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 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 985 instanceKlassHandle klass (THREAD, k); 986 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 987 988 java_lang_Thread::set_thread(thread_oop(), thread); 989 java_lang_Thread::set_priority(thread_oop(), NormPriority); 990 thread->set_threadObj(thread_oop()); 991 992 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 993 994 JavaValue result(T_VOID); 995 JavaCalls::call_special(&result, thread_oop, 996 klass, 997 vmSymbols::object_initializer_name(), 998 vmSymbols::threadgroup_string_void_signature(), 999 thread_group, 1000 string, 1001 CHECK_NULL); 1002 return thread_oop(); 1003 } 1004 1005 char java_runtime_name[128] = ""; 1006 char java_runtime_version[128] = ""; 1007 1008 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1009 static const char* get_java_runtime_name(TRAPS) { 1010 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1011 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1012 fieldDescriptor fd; 1013 bool found = k != NULL && 1014 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1015 vmSymbols::string_signature(), &fd); 1016 if (found) { 1017 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1018 if (name_oop == NULL) { 1019 return NULL; 1020 } 1021 const char* name = java_lang_String::as_utf8_string(name_oop, 1022 java_runtime_name, 1023 sizeof(java_runtime_name)); 1024 return name; 1025 } else { 1026 return NULL; 1027 } 1028 } 1029 1030 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1031 static const char* get_java_runtime_version(TRAPS) { 1032 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1033 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1034 fieldDescriptor fd; 1035 bool found = k != NULL && 1036 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1037 vmSymbols::string_signature(), &fd); 1038 if (found) { 1039 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1040 if (name_oop == NULL) { 1041 return NULL; 1042 } 1043 const char* name = java_lang_String::as_utf8_string(name_oop, 1044 java_runtime_version, 1045 sizeof(java_runtime_version)); 1046 return name; 1047 } else { 1048 return NULL; 1049 } 1050 } 1051 1052 // General purpose hook into Java code, run once when the VM is initialized. 1053 // The Java library method itself may be changed independently from the VM. 1054 static void call_postVMInitHook(TRAPS) { 1055 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); 1056 instanceKlassHandle klass (THREAD, k); 1057 if (klass.not_null()) { 1058 JavaValue result(T_VOID); 1059 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1060 vmSymbols::void_method_signature(), 1061 CHECK); 1062 } 1063 } 1064 1065 static void reset_vm_info_property(TRAPS) { 1066 // the vm info string 1067 ResourceMark rm(THREAD); 1068 const char *vm_info = VM_Version::vm_info_string(); 1069 1070 // java.lang.System class 1071 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1072 instanceKlassHandle klass (THREAD, k); 1073 1074 // setProperty arguments 1075 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1076 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1077 1078 // return value 1079 JavaValue r(T_OBJECT); 1080 1081 // public static String setProperty(String key, String value); 1082 JavaCalls::call_static(&r, 1083 klass, 1084 vmSymbols::setProperty_name(), 1085 vmSymbols::string_string_string_signature(), 1086 key_str, 1087 value_str, 1088 CHECK); 1089 } 1090 1091 1092 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1093 bool daemon, TRAPS) { 1094 assert(thread_group.not_null(), "thread group should be specified"); 1095 assert(threadObj() == NULL, "should only create Java thread object once"); 1096 1097 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1098 instanceKlassHandle klass (THREAD, k); 1099 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1100 1101 java_lang_Thread::set_thread(thread_oop(), this); 1102 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1103 set_threadObj(thread_oop()); 1104 1105 JavaValue result(T_VOID); 1106 if (thread_name != NULL) { 1107 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1108 // Thread gets assigned specified name and null target 1109 JavaCalls::call_special(&result, 1110 thread_oop, 1111 klass, 1112 vmSymbols::object_initializer_name(), 1113 vmSymbols::threadgroup_string_void_signature(), 1114 thread_group, // Argument 1 1115 name, // Argument 2 1116 THREAD); 1117 } else { 1118 // Thread gets assigned name "Thread-nnn" and null target 1119 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1120 JavaCalls::call_special(&result, 1121 thread_oop, 1122 klass, 1123 vmSymbols::object_initializer_name(), 1124 vmSymbols::threadgroup_runnable_void_signature(), 1125 thread_group, // Argument 1 1126 Handle(), // Argument 2 1127 THREAD); 1128 } 1129 1130 1131 if (daemon) { 1132 java_lang_Thread::set_daemon(thread_oop()); 1133 } 1134 1135 if (HAS_PENDING_EXCEPTION) { 1136 return; 1137 } 1138 1139 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass()); 1140 Handle threadObj(THREAD, this->threadObj()); 1141 1142 JavaCalls::call_special(&result, 1143 thread_group, 1144 group, 1145 vmSymbols::add_method_name(), 1146 vmSymbols::thread_void_signature(), 1147 threadObj, // Arg 1 1148 THREAD); 1149 } 1150 1151 // NamedThread -- non-JavaThread subclasses with multiple 1152 // uniquely named instances should derive from this. 1153 NamedThread::NamedThread() : Thread() { 1154 _name = NULL; 1155 _processed_thread = NULL; 1156 _gc_id = GCId::undefined(); 1157 } 1158 1159 NamedThread::~NamedThread() { 1160 if (_name != NULL) { 1161 FREE_C_HEAP_ARRAY(char, _name); 1162 _name = NULL; 1163 } 1164 } 1165 1166 void NamedThread::set_name(const char* format, ...) { 1167 guarantee(_name == NULL, "Only get to set name once."); 1168 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1169 guarantee(_name != NULL, "alloc failure"); 1170 va_list ap; 1171 va_start(ap, format); 1172 jio_vsnprintf(_name, max_name_len, format, ap); 1173 va_end(ap); 1174 } 1175 1176 void NamedThread::initialize_named_thread() { 1177 set_native_thread_name(name()); 1178 } 1179 1180 void NamedThread::print_on(outputStream* st) const { 1181 st->print("\"%s\" ", name()); 1182 Thread::print_on(st); 1183 st->cr(); 1184 } 1185 1186 1187 // ======= WatcherThread ======== 1188 1189 // The watcher thread exists to simulate timer interrupts. It should 1190 // be replaced by an abstraction over whatever native support for 1191 // timer interrupts exists on the platform. 1192 1193 WatcherThread* WatcherThread::_watcher_thread = NULL; 1194 bool WatcherThread::_startable = false; 1195 volatile bool WatcherThread::_should_terminate = false; 1196 1197 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1198 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1199 if (os::create_thread(this, os::watcher_thread)) { 1200 _watcher_thread = this; 1201 1202 // Set the watcher thread to the highest OS priority which should not be 1203 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1204 // is created. The only normal thread using this priority is the reference 1205 // handler thread, which runs for very short intervals only. 1206 // If the VMThread's priority is not lower than the WatcherThread profiling 1207 // will be inaccurate. 1208 os::set_priority(this, MaxPriority); 1209 if (!DisableStartThread) { 1210 os::start_thread(this); 1211 } 1212 } 1213 } 1214 1215 int WatcherThread::sleep() const { 1216 // The WatcherThread does not participate in the safepoint protocol 1217 // for the PeriodicTask_lock because it is not a JavaThread. 1218 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1219 1220 if (_should_terminate) { 1221 // check for termination before we do any housekeeping or wait 1222 return 0; // we did not sleep. 1223 } 1224 1225 // remaining will be zero if there are no tasks, 1226 // causing the WatcherThread to sleep until a task is 1227 // enrolled 1228 int remaining = PeriodicTask::time_to_wait(); 1229 int time_slept = 0; 1230 1231 // we expect this to timeout - we only ever get unparked when 1232 // we should terminate or when a new task has been enrolled 1233 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1234 1235 jlong time_before_loop = os::javaTimeNanos(); 1236 1237 while (true) { 1238 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1239 remaining); 1240 jlong now = os::javaTimeNanos(); 1241 1242 if (remaining == 0) { 1243 // if we didn't have any tasks we could have waited for a long time 1244 // consider the time_slept zero and reset time_before_loop 1245 time_slept = 0; 1246 time_before_loop = now; 1247 } else { 1248 // need to recalculate since we might have new tasks in _tasks 1249 time_slept = (int) ((now - time_before_loop) / 1000000); 1250 } 1251 1252 // Change to task list or spurious wakeup of some kind 1253 if (timedout || _should_terminate) { 1254 break; 1255 } 1256 1257 remaining = PeriodicTask::time_to_wait(); 1258 if (remaining == 0) { 1259 // Last task was just disenrolled so loop around and wait until 1260 // another task gets enrolled 1261 continue; 1262 } 1263 1264 remaining -= time_slept; 1265 if (remaining <= 0) { 1266 break; 1267 } 1268 } 1269 1270 return time_slept; 1271 } 1272 1273 void WatcherThread::run() { 1274 assert(this == watcher_thread(), "just checking"); 1275 1276 this->record_stack_base_and_size(); 1277 this->set_native_thread_name(this->name()); 1278 this->set_active_handles(JNIHandleBlock::allocate_block()); 1279 while (true) { 1280 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1281 assert(watcher_thread() == this, "thread consistency check"); 1282 1283 // Calculate how long it'll be until the next PeriodicTask work 1284 // should be done, and sleep that amount of time. 1285 int time_waited = sleep(); 1286 1287 if (is_error_reported()) { 1288 // A fatal error has happened, the error handler(VMError::report_and_die) 1289 // should abort JVM after creating an error log file. However in some 1290 // rare cases, the error handler itself might deadlock. Here we try to 1291 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1292 // 1293 // This code is in WatcherThread because WatcherThread wakes up 1294 // periodically so the fatal error handler doesn't need to do anything; 1295 // also because the WatcherThread is less likely to crash than other 1296 // threads. 1297 1298 for (;;) { 1299 if (!ShowMessageBoxOnError 1300 && (OnError == NULL || OnError[0] == '\0') 1301 && Arguments::abort_hook() == NULL) { 1302 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds 1303 fdStream err(defaultStream::output_fd()); 1304 err.print_raw_cr("# [ timer expired, abort... ]"); 1305 // skip atexit/vm_exit/vm_abort hooks 1306 os::die(); 1307 } 1308 1309 // Wake up 5 seconds later, the fatal handler may reset OnError or 1310 // ShowMessageBoxOnError when it is ready to abort. 1311 os::sleep(this, 5 * 1000, false); 1312 } 1313 } 1314 1315 if (_should_terminate) { 1316 // check for termination before posting the next tick 1317 break; 1318 } 1319 1320 PeriodicTask::real_time_tick(time_waited); 1321 } 1322 1323 // Signal that it is terminated 1324 { 1325 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1326 _watcher_thread = NULL; 1327 Terminator_lock->notify(); 1328 } 1329 } 1330 1331 void WatcherThread::start() { 1332 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1333 1334 if (watcher_thread() == NULL && _startable) { 1335 _should_terminate = false; 1336 // Create the single instance of WatcherThread 1337 new WatcherThread(); 1338 } 1339 } 1340 1341 void WatcherThread::make_startable() { 1342 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1343 _startable = true; 1344 } 1345 1346 void WatcherThread::stop() { 1347 { 1348 // Follow normal safepoint aware lock enter protocol since the 1349 // WatcherThread is stopped by another JavaThread. 1350 MutexLocker ml(PeriodicTask_lock); 1351 _should_terminate = true; 1352 1353 WatcherThread* watcher = watcher_thread(); 1354 if (watcher != NULL) { 1355 // unpark the WatcherThread so it can see that it should terminate 1356 watcher->unpark(); 1357 } 1358 } 1359 1360 MutexLocker mu(Terminator_lock); 1361 1362 while (watcher_thread() != NULL) { 1363 // This wait should make safepoint checks, wait without a timeout, 1364 // and wait as a suspend-equivalent condition. 1365 // 1366 // Note: If the FlatProfiler is running, then this thread is waiting 1367 // for the WatcherThread to terminate and the WatcherThread, via the 1368 // FlatProfiler task, is waiting for the external suspend request on 1369 // this thread to complete. wait_for_ext_suspend_completion() will 1370 // eventually timeout, but that takes time. Making this wait a 1371 // suspend-equivalent condition solves that timeout problem. 1372 // 1373 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1374 Mutex::_as_suspend_equivalent_flag); 1375 } 1376 } 1377 1378 void WatcherThread::unpark() { 1379 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1380 PeriodicTask_lock->notify(); 1381 } 1382 1383 void WatcherThread::print_on(outputStream* st) const { 1384 st->print("\"%s\" ", name()); 1385 Thread::print_on(st); 1386 st->cr(); 1387 } 1388 1389 // ======= JavaThread ======== 1390 1391 #if INCLUDE_JVMCI 1392 1393 jlong* JavaThread::_jvmci_old_thread_counters; 1394 1395 bool jvmci_counters_include(JavaThread* thread) { 1396 oop threadObj = thread->threadObj(); 1397 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1398 } 1399 1400 void JavaThread::collect_counters(typeArrayOop array) { 1401 if (JVMCICounterSize > 0) { 1402 MutexLocker tl(Threads_lock); 1403 for (int i = 0; i < array->length(); i++) { 1404 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1405 } 1406 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1407 if (jvmci_counters_include(tp)) { 1408 for (int i = 0; i < array->length(); i++) { 1409 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1410 } 1411 } 1412 } 1413 } 1414 } 1415 1416 #endif // INCLUDE_JVMCI 1417 1418 // A JavaThread is a normal Java thread 1419 1420 void JavaThread::initialize() { 1421 // Initialize fields 1422 1423 set_saved_exception_pc(NULL); 1424 set_threadObj(NULL); 1425 _anchor.clear(); 1426 set_entry_point(NULL); 1427 set_jni_functions(jni_functions()); 1428 set_callee_target(NULL); 1429 set_vm_result(NULL); 1430 set_vm_result_2(NULL); 1431 set_vframe_array_head(NULL); 1432 set_vframe_array_last(NULL); 1433 set_deferred_locals(NULL); 1434 set_deopt_mark(NULL); 1435 set_deopt_nmethod(NULL); 1436 clear_must_deopt_id(); 1437 set_monitor_chunks(NULL); 1438 set_next(NULL); 1439 set_thread_state(_thread_new); 1440 _terminated = _not_terminated; 1441 _privileged_stack_top = NULL; 1442 _array_for_gc = NULL; 1443 _suspend_equivalent = false; 1444 _in_deopt_handler = 0; 1445 _doing_unsafe_access = false; 1446 _stack_guard_state = stack_guard_unused; 1447 #if INCLUDE_JVMCI 1448 _pending_monitorenter = false; 1449 _pending_deoptimization = -1; 1450 _pending_failed_speculation = NULL; 1451 _pending_transfer_to_interpreter = false; 1452 _jvmci._alternate_call_target = NULL; 1453 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1454 if (JVMCICounterSize > 0) { 1455 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1456 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1457 } else { 1458 _jvmci_counters = NULL; 1459 } 1460 #endif // INCLUDE_JVMCI 1461 _reserved_stack_activation = NULL; // stack base not known yet 1462 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1463 _exception_pc = 0; 1464 _exception_handler_pc = 0; 1465 _is_method_handle_return = 0; 1466 _jvmti_thread_state= NULL; 1467 _should_post_on_exceptions_flag = JNI_FALSE; 1468 _jvmti_get_loaded_classes_closure = NULL; 1469 _interp_only_mode = 0; 1470 _special_runtime_exit_condition = _no_async_condition; 1471 _pending_async_exception = NULL; 1472 _thread_stat = NULL; 1473 _thread_stat = new ThreadStatistics(); 1474 _blocked_on_compilation = false; 1475 _jni_active_critical = 0; 1476 _pending_jni_exception_check_fn = NULL; 1477 _do_not_unlock_if_synchronized = false; 1478 _cached_monitor_info = NULL; 1479 _parker = Parker::Allocate(this); 1480 1481 #ifndef PRODUCT 1482 _jmp_ring_index = 0; 1483 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1484 record_jump(NULL, NULL, NULL, 0); 1485 } 1486 #endif // PRODUCT 1487 1488 set_thread_profiler(NULL); 1489 if (FlatProfiler::is_active()) { 1490 // This is where we would decide to either give each thread it's own profiler 1491 // or use one global one from FlatProfiler, 1492 // or up to some count of the number of profiled threads, etc. 1493 ThreadProfiler* pp = new ThreadProfiler(); 1494 pp->engage(); 1495 set_thread_profiler(pp); 1496 } 1497 1498 // Setup safepoint state info for this thread 1499 ThreadSafepointState::create(this); 1500 1501 debug_only(_java_call_counter = 0); 1502 1503 // JVMTI PopFrame support 1504 _popframe_condition = popframe_inactive; 1505 _popframe_preserved_args = NULL; 1506 _popframe_preserved_args_size = 0; 1507 _frames_to_pop_failed_realloc = 0; 1508 1509 pd_initialize(); 1510 } 1511 1512 #if INCLUDE_ALL_GCS 1513 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1514 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1515 #endif // INCLUDE_ALL_GCS 1516 1517 JavaThread::JavaThread(bool is_attaching_via_jni) : 1518 Thread() 1519 #if INCLUDE_ALL_GCS 1520 , _satb_mark_queue(&_satb_mark_queue_set), 1521 _dirty_card_queue(&_dirty_card_queue_set) 1522 #endif // INCLUDE_ALL_GCS 1523 { 1524 initialize(); 1525 if (is_attaching_via_jni) { 1526 _jni_attach_state = _attaching_via_jni; 1527 } else { 1528 _jni_attach_state = _not_attaching_via_jni; 1529 } 1530 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1531 } 1532 1533 bool JavaThread::reguard_stack(address cur_sp) { 1534 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1535 && _stack_guard_state != stack_guard_reserved_disabled) { 1536 return true; // Stack already guarded or guard pages not needed. 1537 } 1538 1539 if (register_stack_overflow()) { 1540 // For those architectures which have separate register and 1541 // memory stacks, we must check the register stack to see if 1542 // it has overflowed. 1543 return false; 1544 } 1545 1546 // Java code never executes within the yellow zone: the latter is only 1547 // there to provoke an exception during stack banging. If java code 1548 // is executing there, either StackShadowPages should be larger, or 1549 // some exception code in c1, c2 or the interpreter isn't unwinding 1550 // when it should. 1551 guarantee(cur_sp > stack_reserved_zone_base(), 1552 "not enough space to reguard - increase StackShadowPages"); 1553 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1554 enable_stack_yellow_reserved_zone(); 1555 if (reserved_stack_activation() != stack_base()) { 1556 set_reserved_stack_activation(stack_base()); 1557 } 1558 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1559 set_reserved_stack_activation(stack_base()); 1560 enable_stack_reserved_zone(); 1561 } 1562 return true; 1563 } 1564 1565 bool JavaThread::reguard_stack(void) { 1566 return reguard_stack(os::current_stack_pointer()); 1567 } 1568 1569 1570 void JavaThread::block_if_vm_exited() { 1571 if (_terminated == _vm_exited) { 1572 // _vm_exited is set at safepoint, and Threads_lock is never released 1573 // we will block here forever 1574 Threads_lock->lock_without_safepoint_check(); 1575 ShouldNotReachHere(); 1576 } 1577 } 1578 1579 1580 // Remove this ifdef when C1 is ported to the compiler interface. 1581 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1582 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1583 1584 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1585 Thread() 1586 #if INCLUDE_ALL_GCS 1587 , _satb_mark_queue(&_satb_mark_queue_set), 1588 _dirty_card_queue(&_dirty_card_queue_set) 1589 #endif // INCLUDE_ALL_GCS 1590 { 1591 initialize(); 1592 _jni_attach_state = _not_attaching_via_jni; 1593 set_entry_point(entry_point); 1594 // Create the native thread itself. 1595 // %note runtime_23 1596 os::ThreadType thr_type = os::java_thread; 1597 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1598 os::java_thread; 1599 os::create_thread(this, thr_type, stack_sz); 1600 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1601 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1602 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1603 // the exception consists of creating the exception object & initializing it, initialization 1604 // will leave the VM via a JavaCall and then all locks must be unlocked). 1605 // 1606 // The thread is still suspended when we reach here. Thread must be explicit started 1607 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1608 // by calling Threads:add. The reason why this is not done here, is because the thread 1609 // object must be fully initialized (take a look at JVM_Start) 1610 } 1611 1612 JavaThread::~JavaThread() { 1613 1614 // JSR166 -- return the parker to the free list 1615 Parker::Release(_parker); 1616 _parker = NULL; 1617 1618 // Free any remaining previous UnrollBlock 1619 vframeArray* old_array = vframe_array_last(); 1620 1621 if (old_array != NULL) { 1622 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1623 old_array->set_unroll_block(NULL); 1624 delete old_info; 1625 delete old_array; 1626 } 1627 1628 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1629 if (deferred != NULL) { 1630 // This can only happen if thread is destroyed before deoptimization occurs. 1631 assert(deferred->length() != 0, "empty array!"); 1632 do { 1633 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1634 deferred->remove_at(0); 1635 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1636 delete dlv; 1637 } while (deferred->length() != 0); 1638 delete deferred; 1639 } 1640 1641 // All Java related clean up happens in exit 1642 ThreadSafepointState::destroy(this); 1643 if (_thread_profiler != NULL) delete _thread_profiler; 1644 if (_thread_stat != NULL) delete _thread_stat; 1645 1646 #if INCLUDE_JVMCI 1647 if (JVMCICounterSize > 0) { 1648 if (jvmci_counters_include(this)) { 1649 for (int i = 0; i < JVMCICounterSize; i++) { 1650 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1651 } 1652 } 1653 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1654 } 1655 #endif // INCLUDE_JVMCI 1656 } 1657 1658 1659 // The first routine called by a new Java thread 1660 void JavaThread::run() { 1661 // initialize thread-local alloc buffer related fields 1662 this->initialize_tlab(); 1663 1664 // used to test validity of stack trace backs 1665 this->record_base_of_stack_pointer(); 1666 1667 // Record real stack base and size. 1668 this->record_stack_base_and_size(); 1669 1670 this->create_stack_guard_pages(); 1671 1672 this->cache_global_variables(); 1673 1674 // Thread is now sufficient initialized to be handled by the safepoint code as being 1675 // in the VM. Change thread state from _thread_new to _thread_in_vm 1676 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1677 1678 assert(JavaThread::current() == this, "sanity check"); 1679 assert(!Thread::current()->owns_locks(), "sanity check"); 1680 1681 DTRACE_THREAD_PROBE(start, this); 1682 1683 // This operation might block. We call that after all safepoint checks for a new thread has 1684 // been completed. 1685 this->set_active_handles(JNIHandleBlock::allocate_block()); 1686 1687 if (JvmtiExport::should_post_thread_life()) { 1688 JvmtiExport::post_thread_start(this); 1689 } 1690 1691 EventThreadStart event; 1692 if (event.should_commit()) { 1693 event.set_thread(THREAD_TRACE_ID(this)); 1694 event.commit(); 1695 } 1696 1697 // We call another function to do the rest so we are sure that the stack addresses used 1698 // from there will be lower than the stack base just computed 1699 thread_main_inner(); 1700 1701 // Note, thread is no longer valid at this point! 1702 } 1703 1704 1705 void JavaThread::thread_main_inner() { 1706 assert(JavaThread::current() == this, "sanity check"); 1707 assert(this->threadObj() != NULL, "just checking"); 1708 1709 // Execute thread entry point unless this thread has a pending exception 1710 // or has been stopped before starting. 1711 // Note: Due to JVM_StopThread we can have pending exceptions already! 1712 if (!this->has_pending_exception() && 1713 !java_lang_Thread::is_stillborn(this->threadObj())) { 1714 { 1715 ResourceMark rm(this); 1716 this->set_native_thread_name(this->get_thread_name()); 1717 } 1718 HandleMark hm(this); 1719 this->entry_point()(this, this); 1720 } 1721 1722 DTRACE_THREAD_PROBE(stop, this); 1723 1724 this->exit(false); 1725 delete this; 1726 } 1727 1728 1729 static void ensure_join(JavaThread* thread) { 1730 // We do not need to grap the Threads_lock, since we are operating on ourself. 1731 Handle threadObj(thread, thread->threadObj()); 1732 assert(threadObj.not_null(), "java thread object must exist"); 1733 ObjectLocker lock(threadObj, thread); 1734 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1735 thread->clear_pending_exception(); 1736 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1737 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1738 // Clear the native thread instance - this makes isAlive return false and allows the join() 1739 // to complete once we've done the notify_all below 1740 java_lang_Thread::set_thread(threadObj(), NULL); 1741 lock.notify_all(thread); 1742 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1743 thread->clear_pending_exception(); 1744 } 1745 1746 1747 // For any new cleanup additions, please check to see if they need to be applied to 1748 // cleanup_failed_attach_current_thread as well. 1749 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1750 assert(this == JavaThread::current(), "thread consistency check"); 1751 1752 HandleMark hm(this); 1753 Handle uncaught_exception(this, this->pending_exception()); 1754 this->clear_pending_exception(); 1755 Handle threadObj(this, this->threadObj()); 1756 assert(threadObj.not_null(), "Java thread object should be created"); 1757 1758 if (get_thread_profiler() != NULL) { 1759 get_thread_profiler()->disengage(); 1760 ResourceMark rm; 1761 get_thread_profiler()->print(get_thread_name()); 1762 } 1763 1764 1765 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1766 { 1767 EXCEPTION_MARK; 1768 1769 CLEAR_PENDING_EXCEPTION; 1770 } 1771 if (!destroy_vm) { 1772 if (uncaught_exception.not_null()) { 1773 EXCEPTION_MARK; 1774 // Call method Thread.dispatchUncaughtException(). 1775 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1776 JavaValue result(T_VOID); 1777 JavaCalls::call_virtual(&result, 1778 threadObj, thread_klass, 1779 vmSymbols::dispatchUncaughtException_name(), 1780 vmSymbols::throwable_void_signature(), 1781 uncaught_exception, 1782 THREAD); 1783 if (HAS_PENDING_EXCEPTION) { 1784 ResourceMark rm(this); 1785 jio_fprintf(defaultStream::error_stream(), 1786 "\nException: %s thrown from the UncaughtExceptionHandler" 1787 " in thread \"%s\"\n", 1788 pending_exception()->klass()->external_name(), 1789 get_thread_name()); 1790 CLEAR_PENDING_EXCEPTION; 1791 } 1792 } 1793 1794 // Called before the java thread exit since we want to read info 1795 // from java_lang_Thread object 1796 EventThreadEnd event; 1797 if (event.should_commit()) { 1798 event.set_thread(THREAD_TRACE_ID(this)); 1799 event.commit(); 1800 } 1801 1802 // Call after last event on thread 1803 EVENT_THREAD_EXIT(this); 1804 1805 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1806 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1807 // is deprecated anyhow. 1808 if (!is_Compiler_thread()) { 1809 int count = 3; 1810 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1811 EXCEPTION_MARK; 1812 JavaValue result(T_VOID); 1813 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1814 JavaCalls::call_virtual(&result, 1815 threadObj, thread_klass, 1816 vmSymbols::exit_method_name(), 1817 vmSymbols::void_method_signature(), 1818 THREAD); 1819 CLEAR_PENDING_EXCEPTION; 1820 } 1821 } 1822 // notify JVMTI 1823 if (JvmtiExport::should_post_thread_life()) { 1824 JvmtiExport::post_thread_end(this); 1825 } 1826 1827 // We have notified the agents that we are exiting, before we go on, 1828 // we must check for a pending external suspend request and honor it 1829 // in order to not surprise the thread that made the suspend request. 1830 while (true) { 1831 { 1832 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1833 if (!is_external_suspend()) { 1834 set_terminated(_thread_exiting); 1835 ThreadService::current_thread_exiting(this); 1836 break; 1837 } 1838 // Implied else: 1839 // Things get a little tricky here. We have a pending external 1840 // suspend request, but we are holding the SR_lock so we 1841 // can't just self-suspend. So we temporarily drop the lock 1842 // and then self-suspend. 1843 } 1844 1845 ThreadBlockInVM tbivm(this); 1846 java_suspend_self(); 1847 1848 // We're done with this suspend request, but we have to loop around 1849 // and check again. Eventually we will get SR_lock without a pending 1850 // external suspend request and will be able to mark ourselves as 1851 // exiting. 1852 } 1853 // no more external suspends are allowed at this point 1854 } else { 1855 // before_exit() has already posted JVMTI THREAD_END events 1856 } 1857 1858 // Notify waiters on thread object. This has to be done after exit() is called 1859 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1860 // group should have the destroyed bit set before waiters are notified). 1861 ensure_join(this); 1862 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1863 1864 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1865 // held by this thread must be released. The spec does not distinguish 1866 // between JNI-acquired and regular Java monitors. We can only see 1867 // regular Java monitors here if monitor enter-exit matching is broken. 1868 // 1869 // Optionally release any monitors for regular JavaThread exits. This 1870 // is provided as a work around for any bugs in monitor enter-exit 1871 // matching. This can be expensive so it is not enabled by default. 1872 // 1873 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1874 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1875 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1876 // Sanity check even though JNI DetachCurrentThread() would have 1877 // returned JNI_ERR if there was a Java frame. JavaThread exit 1878 // should be done executing Java code by the time we get here. 1879 assert(!this->has_last_Java_frame(), 1880 "should not have a Java frame when detaching or exiting"); 1881 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1882 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1883 } 1884 1885 // These things needs to be done while we are still a Java Thread. Make sure that thread 1886 // is in a consistent state, in case GC happens 1887 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1888 1889 if (active_handles() != NULL) { 1890 JNIHandleBlock* block = active_handles(); 1891 set_active_handles(NULL); 1892 JNIHandleBlock::release_block(block); 1893 } 1894 1895 if (free_handle_block() != NULL) { 1896 JNIHandleBlock* block = free_handle_block(); 1897 set_free_handle_block(NULL); 1898 JNIHandleBlock::release_block(block); 1899 } 1900 1901 // These have to be removed while this is still a valid thread. 1902 remove_stack_guard_pages(); 1903 1904 if (UseTLAB) { 1905 tlab().make_parsable(true); // retire TLAB 1906 } 1907 1908 if (JvmtiEnv::environments_might_exist()) { 1909 JvmtiExport::cleanup_thread(this); 1910 } 1911 1912 // We must flush any deferred card marks before removing a thread from 1913 // the list of active threads. 1914 Universe::heap()->flush_deferred_store_barrier(this); 1915 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1916 1917 #if INCLUDE_ALL_GCS 1918 // We must flush the G1-related buffers before removing a thread 1919 // from the list of active threads. We must do this after any deferred 1920 // card marks have been flushed (above) so that any entries that are 1921 // added to the thread's dirty card queue as a result are not lost. 1922 if (UseG1GC) { 1923 flush_barrier_queues(); 1924 } 1925 #endif // INCLUDE_ALL_GCS 1926 1927 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1928 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1929 os::current_thread_id()); 1930 1931 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1932 Threads::remove(this); 1933 } 1934 1935 #if INCLUDE_ALL_GCS 1936 // Flush G1-related queues. 1937 void JavaThread::flush_barrier_queues() { 1938 satb_mark_queue().flush(); 1939 dirty_card_queue().flush(); 1940 } 1941 1942 void JavaThread::initialize_queues() { 1943 assert(!SafepointSynchronize::is_at_safepoint(), 1944 "we should not be at a safepoint"); 1945 1946 SATBMarkQueue& satb_queue = satb_mark_queue(); 1947 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1948 // The SATB queue should have been constructed with its active 1949 // field set to false. 1950 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1951 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1952 // If we are creating the thread during a marking cycle, we should 1953 // set the active field of the SATB queue to true. 1954 if (satb_queue_set.is_active()) { 1955 satb_queue.set_active(true); 1956 } 1957 1958 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1959 // The dirty card queue should have been constructed with its 1960 // active field set to true. 1961 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1962 } 1963 #endif // INCLUDE_ALL_GCS 1964 1965 void JavaThread::cleanup_failed_attach_current_thread() { 1966 if (get_thread_profiler() != NULL) { 1967 get_thread_profiler()->disengage(); 1968 ResourceMark rm; 1969 get_thread_profiler()->print(get_thread_name()); 1970 } 1971 1972 if (active_handles() != NULL) { 1973 JNIHandleBlock* block = active_handles(); 1974 set_active_handles(NULL); 1975 JNIHandleBlock::release_block(block); 1976 } 1977 1978 if (free_handle_block() != NULL) { 1979 JNIHandleBlock* block = free_handle_block(); 1980 set_free_handle_block(NULL); 1981 JNIHandleBlock::release_block(block); 1982 } 1983 1984 // These have to be removed while this is still a valid thread. 1985 remove_stack_guard_pages(); 1986 1987 if (UseTLAB) { 1988 tlab().make_parsable(true); // retire TLAB, if any 1989 } 1990 1991 #if INCLUDE_ALL_GCS 1992 if (UseG1GC) { 1993 flush_barrier_queues(); 1994 } 1995 #endif // INCLUDE_ALL_GCS 1996 1997 Threads::remove(this); 1998 delete this; 1999 } 2000 2001 2002 2003 2004 JavaThread* JavaThread::active() { 2005 Thread* thread = Thread::current(); 2006 if (thread->is_Java_thread()) { 2007 return (JavaThread*) thread; 2008 } else { 2009 assert(thread->is_VM_thread(), "this must be a vm thread"); 2010 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2011 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2012 assert(ret->is_Java_thread(), "must be a Java thread"); 2013 return ret; 2014 } 2015 } 2016 2017 bool JavaThread::is_lock_owned(address adr) const { 2018 if (Thread::is_lock_owned(adr)) return true; 2019 2020 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2021 if (chunk->contains(adr)) return true; 2022 } 2023 2024 return false; 2025 } 2026 2027 2028 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2029 chunk->set_next(monitor_chunks()); 2030 set_monitor_chunks(chunk); 2031 } 2032 2033 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2034 guarantee(monitor_chunks() != NULL, "must be non empty"); 2035 if (monitor_chunks() == chunk) { 2036 set_monitor_chunks(chunk->next()); 2037 } else { 2038 MonitorChunk* prev = monitor_chunks(); 2039 while (prev->next() != chunk) prev = prev->next(); 2040 prev->set_next(chunk->next()); 2041 } 2042 } 2043 2044 // JVM support. 2045 2046 // Note: this function shouldn't block if it's called in 2047 // _thread_in_native_trans state (such as from 2048 // check_special_condition_for_native_trans()). 2049 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2050 2051 if (has_last_Java_frame() && has_async_condition()) { 2052 // If we are at a polling page safepoint (not a poll return) 2053 // then we must defer async exception because live registers 2054 // will be clobbered by the exception path. Poll return is 2055 // ok because the call we a returning from already collides 2056 // with exception handling registers and so there is no issue. 2057 // (The exception handling path kills call result registers but 2058 // this is ok since the exception kills the result anyway). 2059 2060 if (is_at_poll_safepoint()) { 2061 // if the code we are returning to has deoptimized we must defer 2062 // the exception otherwise live registers get clobbered on the 2063 // exception path before deoptimization is able to retrieve them. 2064 // 2065 RegisterMap map(this, false); 2066 frame caller_fr = last_frame().sender(&map); 2067 assert(caller_fr.is_compiled_frame(), "what?"); 2068 if (caller_fr.is_deoptimized_frame()) { 2069 log_info(exceptions)("deferred async exception at compiled safepoint"); 2070 return; 2071 } 2072 } 2073 } 2074 2075 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2076 if (condition == _no_async_condition) { 2077 // Conditions have changed since has_special_runtime_exit_condition() 2078 // was called: 2079 // - if we were here only because of an external suspend request, 2080 // then that was taken care of above (or cancelled) so we are done 2081 // - if we were here because of another async request, then it has 2082 // been cleared between the has_special_runtime_exit_condition() 2083 // and now so again we are done 2084 return; 2085 } 2086 2087 // Check for pending async. exception 2088 if (_pending_async_exception != NULL) { 2089 // Only overwrite an already pending exception, if it is not a threadDeath. 2090 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2091 2092 // We cannot call Exceptions::_throw(...) here because we cannot block 2093 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2094 2095 if (log_is_enabled(Info, exceptions)) { 2096 ResourceMark rm; 2097 outputStream* logstream = LogHandle(exceptions)::info_stream(); 2098 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2099 if (has_last_Java_frame()) { 2100 frame f = last_frame(); 2101 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2102 } 2103 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2104 } 2105 _pending_async_exception = NULL; 2106 clear_has_async_exception(); 2107 } 2108 } 2109 2110 if (check_unsafe_error && 2111 condition == _async_unsafe_access_error && !has_pending_exception()) { 2112 condition = _no_async_condition; // done 2113 switch (thread_state()) { 2114 case _thread_in_vm: { 2115 JavaThread* THREAD = this; 2116 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2117 } 2118 case _thread_in_native: { 2119 ThreadInVMfromNative tiv(this); 2120 JavaThread* THREAD = this; 2121 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2122 } 2123 case _thread_in_Java: { 2124 ThreadInVMfromJava tiv(this); 2125 JavaThread* THREAD = this; 2126 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2127 } 2128 default: 2129 ShouldNotReachHere(); 2130 } 2131 } 2132 2133 assert(condition == _no_async_condition || has_pending_exception() || 2134 (!check_unsafe_error && condition == _async_unsafe_access_error), 2135 "must have handled the async condition, if no exception"); 2136 } 2137 2138 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2139 // 2140 // Check for pending external suspend. Internal suspend requests do 2141 // not use handle_special_runtime_exit_condition(). 2142 // If JNIEnv proxies are allowed, don't self-suspend if the target 2143 // thread is not the current thread. In older versions of jdbx, jdbx 2144 // threads could call into the VM with another thread's JNIEnv so we 2145 // can be here operating on behalf of a suspended thread (4432884). 2146 bool do_self_suspend = is_external_suspend_with_lock(); 2147 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2148 // 2149 // Because thread is external suspended the safepoint code will count 2150 // thread as at a safepoint. This can be odd because we can be here 2151 // as _thread_in_Java which would normally transition to _thread_blocked 2152 // at a safepoint. We would like to mark the thread as _thread_blocked 2153 // before calling java_suspend_self like all other callers of it but 2154 // we must then observe proper safepoint protocol. (We can't leave 2155 // _thread_blocked with a safepoint in progress). However we can be 2156 // here as _thread_in_native_trans so we can't use a normal transition 2157 // constructor/destructor pair because they assert on that type of 2158 // transition. We could do something like: 2159 // 2160 // JavaThreadState state = thread_state(); 2161 // set_thread_state(_thread_in_vm); 2162 // { 2163 // ThreadBlockInVM tbivm(this); 2164 // java_suspend_self() 2165 // } 2166 // set_thread_state(_thread_in_vm_trans); 2167 // if (safepoint) block; 2168 // set_thread_state(state); 2169 // 2170 // but that is pretty messy. Instead we just go with the way the 2171 // code has worked before and note that this is the only path to 2172 // java_suspend_self that doesn't put the thread in _thread_blocked 2173 // mode. 2174 2175 frame_anchor()->make_walkable(this); 2176 java_suspend_self(); 2177 2178 // We might be here for reasons in addition to the self-suspend request 2179 // so check for other async requests. 2180 } 2181 2182 if (check_asyncs) { 2183 check_and_handle_async_exceptions(); 2184 } 2185 } 2186 2187 void JavaThread::send_thread_stop(oop java_throwable) { 2188 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2189 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2190 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2191 2192 // Do not throw asynchronous exceptions against the compiler thread 2193 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2194 if (!can_call_java()) return; 2195 2196 { 2197 // Actually throw the Throwable against the target Thread - however 2198 // only if there is no thread death exception installed already. 2199 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2200 // If the topmost frame is a runtime stub, then we are calling into 2201 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2202 // must deoptimize the caller before continuing, as the compiled exception handler table 2203 // may not be valid 2204 if (has_last_Java_frame()) { 2205 frame f = last_frame(); 2206 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2207 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2208 RegisterMap reg_map(this, UseBiasedLocking); 2209 frame compiled_frame = f.sender(®_map); 2210 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2211 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2212 } 2213 } 2214 } 2215 2216 // Set async. pending exception in thread. 2217 set_pending_async_exception(java_throwable); 2218 2219 if (log_is_enabled(Info, exceptions)) { 2220 ResourceMark rm; 2221 log_info(exceptions)("Pending Async. exception installed of type: %s", 2222 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2223 } 2224 // for AbortVMOnException flag 2225 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2226 } 2227 } 2228 2229 2230 // Interrupt thread so it will wake up from a potential wait() 2231 Thread::interrupt(this); 2232 } 2233 2234 // External suspension mechanism. 2235 // 2236 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2237 // to any VM_locks and it is at a transition 2238 // Self-suspension will happen on the transition out of the vm. 2239 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2240 // 2241 // Guarantees on return: 2242 // + Target thread will not execute any new bytecode (that's why we need to 2243 // force a safepoint) 2244 // + Target thread will not enter any new monitors 2245 // 2246 void JavaThread::java_suspend() { 2247 { MutexLocker mu(Threads_lock); 2248 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2249 return; 2250 } 2251 } 2252 2253 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2254 if (!is_external_suspend()) { 2255 // a racing resume has cancelled us; bail out now 2256 return; 2257 } 2258 2259 // suspend is done 2260 uint32_t debug_bits = 0; 2261 // Warning: is_ext_suspend_completed() may temporarily drop the 2262 // SR_lock to allow the thread to reach a stable thread state if 2263 // it is currently in a transient thread state. 2264 if (is_ext_suspend_completed(false /* !called_by_wait */, 2265 SuspendRetryDelay, &debug_bits)) { 2266 return; 2267 } 2268 } 2269 2270 VM_ForceSafepoint vm_suspend; 2271 VMThread::execute(&vm_suspend); 2272 } 2273 2274 // Part II of external suspension. 2275 // A JavaThread self suspends when it detects a pending external suspend 2276 // request. This is usually on transitions. It is also done in places 2277 // where continuing to the next transition would surprise the caller, 2278 // e.g., monitor entry. 2279 // 2280 // Returns the number of times that the thread self-suspended. 2281 // 2282 // Note: DO NOT call java_suspend_self() when you just want to block current 2283 // thread. java_suspend_self() is the second stage of cooperative 2284 // suspension for external suspend requests and should only be used 2285 // to complete an external suspend request. 2286 // 2287 int JavaThread::java_suspend_self() { 2288 int ret = 0; 2289 2290 // we are in the process of exiting so don't suspend 2291 if (is_exiting()) { 2292 clear_external_suspend(); 2293 return ret; 2294 } 2295 2296 assert(_anchor.walkable() || 2297 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2298 "must have walkable stack"); 2299 2300 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2301 2302 assert(!this->is_ext_suspended(), 2303 "a thread trying to self-suspend should not already be suspended"); 2304 2305 if (this->is_suspend_equivalent()) { 2306 // If we are self-suspending as a result of the lifting of a 2307 // suspend equivalent condition, then the suspend_equivalent 2308 // flag is not cleared until we set the ext_suspended flag so 2309 // that wait_for_ext_suspend_completion() returns consistent 2310 // results. 2311 this->clear_suspend_equivalent(); 2312 } 2313 2314 // A racing resume may have cancelled us before we grabbed SR_lock 2315 // above. Or another external suspend request could be waiting for us 2316 // by the time we return from SR_lock()->wait(). The thread 2317 // that requested the suspension may already be trying to walk our 2318 // stack and if we return now, we can change the stack out from under 2319 // it. This would be a "bad thing (TM)" and cause the stack walker 2320 // to crash. We stay self-suspended until there are no more pending 2321 // external suspend requests. 2322 while (is_external_suspend()) { 2323 ret++; 2324 this->set_ext_suspended(); 2325 2326 // _ext_suspended flag is cleared by java_resume() 2327 while (is_ext_suspended()) { 2328 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2329 } 2330 } 2331 2332 return ret; 2333 } 2334 2335 #ifdef ASSERT 2336 // verify the JavaThread has not yet been published in the Threads::list, and 2337 // hence doesn't need protection from concurrent access at this stage 2338 void JavaThread::verify_not_published() { 2339 if (!Threads_lock->owned_by_self()) { 2340 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2341 assert(!Threads::includes(this), 2342 "java thread shouldn't have been published yet!"); 2343 } else { 2344 assert(!Threads::includes(this), 2345 "java thread shouldn't have been published yet!"); 2346 } 2347 } 2348 #endif 2349 2350 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2351 // progress or when _suspend_flags is non-zero. 2352 // Current thread needs to self-suspend if there is a suspend request and/or 2353 // block if a safepoint is in progress. 2354 // Async exception ISN'T checked. 2355 // Note only the ThreadInVMfromNative transition can call this function 2356 // directly and when thread state is _thread_in_native_trans 2357 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2358 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2359 2360 JavaThread *curJT = JavaThread::current(); 2361 bool do_self_suspend = thread->is_external_suspend(); 2362 2363 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2364 2365 // If JNIEnv proxies are allowed, don't self-suspend if the target 2366 // thread is not the current thread. In older versions of jdbx, jdbx 2367 // threads could call into the VM with another thread's JNIEnv so we 2368 // can be here operating on behalf of a suspended thread (4432884). 2369 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2370 JavaThreadState state = thread->thread_state(); 2371 2372 // We mark this thread_blocked state as a suspend-equivalent so 2373 // that a caller to is_ext_suspend_completed() won't be confused. 2374 // The suspend-equivalent state is cleared by java_suspend_self(). 2375 thread->set_suspend_equivalent(); 2376 2377 // If the safepoint code sees the _thread_in_native_trans state, it will 2378 // wait until the thread changes to other thread state. There is no 2379 // guarantee on how soon we can obtain the SR_lock and complete the 2380 // self-suspend request. It would be a bad idea to let safepoint wait for 2381 // too long. Temporarily change the state to _thread_blocked to 2382 // let the VM thread know that this thread is ready for GC. The problem 2383 // of changing thread state is that safepoint could happen just after 2384 // java_suspend_self() returns after being resumed, and VM thread will 2385 // see the _thread_blocked state. We must check for safepoint 2386 // after restoring the state and make sure we won't leave while a safepoint 2387 // is in progress. 2388 thread->set_thread_state(_thread_blocked); 2389 thread->java_suspend_self(); 2390 thread->set_thread_state(state); 2391 // Make sure new state is seen by VM thread 2392 if (os::is_MP()) { 2393 if (UseMembar) { 2394 // Force a fence between the write above and read below 2395 OrderAccess::fence(); 2396 } else { 2397 // Must use this rather than serialization page in particular on Windows 2398 InterfaceSupport::serialize_memory(thread); 2399 } 2400 } 2401 } 2402 2403 if (SafepointSynchronize::do_call_back()) { 2404 // If we are safepointing, then block the caller which may not be 2405 // the same as the target thread (see above). 2406 SafepointSynchronize::block(curJT); 2407 } 2408 2409 if (thread->is_deopt_suspend()) { 2410 thread->clear_deopt_suspend(); 2411 RegisterMap map(thread, false); 2412 frame f = thread->last_frame(); 2413 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2414 f = f.sender(&map); 2415 } 2416 if (f.id() == thread->must_deopt_id()) { 2417 thread->clear_must_deopt_id(); 2418 f.deoptimize(thread); 2419 } else { 2420 fatal("missed deoptimization!"); 2421 } 2422 } 2423 } 2424 2425 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2426 // progress or when _suspend_flags is non-zero. 2427 // Current thread needs to self-suspend if there is a suspend request and/or 2428 // block if a safepoint is in progress. 2429 // Also check for pending async exception (not including unsafe access error). 2430 // Note only the native==>VM/Java barriers can call this function and when 2431 // thread state is _thread_in_native_trans. 2432 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2433 check_safepoint_and_suspend_for_native_trans(thread); 2434 2435 if (thread->has_async_exception()) { 2436 // We are in _thread_in_native_trans state, don't handle unsafe 2437 // access error since that may block. 2438 thread->check_and_handle_async_exceptions(false); 2439 } 2440 } 2441 2442 // This is a variant of the normal 2443 // check_special_condition_for_native_trans with slightly different 2444 // semantics for use by critical native wrappers. It does all the 2445 // normal checks but also performs the transition back into 2446 // thread_in_Java state. This is required so that critical natives 2447 // can potentially block and perform a GC if they are the last thread 2448 // exiting the GCLocker. 2449 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2450 check_special_condition_for_native_trans(thread); 2451 2452 // Finish the transition 2453 thread->set_thread_state(_thread_in_Java); 2454 2455 if (thread->do_critical_native_unlock()) { 2456 ThreadInVMfromJavaNoAsyncException tiv(thread); 2457 GCLocker::unlock_critical(thread); 2458 thread->clear_critical_native_unlock(); 2459 } 2460 } 2461 2462 // We need to guarantee the Threads_lock here, since resumes are not 2463 // allowed during safepoint synchronization 2464 // Can only resume from an external suspension 2465 void JavaThread::java_resume() { 2466 assert_locked_or_safepoint(Threads_lock); 2467 2468 // Sanity check: thread is gone, has started exiting or the thread 2469 // was not externally suspended. 2470 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2471 return; 2472 } 2473 2474 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2475 2476 clear_external_suspend(); 2477 2478 if (is_ext_suspended()) { 2479 clear_ext_suspended(); 2480 SR_lock()->notify_all(); 2481 } 2482 } 2483 2484 size_t JavaThread::_stack_red_zone_size = 0; 2485 size_t JavaThread::_stack_yellow_zone_size = 0; 2486 size_t JavaThread::_stack_reserved_zone_size = 0; 2487 size_t JavaThread::_stack_shadow_zone_size = 0; 2488 2489 void JavaThread::create_stack_guard_pages() { 2490 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2491 address low_addr = stack_end(); 2492 size_t len = stack_guard_zone_size(); 2493 2494 int allocate = os::allocate_stack_guard_pages(); 2495 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2496 2497 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2498 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2499 return; 2500 } 2501 2502 if (os::guard_memory((char *) low_addr, len)) { 2503 _stack_guard_state = stack_guard_enabled; 2504 } else { 2505 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2506 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2507 if (os::uncommit_memory((char *) low_addr, len)) { 2508 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2509 } 2510 return; 2511 } 2512 2513 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2514 PTR_FORMAT "-" PTR_FORMAT ".", 2515 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2516 2517 } 2518 2519 void JavaThread::remove_stack_guard_pages() { 2520 assert(Thread::current() == this, "from different thread"); 2521 if (_stack_guard_state == stack_guard_unused) return; 2522 address low_addr = stack_end(); 2523 size_t len = stack_guard_zone_size(); 2524 2525 if (os::allocate_stack_guard_pages()) { 2526 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2527 _stack_guard_state = stack_guard_unused; 2528 } else { 2529 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2530 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2531 return; 2532 } 2533 } else { 2534 if (_stack_guard_state == stack_guard_unused) return; 2535 if (os::unguard_memory((char *) low_addr, len)) { 2536 _stack_guard_state = stack_guard_unused; 2537 } else { 2538 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2539 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2540 return; 2541 } 2542 } 2543 2544 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2545 PTR_FORMAT "-" PTR_FORMAT ".", 2546 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2547 2548 } 2549 2550 void JavaThread::enable_stack_reserved_zone() { 2551 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2552 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2553 2554 // The base notation is from the stack's point of view, growing downward. 2555 // We need to adjust it to work correctly with guard_memory() 2556 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2557 2558 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2559 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2560 2561 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2562 _stack_guard_state = stack_guard_enabled; 2563 } else { 2564 warning("Attempt to guard stack reserved zone failed."); 2565 } 2566 enable_register_stack_guard(); 2567 } 2568 2569 void JavaThread::disable_stack_reserved_zone() { 2570 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2571 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2572 2573 // Simply return if called for a thread that does not use guard pages. 2574 if (_stack_guard_state == stack_guard_unused) return; 2575 2576 // The base notation is from the stack's point of view, growing downward. 2577 // We need to adjust it to work correctly with guard_memory() 2578 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2579 2580 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2581 _stack_guard_state = stack_guard_reserved_disabled; 2582 } else { 2583 warning("Attempt to unguard stack reserved zone failed."); 2584 } 2585 disable_register_stack_guard(); 2586 } 2587 2588 void JavaThread::enable_stack_yellow_reserved_zone() { 2589 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2590 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2591 2592 // The base notation is from the stacks point of view, growing downward. 2593 // We need to adjust it to work correctly with guard_memory() 2594 address base = stack_red_zone_base(); 2595 2596 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2597 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2598 2599 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2600 _stack_guard_state = stack_guard_enabled; 2601 } else { 2602 warning("Attempt to guard stack yellow zone failed."); 2603 } 2604 enable_register_stack_guard(); 2605 } 2606 2607 void JavaThread::disable_stack_yellow_reserved_zone() { 2608 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2609 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2610 2611 // Simply return if called for a thread that does not use guard pages. 2612 if (_stack_guard_state == stack_guard_unused) return; 2613 2614 // The base notation is from the stacks point of view, growing downward. 2615 // We need to adjust it to work correctly with guard_memory() 2616 address base = stack_red_zone_base(); 2617 2618 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2619 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2620 } else { 2621 warning("Attempt to unguard stack yellow zone failed."); 2622 } 2623 disable_register_stack_guard(); 2624 } 2625 2626 void JavaThread::enable_stack_red_zone() { 2627 // The base notation is from the stacks point of view, growing downward. 2628 // We need to adjust it to work correctly with guard_memory() 2629 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2630 address base = stack_red_zone_base() - stack_red_zone_size(); 2631 2632 guarantee(base < stack_base(), "Error calculating stack red zone"); 2633 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2634 2635 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2636 warning("Attempt to guard stack red zone failed."); 2637 } 2638 } 2639 2640 void JavaThread::disable_stack_red_zone() { 2641 // The base notation is from the stacks point of view, growing downward. 2642 // We need to adjust it to work correctly with guard_memory() 2643 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2644 address base = stack_red_zone_base() - stack_red_zone_size(); 2645 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2646 warning("Attempt to unguard stack red zone failed."); 2647 } 2648 } 2649 2650 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2651 // ignore is there is no stack 2652 if (!has_last_Java_frame()) return; 2653 // traverse the stack frames. Starts from top frame. 2654 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2655 frame* fr = fst.current(); 2656 f(fr, fst.register_map()); 2657 } 2658 } 2659 2660 2661 #ifndef PRODUCT 2662 // Deoptimization 2663 // Function for testing deoptimization 2664 void JavaThread::deoptimize() { 2665 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2666 StackFrameStream fst(this, UseBiasedLocking); 2667 bool deopt = false; // Dump stack only if a deopt actually happens. 2668 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2669 // Iterate over all frames in the thread and deoptimize 2670 for (; !fst.is_done(); fst.next()) { 2671 if (fst.current()->can_be_deoptimized()) { 2672 2673 if (only_at) { 2674 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2675 // consists of comma or carriage return separated numbers so 2676 // search for the current bci in that string. 2677 address pc = fst.current()->pc(); 2678 nmethod* nm = (nmethod*) fst.current()->cb(); 2679 ScopeDesc* sd = nm->scope_desc_at(pc); 2680 char buffer[8]; 2681 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2682 size_t len = strlen(buffer); 2683 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2684 while (found != NULL) { 2685 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2686 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2687 // Check that the bci found is bracketed by terminators. 2688 break; 2689 } 2690 found = strstr(found + 1, buffer); 2691 } 2692 if (!found) { 2693 continue; 2694 } 2695 } 2696 2697 if (DebugDeoptimization && !deopt) { 2698 deopt = true; // One-time only print before deopt 2699 tty->print_cr("[BEFORE Deoptimization]"); 2700 trace_frames(); 2701 trace_stack(); 2702 } 2703 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2704 } 2705 } 2706 2707 if (DebugDeoptimization && deopt) { 2708 tty->print_cr("[AFTER Deoptimization]"); 2709 trace_frames(); 2710 } 2711 } 2712 2713 2714 // Make zombies 2715 void JavaThread::make_zombies() { 2716 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2717 if (fst.current()->can_be_deoptimized()) { 2718 // it is a Java nmethod 2719 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2720 nm->make_not_entrant(); 2721 } 2722 } 2723 } 2724 #endif // PRODUCT 2725 2726 2727 void JavaThread::deoptimized_wrt_marked_nmethods() { 2728 if (!has_last_Java_frame()) return; 2729 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2730 StackFrameStream fst(this, UseBiasedLocking); 2731 for (; !fst.is_done(); fst.next()) { 2732 if (fst.current()->should_be_deoptimized()) { 2733 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2734 } 2735 } 2736 } 2737 2738 2739 // If the caller is a NamedThread, then remember, in the current scope, 2740 // the given JavaThread in its _processed_thread field. 2741 class RememberProcessedThread: public StackObj { 2742 NamedThread* _cur_thr; 2743 public: 2744 RememberProcessedThread(JavaThread* jthr) { 2745 Thread* thread = Thread::current(); 2746 if (thread->is_Named_thread()) { 2747 _cur_thr = (NamedThread *)thread; 2748 _cur_thr->set_processed_thread(jthr); 2749 } else { 2750 _cur_thr = NULL; 2751 } 2752 } 2753 2754 ~RememberProcessedThread() { 2755 if (_cur_thr) { 2756 _cur_thr->set_processed_thread(NULL); 2757 } 2758 } 2759 }; 2760 2761 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 2762 // Verify that the deferred card marks have been flushed. 2763 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2764 2765 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2766 // since there may be more than one thread using each ThreadProfiler. 2767 2768 // Traverse the GCHandles 2769 Thread::oops_do(f, cld_f, cf); 2770 2771 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2772 2773 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2774 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2775 2776 if (has_last_Java_frame()) { 2777 // Record JavaThread to GC thread 2778 RememberProcessedThread rpt(this); 2779 2780 // Traverse the privileged stack 2781 if (_privileged_stack_top != NULL) { 2782 _privileged_stack_top->oops_do(f); 2783 } 2784 2785 // traverse the registered growable array 2786 if (_array_for_gc != NULL) { 2787 for (int index = 0; index < _array_for_gc->length(); index++) { 2788 f->do_oop(_array_for_gc->adr_at(index)); 2789 } 2790 } 2791 2792 // Traverse the monitor chunks 2793 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2794 chunk->oops_do(f); 2795 } 2796 2797 // Traverse the execution stack 2798 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2799 fst.current()->oops_do(f, cld_f, cf, fst.register_map()); 2800 } 2801 } 2802 2803 // callee_target is never live across a gc point so NULL it here should 2804 // it still contain a methdOop. 2805 2806 set_callee_target(NULL); 2807 2808 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2809 // If we have deferred set_locals there might be oops waiting to be 2810 // written 2811 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2812 if (list != NULL) { 2813 for (int i = 0; i < list->length(); i++) { 2814 list->at(i)->oops_do(f); 2815 } 2816 } 2817 2818 // Traverse instance variables at the end since the GC may be moving things 2819 // around using this function 2820 f->do_oop((oop*) &_threadObj); 2821 f->do_oop((oop*) &_vm_result); 2822 f->do_oop((oop*) &_exception_oop); 2823 f->do_oop((oop*) &_pending_async_exception); 2824 2825 if (jvmti_thread_state() != NULL) { 2826 jvmti_thread_state()->oops_do(f); 2827 } 2828 } 2829 2830 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2831 Thread::nmethods_do(cf); // (super method is a no-op) 2832 2833 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2834 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2835 2836 if (has_last_Java_frame()) { 2837 // Traverse the execution stack 2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2839 fst.current()->nmethods_do(cf); 2840 } 2841 } 2842 } 2843 2844 void JavaThread::metadata_do(void f(Metadata*)) { 2845 if (has_last_Java_frame()) { 2846 // Traverse the execution stack to call f() on the methods in the stack 2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2848 fst.current()->metadata_do(f); 2849 } 2850 } else if (is_Compiler_thread()) { 2851 // need to walk ciMetadata in current compile tasks to keep alive. 2852 CompilerThread* ct = (CompilerThread*)this; 2853 if (ct->env() != NULL) { 2854 ct->env()->metadata_do(f); 2855 } 2856 if (ct->task() != NULL) { 2857 ct->task()->metadata_do(f); 2858 } 2859 } 2860 } 2861 2862 // Printing 2863 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2864 switch (_thread_state) { 2865 case _thread_uninitialized: return "_thread_uninitialized"; 2866 case _thread_new: return "_thread_new"; 2867 case _thread_new_trans: return "_thread_new_trans"; 2868 case _thread_in_native: return "_thread_in_native"; 2869 case _thread_in_native_trans: return "_thread_in_native_trans"; 2870 case _thread_in_vm: return "_thread_in_vm"; 2871 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2872 case _thread_in_Java: return "_thread_in_Java"; 2873 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2874 case _thread_blocked: return "_thread_blocked"; 2875 case _thread_blocked_trans: return "_thread_blocked_trans"; 2876 default: return "unknown thread state"; 2877 } 2878 } 2879 2880 #ifndef PRODUCT 2881 void JavaThread::print_thread_state_on(outputStream *st) const { 2882 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2883 }; 2884 void JavaThread::print_thread_state() const { 2885 print_thread_state_on(tty); 2886 } 2887 #endif // PRODUCT 2888 2889 // Called by Threads::print() for VM_PrintThreads operation 2890 void JavaThread::print_on(outputStream *st) const { 2891 st->print("\"%s\" ", get_thread_name()); 2892 oop thread_oop = threadObj(); 2893 if (thread_oop != NULL) { 2894 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2895 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2896 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2897 } 2898 Thread::print_on(st); 2899 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2900 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2901 if (thread_oop != NULL) { 2902 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2903 } 2904 #ifndef PRODUCT 2905 print_thread_state_on(st); 2906 _safepoint_state->print_on(st); 2907 #endif // PRODUCT 2908 if (is_Compiler_thread()) { 2909 CompilerThread* ct = (CompilerThread*)this; 2910 if (ct->task() != NULL) { 2911 st->print(" Compiling: "); 2912 ct->task()->print(st, NULL, true, false); 2913 } else { 2914 st->print(" No compile task"); 2915 } 2916 st->cr(); 2917 } 2918 } 2919 2920 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2921 st->print("%s", get_thread_name_string(buf, buflen)); 2922 } 2923 2924 // Called by fatal error handler. The difference between this and 2925 // JavaThread::print() is that we can't grab lock or allocate memory. 2926 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2927 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2928 oop thread_obj = threadObj(); 2929 if (thread_obj != NULL) { 2930 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2931 } 2932 st->print(" ["); 2933 st->print("%s", _get_thread_state_name(_thread_state)); 2934 if (osthread()) { 2935 st->print(", id=%d", osthread()->thread_id()); 2936 } 2937 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2938 p2i(stack_end()), p2i(stack_base())); 2939 st->print("]"); 2940 return; 2941 } 2942 2943 // Verification 2944 2945 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2946 2947 void JavaThread::verify() { 2948 // Verify oops in the thread. 2949 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); 2950 2951 // Verify the stack frames. 2952 frames_do(frame_verify); 2953 } 2954 2955 // CR 6300358 (sub-CR 2137150) 2956 // Most callers of this method assume that it can't return NULL but a 2957 // thread may not have a name whilst it is in the process of attaching to 2958 // the VM - see CR 6412693, and there are places where a JavaThread can be 2959 // seen prior to having it's threadObj set (eg JNI attaching threads and 2960 // if vm exit occurs during initialization). These cases can all be accounted 2961 // for such that this method never returns NULL. 2962 const char* JavaThread::get_thread_name() const { 2963 #ifdef ASSERT 2964 // early safepoints can hit while current thread does not yet have TLS 2965 if (!SafepointSynchronize::is_at_safepoint()) { 2966 Thread *cur = Thread::current(); 2967 if (!(cur->is_Java_thread() && cur == this)) { 2968 // Current JavaThreads are allowed to get their own name without 2969 // the Threads_lock. 2970 assert_locked_or_safepoint(Threads_lock); 2971 } 2972 } 2973 #endif // ASSERT 2974 return get_thread_name_string(); 2975 } 2976 2977 // Returns a non-NULL representation of this thread's name, or a suitable 2978 // descriptive string if there is no set name 2979 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2980 const char* name_str; 2981 oop thread_obj = threadObj(); 2982 if (thread_obj != NULL) { 2983 oop name = java_lang_Thread::name(thread_obj); 2984 if (name != NULL) { 2985 if (buf == NULL) { 2986 name_str = java_lang_String::as_utf8_string(name); 2987 } else { 2988 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2989 } 2990 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2991 name_str = "<no-name - thread is attaching>"; 2992 } else { 2993 name_str = Thread::name(); 2994 } 2995 } else { 2996 name_str = Thread::name(); 2997 } 2998 assert(name_str != NULL, "unexpected NULL thread name"); 2999 return name_str; 3000 } 3001 3002 3003 const char* JavaThread::get_threadgroup_name() const { 3004 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3005 oop thread_obj = threadObj(); 3006 if (thread_obj != NULL) { 3007 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3008 if (thread_group != NULL) { 3009 // ThreadGroup.name can be null 3010 return java_lang_ThreadGroup::name(thread_group); 3011 } 3012 } 3013 return NULL; 3014 } 3015 3016 const char* JavaThread::get_parent_name() const { 3017 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3018 oop thread_obj = threadObj(); 3019 if (thread_obj != NULL) { 3020 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3021 if (thread_group != NULL) { 3022 oop parent = java_lang_ThreadGroup::parent(thread_group); 3023 if (parent != NULL) { 3024 // ThreadGroup.name can be null 3025 return java_lang_ThreadGroup::name(parent); 3026 } 3027 } 3028 } 3029 return NULL; 3030 } 3031 3032 ThreadPriority JavaThread::java_priority() const { 3033 oop thr_oop = threadObj(); 3034 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3035 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3036 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3037 return priority; 3038 } 3039 3040 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3041 3042 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3043 // Link Java Thread object <-> C++ Thread 3044 3045 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3046 // and put it into a new Handle. The Handle "thread_oop" can then 3047 // be used to pass the C++ thread object to other methods. 3048 3049 // Set the Java level thread object (jthread) field of the 3050 // new thread (a JavaThread *) to C++ thread object using the 3051 // "thread_oop" handle. 3052 3053 // Set the thread field (a JavaThread *) of the 3054 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3055 3056 Handle thread_oop(Thread::current(), 3057 JNIHandles::resolve_non_null(jni_thread)); 3058 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3059 "must be initialized"); 3060 set_threadObj(thread_oop()); 3061 java_lang_Thread::set_thread(thread_oop(), this); 3062 3063 if (prio == NoPriority) { 3064 prio = java_lang_Thread::priority(thread_oop()); 3065 assert(prio != NoPriority, "A valid priority should be present"); 3066 } 3067 3068 // Push the Java priority down to the native thread; needs Threads_lock 3069 Thread::set_priority(this, prio); 3070 3071 prepare_ext(); 3072 3073 // Add the new thread to the Threads list and set it in motion. 3074 // We must have threads lock in order to call Threads::add. 3075 // It is crucial that we do not block before the thread is 3076 // added to the Threads list for if a GC happens, then the java_thread oop 3077 // will not be visited by GC. 3078 Threads::add(this); 3079 } 3080 3081 oop JavaThread::current_park_blocker() { 3082 // Support for JSR-166 locks 3083 oop thread_oop = threadObj(); 3084 if (thread_oop != NULL && 3085 JDK_Version::current().supports_thread_park_blocker()) { 3086 return java_lang_Thread::park_blocker(thread_oop); 3087 } 3088 return NULL; 3089 } 3090 3091 3092 void JavaThread::print_stack_on(outputStream* st) { 3093 if (!has_last_Java_frame()) return; 3094 ResourceMark rm; 3095 HandleMark hm; 3096 3097 RegisterMap reg_map(this); 3098 vframe* start_vf = last_java_vframe(®_map); 3099 int count = 0; 3100 for (vframe* f = start_vf; f; f = f->sender()) { 3101 if (f->is_java_frame()) { 3102 javaVFrame* jvf = javaVFrame::cast(f); 3103 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3104 3105 // Print out lock information 3106 if (JavaMonitorsInStackTrace) { 3107 jvf->print_lock_info_on(st, count); 3108 } 3109 } else { 3110 // Ignore non-Java frames 3111 } 3112 3113 // Bail-out case for too deep stacks 3114 count++; 3115 if (MaxJavaStackTraceDepth == count) return; 3116 } 3117 } 3118 3119 3120 // JVMTI PopFrame support 3121 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3122 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3123 if (in_bytes(size_in_bytes) != 0) { 3124 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3125 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3126 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3127 } 3128 } 3129 3130 void* JavaThread::popframe_preserved_args() { 3131 return _popframe_preserved_args; 3132 } 3133 3134 ByteSize JavaThread::popframe_preserved_args_size() { 3135 return in_ByteSize(_popframe_preserved_args_size); 3136 } 3137 3138 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3139 int sz = in_bytes(popframe_preserved_args_size()); 3140 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3141 return in_WordSize(sz / wordSize); 3142 } 3143 3144 void JavaThread::popframe_free_preserved_args() { 3145 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3146 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3147 _popframe_preserved_args = NULL; 3148 _popframe_preserved_args_size = 0; 3149 } 3150 3151 #ifndef PRODUCT 3152 3153 void JavaThread::trace_frames() { 3154 tty->print_cr("[Describe stack]"); 3155 int frame_no = 1; 3156 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3157 tty->print(" %d. ", frame_no++); 3158 fst.current()->print_value_on(tty, this); 3159 tty->cr(); 3160 } 3161 } 3162 3163 class PrintAndVerifyOopClosure: public OopClosure { 3164 protected: 3165 template <class T> inline void do_oop_work(T* p) { 3166 oop obj = oopDesc::load_decode_heap_oop(p); 3167 if (obj == NULL) return; 3168 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3169 if (obj->is_oop_or_null()) { 3170 if (obj->is_objArray()) { 3171 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3172 } else { 3173 obj->print(); 3174 } 3175 } else { 3176 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3177 } 3178 tty->cr(); 3179 } 3180 public: 3181 virtual void do_oop(oop* p) { do_oop_work(p); } 3182 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3183 }; 3184 3185 3186 static void oops_print(frame* f, const RegisterMap *map) { 3187 PrintAndVerifyOopClosure print; 3188 f->print_value(); 3189 f->oops_do(&print, NULL, NULL, (RegisterMap*)map); 3190 } 3191 3192 // Print our all the locations that contain oops and whether they are 3193 // valid or not. This useful when trying to find the oldest frame 3194 // where an oop has gone bad since the frame walk is from youngest to 3195 // oldest. 3196 void JavaThread::trace_oops() { 3197 tty->print_cr("[Trace oops]"); 3198 frames_do(oops_print); 3199 } 3200 3201 3202 #ifdef ASSERT 3203 // Print or validate the layout of stack frames 3204 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3205 ResourceMark rm; 3206 PRESERVE_EXCEPTION_MARK; 3207 FrameValues values; 3208 int frame_no = 0; 3209 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3210 fst.current()->describe(values, ++frame_no); 3211 if (depth == frame_no) break; 3212 } 3213 if (validate_only) { 3214 values.validate(); 3215 } else { 3216 tty->print_cr("[Describe stack layout]"); 3217 values.print(this); 3218 } 3219 } 3220 #endif 3221 3222 void JavaThread::trace_stack_from(vframe* start_vf) { 3223 ResourceMark rm; 3224 int vframe_no = 1; 3225 for (vframe* f = start_vf; f; f = f->sender()) { 3226 if (f->is_java_frame()) { 3227 javaVFrame::cast(f)->print_activation(vframe_no++); 3228 } else { 3229 f->print(); 3230 } 3231 if (vframe_no > StackPrintLimit) { 3232 tty->print_cr("...<more frames>..."); 3233 return; 3234 } 3235 } 3236 } 3237 3238 3239 void JavaThread::trace_stack() { 3240 if (!has_last_Java_frame()) return; 3241 ResourceMark rm; 3242 HandleMark hm; 3243 RegisterMap reg_map(this); 3244 trace_stack_from(last_java_vframe(®_map)); 3245 } 3246 3247 3248 #endif // PRODUCT 3249 3250 3251 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3252 assert(reg_map != NULL, "a map must be given"); 3253 frame f = last_frame(); 3254 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3255 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3256 } 3257 return NULL; 3258 } 3259 3260 3261 Klass* JavaThread::security_get_caller_class(int depth) { 3262 vframeStream vfst(this); 3263 vfst.security_get_caller_frame(depth); 3264 if (!vfst.at_end()) { 3265 return vfst.method()->method_holder(); 3266 } 3267 return NULL; 3268 } 3269 3270 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3271 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3272 CompileBroker::compiler_thread_loop(); 3273 } 3274 3275 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3276 NMethodSweeper::sweeper_loop(); 3277 } 3278 3279 // Create a CompilerThread 3280 CompilerThread::CompilerThread(CompileQueue* queue, 3281 CompilerCounters* counters) 3282 : JavaThread(&compiler_thread_entry) { 3283 _env = NULL; 3284 _log = NULL; 3285 _task = NULL; 3286 _queue = queue; 3287 _counters = counters; 3288 _buffer_blob = NULL; 3289 _compiler = NULL; 3290 3291 #ifndef PRODUCT 3292 _ideal_graph_printer = NULL; 3293 #endif 3294 } 3295 3296 bool CompilerThread::can_call_java() const { 3297 return _compiler != NULL && _compiler->is_jvmci(); 3298 } 3299 3300 // Create sweeper thread 3301 CodeCacheSweeperThread::CodeCacheSweeperThread() 3302 : JavaThread(&sweeper_thread_entry) { 3303 _scanned_nmethod = NULL; 3304 } 3305 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 3306 JavaThread::oops_do(f, cld_f, cf); 3307 if (_scanned_nmethod != NULL && cf != NULL) { 3308 // Safepoints can occur when the sweeper is scanning an nmethod so 3309 // process it here to make sure it isn't unloaded in the middle of 3310 // a scan. 3311 cf->do_code_blob(_scanned_nmethod); 3312 } 3313 } 3314 3315 3316 // ======= Threads ======== 3317 3318 // The Threads class links together all active threads, and provides 3319 // operations over all threads. It is protected by its own Mutex 3320 // lock, which is also used in other contexts to protect thread 3321 // operations from having the thread being operated on from exiting 3322 // and going away unexpectedly (e.g., safepoint synchronization) 3323 3324 JavaThread* Threads::_thread_list = NULL; 3325 int Threads::_number_of_threads = 0; 3326 int Threads::_number_of_non_daemon_threads = 0; 3327 int Threads::_return_code = 0; 3328 int Threads::_thread_claim_parity = 0; 3329 size_t JavaThread::_stack_size_at_create = 0; 3330 #ifdef ASSERT 3331 bool Threads::_vm_complete = false; 3332 #endif 3333 3334 // All JavaThreads 3335 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3336 3337 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3338 void Threads::threads_do(ThreadClosure* tc) { 3339 assert_locked_or_safepoint(Threads_lock); 3340 // ALL_JAVA_THREADS iterates through all JavaThreads 3341 ALL_JAVA_THREADS(p) { 3342 tc->do_thread(p); 3343 } 3344 // Someday we could have a table or list of all non-JavaThreads. 3345 // For now, just manually iterate through them. 3346 tc->do_thread(VMThread::vm_thread()); 3347 Universe::heap()->gc_threads_do(tc); 3348 WatcherThread *wt = WatcherThread::watcher_thread(); 3349 // Strictly speaking, the following NULL check isn't sufficient to make sure 3350 // the data for WatcherThread is still valid upon being examined. However, 3351 // considering that WatchThread terminates when the VM is on the way to 3352 // exit at safepoint, the chance of the above is extremely small. The right 3353 // way to prevent termination of WatcherThread would be to acquire 3354 // Terminator_lock, but we can't do that without violating the lock rank 3355 // checking in some cases. 3356 if (wt != NULL) { 3357 tc->do_thread(wt); 3358 } 3359 3360 // If CompilerThreads ever become non-JavaThreads, add them here 3361 } 3362 3363 // The system initialization in the library has three phases. 3364 // 3365 // Phase 1: java.lang.System class initialization 3366 // java.lang.System is a primordial class loaded and initialized 3367 // by the VM early during startup. java.lang.System.<clinit> 3368 // only does registerNatives and keeps the rest of the class 3369 // initialization work later until thread initialization completes. 3370 // 3371 // System.initPhase1 initializes the system properties, the static 3372 // fields in, out, and err. Set up java signal handlers, OS-specific 3373 // system settings, and thread group of the main thread. 3374 static void call_initPhase1(TRAPS) { 3375 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3376 instanceKlassHandle klass (THREAD, k); 3377 3378 JavaValue result(T_VOID); 3379 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3380 vmSymbols::void_method_signature(), CHECK); 3381 } 3382 3383 // Phase 2. Module system initialization 3384 // This will initialize the module system. Only java.base classes 3385 // can be loaded until phase 2 completes. 3386 // 3387 // Call System.initPhase2 after the compiler initialization and jsr292 3388 // classes get initialized because module initialization runs a lot of java 3389 // code, that for performance reasons, should be compiled. Also, this will 3390 // enable the startup code to use lambda and other language features in this 3391 // phase and onward. 3392 // 3393 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3394 static void call_initPhase2(TRAPS) { 3395 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3396 instanceKlassHandle klass (THREAD, k); 3397 3398 JavaValue result(T_VOID); 3399 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3400 vmSymbols::void_method_signature(), CHECK); 3401 universe_post_module_init(); 3402 } 3403 3404 // Phase 3. final setup - set security manager, system class loader and TCCL 3405 // 3406 // This will instantiate and set the security manager, set the system class 3407 // loader as well as the thread context class loader. The security manager 3408 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3409 // other modules or the application's classpath. 3410 static void call_initPhase3(TRAPS) { 3411 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3412 instanceKlassHandle klass (THREAD, k); 3413 3414 JavaValue result(T_VOID); 3415 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3416 vmSymbols::void_method_signature(), CHECK); 3417 } 3418 3419 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3420 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3421 3422 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3423 create_vm_init_libraries(); 3424 } 3425 3426 initialize_class(vmSymbols::java_lang_String(), CHECK); 3427 3428 // Inject CompactStrings value after the static initializers for String ran. 3429 java_lang_String::set_compact_strings(CompactStrings); 3430 3431 // Initialize java_lang.System (needed before creating the thread) 3432 initialize_class(vmSymbols::java_lang_System(), CHECK); 3433 // The VM creates & returns objects of this class. Make sure it's initialized. 3434 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3435 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3436 Handle thread_group = create_initial_thread_group(CHECK); 3437 Universe::set_main_thread_group(thread_group()); 3438 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3439 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3440 main_thread->set_threadObj(thread_object); 3441 // Set thread status to running since main thread has 3442 // been started and running. 3443 java_lang_Thread::set_thread_status(thread_object, 3444 java_lang_Thread::RUNNABLE); 3445 3446 // The VM creates objects of this class. 3447 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK); 3448 3449 // The VM preresolves methods to these classes. Make sure that they get initialized 3450 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3451 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3452 3453 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3454 call_initPhase1(CHECK); 3455 3456 // get the Java runtime name after java.lang.System is initialized 3457 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3458 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3459 3460 // an instance of OutOfMemory exception has been allocated earlier 3461 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3462 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3463 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3464 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3465 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3466 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3467 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3468 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3469 } 3470 3471 void Threads::initialize_jsr292_core_classes(TRAPS) { 3472 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3473 3474 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3475 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3476 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3477 } 3478 3479 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3480 extern void JDK_Version_init(); 3481 3482 // Preinitialize version info. 3483 VM_Version::early_initialize(); 3484 3485 // Check version 3486 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3487 3488 // Initialize library-based TLS 3489 ThreadLocalStorage::init(); 3490 3491 // Initialize the output stream module 3492 ostream_init(); 3493 3494 // Process java launcher properties. 3495 Arguments::process_sun_java_launcher_properties(args); 3496 3497 // Initialize the os module 3498 os::init(); 3499 3500 // Record VM creation timing statistics 3501 TraceVmCreationTime create_vm_timer; 3502 create_vm_timer.start(); 3503 3504 // Initialize system properties. 3505 Arguments::init_system_properties(); 3506 3507 // So that JDK version can be used as a discriminator when parsing arguments 3508 JDK_Version_init(); 3509 3510 // Update/Initialize System properties after JDK version number is known 3511 Arguments::init_version_specific_system_properties(); 3512 3513 // Make sure to initialize log configuration *before* parsing arguments 3514 LogConfiguration::initialize(create_vm_timer.begin_time()); 3515 3516 // Parse arguments 3517 jint parse_result = Arguments::parse(args); 3518 if (parse_result != JNI_OK) return parse_result; 3519 3520 os::init_before_ergo(); 3521 3522 jint ergo_result = Arguments::apply_ergo(); 3523 if (ergo_result != JNI_OK) return ergo_result; 3524 3525 // Final check of all ranges after ergonomics which may change values. 3526 if (!CommandLineFlagRangeList::check_ranges()) { 3527 return JNI_EINVAL; 3528 } 3529 3530 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3531 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3532 if (!constraint_result) { 3533 return JNI_EINVAL; 3534 } 3535 3536 if (PauseAtStartup) { 3537 os::pause(); 3538 } 3539 3540 HOTSPOT_VM_INIT_BEGIN(); 3541 3542 // Timing (must come after argument parsing) 3543 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3544 3545 // Initialize the os module after parsing the args 3546 jint os_init_2_result = os::init_2(); 3547 if (os_init_2_result != JNI_OK) return os_init_2_result; 3548 3549 jint adjust_after_os_result = Arguments::adjust_after_os(); 3550 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3551 3552 // Initialize output stream logging 3553 ostream_init_log(); 3554 3555 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3556 // Must be before create_vm_init_agents() 3557 if (Arguments::init_libraries_at_startup()) { 3558 convert_vm_init_libraries_to_agents(); 3559 } 3560 3561 // Launch -agentlib/-agentpath and converted -Xrun agents 3562 if (Arguments::init_agents_at_startup()) { 3563 create_vm_init_agents(); 3564 } 3565 3566 // Initialize Threads state 3567 _thread_list = NULL; 3568 _number_of_threads = 0; 3569 _number_of_non_daemon_threads = 0; 3570 3571 // Initialize global data structures and create system classes in heap 3572 vm_init_globals(); 3573 3574 #if INCLUDE_JVMCI 3575 if (JVMCICounterSize > 0) { 3576 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3577 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3578 } else { 3579 JavaThread::_jvmci_old_thread_counters = NULL; 3580 } 3581 #endif // INCLUDE_JVMCI 3582 3583 // Attach the main thread to this os thread 3584 JavaThread* main_thread = new JavaThread(); 3585 main_thread->set_thread_state(_thread_in_vm); 3586 main_thread->initialize_thread_current(); 3587 // must do this before set_active_handles 3588 main_thread->record_stack_base_and_size(); 3589 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3590 3591 if (!main_thread->set_as_starting_thread()) { 3592 vm_shutdown_during_initialization( 3593 "Failed necessary internal allocation. Out of swap space"); 3594 delete main_thread; 3595 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3596 return JNI_ENOMEM; 3597 } 3598 3599 // Enable guard page *after* os::create_main_thread(), otherwise it would 3600 // crash Linux VM, see notes in os_linux.cpp. 3601 main_thread->create_stack_guard_pages(); 3602 3603 // Initialize Java-Level synchronization subsystem 3604 ObjectMonitor::Initialize(); 3605 3606 // Initialize global modules 3607 jint status = init_globals(); 3608 if (status != JNI_OK) { 3609 delete main_thread; 3610 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3611 return status; 3612 } 3613 3614 if (TRACE_INITIALIZE() != JNI_OK) { 3615 vm_exit_during_initialization("Failed to initialize tracing backend"); 3616 } 3617 3618 // Should be done after the heap is fully created 3619 main_thread->cache_global_variables(); 3620 3621 HandleMark hm; 3622 3623 { MutexLocker mu(Threads_lock); 3624 Threads::add(main_thread); 3625 } 3626 3627 // Any JVMTI raw monitors entered in onload will transition into 3628 // real raw monitor. VM is setup enough here for raw monitor enter. 3629 JvmtiExport::transition_pending_onload_raw_monitors(); 3630 3631 // Create the VMThread 3632 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3633 3634 VMThread::create(); 3635 Thread* vmthread = VMThread::vm_thread(); 3636 3637 if (!os::create_thread(vmthread, os::vm_thread)) { 3638 vm_exit_during_initialization("Cannot create VM thread. " 3639 "Out of system resources."); 3640 } 3641 3642 // Wait for the VM thread to become ready, and VMThread::run to initialize 3643 // Monitors can have spurious returns, must always check another state flag 3644 { 3645 MutexLocker ml(Notify_lock); 3646 os::start_thread(vmthread); 3647 while (vmthread->active_handles() == NULL) { 3648 Notify_lock->wait(); 3649 } 3650 } 3651 } 3652 3653 assert(Universe::is_fully_initialized(), "not initialized"); 3654 if (VerifyDuringStartup) { 3655 // Make sure we're starting with a clean slate. 3656 VM_Verify verify_op; 3657 VMThread::execute(&verify_op); 3658 } 3659 3660 Thread* THREAD = Thread::current(); 3661 3662 // At this point, the Universe is initialized, but we have not executed 3663 // any byte code. Now is a good time (the only time) to dump out the 3664 // internal state of the JVM for sharing. 3665 if (DumpSharedSpaces) { 3666 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3667 ShouldNotReachHere(); 3668 } 3669 3670 // Always call even when there are not JVMTI environments yet, since environments 3671 // may be attached late and JVMTI must track phases of VM execution 3672 JvmtiExport::enter_early_start_phase(); 3673 3674 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3675 JvmtiExport::post_early_vm_start(); 3676 3677 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3678 3679 // We need this for ClassDataSharing - the initial vm.info property is set 3680 // with the default value of CDS "sharing" which may be reset through 3681 // command line options. 3682 reset_vm_info_property(CHECK_JNI_ERR); 3683 3684 quicken_jni_functions(); 3685 3686 // No more stub generation allowed after that point. 3687 StubCodeDesc::freeze(); 3688 3689 // Set flag that basic initialization has completed. Used by exceptions and various 3690 // debug stuff, that does not work until all basic classes have been initialized. 3691 set_init_completed(); 3692 3693 LogConfiguration::post_initialize(); 3694 Metaspace::post_initialize(); 3695 3696 HOTSPOT_VM_INIT_END(); 3697 3698 // record VM initialization completion time 3699 #if INCLUDE_MANAGEMENT 3700 Management::record_vm_init_completed(); 3701 #endif // INCLUDE_MANAGEMENT 3702 3703 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3704 // set_init_completed has just been called, causing exceptions not to be shortcut 3705 // anymore. We call vm_exit_during_initialization directly instead. 3706 3707 // Initialize reference pending list locker 3708 bool needs_locker_thread = Universe::heap()->needs_reference_pending_list_locker_thread(); 3709 ReferencePendingListLocker::initialize(needs_locker_thread, CHECK_JNI_ERR); 3710 3711 // Signal Dispatcher needs to be started before VMInit event is posted 3712 os::signal_init(); 3713 3714 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3715 if (!DisableAttachMechanism) { 3716 AttachListener::vm_start(); 3717 if (StartAttachListener || AttachListener::init_at_startup()) { 3718 AttachListener::init(); 3719 } 3720 } 3721 3722 // Launch -Xrun agents 3723 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3724 // back-end can launch with -Xdebug -Xrunjdwp. 3725 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3726 create_vm_init_libraries(); 3727 } 3728 3729 if (CleanChunkPoolAsync) { 3730 Chunk::start_chunk_pool_cleaner_task(); 3731 } 3732 3733 // initialize compiler(s) 3734 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3735 CompileBroker::compilation_init(CHECK_JNI_ERR); 3736 #endif 3737 3738 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3739 // It is done after compilers are initialized, because otherwise compilations of 3740 // signature polymorphic MH intrinsics can be missed 3741 // (see SystemDictionary::find_method_handle_intrinsic). 3742 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3743 3744 // This will initialize the module system. Only java.base classes can be 3745 // loaded until phase 2 completes 3746 call_initPhase2(CHECK_JNI_ERR); 3747 3748 // Always call even when there are not JVMTI environments yet, since environments 3749 // may be attached late and JVMTI must track phases of VM execution 3750 JvmtiExport::enter_start_phase(); 3751 3752 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3753 JvmtiExport::post_vm_start(); 3754 3755 // Final system initialization including security manager and system class loader 3756 call_initPhase3(CHECK_JNI_ERR); 3757 3758 // cache the system class loader 3759 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3760 3761 // Always call even when there are not JVMTI environments yet, since environments 3762 // may be attached late and JVMTI must track phases of VM execution 3763 JvmtiExport::enter_live_phase(); 3764 3765 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3766 JvmtiExport::post_vm_initialized(); 3767 3768 if (TRACE_START() != JNI_OK) { 3769 vm_exit_during_initialization("Failed to start tracing backend."); 3770 } 3771 3772 #if INCLUDE_MANAGEMENT 3773 Management::initialize(THREAD); 3774 3775 if (HAS_PENDING_EXCEPTION) { 3776 // management agent fails to start possibly due to 3777 // configuration problem and is responsible for printing 3778 // stack trace if appropriate. Simply exit VM. 3779 vm_exit(1); 3780 } 3781 #endif // INCLUDE_MANAGEMENT 3782 3783 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3784 if (MemProfiling) MemProfiler::engage(); 3785 StatSampler::engage(); 3786 if (CheckJNICalls) JniPeriodicChecker::engage(); 3787 3788 BiasedLocking::init(); 3789 3790 #if INCLUDE_RTM_OPT 3791 RTMLockingCounters::init(); 3792 #endif 3793 3794 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3795 call_postVMInitHook(THREAD); 3796 // The Java side of PostVMInitHook.run must deal with all 3797 // exceptions and provide means of diagnosis. 3798 if (HAS_PENDING_EXCEPTION) { 3799 CLEAR_PENDING_EXCEPTION; 3800 } 3801 } 3802 3803 { 3804 MutexLocker ml(PeriodicTask_lock); 3805 // Make sure the WatcherThread can be started by WatcherThread::start() 3806 // or by dynamic enrollment. 3807 WatcherThread::make_startable(); 3808 // Start up the WatcherThread if there are any periodic tasks 3809 // NOTE: All PeriodicTasks should be registered by now. If they 3810 // aren't, late joiners might appear to start slowly (we might 3811 // take a while to process their first tick). 3812 if (PeriodicTask::num_tasks() > 0) { 3813 WatcherThread::start(); 3814 } 3815 } 3816 3817 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM); 3818 3819 create_vm_timer.end(); 3820 #ifdef ASSERT 3821 _vm_complete = true; 3822 #endif 3823 return JNI_OK; 3824 } 3825 3826 // type for the Agent_OnLoad and JVM_OnLoad entry points 3827 extern "C" { 3828 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3829 } 3830 // Find a command line agent library and return its entry point for 3831 // -agentlib: -agentpath: -Xrun 3832 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3833 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3834 const char *on_load_symbols[], 3835 size_t num_symbol_entries) { 3836 OnLoadEntry_t on_load_entry = NULL; 3837 void *library = NULL; 3838 3839 if (!agent->valid()) { 3840 char buffer[JVM_MAXPATHLEN]; 3841 char ebuf[1024] = ""; 3842 const char *name = agent->name(); 3843 const char *msg = "Could not find agent library "; 3844 3845 // First check to see if agent is statically linked into executable 3846 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3847 library = agent->os_lib(); 3848 } else if (agent->is_absolute_path()) { 3849 library = os::dll_load(name, ebuf, sizeof ebuf); 3850 if (library == NULL) { 3851 const char *sub_msg = " in absolute path, with error: "; 3852 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3853 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3854 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3855 // If we can't find the agent, exit. 3856 vm_exit_during_initialization(buf, NULL); 3857 FREE_C_HEAP_ARRAY(char, buf); 3858 } 3859 } else { 3860 // Try to load the agent from the standard dll directory 3861 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3862 name)) { 3863 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3864 } 3865 if (library == NULL) { // Try the local directory 3866 char ns[1] = {0}; 3867 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3868 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3869 } 3870 if (library == NULL) { 3871 const char *sub_msg = " on the library path, with error: "; 3872 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3873 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3874 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3875 // If we can't find the agent, exit. 3876 vm_exit_during_initialization(buf, NULL); 3877 FREE_C_HEAP_ARRAY(char, buf); 3878 } 3879 } 3880 } 3881 agent->set_os_lib(library); 3882 agent->set_valid(); 3883 } 3884 3885 // Find the OnLoad function. 3886 on_load_entry = 3887 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3888 false, 3889 on_load_symbols, 3890 num_symbol_entries)); 3891 return on_load_entry; 3892 } 3893 3894 // Find the JVM_OnLoad entry point 3895 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3896 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3897 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3898 } 3899 3900 // Find the Agent_OnLoad entry point 3901 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3902 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3903 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3904 } 3905 3906 // For backwards compatibility with -Xrun 3907 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3908 // treated like -agentpath: 3909 // Must be called before agent libraries are created 3910 void Threads::convert_vm_init_libraries_to_agents() { 3911 AgentLibrary* agent; 3912 AgentLibrary* next; 3913 3914 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3915 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3916 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3917 3918 // If there is an JVM_OnLoad function it will get called later, 3919 // otherwise see if there is an Agent_OnLoad 3920 if (on_load_entry == NULL) { 3921 on_load_entry = lookup_agent_on_load(agent); 3922 if (on_load_entry != NULL) { 3923 // switch it to the agent list -- so that Agent_OnLoad will be called, 3924 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3925 Arguments::convert_library_to_agent(agent); 3926 } else { 3927 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3928 } 3929 } 3930 } 3931 } 3932 3933 // Create agents for -agentlib: -agentpath: and converted -Xrun 3934 // Invokes Agent_OnLoad 3935 // Called very early -- before JavaThreads exist 3936 void Threads::create_vm_init_agents() { 3937 extern struct JavaVM_ main_vm; 3938 AgentLibrary* agent; 3939 3940 JvmtiExport::enter_onload_phase(); 3941 3942 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3943 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3944 3945 if (on_load_entry != NULL) { 3946 // Invoke the Agent_OnLoad function 3947 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3948 if (err != JNI_OK) { 3949 vm_exit_during_initialization("agent library failed to init", agent->name()); 3950 } 3951 } else { 3952 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3953 } 3954 } 3955 JvmtiExport::enter_primordial_phase(); 3956 } 3957 3958 extern "C" { 3959 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3960 } 3961 3962 void Threads::shutdown_vm_agents() { 3963 // Send any Agent_OnUnload notifications 3964 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3965 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3966 extern struct JavaVM_ main_vm; 3967 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3968 3969 // Find the Agent_OnUnload function. 3970 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3971 os::find_agent_function(agent, 3972 false, 3973 on_unload_symbols, 3974 num_symbol_entries)); 3975 3976 // Invoke the Agent_OnUnload function 3977 if (unload_entry != NULL) { 3978 JavaThread* thread = JavaThread::current(); 3979 ThreadToNativeFromVM ttn(thread); 3980 HandleMark hm(thread); 3981 (*unload_entry)(&main_vm); 3982 } 3983 } 3984 } 3985 3986 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3987 // Invokes JVM_OnLoad 3988 void Threads::create_vm_init_libraries() { 3989 extern struct JavaVM_ main_vm; 3990 AgentLibrary* agent; 3991 3992 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3993 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3994 3995 if (on_load_entry != NULL) { 3996 // Invoke the JVM_OnLoad function 3997 JavaThread* thread = JavaThread::current(); 3998 ThreadToNativeFromVM ttn(thread); 3999 HandleMark hm(thread); 4000 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4001 if (err != JNI_OK) { 4002 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4003 } 4004 } else { 4005 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4006 } 4007 } 4008 } 4009 4010 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4011 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4012 4013 JavaThread* java_thread = NULL; 4014 // Sequential search for now. Need to do better optimization later. 4015 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4016 oop tobj = thread->threadObj(); 4017 if (!thread->is_exiting() && 4018 tobj != NULL && 4019 java_tid == java_lang_Thread::thread_id(tobj)) { 4020 java_thread = thread; 4021 break; 4022 } 4023 } 4024 return java_thread; 4025 } 4026 4027 4028 // Last thread running calls java.lang.Shutdown.shutdown() 4029 void JavaThread::invoke_shutdown_hooks() { 4030 HandleMark hm(this); 4031 4032 // We could get here with a pending exception, if so clear it now. 4033 if (this->has_pending_exception()) { 4034 this->clear_pending_exception(); 4035 } 4036 4037 EXCEPTION_MARK; 4038 Klass* k = 4039 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4040 THREAD); 4041 if (k != NULL) { 4042 // SystemDictionary::resolve_or_null will return null if there was 4043 // an exception. If we cannot load the Shutdown class, just don't 4044 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4045 // and finalizers (if runFinalizersOnExit is set) won't be run. 4046 // Note that if a shutdown hook was registered or runFinalizersOnExit 4047 // was called, the Shutdown class would have already been loaded 4048 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4049 instanceKlassHandle shutdown_klass (THREAD, k); 4050 JavaValue result(T_VOID); 4051 JavaCalls::call_static(&result, 4052 shutdown_klass, 4053 vmSymbols::shutdown_method_name(), 4054 vmSymbols::void_method_signature(), 4055 THREAD); 4056 } 4057 CLEAR_PENDING_EXCEPTION; 4058 } 4059 4060 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4061 // the program falls off the end of main(). Another VM exit path is through 4062 // vm_exit() when the program calls System.exit() to return a value or when 4063 // there is a serious error in VM. The two shutdown paths are not exactly 4064 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4065 // and VM_Exit op at VM level. 4066 // 4067 // Shutdown sequence: 4068 // + Shutdown native memory tracking if it is on 4069 // + Wait until we are the last non-daemon thread to execute 4070 // <-- every thing is still working at this moment --> 4071 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4072 // shutdown hooks, run finalizers if finalization-on-exit 4073 // + Call before_exit(), prepare for VM exit 4074 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4075 // currently the only user of this mechanism is File.deleteOnExit()) 4076 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4077 // post thread end and vm death events to JVMTI, 4078 // stop signal thread 4079 // + Call JavaThread::exit(), it will: 4080 // > release JNI handle blocks, remove stack guard pages 4081 // > remove this thread from Threads list 4082 // <-- no more Java code from this thread after this point --> 4083 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4084 // the compiler threads at safepoint 4085 // <-- do not use anything that could get blocked by Safepoint --> 4086 // + Disable tracing at JNI/JVM barriers 4087 // + Set _vm_exited flag for threads that are still running native code 4088 // + Delete this thread 4089 // + Call exit_globals() 4090 // > deletes tty 4091 // > deletes PerfMemory resources 4092 // + Return to caller 4093 4094 bool Threads::destroy_vm() { 4095 JavaThread* thread = JavaThread::current(); 4096 4097 #ifdef ASSERT 4098 _vm_complete = false; 4099 #endif 4100 // Wait until we are the last non-daemon thread to execute 4101 { MutexLocker nu(Threads_lock); 4102 while (Threads::number_of_non_daemon_threads() > 1) 4103 // This wait should make safepoint checks, wait without a timeout, 4104 // and wait as a suspend-equivalent condition. 4105 // 4106 // Note: If the FlatProfiler is running and this thread is waiting 4107 // for another non-daemon thread to finish, then the FlatProfiler 4108 // is waiting for the external suspend request on this thread to 4109 // complete. wait_for_ext_suspend_completion() will eventually 4110 // timeout, but that takes time. Making this wait a suspend- 4111 // equivalent condition solves that timeout problem. 4112 // 4113 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4114 Mutex::_as_suspend_equivalent_flag); 4115 } 4116 4117 // Hang forever on exit if we are reporting an error. 4118 if (ShowMessageBoxOnError && is_error_reported()) { 4119 os::infinite_sleep(); 4120 } 4121 os::wait_for_keypress_at_exit(); 4122 4123 // run Java level shutdown hooks 4124 thread->invoke_shutdown_hooks(); 4125 4126 before_exit(thread); 4127 4128 thread->exit(true); 4129 4130 // Stop VM thread. 4131 { 4132 // 4945125 The vm thread comes to a safepoint during exit. 4133 // GC vm_operations can get caught at the safepoint, and the 4134 // heap is unparseable if they are caught. Grab the Heap_lock 4135 // to prevent this. The GC vm_operations will not be able to 4136 // queue until after the vm thread is dead. After this point, 4137 // we'll never emerge out of the safepoint before the VM exits. 4138 4139 MutexLocker ml(Heap_lock); 4140 4141 VMThread::wait_for_vm_thread_exit(); 4142 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4143 VMThread::destroy(); 4144 } 4145 4146 // clean up ideal graph printers 4147 #if defined(COMPILER2) && !defined(PRODUCT) 4148 IdealGraphPrinter::clean_up(); 4149 #endif 4150 4151 // Now, all Java threads are gone except daemon threads. Daemon threads 4152 // running Java code or in VM are stopped by the Safepoint. However, 4153 // daemon threads executing native code are still running. But they 4154 // will be stopped at native=>Java/VM barriers. Note that we can't 4155 // simply kill or suspend them, as it is inherently deadlock-prone. 4156 4157 VM_Exit::set_vm_exited(); 4158 4159 notify_vm_shutdown(); 4160 4161 delete thread; 4162 4163 #if INCLUDE_JVMCI 4164 if (JVMCICounterSize > 0) { 4165 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4166 } 4167 #endif 4168 4169 // exit_globals() will delete tty 4170 exit_globals(); 4171 4172 LogConfiguration::finalize(); 4173 4174 return true; 4175 } 4176 4177 4178 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4179 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4180 return is_supported_jni_version(version); 4181 } 4182 4183 4184 jboolean Threads::is_supported_jni_version(jint version) { 4185 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4186 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4187 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4188 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4189 if (version == JNI_VERSION_9) return JNI_TRUE; 4190 return JNI_FALSE; 4191 } 4192 4193 4194 void Threads::add(JavaThread* p, bool force_daemon) { 4195 // The threads lock must be owned at this point 4196 assert_locked_or_safepoint(Threads_lock); 4197 4198 // See the comment for this method in thread.hpp for its purpose and 4199 // why it is called here. 4200 p->initialize_queues(); 4201 p->set_next(_thread_list); 4202 _thread_list = p; 4203 _number_of_threads++; 4204 oop threadObj = p->threadObj(); 4205 bool daemon = true; 4206 // Bootstrapping problem: threadObj can be null for initial 4207 // JavaThread (or for threads attached via JNI) 4208 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4209 _number_of_non_daemon_threads++; 4210 daemon = false; 4211 } 4212 4213 ThreadService::add_thread(p, daemon); 4214 4215 // Possible GC point. 4216 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4217 } 4218 4219 void Threads::remove(JavaThread* p) { 4220 // Extra scope needed for Thread_lock, so we can check 4221 // that we do not remove thread without safepoint code notice 4222 { MutexLocker ml(Threads_lock); 4223 4224 assert(includes(p), "p must be present"); 4225 4226 JavaThread* current = _thread_list; 4227 JavaThread* prev = NULL; 4228 4229 while (current != p) { 4230 prev = current; 4231 current = current->next(); 4232 } 4233 4234 if (prev) { 4235 prev->set_next(current->next()); 4236 } else { 4237 _thread_list = p->next(); 4238 } 4239 _number_of_threads--; 4240 oop threadObj = p->threadObj(); 4241 bool daemon = true; 4242 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4243 _number_of_non_daemon_threads--; 4244 daemon = false; 4245 4246 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4247 // on destroy_vm will wake up. 4248 if (number_of_non_daemon_threads() == 1) { 4249 Threads_lock->notify_all(); 4250 } 4251 } 4252 ThreadService::remove_thread(p, daemon); 4253 4254 // Make sure that safepoint code disregard this thread. This is needed since 4255 // the thread might mess around with locks after this point. This can cause it 4256 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4257 // of this thread since it is removed from the queue. 4258 p->set_terminated_value(); 4259 } // unlock Threads_lock 4260 4261 // Since Events::log uses a lock, we grab it outside the Threads_lock 4262 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4263 } 4264 4265 // Threads_lock must be held when this is called (or must be called during a safepoint) 4266 bool Threads::includes(JavaThread* p) { 4267 assert(Threads_lock->is_locked(), "sanity check"); 4268 ALL_JAVA_THREADS(q) { 4269 if (q == p) { 4270 return true; 4271 } 4272 } 4273 return false; 4274 } 4275 4276 // Operations on the Threads list for GC. These are not explicitly locked, 4277 // but the garbage collector must provide a safe context for them to run. 4278 // In particular, these things should never be called when the Threads_lock 4279 // is held by some other thread. (Note: the Safepoint abstraction also 4280 // uses the Threads_lock to guarantee this property. It also makes sure that 4281 // all threads gets blocked when exiting or starting). 4282 4283 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4284 ALL_JAVA_THREADS(p) { 4285 p->oops_do(f, cld_f, cf); 4286 } 4287 VMThread::vm_thread()->oops_do(f, cld_f, cf); 4288 } 4289 4290 void Threads::change_thread_claim_parity() { 4291 // Set the new claim parity. 4292 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4293 "Not in range."); 4294 _thread_claim_parity++; 4295 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4296 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4297 "Not in range."); 4298 } 4299 4300 #ifdef ASSERT 4301 void Threads::assert_all_threads_claimed() { 4302 ALL_JAVA_THREADS(p) { 4303 const int thread_parity = p->oops_do_parity(); 4304 assert((thread_parity == _thread_claim_parity), 4305 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4306 } 4307 } 4308 #endif // ASSERT 4309 4310 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { 4311 int cp = Threads::thread_claim_parity(); 4312 ALL_JAVA_THREADS(p) { 4313 if (p->claim_oops_do(is_par, cp)) { 4314 p->oops_do(f, cld_f, cf); 4315 } 4316 } 4317 VMThread* vmt = VMThread::vm_thread(); 4318 if (vmt->claim_oops_do(is_par, cp)) { 4319 vmt->oops_do(f, cld_f, cf); 4320 } 4321 } 4322 4323 #if INCLUDE_ALL_GCS 4324 // Used by ParallelScavenge 4325 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4326 ALL_JAVA_THREADS(p) { 4327 q->enqueue(new ThreadRootsTask(p)); 4328 } 4329 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4330 } 4331 4332 // Used by Parallel Old 4333 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4334 ALL_JAVA_THREADS(p) { 4335 q->enqueue(new ThreadRootsMarkingTask(p)); 4336 } 4337 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4338 } 4339 #endif // INCLUDE_ALL_GCS 4340 4341 void Threads::nmethods_do(CodeBlobClosure* cf) { 4342 ALL_JAVA_THREADS(p) { 4343 p->nmethods_do(cf); 4344 } 4345 VMThread::vm_thread()->nmethods_do(cf); 4346 } 4347 4348 void Threads::metadata_do(void f(Metadata*)) { 4349 ALL_JAVA_THREADS(p) { 4350 p->metadata_do(f); 4351 } 4352 } 4353 4354 class ThreadHandlesClosure : public ThreadClosure { 4355 void (*_f)(Metadata*); 4356 public: 4357 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4358 virtual void do_thread(Thread* thread) { 4359 thread->metadata_handles_do(_f); 4360 } 4361 }; 4362 4363 void Threads::metadata_handles_do(void f(Metadata*)) { 4364 // Only walk the Handles in Thread. 4365 ThreadHandlesClosure handles_closure(f); 4366 threads_do(&handles_closure); 4367 } 4368 4369 void Threads::deoptimized_wrt_marked_nmethods() { 4370 ALL_JAVA_THREADS(p) { 4371 p->deoptimized_wrt_marked_nmethods(); 4372 } 4373 } 4374 4375 4376 // Get count Java threads that are waiting to enter the specified monitor. 4377 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4378 address monitor, 4379 bool doLock) { 4380 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4381 "must grab Threads_lock or be at safepoint"); 4382 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4383 4384 int i = 0; 4385 { 4386 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4387 ALL_JAVA_THREADS(p) { 4388 if (!p->can_call_java()) continue; 4389 4390 address pending = (address)p->current_pending_monitor(); 4391 if (pending == monitor) { // found a match 4392 if (i < count) result->append(p); // save the first count matches 4393 i++; 4394 } 4395 } 4396 } 4397 return result; 4398 } 4399 4400 4401 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4402 bool doLock) { 4403 assert(doLock || 4404 Threads_lock->owned_by_self() || 4405 SafepointSynchronize::is_at_safepoint(), 4406 "must grab Threads_lock or be at safepoint"); 4407 4408 // NULL owner means not locked so we can skip the search 4409 if (owner == NULL) return NULL; 4410 4411 { 4412 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4413 ALL_JAVA_THREADS(p) { 4414 // first, see if owner is the address of a Java thread 4415 if (owner == (address)p) return p; 4416 } 4417 } 4418 // Cannot assert on lack of success here since this function may be 4419 // used by code that is trying to report useful problem information 4420 // like deadlock detection. 4421 if (UseHeavyMonitors) return NULL; 4422 4423 // If we didn't find a matching Java thread and we didn't force use of 4424 // heavyweight monitors, then the owner is the stack address of the 4425 // Lock Word in the owning Java thread's stack. 4426 // 4427 JavaThread* the_owner = NULL; 4428 { 4429 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4430 ALL_JAVA_THREADS(q) { 4431 if (q->is_lock_owned(owner)) { 4432 the_owner = q; 4433 break; 4434 } 4435 } 4436 } 4437 // cannot assert on lack of success here; see above comment 4438 return the_owner; 4439 } 4440 4441 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4442 void Threads::print_on(outputStream* st, bool print_stacks, 4443 bool internal_format, bool print_concurrent_locks) { 4444 char buf[32]; 4445 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4446 4447 st->print_cr("Full thread dump %s (%s %s):", 4448 Abstract_VM_Version::vm_name(), 4449 Abstract_VM_Version::vm_release(), 4450 Abstract_VM_Version::vm_info_string()); 4451 st->cr(); 4452 4453 #if INCLUDE_SERVICES 4454 // Dump concurrent locks 4455 ConcurrentLocksDump concurrent_locks; 4456 if (print_concurrent_locks) { 4457 concurrent_locks.dump_at_safepoint(); 4458 } 4459 #endif // INCLUDE_SERVICES 4460 4461 ALL_JAVA_THREADS(p) { 4462 ResourceMark rm; 4463 p->print_on(st); 4464 if (print_stacks) { 4465 if (internal_format) { 4466 p->trace_stack(); 4467 } else { 4468 p->print_stack_on(st); 4469 } 4470 } 4471 st->cr(); 4472 #if INCLUDE_SERVICES 4473 if (print_concurrent_locks) { 4474 concurrent_locks.print_locks_on(p, st); 4475 } 4476 #endif // INCLUDE_SERVICES 4477 } 4478 4479 VMThread::vm_thread()->print_on(st); 4480 st->cr(); 4481 Universe::heap()->print_gc_threads_on(st); 4482 WatcherThread* wt = WatcherThread::watcher_thread(); 4483 if (wt != NULL) { 4484 wt->print_on(st); 4485 st->cr(); 4486 } 4487 st->flush(); 4488 } 4489 4490 // Threads::print_on_error() is called by fatal error handler. It's possible 4491 // that VM is not at safepoint and/or current thread is inside signal handler. 4492 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4493 // memory (even in resource area), it might deadlock the error handler. 4494 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4495 int buflen) { 4496 bool found_current = false; 4497 st->print_cr("Java Threads: ( => current thread )"); 4498 ALL_JAVA_THREADS(thread) { 4499 bool is_current = (current == thread); 4500 found_current = found_current || is_current; 4501 4502 st->print("%s", is_current ? "=>" : " "); 4503 4504 st->print(PTR_FORMAT, p2i(thread)); 4505 st->print(" "); 4506 thread->print_on_error(st, buf, buflen); 4507 st->cr(); 4508 } 4509 st->cr(); 4510 4511 st->print_cr("Other Threads:"); 4512 if (VMThread::vm_thread()) { 4513 bool is_current = (current == VMThread::vm_thread()); 4514 found_current = found_current || is_current; 4515 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4516 4517 st->print(PTR_FORMAT, p2i(VMThread::vm_thread())); 4518 st->print(" "); 4519 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4520 st->cr(); 4521 } 4522 WatcherThread* wt = WatcherThread::watcher_thread(); 4523 if (wt != NULL) { 4524 bool is_current = (current == wt); 4525 found_current = found_current || is_current; 4526 st->print("%s", is_current ? "=>" : " "); 4527 4528 st->print(PTR_FORMAT, p2i(wt)); 4529 st->print(" "); 4530 wt->print_on_error(st, buf, buflen); 4531 st->cr(); 4532 } 4533 if (!found_current) { 4534 st->cr(); 4535 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4536 current->print_on_error(st, buf, buflen); 4537 st->cr(); 4538 } 4539 st->cr(); 4540 st->print_cr("Threads with active compile tasks:"); 4541 print_threads_compiling(st, buf, buflen); 4542 } 4543 4544 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4545 ALL_JAVA_THREADS(thread) { 4546 if (thread->is_Compiler_thread()) { 4547 CompilerThread* ct = (CompilerThread*) thread; 4548 if (ct->task() != NULL) { 4549 thread->print_name_on_error(st, buf, buflen); 4550 ct->task()->print(st, NULL, true, true); 4551 } 4552 } 4553 } 4554 } 4555 4556 4557 // Internal SpinLock and Mutex 4558 // Based on ParkEvent 4559 4560 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4561 // 4562 // We employ SpinLocks _only for low-contention, fixed-length 4563 // short-duration critical sections where we're concerned 4564 // about native mutex_t or HotSpot Mutex:: latency. 4565 // The mux construct provides a spin-then-block mutual exclusion 4566 // mechanism. 4567 // 4568 // Testing has shown that contention on the ListLock guarding gFreeList 4569 // is common. If we implement ListLock as a simple SpinLock it's common 4570 // for the JVM to devolve to yielding with little progress. This is true 4571 // despite the fact that the critical sections protected by ListLock are 4572 // extremely short. 4573 // 4574 // TODO-FIXME: ListLock should be of type SpinLock. 4575 // We should make this a 1st-class type, integrated into the lock 4576 // hierarchy as leaf-locks. Critically, the SpinLock structure 4577 // should have sufficient padding to avoid false-sharing and excessive 4578 // cache-coherency traffic. 4579 4580 4581 typedef volatile int SpinLockT; 4582 4583 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4584 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4585 return; // normal fast-path return 4586 } 4587 4588 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4589 TEVENT(SpinAcquire - ctx); 4590 int ctr = 0; 4591 int Yields = 0; 4592 for (;;) { 4593 while (*adr != 0) { 4594 ++ctr; 4595 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4596 if (Yields > 5) { 4597 os::naked_short_sleep(1); 4598 } else { 4599 os::naked_yield(); 4600 ++Yields; 4601 } 4602 } else { 4603 SpinPause(); 4604 } 4605 } 4606 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4607 } 4608 } 4609 4610 void Thread::SpinRelease(volatile int * adr) { 4611 assert(*adr != 0, "invariant"); 4612 OrderAccess::fence(); // guarantee at least release consistency. 4613 // Roach-motel semantics. 4614 // It's safe if subsequent LDs and STs float "up" into the critical section, 4615 // but prior LDs and STs within the critical section can't be allowed 4616 // to reorder or float past the ST that releases the lock. 4617 // Loads and stores in the critical section - which appear in program 4618 // order before the store that releases the lock - must also appear 4619 // before the store that releases the lock in memory visibility order. 4620 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4621 // the ST of 0 into the lock-word which releases the lock, so fence 4622 // more than covers this on all platforms. 4623 *adr = 0; 4624 } 4625 4626 // muxAcquire and muxRelease: 4627 // 4628 // * muxAcquire and muxRelease support a single-word lock-word construct. 4629 // The LSB of the word is set IFF the lock is held. 4630 // The remainder of the word points to the head of a singly-linked list 4631 // of threads blocked on the lock. 4632 // 4633 // * The current implementation of muxAcquire-muxRelease uses its own 4634 // dedicated Thread._MuxEvent instance. If we're interested in 4635 // minimizing the peak number of extant ParkEvent instances then 4636 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4637 // as certain invariants were satisfied. Specifically, care would need 4638 // to be taken with regards to consuming unpark() "permits". 4639 // A safe rule of thumb is that a thread would never call muxAcquire() 4640 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4641 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4642 // consume an unpark() permit intended for monitorenter, for instance. 4643 // One way around this would be to widen the restricted-range semaphore 4644 // implemented in park(). Another alternative would be to provide 4645 // multiple instances of the PlatformEvent() for each thread. One 4646 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4647 // 4648 // * Usage: 4649 // -- Only as leaf locks 4650 // -- for short-term locking only as muxAcquire does not perform 4651 // thread state transitions. 4652 // 4653 // Alternatives: 4654 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4655 // but with parking or spin-then-park instead of pure spinning. 4656 // * Use Taura-Oyama-Yonenzawa locks. 4657 // * It's possible to construct a 1-0 lock if we encode the lockword as 4658 // (List,LockByte). Acquire will CAS the full lockword while Release 4659 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4660 // acquiring threads use timers (ParkTimed) to detect and recover from 4661 // the stranding window. Thread/Node structures must be aligned on 256-byte 4662 // boundaries by using placement-new. 4663 // * Augment MCS with advisory back-link fields maintained with CAS(). 4664 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4665 // The validity of the backlinks must be ratified before we trust the value. 4666 // If the backlinks are invalid the exiting thread must back-track through the 4667 // the forward links, which are always trustworthy. 4668 // * Add a successor indication. The LockWord is currently encoded as 4669 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4670 // to provide the usual futile-wakeup optimization. 4671 // See RTStt for details. 4672 // * Consider schedctl.sc_nopreempt to cover the critical section. 4673 // 4674 4675 4676 typedef volatile intptr_t MutexT; // Mux Lock-word 4677 enum MuxBits { LOCKBIT = 1 }; 4678 4679 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4680 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4681 if (w == 0) return; 4682 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4683 return; 4684 } 4685 4686 TEVENT(muxAcquire - Contention); 4687 ParkEvent * const Self = Thread::current()->_MuxEvent; 4688 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4689 for (;;) { 4690 int its = (os::is_MP() ? 100 : 0) + 1; 4691 4692 // Optional spin phase: spin-then-park strategy 4693 while (--its >= 0) { 4694 w = *Lock; 4695 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4696 return; 4697 } 4698 } 4699 4700 Self->reset(); 4701 Self->OnList = intptr_t(Lock); 4702 // The following fence() isn't _strictly necessary as the subsequent 4703 // CAS() both serializes execution and ratifies the fetched *Lock value. 4704 OrderAccess::fence(); 4705 for (;;) { 4706 w = *Lock; 4707 if ((w & LOCKBIT) == 0) { 4708 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4709 Self->OnList = 0; // hygiene - allows stronger asserts 4710 return; 4711 } 4712 continue; // Interference -- *Lock changed -- Just retry 4713 } 4714 assert(w & LOCKBIT, "invariant"); 4715 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4716 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4717 } 4718 4719 while (Self->OnList != 0) { 4720 Self->park(); 4721 } 4722 } 4723 } 4724 4725 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4726 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4727 if (w == 0) return; 4728 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4729 return; 4730 } 4731 4732 TEVENT(muxAcquire - Contention); 4733 ParkEvent * ReleaseAfter = NULL; 4734 if (ev == NULL) { 4735 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4736 } 4737 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4738 for (;;) { 4739 guarantee(ev->OnList == 0, "invariant"); 4740 int its = (os::is_MP() ? 100 : 0) + 1; 4741 4742 // Optional spin phase: spin-then-park strategy 4743 while (--its >= 0) { 4744 w = *Lock; 4745 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4746 if (ReleaseAfter != NULL) { 4747 ParkEvent::Release(ReleaseAfter); 4748 } 4749 return; 4750 } 4751 } 4752 4753 ev->reset(); 4754 ev->OnList = intptr_t(Lock); 4755 // The following fence() isn't _strictly necessary as the subsequent 4756 // CAS() both serializes execution and ratifies the fetched *Lock value. 4757 OrderAccess::fence(); 4758 for (;;) { 4759 w = *Lock; 4760 if ((w & LOCKBIT) == 0) { 4761 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4762 ev->OnList = 0; 4763 // We call ::Release while holding the outer lock, thus 4764 // artificially lengthening the critical section. 4765 // Consider deferring the ::Release() until the subsequent unlock(), 4766 // after we've dropped the outer lock. 4767 if (ReleaseAfter != NULL) { 4768 ParkEvent::Release(ReleaseAfter); 4769 } 4770 return; 4771 } 4772 continue; // Interference -- *Lock changed -- Just retry 4773 } 4774 assert(w & LOCKBIT, "invariant"); 4775 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4776 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4777 } 4778 4779 while (ev->OnList != 0) { 4780 ev->park(); 4781 } 4782 } 4783 } 4784 4785 // Release() must extract a successor from the list and then wake that thread. 4786 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4787 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4788 // Release() would : 4789 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4790 // (B) Extract a successor from the private list "in-hand" 4791 // (C) attempt to CAS() the residual back into *Lock over null. 4792 // If there were any newly arrived threads and the CAS() would fail. 4793 // In that case Release() would detach the RATs, re-merge the list in-hand 4794 // with the RATs and repeat as needed. Alternately, Release() might 4795 // detach and extract a successor, but then pass the residual list to the wakee. 4796 // The wakee would be responsible for reattaching and remerging before it 4797 // competed for the lock. 4798 // 4799 // Both "pop" and DMR are immune from ABA corruption -- there can be 4800 // multiple concurrent pushers, but only one popper or detacher. 4801 // This implementation pops from the head of the list. This is unfair, 4802 // but tends to provide excellent throughput as hot threads remain hot. 4803 // (We wake recently run threads first). 4804 // 4805 // All paths through muxRelease() will execute a CAS. 4806 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4807 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4808 // executed within the critical section are complete and globally visible before the 4809 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4810 void Thread::muxRelease(volatile intptr_t * Lock) { 4811 for (;;) { 4812 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4813 assert(w & LOCKBIT, "invariant"); 4814 if (w == LOCKBIT) return; 4815 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4816 assert(List != NULL, "invariant"); 4817 assert(List->OnList == intptr_t(Lock), "invariant"); 4818 ParkEvent * const nxt = List->ListNext; 4819 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4820 4821 // The following CAS() releases the lock and pops the head element. 4822 // The CAS() also ratifies the previously fetched lock-word value. 4823 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4824 continue; 4825 } 4826 List->OnList = 0; 4827 OrderAccess::fence(); 4828 List->unpark(); 4829 return; 4830 } 4831 } 4832 4833 4834 void Threads::verify() { 4835 ALL_JAVA_THREADS(p) { 4836 p->verify(); 4837 } 4838 VMThread* thread = VMThread::vm_thread(); 4839 if (thread != NULL) thread->verify(); 4840 }