away unexpectedly (e.g., safepoint synchronization) 3205 3206JavaThread* Threads::_thread_list = NULL; 3207int Threads::_number_of_threads = 0; 3208int Threads::_number_of_non_daemon_threads = 0; 3209int Threads::_return_code = 0; 3210size_t JavaThread::_stack_size_at_create = 0; 3211#ifdef ASSERT 3212bool Threads::_vm_complete = false; 3213#endif 3214 3215// All JavaThreads 3216#define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3217 3218// All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3219void Threads::threads_do(ThreadClosure* tc) { 3220 assert_locked_or_safepoint(Threads_lock); 3221 // ALL_JAVA_THREADS iterates through all JavaThreads 3222 ALL_JAVA_THREADS(p) { 3223 tc->do_thread(p); 3224 } 3225 // Someday we could have a table or list of all non-JavaThreads. 3226 // For now, just manually iterate through them. 3227 tc->do_thread(VMThread::vm_thread()); 3228 Universe::heap()->gc_threads_do(tc); 3229 WatcherThread *wt = WatcherThread::watcher_thread(); 3230 // Strictly speaking, the following NULL check isn't sufficient to make sure 3231 // the data for WatcherThread is still valid upon being examined. However, 3232 // considering that WatchThread terminates when the VM is on the way to 3233 // exit at safepoint, the chance of the above is extremely small. The right 3234 // way to prevent termination of WatcherThread would be to acquire 3235 // Terminator_lock, but we can't do that without violating the lock rank 3236 // checking in some cases. 3237 if (wt != NULL) { 3238 tc->do_thread(wt); 3239 } 3240 3241 // If CompilerThreads ever become non-JavaThreads, add them here 3242} 3243 3244 3245void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3246 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3247 3248 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3249 create_vm_init_libraries(); 3250 } 3251 3252 initialize_class(vmSymbols::java_lang_String(), CHECK); 3253 3254 // Initialize java_lang.System (needed before creating the thread) 3255 initialize_class(vmSymbols::java_lang_System(), CHECK); 3256 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3257 Handle thread_group = create_initial_thread_group(CHECK); 3258 Universe::set_main_thread_group(thread_group()); 3259 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3260 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3261 main_thread->set_threadObj(thread_object); 3262 // Set thread status to running since main thread has 3263 // been started and running. 3264 java_lang_Thread::set_thread_status(thread_object, 3265 java_lang_Thread::RUNNABLE); 3266 3267 // The VM creates & returns objects of this class. Make sure it's initialized. 3268 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3269 3270 // The VM preresolves methods to these classes. Make sure that they get initialized 3271 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3272 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3273 call_initializeSystemClass(CHECK); 3274 3275 // get the Java runtime name after java.lang.System is initialized 3276 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3277 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3278 3279 // an instance of OutOfMemory exception has been allocated earlier 3280 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3281 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3282 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3283 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3284 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3285 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3286 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3287 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3288} 3289 3290void Threads::initialize_jsr292_core_classes(TRAPS) { 3291 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3292 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3293 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3294} 3295 3296jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3297 extern void JDK_Version_init(); 3298 3299 // Check version 3300 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3301 3302 // Initialize the output stream module 3303 ostream_init(); 3304 3305 // Process java launcher properties. 3306 Arguments::process_sun_java_launcher_properties(args); 3307 3308 // Initialize the os module before using TLS 3309 os::init(); 3310 3311 // Initialize system properties. 3312 Arguments::init_system_properties(); 3313 3314 // So that JDK version can be used as a discriminator when parsing arguments 3315 JDK_Version_init(); 3316 3317 // Update/Initialize System properties after JDK version number is known 3318 Arguments::init_version_specific_system_properties(); 3319 3320 // Parse arguments 3321 jint parse_result = Arguments::parse(args); 3322 if (parse_result != JNI_OK) return parse_result; 3323 3324 os::init_before_ergo(); 3325 3326 jint ergo_result = Arguments::apply_ergo(); 3327 if (ergo_result != JNI_OK) return ergo_result; 3328 3329 if (PauseAtStartup) { 3330 os::pause(); 3331 } 3332 3333 HOTSPOT_VM_INIT_BEGIN(); 3334 3335 // Record VM creation timing statistics 3336 TraceVmCreationTime create_vm_timer; 3337 create_vm_timer.start(); 3338 3339 // Timing (must come after argument parsing) 3340 TraceTime timer("Create VM", TraceStartupTime); 3341 3342 // Initialize the os module after parsing the args 3343 jint os_init_2_result = os::init_2(); 3344 if (os_init_2_result != JNI_OK) return os_init_2_result; 3345 3346 jint adjust_after_os_result = Arguments::adjust_after_os(); 3347 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3348 3349 // initialize TLS 3350 ThreadLocalStorage::init(); 3351 3352 // Initialize output stream logging 3353 ostream_init_log(); 3354 3355 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3356 // Must be before create_vm_init_agents() 3357 if (Arguments::init_libraries_at_startup()) { 3358 convert_vm_init_libraries_to_agents(); 3359 } 3360 3361 // Launch -agentlib/-agentpath and converted -Xrun agents 3362 if (Arguments::init_agents_at_startup()) { 3363 create_vm_init_agents(); 3364 } 3365 3366 // Initialize Threads state 3367 _thread_list = NULL; 3368 _number_of_threads = 0; 3369 _number_of_non_daemon_threads = 0; 3370 3371 // Initialize global data structures and create system classes in heap 3372 vm_init_globals(); 3373 3374 // Attach the main thread to this os thread 3375 JavaThread* main_thread = new JavaThread(); 3376 main_thread->set_thread_state(_thread_in_vm); 3377 // must do this before set_active_handles and initialize_thread_local_storage 3378 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3379 // change the stack size recorded here to one based on the java thread 3380 // stacksize. This adjusted size is what is used to figure the placement 3381 // of the guard pages. 3382 main_thread->record_stack_base_and_size(); 3383 main_thread->initialize_thread_local_storage(); 3384 3385 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3386 3387 if (!main_thread->set_as_starting_thread()) { 3388 vm_shutdown_during_initialization( 3389 "Failed necessary internal allocation. Out of swap space"); 3390 delete main_thread; 3391 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3392 return JNI_ENOMEM; 3393 } 3394 3395 // Enable guard page *after* os::create_main_thread(), otherwise it would 3396 // crash Linux VM, see notes in os_linux.cpp. 3397 main_thread->create_stack_guard_pages(); 3398 3399 // Initialize Java-Level synchronization subsystem 3400 ObjectMonitor::Initialize(); 3401 3402 // Initialize global modules 3403 jint status = init_globals(); 3404 if (status != JNI_OK) { 3405 delete main_thread; 3406 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3407 return status; 3408 } 3409 3410 // Should be done after the heap is fully created 3411 main_thread->cache_global_variables(); 3412 3413 HandleMark hm; 3414 3415 { MutexLocker mu(Threads_lock); 3416 Threads::add(main_thread); 3417 } 3418 3419 // Any JVMTI raw monitors entered in onload will transition into 3420 // real raw monitor. VM is setup enough here for raw monitor enter. 3421 JvmtiExport::transition_pending_onload_raw_monitors(); 3422 3423 // Create the VMThread 3424 { TraceTime timer("Start VMThread", TraceStartupTime); 3425 VMThread::create(); 3426 Thread* vmthread = VMThread::vm_thread(); 3427 3428 if (!os::create_thread(vmthread, os::vm_thread)) { 3429 vm_exit_during_initialization("Cannot create VM thread. " 3430 "Out of system resources."); 3431 } 3432 3433 // Wait for the VM thread to become ready, and VMThread::run to initialize 3434 // Monitors can have spurious returns, must always check another state flag 3435 { 3436 MutexLocker ml(Notify_lock); 3437 os::start_thread(vmthread); 3438 while (vmthread->active_handles() == NULL) { 3439 Notify_lock->wait(); 3440 } 3441 } 3442 } 3443 3444 assert(Universe::is_fully_initialized(), "not initialized"); 3445 if (VerifyDuringStartup) { 3446 // Make sure we're starting with a clean slate. 3447 VM_Verify verify_op; 3448 VMThread::execute(&verify_op); 3449 } 3450 3451 Thread* THREAD = Thread::current(); 3452 3453 // At this point, the Universe is initialized, but we have not executed 3454 // any byte code. Now is a good time (the only time) to dump out the 3455 // internal state of the JVM for sharing. 3456 if (DumpSharedSpaces) { 3457 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3458 ShouldNotReachHere(); 3459 } 3460 3461 // Always call even when there are not JVMTI environments yet, since environments 3462 // may be attached late and JVMTI must track phases of VM execution 3463 JvmtiExport::enter_start_phase(); 3464 3465 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3466 JvmtiExport::post_vm_start(); 3467 3468 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3469 3470 // We need this for ClassDataSharing - the initial vm.info property is set 3471 // with the default value of CDS "sharing" which may be reset through 3472 // command line options. 3473 reset_vm_info_property(CHECK_JNI_ERR); 3474 3475 quicken_jni_functions(); 3476 3477 // Must be run after init_ft which initializes ft_enabled 3478 if (TRACE_INITIALIZE() != JNI_OK) { 3479 vm_exit_during_initialization("Failed to initialize tracing backend"); 3480 } 3481 3482 // Set flag that basic initialization has completed. Used by exceptions and various 3483 // debug stuff, that does not work until all basic classes have been initialized. 3484 set_init_completed(); 3485 3486 Metaspace::post_initialize(); 3487 3488 HOTSPOT_VM_INIT_END(); 3489 3490 // record VM initialization completion time 3491#if INCLUDE_MANAGEMENT 3492 Management::record_vm_init_completed(); 3493#endif // INCLUDE_MANAGEMENT 3494 3495 // Compute system loader. Note that this has to occur after set_init_completed, since 3496 // valid exceptions may be thrown in the process. 3497 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3498 // set_init_completed has just been called, causing exceptions not to be shortcut 3499 // anymore. We call vm_exit_during_initialization directly instead. 3500 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR); 3501 3502#if INCLUDE_ALL_GCS 3503 // Support for ConcurrentMarkSweep. This should be cleaned up 3504 // and better encapsulated. The ugly nested if test would go away 3505 // once things are properly refactored. XXX YSR 3506 if (UseConcMarkSweepGC || UseG1GC) { 3507 if (UseConcMarkSweepGC) { 3508 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3509 } else { 3510 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3511 } 3512 } 3513#endif // INCLUDE_ALL_GCS 3514 3515 // Always call even when there are not JVMTI environments yet, since environments 3516 // may be attached late and JVMTI must track phases of VM execution 3517 JvmtiExport::enter_live_phase(); 3518 3519 // Signal Dispatcher needs to be started before VMInit event is posted 3520 os::signal_init(); 3521 3522 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3523 if (!DisableAttachMechanism) { 3524 AttachListener::vm_start(); 3525 if (StartAttachListener || AttachListener::init_at_startup()) { 3526 AttachListener::init(); 3527 } 3528 } 3529 3530 // Launch -Xrun agents 3531 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3532 // back-end can launch with -Xdebug -Xrunjdwp. 3533 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3534 create_vm_init_libraries(); 3535 } 3536 3537 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3538 JvmtiExport::post_vm_initialized(); 3539 3540 if (TRACE_START() != JNI_OK) { 3541 vm_exit_during_initialization("Failed to start tracing backend."); 3542 } 3543 3544 if (CleanChunkPoolAsync) { 3545 Chunk::start_chunk_pool_cleaner_task(); 3546 } 3547 3548 // initialize compiler(s) 3549#if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) 3550 CompileBroker::compilation_init(); 3551#endif 3552 3553 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3554 // It is done after compilers are initialized, because otherwise compilations of 3555 // signature polymorphic MH intrinsics can be missed 3556 // (see SystemDictionary::find_method_handle_intrinsic). 3557 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3558 3559#if INCLUDE_MANAGEMENT 3560 Management::initialize(THREAD); 3561 3562 if (HAS_PENDING_EXCEPTION) { 3563 // management agent fails to start possibly due to 3564 // configuration problem and is responsible for printing 3565 // stack trace if appropriate. Simply exit VM. 3566 vm_exit(1); 3567 } 3568#endif // INCLUDE_MANAGEMENT 3569 3570 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3571 if (MemProfiling) MemProfiler::engage(); 3572 StatSampler::engage(); 3573 if (CheckJNICalls) JniPeriodicChecker::engage(); 3574 3575 BiasedLocking::init(); 3576 3577#if INCLUDE_RTM_OPT 3578 RTMLockingCounters::init(); 3579#endif 3580 3581 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3582 call_postVMInitHook(THREAD); 3583 // The Java side of PostVMInitHook.run must deal with all 3584 // exceptions and provide means of diagnosis. 3585 if (HAS_PENDING_EXCEPTION) { 3586 CLEAR_PENDING_EXCEPTION; 3587 } 3588 } 3589 3590 { 3591 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 3592 // Make sure the watcher thread can be started by WatcherThread::start() 3593 // or by dynamic enrollment. 3594 WatcherThread::make_startable(); 3595 // Start up the WatcherThread if there are any periodic tasks 3596 // NOTE: All PeriodicTasks should be registered by now. If they 3597 // aren't, late joiners might appear to start slowly (we might 3598 // take a while to process their first tick). 3599 if (PeriodicTask::num_tasks() > 0) { 3600 WatcherThread::start(); 3601 } 3602 } 3603 3604 // Give os specific code one last chance to start 3605 os::init_3(); 3606 3607 create_vm_timer.end(); 3608#ifdef ASSERT 3609 _vm_complete = true; 3610#endif 3611 return JNI_OK; 3612} 3613 3614// type for the Agent_OnLoad and JVM_OnLoad entry points 3615extern "C" { 3616 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3617} 3618// Find a command line agent library and return its entry point for 3619// -agentlib: -agentpath: -Xrun 3620// num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3621static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3622 const char *on_load_symbols[], 3623 size_t num_symbol_entries) { 3624 OnLoadEntry_t on_load_entry = NULL; 3625 void *library = NULL; 3626 3627 if (!agent->valid()) { 3628 char buffer[JVM_MAXPATHLEN]; 3629 char ebuf[1024]; 3630 const char *name = agent->name(); 3631 const char *msg = "Could not find agent library "; 3632 3633 // First check to see if agent is statically linked into executable 3634 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3635 library = agent->os_lib(); 3636 } else if (agent->is_absolute_path()) { 3637 library = os::dll_load(name, ebuf, sizeof ebuf); 3638 if (library == NULL) { 3639 const char *sub_msg = " in absolute path, with error: "; 3640 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3641 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3642 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3643 // If we can't find the agent, exit. 3644 vm_exit_during_initialization(buf, NULL); 3645 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3646 } 3647 } else { 3648 // Try to load the agent from the standard dll directory 3649 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3650 name)) { 3651 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3652 } 3653 if (library == NULL) { // Try the local directory 3654 char ns[1] = {0}; 3655 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3656 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3657 } 3658 if (library == NULL) { 3659 const char *sub_msg = " on the library path, with error: "; 3660 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3661 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3662 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3663 // If we can't find the agent, exit. 3664 vm_exit_during_initialization(buf, NULL); 3665 FREE_C_HEAP_ARRAY(char, buf, mtThread); 3666 } 3667 } 3668 } 3669 agent->set_os_lib(library); 3670 agent->set_valid(); 3671 } 3672 3673 // Find the OnLoad function. 3674 on_load_entry = 3675 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3676 false, 3677 on_load_symbols, 3678 num_symbol_entries)); 3679 return on_load_entry; 3680} 3681 3682// Find the JVM_OnLoad entry point 3683static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3684 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3685 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3686} 3687 3688// Find the Agent_OnLoad entry point 3689static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3690 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3691 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3692} 3693 3694// For backwards compatibility with -Xrun 3695// Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3696// treated like -agentpath: 3697// Must be called before agent libraries are created 3698void Threads::convert_vm_init_libraries_to_agents() { 3699 AgentLibrary* agent; 3700 AgentLibrary* next; 3701 3702 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3703 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3704 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3705 3706 // If there is an JVM_OnLoad function it will get called later, 3707 // otherwise see if there is an Agent_OnLoad 3708 if (on_load_entry == NULL) { 3709 on_load_entry = lookup_agent_on_load(agent); 3710 if (on_load_entry != NULL) { 3711 // switch it to the agent list -- so that Agent_OnLoad will be called, 3712 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3713 Arguments::convert_library_to_agent(agent); 3714 } else { 3715 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3716 } 3717 } 3718 } 3719} 3720 3721// Create agents for -agentlib: -agentpath: and converted -Xrun 3722// Invokes Agent_OnLoad 3723// Called very early -- before JavaThreads exist 3724void Threads::create_vm_init_agents() { 3725 extern struct JavaVM_ main_vm; 3726 AgentLibrary* agent; 3727 3728 JvmtiExport::enter_onload_phase(); 3729 3730 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3731 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3732 3733 if (on_load_entry != NULL) { 3734 // Invoke the Agent_OnLoad function 3735 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3736 if (err != JNI_OK) { 3737 vm_exit_during_initialization("agent library failed to init", agent->name()); 3738 } 3739 } else { 3740 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3741 } 3742 } 3743 JvmtiExport::enter_primordial_phase(); 3744} 3745 3746extern "C" { 3747 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3748} 3749 3750void Threads::shutdown_vm_agents() { 3751 // Send any Agent_OnUnload notifications 3752 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3753 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3754 extern struct JavaVM_ main_vm; 3755 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3756 3757 // Find the Agent_OnUnload function. 3758 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3759 os::find_agent_function(agent, 3760 false, 3761 on_unload_symbols, 3762 num_symbol_entries)); 3763 3764 // Invoke the Agent_OnUnload function 3765 if (unload_entry != NULL) { 3766 JavaThread* thread = JavaThread::current(); 3767 ThreadToNativeFromVM ttn(thread); 3768 HandleMark hm(thread); 3769 (*unload_entry)(&main_vm); 3770 } 3771 } 3772} 3773 3774// Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3775// Invokes JVM_OnLoad 3776void Threads::create_vm_init_libraries() { 3777 extern struct JavaVM_ main_vm; 3778 AgentLibrary* agent; 3779 3780 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3781 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3782 3783 if (on_load_entry != NULL) { 3784 // Invoke the JVM_OnLoad function 3785 JavaThread* thread = JavaThread::current(); 3786 ThreadToNativeFromVM ttn(thread); 3787 HandleMark hm(thread); 3788 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3789 if (err != JNI_OK) { 3790 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3791 } 3792 } else { 3793 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3794 } 3795 } 3796} 3797 3798// Last thread running calls java.lang.Shutdown.shutdown() 3799void JavaThread::invoke_shutdown_hooks() { 3800 HandleMark hm(this); 3801 3802 // We could get here with a pending exception, if so clear it now. 3803 if (this->has_pending_exception()) { 3804 this->clear_pending_exception(); 3805 } 3806 3807 EXCEPTION_MARK; 3808 Klass* k = 3809 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3810 THREAD); 3811 if (k != NULL) { 3812 // SystemDictionary::resolve_or_null will return null if there was 3813 // an exception. If we cannot load the Shutdown class, just don't 3814 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3815 // and finalizers (if runFinalizersOnExit is set) won't be run. 3816 // Note that if a shutdown hook was registered or runFinalizersOnExit 3817 // was called, the Shutdown class would have already been loaded 3818 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3819 instanceKlassHandle shutdown_klass (THREAD, k); 3820 JavaValue result(T_VOID); 3821 JavaCalls::call_static(&result, 3822 shutdown_klass, 3823 vmSymbols::shutdown_method_name(), 3824 vmSymbols::void_method_signature(), 3825 THREAD); 3826 } 3827 CLEAR_PENDING_EXCEPTION; 3828} 3829 3830// Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3831// the program falls off the end of main(). Another VM exit path is through 3832// vm_exit() when the program calls System.exit() to return a value or when 3833// there is a serious error in VM. The two shutdown paths are not exactly 3834// the same, but they share Shutdown.shutdown() at Java level and before_exit() 3835// and VM_Exit op at VM level. 3836// 3837// Shutdown sequence: 3838// + Shutdown native memory tracking if it is on 3839// + Wait until we are the last non-daemon thread to execute 3840// <-- every thing is still working at this moment --> 3841// + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3842// shutdown hooks, run finalizers if finalization-on-exit 3843// + Call before_exit(), prepare for VM exit 3844// > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3845// currently the only user of this mechanism is File.deleteOnExit()) 3846// > stop flat profiler, StatSampler, watcher thread, CMS threads, 3847// post thread end and vm death events to JVMTI, 3848// stop signal thread 3849// + Call JavaThread::exit(), it will: 3850// > release JNI handle blocks, remove stack guard pages 3851// > remove this thread from Threads list 3852// <-- no more Java code from this thread after this point --> 3853// + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3854// the compiler threads at safepoint 3855// <-- do not use anything that could get blocked by Safepoint --> 3856// + Disable tracing at JNI/JVM barriers 3857// + Set _vm_exited flag for threads that are still running native code 3858// + Delete this thread 3859// + Call exit_globals() 3860// > deletes tty 3861// > deletes PerfMemory resources 3862// + Return to caller 3863 3864bool Threads::destroy_vm() { 3865 JavaThread* thread = JavaThread::current(); 3866 3867#ifdef ASSERT 3868 _vm_complete = false; 3869#endif 3870 // Wait until we are the last non-daemon thread to execute 3871 { MutexLocker nu(Threads_lock); 3872 while (Threads::number_of_non_daemon_threads() > 1) 3873 // This wait should make safepoint checks, wait without a timeout, 3874 // and wait as a suspend-equivalent condition. 3875 // 3876 // Note: If the FlatProfiler is running and this thread is waiting 3877 // for another non-daemon thread to finish, then the FlatProfiler 3878 // is waiting for the external suspend request on this thread to 3879 // complete. wait_for_ext_suspend_completion() will eventually 3880 // timeout, but that takes time. Making this wait a suspend- 3881 // equivalent condition solves that timeout problem. 3882 // 3883 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3884 Mutex::_as_suspend_equivalent_flag); 3885 } 3886 3887 // Hang forever on exit if we are reporting an error. 3888 if (ShowMessageBoxOnError && is_error_reported()) { 3889 os::infinite_sleep(); 3890 } 3891 os::wait_for_keypress_at_exit(); 3892 3893 // run Java level shutdown hooks 3894 thread->invoke_shutdown_hooks(); 3895 3896 before_exit(thread); 3897 3898 thread->exit(true); 3899 3900 // Stop VM thread. 3901 { 3902 // 4945125 The vm thread comes to a safepoint during exit. 3903 // GC vm_operations can get caught at the safepoint, and the 3904 // heap is unparseable if they are caught. Grab the Heap_lock 3905 // to prevent this. The GC vm_operations will not be able to 3906 // queue until after the vm thread is dead. After this point, 3907 // we'll never emerge out of the safepoint before the VM exits. 3908 3909 MutexLocker ml(Heap_lock); 3910 3911 VMThread::wait_for_vm_thread_exit(); 3912 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3913 VMThread::destroy(); 3914 } 3915 3916 // clean up ideal graph printers 3917#if defined(COMPILER2) && !defined(PRODUCT) 3918 IdealGraphPrinter::clean_up(); 3919#endif 3920 3921 // Now, all Java threads are gone except daemon threads. Daemon threads 3922 // running Java code or in VM are stopped by the Safepoint. However, 3923 // daemon threads executing native code are still running. But they 3924 // will be stopped at native=>Java/VM barriers. Note that we can't 3925 // simply kill or suspend them, as it is inherently deadlock-prone. 3926 3927#ifndef PRODUCT 3928 // disable function tracing at JNI/JVM barriers 3929 TraceJNICalls = false; 3930 TraceJVMCalls = false; 3931 TraceRuntimeCalls = false; 3932#endif 3933 3934 VM_Exit::set_vm_exited(); 3935 3936 notify_vm_shutdown(); 3937 3938 delete thread; 3939 3940 // exit_globals() will delete tty 3941 exit_globals(); 3942 3943 return true; 3944} 3945 3946 3947jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3948 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3949 return is_supported_jni_version(version); 3950} 3951 3952 3953jboolean Threads::is_supported_jni_version(jint version) { 3954 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3955 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3956 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3957 if (version == JNI_VERSION_1_8) return JNI_TRUE; 3958 return JNI_FALSE; 3959} 3960 3961 3962void Threads::add(JavaThread* p, bool force_daemon) { 3963 // The threads lock must be owned at this point 3964 assert_locked_or_safepoint(Threads_lock); 3965 3966 // See the comment for this method in thread.hpp for its purpose and 3967 // why it is called here. 3968 p->initialize_queues(); 3969 p->set_next(_thread_list); 3970 _thread_list = p; 3971 _number_of_threads++; 3972 oop threadObj = p->threadObj(); 3973 bool daemon = true; 3974 // Bootstrapping problem: threadObj can be null for initial 3975 // JavaThread (or for threads attached via JNI) 3976 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3977 _number_of_non_daemon_threads++; 3978 daemon = false; 3979 } 3980 3981 ThreadService::add_thread(p, daemon); 3982 3983 // Possible GC point. 3984 Events::log(p, "Thread added: " INTPTR_FORMAT, p); 3985} 3986 3987void Threads::remove(JavaThread* p) { 3988 // Extra scope needed for Thread_lock, so we can check 3989 // that we do not remove thread without safepoint code notice 3990 { MutexLocker ml(Threads_lock); 3991 3992 assert(includes(p), "p must be present"); 3993 3994 JavaThread* current = _thread_list; 3995 JavaThread* prev = NULL; 3996 3997 while (current != p) { 3998 prev = current; 3999 current = current->next(); 4000 } 4001 4002 if (prev) { 4003 prev->set_next(current->next()); 4004 } else { 4005 _thread_list = p->next(); 4006 } 4007 _number_of_threads--; 4008 oop threadObj = p->threadObj(); 4009 bool daemon = true; 4010 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4011 _number_of_non_daemon_threads--; 4012 daemon = false; 4013 4014 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4015 // on destroy_vm will wake up. 4016 if (number_of_non_daemon_threads() == 1) { 4017 Threads_lock->notify_all(); 4018 } 4019 } 4020 ThreadService::remove_thread(p, daemon); 4021 4022 // Make sure that safepoint code disregard this thread. This is needed since 4023 // the thread might mess around with locks after this point. This can cause it 4024 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4025 // of this thread since it is removed from the queue. 4026 p->set_terminated_value(); 4027 } // unlock Threads_lock 4028 4029 // Since Events::log uses a lock, we grab it outside the Threads_lock 4030 Events::log(p, "Thread exited: " INTPTR_FORMAT, p); 4031} 4032 4033// Threads_lock must be held when this is called (or must be called during a safepoint) 4034bool Threads::includes(JavaThread* p) { 4035 assert(Threads_lock->is_locked(), "sanity check"); 4036 ALL_JAVA_THREADS(q) { 4037 if (q == p) { 4038 return true; 4039 } 4040 } 4041 return false; 4042} 4043 4044// Operations on the Threads list for GC. These are not explicitly locked, 4045// but the garbage collector must provide a safe context for them to run. 4046// In particular, these things should never be called when the Threads_lock 4047// is held by some other thread. (Note: the Safepoint abstraction also 4048// uses the Threads_lock to guarantee this property. It also makes sure that 4049// all threads gets blocked when exiting or starting). 4050 4051void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4052 ALL_JAVA_THREADS(p) { 4053 p->oops_do(f, cld_f, cf); 4054 } 4055 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4056} 4057 4058void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4059 // Introduce a mechanism allowing parallel threads to claim threads as 4060 // root groups. Overhead should be small enough to use all the time, 4061 // even in sequential code. 4062 SharedHeap* sh = SharedHeap::heap(); 4063 // Cannot yet substitute active_workers for n_par_threads 4064 // because of G1CollectedHeap::verify() use of 4065 // SharedHeap::process_roots(). n_par_threads == 0 will 4066 // turn off parallelism in process_roots while active_workers 4067 // is being used for parallelism elsewhere. 4068 bool is_par = sh->n_par_threads() > 0; 4069 assert(!is_par || 4070 (SharedHeap::heap()->n_par_threads() == 4071 SharedHeap::heap()->workers()->active_workers()), "Mismatch"); 4072 int cp = SharedHeap::heap()->strong_roots_parity(); 4073 ALL_JAVA_THREADS(p) { 4074 if (p->claim_oops_do(is_par, cp)) { 4075 p->oops_do(f, cld_f, cf); 4076 } 4077 } 4078 VMThread* vmt = VMThread::vm_thread(); 4079 if (vmt->claim_oops_do(is_par, cp)) { 4080 vmt->oops_do(f, cld_f, cf); 4081 } 4082} 4083 4084#if INCLUDE_ALL_GCS 4085// Used by ParallelScavenge 4086void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4087 ALL_JAVA_THREADS(p) { 4088 q->enqueue(new ThreadRootsTask(p)); 4089 } 4090 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4091} 4092 4093// Used by Parallel Old 4094void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4095 ALL_JAVA_THREADS(p) { 4096 q->enqueue(new ThreadRootsMarkingTask(p)); 4097 } 4098 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4099} 4100#endif // INCLUDE_ALL_GCS 4101 4102void Threads::nmethods_do(CodeBlobClosure* cf) { 4103 ALL_JAVA_THREADS(p) { 4104 p->nmethods_do(cf); 4105 } 4106 VMThread::vm_thread()->nmethods_do(cf); 4107} 4108 4109void Threads::metadata_do(void f(Metadata*)) { 4110 ALL_JAVA_THREADS(p) { 4111 p->metadata_do(f); 4112 } 4113} 4114 4115void Threads::deoptimized_wrt_marked_nmethods() { 4116 ALL_JAVA_THREADS(p) { 4117 p->deoptimized_wrt_marked_nmethods(); 4118 } 4119} 4120 4121 4122// Get count Java threads that are waiting to enter the specified monitor. 4123GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4124 address monitor, 4125 bool doLock) { 4126 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4127 "must grab Threads_lock or be at safepoint"); 4128 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4129 4130 int i = 0; 4131 { 4132 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4133 ALL_JAVA_THREADS(p) { 4134 if (p->is_Compiler_thread()) continue; 4135 4136 address pending = (address)p->current_pending_monitor(); 4137 if (pending == monitor) { // found a match 4138 if (i < count) result->append(p); // save the first count matches 4139 i++; 4140 } 4141 } 4142 } 4143 return result; 4144} 4145 4146 4147JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4148 bool doLock) { 4149 assert(doLock || 4150 Threads_lock->owned_by_self() || 4151 SafepointSynchronize::is_at_safepoint(), 4152 "must grab Threads_lock or be at safepoint"); 4153 4154 // NULL owner means not locked so we can skip the search 4155 if (owner == NULL) return NULL; 4156 4157 { 4158 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4159 ALL_JAVA_THREADS(p) { 4160 // first, see if owner is the address of a Java thread 4161 if (owner == (address)p) return p; 4162 } 4163 } 4164 // Cannot assert on lack of success here since this function may be 4165 // used by code that is trying to report useful problem information 4166 // like deadlock detection. 4167 if (UseHeavyMonitors) return NULL; 4168 4169 // If we didn't find a matching Java thread and we didn't force use of 4170 // heavyweight monitors, then the owner is the stack address of the 4171 // Lock Word in the owning Java thread's stack. 4172 // 4173 JavaThread* the_owner = NULL; 4174 { 4175 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4176 ALL_JAVA_THREADS(q) { 4177 if (q->is_lock_owned(owner)) { 4178 the_owner = q; 4179 break; 4180 } 4181 } 4182 } 4183 // cannot assert on lack of success here; see above comment 4184 return the_owner; 4185} 4186 4187// Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4188void Threads::print_on(outputStream* st, bool print_stacks, 4189 bool internal_format, bool print_concurrent_locks) { 4190 char buf[32]; 4191 st->print_cr("%s", os::local_time_string(buf, sizeof(buf))); 4192 4193 st->print_cr("Full thread dump %s (%s %s):", 4194 Abstract_VM_Version::vm_name(), 4195 Abstract_VM_Version::vm_release(), 4196 Abstract_VM_Version::vm_info_string()); 4197 st->cr(); 4198 4199#if INCLUDE_ALL_GCS 4200 // Dump concurrent locks 4201 ConcurrentLocksDump concurrent_locks; 4202 if (print_concurrent_locks) { 4203 concurrent_locks.dump_at_safepoint(); 4204 } 4205#endif // INCLUDE_ALL_GCS 4206 4207 ALL_JAVA_THREADS(p) { 4208 ResourceMark rm; 4209 p->print_on(st); 4210 if (print_stacks) { 4211 if (internal_format) { 4212 p->trace_stack(); 4213 } else { 4214 p->print_stack_on(st); 4215 } 4216 } 4217 st->cr(); 4218#if INCLUDE_ALL_GCS 4219 if (print_concurrent_locks) { 4220 concurrent_locks.print_locks_on(p, st); 4221 } 4222#endif // INCLUDE_ALL_GCS 4223 } 4224 4225 VMThread::vm_thread()->print_on(st); 4226 st->cr(); 4227 Universe::heap()->print_gc_threads_on(st); 4228 WatcherThread* wt = WatcherThread::watcher_thread(); 4229 if (wt != NULL) { 4230 wt->print_on(st); 4231 st->cr(); 4232 } 4233 CompileBroker::print_compiler_threads_on(st); 4234 st->flush(); 4235} 4236 4237// Threads::print_on_error() is called by fatal error handler. It's possible 4238// that VM is not at safepoint and/or current thread is inside signal handler. 4239// Don't print stack trace, as the stack may not be walkable. Don't allocate 4240// memory (even in resource area), it might deadlock the error handler. 4241void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4242 int buflen) { 4243 bool found_current = false; 4244 st->print_cr("Java Threads: ( => current thread )"); 4245 ALL_JAVA_THREADS(thread) { 4246 bool is_current = (current == thread); 4247 found_current = found_current || is_current; 4248 4249 st->print("%s", is_current ? "=>" : " "); 4250 4251 st->print(PTR_FORMAT, thread); 4252 st->print(" "); 4253 thread->print_on_error(st, buf, buflen); 4254 st->cr(); 4255 } 4256 st->cr(); 4257 4258 st->print_cr("Other Threads:"); 4259 if (VMThread::vm_thread()) { 4260 bool is_current = (current == VMThread::vm_thread()); 4261 found_current = found_current || is_current; 4262 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4263 4264 st->print(PTR_FORMAT, VMThread::vm_thread()); 4265 st->print(" "); 4266 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4267 st->cr(); 4268 } 4269 WatcherThread* wt = WatcherThread::watcher_thread(); 4270 if (wt != NULL) { 4271 bool is_current = (current == wt); 4272 found_current = found_current || is_current; 4273 st->print("%s", is_current ? "=>" : " "); 4274 4275 st->print(PTR_FORMAT, wt); 4276 st->print(" "); 4277 wt->print_on_error(st, buf, buflen); 4278 st->cr(); 4279 } 4280 if (!found_current) { 4281 st->cr(); 4282 st->print("=>" PTR_FORMAT " (exited) ", current); 4283 current->print_on_error(st, buf, buflen); 4284 st->cr(); 4285 } 4286} 4287 4288// Internal SpinLock and Mutex 4289// Based on ParkEvent 4290 4291// Ad-hoc mutual exclusion primitives: SpinLock and Mux 4292// 4293// We employ SpinLocks _only for low-contention, fixed-length 4294// short-duration critical sections where we're concerned 4295// about native mutex_t or HotSpot Mutex:: latency. 4296// The mux construct provides a spin-then-block mutual exclusion 4297// mechanism. 4298// 4299// Testing has shown that contention on the ListLock guarding gFreeList 4300// is common. If we implement ListLock as a simple SpinLock it's common 4301// for the JVM to devolve to yielding with little progress. This is true 4302// despite the fact that the critical sections protected by ListLock are 4303// extremely short. 4304// 4305// TODO-FIXME: ListLock should be of type SpinLock. 4306// We should make this a 1st-class type, integrated into the lock 4307// hierarchy as leaf-locks. Critically, the SpinLock structure 4308// should have sufficient padding to avoid false-sharing and excessive 4309// cache-coherency traffic. 4310 4311 4312typedef volatile int SpinLockT; 4313 4314void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4315 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4316 return; // normal fast-path return 4317 } 4318 4319 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4320 TEVENT(SpinAcquire - ctx); 4321 int ctr = 0; 4322 int Yields = 0; 4323 for (;;) { 4324 while (*adr != 0) { 4325 ++ctr; 4326 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4327 if (Yields > 5) { 4328 os::naked_short_sleep(1); 4329 } else { 4330 os::naked_yield(); 4331 ++Yields; 4332 } 4333 } else { 4334 SpinPause(); 4335 } 4336 } 4337 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4338 } 4339} 4340 4341void Thread::SpinRelease(volatile int * adr) { 4342 assert(*adr != 0, "invariant"); 4343 OrderAccess::fence(); // guarantee at least release consistency. 4344 // Roach-motel semantics. 4345 // It's safe if subsequent LDs and STs float "up" into the critical section, 4346 // but prior LDs and STs within the critical section can't be allowed 4347 // to reorder or float past the ST that releases the lock. 4348 // Loads and stores in the critical section - which appear in program 4349 // order before the store that releases the lock - must also appear 4350 // before the store that releases the lock in memory visibility order. 4351 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4352 // the ST of 0 into the lock-word which releases the lock, so fence 4353 // more than covers this on all platforms. 4354 *adr = 0; 4355} 4356 4357// muxAcquire and muxRelease: 4358// 4359// * muxAcquire and muxRelease support a single-word lock-word construct. 4360// The LSB of the word is set IFF the lock is held. 4361// The remainder of the word points to the head of a singly-linked list 4362// of threads blocked on the lock. 4363// 4364// * The current implementation of muxAcquire-muxRelease uses its own 4365// dedicated Thread._MuxEvent instance. If we're interested in 4366// minimizing the peak number of extant ParkEvent instances then 4367// we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4368// as certain invariants were satisfied. Specifically, care would need 4369// to be taken with regards to consuming unpark() "permits". 4370// A safe rule of thumb is that a thread would never call muxAcquire() 4371// if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4372// park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4373// consume an unpark() permit intended for monitorenter, for instance. 4374// One way around this would be to widen the restricted-range semaphore 4375// implemented in park(). Another alternative would be to provide 4376// multiple instances of the PlatformEvent() for each thread. One 4377// instance would be dedicated to muxAcquire-muxRelease, for instance. 4378// 4379// * Usage: 4380// -- Only as leaf locks 4381// -- for short-term locking only as muxAcquire does not perform 4382// thread state transitions. 4383// 4384// Alternatives: 4385// * We could implement muxAcquire and muxRelease with MCS or CLH locks 4386// but with parking or spin-then-park instead of pure spinning. 4387// * Use Taura-Oyama-Yonenzawa locks. 4388// * It's possible to construct a 1-0 lock if we encode the lockword as 4389// (List,LockByte). Acquire will CAS the full lockword while Release 4390// will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4391// acquiring threads use timers (ParkTimed) to detect and recover from 4392// the stranding window. Thread/Node structures must be aligned on 256-byte 4393// boundaries by using placement-new. 4394// * Augment MCS with advisory back-link fields maintained with CAS(). 4395// Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4396// The validity of the backlinks must be ratified before we trust the value. 4397// If the backlinks are invalid the exiting thread must back-track through the 4398// the forward links, which are always trustworthy. 4399// * Add a successor indication. The LockWord is currently encoded as 4400// (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4401// to provide the usual futile-wakeup optimization. 4402// See RTStt for details. 4403// * Consider schedctl.sc_nopreempt to cover the critical section. 4404// 4405 4406 4407typedef volatile intptr_t MutexT; // Mux Lock-word 4408enum MuxBits { LOCKBIT = 1 }; 4409 4410void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4411 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4412 if (w == 0) return; 4413 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4414 return; 4415 } 4416 4417 TEVENT(muxAcquire - Contention); 4418 ParkEvent * const Self = Thread::current()->_MuxEvent; 4419 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4420 for (;;) { 4421 int its = (os::is_MP() ? 100 : 0) + 1; 4422 4423 // Optional spin phase: spin-then-park strategy 4424 while (--its >= 0) { 4425 w = *Lock; 4426 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4427 return; 4428 } 4429 } 4430 4431 Self->reset(); 4432 Self->OnList = intptr_t(Lock); 4433 // The following fence() isn't _strictly necessary as the subsequent 4434 // CAS() both serializes execution and ratifies the fetched *Lock value. 4435 OrderAccess::fence(); 4436 for (;;) { 4437 w = *Lock; 4438 if ((w & LOCKBIT) == 0) { 4439 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4440 Self->OnList = 0; // hygiene - allows stronger asserts 4441 return; 4442 } 4443 continue; // Interference -- *Lock changed -- Just retry 4444 } 4445 assert(w & LOCKBIT, "invariant"); 4446 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4447 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4448 } 4449 4450 while (Self->OnList != 0) { 4451 Self->park(); 4452 } 4453 } 4454} 4455 4456void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4457 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4458 if (w == 0) return; 4459 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4460 return; 4461 } 4462 4463 TEVENT(muxAcquire - Contention); 4464 ParkEvent * ReleaseAfter = NULL; 4465 if (ev == NULL) { 4466 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4467 } 4468 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4469 for (;;) { 4470 guarantee(ev->OnList == 0, "invariant"); 4471 int its = (os::is_MP() ? 100 : 0) + 1; 4472 4473 // Optional spin phase: spin-then-park strategy 4474 while (--its >= 0) { 4475 w = *Lock; 4476 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4477 if (ReleaseAfter != NULL) { 4478 ParkEvent::Release(ReleaseAfter); 4479 } 4480 return; 4481 } 4482 } 4483 4484 ev->reset(); 4485 ev->OnList = intptr_t(Lock); 4486 // The following fence() isn't _strictly necessary as the subsequent 4487 // CAS() both serializes execution and ratifies the fetched *Lock value. 4488 OrderAccess::fence(); 4489 for (;;) { 4490 w = *Lock; 4491 if ((w & LOCKBIT) == 0) { 4492 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4493 ev->OnList = 0; 4494 // We call ::Release while holding the outer lock, thus 4495 // artificially lengthening the critical section. 4496 // Consider deferring the ::Release() until the subsequent unlock(), 4497 // after we've dropped the outer lock. 4498 if (ReleaseAfter != NULL) { 4499 ParkEvent::Release(ReleaseAfter); 4500 } 4501 return; 4502 } 4503 continue; // Interference -- *Lock changed -- Just retry 4504 } 4505 assert(w & LOCKBIT, "invariant"); 4506 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4507 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4508 } 4509 4510 while (ev->OnList != 0) { 4511 ev->park(); 4512 } 4513 } 4514} 4515 4516// Release() must extract a successor from the list and then wake that thread. 4517// It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4518// similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4519// Release() would : 4520// (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4521// (B) Extract a successor from the private list "in-hand" 4522// (C) attempt to CAS() the residual back into *Lock over null. 4523// If there were any newly arrived threads and the CAS() would fail. 4524// In that case Release() would detach the RATs, re-merge the list in-hand 4525// with the RATs and repeat as needed. Alternately, Release() might 4526// detach and extract a successor, but then pass the residual list to the wakee. 4527// The wakee would be responsible for reattaching and remerging before it 4528// competed for the lock. 4529// 4530// Both "pop" and DMR are immune from ABA corruption -- there can be 4531// multiple concurrent pushers, but only one popper or detacher. 4532// This implementation pops from the head of the list. This is unfair, 4533// but tends to provide excellent throughput as hot threads remain hot. 4534// (We wake recently run threads first). 4535// 4536// All paths through muxRelease() will execute a CAS. 4537// Release consistency -- We depend on the CAS in muxRelease() to provide full 4538// bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4539// executed within the critical section are complete and globally visible before the 4540// store (CAS) to the lock-word that releases the lock becomes globally visible. 4541void Thread::muxRelease(volatile intptr_t * Lock) { 4542 for (;;) { 4543 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4544 assert(w & LOCKBIT, "invariant"); 4545 if (w == LOCKBIT) return; 4546 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4547 assert(List != NULL, "invariant"); 4548 assert(List->OnList == intptr_t(Lock), "invariant"); 4549 ParkEvent * const nxt = List->ListNext; 4550 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4551 4552 // The following CAS() releases the lock and pops the head element. 4553 // The CAS() also ratifies the previously fetched lock-word value. 4554 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4555 continue; 4556 } 4557 List->OnList = 0; 4558 OrderAccess::fence(); 4559 List->unpark(); 4560 return; 4561 } 4562} 4563 4564 4565void Threads::verify() { 4566 ALL_JAVA_THREADS(p) { 4567 p->verify(); 4568 } 4569 VMThread* thread = VMThread::vm_thread(); 4570 if (thread != NULL) thread->verify(); 4571} 4572