1 /* 2 * Copyright (c) 1997, 2017, 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 "jvm.h" 27 #include "classfile/classLoader.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.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/workgroup.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "interpreter/linkResolver.hpp" 41 #include "interpreter/oopMapCache.hpp" 42 #include "jvmtifiles/jvmtiEnv.hpp" 43 #include "logging/log.hpp" 44 #include "logging/logConfiguration.hpp" 45 #include "logging/logStream.hpp" 46 #include "memory/metaspaceShared.hpp" 47 #include "memory/oopFactory.hpp" 48 #include "memory/resourceArea.hpp" 49 #include "memory/universe.inline.hpp" 50 #include "oops/instanceKlass.hpp" 51 #include "oops/objArrayOop.hpp" 52 #include "oops/oop.inline.hpp" 53 #include "oops/symbol.hpp" 54 #include "oops/verifyOopClosure.hpp" 55 #include "prims/jvm_misc.hpp" 56 #include "prims/jvmtiExport.hpp" 57 #include "prims/jvmtiThreadState.hpp" 58 #include "prims/privilegedStack.hpp" 59 #include "runtime/arguments.hpp" 60 #include "runtime/atomic.hpp" 61 #include "runtime/biasedLocking.hpp" 62 #include "runtime/commandLineFlagConstraintList.hpp" 63 #include "runtime/commandLineFlagWriteableList.hpp" 64 #include "runtime/commandLineFlagRangeList.hpp" 65 #include "runtime/deoptimization.hpp" 66 #include "runtime/frame.inline.hpp" 67 #include "runtime/globals.hpp" 68 #include "runtime/handshake.hpp" 69 #include "runtime/init.hpp" 70 #include "runtime/interfaceSupport.hpp" 71 #include "runtime/java.hpp" 72 #include "runtime/javaCalls.hpp" 73 #include "runtime/jniPeriodicChecker.hpp" 74 #include "runtime/memprofiler.hpp" 75 #include "runtime/mutexLocker.hpp" 76 #include "runtime/objectMonitor.hpp" 77 #include "runtime/orderAccess.inline.hpp" 78 #include "runtime/osThread.hpp" 79 #include "runtime/prefetch.inline.hpp" 80 #include "runtime/safepoint.hpp" 81 #include "runtime/safepointMechanism.inline.hpp" 82 #include "runtime/sharedRuntime.hpp" 83 #include "runtime/statSampler.hpp" 84 #include "runtime/stubRoutines.hpp" 85 #include "runtime/sweeper.hpp" 86 #include "runtime/task.hpp" 87 #include "runtime/thread.inline.hpp" 88 #include "runtime/threadCritical.hpp" 89 #include "runtime/threadSMR.inline.hpp" 90 #include "runtime/timer.hpp" 91 #include "runtime/timerTrace.hpp" 92 #include "runtime/vframe.hpp" 93 #include "runtime/vframeArray.hpp" 94 #include "runtime/vframe_hp.hpp" 95 #include "runtime/vmThread.hpp" 96 #include "runtime/vm_operations.hpp" 97 #include "runtime/vm_version.hpp" 98 #include "services/attachListener.hpp" 99 #include "services/management.hpp" 100 #include "services/memTracker.hpp" 101 #include "services/threadService.hpp" 102 #include "trace/traceMacros.hpp" 103 #include "trace/tracing.hpp" 104 #include "utilities/align.hpp" 105 #include "utilities/defaultStream.hpp" 106 #include "utilities/dtrace.hpp" 107 #include "utilities/events.hpp" 108 #include "utilities/macros.hpp" 109 #include "utilities/preserveException.hpp" 110 #include "utilities/resourceHash.hpp" 111 #include "utilities/vmError.hpp" 112 #if INCLUDE_ALL_GCS 113 #include "gc/cms/concurrentMarkSweepThread.hpp" 114 #include "gc/g1/concurrentMarkThread.inline.hpp" 115 #include "gc/parallel/pcTasks.hpp" 116 #endif // INCLUDE_ALL_GCS 117 #if INCLUDE_JVMCI 118 #include "jvmci/jvmciCompiler.hpp" 119 #include "jvmci/jvmciRuntime.hpp" 120 #include "logging/logHandle.hpp" 121 #endif 122 #ifdef COMPILER1 123 #include "c1/c1_Compiler.hpp" 124 #endif 125 #ifdef COMPILER2 126 #include "opto/c2compiler.hpp" 127 #include "opto/idealGraphPrinter.hpp" 128 #endif 129 #if INCLUDE_RTM_OPT 130 #include "runtime/rtmLocking.hpp" 131 #endif 132 133 // Initialization after module runtime initialization 134 void universe_post_module_init(); // must happen after call_initPhase2 135 136 #ifdef DTRACE_ENABLED 137 138 // Only bother with this argument setup if dtrace is available 139 140 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 141 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 142 143 #define DTRACE_THREAD_PROBE(probe, javathread) \ 144 { \ 145 ResourceMark rm(this); \ 146 int len = 0; \ 147 const char* name = (javathread)->get_thread_name(); \ 148 len = strlen(name); \ 149 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 150 (char *) name, len, \ 151 java_lang_Thread::thread_id((javathread)->threadObj()), \ 152 (uintptr_t) (javathread)->osthread()->thread_id(), \ 153 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 154 } 155 156 #else // ndef DTRACE_ENABLED 157 158 #define DTRACE_THREAD_PROBE(probe, javathread) 159 160 #endif // ndef DTRACE_ENABLED 161 162 #ifndef USE_LIBRARY_BASED_TLS_ONLY 163 // Current thread is maintained as a thread-local variable 164 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 165 #endif 166 // Class hierarchy 167 // - Thread 168 // - VMThread 169 // - WatcherThread 170 // - ConcurrentMarkSweepThread 171 // - JavaThread 172 // - CompilerThread 173 174 // ======= Thread ======== 175 // Support for forcing alignment of thread objects for biased locking 176 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 177 if (UseBiasedLocking) { 178 const int alignment = markOopDesc::biased_lock_alignment; 179 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 180 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 181 : AllocateHeap(aligned_size, flags, CURRENT_PC, 182 AllocFailStrategy::RETURN_NULL); 183 void* aligned_addr = align_up(real_malloc_addr, alignment); 184 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 185 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 186 "JavaThread alignment code overflowed allocated storage"); 187 if (aligned_addr != real_malloc_addr) { 188 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 189 p2i(real_malloc_addr), 190 p2i(aligned_addr)); 191 } 192 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 193 return aligned_addr; 194 } else { 195 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 196 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 197 } 198 } 199 200 void Thread::operator delete(void* p) { 201 if (UseBiasedLocking) { 202 FreeHeap(((Thread*) p)->_real_malloc_address); 203 } else { 204 FreeHeap(p); 205 } 206 } 207 208 void JavaThread::smr_delete() { 209 if (_on_thread_list) { 210 Threads::smr_delete(this); 211 } else { 212 delete this; 213 } 214 } 215 216 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 217 // JavaThread 218 219 220 Thread::Thread() { 221 // stack and get_thread 222 set_stack_base(NULL); 223 set_stack_size(0); 224 set_self_raw_id(0); 225 set_lgrp_id(-1); 226 DEBUG_ONLY(clear_suspendible_thread();) 227 228 // allocated data structures 229 set_osthread(NULL); 230 set_resource_area(new (mtThread)ResourceArea()); 231 DEBUG_ONLY(_current_resource_mark = NULL;) 232 set_handle_area(new (mtThread) HandleArea(NULL)); 233 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 234 set_active_handles(NULL); 235 set_free_handle_block(NULL); 236 set_last_handle_mark(NULL); 237 238 // This initial value ==> never claimed. 239 _oops_do_parity = 0; 240 _threads_hazard_ptr = NULL; 241 _nested_threads_hazard_ptr = NULL; 242 _nested_threads_hazard_ptr_cnt = 0; 243 244 // the handle mark links itself to last_handle_mark 245 new HandleMark(this); 246 247 // plain initialization 248 debug_only(_owned_locks = NULL;) 249 debug_only(_allow_allocation_count = 0;) 250 NOT_PRODUCT(_allow_safepoint_count = 0;) 251 NOT_PRODUCT(_skip_gcalot = false;) 252 _jvmti_env_iteration_count = 0; 253 set_allocated_bytes(0); 254 _vm_operation_started_count = 0; 255 _vm_operation_completed_count = 0; 256 _current_pending_monitor = NULL; 257 _current_pending_monitor_is_from_java = true; 258 _current_waiting_monitor = NULL; 259 _num_nested_signal = 0; 260 omFreeList = NULL; 261 omFreeCount = 0; 262 omFreeProvision = 32; 263 omInUseList = NULL; 264 omInUseCount = 0; 265 266 #ifdef ASSERT 267 _visited_for_critical_count = false; 268 #endif 269 270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 271 Monitor::_safepoint_check_sometimes); 272 _suspend_flags = 0; 273 274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 275 _hashStateX = os::random(); 276 _hashStateY = 842502087; 277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 278 _hashStateW = 273326509; 279 280 _OnTrap = 0; 281 _schedctl = NULL; 282 _Stalled = 0; 283 _TypeTag = 0x2BAD; 284 285 // Many of the following fields are effectively final - immutable 286 // Note that nascent threads can't use the Native Monitor-Mutex 287 // construct until the _MutexEvent is initialized ... 288 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 289 // we might instead use a stack of ParkEvents that we could provision on-demand. 290 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 291 // and ::Release() 292 _ParkEvent = ParkEvent::Allocate(this); 293 _SleepEvent = ParkEvent::Allocate(this); 294 _MutexEvent = ParkEvent::Allocate(this); 295 _MuxEvent = ParkEvent::Allocate(this); 296 297 #ifdef CHECK_UNHANDLED_OOPS 298 if (CheckUnhandledOops) { 299 _unhandled_oops = new UnhandledOops(this); 300 } 301 #endif // CHECK_UNHANDLED_OOPS 302 #ifdef ASSERT 303 if (UseBiasedLocking) { 304 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 305 assert(this == _real_malloc_address || 306 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 307 "bug in forced alignment of thread objects"); 308 } 309 #endif // ASSERT 310 } 311 312 void Thread::initialize_thread_current() { 313 #ifndef USE_LIBRARY_BASED_TLS_ONLY 314 assert(_thr_current == NULL, "Thread::current already initialized"); 315 _thr_current = this; 316 #endif 317 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 318 ThreadLocalStorage::set_thread(this); 319 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 320 } 321 322 void Thread::clear_thread_current() { 323 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 324 #ifndef USE_LIBRARY_BASED_TLS_ONLY 325 _thr_current = NULL; 326 #endif 327 ThreadLocalStorage::set_thread(NULL); 328 } 329 330 void Thread::record_stack_base_and_size() { 331 set_stack_base(os::current_stack_base()); 332 set_stack_size(os::current_stack_size()); 333 // CR 7190089: on Solaris, primordial thread's stack is adjusted 334 // in initialize_thread(). Without the adjustment, stack size is 335 // incorrect if stack is set to unlimited (ulimit -s unlimited). 336 // So far, only Solaris has real implementation of initialize_thread(). 337 // 338 // set up any platform-specific state. 339 os::initialize_thread(this); 340 341 // Set stack limits after thread is initialized. 342 if (is_Java_thread()) { 343 ((JavaThread*) this)->set_stack_overflow_limit(); 344 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 345 } 346 #if INCLUDE_NMT 347 // record thread's native stack, stack grows downward 348 MemTracker::record_thread_stack(stack_end(), stack_size()); 349 #endif // INCLUDE_NMT 350 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 351 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 352 os::current_thread_id(), p2i(stack_base() - stack_size()), 353 p2i(stack_base()), stack_size()/1024); 354 } 355 356 357 Thread::~Thread() { 358 EVENT_THREAD_DESTRUCT(this); 359 360 // stack_base can be NULL if the thread is never started or exited before 361 // record_stack_base_and_size called. Although, we would like to ensure 362 // that all started threads do call record_stack_base_and_size(), there is 363 // not proper way to enforce that. 364 #if INCLUDE_NMT 365 if (_stack_base != NULL) { 366 MemTracker::release_thread_stack(stack_end(), stack_size()); 367 #ifdef ASSERT 368 set_stack_base(NULL); 369 #endif 370 } 371 #endif // INCLUDE_NMT 372 373 // deallocate data structures 374 delete resource_area(); 375 // since the handle marks are using the handle area, we have to deallocated the root 376 // handle mark before deallocating the thread's handle area, 377 assert(last_handle_mark() != NULL, "check we have an element"); 378 delete last_handle_mark(); 379 assert(last_handle_mark() == NULL, "check we have reached the end"); 380 381 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 382 // We NULL out the fields for good hygiene. 383 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 384 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 385 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 386 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 387 388 delete handle_area(); 389 delete metadata_handles(); 390 391 // SR_handler uses this as a termination indicator - 392 // needs to happen before os::free_thread() 393 delete _SR_lock; 394 _SR_lock = NULL; 395 396 // osthread() can be NULL, if creation of thread failed. 397 if (osthread() != NULL) os::free_thread(osthread()); 398 399 // clear Thread::current if thread is deleting itself. 400 // Needed to ensure JNI correctly detects non-attached threads. 401 if (this == Thread::current()) { 402 clear_thread_current(); 403 } 404 405 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 406 } 407 408 // NOTE: dummy function for assertion purpose. 409 void Thread::run() { 410 ShouldNotReachHere(); 411 } 412 413 #ifdef ASSERT 414 // A JavaThread is considered "dangling" if it is not the current 415 // thread, has been added the Threads list, the system is not at a 416 // safepoint and the Thread is not "protected". 417 // 418 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 419 assert(!thread->is_Java_thread() || Thread::current() == thread || 420 !((JavaThread *) thread)->on_thread_list() || 421 SafepointSynchronize::is_at_safepoint() || 422 Threads::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 423 "possibility of dangling Thread pointer"); 424 } 425 #endif 426 427 ThreadPriority Thread::get_priority(const Thread* const thread) { 428 ThreadPriority priority; 429 // Can return an error! 430 (void)os::get_priority(thread, priority); 431 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 432 return priority; 433 } 434 435 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 436 debug_only(check_for_dangling_thread_pointer(thread);) 437 // Can return an error! 438 (void)os::set_priority(thread, priority); 439 } 440 441 442 void Thread::start(Thread* thread) { 443 // Start is different from resume in that its safety is guaranteed by context or 444 // being called from a Java method synchronized on the Thread object. 445 if (!DisableStartThread) { 446 if (thread->is_Java_thread()) { 447 // Initialize the thread state to RUNNABLE before starting this thread. 448 // Can not set it after the thread started because we do not know the 449 // exact thread state at that time. It could be in MONITOR_WAIT or 450 // in SLEEPING or some other state. 451 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 452 java_lang_Thread::RUNNABLE); 453 } 454 os::start_thread(thread); 455 } 456 } 457 458 // Enqueue a VM_Operation to do the job for us - sometime later 459 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 460 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 461 VMThread::execute(vm_stop); 462 } 463 464 465 // Check if an external suspend request has completed (or has been 466 // cancelled). Returns true if the thread is externally suspended and 467 // false otherwise. 468 // 469 // The bits parameter returns information about the code path through 470 // the routine. Useful for debugging: 471 // 472 // set in is_ext_suspend_completed(): 473 // 0x00000001 - routine was entered 474 // 0x00000010 - routine return false at end 475 // 0x00000100 - thread exited (return false) 476 // 0x00000200 - suspend request cancelled (return false) 477 // 0x00000400 - thread suspended (return true) 478 // 0x00001000 - thread is in a suspend equivalent state (return true) 479 // 0x00002000 - thread is native and walkable (return true) 480 // 0x00004000 - thread is native_trans and walkable (needed retry) 481 // 482 // set in wait_for_ext_suspend_completion(): 483 // 0x00010000 - routine was entered 484 // 0x00020000 - suspend request cancelled before loop (return false) 485 // 0x00040000 - thread suspended before loop (return true) 486 // 0x00080000 - suspend request cancelled in loop (return false) 487 // 0x00100000 - thread suspended in loop (return true) 488 // 0x00200000 - suspend not completed during retry loop (return false) 489 490 // Helper class for tracing suspend wait debug bits. 491 // 492 // 0x00000100 indicates that the target thread exited before it could 493 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 494 // 0x00080000 each indicate a cancelled suspend request so they don't 495 // count as wait failures either. 496 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 497 498 class TraceSuspendDebugBits : public StackObj { 499 private: 500 JavaThread * jt; 501 bool is_wait; 502 bool called_by_wait; // meaningful when !is_wait 503 uint32_t * bits; 504 505 public: 506 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 507 uint32_t *_bits) { 508 jt = _jt; 509 is_wait = _is_wait; 510 called_by_wait = _called_by_wait; 511 bits = _bits; 512 } 513 514 ~TraceSuspendDebugBits() { 515 if (!is_wait) { 516 #if 1 517 // By default, don't trace bits for is_ext_suspend_completed() calls. 518 // That trace is very chatty. 519 return; 520 #else 521 if (!called_by_wait) { 522 // If tracing for is_ext_suspend_completed() is enabled, then only 523 // trace calls to it from wait_for_ext_suspend_completion() 524 return; 525 } 526 #endif 527 } 528 529 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 530 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 531 MutexLocker ml(Threads_lock); // needed for get_thread_name() 532 ResourceMark rm; 533 534 tty->print_cr( 535 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 536 jt->get_thread_name(), *bits); 537 538 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 539 } 540 } 541 } 542 }; 543 #undef DEBUG_FALSE_BITS 544 545 546 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 547 uint32_t *bits) { 548 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 549 550 bool did_trans_retry = false; // only do thread_in_native_trans retry once 551 bool do_trans_retry; // flag to force the retry 552 553 *bits |= 0x00000001; 554 555 do { 556 do_trans_retry = false; 557 558 if (is_exiting()) { 559 // Thread is in the process of exiting. This is always checked 560 // first to reduce the risk of dereferencing a freed JavaThread. 561 *bits |= 0x00000100; 562 return false; 563 } 564 565 if (!is_external_suspend()) { 566 // Suspend request is cancelled. This is always checked before 567 // is_ext_suspended() to reduce the risk of a rogue resume 568 // confusing the thread that made the suspend request. 569 *bits |= 0x00000200; 570 return false; 571 } 572 573 if (is_ext_suspended()) { 574 // thread is suspended 575 *bits |= 0x00000400; 576 return true; 577 } 578 579 // Now that we no longer do hard suspends of threads running 580 // native code, the target thread can be changing thread state 581 // while we are in this routine: 582 // 583 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 584 // 585 // We save a copy of the thread state as observed at this moment 586 // and make our decision about suspend completeness based on the 587 // copy. This closes the race where the thread state is seen as 588 // _thread_in_native_trans in the if-thread_blocked check, but is 589 // seen as _thread_blocked in if-thread_in_native_trans check. 590 JavaThreadState save_state = thread_state(); 591 592 if (save_state == _thread_blocked && is_suspend_equivalent()) { 593 // If the thread's state is _thread_blocked and this blocking 594 // condition is known to be equivalent to a suspend, then we can 595 // consider the thread to be externally suspended. This means that 596 // the code that sets _thread_blocked has been modified to do 597 // self-suspension if the blocking condition releases. We also 598 // used to check for CONDVAR_WAIT here, but that is now covered by 599 // the _thread_blocked with self-suspension check. 600 // 601 // Return true since we wouldn't be here unless there was still an 602 // external suspend request. 603 *bits |= 0x00001000; 604 return true; 605 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 606 // Threads running native code will self-suspend on native==>VM/Java 607 // transitions. If its stack is walkable (should always be the case 608 // unless this function is called before the actual java_suspend() 609 // call), then the wait is done. 610 *bits |= 0x00002000; 611 return true; 612 } else if (!called_by_wait && !did_trans_retry && 613 save_state == _thread_in_native_trans && 614 frame_anchor()->walkable()) { 615 // The thread is transitioning from thread_in_native to another 616 // thread state. check_safepoint_and_suspend_for_native_trans() 617 // will force the thread to self-suspend. If it hasn't gotten 618 // there yet we may have caught the thread in-between the native 619 // code check above and the self-suspend. Lucky us. If we were 620 // called by wait_for_ext_suspend_completion(), then it 621 // will be doing the retries so we don't have to. 622 // 623 // Since we use the saved thread state in the if-statement above, 624 // there is a chance that the thread has already transitioned to 625 // _thread_blocked by the time we get here. In that case, we will 626 // make a single unnecessary pass through the logic below. This 627 // doesn't hurt anything since we still do the trans retry. 628 629 *bits |= 0x00004000; 630 631 // Once the thread leaves thread_in_native_trans for another 632 // thread state, we break out of this retry loop. We shouldn't 633 // need this flag to prevent us from getting back here, but 634 // sometimes paranoia is good. 635 did_trans_retry = true; 636 637 // We wait for the thread to transition to a more usable state. 638 for (int i = 1; i <= SuspendRetryCount; i++) { 639 // We used to do an "os::yield_all(i)" call here with the intention 640 // that yielding would increase on each retry. However, the parameter 641 // is ignored on Linux which means the yield didn't scale up. Waiting 642 // on the SR_lock below provides a much more predictable scale up for 643 // the delay. It also provides a simple/direct point to check for any 644 // safepoint requests from the VMThread 645 646 // temporarily drops SR_lock while doing wait with safepoint check 647 // (if we're a JavaThread - the WatcherThread can also call this) 648 // and increase delay with each retry 649 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 650 651 // check the actual thread state instead of what we saved above 652 if (thread_state() != _thread_in_native_trans) { 653 // the thread has transitioned to another thread state so 654 // try all the checks (except this one) one more time. 655 do_trans_retry = true; 656 break; 657 } 658 } // end retry loop 659 660 661 } 662 } while (do_trans_retry); 663 664 *bits |= 0x00000010; 665 return false; 666 } 667 668 // Wait for an external suspend request to complete (or be cancelled). 669 // Returns true if the thread is externally suspended and false otherwise. 670 // 671 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 672 uint32_t *bits) { 673 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 674 false /* !called_by_wait */, bits); 675 676 // local flag copies to minimize SR_lock hold time 677 bool is_suspended; 678 bool pending; 679 uint32_t reset_bits; 680 681 // set a marker so is_ext_suspend_completed() knows we are the caller 682 *bits |= 0x00010000; 683 684 // We use reset_bits to reinitialize the bits value at the top of 685 // each retry loop. This allows the caller to make use of any 686 // unused bits for their own marking purposes. 687 reset_bits = *bits; 688 689 { 690 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 691 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 692 delay, bits); 693 pending = is_external_suspend(); 694 } 695 // must release SR_lock to allow suspension to complete 696 697 if (!pending) { 698 // A cancelled suspend request is the only false return from 699 // is_ext_suspend_completed() that keeps us from entering the 700 // retry loop. 701 *bits |= 0x00020000; 702 return false; 703 } 704 705 if (is_suspended) { 706 *bits |= 0x00040000; 707 return true; 708 } 709 710 for (int i = 1; i <= retries; i++) { 711 *bits = reset_bits; // reinit to only track last retry 712 713 // We used to do an "os::yield_all(i)" call here with the intention 714 // that yielding would increase on each retry. However, the parameter 715 // is ignored on Linux which means the yield didn't scale up. Waiting 716 // on the SR_lock below provides a much more predictable scale up for 717 // the delay. It also provides a simple/direct point to check for any 718 // safepoint requests from the VMThread 719 720 { 721 MutexLocker ml(SR_lock()); 722 // wait with safepoint check (if we're a JavaThread - the WatcherThread 723 // can also call this) and increase delay with each retry 724 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 725 726 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 727 delay, bits); 728 729 // It is possible for the external suspend request to be cancelled 730 // (by a resume) before the actual suspend operation is completed. 731 // Refresh our local copy to see if we still need to wait. 732 pending = is_external_suspend(); 733 } 734 735 if (!pending) { 736 // A cancelled suspend request is the only false return from 737 // is_ext_suspend_completed() that keeps us from staying in the 738 // retry loop. 739 *bits |= 0x00080000; 740 return false; 741 } 742 743 if (is_suspended) { 744 *bits |= 0x00100000; 745 return true; 746 } 747 } // end retry loop 748 749 // thread did not suspend after all our retries 750 *bits |= 0x00200000; 751 return false; 752 } 753 754 // Called from API entry points which perform stack walking. If the 755 // associated JavaThread is the current thread, then wait_for_suspend 756 // is not used. Otherwise, it determines if we should wait for the 757 // "other" thread to complete external suspension. (NOTE: in future 758 // releases the suspension mechanism should be reimplemented so this 759 // is not necessary.) 760 // 761 bool 762 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 763 if (this != JavaThread::current()) { 764 // "other" threads require special handling. 765 if (wait_for_suspend) { 766 // We are allowed to wait for the external suspend to complete 767 // so give the other thread a chance to get suspended. 768 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 769 SuspendRetryDelay, bits)) { 770 // Didn't make it so let the caller know. 771 return false; 772 } 773 } 774 // We aren't allowed to wait for the external suspend to complete 775 // so if the other thread isn't externally suspended we need to 776 // let the caller know. 777 else if (!is_ext_suspend_completed_with_lock(bits)) { 778 return false; 779 } 780 } 781 782 return true; 783 } 784 785 #ifndef PRODUCT 786 void JavaThread::record_jump(address target, address instr, const char* file, 787 int line) { 788 789 // This should not need to be atomic as the only way for simultaneous 790 // updates is via interrupts. Even then this should be rare or non-existent 791 // and we don't care that much anyway. 792 793 int index = _jmp_ring_index; 794 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 795 _jmp_ring[index]._target = (intptr_t) target; 796 _jmp_ring[index]._instruction = (intptr_t) instr; 797 _jmp_ring[index]._file = file; 798 _jmp_ring[index]._line = line; 799 } 800 #endif // PRODUCT 801 802 void Thread::interrupt(Thread* thread) { 803 debug_only(check_for_dangling_thread_pointer(thread);) 804 os::interrupt(thread); 805 } 806 807 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 808 debug_only(check_for_dangling_thread_pointer(thread);) 809 // Note: If clear_interrupted==false, this simply fetches and 810 // returns the value of the field osthread()->interrupted(). 811 return os::is_interrupted(thread, clear_interrupted); 812 } 813 814 815 // GC Support 816 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 817 int thread_parity = _oops_do_parity; 818 if (thread_parity != strong_roots_parity) { 819 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 820 if (res == thread_parity) { 821 return true; 822 } else { 823 guarantee(res == strong_roots_parity, "Or else what?"); 824 return false; 825 } 826 } 827 return false; 828 } 829 830 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 831 active_handles()->oops_do(f); 832 // Do oop for ThreadShadow 833 f->do_oop((oop*)&_pending_exception); 834 handle_area()->oops_do(f); 835 836 if (MonitorInUseLists) { 837 // When using thread local monitor lists, we scan them here, 838 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 839 ObjectSynchronizer::thread_local_used_oops_do(this, f); 840 } 841 } 842 843 void Thread::metadata_handles_do(void f(Metadata*)) { 844 // Only walk the Handles in Thread. 845 if (metadata_handles() != NULL) { 846 for (int i = 0; i< metadata_handles()->length(); i++) { 847 f(metadata_handles()->at(i)); 848 } 849 } 850 } 851 852 void Thread::print_on(outputStream* st) const { 853 // get_priority assumes osthread initialized 854 if (osthread() != NULL) { 855 int os_prio; 856 if (os::get_native_priority(this, &os_prio) == OS_OK) { 857 st->print("os_prio=%d ", os_prio); 858 } 859 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 860 ext().print_on(st); 861 osthread()->print_on(st); 862 } 863 if (_threads_hazard_ptr != NULL) { 864 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 865 } 866 if (_nested_threads_hazard_ptr != NULL) { 867 print_nested_threads_hazard_ptrs_on(st); 868 } 869 st->print(" "); 870 debug_only(if (WizardMode) print_owned_locks_on(st);) 871 } 872 873 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const { 874 assert(_nested_threads_hazard_ptr != NULL, "must be set to print"); 875 876 if (EnableThreadSMRStatistics) { 877 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt); 878 } 879 st->print(", _nested_threads_hazard_ptrs="); 880 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL; 881 node = node->next()) { 882 if (node != _nested_threads_hazard_ptr) { 883 // First node does not need a comma-space separator. 884 st->print(", "); 885 } 886 st->print(INTPTR_FORMAT, p2i(node->t_list())); 887 } 888 } 889 890 // Thread::print_on_error() is called by fatal error handler. Don't use 891 // any lock or allocate memory. 892 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 893 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 894 895 if (is_VM_thread()) { st->print("VMThread"); } 896 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 897 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 898 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 899 else { st->print("Thread"); } 900 901 if (is_Named_thread()) { 902 st->print(" \"%s\"", name()); 903 } 904 905 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 906 p2i(stack_end()), p2i(stack_base())); 907 908 if (osthread()) { 909 st->print(" [id=%d]", osthread()->thread_id()); 910 } 911 912 if (_threads_hazard_ptr != NULL) { 913 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 914 } 915 if (_nested_threads_hazard_ptr != NULL) { 916 print_nested_threads_hazard_ptrs_on(st); 917 } 918 } 919 920 void Thread::print_value_on(outputStream* st) const { 921 if (is_Named_thread()) { 922 st->print(" \"%s\" ", name()); 923 } 924 st->print(INTPTR_FORMAT, p2i(this)); // print address 925 } 926 927 #ifdef ASSERT 928 void Thread::print_owned_locks_on(outputStream* st) const { 929 Monitor *cur = _owned_locks; 930 if (cur == NULL) { 931 st->print(" (no locks) "); 932 } else { 933 st->print_cr(" Locks owned:"); 934 while (cur) { 935 cur->print_on(st); 936 cur = cur->next(); 937 } 938 } 939 } 940 941 static int ref_use_count = 0; 942 943 bool Thread::owns_locks_but_compiled_lock() const { 944 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 945 if (cur != Compile_lock) return true; 946 } 947 return false; 948 } 949 950 951 #endif 952 953 #ifndef PRODUCT 954 955 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 956 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 957 // no threads which allow_vm_block's are held 958 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 959 // Check if current thread is allowed to block at a safepoint 960 if (!(_allow_safepoint_count == 0)) { 961 fatal("Possible safepoint reached by thread that does not allow it"); 962 } 963 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 964 fatal("LEAF method calling lock?"); 965 } 966 967 #ifdef ASSERT 968 if (potential_vm_operation && is_Java_thread() 969 && !Universe::is_bootstrapping()) { 970 // Make sure we do not hold any locks that the VM thread also uses. 971 // This could potentially lead to deadlocks 972 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 973 // Threads_lock is special, since the safepoint synchronization will not start before this is 974 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 975 // since it is used to transfer control between JavaThreads and the VMThread 976 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 977 if ((cur->allow_vm_block() && 978 cur != Threads_lock && 979 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 980 cur != VMOperationRequest_lock && 981 cur != VMOperationQueue_lock) || 982 cur->rank() == Mutex::special) { 983 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 984 } 985 } 986 } 987 988 if (GCALotAtAllSafepoints) { 989 // We could enter a safepoint here and thus have a gc 990 InterfaceSupport::check_gc_alot(); 991 } 992 #endif 993 } 994 #endif 995 996 bool Thread::is_in_stack(address adr) const { 997 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 998 address end = os::current_stack_pointer(); 999 // Allow non Java threads to call this without stack_base 1000 if (_stack_base == NULL) return true; 1001 if (stack_base() >= adr && adr >= end) return true; 1002 1003 return false; 1004 } 1005 1006 bool Thread::is_in_usable_stack(address adr) const { 1007 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1008 size_t usable_stack_size = _stack_size - stack_guard_size; 1009 1010 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1011 } 1012 1013 1014 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1015 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1016 // used for compilation in the future. If that change is made, the need for these methods 1017 // should be revisited, and they should be removed if possible. 1018 1019 bool Thread::is_lock_owned(address adr) const { 1020 return on_local_stack(adr); 1021 } 1022 1023 bool Thread::set_as_starting_thread() { 1024 // NOTE: this must be called inside the main thread. 1025 return os::create_main_thread((JavaThread*)this); 1026 } 1027 1028 static void initialize_class(Symbol* class_name, TRAPS) { 1029 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1030 InstanceKlass::cast(klass)->initialize(CHECK); 1031 } 1032 1033 1034 // Creates the initial ThreadGroup 1035 static Handle create_initial_thread_group(TRAPS) { 1036 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 1037 InstanceKlass* ik = InstanceKlass::cast(k); 1038 1039 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 1040 { 1041 JavaValue result(T_VOID); 1042 JavaCalls::call_special(&result, 1043 system_instance, 1044 ik, 1045 vmSymbols::object_initializer_name(), 1046 vmSymbols::void_method_signature(), 1047 CHECK_NH); 1048 } 1049 Universe::set_system_thread_group(system_instance()); 1050 1051 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 1052 { 1053 JavaValue result(T_VOID); 1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1055 JavaCalls::call_special(&result, 1056 main_instance, 1057 ik, 1058 vmSymbols::object_initializer_name(), 1059 vmSymbols::threadgroup_string_void_signature(), 1060 system_instance, 1061 string, 1062 CHECK_NH); 1063 } 1064 return main_instance; 1065 } 1066 1067 // Creates the initial Thread 1068 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1069 TRAPS) { 1070 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1071 InstanceKlass* ik = InstanceKlass::cast(k); 1072 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1073 1074 java_lang_Thread::set_thread(thread_oop(), thread); 1075 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1076 thread->set_threadObj(thread_oop()); 1077 1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1079 1080 JavaValue result(T_VOID); 1081 JavaCalls::call_special(&result, thread_oop, 1082 ik, 1083 vmSymbols::object_initializer_name(), 1084 vmSymbols::threadgroup_string_void_signature(), 1085 thread_group, 1086 string, 1087 CHECK_NULL); 1088 return thread_oop(); 1089 } 1090 1091 char java_runtime_name[128] = ""; 1092 char java_runtime_version[128] = ""; 1093 1094 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1095 static const char* get_java_runtime_name(TRAPS) { 1096 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1097 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1098 fieldDescriptor fd; 1099 bool found = k != NULL && 1100 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1101 vmSymbols::string_signature(), &fd); 1102 if (found) { 1103 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1104 if (name_oop == NULL) { 1105 return NULL; 1106 } 1107 const char* name = java_lang_String::as_utf8_string(name_oop, 1108 java_runtime_name, 1109 sizeof(java_runtime_name)); 1110 return name; 1111 } else { 1112 return NULL; 1113 } 1114 } 1115 1116 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1117 static const char* get_java_runtime_version(TRAPS) { 1118 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1119 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1120 fieldDescriptor fd; 1121 bool found = k != NULL && 1122 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1123 vmSymbols::string_signature(), &fd); 1124 if (found) { 1125 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1126 if (name_oop == NULL) { 1127 return NULL; 1128 } 1129 const char* name = java_lang_String::as_utf8_string(name_oop, 1130 java_runtime_version, 1131 sizeof(java_runtime_version)); 1132 return name; 1133 } else { 1134 return NULL; 1135 } 1136 } 1137 1138 // General purpose hook into Java code, run once when the VM is initialized. 1139 // The Java library method itself may be changed independently from the VM. 1140 static void call_postVMInitHook(TRAPS) { 1141 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1142 if (klass != NULL) { 1143 JavaValue result(T_VOID); 1144 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1145 vmSymbols::void_method_signature(), 1146 CHECK); 1147 } 1148 } 1149 1150 static void reset_vm_info_property(TRAPS) { 1151 // the vm info string 1152 ResourceMark rm(THREAD); 1153 const char *vm_info = VM_Version::vm_info_string(); 1154 1155 // java.lang.System class 1156 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1157 1158 // setProperty arguments 1159 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1160 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1161 1162 // return value 1163 JavaValue r(T_OBJECT); 1164 1165 // public static String setProperty(String key, String value); 1166 JavaCalls::call_static(&r, 1167 klass, 1168 vmSymbols::setProperty_name(), 1169 vmSymbols::string_string_string_signature(), 1170 key_str, 1171 value_str, 1172 CHECK); 1173 } 1174 1175 1176 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1177 bool daemon, TRAPS) { 1178 assert(thread_group.not_null(), "thread group should be specified"); 1179 assert(threadObj() == NULL, "should only create Java thread object once"); 1180 1181 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1182 InstanceKlass* ik = InstanceKlass::cast(k); 1183 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1184 1185 java_lang_Thread::set_thread(thread_oop(), this); 1186 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1187 set_threadObj(thread_oop()); 1188 1189 JavaValue result(T_VOID); 1190 if (thread_name != NULL) { 1191 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1192 // Thread gets assigned specified name and null target 1193 JavaCalls::call_special(&result, 1194 thread_oop, 1195 ik, 1196 vmSymbols::object_initializer_name(), 1197 vmSymbols::threadgroup_string_void_signature(), 1198 thread_group, // Argument 1 1199 name, // Argument 2 1200 THREAD); 1201 } else { 1202 // Thread gets assigned name "Thread-nnn" and null target 1203 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1204 JavaCalls::call_special(&result, 1205 thread_oop, 1206 ik, 1207 vmSymbols::object_initializer_name(), 1208 vmSymbols::threadgroup_runnable_void_signature(), 1209 thread_group, // Argument 1 1210 Handle(), // Argument 2 1211 THREAD); 1212 } 1213 1214 1215 if (daemon) { 1216 java_lang_Thread::set_daemon(thread_oop()); 1217 } 1218 1219 if (HAS_PENDING_EXCEPTION) { 1220 return; 1221 } 1222 1223 Klass* group = SystemDictionary::ThreadGroup_klass(); 1224 Handle threadObj(THREAD, this->threadObj()); 1225 1226 JavaCalls::call_special(&result, 1227 thread_group, 1228 group, 1229 vmSymbols::add_method_name(), 1230 vmSymbols::thread_void_signature(), 1231 threadObj, // Arg 1 1232 THREAD); 1233 } 1234 1235 // NamedThread -- non-JavaThread subclasses with multiple 1236 // uniquely named instances should derive from this. 1237 NamedThread::NamedThread() : Thread() { 1238 _name = NULL; 1239 _processed_thread = NULL; 1240 _gc_id = GCId::undefined(); 1241 } 1242 1243 NamedThread::~NamedThread() { 1244 if (_name != NULL) { 1245 FREE_C_HEAP_ARRAY(char, _name); 1246 _name = NULL; 1247 } 1248 } 1249 1250 void NamedThread::set_name(const char* format, ...) { 1251 guarantee(_name == NULL, "Only get to set name once."); 1252 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1253 guarantee(_name != NULL, "alloc failure"); 1254 va_list ap; 1255 va_start(ap, format); 1256 jio_vsnprintf(_name, max_name_len, format, ap); 1257 va_end(ap); 1258 } 1259 1260 void NamedThread::initialize_named_thread() { 1261 set_native_thread_name(name()); 1262 } 1263 1264 void NamedThread::print_on(outputStream* st) const { 1265 st->print("\"%s\" ", name()); 1266 Thread::print_on(st); 1267 st->cr(); 1268 } 1269 1270 1271 // ======= WatcherThread ======== 1272 1273 // The watcher thread exists to simulate timer interrupts. It should 1274 // be replaced by an abstraction over whatever native support for 1275 // timer interrupts exists on the platform. 1276 1277 WatcherThread* WatcherThread::_watcher_thread = NULL; 1278 bool WatcherThread::_startable = false; 1279 volatile bool WatcherThread::_should_terminate = false; 1280 1281 WatcherThread::WatcherThread() : Thread() { 1282 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1283 if (os::create_thread(this, os::watcher_thread)) { 1284 _watcher_thread = this; 1285 1286 // Set the watcher thread to the highest OS priority which should not be 1287 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1288 // is created. The only normal thread using this priority is the reference 1289 // handler thread, which runs for very short intervals only. 1290 // If the VMThread's priority is not lower than the WatcherThread profiling 1291 // will be inaccurate. 1292 os::set_priority(this, MaxPriority); 1293 if (!DisableStartThread) { 1294 os::start_thread(this); 1295 } 1296 } 1297 } 1298 1299 int WatcherThread::sleep() const { 1300 // The WatcherThread does not participate in the safepoint protocol 1301 // for the PeriodicTask_lock because it is not a JavaThread. 1302 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1303 1304 if (_should_terminate) { 1305 // check for termination before we do any housekeeping or wait 1306 return 0; // we did not sleep. 1307 } 1308 1309 // remaining will be zero if there are no tasks, 1310 // causing the WatcherThread to sleep until a task is 1311 // enrolled 1312 int remaining = PeriodicTask::time_to_wait(); 1313 int time_slept = 0; 1314 1315 // we expect this to timeout - we only ever get unparked when 1316 // we should terminate or when a new task has been enrolled 1317 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1318 1319 jlong time_before_loop = os::javaTimeNanos(); 1320 1321 while (true) { 1322 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1323 remaining); 1324 jlong now = os::javaTimeNanos(); 1325 1326 if (remaining == 0) { 1327 // if we didn't have any tasks we could have waited for a long time 1328 // consider the time_slept zero and reset time_before_loop 1329 time_slept = 0; 1330 time_before_loop = now; 1331 } else { 1332 // need to recalculate since we might have new tasks in _tasks 1333 time_slept = (int) ((now - time_before_loop) / 1000000); 1334 } 1335 1336 // Change to task list or spurious wakeup of some kind 1337 if (timedout || _should_terminate) { 1338 break; 1339 } 1340 1341 remaining = PeriodicTask::time_to_wait(); 1342 if (remaining == 0) { 1343 // Last task was just disenrolled so loop around and wait until 1344 // another task gets enrolled 1345 continue; 1346 } 1347 1348 remaining -= time_slept; 1349 if (remaining <= 0) { 1350 break; 1351 } 1352 } 1353 1354 return time_slept; 1355 } 1356 1357 void WatcherThread::run() { 1358 assert(this == watcher_thread(), "just checking"); 1359 1360 this->record_stack_base_and_size(); 1361 this->set_native_thread_name(this->name()); 1362 this->set_active_handles(JNIHandleBlock::allocate_block()); 1363 while (true) { 1364 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1365 assert(watcher_thread() == this, "thread consistency check"); 1366 1367 // Calculate how long it'll be until the next PeriodicTask work 1368 // should be done, and sleep that amount of time. 1369 int time_waited = sleep(); 1370 1371 if (VMError::is_error_reported()) { 1372 // A fatal error has happened, the error handler(VMError::report_and_die) 1373 // should abort JVM after creating an error log file. However in some 1374 // rare cases, the error handler itself might deadlock. Here periodically 1375 // check for error reporting timeouts, and if it happens, just proceed to 1376 // abort the VM. 1377 1378 // This code is in WatcherThread because WatcherThread wakes up 1379 // periodically so the fatal error handler doesn't need to do anything; 1380 // also because the WatcherThread is less likely to crash than other 1381 // threads. 1382 1383 for (;;) { 1384 // Note: we use naked sleep in this loop because we want to avoid using 1385 // any kind of VM infrastructure which may be broken at this point. 1386 if (VMError::check_timeout()) { 1387 // We hit error reporting timeout. Error reporting was interrupted and 1388 // will be wrapping things up now (closing files etc). Give it some more 1389 // time, then quit the VM. 1390 os::naked_short_sleep(200); 1391 // Print a message to stderr. 1392 fdStream err(defaultStream::output_fd()); 1393 err.print_raw_cr("# [ timer expired, abort... ]"); 1394 // skip atexit/vm_exit/vm_abort hooks 1395 os::die(); 1396 } 1397 1398 // Wait a second, then recheck for timeout. 1399 os::naked_short_sleep(999); 1400 } 1401 } 1402 1403 if (_should_terminate) { 1404 // check for termination before posting the next tick 1405 break; 1406 } 1407 1408 PeriodicTask::real_time_tick(time_waited); 1409 } 1410 1411 // Signal that it is terminated 1412 { 1413 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1414 _watcher_thread = NULL; 1415 Terminator_lock->notify(); 1416 } 1417 } 1418 1419 void WatcherThread::start() { 1420 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1421 1422 if (watcher_thread() == NULL && _startable) { 1423 _should_terminate = false; 1424 // Create the single instance of WatcherThread 1425 new WatcherThread(); 1426 } 1427 } 1428 1429 void WatcherThread::make_startable() { 1430 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1431 _startable = true; 1432 } 1433 1434 void WatcherThread::stop() { 1435 { 1436 // Follow normal safepoint aware lock enter protocol since the 1437 // WatcherThread is stopped by another JavaThread. 1438 MutexLocker ml(PeriodicTask_lock); 1439 _should_terminate = true; 1440 1441 WatcherThread* watcher = watcher_thread(); 1442 if (watcher != NULL) { 1443 // unpark the WatcherThread so it can see that it should terminate 1444 watcher->unpark(); 1445 } 1446 } 1447 1448 MutexLocker mu(Terminator_lock); 1449 1450 while (watcher_thread() != NULL) { 1451 // This wait should make safepoint checks, wait without a timeout, 1452 // and wait as a suspend-equivalent condition. 1453 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1454 Mutex::_as_suspend_equivalent_flag); 1455 } 1456 } 1457 1458 void WatcherThread::unpark() { 1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1460 PeriodicTask_lock->notify(); 1461 } 1462 1463 void WatcherThread::print_on(outputStream* st) const { 1464 st->print("\"%s\" ", name()); 1465 Thread::print_on(st); 1466 st->cr(); 1467 } 1468 1469 // ======= JavaThread ======== 1470 1471 #if INCLUDE_JVMCI 1472 1473 jlong* JavaThread::_jvmci_old_thread_counters; 1474 1475 bool jvmci_counters_include(JavaThread* thread) { 1476 oop threadObj = thread->threadObj(); 1477 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1478 } 1479 1480 void JavaThread::collect_counters(typeArrayOop array) { 1481 if (JVMCICounterSize > 0) { 1482 // dcubed - Looks like the Threads_lock is for stable access 1483 // to _jvmci_old_thread_counters and _jvmci_counters. 1484 MutexLocker tl(Threads_lock); 1485 JavaThreadIteratorWithHandle jtiwh; 1486 for (int i = 0; i < array->length(); i++) { 1487 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1488 } 1489 for (; JavaThread *tp = jtiwh.next(); ) { 1490 if (jvmci_counters_include(tp)) { 1491 for (int i = 0; i < array->length(); i++) { 1492 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1493 } 1494 } 1495 } 1496 } 1497 } 1498 1499 #endif // INCLUDE_JVMCI 1500 1501 // A JavaThread is a normal Java thread 1502 1503 void JavaThread::initialize() { 1504 // Initialize fields 1505 1506 set_saved_exception_pc(NULL); 1507 set_threadObj(NULL); 1508 _anchor.clear(); 1509 set_entry_point(NULL); 1510 set_jni_functions(jni_functions()); 1511 set_callee_target(NULL); 1512 set_vm_result(NULL); 1513 set_vm_result_2(NULL); 1514 set_vframe_array_head(NULL); 1515 set_vframe_array_last(NULL); 1516 set_deferred_locals(NULL); 1517 set_deopt_mark(NULL); 1518 set_deopt_compiled_method(NULL); 1519 clear_must_deopt_id(); 1520 set_monitor_chunks(NULL); 1521 set_next(NULL); 1522 _on_thread_list = false; 1523 set_thread_state(_thread_new); 1524 _terminated = _not_terminated; 1525 _privileged_stack_top = NULL; 1526 _array_for_gc = NULL; 1527 _suspend_equivalent = false; 1528 _in_deopt_handler = 0; 1529 _doing_unsafe_access = false; 1530 _stack_guard_state = stack_guard_unused; 1531 #if INCLUDE_JVMCI 1532 _pending_monitorenter = false; 1533 _pending_deoptimization = -1; 1534 _pending_failed_speculation = NULL; 1535 _pending_transfer_to_interpreter = false; 1536 _adjusting_comp_level = false; 1537 _jvmci._alternate_call_target = NULL; 1538 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1539 if (JVMCICounterSize > 0) { 1540 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1541 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1542 } else { 1543 _jvmci_counters = NULL; 1544 } 1545 #endif // INCLUDE_JVMCI 1546 _reserved_stack_activation = NULL; // stack base not known yet 1547 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1548 _exception_pc = 0; 1549 _exception_handler_pc = 0; 1550 _is_method_handle_return = 0; 1551 _jvmti_thread_state= NULL; 1552 _should_post_on_exceptions_flag = JNI_FALSE; 1553 _jvmti_get_loaded_classes_closure = NULL; 1554 _interp_only_mode = 0; 1555 _special_runtime_exit_condition = _no_async_condition; 1556 _pending_async_exception = NULL; 1557 _thread_stat = NULL; 1558 _thread_stat = new ThreadStatistics(); 1559 _blocked_on_compilation = false; 1560 _jni_active_critical = 0; 1561 _pending_jni_exception_check_fn = NULL; 1562 _do_not_unlock_if_synchronized = false; 1563 _cached_monitor_info = NULL; 1564 _parker = Parker::Allocate(this); 1565 1566 #ifndef PRODUCT 1567 _jmp_ring_index = 0; 1568 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1569 record_jump(NULL, NULL, NULL, 0); 1570 } 1571 #endif // PRODUCT 1572 1573 // Setup safepoint state info for this thread 1574 ThreadSafepointState::create(this); 1575 1576 debug_only(_java_call_counter = 0); 1577 1578 // JVMTI PopFrame support 1579 _popframe_condition = popframe_inactive; 1580 _popframe_preserved_args = NULL; 1581 _popframe_preserved_args_size = 0; 1582 _frames_to_pop_failed_realloc = 0; 1583 1584 if (SafepointMechanism::uses_thread_local_poll()) { 1585 SafepointMechanism::initialize_header(this); 1586 } 1587 1588 pd_initialize(); 1589 } 1590 1591 #if INCLUDE_ALL_GCS 1592 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1593 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1594 #endif // INCLUDE_ALL_GCS 1595 1596 JavaThread::JavaThread(bool is_attaching_via_jni) : 1597 Thread() 1598 #if INCLUDE_ALL_GCS 1599 , _satb_mark_queue(&_satb_mark_queue_set), 1600 _dirty_card_queue(&_dirty_card_queue_set) 1601 #endif // INCLUDE_ALL_GCS 1602 { 1603 initialize(); 1604 if (is_attaching_via_jni) { 1605 _jni_attach_state = _attaching_via_jni; 1606 } else { 1607 _jni_attach_state = _not_attaching_via_jni; 1608 } 1609 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1610 } 1611 1612 bool JavaThread::reguard_stack(address cur_sp) { 1613 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1614 && _stack_guard_state != stack_guard_reserved_disabled) { 1615 return true; // Stack already guarded or guard pages not needed. 1616 } 1617 1618 if (register_stack_overflow()) { 1619 // For those architectures which have separate register and 1620 // memory stacks, we must check the register stack to see if 1621 // it has overflowed. 1622 return false; 1623 } 1624 1625 // Java code never executes within the yellow zone: the latter is only 1626 // there to provoke an exception during stack banging. If java code 1627 // is executing there, either StackShadowPages should be larger, or 1628 // some exception code in c1, c2 or the interpreter isn't unwinding 1629 // when it should. 1630 guarantee(cur_sp > stack_reserved_zone_base(), 1631 "not enough space to reguard - increase StackShadowPages"); 1632 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1633 enable_stack_yellow_reserved_zone(); 1634 if (reserved_stack_activation() != stack_base()) { 1635 set_reserved_stack_activation(stack_base()); 1636 } 1637 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1638 set_reserved_stack_activation(stack_base()); 1639 enable_stack_reserved_zone(); 1640 } 1641 return true; 1642 } 1643 1644 bool JavaThread::reguard_stack(void) { 1645 return reguard_stack(os::current_stack_pointer()); 1646 } 1647 1648 1649 void JavaThread::block_if_vm_exited() { 1650 if (_terminated == _vm_exited) { 1651 // _vm_exited is set at safepoint, and Threads_lock is never released 1652 // we will block here forever 1653 Threads_lock->lock_without_safepoint_check(); 1654 ShouldNotReachHere(); 1655 } 1656 } 1657 1658 1659 // Remove this ifdef when C1 is ported to the compiler interface. 1660 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1661 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1662 1663 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1664 Thread() 1665 #if INCLUDE_ALL_GCS 1666 , _satb_mark_queue(&_satb_mark_queue_set), 1667 _dirty_card_queue(&_dirty_card_queue_set) 1668 #endif // INCLUDE_ALL_GCS 1669 { 1670 initialize(); 1671 _jni_attach_state = _not_attaching_via_jni; 1672 set_entry_point(entry_point); 1673 // Create the native thread itself. 1674 // %note runtime_23 1675 os::ThreadType thr_type = os::java_thread; 1676 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1677 os::java_thread; 1678 os::create_thread(this, thr_type, stack_sz); 1679 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1680 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1681 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1682 // the exception consists of creating the exception object & initializing it, initialization 1683 // will leave the VM via a JavaCall and then all locks must be unlocked). 1684 // 1685 // The thread is still suspended when we reach here. Thread must be explicit started 1686 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1687 // by calling Threads:add. The reason why this is not done here, is because the thread 1688 // object must be fully initialized (take a look at JVM_Start) 1689 } 1690 1691 JavaThread::~JavaThread() { 1692 1693 // JSR166 -- return the parker to the free list 1694 Parker::Release(_parker); 1695 _parker = NULL; 1696 1697 // Free any remaining previous UnrollBlock 1698 vframeArray* old_array = vframe_array_last(); 1699 1700 if (old_array != NULL) { 1701 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1702 old_array->set_unroll_block(NULL); 1703 delete old_info; 1704 delete old_array; 1705 } 1706 1707 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1708 if (deferred != NULL) { 1709 // This can only happen if thread is destroyed before deoptimization occurs. 1710 assert(deferred->length() != 0, "empty array!"); 1711 do { 1712 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1713 deferred->remove_at(0); 1714 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1715 delete dlv; 1716 } while (deferred->length() != 0); 1717 delete deferred; 1718 } 1719 1720 // All Java related clean up happens in exit 1721 ThreadSafepointState::destroy(this); 1722 if (_thread_stat != NULL) delete _thread_stat; 1723 1724 #if INCLUDE_JVMCI 1725 if (JVMCICounterSize > 0) { 1726 if (jvmci_counters_include(this)) { 1727 for (int i = 0; i < JVMCICounterSize; i++) { 1728 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1729 } 1730 } 1731 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1732 } 1733 #endif // INCLUDE_JVMCI 1734 } 1735 1736 1737 // The first routine called by a new Java thread 1738 void JavaThread::run() { 1739 // initialize thread-local alloc buffer related fields 1740 this->initialize_tlab(); 1741 1742 // used to test validity of stack trace backs 1743 this->record_base_of_stack_pointer(); 1744 1745 // Record real stack base and size. 1746 this->record_stack_base_and_size(); 1747 1748 this->create_stack_guard_pages(); 1749 1750 this->cache_global_variables(); 1751 1752 // Thread is now sufficient initialized to be handled by the safepoint code as being 1753 // in the VM. Change thread state from _thread_new to _thread_in_vm 1754 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1755 1756 assert(JavaThread::current() == this, "sanity check"); 1757 assert(!Thread::current()->owns_locks(), "sanity check"); 1758 1759 DTRACE_THREAD_PROBE(start, this); 1760 1761 // This operation might block. We call that after all safepoint checks for a new thread has 1762 // been completed. 1763 this->set_active_handles(JNIHandleBlock::allocate_block()); 1764 1765 if (JvmtiExport::should_post_thread_life()) { 1766 JvmtiExport::post_thread_start(this); 1767 } 1768 1769 EventThreadStart event; 1770 if (event.should_commit()) { 1771 event.set_thread(THREAD_TRACE_ID(this)); 1772 event.commit(); 1773 } 1774 1775 // We call another function to do the rest so we are sure that the stack addresses used 1776 // from there will be lower than the stack base just computed 1777 thread_main_inner(); 1778 1779 // Note, thread is no longer valid at this point! 1780 } 1781 1782 1783 void JavaThread::thread_main_inner() { 1784 assert(JavaThread::current() == this, "sanity check"); 1785 assert(this->threadObj() != NULL, "just checking"); 1786 1787 // Execute thread entry point unless this thread has a pending exception 1788 // or has been stopped before starting. 1789 // Note: Due to JVM_StopThread we can have pending exceptions already! 1790 if (!this->has_pending_exception() && 1791 !java_lang_Thread::is_stillborn(this->threadObj())) { 1792 { 1793 ResourceMark rm(this); 1794 this->set_native_thread_name(this->get_thread_name()); 1795 } 1796 HandleMark hm(this); 1797 this->entry_point()(this, this); 1798 } 1799 1800 DTRACE_THREAD_PROBE(stop, this); 1801 1802 this->exit(false); 1803 this->smr_delete(); 1804 } 1805 1806 1807 static void ensure_join(JavaThread* thread) { 1808 // We do not need to grab the Threads_lock, since we are operating on ourself. 1809 Handle threadObj(thread, thread->threadObj()); 1810 assert(threadObj.not_null(), "java thread object must exist"); 1811 ObjectLocker lock(threadObj, thread); 1812 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1813 thread->clear_pending_exception(); 1814 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1815 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1816 // Clear the native thread instance - this makes isAlive return false and allows the join() 1817 // to complete once we've done the notify_all below 1818 java_lang_Thread::set_thread(threadObj(), NULL); 1819 lock.notify_all(thread); 1820 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1821 thread->clear_pending_exception(); 1822 } 1823 1824 1825 // For any new cleanup additions, please check to see if they need to be applied to 1826 // cleanup_failed_attach_current_thread as well. 1827 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1828 assert(this == JavaThread::current(), "thread consistency check"); 1829 1830 elapsedTimer _timer_exit_phase1; 1831 elapsedTimer _timer_exit_phase2; 1832 elapsedTimer _timer_exit_phase3; 1833 elapsedTimer _timer_exit_phase4; 1834 1835 if (log_is_enabled(Debug, os, thread, timer)) { 1836 _timer_exit_phase1.start(); 1837 } 1838 1839 HandleMark hm(this); 1840 Handle uncaught_exception(this, this->pending_exception()); 1841 this->clear_pending_exception(); 1842 Handle threadObj(this, this->threadObj()); 1843 assert(threadObj.not_null(), "Java thread object should be created"); 1844 1845 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1846 { 1847 EXCEPTION_MARK; 1848 1849 CLEAR_PENDING_EXCEPTION; 1850 } 1851 if (!destroy_vm) { 1852 if (uncaught_exception.not_null()) { 1853 EXCEPTION_MARK; 1854 // Call method Thread.dispatchUncaughtException(). 1855 Klass* thread_klass = SystemDictionary::Thread_klass(); 1856 JavaValue result(T_VOID); 1857 JavaCalls::call_virtual(&result, 1858 threadObj, thread_klass, 1859 vmSymbols::dispatchUncaughtException_name(), 1860 vmSymbols::throwable_void_signature(), 1861 uncaught_exception, 1862 THREAD); 1863 if (HAS_PENDING_EXCEPTION) { 1864 ResourceMark rm(this); 1865 jio_fprintf(defaultStream::error_stream(), 1866 "\nException: %s thrown from the UncaughtExceptionHandler" 1867 " in thread \"%s\"\n", 1868 pending_exception()->klass()->external_name(), 1869 get_thread_name()); 1870 CLEAR_PENDING_EXCEPTION; 1871 } 1872 } 1873 1874 // Called before the java thread exit since we want to read info 1875 // from java_lang_Thread object 1876 EventThreadEnd event; 1877 if (event.should_commit()) { 1878 event.set_thread(THREAD_TRACE_ID(this)); 1879 event.commit(); 1880 } 1881 1882 // Call after last event on thread 1883 EVENT_THREAD_EXIT(this); 1884 1885 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1886 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1887 // is deprecated anyhow. 1888 if (!is_Compiler_thread()) { 1889 int count = 3; 1890 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1891 EXCEPTION_MARK; 1892 JavaValue result(T_VOID); 1893 Klass* thread_klass = SystemDictionary::Thread_klass(); 1894 JavaCalls::call_virtual(&result, 1895 threadObj, thread_klass, 1896 vmSymbols::exit_method_name(), 1897 vmSymbols::void_method_signature(), 1898 THREAD); 1899 CLEAR_PENDING_EXCEPTION; 1900 } 1901 } 1902 // notify JVMTI 1903 if (JvmtiExport::should_post_thread_life()) { 1904 JvmtiExport::post_thread_end(this); 1905 } 1906 1907 // We have notified the agents that we are exiting, before we go on, 1908 // we must check for a pending external suspend request and honor it 1909 // in order to not surprise the thread that made the suspend request. 1910 while (true) { 1911 { 1912 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1913 if (!is_external_suspend()) { 1914 set_terminated(_thread_exiting); 1915 ThreadService::current_thread_exiting(this); 1916 break; 1917 } 1918 // Implied else: 1919 // Things get a little tricky here. We have a pending external 1920 // suspend request, but we are holding the SR_lock so we 1921 // can't just self-suspend. So we temporarily drop the lock 1922 // and then self-suspend. 1923 } 1924 1925 ThreadBlockInVM tbivm(this); 1926 java_suspend_self(); 1927 1928 // We're done with this suspend request, but we have to loop around 1929 // and check again. Eventually we will get SR_lock without a pending 1930 // external suspend request and will be able to mark ourselves as 1931 // exiting. 1932 } 1933 // no more external suspends are allowed at this point 1934 } else { 1935 // before_exit() has already posted JVMTI THREAD_END events 1936 } 1937 1938 if (log_is_enabled(Debug, os, thread, timer)) { 1939 _timer_exit_phase1.stop(); 1940 _timer_exit_phase2.start(); 1941 } 1942 // Notify waiters on thread object. This has to be done after exit() is called 1943 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1944 // group should have the destroyed bit set before waiters are notified). 1945 ensure_join(this); 1946 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1947 1948 if (log_is_enabled(Debug, os, thread, timer)) { 1949 _timer_exit_phase2.stop(); 1950 _timer_exit_phase3.start(); 1951 } 1952 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1953 // held by this thread must be released. The spec does not distinguish 1954 // between JNI-acquired and regular Java monitors. We can only see 1955 // regular Java monitors here if monitor enter-exit matching is broken. 1956 // 1957 // Optionally release any monitors for regular JavaThread exits. This 1958 // is provided as a work around for any bugs in monitor enter-exit 1959 // matching. This can be expensive so it is not enabled by default. 1960 // 1961 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1962 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1963 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1964 // Sanity check even though JNI DetachCurrentThread() would have 1965 // returned JNI_ERR if there was a Java frame. JavaThread exit 1966 // should be done executing Java code by the time we get here. 1967 assert(!this->has_last_Java_frame(), 1968 "should not have a Java frame when detaching or exiting"); 1969 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1970 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1971 } 1972 1973 // These things needs to be done while we are still a Java Thread. Make sure that thread 1974 // is in a consistent state, in case GC happens 1975 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1976 1977 if (active_handles() != NULL) { 1978 JNIHandleBlock* block = active_handles(); 1979 set_active_handles(NULL); 1980 JNIHandleBlock::release_block(block); 1981 } 1982 1983 if (free_handle_block() != NULL) { 1984 JNIHandleBlock* block = free_handle_block(); 1985 set_free_handle_block(NULL); 1986 JNIHandleBlock::release_block(block); 1987 } 1988 1989 // These have to be removed while this is still a valid thread. 1990 remove_stack_guard_pages(); 1991 1992 if (UseTLAB) { 1993 tlab().make_parsable(true); // retire TLAB 1994 } 1995 1996 if (JvmtiEnv::environments_might_exist()) { 1997 JvmtiExport::cleanup_thread(this); 1998 } 1999 2000 // We must flush any deferred card marks before removing a thread from 2001 // the list of active threads. 2002 Universe::heap()->flush_deferred_store_barrier(this); 2003 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 2004 2005 #if INCLUDE_ALL_GCS 2006 // We must flush the G1-related buffers before removing a thread 2007 // from the list of active threads. We must do this after any deferred 2008 // card marks have been flushed (above) so that any entries that are 2009 // added to the thread's dirty card queue as a result are not lost. 2010 if (UseG1GC) { 2011 flush_barrier_queues(); 2012 } 2013 #endif // INCLUDE_ALL_GCS 2014 2015 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2016 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2017 os::current_thread_id()); 2018 2019 if (log_is_enabled(Debug, os, thread, timer)) { 2020 _timer_exit_phase3.stop(); 2021 _timer_exit_phase4.start(); 2022 } 2023 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2024 Threads::remove(this); 2025 2026 if (log_is_enabled(Debug, os, thread, timer)) { 2027 _timer_exit_phase4.stop(); 2028 ResourceMark rm(this); 2029 log_debug(os, thread, timer)("name='%s'" 2030 ", exit-phase1=" JLONG_FORMAT 2031 ", exit-phase2=" JLONG_FORMAT 2032 ", exit-phase3=" JLONG_FORMAT 2033 ", exit-phase4=" JLONG_FORMAT, 2034 get_thread_name(), 2035 _timer_exit_phase1.milliseconds(), 2036 _timer_exit_phase2.milliseconds(), 2037 _timer_exit_phase3.milliseconds(), 2038 _timer_exit_phase4.milliseconds()); 2039 } 2040 } 2041 2042 #if INCLUDE_ALL_GCS 2043 // Flush G1-related queues. 2044 void JavaThread::flush_barrier_queues() { 2045 satb_mark_queue().flush(); 2046 dirty_card_queue().flush(); 2047 } 2048 2049 void JavaThread::initialize_queues() { 2050 assert(!SafepointSynchronize::is_at_safepoint(), 2051 "we should not be at a safepoint"); 2052 2053 SATBMarkQueue& satb_queue = satb_mark_queue(); 2054 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 2055 // The SATB queue should have been constructed with its active 2056 // field set to false. 2057 assert(!satb_queue.is_active(), "SATB queue should not be active"); 2058 assert(satb_queue.is_empty(), "SATB queue should be empty"); 2059 // If we are creating the thread during a marking cycle, we should 2060 // set the active field of the SATB queue to true. 2061 if (satb_queue_set.is_active()) { 2062 satb_queue.set_active(true); 2063 } 2064 2065 DirtyCardQueue& dirty_queue = dirty_card_queue(); 2066 // The dirty card queue should have been constructed with its 2067 // active field set to true. 2068 assert(dirty_queue.is_active(), "dirty card queue should be active"); 2069 } 2070 #endif // INCLUDE_ALL_GCS 2071 2072 void JavaThread::cleanup_failed_attach_current_thread() { 2073 if (active_handles() != NULL) { 2074 JNIHandleBlock* block = active_handles(); 2075 set_active_handles(NULL); 2076 JNIHandleBlock::release_block(block); 2077 } 2078 2079 if (free_handle_block() != NULL) { 2080 JNIHandleBlock* block = free_handle_block(); 2081 set_free_handle_block(NULL); 2082 JNIHandleBlock::release_block(block); 2083 } 2084 2085 // These have to be removed while this is still a valid thread. 2086 remove_stack_guard_pages(); 2087 2088 if (UseTLAB) { 2089 tlab().make_parsable(true); // retire TLAB, if any 2090 } 2091 2092 #if INCLUDE_ALL_GCS 2093 if (UseG1GC) { 2094 flush_barrier_queues(); 2095 } 2096 #endif // INCLUDE_ALL_GCS 2097 2098 Threads::remove(this); 2099 this->smr_delete(); 2100 } 2101 2102 2103 2104 2105 JavaThread* JavaThread::active() { 2106 Thread* thread = Thread::current(); 2107 if (thread->is_Java_thread()) { 2108 return (JavaThread*) thread; 2109 } else { 2110 assert(thread->is_VM_thread(), "this must be a vm thread"); 2111 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2112 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2113 assert(ret->is_Java_thread(), "must be a Java thread"); 2114 return ret; 2115 } 2116 } 2117 2118 bool JavaThread::is_lock_owned(address adr) const { 2119 if (Thread::is_lock_owned(adr)) return true; 2120 2121 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2122 if (chunk->contains(adr)) return true; 2123 } 2124 2125 return false; 2126 } 2127 2128 2129 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2130 chunk->set_next(monitor_chunks()); 2131 set_monitor_chunks(chunk); 2132 } 2133 2134 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2135 guarantee(monitor_chunks() != NULL, "must be non empty"); 2136 if (monitor_chunks() == chunk) { 2137 set_monitor_chunks(chunk->next()); 2138 } else { 2139 MonitorChunk* prev = monitor_chunks(); 2140 while (prev->next() != chunk) prev = prev->next(); 2141 prev->set_next(chunk->next()); 2142 } 2143 } 2144 2145 // JVM support. 2146 2147 // Note: this function shouldn't block if it's called in 2148 // _thread_in_native_trans state (such as from 2149 // check_special_condition_for_native_trans()). 2150 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2151 2152 if (has_last_Java_frame() && has_async_condition()) { 2153 // If we are at a polling page safepoint (not a poll return) 2154 // then we must defer async exception because live registers 2155 // will be clobbered by the exception path. Poll return is 2156 // ok because the call we a returning from already collides 2157 // with exception handling registers and so there is no issue. 2158 // (The exception handling path kills call result registers but 2159 // this is ok since the exception kills the result anyway). 2160 2161 if (is_at_poll_safepoint()) { 2162 // if the code we are returning to has deoptimized we must defer 2163 // the exception otherwise live registers get clobbered on the 2164 // exception path before deoptimization is able to retrieve them. 2165 // 2166 RegisterMap map(this, false); 2167 frame caller_fr = last_frame().sender(&map); 2168 assert(caller_fr.is_compiled_frame(), "what?"); 2169 if (caller_fr.is_deoptimized_frame()) { 2170 log_info(exceptions)("deferred async exception at compiled safepoint"); 2171 return; 2172 } 2173 } 2174 } 2175 2176 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2177 if (condition == _no_async_condition) { 2178 // Conditions have changed since has_special_runtime_exit_condition() 2179 // was called: 2180 // - if we were here only because of an external suspend request, 2181 // then that was taken care of above (or cancelled) so we are done 2182 // - if we were here because of another async request, then it has 2183 // been cleared between the has_special_runtime_exit_condition() 2184 // and now so again we are done 2185 return; 2186 } 2187 2188 // Check for pending async. exception 2189 if (_pending_async_exception != NULL) { 2190 // Only overwrite an already pending exception, if it is not a threadDeath. 2191 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2192 2193 // We cannot call Exceptions::_throw(...) here because we cannot block 2194 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2195 2196 LogTarget(Info, exceptions) lt; 2197 if (lt.is_enabled()) { 2198 ResourceMark rm; 2199 LogStream ls(lt); 2200 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2201 if (has_last_Java_frame()) { 2202 frame f = last_frame(); 2203 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2204 } 2205 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2206 } 2207 _pending_async_exception = NULL; 2208 clear_has_async_exception(); 2209 } 2210 } 2211 2212 if (check_unsafe_error && 2213 condition == _async_unsafe_access_error && !has_pending_exception()) { 2214 condition = _no_async_condition; // done 2215 switch (thread_state()) { 2216 case _thread_in_vm: { 2217 JavaThread* THREAD = this; 2218 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2219 } 2220 case _thread_in_native: { 2221 ThreadInVMfromNative tiv(this); 2222 JavaThread* THREAD = this; 2223 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2224 } 2225 case _thread_in_Java: { 2226 ThreadInVMfromJava tiv(this); 2227 JavaThread* THREAD = this; 2228 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2229 } 2230 default: 2231 ShouldNotReachHere(); 2232 } 2233 } 2234 2235 assert(condition == _no_async_condition || has_pending_exception() || 2236 (!check_unsafe_error && condition == _async_unsafe_access_error), 2237 "must have handled the async condition, if no exception"); 2238 } 2239 2240 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2241 // 2242 // Check for pending external suspend. Internal suspend requests do 2243 // not use handle_special_runtime_exit_condition(). 2244 // If JNIEnv proxies are allowed, don't self-suspend if the target 2245 // thread is not the current thread. In older versions of jdbx, jdbx 2246 // threads could call into the VM with another thread's JNIEnv so we 2247 // can be here operating on behalf of a suspended thread (4432884). 2248 bool do_self_suspend = is_external_suspend_with_lock(); 2249 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2250 // 2251 // Because thread is external suspended the safepoint code will count 2252 // thread as at a safepoint. This can be odd because we can be here 2253 // as _thread_in_Java which would normally transition to _thread_blocked 2254 // at a safepoint. We would like to mark the thread as _thread_blocked 2255 // before calling java_suspend_self like all other callers of it but 2256 // we must then observe proper safepoint protocol. (We can't leave 2257 // _thread_blocked with a safepoint in progress). However we can be 2258 // here as _thread_in_native_trans so we can't use a normal transition 2259 // constructor/destructor pair because they assert on that type of 2260 // transition. We could do something like: 2261 // 2262 // JavaThreadState state = thread_state(); 2263 // set_thread_state(_thread_in_vm); 2264 // { 2265 // ThreadBlockInVM tbivm(this); 2266 // java_suspend_self() 2267 // } 2268 // set_thread_state(_thread_in_vm_trans); 2269 // if (safepoint) block; 2270 // set_thread_state(state); 2271 // 2272 // but that is pretty messy. Instead we just go with the way the 2273 // code has worked before and note that this is the only path to 2274 // java_suspend_self that doesn't put the thread in _thread_blocked 2275 // mode. 2276 2277 frame_anchor()->make_walkable(this); 2278 java_suspend_self(); 2279 2280 // We might be here for reasons in addition to the self-suspend request 2281 // so check for other async requests. 2282 } 2283 2284 if (check_asyncs) { 2285 check_and_handle_async_exceptions(); 2286 } 2287 #if INCLUDE_TRACE 2288 if (is_trace_suspend()) { 2289 TRACE_SUSPEND_THREAD(this); 2290 } 2291 #endif 2292 } 2293 2294 void JavaThread::send_thread_stop(oop java_throwable) { 2295 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2296 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2297 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2298 2299 // Do not throw asynchronous exceptions against the compiler thread 2300 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2301 if (!can_call_java()) return; 2302 2303 { 2304 // Actually throw the Throwable against the target Thread - however 2305 // only if there is no thread death exception installed already. 2306 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2307 // If the topmost frame is a runtime stub, then we are calling into 2308 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2309 // must deoptimize the caller before continuing, as the compiled exception handler table 2310 // may not be valid 2311 if (has_last_Java_frame()) { 2312 frame f = last_frame(); 2313 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2314 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2315 RegisterMap reg_map(this, UseBiasedLocking); 2316 frame compiled_frame = f.sender(®_map); 2317 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2318 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2319 } 2320 } 2321 } 2322 2323 // Set async. pending exception in thread. 2324 set_pending_async_exception(java_throwable); 2325 2326 if (log_is_enabled(Info, exceptions)) { 2327 ResourceMark rm; 2328 log_info(exceptions)("Pending Async. exception installed of type: %s", 2329 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2330 } 2331 // for AbortVMOnException flag 2332 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2333 } 2334 } 2335 2336 2337 // Interrupt thread so it will wake up from a potential wait() 2338 Thread::interrupt(this); 2339 } 2340 2341 // External suspension mechanism. 2342 // 2343 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2344 // to any VM_locks and it is at a transition 2345 // Self-suspension will happen on the transition out of the vm. 2346 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2347 // 2348 // Guarantees on return: 2349 // + Target thread will not execute any new bytecode (that's why we need to 2350 // force a safepoint) 2351 // + Target thread will not enter any new monitors 2352 // 2353 void JavaThread::java_suspend() { 2354 ThreadsListHandle tlh; 2355 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2356 return; 2357 } 2358 2359 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2360 if (!is_external_suspend()) { 2361 // a racing resume has cancelled us; bail out now 2362 return; 2363 } 2364 2365 // suspend is done 2366 uint32_t debug_bits = 0; 2367 // Warning: is_ext_suspend_completed() may temporarily drop the 2368 // SR_lock to allow the thread to reach a stable thread state if 2369 // it is currently in a transient thread state. 2370 if (is_ext_suspend_completed(false /* !called_by_wait */, 2371 SuspendRetryDelay, &debug_bits)) { 2372 return; 2373 } 2374 } 2375 2376 VM_ThreadSuspend vm_suspend; 2377 VMThread::execute(&vm_suspend); 2378 } 2379 2380 // Part II of external suspension. 2381 // A JavaThread self suspends when it detects a pending external suspend 2382 // request. This is usually on transitions. It is also done in places 2383 // where continuing to the next transition would surprise the caller, 2384 // e.g., monitor entry. 2385 // 2386 // Returns the number of times that the thread self-suspended. 2387 // 2388 // Note: DO NOT call java_suspend_self() when you just want to block current 2389 // thread. java_suspend_self() is the second stage of cooperative 2390 // suspension for external suspend requests and should only be used 2391 // to complete an external suspend request. 2392 // 2393 int JavaThread::java_suspend_self() { 2394 int ret = 0; 2395 2396 // we are in the process of exiting so don't suspend 2397 if (is_exiting()) { 2398 clear_external_suspend(); 2399 return ret; 2400 } 2401 2402 assert(_anchor.walkable() || 2403 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2404 "must have walkable stack"); 2405 2406 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2407 2408 assert(!this->is_ext_suspended(), 2409 "a thread trying to self-suspend should not already be suspended"); 2410 2411 if (this->is_suspend_equivalent()) { 2412 // If we are self-suspending as a result of the lifting of a 2413 // suspend equivalent condition, then the suspend_equivalent 2414 // flag is not cleared until we set the ext_suspended flag so 2415 // that wait_for_ext_suspend_completion() returns consistent 2416 // results. 2417 this->clear_suspend_equivalent(); 2418 } 2419 2420 // A racing resume may have cancelled us before we grabbed SR_lock 2421 // above. Or another external suspend request could be waiting for us 2422 // by the time we return from SR_lock()->wait(). The thread 2423 // that requested the suspension may already be trying to walk our 2424 // stack and if we return now, we can change the stack out from under 2425 // it. This would be a "bad thing (TM)" and cause the stack walker 2426 // to crash. We stay self-suspended until there are no more pending 2427 // external suspend requests. 2428 while (is_external_suspend()) { 2429 ret++; 2430 this->set_ext_suspended(); 2431 2432 // _ext_suspended flag is cleared by java_resume() 2433 while (is_ext_suspended()) { 2434 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2435 } 2436 } 2437 2438 return ret; 2439 } 2440 2441 #ifdef ASSERT 2442 // verify the JavaThread has not yet been published in the Threads::list, and 2443 // hence doesn't need protection from concurrent access at this stage 2444 void JavaThread::verify_not_published() { 2445 ThreadsListHandle tlh; 2446 assert(!tlh.includes(this), "JavaThread shouldn't have been published yet!"); 2447 } 2448 #endif 2449 2450 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2451 // progress or when _suspend_flags is non-zero. 2452 // Current thread needs to self-suspend if there is a suspend request and/or 2453 // block if a safepoint is in progress. 2454 // Async exception ISN'T checked. 2455 // Note only the ThreadInVMfromNative transition can call this function 2456 // directly and when thread state is _thread_in_native_trans 2457 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2458 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2459 2460 JavaThread *curJT = JavaThread::current(); 2461 bool do_self_suspend = thread->is_external_suspend(); 2462 2463 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2464 2465 // If JNIEnv proxies are allowed, don't self-suspend if the target 2466 // thread is not the current thread. In older versions of jdbx, jdbx 2467 // threads could call into the VM with another thread's JNIEnv so we 2468 // can be here operating on behalf of a suspended thread (4432884). 2469 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2470 JavaThreadState state = thread->thread_state(); 2471 2472 // We mark this thread_blocked state as a suspend-equivalent so 2473 // that a caller to is_ext_suspend_completed() won't be confused. 2474 // The suspend-equivalent state is cleared by java_suspend_self(). 2475 thread->set_suspend_equivalent(); 2476 2477 // If the safepoint code sees the _thread_in_native_trans state, it will 2478 // wait until the thread changes to other thread state. There is no 2479 // guarantee on how soon we can obtain the SR_lock and complete the 2480 // self-suspend request. It would be a bad idea to let safepoint wait for 2481 // too long. Temporarily change the state to _thread_blocked to 2482 // let the VM thread know that this thread is ready for GC. The problem 2483 // of changing thread state is that safepoint could happen just after 2484 // java_suspend_self() returns after being resumed, and VM thread will 2485 // see the _thread_blocked state. We must check for safepoint 2486 // after restoring the state and make sure we won't leave while a safepoint 2487 // is in progress. 2488 thread->set_thread_state(_thread_blocked); 2489 thread->java_suspend_self(); 2490 thread->set_thread_state(state); 2491 2492 InterfaceSupport::serialize_thread_state_with_handler(thread); 2493 } 2494 2495 SafepointMechanism::block_if_requested(curJT); 2496 2497 if (thread->is_deopt_suspend()) { 2498 thread->clear_deopt_suspend(); 2499 RegisterMap map(thread, false); 2500 frame f = thread->last_frame(); 2501 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2502 f = f.sender(&map); 2503 } 2504 if (f.id() == thread->must_deopt_id()) { 2505 thread->clear_must_deopt_id(); 2506 f.deoptimize(thread); 2507 } else { 2508 fatal("missed deoptimization!"); 2509 } 2510 } 2511 #if INCLUDE_TRACE 2512 if (thread->is_trace_suspend()) { 2513 TRACE_SUSPEND_THREAD(thread); 2514 } 2515 #endif 2516 } 2517 2518 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2519 // progress or when _suspend_flags is non-zero. 2520 // Current thread needs to self-suspend if there is a suspend request and/or 2521 // block if a safepoint is in progress. 2522 // Also check for pending async exception (not including unsafe access error). 2523 // Note only the native==>VM/Java barriers can call this function and when 2524 // thread state is _thread_in_native_trans. 2525 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2526 check_safepoint_and_suspend_for_native_trans(thread); 2527 2528 if (thread->has_async_exception()) { 2529 // We are in _thread_in_native_trans state, don't handle unsafe 2530 // access error since that may block. 2531 thread->check_and_handle_async_exceptions(false); 2532 } 2533 } 2534 2535 // This is a variant of the normal 2536 // check_special_condition_for_native_trans with slightly different 2537 // semantics for use by critical native wrappers. It does all the 2538 // normal checks but also performs the transition back into 2539 // thread_in_Java state. This is required so that critical natives 2540 // can potentially block and perform a GC if they are the last thread 2541 // exiting the GCLocker. 2542 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2543 check_special_condition_for_native_trans(thread); 2544 2545 // Finish the transition 2546 thread->set_thread_state(_thread_in_Java); 2547 2548 if (thread->do_critical_native_unlock()) { 2549 ThreadInVMfromJavaNoAsyncException tiv(thread); 2550 GCLocker::unlock_critical(thread); 2551 thread->clear_critical_native_unlock(); 2552 } 2553 } 2554 2555 // We need to guarantee the Threads_lock here, since resumes are not 2556 // allowed during safepoint synchronization 2557 // Can only resume from an external suspension 2558 void JavaThread::java_resume() { 2559 assert_locked_or_safepoint(Threads_lock); 2560 2561 // Sanity check: thread is gone, has started exiting or the thread 2562 // was not externally suspended. 2563 ThreadsListHandle tlh; 2564 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2565 return; 2566 } 2567 2568 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2569 2570 clear_external_suspend(); 2571 2572 if (is_ext_suspended()) { 2573 clear_ext_suspended(); 2574 SR_lock()->notify_all(); 2575 } 2576 } 2577 2578 size_t JavaThread::_stack_red_zone_size = 0; 2579 size_t JavaThread::_stack_yellow_zone_size = 0; 2580 size_t JavaThread::_stack_reserved_zone_size = 0; 2581 size_t JavaThread::_stack_shadow_zone_size = 0; 2582 2583 void JavaThread::create_stack_guard_pages() { 2584 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2585 address low_addr = stack_end(); 2586 size_t len = stack_guard_zone_size(); 2587 2588 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2589 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2590 2591 int must_commit = os::must_commit_stack_guard_pages(); 2592 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2593 2594 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2595 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2596 return; 2597 } 2598 2599 if (os::guard_memory((char *) low_addr, len)) { 2600 _stack_guard_state = stack_guard_enabled; 2601 } else { 2602 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2603 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2604 if (os::uncommit_memory((char *) low_addr, len)) { 2605 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2606 } 2607 return; 2608 } 2609 2610 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2611 PTR_FORMAT "-" PTR_FORMAT ".", 2612 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2613 } 2614 2615 void JavaThread::remove_stack_guard_pages() { 2616 assert(Thread::current() == this, "from different thread"); 2617 if (_stack_guard_state == stack_guard_unused) return; 2618 address low_addr = stack_end(); 2619 size_t len = stack_guard_zone_size(); 2620 2621 if (os::must_commit_stack_guard_pages()) { 2622 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2623 _stack_guard_state = stack_guard_unused; 2624 } else { 2625 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2626 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2627 return; 2628 } 2629 } else { 2630 if (_stack_guard_state == stack_guard_unused) return; 2631 if (os::unguard_memory((char *) low_addr, len)) { 2632 _stack_guard_state = stack_guard_unused; 2633 } else { 2634 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2635 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2636 return; 2637 } 2638 } 2639 2640 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2641 PTR_FORMAT "-" PTR_FORMAT ".", 2642 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2643 } 2644 2645 void JavaThread::enable_stack_reserved_zone() { 2646 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2647 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2648 2649 // The base notation is from the stack's point of view, growing downward. 2650 // We need to adjust it to work correctly with guard_memory() 2651 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2652 2653 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2654 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2655 2656 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2657 _stack_guard_state = stack_guard_enabled; 2658 } else { 2659 warning("Attempt to guard stack reserved zone failed."); 2660 } 2661 enable_register_stack_guard(); 2662 } 2663 2664 void JavaThread::disable_stack_reserved_zone() { 2665 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2666 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2667 2668 // Simply return if called for a thread that does not use guard pages. 2669 if (_stack_guard_state == stack_guard_unused) return; 2670 2671 // The base notation is from the stack's point of view, growing downward. 2672 // We need to adjust it to work correctly with guard_memory() 2673 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2674 2675 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2676 _stack_guard_state = stack_guard_reserved_disabled; 2677 } else { 2678 warning("Attempt to unguard stack reserved zone failed."); 2679 } 2680 disable_register_stack_guard(); 2681 } 2682 2683 void JavaThread::enable_stack_yellow_reserved_zone() { 2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2685 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2686 2687 // The base notation is from the stacks point of view, growing downward. 2688 // We need to adjust it to work correctly with guard_memory() 2689 address base = stack_red_zone_base(); 2690 2691 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2692 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2693 2694 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2695 _stack_guard_state = stack_guard_enabled; 2696 } else { 2697 warning("Attempt to guard stack yellow zone failed."); 2698 } 2699 enable_register_stack_guard(); 2700 } 2701 2702 void JavaThread::disable_stack_yellow_reserved_zone() { 2703 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2704 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2705 2706 // Simply return if called for a thread that does not use guard pages. 2707 if (_stack_guard_state == stack_guard_unused) return; 2708 2709 // The base notation is from the stacks point of view, growing downward. 2710 // We need to adjust it to work correctly with guard_memory() 2711 address base = stack_red_zone_base(); 2712 2713 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2714 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2715 } else { 2716 warning("Attempt to unguard stack yellow zone failed."); 2717 } 2718 disable_register_stack_guard(); 2719 } 2720 2721 void JavaThread::enable_stack_red_zone() { 2722 // The base notation is from the stacks point of view, growing downward. 2723 // We need to adjust it to work correctly with guard_memory() 2724 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2725 address base = stack_red_zone_base() - stack_red_zone_size(); 2726 2727 guarantee(base < stack_base(), "Error calculating stack red zone"); 2728 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2729 2730 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2731 warning("Attempt to guard stack red zone failed."); 2732 } 2733 } 2734 2735 void JavaThread::disable_stack_red_zone() { 2736 // The base notation is from the stacks point of view, growing downward. 2737 // We need to adjust it to work correctly with guard_memory() 2738 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2739 address base = stack_red_zone_base() - stack_red_zone_size(); 2740 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2741 warning("Attempt to unguard stack red zone failed."); 2742 } 2743 } 2744 2745 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2746 // ignore is there is no stack 2747 if (!has_last_Java_frame()) return; 2748 // traverse the stack frames. Starts from top frame. 2749 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2750 frame* fr = fst.current(); 2751 f(fr, fst.register_map()); 2752 } 2753 } 2754 2755 2756 #ifndef PRODUCT 2757 // Deoptimization 2758 // Function for testing deoptimization 2759 void JavaThread::deoptimize() { 2760 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2761 StackFrameStream fst(this, UseBiasedLocking); 2762 bool deopt = false; // Dump stack only if a deopt actually happens. 2763 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2764 // Iterate over all frames in the thread and deoptimize 2765 for (; !fst.is_done(); fst.next()) { 2766 if (fst.current()->can_be_deoptimized()) { 2767 2768 if (only_at) { 2769 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2770 // consists of comma or carriage return separated numbers so 2771 // search for the current bci in that string. 2772 address pc = fst.current()->pc(); 2773 nmethod* nm = (nmethod*) fst.current()->cb(); 2774 ScopeDesc* sd = nm->scope_desc_at(pc); 2775 char buffer[8]; 2776 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2777 size_t len = strlen(buffer); 2778 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2779 while (found != NULL) { 2780 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2781 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2782 // Check that the bci found is bracketed by terminators. 2783 break; 2784 } 2785 found = strstr(found + 1, buffer); 2786 } 2787 if (!found) { 2788 continue; 2789 } 2790 } 2791 2792 if (DebugDeoptimization && !deopt) { 2793 deopt = true; // One-time only print before deopt 2794 tty->print_cr("[BEFORE Deoptimization]"); 2795 trace_frames(); 2796 trace_stack(); 2797 } 2798 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2799 } 2800 } 2801 2802 if (DebugDeoptimization && deopt) { 2803 tty->print_cr("[AFTER Deoptimization]"); 2804 trace_frames(); 2805 } 2806 } 2807 2808 2809 // Make zombies 2810 void JavaThread::make_zombies() { 2811 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2812 if (fst.current()->can_be_deoptimized()) { 2813 // it is a Java nmethod 2814 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2815 nm->make_not_entrant(); 2816 } 2817 } 2818 } 2819 #endif // PRODUCT 2820 2821 2822 void JavaThread::deoptimized_wrt_marked_nmethods() { 2823 if (!has_last_Java_frame()) return; 2824 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2825 StackFrameStream fst(this, UseBiasedLocking); 2826 for (; !fst.is_done(); fst.next()) { 2827 if (fst.current()->should_be_deoptimized()) { 2828 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2829 } 2830 } 2831 } 2832 2833 2834 // If the caller is a NamedThread, then remember, in the current scope, 2835 // the given JavaThread in its _processed_thread field. 2836 class RememberProcessedThread: public StackObj { 2837 NamedThread* _cur_thr; 2838 public: 2839 RememberProcessedThread(JavaThread* jthr) { 2840 Thread* thread = Thread::current(); 2841 if (thread->is_Named_thread()) { 2842 _cur_thr = (NamedThread *)thread; 2843 _cur_thr->set_processed_thread(jthr); 2844 } else { 2845 _cur_thr = NULL; 2846 } 2847 } 2848 2849 ~RememberProcessedThread() { 2850 if (_cur_thr) { 2851 _cur_thr->set_processed_thread(NULL); 2852 } 2853 } 2854 }; 2855 2856 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2857 // Verify that the deferred card marks have been flushed. 2858 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2859 2860 // Traverse the GCHandles 2861 Thread::oops_do(f, cf); 2862 2863 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2864 2865 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2866 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2867 2868 if (has_last_Java_frame()) { 2869 // Record JavaThread to GC thread 2870 RememberProcessedThread rpt(this); 2871 2872 // Traverse the privileged stack 2873 if (_privileged_stack_top != NULL) { 2874 _privileged_stack_top->oops_do(f); 2875 } 2876 2877 // traverse the registered growable array 2878 if (_array_for_gc != NULL) { 2879 for (int index = 0; index < _array_for_gc->length(); index++) { 2880 f->do_oop(_array_for_gc->adr_at(index)); 2881 } 2882 } 2883 2884 // Traverse the monitor chunks 2885 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2886 chunk->oops_do(f); 2887 } 2888 2889 // Traverse the execution stack 2890 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2891 fst.current()->oops_do(f, cf, fst.register_map()); 2892 } 2893 } 2894 2895 // callee_target is never live across a gc point so NULL it here should 2896 // it still contain a methdOop. 2897 2898 set_callee_target(NULL); 2899 2900 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2901 // If we have deferred set_locals there might be oops waiting to be 2902 // written 2903 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2904 if (list != NULL) { 2905 for (int i = 0; i < list->length(); i++) { 2906 list->at(i)->oops_do(f); 2907 } 2908 } 2909 2910 // Traverse instance variables at the end since the GC may be moving things 2911 // around using this function 2912 f->do_oop((oop*) &_threadObj); 2913 f->do_oop((oop*) &_vm_result); 2914 f->do_oop((oop*) &_exception_oop); 2915 f->do_oop((oop*) &_pending_async_exception); 2916 2917 if (jvmti_thread_state() != NULL) { 2918 jvmti_thread_state()->oops_do(f); 2919 } 2920 } 2921 2922 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2923 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2924 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2925 2926 if (has_last_Java_frame()) { 2927 // Traverse the execution stack 2928 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2929 fst.current()->nmethods_do(cf); 2930 } 2931 } 2932 } 2933 2934 void JavaThread::metadata_do(void f(Metadata*)) { 2935 if (has_last_Java_frame()) { 2936 // Traverse the execution stack to call f() on the methods in the stack 2937 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2938 fst.current()->metadata_do(f); 2939 } 2940 } else if (is_Compiler_thread()) { 2941 // need to walk ciMetadata in current compile tasks to keep alive. 2942 CompilerThread* ct = (CompilerThread*)this; 2943 if (ct->env() != NULL) { 2944 ct->env()->metadata_do(f); 2945 } 2946 if (ct->task() != NULL) { 2947 ct->task()->metadata_do(f); 2948 } 2949 } 2950 } 2951 2952 // Printing 2953 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2954 switch (_thread_state) { 2955 case _thread_uninitialized: return "_thread_uninitialized"; 2956 case _thread_new: return "_thread_new"; 2957 case _thread_new_trans: return "_thread_new_trans"; 2958 case _thread_in_native: return "_thread_in_native"; 2959 case _thread_in_native_trans: return "_thread_in_native_trans"; 2960 case _thread_in_vm: return "_thread_in_vm"; 2961 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2962 case _thread_in_Java: return "_thread_in_Java"; 2963 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2964 case _thread_blocked: return "_thread_blocked"; 2965 case _thread_blocked_trans: return "_thread_blocked_trans"; 2966 default: return "unknown thread state"; 2967 } 2968 } 2969 2970 #ifndef PRODUCT 2971 void JavaThread::print_thread_state_on(outputStream *st) const { 2972 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2973 }; 2974 void JavaThread::print_thread_state() const { 2975 print_thread_state_on(tty); 2976 } 2977 #endif // PRODUCT 2978 2979 // Called by Threads::print() for VM_PrintThreads operation 2980 void JavaThread::print_on(outputStream *st) const { 2981 st->print_raw("\""); 2982 st->print_raw(get_thread_name()); 2983 st->print_raw("\" "); 2984 oop thread_oop = threadObj(); 2985 if (thread_oop != NULL) { 2986 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2987 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2988 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2989 } 2990 Thread::print_on(st); 2991 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2992 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2993 if (thread_oop != NULL) { 2994 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2995 } 2996 #ifndef PRODUCT 2997 print_thread_state_on(st); 2998 _safepoint_state->print_on(st); 2999 #endif // PRODUCT 3000 if (is_Compiler_thread()) { 3001 CompilerThread* ct = (CompilerThread*)this; 3002 if (ct->task() != NULL) { 3003 st->print(" Compiling: "); 3004 ct->task()->print(st, NULL, true, false); 3005 } else { 3006 st->print(" No compile task"); 3007 } 3008 st->cr(); 3009 } 3010 } 3011 3012 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3013 st->print("%s", get_thread_name_string(buf, buflen)); 3014 } 3015 3016 // Called by fatal error handler. The difference between this and 3017 // JavaThread::print() is that we can't grab lock or allocate memory. 3018 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3019 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3020 oop thread_obj = threadObj(); 3021 if (thread_obj != NULL) { 3022 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3023 } 3024 st->print(" ["); 3025 st->print("%s", _get_thread_state_name(_thread_state)); 3026 if (osthread()) { 3027 st->print(", id=%d", osthread()->thread_id()); 3028 } 3029 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3030 p2i(stack_end()), p2i(stack_base())); 3031 st->print("]"); 3032 3033 if (_threads_hazard_ptr != NULL) { 3034 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 3035 } 3036 if (_nested_threads_hazard_ptr != NULL) { 3037 print_nested_threads_hazard_ptrs_on(st); 3038 } 3039 return; 3040 } 3041 3042 // Verification 3043 3044 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3045 3046 void JavaThread::verify() { 3047 // Verify oops in the thread. 3048 oops_do(&VerifyOopClosure::verify_oop, NULL); 3049 3050 // Verify the stack frames. 3051 frames_do(frame_verify); 3052 } 3053 3054 // CR 6300358 (sub-CR 2137150) 3055 // Most callers of this method assume that it can't return NULL but a 3056 // thread may not have a name whilst it is in the process of attaching to 3057 // the VM - see CR 6412693, and there are places where a JavaThread can be 3058 // seen prior to having it's threadObj set (eg JNI attaching threads and 3059 // if vm exit occurs during initialization). These cases can all be accounted 3060 // for such that this method never returns NULL. 3061 const char* JavaThread::get_thread_name() const { 3062 #ifdef ASSERT 3063 // early safepoints can hit while current thread does not yet have TLS 3064 if (!SafepointSynchronize::is_at_safepoint()) { 3065 Thread *cur = Thread::current(); 3066 if (!(cur->is_Java_thread() && cur == this)) { 3067 // Current JavaThreads are allowed to get their own name without 3068 // the Threads_lock. 3069 assert_locked_or_safepoint(Threads_lock); 3070 } 3071 } 3072 #endif // ASSERT 3073 return get_thread_name_string(); 3074 } 3075 3076 // Returns a non-NULL representation of this thread's name, or a suitable 3077 // descriptive string if there is no set name 3078 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3079 const char* name_str; 3080 oop thread_obj = threadObj(); 3081 if (thread_obj != NULL) { 3082 oop name = java_lang_Thread::name(thread_obj); 3083 if (name != NULL) { 3084 if (buf == NULL) { 3085 name_str = java_lang_String::as_utf8_string(name); 3086 } else { 3087 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3088 } 3089 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3090 name_str = "<no-name - thread is attaching>"; 3091 } else { 3092 name_str = Thread::name(); 3093 } 3094 } else { 3095 name_str = Thread::name(); 3096 } 3097 assert(name_str != NULL, "unexpected NULL thread name"); 3098 return name_str; 3099 } 3100 3101 3102 const char* JavaThread::get_threadgroup_name() const { 3103 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3104 oop thread_obj = threadObj(); 3105 if (thread_obj != NULL) { 3106 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3107 if (thread_group != NULL) { 3108 // ThreadGroup.name can be null 3109 return java_lang_ThreadGroup::name(thread_group); 3110 } 3111 } 3112 return NULL; 3113 } 3114 3115 const char* JavaThread::get_parent_name() const { 3116 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3117 oop thread_obj = threadObj(); 3118 if (thread_obj != NULL) { 3119 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3120 if (thread_group != NULL) { 3121 oop parent = java_lang_ThreadGroup::parent(thread_group); 3122 if (parent != NULL) { 3123 // ThreadGroup.name can be null 3124 return java_lang_ThreadGroup::name(parent); 3125 } 3126 } 3127 } 3128 return NULL; 3129 } 3130 3131 ThreadPriority JavaThread::java_priority() const { 3132 oop thr_oop = threadObj(); 3133 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3134 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3135 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3136 return priority; 3137 } 3138 3139 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3140 3141 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3142 // Link Java Thread object <-> C++ Thread 3143 3144 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3145 // and put it into a new Handle. The Handle "thread_oop" can then 3146 // be used to pass the C++ thread object to other methods. 3147 3148 // Set the Java level thread object (jthread) field of the 3149 // new thread (a JavaThread *) to C++ thread object using the 3150 // "thread_oop" handle. 3151 3152 // Set the thread field (a JavaThread *) of the 3153 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3154 3155 Handle thread_oop(Thread::current(), 3156 JNIHandles::resolve_non_null(jni_thread)); 3157 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3158 "must be initialized"); 3159 set_threadObj(thread_oop()); 3160 java_lang_Thread::set_thread(thread_oop(), this); 3161 3162 if (prio == NoPriority) { 3163 prio = java_lang_Thread::priority(thread_oop()); 3164 assert(prio != NoPriority, "A valid priority should be present"); 3165 } 3166 3167 // Push the Java priority down to the native thread; needs Threads_lock 3168 Thread::set_priority(this, prio); 3169 3170 prepare_ext(); 3171 3172 // Add the new thread to the Threads list and set it in motion. 3173 // We must have threads lock in order to call Threads::add. 3174 // It is crucial that we do not block before the thread is 3175 // added to the Threads list for if a GC happens, then the java_thread oop 3176 // will not be visited by GC. 3177 Threads::add(this); 3178 } 3179 3180 oop JavaThread::current_park_blocker() { 3181 // Support for JSR-166 locks 3182 oop thread_oop = threadObj(); 3183 if (thread_oop != NULL && 3184 JDK_Version::current().supports_thread_park_blocker()) { 3185 return java_lang_Thread::park_blocker(thread_oop); 3186 } 3187 return NULL; 3188 } 3189 3190 3191 void JavaThread::print_stack_on(outputStream* st) { 3192 if (!has_last_Java_frame()) return; 3193 ResourceMark rm; 3194 HandleMark hm; 3195 3196 RegisterMap reg_map(this); 3197 vframe* start_vf = last_java_vframe(®_map); 3198 int count = 0; 3199 for (vframe* f = start_vf; f; f = f->sender()) { 3200 if (f->is_java_frame()) { 3201 javaVFrame* jvf = javaVFrame::cast(f); 3202 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3203 3204 // Print out lock information 3205 if (JavaMonitorsInStackTrace) { 3206 jvf->print_lock_info_on(st, count); 3207 } 3208 } else { 3209 // Ignore non-Java frames 3210 } 3211 3212 // Bail-out case for too deep stacks 3213 count++; 3214 if (MaxJavaStackTraceDepth == count) return; 3215 } 3216 } 3217 3218 3219 // JVMTI PopFrame support 3220 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3221 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3222 if (in_bytes(size_in_bytes) != 0) { 3223 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3224 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3225 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3226 } 3227 } 3228 3229 void* JavaThread::popframe_preserved_args() { 3230 return _popframe_preserved_args; 3231 } 3232 3233 ByteSize JavaThread::popframe_preserved_args_size() { 3234 return in_ByteSize(_popframe_preserved_args_size); 3235 } 3236 3237 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3238 int sz = in_bytes(popframe_preserved_args_size()); 3239 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3240 return in_WordSize(sz / wordSize); 3241 } 3242 3243 void JavaThread::popframe_free_preserved_args() { 3244 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3245 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3246 _popframe_preserved_args = NULL; 3247 _popframe_preserved_args_size = 0; 3248 } 3249 3250 #ifndef PRODUCT 3251 3252 void JavaThread::trace_frames() { 3253 tty->print_cr("[Describe stack]"); 3254 int frame_no = 1; 3255 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3256 tty->print(" %d. ", frame_no++); 3257 fst.current()->print_value_on(tty, this); 3258 tty->cr(); 3259 } 3260 } 3261 3262 class PrintAndVerifyOopClosure: public OopClosure { 3263 protected: 3264 template <class T> inline void do_oop_work(T* p) { 3265 oop obj = oopDesc::load_decode_heap_oop(p); 3266 if (obj == NULL) return; 3267 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3268 if (oopDesc::is_oop_or_null(obj)) { 3269 if (obj->is_objArray()) { 3270 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3271 } else { 3272 obj->print(); 3273 } 3274 } else { 3275 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3276 } 3277 tty->cr(); 3278 } 3279 public: 3280 virtual void do_oop(oop* p) { do_oop_work(p); } 3281 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3282 }; 3283 3284 3285 static void oops_print(frame* f, const RegisterMap *map) { 3286 PrintAndVerifyOopClosure print; 3287 f->print_value(); 3288 f->oops_do(&print, NULL, (RegisterMap*)map); 3289 } 3290 3291 // Print our all the locations that contain oops and whether they are 3292 // valid or not. This useful when trying to find the oldest frame 3293 // where an oop has gone bad since the frame walk is from youngest to 3294 // oldest. 3295 void JavaThread::trace_oops() { 3296 tty->print_cr("[Trace oops]"); 3297 frames_do(oops_print); 3298 } 3299 3300 3301 #ifdef ASSERT 3302 // Print or validate the layout of stack frames 3303 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3304 ResourceMark rm; 3305 PRESERVE_EXCEPTION_MARK; 3306 FrameValues values; 3307 int frame_no = 0; 3308 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3309 fst.current()->describe(values, ++frame_no); 3310 if (depth == frame_no) break; 3311 } 3312 if (validate_only) { 3313 values.validate(); 3314 } else { 3315 tty->print_cr("[Describe stack layout]"); 3316 values.print(this); 3317 } 3318 } 3319 #endif 3320 3321 void JavaThread::trace_stack_from(vframe* start_vf) { 3322 ResourceMark rm; 3323 int vframe_no = 1; 3324 for (vframe* f = start_vf; f; f = f->sender()) { 3325 if (f->is_java_frame()) { 3326 javaVFrame::cast(f)->print_activation(vframe_no++); 3327 } else { 3328 f->print(); 3329 } 3330 if (vframe_no > StackPrintLimit) { 3331 tty->print_cr("...<more frames>..."); 3332 return; 3333 } 3334 } 3335 } 3336 3337 3338 void JavaThread::trace_stack() { 3339 if (!has_last_Java_frame()) return; 3340 ResourceMark rm; 3341 HandleMark hm; 3342 RegisterMap reg_map(this); 3343 trace_stack_from(last_java_vframe(®_map)); 3344 } 3345 3346 3347 #endif // PRODUCT 3348 3349 3350 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3351 assert(reg_map != NULL, "a map must be given"); 3352 frame f = last_frame(); 3353 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3354 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3355 } 3356 return NULL; 3357 } 3358 3359 3360 Klass* JavaThread::security_get_caller_class(int depth) { 3361 vframeStream vfst(this); 3362 vfst.security_get_caller_frame(depth); 3363 if (!vfst.at_end()) { 3364 return vfst.method()->method_holder(); 3365 } 3366 return NULL; 3367 } 3368 3369 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3370 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3371 CompileBroker::compiler_thread_loop(); 3372 } 3373 3374 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3375 NMethodSweeper::sweeper_loop(); 3376 } 3377 3378 // Create a CompilerThread 3379 CompilerThread::CompilerThread(CompileQueue* queue, 3380 CompilerCounters* counters) 3381 : JavaThread(&compiler_thread_entry) { 3382 _env = NULL; 3383 _log = NULL; 3384 _task = NULL; 3385 _queue = queue; 3386 _counters = counters; 3387 _buffer_blob = NULL; 3388 _compiler = NULL; 3389 3390 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3391 resource_area()->bias_to(mtCompiler); 3392 3393 #ifndef PRODUCT 3394 _ideal_graph_printer = NULL; 3395 #endif 3396 } 3397 3398 bool CompilerThread::can_call_java() const { 3399 return _compiler != NULL && _compiler->is_jvmci(); 3400 } 3401 3402 // Create sweeper thread 3403 CodeCacheSweeperThread::CodeCacheSweeperThread() 3404 : JavaThread(&sweeper_thread_entry) { 3405 _scanned_compiled_method = NULL; 3406 } 3407 3408 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3409 JavaThread::oops_do(f, cf); 3410 if (_scanned_compiled_method != NULL && cf != NULL) { 3411 // Safepoints can occur when the sweeper is scanning an nmethod so 3412 // process it here to make sure it isn't unloaded in the middle of 3413 // a scan. 3414 cf->do_code_blob(_scanned_compiled_method); 3415 } 3416 } 3417 3418 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3419 JavaThread::nmethods_do(cf); 3420 if (_scanned_compiled_method != NULL && cf != NULL) { 3421 // Safepoints can occur when the sweeper is scanning an nmethod so 3422 // process it here to make sure it isn't unloaded in the middle of 3423 // a scan. 3424 cf->do_code_blob(_scanned_compiled_method); 3425 } 3426 } 3427 3428 3429 // ======= Threads ======== 3430 3431 // The Threads class links together all active threads, and provides 3432 // operations over all threads. It is protected by its own Mutex 3433 // lock, which is also used in other contexts to protect thread 3434 // operations from having the thread being operated on from exiting 3435 // and going away unexpectedly (e.g., safepoint synchronization) 3436 3437 JavaThread* Threads::_thread_list = NULL; 3438 int Threads::_number_of_threads = 0; 3439 int Threads::_number_of_non_daemon_threads = 0; 3440 int Threads::_return_code = 0; 3441 int Threads::_thread_claim_parity = 0; 3442 size_t JavaThread::_stack_size_at_create = 0; 3443 // Safe Memory Reclamation (SMR) support: 3444 Monitor* Threads::_smr_delete_lock = 3445 new Monitor(Monitor::special, "smr_delete_lock", 3446 false /* allow_vm_block */, 3447 Monitor::_safepoint_check_never); 3448 // The '_cnt', '_max' and '_times" fields are enabled via 3449 // -XX:+EnableThreadSMRStatistics: 3450 3451 // # of parallel threads in _smr_delete_lock->wait(). 3452 // Impl note: Hard to imagine > 64K waiting threads so this could be 16-bit, 3453 // but there is no nice 16-bit _FORMAT support. 3454 uint Threads::_smr_delete_lock_wait_cnt = 0; 3455 3456 // Max # of parallel threads in _smr_delete_lock->wait(). 3457 // Impl note: See _smr_delete_lock_wait_cnt note. 3458 uint Threads::_smr_delete_lock_wait_max = 0; 3459 3460 // Flag to indicate when an _smr_delete_lock->notify() is needed. 3461 // Impl note: See _smr_delete_lock_wait_cnt note. 3462 volatile uint Threads::_smr_delete_notify = 0; 3463 3464 // # of threads deleted over VM lifetime. 3465 // Impl note: Atomically incremented over VM lifetime so use unsigned for more 3466 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc 3467 // isn't available everywhere (or is it?). 3468 volatile uint Threads::_smr_deleted_thread_cnt = 0; 3469 3470 // Max time in millis to delete a thread. 3471 // Impl note: 16-bit might be too small on an overloaded machine. Use 3472 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a 3473 // loop for correctness. 3474 volatile uint Threads::_smr_deleted_thread_time_max = 0; 3475 3476 // Cumulative time in millis to delete threads. 3477 // Impl note: Atomically added to over VM lifetime so use unsigned for more 3478 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc 3479 // isn't available everywhere (or is it?). 3480 volatile uint Threads::_smr_deleted_thread_times = 0; 3481 3482 ThreadsList* volatile Threads::_smr_java_thread_list = new ThreadsList(0); 3483 3484 // # of ThreadsLists allocated over VM lifetime. 3485 // Impl note: We allocate a new ThreadsList for every thread create and 3486 // every thread delete so we need a bigger type than the 3487 // _smr_deleted_thread_cnt field. 3488 uint64_t Threads::_smr_java_thread_list_alloc_cnt = 1; 3489 3490 // # of ThreadsLists freed over VM lifetime. 3491 // Impl note: See _smr_java_thread_list_alloc_cnt note. 3492 uint64_t Threads::_smr_java_thread_list_free_cnt = 0; 3493 3494 // Max size ThreadsList allocated. 3495 // Impl note: Max # of threads alive at one time should fit in unsigned 32-bit. 3496 uint Threads::_smr_java_thread_list_max = 0; 3497 3498 // Max # of nested ThreadsLists for a thread. 3499 // Impl note: Hard to imagine > 64K nested ThreadsLists so this could be 3500 // 16-bit, but there is no nice 16-bit _FORMAT support. 3501 uint Threads::_smr_nested_thread_list_max = 0; 3502 3503 // # of ThreadsListHandles deleted over VM lifetime. 3504 // Impl note: Atomically incremented over VM lifetime so use unsigned for 3505 // more range. There will be fewer ThreadsListHandles than threads so 3506 // unsigned 32-bit should be fine. 3507 volatile uint Threads::_smr_tlh_cnt = 0; 3508 3509 // Max time in millis to delete a ThreadsListHandle. 3510 // Impl note: 16-bit might be too small on an overloaded machine. Use 3511 // unsigned since this is a time value. Set via Atomic::cmpxchg() in a 3512 // loop for correctness. 3513 volatile uint Threads::_smr_tlh_time_max = 0; 3514 3515 // Cumulative time in millis to delete ThreadsListHandles. 3516 // Impl note: Atomically added to over VM lifetime so use unsigned for more 3517 // range. Unsigned 64-bit would be more future proof, but 64-bit atomic inc 3518 // isn't available everywhere (or is it?). 3519 volatile uint Threads::_smr_tlh_times = 0; 3520 3521 ThreadsList* Threads::_smr_to_delete_list = NULL; 3522 3523 // # of parallel ThreadsLists on the to-delete list. 3524 // Impl note: Hard to imagine > 64K ThreadsLists needing to be deleted so 3525 // this could be 16-bit, but there is no nice 16-bit _FORMAT support. 3526 uint Threads::_smr_to_delete_list_cnt = 0; 3527 3528 // Max # of parallel ThreadsLists on the to-delete list. 3529 // Impl note: See _smr_to_delete_list_cnt note. 3530 uint Threads::_smr_to_delete_list_max = 0; 3531 3532 #ifdef ASSERT 3533 bool Threads::_vm_complete = false; 3534 #endif 3535 3536 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3537 Prefetch::read((void*)addr, prefetch_interval); 3538 return *addr; 3539 } 3540 3541 // Possibly the ugliest for loop the world has seen. C++ does not allow 3542 // multiple types in the declaration section of the for loop. In this case 3543 // we are only dealing with pointers and hence can cast them. It looks ugly 3544 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3545 #define DO_JAVA_THREADS(LIST, X) \ 3546 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3547 *MACRO_list = (JavaThread*)(LIST), \ 3548 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3549 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3550 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3551 MACRO_current_p != MACRO_end; \ 3552 MACRO_current_p++, \ 3553 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3554 3555 // All JavaThreads 3556 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(get_smr_java_thread_list(), X) 3557 3558 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3559 void Threads::threads_do(ThreadClosure* tc) { 3560 assert_locked_or_safepoint(Threads_lock); 3561 // ALL_JAVA_THREADS iterates through all JavaThreads 3562 ALL_JAVA_THREADS(p) { 3563 tc->do_thread(p); 3564 } 3565 // Someday we could have a table or list of all non-JavaThreads. 3566 // For now, just manually iterate through them. 3567 tc->do_thread(VMThread::vm_thread()); 3568 Universe::heap()->gc_threads_do(tc); 3569 WatcherThread *wt = WatcherThread::watcher_thread(); 3570 // Strictly speaking, the following NULL check isn't sufficient to make sure 3571 // the data for WatcherThread is still valid upon being examined. However, 3572 // considering that WatchThread terminates when the VM is on the way to 3573 // exit at safepoint, the chance of the above is extremely small. The right 3574 // way to prevent termination of WatcherThread would be to acquire 3575 // Terminator_lock, but we can't do that without violating the lock rank 3576 // checking in some cases. 3577 if (wt != NULL) { 3578 tc->do_thread(wt); 3579 } 3580 3581 // If CompilerThreads ever become non-JavaThreads, add them here 3582 } 3583 3584 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3585 int cp = Threads::thread_claim_parity(); 3586 ALL_JAVA_THREADS(p) { 3587 if (p->claim_oops_do(is_par, cp)) { 3588 tc->do_thread(p); 3589 } 3590 } 3591 VMThread* vmt = VMThread::vm_thread(); 3592 if (vmt->claim_oops_do(is_par, cp)) { 3593 tc->do_thread(vmt); 3594 } 3595 } 3596 3597 // The system initialization in the library has three phases. 3598 // 3599 // Phase 1: java.lang.System class initialization 3600 // java.lang.System is a primordial class loaded and initialized 3601 // by the VM early during startup. java.lang.System.<clinit> 3602 // only does registerNatives and keeps the rest of the class 3603 // initialization work later until thread initialization completes. 3604 // 3605 // System.initPhase1 initializes the system properties, the static 3606 // fields in, out, and err. Set up java signal handlers, OS-specific 3607 // system settings, and thread group of the main thread. 3608 static void call_initPhase1(TRAPS) { 3609 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3610 JavaValue result(T_VOID); 3611 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3612 vmSymbols::void_method_signature(), CHECK); 3613 } 3614 3615 // Phase 2. Module system initialization 3616 // This will initialize the module system. Only java.base classes 3617 // can be loaded until phase 2 completes. 3618 // 3619 // Call System.initPhase2 after the compiler initialization and jsr292 3620 // classes get initialized because module initialization runs a lot of java 3621 // code, that for performance reasons, should be compiled. Also, this will 3622 // enable the startup code to use lambda and other language features in this 3623 // phase and onward. 3624 // 3625 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3626 static void call_initPhase2(TRAPS) { 3627 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3628 3629 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3630 3631 JavaValue result(T_INT); 3632 JavaCallArguments args; 3633 args.push_int(DisplayVMOutputToStderr); 3634 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3635 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3636 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3637 if (result.get_jint() != JNI_OK) { 3638 vm_exit_during_initialization(); // no message or exception 3639 } 3640 3641 universe_post_module_init(); 3642 } 3643 3644 // Phase 3. final setup - set security manager, system class loader and TCCL 3645 // 3646 // This will instantiate and set the security manager, set the system class 3647 // loader as well as the thread context class loader. The security manager 3648 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3649 // other modules or the application's classpath. 3650 static void call_initPhase3(TRAPS) { 3651 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3652 JavaValue result(T_VOID); 3653 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3654 vmSymbols::void_method_signature(), CHECK); 3655 } 3656 3657 // Safe Memory Reclamation (SMR) support: 3658 // 3659 3660 // Acquire a stable ThreadsList. 3661 // 3662 ThreadsList *Threads::acquire_stable_list(Thread *self, bool is_ThreadsListSetter) { 3663 assert(self != NULL, "sanity check"); 3664 // acquire_stable_list_nested_path() will grab the Threads_lock 3665 // so let's make sure the ThreadsListHandle is in a safe place. 3666 // ThreadsListSetter cannot make this check on this code path. 3667 debug_only(if (!is_ThreadsListSetter && StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);) 3668 3669 if (self->get_threads_hazard_ptr() == NULL) { 3670 // The typical case is first. 3671 return acquire_stable_list_fast_path(self); 3672 } 3673 3674 // The nested case is rare. 3675 return acquire_stable_list_nested_path(self); 3676 } 3677 3678 // Fast path (and lock free) way to acquire a stable ThreadsList. 3679 // 3680 ThreadsList *Threads::acquire_stable_list_fast_path(Thread *self) { 3681 assert(self != NULL, "sanity check"); 3682 assert(self->get_threads_hazard_ptr() == NULL, "sanity check"); 3683 assert(self->get_nested_threads_hazard_ptr() == NULL, 3684 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 3685 3686 ThreadsList* threads; 3687 3688 // Stable recording of a hazard ptr for SMR. This code does not use 3689 // locks so its use of the _smr_java_thread_list & _threads_hazard_ptr 3690 // fields is racy relative to code that uses those fields with locks. 3691 // OrderAccess and Atomic functions are used to deal with those races. 3692 // 3693 while (true) { 3694 threads = get_smr_java_thread_list(); 3695 3696 // Publish a tagged hazard ptr to denote that the hazard ptr is not 3697 // yet verified as being stable. Due to the fence after the hazard 3698 // ptr write, it will be sequentially consistent w.r.t. the 3699 // sequentially consistent writes of the ThreadsList, even on 3700 // non-multiple copy atomic machines where stores can be observed 3701 // in different order from different observer threads. 3702 ThreadsList* unverified_threads = Thread::tag_hazard_ptr(threads); 3703 self->set_threads_hazard_ptr(unverified_threads); 3704 3705 // If _smr_java_thread_list has changed, we have lost a race with 3706 // Threads::add() or Threads::remove() and have to try again. 3707 if (get_smr_java_thread_list() != threads) { 3708 continue; 3709 } 3710 3711 // We try to remove the tag which will verify the hazard ptr as 3712 // being stable. This exchange can race with a scanning thread 3713 // which might invalidate the tagged hazard ptr to keep it from 3714 // being followed to access JavaThread ptrs. If we lose the race, 3715 // we simply retry. If we win the race, then the stable hazard 3716 // ptr is officially published. 3717 if (self->cmpxchg_threads_hazard_ptr(threads, unverified_threads) == unverified_threads) { 3718 break; 3719 } 3720 } 3721 3722 // A stable hazard ptr has been published letting other threads know 3723 // that the ThreadsList and the JavaThreads reachable from this list 3724 // are protected and hence they should not be deleted until everyone 3725 // agrees it is safe to do so. 3726 3727 return threads; 3728 } 3729 3730 // Acquire a nested stable ThreadsList; this is rare so it uses 3731 // Threads_lock. 3732 // 3733 ThreadsList *Threads::acquire_stable_list_nested_path(Thread *self) { 3734 assert(self != NULL, "sanity check"); 3735 assert(self->get_threads_hazard_ptr() != NULL, 3736 "cannot have a NULL regular hazard ptr when acquiring a nested hazard ptr"); 3737 3738 // The thread already has a hazard ptr (ThreadsList ref) so we need 3739 // to create a nested ThreadsListHandle with the current ThreadsList 3740 // since it might be different than our current hazard ptr. The need 3741 // for a nested ThreadsListHandle is rare so we do this while holding 3742 // the Threads_lock so we don't race with the scanning code; the code 3743 // is so much simpler this way. 3744 3745 NestedThreadsList* node; 3746 { 3747 // Only grab the Threads_lock if we don't already own it. 3748 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock); 3749 node = new NestedThreadsList(get_smr_java_thread_list()); 3750 // We insert at the front of the list to match up with the delete 3751 // in release_stable_list(). 3752 node->set_next(self->get_nested_threads_hazard_ptr()); 3753 self->set_nested_threads_hazard_ptr(node); 3754 if (EnableThreadSMRStatistics) { 3755 self->inc_nested_threads_hazard_ptr_cnt(); 3756 if (self->nested_threads_hazard_ptr_cnt() > _smr_nested_thread_list_max) { 3757 _smr_nested_thread_list_max = self->nested_threads_hazard_ptr_cnt(); 3758 } 3759 } 3760 } 3761 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::acquire_stable_list: add NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list())); 3762 3763 return node->t_list(); 3764 } 3765 3766 // Release a stable ThreadsList. 3767 // 3768 void Threads::release_stable_list(Thread *self) { 3769 assert(self != NULL, "sanity check"); 3770 // release_stable_list_nested_path() will grab the Threads_lock 3771 // so let's make sure the ThreadsListHandle is in a safe place. 3772 debug_only(if (StrictSafepointChecks) self->check_for_valid_safepoint_state(/* potential_vm_operation */ false);) 3773 3774 if (self->get_nested_threads_hazard_ptr() == NULL) { 3775 // The typical case is first. 3776 release_stable_list_fast_path(self); 3777 return; 3778 } 3779 3780 // The nested case is rare. 3781 release_stable_list_nested_path(self); 3782 } 3783 3784 // Fast path way to release a stable ThreadsList. The release portion 3785 // is lock-free, but the wake up portion is not. 3786 // 3787 void Threads::release_stable_list_fast_path(Thread *self) { 3788 assert(self != NULL, "sanity check"); 3789 assert(self->get_threads_hazard_ptr() != NULL, "sanity check"); 3790 assert(self->get_nested_threads_hazard_ptr() == NULL, 3791 "cannot have a nested hazard ptr when releasing a regular hazard ptr"); 3792 3793 // After releasing the hazard ptr, other threads may go ahead and 3794 // free up some memory temporarily used by a ThreadsList snapshot. 3795 self->set_threads_hazard_ptr(NULL); 3796 3797 // We use double-check locking to reduce traffic on the system 3798 // wide smr_delete_lock. 3799 if (Threads::smr_delete_notify()) { 3800 // An exiting thread might be waiting in smr_delete(); we need to 3801 // check with smr_delete_lock to be sure. 3802 release_stable_list_wake_up((char *) "regular hazard ptr"); 3803 } 3804 } 3805 3806 // Release a nested stable ThreadsList; this is rare so it uses 3807 // Threads_lock. 3808 // 3809 void Threads::release_stable_list_nested_path(Thread *self) { 3810 assert(self != NULL, "sanity check"); 3811 assert(self->get_nested_threads_hazard_ptr() != NULL, "sanity check"); 3812 assert(self->get_threads_hazard_ptr() != NULL, 3813 "must have a regular hazard ptr to have nested hazard ptrs"); 3814 3815 // We have a nested ThreadsListHandle so we have to release it first. 3816 // The need for a nested ThreadsListHandle is rare so we do this while 3817 // holding the Threads_lock so we don't race with the scanning code; 3818 // the code is so much simpler this way. 3819 3820 NestedThreadsList *node; 3821 { 3822 // Only grab the Threads_lock if we don't already own it. 3823 MutexLockerEx ml(Threads_lock->owned_by_self() ? NULL : Threads_lock); 3824 // We remove from the front of the list to match up with the insert 3825 // in acquire_stable_list(). 3826 node = self->get_nested_threads_hazard_ptr(); 3827 self->set_nested_threads_hazard_ptr(node->next()); 3828 if (EnableThreadSMRStatistics) { 3829 self->dec_nested_threads_hazard_ptr_cnt(); 3830 } 3831 } 3832 3833 // An exiting thread might be waiting in smr_delete(); we need to 3834 // check with smr_delete_lock to be sure. 3835 release_stable_list_wake_up((char *) "nested hazard ptr"); 3836 3837 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list: delete NestedThreadsList node containing ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(node->t_list())); 3838 3839 delete node; 3840 } 3841 3842 // Wake up portion of the release stable ThreadsList protocol; 3843 // uses the smr_delete_lock(). 3844 // 3845 void Threads::release_stable_list_wake_up(char *log_str) { 3846 assert(log_str != NULL, "sanity check"); 3847 3848 // Note: smr_delete_lock is held in smr_delete() for the entire 3849 // hazard ptr search so that we do not lose this notify() if 3850 // the exiting thread has to wait. That code path also holds 3851 // Threads_lock (which was grabbed before smr_delete_lock) so that 3852 // threads_do() can be called. This means the system can't start a 3853 // safepoint which means this thread can't take too long to get to 3854 // a safepoint because of being blocked on smr_delete_lock. 3855 // 3856 MonitorLockerEx ml(Threads::smr_delete_lock(), Monitor::_no_safepoint_check_flag); 3857 if (Threads::smr_delete_notify()) { 3858 // Notify any exiting JavaThreads that are waiting in smr_delete() 3859 // that we've released a ThreadsList. 3860 ml.notify_all(); 3861 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::release_stable_list notified %s", os::current_thread_id(), log_str); 3862 } 3863 } 3864 3865 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3866 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3867 3868 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3869 create_vm_init_libraries(); 3870 } 3871 3872 initialize_class(vmSymbols::java_lang_String(), CHECK); 3873 3874 // Inject CompactStrings value after the static initializers for String ran. 3875 java_lang_String::set_compact_strings(CompactStrings); 3876 3877 // Initialize java_lang.System (needed before creating the thread) 3878 initialize_class(vmSymbols::java_lang_System(), CHECK); 3879 // The VM creates & returns objects of this class. Make sure it's initialized. 3880 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3881 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3882 Handle thread_group = create_initial_thread_group(CHECK); 3883 Universe::set_main_thread_group(thread_group()); 3884 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3885 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3886 main_thread->set_threadObj(thread_object); 3887 // Set thread status to running since main thread has 3888 // been started and running. 3889 java_lang_Thread::set_thread_status(thread_object, 3890 java_lang_Thread::RUNNABLE); 3891 3892 // The VM creates objects of this class. 3893 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3894 3895 // The VM preresolves methods to these classes. Make sure that they get initialized 3896 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3897 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3898 3899 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3900 call_initPhase1(CHECK); 3901 3902 // get the Java runtime name after java.lang.System is initialized 3903 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3904 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3905 3906 // an instance of OutOfMemory exception has been allocated earlier 3907 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3908 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3909 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3910 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3911 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3912 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3913 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3914 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3915 } 3916 3917 void Threads::initialize_jsr292_core_classes(TRAPS) { 3918 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3919 3920 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3921 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3922 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3923 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3924 } 3925 3926 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3927 extern void JDK_Version_init(); 3928 3929 // Preinitialize version info. 3930 VM_Version::early_initialize(); 3931 3932 // Check version 3933 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3934 3935 // Initialize library-based TLS 3936 ThreadLocalStorage::init(); 3937 3938 // Initialize the output stream module 3939 ostream_init(); 3940 3941 // Process java launcher properties. 3942 Arguments::process_sun_java_launcher_properties(args); 3943 3944 // Initialize the os module 3945 os::init(); 3946 3947 // Record VM creation timing statistics 3948 TraceVmCreationTime create_vm_timer; 3949 create_vm_timer.start(); 3950 3951 // Initialize system properties. 3952 Arguments::init_system_properties(); 3953 3954 // So that JDK version can be used as a discriminator when parsing arguments 3955 JDK_Version_init(); 3956 3957 // Update/Initialize System properties after JDK version number is known 3958 Arguments::init_version_specific_system_properties(); 3959 3960 // Make sure to initialize log configuration *before* parsing arguments 3961 LogConfiguration::initialize(create_vm_timer.begin_time()); 3962 3963 // Parse arguments 3964 // Note: this internally calls os::init_container_support() 3965 jint parse_result = Arguments::parse(args); 3966 if (parse_result != JNI_OK) return parse_result; 3967 3968 os::init_before_ergo(); 3969 3970 jint ergo_result = Arguments::apply_ergo(); 3971 if (ergo_result != JNI_OK) return ergo_result; 3972 3973 // Final check of all ranges after ergonomics which may change values. 3974 if (!CommandLineFlagRangeList::check_ranges()) { 3975 return JNI_EINVAL; 3976 } 3977 3978 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3979 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3980 if (!constraint_result) { 3981 return JNI_EINVAL; 3982 } 3983 3984 CommandLineFlagWriteableList::mark_startup(); 3985 3986 if (PauseAtStartup) { 3987 os::pause(); 3988 } 3989 3990 HOTSPOT_VM_INIT_BEGIN(); 3991 3992 // Timing (must come after argument parsing) 3993 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3994 3995 SafepointMechanism::initialize(); 3996 3997 // Initialize the os module after parsing the args 3998 jint os_init_2_result = os::init_2(); 3999 if (os_init_2_result != JNI_OK) return os_init_2_result; 4000 4001 jint adjust_after_os_result = Arguments::adjust_after_os(); 4002 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 4003 4004 // Initialize output stream logging 4005 ostream_init_log(); 4006 4007 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 4008 // Must be before create_vm_init_agents() 4009 if (Arguments::init_libraries_at_startup()) { 4010 convert_vm_init_libraries_to_agents(); 4011 } 4012 4013 // Launch -agentlib/-agentpath and converted -Xrun agents 4014 if (Arguments::init_agents_at_startup()) { 4015 create_vm_init_agents(); 4016 } 4017 4018 // Initialize Threads state 4019 _thread_list = NULL; 4020 _number_of_threads = 0; 4021 _number_of_non_daemon_threads = 0; 4022 4023 // Initialize global data structures and create system classes in heap 4024 vm_init_globals(); 4025 4026 #if INCLUDE_JVMCI 4027 if (JVMCICounterSize > 0) { 4028 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 4029 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 4030 } else { 4031 JavaThread::_jvmci_old_thread_counters = NULL; 4032 } 4033 #endif // INCLUDE_JVMCI 4034 4035 // Attach the main thread to this os thread 4036 JavaThread* main_thread = new JavaThread(); 4037 main_thread->set_thread_state(_thread_in_vm); 4038 main_thread->initialize_thread_current(); 4039 // must do this before set_active_handles 4040 main_thread->record_stack_base_and_size(); 4041 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 4042 4043 if (!main_thread->set_as_starting_thread()) { 4044 vm_shutdown_during_initialization( 4045 "Failed necessary internal allocation. Out of swap space"); 4046 main_thread->smr_delete(); 4047 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 4048 return JNI_ENOMEM; 4049 } 4050 4051 // Enable guard page *after* os::create_main_thread(), otherwise it would 4052 // crash Linux VM, see notes in os_linux.cpp. 4053 main_thread->create_stack_guard_pages(); 4054 4055 // Initialize Java-Level synchronization subsystem 4056 ObjectMonitor::Initialize(); 4057 4058 // Initialize global modules 4059 jint status = init_globals(); 4060 if (status != JNI_OK) { 4061 main_thread->smr_delete(); 4062 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 4063 return status; 4064 } 4065 4066 if (TRACE_INITIALIZE() != JNI_OK) { 4067 vm_exit_during_initialization("Failed to initialize tracing backend"); 4068 } 4069 4070 // Should be done after the heap is fully created 4071 main_thread->cache_global_variables(); 4072 4073 HandleMark hm; 4074 4075 { MutexLocker mu(Threads_lock); 4076 Threads::add(main_thread); 4077 } 4078 4079 // Any JVMTI raw monitors entered in onload will transition into 4080 // real raw monitor. VM is setup enough here for raw monitor enter. 4081 JvmtiExport::transition_pending_onload_raw_monitors(); 4082 4083 // Create the VMThread 4084 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 4085 4086 VMThread::create(); 4087 Thread* vmthread = VMThread::vm_thread(); 4088 4089 if (!os::create_thread(vmthread, os::vm_thread)) { 4090 vm_exit_during_initialization("Cannot create VM thread. " 4091 "Out of system resources."); 4092 } 4093 4094 // Wait for the VM thread to become ready, and VMThread::run to initialize 4095 // Monitors can have spurious returns, must always check another state flag 4096 { 4097 MutexLocker ml(Notify_lock); 4098 os::start_thread(vmthread); 4099 while (vmthread->active_handles() == NULL) { 4100 Notify_lock->wait(); 4101 } 4102 } 4103 } 4104 4105 assert(Universe::is_fully_initialized(), "not initialized"); 4106 if (VerifyDuringStartup) { 4107 // Make sure we're starting with a clean slate. 4108 VM_Verify verify_op; 4109 VMThread::execute(&verify_op); 4110 } 4111 4112 Thread* THREAD = Thread::current(); 4113 4114 // Always call even when there are not JVMTI environments yet, since environments 4115 // may be attached late and JVMTI must track phases of VM execution 4116 JvmtiExport::enter_early_start_phase(); 4117 4118 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4119 JvmtiExport::post_early_vm_start(); 4120 4121 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 4122 4123 // We need this for ClassDataSharing - the initial vm.info property is set 4124 // with the default value of CDS "sharing" which may be reset through 4125 // command line options. 4126 reset_vm_info_property(CHECK_JNI_ERR); 4127 4128 quicken_jni_functions(); 4129 4130 // No more stub generation allowed after that point. 4131 StubCodeDesc::freeze(); 4132 4133 // Set flag that basic initialization has completed. Used by exceptions and various 4134 // debug stuff, that does not work until all basic classes have been initialized. 4135 set_init_completed(); 4136 4137 LogConfiguration::post_initialize(); 4138 Metaspace::post_initialize(); 4139 4140 HOTSPOT_VM_INIT_END(); 4141 4142 // record VM initialization completion time 4143 #if INCLUDE_MANAGEMENT 4144 Management::record_vm_init_completed(); 4145 #endif // INCLUDE_MANAGEMENT 4146 4147 // Signal Dispatcher needs to be started before VMInit event is posted 4148 os::signal_init(CHECK_JNI_ERR); 4149 4150 // Start Attach Listener if +StartAttachListener or it can't be started lazily 4151 if (!DisableAttachMechanism) { 4152 AttachListener::vm_start(); 4153 if (StartAttachListener || AttachListener::init_at_startup()) { 4154 AttachListener::init(); 4155 } 4156 } 4157 4158 // Launch -Xrun agents 4159 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 4160 // back-end can launch with -Xdebug -Xrunjdwp. 4161 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 4162 create_vm_init_libraries(); 4163 } 4164 4165 if (CleanChunkPoolAsync) { 4166 Chunk::start_chunk_pool_cleaner_task(); 4167 } 4168 4169 // initialize compiler(s) 4170 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 4171 CompileBroker::compilation_init(CHECK_JNI_ERR); 4172 #endif 4173 4174 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4175 // It is done after compilers are initialized, because otherwise compilations of 4176 // signature polymorphic MH intrinsics can be missed 4177 // (see SystemDictionary::find_method_handle_intrinsic). 4178 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4179 4180 // This will initialize the module system. Only java.base classes can be 4181 // loaded until phase 2 completes 4182 call_initPhase2(CHECK_JNI_ERR); 4183 4184 // Always call even when there are not JVMTI environments yet, since environments 4185 // may be attached late and JVMTI must track phases of VM execution 4186 JvmtiExport::enter_start_phase(); 4187 4188 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4189 JvmtiExport::post_vm_start(); 4190 4191 // Final system initialization including security manager and system class loader 4192 call_initPhase3(CHECK_JNI_ERR); 4193 4194 // cache the system and platform class loaders 4195 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4196 4197 #if INCLUDE_JVMCI 4198 if (EnableJVMCI) { 4199 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 4200 // The JVMCI Java initialization code will read this flag and 4201 // do the printing if it's set. 4202 bool init = JVMCIPrintProperties; 4203 4204 if (!init) { 4205 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4206 // compilations via JVMCI will not actually block until JVMCI is initialized. 4207 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4208 } 4209 4210 if (init) { 4211 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 4212 } 4213 } 4214 #endif 4215 4216 // Always call even when there are not JVMTI environments yet, since environments 4217 // may be attached late and JVMTI must track phases of VM execution 4218 JvmtiExport::enter_live_phase(); 4219 4220 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4221 JvmtiExport::post_vm_initialized(); 4222 4223 if (TRACE_START() != JNI_OK) { 4224 vm_exit_during_initialization("Failed to start tracing backend."); 4225 } 4226 4227 #if INCLUDE_MANAGEMENT 4228 Management::initialize(THREAD); 4229 4230 if (HAS_PENDING_EXCEPTION) { 4231 // management agent fails to start possibly due to 4232 // configuration problem and is responsible for printing 4233 // stack trace if appropriate. Simply exit VM. 4234 vm_exit(1); 4235 } 4236 #endif // INCLUDE_MANAGEMENT 4237 4238 if (MemProfiling) MemProfiler::engage(); 4239 StatSampler::engage(); 4240 if (CheckJNICalls) JniPeriodicChecker::engage(); 4241 4242 BiasedLocking::init(); 4243 4244 #if INCLUDE_RTM_OPT 4245 RTMLockingCounters::init(); 4246 #endif 4247 4248 if (JDK_Version::current().post_vm_init_hook_enabled()) { 4249 call_postVMInitHook(THREAD); 4250 // The Java side of PostVMInitHook.run must deal with all 4251 // exceptions and provide means of diagnosis. 4252 if (HAS_PENDING_EXCEPTION) { 4253 CLEAR_PENDING_EXCEPTION; 4254 } 4255 } 4256 4257 { 4258 MutexLocker ml(PeriodicTask_lock); 4259 // Make sure the WatcherThread can be started by WatcherThread::start() 4260 // or by dynamic enrollment. 4261 WatcherThread::make_startable(); 4262 // Start up the WatcherThread if there are any periodic tasks 4263 // NOTE: All PeriodicTasks should be registered by now. If they 4264 // aren't, late joiners might appear to start slowly (we might 4265 // take a while to process their first tick). 4266 if (PeriodicTask::num_tasks() > 0) { 4267 WatcherThread::start(); 4268 } 4269 } 4270 4271 create_vm_timer.end(); 4272 #ifdef ASSERT 4273 _vm_complete = true; 4274 #endif 4275 4276 if (DumpSharedSpaces) { 4277 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4278 ShouldNotReachHere(); 4279 } 4280 4281 return JNI_OK; 4282 } 4283 4284 // type for the Agent_OnLoad and JVM_OnLoad entry points 4285 extern "C" { 4286 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4287 } 4288 // Find a command line agent library and return its entry point for 4289 // -agentlib: -agentpath: -Xrun 4290 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4291 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4292 const char *on_load_symbols[], 4293 size_t num_symbol_entries) { 4294 OnLoadEntry_t on_load_entry = NULL; 4295 void *library = NULL; 4296 4297 if (!agent->valid()) { 4298 char buffer[JVM_MAXPATHLEN]; 4299 char ebuf[1024] = ""; 4300 const char *name = agent->name(); 4301 const char *msg = "Could not find agent library "; 4302 4303 // First check to see if agent is statically linked into executable 4304 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4305 library = agent->os_lib(); 4306 } else if (agent->is_absolute_path()) { 4307 library = os::dll_load(name, ebuf, sizeof ebuf); 4308 if (library == NULL) { 4309 const char *sub_msg = " in absolute path, with error: "; 4310 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4311 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4312 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4313 // If we can't find the agent, exit. 4314 vm_exit_during_initialization(buf, NULL); 4315 FREE_C_HEAP_ARRAY(char, buf); 4316 } 4317 } else { 4318 // Try to load the agent from the standard dll directory 4319 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4320 name)) { 4321 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4322 } 4323 if (library == NULL) { // Try the library path directory. 4324 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4325 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4326 } 4327 if (library == NULL) { 4328 const char *sub_msg = " on the library path, with error: "; 4329 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4330 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4331 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4332 // If we can't find the agent, exit. 4333 vm_exit_during_initialization(buf, NULL); 4334 FREE_C_HEAP_ARRAY(char, buf); 4335 } 4336 } 4337 } 4338 agent->set_os_lib(library); 4339 agent->set_valid(); 4340 } 4341 4342 // Find the OnLoad function. 4343 on_load_entry = 4344 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4345 false, 4346 on_load_symbols, 4347 num_symbol_entries)); 4348 return on_load_entry; 4349 } 4350 4351 // Find the JVM_OnLoad entry point 4352 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4353 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4354 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4355 } 4356 4357 // Find the Agent_OnLoad entry point 4358 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4359 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4360 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4361 } 4362 4363 // For backwards compatibility with -Xrun 4364 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4365 // treated like -agentpath: 4366 // Must be called before agent libraries are created 4367 void Threads::convert_vm_init_libraries_to_agents() { 4368 AgentLibrary* agent; 4369 AgentLibrary* next; 4370 4371 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4372 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4373 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4374 4375 // If there is an JVM_OnLoad function it will get called later, 4376 // otherwise see if there is an Agent_OnLoad 4377 if (on_load_entry == NULL) { 4378 on_load_entry = lookup_agent_on_load(agent); 4379 if (on_load_entry != NULL) { 4380 // switch it to the agent list -- so that Agent_OnLoad will be called, 4381 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4382 Arguments::convert_library_to_agent(agent); 4383 } else { 4384 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4385 } 4386 } 4387 } 4388 } 4389 4390 // Create agents for -agentlib: -agentpath: and converted -Xrun 4391 // Invokes Agent_OnLoad 4392 // Called very early -- before JavaThreads exist 4393 void Threads::create_vm_init_agents() { 4394 extern struct JavaVM_ main_vm; 4395 AgentLibrary* agent; 4396 4397 JvmtiExport::enter_onload_phase(); 4398 4399 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4400 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4401 4402 if (on_load_entry != NULL) { 4403 // Invoke the Agent_OnLoad function 4404 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4405 if (err != JNI_OK) { 4406 vm_exit_during_initialization("agent library failed to init", agent->name()); 4407 } 4408 } else { 4409 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4410 } 4411 } 4412 JvmtiExport::enter_primordial_phase(); 4413 } 4414 4415 extern "C" { 4416 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4417 } 4418 4419 void Threads::shutdown_vm_agents() { 4420 // Send any Agent_OnUnload notifications 4421 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4422 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4423 extern struct JavaVM_ main_vm; 4424 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4425 4426 // Find the Agent_OnUnload function. 4427 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4428 os::find_agent_function(agent, 4429 false, 4430 on_unload_symbols, 4431 num_symbol_entries)); 4432 4433 // Invoke the Agent_OnUnload function 4434 if (unload_entry != NULL) { 4435 JavaThread* thread = JavaThread::current(); 4436 ThreadToNativeFromVM ttn(thread); 4437 HandleMark hm(thread); 4438 (*unload_entry)(&main_vm); 4439 } 4440 } 4441 } 4442 4443 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4444 // Invokes JVM_OnLoad 4445 void Threads::create_vm_init_libraries() { 4446 extern struct JavaVM_ main_vm; 4447 AgentLibrary* agent; 4448 4449 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4450 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4451 4452 if (on_load_entry != NULL) { 4453 // Invoke the JVM_OnLoad function 4454 JavaThread* thread = JavaThread::current(); 4455 ThreadToNativeFromVM ttn(thread); 4456 HandleMark hm(thread); 4457 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4458 if (err != JNI_OK) { 4459 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4460 } 4461 } else { 4462 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4463 } 4464 } 4465 } 4466 4467 4468 // Last thread running calls java.lang.Shutdown.shutdown() 4469 void JavaThread::invoke_shutdown_hooks() { 4470 HandleMark hm(this); 4471 4472 // We could get here with a pending exception, if so clear it now. 4473 if (this->has_pending_exception()) { 4474 this->clear_pending_exception(); 4475 } 4476 4477 EXCEPTION_MARK; 4478 Klass* shutdown_klass = 4479 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4480 THREAD); 4481 if (shutdown_klass != NULL) { 4482 // SystemDictionary::resolve_or_null will return null if there was 4483 // an exception. If we cannot load the Shutdown class, just don't 4484 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4485 // and finalizers (if runFinalizersOnExit is set) won't be run. 4486 // Note that if a shutdown hook was registered or runFinalizersOnExit 4487 // was called, the Shutdown class would have already been loaded 4488 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4489 JavaValue result(T_VOID); 4490 JavaCalls::call_static(&result, 4491 shutdown_klass, 4492 vmSymbols::shutdown_method_name(), 4493 vmSymbols::void_method_signature(), 4494 THREAD); 4495 } 4496 CLEAR_PENDING_EXCEPTION; 4497 } 4498 4499 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4500 // the program falls off the end of main(). Another VM exit path is through 4501 // vm_exit() when the program calls System.exit() to return a value or when 4502 // there is a serious error in VM. The two shutdown paths are not exactly 4503 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4504 // and VM_Exit op at VM level. 4505 // 4506 // Shutdown sequence: 4507 // + Shutdown native memory tracking if it is on 4508 // + Wait until we are the last non-daemon thread to execute 4509 // <-- every thing is still working at this moment --> 4510 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4511 // shutdown hooks, run finalizers if finalization-on-exit 4512 // + Call before_exit(), prepare for VM exit 4513 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4514 // currently the only user of this mechanism is File.deleteOnExit()) 4515 // > stop StatSampler, watcher thread, CMS threads, 4516 // post thread end and vm death events to JVMTI, 4517 // stop signal thread 4518 // + Call JavaThread::exit(), it will: 4519 // > release JNI handle blocks, remove stack guard pages 4520 // > remove this thread from Threads list 4521 // <-- no more Java code from this thread after this point --> 4522 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4523 // the compiler threads at safepoint 4524 // <-- do not use anything that could get blocked by Safepoint --> 4525 // + Disable tracing at JNI/JVM barriers 4526 // + Set _vm_exited flag for threads that are still running native code 4527 // + Delete this thread 4528 // + Call exit_globals() 4529 // > deletes tty 4530 // > deletes PerfMemory resources 4531 // + Return to caller 4532 4533 bool Threads::destroy_vm() { 4534 JavaThread* thread = JavaThread::current(); 4535 4536 #ifdef ASSERT 4537 _vm_complete = false; 4538 #endif 4539 // Wait until we are the last non-daemon thread to execute 4540 { MutexLocker nu(Threads_lock); 4541 while (Threads::number_of_non_daemon_threads() > 1) 4542 // This wait should make safepoint checks, wait without a timeout, 4543 // and wait as a suspend-equivalent condition. 4544 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4545 Mutex::_as_suspend_equivalent_flag); 4546 } 4547 4548 // Hang forever on exit if we are reporting an error. 4549 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4550 os::infinite_sleep(); 4551 } 4552 os::wait_for_keypress_at_exit(); 4553 4554 // run Java level shutdown hooks 4555 thread->invoke_shutdown_hooks(); 4556 4557 before_exit(thread); 4558 4559 thread->exit(true); 4560 4561 // Stop VM thread. 4562 { 4563 // 4945125 The vm thread comes to a safepoint during exit. 4564 // GC vm_operations can get caught at the safepoint, and the 4565 // heap is unparseable if they are caught. Grab the Heap_lock 4566 // to prevent this. The GC vm_operations will not be able to 4567 // queue until after the vm thread is dead. After this point, 4568 // we'll never emerge out of the safepoint before the VM exits. 4569 4570 MutexLocker ml(Heap_lock); 4571 4572 VMThread::wait_for_vm_thread_exit(); 4573 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4574 VMThread::destroy(); 4575 } 4576 4577 // clean up ideal graph printers 4578 #if defined(COMPILER2) && !defined(PRODUCT) 4579 IdealGraphPrinter::clean_up(); 4580 #endif 4581 4582 // Now, all Java threads are gone except daemon threads. Daemon threads 4583 // running Java code or in VM are stopped by the Safepoint. However, 4584 // daemon threads executing native code are still running. But they 4585 // will be stopped at native=>Java/VM barriers. Note that we can't 4586 // simply kill or suspend them, as it is inherently deadlock-prone. 4587 4588 VM_Exit::set_vm_exited(); 4589 4590 notify_vm_shutdown(); 4591 4592 // We are after VM_Exit::set_vm_exited() so we can't call 4593 // thread->smr_delete() or we will block on the Threads_lock. 4594 // Deleting the shutdown thread here is safe because another 4595 // JavaThread cannot have an active ThreadsListHandle for 4596 // this JavaThread. 4597 delete thread; 4598 4599 #if INCLUDE_JVMCI 4600 if (JVMCICounterSize > 0) { 4601 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4602 } 4603 #endif 4604 4605 // exit_globals() will delete tty 4606 exit_globals(); 4607 4608 LogConfiguration::finalize(); 4609 4610 return true; 4611 } 4612 4613 4614 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4615 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4616 return is_supported_jni_version(version); 4617 } 4618 4619 4620 jboolean Threads::is_supported_jni_version(jint version) { 4621 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4622 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4623 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4624 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4625 if (version == JNI_VERSION_9) return JNI_TRUE; 4626 if (version == JNI_VERSION_10) return JNI_TRUE; 4627 return JNI_FALSE; 4628 } 4629 4630 // Hash table of pointers found by a scan. Used for collecting hazard 4631 // pointers (ThreadsList references). Also used for collecting JavaThreads 4632 // that are indirectly referenced by hazard ptrs. An instance of this 4633 // class only contains one type of pointer. 4634 // 4635 class ThreadScanHashtable : public CHeapObj<mtThread> { 4636 private: 4637 static bool ptr_equals(void * const& s1, void * const& s2) { 4638 return s1 == s2; 4639 } 4640 4641 static unsigned int ptr_hash(void * const& s1) { 4642 return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u); 4643 } 4644 4645 int _table_size; 4646 // ResourceHashtable SIZE is specified at compile time so our 4647 // dynamic _table_size is unused for now; 1031 is the first prime 4648 // after 1024. 4649 typedef ResourceHashtable<void *, int, &ThreadScanHashtable::ptr_hash, 4650 &ThreadScanHashtable::ptr_equals, 1031, 4651 ResourceObj::C_HEAP, mtThread> PtrTable; 4652 PtrTable * _ptrs; 4653 4654 public: 4655 // ResourceHashtable is passed to various functions and populated in 4656 // different places so we allocate it using C_HEAP to make it immune 4657 // from any ResourceMarks that happen to be in the code paths. 4658 ThreadScanHashtable(int table_size) : _table_size(table_size), _ptrs(new (ResourceObj::C_HEAP, mtThread) PtrTable()) {} 4659 4660 ~ThreadScanHashtable() { delete _ptrs; } 4661 4662 bool has_entry(void *pointer) { 4663 int *val_ptr = _ptrs->get(pointer); 4664 return val_ptr != NULL && *val_ptr == 1; 4665 } 4666 4667 void add_entry(void *pointer) { 4668 _ptrs->put(pointer, 1); 4669 } 4670 }; 4671 4672 // Closure to gather JavaThreads indirectly referenced by hazard ptrs 4673 // (ThreadsList references) into a hash table. This closure handles part 2 4674 // of the dance - adding all the JavaThreads referenced by the hazard 4675 // pointer (ThreadsList reference) to the hash table. 4676 // 4677 class AddThreadHazardPointerThreadClosure : public ThreadClosure { 4678 private: 4679 ThreadScanHashtable *_table; 4680 4681 public: 4682 AddThreadHazardPointerThreadClosure(ThreadScanHashtable *table) : _table(table) {} 4683 4684 virtual void do_thread(Thread *thread) { 4685 if (!_table->has_entry((void*)thread)) { 4686 // The same JavaThread might be on more than one ThreadsList or 4687 // more than one thread might be using the same ThreadsList. In 4688 // either case, we only need a single entry for a JavaThread. 4689 _table->add_entry((void*)thread); 4690 } 4691 } 4692 }; 4693 4694 // Closure to gather JavaThreads indirectly referenced by hazard ptrs 4695 // (ThreadsList references) into a hash table. This closure handles part 1 4696 // of the dance - hazard ptr chain walking and dispatch to another 4697 // closure. 4698 // 4699 class ScanHazardPtrGatherProtectedThreadsClosure : public ThreadClosure { 4700 private: 4701 ThreadScanHashtable *_table; 4702 public: 4703 ScanHazardPtrGatherProtectedThreadsClosure(ThreadScanHashtable *table) : _table(table) {} 4704 4705 virtual void do_thread(Thread *thread) { 4706 assert_locked_or_safepoint(Threads_lock); 4707 4708 if (thread == NULL) return; 4709 4710 // This code races with Threads::acquire_stable_list() which is 4711 // lock-free so we have to handle some special situations. 4712 // 4713 ThreadsList *current_list = NULL; 4714 while (true) { 4715 current_list = thread->get_threads_hazard_ptr(); 4716 // No hazard ptr so nothing more to do. 4717 if (current_list == NULL) { 4718 assert(thread->get_nested_threads_hazard_ptr() == NULL, 4719 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 4720 return; 4721 } 4722 4723 // If the hazard ptr is verified as stable (since it is not tagged), 4724 // then it is safe to use. 4725 if (!Thread::is_hazard_ptr_tagged(current_list)) break; 4726 4727 // The hazard ptr is tagged as not yet verified as being stable 4728 // so we are racing with acquire_stable_list(). This exchange 4729 // attempts to invalidate the hazard ptr. If we win the race, 4730 // then we can ignore this unstable hazard ptr and the other 4731 // thread will retry the attempt to publish a stable hazard ptr. 4732 // If we lose the race, then we retry our attempt to look at the 4733 // hazard ptr. 4734 if (thread->cmpxchg_threads_hazard_ptr(NULL, current_list) == current_list) return; 4735 } 4736 4737 // The current JavaThread has a hazard ptr (ThreadsList reference) 4738 // which might be _smr_java_thread_list or it might be an older 4739 // ThreadsList that has been removed but not freed. In either case, 4740 // the hazard ptr is protecting all the JavaThreads on that 4741 // ThreadsList. 4742 AddThreadHazardPointerThreadClosure add_cl(_table); 4743 current_list->threads_do(&add_cl); 4744 4745 // Any NestedThreadsLists are also protecting JavaThreads so 4746 // gather those also; the ThreadsLists may be different. 4747 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); 4748 node != NULL; node = node->next()) { 4749 node->t_list()->threads_do(&add_cl); 4750 } 4751 } 4752 }; 4753 4754 // Closure to print JavaThreads that have a hazard ptr (ThreadsList 4755 // reference) that contains an indirect reference to a specific JavaThread. 4756 // 4757 class ScanHazardPtrPrintMatchingThreadsClosure : public ThreadClosure { 4758 private: 4759 JavaThread *_thread; 4760 public: 4761 ScanHazardPtrPrintMatchingThreadsClosure(JavaThread *thread) : _thread(thread) {} 4762 4763 virtual void do_thread(Thread *thread) { 4764 assert_locked_or_safepoint(Threads_lock); 4765 4766 if (thread == NULL) return; 4767 ThreadsList *current_list = thread->get_threads_hazard_ptr(); 4768 if (current_list == NULL) { 4769 assert(thread->get_nested_threads_hazard_ptr() == NULL, 4770 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 4771 return; 4772 } 4773 // If the hazard ptr is unverified, then ignore it. 4774 if (Thread::is_hazard_ptr_tagged(current_list)) return; 4775 4776 // The current JavaThread has a hazard ptr (ThreadsList reference) 4777 // which might be _smr_java_thread_list or it might be an older 4778 // ThreadsList that has been removed but not freed. In either case, 4779 // the hazard ptr is protecting all the JavaThreads on that 4780 // ThreadsList, but we only care about matching a specific JavaThread. 4781 DO_JAVA_THREADS(current_list, p) { 4782 if (p == _thread) { 4783 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread)); 4784 break; 4785 } 4786 } 4787 4788 // Any NestedThreadsLists are also protecting JavaThreads so 4789 // check those also; the ThreadsLists may be different. 4790 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); 4791 node != NULL; node = node->next()) { 4792 DO_JAVA_THREADS(node->t_list(), p) { 4793 if (p == _thread) { 4794 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread1=" INTPTR_FORMAT " has a nested hazard pointer for thread2=" INTPTR_FORMAT, os::current_thread_id(), p2i(thread), p2i(_thread)); 4795 return; 4796 } 4797 } 4798 } 4799 } 4800 }; 4801 4802 // Return true if the specified JavaThread is protected by a hazard 4803 // pointer (ThreadsList reference). Otherwise, returns false. 4804 // 4805 bool Threads::is_a_protected_JavaThread(JavaThread *thread) { 4806 assert_locked_or_safepoint(Threads_lock); 4807 4808 // Hash table size should be first power of two higher than twice 4809 // the length of the Threads list. 4810 int hash_table_size = MIN2(_number_of_threads, 32) << 1; 4811 hash_table_size--; 4812 hash_table_size |= hash_table_size >> 1; 4813 hash_table_size |= hash_table_size >> 2; 4814 hash_table_size |= hash_table_size >> 4; 4815 hash_table_size |= hash_table_size >> 8; 4816 hash_table_size |= hash_table_size >> 16; 4817 hash_table_size++; 4818 4819 // Gather a hash table of the JavaThreads indirectly referenced by 4820 // hazard ptrs. 4821 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size); 4822 ScanHazardPtrGatherProtectedThreadsClosure scan_cl(scan_table); 4823 Threads::threads_do(&scan_cl); 4824 4825 bool thread_is_protected = false; 4826 if (scan_table->has_entry((void*)thread)) { 4827 thread_is_protected = true; 4828 } 4829 delete scan_table; 4830 return thread_is_protected; 4831 } 4832 4833 // Safely delete a JavaThread when it is no longer in use by a 4834 // ThreadsListHandle. 4835 // 4836 void Threads::smr_delete(JavaThread *thread) { 4837 assert(!Threads_lock->owned_by_self(), "sanity"); 4838 4839 bool has_logged_once = false; 4840 elapsedTimer timer; 4841 if (EnableThreadSMRStatistics) { 4842 timer.start(); 4843 } 4844 4845 while (true) { 4846 { 4847 // No safepoint check because this JavaThread is not on the 4848 // Threads list. 4849 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 4850 // Cannot use a MonitorLockerEx helper here because we have 4851 // to drop the Threads_lock first if we wait. 4852 Threads::smr_delete_lock()->lock_without_safepoint_check(); 4853 // Set the smr_delete_notify flag after we grab smr_delete_lock 4854 // and before we scan hazard ptrs because we're doing 4855 // double-check locking in release_stable_list(). 4856 Threads::set_smr_delete_notify(); 4857 4858 if (!is_a_protected_JavaThread(thread)) { 4859 // This is the common case. 4860 Threads::clear_smr_delete_notify(); 4861 Threads::smr_delete_lock()->unlock(); 4862 break; 4863 } 4864 if (!has_logged_once) { 4865 has_logged_once = true; 4866 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is not deleted.", os::current_thread_id(), p2i(thread)); 4867 if (log_is_enabled(Debug, os, thread)) { 4868 ScanHazardPtrPrintMatchingThreadsClosure scan_cl(thread); 4869 Threads::threads_do(&scan_cl); 4870 } 4871 } 4872 } // We have to drop the Threads_lock to wait or delete the thread 4873 4874 if (EnableThreadSMRStatistics) { 4875 _smr_delete_lock_wait_cnt++; 4876 if (_smr_delete_lock_wait_cnt > _smr_delete_lock_wait_max) { 4877 _smr_delete_lock_wait_max = _smr_delete_lock_wait_cnt; 4878 } 4879 } 4880 // Wait for a release_stable_list() call before we check again. No 4881 // safepoint check, no timeout, and not as suspend equivalent flag 4882 // because this JavaThread is not on the Threads list. 4883 Threads::smr_delete_lock()->wait(Mutex::_no_safepoint_check_flag, 0, 4884 !Mutex::_as_suspend_equivalent_flag); 4885 if (EnableThreadSMRStatistics) { 4886 _smr_delete_lock_wait_cnt--; 4887 } 4888 4889 Threads::clear_smr_delete_notify(); 4890 Threads::smr_delete_lock()->unlock(); 4891 // Retry the whole scenario. 4892 } 4893 4894 // If someone set a handshake on us just as we entered exit path, we simple cancel it. 4895 if (ThreadLocalHandshakes) { 4896 thread->cancel_handshake(); 4897 } 4898 4899 delete thread; 4900 if (EnableThreadSMRStatistics) { 4901 timer.stop(); 4902 uint millis = (uint)timer.milliseconds(); 4903 Threads::inc_smr_deleted_thread_cnt(); 4904 Threads::add_smr_deleted_thread_times(millis); 4905 Threads::update_smr_deleted_thread_time_max(millis); 4906 } 4907 4908 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_delete: thread=" INTPTR_FORMAT " is deleted.", os::current_thread_id(), p2i(thread)); 4909 } 4910 4911 bool Threads::smr_delete_notify() { 4912 // Use load_acquire() in order to see any updates to _smr_delete_notify 4913 // earlier than when smr_delete_lock is grabbed. 4914 return (OrderAccess::load_acquire(&_smr_delete_notify) != 0); 4915 } 4916 4917 // set_smr_delete_notify() and clear_smr_delete_notify() are called 4918 // under the protection of the smr_delete_lock, but we also use an 4919 // Atomic operation to ensure the memory update is seen earlier than 4920 // when the smr_delete_lock is dropped. 4921 // 4922 void Threads::set_smr_delete_notify() { 4923 Atomic::inc(&_smr_delete_notify); 4924 } 4925 4926 void Threads::clear_smr_delete_notify() { 4927 Atomic::dec(&_smr_delete_notify); 4928 } 4929 4930 // Closure to gather hazard ptrs (ThreadsList references) into a hash table. 4931 // 4932 class ScanHazardPtrGatherThreadsListClosure : public ThreadClosure { 4933 private: 4934 ThreadScanHashtable *_table; 4935 public: 4936 ScanHazardPtrGatherThreadsListClosure(ThreadScanHashtable *table) : _table(table) {} 4937 4938 virtual void do_thread(Thread* thread) { 4939 assert_locked_or_safepoint(Threads_lock); 4940 4941 if (thread == NULL) return; 4942 ThreadsList *threads = thread->get_threads_hazard_ptr(); 4943 if (threads == NULL) { 4944 assert(thread->get_nested_threads_hazard_ptr() == NULL, 4945 "cannot have a nested hazard ptr with a NULL regular hazard ptr"); 4946 return; 4947 } 4948 // In this closure we always ignore the tag that might mark this 4949 // hazard ptr as not yet verified. If we happen to catch an 4950 // unverified hazard ptr that is subsequently discarded (not 4951 // published), then the only side effect is that we might keep a 4952 // to-be-deleted ThreadsList alive a little longer. 4953 threads = Thread::untag_hazard_ptr(threads); 4954 if (!_table->has_entry((void*)threads)) { 4955 _table->add_entry((void*)threads); 4956 } 4957 4958 // Any NestedThreadsLists are also protecting JavaThreads so 4959 // gather those also; the ThreadsLists may be different. 4960 for (NestedThreadsList* node = thread->get_nested_threads_hazard_ptr(); 4961 node != NULL; node = node->next()) { 4962 threads = node->t_list(); 4963 if (!_table->has_entry((void*)threads)) { 4964 _table->add_entry((void*)threads); 4965 } 4966 } 4967 } 4968 }; 4969 4970 // Safely free a ThreadsList after a Threads::add() or Threads::remove(). 4971 // The specified ThreadsList may not get deleted during this call if it 4972 // is still in-use (referenced by a hazard ptr). Other ThreadsLists 4973 // in the chain may get deleted by this call if they are no longer in-use. 4974 void Threads::smr_free_list(ThreadsList* threads) { 4975 assert_locked_or_safepoint(Threads_lock); 4976 4977 threads->set_next_list(_smr_to_delete_list); 4978 _smr_to_delete_list = threads; 4979 if (EnableThreadSMRStatistics) { 4980 _smr_to_delete_list_cnt++; 4981 if (_smr_to_delete_list_cnt > _smr_to_delete_list_max) { 4982 _smr_to_delete_list_max = _smr_to_delete_list_cnt; 4983 } 4984 } 4985 4986 // Hash table size should be first power of two higher than twice the length of the ThreadsList 4987 int hash_table_size = MIN2(_number_of_threads, 32) << 1; 4988 hash_table_size--; 4989 hash_table_size |= hash_table_size >> 1; 4990 hash_table_size |= hash_table_size >> 2; 4991 hash_table_size |= hash_table_size >> 4; 4992 hash_table_size |= hash_table_size >> 8; 4993 hash_table_size |= hash_table_size >> 16; 4994 hash_table_size++; 4995 4996 // Gather a hash table of the current hazard ptrs: 4997 ThreadScanHashtable *scan_table = new ThreadScanHashtable(hash_table_size); 4998 ScanHazardPtrGatherThreadsListClosure scan_cl(scan_table); 4999 Threads::threads_do(&scan_cl); 5000 5001 // Walk through the linked list of pending freeable ThreadsLists 5002 // and free the ones that are not referenced from hazard ptrs. 5003 ThreadsList* current = _smr_to_delete_list; 5004 ThreadsList* prev = NULL; 5005 ThreadsList* next = NULL; 5006 bool threads_is_freed = false; 5007 while (current != NULL) { 5008 next = current->next_list(); 5009 if (!scan_table->has_entry((void*)current)) { 5010 // This ThreadsList is not referenced by a hazard ptr. 5011 if (prev != NULL) { 5012 prev->set_next_list(next); 5013 } 5014 if (_smr_to_delete_list == current) { 5015 _smr_to_delete_list = next; 5016 } 5017 5018 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is freed.", os::current_thread_id(), p2i(current)); 5019 if (current == threads) threads_is_freed = true; 5020 delete current; 5021 if (EnableThreadSMRStatistics) { 5022 _smr_java_thread_list_free_cnt++; 5023 _smr_to_delete_list_cnt--; 5024 } 5025 } else { 5026 prev = current; 5027 } 5028 current = next; 5029 } 5030 5031 if (!threads_is_freed) { 5032 // Only report "is not freed" on the original call to 5033 // smr_free_list() for this ThreadsList. 5034 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::smr_free_list: threads=" INTPTR_FORMAT " is not freed.", os::current_thread_id(), p2i(threads)); 5035 } 5036 5037 delete scan_table; 5038 } 5039 5040 // Remove a JavaThread from a ThreadsList. The returned ThreadsList is a 5041 // new copy of the specified ThreadsList with the specified JavaThread 5042 // removed. 5043 ThreadsList *ThreadsList::remove_thread(ThreadsList* list, JavaThread* java_thread) { 5044 assert(list->_length > 0, "sanity"); 5045 5046 uint i = 0; 5047 DO_JAVA_THREADS(list, current) { 5048 if (current == java_thread) { 5049 break; 5050 } 5051 i++; 5052 } 5053 assert(i < list->_length, "did not find JavaThread on the list"); 5054 const uint index = i; 5055 const uint new_length = list->_length - 1; 5056 const uint head_length = index; 5057 const uint tail_length = (new_length >= index) ? (new_length - index) : 0; 5058 ThreadsList *const new_list = new ThreadsList(new_length); 5059 5060 if (head_length > 0) { 5061 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length); 5062 } 5063 if (tail_length > 0) { 5064 Copy::disjoint_words((HeapWord*)list->_threads + index + 1, (HeapWord*)new_list->_threads + index, tail_length); 5065 } 5066 5067 return new_list; 5068 } 5069 5070 // Add a JavaThread to a ThreadsList. The returned ThreadsList is a 5071 // new copy of the specified ThreadsList with the specified JavaThread 5072 // appended to the end. 5073 ThreadsList *ThreadsList::add_thread(ThreadsList *list, JavaThread *java_thread) { 5074 const uint index = list->_length; 5075 const uint new_length = index + 1; 5076 const uint head_length = index; 5077 ThreadsList *const new_list = new ThreadsList(new_length); 5078 5079 if (head_length > 0) { 5080 Copy::disjoint_words((HeapWord*)list->_threads, (HeapWord*)new_list->_threads, head_length); 5081 } 5082 *(JavaThread**)(new_list->_threads + index) = java_thread; 5083 5084 return new_list; 5085 } 5086 5087 int ThreadsList::find_index_of_JavaThread(JavaThread *target) { 5088 if (target == NULL) { 5089 return -1; 5090 } 5091 for (uint i = 0; i < length(); i++) { 5092 if (target == thread_at(i)) { 5093 return (int)i; 5094 } 5095 } 5096 return -1; 5097 } 5098 5099 JavaThread* ThreadsList::find_JavaThread_from_java_tid(jlong java_tid) const { 5100 DO_JAVA_THREADS(this, thread) { 5101 oop tobj = thread->threadObj(); 5102 // Ignore the thread if it hasn't run yet, has exited 5103 // or is starting to exit. 5104 if (tobj != NULL && !thread->is_exiting() && 5105 java_tid == java_lang_Thread::thread_id(tobj)) { 5106 // found a match 5107 return thread; 5108 } 5109 } 5110 return NULL; 5111 } 5112 5113 bool ThreadsList::includes(const JavaThread * const p) const { 5114 if (p == NULL) { 5115 return false; 5116 } 5117 DO_JAVA_THREADS(this, q) { 5118 if (q == p) { 5119 return true; 5120 } 5121 } 5122 return false; 5123 } 5124 5125 void Threads::add(JavaThread* p, bool force_daemon) { 5126 // The threads lock must be owned at this point 5127 assert_locked_or_safepoint(Threads_lock); 5128 5129 // See the comment for this method in thread.hpp for its purpose and 5130 // why it is called here. 5131 p->initialize_queues(); 5132 p->set_next(_thread_list); 5133 _thread_list = p; 5134 5135 // Once a JavaThread is added to the Threads list, smr_delete() has 5136 // to be used to delete it. Otherwise we can just delete it directly. 5137 p->set_on_thread_list(); 5138 5139 _number_of_threads++; 5140 oop threadObj = p->threadObj(); 5141 bool daemon = true; 5142 // Bootstrapping problem: threadObj can be null for initial 5143 // JavaThread (or for threads attached via JNI) 5144 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 5145 _number_of_non_daemon_threads++; 5146 daemon = false; 5147 } 5148 5149 ThreadService::add_thread(p, daemon); 5150 5151 // Maintain fast thread list 5152 ThreadsList *new_list = ThreadsList::add_thread(get_smr_java_thread_list(), p); 5153 if (EnableThreadSMRStatistics) { 5154 _smr_java_thread_list_alloc_cnt++; 5155 if (new_list->length() > _smr_java_thread_list_max) { 5156 _smr_java_thread_list_max = new_list->length(); 5157 } 5158 } 5159 // Initial _smr_java_thread_list will not generate a "Threads::add" mesg. 5160 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::add: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); 5161 5162 ThreadsList *old_list = xchg_smr_java_thread_list(new_list); 5163 smr_free_list(old_list); 5164 5165 // Possible GC point. 5166 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 5167 } 5168 5169 void Threads::remove(JavaThread* p) { 5170 5171 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 5172 ObjectSynchronizer::omFlush(p); 5173 5174 // Extra scope needed for Thread_lock, so we can check 5175 // that we do not remove thread without safepoint code notice 5176 { MutexLocker ml(Threads_lock); 5177 5178 assert(get_smr_java_thread_list()->includes(p), "p must be present"); 5179 5180 // Maintain fast thread list 5181 ThreadsList *new_list = ThreadsList::remove_thread(get_smr_java_thread_list(), p); 5182 if (EnableThreadSMRStatistics) { 5183 _smr_java_thread_list_alloc_cnt++; 5184 // This list is smaller so no need to check for a "longest" update. 5185 } 5186 5187 // Final _smr_java_thread_list will not generate a "Threads::remove" mesg. 5188 log_debug(thread, smr)("tid=" UINTX_FORMAT ": Threads::remove: new ThreadsList=" INTPTR_FORMAT, os::current_thread_id(), p2i(new_list)); 5189 5190 ThreadsList *old_list = xchg_smr_java_thread_list(new_list); 5191 smr_free_list(old_list); 5192 5193 JavaThread* current = _thread_list; 5194 JavaThread* prev = NULL; 5195 5196 while (current != p) { 5197 prev = current; 5198 current = current->next(); 5199 } 5200 5201 if (prev) { 5202 prev->set_next(current->next()); 5203 } else { 5204 _thread_list = p->next(); 5205 } 5206 5207 _number_of_threads--; 5208 oop threadObj = p->threadObj(); 5209 bool daemon = true; 5210 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 5211 _number_of_non_daemon_threads--; 5212 daemon = false; 5213 5214 // Only one thread left, do a notify on the Threads_lock so a thread waiting 5215 // on destroy_vm will wake up. 5216 if (number_of_non_daemon_threads() == 1) { 5217 Threads_lock->notify_all(); 5218 } 5219 } 5220 ThreadService::remove_thread(p, daemon); 5221 5222 // Make sure that safepoint code disregard this thread. This is needed since 5223 // the thread might mess around with locks after this point. This can cause it 5224 // to do callbacks into the safepoint code. However, the safepoint code is not aware 5225 // of this thread since it is removed from the queue. 5226 p->set_terminated_value(); 5227 } // unlock Threads_lock 5228 5229 // Since Events::log uses a lock, we grab it outside the Threads_lock 5230 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 5231 } 5232 5233 // Operations on the Threads list for GC. These are not explicitly locked, 5234 // but the garbage collector must provide a safe context for them to run. 5235 // In particular, these things should never be called when the Threads_lock 5236 // is held by some other thread. (Note: the Safepoint abstraction also 5237 // uses the Threads_lock to guarantee this property. It also makes sure that 5238 // all threads gets blocked when exiting or starting). 5239 5240 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 5241 ALL_JAVA_THREADS(p) { 5242 p->oops_do(f, cf); 5243 } 5244 VMThread::vm_thread()->oops_do(f, cf); 5245 } 5246 5247 void Threads::change_thread_claim_parity() { 5248 // Set the new claim parity. 5249 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 5250 "Not in range."); 5251 _thread_claim_parity++; 5252 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 5253 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 5254 "Not in range."); 5255 } 5256 5257 #ifdef ASSERT 5258 void Threads::assert_all_threads_claimed() { 5259 ALL_JAVA_THREADS(p) { 5260 const int thread_parity = p->oops_do_parity(); 5261 assert((thread_parity == _thread_claim_parity), 5262 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 5263 } 5264 VMThread* vmt = VMThread::vm_thread(); 5265 const int thread_parity = vmt->oops_do_parity(); 5266 assert((thread_parity == _thread_claim_parity), 5267 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 5268 } 5269 #endif // ASSERT 5270 5271 class ParallelOopsDoThreadClosure : public ThreadClosure { 5272 private: 5273 OopClosure* _f; 5274 CodeBlobClosure* _cf; 5275 public: 5276 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 5277 void do_thread(Thread* t) { 5278 t->oops_do(_f, _cf); 5279 } 5280 }; 5281 5282 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 5283 ParallelOopsDoThreadClosure tc(f, cf); 5284 possibly_parallel_threads_do(is_par, &tc); 5285 } 5286 5287 #if INCLUDE_ALL_GCS 5288 // Used by ParallelScavenge 5289 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 5290 ALL_JAVA_THREADS(p) { 5291 q->enqueue(new ThreadRootsTask(p)); 5292 } 5293 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 5294 } 5295 5296 // Used by Parallel Old 5297 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 5298 ALL_JAVA_THREADS(p) { 5299 q->enqueue(new ThreadRootsMarkingTask(p)); 5300 } 5301 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 5302 } 5303 #endif // INCLUDE_ALL_GCS 5304 5305 void Threads::nmethods_do(CodeBlobClosure* cf) { 5306 ALL_JAVA_THREADS(p) { 5307 // This is used by the code cache sweeper to mark nmethods that are active 5308 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 5309 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 5310 if(!p->is_Code_cache_sweeper_thread()) { 5311 p->nmethods_do(cf); 5312 } 5313 } 5314 } 5315 5316 void Threads::metadata_do(void f(Metadata*)) { 5317 ALL_JAVA_THREADS(p) { 5318 p->metadata_do(f); 5319 } 5320 } 5321 5322 class ThreadHandlesClosure : public ThreadClosure { 5323 void (*_f)(Metadata*); 5324 public: 5325 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 5326 virtual void do_thread(Thread* thread) { 5327 thread->metadata_handles_do(_f); 5328 } 5329 }; 5330 5331 void Threads::metadata_handles_do(void f(Metadata*)) { 5332 // Only walk the Handles in Thread. 5333 ThreadHandlesClosure handles_closure(f); 5334 threads_do(&handles_closure); 5335 } 5336 5337 void Threads::deoptimized_wrt_marked_nmethods() { 5338 ALL_JAVA_THREADS(p) { 5339 p->deoptimized_wrt_marked_nmethods(); 5340 } 5341 } 5342 5343 5344 // Get count Java threads that are waiting to enter the specified monitor. 5345 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 5346 int count, 5347 address monitor) { 5348 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 5349 5350 int i = 0; 5351 DO_JAVA_THREADS(t_list, p) { 5352 if (!p->can_call_java()) continue; 5353 5354 address pending = (address)p->current_pending_monitor(); 5355 if (pending == monitor) { // found a match 5356 if (i < count) result->append(p); // save the first count matches 5357 i++; 5358 } 5359 } 5360 5361 return result; 5362 } 5363 5364 5365 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 5366 address owner) { 5367 // NULL owner means not locked so we can skip the search 5368 if (owner == NULL) return NULL; 5369 5370 DO_JAVA_THREADS(t_list, p) { 5371 // first, see if owner is the address of a Java thread 5372 if (owner == (address)p) return p; 5373 } 5374 5375 // Cannot assert on lack of success here since this function may be 5376 // used by code that is trying to report useful problem information 5377 // like deadlock detection. 5378 if (UseHeavyMonitors) return NULL; 5379 5380 // If we didn't find a matching Java thread and we didn't force use of 5381 // heavyweight monitors, then the owner is the stack address of the 5382 // Lock Word in the owning Java thread's stack. 5383 // 5384 JavaThread* the_owner = NULL; 5385 DO_JAVA_THREADS(t_list, q) { 5386 if (q->is_lock_owned(owner)) { 5387 the_owner = q; 5388 break; 5389 } 5390 } 5391 5392 // cannot assert on lack of success here; see above comment 5393 return the_owner; 5394 } 5395 5396 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 5397 void Threads::print_on(outputStream* st, bool print_stacks, 5398 bool internal_format, bool print_concurrent_locks) { 5399 char buf[32]; 5400 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 5401 5402 st->print_cr("Full thread dump %s (%s %s):", 5403 Abstract_VM_Version::vm_name(), 5404 Abstract_VM_Version::vm_release(), 5405 Abstract_VM_Version::vm_info_string()); 5406 st->cr(); 5407 5408 #if INCLUDE_SERVICES 5409 // Dump concurrent locks 5410 ConcurrentLocksDump concurrent_locks; 5411 if (print_concurrent_locks) { 5412 concurrent_locks.dump_at_safepoint(); 5413 } 5414 #endif // INCLUDE_SERVICES 5415 5416 print_smr_info_on(st); 5417 st->cr(); 5418 5419 ALL_JAVA_THREADS(p) { 5420 ResourceMark rm; 5421 p->print_on(st); 5422 if (print_stacks) { 5423 if (internal_format) { 5424 p->trace_stack(); 5425 } else { 5426 p->print_stack_on(st); 5427 } 5428 } 5429 st->cr(); 5430 #if INCLUDE_SERVICES 5431 if (print_concurrent_locks) { 5432 concurrent_locks.print_locks_on(p, st); 5433 } 5434 #endif // INCLUDE_SERVICES 5435 } 5436 5437 VMThread::vm_thread()->print_on(st); 5438 st->cr(); 5439 Universe::heap()->print_gc_threads_on(st); 5440 WatcherThread* wt = WatcherThread::watcher_thread(); 5441 if (wt != NULL) { 5442 wt->print_on(st); 5443 st->cr(); 5444 } 5445 5446 st->flush(); 5447 } 5448 5449 // Log Threads class SMR info. 5450 void Threads::log_smr_statistics() { 5451 LogTarget(Info, thread, smr) log; 5452 if (log.is_enabled()) { 5453 LogStream out(log); 5454 print_smr_info_on(&out); 5455 } 5456 } 5457 5458 // Print Threads class SMR info. 5459 void Threads::print_smr_info_on(outputStream* st) { 5460 // Only grab the Threads_lock if we don't already own it 5461 // and if we are not reporting an error. 5462 MutexLockerEx ml((Threads_lock->owned_by_self() || VMError::is_error_reported()) ? NULL : Threads_lock); 5463 5464 st->print_cr("Threads class SMR info:"); 5465 st->print_cr("_smr_java_thread_list=" INTPTR_FORMAT ", length=%u, " 5466 "elements={", p2i(_smr_java_thread_list), 5467 _smr_java_thread_list->length()); 5468 print_smr_info_elements_on(st, _smr_java_thread_list); 5469 st->print_cr("}"); 5470 if (_smr_to_delete_list != NULL) { 5471 st->print_cr("_smr_to_delete_list=" INTPTR_FORMAT ", length=%u, " 5472 "elements={", p2i(_smr_to_delete_list), 5473 _smr_to_delete_list->length()); 5474 print_smr_info_elements_on(st, _smr_to_delete_list); 5475 st->print_cr("}"); 5476 for (ThreadsList *t_list = _smr_to_delete_list->next_list(); 5477 t_list != NULL; t_list = t_list->next_list()) { 5478 st->print("next-> " INTPTR_FORMAT ", length=%u, " 5479 "elements={", p2i(t_list), t_list->length()); 5480 print_smr_info_elements_on(st, t_list); 5481 st->print_cr("}"); 5482 } 5483 } 5484 if (!EnableThreadSMRStatistics) { 5485 return; 5486 } 5487 st->print_cr("_smr_java_thread_list_alloc_cnt=" UINT64_FORMAT "," 5488 "_smr_java_thread_list_free_cnt=" UINT64_FORMAT "," 5489 "_smr_java_thread_list_max=%u, " 5490 "_smr_nested_thread_list_max=%u", 5491 _smr_java_thread_list_alloc_cnt, 5492 _smr_java_thread_list_free_cnt, 5493 _smr_java_thread_list_max, 5494 _smr_nested_thread_list_max); 5495 if (_smr_tlh_cnt > 0) { 5496 st->print_cr("_smr_tlh_cnt=%u" 5497 ", _smr_tlh_times=%u" 5498 ", avg_smr_tlh_time=%0.2f" 5499 ", _smr_tlh_time_max=%u", 5500 _smr_tlh_cnt, _smr_tlh_times, 5501 ((double) _smr_tlh_times / _smr_tlh_cnt), 5502 _smr_tlh_time_max); 5503 } 5504 if (_smr_deleted_thread_cnt > 0) { 5505 st->print_cr("_smr_deleted_thread_cnt=%u" 5506 ", _smr_deleted_thread_times=%u" 5507 ", avg_smr_deleted_thread_time=%0.2f" 5508 ", _smr_deleted_thread_time_max=%u", 5509 _smr_deleted_thread_cnt, _smr_deleted_thread_times, 5510 ((double) _smr_deleted_thread_times / _smr_deleted_thread_cnt), 5511 _smr_deleted_thread_time_max); 5512 } 5513 st->print_cr("_smr_delete_lock_wait_cnt=%u, _smr_delete_lock_wait_max=%u", 5514 _smr_delete_lock_wait_cnt, _smr_delete_lock_wait_max); 5515 st->print_cr("_smr_to_delete_list_cnt=%u, _smr_to_delete_list_max=%u", 5516 _smr_to_delete_list_cnt, _smr_to_delete_list_max); 5517 } 5518 5519 // Print ThreadsList elements (4 per line). 5520 void Threads::print_smr_info_elements_on(outputStream* st, 5521 ThreadsList* t_list) { 5522 uint cnt = 0; 5523 JavaThreadIterator jti(t_list); 5524 for (JavaThread *jt = jti.first(); jt != NULL; jt = jti.next()) { 5525 st->print(INTPTR_FORMAT, p2i(jt)); 5526 if (cnt < t_list->length() - 1) { 5527 // Separate with comma or comma-space except for the last one. 5528 if (((cnt + 1) % 4) == 0) { 5529 // Four INTPTR_FORMAT fit on an 80 column line so end the 5530 // current line with just a comma. 5531 st->print_cr(","); 5532 } else { 5533 // Not the last one on the current line so use comma-space: 5534 st->print(", "); 5535 } 5536 } else { 5537 // Last one so just end the current line. 5538 st->cr(); 5539 } 5540 cnt++; 5541 } 5542 } 5543 5544 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 5545 int buflen, bool* found_current) { 5546 if (this_thread != NULL) { 5547 bool is_current = (current == this_thread); 5548 *found_current = *found_current || is_current; 5549 st->print("%s", is_current ? "=>" : " "); 5550 5551 st->print(PTR_FORMAT, p2i(this_thread)); 5552 st->print(" "); 5553 this_thread->print_on_error(st, buf, buflen); 5554 st->cr(); 5555 } 5556 } 5557 5558 class PrintOnErrorClosure : public ThreadClosure { 5559 outputStream* _st; 5560 Thread* _current; 5561 char* _buf; 5562 int _buflen; 5563 bool* _found_current; 5564 public: 5565 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 5566 int buflen, bool* found_current) : 5567 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 5568 5569 virtual void do_thread(Thread* thread) { 5570 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 5571 } 5572 }; 5573 5574 // Threads::print_on_error() is called by fatal error handler. It's possible 5575 // that VM is not at safepoint and/or current thread is inside signal handler. 5576 // Don't print stack trace, as the stack may not be walkable. Don't allocate 5577 // memory (even in resource area), it might deadlock the error handler. 5578 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 5579 int buflen) { 5580 print_smr_info_on(st); 5581 st->cr(); 5582 5583 bool found_current = false; 5584 st->print_cr("Java Threads: ( => current thread )"); 5585 ALL_JAVA_THREADS(thread) { 5586 print_on_error(thread, st, current, buf, buflen, &found_current); 5587 } 5588 st->cr(); 5589 5590 st->print_cr("Other Threads:"); 5591 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 5592 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 5593 5594 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 5595 Universe::heap()->gc_threads_do(&print_closure); 5596 5597 if (!found_current) { 5598 st->cr(); 5599 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 5600 current->print_on_error(st, buf, buflen); 5601 st->cr(); 5602 } 5603 st->cr(); 5604 5605 st->print_cr("Threads with active compile tasks:"); 5606 print_threads_compiling(st, buf, buflen); 5607 } 5608 5609 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 5610 ALL_JAVA_THREADS(thread) { 5611 if (thread->is_Compiler_thread()) { 5612 CompilerThread* ct = (CompilerThread*) thread; 5613 if (ct->task() != NULL) { 5614 thread->print_name_on_error(st, buf, buflen); 5615 ct->task()->print(st, NULL, true, true); 5616 } 5617 } 5618 } 5619 } 5620 5621 5622 // Internal SpinLock and Mutex 5623 // Based on ParkEvent 5624 5625 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 5626 // 5627 // We employ SpinLocks _only for low-contention, fixed-length 5628 // short-duration critical sections where we're concerned 5629 // about native mutex_t or HotSpot Mutex:: latency. 5630 // The mux construct provides a spin-then-block mutual exclusion 5631 // mechanism. 5632 // 5633 // Testing has shown that contention on the ListLock guarding gFreeList 5634 // is common. If we implement ListLock as a simple SpinLock it's common 5635 // for the JVM to devolve to yielding with little progress. This is true 5636 // despite the fact that the critical sections protected by ListLock are 5637 // extremely short. 5638 // 5639 // TODO-FIXME: ListLock should be of type SpinLock. 5640 // We should make this a 1st-class type, integrated into the lock 5641 // hierarchy as leaf-locks. Critically, the SpinLock structure 5642 // should have sufficient padding to avoid false-sharing and excessive 5643 // cache-coherency traffic. 5644 5645 5646 typedef volatile int SpinLockT; 5647 5648 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 5649 if (Atomic::cmpxchg (1, adr, 0) == 0) { 5650 return; // normal fast-path return 5651 } 5652 5653 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 5654 TEVENT(SpinAcquire - ctx); 5655 int ctr = 0; 5656 int Yields = 0; 5657 for (;;) { 5658 while (*adr != 0) { 5659 ++ctr; 5660 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 5661 if (Yields > 5) { 5662 os::naked_short_sleep(1); 5663 } else { 5664 os::naked_yield(); 5665 ++Yields; 5666 } 5667 } else { 5668 SpinPause(); 5669 } 5670 } 5671 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 5672 } 5673 } 5674 5675 void Thread::SpinRelease(volatile int * adr) { 5676 assert(*adr != 0, "invariant"); 5677 OrderAccess::fence(); // guarantee at least release consistency. 5678 // Roach-motel semantics. 5679 // It's safe if subsequent LDs and STs float "up" into the critical section, 5680 // but prior LDs and STs within the critical section can't be allowed 5681 // to reorder or float past the ST that releases the lock. 5682 // Loads and stores in the critical section - which appear in program 5683 // order before the store that releases the lock - must also appear 5684 // before the store that releases the lock in memory visibility order. 5685 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 5686 // the ST of 0 into the lock-word which releases the lock, so fence 5687 // more than covers this on all platforms. 5688 *adr = 0; 5689 } 5690 5691 // muxAcquire and muxRelease: 5692 // 5693 // * muxAcquire and muxRelease support a single-word lock-word construct. 5694 // The LSB of the word is set IFF the lock is held. 5695 // The remainder of the word points to the head of a singly-linked list 5696 // of threads blocked on the lock. 5697 // 5698 // * The current implementation of muxAcquire-muxRelease uses its own 5699 // dedicated Thread._MuxEvent instance. If we're interested in 5700 // minimizing the peak number of extant ParkEvent instances then 5701 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 5702 // as certain invariants were satisfied. Specifically, care would need 5703 // to be taken with regards to consuming unpark() "permits". 5704 // A safe rule of thumb is that a thread would never call muxAcquire() 5705 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 5706 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 5707 // consume an unpark() permit intended for monitorenter, for instance. 5708 // One way around this would be to widen the restricted-range semaphore 5709 // implemented in park(). Another alternative would be to provide 5710 // multiple instances of the PlatformEvent() for each thread. One 5711 // instance would be dedicated to muxAcquire-muxRelease, for instance. 5712 // 5713 // * Usage: 5714 // -- Only as leaf locks 5715 // -- for short-term locking only as muxAcquire does not perform 5716 // thread state transitions. 5717 // 5718 // Alternatives: 5719 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 5720 // but with parking or spin-then-park instead of pure spinning. 5721 // * Use Taura-Oyama-Yonenzawa locks. 5722 // * It's possible to construct a 1-0 lock if we encode the lockword as 5723 // (List,LockByte). Acquire will CAS the full lockword while Release 5724 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 5725 // acquiring threads use timers (ParkTimed) to detect and recover from 5726 // the stranding window. Thread/Node structures must be aligned on 256-byte 5727 // boundaries by using placement-new. 5728 // * Augment MCS with advisory back-link fields maintained with CAS(). 5729 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 5730 // The validity of the backlinks must be ratified before we trust the value. 5731 // If the backlinks are invalid the exiting thread must back-track through the 5732 // the forward links, which are always trustworthy. 5733 // * Add a successor indication. The LockWord is currently encoded as 5734 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 5735 // to provide the usual futile-wakeup optimization. 5736 // See RTStt for details. 5737 // * Consider schedctl.sc_nopreempt to cover the critical section. 5738 // 5739 5740 5741 const intptr_t LOCKBIT = 1; 5742 5743 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 5744 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 5745 if (w == 0) return; 5746 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5747 return; 5748 } 5749 5750 TEVENT(muxAcquire - Contention); 5751 ParkEvent * const Self = Thread::current()->_MuxEvent; 5752 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 5753 for (;;) { 5754 int its = (os::is_MP() ? 100 : 0) + 1; 5755 5756 // Optional spin phase: spin-then-park strategy 5757 while (--its >= 0) { 5758 w = *Lock; 5759 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5760 return; 5761 } 5762 } 5763 5764 Self->reset(); 5765 Self->OnList = intptr_t(Lock); 5766 // The following fence() isn't _strictly necessary as the subsequent 5767 // CAS() both serializes execution and ratifies the fetched *Lock value. 5768 OrderAccess::fence(); 5769 for (;;) { 5770 w = *Lock; 5771 if ((w & LOCKBIT) == 0) { 5772 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5773 Self->OnList = 0; // hygiene - allows stronger asserts 5774 return; 5775 } 5776 continue; // Interference -- *Lock changed -- Just retry 5777 } 5778 assert(w & LOCKBIT, "invariant"); 5779 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5780 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 5781 } 5782 5783 while (Self->OnList != 0) { 5784 Self->park(); 5785 } 5786 } 5787 } 5788 5789 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 5790 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 5791 if (w == 0) return; 5792 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5793 return; 5794 } 5795 5796 TEVENT(muxAcquire - Contention); 5797 ParkEvent * ReleaseAfter = NULL; 5798 if (ev == NULL) { 5799 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 5800 } 5801 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 5802 for (;;) { 5803 guarantee(ev->OnList == 0, "invariant"); 5804 int its = (os::is_MP() ? 100 : 0) + 1; 5805 5806 // Optional spin phase: spin-then-park strategy 5807 while (--its >= 0) { 5808 w = *Lock; 5809 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5810 if (ReleaseAfter != NULL) { 5811 ParkEvent::Release(ReleaseAfter); 5812 } 5813 return; 5814 } 5815 } 5816 5817 ev->reset(); 5818 ev->OnList = intptr_t(Lock); 5819 // The following fence() isn't _strictly necessary as the subsequent 5820 // CAS() both serializes execution and ratifies the fetched *Lock value. 5821 OrderAccess::fence(); 5822 for (;;) { 5823 w = *Lock; 5824 if ((w & LOCKBIT) == 0) { 5825 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5826 ev->OnList = 0; 5827 // We call ::Release while holding the outer lock, thus 5828 // artificially lengthening the critical section. 5829 // Consider deferring the ::Release() until the subsequent unlock(), 5830 // after we've dropped the outer lock. 5831 if (ReleaseAfter != NULL) { 5832 ParkEvent::Release(ReleaseAfter); 5833 } 5834 return; 5835 } 5836 continue; // Interference -- *Lock changed -- Just retry 5837 } 5838 assert(w & LOCKBIT, "invariant"); 5839 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5840 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 5841 } 5842 5843 while (ev->OnList != 0) { 5844 ev->park(); 5845 } 5846 } 5847 } 5848 5849 // Release() must extract a successor from the list and then wake that thread. 5850 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5851 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5852 // Release() would : 5853 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5854 // (B) Extract a successor from the private list "in-hand" 5855 // (C) attempt to CAS() the residual back into *Lock over null. 5856 // If there were any newly arrived threads and the CAS() would fail. 5857 // In that case Release() would detach the RATs, re-merge the list in-hand 5858 // with the RATs and repeat as needed. Alternately, Release() might 5859 // detach and extract a successor, but then pass the residual list to the wakee. 5860 // The wakee would be responsible for reattaching and remerging before it 5861 // competed for the lock. 5862 // 5863 // Both "pop" and DMR are immune from ABA corruption -- there can be 5864 // multiple concurrent pushers, but only one popper or detacher. 5865 // This implementation pops from the head of the list. This is unfair, 5866 // but tends to provide excellent throughput as hot threads remain hot. 5867 // (We wake recently run threads first). 5868 // 5869 // All paths through muxRelease() will execute a CAS. 5870 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5871 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5872 // executed within the critical section are complete and globally visible before the 5873 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5874 void Thread::muxRelease(volatile intptr_t * Lock) { 5875 for (;;) { 5876 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 5877 assert(w & LOCKBIT, "invariant"); 5878 if (w == LOCKBIT) return; 5879 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5880 assert(List != NULL, "invariant"); 5881 assert(List->OnList == intptr_t(Lock), "invariant"); 5882 ParkEvent * const nxt = List->ListNext; 5883 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5884 5885 // The following CAS() releases the lock and pops the head element. 5886 // The CAS() also ratifies the previously fetched lock-word value. 5887 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 5888 continue; 5889 } 5890 List->OnList = 0; 5891 OrderAccess::fence(); 5892 List->unpark(); 5893 return; 5894 } 5895 } 5896 5897 5898 void Threads::verify() { 5899 ALL_JAVA_THREADS(p) { 5900 p->verify(); 5901 } 5902 VMThread* thread = VMThread::vm_thread(); 5903 if (thread != NULL) thread->verify(); 5904 }