thread.cpp revision 7551:c75901698a47
1/* 2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26#include "classfile/classLoader.hpp" 27#include "classfile/javaClasses.hpp" 28#include "classfile/systemDictionary.hpp" 29#include "classfile/vmSymbols.hpp" 30#include "code/codeCache.hpp" 31#include "code/scopeDesc.hpp" 32#include "compiler/compileBroker.hpp" 33#include "interpreter/interpreter.hpp" 34#include "interpreter/linkResolver.hpp" 35#include "interpreter/oopMapCache.hpp" 36#include "jvmtifiles/jvmtiEnv.hpp" 37#include "memory/gcLocker.inline.hpp" 38#include "memory/metaspaceShared.hpp" 39#include "memory/oopFactory.hpp" 40#include "memory/universe.inline.hpp" 41#include "oops/instanceKlass.hpp" 42#include "oops/objArrayOop.hpp" 43#include "oops/oop.inline.hpp" 44#include "oops/symbol.hpp" 45#include "prims/jvm_misc.hpp" 46#include "prims/jvmtiExport.hpp" 47#include "prims/jvmtiThreadState.hpp" 48#include "prims/privilegedStack.hpp" 49#include "runtime/arguments.hpp" 50#include "runtime/atomic.inline.hpp" 51#include "runtime/biasedLocking.hpp" 52#include "runtime/deoptimization.hpp" 53#include "runtime/fprofiler.hpp" 54#include "runtime/frame.inline.hpp" 55#include "runtime/init.hpp" 56#include "runtime/interfaceSupport.hpp" 57#include "runtime/java.hpp" 58#include "runtime/javaCalls.hpp" 59#include "runtime/jniPeriodicChecker.hpp" 60#include "runtime/memprofiler.hpp" 61#include "runtime/mutexLocker.hpp" 62#include "runtime/objectMonitor.hpp" 63#include "runtime/orderAccess.inline.hpp" 64#include "runtime/osThread.hpp" 65#include "runtime/safepoint.hpp" 66#include "runtime/sharedRuntime.hpp" 67#include "runtime/statSampler.hpp" 68#include "runtime/stubRoutines.hpp" 69#include "runtime/sweeper.hpp" 70#include "runtime/task.hpp" 71#include "runtime/thread.inline.hpp" 72#include "runtime/threadCritical.hpp" 73#include "runtime/threadLocalStorage.hpp" 74#include "runtime/vframe.hpp" 75#include "runtime/vframeArray.hpp" 76#include "runtime/vframe_hp.hpp" 77#include "runtime/vmThread.hpp" 78#include "runtime/vm_operations.hpp" 79#include "runtime/vm_version.hpp" 80#include "services/attachListener.hpp" 81#include "services/management.hpp" 82#include "services/memTracker.hpp" 83#include "services/threadService.hpp" 84#include "trace/tracing.hpp" 85#include "trace/traceMacros.hpp" 86#include "utilities/defaultStream.hpp" 87#include "utilities/dtrace.hpp" 88#include "utilities/events.hpp" 89#include "utilities/preserveException.hpp" 90#include "utilities/macros.hpp" 91#if INCLUDE_ALL_GCS 92#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 93#include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 94#include "gc_implementation/parallelScavenge/pcTasks.hpp" 95#endif // INCLUDE_ALL_GCS 96#ifdef COMPILER1 97#include "c1/c1_Compiler.hpp" 98#endif 99#ifdef COMPILER2 100#include "opto/c2compiler.hpp" 101#include "opto/idealGraphPrinter.hpp" 102#endif 103#if INCLUDE_RTM_OPT 104#include "runtime/rtmLocking.hpp" 105#endif 106 107PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC 108 109#ifdef DTRACE_ENABLED 110 111// Only bother with this argument setup if dtrace is available 112 113 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 114 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 115 116 #define DTRACE_THREAD_PROBE(probe, javathread) \ 117 { \ 118 ResourceMark rm(this); \ 119 int len = 0; \ 120 const char* name = (javathread)->get_thread_name(); \ 121 len = strlen(name); \ 122 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 123 (char *) name, len, \ 124 java_lang_Thread::thread_id((javathread)->threadObj()), \ 125 (uintptr_t) (javathread)->osthread()->thread_id(), \ 126 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 127 } 128 129#else // ndef DTRACE_ENABLED 130 131 #define DTRACE_THREAD_PROBE(probe, javathread) 132 133#endif // ndef DTRACE_ENABLED 134 135 136// Class hierarchy 137// - Thread 138// - VMThread 139// - WatcherThread 140// - ConcurrentMarkSweepThread 141// - JavaThread 142// - CompilerThread 143 144// ======= Thread ======== 145// Support for forcing alignment of thread objects for biased locking 146void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 147 if (UseBiasedLocking) { 148 const int alignment = markOopDesc::biased_lock_alignment; 149 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 150 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 151 : AllocateHeap(aligned_size, flags, CURRENT_PC, 152 AllocFailStrategy::RETURN_NULL); 153 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 154 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 155 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 156 "JavaThread alignment code overflowed allocated storage"); 157 if (TraceBiasedLocking) { 158 if (aligned_addr != real_malloc_addr) { 159 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 160 real_malloc_addr, aligned_addr); 161 } 162 } 163 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 164 return aligned_addr; 165 } else { 166 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 167 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 168 } 169} 170 171void Thread::operator delete(void* p) { 172 if (UseBiasedLocking) { 173 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 174 FreeHeap(real_malloc_addr); 175 } else { 176 FreeHeap(p); 177 } 178} 179 180 181// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 182// JavaThread 183 184 185Thread::Thread() { 186 // stack and get_thread 187 set_stack_base(NULL); 188 set_stack_size(0); 189 set_self_raw_id(0); 190 set_lgrp_id(-1); 191 192 // allocated data structures 193 set_osthread(NULL); 194 set_resource_area(new (mtThread)ResourceArea()); 195 DEBUG_ONLY(_current_resource_mark = NULL;) 196 set_handle_area(new (mtThread) HandleArea(NULL)); 197 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 198 set_active_handles(NULL); 199 set_free_handle_block(NULL); 200 set_last_handle_mark(NULL); 201 202 // This initial value ==> never claimed. 203 _oops_do_parity = 0; 204 205 _metadata_on_stack_buffer = NULL; 206 207 // the handle mark links itself to last_handle_mark 208 new HandleMark(this); 209 210 // plain initialization 211 debug_only(_owned_locks = NULL;) 212 debug_only(_allow_allocation_count = 0;) 213 NOT_PRODUCT(_allow_safepoint_count = 0;) 214 NOT_PRODUCT(_skip_gcalot = false;) 215 _jvmti_env_iteration_count = 0; 216 set_allocated_bytes(0); 217 _vm_operation_started_count = 0; 218 _vm_operation_completed_count = 0; 219 _current_pending_monitor = NULL; 220 _current_pending_monitor_is_from_java = true; 221 _current_waiting_monitor = NULL; 222 _num_nested_signal = 0; 223 omFreeList = NULL; 224 omFreeCount = 0; 225 omFreeProvision = 32; 226 omInUseList = NULL; 227 omInUseCount = 0; 228 229#ifdef ASSERT 230 _visited_for_critical_count = false; 231#endif 232 233 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 234 Monitor::_safepoint_check_sometimes); 235 _suspend_flags = 0; 236 237 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 238 _hashStateX = os::random(); 239 _hashStateY = 842502087; 240 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 241 _hashStateW = 273326509; 242 243 _OnTrap = 0; 244 _schedctl = NULL; 245 _Stalled = 0; 246 _TypeTag = 0x2BAD; 247 248 // Many of the following fields are effectively final - immutable 249 // Note that nascent threads can't use the Native Monitor-Mutex 250 // construct until the _MutexEvent is initialized ... 251 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 252 // we might instead use a stack of ParkEvents that we could provision on-demand. 253 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 254 // and ::Release() 255 _ParkEvent = ParkEvent::Allocate(this); 256 _SleepEvent = ParkEvent::Allocate(this); 257 _MutexEvent = ParkEvent::Allocate(this); 258 _MuxEvent = ParkEvent::Allocate(this); 259 260#ifdef CHECK_UNHANDLED_OOPS 261 if (CheckUnhandledOops) { 262 _unhandled_oops = new UnhandledOops(this); 263 } 264#endif // CHECK_UNHANDLED_OOPS 265#ifdef ASSERT 266 if (UseBiasedLocking) { 267 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 268 assert(this == _real_malloc_address || 269 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 270 "bug in forced alignment of thread objects"); 271 } 272#endif // ASSERT 273} 274 275void Thread::initialize_thread_local_storage() { 276 // Note: Make sure this method only calls 277 // non-blocking operations. Otherwise, it might not work 278 // with the thread-startup/safepoint interaction. 279 280 // During Java thread startup, safepoint code should allow this 281 // method to complete because it may need to allocate memory to 282 // store information for the new thread. 283 284 // initialize structure dependent on thread local storage 285 ThreadLocalStorage::set_thread(this); 286} 287 288void Thread::record_stack_base_and_size() { 289 set_stack_base(os::current_stack_base()); 290 set_stack_size(os::current_stack_size()); 291 if (is_Java_thread()) { 292 ((JavaThread*) this)->set_stack_overflow_limit(); 293 } 294 // CR 7190089: on Solaris, primordial thread's stack is adjusted 295 // in initialize_thread(). Without the adjustment, stack size is 296 // incorrect if stack is set to unlimited (ulimit -s unlimited). 297 // So far, only Solaris has real implementation of initialize_thread(). 298 // 299 // set up any platform-specific state. 300 os::initialize_thread(this); 301 302#if INCLUDE_NMT 303 // record thread's native stack, stack grows downward 304 address stack_low_addr = stack_base() - stack_size(); 305 MemTracker::record_thread_stack(stack_low_addr, stack_size()); 306#endif // INCLUDE_NMT 307} 308 309 310Thread::~Thread() { 311 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 312 ObjectSynchronizer::omFlush(this); 313 314 EVENT_THREAD_DESTRUCT(this); 315 316 // stack_base can be NULL if the thread is never started or exited before 317 // record_stack_base_and_size called. Although, we would like to ensure 318 // that all started threads do call record_stack_base_and_size(), there is 319 // not proper way to enforce that. 320#if INCLUDE_NMT 321 if (_stack_base != NULL) { 322 address low_stack_addr = stack_base() - stack_size(); 323 MemTracker::release_thread_stack(low_stack_addr, stack_size()); 324#ifdef ASSERT 325 set_stack_base(NULL); 326#endif 327 } 328#endif // INCLUDE_NMT 329 330 // deallocate data structures 331 delete resource_area(); 332 // since the handle marks are using the handle area, we have to deallocated the root 333 // handle mark before deallocating the thread's handle area, 334 assert(last_handle_mark() != NULL, "check we have an element"); 335 delete last_handle_mark(); 336 assert(last_handle_mark() == NULL, "check we have reached the end"); 337 338 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 339 // We NULL out the fields for good hygiene. 340 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 341 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 342 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 343 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 344 345 delete handle_area(); 346 delete metadata_handles(); 347 348 // osthread() can be NULL, if creation of thread failed. 349 if (osthread() != NULL) os::free_thread(osthread()); 350 351 delete _SR_lock; 352 353 // clear thread local storage if the Thread is deleting itself 354 if (this == Thread::current()) { 355 ThreadLocalStorage::set_thread(NULL); 356 } else { 357 // In the case where we're not the current thread, invalidate all the 358 // caches in case some code tries to get the current thread or the 359 // thread that was destroyed, and gets stale information. 360 ThreadLocalStorage::invalidate_all(); 361 } 362 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 363} 364 365// NOTE: dummy function for assertion purpose. 366void Thread::run() { 367 ShouldNotReachHere(); 368} 369 370#ifdef ASSERT 371// Private method to check for dangling thread pointer 372void check_for_dangling_thread_pointer(Thread *thread) { 373 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 374 "possibility of dangling Thread pointer"); 375} 376#endif 377 378ThreadPriority Thread::get_priority(const Thread* const thread) { 379 ThreadPriority priority; 380 // Can return an error! 381 (void)os::get_priority(thread, priority); 382 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 383 return priority; 384} 385 386void Thread::set_priority(Thread* thread, ThreadPriority priority) { 387 debug_only(check_for_dangling_thread_pointer(thread);) 388 // Can return an error! 389 (void)os::set_priority(thread, priority); 390} 391 392 393void Thread::start(Thread* thread) { 394 // Start is different from resume in that its safety is guaranteed by context or 395 // being called from a Java method synchronized on the Thread object. 396 if (!DisableStartThread) { 397 if (thread->is_Java_thread()) { 398 // Initialize the thread state to RUNNABLE before starting this thread. 399 // Can not set it after the thread started because we do not know the 400 // exact thread state at that time. It could be in MONITOR_WAIT or 401 // in SLEEPING or some other state. 402 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 403 java_lang_Thread::RUNNABLE); 404 } 405 os::start_thread(thread); 406 } 407} 408 409// Enqueue a VM_Operation to do the job for us - sometime later 410void Thread::send_async_exception(oop java_thread, oop java_throwable) { 411 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 412 VMThread::execute(vm_stop); 413} 414 415 416// Check if an external suspend request has completed (or has been 417// cancelled). Returns true if the thread is externally suspended and 418// false otherwise. 419// 420// The bits parameter returns information about the code path through 421// the routine. Useful for debugging: 422// 423// set in is_ext_suspend_completed(): 424// 0x00000001 - routine was entered 425// 0x00000010 - routine return false at end 426// 0x00000100 - thread exited (return false) 427// 0x00000200 - suspend request cancelled (return false) 428// 0x00000400 - thread suspended (return true) 429// 0x00001000 - thread is in a suspend equivalent state (return true) 430// 0x00002000 - thread is native and walkable (return true) 431// 0x00004000 - thread is native_trans and walkable (needed retry) 432// 433// set in wait_for_ext_suspend_completion(): 434// 0x00010000 - routine was entered 435// 0x00020000 - suspend request cancelled before loop (return false) 436// 0x00040000 - thread suspended before loop (return true) 437// 0x00080000 - suspend request cancelled in loop (return false) 438// 0x00100000 - thread suspended in loop (return true) 439// 0x00200000 - suspend not completed during retry loop (return false) 440 441// Helper class for tracing suspend wait debug bits. 442// 443// 0x00000100 indicates that the target thread exited before it could 444// self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 445// 0x00080000 each indicate a cancelled suspend request so they don't 446// count as wait failures either. 447#define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 448 449class TraceSuspendDebugBits : public StackObj { 450 private: 451 JavaThread * jt; 452 bool is_wait; 453 bool called_by_wait; // meaningful when !is_wait 454 uint32_t * bits; 455 456 public: 457 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 458 uint32_t *_bits) { 459 jt = _jt; 460 is_wait = _is_wait; 461 called_by_wait = _called_by_wait; 462 bits = _bits; 463 } 464 465 ~TraceSuspendDebugBits() { 466 if (!is_wait) { 467#if 1 468 // By default, don't trace bits for is_ext_suspend_completed() calls. 469 // That trace is very chatty. 470 return; 471#else 472 if (!called_by_wait) { 473 // If tracing for is_ext_suspend_completed() is enabled, then only 474 // trace calls to it from wait_for_ext_suspend_completion() 475 return; 476 } 477#endif 478 } 479 480 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 481 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 482 MutexLocker ml(Threads_lock); // needed for get_thread_name() 483 ResourceMark rm; 484 485 tty->print_cr( 486 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 487 jt->get_thread_name(), *bits); 488 489 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 490 } 491 } 492 } 493}; 494#undef DEBUG_FALSE_BITS 495 496 497bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 498 uint32_t *bits) { 499 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 500 501 bool did_trans_retry = false; // only do thread_in_native_trans retry once 502 bool do_trans_retry; // flag to force the retry 503 504 *bits |= 0x00000001; 505 506 do { 507 do_trans_retry = false; 508 509 if (is_exiting()) { 510 // Thread is in the process of exiting. This is always checked 511 // first to reduce the risk of dereferencing a freed JavaThread. 512 *bits |= 0x00000100; 513 return false; 514 } 515 516 if (!is_external_suspend()) { 517 // Suspend request is cancelled. This is always checked before 518 // is_ext_suspended() to reduce the risk of a rogue resume 519 // confusing the thread that made the suspend request. 520 *bits |= 0x00000200; 521 return false; 522 } 523 524 if (is_ext_suspended()) { 525 // thread is suspended 526 *bits |= 0x00000400; 527 return true; 528 } 529 530 // Now that we no longer do hard suspends of threads running 531 // native code, the target thread can be changing thread state 532 // while we are in this routine: 533 // 534 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 535 // 536 // We save a copy of the thread state as observed at this moment 537 // and make our decision about suspend completeness based on the 538 // copy. This closes the race where the thread state is seen as 539 // _thread_in_native_trans in the if-thread_blocked check, but is 540 // seen as _thread_blocked in if-thread_in_native_trans check. 541 JavaThreadState save_state = thread_state(); 542 543 if (save_state == _thread_blocked && is_suspend_equivalent()) { 544 // If the thread's state is _thread_blocked and this blocking 545 // condition is known to be equivalent to a suspend, then we can 546 // consider the thread to be externally suspended. This means that 547 // the code that sets _thread_blocked has been modified to do 548 // self-suspension if the blocking condition releases. We also 549 // used to check for CONDVAR_WAIT here, but that is now covered by 550 // the _thread_blocked with self-suspension check. 551 // 552 // Return true since we wouldn't be here unless there was still an 553 // external suspend request. 554 *bits |= 0x00001000; 555 return true; 556 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 557 // Threads running native code will self-suspend on native==>VM/Java 558 // transitions. If its stack is walkable (should always be the case 559 // unless this function is called before the actual java_suspend() 560 // call), then the wait is done. 561 *bits |= 0x00002000; 562 return true; 563 } else if (!called_by_wait && !did_trans_retry && 564 save_state == _thread_in_native_trans && 565 frame_anchor()->walkable()) { 566 // The thread is transitioning from thread_in_native to another 567 // thread state. check_safepoint_and_suspend_for_native_trans() 568 // will force the thread to self-suspend. If it hasn't gotten 569 // there yet we may have caught the thread in-between the native 570 // code check above and the self-suspend. Lucky us. If we were 571 // called by wait_for_ext_suspend_completion(), then it 572 // will be doing the retries so we don't have to. 573 // 574 // Since we use the saved thread state in the if-statement above, 575 // there is a chance that the thread has already transitioned to 576 // _thread_blocked by the time we get here. In that case, we will 577 // make a single unnecessary pass through the logic below. This 578 // doesn't hurt anything since we still do the trans retry. 579 580 *bits |= 0x00004000; 581 582 // Once the thread leaves thread_in_native_trans for another 583 // thread state, we break out of this retry loop. We shouldn't 584 // need this flag to prevent us from getting back here, but 585 // sometimes paranoia is good. 586 did_trans_retry = true; 587 588 // We wait for the thread to transition to a more usable state. 589 for (int i = 1; i <= SuspendRetryCount; i++) { 590 // We used to do an "os::yield_all(i)" call here with the intention 591 // that yielding would increase on each retry. However, the parameter 592 // is ignored on Linux which means the yield didn't scale up. Waiting 593 // on the SR_lock below provides a much more predictable scale up for 594 // the delay. It also provides a simple/direct point to check for any 595 // safepoint requests from the VMThread 596 597 // temporarily drops SR_lock while doing wait with safepoint check 598 // (if we're a JavaThread - the WatcherThread can also call this) 599 // and increase delay with each retry 600 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 601 602 // check the actual thread state instead of what we saved above 603 if (thread_state() != _thread_in_native_trans) { 604 // the thread has transitioned to another thread state so 605 // try all the checks (except this one) one more time. 606 do_trans_retry = true; 607 break; 608 } 609 } // end retry loop 610 611 612 } 613 } while (do_trans_retry); 614 615 *bits |= 0x00000010; 616 return false; 617} 618 619// Wait for an external suspend request to complete (or be cancelled). 620// Returns true if the thread is externally suspended and false otherwise. 621// 622bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 623 uint32_t *bits) { 624 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 625 false /* !called_by_wait */, bits); 626 627 // local flag copies to minimize SR_lock hold time 628 bool is_suspended; 629 bool pending; 630 uint32_t reset_bits; 631 632 // set a marker so is_ext_suspend_completed() knows we are the caller 633 *bits |= 0x00010000; 634 635 // We use reset_bits to reinitialize the bits value at the top of 636 // each retry loop. This allows the caller to make use of any 637 // unused bits for their own marking purposes. 638 reset_bits = *bits; 639 640 { 641 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 642 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 643 delay, bits); 644 pending = is_external_suspend(); 645 } 646 // must release SR_lock to allow suspension to complete 647 648 if (!pending) { 649 // A cancelled suspend request is the only false return from 650 // is_ext_suspend_completed() that keeps us from entering the 651 // retry loop. 652 *bits |= 0x00020000; 653 return false; 654 } 655 656 if (is_suspended) { 657 *bits |= 0x00040000; 658 return true; 659 } 660 661 for (int i = 1; i <= retries; i++) { 662 *bits = reset_bits; // reinit to only track last retry 663 664 // We used to do an "os::yield_all(i)" call here with the intention 665 // that yielding would increase on each retry. However, the parameter 666 // is ignored on Linux which means the yield didn't scale up. Waiting 667 // on the SR_lock below provides a much more predictable scale up for 668 // the delay. It also provides a simple/direct point to check for any 669 // safepoint requests from the VMThread 670 671 { 672 MutexLocker ml(SR_lock()); 673 // wait with safepoint check (if we're a JavaThread - the WatcherThread 674 // can also call this) and increase delay with each retry 675 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 676 677 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 678 delay, bits); 679 680 // It is possible for the external suspend request to be cancelled 681 // (by a resume) before the actual suspend operation is completed. 682 // Refresh our local copy to see if we still need to wait. 683 pending = is_external_suspend(); 684 } 685 686 if (!pending) { 687 // A cancelled suspend request is the only false return from 688 // is_ext_suspend_completed() that keeps us from staying in the 689 // retry loop. 690 *bits |= 0x00080000; 691 return false; 692 } 693 694 if (is_suspended) { 695 *bits |= 0x00100000; 696 return true; 697 } 698 } // end retry loop 699 700 // thread did not suspend after all our retries 701 *bits |= 0x00200000; 702 return false; 703} 704 705#ifndef PRODUCT 706void JavaThread::record_jump(address target, address instr, const char* file, 707 int line) { 708 709 // This should not need to be atomic as the only way for simultaneous 710 // updates is via interrupts. Even then this should be rare or non-existent 711 // and we don't care that much anyway. 712 713 int index = _jmp_ring_index; 714 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 715 _jmp_ring[index]._target = (intptr_t) target; 716 _jmp_ring[index]._instruction = (intptr_t) instr; 717 _jmp_ring[index]._file = file; 718 _jmp_ring[index]._line = line; 719} 720#endif // PRODUCT 721 722// Called by flat profiler 723// Callers have already called wait_for_ext_suspend_completion 724// The assertion for that is currently too complex to put here: 725bool JavaThread::profile_last_Java_frame(frame* _fr) { 726 bool gotframe = false; 727 // self suspension saves needed state. 728 if (has_last_Java_frame() && _anchor.walkable()) { 729 *_fr = pd_last_frame(); 730 gotframe = true; 731 } 732 return gotframe; 733} 734 735void Thread::interrupt(Thread* thread) { 736 debug_only(check_for_dangling_thread_pointer(thread);) 737 os::interrupt(thread); 738} 739 740bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 741 debug_only(check_for_dangling_thread_pointer(thread);) 742 // Note: If clear_interrupted==false, this simply fetches and 743 // returns the value of the field osthread()->interrupted(). 744 return os::is_interrupted(thread, clear_interrupted); 745} 746 747 748// GC Support 749bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 750 jint thread_parity = _oops_do_parity; 751 if (thread_parity != strong_roots_parity) { 752 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 753 if (res == thread_parity) { 754 return true; 755 } else { 756 guarantee(res == strong_roots_parity, "Or else what?"); 757 assert(SharedHeap::heap()->workers()->active_workers() > 0, 758 "Should only fail when parallel."); 759 return false; 760 } 761 } 762 assert(SharedHeap::heap()->workers()->active_workers() > 0, 763 "Should only fail when parallel."); 764 return false; 765} 766 767void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 768 active_handles()->oops_do(f); 769 // Do oop for ThreadShadow 770 f->do_oop((oop*)&_pending_exception); 771 handle_area()->oops_do(f); 772} 773 774void Thread::nmethods_do(CodeBlobClosure* cf) { 775 // no nmethods in a generic thread... 776} 777 778void Thread::metadata_do(void f(Metadata*)) { 779 if (metadata_handles() != NULL) { 780 for (int i = 0; i< metadata_handles()->length(); i++) { 781 f(metadata_handles()->at(i)); 782 } 783 } 784} 785 786void Thread::print_on(outputStream* st) const { 787 // get_priority assumes osthread initialized 788 if (osthread() != NULL) { 789 int os_prio; 790 if (os::get_native_priority(this, &os_prio) == OS_OK) { 791 st->print("os_prio=%d ", os_prio); 792 } 793 st->print("tid=" INTPTR_FORMAT " ", this); 794 ext().print_on(st); 795 osthread()->print_on(st); 796 } 797 debug_only(if (WizardMode) print_owned_locks_on(st);) 798} 799 800// Thread::print_on_error() is called by fatal error handler. Don't use 801// any lock or allocate memory. 802void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 803 if (is_VM_thread()) st->print("VMThread"); 804 else if (is_Compiler_thread()) st->print("CompilerThread"); 805 else if (is_Java_thread()) st->print("JavaThread"); 806 else if (is_GC_task_thread()) st->print("GCTaskThread"); 807 else if (is_Watcher_thread()) st->print("WatcherThread"); 808 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 809 else st->print("Thread"); 810 811 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 812 _stack_base - _stack_size, _stack_base); 813 814 if (osthread()) { 815 st->print(" [id=%d]", osthread()->thread_id()); 816 } 817} 818 819#ifdef ASSERT 820void Thread::print_owned_locks_on(outputStream* st) const { 821 Monitor *cur = _owned_locks; 822 if (cur == NULL) { 823 st->print(" (no locks) "); 824 } else { 825 st->print_cr(" Locks owned:"); 826 while (cur) { 827 cur->print_on(st); 828 cur = cur->next(); 829 } 830 } 831} 832 833static int ref_use_count = 0; 834 835bool Thread::owns_locks_but_compiled_lock() const { 836 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 837 if (cur != Compile_lock) return true; 838 } 839 return false; 840} 841 842 843#endif 844 845#ifndef PRODUCT 846 847// The flag: potential_vm_operation notifies if this particular safepoint state could potential 848// invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 849// no threads which allow_vm_block's are held 850void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 851 // Check if current thread is allowed to block at a safepoint 852 if (!(_allow_safepoint_count == 0)) { 853 fatal("Possible safepoint reached by thread that does not allow it"); 854 } 855 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 856 fatal("LEAF method calling lock?"); 857 } 858 859#ifdef ASSERT 860 if (potential_vm_operation && is_Java_thread() 861 && !Universe::is_bootstrapping()) { 862 // Make sure we do not hold any locks that the VM thread also uses. 863 // This could potentially lead to deadlocks 864 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 865 // Threads_lock is special, since the safepoint synchronization will not start before this is 866 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 867 // since it is used to transfer control between JavaThreads and the VMThread 868 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 869 if ((cur->allow_vm_block() && 870 cur != Threads_lock && 871 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 872 cur != VMOperationRequest_lock && 873 cur != VMOperationQueue_lock) || 874 cur->rank() == Mutex::special) { 875 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name())); 876 } 877 } 878 } 879 880 if (GCALotAtAllSafepoints) { 881 // We could enter a safepoint here and thus have a gc 882 InterfaceSupport::check_gc_alot(); 883 } 884#endif 885} 886#endif 887 888bool Thread::is_in_stack(address adr) const { 889 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 890 address end = os::current_stack_pointer(); 891 // Allow non Java threads to call this without stack_base 892 if (_stack_base == NULL) return true; 893 if (stack_base() >= adr && adr >= end) return true; 894 895 return false; 896} 897 898 899bool Thread::is_in_usable_stack(address adr) const { 900 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0; 901 size_t usable_stack_size = _stack_size - stack_guard_size; 902 903 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 904} 905 906 907// We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 908// However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 909// used for compilation in the future. If that change is made, the need for these methods 910// should be revisited, and they should be removed if possible. 911 912bool Thread::is_lock_owned(address adr) const { 913 return on_local_stack(adr); 914} 915 916bool Thread::set_as_starting_thread() { 917 // NOTE: this must be called inside the main thread. 918 return os::create_main_thread((JavaThread*)this); 919} 920 921static void initialize_class(Symbol* class_name, TRAPS) { 922 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 923 InstanceKlass::cast(klass)->initialize(CHECK); 924} 925 926 927// Creates the initial ThreadGroup 928static Handle create_initial_thread_group(TRAPS) { 929 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 930 instanceKlassHandle klass (THREAD, k); 931 932 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 933 { 934 JavaValue result(T_VOID); 935 JavaCalls::call_special(&result, 936 system_instance, 937 klass, 938 vmSymbols::object_initializer_name(), 939 vmSymbols::void_method_signature(), 940 CHECK_NH); 941 } 942 Universe::set_system_thread_group(system_instance()); 943 944 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 945 { 946 JavaValue result(T_VOID); 947 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 948 JavaCalls::call_special(&result, 949 main_instance, 950 klass, 951 vmSymbols::object_initializer_name(), 952 vmSymbols::threadgroup_string_void_signature(), 953 system_instance, 954 string, 955 CHECK_NH); 956 } 957 return main_instance; 958} 959 960// Creates the initial Thread 961static oop create_initial_thread(Handle thread_group, JavaThread* thread, 962 TRAPS) { 963 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 964 instanceKlassHandle klass (THREAD, k); 965 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 966 967 java_lang_Thread::set_thread(thread_oop(), thread); 968 java_lang_Thread::set_priority(thread_oop(), NormPriority); 969 thread->set_threadObj(thread_oop()); 970 971 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 972 973 JavaValue result(T_VOID); 974 JavaCalls::call_special(&result, thread_oop, 975 klass, 976 vmSymbols::object_initializer_name(), 977 vmSymbols::threadgroup_string_void_signature(), 978 thread_group, 979 string, 980 CHECK_NULL); 981 return thread_oop(); 982} 983 984static void call_initializeSystemClass(TRAPS) { 985 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 986 instanceKlassHandle klass (THREAD, k); 987 988 JavaValue result(T_VOID); 989 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 990 vmSymbols::void_method_signature(), CHECK); 991} 992 993char java_runtime_name[128] = ""; 994char java_runtime_version[128] = ""; 995 996// extract the JRE name from sun.misc.Version.java_runtime_name 997static const char* get_java_runtime_name(TRAPS) { 998 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 999 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1000 fieldDescriptor fd; 1001 bool found = k != NULL && 1002 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1003 vmSymbols::string_signature(), &fd); 1004 if (found) { 1005 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1006 if (name_oop == NULL) { 1007 return NULL; 1008 } 1009 const char* name = java_lang_String::as_utf8_string(name_oop, 1010 java_runtime_name, 1011 sizeof(java_runtime_name)); 1012 return name; 1013 } else { 1014 return NULL; 1015 } 1016} 1017 1018// extract the JRE version from sun.misc.Version.java_runtime_version 1019static const char* get_java_runtime_version(TRAPS) { 1020 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), 1021 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1022 fieldDescriptor fd; 1023 bool found = k != NULL && 1024 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1025 vmSymbols::string_signature(), &fd); 1026 if (found) { 1027 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1028 if (name_oop == NULL) { 1029 return NULL; 1030 } 1031 const char* name = java_lang_String::as_utf8_string(name_oop, 1032 java_runtime_version, 1033 sizeof(java_runtime_version)); 1034 return name; 1035 } else { 1036 return NULL; 1037 } 1038} 1039 1040// General purpose hook into Java code, run once when the VM is initialized. 1041// The Java library method itself may be changed independently from the VM. 1042static void call_postVMInitHook(TRAPS) { 1043 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1044 instanceKlassHandle klass (THREAD, k); 1045 if (klass.not_null()) { 1046 JavaValue result(T_VOID); 1047 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1048 vmSymbols::void_method_signature(), 1049 CHECK); 1050 } 1051} 1052 1053static void reset_vm_info_property(TRAPS) { 1054 // the vm info string 1055 ResourceMark rm(THREAD); 1056 const char *vm_info = VM_Version::vm_info_string(); 1057 1058 // java.lang.System class 1059 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1060 instanceKlassHandle klass (THREAD, k); 1061 1062 // setProperty arguments 1063 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1064 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1065 1066 // return value 1067 JavaValue r(T_OBJECT); 1068 1069 // public static String setProperty(String key, String value); 1070 JavaCalls::call_static(&r, 1071 klass, 1072 vmSymbols::setProperty_name(), 1073 vmSymbols::string_string_string_signature(), 1074 key_str, 1075 value_str, 1076 CHECK); 1077} 1078 1079 1080void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1081 bool daemon, TRAPS) { 1082 assert(thread_group.not_null(), "thread group should be specified"); 1083 assert(threadObj() == NULL, "should only create Java thread object once"); 1084 1085 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1086 instanceKlassHandle klass (THREAD, k); 1087 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1088 1089 java_lang_Thread::set_thread(thread_oop(), this); 1090 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1091 set_threadObj(thread_oop()); 1092 1093 JavaValue result(T_VOID); 1094 if (thread_name != NULL) { 1095 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1096 // Thread gets assigned specified name and null target 1097 JavaCalls::call_special(&result, 1098 thread_oop, 1099 klass, 1100 vmSymbols::object_initializer_name(), 1101 vmSymbols::threadgroup_string_void_signature(), 1102 thread_group, // Argument 1 1103 name, // Argument 2 1104 THREAD); 1105 } else { 1106 // Thread gets assigned name "Thread-nnn" and null target 1107 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1108 JavaCalls::call_special(&result, 1109 thread_oop, 1110 klass, 1111 vmSymbols::object_initializer_name(), 1112 vmSymbols::threadgroup_runnable_void_signature(), 1113 thread_group, // Argument 1 1114 Handle(), // Argument 2 1115 THREAD); 1116 } 1117 1118 1119 if (daemon) { 1120 java_lang_Thread::set_daemon(thread_oop()); 1121 } 1122 1123 if (HAS_PENDING_EXCEPTION) { 1124 return; 1125 } 1126 1127 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass()); 1128 Handle threadObj(THREAD, this->threadObj()); 1129 1130 JavaCalls::call_special(&result, 1131 thread_group, 1132 group, 1133 vmSymbols::add_method_name(), 1134 vmSymbols::thread_void_signature(), 1135 threadObj, // Arg 1 1136 THREAD); 1137} 1138 1139// NamedThread -- non-JavaThread subclasses with multiple 1140// uniquely named instances should derive from this. 1141NamedThread::NamedThread() : Thread() { 1142 _name = NULL; 1143 _processed_thread = NULL; 1144} 1145 1146NamedThread::~NamedThread() { 1147 if (_name != NULL) { 1148 FREE_C_HEAP_ARRAY(char, _name); 1149 _name = NULL; 1150 } 1151} 1152 1153void NamedThread::set_name(const char* format, ...) { 1154 guarantee(_name == NULL, "Only get to set name once."); 1155 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1156 guarantee(_name != NULL, "alloc failure"); 1157 va_list ap; 1158 va_start(ap, format); 1159 jio_vsnprintf(_name, max_name_len, format, ap); 1160 va_end(ap); 1161} 1162 1163void NamedThread::print_on(outputStream* st) const { 1164 st->print("\"%s\" ", name()); 1165 Thread::print_on(st); 1166 st->cr(); 1167} 1168 1169 1170// ======= WatcherThread ======== 1171 1172// The watcher thread exists to simulate timer interrupts. It should 1173// be replaced by an abstraction over whatever native support for 1174// timer interrupts exists on the platform. 1175 1176WatcherThread* WatcherThread::_watcher_thread = NULL; 1177bool WatcherThread::_startable = false; 1178volatile bool WatcherThread::_should_terminate = false; 1179 1180WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1181 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1182 if (os::create_thread(this, os::watcher_thread)) { 1183 _watcher_thread = this; 1184 1185 // Set the watcher thread to the highest OS priority which should not be 1186 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1187 // is created. The only normal thread using this priority is the reference 1188 // handler thread, which runs for very short intervals only. 1189 // If the VMThread's priority is not lower than the WatcherThread profiling 1190 // will be inaccurate. 1191 os::set_priority(this, MaxPriority); 1192 if (!DisableStartThread) { 1193 os::start_thread(this); 1194 } 1195 } 1196} 1197 1198int WatcherThread::sleep() const { 1199 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1200 1201 // remaining will be zero if there are no tasks, 1202 // causing the WatcherThread to sleep until a task is 1203 // enrolled 1204 int remaining = PeriodicTask::time_to_wait(); 1205 int time_slept = 0; 1206 1207 // we expect this to timeout - we only ever get unparked when 1208 // we should terminate or when a new task has been enrolled 1209 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1210 1211 jlong time_before_loop = os::javaTimeNanos(); 1212 1213 for (;;) { 1214 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining); 1215 jlong now = os::javaTimeNanos(); 1216 1217 if (remaining == 0) { 1218 // if we didn't have any tasks we could have waited for a long time 1219 // consider the time_slept zero and reset time_before_loop 1220 time_slept = 0; 1221 time_before_loop = now; 1222 } else { 1223 // need to recalculate since we might have new tasks in _tasks 1224 time_slept = (int) ((now - time_before_loop) / 1000000); 1225 } 1226 1227 // Change to task list or spurious wakeup of some kind 1228 if (timedout || _should_terminate) { 1229 break; 1230 } 1231 1232 remaining = PeriodicTask::time_to_wait(); 1233 if (remaining == 0) { 1234 // Last task was just disenrolled so loop around and wait until 1235 // another task gets enrolled 1236 continue; 1237 } 1238 1239 remaining -= time_slept; 1240 if (remaining <= 0) { 1241 break; 1242 } 1243 } 1244 1245 return time_slept; 1246} 1247 1248void WatcherThread::run() { 1249 assert(this == watcher_thread(), "just checking"); 1250 1251 this->record_stack_base_and_size(); 1252 this->initialize_thread_local_storage(); 1253 this->set_native_thread_name(this->name()); 1254 this->set_active_handles(JNIHandleBlock::allocate_block()); 1255 while (!_should_terminate) { 1256 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1257 assert(watcher_thread() == this, "thread consistency check"); 1258 1259 // Calculate how long it'll be until the next PeriodicTask work 1260 // should be done, and sleep that amount of time. 1261 int time_waited = sleep(); 1262 1263 if (is_error_reported()) { 1264 // A fatal error has happened, the error handler(VMError::report_and_die) 1265 // should abort JVM after creating an error log file. However in some 1266 // rare cases, the error handler itself might deadlock. Here we try to 1267 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1268 // 1269 // This code is in WatcherThread because WatcherThread wakes up 1270 // periodically so the fatal error handler doesn't need to do anything; 1271 // also because the WatcherThread is less likely to crash than other 1272 // threads. 1273 1274 for (;;) { 1275 if (!ShowMessageBoxOnError 1276 && (OnError == NULL || OnError[0] == '\0') 1277 && Arguments::abort_hook() == NULL) { 1278 os::sleep(this, 2 * 60 * 1000, false); 1279 fdStream err(defaultStream::output_fd()); 1280 err.print_raw_cr("# [ timer expired, abort... ]"); 1281 // skip atexit/vm_exit/vm_abort hooks 1282 os::die(); 1283 } 1284 1285 // Wake up 5 seconds later, the fatal handler may reset OnError or 1286 // ShowMessageBoxOnError when it is ready to abort. 1287 os::sleep(this, 5 * 1000, false); 1288 } 1289 } 1290 1291 PeriodicTask::real_time_tick(time_waited); 1292 } 1293 1294 // Signal that it is terminated 1295 { 1296 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1297 _watcher_thread = NULL; 1298 Terminator_lock->notify(); 1299 } 1300 1301 // Thread destructor usually does this.. 1302 ThreadLocalStorage::set_thread(NULL); 1303} 1304 1305void WatcherThread::start() { 1306 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1307 1308 if (watcher_thread() == NULL && _startable) { 1309 _should_terminate = false; 1310 // Create the single instance of WatcherThread 1311 new WatcherThread(); 1312 } 1313} 1314 1315void WatcherThread::make_startable() { 1316 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1317 _startable = true; 1318} 1319 1320void WatcherThread::stop() { 1321 // Get the PeriodicTask_lock if we can. If we cannot, then the 1322 // WatcherThread is using it and we don't want to block on that lock 1323 // here because that might cause a safepoint deadlock depending on 1324 // what the current WatcherThread tasks are doing. 1325 bool have_lock = PeriodicTask_lock->try_lock(); 1326 1327 _should_terminate = true; 1328 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1329 1330 if (have_lock) { 1331 WatcherThread* watcher = watcher_thread(); 1332 if (watcher != NULL) { 1333 // If we managed to get the lock, then we should unpark the 1334 // WatcherThread so that it can see we want it to stop. 1335 watcher->unpark(); 1336 } 1337 1338 PeriodicTask_lock->unlock(); 1339 } 1340 1341 // it is ok to take late safepoints here, if needed 1342 MutexLocker mu(Terminator_lock); 1343 1344 while (watcher_thread() != NULL) { 1345 // This wait should make safepoint checks, wait without a timeout, 1346 // and wait as a suspend-equivalent condition. 1347 // 1348 // Note: If the FlatProfiler is running, then this thread is waiting 1349 // for the WatcherThread to terminate and the WatcherThread, via the 1350 // FlatProfiler task, is waiting for the external suspend request on 1351 // this thread to complete. wait_for_ext_suspend_completion() will 1352 // eventually timeout, but that takes time. Making this wait a 1353 // suspend-equivalent condition solves that timeout problem. 1354 // 1355 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1356 Mutex::_as_suspend_equivalent_flag); 1357 } 1358} 1359 1360void WatcherThread::unpark() { 1361 MutexLockerEx ml(PeriodicTask_lock->owned_by_self() 1362 ? NULL 1363 : PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1364 PeriodicTask_lock->notify(); 1365} 1366 1367void WatcherThread::print_on(outputStream* st) const { 1368 st->print("\"%s\" ", name()); 1369 Thread::print_on(st); 1370 st->cr(); 1371} 1372 1373// ======= JavaThread ======== 1374 1375// A JavaThread is a normal Java thread 1376 1377void JavaThread::initialize() { 1378 // Initialize fields 1379 1380 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids) 1381 set_claimed_par_id(UINT_MAX); 1382 1383 set_saved_exception_pc(NULL); 1384 set_threadObj(NULL); 1385 _anchor.clear(); 1386 set_entry_point(NULL); 1387 set_jni_functions(jni_functions()); 1388 set_callee_target(NULL); 1389 set_vm_result(NULL); 1390 set_vm_result_2(NULL); 1391 set_vframe_array_head(NULL); 1392 set_vframe_array_last(NULL); 1393 set_deferred_locals(NULL); 1394 set_deopt_mark(NULL); 1395 set_deopt_nmethod(NULL); 1396 clear_must_deopt_id(); 1397 set_monitor_chunks(NULL); 1398 set_next(NULL); 1399 set_thread_state(_thread_new); 1400 _terminated = _not_terminated; 1401 _privileged_stack_top = NULL; 1402 _array_for_gc = NULL; 1403 _suspend_equivalent = false; 1404 _in_deopt_handler = 0; 1405 _doing_unsafe_access = false; 1406 _stack_guard_state = stack_guard_unused; 1407 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1408 _exception_pc = 0; 1409 _exception_handler_pc = 0; 1410 _is_method_handle_return = 0; 1411 _jvmti_thread_state= NULL; 1412 _should_post_on_exceptions_flag = JNI_FALSE; 1413 _jvmti_get_loaded_classes_closure = NULL; 1414 _interp_only_mode = 0; 1415 _special_runtime_exit_condition = _no_async_condition; 1416 _pending_async_exception = NULL; 1417 _thread_stat = NULL; 1418 _thread_stat = new ThreadStatistics(); 1419 _blocked_on_compilation = false; 1420 _jni_active_critical = 0; 1421 _pending_jni_exception_check_fn = NULL; 1422 _do_not_unlock_if_synchronized = false; 1423 _cached_monitor_info = NULL; 1424 _parker = Parker::Allocate(this); 1425 1426#ifndef PRODUCT 1427 _jmp_ring_index = 0; 1428 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1429 record_jump(NULL, NULL, NULL, 0); 1430 } 1431#endif // PRODUCT 1432 1433 set_thread_profiler(NULL); 1434 if (FlatProfiler::is_active()) { 1435 // This is where we would decide to either give each thread it's own profiler 1436 // or use one global one from FlatProfiler, 1437 // or up to some count of the number of profiled threads, etc. 1438 ThreadProfiler* pp = new ThreadProfiler(); 1439 pp->engage(); 1440 set_thread_profiler(pp); 1441 } 1442 1443 // Setup safepoint state info for this thread 1444 ThreadSafepointState::create(this); 1445 1446 debug_only(_java_call_counter = 0); 1447 1448 // JVMTI PopFrame support 1449 _popframe_condition = popframe_inactive; 1450 _popframe_preserved_args = NULL; 1451 _popframe_preserved_args_size = 0; 1452 1453 pd_initialize(); 1454} 1455 1456#if INCLUDE_ALL_GCS 1457SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1458DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1459#endif // INCLUDE_ALL_GCS 1460 1461JavaThread::JavaThread(bool is_attaching_via_jni) : 1462 Thread() 1463#if INCLUDE_ALL_GCS 1464 , _satb_mark_queue(&_satb_mark_queue_set), 1465 _dirty_card_queue(&_dirty_card_queue_set) 1466#endif // INCLUDE_ALL_GCS 1467{ 1468 initialize(); 1469 if (is_attaching_via_jni) { 1470 _jni_attach_state = _attaching_via_jni; 1471 } else { 1472 _jni_attach_state = _not_attaching_via_jni; 1473 } 1474 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1475} 1476 1477bool JavaThread::reguard_stack(address cur_sp) { 1478 if (_stack_guard_state != stack_guard_yellow_disabled) { 1479 return true; // Stack already guarded or guard pages not needed. 1480 } 1481 1482 if (register_stack_overflow()) { 1483 // For those architectures which have separate register and 1484 // memory stacks, we must check the register stack to see if 1485 // it has overflowed. 1486 return false; 1487 } 1488 1489 // Java code never executes within the yellow zone: the latter is only 1490 // there to provoke an exception during stack banging. If java code 1491 // is executing there, either StackShadowPages should be larger, or 1492 // some exception code in c1, c2 or the interpreter isn't unwinding 1493 // when it should. 1494 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1495 1496 enable_stack_yellow_zone(); 1497 return true; 1498} 1499 1500bool JavaThread::reguard_stack(void) { 1501 return reguard_stack(os::current_stack_pointer()); 1502} 1503 1504 1505void JavaThread::block_if_vm_exited() { 1506 if (_terminated == _vm_exited) { 1507 // _vm_exited is set at safepoint, and Threads_lock is never released 1508 // we will block here forever 1509 Threads_lock->lock_without_safepoint_check(); 1510 ShouldNotReachHere(); 1511 } 1512} 1513 1514 1515// Remove this ifdef when C1 is ported to the compiler interface. 1516static void compiler_thread_entry(JavaThread* thread, TRAPS); 1517static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1518 1519JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1520 Thread() 1521#if INCLUDE_ALL_GCS 1522 , _satb_mark_queue(&_satb_mark_queue_set), 1523 _dirty_card_queue(&_dirty_card_queue_set) 1524#endif // INCLUDE_ALL_GCS 1525{ 1526 initialize(); 1527 _jni_attach_state = _not_attaching_via_jni; 1528 set_entry_point(entry_point); 1529 // Create the native thread itself. 1530 // %note runtime_23 1531 os::ThreadType thr_type = os::java_thread; 1532 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1533 os::java_thread; 1534 os::create_thread(this, thr_type, stack_sz); 1535 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1536 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1537 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1538 // the exception consists of creating the exception object & initializing it, initialization 1539 // will leave the VM via a JavaCall and then all locks must be unlocked). 1540 // 1541 // The thread is still suspended when we reach here. Thread must be explicit started 1542 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1543 // by calling Threads:add. The reason why this is not done here, is because the thread 1544 // object must be fully initialized (take a look at JVM_Start) 1545} 1546 1547JavaThread::~JavaThread() { 1548 1549 // JSR166 -- return the parker to the free list 1550 Parker::Release(_parker); 1551 _parker = NULL; 1552 1553 // Free any remaining previous UnrollBlock 1554 vframeArray* old_array = vframe_array_last(); 1555 1556 if (old_array != NULL) { 1557 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1558 old_array->set_unroll_block(NULL); 1559 delete old_info; 1560 delete old_array; 1561 } 1562 1563 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1564 if (deferred != NULL) { 1565 // This can only happen if thread is destroyed before deoptimization occurs. 1566 assert(deferred->length() != 0, "empty array!"); 1567 do { 1568 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1569 deferred->remove_at(0); 1570 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1571 delete dlv; 1572 } while (deferred->length() != 0); 1573 delete deferred; 1574 } 1575 1576 // All Java related clean up happens in exit 1577 ThreadSafepointState::destroy(this); 1578 if (_thread_profiler != NULL) delete _thread_profiler; 1579 if (_thread_stat != NULL) delete _thread_stat; 1580} 1581 1582 1583// The first routine called by a new Java thread 1584void JavaThread::run() { 1585 // initialize thread-local alloc buffer related fields 1586 this->initialize_tlab(); 1587 1588 // used to test validity of stack trace backs 1589 this->record_base_of_stack_pointer(); 1590 1591 // Record real stack base and size. 1592 this->record_stack_base_and_size(); 1593 1594 // Initialize thread local storage; set before calling MutexLocker 1595 this->initialize_thread_local_storage(); 1596 1597 this->create_stack_guard_pages(); 1598 1599 this->cache_global_variables(); 1600 1601 // Thread is now sufficient initialized to be handled by the safepoint code as being 1602 // in the VM. Change thread state from _thread_new to _thread_in_vm 1603 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1604 1605 assert(JavaThread::current() == this, "sanity check"); 1606 assert(!Thread::current()->owns_locks(), "sanity check"); 1607 1608 DTRACE_THREAD_PROBE(start, this); 1609 1610 // This operation might block. We call that after all safepoint checks for a new thread has 1611 // been completed. 1612 this->set_active_handles(JNIHandleBlock::allocate_block()); 1613 1614 if (JvmtiExport::should_post_thread_life()) { 1615 JvmtiExport::post_thread_start(this); 1616 } 1617 1618 EventThreadStart event; 1619 if (event.should_commit()) { 1620 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1621 event.commit(); 1622 } 1623 1624 // We call another function to do the rest so we are sure that the stack addresses used 1625 // from there will be lower than the stack base just computed 1626 thread_main_inner(); 1627 1628 // Note, thread is no longer valid at this point! 1629} 1630 1631 1632void JavaThread::thread_main_inner() { 1633 assert(JavaThread::current() == this, "sanity check"); 1634 assert(this->threadObj() != NULL, "just checking"); 1635 1636 // Execute thread entry point unless this thread has a pending exception 1637 // or has been stopped before starting. 1638 // Note: Due to JVM_StopThread we can have pending exceptions already! 1639 if (!this->has_pending_exception() && 1640 !java_lang_Thread::is_stillborn(this->threadObj())) { 1641 { 1642 ResourceMark rm(this); 1643 this->set_native_thread_name(this->get_thread_name()); 1644 } 1645 HandleMark hm(this); 1646 this->entry_point()(this, this); 1647 } 1648 1649 DTRACE_THREAD_PROBE(stop, this); 1650 1651 this->exit(false); 1652 delete this; 1653} 1654 1655 1656static void ensure_join(JavaThread* thread) { 1657 // We do not need to grap the Threads_lock, since we are operating on ourself. 1658 Handle threadObj(thread, thread->threadObj()); 1659 assert(threadObj.not_null(), "java thread object must exist"); 1660 ObjectLocker lock(threadObj, thread); 1661 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1662 thread->clear_pending_exception(); 1663 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1664 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1665 // Clear the native thread instance - this makes isAlive return false and allows the join() 1666 // to complete once we've done the notify_all below 1667 java_lang_Thread::set_thread(threadObj(), NULL); 1668 lock.notify_all(thread); 1669 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1670 thread->clear_pending_exception(); 1671} 1672 1673 1674// For any new cleanup additions, please check to see if they need to be applied to 1675// cleanup_failed_attach_current_thread as well. 1676void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1677 assert(this == JavaThread::current(), "thread consistency check"); 1678 1679 HandleMark hm(this); 1680 Handle uncaught_exception(this, this->pending_exception()); 1681 this->clear_pending_exception(); 1682 Handle threadObj(this, this->threadObj()); 1683 assert(threadObj.not_null(), "Java thread object should be created"); 1684 1685 if (get_thread_profiler() != NULL) { 1686 get_thread_profiler()->disengage(); 1687 ResourceMark rm; 1688 get_thread_profiler()->print(get_thread_name()); 1689 } 1690 1691 1692 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1693 { 1694 EXCEPTION_MARK; 1695 1696 CLEAR_PENDING_EXCEPTION; 1697 } 1698 if (!destroy_vm) { 1699 if (uncaught_exception.not_null()) { 1700 EXCEPTION_MARK; 1701 // Call method Thread.dispatchUncaughtException(). 1702 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1703 JavaValue result(T_VOID); 1704 JavaCalls::call_virtual(&result, 1705 threadObj, thread_klass, 1706 vmSymbols::dispatchUncaughtException_name(), 1707 vmSymbols::throwable_void_signature(), 1708 uncaught_exception, 1709 THREAD); 1710 if (HAS_PENDING_EXCEPTION) { 1711 ResourceMark rm(this); 1712 jio_fprintf(defaultStream::error_stream(), 1713 "\nException: %s thrown from the UncaughtExceptionHandler" 1714 " in thread \"%s\"\n", 1715 pending_exception()->klass()->external_name(), 1716 get_thread_name()); 1717 CLEAR_PENDING_EXCEPTION; 1718 } 1719 } 1720 1721 // Called before the java thread exit since we want to read info 1722 // from java_lang_Thread object 1723 EventThreadEnd event; 1724 if (event.should_commit()) { 1725 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); 1726 event.commit(); 1727 } 1728 1729 // Call after last event on thread 1730 EVENT_THREAD_EXIT(this); 1731 1732 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1733 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1734 // is deprecated anyhow. 1735 if (!is_Compiler_thread()) { 1736 int count = 3; 1737 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1738 EXCEPTION_MARK; 1739 JavaValue result(T_VOID); 1740 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1741 JavaCalls::call_virtual(&result, 1742 threadObj, thread_klass, 1743 vmSymbols::exit_method_name(), 1744 vmSymbols::void_method_signature(), 1745 THREAD); 1746 CLEAR_PENDING_EXCEPTION; 1747 } 1748 } 1749 // notify JVMTI 1750 if (JvmtiExport::should_post_thread_life()) { 1751 JvmtiExport::post_thread_end(this); 1752 } 1753 1754 // We have notified the agents that we are exiting, before we go on, 1755 // we must check for a pending external suspend request and honor it 1756 // in order to not surprise the thread that made the suspend request. 1757 while (true) { 1758 { 1759 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1760 if (!is_external_suspend()) { 1761 set_terminated(_thread_exiting); 1762 ThreadService::current_thread_exiting(this); 1763 break; 1764 } 1765 // Implied else: 1766 // Things get a little tricky here. We have a pending external 1767 // suspend request, but we are holding the SR_lock so we 1768 // can't just self-suspend. So we temporarily drop the lock 1769 // and then self-suspend. 1770 } 1771 1772 ThreadBlockInVM tbivm(this); 1773 java_suspend_self(); 1774 1775 // We're done with this suspend request, but we have to loop around 1776 // and check again. Eventually we will get SR_lock without a pending 1777 // external suspend request and will be able to mark ourselves as 1778 // exiting. 1779 } 1780 // no more external suspends are allowed at this point 1781 } else { 1782 // before_exit() has already posted JVMTI THREAD_END events 1783 } 1784 1785 // Notify waiters on thread object. This has to be done after exit() is called 1786 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1787 // group should have the destroyed bit set before waiters are notified). 1788 ensure_join(this); 1789 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1790 1791 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1792 // held by this thread must be released. A detach operation must only 1793 // get here if there are no Java frames on the stack. Therefore, any 1794 // owned monitors at this point MUST be JNI-acquired monitors which are 1795 // pre-inflated and in the monitor cache. 1796 // 1797 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1798 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1799 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1800 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1801 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1802 } 1803 1804 // These things needs to be done while we are still a Java Thread. Make sure that thread 1805 // is in a consistent state, in case GC happens 1806 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1807 1808 if (active_handles() != NULL) { 1809 JNIHandleBlock* block = active_handles(); 1810 set_active_handles(NULL); 1811 JNIHandleBlock::release_block(block); 1812 } 1813 1814 if (free_handle_block() != NULL) { 1815 JNIHandleBlock* block = free_handle_block(); 1816 set_free_handle_block(NULL); 1817 JNIHandleBlock::release_block(block); 1818 } 1819 1820 // These have to be removed while this is still a valid thread. 1821 remove_stack_guard_pages(); 1822 1823 if (UseTLAB) { 1824 tlab().make_parsable(true); // retire TLAB 1825 } 1826 1827 if (JvmtiEnv::environments_might_exist()) { 1828 JvmtiExport::cleanup_thread(this); 1829 } 1830 1831 // We must flush any deferred card marks before removing a thread from 1832 // the list of active threads. 1833 Universe::heap()->flush_deferred_store_barrier(this); 1834 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1835 1836#if INCLUDE_ALL_GCS 1837 // We must flush the G1-related buffers before removing a thread 1838 // from the list of active threads. We must do this after any deferred 1839 // card marks have been flushed (above) so that any entries that are 1840 // added to the thread's dirty card queue as a result are not lost. 1841 if (UseG1GC) { 1842 flush_barrier_queues(); 1843 } 1844#endif // INCLUDE_ALL_GCS 1845 1846 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1847 Threads::remove(this); 1848} 1849 1850#if INCLUDE_ALL_GCS 1851// Flush G1-related queues. 1852void JavaThread::flush_barrier_queues() { 1853 satb_mark_queue().flush(); 1854 dirty_card_queue().flush(); 1855} 1856 1857void JavaThread::initialize_queues() { 1858 assert(!SafepointSynchronize::is_at_safepoint(), 1859 "we should not be at a safepoint"); 1860 1861 ObjPtrQueue& satb_queue = satb_mark_queue(); 1862 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1863 // The SATB queue should have been constructed with its active 1864 // field set to false. 1865 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1866 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1867 // If we are creating the thread during a marking cycle, we should 1868 // set the active field of the SATB queue to true. 1869 if (satb_queue_set.is_active()) { 1870 satb_queue.set_active(true); 1871 } 1872 1873 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1874 // The dirty card queue should have been constructed with its 1875 // active field set to true. 1876 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1877} 1878#endif // INCLUDE_ALL_GCS 1879 1880void JavaThread::cleanup_failed_attach_current_thread() { 1881 if (get_thread_profiler() != NULL) { 1882 get_thread_profiler()->disengage(); 1883 ResourceMark rm; 1884 get_thread_profiler()->print(get_thread_name()); 1885 } 1886 1887 if (active_handles() != NULL) { 1888 JNIHandleBlock* block = active_handles(); 1889 set_active_handles(NULL); 1890 JNIHandleBlock::release_block(block); 1891 } 1892 1893 if (free_handle_block() != NULL) { 1894 JNIHandleBlock* block = free_handle_block(); 1895 set_free_handle_block(NULL); 1896 JNIHandleBlock::release_block(block); 1897 } 1898 1899 // These have to be removed while this is still a valid thread. 1900 remove_stack_guard_pages(); 1901 1902 if (UseTLAB) { 1903 tlab().make_parsable(true); // retire TLAB, if any 1904 } 1905 1906#if INCLUDE_ALL_GCS 1907 if (UseG1GC) { 1908 flush_barrier_queues(); 1909 } 1910#endif // INCLUDE_ALL_GCS 1911 1912 Threads::remove(this); 1913 delete this; 1914} 1915 1916 1917 1918 1919JavaThread* JavaThread::active() { 1920 Thread* thread = ThreadLocalStorage::thread(); 1921 assert(thread != NULL, "just checking"); 1922 if (thread->is_Java_thread()) { 1923 return (JavaThread*) thread; 1924 } else { 1925 assert(thread->is_VM_thread(), "this must be a vm thread"); 1926 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1927 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1928 assert(ret->is_Java_thread(), "must be a Java thread"); 1929 return ret; 1930 } 1931} 1932 1933bool JavaThread::is_lock_owned(address adr) const { 1934 if (Thread::is_lock_owned(adr)) return true; 1935 1936 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1937 if (chunk->contains(adr)) return true; 1938 } 1939 1940 return false; 1941} 1942 1943 1944void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1945 chunk->set_next(monitor_chunks()); 1946 set_monitor_chunks(chunk); 1947} 1948 1949void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1950 guarantee(monitor_chunks() != NULL, "must be non empty"); 1951 if (monitor_chunks() == chunk) { 1952 set_monitor_chunks(chunk->next()); 1953 } else { 1954 MonitorChunk* prev = monitor_chunks(); 1955 while (prev->next() != chunk) prev = prev->next(); 1956 prev->set_next(chunk->next()); 1957 } 1958} 1959 1960// JVM support. 1961 1962// Note: this function shouldn't block if it's called in 1963// _thread_in_native_trans state (such as from 1964// check_special_condition_for_native_trans()). 1965void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 1966 1967 if (has_last_Java_frame() && has_async_condition()) { 1968 // If we are at a polling page safepoint (not a poll return) 1969 // then we must defer async exception because live registers 1970 // will be clobbered by the exception path. Poll return is 1971 // ok because the call we a returning from already collides 1972 // with exception handling registers and so there is no issue. 1973 // (The exception handling path kills call result registers but 1974 // this is ok since the exception kills the result anyway). 1975 1976 if (is_at_poll_safepoint()) { 1977 // if the code we are returning to has deoptimized we must defer 1978 // the exception otherwise live registers get clobbered on the 1979 // exception path before deoptimization is able to retrieve them. 1980 // 1981 RegisterMap map(this, false); 1982 frame caller_fr = last_frame().sender(&map); 1983 assert(caller_fr.is_compiled_frame(), "what?"); 1984 if (caller_fr.is_deoptimized_frame()) { 1985 if (TraceExceptions) { 1986 ResourceMark rm; 1987 tty->print_cr("deferred async exception at compiled safepoint"); 1988 } 1989 return; 1990 } 1991 } 1992 } 1993 1994 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 1995 if (condition == _no_async_condition) { 1996 // Conditions have changed since has_special_runtime_exit_condition() 1997 // was called: 1998 // - if we were here only because of an external suspend request, 1999 // then that was taken care of above (or cancelled) so we are done 2000 // - if we were here because of another async request, then it has 2001 // been cleared between the has_special_runtime_exit_condition() 2002 // and now so again we are done 2003 return; 2004 } 2005 2006 // Check for pending async. exception 2007 if (_pending_async_exception != NULL) { 2008 // Only overwrite an already pending exception, if it is not a threadDeath. 2009 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2010 2011 // We cannot call Exceptions::_throw(...) here because we cannot block 2012 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2013 2014 if (TraceExceptions) { 2015 ResourceMark rm; 2016 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 2017 if (has_last_Java_frame()) { 2018 frame f = last_frame(); 2019 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 2020 } 2021 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2022 } 2023 _pending_async_exception = NULL; 2024 clear_has_async_exception(); 2025 } 2026 } 2027 2028 if (check_unsafe_error && 2029 condition == _async_unsafe_access_error && !has_pending_exception()) { 2030 condition = _no_async_condition; // done 2031 switch (thread_state()) { 2032 case _thread_in_vm: { 2033 JavaThread* THREAD = this; 2034 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2035 } 2036 case _thread_in_native: { 2037 ThreadInVMfromNative tiv(this); 2038 JavaThread* THREAD = this; 2039 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2040 } 2041 case _thread_in_Java: { 2042 ThreadInVMfromJava tiv(this); 2043 JavaThread* THREAD = this; 2044 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2045 } 2046 default: 2047 ShouldNotReachHere(); 2048 } 2049 } 2050 2051 assert(condition == _no_async_condition || has_pending_exception() || 2052 (!check_unsafe_error && condition == _async_unsafe_access_error), 2053 "must have handled the async condition, if no exception"); 2054} 2055 2056void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2057 // 2058 // Check for pending external suspend. Internal suspend requests do 2059 // not use handle_special_runtime_exit_condition(). 2060 // If JNIEnv proxies are allowed, don't self-suspend if the target 2061 // thread is not the current thread. In older versions of jdbx, jdbx 2062 // threads could call into the VM with another thread's JNIEnv so we 2063 // can be here operating on behalf of a suspended thread (4432884). 2064 bool do_self_suspend = is_external_suspend_with_lock(); 2065 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2066 // 2067 // Because thread is external suspended the safepoint code will count 2068 // thread as at a safepoint. This can be odd because we can be here 2069 // as _thread_in_Java which would normally transition to _thread_blocked 2070 // at a safepoint. We would like to mark the thread as _thread_blocked 2071 // before calling java_suspend_self like all other callers of it but 2072 // we must then observe proper safepoint protocol. (We can't leave 2073 // _thread_blocked with a safepoint in progress). However we can be 2074 // here as _thread_in_native_trans so we can't use a normal transition 2075 // constructor/destructor pair because they assert on that type of 2076 // transition. We could do something like: 2077 // 2078 // JavaThreadState state = thread_state(); 2079 // set_thread_state(_thread_in_vm); 2080 // { 2081 // ThreadBlockInVM tbivm(this); 2082 // java_suspend_self() 2083 // } 2084 // set_thread_state(_thread_in_vm_trans); 2085 // if (safepoint) block; 2086 // set_thread_state(state); 2087 // 2088 // but that is pretty messy. Instead we just go with the way the 2089 // code has worked before and note that this is the only path to 2090 // java_suspend_self that doesn't put the thread in _thread_blocked 2091 // mode. 2092 2093 frame_anchor()->make_walkable(this); 2094 java_suspend_self(); 2095 2096 // We might be here for reasons in addition to the self-suspend request 2097 // so check for other async requests. 2098 } 2099 2100 if (check_asyncs) { 2101 check_and_handle_async_exceptions(); 2102 } 2103} 2104 2105void JavaThread::send_thread_stop(oop java_throwable) { 2106 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2107 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2108 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2109 2110 // Do not throw asynchronous exceptions against the compiler thread 2111 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2112 if (is_Compiler_thread()) return; 2113 2114 { 2115 // Actually throw the Throwable against the target Thread - however 2116 // only if there is no thread death exception installed already. 2117 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2118 // If the topmost frame is a runtime stub, then we are calling into 2119 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2120 // must deoptimize the caller before continuing, as the compiled exception handler table 2121 // may not be valid 2122 if (has_last_Java_frame()) { 2123 frame f = last_frame(); 2124 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2125 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2126 RegisterMap reg_map(this, UseBiasedLocking); 2127 frame compiled_frame = f.sender(®_map); 2128 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2129 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2130 } 2131 } 2132 } 2133 2134 // Set async. pending exception in thread. 2135 set_pending_async_exception(java_throwable); 2136 2137 if (TraceExceptions) { 2138 ResourceMark rm; 2139 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2140 } 2141 // for AbortVMOnException flag 2142 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name())); 2143 } 2144 } 2145 2146 2147 // Interrupt thread so it will wake up from a potential wait() 2148 Thread::interrupt(this); 2149} 2150 2151// External suspension mechanism. 2152// 2153// Tell the VM to suspend a thread when ever it knows that it does not hold on 2154// to any VM_locks and it is at a transition 2155// Self-suspension will happen on the transition out of the vm. 2156// Catch "this" coming in from JNIEnv pointers when the thread has been freed 2157// 2158// Guarantees on return: 2159// + Target thread will not execute any new bytecode (that's why we need to 2160// force a safepoint) 2161// + Target thread will not enter any new monitors 2162// 2163void JavaThread::java_suspend() { 2164 { MutexLocker mu(Threads_lock); 2165 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2166 return; 2167 } 2168 } 2169 2170 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2171 if (!is_external_suspend()) { 2172 // a racing resume has cancelled us; bail out now 2173 return; 2174 } 2175 2176 // suspend is done 2177 uint32_t debug_bits = 0; 2178 // Warning: is_ext_suspend_completed() may temporarily drop the 2179 // SR_lock to allow the thread to reach a stable thread state if 2180 // it is currently in a transient thread state. 2181 if (is_ext_suspend_completed(false /* !called_by_wait */, 2182 SuspendRetryDelay, &debug_bits)) { 2183 return; 2184 } 2185 } 2186 2187 VM_ForceSafepoint vm_suspend; 2188 VMThread::execute(&vm_suspend); 2189} 2190 2191// Part II of external suspension. 2192// A JavaThread self suspends when it detects a pending external suspend 2193// request. This is usually on transitions. It is also done in places 2194// where continuing to the next transition would surprise the caller, 2195// e.g., monitor entry. 2196// 2197// Returns the number of times that the thread self-suspended. 2198// 2199// Note: DO NOT call java_suspend_self() when you just want to block current 2200// thread. java_suspend_self() is the second stage of cooperative 2201// suspension for external suspend requests and should only be used 2202// to complete an external suspend request. 2203// 2204int JavaThread::java_suspend_self() { 2205 int ret = 0; 2206 2207 // we are in the process of exiting so don't suspend 2208 if (is_exiting()) { 2209 clear_external_suspend(); 2210 return ret; 2211 } 2212 2213 assert(_anchor.walkable() || 2214 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2215 "must have walkable stack"); 2216 2217 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2218 2219 assert(!this->is_ext_suspended(), 2220 "a thread trying to self-suspend should not already be suspended"); 2221 2222 if (this->is_suspend_equivalent()) { 2223 // If we are self-suspending as a result of the lifting of a 2224 // suspend equivalent condition, then the suspend_equivalent 2225 // flag is not cleared until we set the ext_suspended flag so 2226 // that wait_for_ext_suspend_completion() returns consistent 2227 // results. 2228 this->clear_suspend_equivalent(); 2229 } 2230 2231 // A racing resume may have cancelled us before we grabbed SR_lock 2232 // above. Or another external suspend request could be waiting for us 2233 // by the time we return from SR_lock()->wait(). The thread 2234 // that requested the suspension may already be trying to walk our 2235 // stack and if we return now, we can change the stack out from under 2236 // it. This would be a "bad thing (TM)" and cause the stack walker 2237 // to crash. We stay self-suspended until there are no more pending 2238 // external suspend requests. 2239 while (is_external_suspend()) { 2240 ret++; 2241 this->set_ext_suspended(); 2242 2243 // _ext_suspended flag is cleared by java_resume() 2244 while (is_ext_suspended()) { 2245 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2246 } 2247 } 2248 2249 return ret; 2250} 2251 2252#ifdef ASSERT 2253// verify the JavaThread has not yet been published in the Threads::list, and 2254// hence doesn't need protection from concurrent access at this stage 2255void JavaThread::verify_not_published() { 2256 if (!Threads_lock->owned_by_self()) { 2257 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2258 assert(!Threads::includes(this), 2259 "java thread shouldn't have been published yet!"); 2260 } else { 2261 assert(!Threads::includes(this), 2262 "java thread shouldn't have been published yet!"); 2263 } 2264} 2265#endif 2266 2267// Slow path when the native==>VM/Java barriers detect a safepoint is in 2268// progress or when _suspend_flags is non-zero. 2269// Current thread needs to self-suspend if there is a suspend request and/or 2270// block if a safepoint is in progress. 2271// Async exception ISN'T checked. 2272// Note only the ThreadInVMfromNative transition can call this function 2273// directly and when thread state is _thread_in_native_trans 2274void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2275 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2276 2277 JavaThread *curJT = JavaThread::current(); 2278 bool do_self_suspend = thread->is_external_suspend(); 2279 2280 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2281 2282 // If JNIEnv proxies are allowed, don't self-suspend if the target 2283 // thread is not the current thread. In older versions of jdbx, jdbx 2284 // threads could call into the VM with another thread's JNIEnv so we 2285 // can be here operating on behalf of a suspended thread (4432884). 2286 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2287 JavaThreadState state = thread->thread_state(); 2288 2289 // We mark this thread_blocked state as a suspend-equivalent so 2290 // that a caller to is_ext_suspend_completed() won't be confused. 2291 // The suspend-equivalent state is cleared by java_suspend_self(). 2292 thread->set_suspend_equivalent(); 2293 2294 // If the safepoint code sees the _thread_in_native_trans state, it will 2295 // wait until the thread changes to other thread state. There is no 2296 // guarantee on how soon we can obtain the SR_lock and complete the 2297 // self-suspend request. It would be a bad idea to let safepoint wait for 2298 // too long. Temporarily change the state to _thread_blocked to 2299 // let the VM thread know that this thread is ready for GC. The problem 2300 // of changing thread state is that safepoint could happen just after 2301 // java_suspend_self() returns after being resumed, and VM thread will 2302 // see the _thread_blocked state. We must check for safepoint 2303 // after restoring the state and make sure we won't leave while a safepoint 2304 // is in progress. 2305 thread->set_thread_state(_thread_blocked); 2306 thread->java_suspend_self(); 2307 thread->set_thread_state(state); 2308 // Make sure new state is seen by VM thread 2309 if (os::is_MP()) { 2310 if (UseMembar) { 2311 // Force a fence between the write above and read below 2312 OrderAccess::fence(); 2313 } else { 2314 // Must use this rather than serialization page in particular on Windows 2315 InterfaceSupport::serialize_memory(thread); 2316 } 2317 } 2318 } 2319 2320 if (SafepointSynchronize::do_call_back()) { 2321 // If we are safepointing, then block the caller which may not be 2322 // the same as the target thread (see above). 2323 SafepointSynchronize::block(curJT); 2324 } 2325 2326 if (thread->is_deopt_suspend()) { 2327 thread->clear_deopt_suspend(); 2328 RegisterMap map(thread, false); 2329 frame f = thread->last_frame(); 2330 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2331 f = f.sender(&map); 2332 } 2333 if (f.id() == thread->must_deopt_id()) { 2334 thread->clear_must_deopt_id(); 2335 f.deoptimize(thread); 2336 } else { 2337 fatal("missed deoptimization!"); 2338 } 2339 } 2340} 2341 2342// Slow path when the native==>VM/Java barriers detect a safepoint is in 2343// progress or when _suspend_flags is non-zero. 2344// Current thread needs to self-suspend if there is a suspend request and/or 2345// block if a safepoint is in progress. 2346// Also check for pending async exception (not including unsafe access error). 2347// Note only the native==>VM/Java barriers can call this function and when 2348// thread state is _thread_in_native_trans. 2349void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2350 check_safepoint_and_suspend_for_native_trans(thread); 2351 2352 if (thread->has_async_exception()) { 2353 // We are in _thread_in_native_trans state, don't handle unsafe 2354 // access error since that may block. 2355 thread->check_and_handle_async_exceptions(false); 2356 } 2357} 2358 2359// This is a variant of the normal 2360// check_special_condition_for_native_trans with slightly different 2361// semantics for use by critical native wrappers. It does all the 2362// normal checks but also performs the transition back into 2363// thread_in_Java state. This is required so that critical natives 2364// can potentially block and perform a GC if they are the last thread 2365// exiting the GC_locker. 2366void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2367 check_special_condition_for_native_trans(thread); 2368 2369 // Finish the transition 2370 thread->set_thread_state(_thread_in_Java); 2371 2372 if (thread->do_critical_native_unlock()) { 2373 ThreadInVMfromJavaNoAsyncException tiv(thread); 2374 GC_locker::unlock_critical(thread); 2375 thread->clear_critical_native_unlock(); 2376 } 2377} 2378 2379// We need to guarantee the Threads_lock here, since resumes are not 2380// allowed during safepoint synchronization 2381// Can only resume from an external suspension 2382void JavaThread::java_resume() { 2383 assert_locked_or_safepoint(Threads_lock); 2384 2385 // Sanity check: thread is gone, has started exiting or the thread 2386 // was not externally suspended. 2387 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2388 return; 2389 } 2390 2391 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2392 2393 clear_external_suspend(); 2394 2395 if (is_ext_suspended()) { 2396 clear_ext_suspended(); 2397 SR_lock()->notify_all(); 2398 } 2399} 2400 2401void JavaThread::create_stack_guard_pages() { 2402 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2403 address low_addr = stack_base() - stack_size(); 2404 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2405 2406 int allocate = os::allocate_stack_guard_pages(); 2407 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2408 2409 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2410 warning("Attempt to allocate stack guard pages failed."); 2411 return; 2412 } 2413 2414 if (os::guard_memory((char *) low_addr, len)) { 2415 _stack_guard_state = stack_guard_enabled; 2416 } else { 2417 warning("Attempt to protect stack guard pages failed."); 2418 if (os::uncommit_memory((char *) low_addr, len)) { 2419 warning("Attempt to deallocate stack guard pages failed."); 2420 } 2421 } 2422} 2423 2424void JavaThread::remove_stack_guard_pages() { 2425 assert(Thread::current() == this, "from different thread"); 2426 if (_stack_guard_state == stack_guard_unused) return; 2427 address low_addr = stack_base() - stack_size(); 2428 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2429 2430 if (os::allocate_stack_guard_pages()) { 2431 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2432 _stack_guard_state = stack_guard_unused; 2433 } else { 2434 warning("Attempt to deallocate stack guard pages failed."); 2435 } 2436 } else { 2437 if (_stack_guard_state == stack_guard_unused) return; 2438 if (os::unguard_memory((char *) low_addr, len)) { 2439 _stack_guard_state = stack_guard_unused; 2440 } else { 2441 warning("Attempt to unprotect stack guard pages failed."); 2442 } 2443 } 2444} 2445 2446void JavaThread::enable_stack_yellow_zone() { 2447 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2448 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2449 2450 // The base notation is from the stacks point of view, growing downward. 2451 // We need to adjust it to work correctly with guard_memory() 2452 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2453 2454 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2455 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2456 2457 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2458 _stack_guard_state = stack_guard_enabled; 2459 } else { 2460 warning("Attempt to guard stack yellow zone failed."); 2461 } 2462 enable_register_stack_guard(); 2463} 2464 2465void JavaThread::disable_stack_yellow_zone() { 2466 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2467 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2468 2469 // Simply return if called for a thread that does not use guard pages. 2470 if (_stack_guard_state == stack_guard_unused) return; 2471 2472 // The base notation is from the stacks point of view, growing downward. 2473 // We need to adjust it to work correctly with guard_memory() 2474 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2475 2476 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2477 _stack_guard_state = stack_guard_yellow_disabled; 2478 } else { 2479 warning("Attempt to unguard stack yellow zone failed."); 2480 } 2481 disable_register_stack_guard(); 2482} 2483 2484void JavaThread::enable_stack_red_zone() { 2485 // The base notation is from the stacks point of view, growing downward. 2486 // We need to adjust it to work correctly with guard_memory() 2487 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2488 address base = stack_red_zone_base() - stack_red_zone_size(); 2489 2490 guarantee(base < stack_base(), "Error calculating stack red zone"); 2491 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2492 2493 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2494 warning("Attempt to guard stack red zone failed."); 2495 } 2496} 2497 2498void JavaThread::disable_stack_red_zone() { 2499 // The base notation is from the stacks point of view, growing downward. 2500 // We need to adjust it to work correctly with guard_memory() 2501 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2502 address base = stack_red_zone_base() - stack_red_zone_size(); 2503 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2504 warning("Attempt to unguard stack red zone failed."); 2505 } 2506} 2507 2508void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2509 // ignore is there is no stack 2510 if (!has_last_Java_frame()) return; 2511 // traverse the stack frames. Starts from top frame. 2512 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2513 frame* fr = fst.current(); 2514 f(fr, fst.register_map()); 2515 } 2516} 2517 2518 2519#ifndef PRODUCT 2520// Deoptimization 2521// Function for testing deoptimization 2522void JavaThread::deoptimize() { 2523 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2524 StackFrameStream fst(this, UseBiasedLocking); 2525 bool deopt = false; // Dump stack only if a deopt actually happens. 2526 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2527 // Iterate over all frames in the thread and deoptimize 2528 for (; !fst.is_done(); fst.next()) { 2529 if (fst.current()->can_be_deoptimized()) { 2530 2531 if (only_at) { 2532 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2533 // consists of comma or carriage return separated numbers so 2534 // search for the current bci in that string. 2535 address pc = fst.current()->pc(); 2536 nmethod* nm = (nmethod*) fst.current()->cb(); 2537 ScopeDesc* sd = nm->scope_desc_at(pc); 2538 char buffer[8]; 2539 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2540 size_t len = strlen(buffer); 2541 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2542 while (found != NULL) { 2543 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2544 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2545 // Check that the bci found is bracketed by terminators. 2546 break; 2547 } 2548 found = strstr(found + 1, buffer); 2549 } 2550 if (!found) { 2551 continue; 2552 } 2553 } 2554 2555 if (DebugDeoptimization && !deopt) { 2556 deopt = true; // One-time only print before deopt 2557 tty->print_cr("[BEFORE Deoptimization]"); 2558 trace_frames(); 2559 trace_stack(); 2560 } 2561 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2562 } 2563 } 2564 2565 if (DebugDeoptimization && deopt) { 2566 tty->print_cr("[AFTER Deoptimization]"); 2567 trace_frames(); 2568 } 2569} 2570 2571 2572// Make zombies 2573void JavaThread::make_zombies() { 2574 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2575 if (fst.current()->can_be_deoptimized()) { 2576 // it is a Java nmethod 2577 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2578 nm->make_not_entrant(); 2579 } 2580 } 2581} 2582#endif // PRODUCT 2583 2584 2585void JavaThread::deoptimized_wrt_marked_nmethods() { 2586 if (!has_last_Java_frame()) return; 2587 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2588 StackFrameStream fst(this, UseBiasedLocking); 2589 for (; !fst.is_done(); fst.next()) { 2590 if (fst.current()->should_be_deoptimized()) { 2591 if (LogCompilation && xtty != NULL) { 2592 nmethod* nm = fst.current()->cb()->as_nmethod_or_null(); 2593 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'", 2594 this->name(), nm != NULL ? nm->compile_id() : -1); 2595 } 2596 2597 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2598 } 2599 } 2600} 2601 2602 2603// If the caller is a NamedThread, then remember, in the current scope, 2604// the given JavaThread in its _processed_thread field. 2605class RememberProcessedThread: public StackObj { 2606 NamedThread* _cur_thr; 2607 public: 2608 RememberProcessedThread(JavaThread* jthr) { 2609 Thread* thread = Thread::current(); 2610 if (thread->is_Named_thread()) { 2611 _cur_thr = (NamedThread *)thread; 2612 _cur_thr->set_processed_thread(jthr); 2613 } else { 2614 _cur_thr = NULL; 2615 } 2616 } 2617 2618 ~RememberProcessedThread() { 2619 if (_cur_thr) { 2620 _cur_thr->set_processed_thread(NULL); 2621 } 2622 } 2623}; 2624 2625void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2626 // Verify that the deferred card marks have been flushed. 2627 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2628 2629 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2630 // since there may be more than one thread using each ThreadProfiler. 2631 2632 // Traverse the GCHandles 2633 Thread::oops_do(f, cld_f, cf); 2634 2635 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2636 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2637 2638 if (has_last_Java_frame()) { 2639 // Record JavaThread to GC thread 2640 RememberProcessedThread rpt(this); 2641 2642 // Traverse the privileged stack 2643 if (_privileged_stack_top != NULL) { 2644 _privileged_stack_top->oops_do(f); 2645 } 2646 2647 // traverse the registered growable array 2648 if (_array_for_gc != NULL) { 2649 for (int index = 0; index < _array_for_gc->length(); index++) { 2650 f->do_oop(_array_for_gc->adr_at(index)); 2651 } 2652 } 2653 2654 // Traverse the monitor chunks 2655 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2656 chunk->oops_do(f); 2657 } 2658 2659 // Traverse the execution stack 2660 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2661 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2662 } 2663 } 2664 2665 // callee_target is never live across a gc point so NULL it here should 2666 // it still contain a methdOop. 2667 2668 set_callee_target(NULL); 2669 2670 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2671 // If we have deferred set_locals there might be oops waiting to be 2672 // written 2673 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2674 if (list != NULL) { 2675 for (int i = 0; i < list->length(); i++) { 2676 list->at(i)->oops_do(f); 2677 } 2678 } 2679 2680 // Traverse instance variables at the end since the GC may be moving things 2681 // around using this function 2682 f->do_oop((oop*) &_threadObj); 2683 f->do_oop((oop*) &_vm_result); 2684 f->do_oop((oop*) &_exception_oop); 2685 f->do_oop((oop*) &_pending_async_exception); 2686 2687 if (jvmti_thread_state() != NULL) { 2688 jvmti_thread_state()->oops_do(f); 2689 } 2690} 2691 2692void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2693 Thread::nmethods_do(cf); // (super method is a no-op) 2694 2695 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2696 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2697 2698 if (has_last_Java_frame()) { 2699 // Traverse the execution stack 2700 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2701 fst.current()->nmethods_do(cf); 2702 } 2703 } 2704} 2705 2706void JavaThread::metadata_do(void f(Metadata*)) { 2707 Thread::metadata_do(f); 2708 if (has_last_Java_frame()) { 2709 // Traverse the execution stack to call f() on the methods in the stack 2710 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2711 fst.current()->metadata_do(f); 2712 } 2713 } else if (is_Compiler_thread()) { 2714 // need to walk ciMetadata in current compile tasks to keep alive. 2715 CompilerThread* ct = (CompilerThread*)this; 2716 if (ct->env() != NULL) { 2717 ct->env()->metadata_do(f); 2718 } 2719 } 2720} 2721 2722// Printing 2723const char* _get_thread_state_name(JavaThreadState _thread_state) { 2724 switch (_thread_state) { 2725 case _thread_uninitialized: return "_thread_uninitialized"; 2726 case _thread_new: return "_thread_new"; 2727 case _thread_new_trans: return "_thread_new_trans"; 2728 case _thread_in_native: return "_thread_in_native"; 2729 case _thread_in_native_trans: return "_thread_in_native_trans"; 2730 case _thread_in_vm: return "_thread_in_vm"; 2731 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2732 case _thread_in_Java: return "_thread_in_Java"; 2733 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2734 case _thread_blocked: return "_thread_blocked"; 2735 case _thread_blocked_trans: return "_thread_blocked_trans"; 2736 default: return "unknown thread state"; 2737 } 2738} 2739 2740#ifndef PRODUCT 2741void JavaThread::print_thread_state_on(outputStream *st) const { 2742 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2743}; 2744void JavaThread::print_thread_state() const { 2745 print_thread_state_on(tty); 2746} 2747#endif // PRODUCT 2748 2749// Called by Threads::print() for VM_PrintThreads operation 2750void JavaThread::print_on(outputStream *st) const { 2751 st->print("\"%s\" ", get_thread_name()); 2752 oop thread_oop = threadObj(); 2753 if (thread_oop != NULL) { 2754 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2755 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2756 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2757 } 2758 Thread::print_on(st); 2759 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2760 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2761 if (thread_oop != NULL) { 2762 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2763 } 2764#ifndef PRODUCT 2765 print_thread_state_on(st); 2766 _safepoint_state->print_on(st); 2767#endif // PRODUCT 2768} 2769 2770// Called by fatal error handler. The difference between this and 2771// JavaThread::print() is that we can't grab lock or allocate memory. 2772void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2773 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2774 oop thread_obj = threadObj(); 2775 if (thread_obj != NULL) { 2776 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2777 } 2778 st->print(" ["); 2779 st->print("%s", _get_thread_state_name(_thread_state)); 2780 if (osthread()) { 2781 st->print(", id=%d", osthread()->thread_id()); 2782 } 2783 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2784 _stack_base - _stack_size, _stack_base); 2785 st->print("]"); 2786 return; 2787} 2788 2789// Verification 2790 2791static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2792 2793void JavaThread::verify() { 2794 // Verify oops in the thread. 2795 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2796 2797 // Verify the stack frames. 2798 frames_do(frame_verify); 2799} 2800 2801// CR 6300358 (sub-CR 2137150) 2802// Most callers of this method assume that it can't return NULL but a 2803// thread may not have a name whilst it is in the process of attaching to 2804// the VM - see CR 6412693, and there are places where a JavaThread can be 2805// seen prior to having it's threadObj set (eg JNI attaching threads and 2806// if vm exit occurs during initialization). These cases can all be accounted 2807// for such that this method never returns NULL. 2808const char* JavaThread::get_thread_name() const { 2809#ifdef ASSERT 2810 // early safepoints can hit while current thread does not yet have TLS 2811 if (!SafepointSynchronize::is_at_safepoint()) { 2812 Thread *cur = Thread::current(); 2813 if (!(cur->is_Java_thread() && cur == this)) { 2814 // Current JavaThreads are allowed to get their own name without 2815 // the Threads_lock. 2816 assert_locked_or_safepoint(Threads_lock); 2817 } 2818 } 2819#endif // ASSERT 2820 return get_thread_name_string(); 2821} 2822 2823// Returns a non-NULL representation of this thread's name, or a suitable 2824// descriptive string if there is no set name 2825const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2826 const char* name_str; 2827 oop thread_obj = threadObj(); 2828 if (thread_obj != NULL) { 2829 oop name = java_lang_Thread::name(thread_obj); 2830 if (name != NULL) { 2831 if (buf == NULL) { 2832 name_str = java_lang_String::as_utf8_string(name); 2833 } else { 2834 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2835 } 2836 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2837 name_str = "<no-name - thread is attaching>"; 2838 } else { 2839 name_str = Thread::name(); 2840 } 2841 } else { 2842 name_str = Thread::name(); 2843 } 2844 assert(name_str != NULL, "unexpected NULL thread name"); 2845 return name_str; 2846} 2847 2848 2849const char* JavaThread::get_threadgroup_name() const { 2850 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2851 oop thread_obj = threadObj(); 2852 if (thread_obj != NULL) { 2853 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2854 if (thread_group != NULL) { 2855 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2856 // ThreadGroup.name can be null 2857 if (name != NULL) { 2858 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2859 return str; 2860 } 2861 } 2862 } 2863 return NULL; 2864} 2865 2866const char* JavaThread::get_parent_name() const { 2867 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2868 oop thread_obj = threadObj(); 2869 if (thread_obj != NULL) { 2870 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2871 if (thread_group != NULL) { 2872 oop parent = java_lang_ThreadGroup::parent(thread_group); 2873 if (parent != NULL) { 2874 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2875 // ThreadGroup.name can be null 2876 if (name != NULL) { 2877 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2878 return str; 2879 } 2880 } 2881 } 2882 } 2883 return NULL; 2884} 2885 2886ThreadPriority JavaThread::java_priority() const { 2887 oop thr_oop = threadObj(); 2888 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2889 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2890 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2891 return priority; 2892} 2893 2894void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2895 2896 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2897 // Link Java Thread object <-> C++ Thread 2898 2899 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2900 // and put it into a new Handle. The Handle "thread_oop" can then 2901 // be used to pass the C++ thread object to other methods. 2902 2903 // Set the Java level thread object (jthread) field of the 2904 // new thread (a JavaThread *) to C++ thread object using the 2905 // "thread_oop" handle. 2906 2907 // Set the thread field (a JavaThread *) of the 2908 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2909 2910 Handle thread_oop(Thread::current(), 2911 JNIHandles::resolve_non_null(jni_thread)); 2912 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 2913 "must be initialized"); 2914 set_threadObj(thread_oop()); 2915 java_lang_Thread::set_thread(thread_oop(), this); 2916 2917 if (prio == NoPriority) { 2918 prio = java_lang_Thread::priority(thread_oop()); 2919 assert(prio != NoPriority, "A valid priority should be present"); 2920 } 2921 2922 // Push the Java priority down to the native thread; needs Threads_lock 2923 Thread::set_priority(this, prio); 2924 2925 prepare_ext(); 2926 2927 // Add the new thread to the Threads list and set it in motion. 2928 // We must have threads lock in order to call Threads::add. 2929 // It is crucial that we do not block before the thread is 2930 // added to the Threads list for if a GC happens, then the java_thread oop 2931 // will not be visited by GC. 2932 Threads::add(this); 2933} 2934 2935oop JavaThread::current_park_blocker() { 2936 // Support for JSR-166 locks 2937 oop thread_oop = threadObj(); 2938 if (thread_oop != NULL && 2939 JDK_Version::current().supports_thread_park_blocker()) { 2940 return java_lang_Thread::park_blocker(thread_oop); 2941 } 2942 return NULL; 2943} 2944 2945 2946void JavaThread::print_stack_on(outputStream* st) { 2947 if (!has_last_Java_frame()) return; 2948 ResourceMark rm; 2949 HandleMark hm; 2950 2951 RegisterMap reg_map(this); 2952 vframe* start_vf = last_java_vframe(®_map); 2953 int count = 0; 2954 for (vframe* f = start_vf; f; f = f->sender()) { 2955 if (f->is_java_frame()) { 2956 javaVFrame* jvf = javaVFrame::cast(f); 2957 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 2958 2959 // Print out lock information 2960 if (JavaMonitorsInStackTrace) { 2961 jvf->print_lock_info_on(st, count); 2962 } 2963 } else { 2964 // Ignore non-Java frames 2965 } 2966 2967 // Bail-out case for too deep stacks 2968 count++; 2969 if (MaxJavaStackTraceDepth == count) return; 2970 } 2971} 2972 2973 2974// JVMTI PopFrame support 2975void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 2976 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 2977 if (in_bytes(size_in_bytes) != 0) { 2978 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 2979 _popframe_preserved_args_size = in_bytes(size_in_bytes); 2980 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 2981 } 2982} 2983 2984void* JavaThread::popframe_preserved_args() { 2985 return _popframe_preserved_args; 2986} 2987 2988ByteSize JavaThread::popframe_preserved_args_size() { 2989 return in_ByteSize(_popframe_preserved_args_size); 2990} 2991 2992WordSize JavaThread::popframe_preserved_args_size_in_words() { 2993 int sz = in_bytes(popframe_preserved_args_size()); 2994 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 2995 return in_WordSize(sz / wordSize); 2996} 2997 2998void JavaThread::popframe_free_preserved_args() { 2999 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3000 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3001 _popframe_preserved_args = NULL; 3002 _popframe_preserved_args_size = 0; 3003} 3004 3005#ifndef PRODUCT 3006 3007void JavaThread::trace_frames() { 3008 tty->print_cr("[Describe stack]"); 3009 int frame_no = 1; 3010 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3011 tty->print(" %d. ", frame_no++); 3012 fst.current()->print_value_on(tty, this); 3013 tty->cr(); 3014 } 3015} 3016 3017class PrintAndVerifyOopClosure: public OopClosure { 3018 protected: 3019 template <class T> inline void do_oop_work(T* p) { 3020 oop obj = oopDesc::load_decode_heap_oop(p); 3021 if (obj == NULL) return; 3022 tty->print(INTPTR_FORMAT ": ", p); 3023 if (obj->is_oop_or_null()) { 3024 if (obj->is_objArray()) { 3025 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); 3026 } else { 3027 obj->print(); 3028 } 3029 } else { 3030 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); 3031 } 3032 tty->cr(); 3033 } 3034 public: 3035 virtual void do_oop(oop* p) { do_oop_work(p); } 3036 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3037}; 3038 3039 3040static void oops_print(frame* f, const RegisterMap *map) { 3041 PrintAndVerifyOopClosure print; 3042 f->print_value(); 3043 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3044} 3045 3046// Print our all the locations that contain oops and whether they are 3047// valid or not. This useful when trying to find the oldest frame 3048// where an oop has gone bad since the frame walk is from youngest to 3049// oldest. 3050void JavaThread::trace_oops() { 3051 tty->print_cr("[Trace oops]"); 3052 frames_do(oops_print); 3053} 3054 3055 3056#ifdef ASSERT 3057// Print or validate the layout of stack frames 3058void JavaThread::print_frame_layout(int depth, bool validate_only) { 3059 ResourceMark rm; 3060 PRESERVE_EXCEPTION_MARK; 3061 FrameValues values; 3062 int frame_no = 0; 3063 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3064 fst.current()->describe(values, ++frame_no); 3065 if (depth == frame_no) break; 3066 } 3067 if (validate_only) { 3068 values.validate(); 3069 } else { 3070 tty->print_cr("[Describe stack layout]"); 3071 values.print(this); 3072 } 3073} 3074#endif 3075 3076void JavaThread::trace_stack_from(vframe* start_vf) { 3077 ResourceMark rm; 3078 int vframe_no = 1; 3079 for (vframe* f = start_vf; f; f = f->sender()) { 3080 if (f->is_java_frame()) { 3081 javaVFrame::cast(f)->print_activation(vframe_no++); 3082 } else { 3083 f->print(); 3084 } 3085 if (vframe_no > StackPrintLimit) { 3086 tty->print_cr("...<more frames>..."); 3087 return; 3088 } 3089 } 3090} 3091 3092 3093void JavaThread::trace_stack() { 3094 if (!has_last_Java_frame()) return; 3095 ResourceMark rm; 3096 HandleMark hm; 3097 RegisterMap reg_map(this); 3098 trace_stack_from(last_java_vframe(®_map)); 3099} 3100 3101 3102#endif // PRODUCT 3103 3104 3105javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3106 assert(reg_map != NULL, "a map must be given"); 3107 frame f = last_frame(); 3108 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3109 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3110 } 3111 return NULL; 3112} 3113 3114 3115Klass* JavaThread::security_get_caller_class(int depth) { 3116 vframeStream vfst(this); 3117 vfst.security_get_caller_frame(depth); 3118 if (!vfst.at_end()) { 3119 return vfst.method()->method_holder(); 3120 } 3121 return NULL; 3122} 3123 3124static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3125 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3126 CompileBroker::compiler_thread_loop(); 3127} 3128 3129static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3130 NMethodSweeper::sweeper_loop(); 3131} 3132 3133// Create a CompilerThread 3134CompilerThread::CompilerThread(CompileQueue* queue, 3135 CompilerCounters* counters) 3136 : JavaThread(&compiler_thread_entry) { 3137 _env = NULL; 3138 _log = NULL; 3139 _task = NULL; 3140 _queue = queue; 3141 _counters = counters; 3142 _buffer_blob = NULL; 3143 _compiler = NULL; 3144 3145#ifndef PRODUCT 3146 _ideal_graph_printer = NULL; 3147#endif 3148} 3149 3150// Create sweeper thread 3151CodeCacheSweeperThread::CodeCacheSweeperThread() 3152: JavaThread(&sweeper_thread_entry) { 3153 _scanned_nmethod = NULL; 3154} 3155void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3156 JavaThread::oops_do(f, cld_f, cf); 3157 if (_scanned_nmethod != NULL && cf != NULL) { 3158 // Safepoints can occur when the sweeper is scanning an nmethod so 3159 // process it here to make sure it isn't unloaded in the middle of 3160 // a scan. 3161 cf->do_code_blob(_scanned_nmethod); 3162 } 3163} 3164 3165 3166// ======= Threads ======== 3167 3168// The Threads class links together all active threads, and provides 3169// operations over all threads. It is protected by its own Mutex 3170// lock, which is also used in other contexts to protect thread 3171// operations from having the thread being operated on from exiting 3172// and going away unexpectedly (e.g., safepoint synchronization) 3173 3174JavaThread* Threads::_thread_list = NULL; 3175int Threads::_number_of_threads = 0; 3176int Threads::_number_of_non_daemon_threads = 0; 3177int Threads::_return_code = 0; 3178size_t JavaThread::_stack_size_at_create = 0; 3179#ifdef ASSERT 3180bool Threads::_vm_complete = false; 3181#endif 3182 3183// All JavaThreads 3184#define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3185 3186// All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3187void Threads::threads_do(ThreadClosure* tc) { 3188 assert_locked_or_safepoint(Threads_lock); 3189 // ALL_JAVA_THREADS iterates through all JavaThreads 3190 ALL_JAVA_THREADS(p) { 3191 tc->do_thread(p); 3192 } 3193 // Someday we could have a table or list of all non-JavaThreads. 3194 // For now, just manually iterate through them. 3195 tc->do_thread(VMThread::vm_thread()); 3196 Universe::heap()->gc_threads_do(tc); 3197 WatcherThread *wt = WatcherThread::watcher_thread(); 3198 // Strictly speaking, the following NULL check isn't sufficient to make sure 3199 // the data for WatcherThread is still valid upon being examined. However, 3200 // considering that WatchThread terminates when the VM is on the way to 3201 // exit at safepoint, the chance of the above is extremely small. The right 3202 // way to prevent termination of WatcherThread would be to acquire 3203 // Terminator_lock, but we can't do that without violating the lock rank 3204 // checking in some cases. 3205 if (wt != NULL) { 3206 tc->do_thread(wt); 3207 } 3208 3209 // If CompilerThreads ever become non-JavaThreads, add them here 3210} 3211 3212 3213void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3214 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3215 3216 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3217 create_vm_init_libraries(); 3218 } 3219 3220 initialize_class(vmSymbols::java_lang_String(), CHECK); 3221 3222 // Initialize java_lang.System (needed before creating the thread) 3223 initialize_class(vmSymbols::java_lang_System(), CHECK); 3224 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3225 Handle thread_group = create_initial_thread_group(CHECK); 3226 Universe::set_main_thread_group(thread_group()); 3227 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3228 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3229 main_thread->set_threadObj(thread_object); 3230 // Set thread status to running since main thread has 3231 // been started and running. 3232 java_lang_Thread::set_thread_status(thread_object, 3233 java_lang_Thread::RUNNABLE); 3234 3235 // The VM creates & returns objects of this class. Make sure it's initialized. 3236 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3237 3238 // The VM preresolves methods to these classes. Make sure that they get initialized 3239 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3240 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3241 call_initializeSystemClass(CHECK); 3242 3243 // get the Java runtime name after java.lang.System is initialized 3244 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3245 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3246 3247 // an instance of OutOfMemory exception has been allocated earlier 3248 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3249 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3250 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3251 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3252 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3253 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3254 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3255 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3256} 3257 3258void Threads::initialize_jsr292_core_classes(TRAPS) { 3259 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3260 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3261 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3262} 3263 3264jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3265 extern void JDK_Version_init(); 3266 3267 // Check version 3268 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3269 3270 // Initialize the output stream module 3271 ostream_init(); 3272 3273 // Process java launcher properties. 3274 Arguments::process_sun_java_launcher_properties(args); 3275 3276 // Initialize the os module before using TLS 3277 os::init(); 3278 3279 // Initialize system properties. 3280 Arguments::init_system_properties(); 3281 3282 // So that JDK version can be used as a discriminator when parsing arguments 3283 JDK_Version_init(); 3284 3285 // Update/Initialize System properties after JDK version number is known 3286 Arguments::init_version_specific_system_properties(); 3287 3288 // Parse arguments 3289 jint parse_result = Arguments::parse(args); 3290 if (parse_result != JNI_OK) return parse_result; 3291 3292 os::init_before_ergo(); 3293 3294 jint ergo_result = Arguments::apply_ergo(); 3295 if (ergo_result != JNI_OK) return ergo_result; 3296 3297 if (PauseAtStartup) { 3298 os::pause(); 3299 } 3300 3301 HOTSPOT_VM_INIT_BEGIN(); 3302 3303 // Record VM creation timing statistics 3304 TraceVmCreationTime create_vm_timer; 3305 create_vm_timer.start(); 3306 3307 // Timing (must come after argument parsing) 3308 TraceTime timer("Create VM", TraceStartupTime); 3309 3310 // Initialize the os module after parsing the args 3311 jint os_init_2_result = os::init_2(); 3312 if (os_init_2_result != JNI_OK) return os_init_2_result; 3313 3314 jint adjust_after_os_result = Arguments::adjust_after_os(); 3315 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3316 3317 // initialize TLS 3318 ThreadLocalStorage::init(); 3319 3320 // Initialize output stream logging 3321 ostream_init_log(); 3322 3323 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3324 // Must be before create_vm_init_agents() 3325 if (Arguments::init_libraries_at_startup()) { 3326 convert_vm_init_libraries_to_agents(); 3327 } 3328 3329 // Launch -agentlib/-agentpath and converted -Xrun agents 3330 if (Arguments::init_agents_at_startup()) { 3331 create_vm_init_agents(); 3332 } 3333 3334 // Initialize Threads state 3335 _thread_list = NULL; 3336 _number_of_threads = 0; 3337 _number_of_non_daemon_threads = 0; 3338 3339 // Initialize global data structures and create system classes in heap 3340 vm_init_globals(); 3341 3342 // Attach the main thread to this os thread 3343 JavaThread* main_thread = new JavaThread(); 3344 main_thread->set_thread_state(_thread_in_vm); 3345 // must do this before set_active_handles and initialize_thread_local_storage 3346 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3347 // change the stack size recorded here to one based on the java thread 3348 // stacksize. This adjusted size is what is used to figure the placement 3349 // of the guard pages. 3350 main_thread->record_stack_base_and_size(); 3351 main_thread->initialize_thread_local_storage(); 3352 3353 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3354 3355 if (!main_thread->set_as_starting_thread()) { 3356 vm_shutdown_during_initialization( 3357 "Failed necessary internal allocation. Out of swap space"); 3358 delete main_thread; 3359 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3360 return JNI_ENOMEM; 3361 } 3362 3363 // Enable guard page *after* os::create_main_thread(), otherwise it would 3364 // crash Linux VM, see notes in os_linux.cpp. 3365 main_thread->create_stack_guard_pages(); 3366 3367 // Initialize Java-Level synchronization subsystem 3368 ObjectMonitor::Initialize(); 3369 3370 // Initialize global modules 3371 jint status = init_globals(); 3372 if (status != JNI_OK) { 3373 delete main_thread; 3374 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3375 return status; 3376 } 3377 3378 // Should be done after the heap is fully created 3379 main_thread->cache_global_variables(); 3380 3381 HandleMark hm; 3382 3383 { MutexLocker mu(Threads_lock); 3384 Threads::add(main_thread); 3385 } 3386 3387 // Any JVMTI raw monitors entered in onload will transition into 3388 // real raw monitor. VM is setup enough here for raw monitor enter. 3389 JvmtiExport::transition_pending_onload_raw_monitors(); 3390 3391 // Create the VMThread 3392 { TraceTime timer("Start VMThread", TraceStartupTime); 3393 VMThread::create(); 3394 Thread* vmthread = VMThread::vm_thread(); 3395 3396 if (!os::create_thread(vmthread, os::vm_thread)) { 3397 vm_exit_during_initialization("Cannot create VM thread. " 3398 "Out of system resources."); 3399 } 3400 3401 // Wait for the VM thread to become ready, and VMThread::run to initialize 3402 // Monitors can have spurious returns, must always check another state flag 3403 { 3404 MutexLocker ml(Notify_lock); 3405 os::start_thread(vmthread); 3406 while (vmthread->active_handles() == NULL) { 3407 Notify_lock->wait(); 3408 } 3409 } 3410 } 3411 3412 assert(Universe::is_fully_initialized(), "not initialized"); 3413 if (VerifyDuringStartup) { 3414 // Make sure we're starting with a clean slate. 3415 VM_Verify verify_op; 3416 VMThread::execute(&verify_op); 3417 } 3418 3419 Thread* THREAD = Thread::current(); 3420 3421 // At this point, the Universe is initialized, but we have not executed 3422 // any byte code. Now is a good time (the only time) to dump out the 3423 // internal state of the JVM for sharing. 3424 if (DumpSharedSpaces) { 3425 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3426 ShouldNotReachHere(); 3427 } 3428 3429 // Always call even when there are not JVMTI environments yet, since environments 3430 // may be attached late and JVMTI must track phases of VM execution 3431 JvmtiExport::enter_start_phase(); 3432 3433 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3434 JvmtiExport::post_vm_start(); 3435 3436 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3437 3438 // We need this for ClassDataSharing - the initial vm.info property is set 3439 // with the default value of CDS "sharing" which may be reset through 3440 // command line options. 3441 reset_vm_info_property(CHECK_JNI_ERR); 3442 3443 quicken_jni_functions(); 3444 3445 // Must be run after init_ft which initializes ft_enabled 3446 if (TRACE_INITIALIZE() != JNI_OK) { 3447 vm_exit_during_initialization("Failed to initialize tracing backend"); 3448 } 3449 3450 // Set flag that basic initialization has completed. Used by exceptions and various 3451 // debug stuff, that does not work until all basic classes have been initialized. 3452 set_init_completed(); 3453 3454 Metaspace::post_initialize(); 3455 3456 HOTSPOT_VM_INIT_END(); 3457 3458 // record VM initialization completion time 3459#if INCLUDE_MANAGEMENT 3460 Management::record_vm_init_completed(); 3461#endif // INCLUDE_MANAGEMENT 3462 3463 // Compute system loader. Note that this has to occur after set_init_completed, since 3464 // valid exceptions may be thrown in the process. 3465 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3466 // set_init_completed has just been called, causing exceptions not to be shortcut 3467 // anymore. We call vm_exit_during_initialization directly instead. 3468 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR); 3469 3470#if INCLUDE_ALL_GCS 3471 // Support for ConcurrentMarkSweep. This should be cleaned up 3472 // and better encapsulated. The ugly nested if test would go away 3473 // once things are properly refactored. XXX YSR 3474 if (UseConcMarkSweepGC || UseG1GC) { 3475 if (UseConcMarkSweepGC) { 3476 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3477 } else { 3478 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR); 3479 } 3480 } 3481#endif // INCLUDE_ALL_GCS 3482 3483 // Always call even when there are not JVMTI environments yet, since environments 3484 // may be attached late and JVMTI must track phases of VM execution 3485 JvmtiExport::enter_live_phase(); 3486 3487 // Signal Dispatcher needs to be started before VMInit event is posted 3488 os::signal_init(); 3489 3490 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3491 if (!DisableAttachMechanism) { 3492 AttachListener::vm_start(); 3493 if (StartAttachListener || AttachListener::init_at_startup()) { 3494 AttachListener::init(); 3495 } 3496 } 3497 3498 // Launch -Xrun agents 3499 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3500 // back-end can launch with -Xdebug -Xrunjdwp. 3501 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3502 create_vm_init_libraries(); 3503 } 3504 3505 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3506 JvmtiExport::post_vm_initialized(); 3507 3508 if (TRACE_START() != JNI_OK) { 3509 vm_exit_during_initialization("Failed to start tracing backend."); 3510 } 3511 3512 if (CleanChunkPoolAsync) { 3513 Chunk::start_chunk_pool_cleaner_task(); 3514 } 3515 3516 // initialize compiler(s) 3517#if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) 3518 CompileBroker::compilation_init(); 3519#endif 3520 3521 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3522 // It is done after compilers are initialized, because otherwise compilations of 3523 // signature polymorphic MH intrinsics can be missed 3524 // (see SystemDictionary::find_method_handle_intrinsic). 3525 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3526 3527#if INCLUDE_MANAGEMENT 3528 Management::initialize(THREAD); 3529 3530 if (HAS_PENDING_EXCEPTION) { 3531 // management agent fails to start possibly due to 3532 // configuration problem and is responsible for printing 3533 // stack trace if appropriate. Simply exit VM. 3534 vm_exit(1); 3535 } 3536#endif // INCLUDE_MANAGEMENT 3537 3538 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3539 if (MemProfiling) MemProfiler::engage(); 3540 StatSampler::engage(); 3541 if (CheckJNICalls) JniPeriodicChecker::engage(); 3542 3543 BiasedLocking::init(); 3544 3545#if INCLUDE_RTM_OPT 3546 RTMLockingCounters::init(); 3547#endif 3548 3549 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3550 call_postVMInitHook(THREAD); 3551 // The Java side of PostVMInitHook.run must deal with all 3552 // exceptions and provide means of diagnosis. 3553 if (HAS_PENDING_EXCEPTION) { 3554 CLEAR_PENDING_EXCEPTION; 3555 } 3556 } 3557 3558 { 3559 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 3560 // Make sure the watcher thread can be started by WatcherThread::start() 3561 // or by dynamic enrollment. 3562 WatcherThread::make_startable(); 3563 // Start up the WatcherThread if there are any periodic tasks 3564 // NOTE: All PeriodicTasks should be registered by now. If they 3565 // aren't, late joiners might appear to start slowly (we might 3566 // take a while to process their first tick). 3567 if (PeriodicTask::num_tasks() > 0) { 3568 WatcherThread::start(); 3569 } 3570 } 3571 3572 create_vm_timer.end(); 3573#ifdef ASSERT 3574 _vm_complete = true; 3575#endif 3576 return JNI_OK; 3577} 3578 3579// type for the Agent_OnLoad and JVM_OnLoad entry points 3580extern "C" { 3581 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3582} 3583// Find a command line agent library and return its entry point for 3584// -agentlib: -agentpath: -Xrun 3585// num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3586static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3587 const char *on_load_symbols[], 3588 size_t num_symbol_entries) { 3589 OnLoadEntry_t on_load_entry = NULL; 3590 void *library = NULL; 3591 3592 if (!agent->valid()) { 3593 char buffer[JVM_MAXPATHLEN]; 3594 char ebuf[1024] = ""; 3595 const char *name = agent->name(); 3596 const char *msg = "Could not find agent library "; 3597 3598 // First check to see if agent is statically linked into executable 3599 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3600 library = agent->os_lib(); 3601 } else if (agent->is_absolute_path()) { 3602 library = os::dll_load(name, ebuf, sizeof ebuf); 3603 if (library == NULL) { 3604 const char *sub_msg = " in absolute path, with error: "; 3605 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3606 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3607 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3608 // If we can't find the agent, exit. 3609 vm_exit_during_initialization(buf, NULL); 3610 FREE_C_HEAP_ARRAY(char, buf); 3611 } 3612 } else { 3613 // Try to load the agent from the standard dll directory 3614 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3615 name)) { 3616 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3617 } 3618 if (library == NULL) { // Try the local directory 3619 char ns[1] = {0}; 3620 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3621 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3622 } 3623 if (library == NULL) { 3624 const char *sub_msg = " on the library path, with error: "; 3625 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3626 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3627 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3628 // If we can't find the agent, exit. 3629 vm_exit_during_initialization(buf, NULL); 3630 FREE_C_HEAP_ARRAY(char, buf); 3631 } 3632 } 3633 } 3634 agent->set_os_lib(library); 3635 agent->set_valid(); 3636 } 3637 3638 // Find the OnLoad function. 3639 on_load_entry = 3640 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3641 false, 3642 on_load_symbols, 3643 num_symbol_entries)); 3644 return on_load_entry; 3645} 3646 3647// Find the JVM_OnLoad entry point 3648static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3649 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3650 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3651} 3652 3653// Find the Agent_OnLoad entry point 3654static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3655 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3656 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3657} 3658 3659// For backwards compatibility with -Xrun 3660// Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3661// treated like -agentpath: 3662// Must be called before agent libraries are created 3663void Threads::convert_vm_init_libraries_to_agents() { 3664 AgentLibrary* agent; 3665 AgentLibrary* next; 3666 3667 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3668 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3669 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3670 3671 // If there is an JVM_OnLoad function it will get called later, 3672 // otherwise see if there is an Agent_OnLoad 3673 if (on_load_entry == NULL) { 3674 on_load_entry = lookup_agent_on_load(agent); 3675 if (on_load_entry != NULL) { 3676 // switch it to the agent list -- so that Agent_OnLoad will be called, 3677 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3678 Arguments::convert_library_to_agent(agent); 3679 } else { 3680 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3681 } 3682 } 3683 } 3684} 3685 3686// Create agents for -agentlib: -agentpath: and converted -Xrun 3687// Invokes Agent_OnLoad 3688// Called very early -- before JavaThreads exist 3689void Threads::create_vm_init_agents() { 3690 extern struct JavaVM_ main_vm; 3691 AgentLibrary* agent; 3692 3693 JvmtiExport::enter_onload_phase(); 3694 3695 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3696 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3697 3698 if (on_load_entry != NULL) { 3699 // Invoke the Agent_OnLoad function 3700 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3701 if (err != JNI_OK) { 3702 vm_exit_during_initialization("agent library failed to init", agent->name()); 3703 } 3704 } else { 3705 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3706 } 3707 } 3708 JvmtiExport::enter_primordial_phase(); 3709} 3710 3711extern "C" { 3712 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3713} 3714 3715void Threads::shutdown_vm_agents() { 3716 // Send any Agent_OnUnload notifications 3717 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3718 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3719 extern struct JavaVM_ main_vm; 3720 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3721 3722 // Find the Agent_OnUnload function. 3723 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3724 os::find_agent_function(agent, 3725 false, 3726 on_unload_symbols, 3727 num_symbol_entries)); 3728 3729 // Invoke the Agent_OnUnload function 3730 if (unload_entry != NULL) { 3731 JavaThread* thread = JavaThread::current(); 3732 ThreadToNativeFromVM ttn(thread); 3733 HandleMark hm(thread); 3734 (*unload_entry)(&main_vm); 3735 } 3736 } 3737} 3738 3739// Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3740// Invokes JVM_OnLoad 3741void Threads::create_vm_init_libraries() { 3742 extern struct JavaVM_ main_vm; 3743 AgentLibrary* agent; 3744 3745 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3746 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3747 3748 if (on_load_entry != NULL) { 3749 // Invoke the JVM_OnLoad function 3750 JavaThread* thread = JavaThread::current(); 3751 ThreadToNativeFromVM ttn(thread); 3752 HandleMark hm(thread); 3753 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3754 if (err != JNI_OK) { 3755 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3756 } 3757 } else { 3758 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3759 } 3760 } 3761} 3762 3763JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 3764 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 3765 3766 JavaThread* java_thread = NULL; 3767 // Sequential search for now. Need to do better optimization later. 3768 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 3769 oop tobj = thread->threadObj(); 3770 if (!thread->is_exiting() && 3771 tobj != NULL && 3772 java_tid == java_lang_Thread::thread_id(tobj)) { 3773 java_thread = thread; 3774 break; 3775 } 3776 } 3777 return java_thread; 3778} 3779 3780 3781// Last thread running calls java.lang.Shutdown.shutdown() 3782void JavaThread::invoke_shutdown_hooks() { 3783 HandleMark hm(this); 3784 3785 // We could get here with a pending exception, if so clear it now. 3786 if (this->has_pending_exception()) { 3787 this->clear_pending_exception(); 3788 } 3789 3790 EXCEPTION_MARK; 3791 Klass* k = 3792 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3793 THREAD); 3794 if (k != NULL) { 3795 // SystemDictionary::resolve_or_null will return null if there was 3796 // an exception. If we cannot load the Shutdown class, just don't 3797 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3798 // and finalizers (if runFinalizersOnExit is set) won't be run. 3799 // Note that if a shutdown hook was registered or runFinalizersOnExit 3800 // was called, the Shutdown class would have already been loaded 3801 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3802 instanceKlassHandle shutdown_klass (THREAD, k); 3803 JavaValue result(T_VOID); 3804 JavaCalls::call_static(&result, 3805 shutdown_klass, 3806 vmSymbols::shutdown_method_name(), 3807 vmSymbols::void_method_signature(), 3808 THREAD); 3809 } 3810 CLEAR_PENDING_EXCEPTION; 3811} 3812 3813// Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3814// the program falls off the end of main(). Another VM exit path is through 3815// vm_exit() when the program calls System.exit() to return a value or when 3816// there is a serious error in VM. The two shutdown paths are not exactly 3817// the same, but they share Shutdown.shutdown() at Java level and before_exit() 3818// and VM_Exit op at VM level. 3819// 3820// Shutdown sequence: 3821// + Shutdown native memory tracking if it is on 3822// + Wait until we are the last non-daemon thread to execute 3823// <-- every thing is still working at this moment --> 3824// + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3825// shutdown hooks, run finalizers if finalization-on-exit 3826// + Call before_exit(), prepare for VM exit 3827// > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3828// currently the only user of this mechanism is File.deleteOnExit()) 3829// > stop flat profiler, StatSampler, watcher thread, CMS threads, 3830// post thread end and vm death events to JVMTI, 3831// stop signal thread 3832// + Call JavaThread::exit(), it will: 3833// > release JNI handle blocks, remove stack guard pages 3834// > remove this thread from Threads list 3835// <-- no more Java code from this thread after this point --> 3836// + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3837// the compiler threads at safepoint 3838// <-- do not use anything that could get blocked by Safepoint --> 3839// + Disable tracing at JNI/JVM barriers 3840// + Set _vm_exited flag for threads that are still running native code 3841// + Delete this thread 3842// + Call exit_globals() 3843// > deletes tty 3844// > deletes PerfMemory resources 3845// + Return to caller 3846 3847bool Threads::destroy_vm() { 3848 JavaThread* thread = JavaThread::current(); 3849 3850#ifdef ASSERT 3851 _vm_complete = false; 3852#endif 3853 // Wait until we are the last non-daemon thread to execute 3854 { MutexLocker nu(Threads_lock); 3855 while (Threads::number_of_non_daemon_threads() > 1) 3856 // This wait should make safepoint checks, wait without a timeout, 3857 // and wait as a suspend-equivalent condition. 3858 // 3859 // Note: If the FlatProfiler is running and this thread is waiting 3860 // for another non-daemon thread to finish, then the FlatProfiler 3861 // is waiting for the external suspend request on this thread to 3862 // complete. wait_for_ext_suspend_completion() will eventually 3863 // timeout, but that takes time. Making this wait a suspend- 3864 // equivalent condition solves that timeout problem. 3865 // 3866 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3867 Mutex::_as_suspend_equivalent_flag); 3868 } 3869 3870 // Hang forever on exit if we are reporting an error. 3871 if (ShowMessageBoxOnError && is_error_reported()) { 3872 os::infinite_sleep(); 3873 } 3874 os::wait_for_keypress_at_exit(); 3875 3876 // run Java level shutdown hooks 3877 thread->invoke_shutdown_hooks(); 3878 3879 before_exit(thread); 3880 3881 thread->exit(true); 3882 3883 // Stop VM thread. 3884 { 3885 // 4945125 The vm thread comes to a safepoint during exit. 3886 // GC vm_operations can get caught at the safepoint, and the 3887 // heap is unparseable if they are caught. Grab the Heap_lock 3888 // to prevent this. The GC vm_operations will not be able to 3889 // queue until after the vm thread is dead. After this point, 3890 // we'll never emerge out of the safepoint before the VM exits. 3891 3892 MutexLocker ml(Heap_lock); 3893 3894 VMThread::wait_for_vm_thread_exit(); 3895 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3896 VMThread::destroy(); 3897 } 3898 3899 // clean up ideal graph printers 3900#if defined(COMPILER2) && !defined(PRODUCT) 3901 IdealGraphPrinter::clean_up(); 3902#endif 3903 3904 // Now, all Java threads are gone except daemon threads. Daemon threads 3905 // running Java code or in VM are stopped by the Safepoint. However, 3906 // daemon threads executing native code are still running. But they 3907 // will be stopped at native=>Java/VM barriers. Note that we can't 3908 // simply kill or suspend them, as it is inherently deadlock-prone. 3909 3910#ifndef PRODUCT 3911 // disable function tracing at JNI/JVM barriers 3912 TraceJNICalls = false; 3913 TraceJVMCalls = false; 3914 TraceRuntimeCalls = false; 3915#endif 3916 3917 VM_Exit::set_vm_exited(); 3918 3919 notify_vm_shutdown(); 3920 3921 delete thread; 3922 3923 // exit_globals() will delete tty 3924 exit_globals(); 3925 3926 return true; 3927} 3928 3929 3930jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3931 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3932 return is_supported_jni_version(version); 3933} 3934 3935 3936jboolean Threads::is_supported_jni_version(jint version) { 3937 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3938 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3939 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3940 if (version == JNI_VERSION_1_8) return JNI_TRUE; 3941 return JNI_FALSE; 3942} 3943 3944 3945void Threads::add(JavaThread* p, bool force_daemon) { 3946 // The threads lock must be owned at this point 3947 assert_locked_or_safepoint(Threads_lock); 3948 3949 // See the comment for this method in thread.hpp for its purpose and 3950 // why it is called here. 3951 p->initialize_queues(); 3952 p->set_next(_thread_list); 3953 _thread_list = p; 3954 _number_of_threads++; 3955 oop threadObj = p->threadObj(); 3956 bool daemon = true; 3957 // Bootstrapping problem: threadObj can be null for initial 3958 // JavaThread (or for threads attached via JNI) 3959 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3960 _number_of_non_daemon_threads++; 3961 daemon = false; 3962 } 3963 3964 ThreadService::add_thread(p, daemon); 3965 3966 // Possible GC point. 3967 Events::log(p, "Thread added: " INTPTR_FORMAT, p); 3968} 3969 3970void Threads::remove(JavaThread* p) { 3971 // Extra scope needed for Thread_lock, so we can check 3972 // that we do not remove thread without safepoint code notice 3973 { MutexLocker ml(Threads_lock); 3974 3975 assert(includes(p), "p must be present"); 3976 3977 JavaThread* current = _thread_list; 3978 JavaThread* prev = NULL; 3979 3980 while (current != p) { 3981 prev = current; 3982 current = current->next(); 3983 } 3984 3985 if (prev) { 3986 prev->set_next(current->next()); 3987 } else { 3988 _thread_list = p->next(); 3989 } 3990 _number_of_threads--; 3991 oop threadObj = p->threadObj(); 3992 bool daemon = true; 3993 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 3994 _number_of_non_daemon_threads--; 3995 daemon = false; 3996 3997 // Only one thread left, do a notify on the Threads_lock so a thread waiting 3998 // on destroy_vm will wake up. 3999 if (number_of_non_daemon_threads() == 1) { 4000 Threads_lock->notify_all(); 4001 } 4002 } 4003 ThreadService::remove_thread(p, daemon); 4004 4005 // Make sure that safepoint code disregard this thread. This is needed since 4006 // the thread might mess around with locks after this point. This can cause it 4007 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4008 // of this thread since it is removed from the queue. 4009 p->set_terminated_value(); 4010 } // unlock Threads_lock 4011 4012 // Since Events::log uses a lock, we grab it outside the Threads_lock 4013 Events::log(p, "Thread exited: " INTPTR_FORMAT, p); 4014} 4015 4016// Threads_lock must be held when this is called (or must be called during a safepoint) 4017bool Threads::includes(JavaThread* p) { 4018 assert(Threads_lock->is_locked(), "sanity check"); 4019 ALL_JAVA_THREADS(q) { 4020 if (q == p) { 4021 return true; 4022 } 4023 } 4024 return false; 4025} 4026 4027// Operations on the Threads list for GC. These are not explicitly locked, 4028// but the garbage collector must provide a safe context for them to run. 4029// In particular, these things should never be called when the Threads_lock 4030// is held by some other thread. (Note: the Safepoint abstraction also 4031// uses the Threads_lock to guarantee this property. It also makes sure that 4032// all threads gets blocked when exiting or starting). 4033 4034void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4035 ALL_JAVA_THREADS(p) { 4036 p->oops_do(f, cld_f, cf); 4037 } 4038 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4039} 4040 4041void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4042 // Introduce a mechanism allowing parallel threads to claim threads as 4043 // root groups. Overhead should be small enough to use all the time, 4044 // even in sequential code. 4045 SharedHeap* sh = SharedHeap::heap(); 4046 // Cannot yet substitute active_workers for n_par_threads 4047 // because of G1CollectedHeap::verify() use of 4048 // SharedHeap::process_roots(). n_par_threads == 0 will 4049 // turn off parallelism in process_roots while active_workers 4050 // is being used for parallelism elsewhere. 4051 bool is_par = sh->n_par_threads() > 0; 4052 assert(!is_par || 4053 (SharedHeap::heap()->n_par_threads() == 4054 SharedHeap::heap()->workers()->active_workers()), "Mismatch"); 4055 int cp = SharedHeap::heap()->strong_roots_parity(); 4056 ALL_JAVA_THREADS(p) { 4057 if (p->claim_oops_do(is_par, cp)) { 4058 p->oops_do(f, cld_f, cf); 4059 } 4060 } 4061 VMThread* vmt = VMThread::vm_thread(); 4062 if (vmt->claim_oops_do(is_par, cp)) { 4063 vmt->oops_do(f, cld_f, cf); 4064 } 4065} 4066 4067#if INCLUDE_ALL_GCS 4068// Used by ParallelScavenge 4069void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4070 ALL_JAVA_THREADS(p) { 4071 q->enqueue(new ThreadRootsTask(p)); 4072 } 4073 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4074} 4075 4076// Used by Parallel Old 4077void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4078 ALL_JAVA_THREADS(p) { 4079 q->enqueue(new ThreadRootsMarkingTask(p)); 4080 } 4081 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4082} 4083#endif // INCLUDE_ALL_GCS 4084 4085void Threads::nmethods_do(CodeBlobClosure* cf) { 4086 ALL_JAVA_THREADS(p) { 4087 p->nmethods_do(cf); 4088 } 4089 VMThread::vm_thread()->nmethods_do(cf); 4090} 4091 4092void Threads::metadata_do(void f(Metadata*)) { 4093 ALL_JAVA_THREADS(p) { 4094 p->metadata_do(f); 4095 } 4096} 4097 4098void Threads::deoptimized_wrt_marked_nmethods() { 4099 ALL_JAVA_THREADS(p) { 4100 p->deoptimized_wrt_marked_nmethods(); 4101 } 4102} 4103 4104 4105// Get count Java threads that are waiting to enter the specified monitor. 4106GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4107 address monitor, 4108 bool doLock) { 4109 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4110 "must grab Threads_lock or be at safepoint"); 4111 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4112 4113 int i = 0; 4114 { 4115 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4116 ALL_JAVA_THREADS(p) { 4117 if (p->is_Compiler_thread()) continue; 4118 4119 address pending = (address)p->current_pending_monitor(); 4120 if (pending == monitor) { // found a match 4121 if (i < count) result->append(p); // save the first count matches 4122 i++; 4123 } 4124 } 4125 } 4126 return result; 4127} 4128 4129 4130JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4131 bool doLock) { 4132 assert(doLock || 4133 Threads_lock->owned_by_self() || 4134 SafepointSynchronize::is_at_safepoint(), 4135 "must grab Threads_lock or be at safepoint"); 4136 4137 // NULL owner means not locked so we can skip the search 4138 if (owner == NULL) return NULL; 4139 4140 { 4141 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4142 ALL_JAVA_THREADS(p) { 4143 // first, see if owner is the address of a Java thread 4144 if (owner == (address)p) return p; 4145 } 4146 } 4147 // Cannot assert on lack of success here since this function may be 4148 // used by code that is trying to report useful problem information 4149 // like deadlock detection. 4150 if (UseHeavyMonitors) return NULL; 4151 4152 // If we didn't find a matching Java thread and we didn't force use of 4153 // heavyweight monitors, then the owner is the stack address of the 4154 // Lock Word in the owning Java thread's stack. 4155 // 4156 JavaThread* the_owner = NULL; 4157 { 4158 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4159 ALL_JAVA_THREADS(q) { 4160 if (q->is_lock_owned(owner)) { 4161 the_owner = q; 4162 break; 4163 } 4164 } 4165 } 4166 // cannot assert on lack of success here; see above comment 4167 return the_owner; 4168} 4169 4170// Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4171void Threads::print_on(outputStream* st, bool print_stacks, 4172 bool internal_format, bool print_concurrent_locks) { 4173 char buf[32]; 4174 st->print_cr("%s", os::local_time_string(buf, sizeof(buf))); 4175 4176 st->print_cr("Full thread dump %s (%s %s):", 4177 Abstract_VM_Version::vm_name(), 4178 Abstract_VM_Version::vm_release(), 4179 Abstract_VM_Version::vm_info_string()); 4180 st->cr(); 4181 4182#if INCLUDE_ALL_GCS 4183 // Dump concurrent locks 4184 ConcurrentLocksDump concurrent_locks; 4185 if (print_concurrent_locks) { 4186 concurrent_locks.dump_at_safepoint(); 4187 } 4188#endif // INCLUDE_ALL_GCS 4189 4190 ALL_JAVA_THREADS(p) { 4191 ResourceMark rm; 4192 p->print_on(st); 4193 if (print_stacks) { 4194 if (internal_format) { 4195 p->trace_stack(); 4196 } else { 4197 p->print_stack_on(st); 4198 } 4199 } 4200 st->cr(); 4201#if INCLUDE_ALL_GCS 4202 if (print_concurrent_locks) { 4203 concurrent_locks.print_locks_on(p, st); 4204 } 4205#endif // INCLUDE_ALL_GCS 4206 } 4207 4208 VMThread::vm_thread()->print_on(st); 4209 st->cr(); 4210 Universe::heap()->print_gc_threads_on(st); 4211 WatcherThread* wt = WatcherThread::watcher_thread(); 4212 if (wt != NULL) { 4213 wt->print_on(st); 4214 st->cr(); 4215 } 4216 CompileBroker::print_compiler_threads_on(st); 4217 st->flush(); 4218} 4219 4220// Threads::print_on_error() is called by fatal error handler. It's possible 4221// that VM is not at safepoint and/or current thread is inside signal handler. 4222// Don't print stack trace, as the stack may not be walkable. Don't allocate 4223// memory (even in resource area), it might deadlock the error handler. 4224void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4225 int buflen) { 4226 bool found_current = false; 4227 st->print_cr("Java Threads: ( => current thread )"); 4228 ALL_JAVA_THREADS(thread) { 4229 bool is_current = (current == thread); 4230 found_current = found_current || is_current; 4231 4232 st->print("%s", is_current ? "=>" : " "); 4233 4234 st->print(PTR_FORMAT, thread); 4235 st->print(" "); 4236 thread->print_on_error(st, buf, buflen); 4237 st->cr(); 4238 } 4239 st->cr(); 4240 4241 st->print_cr("Other Threads:"); 4242 if (VMThread::vm_thread()) { 4243 bool is_current = (current == VMThread::vm_thread()); 4244 found_current = found_current || is_current; 4245 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4246 4247 st->print(PTR_FORMAT, VMThread::vm_thread()); 4248 st->print(" "); 4249 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4250 st->cr(); 4251 } 4252 WatcherThread* wt = WatcherThread::watcher_thread(); 4253 if (wt != NULL) { 4254 bool is_current = (current == wt); 4255 found_current = found_current || is_current; 4256 st->print("%s", is_current ? "=>" : " "); 4257 4258 st->print(PTR_FORMAT, wt); 4259 st->print(" "); 4260 wt->print_on_error(st, buf, buflen); 4261 st->cr(); 4262 } 4263 if (!found_current) { 4264 st->cr(); 4265 st->print("=>" PTR_FORMAT " (exited) ", current); 4266 current->print_on_error(st, buf, buflen); 4267 st->cr(); 4268 } 4269} 4270 4271// Internal SpinLock and Mutex 4272// Based on ParkEvent 4273 4274// Ad-hoc mutual exclusion primitives: SpinLock and Mux 4275// 4276// We employ SpinLocks _only for low-contention, fixed-length 4277// short-duration critical sections where we're concerned 4278// about native mutex_t or HotSpot Mutex:: latency. 4279// The mux construct provides a spin-then-block mutual exclusion 4280// mechanism. 4281// 4282// Testing has shown that contention on the ListLock guarding gFreeList 4283// is common. If we implement ListLock as a simple SpinLock it's common 4284// for the JVM to devolve to yielding with little progress. This is true 4285// despite the fact that the critical sections protected by ListLock are 4286// extremely short. 4287// 4288// TODO-FIXME: ListLock should be of type SpinLock. 4289// We should make this a 1st-class type, integrated into the lock 4290// hierarchy as leaf-locks. Critically, the SpinLock structure 4291// should have sufficient padding to avoid false-sharing and excessive 4292// cache-coherency traffic. 4293 4294 4295typedef volatile int SpinLockT; 4296 4297void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4298 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4299 return; // normal fast-path return 4300 } 4301 4302 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4303 TEVENT(SpinAcquire - ctx); 4304 int ctr = 0; 4305 int Yields = 0; 4306 for (;;) { 4307 while (*adr != 0) { 4308 ++ctr; 4309 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4310 if (Yields > 5) { 4311 os::naked_short_sleep(1); 4312 } else { 4313 os::naked_yield(); 4314 ++Yields; 4315 } 4316 } else { 4317 SpinPause(); 4318 } 4319 } 4320 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4321 } 4322} 4323 4324void Thread::SpinRelease(volatile int * adr) { 4325 assert(*adr != 0, "invariant"); 4326 OrderAccess::fence(); // guarantee at least release consistency. 4327 // Roach-motel semantics. 4328 // It's safe if subsequent LDs and STs float "up" into the critical section, 4329 // but prior LDs and STs within the critical section can't be allowed 4330 // to reorder or float past the ST that releases the lock. 4331 // Loads and stores in the critical section - which appear in program 4332 // order before the store that releases the lock - must also appear 4333 // before the store that releases the lock in memory visibility order. 4334 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4335 // the ST of 0 into the lock-word which releases the lock, so fence 4336 // more than covers this on all platforms. 4337 *adr = 0; 4338} 4339 4340// muxAcquire and muxRelease: 4341// 4342// * muxAcquire and muxRelease support a single-word lock-word construct. 4343// The LSB of the word is set IFF the lock is held. 4344// The remainder of the word points to the head of a singly-linked list 4345// of threads blocked on the lock. 4346// 4347// * The current implementation of muxAcquire-muxRelease uses its own 4348// dedicated Thread._MuxEvent instance. If we're interested in 4349// minimizing the peak number of extant ParkEvent instances then 4350// we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4351// as certain invariants were satisfied. Specifically, care would need 4352// to be taken with regards to consuming unpark() "permits". 4353// A safe rule of thumb is that a thread would never call muxAcquire() 4354// if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4355// park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4356// consume an unpark() permit intended for monitorenter, for instance. 4357// One way around this would be to widen the restricted-range semaphore 4358// implemented in park(). Another alternative would be to provide 4359// multiple instances of the PlatformEvent() for each thread. One 4360// instance would be dedicated to muxAcquire-muxRelease, for instance. 4361// 4362// * Usage: 4363// -- Only as leaf locks 4364// -- for short-term locking only as muxAcquire does not perform 4365// thread state transitions. 4366// 4367// Alternatives: 4368// * We could implement muxAcquire and muxRelease with MCS or CLH locks 4369// but with parking or spin-then-park instead of pure spinning. 4370// * Use Taura-Oyama-Yonenzawa locks. 4371// * It's possible to construct a 1-0 lock if we encode the lockword as 4372// (List,LockByte). Acquire will CAS the full lockword while Release 4373// will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4374// acquiring threads use timers (ParkTimed) to detect and recover from 4375// the stranding window. Thread/Node structures must be aligned on 256-byte 4376// boundaries by using placement-new. 4377// * Augment MCS with advisory back-link fields maintained with CAS(). 4378// Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4379// The validity of the backlinks must be ratified before we trust the value. 4380// If the backlinks are invalid the exiting thread must back-track through the 4381// the forward links, which are always trustworthy. 4382// * Add a successor indication. The LockWord is currently encoded as 4383// (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4384// to provide the usual futile-wakeup optimization. 4385// See RTStt for details. 4386// * Consider schedctl.sc_nopreempt to cover the critical section. 4387// 4388 4389 4390typedef volatile intptr_t MutexT; // Mux Lock-word 4391enum MuxBits { LOCKBIT = 1 }; 4392 4393void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4394 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4395 if (w == 0) return; 4396 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4397 return; 4398 } 4399 4400 TEVENT(muxAcquire - Contention); 4401 ParkEvent * const Self = Thread::current()->_MuxEvent; 4402 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4403 for (;;) { 4404 int its = (os::is_MP() ? 100 : 0) + 1; 4405 4406 // Optional spin phase: spin-then-park strategy 4407 while (--its >= 0) { 4408 w = *Lock; 4409 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4410 return; 4411 } 4412 } 4413 4414 Self->reset(); 4415 Self->OnList = intptr_t(Lock); 4416 // The following fence() isn't _strictly necessary as the subsequent 4417 // CAS() both serializes execution and ratifies the fetched *Lock value. 4418 OrderAccess::fence(); 4419 for (;;) { 4420 w = *Lock; 4421 if ((w & LOCKBIT) == 0) { 4422 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4423 Self->OnList = 0; // hygiene - allows stronger asserts 4424 return; 4425 } 4426 continue; // Interference -- *Lock changed -- Just retry 4427 } 4428 assert(w & LOCKBIT, "invariant"); 4429 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4430 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4431 } 4432 4433 while (Self->OnList != 0) { 4434 Self->park(); 4435 } 4436 } 4437} 4438 4439void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4440 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4441 if (w == 0) return; 4442 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4443 return; 4444 } 4445 4446 TEVENT(muxAcquire - Contention); 4447 ParkEvent * ReleaseAfter = NULL; 4448 if (ev == NULL) { 4449 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4450 } 4451 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4452 for (;;) { 4453 guarantee(ev->OnList == 0, "invariant"); 4454 int its = (os::is_MP() ? 100 : 0) + 1; 4455 4456 // Optional spin phase: spin-then-park strategy 4457 while (--its >= 0) { 4458 w = *Lock; 4459 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4460 if (ReleaseAfter != NULL) { 4461 ParkEvent::Release(ReleaseAfter); 4462 } 4463 return; 4464 } 4465 } 4466 4467 ev->reset(); 4468 ev->OnList = intptr_t(Lock); 4469 // The following fence() isn't _strictly necessary as the subsequent 4470 // CAS() both serializes execution and ratifies the fetched *Lock value. 4471 OrderAccess::fence(); 4472 for (;;) { 4473 w = *Lock; 4474 if ((w & LOCKBIT) == 0) { 4475 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4476 ev->OnList = 0; 4477 // We call ::Release while holding the outer lock, thus 4478 // artificially lengthening the critical section. 4479 // Consider deferring the ::Release() until the subsequent unlock(), 4480 // after we've dropped the outer lock. 4481 if (ReleaseAfter != NULL) { 4482 ParkEvent::Release(ReleaseAfter); 4483 } 4484 return; 4485 } 4486 continue; // Interference -- *Lock changed -- Just retry 4487 } 4488 assert(w & LOCKBIT, "invariant"); 4489 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4490 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4491 } 4492 4493 while (ev->OnList != 0) { 4494 ev->park(); 4495 } 4496 } 4497} 4498 4499// Release() must extract a successor from the list and then wake that thread. 4500// It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4501// similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4502// Release() would : 4503// (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4504// (B) Extract a successor from the private list "in-hand" 4505// (C) attempt to CAS() the residual back into *Lock over null. 4506// If there were any newly arrived threads and the CAS() would fail. 4507// In that case Release() would detach the RATs, re-merge the list in-hand 4508// with the RATs and repeat as needed. Alternately, Release() might 4509// detach and extract a successor, but then pass the residual list to the wakee. 4510// The wakee would be responsible for reattaching and remerging before it 4511// competed for the lock. 4512// 4513// Both "pop" and DMR are immune from ABA corruption -- there can be 4514// multiple concurrent pushers, but only one popper or detacher. 4515// This implementation pops from the head of the list. This is unfair, 4516// but tends to provide excellent throughput as hot threads remain hot. 4517// (We wake recently run threads first). 4518// 4519// All paths through muxRelease() will execute a CAS. 4520// Release consistency -- We depend on the CAS in muxRelease() to provide full 4521// bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4522// executed within the critical section are complete and globally visible before the 4523// store (CAS) to the lock-word that releases the lock becomes globally visible. 4524void Thread::muxRelease(volatile intptr_t * Lock) { 4525 for (;;) { 4526 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4527 assert(w & LOCKBIT, "invariant"); 4528 if (w == LOCKBIT) return; 4529 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4530 assert(List != NULL, "invariant"); 4531 assert(List->OnList == intptr_t(Lock), "invariant"); 4532 ParkEvent * const nxt = List->ListNext; 4533 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4534 4535 // The following CAS() releases the lock and pops the head element. 4536 // The CAS() also ratifies the previously fetched lock-word value. 4537 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4538 continue; 4539 } 4540 List->OnList = 0; 4541 OrderAccess::fence(); 4542 List->unpark(); 4543 return; 4544 } 4545} 4546 4547 4548void Threads::verify() { 4549 ALL_JAVA_THREADS(p) { 4550 p->verify(); 4551 } 4552 VMThread* thread = VMThread::vm_thread(); 4553 if (thread != NULL) thread->verify(); 4554} 4555