1 /* 2 * Copyright (c) 1997, 2016, 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/moduleEntry.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/codeCacheExtensions.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/gcId.hpp" 37 #include "gc/shared/gcLocker.inline.hpp" 38 #include "gc/shared/referencePendingListLocker.hpp" 39 #include "gc/shared/workgroup.hpp" 40 #include "interpreter/interpreter.hpp" 41 #include "interpreter/linkResolver.hpp" 42 #include "interpreter/oopMapCache.hpp" 43 #include "jvmtifiles/jvmtiEnv.hpp" 44 #include "logging/log.hpp" 45 #include "logging/logConfiguration.hpp" 46 #include "memory/metaspaceShared.hpp" 47 #include "memory/oopFactory.hpp" 48 #include "memory/universe.inline.hpp" 49 #include "oops/instanceKlass.hpp" 50 #include "oops/objArrayOop.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "oops/symbol.hpp" 53 #include "oops/verifyOopClosure.hpp" 54 #include "prims/jvm_misc.hpp" 55 #include "prims/jvmtiExport.hpp" 56 #include "prims/jvmtiThreadState.hpp" 57 #include "prims/privilegedStack.hpp" 58 #include "runtime/arguments.hpp" 59 #include "runtime/atomic.inline.hpp" 60 #include "runtime/biasedLocking.hpp" 61 #include "runtime/commandLineFlagConstraintList.hpp" 62 #include "runtime/commandLineFlagRangeList.hpp" 63 #include "runtime/deoptimization.hpp" 64 #include "runtime/fprofiler.hpp" 65 #include "runtime/frame.inline.hpp" 66 #include "runtime/globals.hpp" 67 #include "runtime/init.hpp" 68 #include "runtime/interfaceSupport.hpp" 69 #include "runtime/java.hpp" 70 #include "runtime/javaCalls.hpp" 71 #include "runtime/jniPeriodicChecker.hpp" 72 #include "runtime/timerTrace.hpp" 73 #include "runtime/memprofiler.hpp" 74 #include "runtime/mutexLocker.hpp" 75 #include "runtime/objectMonitor.hpp" 76 #include "runtime/orderAccess.inline.hpp" 77 #include "runtime/osThread.hpp" 78 #include "runtime/safepoint.hpp" 79 #include "runtime/sharedRuntime.hpp" 80 #include "runtime/statSampler.hpp" 81 #include "runtime/stubRoutines.hpp" 82 #include "runtime/sweeper.hpp" 83 #include "runtime/task.hpp" 84 #include "runtime/thread.inline.hpp" 85 #include "runtime/threadCritical.hpp" 86 #include "runtime/vframe.hpp" 87 #include "runtime/vframeArray.hpp" 88 #include "runtime/vframe_hp.hpp" 89 #include "runtime/vmThread.hpp" 90 #include "runtime/vm_operations.hpp" 91 #include "runtime/vm_version.hpp" 92 #include "services/attachListener.hpp" 93 #include "services/management.hpp" 94 #include "services/memTracker.hpp" 95 #include "services/threadService.hpp" 96 #include "trace/traceMacros.hpp" 97 #include "trace/tracing.hpp" 98 #include "utilities/defaultStream.hpp" 99 #include "utilities/dtrace.hpp" 100 #include "utilities/events.hpp" 101 #include "utilities/macros.hpp" 102 #include "utilities/preserveException.hpp" 103 #if INCLUDE_ALL_GCS 104 #include "gc/cms/concurrentMarkSweepThread.hpp" 105 #include "gc/g1/concurrentMarkThread.inline.hpp" 106 #include "gc/parallel/pcTasks.hpp" 107 #endif // INCLUDE_ALL_GCS 108 #if INCLUDE_JVMCI 109 #include "jvmci/jvmciCompiler.hpp" 110 #include "jvmci/jvmciRuntime.hpp" 111 #endif 112 #ifdef COMPILER1 113 #include "c1/c1_Compiler.hpp" 114 #endif 115 #ifdef COMPILER2 116 #include "opto/c2compiler.hpp" 117 #include "opto/idealGraphPrinter.hpp" 118 #endif 119 #if INCLUDE_RTM_OPT 120 #include "runtime/rtmLocking.hpp" 121 #endif 122 123 // Initialization after module runtime initialization 124 void universe_post_module_init(); // must happen after call_initPhase2 125 126 #ifdef DTRACE_ENABLED 127 128 // Only bother with this argument setup if dtrace is available 129 130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 132 133 #define DTRACE_THREAD_PROBE(probe, javathread) \ 134 { \ 135 ResourceMark rm(this); \ 136 int len = 0; \ 137 const char* name = (javathread)->get_thread_name(); \ 138 len = strlen(name); \ 139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 140 (char *) name, len, \ 141 java_lang_Thread::thread_id((javathread)->threadObj()), \ 142 (uintptr_t) (javathread)->osthread()->thread_id(), \ 143 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 144 } 145 146 #else // ndef DTRACE_ENABLED 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) 149 150 #endif // ndef DTRACE_ENABLED 151 152 #ifndef USE_LIBRARY_BASED_TLS_ONLY 153 // Current thread is maintained as a thread-local variable 154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 155 #endif 156 157 // Class hierarchy 158 // - Thread 159 // - VMThread 160 // - WatcherThread 161 // - ConcurrentMarkSweepThread 162 // - JavaThread 163 // - CompilerThread 164 165 // ======= Thread ======== 166 // Support for forcing alignment of thread objects for biased locking 167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 168 if (UseBiasedLocking) { 169 const int alignment = markOopDesc::biased_lock_alignment; 170 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 172 : AllocateHeap(aligned_size, flags, CURRENT_PC, 173 AllocFailStrategy::RETURN_NULL); 174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 177 "JavaThread alignment code overflowed allocated storage"); 178 if (aligned_addr != real_malloc_addr) { 179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 180 p2i(real_malloc_addr), 181 p2i(aligned_addr)); 182 } 183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 184 return aligned_addr; 185 } else { 186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 188 } 189 } 190 191 void Thread::operator delete(void* p) { 192 if (UseBiasedLocking) { 193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 194 FreeHeap(real_malloc_addr); 195 } else { 196 FreeHeap(p); 197 } 198 } 199 200 201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 202 // JavaThread 203 204 205 Thread::Thread() { 206 // stack and get_thread 207 set_stack_base(NULL); 208 set_stack_size(0); 209 set_self_raw_id(0); 210 set_lgrp_id(-1); 211 DEBUG_ONLY(clear_suspendible_thread();) 212 213 // allocated data structures 214 set_osthread(NULL); 215 set_resource_area(new (mtThread)ResourceArea()); 216 DEBUG_ONLY(_current_resource_mark = NULL;) 217 set_handle_area(new (mtThread) HandleArea(NULL)); 218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 219 set_active_handles(NULL); 220 set_free_handle_block(NULL); 221 set_last_handle_mark(NULL); 222 223 // This initial value ==> never claimed. 224 _oops_do_parity = 0; 225 226 // the handle mark links itself to last_handle_mark 227 new HandleMark(this); 228 229 // plain initialization 230 debug_only(_owned_locks = NULL;) 231 debug_only(_allow_allocation_count = 0;) 232 NOT_PRODUCT(_allow_safepoint_count = 0;) 233 NOT_PRODUCT(_skip_gcalot = false;) 234 _jvmti_env_iteration_count = 0; 235 set_allocated_bytes(0); 236 _vm_operation_started_count = 0; 237 _vm_operation_completed_count = 0; 238 _current_pending_monitor = NULL; 239 _current_pending_monitor_is_from_java = true; 240 _current_waiting_monitor = NULL; 241 _num_nested_signal = 0; 242 omFreeList = NULL; 243 omFreeCount = 0; 244 omFreeProvision = 32; 245 omInUseList = NULL; 246 omInUseCount = 0; 247 248 #ifdef ASSERT 249 _visited_for_critical_count = false; 250 #endif 251 252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 253 Monitor::_safepoint_check_sometimes); 254 _suspend_flags = 0; 255 256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 257 _hashStateX = os::random(); 258 _hashStateY = 842502087; 259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 260 _hashStateW = 273326509; 261 262 _OnTrap = 0; 263 _schedctl = NULL; 264 _Stalled = 0; 265 _TypeTag = 0x2BAD; 266 267 // Many of the following fields are effectively final - immutable 268 // Note that nascent threads can't use the Native Monitor-Mutex 269 // construct until the _MutexEvent is initialized ... 270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 271 // we might instead use a stack of ParkEvents that we could provision on-demand. 272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 273 // and ::Release() 274 _ParkEvent = ParkEvent::Allocate(this); 275 _SleepEvent = ParkEvent::Allocate(this); 276 _MutexEvent = ParkEvent::Allocate(this); 277 _MuxEvent = ParkEvent::Allocate(this); 278 279 #ifdef CHECK_UNHANDLED_OOPS 280 if (CheckUnhandledOops) { 281 _unhandled_oops = new UnhandledOops(this); 282 } 283 #endif // CHECK_UNHANDLED_OOPS 284 #ifdef ASSERT 285 if (UseBiasedLocking) { 286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 287 assert(this == _real_malloc_address || 288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 289 "bug in forced alignment of thread objects"); 290 } 291 #endif // ASSERT 292 } 293 294 void Thread::initialize_thread_current() { 295 #ifndef USE_LIBRARY_BASED_TLS_ONLY 296 assert(_thr_current == NULL, "Thread::current already initialized"); 297 _thr_current = this; 298 #endif 299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 300 ThreadLocalStorage::set_thread(this); 301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 302 } 303 304 void Thread::clear_thread_current() { 305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 306 #ifndef USE_LIBRARY_BASED_TLS_ONLY 307 _thr_current = NULL; 308 #endif 309 ThreadLocalStorage::set_thread(NULL); 310 } 311 312 void Thread::record_stack_base_and_size() { 313 set_stack_base(os::current_stack_base()); 314 set_stack_size(os::current_stack_size()); 315 // CR 7190089: on Solaris, primordial thread's stack is adjusted 316 // in initialize_thread(). Without the adjustment, stack size is 317 // incorrect if stack is set to unlimited (ulimit -s unlimited). 318 // So far, only Solaris has real implementation of initialize_thread(). 319 // 320 // set up any platform-specific state. 321 os::initialize_thread(this); 322 323 // Set stack limits after thread is initialized. 324 if (is_Java_thread()) { 325 ((JavaThread*) this)->set_stack_overflow_limit(); 326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 327 } 328 #if INCLUDE_NMT 329 // record thread's native stack, stack grows downward 330 MemTracker::record_thread_stack(stack_end(), stack_size()); 331 #endif // INCLUDE_NMT 332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 334 os::current_thread_id(), p2i(stack_base() - stack_size()), 335 p2i(stack_base()), stack_size()/1024); 336 } 337 338 339 Thread::~Thread() { 340 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 341 ObjectSynchronizer::omFlush(this); 342 343 EVENT_THREAD_DESTRUCT(this); 344 345 // stack_base can be NULL if the thread is never started or exited before 346 // record_stack_base_and_size called. Although, we would like to ensure 347 // that all started threads do call record_stack_base_and_size(), there is 348 // not proper way to enforce that. 349 #if INCLUDE_NMT 350 if (_stack_base != NULL) { 351 MemTracker::release_thread_stack(stack_end(), stack_size()); 352 #ifdef ASSERT 353 set_stack_base(NULL); 354 #endif 355 } 356 #endif // INCLUDE_NMT 357 358 // deallocate data structures 359 delete resource_area(); 360 // since the handle marks are using the handle area, we have to deallocated the root 361 // handle mark before deallocating the thread's handle area, 362 assert(last_handle_mark() != NULL, "check we have an element"); 363 delete last_handle_mark(); 364 assert(last_handle_mark() == NULL, "check we have reached the end"); 365 366 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 367 // We NULL out the fields for good hygiene. 368 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 369 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 370 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 371 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 372 373 delete handle_area(); 374 delete metadata_handles(); 375 376 // osthread() can be NULL, if creation of thread failed. 377 if (osthread() != NULL) os::free_thread(osthread()); 378 379 delete _SR_lock; 380 381 // clear Thread::current if thread is deleting itself. 382 // Needed to ensure JNI correctly detects non-attached threads. 383 if (this == Thread::current()) { 384 clear_thread_current(); 385 } 386 387 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 388 } 389 390 // NOTE: dummy function for assertion purpose. 391 void Thread::run() { 392 ShouldNotReachHere(); 393 } 394 395 #ifdef ASSERT 396 // Private method to check for dangling thread pointer 397 void check_for_dangling_thread_pointer(Thread *thread) { 398 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 399 "possibility of dangling Thread pointer"); 400 } 401 #endif 402 403 ThreadPriority Thread::get_priority(const Thread* const thread) { 404 ThreadPriority priority; 405 // Can return an error! 406 (void)os::get_priority(thread, priority); 407 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 408 return priority; 409 } 410 411 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 412 debug_only(check_for_dangling_thread_pointer(thread);) 413 // Can return an error! 414 (void)os::set_priority(thread, priority); 415 } 416 417 418 void Thread::start(Thread* thread) { 419 // Start is different from resume in that its safety is guaranteed by context or 420 // being called from a Java method synchronized on the Thread object. 421 if (!DisableStartThread) { 422 if (thread->is_Java_thread()) { 423 // Initialize the thread state to RUNNABLE before starting this thread. 424 // Can not set it after the thread started because we do not know the 425 // exact thread state at that time. It could be in MONITOR_WAIT or 426 // in SLEEPING or some other state. 427 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 428 java_lang_Thread::RUNNABLE); 429 } 430 os::start_thread(thread); 431 } 432 } 433 434 // Enqueue a VM_Operation to do the job for us - sometime later 435 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 436 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 437 VMThread::execute(vm_stop); 438 } 439 440 441 // Check if an external suspend request has completed (or has been 442 // cancelled). Returns true if the thread is externally suspended and 443 // false otherwise. 444 // 445 // The bits parameter returns information about the code path through 446 // the routine. Useful for debugging: 447 // 448 // set in is_ext_suspend_completed(): 449 // 0x00000001 - routine was entered 450 // 0x00000010 - routine return false at end 451 // 0x00000100 - thread exited (return false) 452 // 0x00000200 - suspend request cancelled (return false) 453 // 0x00000400 - thread suspended (return true) 454 // 0x00001000 - thread is in a suspend equivalent state (return true) 455 // 0x00002000 - thread is native and walkable (return true) 456 // 0x00004000 - thread is native_trans and walkable (needed retry) 457 // 458 // set in wait_for_ext_suspend_completion(): 459 // 0x00010000 - routine was entered 460 // 0x00020000 - suspend request cancelled before loop (return false) 461 // 0x00040000 - thread suspended before loop (return true) 462 // 0x00080000 - suspend request cancelled in loop (return false) 463 // 0x00100000 - thread suspended in loop (return true) 464 // 0x00200000 - suspend not completed during retry loop (return false) 465 466 // Helper class for tracing suspend wait debug bits. 467 // 468 // 0x00000100 indicates that the target thread exited before it could 469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 470 // 0x00080000 each indicate a cancelled suspend request so they don't 471 // count as wait failures either. 472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 473 474 class TraceSuspendDebugBits : public StackObj { 475 private: 476 JavaThread * jt; 477 bool is_wait; 478 bool called_by_wait; // meaningful when !is_wait 479 uint32_t * bits; 480 481 public: 482 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 483 uint32_t *_bits) { 484 jt = _jt; 485 is_wait = _is_wait; 486 called_by_wait = _called_by_wait; 487 bits = _bits; 488 } 489 490 ~TraceSuspendDebugBits() { 491 if (!is_wait) { 492 #if 1 493 // By default, don't trace bits for is_ext_suspend_completed() calls. 494 // That trace is very chatty. 495 return; 496 #else 497 if (!called_by_wait) { 498 // If tracing for is_ext_suspend_completed() is enabled, then only 499 // trace calls to it from wait_for_ext_suspend_completion() 500 return; 501 } 502 #endif 503 } 504 505 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 506 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 507 MutexLocker ml(Threads_lock); // needed for get_thread_name() 508 ResourceMark rm; 509 510 tty->print_cr( 511 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 512 jt->get_thread_name(), *bits); 513 514 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 515 } 516 } 517 } 518 }; 519 #undef DEBUG_FALSE_BITS 520 521 522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 523 uint32_t *bits) { 524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 525 526 bool did_trans_retry = false; // only do thread_in_native_trans retry once 527 bool do_trans_retry; // flag to force the retry 528 529 *bits |= 0x00000001; 530 531 do { 532 do_trans_retry = false; 533 534 if (is_exiting()) { 535 // Thread is in the process of exiting. This is always checked 536 // first to reduce the risk of dereferencing a freed JavaThread. 537 *bits |= 0x00000100; 538 return false; 539 } 540 541 if (!is_external_suspend()) { 542 // Suspend request is cancelled. This is always checked before 543 // is_ext_suspended() to reduce the risk of a rogue resume 544 // confusing the thread that made the suspend request. 545 *bits |= 0x00000200; 546 return false; 547 } 548 549 if (is_ext_suspended()) { 550 // thread is suspended 551 *bits |= 0x00000400; 552 return true; 553 } 554 555 // Now that we no longer do hard suspends of threads running 556 // native code, the target thread can be changing thread state 557 // while we are in this routine: 558 // 559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 560 // 561 // We save a copy of the thread state as observed at this moment 562 // and make our decision about suspend completeness based on the 563 // copy. This closes the race where the thread state is seen as 564 // _thread_in_native_trans in the if-thread_blocked check, but is 565 // seen as _thread_blocked in if-thread_in_native_trans check. 566 JavaThreadState save_state = thread_state(); 567 568 if (save_state == _thread_blocked && is_suspend_equivalent()) { 569 // If the thread's state is _thread_blocked and this blocking 570 // condition is known to be equivalent to a suspend, then we can 571 // consider the thread to be externally suspended. This means that 572 // the code that sets _thread_blocked has been modified to do 573 // self-suspension if the blocking condition releases. We also 574 // used to check for CONDVAR_WAIT here, but that is now covered by 575 // the _thread_blocked with self-suspension check. 576 // 577 // Return true since we wouldn't be here unless there was still an 578 // external suspend request. 579 *bits |= 0x00001000; 580 return true; 581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 582 // Threads running native code will self-suspend on native==>VM/Java 583 // transitions. If its stack is walkable (should always be the case 584 // unless this function is called before the actual java_suspend() 585 // call), then the wait is done. 586 *bits |= 0x00002000; 587 return true; 588 } else if (!called_by_wait && !did_trans_retry && 589 save_state == _thread_in_native_trans && 590 frame_anchor()->walkable()) { 591 // The thread is transitioning from thread_in_native to another 592 // thread state. check_safepoint_and_suspend_for_native_trans() 593 // will force the thread to self-suspend. If it hasn't gotten 594 // there yet we may have caught the thread in-between the native 595 // code check above and the self-suspend. Lucky us. If we were 596 // called by wait_for_ext_suspend_completion(), then it 597 // will be doing the retries so we don't have to. 598 // 599 // Since we use the saved thread state in the if-statement above, 600 // there is a chance that the thread has already transitioned to 601 // _thread_blocked by the time we get here. In that case, we will 602 // make a single unnecessary pass through the logic below. This 603 // doesn't hurt anything since we still do the trans retry. 604 605 *bits |= 0x00004000; 606 607 // Once the thread leaves thread_in_native_trans for another 608 // thread state, we break out of this retry loop. We shouldn't 609 // need this flag to prevent us from getting back here, but 610 // sometimes paranoia is good. 611 did_trans_retry = true; 612 613 // We wait for the thread to transition to a more usable state. 614 for (int i = 1; i <= SuspendRetryCount; i++) { 615 // We used to do an "os::yield_all(i)" call here with the intention 616 // that yielding would increase on each retry. However, the parameter 617 // is ignored on Linux which means the yield didn't scale up. Waiting 618 // on the SR_lock below provides a much more predictable scale up for 619 // the delay. It also provides a simple/direct point to check for any 620 // safepoint requests from the VMThread 621 622 // temporarily drops SR_lock while doing wait with safepoint check 623 // (if we're a JavaThread - the WatcherThread can also call this) 624 // and increase delay with each retry 625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 626 627 // check the actual thread state instead of what we saved above 628 if (thread_state() != _thread_in_native_trans) { 629 // the thread has transitioned to another thread state so 630 // try all the checks (except this one) one more time. 631 do_trans_retry = true; 632 break; 633 } 634 } // end retry loop 635 636 637 } 638 } while (do_trans_retry); 639 640 *bits |= 0x00000010; 641 return false; 642 } 643 644 // Wait for an external suspend request to complete (or be cancelled). 645 // Returns true if the thread is externally suspended and false otherwise. 646 // 647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 648 uint32_t *bits) { 649 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 650 false /* !called_by_wait */, bits); 651 652 // local flag copies to minimize SR_lock hold time 653 bool is_suspended; 654 bool pending; 655 uint32_t reset_bits; 656 657 // set a marker so is_ext_suspend_completed() knows we are the caller 658 *bits |= 0x00010000; 659 660 // We use reset_bits to reinitialize the bits value at the top of 661 // each retry loop. This allows the caller to make use of any 662 // unused bits for their own marking purposes. 663 reset_bits = *bits; 664 665 { 666 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 667 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 668 delay, bits); 669 pending = is_external_suspend(); 670 } 671 // must release SR_lock to allow suspension to complete 672 673 if (!pending) { 674 // A cancelled suspend request is the only false return from 675 // is_ext_suspend_completed() that keeps us from entering the 676 // retry loop. 677 *bits |= 0x00020000; 678 return false; 679 } 680 681 if (is_suspended) { 682 *bits |= 0x00040000; 683 return true; 684 } 685 686 for (int i = 1; i <= retries; i++) { 687 *bits = reset_bits; // reinit to only track last retry 688 689 // We used to do an "os::yield_all(i)" call here with the intention 690 // that yielding would increase on each retry. However, the parameter 691 // is ignored on Linux which means the yield didn't scale up. Waiting 692 // on the SR_lock below provides a much more predictable scale up for 693 // the delay. It also provides a simple/direct point to check for any 694 // safepoint requests from the VMThread 695 696 { 697 MutexLocker ml(SR_lock()); 698 // wait with safepoint check (if we're a JavaThread - the WatcherThread 699 // can also call this) and increase delay with each retry 700 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 701 702 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 703 delay, bits); 704 705 // It is possible for the external suspend request to be cancelled 706 // (by a resume) before the actual suspend operation is completed. 707 // Refresh our local copy to see if we still need to wait. 708 pending = is_external_suspend(); 709 } 710 711 if (!pending) { 712 // A cancelled suspend request is the only false return from 713 // is_ext_suspend_completed() that keeps us from staying in the 714 // retry loop. 715 *bits |= 0x00080000; 716 return false; 717 } 718 719 if (is_suspended) { 720 *bits |= 0x00100000; 721 return true; 722 } 723 } // end retry loop 724 725 // thread did not suspend after all our retries 726 *bits |= 0x00200000; 727 return false; 728 } 729 730 #ifndef PRODUCT 731 void JavaThread::record_jump(address target, address instr, const char* file, 732 int line) { 733 734 // This should not need to be atomic as the only way for simultaneous 735 // updates is via interrupts. Even then this should be rare or non-existent 736 // and we don't care that much anyway. 737 738 int index = _jmp_ring_index; 739 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 740 _jmp_ring[index]._target = (intptr_t) target; 741 _jmp_ring[index]._instruction = (intptr_t) instr; 742 _jmp_ring[index]._file = file; 743 _jmp_ring[index]._line = line; 744 } 745 #endif // PRODUCT 746 747 // Called by flat profiler 748 // Callers have already called wait_for_ext_suspend_completion 749 // The assertion for that is currently too complex to put here: 750 bool JavaThread::profile_last_Java_frame(frame* _fr) { 751 bool gotframe = false; 752 // self suspension saves needed state. 753 if (has_last_Java_frame() && _anchor.walkable()) { 754 *_fr = pd_last_frame(); 755 gotframe = true; 756 } 757 return gotframe; 758 } 759 760 void Thread::interrupt(Thread* thread) { 761 debug_only(check_for_dangling_thread_pointer(thread);) 762 os::interrupt(thread); 763 } 764 765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 766 debug_only(check_for_dangling_thread_pointer(thread);) 767 // Note: If clear_interrupted==false, this simply fetches and 768 // returns the value of the field osthread()->interrupted(). 769 return os::is_interrupted(thread, clear_interrupted); 770 } 771 772 773 // GC Support 774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 775 jint thread_parity = _oops_do_parity; 776 if (thread_parity != strong_roots_parity) { 777 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 778 if (res == thread_parity) { 779 return true; 780 } else { 781 guarantee(res == strong_roots_parity, "Or else what?"); 782 return false; 783 } 784 } 785 return false; 786 } 787 788 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 789 active_handles()->oops_do(f); 790 // Do oop for ThreadShadow 791 f->do_oop((oop*)&_pending_exception); 792 handle_area()->oops_do(f); 793 } 794 795 void Thread::nmethods_do(CodeBlobClosure* cf) { 796 // no nmethods in a generic thread... 797 } 798 799 void Thread::metadata_handles_do(void f(Metadata*)) { 800 // Only walk the Handles in Thread. 801 if (metadata_handles() != NULL) { 802 for (int i = 0; i< metadata_handles()->length(); i++) { 803 f(metadata_handles()->at(i)); 804 } 805 } 806 } 807 808 void Thread::print_on(outputStream* st) const { 809 // get_priority assumes osthread initialized 810 if (osthread() != NULL) { 811 int os_prio; 812 if (os::get_native_priority(this, &os_prio) == OS_OK) { 813 st->print("os_prio=%d ", os_prio); 814 } 815 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 816 ext().print_on(st); 817 osthread()->print_on(st); 818 } 819 debug_only(if (WizardMode) print_owned_locks_on(st);) 820 } 821 822 // Thread::print_on_error() is called by fatal error handler. Don't use 823 // any lock or allocate memory. 824 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 825 if (is_VM_thread()) st->print("VMThread"); 826 else if (is_Compiler_thread()) st->print("CompilerThread"); 827 else if (is_Java_thread()) st->print("JavaThread"); 828 else if (is_GC_task_thread()) st->print("GCTaskThread"); 829 else if (is_Watcher_thread()) st->print("WatcherThread"); 830 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 831 else st->print("Thread"); 832 833 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 834 p2i(stack_end()), p2i(stack_base())); 835 836 if (osthread()) { 837 st->print(" [id=%d]", osthread()->thread_id()); 838 } 839 } 840 841 #ifdef ASSERT 842 void Thread::print_owned_locks_on(outputStream* st) const { 843 Monitor *cur = _owned_locks; 844 if (cur == NULL) { 845 st->print(" (no locks) "); 846 } else { 847 st->print_cr(" Locks owned:"); 848 while (cur) { 849 cur->print_on(st); 850 cur = cur->next(); 851 } 852 } 853 } 854 855 static int ref_use_count = 0; 856 857 bool Thread::owns_locks_but_compiled_lock() const { 858 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 859 if (cur != Compile_lock) return true; 860 } 861 return false; 862 } 863 864 865 #endif 866 867 #ifndef PRODUCT 868 869 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 870 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 871 // no threads which allow_vm_block's are held 872 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 873 // Check if current thread is allowed to block at a safepoint 874 if (!(_allow_safepoint_count == 0)) { 875 fatal("Possible safepoint reached by thread that does not allow it"); 876 } 877 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 878 fatal("LEAF method calling lock?"); 879 } 880 881 #ifdef ASSERT 882 if (potential_vm_operation && is_Java_thread() 883 && !Universe::is_bootstrapping()) { 884 // Make sure we do not hold any locks that the VM thread also uses. 885 // This could potentially lead to deadlocks 886 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 887 // Threads_lock is special, since the safepoint synchronization will not start before this is 888 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 889 // since it is used to transfer control between JavaThreads and the VMThread 890 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 891 if ((cur->allow_vm_block() && 892 cur != Threads_lock && 893 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 894 cur != VMOperationRequest_lock && 895 cur != VMOperationQueue_lock) || 896 cur->rank() == Mutex::special) { 897 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 898 } 899 } 900 } 901 902 if (GCALotAtAllSafepoints) { 903 // We could enter a safepoint here and thus have a gc 904 InterfaceSupport::check_gc_alot(); 905 } 906 #endif 907 } 908 #endif 909 910 bool Thread::is_in_stack(address adr) const { 911 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 912 address end = os::current_stack_pointer(); 913 // Allow non Java threads to call this without stack_base 914 if (_stack_base == NULL) return true; 915 if (stack_base() >= adr && adr >= end) return true; 916 917 return false; 918 } 919 920 bool Thread::is_in_usable_stack(address adr) const { 921 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 922 size_t usable_stack_size = _stack_size - stack_guard_size; 923 924 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 925 } 926 927 928 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 929 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 930 // used for compilation in the future. If that change is made, the need for these methods 931 // should be revisited, and they should be removed if possible. 932 933 bool Thread::is_lock_owned(address adr) const { 934 return on_local_stack(adr); 935 } 936 937 bool Thread::set_as_starting_thread() { 938 // NOTE: this must be called inside the main thread. 939 return os::create_main_thread((JavaThread*)this); 940 } 941 942 static void initialize_class(Symbol* class_name, TRAPS) { 943 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 944 InstanceKlass::cast(klass)->initialize(CHECK); 945 } 946 947 948 // Creates the initial ThreadGroup 949 static Handle create_initial_thread_group(TRAPS) { 950 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 951 instanceKlassHandle klass (THREAD, k); 952 953 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 954 { 955 JavaValue result(T_VOID); 956 JavaCalls::call_special(&result, 957 system_instance, 958 klass, 959 vmSymbols::object_initializer_name(), 960 vmSymbols::void_method_signature(), 961 CHECK_NH); 962 } 963 Universe::set_system_thread_group(system_instance()); 964 965 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 966 { 967 JavaValue result(T_VOID); 968 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 969 JavaCalls::call_special(&result, 970 main_instance, 971 klass, 972 vmSymbols::object_initializer_name(), 973 vmSymbols::threadgroup_string_void_signature(), 974 system_instance, 975 string, 976 CHECK_NH); 977 } 978 return main_instance; 979 } 980 981 // Creates the initial Thread 982 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 983 TRAPS) { 984 static const char *initial_thread_name = "main"; 985 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 986 instanceKlassHandle klass (THREAD, k); 987 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 988 989 java_lang_Thread::set_thread(thread_oop(), thread); 990 java_lang_Thread::set_priority(thread_oop(), NormPriority); 991 thread->set_threadObj(thread_oop()); 992 thread->set_native_thread_name(initial_thread_name); 993 994 Handle string = java_lang_String::create_from_str(initial_thread_name, CHECK_NULL); 995 996 JavaValue result(T_VOID); 997 JavaCalls::call_special(&result, thread_oop, 998 klass, 999 vmSymbols::object_initializer_name(), 1000 vmSymbols::threadgroup_string_void_signature(), 1001 thread_group, 1002 string, 1003 CHECK_NULL); 1004 return thread_oop(); 1005 } 1006 1007 char java_runtime_name[128] = ""; 1008 char java_runtime_version[128] = ""; 1009 1010 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1011 static const char* get_java_runtime_name(TRAPS) { 1012 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1013 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1014 fieldDescriptor fd; 1015 bool found = k != NULL && 1016 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1017 vmSymbols::string_signature(), &fd); 1018 if (found) { 1019 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1020 if (name_oop == NULL) { 1021 return NULL; 1022 } 1023 const char* name = java_lang_String::as_utf8_string(name_oop, 1024 java_runtime_name, 1025 sizeof(java_runtime_name)); 1026 return name; 1027 } else { 1028 return NULL; 1029 } 1030 } 1031 1032 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1033 static const char* get_java_runtime_version(TRAPS) { 1034 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1035 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1036 fieldDescriptor fd; 1037 bool found = k != NULL && 1038 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1039 vmSymbols::string_signature(), &fd); 1040 if (found) { 1041 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1042 if (name_oop == NULL) { 1043 return NULL; 1044 } 1045 const char* name = java_lang_String::as_utf8_string(name_oop, 1046 java_runtime_version, 1047 sizeof(java_runtime_version)); 1048 return name; 1049 } else { 1050 return NULL; 1051 } 1052 } 1053 1054 // General purpose hook into Java code, run once when the VM is initialized. 1055 // The Java library method itself may be changed independently from the VM. 1056 static void call_postVMInitHook(TRAPS) { 1057 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1058 instanceKlassHandle klass (THREAD, k); 1059 if (klass.not_null()) { 1060 JavaValue result(T_VOID); 1061 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1062 vmSymbols::void_method_signature(), 1063 CHECK); 1064 } 1065 } 1066 1067 static void reset_vm_info_property(TRAPS) { 1068 // the vm info string 1069 ResourceMark rm(THREAD); 1070 const char *vm_info = VM_Version::vm_info_string(); 1071 1072 // java.lang.System class 1073 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1074 instanceKlassHandle klass (THREAD, k); 1075 1076 // setProperty arguments 1077 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1078 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1079 1080 // return value 1081 JavaValue r(T_OBJECT); 1082 1083 // public static String setProperty(String key, String value); 1084 JavaCalls::call_static(&r, 1085 klass, 1086 vmSymbols::setProperty_name(), 1087 vmSymbols::string_string_string_signature(), 1088 key_str, 1089 value_str, 1090 CHECK); 1091 } 1092 1093 1094 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1095 bool daemon, TRAPS) { 1096 assert(thread_group.not_null(), "thread group should be specified"); 1097 assert(threadObj() == NULL, "should only create Java thread object once"); 1098 1099 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1100 instanceKlassHandle klass (THREAD, k); 1101 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1102 1103 java_lang_Thread::set_thread(thread_oop(), this); 1104 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1105 set_threadObj(thread_oop()); 1106 1107 JavaValue result(T_VOID); 1108 if (thread_name != NULL) { 1109 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1110 // Thread gets assigned specified name and null target 1111 JavaCalls::call_special(&result, 1112 thread_oop, 1113 klass, 1114 vmSymbols::object_initializer_name(), 1115 vmSymbols::threadgroup_string_void_signature(), 1116 thread_group, // Argument 1 1117 name, // Argument 2 1118 THREAD); 1119 } else { 1120 // Thread gets assigned name "Thread-nnn" and null target 1121 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1122 JavaCalls::call_special(&result, 1123 thread_oop, 1124 klass, 1125 vmSymbols::object_initializer_name(), 1126 vmSymbols::threadgroup_runnable_void_signature(), 1127 thread_group, // Argument 1 1128 Handle(), // Argument 2 1129 THREAD); 1130 } 1131 1132 1133 if (daemon) { 1134 java_lang_Thread::set_daemon(thread_oop()); 1135 } 1136 1137 if (HAS_PENDING_EXCEPTION) { 1138 return; 1139 } 1140 1141 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass()); 1142 Handle threadObj(THREAD, this->threadObj()); 1143 1144 JavaCalls::call_special(&result, 1145 thread_group, 1146 group, 1147 vmSymbols::add_method_name(), 1148 vmSymbols::thread_void_signature(), 1149 threadObj, // Arg 1 1150 THREAD); 1151 } 1152 1153 // NamedThread -- non-JavaThread subclasses with multiple 1154 // uniquely named instances should derive from this. 1155 NamedThread::NamedThread() : Thread() { 1156 _name = NULL; 1157 _processed_thread = NULL; 1158 _gc_id = GCId::undefined(); 1159 } 1160 1161 NamedThread::~NamedThread() { 1162 if (_name != NULL) { 1163 FREE_C_HEAP_ARRAY(char, _name); 1164 _name = NULL; 1165 } 1166 } 1167 1168 void NamedThread::set_name(const char* format, ...) { 1169 guarantee(_name == NULL, "Only get to set name once."); 1170 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1171 guarantee(_name != NULL, "alloc failure"); 1172 va_list ap; 1173 va_start(ap, format); 1174 jio_vsnprintf(_name, max_name_len, format, ap); 1175 va_end(ap); 1176 } 1177 1178 void NamedThread::initialize_named_thread() { 1179 set_native_thread_name(name()); 1180 } 1181 1182 void NamedThread::print_on(outputStream* st) const { 1183 st->print("\"%s\" ", name()); 1184 Thread::print_on(st); 1185 st->cr(); 1186 } 1187 1188 1189 // ======= WatcherThread ======== 1190 1191 // The watcher thread exists to simulate timer interrupts. It should 1192 // be replaced by an abstraction over whatever native support for 1193 // timer interrupts exists on the platform. 1194 1195 WatcherThread* WatcherThread::_watcher_thread = NULL; 1196 bool WatcherThread::_startable = false; 1197 volatile bool WatcherThread::_should_terminate = false; 1198 1199 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1200 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1201 if (os::create_thread(this, os::watcher_thread)) { 1202 _watcher_thread = this; 1203 1204 // Set the watcher thread to the highest OS priority which should not be 1205 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1206 // is created. The only normal thread using this priority is the reference 1207 // handler thread, which runs for very short intervals only. 1208 // If the VMThread's priority is not lower than the WatcherThread profiling 1209 // will be inaccurate. 1210 os::set_priority(this, MaxPriority); 1211 if (!DisableStartThread) { 1212 os::start_thread(this); 1213 } 1214 } 1215 } 1216 1217 int WatcherThread::sleep() const { 1218 // The WatcherThread does not participate in the safepoint protocol 1219 // for the PeriodicTask_lock because it is not a JavaThread. 1220 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1221 1222 if (_should_terminate) { 1223 // check for termination before we do any housekeeping or wait 1224 return 0; // we did not sleep. 1225 } 1226 1227 // remaining will be zero if there are no tasks, 1228 // causing the WatcherThread to sleep until a task is 1229 // enrolled 1230 int remaining = PeriodicTask::time_to_wait(); 1231 int time_slept = 0; 1232 1233 // we expect this to timeout - we only ever get unparked when 1234 // we should terminate or when a new task has been enrolled 1235 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1236 1237 jlong time_before_loop = os::javaTimeNanos(); 1238 1239 while (true) { 1240 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1241 remaining); 1242 jlong now = os::javaTimeNanos(); 1243 1244 if (remaining == 0) { 1245 // if we didn't have any tasks we could have waited for a long time 1246 // consider the time_slept zero and reset time_before_loop 1247 time_slept = 0; 1248 time_before_loop = now; 1249 } else { 1250 // need to recalculate since we might have new tasks in _tasks 1251 time_slept = (int) ((now - time_before_loop) / 1000000); 1252 } 1253 1254 // Change to task list or spurious wakeup of some kind 1255 if (timedout || _should_terminate) { 1256 break; 1257 } 1258 1259 remaining = PeriodicTask::time_to_wait(); 1260 if (remaining == 0) { 1261 // Last task was just disenrolled so loop around and wait until 1262 // another task gets enrolled 1263 continue; 1264 } 1265 1266 remaining -= time_slept; 1267 if (remaining <= 0) { 1268 break; 1269 } 1270 } 1271 1272 return time_slept; 1273 } 1274 1275 void WatcherThread::run() { 1276 assert(this == watcher_thread(), "just checking"); 1277 1278 this->record_stack_base_and_size(); 1279 this->set_native_thread_name(this->name()); 1280 this->set_active_handles(JNIHandleBlock::allocate_block()); 1281 while (true) { 1282 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1283 assert(watcher_thread() == this, "thread consistency check"); 1284 1285 // Calculate how long it'll be until the next PeriodicTask work 1286 // should be done, and sleep that amount of time. 1287 int time_waited = sleep(); 1288 1289 if (is_error_reported()) { 1290 // A fatal error has happened, the error handler(VMError::report_and_die) 1291 // should abort JVM after creating an error log file. However in some 1292 // rare cases, the error handler itself might deadlock. Here we try to 1293 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1294 // 1295 // This code is in WatcherThread because WatcherThread wakes up 1296 // periodically so the fatal error handler doesn't need to do anything; 1297 // also because the WatcherThread is less likely to crash than other 1298 // threads. 1299 1300 for (;;) { 1301 if (!ShowMessageBoxOnError 1302 && (OnError == NULL || OnError[0] == '\0') 1303 && Arguments::abort_hook() == NULL) { 1304 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds 1305 fdStream err(defaultStream::output_fd()); 1306 err.print_raw_cr("# [ timer expired, abort... ]"); 1307 // skip atexit/vm_exit/vm_abort hooks 1308 os::die(); 1309 } 1310 1311 // Wake up 5 seconds later, the fatal handler may reset OnError or 1312 // ShowMessageBoxOnError when it is ready to abort. 1313 os::sleep(this, 5 * 1000, false); 1314 } 1315 } 1316 1317 if (_should_terminate) { 1318 // check for termination before posting the next tick 1319 break; 1320 } 1321 1322 PeriodicTask::real_time_tick(time_waited); 1323 } 1324 1325 // Signal that it is terminated 1326 { 1327 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1328 _watcher_thread = NULL; 1329 Terminator_lock->notify(); 1330 } 1331 } 1332 1333 void WatcherThread::start() { 1334 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1335 1336 if (watcher_thread() == NULL && _startable) { 1337 _should_terminate = false; 1338 // Create the single instance of WatcherThread 1339 new WatcherThread(); 1340 } 1341 } 1342 1343 void WatcherThread::make_startable() { 1344 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1345 _startable = true; 1346 } 1347 1348 void WatcherThread::stop() { 1349 { 1350 // Follow normal safepoint aware lock enter protocol since the 1351 // WatcherThread is stopped by another JavaThread. 1352 MutexLocker ml(PeriodicTask_lock); 1353 _should_terminate = true; 1354 1355 WatcherThread* watcher = watcher_thread(); 1356 if (watcher != NULL) { 1357 // unpark the WatcherThread so it can see that it should terminate 1358 watcher->unpark(); 1359 } 1360 } 1361 1362 MutexLocker mu(Terminator_lock); 1363 1364 while (watcher_thread() != NULL) { 1365 // This wait should make safepoint checks, wait without a timeout, 1366 // and wait as a suspend-equivalent condition. 1367 // 1368 // Note: If the FlatProfiler is running, then this thread is waiting 1369 // for the WatcherThread to terminate and the WatcherThread, via the 1370 // FlatProfiler task, is waiting for the external suspend request on 1371 // this thread to complete. wait_for_ext_suspend_completion() will 1372 // eventually timeout, but that takes time. Making this wait a 1373 // suspend-equivalent condition solves that timeout problem. 1374 // 1375 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1376 Mutex::_as_suspend_equivalent_flag); 1377 } 1378 } 1379 1380 void WatcherThread::unpark() { 1381 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1382 PeriodicTask_lock->notify(); 1383 } 1384 1385 void WatcherThread::print_on(outputStream* st) const { 1386 st->print("\"%s\" ", name()); 1387 Thread::print_on(st); 1388 st->cr(); 1389 } 1390 1391 // ======= JavaThread ======== 1392 1393 #if INCLUDE_JVMCI 1394 1395 jlong* JavaThread::_jvmci_old_thread_counters; 1396 1397 bool jvmci_counters_include(JavaThread* thread) { 1398 oop threadObj = thread->threadObj(); 1399 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1400 } 1401 1402 void JavaThread::collect_counters(typeArrayOop array) { 1403 if (JVMCICounterSize > 0) { 1404 MutexLocker tl(Threads_lock); 1405 for (int i = 0; i < array->length(); i++) { 1406 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1407 } 1408 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1409 if (jvmci_counters_include(tp)) { 1410 for (int i = 0; i < array->length(); i++) { 1411 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1412 } 1413 } 1414 } 1415 } 1416 } 1417 1418 #endif // INCLUDE_JVMCI 1419 1420 // A JavaThread is a normal Java thread 1421 1422 void JavaThread::initialize() { 1423 // Initialize fields 1424 1425 set_saved_exception_pc(NULL); 1426 set_threadObj(NULL); 1427 _anchor.clear(); 1428 set_entry_point(NULL); 1429 set_jni_functions(jni_functions()); 1430 set_callee_target(NULL); 1431 set_vm_result(NULL); 1432 set_vm_result_2(NULL); 1433 set_vframe_array_head(NULL); 1434 set_vframe_array_last(NULL); 1435 set_deferred_locals(NULL); 1436 set_deopt_mark(NULL); 1437 set_deopt_nmethod(NULL); 1438 clear_must_deopt_id(); 1439 set_monitor_chunks(NULL); 1440 set_next(NULL); 1441 set_thread_state(_thread_new); 1442 _terminated = _not_terminated; 1443 _privileged_stack_top = NULL; 1444 _array_for_gc = NULL; 1445 _suspend_equivalent = false; 1446 _in_deopt_handler = 0; 1447 _doing_unsafe_access = false; 1448 _stack_guard_state = stack_guard_unused; 1449 #if INCLUDE_JVMCI 1450 _pending_monitorenter = false; 1451 _pending_deoptimization = -1; 1452 _pending_failed_speculation = NULL; 1453 _pending_transfer_to_interpreter = false; 1454 _jvmci._alternate_call_target = NULL; 1455 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1456 if (JVMCICounterSize > 0) { 1457 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1458 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1459 } else { 1460 _jvmci_counters = NULL; 1461 } 1462 #endif // INCLUDE_JVMCI 1463 _reserved_stack_activation = NULL; // stack base not known yet 1464 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1465 _exception_pc = 0; 1466 _exception_handler_pc = 0; 1467 _is_method_handle_return = 0; 1468 _jvmti_thread_state= NULL; 1469 _should_post_on_exceptions_flag = JNI_FALSE; 1470 _jvmti_get_loaded_classes_closure = NULL; 1471 _interp_only_mode = 0; 1472 _special_runtime_exit_condition = _no_async_condition; 1473 _pending_async_exception = NULL; 1474 _thread_stat = NULL; 1475 _thread_stat = new ThreadStatistics(); 1476 _blocked_on_compilation = false; 1477 _jni_active_critical = 0; 1478 _pending_jni_exception_check_fn = NULL; 1479 _do_not_unlock_if_synchronized = false; 1480 _cached_monitor_info = NULL; 1481 _parker = Parker::Allocate(this); 1482 1483 #ifndef PRODUCT 1484 _jmp_ring_index = 0; 1485 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1486 record_jump(NULL, NULL, NULL, 0); 1487 } 1488 #endif // PRODUCT 1489 1490 set_thread_profiler(NULL); 1491 if (FlatProfiler::is_active()) { 1492 // This is where we would decide to either give each thread it's own profiler 1493 // or use one global one from FlatProfiler, 1494 // or up to some count of the number of profiled threads, etc. 1495 ThreadProfiler* pp = new ThreadProfiler(); 1496 pp->engage(); 1497 set_thread_profiler(pp); 1498 } 1499 1500 // Setup safepoint state info for this thread 1501 ThreadSafepointState::create(this); 1502 1503 debug_only(_java_call_counter = 0); 1504 1505 // JVMTI PopFrame support 1506 _popframe_condition = popframe_inactive; 1507 _popframe_preserved_args = NULL; 1508 _popframe_preserved_args_size = 0; 1509 _frames_to_pop_failed_realloc = 0; 1510 1511 pd_initialize(); 1512 } 1513 1514 #if INCLUDE_ALL_GCS 1515 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1516 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1517 #endif // INCLUDE_ALL_GCS 1518 1519 JavaThread::JavaThread(bool is_attaching_via_jni) : 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 if (is_attaching_via_jni) { 1528 _jni_attach_state = _attaching_via_jni; 1529 } else { 1530 _jni_attach_state = _not_attaching_via_jni; 1531 } 1532 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1533 } 1534 1535 bool JavaThread::reguard_stack(address cur_sp) { 1536 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1537 && _stack_guard_state != stack_guard_reserved_disabled) { 1538 return true; // Stack already guarded or guard pages not needed. 1539 } 1540 1541 if (register_stack_overflow()) { 1542 // For those architectures which have separate register and 1543 // memory stacks, we must check the register stack to see if 1544 // it has overflowed. 1545 return false; 1546 } 1547 1548 // Java code never executes within the yellow zone: the latter is only 1549 // there to provoke an exception during stack banging. If java code 1550 // is executing there, either StackShadowPages should be larger, or 1551 // some exception code in c1, c2 or the interpreter isn't unwinding 1552 // when it should. 1553 guarantee(cur_sp > stack_reserved_zone_base(), 1554 "not enough space to reguard - increase StackShadowPages"); 1555 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1556 enable_stack_yellow_reserved_zone(); 1557 if (reserved_stack_activation() != stack_base()) { 1558 set_reserved_stack_activation(stack_base()); 1559 } 1560 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1561 set_reserved_stack_activation(stack_base()); 1562 enable_stack_reserved_zone(); 1563 } 1564 return true; 1565 } 1566 1567 bool JavaThread::reguard_stack(void) { 1568 return reguard_stack(os::current_stack_pointer()); 1569 } 1570 1571 1572 void JavaThread::block_if_vm_exited() { 1573 if (_terminated == _vm_exited) { 1574 // _vm_exited is set at safepoint, and Threads_lock is never released 1575 // we will block here forever 1576 Threads_lock->lock_without_safepoint_check(); 1577 ShouldNotReachHere(); 1578 } 1579 } 1580 1581 1582 // Remove this ifdef when C1 is ported to the compiler interface. 1583 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1584 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1585 1586 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1587 Thread() 1588 #if INCLUDE_ALL_GCS 1589 , _satb_mark_queue(&_satb_mark_queue_set), 1590 _dirty_card_queue(&_dirty_card_queue_set) 1591 #endif // INCLUDE_ALL_GCS 1592 { 1593 initialize(); 1594 _jni_attach_state = _not_attaching_via_jni; 1595 set_entry_point(entry_point); 1596 // Create the native thread itself. 1597 // %note runtime_23 1598 os::ThreadType thr_type = os::java_thread; 1599 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1600 os::java_thread; 1601 os::create_thread(this, thr_type, stack_sz); 1602 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1603 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1604 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1605 // the exception consists of creating the exception object & initializing it, initialization 1606 // will leave the VM via a JavaCall and then all locks must be unlocked). 1607 // 1608 // The thread is still suspended when we reach here. Thread must be explicit started 1609 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1610 // by calling Threads:add. The reason why this is not done here, is because the thread 1611 // object must be fully initialized (take a look at JVM_Start) 1612 } 1613 1614 JavaThread::~JavaThread() { 1615 1616 // JSR166 -- return the parker to the free list 1617 Parker::Release(_parker); 1618 _parker = NULL; 1619 1620 // Free any remaining previous UnrollBlock 1621 vframeArray* old_array = vframe_array_last(); 1622 1623 if (old_array != NULL) { 1624 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1625 old_array->set_unroll_block(NULL); 1626 delete old_info; 1627 delete old_array; 1628 } 1629 1630 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1631 if (deferred != NULL) { 1632 // This can only happen if thread is destroyed before deoptimization occurs. 1633 assert(deferred->length() != 0, "empty array!"); 1634 do { 1635 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1636 deferred->remove_at(0); 1637 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1638 delete dlv; 1639 } while (deferred->length() != 0); 1640 delete deferred; 1641 } 1642 1643 // All Java related clean up happens in exit 1644 ThreadSafepointState::destroy(this); 1645 if (_thread_profiler != NULL) delete _thread_profiler; 1646 if (_thread_stat != NULL) delete _thread_stat; 1647 1648 #if INCLUDE_JVMCI 1649 if (JVMCICounterSize > 0) { 1650 if (jvmci_counters_include(this)) { 1651 for (int i = 0; i < JVMCICounterSize; i++) { 1652 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1653 } 1654 } 1655 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1656 } 1657 #endif // INCLUDE_JVMCI 1658 } 1659 1660 1661 // The first routine called by a new Java thread 1662 void JavaThread::run() { 1663 // initialize thread-local alloc buffer related fields 1664 this->initialize_tlab(); 1665 1666 // used to test validity of stack trace backs 1667 this->record_base_of_stack_pointer(); 1668 1669 // Record real stack base and size. 1670 this->record_stack_base_and_size(); 1671 1672 this->create_stack_guard_pages(); 1673 1674 this->cache_global_variables(); 1675 1676 // Thread is now sufficient initialized to be handled by the safepoint code as being 1677 // in the VM. Change thread state from _thread_new to _thread_in_vm 1678 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1679 1680 assert(JavaThread::current() == this, "sanity check"); 1681 assert(!Thread::current()->owns_locks(), "sanity check"); 1682 1683 DTRACE_THREAD_PROBE(start, this); 1684 1685 // This operation might block. We call that after all safepoint checks for a new thread has 1686 // been completed. 1687 this->set_active_handles(JNIHandleBlock::allocate_block()); 1688 1689 if (JvmtiExport::should_post_thread_life()) { 1690 JvmtiExport::post_thread_start(this); 1691 } 1692 1693 EventThreadStart event; 1694 if (event.should_commit()) { 1695 event.set_thread(THREAD_TRACE_ID(this)); 1696 event.commit(); 1697 } 1698 1699 // We call another function to do the rest so we are sure that the stack addresses used 1700 // from there will be lower than the stack base just computed 1701 thread_main_inner(); 1702 1703 // Note, thread is no longer valid at this point! 1704 } 1705 1706 1707 void JavaThread::thread_main_inner() { 1708 assert(JavaThread::current() == this, "sanity check"); 1709 assert(this->threadObj() != NULL, "just checking"); 1710 1711 // Execute thread entry point unless this thread has a pending exception 1712 // or has been stopped before starting. 1713 // Note: Due to JVM_StopThread we can have pending exceptions already! 1714 if (!this->has_pending_exception() && 1715 !java_lang_Thread::is_stillborn(this->threadObj())) { 1716 { 1717 ResourceMark rm(this); 1718 this->set_native_thread_name(this->get_thread_name()); 1719 } 1720 HandleMark hm(this); 1721 this->entry_point()(this, this); 1722 } 1723 1724 DTRACE_THREAD_PROBE(stop, this); 1725 1726 this->exit(false); 1727 delete this; 1728 } 1729 1730 1731 static void ensure_join(JavaThread* thread) { 1732 // We do not need to grap the Threads_lock, since we are operating on ourself. 1733 Handle threadObj(thread, thread->threadObj()); 1734 assert(threadObj.not_null(), "java thread object must exist"); 1735 ObjectLocker lock(threadObj, thread); 1736 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1737 thread->clear_pending_exception(); 1738 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1739 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1740 // Clear the native thread instance - this makes isAlive return false and allows the join() 1741 // to complete once we've done the notify_all below 1742 java_lang_Thread::set_thread(threadObj(), NULL); 1743 lock.notify_all(thread); 1744 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1745 thread->clear_pending_exception(); 1746 } 1747 1748 1749 // For any new cleanup additions, please check to see if they need to be applied to 1750 // cleanup_failed_attach_current_thread as well. 1751 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1752 assert(this == JavaThread::current(), "thread consistency check"); 1753 1754 HandleMark hm(this); 1755 Handle uncaught_exception(this, this->pending_exception()); 1756 this->clear_pending_exception(); 1757 Handle threadObj(this, this->threadObj()); 1758 assert(threadObj.not_null(), "Java thread object should be created"); 1759 1760 if (get_thread_profiler() != NULL) { 1761 get_thread_profiler()->disengage(); 1762 ResourceMark rm; 1763 get_thread_profiler()->print(get_thread_name()); 1764 } 1765 1766 1767 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1768 { 1769 EXCEPTION_MARK; 1770 1771 CLEAR_PENDING_EXCEPTION; 1772 } 1773 if (!destroy_vm) { 1774 if (uncaught_exception.not_null()) { 1775 EXCEPTION_MARK; 1776 // Call method Thread.dispatchUncaughtException(). 1777 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1778 JavaValue result(T_VOID); 1779 JavaCalls::call_virtual(&result, 1780 threadObj, thread_klass, 1781 vmSymbols::dispatchUncaughtException_name(), 1782 vmSymbols::throwable_void_signature(), 1783 uncaught_exception, 1784 THREAD); 1785 if (HAS_PENDING_EXCEPTION) { 1786 ResourceMark rm(this); 1787 jio_fprintf(defaultStream::error_stream(), 1788 "\nException: %s thrown from the UncaughtExceptionHandler" 1789 " in thread \"%s\"\n", 1790 pending_exception()->klass()->external_name(), 1791 get_thread_name()); 1792 CLEAR_PENDING_EXCEPTION; 1793 } 1794 } 1795 1796 // Called before the java thread exit since we want to read info 1797 // from java_lang_Thread object 1798 EventThreadEnd event; 1799 if (event.should_commit()) { 1800 event.set_thread(THREAD_TRACE_ID(this)); 1801 event.commit(); 1802 } 1803 1804 // Call after last event on thread 1805 EVENT_THREAD_EXIT(this); 1806 1807 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1808 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1809 // is deprecated anyhow. 1810 if (!is_Compiler_thread()) { 1811 int count = 3; 1812 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1813 EXCEPTION_MARK; 1814 JavaValue result(T_VOID); 1815 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1816 JavaCalls::call_virtual(&result, 1817 threadObj, thread_klass, 1818 vmSymbols::exit_method_name(), 1819 vmSymbols::void_method_signature(), 1820 THREAD); 1821 CLEAR_PENDING_EXCEPTION; 1822 } 1823 } 1824 // notify JVMTI 1825 if (JvmtiExport::should_post_thread_life()) { 1826 JvmtiExport::post_thread_end(this); 1827 } 1828 1829 // We have notified the agents that we are exiting, before we go on, 1830 // we must check for a pending external suspend request and honor it 1831 // in order to not surprise the thread that made the suspend request. 1832 while (true) { 1833 { 1834 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1835 if (!is_external_suspend()) { 1836 set_terminated(_thread_exiting); 1837 ThreadService::current_thread_exiting(this); 1838 break; 1839 } 1840 // Implied else: 1841 // Things get a little tricky here. We have a pending external 1842 // suspend request, but we are holding the SR_lock so we 1843 // can't just self-suspend. So we temporarily drop the lock 1844 // and then self-suspend. 1845 } 1846 1847 ThreadBlockInVM tbivm(this); 1848 java_suspend_self(); 1849 1850 // We're done with this suspend request, but we have to loop around 1851 // and check again. Eventually we will get SR_lock without a pending 1852 // external suspend request and will be able to mark ourselves as 1853 // exiting. 1854 } 1855 // no more external suspends are allowed at this point 1856 } else { 1857 // before_exit() has already posted JVMTI THREAD_END events 1858 } 1859 1860 // Notify waiters on thread object. This has to be done after exit() is called 1861 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1862 // group should have the destroyed bit set before waiters are notified). 1863 ensure_join(this); 1864 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1865 1866 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1867 // held by this thread must be released. The spec does not distinguish 1868 // between JNI-acquired and regular Java monitors. We can only see 1869 // regular Java monitors here if monitor enter-exit matching is broken. 1870 // 1871 // Optionally release any monitors for regular JavaThread exits. This 1872 // is provided as a work around for any bugs in monitor enter-exit 1873 // matching. This can be expensive so it is not enabled by default. 1874 // 1875 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1876 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1877 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1878 // Sanity check even though JNI DetachCurrentThread() would have 1879 // returned JNI_ERR if there was a Java frame. JavaThread exit 1880 // should be done executing Java code by the time we get here. 1881 assert(!this->has_last_Java_frame(), 1882 "should not have a Java frame when detaching or exiting"); 1883 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1884 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1885 } 1886 1887 // These things needs to be done while we are still a Java Thread. Make sure that thread 1888 // is in a consistent state, in case GC happens 1889 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1890 1891 if (active_handles() != NULL) { 1892 JNIHandleBlock* block = active_handles(); 1893 set_active_handles(NULL); 1894 JNIHandleBlock::release_block(block); 1895 } 1896 1897 if (free_handle_block() != NULL) { 1898 JNIHandleBlock* block = free_handle_block(); 1899 set_free_handle_block(NULL); 1900 JNIHandleBlock::release_block(block); 1901 } 1902 1903 // These have to be removed while this is still a valid thread. 1904 remove_stack_guard_pages(); 1905 1906 if (UseTLAB) { 1907 tlab().make_parsable(true); // retire TLAB 1908 } 1909 1910 if (JvmtiEnv::environments_might_exist()) { 1911 JvmtiExport::cleanup_thread(this); 1912 } 1913 1914 // We must flush any deferred card marks before removing a thread from 1915 // the list of active threads. 1916 Universe::heap()->flush_deferred_store_barrier(this); 1917 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1918 1919 #if INCLUDE_ALL_GCS 1920 // We must flush the G1-related buffers before removing a thread 1921 // from the list of active threads. We must do this after any deferred 1922 // card marks have been flushed (above) so that any entries that are 1923 // added to the thread's dirty card queue as a result are not lost. 1924 if (UseG1GC) { 1925 flush_barrier_queues(); 1926 } 1927 #endif // INCLUDE_ALL_GCS 1928 1929 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1930 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1931 os::current_thread_id()); 1932 1933 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1934 Threads::remove(this); 1935 } 1936 1937 #if INCLUDE_ALL_GCS 1938 // Flush G1-related queues. 1939 void JavaThread::flush_barrier_queues() { 1940 satb_mark_queue().flush(); 1941 dirty_card_queue().flush(); 1942 } 1943 1944 void JavaThread::initialize_queues() { 1945 assert(!SafepointSynchronize::is_at_safepoint(), 1946 "we should not be at a safepoint"); 1947 1948 SATBMarkQueue& satb_queue = satb_mark_queue(); 1949 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1950 // The SATB queue should have been constructed with its active 1951 // field set to false. 1952 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1953 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1954 // If we are creating the thread during a marking cycle, we should 1955 // set the active field of the SATB queue to true. 1956 if (satb_queue_set.is_active()) { 1957 satb_queue.set_active(true); 1958 } 1959 1960 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1961 // The dirty card queue should have been constructed with its 1962 // active field set to true. 1963 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1964 } 1965 #endif // INCLUDE_ALL_GCS 1966 1967 void JavaThread::cleanup_failed_attach_current_thread() { 1968 if (get_thread_profiler() != NULL) { 1969 get_thread_profiler()->disengage(); 1970 ResourceMark rm; 1971 get_thread_profiler()->print(get_thread_name()); 1972 } 1973 1974 if (active_handles() != NULL) { 1975 JNIHandleBlock* block = active_handles(); 1976 set_active_handles(NULL); 1977 JNIHandleBlock::release_block(block); 1978 } 1979 1980 if (free_handle_block() != NULL) { 1981 JNIHandleBlock* block = free_handle_block(); 1982 set_free_handle_block(NULL); 1983 JNIHandleBlock::release_block(block); 1984 } 1985 1986 // These have to be removed while this is still a valid thread. 1987 remove_stack_guard_pages(); 1988 1989 if (UseTLAB) { 1990 tlab().make_parsable(true); // retire TLAB, if any 1991 } 1992 1993 #if INCLUDE_ALL_GCS 1994 if (UseG1GC) { 1995 flush_barrier_queues(); 1996 } 1997 #endif // INCLUDE_ALL_GCS 1998 1999 Threads::remove(this); 2000 delete this; 2001 } 2002 2003 2004 2005 2006 JavaThread* JavaThread::active() { 2007 Thread* thread = Thread::current(); 2008 if (thread->is_Java_thread()) { 2009 return (JavaThread*) thread; 2010 } else { 2011 assert(thread->is_VM_thread(), "this must be a vm thread"); 2012 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2013 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2014 assert(ret->is_Java_thread(), "must be a Java thread"); 2015 return ret; 2016 } 2017 } 2018 2019 bool JavaThread::is_lock_owned(address adr) const { 2020 if (Thread::is_lock_owned(adr)) return true; 2021 2022 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2023 if (chunk->contains(adr)) return true; 2024 } 2025 2026 return false; 2027 } 2028 2029 2030 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2031 chunk->set_next(monitor_chunks()); 2032 set_monitor_chunks(chunk); 2033 } 2034 2035 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2036 guarantee(monitor_chunks() != NULL, "must be non empty"); 2037 if (monitor_chunks() == chunk) { 2038 set_monitor_chunks(chunk->next()); 2039 } else { 2040 MonitorChunk* prev = monitor_chunks(); 2041 while (prev->next() != chunk) prev = prev->next(); 2042 prev->set_next(chunk->next()); 2043 } 2044 } 2045 2046 // JVM support. 2047 2048 // Note: this function shouldn't block if it's called in 2049 // _thread_in_native_trans state (such as from 2050 // check_special_condition_for_native_trans()). 2051 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2052 2053 if (has_last_Java_frame() && has_async_condition()) { 2054 // If we are at a polling page safepoint (not a poll return) 2055 // then we must defer async exception because live registers 2056 // will be clobbered by the exception path. Poll return is 2057 // ok because the call we a returning from already collides 2058 // with exception handling registers and so there is no issue. 2059 // (The exception handling path kills call result registers but 2060 // this is ok since the exception kills the result anyway). 2061 2062 if (is_at_poll_safepoint()) { 2063 // if the code we are returning to has deoptimized we must defer 2064 // the exception otherwise live registers get clobbered on the 2065 // exception path before deoptimization is able to retrieve them. 2066 // 2067 RegisterMap map(this, false); 2068 frame caller_fr = last_frame().sender(&map); 2069 assert(caller_fr.is_compiled_frame(), "what?"); 2070 if (caller_fr.is_deoptimized_frame()) { 2071 log_info(exceptions)("deferred async exception at compiled safepoint"); 2072 return; 2073 } 2074 } 2075 } 2076 2077 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2078 if (condition == _no_async_condition) { 2079 // Conditions have changed since has_special_runtime_exit_condition() 2080 // was called: 2081 // - if we were here only because of an external suspend request, 2082 // then that was taken care of above (or cancelled) so we are done 2083 // - if we were here because of another async request, then it has 2084 // been cleared between the has_special_runtime_exit_condition() 2085 // and now so again we are done 2086 return; 2087 } 2088 2089 // Check for pending async. exception 2090 if (_pending_async_exception != NULL) { 2091 // Only overwrite an already pending exception, if it is not a threadDeath. 2092 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2093 2094 // We cannot call Exceptions::_throw(...) here because we cannot block 2095 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2096 2097 if (log_is_enabled(Info, exceptions)) { 2098 ResourceMark rm; 2099 outputStream* logstream = LogHandle(exceptions)::info_stream(); 2100 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2101 if (has_last_Java_frame()) { 2102 frame f = last_frame(); 2103 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2104 } 2105 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2106 } 2107 _pending_async_exception = NULL; 2108 clear_has_async_exception(); 2109 } 2110 } 2111 2112 if (check_unsafe_error && 2113 condition == _async_unsafe_access_error && !has_pending_exception()) { 2114 condition = _no_async_condition; // done 2115 switch (thread_state()) { 2116 case _thread_in_vm: { 2117 JavaThread* THREAD = this; 2118 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2119 } 2120 case _thread_in_native: { 2121 ThreadInVMfromNative tiv(this); 2122 JavaThread* THREAD = this; 2123 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2124 } 2125 case _thread_in_Java: { 2126 ThreadInVMfromJava tiv(this); 2127 JavaThread* THREAD = this; 2128 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2129 } 2130 default: 2131 ShouldNotReachHere(); 2132 } 2133 } 2134 2135 assert(condition == _no_async_condition || has_pending_exception() || 2136 (!check_unsafe_error && condition == _async_unsafe_access_error), 2137 "must have handled the async condition, if no exception"); 2138 } 2139 2140 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2141 // 2142 // Check for pending external suspend. Internal suspend requests do 2143 // not use handle_special_runtime_exit_condition(). 2144 // If JNIEnv proxies are allowed, don't self-suspend if the target 2145 // thread is not the current thread. In older versions of jdbx, jdbx 2146 // threads could call into the VM with another thread's JNIEnv so we 2147 // can be here operating on behalf of a suspended thread (4432884). 2148 bool do_self_suspend = is_external_suspend_with_lock(); 2149 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2150 // 2151 // Because thread is external suspended the safepoint code will count 2152 // thread as at a safepoint. This can be odd because we can be here 2153 // as _thread_in_Java which would normally transition to _thread_blocked 2154 // at a safepoint. We would like to mark the thread as _thread_blocked 2155 // before calling java_suspend_self like all other callers of it but 2156 // we must then observe proper safepoint protocol. (We can't leave 2157 // _thread_blocked with a safepoint in progress). However we can be 2158 // here as _thread_in_native_trans so we can't use a normal transition 2159 // constructor/destructor pair because they assert on that type of 2160 // transition. We could do something like: 2161 // 2162 // JavaThreadState state = thread_state(); 2163 // set_thread_state(_thread_in_vm); 2164 // { 2165 // ThreadBlockInVM tbivm(this); 2166 // java_suspend_self() 2167 // } 2168 // set_thread_state(_thread_in_vm_trans); 2169 // if (safepoint) block; 2170 // set_thread_state(state); 2171 // 2172 // but that is pretty messy. Instead we just go with the way the 2173 // code has worked before and note that this is the only path to 2174 // java_suspend_self that doesn't put the thread in _thread_blocked 2175 // mode. 2176 2177 frame_anchor()->make_walkable(this); 2178 java_suspend_self(); 2179 2180 // We might be here for reasons in addition to the self-suspend request 2181 // so check for other async requests. 2182 } 2183 2184 if (check_asyncs) { 2185 check_and_handle_async_exceptions(); 2186 } 2187 } 2188 2189 void JavaThread::send_thread_stop(oop java_throwable) { 2190 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2191 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2192 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2193 2194 // Do not throw asynchronous exceptions against the compiler thread 2195 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2196 if (!can_call_java()) return; 2197 2198 { 2199 // Actually throw the Throwable against the target Thread - however 2200 // only if there is no thread death exception installed already. 2201 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2202 // If the topmost frame is a runtime stub, then we are calling into 2203 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2204 // must deoptimize the caller before continuing, as the compiled exception handler table 2205 // may not be valid 2206 if (has_last_Java_frame()) { 2207 frame f = last_frame(); 2208 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2209 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2210 RegisterMap reg_map(this, UseBiasedLocking); 2211 frame compiled_frame = f.sender(®_map); 2212 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2213 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2214 } 2215 } 2216 } 2217 2218 // Set async. pending exception in thread. 2219 set_pending_async_exception(java_throwable); 2220 2221 if (log_is_enabled(Info, exceptions)) { 2222 ResourceMark rm; 2223 log_info(exceptions)("Pending Async. exception installed of type: %s", 2224 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2225 } 2226 // for AbortVMOnException flag 2227 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2228 } 2229 } 2230 2231 2232 // Interrupt thread so it will wake up from a potential wait() 2233 Thread::interrupt(this); 2234 } 2235 2236 // External suspension mechanism. 2237 // 2238 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2239 // to any VM_locks and it is at a transition 2240 // Self-suspension will happen on the transition out of the vm. 2241 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2242 // 2243 // Guarantees on return: 2244 // + Target thread will not execute any new bytecode (that's why we need to 2245 // force a safepoint) 2246 // + Target thread will not enter any new monitors 2247 // 2248 void JavaThread::java_suspend() { 2249 { MutexLocker mu(Threads_lock); 2250 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2251 return; 2252 } 2253 } 2254 2255 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2256 if (!is_external_suspend()) { 2257 // a racing resume has cancelled us; bail out now 2258 return; 2259 } 2260 2261 // suspend is done 2262 uint32_t debug_bits = 0; 2263 // Warning: is_ext_suspend_completed() may temporarily drop the 2264 // SR_lock to allow the thread to reach a stable thread state if 2265 // it is currently in a transient thread state. 2266 if (is_ext_suspend_completed(false /* !called_by_wait */, 2267 SuspendRetryDelay, &debug_bits)) { 2268 return; 2269 } 2270 } 2271 2272 VM_ForceSafepoint vm_suspend; 2273 VMThread::execute(&vm_suspend); 2274 } 2275 2276 // Part II of external suspension. 2277 // A JavaThread self suspends when it detects a pending external suspend 2278 // request. This is usually on transitions. It is also done in places 2279 // where continuing to the next transition would surprise the caller, 2280 // e.g., monitor entry. 2281 // 2282 // Returns the number of times that the thread self-suspended. 2283 // 2284 // Note: DO NOT call java_suspend_self() when you just want to block current 2285 // thread. java_suspend_self() is the second stage of cooperative 2286 // suspension for external suspend requests and should only be used 2287 // to complete an external suspend request. 2288 // 2289 int JavaThread::java_suspend_self() { 2290 int ret = 0; 2291 2292 // we are in the process of exiting so don't suspend 2293 if (is_exiting()) { 2294 clear_external_suspend(); 2295 return ret; 2296 } 2297 2298 assert(_anchor.walkable() || 2299 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2300 "must have walkable stack"); 2301 2302 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2303 2304 assert(!this->is_ext_suspended(), 2305 "a thread trying to self-suspend should not already be suspended"); 2306 2307 if (this->is_suspend_equivalent()) { 2308 // If we are self-suspending as a result of the lifting of a 2309 // suspend equivalent condition, then the suspend_equivalent 2310 // flag is not cleared until we set the ext_suspended flag so 2311 // that wait_for_ext_suspend_completion() returns consistent 2312 // results. 2313 this->clear_suspend_equivalent(); 2314 } 2315 2316 // A racing resume may have cancelled us before we grabbed SR_lock 2317 // above. Or another external suspend request could be waiting for us 2318 // by the time we return from SR_lock()->wait(). The thread 2319 // that requested the suspension may already be trying to walk our 2320 // stack and if we return now, we can change the stack out from under 2321 // it. This would be a "bad thing (TM)" and cause the stack walker 2322 // to crash. We stay self-suspended until there are no more pending 2323 // external suspend requests. 2324 while (is_external_suspend()) { 2325 ret++; 2326 this->set_ext_suspended(); 2327 2328 // _ext_suspended flag is cleared by java_resume() 2329 while (is_ext_suspended()) { 2330 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2331 } 2332 } 2333 2334 return ret; 2335 } 2336 2337 #ifdef ASSERT 2338 // verify the JavaThread has not yet been published in the Threads::list, and 2339 // hence doesn't need protection from concurrent access at this stage 2340 void JavaThread::verify_not_published() { 2341 if (!Threads_lock->owned_by_self()) { 2342 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2343 assert(!Threads::includes(this), 2344 "java thread shouldn't have been published yet!"); 2345 } else { 2346 assert(!Threads::includes(this), 2347 "java thread shouldn't have been published yet!"); 2348 } 2349 } 2350 #endif 2351 2352 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2353 // progress or when _suspend_flags is non-zero. 2354 // Current thread needs to self-suspend if there is a suspend request and/or 2355 // block if a safepoint is in progress. 2356 // Async exception ISN'T checked. 2357 // Note only the ThreadInVMfromNative transition can call this function 2358 // directly and when thread state is _thread_in_native_trans 2359 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2360 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2361 2362 JavaThread *curJT = JavaThread::current(); 2363 bool do_self_suspend = thread->is_external_suspend(); 2364 2365 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2366 2367 // If JNIEnv proxies are allowed, don't self-suspend if the target 2368 // thread is not the current thread. In older versions of jdbx, jdbx 2369 // threads could call into the VM with another thread's JNIEnv so we 2370 // can be here operating on behalf of a suspended thread (4432884). 2371 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2372 JavaThreadState state = thread->thread_state(); 2373 2374 // We mark this thread_blocked state as a suspend-equivalent so 2375 // that a caller to is_ext_suspend_completed() won't be confused. 2376 // The suspend-equivalent state is cleared by java_suspend_self(). 2377 thread->set_suspend_equivalent(); 2378 2379 // If the safepoint code sees the _thread_in_native_trans state, it will 2380 // wait until the thread changes to other thread state. There is no 2381 // guarantee on how soon we can obtain the SR_lock and complete the 2382 // self-suspend request. It would be a bad idea to let safepoint wait for 2383 // too long. Temporarily change the state to _thread_blocked to 2384 // let the VM thread know that this thread is ready for GC. The problem 2385 // of changing thread state is that safepoint could happen just after 2386 // java_suspend_self() returns after being resumed, and VM thread will 2387 // see the _thread_blocked state. We must check for safepoint 2388 // after restoring the state and make sure we won't leave while a safepoint 2389 // is in progress. 2390 thread->set_thread_state(_thread_blocked); 2391 thread->java_suspend_self(); 2392 thread->set_thread_state(state); 2393 // Make sure new state is seen by VM thread 2394 if (os::is_MP()) { 2395 if (UseMembar) { 2396 // Force a fence between the write above and read below 2397 OrderAccess::fence(); 2398 } else { 2399 // Must use this rather than serialization page in particular on Windows 2400 InterfaceSupport::serialize_memory(thread); 2401 } 2402 } 2403 } 2404 2405 if (SafepointSynchronize::do_call_back()) { 2406 // If we are safepointing, then block the caller which may not be 2407 // the same as the target thread (see above). 2408 SafepointSynchronize::block(curJT); 2409 } 2410 2411 if (thread->is_deopt_suspend()) { 2412 thread->clear_deopt_suspend(); 2413 RegisterMap map(thread, false); 2414 frame f = thread->last_frame(); 2415 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2416 f = f.sender(&map); 2417 } 2418 if (f.id() == thread->must_deopt_id()) { 2419 thread->clear_must_deopt_id(); 2420 f.deoptimize(thread); 2421 } else { 2422 fatal("missed deoptimization!"); 2423 } 2424 } 2425 } 2426 2427 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2428 // progress or when _suspend_flags is non-zero. 2429 // Current thread needs to self-suspend if there is a suspend request and/or 2430 // block if a safepoint is in progress. 2431 // Also check for pending async exception (not including unsafe access error). 2432 // Note only the native==>VM/Java barriers can call this function and when 2433 // thread state is _thread_in_native_trans. 2434 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2435 check_safepoint_and_suspend_for_native_trans(thread); 2436 2437 if (thread->has_async_exception()) { 2438 // We are in _thread_in_native_trans state, don't handle unsafe 2439 // access error since that may block. 2440 thread->check_and_handle_async_exceptions(false); 2441 } 2442 } 2443 2444 // This is a variant of the normal 2445 // check_special_condition_for_native_trans with slightly different 2446 // semantics for use by critical native wrappers. It does all the 2447 // normal checks but also performs the transition back into 2448 // thread_in_Java state. This is required so that critical natives 2449 // can potentially block and perform a GC if they are the last thread 2450 // exiting the GCLocker. 2451 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2452 check_special_condition_for_native_trans(thread); 2453 2454 // Finish the transition 2455 thread->set_thread_state(_thread_in_Java); 2456 2457 if (thread->do_critical_native_unlock()) { 2458 ThreadInVMfromJavaNoAsyncException tiv(thread); 2459 GCLocker::unlock_critical(thread); 2460 thread->clear_critical_native_unlock(); 2461 } 2462 } 2463 2464 // We need to guarantee the Threads_lock here, since resumes are not 2465 // allowed during safepoint synchronization 2466 // Can only resume from an external suspension 2467 void JavaThread::java_resume() { 2468 assert_locked_or_safepoint(Threads_lock); 2469 2470 // Sanity check: thread is gone, has started exiting or the thread 2471 // was not externally suspended. 2472 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2473 return; 2474 } 2475 2476 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2477 2478 clear_external_suspend(); 2479 2480 if (is_ext_suspended()) { 2481 clear_ext_suspended(); 2482 SR_lock()->notify_all(); 2483 } 2484 } 2485 2486 size_t JavaThread::_stack_red_zone_size = 0; 2487 size_t JavaThread::_stack_yellow_zone_size = 0; 2488 size_t JavaThread::_stack_reserved_zone_size = 0; 2489 size_t JavaThread::_stack_shadow_zone_size = 0; 2490 2491 void JavaThread::create_stack_guard_pages() { 2492 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2493 address low_addr = stack_end(); 2494 size_t len = stack_guard_zone_size(); 2495 2496 int allocate = os::allocate_stack_guard_pages(); 2497 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2498 2499 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2500 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2501 return; 2502 } 2503 2504 if (os::guard_memory((char *) low_addr, len)) { 2505 _stack_guard_state = stack_guard_enabled; 2506 } else { 2507 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2508 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2509 if (os::uncommit_memory((char *) low_addr, len)) { 2510 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2511 } 2512 return; 2513 } 2514 2515 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2516 PTR_FORMAT "-" PTR_FORMAT ".", 2517 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2518 2519 } 2520 2521 void JavaThread::remove_stack_guard_pages() { 2522 assert(Thread::current() == this, "from different thread"); 2523 if (_stack_guard_state == stack_guard_unused) return; 2524 address low_addr = stack_end(); 2525 size_t len = stack_guard_zone_size(); 2526 2527 if (os::allocate_stack_guard_pages()) { 2528 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2529 _stack_guard_state = stack_guard_unused; 2530 } else { 2531 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2532 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2533 return; 2534 } 2535 } else { 2536 if (_stack_guard_state == stack_guard_unused) return; 2537 if (os::unguard_memory((char *) low_addr, len)) { 2538 _stack_guard_state = stack_guard_unused; 2539 } else { 2540 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2541 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2542 return; 2543 } 2544 } 2545 2546 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2547 PTR_FORMAT "-" PTR_FORMAT ".", 2548 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2549 2550 } 2551 2552 void JavaThread::enable_stack_reserved_zone() { 2553 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2554 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2555 2556 // The base notation is from the stack's point of view, growing downward. 2557 // We need to adjust it to work correctly with guard_memory() 2558 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2559 2560 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2561 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2562 2563 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2564 _stack_guard_state = stack_guard_enabled; 2565 } else { 2566 warning("Attempt to guard stack reserved zone failed."); 2567 } 2568 enable_register_stack_guard(); 2569 } 2570 2571 void JavaThread::disable_stack_reserved_zone() { 2572 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2573 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2574 2575 // Simply return if called for a thread that does not use guard pages. 2576 if (_stack_guard_state == stack_guard_unused) return; 2577 2578 // The base notation is from the stack's point of view, growing downward. 2579 // We need to adjust it to work correctly with guard_memory() 2580 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2581 2582 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2583 _stack_guard_state = stack_guard_reserved_disabled; 2584 } else { 2585 warning("Attempt to unguard stack reserved zone failed."); 2586 } 2587 disable_register_stack_guard(); 2588 } 2589 2590 void JavaThread::enable_stack_yellow_reserved_zone() { 2591 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2592 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2593 2594 // The base notation is from the stacks point of view, growing downward. 2595 // We need to adjust it to work correctly with guard_memory() 2596 address base = stack_red_zone_base(); 2597 2598 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2599 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2600 2601 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2602 _stack_guard_state = stack_guard_enabled; 2603 } else { 2604 warning("Attempt to guard stack yellow zone failed."); 2605 } 2606 enable_register_stack_guard(); 2607 } 2608 2609 void JavaThread::disable_stack_yellow_reserved_zone() { 2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2611 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2612 2613 // Simply return if called for a thread that does not use guard pages. 2614 if (_stack_guard_state == stack_guard_unused) return; 2615 2616 // The base notation is from the stacks point of view, growing downward. 2617 // We need to adjust it to work correctly with guard_memory() 2618 address base = stack_red_zone_base(); 2619 2620 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2621 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2622 } else { 2623 warning("Attempt to unguard stack yellow zone failed."); 2624 } 2625 disable_register_stack_guard(); 2626 } 2627 2628 void JavaThread::enable_stack_red_zone() { 2629 // The base notation is from the stacks point of view, growing downward. 2630 // We need to adjust it to work correctly with guard_memory() 2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2632 address base = stack_red_zone_base() - stack_red_zone_size(); 2633 2634 guarantee(base < stack_base(), "Error calculating stack red zone"); 2635 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2636 2637 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2638 warning("Attempt to guard stack red zone failed."); 2639 } 2640 } 2641 2642 void JavaThread::disable_stack_red_zone() { 2643 // The base notation is from the stacks point of view, growing downward. 2644 // We need to adjust it to work correctly with guard_memory() 2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2646 address base = stack_red_zone_base() - stack_red_zone_size(); 2647 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2648 warning("Attempt to unguard stack red zone failed."); 2649 } 2650 } 2651 2652 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2653 // ignore is there is no stack 2654 if (!has_last_Java_frame()) return; 2655 // traverse the stack frames. Starts from top frame. 2656 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2657 frame* fr = fst.current(); 2658 f(fr, fst.register_map()); 2659 } 2660 } 2661 2662 2663 #ifndef PRODUCT 2664 // Deoptimization 2665 // Function for testing deoptimization 2666 void JavaThread::deoptimize() { 2667 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2668 StackFrameStream fst(this, UseBiasedLocking); 2669 bool deopt = false; // Dump stack only if a deopt actually happens. 2670 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2671 // Iterate over all frames in the thread and deoptimize 2672 for (; !fst.is_done(); fst.next()) { 2673 if (fst.current()->can_be_deoptimized()) { 2674 2675 if (only_at) { 2676 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2677 // consists of comma or carriage return separated numbers so 2678 // search for the current bci in that string. 2679 address pc = fst.current()->pc(); 2680 nmethod* nm = (nmethod*) fst.current()->cb(); 2681 ScopeDesc* sd = nm->scope_desc_at(pc); 2682 char buffer[8]; 2683 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2684 size_t len = strlen(buffer); 2685 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2686 while (found != NULL) { 2687 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2688 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2689 // Check that the bci found is bracketed by terminators. 2690 break; 2691 } 2692 found = strstr(found + 1, buffer); 2693 } 2694 if (!found) { 2695 continue; 2696 } 2697 } 2698 2699 if (DebugDeoptimization && !deopt) { 2700 deopt = true; // One-time only print before deopt 2701 tty->print_cr("[BEFORE Deoptimization]"); 2702 trace_frames(); 2703 trace_stack(); 2704 } 2705 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2706 } 2707 } 2708 2709 if (DebugDeoptimization && deopt) { 2710 tty->print_cr("[AFTER Deoptimization]"); 2711 trace_frames(); 2712 } 2713 } 2714 2715 2716 // Make zombies 2717 void JavaThread::make_zombies() { 2718 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2719 if (fst.current()->can_be_deoptimized()) { 2720 // it is a Java nmethod 2721 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2722 nm->make_not_entrant(); 2723 } 2724 } 2725 } 2726 #endif // PRODUCT 2727 2728 2729 void JavaThread::deoptimized_wrt_marked_nmethods() { 2730 if (!has_last_Java_frame()) return; 2731 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2732 StackFrameStream fst(this, UseBiasedLocking); 2733 for (; !fst.is_done(); fst.next()) { 2734 if (fst.current()->should_be_deoptimized()) { 2735 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2736 } 2737 } 2738 } 2739 2740 2741 // If the caller is a NamedThread, then remember, in the current scope, 2742 // the given JavaThread in its _processed_thread field. 2743 class RememberProcessedThread: public StackObj { 2744 NamedThread* _cur_thr; 2745 public: 2746 RememberProcessedThread(JavaThread* jthr) { 2747 Thread* thread = Thread::current(); 2748 if (thread->is_Named_thread()) { 2749 _cur_thr = (NamedThread *)thread; 2750 _cur_thr->set_processed_thread(jthr); 2751 } else { 2752 _cur_thr = NULL; 2753 } 2754 } 2755 2756 ~RememberProcessedThread() { 2757 if (_cur_thr) { 2758 _cur_thr->set_processed_thread(NULL); 2759 } 2760 } 2761 }; 2762 2763 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2764 // Verify that the deferred card marks have been flushed. 2765 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2766 2767 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2768 // since there may be more than one thread using each ThreadProfiler. 2769 2770 // Traverse the GCHandles 2771 Thread::oops_do(f, cld_f, cf); 2772 2773 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2774 2775 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2776 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2777 2778 if (has_last_Java_frame()) { 2779 // Record JavaThread to GC thread 2780 RememberProcessedThread rpt(this); 2781 2782 // Traverse the privileged stack 2783 if (_privileged_stack_top != NULL) { 2784 _privileged_stack_top->oops_do(f); 2785 } 2786 2787 // traverse the registered growable array 2788 if (_array_for_gc != NULL) { 2789 for (int index = 0; index < _array_for_gc->length(); index++) { 2790 f->do_oop(_array_for_gc->adr_at(index)); 2791 } 2792 } 2793 2794 // Traverse the monitor chunks 2795 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2796 chunk->oops_do(f); 2797 } 2798 2799 // Traverse the execution stack 2800 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2801 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2802 } 2803 } 2804 2805 // callee_target is never live across a gc point so NULL it here should 2806 // it still contain a methdOop. 2807 2808 set_callee_target(NULL); 2809 2810 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2811 // If we have deferred set_locals there might be oops waiting to be 2812 // written 2813 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2814 if (list != NULL) { 2815 for (int i = 0; i < list->length(); i++) { 2816 list->at(i)->oops_do(f); 2817 } 2818 } 2819 2820 // Traverse instance variables at the end since the GC may be moving things 2821 // around using this function 2822 f->do_oop((oop*) &_threadObj); 2823 f->do_oop((oop*) &_vm_result); 2824 f->do_oop((oop*) &_exception_oop); 2825 f->do_oop((oop*) &_pending_async_exception); 2826 2827 if (jvmti_thread_state() != NULL) { 2828 jvmti_thread_state()->oops_do(f); 2829 } 2830 } 2831 2832 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2833 Thread::nmethods_do(cf); // (super method is a no-op) 2834 2835 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2836 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2837 2838 if (has_last_Java_frame()) { 2839 // Traverse the execution stack 2840 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2841 fst.current()->nmethods_do(cf); 2842 } 2843 } 2844 } 2845 2846 void JavaThread::metadata_do(void f(Metadata*)) { 2847 if (has_last_Java_frame()) { 2848 // Traverse the execution stack to call f() on the methods in the stack 2849 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2850 fst.current()->metadata_do(f); 2851 } 2852 } else if (is_Compiler_thread()) { 2853 // need to walk ciMetadata in current compile tasks to keep alive. 2854 CompilerThread* ct = (CompilerThread*)this; 2855 if (ct->env() != NULL) { 2856 ct->env()->metadata_do(f); 2857 } 2858 if (ct->task() != NULL) { 2859 ct->task()->metadata_do(f); 2860 } 2861 } 2862 } 2863 2864 // Printing 2865 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2866 switch (_thread_state) { 2867 case _thread_uninitialized: return "_thread_uninitialized"; 2868 case _thread_new: return "_thread_new"; 2869 case _thread_new_trans: return "_thread_new_trans"; 2870 case _thread_in_native: return "_thread_in_native"; 2871 case _thread_in_native_trans: return "_thread_in_native_trans"; 2872 case _thread_in_vm: return "_thread_in_vm"; 2873 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2874 case _thread_in_Java: return "_thread_in_Java"; 2875 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2876 case _thread_blocked: return "_thread_blocked"; 2877 case _thread_blocked_trans: return "_thread_blocked_trans"; 2878 default: return "unknown thread state"; 2879 } 2880 } 2881 2882 #ifndef PRODUCT 2883 void JavaThread::print_thread_state_on(outputStream *st) const { 2884 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2885 }; 2886 void JavaThread::print_thread_state() const { 2887 print_thread_state_on(tty); 2888 } 2889 #endif // PRODUCT 2890 2891 // Called by Threads::print() for VM_PrintThreads operation 2892 void JavaThread::print_on(outputStream *st) const { 2893 st->print("\"%s\" ", get_thread_name()); 2894 oop thread_oop = threadObj(); 2895 if (thread_oop != NULL) { 2896 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2897 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2898 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2899 } 2900 Thread::print_on(st); 2901 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2902 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2903 if (thread_oop != NULL) { 2904 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2905 } 2906 #ifndef PRODUCT 2907 print_thread_state_on(st); 2908 _safepoint_state->print_on(st); 2909 #endif // PRODUCT 2910 if (is_Compiler_thread()) { 2911 CompilerThread* ct = (CompilerThread*)this; 2912 if (ct->task() != NULL) { 2913 st->print(" Compiling: "); 2914 ct->task()->print(st, NULL, true, false); 2915 } else { 2916 st->print(" No compile task"); 2917 } 2918 st->cr(); 2919 } 2920 } 2921 2922 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2923 st->print("%s", get_thread_name_string(buf, buflen)); 2924 } 2925 2926 // Called by fatal error handler. The difference between this and 2927 // JavaThread::print() is that we can't grab lock or allocate memory. 2928 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2929 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2930 oop thread_obj = threadObj(); 2931 if (thread_obj != NULL) { 2932 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2933 } 2934 st->print(" ["); 2935 st->print("%s", _get_thread_state_name(_thread_state)); 2936 if (osthread()) { 2937 st->print(", id=%d", osthread()->thread_id()); 2938 } 2939 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2940 p2i(stack_end()), p2i(stack_base())); 2941 st->print("]"); 2942 return; 2943 } 2944 2945 // Verification 2946 2947 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2948 2949 void JavaThread::verify() { 2950 // Verify oops in the thread. 2951 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2952 2953 // Verify the stack frames. 2954 frames_do(frame_verify); 2955 } 2956 2957 // CR 6300358 (sub-CR 2137150) 2958 // Most callers of this method assume that it can't return NULL but a 2959 // thread may not have a name whilst it is in the process of attaching to 2960 // the VM - see CR 6412693, and there are places where a JavaThread can be 2961 // seen prior to having it's threadObj set (eg JNI attaching threads and 2962 // if vm exit occurs during initialization). These cases can all be accounted 2963 // for such that this method never returns NULL. 2964 const char* JavaThread::get_thread_name() const { 2965 #ifdef ASSERT 2966 // early safepoints can hit while current thread does not yet have TLS 2967 if (!SafepointSynchronize::is_at_safepoint()) { 2968 Thread *cur = Thread::current(); 2969 if (!(cur->is_Java_thread() && cur == this)) { 2970 // Current JavaThreads are allowed to get their own name without 2971 // the Threads_lock. 2972 assert_locked_or_safepoint(Threads_lock); 2973 } 2974 } 2975 #endif // ASSERT 2976 return get_thread_name_string(); 2977 } 2978 2979 // Returns a non-NULL representation of this thread's name, or a suitable 2980 // descriptive string if there is no set name 2981 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2982 const char* name_str; 2983 oop thread_obj = threadObj(); 2984 if (thread_obj != NULL) { 2985 oop name = java_lang_Thread::name(thread_obj); 2986 if (name != NULL) { 2987 if (buf == NULL) { 2988 name_str = java_lang_String::as_utf8_string(name); 2989 } else { 2990 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2991 } 2992 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2993 name_str = "<no-name - thread is attaching>"; 2994 } else { 2995 name_str = Thread::name(); 2996 } 2997 } else { 2998 name_str = Thread::name(); 2999 } 3000 assert(name_str != NULL, "unexpected NULL thread name"); 3001 return name_str; 3002 } 3003 3004 3005 const char* JavaThread::get_threadgroup_name() const { 3006 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3007 oop thread_obj = threadObj(); 3008 if (thread_obj != NULL) { 3009 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3010 if (thread_group != NULL) { 3011 // ThreadGroup.name can be null 3012 return java_lang_ThreadGroup::name(thread_group); 3013 } 3014 } 3015 return NULL; 3016 } 3017 3018 const char* JavaThread::get_parent_name() const { 3019 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3020 oop thread_obj = threadObj(); 3021 if (thread_obj != NULL) { 3022 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3023 if (thread_group != NULL) { 3024 oop parent = java_lang_ThreadGroup::parent(thread_group); 3025 if (parent != NULL) { 3026 // ThreadGroup.name can be null 3027 return java_lang_ThreadGroup::name(parent); 3028 } 3029 } 3030 } 3031 return NULL; 3032 } 3033 3034 ThreadPriority JavaThread::java_priority() const { 3035 oop thr_oop = threadObj(); 3036 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3037 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3038 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3039 return priority; 3040 } 3041 3042 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3043 3044 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3045 // Link Java Thread object <-> C++ Thread 3046 3047 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3048 // and put it into a new Handle. The Handle "thread_oop" can then 3049 // be used to pass the C++ thread object to other methods. 3050 3051 // Set the Java level thread object (jthread) field of the 3052 // new thread (a JavaThread *) to C++ thread object using the 3053 // "thread_oop" handle. 3054 3055 // Set the thread field (a JavaThread *) of the 3056 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3057 3058 Handle thread_oop(Thread::current(), 3059 JNIHandles::resolve_non_null(jni_thread)); 3060 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3061 "must be initialized"); 3062 set_threadObj(thread_oop()); 3063 java_lang_Thread::set_thread(thread_oop(), this); 3064 3065 if (prio == NoPriority) { 3066 prio = java_lang_Thread::priority(thread_oop()); 3067 assert(prio != NoPriority, "A valid priority should be present"); 3068 } 3069 3070 // Push the Java priority down to the native thread; needs Threads_lock 3071 Thread::set_priority(this, prio); 3072 3073 prepare_ext(); 3074 3075 // Add the new thread to the Threads list and set it in motion. 3076 // We must have threads lock in order to call Threads::add. 3077 // It is crucial that we do not block before the thread is 3078 // added to the Threads list for if a GC happens, then the java_thread oop 3079 // will not be visited by GC. 3080 Threads::add(this); 3081 } 3082 3083 oop JavaThread::current_park_blocker() { 3084 // Support for JSR-166 locks 3085 oop thread_oop = threadObj(); 3086 if (thread_oop != NULL && 3087 JDK_Version::current().supports_thread_park_blocker()) { 3088 return java_lang_Thread::park_blocker(thread_oop); 3089 } 3090 return NULL; 3091 } 3092 3093 3094 void JavaThread::print_stack_on(outputStream* st) { 3095 if (!has_last_Java_frame()) return; 3096 ResourceMark rm; 3097 HandleMark hm; 3098 3099 RegisterMap reg_map(this); 3100 vframe* start_vf = last_java_vframe(®_map); 3101 int count = 0; 3102 for (vframe* f = start_vf; f; f = f->sender()) { 3103 if (f->is_java_frame()) { 3104 javaVFrame* jvf = javaVFrame::cast(f); 3105 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3106 3107 // Print out lock information 3108 if (JavaMonitorsInStackTrace) { 3109 jvf->print_lock_info_on(st, count); 3110 } 3111 } else { 3112 // Ignore non-Java frames 3113 } 3114 3115 // Bail-out case for too deep stacks 3116 count++; 3117 if (MaxJavaStackTraceDepth == count) return; 3118 } 3119 } 3120 3121 3122 // JVMTI PopFrame support 3123 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3124 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3125 if (in_bytes(size_in_bytes) != 0) { 3126 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3127 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3128 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3129 } 3130 } 3131 3132 void* JavaThread::popframe_preserved_args() { 3133 return _popframe_preserved_args; 3134 } 3135 3136 ByteSize JavaThread::popframe_preserved_args_size() { 3137 return in_ByteSize(_popframe_preserved_args_size); 3138 } 3139 3140 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3141 int sz = in_bytes(popframe_preserved_args_size()); 3142 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3143 return in_WordSize(sz / wordSize); 3144 } 3145 3146 void JavaThread::popframe_free_preserved_args() { 3147 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3148 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3149 _popframe_preserved_args = NULL; 3150 _popframe_preserved_args_size = 0; 3151 } 3152 3153 #ifndef PRODUCT 3154 3155 void JavaThread::trace_frames() { 3156 tty->print_cr("[Describe stack]"); 3157 int frame_no = 1; 3158 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3159 tty->print(" %d. ", frame_no++); 3160 fst.current()->print_value_on(tty, this); 3161 tty->cr(); 3162 } 3163 } 3164 3165 class PrintAndVerifyOopClosure: public OopClosure { 3166 protected: 3167 template <class T> inline void do_oop_work(T* p) { 3168 oop obj = oopDesc::load_decode_heap_oop(p); 3169 if (obj == NULL) return; 3170 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3171 if (obj->is_oop_or_null()) { 3172 if (obj->is_objArray()) { 3173 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3174 } else { 3175 obj->print(); 3176 } 3177 } else { 3178 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3179 } 3180 tty->cr(); 3181 } 3182 public: 3183 virtual void do_oop(oop* p) { do_oop_work(p); } 3184 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3185 }; 3186 3187 3188 static void oops_print(frame* f, const RegisterMap *map) { 3189 PrintAndVerifyOopClosure print; 3190 f->print_value(); 3191 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3192 } 3193 3194 // Print our all the locations that contain oops and whether they are 3195 // valid or not. This useful when trying to find the oldest frame 3196 // where an oop has gone bad since the frame walk is from youngest to 3197 // oldest. 3198 void JavaThread::trace_oops() { 3199 tty->print_cr("[Trace oops]"); 3200 frames_do(oops_print); 3201 } 3202 3203 3204 #ifdef ASSERT 3205 // Print or validate the layout of stack frames 3206 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3207 ResourceMark rm; 3208 PRESERVE_EXCEPTION_MARK; 3209 FrameValues values; 3210 int frame_no = 0; 3211 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3212 fst.current()->describe(values, ++frame_no); 3213 if (depth == frame_no) break; 3214 } 3215 if (validate_only) { 3216 values.validate(); 3217 } else { 3218 tty->print_cr("[Describe stack layout]"); 3219 values.print(this); 3220 } 3221 } 3222 #endif 3223 3224 void JavaThread::trace_stack_from(vframe* start_vf) { 3225 ResourceMark rm; 3226 int vframe_no = 1; 3227 for (vframe* f = start_vf; f; f = f->sender()) { 3228 if (f->is_java_frame()) { 3229 javaVFrame::cast(f)->print_activation(vframe_no++); 3230 } else { 3231 f->print(); 3232 } 3233 if (vframe_no > StackPrintLimit) { 3234 tty->print_cr("...<more frames>..."); 3235 return; 3236 } 3237 } 3238 } 3239 3240 3241 void JavaThread::trace_stack() { 3242 if (!has_last_Java_frame()) return; 3243 ResourceMark rm; 3244 HandleMark hm; 3245 RegisterMap reg_map(this); 3246 trace_stack_from(last_java_vframe(®_map)); 3247 } 3248 3249 3250 #endif // PRODUCT 3251 3252 3253 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3254 assert(reg_map != NULL, "a map must be given"); 3255 frame f = last_frame(); 3256 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3257 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3258 } 3259 return NULL; 3260 } 3261 3262 3263 Klass* JavaThread::security_get_caller_class(int depth) { 3264 vframeStream vfst(this); 3265 vfst.security_get_caller_frame(depth); 3266 if (!vfst.at_end()) { 3267 return vfst.method()->method_holder(); 3268 } 3269 return NULL; 3270 } 3271 3272 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3273 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3274 CompileBroker::compiler_thread_loop(); 3275 } 3276 3277 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3278 NMethodSweeper::sweeper_loop(); 3279 } 3280 3281 // Create a CompilerThread 3282 CompilerThread::CompilerThread(CompileQueue* queue, 3283 CompilerCounters* counters) 3284 : JavaThread(&compiler_thread_entry) { 3285 _env = NULL; 3286 _log = NULL; 3287 _task = NULL; 3288 _queue = queue; 3289 _counters = counters; 3290 _buffer_blob = NULL; 3291 _compiler = NULL; 3292 3293 #ifndef PRODUCT 3294 _ideal_graph_printer = NULL; 3295 #endif 3296 } 3297 3298 bool CompilerThread::can_call_java() const { 3299 return _compiler != NULL && _compiler->is_jvmci(); 3300 } 3301 3302 // Create sweeper thread 3303 CodeCacheSweeperThread::CodeCacheSweeperThread() 3304 : JavaThread(&sweeper_thread_entry) { 3305 _scanned_nmethod = NULL; 3306 } 3307 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3308 JavaThread::oops_do(f, cld_f, cf); 3309 if (_scanned_nmethod != NULL && cf != NULL) { 3310 // Safepoints can occur when the sweeper is scanning an nmethod so 3311 // process it here to make sure it isn't unloaded in the middle of 3312 // a scan. 3313 cf->do_code_blob(_scanned_nmethod); 3314 } 3315 } 3316 3317 3318 // ======= Threads ======== 3319 3320 // The Threads class links together all active threads, and provides 3321 // operations over all threads. It is protected by its own Mutex 3322 // lock, which is also used in other contexts to protect thread 3323 // operations from having the thread being operated on from exiting 3324 // and going away unexpectedly (e.g., safepoint synchronization) 3325 3326 JavaThread* Threads::_thread_list = NULL; 3327 int Threads::_number_of_threads = 0; 3328 int Threads::_number_of_non_daemon_threads = 0; 3329 int Threads::_return_code = 0; 3330 int Threads::_thread_claim_parity = 0; 3331 size_t JavaThread::_stack_size_at_create = 0; 3332 #ifdef ASSERT 3333 bool Threads::_vm_complete = false; 3334 #endif 3335 3336 // All JavaThreads 3337 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3338 3339 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3340 void Threads::threads_do(ThreadClosure* tc) { 3341 assert_locked_or_safepoint(Threads_lock); 3342 // ALL_JAVA_THREADS iterates through all JavaThreads 3343 ALL_JAVA_THREADS(p) { 3344 tc->do_thread(p); 3345 } 3346 // Someday we could have a table or list of all non-JavaThreads. 3347 // For now, just manually iterate through them. 3348 tc->do_thread(VMThread::vm_thread()); 3349 Universe::heap()->gc_threads_do(tc); 3350 WatcherThread *wt = WatcherThread::watcher_thread(); 3351 // Strictly speaking, the following NULL check isn't sufficient to make sure 3352 // the data for WatcherThread is still valid upon being examined. However, 3353 // considering that WatchThread terminates when the VM is on the way to 3354 // exit at safepoint, the chance of the above is extremely small. The right 3355 // way to prevent termination of WatcherThread would be to acquire 3356 // Terminator_lock, but we can't do that without violating the lock rank 3357 // checking in some cases. 3358 if (wt != NULL) { 3359 tc->do_thread(wt); 3360 } 3361 3362 // If CompilerThreads ever become non-JavaThreads, add them here 3363 } 3364 3365 // The system initialization in the library has three phases. 3366 // 3367 // Phase 1: java.lang.System class initialization 3368 // java.lang.System is a primordial class loaded and initialized 3369 // by the VM early during startup. java.lang.System.<clinit> 3370 // only does registerNatives and keeps the rest of the class 3371 // initialization work later until thread initialization completes. 3372 // 3373 // System.initPhase1 initializes the system properties, the static 3374 // fields in, out, and err. Set up java signal handlers, OS-specific 3375 // system settings, and thread group of the main thread. 3376 static void call_initPhase1(TRAPS) { 3377 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3378 instanceKlassHandle klass (THREAD, k); 3379 3380 JavaValue result(T_VOID); 3381 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3382 vmSymbols::void_method_signature(), CHECK); 3383 } 3384 3385 // Phase 2. Module system initialization 3386 // This will initialize the module system. Only java.base classes 3387 // can be loaded until phase 2 completes. 3388 // 3389 // Call System.initPhase2 after the compiler initialization and jsr292 3390 // classes get initialized because module initialization runs a lot of java 3391 // code, that for performance reasons, should be compiled. Also, this will 3392 // enable the startup code to use lambda and other language features in this 3393 // phase and onward. 3394 // 3395 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3396 static void call_initPhase2(TRAPS) { 3397 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3398 instanceKlassHandle klass (THREAD, k); 3399 3400 JavaValue result(T_VOID); 3401 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3402 vmSymbols::void_method_signature(), CHECK); 3403 universe_post_module_init(); 3404 } 3405 3406 // Phase 3. final setup - set security manager, system class loader and TCCL 3407 // 3408 // This will instantiate and set the security manager, set the system class 3409 // loader as well as the thread context class loader. The security manager 3410 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3411 // other modules or the application's classpath. 3412 static void call_initPhase3(TRAPS) { 3413 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3414 instanceKlassHandle klass (THREAD, k); 3415 3416 JavaValue result(T_VOID); 3417 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3418 vmSymbols::void_method_signature(), CHECK); 3419 } 3420 3421 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3422 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3423 3424 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3425 create_vm_init_libraries(); 3426 } 3427 3428 initialize_class(vmSymbols::java_lang_String(), CHECK); 3429 3430 // Inject CompactStrings value after the static initializers for String ran. 3431 java_lang_String::set_compact_strings(CompactStrings); 3432 3433 // Initialize java_lang.System (needed before creating the thread) 3434 initialize_class(vmSymbols::java_lang_System(), CHECK); 3435 // The VM creates & returns objects of this class. Make sure it's initialized. 3436 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3437 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3438 Handle thread_group = create_initial_thread_group(CHECK); 3439 Universe::set_main_thread_group(thread_group()); 3440 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3441 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3442 main_thread->set_threadObj(thread_object); 3443 // Set thread status to running since main thread has 3444 // been started and running. 3445 java_lang_Thread::set_thread_status(thread_object, 3446 java_lang_Thread::RUNNABLE); 3447 3448 // The VM creates objects of this class. 3449 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK); 3450 3451 // The VM preresolves methods to these classes. Make sure that they get initialized 3452 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3453 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3454 3455 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3456 call_initPhase1(CHECK); 3457 3458 // get the Java runtime name after java.lang.System is initialized 3459 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3460 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3461 3462 // an instance of OutOfMemory exception has been allocated earlier 3463 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3464 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3465 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3466 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3467 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3468 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3469 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3470 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3471 } 3472 3473 void Threads::initialize_jsr292_core_classes(TRAPS) { 3474 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3475 3476 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3477 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3478 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3479 } 3480 3481 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3482 extern void JDK_Version_init(); 3483 3484 // Preinitialize version info. 3485 VM_Version::early_initialize(); 3486 3487 // Check version 3488 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3489 3490 // Initialize library-based TLS 3491 ThreadLocalStorage::init(); 3492 3493 // Initialize the output stream module 3494 ostream_init(); 3495 3496 // Process java launcher properties. 3497 Arguments::process_sun_java_launcher_properties(args); 3498 3499 // Initialize the os module 3500 os::init(); 3501 3502 // Record VM creation timing statistics 3503 TraceVmCreationTime create_vm_timer; 3504 create_vm_timer.start(); 3505 3506 // Initialize system properties. 3507 Arguments::init_system_properties(); 3508 3509 // So that JDK version can be used as a discriminator when parsing arguments 3510 JDK_Version_init(); 3511 3512 // Update/Initialize System properties after JDK version number is known 3513 Arguments::init_version_specific_system_properties(); 3514 3515 // Make sure to initialize log configuration *before* parsing arguments 3516 LogConfiguration::initialize(create_vm_timer.begin_time()); 3517 3518 // Parse arguments 3519 jint parse_result = Arguments::parse(args); 3520 if (parse_result != JNI_OK) return parse_result; 3521 3522 os::init_before_ergo(); 3523 3524 jint ergo_result = Arguments::apply_ergo(); 3525 if (ergo_result != JNI_OK) return ergo_result; 3526 3527 // Final check of all ranges after ergonomics which may change values. 3528 if (!CommandLineFlagRangeList::check_ranges()) { 3529 return JNI_EINVAL; 3530 } 3531 3532 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3533 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3534 if (!constraint_result) { 3535 return JNI_EINVAL; 3536 } 3537 3538 if (PauseAtStartup) { 3539 os::pause(); 3540 } 3541 3542 HOTSPOT_VM_INIT_BEGIN(); 3543 3544 // Timing (must come after argument parsing) 3545 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3546 3547 // Initialize the os module after parsing the args 3548 jint os_init_2_result = os::init_2(); 3549 if (os_init_2_result != JNI_OK) return os_init_2_result; 3550 3551 jint adjust_after_os_result = Arguments::adjust_after_os(); 3552 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3553 3554 // Initialize output stream logging 3555 ostream_init_log(); 3556 3557 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3558 // Must be before create_vm_init_agents() 3559 if (Arguments::init_libraries_at_startup()) { 3560 convert_vm_init_libraries_to_agents(); 3561 } 3562 3563 // Launch -agentlib/-agentpath and converted -Xrun agents 3564 if (Arguments::init_agents_at_startup()) { 3565 create_vm_init_agents(); 3566 } 3567 3568 // Initialize Threads state 3569 _thread_list = NULL; 3570 _number_of_threads = 0; 3571 _number_of_non_daemon_threads = 0; 3572 3573 // Initialize global data structures and create system classes in heap 3574 vm_init_globals(); 3575 3576 #if INCLUDE_JVMCI 3577 if (JVMCICounterSize > 0) { 3578 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3579 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3580 } else { 3581 JavaThread::_jvmci_old_thread_counters = NULL; 3582 } 3583 #endif // INCLUDE_JVMCI 3584 3585 // Attach the main thread to this os thread 3586 JavaThread* main_thread = new JavaThread(); 3587 main_thread->set_thread_state(_thread_in_vm); 3588 main_thread->initialize_thread_current(); 3589 // must do this before set_active_handles 3590 main_thread->record_stack_base_and_size(); 3591 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3592 3593 if (!main_thread->set_as_starting_thread()) { 3594 vm_shutdown_during_initialization( 3595 "Failed necessary internal allocation. Out of swap space"); 3596 delete main_thread; 3597 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3598 return JNI_ENOMEM; 3599 } 3600 3601 // Enable guard page *after* os::create_main_thread(), otherwise it would 3602 // crash Linux VM, see notes in os_linux.cpp. 3603 main_thread->create_stack_guard_pages(); 3604 3605 // Initialize Java-Level synchronization subsystem 3606 ObjectMonitor::Initialize(); 3607 3608 // Initialize global modules 3609 jint status = init_globals(); 3610 if (status != JNI_OK) { 3611 delete main_thread; 3612 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3613 return status; 3614 } 3615 3616 if (TRACE_INITIALIZE() != JNI_OK) { 3617 vm_exit_during_initialization("Failed to initialize tracing backend"); 3618 } 3619 3620 // Should be done after the heap is fully created 3621 main_thread->cache_global_variables(); 3622 3623 HandleMark hm; 3624 3625 { MutexLocker mu(Threads_lock); 3626 Threads::add(main_thread); 3627 } 3628 3629 // Any JVMTI raw monitors entered in onload will transition into 3630 // real raw monitor. VM is setup enough here for raw monitor enter. 3631 JvmtiExport::transition_pending_onload_raw_monitors(); 3632 3633 // Create the VMThread 3634 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3635 3636 VMThread::create(); 3637 Thread* vmthread = VMThread::vm_thread(); 3638 3639 if (!os::create_thread(vmthread, os::vm_thread)) { 3640 vm_exit_during_initialization("Cannot create VM thread. " 3641 "Out of system resources."); 3642 } 3643 3644 // Wait for the VM thread to become ready, and VMThread::run to initialize 3645 // Monitors can have spurious returns, must always check another state flag 3646 { 3647 MutexLocker ml(Notify_lock); 3648 os::start_thread(vmthread); 3649 while (vmthread->active_handles() == NULL) { 3650 Notify_lock->wait(); 3651 } 3652 } 3653 } 3654 3655 assert(Universe::is_fully_initialized(), "not initialized"); 3656 if (VerifyDuringStartup) { 3657 // Make sure we're starting with a clean slate. 3658 VM_Verify verify_op; 3659 VMThread::execute(&verify_op); 3660 } 3661 3662 Thread* THREAD = Thread::current(); 3663 3664 // At this point, the Universe is initialized, but we have not executed 3665 // any byte code. Now is a good time (the only time) to dump out the 3666 // internal state of the JVM for sharing. 3667 if (DumpSharedSpaces) { 3668 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3669 ShouldNotReachHere(); 3670 } 3671 3672 // Always call even when there are not JVMTI environments yet, since environments 3673 // may be attached late and JVMTI must track phases of VM execution 3674 JvmtiExport::enter_early_start_phase(); 3675 3676 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3677 JvmtiExport::post_early_vm_start(); 3678 3679 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3680 3681 // We need this for ClassDataSharing - the initial vm.info property is set 3682 // with the default value of CDS "sharing" which may be reset through 3683 // command line options. 3684 reset_vm_info_property(CHECK_JNI_ERR); 3685 3686 quicken_jni_functions(); 3687 3688 // No more stub generation allowed after that point. 3689 StubCodeDesc::freeze(); 3690 3691 // Set flag that basic initialization has completed. Used by exceptions and various 3692 // debug stuff, that does not work until all basic classes have been initialized. 3693 set_init_completed(); 3694 3695 LogConfiguration::post_initialize(); 3696 Metaspace::post_initialize(); 3697 3698 HOTSPOT_VM_INIT_END(); 3699 3700 // record VM initialization completion time 3701 #if INCLUDE_MANAGEMENT 3702 Management::record_vm_init_completed(); 3703 #endif // INCLUDE_MANAGEMENT 3704 3705 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3706 // set_init_completed has just been called, causing exceptions not to be shortcut 3707 // anymore. We call vm_exit_during_initialization directly instead. 3708 3709 // Initialize reference pending list locker 3710 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread(); 3711 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR); 3712 3713 // Signal Dispatcher needs to be started before VMInit event is posted 3714 os::signal_init(); 3715 3716 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3717 if (!DisableAttachMechanism) { 3718 AttachListener::vm_start(); 3719 if (StartAttachListener || AttachListener::init_at_startup()) { 3720 AttachListener::init(); 3721 } 3722 } 3723 3724 // Launch -Xrun agents 3725 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3726 // back-end can launch with -Xdebug -Xrunjdwp. 3727 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3728 create_vm_init_libraries(); 3729 } 3730 3731 if (CleanChunkPoolAsync) { 3732 Chunk::start_chunk_pool_cleaner_task(); 3733 } 3734 3735 // initialize compiler(s) 3736 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3737 CompileBroker::compilation_init(CHECK_JNI_ERR); 3738 #endif 3739 3740 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3741 // It is done after compilers are initialized, because otherwise compilations of 3742 // signature polymorphic MH intrinsics can be missed 3743 // (see SystemDictionary::find_method_handle_intrinsic). 3744 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3745 3746 // This will initialize the module system. Only java.base classes can be 3747 // loaded until phase 2 completes 3748 call_initPhase2(CHECK_JNI_ERR); 3749 3750 // Always call even when there are not JVMTI environments yet, since environments 3751 // may be attached late and JVMTI must track phases of VM execution 3752 JvmtiExport::enter_start_phase(); 3753 3754 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3755 JvmtiExport::post_vm_start(); 3756 3757 // Final system initialization including security manager and system class loader 3758 call_initPhase3(CHECK_JNI_ERR); 3759 3760 // cache the system class loader 3761 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3762 3763 // Always call even when there are not JVMTI environments yet, since environments 3764 // may be attached late and JVMTI must track phases of VM execution 3765 JvmtiExport::enter_live_phase(); 3766 3767 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3768 JvmtiExport::post_vm_initialized(); 3769 3770 if (TRACE_START() != JNI_OK) { 3771 vm_exit_during_initialization("Failed to start tracing backend."); 3772 } 3773 3774 #if INCLUDE_MANAGEMENT 3775 Management::initialize(THREAD); 3776 3777 if (HAS_PENDING_EXCEPTION) { 3778 // management agent fails to start possibly due to 3779 // configuration problem and is responsible for printing 3780 // stack trace if appropriate. Simply exit VM. 3781 vm_exit(1); 3782 } 3783 #endif // INCLUDE_MANAGEMENT 3784 3785 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3786 if (MemProfiling) MemProfiler::engage(); 3787 StatSampler::engage(); 3788 if (CheckJNICalls) JniPeriodicChecker::engage(); 3789 3790 BiasedLocking::init(); 3791 3792 #if INCLUDE_RTM_OPT 3793 RTMLockingCounters::init(); 3794 #endif 3795 3796 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3797 call_postVMInitHook(THREAD); 3798 // The Java side of PostVMInitHook.run must deal with all 3799 // exceptions and provide means of diagnosis. 3800 if (HAS_PENDING_EXCEPTION) { 3801 CLEAR_PENDING_EXCEPTION; 3802 } 3803 } 3804 3805 { 3806 MutexLocker ml(PeriodicTask_lock); 3807 // Make sure the WatcherThread can be started by WatcherThread::start() 3808 // or by dynamic enrollment. 3809 WatcherThread::make_startable(); 3810 // Start up the WatcherThread if there are any periodic tasks 3811 // NOTE: All PeriodicTasks should be registered by now. If they 3812 // aren't, late joiners might appear to start slowly (we might 3813 // take a while to process their first tick). 3814 if (PeriodicTask::num_tasks() > 0) { 3815 WatcherThread::start(); 3816 } 3817 } 3818 3819 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM); 3820 3821 create_vm_timer.end(); 3822 #ifdef ASSERT 3823 _vm_complete = true; 3824 #endif 3825 return JNI_OK; 3826 } 3827 3828 // type for the Agent_OnLoad and JVM_OnLoad entry points 3829 extern "C" { 3830 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3831 } 3832 // Find a command line agent library and return its entry point for 3833 // -agentlib: -agentpath: -Xrun 3834 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3835 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3836 const char *on_load_symbols[], 3837 size_t num_symbol_entries) { 3838 OnLoadEntry_t on_load_entry = NULL; 3839 void *library = NULL; 3840 3841 if (!agent->valid()) { 3842 char buffer[JVM_MAXPATHLEN]; 3843 char ebuf[1024] = ""; 3844 const char *name = agent->name(); 3845 const char *msg = "Could not find agent library "; 3846 3847 // First check to see if agent is statically linked into executable 3848 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3849 library = agent->os_lib(); 3850 } else if (agent->is_absolute_path()) { 3851 library = os::dll_load(name, ebuf, sizeof ebuf); 3852 if (library == NULL) { 3853 const char *sub_msg = " in absolute path, with error: "; 3854 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3855 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3856 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3857 // If we can't find the agent, exit. 3858 vm_exit_during_initialization(buf, NULL); 3859 FREE_C_HEAP_ARRAY(char, buf); 3860 } 3861 } else { 3862 // Try to load the agent from the standard dll directory 3863 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3864 name)) { 3865 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3866 } 3867 if (library == NULL) { // Try the local directory 3868 char ns[1] = {0}; 3869 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3870 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3871 } 3872 if (library == NULL) { 3873 const char *sub_msg = " on the library path, with error: "; 3874 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3875 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3876 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3877 // If we can't find the agent, exit. 3878 vm_exit_during_initialization(buf, NULL); 3879 FREE_C_HEAP_ARRAY(char, buf); 3880 } 3881 } 3882 } 3883 agent->set_os_lib(library); 3884 agent->set_valid(); 3885 } 3886 3887 // Find the OnLoad function. 3888 on_load_entry = 3889 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3890 false, 3891 on_load_symbols, 3892 num_symbol_entries)); 3893 return on_load_entry; 3894 } 3895 3896 // Find the JVM_OnLoad entry point 3897 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3898 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3899 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3900 } 3901 3902 // Find the Agent_OnLoad entry point 3903 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3904 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3905 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3906 } 3907 3908 // For backwards compatibility with -Xrun 3909 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3910 // treated like -agentpath: 3911 // Must be called before agent libraries are created 3912 void Threads::convert_vm_init_libraries_to_agents() { 3913 AgentLibrary* agent; 3914 AgentLibrary* next; 3915 3916 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3917 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3918 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3919 3920 // If there is an JVM_OnLoad function it will get called later, 3921 // otherwise see if there is an Agent_OnLoad 3922 if (on_load_entry == NULL) { 3923 on_load_entry = lookup_agent_on_load(agent); 3924 if (on_load_entry != NULL) { 3925 // switch it to the agent list -- so that Agent_OnLoad will be called, 3926 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3927 Arguments::convert_library_to_agent(agent); 3928 } else { 3929 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3930 } 3931 } 3932 } 3933 } 3934 3935 // Create agents for -agentlib: -agentpath: and converted -Xrun 3936 // Invokes Agent_OnLoad 3937 // Called very early -- before JavaThreads exist 3938 void Threads::create_vm_init_agents() { 3939 extern struct JavaVM_ main_vm; 3940 AgentLibrary* agent; 3941 3942 JvmtiExport::enter_onload_phase(); 3943 3944 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3945 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3946 3947 if (on_load_entry != NULL) { 3948 // Invoke the Agent_OnLoad function 3949 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3950 if (err != JNI_OK) { 3951 vm_exit_during_initialization("agent library failed to init", agent->name()); 3952 } 3953 } else { 3954 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3955 } 3956 } 3957 JvmtiExport::enter_primordial_phase(); 3958 } 3959 3960 extern "C" { 3961 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3962 } 3963 3964 void Threads::shutdown_vm_agents() { 3965 // Send any Agent_OnUnload notifications 3966 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3967 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3968 extern struct JavaVM_ main_vm; 3969 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3970 3971 // Find the Agent_OnUnload function. 3972 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3973 os::find_agent_function(agent, 3974 false, 3975 on_unload_symbols, 3976 num_symbol_entries)); 3977 3978 // Invoke the Agent_OnUnload function 3979 if (unload_entry != NULL) { 3980 JavaThread* thread = JavaThread::current(); 3981 ThreadToNativeFromVM ttn(thread); 3982 HandleMark hm(thread); 3983 (*unload_entry)(&main_vm); 3984 } 3985 } 3986 } 3987 3988 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3989 // Invokes JVM_OnLoad 3990 void Threads::create_vm_init_libraries() { 3991 extern struct JavaVM_ main_vm; 3992 AgentLibrary* agent; 3993 3994 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3995 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3996 3997 if (on_load_entry != NULL) { 3998 // Invoke the JVM_OnLoad function 3999 JavaThread* thread = JavaThread::current(); 4000 ThreadToNativeFromVM ttn(thread); 4001 HandleMark hm(thread); 4002 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4003 if (err != JNI_OK) { 4004 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4005 } 4006 } else { 4007 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4008 } 4009 } 4010 } 4011 4012 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4013 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4014 4015 JavaThread* java_thread = NULL; 4016 // Sequential search for now. Need to do better optimization later. 4017 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4018 oop tobj = thread->threadObj(); 4019 if (!thread->is_exiting() && 4020 tobj != NULL && 4021 java_tid == java_lang_Thread::thread_id(tobj)) { 4022 java_thread = thread; 4023 break; 4024 } 4025 } 4026 return java_thread; 4027 } 4028 4029 4030 // Last thread running calls java.lang.Shutdown.shutdown() 4031 void JavaThread::invoke_shutdown_hooks() { 4032 HandleMark hm(this); 4033 4034 // We could get here with a pending exception, if so clear it now. 4035 if (this->has_pending_exception()) { 4036 this->clear_pending_exception(); 4037 } 4038 4039 EXCEPTION_MARK; 4040 Klass* k = 4041 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4042 THREAD); 4043 if (k != NULL) { 4044 // SystemDictionary::resolve_or_null will return null if there was 4045 // an exception. If we cannot load the Shutdown class, just don't 4046 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4047 // and finalizers (if runFinalizersOnExit is set) won't be run. 4048 // Note that if a shutdown hook was registered or runFinalizersOnExit 4049 // was called, the Shutdown class would have already been loaded 4050 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4051 instanceKlassHandle shutdown_klass (THREAD, k); 4052 JavaValue result(T_VOID); 4053 JavaCalls::call_static(&result, 4054 shutdown_klass, 4055 vmSymbols::shutdown_method_name(), 4056 vmSymbols::void_method_signature(), 4057 THREAD); 4058 } 4059 CLEAR_PENDING_EXCEPTION; 4060 } 4061 4062 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4063 // the program falls off the end of main(). Another VM exit path is through 4064 // vm_exit() when the program calls System.exit() to return a value or when 4065 // there is a serious error in VM. The two shutdown paths are not exactly 4066 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4067 // and VM_Exit op at VM level. 4068 // 4069 // Shutdown sequence: 4070 // + Shutdown native memory tracking if it is on 4071 // + Wait until we are the last non-daemon thread to execute 4072 // <-- every thing is still working at this moment --> 4073 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4074 // shutdown hooks, run finalizers if finalization-on-exit 4075 // + Call before_exit(), prepare for VM exit 4076 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4077 // currently the only user of this mechanism is File.deleteOnExit()) 4078 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4079 // post thread end and vm death events to JVMTI, 4080 // stop signal thread 4081 // + Call JavaThread::exit(), it will: 4082 // > release JNI handle blocks, remove stack guard pages 4083 // > remove this thread from Threads list 4084 // <-- no more Java code from this thread after this point --> 4085 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4086 // the compiler threads at safepoint 4087 // <-- do not use anything that could get blocked by Safepoint --> 4088 // + Disable tracing at JNI/JVM barriers 4089 // + Set _vm_exited flag for threads that are still running native code 4090 // + Delete this thread 4091 // + Call exit_globals() 4092 // > deletes tty 4093 // > deletes PerfMemory resources 4094 // + Return to caller 4095 4096 bool Threads::destroy_vm() { 4097 JavaThread* thread = JavaThread::current(); 4098 4099 #ifdef ASSERT 4100 _vm_complete = false; 4101 #endif 4102 // Wait until we are the last non-daemon thread to execute 4103 { MutexLocker nu(Threads_lock); 4104 while (Threads::number_of_non_daemon_threads() > 1) 4105 // This wait should make safepoint checks, wait without a timeout, 4106 // and wait as a suspend-equivalent condition. 4107 // 4108 // Note: If the FlatProfiler is running and this thread is waiting 4109 // for another non-daemon thread to finish, then the FlatProfiler 4110 // is waiting for the external suspend request on this thread to 4111 // complete. wait_for_ext_suspend_completion() will eventually 4112 // timeout, but that takes time. Making this wait a suspend- 4113 // equivalent condition solves that timeout problem. 4114 // 4115 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4116 Mutex::_as_suspend_equivalent_flag); 4117 } 4118 4119 // Hang forever on exit if we are reporting an error. 4120 if (ShowMessageBoxOnError && is_error_reported()) { 4121 os::infinite_sleep(); 4122 } 4123 os::wait_for_keypress_at_exit(); 4124 4125 // run Java level shutdown hooks 4126 thread->invoke_shutdown_hooks(); 4127 4128 before_exit(thread); 4129 4130 thread->exit(true); 4131 4132 // Stop VM thread. 4133 { 4134 // 4945125 The vm thread comes to a safepoint during exit. 4135 // GC vm_operations can get caught at the safepoint, and the 4136 // heap is unparseable if they are caught. Grab the Heap_lock 4137 // to prevent this. The GC vm_operations will not be able to 4138 // queue until after the vm thread is dead. After this point, 4139 // we'll never emerge out of the safepoint before the VM exits. 4140 4141 MutexLocker ml(Heap_lock); 4142 4143 VMThread::wait_for_vm_thread_exit(); 4144 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4145 VMThread::destroy(); 4146 } 4147 4148 // clean up ideal graph printers 4149 #if defined(COMPILER2) && !defined(PRODUCT) 4150 IdealGraphPrinter::clean_up(); 4151 #endif 4152 4153 // Now, all Java threads are gone except daemon threads. Daemon threads 4154 // running Java code or in VM are stopped by the Safepoint. However, 4155 // daemon threads executing native code are still running. But they 4156 // will be stopped at native=>Java/VM barriers. Note that we can't 4157 // simply kill or suspend them, as it is inherently deadlock-prone. 4158 4159 VM_Exit::set_vm_exited(); 4160 4161 notify_vm_shutdown(); 4162 4163 delete thread; 4164 4165 #if INCLUDE_JVMCI 4166 if (JVMCICounterSize > 0) { 4167 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4168 } 4169 #endif 4170 4171 // exit_globals() will delete tty 4172 exit_globals(); 4173 4174 LogConfiguration::finalize(); 4175 4176 return true; 4177 } 4178 4179 4180 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4181 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4182 return is_supported_jni_version(version); 4183 } 4184 4185 4186 jboolean Threads::is_supported_jni_version(jint version) { 4187 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4188 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4189 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4190 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4191 if (version == JNI_VERSION_9) return JNI_TRUE; 4192 return JNI_FALSE; 4193 } 4194 4195 4196 void Threads::add(JavaThread* p, bool force_daemon) { 4197 // The threads lock must be owned at this point 4198 assert_locked_or_safepoint(Threads_lock); 4199 4200 // See the comment for this method in thread.hpp for its purpose and 4201 // why it is called here. 4202 p->initialize_queues(); 4203 p->set_next(_thread_list); 4204 _thread_list = p; 4205 _number_of_threads++; 4206 oop threadObj = p->threadObj(); 4207 bool daemon = true; 4208 // Bootstrapping problem: threadObj can be null for initial 4209 // JavaThread (or for threads attached via JNI) 4210 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4211 _number_of_non_daemon_threads++; 4212 daemon = false; 4213 } 4214 4215 ThreadService::add_thread(p, daemon); 4216 4217 // Possible GC point. 4218 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4219 } 4220 4221 void Threads::remove(JavaThread* p) { 4222 // Extra scope needed for Thread_lock, so we can check 4223 // that we do not remove thread without safepoint code notice 4224 { MutexLocker ml(Threads_lock); 4225 4226 assert(includes(p), "p must be present"); 4227 4228 JavaThread* current = _thread_list; 4229 JavaThread* prev = NULL; 4230 4231 while (current != p) { 4232 prev = current; 4233 current = current->next(); 4234 } 4235 4236 if (prev) { 4237 prev->set_next(current->next()); 4238 } else { 4239 _thread_list = p->next(); 4240 } 4241 _number_of_threads--; 4242 oop threadObj = p->threadObj(); 4243 bool daemon = true; 4244 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4245 _number_of_non_daemon_threads--; 4246 daemon = false; 4247 4248 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4249 // on destroy_vm will wake up. 4250 if (number_of_non_daemon_threads() == 1) { 4251 Threads_lock->notify_all(); 4252 } 4253 } 4254 ThreadService::remove_thread(p, daemon); 4255 4256 // Make sure that safepoint code disregard this thread. This is needed since 4257 // the thread might mess around with locks after this point. This can cause it 4258 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4259 // of this thread since it is removed from the queue. 4260 p->set_terminated_value(); 4261 } // unlock Threads_lock 4262 4263 // Since Events::log uses a lock, we grab it outside the Threads_lock 4264 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4265 } 4266 4267 // Threads_lock must be held when this is called (or must be called during a safepoint) 4268 bool Threads::includes(JavaThread* p) { 4269 assert(Threads_lock->is_locked(), "sanity check"); 4270 ALL_JAVA_THREADS(q) { 4271 if (q == p) { 4272 return true; 4273 } 4274 } 4275 return false; 4276 } 4277 4278 // Operations on the Threads list for GC. These are not explicitly locked, 4279 // but the garbage collector must provide a safe context for them to run. 4280 // In particular, these things should never be called when the Threads_lock 4281 // is held by some other thread. (Note: the Safepoint abstraction also 4282 // uses the Threads_lock to guarantee this property. It also makes sure that 4283 // all threads gets blocked when exiting or starting). 4284 4285 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4286 ALL_JAVA_THREADS(p) { 4287 p->oops_do(f, cld_f, cf); 4288 } 4289 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4290 } 4291 4292 void Threads::change_thread_claim_parity() { 4293 // Set the new claim parity. 4294 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4295 "Not in range."); 4296 _thread_claim_parity++; 4297 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4298 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4299 "Not in range."); 4300 } 4301 4302 #ifdef ASSERT 4303 void Threads::assert_all_threads_claimed() { 4304 ALL_JAVA_THREADS(p) { 4305 const int thread_parity = p->oops_do_parity(); 4306 assert((thread_parity == _thread_claim_parity), 4307 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4308 } 4309 } 4310 #endif // ASSERT 4311 4312 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4313 int cp = Threads::thread_claim_parity(); 4314 ALL_JAVA_THREADS(p) { 4315 if (p->claim_oops_do(is_par, cp)) { 4316 p->oops_do(f, cld_f, cf); 4317 } 4318 } 4319 VMThread* vmt = VMThread::vm_thread(); 4320 if (vmt->claim_oops_do(is_par, cp)) { 4321 vmt->oops_do(f, cld_f, cf); 4322 } 4323 } 4324 4325 #if INCLUDE_ALL_GCS 4326 // Used by ParallelScavenge 4327 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4328 ALL_JAVA_THREADS(p) { 4329 q->enqueue(new ThreadRootsTask(p)); 4330 } 4331 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4332 } 4333 4334 // Used by Parallel Old 4335 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4336 ALL_JAVA_THREADS(p) { 4337 q->enqueue(new ThreadRootsMarkingTask(p)); 4338 } 4339 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4340 } 4341 #endif // INCLUDE_ALL_GCS 4342 4343 void Threads::nmethods_do(CodeBlobClosure* cf) { 4344 ALL_JAVA_THREADS(p) { 4345 p->nmethods_do(cf); 4346 } 4347 VMThread::vm_thread()->nmethods_do(cf); 4348 } 4349 4350 void Threads::metadata_do(void f(Metadata*)) { 4351 ALL_JAVA_THREADS(p) { 4352 p->metadata_do(f); 4353 } 4354 } 4355 4356 class ThreadHandlesClosure : public ThreadClosure { 4357 void (*_f)(Metadata*); 4358 public: 4359 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4360 virtual void do_thread(Thread* thread) { 4361 thread->metadata_handles_do(_f); 4362 } 4363 }; 4364 4365 void Threads::metadata_handles_do(void f(Metadata*)) { 4366 // Only walk the Handles in Thread. 4367 ThreadHandlesClosure handles_closure(f); 4368 threads_do(&handles_closure); 4369 } 4370 4371 void Threads::deoptimized_wrt_marked_nmethods() { 4372 ALL_JAVA_THREADS(p) { 4373 p->deoptimized_wrt_marked_nmethods(); 4374 } 4375 } 4376 4377 4378 // Get count Java threads that are waiting to enter the specified monitor. 4379 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4380 address monitor, 4381 bool doLock) { 4382 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4383 "must grab Threads_lock or be at safepoint"); 4384 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4385 4386 int i = 0; 4387 { 4388 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4389 ALL_JAVA_THREADS(p) { 4390 if (!p->can_call_java()) continue; 4391 4392 address pending = (address)p->current_pending_monitor(); 4393 if (pending == monitor) { // found a match 4394 if (i < count) result->append(p); // save the first count matches 4395 i++; 4396 } 4397 } 4398 } 4399 return result; 4400 } 4401 4402 4403 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4404 bool doLock) { 4405 assert(doLock || 4406 Threads_lock->owned_by_self() || 4407 SafepointSynchronize::is_at_safepoint(), 4408 "must grab Threads_lock or be at safepoint"); 4409 4410 // NULL owner means not locked so we can skip the search 4411 if (owner == NULL) return NULL; 4412 4413 { 4414 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4415 ALL_JAVA_THREADS(p) { 4416 // first, see if owner is the address of a Java thread 4417 if (owner == (address)p) return p; 4418 } 4419 } 4420 // Cannot assert on lack of success here since this function may be 4421 // used by code that is trying to report useful problem information 4422 // like deadlock detection. 4423 if (UseHeavyMonitors) return NULL; 4424 4425 // If we didn't find a matching Java thread and we didn't force use of 4426 // heavyweight monitors, then the owner is the stack address of the 4427 // Lock Word in the owning Java thread's stack. 4428 // 4429 JavaThread* the_owner = NULL; 4430 { 4431 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4432 ALL_JAVA_THREADS(q) { 4433 if (q->is_lock_owned(owner)) { 4434 the_owner = q; 4435 break; 4436 } 4437 } 4438 } 4439 // cannot assert on lack of success here; see above comment 4440 return the_owner; 4441 } 4442 4443 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4444 void Threads::print_on(outputStream* st, bool print_stacks, 4445 bool internal_format, bool print_concurrent_locks) { 4446 char buf[32]; 4447 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4448 4449 st->print_cr("Full thread dump %s (%s %s):", 4450 Abstract_VM_Version::vm_name(), 4451 Abstract_VM_Version::vm_release(), 4452 Abstract_VM_Version::vm_info_string()); 4453 st->cr(); 4454 4455 #if INCLUDE_SERVICES 4456 // Dump concurrent locks 4457 ConcurrentLocksDump concurrent_locks; 4458 if (print_concurrent_locks) { 4459 concurrent_locks.dump_at_safepoint(); 4460 } 4461 #endif // INCLUDE_SERVICES 4462 4463 ALL_JAVA_THREADS(p) { 4464 ResourceMark rm; 4465 p->print_on(st); 4466 if (print_stacks) { 4467 if (internal_format) { 4468 p->trace_stack(); 4469 } else { 4470 p->print_stack_on(st); 4471 } 4472 } 4473 st->cr(); 4474 #if INCLUDE_SERVICES 4475 if (print_concurrent_locks) { 4476 concurrent_locks.print_locks_on(p, st); 4477 } 4478 #endif // INCLUDE_SERVICES 4479 } 4480 4481 VMThread::vm_thread()->print_on(st); 4482 st->cr(); 4483 Universe::heap()->print_gc_threads_on(st); 4484 WatcherThread* wt = WatcherThread::watcher_thread(); 4485 if (wt != NULL) { 4486 wt->print_on(st); 4487 st->cr(); 4488 } 4489 st->flush(); 4490 } 4491 4492 // Threads::print_on_error() is called by fatal error handler. It's possible 4493 // that VM is not at safepoint and/or current thread is inside signal handler. 4494 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4495 // memory (even in resource area), it might deadlock the error handler. 4496 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4497 int buflen) { 4498 bool found_current = false; 4499 st->print_cr("Java Threads: ( => current thread )"); 4500 ALL_JAVA_THREADS(thread) { 4501 bool is_current = (current == thread); 4502 found_current = found_current || is_current; 4503 4504 st->print("%s", is_current ? "=>" : " "); 4505 4506 st->print(PTR_FORMAT, p2i(thread)); 4507 st->print(" "); 4508 thread->print_on_error(st, buf, buflen); 4509 st->cr(); 4510 } 4511 st->cr(); 4512 4513 st->print_cr("Other Threads:"); 4514 if (VMThread::vm_thread()) { 4515 bool is_current = (current == VMThread::vm_thread()); 4516 found_current = found_current || is_current; 4517 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4518 4519 st->print(PTR_FORMAT, p2i(VMThread::vm_thread())); 4520 st->print(" "); 4521 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4522 st->cr(); 4523 } 4524 WatcherThread* wt = WatcherThread::watcher_thread(); 4525 if (wt != NULL) { 4526 bool is_current = (current == wt); 4527 found_current = found_current || is_current; 4528 st->print("%s", is_current ? "=>" : " "); 4529 4530 st->print(PTR_FORMAT, p2i(wt)); 4531 st->print(" "); 4532 wt->print_on_error(st, buf, buflen); 4533 st->cr(); 4534 } 4535 if (!found_current) { 4536 st->cr(); 4537 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4538 current->print_on_error(st, buf, buflen); 4539 st->cr(); 4540 } 4541 st->cr(); 4542 st->print_cr("Threads with active compile tasks:"); 4543 print_threads_compiling(st, buf, buflen); 4544 } 4545 4546 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4547 ALL_JAVA_THREADS(thread) { 4548 if (thread->is_Compiler_thread()) { 4549 CompilerThread* ct = (CompilerThread*) thread; 4550 if (ct->task() != NULL) { 4551 thread->print_name_on_error(st, buf, buflen); 4552 ct->task()->print(st, NULL, true, true); 4553 } 4554 } 4555 } 4556 } 4557 4558 4559 // Internal SpinLock and Mutex 4560 // Based on ParkEvent 4561 4562 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4563 // 4564 // We employ SpinLocks _only for low-contention, fixed-length 4565 // short-duration critical sections where we're concerned 4566 // about native mutex_t or HotSpot Mutex:: latency. 4567 // The mux construct provides a spin-then-block mutual exclusion 4568 // mechanism. 4569 // 4570 // Testing has shown that contention on the ListLock guarding gFreeList 4571 // is common. If we implement ListLock as a simple SpinLock it's common 4572 // for the JVM to devolve to yielding with little progress. This is true 4573 // despite the fact that the critical sections protected by ListLock are 4574 // extremely short. 4575 // 4576 // TODO-FIXME: ListLock should be of type SpinLock. 4577 // We should make this a 1st-class type, integrated into the lock 4578 // hierarchy as leaf-locks. Critically, the SpinLock structure 4579 // should have sufficient padding to avoid false-sharing and excessive 4580 // cache-coherency traffic. 4581 4582 4583 typedef volatile int SpinLockT; 4584 4585 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4586 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4587 return; // normal fast-path return 4588 } 4589 4590 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4591 TEVENT(SpinAcquire - ctx); 4592 int ctr = 0; 4593 int Yields = 0; 4594 for (;;) { 4595 while (*adr != 0) { 4596 ++ctr; 4597 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4598 if (Yields > 5) { 4599 os::naked_short_sleep(1); 4600 } else { 4601 os::naked_yield(); 4602 ++Yields; 4603 } 4604 } else { 4605 SpinPause(); 4606 } 4607 } 4608 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4609 } 4610 } 4611 4612 void Thread::SpinRelease(volatile int * adr) { 4613 assert(*adr != 0, "invariant"); 4614 OrderAccess::fence(); // guarantee at least release consistency. 4615 // Roach-motel semantics. 4616 // It's safe if subsequent LDs and STs float "up" into the critical section, 4617 // but prior LDs and STs within the critical section can't be allowed 4618 // to reorder or float past the ST that releases the lock. 4619 // Loads and stores in the critical section - which appear in program 4620 // order before the store that releases the lock - must also appear 4621 // before the store that releases the lock in memory visibility order. 4622 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4623 // the ST of 0 into the lock-word which releases the lock, so fence 4624 // more than covers this on all platforms. 4625 *adr = 0; 4626 } 4627 4628 // muxAcquire and muxRelease: 4629 // 4630 // * muxAcquire and muxRelease support a single-word lock-word construct. 4631 // The LSB of the word is set IFF the lock is held. 4632 // The remainder of the word points to the head of a singly-linked list 4633 // of threads blocked on the lock. 4634 // 4635 // * The current implementation of muxAcquire-muxRelease uses its own 4636 // dedicated Thread._MuxEvent instance. If we're interested in 4637 // minimizing the peak number of extant ParkEvent instances then 4638 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4639 // as certain invariants were satisfied. Specifically, care would need 4640 // to be taken with regards to consuming unpark() "permits". 4641 // A safe rule of thumb is that a thread would never call muxAcquire() 4642 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4643 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4644 // consume an unpark() permit intended for monitorenter, for instance. 4645 // One way around this would be to widen the restricted-range semaphore 4646 // implemented in park(). Another alternative would be to provide 4647 // multiple instances of the PlatformEvent() for each thread. One 4648 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4649 // 4650 // * Usage: 4651 // -- Only as leaf locks 4652 // -- for short-term locking only as muxAcquire does not perform 4653 // thread state transitions. 4654 // 4655 // Alternatives: 4656 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4657 // but with parking or spin-then-park instead of pure spinning. 4658 // * Use Taura-Oyama-Yonenzawa locks. 4659 // * It's possible to construct a 1-0 lock if we encode the lockword as 4660 // (List,LockByte). Acquire will CAS the full lockword while Release 4661 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4662 // acquiring threads use timers (ParkTimed) to detect and recover from 4663 // the stranding window. Thread/Node structures must be aligned on 256-byte 4664 // boundaries by using placement-new. 4665 // * Augment MCS with advisory back-link fields maintained with CAS(). 4666 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4667 // The validity of the backlinks must be ratified before we trust the value. 4668 // If the backlinks are invalid the exiting thread must back-track through the 4669 // the forward links, which are always trustworthy. 4670 // * Add a successor indication. The LockWord is currently encoded as 4671 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4672 // to provide the usual futile-wakeup optimization. 4673 // See RTStt for details. 4674 // * Consider schedctl.sc_nopreempt to cover the critical section. 4675 // 4676 4677 4678 typedef volatile intptr_t MutexT; // Mux Lock-word 4679 enum MuxBits { LOCKBIT = 1 }; 4680 4681 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4682 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4683 if (w == 0) return; 4684 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4685 return; 4686 } 4687 4688 TEVENT(muxAcquire - Contention); 4689 ParkEvent * const Self = Thread::current()->_MuxEvent; 4690 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4691 for (;;) { 4692 int its = (os::is_MP() ? 100 : 0) + 1; 4693 4694 // Optional spin phase: spin-then-park strategy 4695 while (--its >= 0) { 4696 w = *Lock; 4697 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4698 return; 4699 } 4700 } 4701 4702 Self->reset(); 4703 Self->OnList = intptr_t(Lock); 4704 // The following fence() isn't _strictly necessary as the subsequent 4705 // CAS() both serializes execution and ratifies the fetched *Lock value. 4706 OrderAccess::fence(); 4707 for (;;) { 4708 w = *Lock; 4709 if ((w & LOCKBIT) == 0) { 4710 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4711 Self->OnList = 0; // hygiene - allows stronger asserts 4712 return; 4713 } 4714 continue; // Interference -- *Lock changed -- Just retry 4715 } 4716 assert(w & LOCKBIT, "invariant"); 4717 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4718 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4719 } 4720 4721 while (Self->OnList != 0) { 4722 Self->park(); 4723 } 4724 } 4725 } 4726 4727 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4728 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4729 if (w == 0) return; 4730 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4731 return; 4732 } 4733 4734 TEVENT(muxAcquire - Contention); 4735 ParkEvent * ReleaseAfter = NULL; 4736 if (ev == NULL) { 4737 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4738 } 4739 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4740 for (;;) { 4741 guarantee(ev->OnList == 0, "invariant"); 4742 int its = (os::is_MP() ? 100 : 0) + 1; 4743 4744 // Optional spin phase: spin-then-park strategy 4745 while (--its >= 0) { 4746 w = *Lock; 4747 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4748 if (ReleaseAfter != NULL) { 4749 ParkEvent::Release(ReleaseAfter); 4750 } 4751 return; 4752 } 4753 } 4754 4755 ev->reset(); 4756 ev->OnList = intptr_t(Lock); 4757 // The following fence() isn't _strictly necessary as the subsequent 4758 // CAS() both serializes execution and ratifies the fetched *Lock value. 4759 OrderAccess::fence(); 4760 for (;;) { 4761 w = *Lock; 4762 if ((w & LOCKBIT) == 0) { 4763 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4764 ev->OnList = 0; 4765 // We call ::Release while holding the outer lock, thus 4766 // artificially lengthening the critical section. 4767 // Consider deferring the ::Release() until the subsequent unlock(), 4768 // after we've dropped the outer lock. 4769 if (ReleaseAfter != NULL) { 4770 ParkEvent::Release(ReleaseAfter); 4771 } 4772 return; 4773 } 4774 continue; // Interference -- *Lock changed -- Just retry 4775 } 4776 assert(w & LOCKBIT, "invariant"); 4777 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4778 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4779 } 4780 4781 while (ev->OnList != 0) { 4782 ev->park(); 4783 } 4784 } 4785 } 4786 4787 // Release() must extract a successor from the list and then wake that thread. 4788 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4789 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4790 // Release() would : 4791 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4792 // (B) Extract a successor from the private list "in-hand" 4793 // (C) attempt to CAS() the residual back into *Lock over null. 4794 // If there were any newly arrived threads and the CAS() would fail. 4795 // In that case Release() would detach the RATs, re-merge the list in-hand 4796 // with the RATs and repeat as needed. Alternately, Release() might 4797 // detach and extract a successor, but then pass the residual list to the wakee. 4798 // The wakee would be responsible for reattaching and remerging before it 4799 // competed for the lock. 4800 // 4801 // Both "pop" and DMR are immune from ABA corruption -- there can be 4802 // multiple concurrent pushers, but only one popper or detacher. 4803 // This implementation pops from the head of the list. This is unfair, 4804 // but tends to provide excellent throughput as hot threads remain hot. 4805 // (We wake recently run threads first). 4806 // 4807 // All paths through muxRelease() will execute a CAS. 4808 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4809 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4810 // executed within the critical section are complete and globally visible before the 4811 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4812 void Thread::muxRelease(volatile intptr_t * Lock) { 4813 for (;;) { 4814 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4815 assert(w & LOCKBIT, "invariant"); 4816 if (w == LOCKBIT) return; 4817 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4818 assert(List != NULL, "invariant"); 4819 assert(List->OnList == intptr_t(Lock), "invariant"); 4820 ParkEvent * const nxt = List->ListNext; 4821 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4822 4823 // The following CAS() releases the lock and pops the head element. 4824 // The CAS() also ratifies the previously fetched lock-word value. 4825 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4826 continue; 4827 } 4828 List->OnList = 0; 4829 OrderAccess::fence(); 4830 List->unpark(); 4831 return; 4832 } 4833 } 4834 4835 4836 void Threads::verify() { 4837 ALL_JAVA_THREADS(p) { 4838 p->verify(); 4839 } 4840 VMThread* thread = VMThread::vm_thread(); 4841 if (thread != NULL) thread->verify(); 4842 }