1 /* 2 * Copyright (c) 1997, 2018, 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/barrierSet.hpp" 37 #include "gc/shared/gcId.hpp" 38 #include "gc/shared/gcLocker.inline.hpp" 39 #include "gc/shared/workgroup.hpp" 40 #include "interpreter/interpreter.hpp" 41 #include "interpreter/linkResolver.hpp" 42 #include "interpreter/oopMapCache.hpp" 43 #include "jfr/jfrEvents.hpp" 44 #include "jfr/support/jfrThreadId.hpp" 45 #include "jvmtifiles/jvmtiEnv.hpp" 46 #include "logging/log.hpp" 47 #include "logging/logConfiguration.hpp" 48 #include "logging/logStream.hpp" 49 #include "memory/allocation.inline.hpp" 50 #include "memory/metaspaceShared.hpp" 51 #include "memory/oopFactory.hpp" 52 #include "memory/resourceArea.hpp" 53 #include "memory/universe.hpp" 54 #include "oops/access.inline.hpp" 55 #include "oops/instanceKlass.hpp" 56 #include "oops/objArrayOop.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "oops/symbol.hpp" 59 #include "oops/typeArrayOop.inline.hpp" 60 #include "oops/verifyOopClosure.hpp" 61 #include "prims/jvm_misc.hpp" 62 #include "prims/jvmtiExport.hpp" 63 #include "prims/jvmtiThreadState.hpp" 64 #include "runtime/arguments.hpp" 65 #include "runtime/atomic.hpp" 66 #include "runtime/biasedLocking.hpp" 67 #include "runtime/fieldDescriptor.inline.hpp" 68 #include "runtime/flags/jvmFlagConstraintList.hpp" 69 #include "runtime/flags/jvmFlagRangeList.hpp" 70 #include "runtime/flags/jvmFlagWriteableList.hpp" 71 #include "runtime/deoptimization.hpp" 72 #include "runtime/frame.inline.hpp" 73 #include "runtime/handshake.hpp" 74 #include "runtime/init.hpp" 75 #include "runtime/interfaceSupport.inline.hpp" 76 #include "runtime/java.hpp" 77 #include "runtime/javaCalls.hpp" 78 #include "runtime/jniHandles.inline.hpp" 79 #include "runtime/jniPeriodicChecker.hpp" 80 #include "runtime/memprofiler.hpp" 81 #include "runtime/mutexLocker.hpp" 82 #include "runtime/objectMonitor.hpp" 83 #include "runtime/orderAccess.hpp" 84 #include "runtime/osThread.hpp" 85 #include "runtime/prefetch.inline.hpp" 86 #include "runtime/safepoint.hpp" 87 #include "runtime/safepointMechanism.inline.hpp" 88 #include "runtime/safepointVerifiers.hpp" 89 #include "runtime/sharedRuntime.hpp" 90 #include "runtime/statSampler.hpp" 91 #include "runtime/stubRoutines.hpp" 92 #include "runtime/sweeper.hpp" 93 #include "runtime/task.hpp" 94 #include "runtime/thread.inline.hpp" 95 #include "runtime/threadCritical.hpp" 96 #include "runtime/threadSMR.inline.hpp" 97 #include "runtime/threadStatisticalInfo.hpp" 98 #include "runtime/timer.hpp" 99 #include "runtime/timerTrace.hpp" 100 #include "runtime/vframe.inline.hpp" 101 #include "runtime/vframeArray.hpp" 102 #include "runtime/vframe_hp.hpp" 103 #include "runtime/vmThread.hpp" 104 #include "runtime/vm_operations.hpp" 105 #include "runtime/vm_version.hpp" 106 #include "services/attachListener.hpp" 107 #include "services/management.hpp" 108 #include "services/memTracker.hpp" 109 #include "services/threadService.hpp" 110 #include "utilities/align.hpp" 111 #include "utilities/copy.hpp" 112 #include "utilities/defaultStream.hpp" 113 #include "utilities/dtrace.hpp" 114 #include "utilities/events.hpp" 115 #include "utilities/macros.hpp" 116 #include "utilities/preserveException.hpp" 117 #include "utilities/singleWriterSynchronizer.hpp" 118 #include "utilities/vmError.hpp" 119 #if INCLUDE_JVMCI 120 #include "jvmci/jvmciCompiler.hpp" 121 #include "jvmci/jvmciRuntime.hpp" 122 #include "logging/logHandle.hpp" 123 #endif 124 #ifdef COMPILER1 125 #include "c1/c1_Compiler.hpp" 126 #endif 127 #ifdef COMPILER2 128 #include "opto/c2compiler.hpp" 129 #include "opto/idealGraphPrinter.hpp" 130 #endif 131 #if INCLUDE_RTM_OPT 132 #include "runtime/rtmLocking.hpp" 133 #endif 134 #if INCLUDE_JFR 135 #include "jfr/jfr.hpp" 136 #endif 137 138 // Initialization after module runtime initialization 139 void universe_post_module_init(); // must happen after call_initPhase2 140 141 #ifdef DTRACE_ENABLED 142 143 // Only bother with this argument setup if dtrace is available 144 145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) \ 149 { \ 150 ResourceMark rm(this); \ 151 int len = 0; \ 152 const char* name = (javathread)->get_thread_name(); \ 153 len = strlen(name); \ 154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 155 (char *) name, len, \ 156 java_lang_Thread::thread_id((javathread)->threadObj()), \ 157 (uintptr_t) (javathread)->osthread()->thread_id(), \ 158 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 159 } 160 161 #else // ndef DTRACE_ENABLED 162 163 #define DTRACE_THREAD_PROBE(probe, javathread) 164 165 #endif // ndef DTRACE_ENABLED 166 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY 168 // Current thread is maintained as a thread-local variable 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 170 #endif 171 172 // ======= Thread ======== 173 // Support for forcing alignment of thread objects for biased locking 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 175 if (UseBiasedLocking) { 176 const int alignment = markOopDesc::biased_lock_alignment; 177 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 179 : AllocateHeap(aligned_size, flags, CURRENT_PC, 180 AllocFailStrategy::RETURN_NULL); 181 void* aligned_addr = align_up(real_malloc_addr, alignment); 182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 184 "JavaThread alignment code overflowed allocated storage"); 185 if (aligned_addr != real_malloc_addr) { 186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 187 p2i(real_malloc_addr), 188 p2i(aligned_addr)); 189 } 190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 191 return aligned_addr; 192 } else { 193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 195 } 196 } 197 198 void Thread::operator delete(void* p) { 199 if (UseBiasedLocking) { 200 FreeHeap(((Thread*) p)->_real_malloc_address); 201 } else { 202 FreeHeap(p); 203 } 204 } 205 206 void JavaThread::smr_delete() { 207 if (_on_thread_list) { 208 ThreadsSMRSupport::smr_delete(this); 209 } else { 210 delete this; 211 } 212 } 213 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 215 // JavaThread 216 217 218 Thread::Thread() { 219 // stack and get_thread 220 set_stack_base(NULL); 221 set_stack_size(0); 222 set_self_raw_id(0); 223 set_lgrp_id(-1); 224 DEBUG_ONLY(clear_suspendible_thread();) 225 226 // allocated data structures 227 set_osthread(NULL); 228 set_resource_area(new (mtThread)ResourceArea()); 229 DEBUG_ONLY(_current_resource_mark = NULL;) 230 set_handle_area(new (mtThread) HandleArea(NULL)); 231 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 232 set_active_handles(NULL); 233 set_free_handle_block(NULL); 234 set_last_handle_mark(NULL); 235 236 // This initial value ==> never claimed. 237 _oops_do_parity = 0; 238 _threads_hazard_ptr = NULL; 239 _threads_list_ptr = NULL; 240 _nested_threads_hazard_ptr_cnt = 0; 241 _rcu_counter = 0; 242 243 // the handle mark links itself to last_handle_mark 244 new HandleMark(this); 245 246 // plain initialization 247 debug_only(_owned_locks = NULL;) 248 debug_only(_allow_allocation_count = 0;) 249 NOT_PRODUCT(_allow_safepoint_count = 0;) 250 NOT_PRODUCT(_skip_gcalot = false;) 251 _jvmti_env_iteration_count = 0; 252 set_allocated_bytes(0); 253 _vm_operation_started_count = 0; 254 _vm_operation_completed_count = 0; 255 _current_pending_monitor = NULL; 256 _current_pending_monitor_is_from_java = true; 257 _current_waiting_monitor = NULL; 258 _num_nested_signal = 0; 259 omFreeList = NULL; 260 omFreeCount = 0; 261 omFreeProvision = 32; 262 omInUseList = NULL; 263 omInUseCount = 0; 264 265 #ifdef ASSERT 266 _visited_for_critical_count = false; 267 #endif 268 269 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 270 Monitor::_safepoint_check_sometimes); 271 _suspend_flags = 0; 272 273 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 274 _hashStateX = os::random(); 275 _hashStateY = 842502087; 276 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 277 _hashStateW = 273326509; 278 279 _OnTrap = 0; 280 _Stalled = 0; 281 _TypeTag = 0x2BAD; 282 283 // Many of the following fields are effectively final - immutable 284 // Note that nascent threads can't use the Native Monitor-Mutex 285 // construct until the _MutexEvent is initialized ... 286 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 287 // we might instead use a stack of ParkEvents that we could provision on-demand. 288 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 289 // and ::Release() 290 _ParkEvent = ParkEvent::Allocate(this); 291 _SleepEvent = ParkEvent::Allocate(this); 292 _MutexEvent = ParkEvent::Allocate(this); 293 _MuxEvent = ParkEvent::Allocate(this); 294 295 #ifdef CHECK_UNHANDLED_OOPS 296 if (CheckUnhandledOops) { 297 _unhandled_oops = new UnhandledOops(this); 298 } 299 #endif // CHECK_UNHANDLED_OOPS 300 #ifdef ASSERT 301 if (UseBiasedLocking) { 302 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 303 assert(this == _real_malloc_address || 304 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 305 "bug in forced alignment of thread objects"); 306 } 307 #endif // ASSERT 308 309 // Notify the barrier set that a thread is being created. Note that some 310 // threads are created before a barrier set is available. The call to 311 // BarrierSet::on_thread_create() for these threads is therefore deferred 312 // to BarrierSet::set_barrier_set(). 313 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 314 if (barrier_set != NULL) { 315 barrier_set->on_thread_create(this); 316 } else { 317 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();) 318 } 319 } 320 321 void Thread::initialize_thread_current() { 322 #ifndef USE_LIBRARY_BASED_TLS_ONLY 323 assert(_thr_current == NULL, "Thread::current already initialized"); 324 _thr_current = this; 325 #endif 326 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 327 ThreadLocalStorage::set_thread(this); 328 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 329 } 330 331 void Thread::clear_thread_current() { 332 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 333 #ifndef USE_LIBRARY_BASED_TLS_ONLY 334 _thr_current = NULL; 335 #endif 336 ThreadLocalStorage::set_thread(NULL); 337 } 338 339 void Thread::record_stack_base_and_size() { 340 // Note: at this point, Thread object is not yet initialized. Do not rely on 341 // any members being initialized. Do not rely on Thread::current() being set. 342 // If possible, refrain from doing anything which may crash or assert since 343 // quite probably those crash dumps will be useless. 344 set_stack_base(os::current_stack_base()); 345 set_stack_size(os::current_stack_size()); 346 347 #ifdef SOLARIS 348 if (os::is_primordial_thread()) { 349 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 350 } 351 #endif 352 353 // Set stack limits after thread is initialized. 354 if (is_Java_thread()) { 355 ((JavaThread*) this)->set_stack_overflow_limit(); 356 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 357 } 358 } 359 360 #if INCLUDE_NMT 361 void Thread::register_thread_stack_with_NMT() { 362 MemTracker::record_thread_stack(stack_end(), stack_size()); 363 } 364 #endif // INCLUDE_NMT 365 366 void Thread::call_run() { 367 // At this point, Thread object should be fully initialized and 368 // Thread::current() should be set. 369 370 register_thread_stack_with_NMT(); 371 372 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 373 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 374 os::current_thread_id(), p2i(stack_base() - stack_size()), 375 p2i(stack_base()), stack_size()/1024); 376 377 // Invoke <ChildClass>::run() 378 this->run(); 379 // Returned from <ChildClass>::run(). Thread finished. 380 381 // Note: at this point the thread object may already have deleted itself. 382 // So from here on do not dereference *this*. 383 384 // If a thread has not deleted itself ("delete this") as part of its 385 // termination sequence, we have to ensure thread-local-storage is 386 // cleared before we actually terminate. No threads should ever be 387 // deleted asynchronously with respect to their termination. 388 if (Thread::current_or_null_safe() != NULL) { 389 assert(Thread::current_or_null_safe() == this, "current thread is wrong"); 390 Thread::clear_thread_current(); 391 } 392 393 } 394 395 Thread::~Thread() { 396 JFR_ONLY(Jfr::on_thread_destruct(this);) 397 398 // Notify the barrier set that a thread is being destroyed. Note that a barrier 399 // set might not be available if we encountered errors during bootstrapping. 400 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 401 if (barrier_set != NULL) { 402 barrier_set->on_thread_destroy(this); 403 } 404 405 406 // stack_base can be NULL if the thread is never started or exited before 407 // record_stack_base_and_size called. Although, we would like to ensure 408 // that all started threads do call record_stack_base_and_size(), there is 409 // not proper way to enforce that. 410 #if INCLUDE_NMT 411 if (_stack_base != NULL) { 412 MemTracker::release_thread_stack(stack_end(), stack_size()); 413 #ifdef ASSERT 414 set_stack_base(NULL); 415 #endif 416 } 417 #endif // INCLUDE_NMT 418 419 // deallocate data structures 420 delete resource_area(); 421 // since the handle marks are using the handle area, we have to deallocated the root 422 // handle mark before deallocating the thread's handle area, 423 assert(last_handle_mark() != NULL, "check we have an element"); 424 delete last_handle_mark(); 425 assert(last_handle_mark() == NULL, "check we have reached the end"); 426 427 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 428 // We NULL out the fields for good hygiene. 429 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 430 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 431 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 432 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 433 434 delete handle_area(); 435 delete metadata_handles(); 436 437 // SR_handler uses this as a termination indicator - 438 // needs to happen before os::free_thread() 439 delete _SR_lock; 440 _SR_lock = NULL; 441 442 // osthread() can be NULL, if creation of thread failed. 443 if (osthread() != NULL) os::free_thread(osthread()); 444 445 // clear Thread::current if thread is deleting itself. 446 // Needed to ensure JNI correctly detects non-attached threads. 447 if (this == Thread::current()) { 448 Thread::clear_thread_current(); 449 } 450 451 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 452 } 453 454 #ifdef ASSERT 455 // A JavaThread is considered "dangling" if it is not the current 456 // thread, has been added the Threads list, the system is not at a 457 // safepoint and the Thread is not "protected". 458 // 459 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 460 assert(!thread->is_Java_thread() || Thread::current() == thread || 461 !((JavaThread *) thread)->on_thread_list() || 462 SafepointSynchronize::is_at_safepoint() || 463 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 464 "possibility of dangling Thread pointer"); 465 } 466 #endif 467 468 ThreadPriority Thread::get_priority(const Thread* const thread) { 469 ThreadPriority priority; 470 // Can return an error! 471 (void)os::get_priority(thread, priority); 472 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 473 return priority; 474 } 475 476 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 477 debug_only(check_for_dangling_thread_pointer(thread);) 478 // Can return an error! 479 (void)os::set_priority(thread, priority); 480 } 481 482 483 void Thread::start(Thread* thread) { 484 // Start is different from resume in that its safety is guaranteed by context or 485 // being called from a Java method synchronized on the Thread object. 486 if (!DisableStartThread) { 487 if (thread->is_Java_thread()) { 488 // Initialize the thread state to RUNNABLE before starting this thread. 489 // Can not set it after the thread started because we do not know the 490 // exact thread state at that time. It could be in MONITOR_WAIT or 491 // in SLEEPING or some other state. 492 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 493 java_lang_Thread::RUNNABLE); 494 } 495 os::start_thread(thread); 496 } 497 } 498 499 // Enqueue a VM_Operation to do the job for us - sometime later 500 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 501 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 502 VMThread::execute(vm_stop); 503 } 504 505 506 // Check if an external suspend request has completed (or has been 507 // cancelled). Returns true if the thread is externally suspended and 508 // false otherwise. 509 // 510 // The bits parameter returns information about the code path through 511 // the routine. Useful for debugging: 512 // 513 // set in is_ext_suspend_completed(): 514 // 0x00000001 - routine was entered 515 // 0x00000010 - routine return false at end 516 // 0x00000100 - thread exited (return false) 517 // 0x00000200 - suspend request cancelled (return false) 518 // 0x00000400 - thread suspended (return true) 519 // 0x00001000 - thread is in a suspend equivalent state (return true) 520 // 0x00002000 - thread is native and walkable (return true) 521 // 0x00004000 - thread is native_trans and walkable (needed retry) 522 // 523 // set in wait_for_ext_suspend_completion(): 524 // 0x00010000 - routine was entered 525 // 0x00020000 - suspend request cancelled before loop (return false) 526 // 0x00040000 - thread suspended before loop (return true) 527 // 0x00080000 - suspend request cancelled in loop (return false) 528 // 0x00100000 - thread suspended in loop (return true) 529 // 0x00200000 - suspend not completed during retry loop (return false) 530 531 // Helper class for tracing suspend wait debug bits. 532 // 533 // 0x00000100 indicates that the target thread exited before it could 534 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 535 // 0x00080000 each indicate a cancelled suspend request so they don't 536 // count as wait failures either. 537 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 538 539 class TraceSuspendDebugBits : public StackObj { 540 private: 541 JavaThread * jt; 542 bool is_wait; 543 bool called_by_wait; // meaningful when !is_wait 544 uint32_t * bits; 545 546 public: 547 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 548 uint32_t *_bits) { 549 jt = _jt; 550 is_wait = _is_wait; 551 called_by_wait = _called_by_wait; 552 bits = _bits; 553 } 554 555 ~TraceSuspendDebugBits() { 556 if (!is_wait) { 557 #if 1 558 // By default, don't trace bits for is_ext_suspend_completed() calls. 559 // That trace is very chatty. 560 return; 561 #else 562 if (!called_by_wait) { 563 // If tracing for is_ext_suspend_completed() is enabled, then only 564 // trace calls to it from wait_for_ext_suspend_completion() 565 return; 566 } 567 #endif 568 } 569 570 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 571 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 572 MutexLocker ml(Threads_lock); // needed for get_thread_name() 573 ResourceMark rm; 574 575 tty->print_cr( 576 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 577 jt->get_thread_name(), *bits); 578 579 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 580 } 581 } 582 } 583 }; 584 #undef DEBUG_FALSE_BITS 585 586 587 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 588 uint32_t *bits) { 589 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 590 591 bool did_trans_retry = false; // only do thread_in_native_trans retry once 592 bool do_trans_retry; // flag to force the retry 593 594 *bits |= 0x00000001; 595 596 do { 597 do_trans_retry = false; 598 599 if (is_exiting()) { 600 // Thread is in the process of exiting. This is always checked 601 // first to reduce the risk of dereferencing a freed JavaThread. 602 *bits |= 0x00000100; 603 return false; 604 } 605 606 if (!is_external_suspend()) { 607 // Suspend request is cancelled. This is always checked before 608 // is_ext_suspended() to reduce the risk of a rogue resume 609 // confusing the thread that made the suspend request. 610 *bits |= 0x00000200; 611 return false; 612 } 613 614 if (is_ext_suspended()) { 615 // thread is suspended 616 *bits |= 0x00000400; 617 return true; 618 } 619 620 // Now that we no longer do hard suspends of threads running 621 // native code, the target thread can be changing thread state 622 // while we are in this routine: 623 // 624 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 625 // 626 // We save a copy of the thread state as observed at this moment 627 // and make our decision about suspend completeness based on the 628 // copy. This closes the race where the thread state is seen as 629 // _thread_in_native_trans in the if-thread_blocked check, but is 630 // seen as _thread_blocked in if-thread_in_native_trans check. 631 JavaThreadState save_state = thread_state(); 632 633 if (save_state == _thread_blocked && is_suspend_equivalent()) { 634 // If the thread's state is _thread_blocked and this blocking 635 // condition is known to be equivalent to a suspend, then we can 636 // consider the thread to be externally suspended. This means that 637 // the code that sets _thread_blocked has been modified to do 638 // self-suspension if the blocking condition releases. We also 639 // used to check for CONDVAR_WAIT here, but that is now covered by 640 // the _thread_blocked with self-suspension check. 641 // 642 // Return true since we wouldn't be here unless there was still an 643 // external suspend request. 644 *bits |= 0x00001000; 645 return true; 646 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 647 // Threads running native code will self-suspend on native==>VM/Java 648 // transitions. If its stack is walkable (should always be the case 649 // unless this function is called before the actual java_suspend() 650 // call), then the wait is done. 651 *bits |= 0x00002000; 652 return true; 653 } else if (!called_by_wait && !did_trans_retry && 654 save_state == _thread_in_native_trans && 655 frame_anchor()->walkable()) { 656 // The thread is transitioning from thread_in_native to another 657 // thread state. check_safepoint_and_suspend_for_native_trans() 658 // will force the thread to self-suspend. If it hasn't gotten 659 // there yet we may have caught the thread in-between the native 660 // code check above and the self-suspend. Lucky us. If we were 661 // called by wait_for_ext_suspend_completion(), then it 662 // will be doing the retries so we don't have to. 663 // 664 // Since we use the saved thread state in the if-statement above, 665 // there is a chance that the thread has already transitioned to 666 // _thread_blocked by the time we get here. In that case, we will 667 // make a single unnecessary pass through the logic below. This 668 // doesn't hurt anything since we still do the trans retry. 669 670 *bits |= 0x00004000; 671 672 // Once the thread leaves thread_in_native_trans for another 673 // thread state, we break out of this retry loop. We shouldn't 674 // need this flag to prevent us from getting back here, but 675 // sometimes paranoia is good. 676 did_trans_retry = true; 677 678 // We wait for the thread to transition to a more usable state. 679 for (int i = 1; i <= SuspendRetryCount; i++) { 680 // We used to do an "os::yield_all(i)" call here with the intention 681 // that yielding would increase on each retry. However, the parameter 682 // is ignored on Linux which means the yield didn't scale up. Waiting 683 // on the SR_lock below provides a much more predictable scale up for 684 // the delay. It also provides a simple/direct point to check for any 685 // safepoint requests from the VMThread 686 687 // temporarily drops SR_lock while doing wait with safepoint check 688 // (if we're a JavaThread - the WatcherThread can also call this) 689 // and increase delay with each retry 690 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 691 692 // check the actual thread state instead of what we saved above 693 if (thread_state() != _thread_in_native_trans) { 694 // the thread has transitioned to another thread state so 695 // try all the checks (except this one) one more time. 696 do_trans_retry = true; 697 break; 698 } 699 } // end retry loop 700 701 702 } 703 } while (do_trans_retry); 704 705 *bits |= 0x00000010; 706 return false; 707 } 708 709 // Wait for an external suspend request to complete (or be cancelled). 710 // Returns true if the thread is externally suspended and false otherwise. 711 // 712 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 713 uint32_t *bits) { 714 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 715 false /* !called_by_wait */, bits); 716 717 // local flag copies to minimize SR_lock hold time 718 bool is_suspended; 719 bool pending; 720 uint32_t reset_bits; 721 722 // set a marker so is_ext_suspend_completed() knows we are the caller 723 *bits |= 0x00010000; 724 725 // We use reset_bits to reinitialize the bits value at the top of 726 // each retry loop. This allows the caller to make use of any 727 // unused bits for their own marking purposes. 728 reset_bits = *bits; 729 730 { 731 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 732 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 733 delay, bits); 734 pending = is_external_suspend(); 735 } 736 // must release SR_lock to allow suspension to complete 737 738 if (!pending) { 739 // A cancelled suspend request is the only false return from 740 // is_ext_suspend_completed() that keeps us from entering the 741 // retry loop. 742 *bits |= 0x00020000; 743 return false; 744 } 745 746 if (is_suspended) { 747 *bits |= 0x00040000; 748 return true; 749 } 750 751 for (int i = 1; i <= retries; i++) { 752 *bits = reset_bits; // reinit to only track last retry 753 754 // We used to do an "os::yield_all(i)" call here with the intention 755 // that yielding would increase on each retry. However, the parameter 756 // is ignored on Linux which means the yield didn't scale up. Waiting 757 // on the SR_lock below provides a much more predictable scale up for 758 // the delay. It also provides a simple/direct point to check for any 759 // safepoint requests from the VMThread 760 761 { 762 MutexLocker ml(SR_lock()); 763 // wait with safepoint check (if we're a JavaThread - the WatcherThread 764 // can also call this) and increase delay with each retry 765 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 766 767 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 768 delay, bits); 769 770 // It is possible for the external suspend request to be cancelled 771 // (by a resume) before the actual suspend operation is completed. 772 // Refresh our local copy to see if we still need to wait. 773 pending = is_external_suspend(); 774 } 775 776 if (!pending) { 777 // A cancelled suspend request is the only false return from 778 // is_ext_suspend_completed() that keeps us from staying in the 779 // retry loop. 780 *bits |= 0x00080000; 781 return false; 782 } 783 784 if (is_suspended) { 785 *bits |= 0x00100000; 786 return true; 787 } 788 } // end retry loop 789 790 // thread did not suspend after all our retries 791 *bits |= 0x00200000; 792 return false; 793 } 794 795 // Called from API entry points which perform stack walking. If the 796 // associated JavaThread is the current thread, then wait_for_suspend 797 // is not used. Otherwise, it determines if we should wait for the 798 // "other" thread to complete external suspension. (NOTE: in future 799 // releases the suspension mechanism should be reimplemented so this 800 // is not necessary.) 801 // 802 bool 803 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 804 if (this != JavaThread::current()) { 805 // "other" threads require special handling. 806 if (wait_for_suspend) { 807 // We are allowed to wait for the external suspend to complete 808 // so give the other thread a chance to get suspended. 809 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 810 SuspendRetryDelay, bits)) { 811 // Didn't make it so let the caller know. 812 return false; 813 } 814 } 815 // We aren't allowed to wait for the external suspend to complete 816 // so if the other thread isn't externally suspended we need to 817 // let the caller know. 818 else if (!is_ext_suspend_completed_with_lock(bits)) { 819 return false; 820 } 821 } 822 823 return true; 824 } 825 826 #ifndef PRODUCT 827 void JavaThread::record_jump(address target, address instr, const char* file, 828 int line) { 829 830 // This should not need to be atomic as the only way for simultaneous 831 // updates is via interrupts. Even then this should be rare or non-existent 832 // and we don't care that much anyway. 833 834 int index = _jmp_ring_index; 835 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 836 _jmp_ring[index]._target = (intptr_t) target; 837 _jmp_ring[index]._instruction = (intptr_t) instr; 838 _jmp_ring[index]._file = file; 839 _jmp_ring[index]._line = line; 840 } 841 #endif // PRODUCT 842 843 void Thread::interrupt(Thread* thread) { 844 debug_only(check_for_dangling_thread_pointer(thread);) 845 os::interrupt(thread); 846 } 847 848 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 849 debug_only(check_for_dangling_thread_pointer(thread);) 850 // Note: If clear_interrupted==false, this simply fetches and 851 // returns the value of the field osthread()->interrupted(). 852 return os::is_interrupted(thread, clear_interrupted); 853 } 854 855 856 // GC Support 857 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 858 int thread_parity = _oops_do_parity; 859 if (thread_parity != strong_roots_parity) { 860 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 861 if (res == thread_parity) { 862 return true; 863 } else { 864 guarantee(res == strong_roots_parity, "Or else what?"); 865 return false; 866 } 867 } 868 return false; 869 } 870 871 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 872 active_handles()->oops_do(f); 873 // Do oop for ThreadShadow 874 f->do_oop((oop*)&_pending_exception); 875 handle_area()->oops_do(f); 876 877 // We scan thread local monitor lists here, and the remaining global 878 // monitors in ObjectSynchronizer::oops_do(). 879 ObjectSynchronizer::thread_local_used_oops_do(this, f); 880 } 881 882 void Thread::metadata_handles_do(void f(Metadata*)) { 883 // Only walk the Handles in Thread. 884 if (metadata_handles() != NULL) { 885 for (int i = 0; i< metadata_handles()->length(); i++) { 886 f(metadata_handles()->at(i)); 887 } 888 } 889 } 890 891 void Thread::print_on(outputStream* st, bool print_extended_info) const { 892 // get_priority assumes osthread initialized 893 if (osthread() != NULL) { 894 int os_prio; 895 if (os::get_native_priority(this, &os_prio) == OS_OK) { 896 st->print("os_prio=%d ", os_prio); 897 } 898 899 st->print("cpu=%.2fms ", 900 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 901 ); 902 st->print("elapsed=%.2fs ", 903 _statistical_info.getElapsedTime() / 1000.0 904 ); 905 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 906 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 907 st->print("allocated=" SIZE_FORMAT "%s ", 908 byte_size_in_proper_unit(allocated_bytes), 909 proper_unit_for_byte_size(allocated_bytes) 910 ); 911 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 912 } 913 914 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 915 osthread()->print_on(st); 916 } 917 ThreadsSMRSupport::print_info_on(this, st); 918 st->print(" "); 919 debug_only(if (WizardMode) print_owned_locks_on(st);) 920 } 921 922 // Thread::print_on_error() is called by fatal error handler. Don't use 923 // any lock or allocate memory. 924 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 925 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 926 927 if (is_VM_thread()) { st->print("VMThread"); } 928 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 929 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 930 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 931 else { st->print("Thread"); } 932 933 if (is_Named_thread()) { 934 st->print(" \"%s\"", name()); 935 } 936 937 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 938 p2i(stack_end()), p2i(stack_base())); 939 940 if (osthread()) { 941 st->print(" [id=%d]", osthread()->thread_id()); 942 } 943 944 ThreadsSMRSupport::print_info_on(this, st); 945 } 946 947 void Thread::print_value_on(outputStream* st) const { 948 if (is_Named_thread()) { 949 st->print(" \"%s\" ", name()); 950 } 951 st->print(INTPTR_FORMAT, p2i(this)); // print address 952 } 953 954 #ifdef ASSERT 955 void Thread::print_owned_locks_on(outputStream* st) const { 956 Monitor *cur = _owned_locks; 957 if (cur == NULL) { 958 st->print(" (no locks) "); 959 } else { 960 st->print_cr(" Locks owned:"); 961 while (cur) { 962 cur->print_on(st); 963 cur = cur->next(); 964 } 965 } 966 } 967 968 static int ref_use_count = 0; 969 970 bool Thread::owns_locks_but_compiled_lock() const { 971 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 972 if (cur != Compile_lock) return true; 973 } 974 return false; 975 } 976 977 978 #endif 979 980 #ifndef PRODUCT 981 982 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 983 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 984 // no locks which allow_vm_block's are held 985 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 986 // Check if current thread is allowed to block at a safepoint 987 if (!(_allow_safepoint_count == 0)) { 988 fatal("Possible safepoint reached by thread that does not allow it"); 989 } 990 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 991 fatal("LEAF method calling lock?"); 992 } 993 994 #ifdef ASSERT 995 if (potential_vm_operation && is_Java_thread() 996 && !Universe::is_bootstrapping()) { 997 // Make sure we do not hold any locks that the VM thread also uses. 998 // This could potentially lead to deadlocks 999 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1000 // Threads_lock is special, since the safepoint synchronization will not start before this is 1001 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1002 // since it is used to transfer control between JavaThreads and the VMThread 1003 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1004 if ((cur->allow_vm_block() && 1005 cur != Threads_lock && 1006 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1007 cur != VMOperationRequest_lock && 1008 cur != VMOperationQueue_lock) || 1009 cur->rank() == Mutex::special) { 1010 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1011 } 1012 } 1013 } 1014 1015 if (GCALotAtAllSafepoints) { 1016 // We could enter a safepoint here and thus have a gc 1017 InterfaceSupport::check_gc_alot(); 1018 } 1019 #endif 1020 } 1021 #endif 1022 1023 bool Thread::is_in_stack(address adr) const { 1024 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1025 address end = os::current_stack_pointer(); 1026 // Allow non Java threads to call this without stack_base 1027 if (_stack_base == NULL) return true; 1028 if (stack_base() >= adr && adr >= end) return true; 1029 1030 return false; 1031 } 1032 1033 bool Thread::is_in_usable_stack(address adr) const { 1034 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1035 size_t usable_stack_size = _stack_size - stack_guard_size; 1036 1037 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1038 } 1039 1040 1041 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1042 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1043 // used for compilation in the future. If that change is made, the need for these methods 1044 // should be revisited, and they should be removed if possible. 1045 1046 bool Thread::is_lock_owned(address adr) const { 1047 return on_local_stack(adr); 1048 } 1049 1050 bool Thread::set_as_starting_thread() { 1051 // NOTE: this must be called inside the main thread. 1052 return os::create_main_thread((JavaThread*)this); 1053 } 1054 1055 static void initialize_class(Symbol* class_name, TRAPS) { 1056 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1057 InstanceKlass::cast(klass)->initialize(CHECK); 1058 } 1059 1060 1061 // Creates the initial ThreadGroup 1062 static Handle create_initial_thread_group(TRAPS) { 1063 Handle system_instance = JavaCalls::construct_new_instance( 1064 SystemDictionary::ThreadGroup_klass(), 1065 vmSymbols::void_method_signature(), 1066 CHECK_NH); 1067 Universe::set_system_thread_group(system_instance()); 1068 1069 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1070 Handle main_instance = JavaCalls::construct_new_instance( 1071 SystemDictionary::ThreadGroup_klass(), 1072 vmSymbols::threadgroup_string_void_signature(), 1073 system_instance, 1074 string, 1075 CHECK_NH); 1076 return main_instance; 1077 } 1078 1079 // Creates the initial Thread 1080 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1081 TRAPS) { 1082 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1083 assert(ik->is_initialized(), "must be"); 1084 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1085 1086 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1087 // constructor calls Thread.current(), which must be set here for the 1088 // initial thread. 1089 java_lang_Thread::set_thread(thread_oop(), thread); 1090 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1091 thread->set_threadObj(thread_oop()); 1092 1093 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1094 1095 JavaValue result(T_VOID); 1096 JavaCalls::call_special(&result, thread_oop, 1097 ik, 1098 vmSymbols::object_initializer_name(), 1099 vmSymbols::threadgroup_string_void_signature(), 1100 thread_group, 1101 string, 1102 CHECK_NULL); 1103 return thread_oop(); 1104 } 1105 1106 char java_runtime_name[128] = ""; 1107 char java_runtime_version[128] = ""; 1108 1109 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1110 static const char* get_java_runtime_name(TRAPS) { 1111 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1112 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1113 fieldDescriptor fd; 1114 bool found = k != NULL && 1115 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1116 vmSymbols::string_signature(), &fd); 1117 if (found) { 1118 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1119 if (name_oop == NULL) { 1120 return NULL; 1121 } 1122 const char* name = java_lang_String::as_utf8_string(name_oop, 1123 java_runtime_name, 1124 sizeof(java_runtime_name)); 1125 return name; 1126 } else { 1127 return NULL; 1128 } 1129 } 1130 1131 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1132 static const char* get_java_runtime_version(TRAPS) { 1133 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1134 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1135 fieldDescriptor fd; 1136 bool found = k != NULL && 1137 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1138 vmSymbols::string_signature(), &fd); 1139 if (found) { 1140 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1141 if (name_oop == NULL) { 1142 return NULL; 1143 } 1144 const char* name = java_lang_String::as_utf8_string(name_oop, 1145 java_runtime_version, 1146 sizeof(java_runtime_version)); 1147 return name; 1148 } else { 1149 return NULL; 1150 } 1151 } 1152 1153 // General purpose hook into Java code, run once when the VM is initialized. 1154 // The Java library method itself may be changed independently from the VM. 1155 static void call_postVMInitHook(TRAPS) { 1156 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1157 if (klass != NULL) { 1158 JavaValue result(T_VOID); 1159 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1160 vmSymbols::void_method_signature(), 1161 CHECK); 1162 } 1163 } 1164 1165 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1166 bool daemon, TRAPS) { 1167 assert(thread_group.not_null(), "thread group should be specified"); 1168 assert(threadObj() == NULL, "should only create Java thread object once"); 1169 1170 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1171 assert(ik->is_initialized(), "must be"); 1172 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1173 1174 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1175 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1176 // constructor calls Thread.current(), which must be set here. 1177 java_lang_Thread::set_thread(thread_oop(), this); 1178 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1179 set_threadObj(thread_oop()); 1180 1181 JavaValue result(T_VOID); 1182 if (thread_name != NULL) { 1183 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1184 // Thread gets assigned specified name and null target 1185 JavaCalls::call_special(&result, 1186 thread_oop, 1187 ik, 1188 vmSymbols::object_initializer_name(), 1189 vmSymbols::threadgroup_string_void_signature(), 1190 thread_group, 1191 name, 1192 THREAD); 1193 } else { 1194 // Thread gets assigned name "Thread-nnn" and null target 1195 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1196 JavaCalls::call_special(&result, 1197 thread_oop, 1198 ik, 1199 vmSymbols::object_initializer_name(), 1200 vmSymbols::threadgroup_runnable_void_signature(), 1201 thread_group, 1202 Handle(), 1203 THREAD); 1204 } 1205 1206 1207 if (daemon) { 1208 java_lang_Thread::set_daemon(thread_oop()); 1209 } 1210 1211 if (HAS_PENDING_EXCEPTION) { 1212 return; 1213 } 1214 1215 Klass* group = SystemDictionary::ThreadGroup_klass(); 1216 Handle threadObj(THREAD, this->threadObj()); 1217 1218 JavaCalls::call_special(&result, 1219 thread_group, 1220 group, 1221 vmSymbols::add_method_name(), 1222 vmSymbols::thread_void_signature(), 1223 threadObj, // Arg 1 1224 THREAD); 1225 } 1226 1227 // List of all NonJavaThreads and safe iteration over that list. 1228 1229 class NonJavaThread::List { 1230 public: 1231 NonJavaThread* volatile _head; 1232 SingleWriterSynchronizer _protect; 1233 1234 List() : _head(NULL), _protect() {} 1235 }; 1236 1237 NonJavaThread::List NonJavaThread::_the_list; 1238 1239 NonJavaThread::Iterator::Iterator() : 1240 _protect_enter(_the_list._protect.enter()), 1241 _current(OrderAccess::load_acquire(&_the_list._head)) 1242 {} 1243 1244 NonJavaThread::Iterator::~Iterator() { 1245 _the_list._protect.exit(_protect_enter); 1246 } 1247 1248 void NonJavaThread::Iterator::step() { 1249 assert(!end(), "precondition"); 1250 _current = OrderAccess::load_acquire(&_current->_next); 1251 } 1252 1253 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1254 // Add this thread to _the_list. 1255 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1256 _next = _the_list._head; 1257 OrderAccess::release_store(&_the_list._head, this); 1258 } 1259 1260 NonJavaThread::~NonJavaThread() { 1261 // Remove this thread from _the_list. 1262 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1263 NonJavaThread* volatile* p = &_the_list._head; 1264 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1265 if (t == this) { 1266 *p = this->_next; 1267 // Wait for any in-progress iterators. 1268 _the_list._protect.synchronize(); 1269 break; 1270 } 1271 } 1272 } 1273 1274 // NamedThread -- non-JavaThread subclasses with multiple 1275 // uniquely named instances should derive from this. 1276 NamedThread::NamedThread() : 1277 NonJavaThread(), 1278 _name(NULL), 1279 _processed_thread(NULL), 1280 _gc_id(GCId::undefined()) 1281 {} 1282 1283 NamedThread::~NamedThread() { 1284 if (_name != NULL) { 1285 FREE_C_HEAP_ARRAY(char, _name); 1286 _name = NULL; 1287 } 1288 } 1289 1290 void NamedThread::set_name(const char* format, ...) { 1291 guarantee(_name == NULL, "Only get to set name once."); 1292 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1293 guarantee(_name != NULL, "alloc failure"); 1294 va_list ap; 1295 va_start(ap, format); 1296 jio_vsnprintf(_name, max_name_len, format, ap); 1297 va_end(ap); 1298 } 1299 1300 void NamedThread::initialize_named_thread() { 1301 set_native_thread_name(name()); 1302 } 1303 1304 void NamedThread::print_on(outputStream* st) const { 1305 st->print("\"%s\" ", name()); 1306 Thread::print_on(st); 1307 st->cr(); 1308 } 1309 1310 1311 // ======= WatcherThread ======== 1312 1313 // The watcher thread exists to simulate timer interrupts. It should 1314 // be replaced by an abstraction over whatever native support for 1315 // timer interrupts exists on the platform. 1316 1317 WatcherThread* WatcherThread::_watcher_thread = NULL; 1318 bool WatcherThread::_startable = false; 1319 volatile bool WatcherThread::_should_terminate = false; 1320 1321 WatcherThread::WatcherThread() : NonJavaThread() { 1322 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1323 if (os::create_thread(this, os::watcher_thread)) { 1324 _watcher_thread = this; 1325 1326 // Set the watcher thread to the highest OS priority which should not be 1327 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1328 // is created. The only normal thread using this priority is the reference 1329 // handler thread, which runs for very short intervals only. 1330 // If the VMThread's priority is not lower than the WatcherThread profiling 1331 // will be inaccurate. 1332 os::set_priority(this, MaxPriority); 1333 if (!DisableStartThread) { 1334 os::start_thread(this); 1335 } 1336 } 1337 } 1338 1339 int WatcherThread::sleep() const { 1340 // The WatcherThread does not participate in the safepoint protocol 1341 // for the PeriodicTask_lock because it is not a JavaThread. 1342 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1343 1344 if (_should_terminate) { 1345 // check for termination before we do any housekeeping or wait 1346 return 0; // we did not sleep. 1347 } 1348 1349 // remaining will be zero if there are no tasks, 1350 // causing the WatcherThread to sleep until a task is 1351 // enrolled 1352 int remaining = PeriodicTask::time_to_wait(); 1353 int time_slept = 0; 1354 1355 // we expect this to timeout - we only ever get unparked when 1356 // we should terminate or when a new task has been enrolled 1357 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1358 1359 jlong time_before_loop = os::javaTimeNanos(); 1360 1361 while (true) { 1362 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1363 remaining); 1364 jlong now = os::javaTimeNanos(); 1365 1366 if (remaining == 0) { 1367 // if we didn't have any tasks we could have waited for a long time 1368 // consider the time_slept zero and reset time_before_loop 1369 time_slept = 0; 1370 time_before_loop = now; 1371 } else { 1372 // need to recalculate since we might have new tasks in _tasks 1373 time_slept = (int) ((now - time_before_loop) / 1000000); 1374 } 1375 1376 // Change to task list or spurious wakeup of some kind 1377 if (timedout || _should_terminate) { 1378 break; 1379 } 1380 1381 remaining = PeriodicTask::time_to_wait(); 1382 if (remaining == 0) { 1383 // Last task was just disenrolled so loop around and wait until 1384 // another task gets enrolled 1385 continue; 1386 } 1387 1388 remaining -= time_slept; 1389 if (remaining <= 0) { 1390 break; 1391 } 1392 } 1393 1394 return time_slept; 1395 } 1396 1397 void WatcherThread::run() { 1398 assert(this == watcher_thread(), "just checking"); 1399 1400 this->set_native_thread_name(this->name()); 1401 this->set_active_handles(JNIHandleBlock::allocate_block()); 1402 while (true) { 1403 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1404 assert(watcher_thread() == this, "thread consistency check"); 1405 1406 // Calculate how long it'll be until the next PeriodicTask work 1407 // should be done, and sleep that amount of time. 1408 int time_waited = sleep(); 1409 1410 if (VMError::is_error_reported()) { 1411 // A fatal error has happened, the error handler(VMError::report_and_die) 1412 // should abort JVM after creating an error log file. However in some 1413 // rare cases, the error handler itself might deadlock. Here periodically 1414 // check for error reporting timeouts, and if it happens, just proceed to 1415 // abort the VM. 1416 1417 // This code is in WatcherThread because WatcherThread wakes up 1418 // periodically so the fatal error handler doesn't need to do anything; 1419 // also because the WatcherThread is less likely to crash than other 1420 // threads. 1421 1422 for (;;) { 1423 // Note: we use naked sleep in this loop because we want to avoid using 1424 // any kind of VM infrastructure which may be broken at this point. 1425 if (VMError::check_timeout()) { 1426 // We hit error reporting timeout. Error reporting was interrupted and 1427 // will be wrapping things up now (closing files etc). Give it some more 1428 // time, then quit the VM. 1429 os::naked_short_sleep(200); 1430 // Print a message to stderr. 1431 fdStream err(defaultStream::output_fd()); 1432 err.print_raw_cr("# [ timer expired, abort... ]"); 1433 // skip atexit/vm_exit/vm_abort hooks 1434 os::die(); 1435 } 1436 1437 // Wait a second, then recheck for timeout. 1438 os::naked_short_sleep(999); 1439 } 1440 } 1441 1442 if (_should_terminate) { 1443 // check for termination before posting the next tick 1444 break; 1445 } 1446 1447 PeriodicTask::real_time_tick(time_waited); 1448 } 1449 1450 // Signal that it is terminated 1451 { 1452 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1453 _watcher_thread = NULL; 1454 Terminator_lock->notify(); 1455 } 1456 } 1457 1458 void WatcherThread::start() { 1459 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1460 1461 if (watcher_thread() == NULL && _startable) { 1462 _should_terminate = false; 1463 // Create the single instance of WatcherThread 1464 new WatcherThread(); 1465 } 1466 } 1467 1468 void WatcherThread::make_startable() { 1469 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1470 _startable = true; 1471 } 1472 1473 void WatcherThread::stop() { 1474 { 1475 // Follow normal safepoint aware lock enter protocol since the 1476 // WatcherThread is stopped by another JavaThread. 1477 MutexLocker ml(PeriodicTask_lock); 1478 _should_terminate = true; 1479 1480 WatcherThread* watcher = watcher_thread(); 1481 if (watcher != NULL) { 1482 // unpark the WatcherThread so it can see that it should terminate 1483 watcher->unpark(); 1484 } 1485 } 1486 1487 MutexLocker mu(Terminator_lock); 1488 1489 while (watcher_thread() != NULL) { 1490 // This wait should make safepoint checks, wait without a timeout, 1491 // and wait as a suspend-equivalent condition. 1492 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1493 Mutex::_as_suspend_equivalent_flag); 1494 } 1495 } 1496 1497 void WatcherThread::unpark() { 1498 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1499 PeriodicTask_lock->notify(); 1500 } 1501 1502 void WatcherThread::print_on(outputStream* st) const { 1503 st->print("\"%s\" ", name()); 1504 Thread::print_on(st); 1505 st->cr(); 1506 } 1507 1508 // ======= JavaThread ======== 1509 1510 #if INCLUDE_JVMCI 1511 1512 jlong* JavaThread::_jvmci_old_thread_counters; 1513 1514 bool jvmci_counters_include(JavaThread* thread) { 1515 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1516 } 1517 1518 void JavaThread::collect_counters(typeArrayOop array) { 1519 if (JVMCICounterSize > 0) { 1520 JavaThreadIteratorWithHandle jtiwh; 1521 for (int i = 0; i < array->length(); i++) { 1522 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1523 } 1524 for (; JavaThread *tp = jtiwh.next(); ) { 1525 if (jvmci_counters_include(tp)) { 1526 for (int i = 0; i < array->length(); i++) { 1527 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1528 } 1529 } 1530 } 1531 } 1532 } 1533 1534 #endif // INCLUDE_JVMCI 1535 1536 // A JavaThread is a normal Java thread 1537 1538 void JavaThread::initialize() { 1539 // Initialize fields 1540 1541 set_saved_exception_pc(NULL); 1542 set_threadObj(NULL); 1543 _anchor.clear(); 1544 set_entry_point(NULL); 1545 set_jni_functions(jni_functions()); 1546 set_callee_target(NULL); 1547 set_vm_result(NULL); 1548 set_vm_result_2(NULL); 1549 set_vframe_array_head(NULL); 1550 set_vframe_array_last(NULL); 1551 set_deferred_locals(NULL); 1552 set_deopt_mark(NULL); 1553 set_deopt_compiled_method(NULL); 1554 clear_must_deopt_id(); 1555 set_monitor_chunks(NULL); 1556 set_next(NULL); 1557 _on_thread_list = false; 1558 set_thread_state(_thread_new); 1559 _terminated = _not_terminated; 1560 _array_for_gc = NULL; 1561 _suspend_equivalent = false; 1562 _in_deopt_handler = 0; 1563 _doing_unsafe_access = false; 1564 _stack_guard_state = stack_guard_unused; 1565 #if INCLUDE_JVMCI 1566 _pending_monitorenter = false; 1567 _pending_deoptimization = -1; 1568 _pending_failed_speculation = 0; 1569 _pending_transfer_to_interpreter = false; 1570 _adjusting_comp_level = false; 1571 _in_retryable_allocation = false; 1572 _jvmci._alternate_call_target = NULL; 1573 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1574 if (JVMCICounterSize > 0) { 1575 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1576 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1577 } else { 1578 _jvmci_counters = NULL; 1579 } 1580 #endif // INCLUDE_JVMCI 1581 _reserved_stack_activation = NULL; // stack base not known yet 1582 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1583 _exception_pc = 0; 1584 _exception_handler_pc = 0; 1585 _is_method_handle_return = 0; 1586 _jvmti_thread_state= NULL; 1587 _should_post_on_exceptions_flag = JNI_FALSE; 1588 _interp_only_mode = 0; 1589 _special_runtime_exit_condition = _no_async_condition; 1590 _pending_async_exception = NULL; 1591 _thread_stat = NULL; 1592 _thread_stat = new ThreadStatistics(); 1593 _blocked_on_compilation = false; 1594 _jni_active_critical = 0; 1595 _pending_jni_exception_check_fn = NULL; 1596 _do_not_unlock_if_synchronized = false; 1597 _cached_monitor_info = NULL; 1598 _parker = Parker::Allocate(this); 1599 1600 #ifndef PRODUCT 1601 _jmp_ring_index = 0; 1602 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1603 record_jump(NULL, NULL, NULL, 0); 1604 } 1605 #endif // PRODUCT 1606 1607 // Setup safepoint state info for this thread 1608 ThreadSafepointState::create(this); 1609 1610 debug_only(_java_call_counter = 0); 1611 1612 // JVMTI PopFrame support 1613 _popframe_condition = popframe_inactive; 1614 _popframe_preserved_args = NULL; 1615 _popframe_preserved_args_size = 0; 1616 _frames_to_pop_failed_realloc = 0; 1617 1618 if (SafepointMechanism::uses_thread_local_poll()) { 1619 SafepointMechanism::initialize_header(this); 1620 } 1621 1622 pd_initialize(); 1623 } 1624 1625 JavaThread::JavaThread(bool is_attaching_via_jni) : 1626 Thread() { 1627 initialize(); 1628 if (is_attaching_via_jni) { 1629 _jni_attach_state = _attaching_via_jni; 1630 } else { 1631 _jni_attach_state = _not_attaching_via_jni; 1632 } 1633 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1634 } 1635 1636 bool JavaThread::reguard_stack(address cur_sp) { 1637 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1638 && _stack_guard_state != stack_guard_reserved_disabled) { 1639 return true; // Stack already guarded or guard pages not needed. 1640 } 1641 1642 if (register_stack_overflow()) { 1643 // For those architectures which have separate register and 1644 // memory stacks, we must check the register stack to see if 1645 // it has overflowed. 1646 return false; 1647 } 1648 1649 // Java code never executes within the yellow zone: the latter is only 1650 // there to provoke an exception during stack banging. If java code 1651 // is executing there, either StackShadowPages should be larger, or 1652 // some exception code in c1, c2 or the interpreter isn't unwinding 1653 // when it should. 1654 guarantee(cur_sp > stack_reserved_zone_base(), 1655 "not enough space to reguard - increase StackShadowPages"); 1656 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1657 enable_stack_yellow_reserved_zone(); 1658 if (reserved_stack_activation() != stack_base()) { 1659 set_reserved_stack_activation(stack_base()); 1660 } 1661 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1662 set_reserved_stack_activation(stack_base()); 1663 enable_stack_reserved_zone(); 1664 } 1665 return true; 1666 } 1667 1668 bool JavaThread::reguard_stack(void) { 1669 return reguard_stack(os::current_stack_pointer()); 1670 } 1671 1672 1673 void JavaThread::block_if_vm_exited() { 1674 if (_terminated == _vm_exited) { 1675 // _vm_exited is set at safepoint, and Threads_lock is never released 1676 // we will block here forever 1677 Threads_lock->lock_without_safepoint_check(); 1678 ShouldNotReachHere(); 1679 } 1680 } 1681 1682 1683 // Remove this ifdef when C1 is ported to the compiler interface. 1684 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1685 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1686 1687 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1688 Thread() { 1689 initialize(); 1690 _jni_attach_state = _not_attaching_via_jni; 1691 set_entry_point(entry_point); 1692 // Create the native thread itself. 1693 // %note runtime_23 1694 os::ThreadType thr_type = os::java_thread; 1695 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1696 os::java_thread; 1697 os::create_thread(this, thr_type, stack_sz); 1698 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1699 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1700 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1701 // the exception consists of creating the exception object & initializing it, initialization 1702 // will leave the VM via a JavaCall and then all locks must be unlocked). 1703 // 1704 // The thread is still suspended when we reach here. Thread must be explicit started 1705 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1706 // by calling Threads:add. The reason why this is not done here, is because the thread 1707 // object must be fully initialized (take a look at JVM_Start) 1708 } 1709 1710 JavaThread::~JavaThread() { 1711 1712 // JSR166 -- return the parker to the free list 1713 Parker::Release(_parker); 1714 _parker = NULL; 1715 1716 // Free any remaining previous UnrollBlock 1717 vframeArray* old_array = vframe_array_last(); 1718 1719 if (old_array != NULL) { 1720 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1721 old_array->set_unroll_block(NULL); 1722 delete old_info; 1723 delete old_array; 1724 } 1725 1726 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1727 if (deferred != NULL) { 1728 // This can only happen if thread is destroyed before deoptimization occurs. 1729 assert(deferred->length() != 0, "empty array!"); 1730 do { 1731 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1732 deferred->remove_at(0); 1733 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1734 delete dlv; 1735 } while (deferred->length() != 0); 1736 delete deferred; 1737 } 1738 1739 // All Java related clean up happens in exit 1740 ThreadSafepointState::destroy(this); 1741 if (_thread_stat != NULL) delete _thread_stat; 1742 1743 #if INCLUDE_JVMCI 1744 if (JVMCICounterSize > 0) { 1745 if (jvmci_counters_include(this)) { 1746 for (int i = 0; i < JVMCICounterSize; i++) { 1747 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1748 } 1749 } 1750 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1751 } 1752 #endif // INCLUDE_JVMCI 1753 } 1754 1755 1756 // The first routine called by a new Java thread 1757 void JavaThread::run() { 1758 // initialize thread-local alloc buffer related fields 1759 this->initialize_tlab(); 1760 1761 // used to test validity of stack trace backs 1762 this->record_base_of_stack_pointer(); 1763 1764 this->create_stack_guard_pages(); 1765 1766 this->cache_global_variables(); 1767 1768 // Thread is now sufficient initialized to be handled by the safepoint code as being 1769 // in the VM. Change thread state from _thread_new to _thread_in_vm 1770 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1771 1772 assert(JavaThread::current() == this, "sanity check"); 1773 assert(!Thread::current()->owns_locks(), "sanity check"); 1774 1775 DTRACE_THREAD_PROBE(start, this); 1776 1777 // This operation might block. We call that after all safepoint checks for a new thread has 1778 // been completed. 1779 this->set_active_handles(JNIHandleBlock::allocate_block()); 1780 1781 if (JvmtiExport::should_post_thread_life()) { 1782 JvmtiExport::post_thread_start(this); 1783 } 1784 1785 EventThreadStart event; 1786 if (event.should_commit()) { 1787 event.set_thread(JFR_THREAD_ID(this)); 1788 event.commit(); 1789 } 1790 1791 // We call another function to do the rest so we are sure that the stack addresses used 1792 // from there will be lower than the stack base just computed 1793 thread_main_inner(); 1794 1795 // Note, thread is no longer valid at this point! 1796 } 1797 1798 1799 void JavaThread::thread_main_inner() { 1800 assert(JavaThread::current() == this, "sanity check"); 1801 assert(this->threadObj() != NULL, "just checking"); 1802 1803 // Execute thread entry point unless this thread has a pending exception 1804 // or has been stopped before starting. 1805 // Note: Due to JVM_StopThread we can have pending exceptions already! 1806 if (!this->has_pending_exception() && 1807 !java_lang_Thread::is_stillborn(this->threadObj())) { 1808 { 1809 ResourceMark rm(this); 1810 this->set_native_thread_name(this->get_thread_name()); 1811 } 1812 HandleMark hm(this); 1813 this->entry_point()(this, this); 1814 } 1815 1816 DTRACE_THREAD_PROBE(stop, this); 1817 1818 this->exit(false); 1819 this->smr_delete(); 1820 } 1821 1822 1823 static void ensure_join(JavaThread* thread) { 1824 // We do not need to grab the Threads_lock, since we are operating on ourself. 1825 Handle threadObj(thread, thread->threadObj()); 1826 assert(threadObj.not_null(), "java thread object must exist"); 1827 ObjectLocker lock(threadObj, thread); 1828 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1829 thread->clear_pending_exception(); 1830 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1831 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1832 // Clear the native thread instance - this makes isAlive return false and allows the join() 1833 // to complete once we've done the notify_all below 1834 java_lang_Thread::set_thread(threadObj(), NULL); 1835 lock.notify_all(thread); 1836 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1837 thread->clear_pending_exception(); 1838 } 1839 1840 static bool is_daemon(oop threadObj) { 1841 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1842 } 1843 1844 // For any new cleanup additions, please check to see if they need to be applied to 1845 // cleanup_failed_attach_current_thread as well. 1846 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1847 assert(this == JavaThread::current(), "thread consistency check"); 1848 1849 elapsedTimer _timer_exit_phase1; 1850 elapsedTimer _timer_exit_phase2; 1851 elapsedTimer _timer_exit_phase3; 1852 elapsedTimer _timer_exit_phase4; 1853 1854 if (log_is_enabled(Debug, os, thread, timer)) { 1855 _timer_exit_phase1.start(); 1856 } 1857 1858 HandleMark hm(this); 1859 Handle uncaught_exception(this, this->pending_exception()); 1860 this->clear_pending_exception(); 1861 Handle threadObj(this, this->threadObj()); 1862 assert(threadObj.not_null(), "Java thread object should be created"); 1863 1864 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1865 { 1866 EXCEPTION_MARK; 1867 1868 CLEAR_PENDING_EXCEPTION; 1869 } 1870 if (!destroy_vm) { 1871 if (uncaught_exception.not_null()) { 1872 EXCEPTION_MARK; 1873 // Call method Thread.dispatchUncaughtException(). 1874 Klass* thread_klass = SystemDictionary::Thread_klass(); 1875 JavaValue result(T_VOID); 1876 JavaCalls::call_virtual(&result, 1877 threadObj, thread_klass, 1878 vmSymbols::dispatchUncaughtException_name(), 1879 vmSymbols::throwable_void_signature(), 1880 uncaught_exception, 1881 THREAD); 1882 if (HAS_PENDING_EXCEPTION) { 1883 ResourceMark rm(this); 1884 jio_fprintf(defaultStream::error_stream(), 1885 "\nException: %s thrown from the UncaughtExceptionHandler" 1886 " in thread \"%s\"\n", 1887 pending_exception()->klass()->external_name(), 1888 get_thread_name()); 1889 CLEAR_PENDING_EXCEPTION; 1890 } 1891 } 1892 1893 // Called before the java thread exit since we want to read info 1894 // from java_lang_Thread object 1895 EventThreadEnd event; 1896 if (event.should_commit()) { 1897 event.set_thread(JFR_THREAD_ID(this)); 1898 event.commit(); 1899 } 1900 1901 // Call after last event on thread 1902 JFR_ONLY(Jfr::on_thread_exit(this);) 1903 1904 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1905 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1906 // is deprecated anyhow. 1907 if (!is_Compiler_thread()) { 1908 int count = 3; 1909 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1910 EXCEPTION_MARK; 1911 JavaValue result(T_VOID); 1912 Klass* thread_klass = SystemDictionary::Thread_klass(); 1913 JavaCalls::call_virtual(&result, 1914 threadObj, thread_klass, 1915 vmSymbols::exit_method_name(), 1916 vmSymbols::void_method_signature(), 1917 THREAD); 1918 CLEAR_PENDING_EXCEPTION; 1919 } 1920 } 1921 // notify JVMTI 1922 if (JvmtiExport::should_post_thread_life()) { 1923 JvmtiExport::post_thread_end(this); 1924 } 1925 1926 // We have notified the agents that we are exiting, before we go on, 1927 // we must check for a pending external suspend request and honor it 1928 // in order to not surprise the thread that made the suspend request. 1929 while (true) { 1930 { 1931 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1932 if (!is_external_suspend()) { 1933 set_terminated(_thread_exiting); 1934 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 1935 break; 1936 } 1937 // Implied else: 1938 // Things get a little tricky here. We have a pending external 1939 // suspend request, but we are holding the SR_lock so we 1940 // can't just self-suspend. So we temporarily drop the lock 1941 // and then self-suspend. 1942 } 1943 1944 ThreadBlockInVM tbivm(this); 1945 java_suspend_self(); 1946 1947 // We're done with this suspend request, but we have to loop around 1948 // and check again. Eventually we will get SR_lock without a pending 1949 // external suspend request and will be able to mark ourselves as 1950 // exiting. 1951 } 1952 // no more external suspends are allowed at this point 1953 } else { 1954 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 1955 // before_exit() has already posted JVMTI THREAD_END events 1956 } 1957 1958 if (log_is_enabled(Debug, os, thread, timer)) { 1959 _timer_exit_phase1.stop(); 1960 _timer_exit_phase2.start(); 1961 } 1962 // Notify waiters on thread object. This has to be done after exit() is called 1963 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1964 // group should have the destroyed bit set before waiters are notified). 1965 ensure_join(this); 1966 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1967 1968 if (log_is_enabled(Debug, os, thread, timer)) { 1969 _timer_exit_phase2.stop(); 1970 _timer_exit_phase3.start(); 1971 } 1972 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1973 // held by this thread must be released. The spec does not distinguish 1974 // between JNI-acquired and regular Java monitors. We can only see 1975 // regular Java monitors here if monitor enter-exit matching is broken. 1976 // 1977 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1978 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1979 if (exit_type == jni_detach) { 1980 // Sanity check even though JNI DetachCurrentThread() would have 1981 // returned JNI_ERR if there was a Java frame. JavaThread exit 1982 // should be done executing Java code by the time we get here. 1983 assert(!this->has_last_Java_frame(), 1984 "should not have a Java frame when detaching or exiting"); 1985 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1986 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1987 } 1988 1989 // These things needs to be done while we are still a Java Thread. Make sure that thread 1990 // is in a consistent state, in case GC happens 1991 1992 if (active_handles() != NULL) { 1993 JNIHandleBlock* block = active_handles(); 1994 set_active_handles(NULL); 1995 JNIHandleBlock::release_block(block); 1996 } 1997 1998 if (free_handle_block() != NULL) { 1999 JNIHandleBlock* block = free_handle_block(); 2000 set_free_handle_block(NULL); 2001 JNIHandleBlock::release_block(block); 2002 } 2003 2004 // These have to be removed while this is still a valid thread. 2005 remove_stack_guard_pages(); 2006 2007 if (UseTLAB) { 2008 tlab().retire(); 2009 } 2010 2011 if (JvmtiEnv::environments_might_exist()) { 2012 JvmtiExport::cleanup_thread(this); 2013 } 2014 2015 // We must flush any deferred card marks and other various GC barrier 2016 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2017 // before removing a thread from the list of active threads. 2018 BarrierSet::barrier_set()->on_thread_detach(this); 2019 2020 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2021 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2022 os::current_thread_id()); 2023 2024 if (log_is_enabled(Debug, os, thread, timer)) { 2025 _timer_exit_phase3.stop(); 2026 _timer_exit_phase4.start(); 2027 } 2028 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2029 Threads::remove(this); 2030 2031 if (log_is_enabled(Debug, os, thread, timer)) { 2032 _timer_exit_phase4.stop(); 2033 ResourceMark rm(this); 2034 log_debug(os, thread, timer)("name='%s'" 2035 ", exit-phase1=" JLONG_FORMAT 2036 ", exit-phase2=" JLONG_FORMAT 2037 ", exit-phase3=" JLONG_FORMAT 2038 ", exit-phase4=" JLONG_FORMAT, 2039 get_thread_name(), 2040 _timer_exit_phase1.milliseconds(), 2041 _timer_exit_phase2.milliseconds(), 2042 _timer_exit_phase3.milliseconds(), 2043 _timer_exit_phase4.milliseconds()); 2044 } 2045 } 2046 2047 void JavaThread::cleanup_failed_attach_current_thread() { 2048 if (active_handles() != NULL) { 2049 JNIHandleBlock* block = active_handles(); 2050 set_active_handles(NULL); 2051 JNIHandleBlock::release_block(block); 2052 } 2053 2054 if (free_handle_block() != NULL) { 2055 JNIHandleBlock* block = free_handle_block(); 2056 set_free_handle_block(NULL); 2057 JNIHandleBlock::release_block(block); 2058 } 2059 2060 // These have to be removed while this is still a valid thread. 2061 remove_stack_guard_pages(); 2062 2063 if (UseTLAB) { 2064 tlab().retire(); 2065 } 2066 2067 BarrierSet::barrier_set()->on_thread_detach(this); 2068 2069 Threads::remove(this); 2070 this->smr_delete(); 2071 } 2072 2073 JavaThread* JavaThread::active() { 2074 Thread* thread = Thread::current(); 2075 if (thread->is_Java_thread()) { 2076 return (JavaThread*) thread; 2077 } else { 2078 assert(thread->is_VM_thread(), "this must be a vm thread"); 2079 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2080 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2081 assert(ret->is_Java_thread(), "must be a Java thread"); 2082 return ret; 2083 } 2084 } 2085 2086 bool JavaThread::is_lock_owned(address adr) const { 2087 if (Thread::is_lock_owned(adr)) return true; 2088 2089 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2090 if (chunk->contains(adr)) return true; 2091 } 2092 2093 return false; 2094 } 2095 2096 2097 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2098 chunk->set_next(monitor_chunks()); 2099 set_monitor_chunks(chunk); 2100 } 2101 2102 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2103 guarantee(monitor_chunks() != NULL, "must be non empty"); 2104 if (monitor_chunks() == chunk) { 2105 set_monitor_chunks(chunk->next()); 2106 } else { 2107 MonitorChunk* prev = monitor_chunks(); 2108 while (prev->next() != chunk) prev = prev->next(); 2109 prev->set_next(chunk->next()); 2110 } 2111 } 2112 2113 // JVM support. 2114 2115 // Note: this function shouldn't block if it's called in 2116 // _thread_in_native_trans state (such as from 2117 // check_special_condition_for_native_trans()). 2118 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2119 2120 if (has_last_Java_frame() && has_async_condition()) { 2121 // If we are at a polling page safepoint (not a poll return) 2122 // then we must defer async exception because live registers 2123 // will be clobbered by the exception path. Poll return is 2124 // ok because the call we a returning from already collides 2125 // with exception handling registers and so there is no issue. 2126 // (The exception handling path kills call result registers but 2127 // this is ok since the exception kills the result anyway). 2128 2129 if (is_at_poll_safepoint()) { 2130 // if the code we are returning to has deoptimized we must defer 2131 // the exception otherwise live registers get clobbered on the 2132 // exception path before deoptimization is able to retrieve them. 2133 // 2134 RegisterMap map(this, false); 2135 frame caller_fr = last_frame().sender(&map); 2136 assert(caller_fr.is_compiled_frame(), "what?"); 2137 if (caller_fr.is_deoptimized_frame()) { 2138 log_info(exceptions)("deferred async exception at compiled safepoint"); 2139 return; 2140 } 2141 } 2142 } 2143 2144 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2145 if (condition == _no_async_condition) { 2146 // Conditions have changed since has_special_runtime_exit_condition() 2147 // was called: 2148 // - if we were here only because of an external suspend request, 2149 // then that was taken care of above (or cancelled) so we are done 2150 // - if we were here because of another async request, then it has 2151 // been cleared between the has_special_runtime_exit_condition() 2152 // and now so again we are done 2153 return; 2154 } 2155 2156 // Check for pending async. exception 2157 if (_pending_async_exception != NULL) { 2158 // Only overwrite an already pending exception, if it is not a threadDeath. 2159 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2160 2161 // We cannot call Exceptions::_throw(...) here because we cannot block 2162 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2163 2164 LogTarget(Info, exceptions) lt; 2165 if (lt.is_enabled()) { 2166 ResourceMark rm; 2167 LogStream ls(lt); 2168 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2169 if (has_last_Java_frame()) { 2170 frame f = last_frame(); 2171 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2172 } 2173 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2174 } 2175 _pending_async_exception = NULL; 2176 clear_has_async_exception(); 2177 } 2178 } 2179 2180 if (check_unsafe_error && 2181 condition == _async_unsafe_access_error && !has_pending_exception()) { 2182 condition = _no_async_condition; // done 2183 switch (thread_state()) { 2184 case _thread_in_vm: { 2185 JavaThread* THREAD = this; 2186 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2187 } 2188 case _thread_in_native: { 2189 ThreadInVMfromNative tiv(this); 2190 JavaThread* THREAD = this; 2191 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2192 } 2193 case _thread_in_Java: { 2194 ThreadInVMfromJava tiv(this); 2195 JavaThread* THREAD = this; 2196 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2197 } 2198 default: 2199 ShouldNotReachHere(); 2200 } 2201 } 2202 2203 assert(condition == _no_async_condition || has_pending_exception() || 2204 (!check_unsafe_error && condition == _async_unsafe_access_error), 2205 "must have handled the async condition, if no exception"); 2206 } 2207 2208 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2209 // 2210 // Check for pending external suspend. Internal suspend requests do 2211 // not use handle_special_runtime_exit_condition(). 2212 // If JNIEnv proxies are allowed, don't self-suspend if the target 2213 // thread is not the current thread. In older versions of jdbx, jdbx 2214 // threads could call into the VM with another thread's JNIEnv so we 2215 // can be here operating on behalf of a suspended thread (4432884). 2216 bool do_self_suspend = is_external_suspend_with_lock(); 2217 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2218 // 2219 // Because thread is external suspended the safepoint code will count 2220 // thread as at a safepoint. This can be odd because we can be here 2221 // as _thread_in_Java which would normally transition to _thread_blocked 2222 // at a safepoint. We would like to mark the thread as _thread_blocked 2223 // before calling java_suspend_self like all other callers of it but 2224 // we must then observe proper safepoint protocol. (We can't leave 2225 // _thread_blocked with a safepoint in progress). However we can be 2226 // here as _thread_in_native_trans so we can't use a normal transition 2227 // constructor/destructor pair because they assert on that type of 2228 // transition. We could do something like: 2229 // 2230 // JavaThreadState state = thread_state(); 2231 // set_thread_state(_thread_in_vm); 2232 // { 2233 // ThreadBlockInVM tbivm(this); 2234 // java_suspend_self() 2235 // } 2236 // set_thread_state(_thread_in_vm_trans); 2237 // if (safepoint) block; 2238 // set_thread_state(state); 2239 // 2240 // but that is pretty messy. Instead we just go with the way the 2241 // code has worked before and note that this is the only path to 2242 // java_suspend_self that doesn't put the thread in _thread_blocked 2243 // mode. 2244 2245 frame_anchor()->make_walkable(this); 2246 java_suspend_self(); 2247 2248 // We might be here for reasons in addition to the self-suspend request 2249 // so check for other async requests. 2250 } 2251 2252 if (check_asyncs) { 2253 check_and_handle_async_exceptions(); 2254 } 2255 2256 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2257 } 2258 2259 void JavaThread::send_thread_stop(oop java_throwable) { 2260 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2261 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2262 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2263 2264 // Do not throw asynchronous exceptions against the compiler thread 2265 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2266 if (!can_call_java()) return; 2267 2268 { 2269 // Actually throw the Throwable against the target Thread - however 2270 // only if there is no thread death exception installed already. 2271 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2272 // If the topmost frame is a runtime stub, then we are calling into 2273 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2274 // must deoptimize the caller before continuing, as the compiled exception handler table 2275 // may not be valid 2276 if (has_last_Java_frame()) { 2277 frame f = last_frame(); 2278 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2279 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2280 RegisterMap reg_map(this, UseBiasedLocking); 2281 frame compiled_frame = f.sender(®_map); 2282 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2283 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2284 } 2285 } 2286 } 2287 2288 // Set async. pending exception in thread. 2289 set_pending_async_exception(java_throwable); 2290 2291 if (log_is_enabled(Info, exceptions)) { 2292 ResourceMark rm; 2293 log_info(exceptions)("Pending Async. exception installed of type: %s", 2294 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2295 } 2296 // for AbortVMOnException flag 2297 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2298 } 2299 } 2300 2301 2302 // Interrupt thread so it will wake up from a potential wait() 2303 Thread::interrupt(this); 2304 } 2305 2306 // External suspension mechanism. 2307 // 2308 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2309 // to any VM_locks and it is at a transition 2310 // Self-suspension will happen on the transition out of the vm. 2311 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2312 // 2313 // Guarantees on return: 2314 // + Target thread will not execute any new bytecode (that's why we need to 2315 // force a safepoint) 2316 // + Target thread will not enter any new monitors 2317 // 2318 void JavaThread::java_suspend() { 2319 ThreadsListHandle tlh; 2320 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2321 return; 2322 } 2323 2324 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2325 if (!is_external_suspend()) { 2326 // a racing resume has cancelled us; bail out now 2327 return; 2328 } 2329 2330 // suspend is done 2331 uint32_t debug_bits = 0; 2332 // Warning: is_ext_suspend_completed() may temporarily drop the 2333 // SR_lock to allow the thread to reach a stable thread state if 2334 // it is currently in a transient thread state. 2335 if (is_ext_suspend_completed(false /* !called_by_wait */, 2336 SuspendRetryDelay, &debug_bits)) { 2337 return; 2338 } 2339 } 2340 2341 VM_ThreadSuspend vm_suspend; 2342 VMThread::execute(&vm_suspend); 2343 } 2344 2345 // Part II of external suspension. 2346 // A JavaThread self suspends when it detects a pending external suspend 2347 // request. This is usually on transitions. It is also done in places 2348 // where continuing to the next transition would surprise the caller, 2349 // e.g., monitor entry. 2350 // 2351 // Returns the number of times that the thread self-suspended. 2352 // 2353 // Note: DO NOT call java_suspend_self() when you just want to block current 2354 // thread. java_suspend_self() is the second stage of cooperative 2355 // suspension for external suspend requests and should only be used 2356 // to complete an external suspend request. 2357 // 2358 int JavaThread::java_suspend_self() { 2359 int ret = 0; 2360 2361 // we are in the process of exiting so don't suspend 2362 if (is_exiting()) { 2363 clear_external_suspend(); 2364 return ret; 2365 } 2366 2367 assert(_anchor.walkable() || 2368 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2369 "must have walkable stack"); 2370 2371 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2372 2373 assert(!this->is_ext_suspended(), 2374 "a thread trying to self-suspend should not already be suspended"); 2375 2376 if (this->is_suspend_equivalent()) { 2377 // If we are self-suspending as a result of the lifting of a 2378 // suspend equivalent condition, then the suspend_equivalent 2379 // flag is not cleared until we set the ext_suspended flag so 2380 // that wait_for_ext_suspend_completion() returns consistent 2381 // results. 2382 this->clear_suspend_equivalent(); 2383 } 2384 2385 // A racing resume may have cancelled us before we grabbed SR_lock 2386 // above. Or another external suspend request could be waiting for us 2387 // by the time we return from SR_lock()->wait(). The thread 2388 // that requested the suspension may already be trying to walk our 2389 // stack and if we return now, we can change the stack out from under 2390 // it. This would be a "bad thing (TM)" and cause the stack walker 2391 // to crash. We stay self-suspended until there are no more pending 2392 // external suspend requests. 2393 while (is_external_suspend()) { 2394 ret++; 2395 this->set_ext_suspended(); 2396 2397 // _ext_suspended flag is cleared by java_resume() 2398 while (is_ext_suspended()) { 2399 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2400 } 2401 } 2402 2403 return ret; 2404 } 2405 2406 #ifdef ASSERT 2407 // Verify the JavaThread has not yet been published in the Threads::list, and 2408 // hence doesn't need protection from concurrent access at this stage. 2409 void JavaThread::verify_not_published() { 2410 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2411 // since an unpublished JavaThread doesn't participate in the 2412 // Thread-SMR protocol for keeping a ThreadsList alive. 2413 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2414 } 2415 #endif 2416 2417 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2418 // progress or when _suspend_flags is non-zero. 2419 // Current thread needs to self-suspend if there is a suspend request and/or 2420 // block if a safepoint is in progress. 2421 // Async exception ISN'T checked. 2422 // Note only the ThreadInVMfromNative transition can call this function 2423 // directly and when thread state is _thread_in_native_trans 2424 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2425 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2426 2427 JavaThread *curJT = JavaThread::current(); 2428 bool do_self_suspend = thread->is_external_suspend(); 2429 2430 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2431 2432 // If JNIEnv proxies are allowed, don't self-suspend if the target 2433 // thread is not the current thread. In older versions of jdbx, jdbx 2434 // threads could call into the VM with another thread's JNIEnv so we 2435 // can be here operating on behalf of a suspended thread (4432884). 2436 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2437 JavaThreadState state = thread->thread_state(); 2438 2439 // We mark this thread_blocked state as a suspend-equivalent so 2440 // that a caller to is_ext_suspend_completed() won't be confused. 2441 // The suspend-equivalent state is cleared by java_suspend_self(). 2442 thread->set_suspend_equivalent(); 2443 2444 // If the safepoint code sees the _thread_in_native_trans state, it will 2445 // wait until the thread changes to other thread state. There is no 2446 // guarantee on how soon we can obtain the SR_lock and complete the 2447 // self-suspend request. It would be a bad idea to let safepoint wait for 2448 // too long. Temporarily change the state to _thread_blocked to 2449 // let the VM thread know that this thread is ready for GC. The problem 2450 // of changing thread state is that safepoint could happen just after 2451 // java_suspend_self() returns after being resumed, and VM thread will 2452 // see the _thread_blocked state. We must check for safepoint 2453 // after restoring the state and make sure we won't leave while a safepoint 2454 // is in progress. 2455 thread->set_thread_state(_thread_blocked); 2456 thread->java_suspend_self(); 2457 thread->set_thread_state(state); 2458 2459 InterfaceSupport::serialize_thread_state_with_handler(thread); 2460 } 2461 2462 SafepointMechanism::block_if_requested(curJT); 2463 2464 if (thread->is_deopt_suspend()) { 2465 thread->clear_deopt_suspend(); 2466 RegisterMap map(thread, false); 2467 frame f = thread->last_frame(); 2468 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2469 f = f.sender(&map); 2470 } 2471 if (f.id() == thread->must_deopt_id()) { 2472 thread->clear_must_deopt_id(); 2473 f.deoptimize(thread); 2474 } else { 2475 fatal("missed deoptimization!"); 2476 } 2477 } 2478 2479 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2480 } 2481 2482 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2483 // progress or when _suspend_flags is non-zero. 2484 // Current thread needs to self-suspend if there is a suspend request and/or 2485 // block if a safepoint is in progress. 2486 // Also check for pending async exception (not including unsafe access error). 2487 // Note only the native==>VM/Java barriers can call this function and when 2488 // thread state is _thread_in_native_trans. 2489 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2490 check_safepoint_and_suspend_for_native_trans(thread); 2491 2492 if (thread->has_async_exception()) { 2493 // We are in _thread_in_native_trans state, don't handle unsafe 2494 // access error since that may block. 2495 thread->check_and_handle_async_exceptions(false); 2496 } 2497 } 2498 2499 // This is a variant of the normal 2500 // check_special_condition_for_native_trans with slightly different 2501 // semantics for use by critical native wrappers. It does all the 2502 // normal checks but also performs the transition back into 2503 // thread_in_Java state. This is required so that critical natives 2504 // can potentially block and perform a GC if they are the last thread 2505 // exiting the GCLocker. 2506 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2507 check_special_condition_for_native_trans(thread); 2508 2509 // Finish the transition 2510 thread->set_thread_state(_thread_in_Java); 2511 2512 if (thread->do_critical_native_unlock()) { 2513 ThreadInVMfromJavaNoAsyncException tiv(thread); 2514 GCLocker::unlock_critical(thread); 2515 thread->clear_critical_native_unlock(); 2516 } 2517 } 2518 2519 // We need to guarantee the Threads_lock here, since resumes are not 2520 // allowed during safepoint synchronization 2521 // Can only resume from an external suspension 2522 void JavaThread::java_resume() { 2523 assert_locked_or_safepoint(Threads_lock); 2524 2525 // Sanity check: thread is gone, has started exiting or the thread 2526 // was not externally suspended. 2527 ThreadsListHandle tlh; 2528 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2529 return; 2530 } 2531 2532 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2533 2534 clear_external_suspend(); 2535 2536 if (is_ext_suspended()) { 2537 clear_ext_suspended(); 2538 SR_lock()->notify_all(); 2539 } 2540 } 2541 2542 size_t JavaThread::_stack_red_zone_size = 0; 2543 size_t JavaThread::_stack_yellow_zone_size = 0; 2544 size_t JavaThread::_stack_reserved_zone_size = 0; 2545 size_t JavaThread::_stack_shadow_zone_size = 0; 2546 2547 void JavaThread::create_stack_guard_pages() { 2548 if (!os::uses_stack_guard_pages() || 2549 _stack_guard_state != stack_guard_unused || 2550 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2551 log_info(os, thread)("Stack guard page creation for thread " 2552 UINTX_FORMAT " disabled", os::current_thread_id()); 2553 return; 2554 } 2555 address low_addr = stack_end(); 2556 size_t len = stack_guard_zone_size(); 2557 2558 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2559 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2560 2561 int must_commit = os::must_commit_stack_guard_pages(); 2562 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2563 2564 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2565 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2566 return; 2567 } 2568 2569 if (os::guard_memory((char *) low_addr, len)) { 2570 _stack_guard_state = stack_guard_enabled; 2571 } else { 2572 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2573 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2574 if (os::uncommit_memory((char *) low_addr, len)) { 2575 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2576 } 2577 return; 2578 } 2579 2580 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2581 PTR_FORMAT "-" PTR_FORMAT ".", 2582 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2583 } 2584 2585 void JavaThread::remove_stack_guard_pages() { 2586 assert(Thread::current() == this, "from different thread"); 2587 if (_stack_guard_state == stack_guard_unused) return; 2588 address low_addr = stack_end(); 2589 size_t len = stack_guard_zone_size(); 2590 2591 if (os::must_commit_stack_guard_pages()) { 2592 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2593 _stack_guard_state = stack_guard_unused; 2594 } else { 2595 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2596 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2597 return; 2598 } 2599 } else { 2600 if (_stack_guard_state == stack_guard_unused) return; 2601 if (os::unguard_memory((char *) low_addr, len)) { 2602 _stack_guard_state = stack_guard_unused; 2603 } else { 2604 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2605 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2606 return; 2607 } 2608 } 2609 2610 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2611 PTR_FORMAT "-" PTR_FORMAT ".", 2612 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2613 } 2614 2615 void JavaThread::enable_stack_reserved_zone() { 2616 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2617 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2618 2619 // The base notation is from the stack's point of view, growing downward. 2620 // We need to adjust it to work correctly with guard_memory() 2621 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2622 2623 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2624 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2625 2626 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2627 _stack_guard_state = stack_guard_enabled; 2628 } else { 2629 warning("Attempt to guard stack reserved zone failed."); 2630 } 2631 enable_register_stack_guard(); 2632 } 2633 2634 void JavaThread::disable_stack_reserved_zone() { 2635 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2636 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2637 2638 // Simply return if called for a thread that does not use guard pages. 2639 if (_stack_guard_state == stack_guard_unused) return; 2640 2641 // The base notation is from the stack's point of view, growing downward. 2642 // We need to adjust it to work correctly with guard_memory() 2643 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2644 2645 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2646 _stack_guard_state = stack_guard_reserved_disabled; 2647 } else { 2648 warning("Attempt to unguard stack reserved zone failed."); 2649 } 2650 disable_register_stack_guard(); 2651 } 2652 2653 void JavaThread::enable_stack_yellow_reserved_zone() { 2654 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2655 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2656 2657 // The base notation is from the stacks point of view, growing downward. 2658 // We need to adjust it to work correctly with guard_memory() 2659 address base = stack_red_zone_base(); 2660 2661 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2662 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2663 2664 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2665 _stack_guard_state = stack_guard_enabled; 2666 } else { 2667 warning("Attempt to guard stack yellow zone failed."); 2668 } 2669 enable_register_stack_guard(); 2670 } 2671 2672 void JavaThread::disable_stack_yellow_reserved_zone() { 2673 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2674 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2675 2676 // Simply return if called for a thread that does not use guard pages. 2677 if (_stack_guard_state == stack_guard_unused) return; 2678 2679 // The base notation is from the stacks point of view, growing downward. 2680 // We need to adjust it to work correctly with guard_memory() 2681 address base = stack_red_zone_base(); 2682 2683 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2684 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2685 } else { 2686 warning("Attempt to unguard stack yellow zone failed."); 2687 } 2688 disable_register_stack_guard(); 2689 } 2690 2691 void JavaThread::enable_stack_red_zone() { 2692 // The base notation is from the stacks point of view, growing downward. 2693 // We need to adjust it to work correctly with guard_memory() 2694 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2695 address base = stack_red_zone_base() - stack_red_zone_size(); 2696 2697 guarantee(base < stack_base(), "Error calculating stack red zone"); 2698 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2699 2700 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2701 warning("Attempt to guard stack red zone failed."); 2702 } 2703 } 2704 2705 void JavaThread::disable_stack_red_zone() { 2706 // The base notation is from the stacks point of view, growing downward. 2707 // We need to adjust it to work correctly with guard_memory() 2708 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2709 address base = stack_red_zone_base() - stack_red_zone_size(); 2710 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2711 warning("Attempt to unguard stack red zone failed."); 2712 } 2713 } 2714 2715 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2716 // ignore is there is no stack 2717 if (!has_last_Java_frame()) return; 2718 // traverse the stack frames. Starts from top frame. 2719 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2720 frame* fr = fst.current(); 2721 f(fr, fst.register_map()); 2722 } 2723 } 2724 2725 2726 #ifndef PRODUCT 2727 // Deoptimization 2728 // Function for testing deoptimization 2729 void JavaThread::deoptimize() { 2730 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2731 StackFrameStream fst(this, UseBiasedLocking); 2732 bool deopt = false; // Dump stack only if a deopt actually happens. 2733 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2734 // Iterate over all frames in the thread and deoptimize 2735 for (; !fst.is_done(); fst.next()) { 2736 if (fst.current()->can_be_deoptimized()) { 2737 2738 if (only_at) { 2739 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2740 // consists of comma or carriage return separated numbers so 2741 // search for the current bci in that string. 2742 address pc = fst.current()->pc(); 2743 nmethod* nm = (nmethod*) fst.current()->cb(); 2744 ScopeDesc* sd = nm->scope_desc_at(pc); 2745 char buffer[8]; 2746 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2747 size_t len = strlen(buffer); 2748 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2749 while (found != NULL) { 2750 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2751 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2752 // Check that the bci found is bracketed by terminators. 2753 break; 2754 } 2755 found = strstr(found + 1, buffer); 2756 } 2757 if (!found) { 2758 continue; 2759 } 2760 } 2761 2762 if (DebugDeoptimization && !deopt) { 2763 deopt = true; // One-time only print before deopt 2764 tty->print_cr("[BEFORE Deoptimization]"); 2765 trace_frames(); 2766 trace_stack(); 2767 } 2768 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2769 } 2770 } 2771 2772 if (DebugDeoptimization && deopt) { 2773 tty->print_cr("[AFTER Deoptimization]"); 2774 trace_frames(); 2775 } 2776 } 2777 2778 2779 // Make zombies 2780 void JavaThread::make_zombies() { 2781 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2782 if (fst.current()->can_be_deoptimized()) { 2783 // it is a Java nmethod 2784 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2785 nm->make_not_entrant(); 2786 } 2787 } 2788 } 2789 #endif // PRODUCT 2790 2791 2792 void JavaThread::deoptimized_wrt_marked_nmethods() { 2793 if (!has_last_Java_frame()) return; 2794 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2795 StackFrameStream fst(this, UseBiasedLocking); 2796 for (; !fst.is_done(); fst.next()) { 2797 if (fst.current()->should_be_deoptimized()) { 2798 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2799 } 2800 } 2801 } 2802 2803 2804 // If the caller is a NamedThread, then remember, in the current scope, 2805 // the given JavaThread in its _processed_thread field. 2806 class RememberProcessedThread: public StackObj { 2807 NamedThread* _cur_thr; 2808 public: 2809 RememberProcessedThread(JavaThread* jthr) { 2810 Thread* thread = Thread::current(); 2811 if (thread->is_Named_thread()) { 2812 _cur_thr = (NamedThread *)thread; 2813 _cur_thr->set_processed_thread(jthr); 2814 } else { 2815 _cur_thr = NULL; 2816 } 2817 } 2818 2819 ~RememberProcessedThread() { 2820 if (_cur_thr) { 2821 _cur_thr->set_processed_thread(NULL); 2822 } 2823 } 2824 }; 2825 2826 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2827 // Verify that the deferred card marks have been flushed. 2828 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2829 2830 // Traverse the GCHandles 2831 Thread::oops_do(f, cf); 2832 2833 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2834 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2835 2836 if (has_last_Java_frame()) { 2837 // Record JavaThread to GC thread 2838 RememberProcessedThread rpt(this); 2839 2840 // traverse the registered growable array 2841 if (_array_for_gc != NULL) { 2842 for (int index = 0; index < _array_for_gc->length(); index++) { 2843 f->do_oop(_array_for_gc->adr_at(index)); 2844 } 2845 } 2846 2847 // Traverse the monitor chunks 2848 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2849 chunk->oops_do(f); 2850 } 2851 2852 // Traverse the execution stack 2853 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2854 fst.current()->oops_do(f, cf, fst.register_map()); 2855 } 2856 } 2857 2858 // callee_target is never live across a gc point so NULL it here should 2859 // it still contain a methdOop. 2860 2861 set_callee_target(NULL); 2862 2863 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2864 // If we have deferred set_locals there might be oops waiting to be 2865 // written 2866 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2867 if (list != NULL) { 2868 for (int i = 0; i < list->length(); i++) { 2869 list->at(i)->oops_do(f); 2870 } 2871 } 2872 2873 // Traverse instance variables at the end since the GC may be moving things 2874 // around using this function 2875 f->do_oop((oop*) &_threadObj); 2876 f->do_oop((oop*) &_vm_result); 2877 f->do_oop((oop*) &_exception_oop); 2878 f->do_oop((oop*) &_pending_async_exception); 2879 2880 if (jvmti_thread_state() != NULL) { 2881 jvmti_thread_state()->oops_do(f); 2882 } 2883 } 2884 2885 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2886 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2887 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2888 2889 if (has_last_Java_frame()) { 2890 // Traverse the execution stack 2891 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2892 fst.current()->nmethods_do(cf); 2893 } 2894 } 2895 } 2896 2897 void JavaThread::metadata_do(void f(Metadata*)) { 2898 if (has_last_Java_frame()) { 2899 // Traverse the execution stack to call f() on the methods in the stack 2900 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2901 fst.current()->metadata_do(f); 2902 } 2903 } else if (is_Compiler_thread()) { 2904 // need to walk ciMetadata in current compile tasks to keep alive. 2905 CompilerThread* ct = (CompilerThread*)this; 2906 if (ct->env() != NULL) { 2907 ct->env()->metadata_do(f); 2908 } 2909 CompileTask* task = ct->task(); 2910 if (task != NULL) { 2911 task->metadata_do(f); 2912 } 2913 } 2914 } 2915 2916 // Printing 2917 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2918 switch (_thread_state) { 2919 case _thread_uninitialized: return "_thread_uninitialized"; 2920 case _thread_new: return "_thread_new"; 2921 case _thread_new_trans: return "_thread_new_trans"; 2922 case _thread_in_native: return "_thread_in_native"; 2923 case _thread_in_native_trans: return "_thread_in_native_trans"; 2924 case _thread_in_vm: return "_thread_in_vm"; 2925 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2926 case _thread_in_Java: return "_thread_in_Java"; 2927 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2928 case _thread_blocked: return "_thread_blocked"; 2929 case _thread_blocked_trans: return "_thread_blocked_trans"; 2930 default: return "unknown thread state"; 2931 } 2932 } 2933 2934 #ifndef PRODUCT 2935 void JavaThread::print_thread_state_on(outputStream *st) const { 2936 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2937 }; 2938 void JavaThread::print_thread_state() const { 2939 print_thread_state_on(tty); 2940 } 2941 #endif // PRODUCT 2942 2943 // Called by Threads::print() for VM_PrintThreads operation 2944 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2945 st->print_raw("\""); 2946 st->print_raw(get_thread_name()); 2947 st->print_raw("\" "); 2948 oop thread_oop = threadObj(); 2949 if (thread_oop != NULL) { 2950 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2951 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2952 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2953 } 2954 Thread::print_on(st, print_extended_info); 2955 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2956 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2957 if (thread_oop != NULL) { 2958 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2959 } 2960 #ifndef PRODUCT 2961 print_thread_state_on(st); 2962 _safepoint_state->print_on(st); 2963 #endif // PRODUCT 2964 if (is_Compiler_thread()) { 2965 CompileTask *task = ((CompilerThread*)this)->task(); 2966 if (task != NULL) { 2967 st->print(" Compiling: "); 2968 task->print(st, NULL, true, false); 2969 } else { 2970 st->print(" No compile task"); 2971 } 2972 st->cr(); 2973 } 2974 } 2975 2976 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2977 st->print("%s", get_thread_name_string(buf, buflen)); 2978 } 2979 2980 // Called by fatal error handler. The difference between this and 2981 // JavaThread::print() is that we can't grab lock or allocate memory. 2982 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2983 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2984 oop thread_obj = threadObj(); 2985 if (thread_obj != NULL) { 2986 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2987 } 2988 st->print(" ["); 2989 st->print("%s", _get_thread_state_name(_thread_state)); 2990 if (osthread()) { 2991 st->print(", id=%d", osthread()->thread_id()); 2992 } 2993 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2994 p2i(stack_end()), p2i(stack_base())); 2995 st->print("]"); 2996 2997 ThreadsSMRSupport::print_info_on(this, st); 2998 return; 2999 } 3000 3001 // Verification 3002 3003 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3004 3005 void JavaThread::verify() { 3006 // Verify oops in the thread. 3007 oops_do(&VerifyOopClosure::verify_oop, NULL); 3008 3009 // Verify the stack frames. 3010 frames_do(frame_verify); 3011 } 3012 3013 // CR 6300358 (sub-CR 2137150) 3014 // Most callers of this method assume that it can't return NULL but a 3015 // thread may not have a name whilst it is in the process of attaching to 3016 // the VM - see CR 6412693, and there are places where a JavaThread can be 3017 // seen prior to having it's threadObj set (eg JNI attaching threads and 3018 // if vm exit occurs during initialization). These cases can all be accounted 3019 // for such that this method never returns NULL. 3020 const char* JavaThread::get_thread_name() const { 3021 #ifdef ASSERT 3022 // early safepoints can hit while current thread does not yet have TLS 3023 if (!SafepointSynchronize::is_at_safepoint()) { 3024 Thread *cur = Thread::current(); 3025 if (!(cur->is_Java_thread() && cur == this)) { 3026 // Current JavaThreads are allowed to get their own name without 3027 // the Threads_lock. 3028 assert_locked_or_safepoint(Threads_lock); 3029 } 3030 } 3031 #endif // ASSERT 3032 return get_thread_name_string(); 3033 } 3034 3035 // Returns a non-NULL representation of this thread's name, or a suitable 3036 // descriptive string if there is no set name 3037 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3038 const char* name_str; 3039 oop thread_obj = threadObj(); 3040 if (thread_obj != NULL) { 3041 oop name = java_lang_Thread::name(thread_obj); 3042 if (name != NULL) { 3043 if (buf == NULL) { 3044 name_str = java_lang_String::as_utf8_string(name); 3045 } else { 3046 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3047 } 3048 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3049 name_str = "<no-name - thread is attaching>"; 3050 } else { 3051 name_str = Thread::name(); 3052 } 3053 } else { 3054 name_str = Thread::name(); 3055 } 3056 assert(name_str != NULL, "unexpected NULL thread name"); 3057 return name_str; 3058 } 3059 3060 3061 const char* JavaThread::get_threadgroup_name() const { 3062 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3063 oop thread_obj = threadObj(); 3064 if (thread_obj != NULL) { 3065 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3066 if (thread_group != NULL) { 3067 // ThreadGroup.name can be null 3068 return java_lang_ThreadGroup::name(thread_group); 3069 } 3070 } 3071 return NULL; 3072 } 3073 3074 const char* JavaThread::get_parent_name() const { 3075 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3076 oop thread_obj = threadObj(); 3077 if (thread_obj != NULL) { 3078 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3079 if (thread_group != NULL) { 3080 oop parent = java_lang_ThreadGroup::parent(thread_group); 3081 if (parent != NULL) { 3082 // ThreadGroup.name can be null 3083 return java_lang_ThreadGroup::name(parent); 3084 } 3085 } 3086 } 3087 return NULL; 3088 } 3089 3090 ThreadPriority JavaThread::java_priority() const { 3091 oop thr_oop = threadObj(); 3092 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3093 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3094 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3095 return priority; 3096 } 3097 3098 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3099 3100 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3101 // Link Java Thread object <-> C++ Thread 3102 3103 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3104 // and put it into a new Handle. The Handle "thread_oop" can then 3105 // be used to pass the C++ thread object to other methods. 3106 3107 // Set the Java level thread object (jthread) field of the 3108 // new thread (a JavaThread *) to C++ thread object using the 3109 // "thread_oop" handle. 3110 3111 // Set the thread field (a JavaThread *) of the 3112 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3113 3114 Handle thread_oop(Thread::current(), 3115 JNIHandles::resolve_non_null(jni_thread)); 3116 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3117 "must be initialized"); 3118 set_threadObj(thread_oop()); 3119 java_lang_Thread::set_thread(thread_oop(), this); 3120 3121 if (prio == NoPriority) { 3122 prio = java_lang_Thread::priority(thread_oop()); 3123 assert(prio != NoPriority, "A valid priority should be present"); 3124 } 3125 3126 // Push the Java priority down to the native thread; needs Threads_lock 3127 Thread::set_priority(this, prio); 3128 3129 // Add the new thread to the Threads list and set it in motion. 3130 // We must have threads lock in order to call Threads::add. 3131 // It is crucial that we do not block before the thread is 3132 // added to the Threads list for if a GC happens, then the java_thread oop 3133 // will not be visited by GC. 3134 Threads::add(this); 3135 } 3136 3137 oop JavaThread::current_park_blocker() { 3138 // Support for JSR-166 locks 3139 oop thread_oop = threadObj(); 3140 if (thread_oop != NULL && 3141 JDK_Version::current().supports_thread_park_blocker()) { 3142 return java_lang_Thread::park_blocker(thread_oop); 3143 } 3144 return NULL; 3145 } 3146 3147 3148 void JavaThread::print_stack_on(outputStream* st) { 3149 if (!has_last_Java_frame()) return; 3150 ResourceMark rm; 3151 HandleMark hm; 3152 3153 RegisterMap reg_map(this); 3154 vframe* start_vf = last_java_vframe(®_map); 3155 int count = 0; 3156 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3157 if (f->is_java_frame()) { 3158 javaVFrame* jvf = javaVFrame::cast(f); 3159 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3160 3161 // Print out lock information 3162 if (JavaMonitorsInStackTrace) { 3163 jvf->print_lock_info_on(st, count); 3164 } 3165 } else { 3166 // Ignore non-Java frames 3167 } 3168 3169 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3170 count++; 3171 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3172 } 3173 } 3174 3175 3176 // JVMTI PopFrame support 3177 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3178 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3179 if (in_bytes(size_in_bytes) != 0) { 3180 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3181 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3182 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3183 } 3184 } 3185 3186 void* JavaThread::popframe_preserved_args() { 3187 return _popframe_preserved_args; 3188 } 3189 3190 ByteSize JavaThread::popframe_preserved_args_size() { 3191 return in_ByteSize(_popframe_preserved_args_size); 3192 } 3193 3194 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3195 int sz = in_bytes(popframe_preserved_args_size()); 3196 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3197 return in_WordSize(sz / wordSize); 3198 } 3199 3200 void JavaThread::popframe_free_preserved_args() { 3201 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3202 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3203 _popframe_preserved_args = NULL; 3204 _popframe_preserved_args_size = 0; 3205 } 3206 3207 #ifndef PRODUCT 3208 3209 void JavaThread::trace_frames() { 3210 tty->print_cr("[Describe stack]"); 3211 int frame_no = 1; 3212 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3213 tty->print(" %d. ", frame_no++); 3214 fst.current()->print_value_on(tty, this); 3215 tty->cr(); 3216 } 3217 } 3218 3219 class PrintAndVerifyOopClosure: public OopClosure { 3220 protected: 3221 template <class T> inline void do_oop_work(T* p) { 3222 oop obj = RawAccess<>::oop_load(p); 3223 if (obj == NULL) return; 3224 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3225 if (oopDesc::is_oop_or_null(obj)) { 3226 if (obj->is_objArray()) { 3227 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3228 } else { 3229 obj->print(); 3230 } 3231 } else { 3232 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3233 } 3234 tty->cr(); 3235 } 3236 public: 3237 virtual void do_oop(oop* p) { do_oop_work(p); } 3238 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3239 }; 3240 3241 3242 static void oops_print(frame* f, const RegisterMap *map) { 3243 PrintAndVerifyOopClosure print; 3244 f->print_value(); 3245 f->oops_do(&print, NULL, (RegisterMap*)map); 3246 } 3247 3248 // Print our all the locations that contain oops and whether they are 3249 // valid or not. This useful when trying to find the oldest frame 3250 // where an oop has gone bad since the frame walk is from youngest to 3251 // oldest. 3252 void JavaThread::trace_oops() { 3253 tty->print_cr("[Trace oops]"); 3254 frames_do(oops_print); 3255 } 3256 3257 3258 #ifdef ASSERT 3259 // Print or validate the layout of stack frames 3260 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3261 ResourceMark rm; 3262 PRESERVE_EXCEPTION_MARK; 3263 FrameValues values; 3264 int frame_no = 0; 3265 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3266 fst.current()->describe(values, ++frame_no); 3267 if (depth == frame_no) break; 3268 } 3269 if (validate_only) { 3270 values.validate(); 3271 } else { 3272 tty->print_cr("[Describe stack layout]"); 3273 values.print(this); 3274 } 3275 } 3276 #endif 3277 3278 void JavaThread::trace_stack_from(vframe* start_vf) { 3279 ResourceMark rm; 3280 int vframe_no = 1; 3281 for (vframe* f = start_vf; f; f = f->sender()) { 3282 if (f->is_java_frame()) { 3283 javaVFrame::cast(f)->print_activation(vframe_no++); 3284 } else { 3285 f->print(); 3286 } 3287 if (vframe_no > StackPrintLimit) { 3288 tty->print_cr("...<more frames>..."); 3289 return; 3290 } 3291 } 3292 } 3293 3294 3295 void JavaThread::trace_stack() { 3296 if (!has_last_Java_frame()) return; 3297 ResourceMark rm; 3298 HandleMark hm; 3299 RegisterMap reg_map(this); 3300 trace_stack_from(last_java_vframe(®_map)); 3301 } 3302 3303 3304 #endif // PRODUCT 3305 3306 3307 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3308 assert(reg_map != NULL, "a map must be given"); 3309 frame f = last_frame(); 3310 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3311 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3312 } 3313 return NULL; 3314 } 3315 3316 3317 Klass* JavaThread::security_get_caller_class(int depth) { 3318 vframeStream vfst(this); 3319 vfst.security_get_caller_frame(depth); 3320 if (!vfst.at_end()) { 3321 return vfst.method()->method_holder(); 3322 } 3323 return NULL; 3324 } 3325 3326 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3327 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3328 CompileBroker::compiler_thread_loop(); 3329 } 3330 3331 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3332 NMethodSweeper::sweeper_loop(); 3333 } 3334 3335 // Create a CompilerThread 3336 CompilerThread::CompilerThread(CompileQueue* queue, 3337 CompilerCounters* counters) 3338 : JavaThread(&compiler_thread_entry) { 3339 _env = NULL; 3340 _log = NULL; 3341 _task = NULL; 3342 _queue = queue; 3343 _counters = counters; 3344 _buffer_blob = NULL; 3345 _compiler = NULL; 3346 3347 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3348 resource_area()->bias_to(mtCompiler); 3349 3350 #ifndef PRODUCT 3351 _ideal_graph_printer = NULL; 3352 #endif 3353 } 3354 3355 CompilerThread::~CompilerThread() { 3356 // Delete objects which were allocated on heap. 3357 delete _counters; 3358 } 3359 3360 bool CompilerThread::can_call_java() const { 3361 return _compiler != NULL && _compiler->is_jvmci(); 3362 } 3363 3364 // Create sweeper thread 3365 CodeCacheSweeperThread::CodeCacheSweeperThread() 3366 : JavaThread(&sweeper_thread_entry) { 3367 _scanned_compiled_method = NULL; 3368 } 3369 3370 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3371 JavaThread::oops_do(f, cf); 3372 if (_scanned_compiled_method != NULL && cf != NULL) { 3373 // Safepoints can occur when the sweeper is scanning an nmethod so 3374 // process it here to make sure it isn't unloaded in the middle of 3375 // a scan. 3376 cf->do_code_blob(_scanned_compiled_method); 3377 } 3378 } 3379 3380 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3381 JavaThread::nmethods_do(cf); 3382 if (_scanned_compiled_method != NULL && cf != NULL) { 3383 // Safepoints can occur when the sweeper is scanning an nmethod so 3384 // process it here to make sure it isn't unloaded in the middle of 3385 // a scan. 3386 cf->do_code_blob(_scanned_compiled_method); 3387 } 3388 } 3389 3390 3391 // ======= Threads ======== 3392 3393 // The Threads class links together all active threads, and provides 3394 // operations over all threads. It is protected by the Threads_lock, 3395 // which is also used in other global contexts like safepointing. 3396 // ThreadsListHandles are used to safely perform operations on one 3397 // or more threads without the risk of the thread exiting during the 3398 // operation. 3399 // 3400 // Note: The Threads_lock is currently more widely used than we 3401 // would like. We are actively migrating Threads_lock uses to other 3402 // mechanisms in order to reduce Threads_lock contention. 3403 3404 JavaThread* Threads::_thread_list = NULL; 3405 int Threads::_number_of_threads = 0; 3406 int Threads::_number_of_non_daemon_threads = 0; 3407 int Threads::_return_code = 0; 3408 int Threads::_thread_claim_parity = 0; 3409 size_t JavaThread::_stack_size_at_create = 0; 3410 3411 #ifdef ASSERT 3412 bool Threads::_vm_complete = false; 3413 size_t Threads::_threads_before_barrier_set = 0; 3414 #endif 3415 3416 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3417 Prefetch::read((void*)addr, prefetch_interval); 3418 return *addr; 3419 } 3420 3421 // Possibly the ugliest for loop the world has seen. C++ does not allow 3422 // multiple types in the declaration section of the for loop. In this case 3423 // we are only dealing with pointers and hence can cast them. It looks ugly 3424 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3425 #define DO_JAVA_THREADS(LIST, X) \ 3426 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3427 *MACRO_list = (JavaThread*)(LIST), \ 3428 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3429 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3430 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3431 MACRO_current_p != MACRO_end; \ 3432 MACRO_current_p++, \ 3433 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3434 3435 // All JavaThreads 3436 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3437 3438 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3439 void Threads::non_java_threads_do(ThreadClosure* tc) { 3440 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3441 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3442 tc->do_thread(njti.current()); 3443 } 3444 } 3445 3446 // All JavaThreads 3447 void Threads::java_threads_do(ThreadClosure* tc) { 3448 assert_locked_or_safepoint(Threads_lock); 3449 // ALL_JAVA_THREADS iterates through all JavaThreads. 3450 ALL_JAVA_THREADS(p) { 3451 tc->do_thread(p); 3452 } 3453 } 3454 3455 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3456 assert_locked_or_safepoint(Threads_lock); 3457 java_threads_do(tc); 3458 tc->do_thread(VMThread::vm_thread()); 3459 } 3460 3461 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3462 void Threads::threads_do(ThreadClosure* tc) { 3463 assert_locked_or_safepoint(Threads_lock); 3464 java_threads_do(tc); 3465 non_java_threads_do(tc); 3466 } 3467 3468 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3469 int cp = Threads::thread_claim_parity(); 3470 ALL_JAVA_THREADS(p) { 3471 if (p->claim_oops_do(is_par, cp)) { 3472 tc->do_thread(p); 3473 } 3474 } 3475 VMThread* vmt = VMThread::vm_thread(); 3476 if (vmt->claim_oops_do(is_par, cp)) { 3477 tc->do_thread(vmt); 3478 } 3479 } 3480 3481 // The system initialization in the library has three phases. 3482 // 3483 // Phase 1: java.lang.System class initialization 3484 // java.lang.System is a primordial class loaded and initialized 3485 // by the VM early during startup. java.lang.System.<clinit> 3486 // only does registerNatives and keeps the rest of the class 3487 // initialization work later until thread initialization completes. 3488 // 3489 // System.initPhase1 initializes the system properties, the static 3490 // fields in, out, and err. Set up java signal handlers, OS-specific 3491 // system settings, and thread group of the main thread. 3492 static void call_initPhase1(TRAPS) { 3493 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3494 JavaValue result(T_VOID); 3495 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3496 vmSymbols::void_method_signature(), CHECK); 3497 } 3498 3499 // Phase 2. Module system initialization 3500 // This will initialize the module system. Only java.base classes 3501 // can be loaded until phase 2 completes. 3502 // 3503 // Call System.initPhase2 after the compiler initialization and jsr292 3504 // classes get initialized because module initialization runs a lot of java 3505 // code, that for performance reasons, should be compiled. Also, this will 3506 // enable the startup code to use lambda and other language features in this 3507 // phase and onward. 3508 // 3509 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3510 static void call_initPhase2(TRAPS) { 3511 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3512 3513 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3514 3515 JavaValue result(T_INT); 3516 JavaCallArguments args; 3517 args.push_int(DisplayVMOutputToStderr); 3518 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3519 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3520 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3521 if (result.get_jint() != JNI_OK) { 3522 vm_exit_during_initialization(); // no message or exception 3523 } 3524 3525 universe_post_module_init(); 3526 } 3527 3528 // Phase 3. final setup - set security manager, system class loader and TCCL 3529 // 3530 // This will instantiate and set the security manager, set the system class 3531 // loader as well as the thread context class loader. The security manager 3532 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3533 // other modules or the application's classpath. 3534 static void call_initPhase3(TRAPS) { 3535 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3536 JavaValue result(T_VOID); 3537 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3538 vmSymbols::void_method_signature(), CHECK); 3539 } 3540 3541 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3542 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3543 3544 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3545 create_vm_init_libraries(); 3546 } 3547 3548 initialize_class(vmSymbols::java_lang_String(), CHECK); 3549 3550 // Inject CompactStrings value after the static initializers for String ran. 3551 java_lang_String::set_compact_strings(CompactStrings); 3552 3553 // Initialize java_lang.System (needed before creating the thread) 3554 initialize_class(vmSymbols::java_lang_System(), CHECK); 3555 // The VM creates & returns objects of this class. Make sure it's initialized. 3556 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3557 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3558 Handle thread_group = create_initial_thread_group(CHECK); 3559 Universe::set_main_thread_group(thread_group()); 3560 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3561 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3562 main_thread->set_threadObj(thread_object); 3563 // Set thread status to running since main thread has 3564 // been started and running. 3565 java_lang_Thread::set_thread_status(thread_object, 3566 java_lang_Thread::RUNNABLE); 3567 3568 // The VM creates objects of this class. 3569 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3570 3571 // The VM preresolves methods to these classes. Make sure that they get initialized 3572 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3573 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3574 3575 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3576 call_initPhase1(CHECK); 3577 3578 // get the Java runtime name after java.lang.System is initialized 3579 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3580 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3581 3582 // an instance of OutOfMemory exception has been allocated earlier 3583 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3584 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3585 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3586 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3587 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3588 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3589 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3590 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3591 } 3592 3593 void Threads::initialize_jsr292_core_classes(TRAPS) { 3594 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3595 3596 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3597 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3598 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3599 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3600 } 3601 3602 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3603 extern void JDK_Version_init(); 3604 3605 // Preinitialize version info. 3606 VM_Version::early_initialize(); 3607 3608 // Check version 3609 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3610 3611 // Initialize library-based TLS 3612 ThreadLocalStorage::init(); 3613 3614 // Initialize the output stream module 3615 ostream_init(); 3616 3617 // Process java launcher properties. 3618 Arguments::process_sun_java_launcher_properties(args); 3619 3620 // Initialize the os module 3621 os::init(); 3622 3623 // Record VM creation timing statistics 3624 TraceVmCreationTime create_vm_timer; 3625 create_vm_timer.start(); 3626 3627 // Initialize system properties. 3628 Arguments::init_system_properties(); 3629 3630 // So that JDK version can be used as a discriminator when parsing arguments 3631 JDK_Version_init(); 3632 3633 // Update/Initialize System properties after JDK version number is known 3634 Arguments::init_version_specific_system_properties(); 3635 3636 // Make sure to initialize log configuration *before* parsing arguments 3637 LogConfiguration::initialize(create_vm_timer.begin_time()); 3638 3639 // Parse arguments 3640 // Note: this internally calls os::init_container_support() 3641 jint parse_result = Arguments::parse(args); 3642 if (parse_result != JNI_OK) return parse_result; 3643 3644 os::init_before_ergo(); 3645 3646 jint ergo_result = Arguments::apply_ergo(); 3647 if (ergo_result != JNI_OK) return ergo_result; 3648 3649 // Final check of all ranges after ergonomics which may change values. 3650 if (!JVMFlagRangeList::check_ranges()) { 3651 return JNI_EINVAL; 3652 } 3653 3654 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3655 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3656 if (!constraint_result) { 3657 return JNI_EINVAL; 3658 } 3659 3660 JVMFlagWriteableList::mark_startup(); 3661 3662 if (PauseAtStartup) { 3663 os::pause(); 3664 } 3665 3666 HOTSPOT_VM_INIT_BEGIN(); 3667 3668 // Timing (must come after argument parsing) 3669 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3670 3671 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3672 // Initialize assert poison page mechanism. 3673 if (ShowRegistersOnAssert) { 3674 initialize_assert_poison(); 3675 } 3676 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3677 3678 // Initialize the os module after parsing the args 3679 jint os_init_2_result = os::init_2(); 3680 if (os_init_2_result != JNI_OK) return os_init_2_result; 3681 3682 SafepointMechanism::initialize(); 3683 3684 jint adjust_after_os_result = Arguments::adjust_after_os(); 3685 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3686 3687 // Initialize output stream logging 3688 ostream_init_log(); 3689 3690 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3691 // Must be before create_vm_init_agents() 3692 if (Arguments::init_libraries_at_startup()) { 3693 convert_vm_init_libraries_to_agents(); 3694 } 3695 3696 // Launch -agentlib/-agentpath and converted -Xrun agents 3697 if (Arguments::init_agents_at_startup()) { 3698 create_vm_init_agents(); 3699 } 3700 3701 // Initialize Threads state 3702 _thread_list = NULL; 3703 _number_of_threads = 0; 3704 _number_of_non_daemon_threads = 0; 3705 3706 // Initialize global data structures and create system classes in heap 3707 vm_init_globals(); 3708 3709 #if INCLUDE_JVMCI 3710 if (JVMCICounterSize > 0) { 3711 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3712 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3713 } else { 3714 JavaThread::_jvmci_old_thread_counters = NULL; 3715 } 3716 #endif // INCLUDE_JVMCI 3717 3718 // Attach the main thread to this os thread 3719 JavaThread* main_thread = new JavaThread(); 3720 main_thread->set_thread_state(_thread_in_vm); 3721 main_thread->initialize_thread_current(); 3722 // must do this before set_active_handles 3723 main_thread->record_stack_base_and_size(); 3724 main_thread->register_thread_stack_with_NMT(); 3725 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3726 3727 if (!main_thread->set_as_starting_thread()) { 3728 vm_shutdown_during_initialization( 3729 "Failed necessary internal allocation. Out of swap space"); 3730 main_thread->smr_delete(); 3731 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3732 return JNI_ENOMEM; 3733 } 3734 3735 // Enable guard page *after* os::create_main_thread(), otherwise it would 3736 // crash Linux VM, see notes in os_linux.cpp. 3737 main_thread->create_stack_guard_pages(); 3738 3739 // Initialize Java-Level synchronization subsystem 3740 ObjectMonitor::Initialize(); 3741 3742 // Initialize global modules 3743 jint status = init_globals(); 3744 if (status != JNI_OK) { 3745 main_thread->smr_delete(); 3746 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3747 return status; 3748 } 3749 3750 JFR_ONLY(Jfr::on_vm_init();) 3751 3752 // Should be done after the heap is fully created 3753 main_thread->cache_global_variables(); 3754 3755 HandleMark hm; 3756 3757 { MutexLocker mu(Threads_lock); 3758 Threads::add(main_thread); 3759 } 3760 3761 // Any JVMTI raw monitors entered in onload will transition into 3762 // real raw monitor. VM is setup enough here for raw monitor enter. 3763 JvmtiExport::transition_pending_onload_raw_monitors(); 3764 3765 // Create the VMThread 3766 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3767 3768 VMThread::create(); 3769 Thread* vmthread = VMThread::vm_thread(); 3770 3771 if (!os::create_thread(vmthread, os::vm_thread)) { 3772 vm_exit_during_initialization("Cannot create VM thread. " 3773 "Out of system resources."); 3774 } 3775 3776 // Wait for the VM thread to become ready, and VMThread::run to initialize 3777 // Monitors can have spurious returns, must always check another state flag 3778 { 3779 MutexLocker ml(Notify_lock); 3780 os::start_thread(vmthread); 3781 while (vmthread->active_handles() == NULL) { 3782 Notify_lock->wait(); 3783 } 3784 } 3785 } 3786 3787 assert(Universe::is_fully_initialized(), "not initialized"); 3788 if (VerifyDuringStartup) { 3789 // Make sure we're starting with a clean slate. 3790 VM_Verify verify_op; 3791 VMThread::execute(&verify_op); 3792 } 3793 3794 // We need this to update the java.vm.info property in case any flags used 3795 // to initially define it have been changed. This is needed for both CDS and 3796 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3797 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3798 // This update must happen before we initialize the java classes, but 3799 // after any initialization logic that might modify the flags. 3800 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3801 3802 Thread* THREAD = Thread::current(); 3803 3804 // Always call even when there are not JVMTI environments yet, since environments 3805 // may be attached late and JVMTI must track phases of VM execution 3806 JvmtiExport::enter_early_start_phase(); 3807 3808 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3809 JvmtiExport::post_early_vm_start(); 3810 3811 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3812 3813 quicken_jni_functions(); 3814 3815 // No more stub generation allowed after that point. 3816 StubCodeDesc::freeze(); 3817 3818 // Set flag that basic initialization has completed. Used by exceptions and various 3819 // debug stuff, that does not work until all basic classes have been initialized. 3820 set_init_completed(); 3821 3822 LogConfiguration::post_initialize(); 3823 Metaspace::post_initialize(); 3824 3825 HOTSPOT_VM_INIT_END(); 3826 3827 // record VM initialization completion time 3828 #if INCLUDE_MANAGEMENT 3829 Management::record_vm_init_completed(); 3830 #endif // INCLUDE_MANAGEMENT 3831 3832 // Signal Dispatcher needs to be started before VMInit event is posted 3833 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3834 3835 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3836 if (!DisableAttachMechanism) { 3837 AttachListener::vm_start(); 3838 if (StartAttachListener || AttachListener::init_at_startup()) { 3839 AttachListener::init(); 3840 } 3841 } 3842 3843 // Launch -Xrun agents 3844 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3845 // back-end can launch with -Xdebug -Xrunjdwp. 3846 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3847 create_vm_init_libraries(); 3848 } 3849 3850 if (CleanChunkPoolAsync) { 3851 Chunk::start_chunk_pool_cleaner_task(); 3852 } 3853 3854 // initialize compiler(s) 3855 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3856 #if INCLUDE_JVMCI 3857 bool force_JVMCI_intialization = false; 3858 if (EnableJVMCI) { 3859 // Initialize JVMCI eagerly when it is explicitly requested. 3860 // Or when JVMCIPrintProperties is enabled. 3861 // The JVMCI Java initialization code will read this flag and 3862 // do the printing if it's set. 3863 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3864 3865 if (!force_JVMCI_intialization) { 3866 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3867 // compilations via JVMCI will not actually block until JVMCI is initialized. 3868 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3869 } 3870 } 3871 #endif 3872 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3873 // Postpone completion of compiler initialization to after JVMCI 3874 // is initialized to avoid timeouts of blocking compilations. 3875 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3876 CompileBroker::compilation_init_phase2(); 3877 } 3878 #endif 3879 3880 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3881 // It is done after compilers are initialized, because otherwise compilations of 3882 // signature polymorphic MH intrinsics can be missed 3883 // (see SystemDictionary::find_method_handle_intrinsic). 3884 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3885 3886 // This will initialize the module system. Only java.base classes can be 3887 // loaded until phase 2 completes 3888 call_initPhase2(CHECK_JNI_ERR); 3889 3890 // Always call even when there are not JVMTI environments yet, since environments 3891 // may be attached late and JVMTI must track phases of VM execution 3892 JvmtiExport::enter_start_phase(); 3893 3894 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3895 JvmtiExport::post_vm_start(); 3896 3897 // Final system initialization including security manager and system class loader 3898 call_initPhase3(CHECK_JNI_ERR); 3899 3900 // cache the system and platform class loaders 3901 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3902 3903 #if INCLUDE_CDS 3904 if (DumpSharedSpaces) { 3905 // capture the module path info from the ModuleEntryTable 3906 ClassLoader::initialize_module_path(THREAD); 3907 } 3908 #endif 3909 3910 #if INCLUDE_JVMCI 3911 if (force_JVMCI_intialization) { 3912 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3913 CompileBroker::compilation_init_phase2(); 3914 } 3915 #endif 3916 3917 // Always call even when there are not JVMTI environments yet, since environments 3918 // may be attached late and JVMTI must track phases of VM execution 3919 JvmtiExport::enter_live_phase(); 3920 3921 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3922 JvmtiExport::post_vm_initialized(); 3923 3924 JFR_ONLY(Jfr::on_vm_start();) 3925 3926 #if INCLUDE_MANAGEMENT 3927 Management::initialize(THREAD); 3928 3929 if (HAS_PENDING_EXCEPTION) { 3930 // management agent fails to start possibly due to 3931 // configuration problem and is responsible for printing 3932 // stack trace if appropriate. Simply exit VM. 3933 vm_exit(1); 3934 } 3935 #endif // INCLUDE_MANAGEMENT 3936 3937 if (MemProfiling) MemProfiler::engage(); 3938 StatSampler::engage(); 3939 if (CheckJNICalls) JniPeriodicChecker::engage(); 3940 3941 BiasedLocking::init(); 3942 3943 #if INCLUDE_RTM_OPT 3944 RTMLockingCounters::init(); 3945 #endif 3946 3947 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3948 call_postVMInitHook(THREAD); 3949 // The Java side of PostVMInitHook.run must deal with all 3950 // exceptions and provide means of diagnosis. 3951 if (HAS_PENDING_EXCEPTION) { 3952 CLEAR_PENDING_EXCEPTION; 3953 } 3954 } 3955 3956 { 3957 MutexLocker ml(PeriodicTask_lock); 3958 // Make sure the WatcherThread can be started by WatcherThread::start() 3959 // or by dynamic enrollment. 3960 WatcherThread::make_startable(); 3961 // Start up the WatcherThread if there are any periodic tasks 3962 // NOTE: All PeriodicTasks should be registered by now. If they 3963 // aren't, late joiners might appear to start slowly (we might 3964 // take a while to process their first tick). 3965 if (PeriodicTask::num_tasks() > 0) { 3966 WatcherThread::start(); 3967 } 3968 } 3969 3970 create_vm_timer.end(); 3971 #ifdef ASSERT 3972 _vm_complete = true; 3973 #endif 3974 3975 if (DumpSharedSpaces) { 3976 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3977 ShouldNotReachHere(); 3978 } 3979 3980 return JNI_OK; 3981 } 3982 3983 // type for the Agent_OnLoad and JVM_OnLoad entry points 3984 extern "C" { 3985 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3986 } 3987 // Find a command line agent library and return its entry point for 3988 // -agentlib: -agentpath: -Xrun 3989 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3990 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3991 const char *on_load_symbols[], 3992 size_t num_symbol_entries) { 3993 OnLoadEntry_t on_load_entry = NULL; 3994 void *library = NULL; 3995 3996 if (!agent->valid()) { 3997 char buffer[JVM_MAXPATHLEN]; 3998 char ebuf[1024] = ""; 3999 const char *name = agent->name(); 4000 const char *msg = "Could not find agent library "; 4001 4002 // First check to see if agent is statically linked into executable 4003 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4004 library = agent->os_lib(); 4005 } else if (agent->is_absolute_path()) { 4006 library = os::dll_load(name, ebuf, sizeof ebuf); 4007 if (library == NULL) { 4008 const char *sub_msg = " in absolute path, with error: "; 4009 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4010 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4011 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4012 // If we can't find the agent, exit. 4013 vm_exit_during_initialization(buf, NULL); 4014 FREE_C_HEAP_ARRAY(char, buf); 4015 } 4016 } else { 4017 // Try to load the agent from the standard dll directory 4018 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4019 name)) { 4020 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4021 } 4022 if (library == NULL) { // Try the library path directory. 4023 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4024 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4025 } 4026 if (library == NULL) { 4027 const char *sub_msg = " on the library path, with error: "; 4028 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4029 4030 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4031 strlen(ebuf) + strlen(sub_msg2) + 1; 4032 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4033 if (!agent->is_instrument_lib()) { 4034 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4035 } else { 4036 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4037 } 4038 // If we can't find the agent, exit. 4039 vm_exit_during_initialization(buf, NULL); 4040 FREE_C_HEAP_ARRAY(char, buf); 4041 } 4042 } 4043 } 4044 agent->set_os_lib(library); 4045 agent->set_valid(); 4046 } 4047 4048 // Find the OnLoad function. 4049 on_load_entry = 4050 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4051 false, 4052 on_load_symbols, 4053 num_symbol_entries)); 4054 return on_load_entry; 4055 } 4056 4057 // Find the JVM_OnLoad entry point 4058 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4059 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4060 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4061 } 4062 4063 // Find the Agent_OnLoad entry point 4064 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4065 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4066 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4067 } 4068 4069 // For backwards compatibility with -Xrun 4070 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4071 // treated like -agentpath: 4072 // Must be called before agent libraries are created 4073 void Threads::convert_vm_init_libraries_to_agents() { 4074 AgentLibrary* agent; 4075 AgentLibrary* next; 4076 4077 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4078 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4079 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4080 4081 // If there is an JVM_OnLoad function it will get called later, 4082 // otherwise see if there is an Agent_OnLoad 4083 if (on_load_entry == NULL) { 4084 on_load_entry = lookup_agent_on_load(agent); 4085 if (on_load_entry != NULL) { 4086 // switch it to the agent list -- so that Agent_OnLoad will be called, 4087 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4088 Arguments::convert_library_to_agent(agent); 4089 } else { 4090 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4091 } 4092 } 4093 } 4094 } 4095 4096 // Create agents for -agentlib: -agentpath: and converted -Xrun 4097 // Invokes Agent_OnLoad 4098 // Called very early -- before JavaThreads exist 4099 void Threads::create_vm_init_agents() { 4100 extern struct JavaVM_ main_vm; 4101 AgentLibrary* agent; 4102 4103 JvmtiExport::enter_onload_phase(); 4104 4105 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4106 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4107 4108 if (on_load_entry != NULL) { 4109 // Invoke the Agent_OnLoad function 4110 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4111 if (err != JNI_OK) { 4112 vm_exit_during_initialization("agent library failed to init", agent->name()); 4113 } 4114 } else { 4115 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4116 } 4117 } 4118 JvmtiExport::enter_primordial_phase(); 4119 } 4120 4121 extern "C" { 4122 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4123 } 4124 4125 void Threads::shutdown_vm_agents() { 4126 // Send any Agent_OnUnload notifications 4127 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4128 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4129 extern struct JavaVM_ main_vm; 4130 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4131 4132 // Find the Agent_OnUnload function. 4133 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4134 os::find_agent_function(agent, 4135 false, 4136 on_unload_symbols, 4137 num_symbol_entries)); 4138 4139 // Invoke the Agent_OnUnload function 4140 if (unload_entry != NULL) { 4141 JavaThread* thread = JavaThread::current(); 4142 ThreadToNativeFromVM ttn(thread); 4143 HandleMark hm(thread); 4144 (*unload_entry)(&main_vm); 4145 } 4146 } 4147 } 4148 4149 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4150 // Invokes JVM_OnLoad 4151 void Threads::create_vm_init_libraries() { 4152 extern struct JavaVM_ main_vm; 4153 AgentLibrary* agent; 4154 4155 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4156 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4157 4158 if (on_load_entry != NULL) { 4159 // Invoke the JVM_OnLoad function 4160 JavaThread* thread = JavaThread::current(); 4161 ThreadToNativeFromVM ttn(thread); 4162 HandleMark hm(thread); 4163 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4164 if (err != JNI_OK) { 4165 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4166 } 4167 } else { 4168 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4169 } 4170 } 4171 } 4172 4173 4174 // Last thread running calls java.lang.Shutdown.shutdown() 4175 void JavaThread::invoke_shutdown_hooks() { 4176 HandleMark hm(this); 4177 4178 // We could get here with a pending exception, if so clear it now. 4179 if (this->has_pending_exception()) { 4180 this->clear_pending_exception(); 4181 } 4182 4183 EXCEPTION_MARK; 4184 Klass* shutdown_klass = 4185 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4186 THREAD); 4187 if (shutdown_klass != NULL) { 4188 // SystemDictionary::resolve_or_null will return null if there was 4189 // an exception. If we cannot load the Shutdown class, just don't 4190 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4191 // won't be run. Note that if a shutdown hook was registered, 4192 // the Shutdown class would have already been loaded 4193 // (Runtime.addShutdownHook will load it). 4194 JavaValue result(T_VOID); 4195 JavaCalls::call_static(&result, 4196 shutdown_klass, 4197 vmSymbols::shutdown_method_name(), 4198 vmSymbols::void_method_signature(), 4199 THREAD); 4200 } 4201 CLEAR_PENDING_EXCEPTION; 4202 } 4203 4204 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4205 // the program falls off the end of main(). Another VM exit path is through 4206 // vm_exit() when the program calls System.exit() to return a value or when 4207 // there is a serious error in VM. The two shutdown paths are not exactly 4208 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4209 // and VM_Exit op at VM level. 4210 // 4211 // Shutdown sequence: 4212 // + Shutdown native memory tracking if it is on 4213 // + Wait until we are the last non-daemon thread to execute 4214 // <-- every thing is still working at this moment --> 4215 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4216 // shutdown hooks 4217 // + Call before_exit(), prepare for VM exit 4218 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4219 // currently the only user of this mechanism is File.deleteOnExit()) 4220 // > stop StatSampler, watcher thread, CMS threads, 4221 // post thread end and vm death events to JVMTI, 4222 // stop signal thread 4223 // + Call JavaThread::exit(), it will: 4224 // > release JNI handle blocks, remove stack guard pages 4225 // > remove this thread from Threads list 4226 // <-- no more Java code from this thread after this point --> 4227 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4228 // the compiler threads at safepoint 4229 // <-- do not use anything that could get blocked by Safepoint --> 4230 // + Disable tracing at JNI/JVM barriers 4231 // + Set _vm_exited flag for threads that are still running native code 4232 // + Call exit_globals() 4233 // > deletes tty 4234 // > deletes PerfMemory resources 4235 // + Delete this thread 4236 // + Return to caller 4237 4238 bool Threads::destroy_vm() { 4239 JavaThread* thread = JavaThread::current(); 4240 4241 #ifdef ASSERT 4242 _vm_complete = false; 4243 #endif 4244 // Wait until we are the last non-daemon thread to execute 4245 { MutexLocker nu(Threads_lock); 4246 while (Threads::number_of_non_daemon_threads() > 1) 4247 // This wait should make safepoint checks, wait without a timeout, 4248 // and wait as a suspend-equivalent condition. 4249 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4250 Mutex::_as_suspend_equivalent_flag); 4251 } 4252 4253 EventShutdown e; 4254 if (e.should_commit()) { 4255 e.set_reason("No remaining non-daemon Java threads"); 4256 e.commit(); 4257 } 4258 4259 // Hang forever on exit if we are reporting an error. 4260 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4261 os::infinite_sleep(); 4262 } 4263 os::wait_for_keypress_at_exit(); 4264 4265 // run Java level shutdown hooks 4266 thread->invoke_shutdown_hooks(); 4267 4268 before_exit(thread); 4269 4270 thread->exit(true); 4271 4272 // Stop VM thread. 4273 { 4274 // 4945125 The vm thread comes to a safepoint during exit. 4275 // GC vm_operations can get caught at the safepoint, and the 4276 // heap is unparseable if they are caught. Grab the Heap_lock 4277 // to prevent this. The GC vm_operations will not be able to 4278 // queue until after the vm thread is dead. After this point, 4279 // we'll never emerge out of the safepoint before the VM exits. 4280 4281 MutexLocker ml(Heap_lock); 4282 4283 VMThread::wait_for_vm_thread_exit(); 4284 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4285 VMThread::destroy(); 4286 } 4287 4288 // Now, all Java threads are gone except daemon threads. Daemon threads 4289 // running Java code or in VM are stopped by the Safepoint. However, 4290 // daemon threads executing native code are still running. But they 4291 // will be stopped at native=>Java/VM barriers. Note that we can't 4292 // simply kill or suspend them, as it is inherently deadlock-prone. 4293 4294 VM_Exit::set_vm_exited(); 4295 4296 // Clean up ideal graph printers after the VMThread has started 4297 // the final safepoint which will block all the Compiler threads. 4298 // Note that this Thread has already logically exited so the 4299 // clean_up() function's use of a JavaThreadIteratorWithHandle 4300 // would be a problem except set_vm_exited() has remembered the 4301 // shutdown thread which is granted a policy exception. 4302 #if defined(COMPILER2) && !defined(PRODUCT) 4303 IdealGraphPrinter::clean_up(); 4304 #endif 4305 4306 notify_vm_shutdown(); 4307 4308 // exit_globals() will delete tty 4309 exit_globals(); 4310 4311 // We are after VM_Exit::set_vm_exited() so we can't call 4312 // thread->smr_delete() or we will block on the Threads_lock. 4313 // Deleting the shutdown thread here is safe because another 4314 // JavaThread cannot have an active ThreadsListHandle for 4315 // this JavaThread. 4316 delete thread; 4317 4318 #if INCLUDE_JVMCI 4319 if (JVMCICounterSize > 0) { 4320 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4321 } 4322 #endif 4323 4324 LogConfiguration::finalize(); 4325 4326 return true; 4327 } 4328 4329 4330 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4331 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4332 return is_supported_jni_version(version); 4333 } 4334 4335 4336 jboolean Threads::is_supported_jni_version(jint version) { 4337 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4338 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4339 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4340 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4341 if (version == JNI_VERSION_9) return JNI_TRUE; 4342 if (version == JNI_VERSION_10) return JNI_TRUE; 4343 return JNI_FALSE; 4344 } 4345 4346 4347 void Threads::add(JavaThread* p, bool force_daemon) { 4348 // The threads lock must be owned at this point 4349 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4350 4351 BarrierSet::barrier_set()->on_thread_attach(p); 4352 4353 p->set_next(_thread_list); 4354 _thread_list = p; 4355 4356 // Once a JavaThread is added to the Threads list, smr_delete() has 4357 // to be used to delete it. Otherwise we can just delete it directly. 4358 p->set_on_thread_list(); 4359 4360 _number_of_threads++; 4361 oop threadObj = p->threadObj(); 4362 bool daemon = true; 4363 // Bootstrapping problem: threadObj can be null for initial 4364 // JavaThread (or for threads attached via JNI) 4365 if ((!force_daemon) && !is_daemon((threadObj))) { 4366 _number_of_non_daemon_threads++; 4367 daemon = false; 4368 } 4369 4370 ThreadService::add_thread(p, daemon); 4371 4372 // Maintain fast thread list 4373 ThreadsSMRSupport::add_thread(p); 4374 4375 // Possible GC point. 4376 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4377 } 4378 4379 void Threads::remove(JavaThread* p) { 4380 4381 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4382 ObjectSynchronizer::omFlush(p); 4383 4384 // Extra scope needed for Thread_lock, so we can check 4385 // that we do not remove thread without safepoint code notice 4386 { MutexLocker ml(Threads_lock); 4387 4388 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4389 4390 // Maintain fast thread list 4391 ThreadsSMRSupport::remove_thread(p); 4392 4393 JavaThread* current = _thread_list; 4394 JavaThread* prev = NULL; 4395 4396 while (current != p) { 4397 prev = current; 4398 current = current->next(); 4399 } 4400 4401 if (prev) { 4402 prev->set_next(current->next()); 4403 } else { 4404 _thread_list = p->next(); 4405 } 4406 4407 _number_of_threads--; 4408 oop threadObj = p->threadObj(); 4409 bool daemon = true; 4410 if (!is_daemon(threadObj)) { 4411 _number_of_non_daemon_threads--; 4412 daemon = false; 4413 4414 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4415 // on destroy_vm will wake up. 4416 if (number_of_non_daemon_threads() == 1) { 4417 Threads_lock->notify_all(); 4418 } 4419 } 4420 ThreadService::remove_thread(p, daemon); 4421 4422 // Make sure that safepoint code disregard this thread. This is needed since 4423 // the thread might mess around with locks after this point. This can cause it 4424 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4425 // of this thread since it is removed from the queue. 4426 p->set_terminated_value(); 4427 } // unlock Threads_lock 4428 4429 // Since Events::log uses a lock, we grab it outside the Threads_lock 4430 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4431 } 4432 4433 // Operations on the Threads list for GC. These are not explicitly locked, 4434 // but the garbage collector must provide a safe context for them to run. 4435 // In particular, these things should never be called when the Threads_lock 4436 // is held by some other thread. (Note: the Safepoint abstraction also 4437 // uses the Threads_lock to guarantee this property. It also makes sure that 4438 // all threads gets blocked when exiting or starting). 4439 4440 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4441 ALL_JAVA_THREADS(p) { 4442 p->oops_do(f, cf); 4443 } 4444 VMThread::vm_thread()->oops_do(f, cf); 4445 } 4446 4447 void Threads::change_thread_claim_parity() { 4448 // Set the new claim parity. 4449 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4450 "Not in range."); 4451 _thread_claim_parity++; 4452 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4453 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4454 "Not in range."); 4455 } 4456 4457 #ifdef ASSERT 4458 void Threads::assert_all_threads_claimed() { 4459 ALL_JAVA_THREADS(p) { 4460 const int thread_parity = p->oops_do_parity(); 4461 assert((thread_parity == _thread_claim_parity), 4462 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4463 } 4464 VMThread* vmt = VMThread::vm_thread(); 4465 const int thread_parity = vmt->oops_do_parity(); 4466 assert((thread_parity == _thread_claim_parity), 4467 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4468 } 4469 #endif // ASSERT 4470 4471 class ParallelOopsDoThreadClosure : public ThreadClosure { 4472 private: 4473 OopClosure* _f; 4474 CodeBlobClosure* _cf; 4475 public: 4476 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4477 void do_thread(Thread* t) { 4478 t->oops_do(_f, _cf); 4479 } 4480 }; 4481 4482 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4483 ParallelOopsDoThreadClosure tc(f, cf); 4484 possibly_parallel_threads_do(is_par, &tc); 4485 } 4486 4487 void Threads::nmethods_do(CodeBlobClosure* cf) { 4488 ALL_JAVA_THREADS(p) { 4489 // This is used by the code cache sweeper to mark nmethods that are active 4490 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4491 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4492 if(!p->is_Code_cache_sweeper_thread()) { 4493 p->nmethods_do(cf); 4494 } 4495 } 4496 } 4497 4498 void Threads::metadata_do(void f(Metadata*)) { 4499 ALL_JAVA_THREADS(p) { 4500 p->metadata_do(f); 4501 } 4502 } 4503 4504 class ThreadHandlesClosure : public ThreadClosure { 4505 void (*_f)(Metadata*); 4506 public: 4507 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4508 virtual void do_thread(Thread* thread) { 4509 thread->metadata_handles_do(_f); 4510 } 4511 }; 4512 4513 void Threads::metadata_handles_do(void f(Metadata*)) { 4514 // Only walk the Handles in Thread. 4515 ThreadHandlesClosure handles_closure(f); 4516 threads_do(&handles_closure); 4517 } 4518 4519 void Threads::deoptimized_wrt_marked_nmethods() { 4520 ALL_JAVA_THREADS(p) { 4521 p->deoptimized_wrt_marked_nmethods(); 4522 } 4523 } 4524 4525 4526 // Get count Java threads that are waiting to enter the specified monitor. 4527 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4528 int count, 4529 address monitor) { 4530 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4531 4532 int i = 0; 4533 DO_JAVA_THREADS(t_list, p) { 4534 if (!p->can_call_java()) continue; 4535 4536 address pending = (address)p->current_pending_monitor(); 4537 if (pending == monitor) { // found a match 4538 if (i < count) result->append(p); // save the first count matches 4539 i++; 4540 } 4541 } 4542 4543 return result; 4544 } 4545 4546 4547 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4548 address owner) { 4549 // NULL owner means not locked so we can skip the search 4550 if (owner == NULL) return NULL; 4551 4552 DO_JAVA_THREADS(t_list, p) { 4553 // first, see if owner is the address of a Java thread 4554 if (owner == (address)p) return p; 4555 } 4556 4557 // Cannot assert on lack of success here since this function may be 4558 // used by code that is trying to report useful problem information 4559 // like deadlock detection. 4560 if (UseHeavyMonitors) return NULL; 4561 4562 // If we didn't find a matching Java thread and we didn't force use of 4563 // heavyweight monitors, then the owner is the stack address of the 4564 // Lock Word in the owning Java thread's stack. 4565 // 4566 JavaThread* the_owner = NULL; 4567 DO_JAVA_THREADS(t_list, q) { 4568 if (q->is_lock_owned(owner)) { 4569 the_owner = q; 4570 break; 4571 } 4572 } 4573 4574 // cannot assert on lack of success here; see above comment 4575 return the_owner; 4576 } 4577 4578 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4579 void Threads::print_on(outputStream* st, bool print_stacks, 4580 bool internal_format, bool print_concurrent_locks, 4581 bool print_extended_info) { 4582 char buf[32]; 4583 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4584 4585 st->print_cr("Full thread dump %s (%s %s):", 4586 VM_Version::vm_name(), 4587 VM_Version::vm_release(), 4588 VM_Version::vm_info_string()); 4589 st->cr(); 4590 4591 #if INCLUDE_SERVICES 4592 // Dump concurrent locks 4593 ConcurrentLocksDump concurrent_locks; 4594 if (print_concurrent_locks) { 4595 concurrent_locks.dump_at_safepoint(); 4596 } 4597 #endif // INCLUDE_SERVICES 4598 4599 ThreadsSMRSupport::print_info_on(st); 4600 st->cr(); 4601 4602 ALL_JAVA_THREADS(p) { 4603 ResourceMark rm; 4604 p->print_on(st, print_extended_info); 4605 if (print_stacks) { 4606 if (internal_format) { 4607 p->trace_stack(); 4608 } else { 4609 p->print_stack_on(st); 4610 } 4611 } 4612 st->cr(); 4613 #if INCLUDE_SERVICES 4614 if (print_concurrent_locks) { 4615 concurrent_locks.print_locks_on(p, st); 4616 } 4617 #endif // INCLUDE_SERVICES 4618 } 4619 4620 VMThread::vm_thread()->print_on(st); 4621 st->cr(); 4622 Universe::heap()->print_gc_threads_on(st); 4623 WatcherThread* wt = WatcherThread::watcher_thread(); 4624 if (wt != NULL) { 4625 wt->print_on(st); 4626 st->cr(); 4627 } 4628 4629 st->flush(); 4630 } 4631 4632 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4633 int buflen, bool* found_current) { 4634 if (this_thread != NULL) { 4635 bool is_current = (current == this_thread); 4636 *found_current = *found_current || is_current; 4637 st->print("%s", is_current ? "=>" : " "); 4638 4639 st->print(PTR_FORMAT, p2i(this_thread)); 4640 st->print(" "); 4641 this_thread->print_on_error(st, buf, buflen); 4642 st->cr(); 4643 } 4644 } 4645 4646 class PrintOnErrorClosure : public ThreadClosure { 4647 outputStream* _st; 4648 Thread* _current; 4649 char* _buf; 4650 int _buflen; 4651 bool* _found_current; 4652 public: 4653 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4654 int buflen, bool* found_current) : 4655 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4656 4657 virtual void do_thread(Thread* thread) { 4658 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4659 } 4660 }; 4661 4662 // Threads::print_on_error() is called by fatal error handler. It's possible 4663 // that VM is not at safepoint and/or current thread is inside signal handler. 4664 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4665 // memory (even in resource area), it might deadlock the error handler. 4666 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4667 int buflen) { 4668 ThreadsSMRSupport::print_info_on(st); 4669 st->cr(); 4670 4671 bool found_current = false; 4672 st->print_cr("Java Threads: ( => current thread )"); 4673 ALL_JAVA_THREADS(thread) { 4674 print_on_error(thread, st, current, buf, buflen, &found_current); 4675 } 4676 st->cr(); 4677 4678 st->print_cr("Other Threads:"); 4679 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4680 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4681 4682 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4683 Universe::heap()->gc_threads_do(&print_closure); 4684 4685 if (!found_current) { 4686 st->cr(); 4687 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4688 current->print_on_error(st, buf, buflen); 4689 st->cr(); 4690 } 4691 st->cr(); 4692 4693 st->print_cr("Threads with active compile tasks:"); 4694 print_threads_compiling(st, buf, buflen); 4695 } 4696 4697 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4698 ALL_JAVA_THREADS(thread) { 4699 if (thread->is_Compiler_thread()) { 4700 CompilerThread* ct = (CompilerThread*) thread; 4701 4702 // Keep task in local variable for NULL check. 4703 // ct->_task might be set to NULL by concurring compiler thread 4704 // because it completed the compilation. The task is never freed, 4705 // though, just returned to a free list. 4706 CompileTask* task = ct->task(); 4707 if (task != NULL) { 4708 thread->print_name_on_error(st, buf, buflen); 4709 task->print(st, NULL, true, true); 4710 } 4711 } 4712 } 4713 } 4714 4715 4716 // Internal SpinLock and Mutex 4717 // Based on ParkEvent 4718 4719 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4720 // 4721 // We employ SpinLocks _only for low-contention, fixed-length 4722 // short-duration critical sections where we're concerned 4723 // about native mutex_t or HotSpot Mutex:: latency. 4724 // The mux construct provides a spin-then-block mutual exclusion 4725 // mechanism. 4726 // 4727 // Testing has shown that contention on the ListLock guarding gFreeList 4728 // is common. If we implement ListLock as a simple SpinLock it's common 4729 // for the JVM to devolve to yielding with little progress. This is true 4730 // despite the fact that the critical sections protected by ListLock are 4731 // extremely short. 4732 // 4733 // TODO-FIXME: ListLock should be of type SpinLock. 4734 // We should make this a 1st-class type, integrated into the lock 4735 // hierarchy as leaf-locks. Critically, the SpinLock structure 4736 // should have sufficient padding to avoid false-sharing and excessive 4737 // cache-coherency traffic. 4738 4739 4740 typedef volatile int SpinLockT; 4741 4742 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4743 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4744 return; // normal fast-path return 4745 } 4746 4747 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4748 int ctr = 0; 4749 int Yields = 0; 4750 for (;;) { 4751 while (*adr != 0) { 4752 ++ctr; 4753 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4754 if (Yields > 5) { 4755 os::naked_short_sleep(1); 4756 } else { 4757 os::naked_yield(); 4758 ++Yields; 4759 } 4760 } else { 4761 SpinPause(); 4762 } 4763 } 4764 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4765 } 4766 } 4767 4768 void Thread::SpinRelease(volatile int * adr) { 4769 assert(*adr != 0, "invariant"); 4770 OrderAccess::fence(); // guarantee at least release consistency. 4771 // Roach-motel semantics. 4772 // It's safe if subsequent LDs and STs float "up" into the critical section, 4773 // but prior LDs and STs within the critical section can't be allowed 4774 // to reorder or float past the ST that releases the lock. 4775 // Loads and stores in the critical section - which appear in program 4776 // order before the store that releases the lock - must also appear 4777 // before the store that releases the lock in memory visibility order. 4778 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4779 // the ST of 0 into the lock-word which releases the lock, so fence 4780 // more than covers this on all platforms. 4781 *adr = 0; 4782 } 4783 4784 // muxAcquire and muxRelease: 4785 // 4786 // * muxAcquire and muxRelease support a single-word lock-word construct. 4787 // The LSB of the word is set IFF the lock is held. 4788 // The remainder of the word points to the head of a singly-linked list 4789 // of threads blocked on the lock. 4790 // 4791 // * The current implementation of muxAcquire-muxRelease uses its own 4792 // dedicated Thread._MuxEvent instance. If we're interested in 4793 // minimizing the peak number of extant ParkEvent instances then 4794 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4795 // as certain invariants were satisfied. Specifically, care would need 4796 // to be taken with regards to consuming unpark() "permits". 4797 // A safe rule of thumb is that a thread would never call muxAcquire() 4798 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4799 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4800 // consume an unpark() permit intended for monitorenter, for instance. 4801 // One way around this would be to widen the restricted-range semaphore 4802 // implemented in park(). Another alternative would be to provide 4803 // multiple instances of the PlatformEvent() for each thread. One 4804 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4805 // 4806 // * Usage: 4807 // -- Only as leaf locks 4808 // -- for short-term locking only as muxAcquire does not perform 4809 // thread state transitions. 4810 // 4811 // Alternatives: 4812 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4813 // but with parking or spin-then-park instead of pure spinning. 4814 // * Use Taura-Oyama-Yonenzawa locks. 4815 // * It's possible to construct a 1-0 lock if we encode the lockword as 4816 // (List,LockByte). Acquire will CAS the full lockword while Release 4817 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4818 // acquiring threads use timers (ParkTimed) to detect and recover from 4819 // the stranding window. Thread/Node structures must be aligned on 256-byte 4820 // boundaries by using placement-new. 4821 // * Augment MCS with advisory back-link fields maintained with CAS(). 4822 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4823 // The validity of the backlinks must be ratified before we trust the value. 4824 // If the backlinks are invalid the exiting thread must back-track through the 4825 // the forward links, which are always trustworthy. 4826 // * Add a successor indication. The LockWord is currently encoded as 4827 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4828 // to provide the usual futile-wakeup optimization. 4829 // See RTStt for details. 4830 // 4831 4832 4833 const intptr_t LOCKBIT = 1; 4834 4835 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4836 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4837 if (w == 0) return; 4838 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4839 return; 4840 } 4841 4842 ParkEvent * const Self = Thread::current()->_MuxEvent; 4843 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4844 for (;;) { 4845 int its = (os::is_MP() ? 100 : 0) + 1; 4846 4847 // Optional spin phase: spin-then-park strategy 4848 while (--its >= 0) { 4849 w = *Lock; 4850 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4851 return; 4852 } 4853 } 4854 4855 Self->reset(); 4856 Self->OnList = intptr_t(Lock); 4857 // The following fence() isn't _strictly necessary as the subsequent 4858 // CAS() both serializes execution and ratifies the fetched *Lock value. 4859 OrderAccess::fence(); 4860 for (;;) { 4861 w = *Lock; 4862 if ((w & LOCKBIT) == 0) { 4863 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4864 Self->OnList = 0; // hygiene - allows stronger asserts 4865 return; 4866 } 4867 continue; // Interference -- *Lock changed -- Just retry 4868 } 4869 assert(w & LOCKBIT, "invariant"); 4870 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4871 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4872 } 4873 4874 while (Self->OnList != 0) { 4875 Self->park(); 4876 } 4877 } 4878 } 4879 4880 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4881 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4882 if (w == 0) return; 4883 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4884 return; 4885 } 4886 4887 ParkEvent * ReleaseAfter = NULL; 4888 if (ev == NULL) { 4889 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4890 } 4891 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4892 for (;;) { 4893 guarantee(ev->OnList == 0, "invariant"); 4894 int its = (os::is_MP() ? 100 : 0) + 1; 4895 4896 // Optional spin phase: spin-then-park strategy 4897 while (--its >= 0) { 4898 w = *Lock; 4899 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4900 if (ReleaseAfter != NULL) { 4901 ParkEvent::Release(ReleaseAfter); 4902 } 4903 return; 4904 } 4905 } 4906 4907 ev->reset(); 4908 ev->OnList = intptr_t(Lock); 4909 // The following fence() isn't _strictly necessary as the subsequent 4910 // CAS() both serializes execution and ratifies the fetched *Lock value. 4911 OrderAccess::fence(); 4912 for (;;) { 4913 w = *Lock; 4914 if ((w & LOCKBIT) == 0) { 4915 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4916 ev->OnList = 0; 4917 // We call ::Release while holding the outer lock, thus 4918 // artificially lengthening the critical section. 4919 // Consider deferring the ::Release() until the subsequent unlock(), 4920 // after we've dropped the outer lock. 4921 if (ReleaseAfter != NULL) { 4922 ParkEvent::Release(ReleaseAfter); 4923 } 4924 return; 4925 } 4926 continue; // Interference -- *Lock changed -- Just retry 4927 } 4928 assert(w & LOCKBIT, "invariant"); 4929 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4930 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4931 } 4932 4933 while (ev->OnList != 0) { 4934 ev->park(); 4935 } 4936 } 4937 } 4938 4939 // Release() must extract a successor from the list and then wake that thread. 4940 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4941 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4942 // Release() would : 4943 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4944 // (B) Extract a successor from the private list "in-hand" 4945 // (C) attempt to CAS() the residual back into *Lock over null. 4946 // If there were any newly arrived threads and the CAS() would fail. 4947 // In that case Release() would detach the RATs, re-merge the list in-hand 4948 // with the RATs and repeat as needed. Alternately, Release() might 4949 // detach and extract a successor, but then pass the residual list to the wakee. 4950 // The wakee would be responsible for reattaching and remerging before it 4951 // competed for the lock. 4952 // 4953 // Both "pop" and DMR are immune from ABA corruption -- there can be 4954 // multiple concurrent pushers, but only one popper or detacher. 4955 // This implementation pops from the head of the list. This is unfair, 4956 // but tends to provide excellent throughput as hot threads remain hot. 4957 // (We wake recently run threads first). 4958 // 4959 // All paths through muxRelease() will execute a CAS. 4960 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4961 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4962 // executed within the critical section are complete and globally visible before the 4963 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4964 void Thread::muxRelease(volatile intptr_t * Lock) { 4965 for (;;) { 4966 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4967 assert(w & LOCKBIT, "invariant"); 4968 if (w == LOCKBIT) return; 4969 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4970 assert(List != NULL, "invariant"); 4971 assert(List->OnList == intptr_t(Lock), "invariant"); 4972 ParkEvent * const nxt = List->ListNext; 4973 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4974 4975 // The following CAS() releases the lock and pops the head element. 4976 // The CAS() also ratifies the previously fetched lock-word value. 4977 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4978 continue; 4979 } 4980 List->OnList = 0; 4981 OrderAccess::fence(); 4982 List->unpark(); 4983 return; 4984 } 4985 } 4986 4987 4988 void Threads::verify() { 4989 ALL_JAVA_THREADS(p) { 4990 p->verify(); 4991 } 4992 VMThread* thread = VMThread::vm_thread(); 4993 if (thread != NULL) thread->verify(); 4994 }