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 "jvmtifiles/jvmtiEnv.hpp" 45 #include "logging/log.hpp" 46 #include "logging/logConfiguration.hpp" 47 #include "logging/logStream.hpp" 48 #include "memory/allocation.inline.hpp" 49 #include "memory/metaspaceShared.hpp" 50 #include "memory/oopFactory.hpp" 51 #include "memory/resourceArea.hpp" 52 #include "memory/universe.hpp" 53 #include "oops/access.inline.hpp" 54 #include "oops/instanceKlass.hpp" 55 #include "oops/objArrayOop.hpp" 56 #include "oops/oop.inline.hpp" 57 #include "oops/symbol.hpp" 58 #include "oops/typeArrayOop.inline.hpp" 59 #include "oops/verifyOopClosure.hpp" 60 #include "prims/jvm_misc.hpp" 61 #include "prims/jvmtiExport.hpp" 62 #include "prims/jvmtiThreadState.hpp" 63 #include "runtime/arguments.hpp" 64 #include "runtime/atomic.hpp" 65 #include "runtime/biasedLocking.hpp" 66 #include "runtime/fieldDescriptor.inline.hpp" 67 #include "runtime/flags/jvmFlagConstraintList.hpp" 68 #include "runtime/flags/jvmFlagRangeList.hpp" 69 #include "runtime/flags/jvmFlagWriteableList.hpp" 70 #include "runtime/deoptimization.hpp" 71 #include "runtime/frame.inline.hpp" 72 #include "runtime/handshake.hpp" 73 #include "runtime/init.hpp" 74 #include "runtime/interfaceSupport.inline.hpp" 75 #include "runtime/java.hpp" 76 #include "runtime/javaCalls.hpp" 77 #include "runtime/jniHandles.inline.hpp" 78 #include "runtime/jniPeriodicChecker.hpp" 79 #include "runtime/memprofiler.hpp" 80 #include "runtime/mutexLocker.hpp" 81 #include "runtime/objectMonitor.hpp" 82 #include "runtime/orderAccess.hpp" 83 #include "runtime/osThread.hpp" 84 #include "runtime/prefetch.inline.hpp" 85 #include "runtime/safepoint.hpp" 86 #include "runtime/safepointMechanism.inline.hpp" 87 #include "runtime/safepointVerifiers.hpp" 88 #include "runtime/sharedRuntime.hpp" 89 #include "runtime/statSampler.hpp" 90 #include "runtime/stubRoutines.hpp" 91 #include "runtime/sweeper.hpp" 92 #include "runtime/task.hpp" 93 #include "runtime/thread.inline.hpp" 94 #include "runtime/threadCritical.hpp" 95 #include "runtime/threadSMR.inline.hpp" 96 #include "runtime/threadStatisticalInfo.hpp" 97 #include "runtime/timer.hpp" 98 #include "runtime/timerTrace.hpp" 99 #include "runtime/vframe.inline.hpp" 100 #include "runtime/vframeArray.hpp" 101 #include "runtime/vframe_hp.hpp" 102 #include "runtime/vmThread.hpp" 103 #include "runtime/vm_operations.hpp" 104 #include "runtime/vm_version.hpp" 105 #include "services/attachListener.hpp" 106 #include "services/management.hpp" 107 #include "services/memTracker.hpp" 108 #include "services/threadService.hpp" 109 #include "utilities/align.hpp" 110 #include "utilities/copy.hpp" 111 #include "utilities/defaultStream.hpp" 112 #include "utilities/dtrace.hpp" 113 #include "utilities/events.hpp" 114 #include "utilities/macros.hpp" 115 #include "utilities/preserveException.hpp" 116 #include "utilities/singleWriterSynchronizer.hpp" 117 #include "utilities/vmError.hpp" 118 #if INCLUDE_JVMCI 119 #include "jvmci/jvmciCompiler.hpp" 120 #include "jvmci/jvmciRuntime.hpp" 121 #include "logging/logHandle.hpp" 122 #endif 123 #ifdef COMPILER1 124 #include "c1/c1_Compiler.hpp" 125 #endif 126 #ifdef COMPILER2 127 #include "opto/c2compiler.hpp" 128 #include "opto/idealGraphPrinter.hpp" 129 #endif 130 #if INCLUDE_RTM_OPT 131 #include "runtime/rtmLocking.hpp" 132 #endif 133 #if INCLUDE_JFR 134 #include "jfr/jfr.hpp" 135 #endif 136 137 // Initialization after module runtime initialization 138 void universe_post_module_init(); // must happen after call_initPhase2 139 140 #ifdef DTRACE_ENABLED 141 142 // Only bother with this argument setup if dtrace is available 143 144 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 145 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 146 147 #define DTRACE_THREAD_PROBE(probe, javathread) \ 148 { \ 149 ResourceMark rm(this); \ 150 int len = 0; \ 151 const char* name = (javathread)->get_thread_name(); \ 152 len = strlen(name); \ 153 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 154 (char *) name, len, \ 155 java_lang_Thread::thread_id((javathread)->threadObj()), \ 156 (uintptr_t) (javathread)->osthread()->thread_id(), \ 157 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 158 } 159 160 #else // ndef DTRACE_ENABLED 161 162 #define DTRACE_THREAD_PROBE(probe, javathread) 163 164 #endif // ndef DTRACE_ENABLED 165 166 #ifndef USE_LIBRARY_BASED_TLS_ONLY 167 // Current thread is maintained as a thread-local variable 168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 169 #endif 170 171 // ======= Thread ======== 172 // Support for forcing alignment of thread objects for biased locking 173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 174 if (UseBiasedLocking) { 175 const int alignment = markOopDesc::biased_lock_alignment; 176 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 177 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 178 : AllocateHeap(aligned_size, flags, CURRENT_PC, 179 AllocFailStrategy::RETURN_NULL); 180 void* aligned_addr = align_up(real_malloc_addr, alignment); 181 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 182 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 183 "JavaThread alignment code overflowed allocated storage"); 184 if (aligned_addr != real_malloc_addr) { 185 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 186 p2i(real_malloc_addr), 187 p2i(aligned_addr)); 188 } 189 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 190 return aligned_addr; 191 } else { 192 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 193 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 194 } 195 } 196 197 void Thread::operator delete(void* p) { 198 if (UseBiasedLocking) { 199 FreeHeap(((Thread*) p)->_real_malloc_address); 200 } else { 201 FreeHeap(p); 202 } 203 } 204 205 void JavaThread::smr_delete() { 206 if (_on_thread_list) { 207 ThreadsSMRSupport::smr_delete(this); 208 } else { 209 delete this; 210 } 211 } 212 213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 214 // JavaThread 215 216 217 Thread::Thread() { 218 // stack and get_thread 219 set_stack_base(NULL); 220 set_stack_size(0); 221 set_self_raw_id(0); 222 set_lgrp_id(-1); 223 DEBUG_ONLY(clear_suspendible_thread();) 224 225 // allocated data structures 226 set_osthread(NULL); 227 set_resource_area(new (mtThread)ResourceArea()); 228 DEBUG_ONLY(_current_resource_mark = NULL;) 229 set_handle_area(new (mtThread) HandleArea(NULL)); 230 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 231 set_active_handles(NULL); 232 set_free_handle_block(NULL); 233 set_last_handle_mark(NULL); 234 DEBUG_ONLY(_missed_ic_stub_refill_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 JFR_ONLY(Jfr::on_thread_start(this);) 373 374 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 375 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 376 os::current_thread_id(), p2i(stack_base() - stack_size()), 377 p2i(stack_base()), stack_size()/1024); 378 379 // Invoke <ChildClass>::run() 380 this->run(); 381 // Returned from <ChildClass>::run(). Thread finished. 382 383 // Note: at this point the thread object may already have deleted itself. 384 // So from here on do not dereference *this*. 385 386 // If a thread has not deleted itself ("delete this") as part of its 387 // termination sequence, we have to ensure thread-local-storage is 388 // cleared before we actually terminate. No threads should ever be 389 // deleted asynchronously with respect to their termination. 390 if (Thread::current_or_null_safe() != NULL) { 391 assert(Thread::current_or_null_safe() == this, "current thread is wrong"); 392 Thread::clear_thread_current(); 393 } 394 395 } 396 397 Thread::~Thread() { 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 // stack_base can be NULL if the thread is never started or exited before 406 // record_stack_base_and_size called. Although, we would like to ensure 407 // that all started threads do call record_stack_base_and_size(), there is 408 // not proper way to enforce that. 409 #if INCLUDE_NMT 410 if (_stack_base != NULL) { 411 MemTracker::release_thread_stack(stack_end(), stack_size()); 412 #ifdef ASSERT 413 set_stack_base(NULL); 414 #endif 415 } 416 #endif // INCLUDE_NMT 417 418 // deallocate data structures 419 delete resource_area(); 420 // since the handle marks are using the handle area, we have to deallocated the root 421 // handle mark before deallocating the thread's handle area, 422 assert(last_handle_mark() != NULL, "check we have an element"); 423 delete last_handle_mark(); 424 assert(last_handle_mark() == NULL, "check we have reached the end"); 425 426 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 427 // We NULL out the fields for good hygiene. 428 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 429 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 430 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 431 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 432 433 delete handle_area(); 434 delete metadata_handles(); 435 436 // SR_handler uses this as a termination indicator - 437 // needs to happen before os::free_thread() 438 delete _SR_lock; 439 _SR_lock = NULL; 440 441 // osthread() can be NULL, if creation of thread failed. 442 if (osthread() != NULL) os::free_thread(osthread()); 443 444 // clear Thread::current if thread is deleting itself. 445 // Needed to ensure JNI correctly detects non-attached threads. 446 if (this == Thread::current()) { 447 Thread::clear_thread_current(); 448 } 449 450 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 451 } 452 453 #ifdef ASSERT 454 // A JavaThread is considered "dangling" if it is not the current 455 // thread, has been added the Threads list, the system is not at a 456 // safepoint and the Thread is not "protected". 457 // 458 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 459 assert(!thread->is_Java_thread() || Thread::current() == thread || 460 !((JavaThread *) thread)->on_thread_list() || 461 SafepointSynchronize::is_at_safepoint() || 462 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 463 "possibility of dangling Thread pointer"); 464 } 465 #endif 466 467 ThreadPriority Thread::get_priority(const Thread* const thread) { 468 ThreadPriority priority; 469 // Can return an error! 470 (void)os::get_priority(thread, priority); 471 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 472 return priority; 473 } 474 475 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 476 debug_only(check_for_dangling_thread_pointer(thread);) 477 // Can return an error! 478 (void)os::set_priority(thread, priority); 479 } 480 481 482 void Thread::start(Thread* thread) { 483 // Start is different from resume in that its safety is guaranteed by context or 484 // being called from a Java method synchronized on the Thread object. 485 if (!DisableStartThread) { 486 if (thread->is_Java_thread()) { 487 // Initialize the thread state to RUNNABLE before starting this thread. 488 // Can not set it after the thread started because we do not know the 489 // exact thread state at that time. It could be in MONITOR_WAIT or 490 // in SLEEPING or some other state. 491 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 492 java_lang_Thread::RUNNABLE); 493 } 494 os::start_thread(thread); 495 } 496 } 497 498 // Enqueue a VM_Operation to do the job for us - sometime later 499 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 500 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 501 VMThread::execute(vm_stop); 502 } 503 504 505 // Check if an external suspend request has completed (or has been 506 // cancelled). Returns true if the thread is externally suspended and 507 // false otherwise. 508 // 509 // The bits parameter returns information about the code path through 510 // the routine. Useful for debugging: 511 // 512 // set in is_ext_suspend_completed(): 513 // 0x00000001 - routine was entered 514 // 0x00000010 - routine return false at end 515 // 0x00000100 - thread exited (return false) 516 // 0x00000200 - suspend request cancelled (return false) 517 // 0x00000400 - thread suspended (return true) 518 // 0x00001000 - thread is in a suspend equivalent state (return true) 519 // 0x00002000 - thread is native and walkable (return true) 520 // 0x00004000 - thread is native_trans and walkable (needed retry) 521 // 522 // set in wait_for_ext_suspend_completion(): 523 // 0x00010000 - routine was entered 524 // 0x00020000 - suspend request cancelled before loop (return false) 525 // 0x00040000 - thread suspended before loop (return true) 526 // 0x00080000 - suspend request cancelled in loop (return false) 527 // 0x00100000 - thread suspended in loop (return true) 528 // 0x00200000 - suspend not completed during retry loop (return false) 529 530 // Helper class for tracing suspend wait debug bits. 531 // 532 // 0x00000100 indicates that the target thread exited before it could 533 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 534 // 0x00080000 each indicate a cancelled suspend request so they don't 535 // count as wait failures either. 536 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 537 538 class TraceSuspendDebugBits : public StackObj { 539 private: 540 JavaThread * jt; 541 bool is_wait; 542 bool called_by_wait; // meaningful when !is_wait 543 uint32_t * bits; 544 545 public: 546 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 547 uint32_t *_bits) { 548 jt = _jt; 549 is_wait = _is_wait; 550 called_by_wait = _called_by_wait; 551 bits = _bits; 552 } 553 554 ~TraceSuspendDebugBits() { 555 if (!is_wait) { 556 #if 1 557 // By default, don't trace bits for is_ext_suspend_completed() calls. 558 // That trace is very chatty. 559 return; 560 #else 561 if (!called_by_wait) { 562 // If tracing for is_ext_suspend_completed() is enabled, then only 563 // trace calls to it from wait_for_ext_suspend_completion() 564 return; 565 } 566 #endif 567 } 568 569 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 570 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 571 MutexLocker ml(Threads_lock); // needed for get_thread_name() 572 ResourceMark rm; 573 574 tty->print_cr( 575 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 576 jt->get_thread_name(), *bits); 577 578 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 579 } 580 } 581 } 582 }; 583 #undef DEBUG_FALSE_BITS 584 585 586 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 587 uint32_t *bits) { 588 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 589 590 bool did_trans_retry = false; // only do thread_in_native_trans retry once 591 bool do_trans_retry; // flag to force the retry 592 593 *bits |= 0x00000001; 594 595 do { 596 do_trans_retry = false; 597 598 if (is_exiting()) { 599 // Thread is in the process of exiting. This is always checked 600 // first to reduce the risk of dereferencing a freed JavaThread. 601 *bits |= 0x00000100; 602 return false; 603 } 604 605 if (!is_external_suspend()) { 606 // Suspend request is cancelled. This is always checked before 607 // is_ext_suspended() to reduce the risk of a rogue resume 608 // confusing the thread that made the suspend request. 609 *bits |= 0x00000200; 610 return false; 611 } 612 613 if (is_ext_suspended()) { 614 // thread is suspended 615 *bits |= 0x00000400; 616 return true; 617 } 618 619 // Now that we no longer do hard suspends of threads running 620 // native code, the target thread can be changing thread state 621 // while we are in this routine: 622 // 623 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 624 // 625 // We save a copy of the thread state as observed at this moment 626 // and make our decision about suspend completeness based on the 627 // copy. This closes the race where the thread state is seen as 628 // _thread_in_native_trans in the if-thread_blocked check, but is 629 // seen as _thread_blocked in if-thread_in_native_trans check. 630 JavaThreadState save_state = thread_state(); 631 632 if (save_state == _thread_blocked && is_suspend_equivalent()) { 633 // If the thread's state is _thread_blocked and this blocking 634 // condition is known to be equivalent to a suspend, then we can 635 // consider the thread to be externally suspended. This means that 636 // the code that sets _thread_blocked has been modified to do 637 // self-suspension if the blocking condition releases. We also 638 // used to check for CONDVAR_WAIT here, but that is now covered by 639 // the _thread_blocked with self-suspension check. 640 // 641 // Return true since we wouldn't be here unless there was still an 642 // external suspend request. 643 *bits |= 0x00001000; 644 return true; 645 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 646 // Threads running native code will self-suspend on native==>VM/Java 647 // transitions. If its stack is walkable (should always be the case 648 // unless this function is called before the actual java_suspend() 649 // call), then the wait is done. 650 *bits |= 0x00002000; 651 return true; 652 } else if (!called_by_wait && !did_trans_retry && 653 save_state == _thread_in_native_trans && 654 frame_anchor()->walkable()) { 655 // The thread is transitioning from thread_in_native to another 656 // thread state. check_safepoint_and_suspend_for_native_trans() 657 // will force the thread to self-suspend. If it hasn't gotten 658 // there yet we may have caught the thread in-between the native 659 // code check above and the self-suspend. Lucky us. If we were 660 // called by wait_for_ext_suspend_completion(), then it 661 // will be doing the retries so we don't have to. 662 // 663 // Since we use the saved thread state in the if-statement above, 664 // there is a chance that the thread has already transitioned to 665 // _thread_blocked by the time we get here. In that case, we will 666 // make a single unnecessary pass through the logic below. This 667 // doesn't hurt anything since we still do the trans retry. 668 669 *bits |= 0x00004000; 670 671 // Once the thread leaves thread_in_native_trans for another 672 // thread state, we break out of this retry loop. We shouldn't 673 // need this flag to prevent us from getting back here, but 674 // sometimes paranoia is good. 675 did_trans_retry = true; 676 677 // We wait for the thread to transition to a more usable state. 678 for (int i = 1; i <= SuspendRetryCount; i++) { 679 // We used to do an "os::yield_all(i)" call here with the intention 680 // that yielding would increase on each retry. However, the parameter 681 // is ignored on Linux which means the yield didn't scale up. Waiting 682 // on the SR_lock below provides a much more predictable scale up for 683 // the delay. It also provides a simple/direct point to check for any 684 // safepoint requests from the VMThread 685 686 // temporarily drops SR_lock while doing wait with safepoint check 687 // (if we're a JavaThread - the WatcherThread can also call this) 688 // and increase delay with each retry 689 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 690 691 // check the actual thread state instead of what we saved above 692 if (thread_state() != _thread_in_native_trans) { 693 // the thread has transitioned to another thread state so 694 // try all the checks (except this one) one more time. 695 do_trans_retry = true; 696 break; 697 } 698 } // end retry loop 699 700 701 } 702 } while (do_trans_retry); 703 704 *bits |= 0x00000010; 705 return false; 706 } 707 708 // Wait for an external suspend request to complete (or be cancelled). 709 // Returns true if the thread is externally suspended and false otherwise. 710 // 711 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 712 uint32_t *bits) { 713 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 714 false /* !called_by_wait */, bits); 715 716 // local flag copies to minimize SR_lock hold time 717 bool is_suspended; 718 bool pending; 719 uint32_t reset_bits; 720 721 // set a marker so is_ext_suspend_completed() knows we are the caller 722 *bits |= 0x00010000; 723 724 // We use reset_bits to reinitialize the bits value at the top of 725 // each retry loop. This allows the caller to make use of any 726 // unused bits for their own marking purposes. 727 reset_bits = *bits; 728 729 { 730 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 731 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 732 delay, bits); 733 pending = is_external_suspend(); 734 } 735 // must release SR_lock to allow suspension to complete 736 737 if (!pending) { 738 // A cancelled suspend request is the only false return from 739 // is_ext_suspend_completed() that keeps us from entering the 740 // retry loop. 741 *bits |= 0x00020000; 742 return false; 743 } 744 745 if (is_suspended) { 746 *bits |= 0x00040000; 747 return true; 748 } 749 750 for (int i = 1; i <= retries; i++) { 751 *bits = reset_bits; // reinit to only track last retry 752 753 // We used to do an "os::yield_all(i)" call here with the intention 754 // that yielding would increase on each retry. However, the parameter 755 // is ignored on Linux which means the yield didn't scale up. Waiting 756 // on the SR_lock below provides a much more predictable scale up for 757 // the delay. It also provides a simple/direct point to check for any 758 // safepoint requests from the VMThread 759 760 { 761 MutexLocker ml(SR_lock()); 762 // wait with safepoint check (if we're a JavaThread - the WatcherThread 763 // can also call this) and increase delay with each retry 764 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 765 766 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 767 delay, bits); 768 769 // It is possible for the external suspend request to be cancelled 770 // (by a resume) before the actual suspend operation is completed. 771 // Refresh our local copy to see if we still need to wait. 772 pending = is_external_suspend(); 773 } 774 775 if (!pending) { 776 // A cancelled suspend request is the only false return from 777 // is_ext_suspend_completed() that keeps us from staying in the 778 // retry loop. 779 *bits |= 0x00080000; 780 return false; 781 } 782 783 if (is_suspended) { 784 *bits |= 0x00100000; 785 return true; 786 } 787 } // end retry loop 788 789 // thread did not suspend after all our retries 790 *bits |= 0x00200000; 791 return false; 792 } 793 794 // Called from API entry points which perform stack walking. If the 795 // associated JavaThread is the current thread, then wait_for_suspend 796 // is not used. Otherwise, it determines if we should wait for the 797 // "other" thread to complete external suspension. (NOTE: in future 798 // releases the suspension mechanism should be reimplemented so this 799 // is not necessary.) 800 // 801 bool 802 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 803 if (this != JavaThread::current()) { 804 // "other" threads require special handling. 805 if (wait_for_suspend) { 806 // We are allowed to wait for the external suspend to complete 807 // so give the other thread a chance to get suspended. 808 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 809 SuspendRetryDelay, bits)) { 810 // Didn't make it so let the caller know. 811 return false; 812 } 813 } 814 // We aren't allowed to wait for the external suspend to complete 815 // so if the other thread isn't externally suspended we need to 816 // let the caller know. 817 else if (!is_ext_suspend_completed_with_lock(bits)) { 818 return false; 819 } 820 } 821 822 return true; 823 } 824 825 #ifndef PRODUCT 826 void JavaThread::record_jump(address target, address instr, const char* file, 827 int line) { 828 829 // This should not need to be atomic as the only way for simultaneous 830 // updates is via interrupts. Even then this should be rare or non-existent 831 // and we don't care that much anyway. 832 833 int index = _jmp_ring_index; 834 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 835 _jmp_ring[index]._target = (intptr_t) target; 836 _jmp_ring[index]._instruction = (intptr_t) instr; 837 _jmp_ring[index]._file = file; 838 _jmp_ring[index]._line = line; 839 } 840 #endif // PRODUCT 841 842 void Thread::interrupt(Thread* thread) { 843 debug_only(check_for_dangling_thread_pointer(thread);) 844 os::interrupt(thread); 845 } 846 847 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 848 debug_only(check_for_dangling_thread_pointer(thread);) 849 // Note: If clear_interrupted==false, this simply fetches and 850 // returns the value of the field osthread()->interrupted(). 851 return os::is_interrupted(thread, clear_interrupted); 852 } 853 854 855 // GC Support 856 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 857 int thread_parity = _oops_do_parity; 858 if (thread_parity != strong_roots_parity) { 859 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 860 if (res == thread_parity) { 861 return true; 862 } else { 863 guarantee(res == strong_roots_parity, "Or else what?"); 864 return false; 865 } 866 } 867 return false; 868 } 869 870 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 871 active_handles()->oops_do(f); 872 // Do oop for ThreadShadow 873 f->do_oop((oop*)&_pending_exception); 874 handle_area()->oops_do(f); 875 876 // We scan thread local monitor lists here, and the remaining global 877 // monitors in ObjectSynchronizer::oops_do(). 878 ObjectSynchronizer::thread_local_used_oops_do(this, f); 879 } 880 881 void Thread::metadata_handles_do(void f(Metadata*)) { 882 // Only walk the Handles in Thread. 883 if (metadata_handles() != NULL) { 884 for (int i = 0; i< metadata_handles()->length(); i++) { 885 f(metadata_handles()->at(i)); 886 } 887 } 888 } 889 890 void Thread::print_on(outputStream* st, bool print_extended_info) const { 891 // get_priority assumes osthread initialized 892 if (osthread() != NULL) { 893 int os_prio; 894 if (os::get_native_priority(this, &os_prio) == OS_OK) { 895 st->print("os_prio=%d ", os_prio); 896 } 897 898 st->print("cpu=%.2fms ", 899 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 900 ); 901 st->print("elapsed=%.2fs ", 902 _statistical_info.getElapsedTime() / 1000.0 903 ); 904 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 905 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 906 st->print("allocated=" SIZE_FORMAT "%s ", 907 byte_size_in_proper_unit(allocated_bytes), 908 proper_unit_for_byte_size(allocated_bytes) 909 ); 910 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 911 } 912 913 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 914 osthread()->print_on(st); 915 } 916 ThreadsSMRSupport::print_info_on(this, st); 917 st->print(" "); 918 debug_only(if (WizardMode) print_owned_locks_on(st);) 919 } 920 921 // Thread::print_on_error() is called by fatal error handler. Don't use 922 // any lock or allocate memory. 923 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 924 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 925 926 if (is_VM_thread()) { st->print("VMThread"); } 927 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 928 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 929 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 930 else { st->print("Thread"); } 931 932 if (is_Named_thread()) { 933 st->print(" \"%s\"", name()); 934 } 935 936 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 937 p2i(stack_end()), p2i(stack_base())); 938 939 if (osthread()) { 940 st->print(" [id=%d]", osthread()->thread_id()); 941 } 942 943 ThreadsSMRSupport::print_info_on(this, st); 944 } 945 946 void Thread::print_value_on(outputStream* st) const { 947 if (is_Named_thread()) { 948 st->print(" \"%s\" ", name()); 949 } 950 st->print(INTPTR_FORMAT, p2i(this)); // print address 951 } 952 953 #ifdef ASSERT 954 void Thread::print_owned_locks_on(outputStream* st) const { 955 Monitor *cur = _owned_locks; 956 if (cur == NULL) { 957 st->print(" (no locks) "); 958 } else { 959 st->print_cr(" Locks owned:"); 960 while (cur) { 961 cur->print_on(st); 962 cur = cur->next(); 963 } 964 } 965 } 966 967 static int ref_use_count = 0; 968 969 bool Thread::owns_locks_but_compiled_lock() const { 970 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 971 if (cur != Compile_lock) return true; 972 } 973 return false; 974 } 975 976 977 #endif 978 979 #ifndef PRODUCT 980 981 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 982 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 983 // no locks which allow_vm_block's are held 984 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 985 // Check if current thread is allowed to block at a safepoint 986 if (!(_allow_safepoint_count == 0)) { 987 fatal("Possible safepoint reached by thread that does not allow it"); 988 } 989 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 990 fatal("LEAF method calling lock?"); 991 } 992 993 #ifdef ASSERT 994 if (potential_vm_operation && is_Java_thread() 995 && !Universe::is_bootstrapping()) { 996 // Make sure we do not hold any locks that the VM thread also uses. 997 // This could potentially lead to deadlocks 998 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 999 // Threads_lock is special, since the safepoint synchronization will not start before this is 1000 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1001 // since it is used to transfer control between JavaThreads and the VMThread 1002 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1003 if ((cur->allow_vm_block() && 1004 cur != Threads_lock && 1005 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1006 cur != VMOperationRequest_lock && 1007 cur != VMOperationQueue_lock) || 1008 cur->rank() == Mutex::special) { 1009 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1010 } 1011 } 1012 } 1013 1014 if (GCALotAtAllSafepoints) { 1015 // We could enter a safepoint here and thus have a gc 1016 InterfaceSupport::check_gc_alot(); 1017 } 1018 #endif 1019 } 1020 #endif 1021 1022 bool Thread::is_in_stack(address adr) const { 1023 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1024 address end = os::current_stack_pointer(); 1025 // Allow non Java threads to call this without stack_base 1026 if (_stack_base == NULL) return true; 1027 if (stack_base() >= adr && adr >= end) return true; 1028 1029 return false; 1030 } 1031 1032 bool Thread::is_in_usable_stack(address adr) const { 1033 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1034 size_t usable_stack_size = _stack_size - stack_guard_size; 1035 1036 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1037 } 1038 1039 1040 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1041 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1042 // used for compilation in the future. If that change is made, the need for these methods 1043 // should be revisited, and they should be removed if possible. 1044 1045 bool Thread::is_lock_owned(address adr) const { 1046 return on_local_stack(adr); 1047 } 1048 1049 bool Thread::set_as_starting_thread() { 1050 // NOTE: this must be called inside the main thread. 1051 return os::create_main_thread((JavaThread*)this); 1052 } 1053 1054 static void initialize_class(Symbol* class_name, TRAPS) { 1055 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1056 InstanceKlass::cast(klass)->initialize(CHECK); 1057 } 1058 1059 1060 // Creates the initial ThreadGroup 1061 static Handle create_initial_thread_group(TRAPS) { 1062 Handle system_instance = JavaCalls::construct_new_instance( 1063 SystemDictionary::ThreadGroup_klass(), 1064 vmSymbols::void_method_signature(), 1065 CHECK_NH); 1066 Universe::set_system_thread_group(system_instance()); 1067 1068 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1069 Handle main_instance = JavaCalls::construct_new_instance( 1070 SystemDictionary::ThreadGroup_klass(), 1071 vmSymbols::threadgroup_string_void_signature(), 1072 system_instance, 1073 string, 1074 CHECK_NH); 1075 return main_instance; 1076 } 1077 1078 // Creates the initial Thread 1079 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1080 TRAPS) { 1081 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1082 assert(ik->is_initialized(), "must be"); 1083 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1084 1085 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1086 // constructor calls Thread.current(), which must be set here for the 1087 // initial thread. 1088 java_lang_Thread::set_thread(thread_oop(), thread); 1089 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1090 thread->set_threadObj(thread_oop()); 1091 1092 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1093 1094 JavaValue result(T_VOID); 1095 JavaCalls::call_special(&result, thread_oop, 1096 ik, 1097 vmSymbols::object_initializer_name(), 1098 vmSymbols::threadgroup_string_void_signature(), 1099 thread_group, 1100 string, 1101 CHECK_NULL); 1102 return thread_oop(); 1103 } 1104 1105 char java_runtime_name[128] = ""; 1106 char java_runtime_version[128] = ""; 1107 1108 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1109 static const char* get_java_runtime_name(TRAPS) { 1110 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1111 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1112 fieldDescriptor fd; 1113 bool found = k != NULL && 1114 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1115 vmSymbols::string_signature(), &fd); 1116 if (found) { 1117 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1118 if (name_oop == NULL) { 1119 return NULL; 1120 } 1121 const char* name = java_lang_String::as_utf8_string(name_oop, 1122 java_runtime_name, 1123 sizeof(java_runtime_name)); 1124 return name; 1125 } else { 1126 return NULL; 1127 } 1128 } 1129 1130 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1131 static const char* get_java_runtime_version(TRAPS) { 1132 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1133 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1134 fieldDescriptor fd; 1135 bool found = k != NULL && 1136 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1137 vmSymbols::string_signature(), &fd); 1138 if (found) { 1139 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1140 if (name_oop == NULL) { 1141 return NULL; 1142 } 1143 const char* name = java_lang_String::as_utf8_string(name_oop, 1144 java_runtime_version, 1145 sizeof(java_runtime_version)); 1146 return name; 1147 } else { 1148 return NULL; 1149 } 1150 } 1151 1152 // General purpose hook into Java code, run once when the VM is initialized. 1153 // The Java library method itself may be changed independently from the VM. 1154 static void call_postVMInitHook(TRAPS) { 1155 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1156 if (klass != NULL) { 1157 JavaValue result(T_VOID); 1158 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1159 vmSymbols::void_method_signature(), 1160 CHECK); 1161 } 1162 } 1163 1164 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1165 bool daemon, TRAPS) { 1166 assert(thread_group.not_null(), "thread group should be specified"); 1167 assert(threadObj() == NULL, "should only create Java thread object once"); 1168 1169 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1170 assert(ik->is_initialized(), "must be"); 1171 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1172 1173 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1174 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1175 // constructor calls Thread.current(), which must be set here. 1176 java_lang_Thread::set_thread(thread_oop(), this); 1177 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1178 set_threadObj(thread_oop()); 1179 1180 JavaValue result(T_VOID); 1181 if (thread_name != NULL) { 1182 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1183 // Thread gets assigned specified name and null target 1184 JavaCalls::call_special(&result, 1185 thread_oop, 1186 ik, 1187 vmSymbols::object_initializer_name(), 1188 vmSymbols::threadgroup_string_void_signature(), 1189 thread_group, 1190 name, 1191 THREAD); 1192 } else { 1193 // Thread gets assigned name "Thread-nnn" and null target 1194 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1195 JavaCalls::call_special(&result, 1196 thread_oop, 1197 ik, 1198 vmSymbols::object_initializer_name(), 1199 vmSymbols::threadgroup_runnable_void_signature(), 1200 thread_group, 1201 Handle(), 1202 THREAD); 1203 } 1204 1205 1206 if (daemon) { 1207 java_lang_Thread::set_daemon(thread_oop()); 1208 } 1209 1210 if (HAS_PENDING_EXCEPTION) { 1211 return; 1212 } 1213 1214 Klass* group = SystemDictionary::ThreadGroup_klass(); 1215 Handle threadObj(THREAD, this->threadObj()); 1216 1217 JavaCalls::call_special(&result, 1218 thread_group, 1219 group, 1220 vmSymbols::add_method_name(), 1221 vmSymbols::thread_void_signature(), 1222 threadObj, // Arg 1 1223 THREAD); 1224 } 1225 1226 // List of all NonJavaThreads and safe iteration over that list. 1227 1228 class NonJavaThread::List { 1229 public: 1230 NonJavaThread* volatile _head; 1231 SingleWriterSynchronizer _protect; 1232 1233 List() : _head(NULL), _protect() {} 1234 }; 1235 1236 NonJavaThread::List NonJavaThread::_the_list; 1237 1238 NonJavaThread::Iterator::Iterator() : 1239 _protect_enter(_the_list._protect.enter()), 1240 _current(OrderAccess::load_acquire(&_the_list._head)) 1241 {} 1242 1243 NonJavaThread::Iterator::~Iterator() { 1244 _the_list._protect.exit(_protect_enter); 1245 } 1246 1247 void NonJavaThread::Iterator::step() { 1248 assert(!end(), "precondition"); 1249 _current = OrderAccess::load_acquire(&_current->_next); 1250 } 1251 1252 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1253 // Add this thread to _the_list. 1254 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1255 _next = _the_list._head; 1256 OrderAccess::release_store(&_the_list._head, this); 1257 } 1258 1259 NonJavaThread::~NonJavaThread() { 1260 JFR_ONLY(Jfr::on_thread_exit(this);) 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 1786 // We call another function to do the rest so we are sure that the stack addresses used 1787 // from there will be lower than the stack base just computed 1788 thread_main_inner(); 1789 1790 // Note, thread is no longer valid at this point! 1791 } 1792 1793 1794 void JavaThread::thread_main_inner() { 1795 assert(JavaThread::current() == this, "sanity check"); 1796 assert(this->threadObj() != NULL, "just checking"); 1797 1798 // Execute thread entry point unless this thread has a pending exception 1799 // or has been stopped before starting. 1800 // Note: Due to JVM_StopThread we can have pending exceptions already! 1801 if (!this->has_pending_exception() && 1802 !java_lang_Thread::is_stillborn(this->threadObj())) { 1803 { 1804 ResourceMark rm(this); 1805 this->set_native_thread_name(this->get_thread_name()); 1806 } 1807 HandleMark hm(this); 1808 this->entry_point()(this, this); 1809 } 1810 1811 DTRACE_THREAD_PROBE(stop, this); 1812 1813 this->exit(false); 1814 this->smr_delete(); 1815 } 1816 1817 1818 static void ensure_join(JavaThread* thread) { 1819 // We do not need to grab the Threads_lock, since we are operating on ourself. 1820 Handle threadObj(thread, thread->threadObj()); 1821 assert(threadObj.not_null(), "java thread object must exist"); 1822 ObjectLocker lock(threadObj, thread); 1823 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1824 thread->clear_pending_exception(); 1825 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1826 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1827 // Clear the native thread instance - this makes isAlive return false and allows the join() 1828 // to complete once we've done the notify_all below 1829 java_lang_Thread::set_thread(threadObj(), NULL); 1830 lock.notify_all(thread); 1831 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1832 thread->clear_pending_exception(); 1833 } 1834 1835 static bool is_daemon(oop threadObj) { 1836 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1837 } 1838 1839 // For any new cleanup additions, please check to see if they need to be applied to 1840 // cleanup_failed_attach_current_thread as well. 1841 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1842 assert(this == JavaThread::current(), "thread consistency check"); 1843 1844 elapsedTimer _timer_exit_phase1; 1845 elapsedTimer _timer_exit_phase2; 1846 elapsedTimer _timer_exit_phase3; 1847 elapsedTimer _timer_exit_phase4; 1848 1849 if (log_is_enabled(Debug, os, thread, timer)) { 1850 _timer_exit_phase1.start(); 1851 } 1852 1853 HandleMark hm(this); 1854 Handle uncaught_exception(this, this->pending_exception()); 1855 this->clear_pending_exception(); 1856 Handle threadObj(this, this->threadObj()); 1857 assert(threadObj.not_null(), "Java thread object should be created"); 1858 1859 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1860 { 1861 EXCEPTION_MARK; 1862 1863 CLEAR_PENDING_EXCEPTION; 1864 } 1865 if (!destroy_vm) { 1866 if (uncaught_exception.not_null()) { 1867 EXCEPTION_MARK; 1868 // Call method Thread.dispatchUncaughtException(). 1869 Klass* thread_klass = SystemDictionary::Thread_klass(); 1870 JavaValue result(T_VOID); 1871 JavaCalls::call_virtual(&result, 1872 threadObj, thread_klass, 1873 vmSymbols::dispatchUncaughtException_name(), 1874 vmSymbols::throwable_void_signature(), 1875 uncaught_exception, 1876 THREAD); 1877 if (HAS_PENDING_EXCEPTION) { 1878 ResourceMark rm(this); 1879 jio_fprintf(defaultStream::error_stream(), 1880 "\nException: %s thrown from the UncaughtExceptionHandler" 1881 " in thread \"%s\"\n", 1882 pending_exception()->klass()->external_name(), 1883 get_thread_name()); 1884 CLEAR_PENDING_EXCEPTION; 1885 } 1886 } 1887 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 1888 1889 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1890 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1891 // is deprecated anyhow. 1892 if (!is_Compiler_thread()) { 1893 int count = 3; 1894 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1895 EXCEPTION_MARK; 1896 JavaValue result(T_VOID); 1897 Klass* thread_klass = SystemDictionary::Thread_klass(); 1898 JavaCalls::call_virtual(&result, 1899 threadObj, thread_klass, 1900 vmSymbols::exit_method_name(), 1901 vmSymbols::void_method_signature(), 1902 THREAD); 1903 CLEAR_PENDING_EXCEPTION; 1904 } 1905 } 1906 // notify JVMTI 1907 if (JvmtiExport::should_post_thread_life()) { 1908 JvmtiExport::post_thread_end(this); 1909 } 1910 1911 // We have notified the agents that we are exiting, before we go on, 1912 // we must check for a pending external suspend request and honor it 1913 // in order to not surprise the thread that made the suspend request. 1914 while (true) { 1915 { 1916 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1917 if (!is_external_suspend()) { 1918 set_terminated(_thread_exiting); 1919 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 1920 break; 1921 } 1922 // Implied else: 1923 // Things get a little tricky here. We have a pending external 1924 // suspend request, but we are holding the SR_lock so we 1925 // can't just self-suspend. So we temporarily drop the lock 1926 // and then self-suspend. 1927 } 1928 1929 ThreadBlockInVM tbivm(this); 1930 java_suspend_self(); 1931 1932 // We're done with this suspend request, but we have to loop around 1933 // and check again. Eventually we will get SR_lock without a pending 1934 // external suspend request and will be able to mark ourselves as 1935 // exiting. 1936 } 1937 // no more external suspends are allowed at this point 1938 } else { 1939 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 1940 // before_exit() has already posted JVMTI THREAD_END events 1941 } 1942 1943 if (log_is_enabled(Debug, os, thread, timer)) { 1944 _timer_exit_phase1.stop(); 1945 _timer_exit_phase2.start(); 1946 } 1947 // Notify waiters on thread object. This has to be done after exit() is called 1948 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1949 // group should have the destroyed bit set before waiters are notified). 1950 ensure_join(this); 1951 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1952 1953 if (log_is_enabled(Debug, os, thread, timer)) { 1954 _timer_exit_phase2.stop(); 1955 _timer_exit_phase3.start(); 1956 } 1957 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1958 // held by this thread must be released. The spec does not distinguish 1959 // between JNI-acquired and regular Java monitors. We can only see 1960 // regular Java monitors here if monitor enter-exit matching is broken. 1961 // 1962 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1963 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1964 if (exit_type == jni_detach) { 1965 // Sanity check even though JNI DetachCurrentThread() would have 1966 // returned JNI_ERR if there was a Java frame. JavaThread exit 1967 // should be done executing Java code by the time we get here. 1968 assert(!this->has_last_Java_frame(), 1969 "should not have a Java frame when detaching or exiting"); 1970 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1971 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1972 } 1973 1974 // These things needs to be done while we are still a Java Thread. Make sure that thread 1975 // is in a consistent state, in case GC happens 1976 JFR_ONLY(Jfr::on_thread_exit(this);) 1977 1978 if (active_handles() != NULL) { 1979 JNIHandleBlock* block = active_handles(); 1980 set_active_handles(NULL); 1981 JNIHandleBlock::release_block(block); 1982 } 1983 1984 if (free_handle_block() != NULL) { 1985 JNIHandleBlock* block = free_handle_block(); 1986 set_free_handle_block(NULL); 1987 JNIHandleBlock::release_block(block); 1988 } 1989 1990 // These have to be removed while this is still a valid thread. 1991 remove_stack_guard_pages(); 1992 1993 if (UseTLAB) { 1994 tlab().retire(); 1995 } 1996 1997 if (JvmtiEnv::environments_might_exist()) { 1998 JvmtiExport::cleanup_thread(this); 1999 } 2000 2001 // We must flush any deferred card marks and other various GC barrier 2002 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2003 // before removing a thread from the list of active threads. 2004 BarrierSet::barrier_set()->on_thread_detach(this); 2005 2006 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2007 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2008 os::current_thread_id()); 2009 2010 if (log_is_enabled(Debug, os, thread, timer)) { 2011 _timer_exit_phase3.stop(); 2012 _timer_exit_phase4.start(); 2013 } 2014 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2015 Threads::remove(this); 2016 2017 if (log_is_enabled(Debug, os, thread, timer)) { 2018 _timer_exit_phase4.stop(); 2019 ResourceMark rm(this); 2020 log_debug(os, thread, timer)("name='%s'" 2021 ", exit-phase1=" JLONG_FORMAT 2022 ", exit-phase2=" JLONG_FORMAT 2023 ", exit-phase3=" JLONG_FORMAT 2024 ", exit-phase4=" JLONG_FORMAT, 2025 get_thread_name(), 2026 _timer_exit_phase1.milliseconds(), 2027 _timer_exit_phase2.milliseconds(), 2028 _timer_exit_phase3.milliseconds(), 2029 _timer_exit_phase4.milliseconds()); 2030 } 2031 } 2032 2033 void JavaThread::cleanup_failed_attach_current_thread() { 2034 if (active_handles() != NULL) { 2035 JNIHandleBlock* block = active_handles(); 2036 set_active_handles(NULL); 2037 JNIHandleBlock::release_block(block); 2038 } 2039 2040 if (free_handle_block() != NULL) { 2041 JNIHandleBlock* block = free_handle_block(); 2042 set_free_handle_block(NULL); 2043 JNIHandleBlock::release_block(block); 2044 } 2045 2046 // These have to be removed while this is still a valid thread. 2047 remove_stack_guard_pages(); 2048 2049 if (UseTLAB) { 2050 tlab().retire(); 2051 } 2052 2053 BarrierSet::barrier_set()->on_thread_detach(this); 2054 2055 Threads::remove(this); 2056 this->smr_delete(); 2057 } 2058 2059 JavaThread* JavaThread::active() { 2060 Thread* thread = Thread::current(); 2061 if (thread->is_Java_thread()) { 2062 return (JavaThread*) thread; 2063 } else { 2064 assert(thread->is_VM_thread(), "this must be a vm thread"); 2065 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2066 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2067 assert(ret->is_Java_thread(), "must be a Java thread"); 2068 return ret; 2069 } 2070 } 2071 2072 bool JavaThread::is_lock_owned(address adr) const { 2073 if (Thread::is_lock_owned(adr)) return true; 2074 2075 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2076 if (chunk->contains(adr)) return true; 2077 } 2078 2079 return false; 2080 } 2081 2082 2083 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2084 chunk->set_next(monitor_chunks()); 2085 set_monitor_chunks(chunk); 2086 } 2087 2088 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2089 guarantee(monitor_chunks() != NULL, "must be non empty"); 2090 if (monitor_chunks() == chunk) { 2091 set_monitor_chunks(chunk->next()); 2092 } else { 2093 MonitorChunk* prev = monitor_chunks(); 2094 while (prev->next() != chunk) prev = prev->next(); 2095 prev->set_next(chunk->next()); 2096 } 2097 } 2098 2099 // JVM support. 2100 2101 // Note: this function shouldn't block if it's called in 2102 // _thread_in_native_trans state (such as from 2103 // check_special_condition_for_native_trans()). 2104 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2105 2106 if (has_last_Java_frame() && has_async_condition()) { 2107 // If we are at a polling page safepoint (not a poll return) 2108 // then we must defer async exception because live registers 2109 // will be clobbered by the exception path. Poll return is 2110 // ok because the call we a returning from already collides 2111 // with exception handling registers and so there is no issue. 2112 // (The exception handling path kills call result registers but 2113 // this is ok since the exception kills the result anyway). 2114 2115 if (is_at_poll_safepoint()) { 2116 // if the code we are returning to has deoptimized we must defer 2117 // the exception otherwise live registers get clobbered on the 2118 // exception path before deoptimization is able to retrieve them. 2119 // 2120 RegisterMap map(this, false); 2121 frame caller_fr = last_frame().sender(&map); 2122 assert(caller_fr.is_compiled_frame(), "what?"); 2123 if (caller_fr.is_deoptimized_frame()) { 2124 log_info(exceptions)("deferred async exception at compiled safepoint"); 2125 return; 2126 } 2127 } 2128 } 2129 2130 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2131 if (condition == _no_async_condition) { 2132 // Conditions have changed since has_special_runtime_exit_condition() 2133 // was called: 2134 // - if we were here only because of an external suspend request, 2135 // then that was taken care of above (or cancelled) so we are done 2136 // - if we were here because of another async request, then it has 2137 // been cleared between the has_special_runtime_exit_condition() 2138 // and now so again we are done 2139 return; 2140 } 2141 2142 // Check for pending async. exception 2143 if (_pending_async_exception != NULL) { 2144 // Only overwrite an already pending exception, if it is not a threadDeath. 2145 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2146 2147 // We cannot call Exceptions::_throw(...) here because we cannot block 2148 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2149 2150 LogTarget(Info, exceptions) lt; 2151 if (lt.is_enabled()) { 2152 ResourceMark rm; 2153 LogStream ls(lt); 2154 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2155 if (has_last_Java_frame()) { 2156 frame f = last_frame(); 2157 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2158 } 2159 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2160 } 2161 _pending_async_exception = NULL; 2162 clear_has_async_exception(); 2163 } 2164 } 2165 2166 if (check_unsafe_error && 2167 condition == _async_unsafe_access_error && !has_pending_exception()) { 2168 condition = _no_async_condition; // done 2169 switch (thread_state()) { 2170 case _thread_in_vm: { 2171 JavaThread* THREAD = this; 2172 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2173 } 2174 case _thread_in_native: { 2175 ThreadInVMfromNative tiv(this); 2176 JavaThread* THREAD = this; 2177 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2178 } 2179 case _thread_in_Java: { 2180 ThreadInVMfromJava tiv(this); 2181 JavaThread* THREAD = this; 2182 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2183 } 2184 default: 2185 ShouldNotReachHere(); 2186 } 2187 } 2188 2189 assert(condition == _no_async_condition || has_pending_exception() || 2190 (!check_unsafe_error && condition == _async_unsafe_access_error), 2191 "must have handled the async condition, if no exception"); 2192 } 2193 2194 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2195 // 2196 // Check for pending external suspend. Internal suspend requests do 2197 // not use handle_special_runtime_exit_condition(). 2198 // If JNIEnv proxies are allowed, don't self-suspend if the target 2199 // thread is not the current thread. In older versions of jdbx, jdbx 2200 // threads could call into the VM with another thread's JNIEnv so we 2201 // can be here operating on behalf of a suspended thread (4432884). 2202 bool do_self_suspend = is_external_suspend_with_lock(); 2203 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2204 // 2205 // Because thread is external suspended the safepoint code will count 2206 // thread as at a safepoint. This can be odd because we can be here 2207 // as _thread_in_Java which would normally transition to _thread_blocked 2208 // at a safepoint. We would like to mark the thread as _thread_blocked 2209 // before calling java_suspend_self like all other callers of it but 2210 // we must then observe proper safepoint protocol. (We can't leave 2211 // _thread_blocked with a safepoint in progress). However we can be 2212 // here as _thread_in_native_trans so we can't use a normal transition 2213 // constructor/destructor pair because they assert on that type of 2214 // transition. We could do something like: 2215 // 2216 // JavaThreadState state = thread_state(); 2217 // set_thread_state(_thread_in_vm); 2218 // { 2219 // ThreadBlockInVM tbivm(this); 2220 // java_suspend_self() 2221 // } 2222 // set_thread_state(_thread_in_vm_trans); 2223 // if (safepoint) block; 2224 // set_thread_state(state); 2225 // 2226 // but that is pretty messy. Instead we just go with the way the 2227 // code has worked before and note that this is the only path to 2228 // java_suspend_self that doesn't put the thread in _thread_blocked 2229 // mode. 2230 2231 frame_anchor()->make_walkable(this); 2232 java_suspend_self(); 2233 2234 // We might be here for reasons in addition to the self-suspend request 2235 // so check for other async requests. 2236 } 2237 2238 if (check_asyncs) { 2239 check_and_handle_async_exceptions(); 2240 } 2241 2242 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2243 } 2244 2245 void JavaThread::send_thread_stop(oop java_throwable) { 2246 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2247 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2248 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2249 2250 // Do not throw asynchronous exceptions against the compiler thread 2251 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2252 if (!can_call_java()) return; 2253 2254 { 2255 // Actually throw the Throwable against the target Thread - however 2256 // only if there is no thread death exception installed already. 2257 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2258 // If the topmost frame is a runtime stub, then we are calling into 2259 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2260 // must deoptimize the caller before continuing, as the compiled exception handler table 2261 // may not be valid 2262 if (has_last_Java_frame()) { 2263 frame f = last_frame(); 2264 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2265 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2266 RegisterMap reg_map(this, UseBiasedLocking); 2267 frame compiled_frame = f.sender(®_map); 2268 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2269 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2270 } 2271 } 2272 } 2273 2274 // Set async. pending exception in thread. 2275 set_pending_async_exception(java_throwable); 2276 2277 if (log_is_enabled(Info, exceptions)) { 2278 ResourceMark rm; 2279 log_info(exceptions)("Pending Async. exception installed of type: %s", 2280 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2281 } 2282 // for AbortVMOnException flag 2283 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2284 } 2285 } 2286 2287 2288 // Interrupt thread so it will wake up from a potential wait() 2289 Thread::interrupt(this); 2290 } 2291 2292 // External suspension mechanism. 2293 // 2294 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2295 // to any VM_locks and it is at a transition 2296 // Self-suspension will happen on the transition out of the vm. 2297 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2298 // 2299 // Guarantees on return: 2300 // + Target thread will not execute any new bytecode (that's why we need to 2301 // force a safepoint) 2302 // + Target thread will not enter any new monitors 2303 // 2304 void JavaThread::java_suspend() { 2305 ThreadsListHandle tlh; 2306 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2307 return; 2308 } 2309 2310 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2311 if (!is_external_suspend()) { 2312 // a racing resume has cancelled us; bail out now 2313 return; 2314 } 2315 2316 // suspend is done 2317 uint32_t debug_bits = 0; 2318 // Warning: is_ext_suspend_completed() may temporarily drop the 2319 // SR_lock to allow the thread to reach a stable thread state if 2320 // it is currently in a transient thread state. 2321 if (is_ext_suspend_completed(false /* !called_by_wait */, 2322 SuspendRetryDelay, &debug_bits)) { 2323 return; 2324 } 2325 } 2326 2327 VM_ThreadSuspend vm_suspend; 2328 VMThread::execute(&vm_suspend); 2329 } 2330 2331 // Part II of external suspension. 2332 // A JavaThread self suspends when it detects a pending external suspend 2333 // request. This is usually on transitions. It is also done in places 2334 // where continuing to the next transition would surprise the caller, 2335 // e.g., monitor entry. 2336 // 2337 // Returns the number of times that the thread self-suspended. 2338 // 2339 // Note: DO NOT call java_suspend_self() when you just want to block current 2340 // thread. java_suspend_self() is the second stage of cooperative 2341 // suspension for external suspend requests and should only be used 2342 // to complete an external suspend request. 2343 // 2344 int JavaThread::java_suspend_self() { 2345 int ret = 0; 2346 2347 // we are in the process of exiting so don't suspend 2348 if (is_exiting()) { 2349 clear_external_suspend(); 2350 return ret; 2351 } 2352 2353 assert(_anchor.walkable() || 2354 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2355 "must have walkable stack"); 2356 2357 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2358 2359 assert(!this->is_ext_suspended(), 2360 "a thread trying to self-suspend should not already be suspended"); 2361 2362 if (this->is_suspend_equivalent()) { 2363 // If we are self-suspending as a result of the lifting of a 2364 // suspend equivalent condition, then the suspend_equivalent 2365 // flag is not cleared until we set the ext_suspended flag so 2366 // that wait_for_ext_suspend_completion() returns consistent 2367 // results. 2368 this->clear_suspend_equivalent(); 2369 } 2370 2371 // A racing resume may have cancelled us before we grabbed SR_lock 2372 // above. Or another external suspend request could be waiting for us 2373 // by the time we return from SR_lock()->wait(). The thread 2374 // that requested the suspension may already be trying to walk our 2375 // stack and if we return now, we can change the stack out from under 2376 // it. This would be a "bad thing (TM)" and cause the stack walker 2377 // to crash. We stay self-suspended until there are no more pending 2378 // external suspend requests. 2379 while (is_external_suspend()) { 2380 ret++; 2381 this->set_ext_suspended(); 2382 2383 // _ext_suspended flag is cleared by java_resume() 2384 while (is_ext_suspended()) { 2385 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2386 } 2387 } 2388 2389 return ret; 2390 } 2391 2392 #ifdef ASSERT 2393 // Verify the JavaThread has not yet been published in the Threads::list, and 2394 // hence doesn't need protection from concurrent access at this stage. 2395 void JavaThread::verify_not_published() { 2396 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2397 // since an unpublished JavaThread doesn't participate in the 2398 // Thread-SMR protocol for keeping a ThreadsList alive. 2399 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2400 } 2401 #endif 2402 2403 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2404 // progress or when _suspend_flags is non-zero. 2405 // Current thread needs to self-suspend if there is a suspend request and/or 2406 // block if a safepoint is in progress. 2407 // Async exception ISN'T checked. 2408 // Note only the ThreadInVMfromNative transition can call this function 2409 // directly and when thread state is _thread_in_native_trans 2410 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2411 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2412 2413 JavaThread *curJT = JavaThread::current(); 2414 bool do_self_suspend = thread->is_external_suspend(); 2415 2416 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2417 2418 // If JNIEnv proxies are allowed, don't self-suspend if the target 2419 // thread is not the current thread. In older versions of jdbx, jdbx 2420 // threads could call into the VM with another thread's JNIEnv so we 2421 // can be here operating on behalf of a suspended thread (4432884). 2422 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2423 JavaThreadState state = thread->thread_state(); 2424 2425 // We mark this thread_blocked state as a suspend-equivalent so 2426 // that a caller to is_ext_suspend_completed() won't be confused. 2427 // The suspend-equivalent state is cleared by java_suspend_self(). 2428 thread->set_suspend_equivalent(); 2429 2430 // If the safepoint code sees the _thread_in_native_trans state, it will 2431 // wait until the thread changes to other thread state. There is no 2432 // guarantee on how soon we can obtain the SR_lock and complete the 2433 // self-suspend request. It would be a bad idea to let safepoint wait for 2434 // too long. Temporarily change the state to _thread_blocked to 2435 // let the VM thread know that this thread is ready for GC. The problem 2436 // of changing thread state is that safepoint could happen just after 2437 // java_suspend_self() returns after being resumed, and VM thread will 2438 // see the _thread_blocked state. We must check for safepoint 2439 // after restoring the state and make sure we won't leave while a safepoint 2440 // is in progress. 2441 thread->set_thread_state(_thread_blocked); 2442 thread->java_suspend_self(); 2443 thread->set_thread_state(state); 2444 2445 InterfaceSupport::serialize_thread_state_with_handler(thread); 2446 } 2447 2448 SafepointMechanism::block_if_requested(curJT); 2449 2450 if (thread->is_deopt_suspend()) { 2451 thread->clear_deopt_suspend(); 2452 RegisterMap map(thread, false); 2453 frame f = thread->last_frame(); 2454 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2455 f = f.sender(&map); 2456 } 2457 if (f.id() == thread->must_deopt_id()) { 2458 thread->clear_must_deopt_id(); 2459 f.deoptimize(thread); 2460 } else { 2461 fatal("missed deoptimization!"); 2462 } 2463 } 2464 2465 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2466 } 2467 2468 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2469 // progress or when _suspend_flags is non-zero. 2470 // Current thread needs to self-suspend if there is a suspend request and/or 2471 // block if a safepoint is in progress. 2472 // Also check for pending async exception (not including unsafe access error). 2473 // Note only the native==>VM/Java barriers can call this function and when 2474 // thread state is _thread_in_native_trans. 2475 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2476 check_safepoint_and_suspend_for_native_trans(thread); 2477 2478 if (thread->has_async_exception()) { 2479 // We are in _thread_in_native_trans state, don't handle unsafe 2480 // access error since that may block. 2481 thread->check_and_handle_async_exceptions(false); 2482 } 2483 } 2484 2485 // This is a variant of the normal 2486 // check_special_condition_for_native_trans with slightly different 2487 // semantics for use by critical native wrappers. It does all the 2488 // normal checks but also performs the transition back into 2489 // thread_in_Java state. This is required so that critical natives 2490 // can potentially block and perform a GC if they are the last thread 2491 // exiting the GCLocker. 2492 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2493 check_special_condition_for_native_trans(thread); 2494 2495 // Finish the transition 2496 thread->set_thread_state(_thread_in_Java); 2497 2498 if (thread->do_critical_native_unlock()) { 2499 ThreadInVMfromJavaNoAsyncException tiv(thread); 2500 GCLocker::unlock_critical(thread); 2501 thread->clear_critical_native_unlock(); 2502 } 2503 } 2504 2505 // We need to guarantee the Threads_lock here, since resumes are not 2506 // allowed during safepoint synchronization 2507 // Can only resume from an external suspension 2508 void JavaThread::java_resume() { 2509 assert_locked_or_safepoint(Threads_lock); 2510 2511 // Sanity check: thread is gone, has started exiting or the thread 2512 // was not externally suspended. 2513 ThreadsListHandle tlh; 2514 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2515 return; 2516 } 2517 2518 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2519 2520 clear_external_suspend(); 2521 2522 if (is_ext_suspended()) { 2523 clear_ext_suspended(); 2524 SR_lock()->notify_all(); 2525 } 2526 } 2527 2528 size_t JavaThread::_stack_red_zone_size = 0; 2529 size_t JavaThread::_stack_yellow_zone_size = 0; 2530 size_t JavaThread::_stack_reserved_zone_size = 0; 2531 size_t JavaThread::_stack_shadow_zone_size = 0; 2532 2533 void JavaThread::create_stack_guard_pages() { 2534 if (!os::uses_stack_guard_pages() || 2535 _stack_guard_state != stack_guard_unused || 2536 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2537 log_info(os, thread)("Stack guard page creation for thread " 2538 UINTX_FORMAT " disabled", os::current_thread_id()); 2539 return; 2540 } 2541 address low_addr = stack_end(); 2542 size_t len = stack_guard_zone_size(); 2543 2544 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2545 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2546 2547 int must_commit = os::must_commit_stack_guard_pages(); 2548 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2549 2550 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2551 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2552 return; 2553 } 2554 2555 if (os::guard_memory((char *) low_addr, len)) { 2556 _stack_guard_state = stack_guard_enabled; 2557 } else { 2558 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2559 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2560 if (os::uncommit_memory((char *) low_addr, len)) { 2561 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2562 } 2563 return; 2564 } 2565 2566 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2567 PTR_FORMAT "-" PTR_FORMAT ".", 2568 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2569 } 2570 2571 void JavaThread::remove_stack_guard_pages() { 2572 assert(Thread::current() == this, "from different thread"); 2573 if (_stack_guard_state == stack_guard_unused) return; 2574 address low_addr = stack_end(); 2575 size_t len = stack_guard_zone_size(); 2576 2577 if (os::must_commit_stack_guard_pages()) { 2578 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2579 _stack_guard_state = stack_guard_unused; 2580 } else { 2581 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2582 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2583 return; 2584 } 2585 } else { 2586 if (_stack_guard_state == stack_guard_unused) return; 2587 if (os::unguard_memory((char *) low_addr, len)) { 2588 _stack_guard_state = stack_guard_unused; 2589 } else { 2590 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2591 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2592 return; 2593 } 2594 } 2595 2596 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2597 PTR_FORMAT "-" PTR_FORMAT ".", 2598 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2599 } 2600 2601 void JavaThread::enable_stack_reserved_zone() { 2602 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2603 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2604 2605 // The base notation is from the stack's point of view, growing downward. 2606 // We need to adjust it to work correctly with guard_memory() 2607 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2608 2609 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2610 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2611 2612 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2613 _stack_guard_state = stack_guard_enabled; 2614 } else { 2615 warning("Attempt to guard stack reserved zone failed."); 2616 } 2617 enable_register_stack_guard(); 2618 } 2619 2620 void JavaThread::disable_stack_reserved_zone() { 2621 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2622 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2623 2624 // Simply return if called for a thread that does not use guard pages. 2625 if (_stack_guard_state == stack_guard_unused) return; 2626 2627 // The base notation is from the stack's point of view, growing downward. 2628 // We need to adjust it to work correctly with guard_memory() 2629 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2630 2631 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2632 _stack_guard_state = stack_guard_reserved_disabled; 2633 } else { 2634 warning("Attempt to unguard stack reserved zone failed."); 2635 } 2636 disable_register_stack_guard(); 2637 } 2638 2639 void JavaThread::enable_stack_yellow_reserved_zone() { 2640 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2641 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2642 2643 // The base notation is from the stacks point of view, growing downward. 2644 // We need to adjust it to work correctly with guard_memory() 2645 address base = stack_red_zone_base(); 2646 2647 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2648 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2649 2650 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2651 _stack_guard_state = stack_guard_enabled; 2652 } else { 2653 warning("Attempt to guard stack yellow zone failed."); 2654 } 2655 enable_register_stack_guard(); 2656 } 2657 2658 void JavaThread::disable_stack_yellow_reserved_zone() { 2659 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2660 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2661 2662 // Simply return if called for a thread that does not use guard pages. 2663 if (_stack_guard_state == stack_guard_unused) return; 2664 2665 // The base notation is from the stacks point of view, growing downward. 2666 // We need to adjust it to work correctly with guard_memory() 2667 address base = stack_red_zone_base(); 2668 2669 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2670 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2671 } else { 2672 warning("Attempt to unguard stack yellow zone failed."); 2673 } 2674 disable_register_stack_guard(); 2675 } 2676 2677 void JavaThread::enable_stack_red_zone() { 2678 // The base notation is from the stacks point of view, growing downward. 2679 // We need to adjust it to work correctly with guard_memory() 2680 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2681 address base = stack_red_zone_base() - stack_red_zone_size(); 2682 2683 guarantee(base < stack_base(), "Error calculating stack red zone"); 2684 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2685 2686 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2687 warning("Attempt to guard stack red zone failed."); 2688 } 2689 } 2690 2691 void JavaThread::disable_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 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2697 warning("Attempt to unguard stack red zone failed."); 2698 } 2699 } 2700 2701 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2702 // ignore is there is no stack 2703 if (!has_last_Java_frame()) return; 2704 // traverse the stack frames. Starts from top frame. 2705 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2706 frame* fr = fst.current(); 2707 f(fr, fst.register_map()); 2708 } 2709 } 2710 2711 2712 #ifndef PRODUCT 2713 // Deoptimization 2714 // Function for testing deoptimization 2715 void JavaThread::deoptimize() { 2716 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2717 StackFrameStream fst(this, UseBiasedLocking); 2718 bool deopt = false; // Dump stack only if a deopt actually happens. 2719 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2720 // Iterate over all frames in the thread and deoptimize 2721 for (; !fst.is_done(); fst.next()) { 2722 if (fst.current()->can_be_deoptimized()) { 2723 2724 if (only_at) { 2725 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2726 // consists of comma or carriage return separated numbers so 2727 // search for the current bci in that string. 2728 address pc = fst.current()->pc(); 2729 nmethod* nm = (nmethod*) fst.current()->cb(); 2730 ScopeDesc* sd = nm->scope_desc_at(pc); 2731 char buffer[8]; 2732 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2733 size_t len = strlen(buffer); 2734 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2735 while (found != NULL) { 2736 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2737 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2738 // Check that the bci found is bracketed by terminators. 2739 break; 2740 } 2741 found = strstr(found + 1, buffer); 2742 } 2743 if (!found) { 2744 continue; 2745 } 2746 } 2747 2748 if (DebugDeoptimization && !deopt) { 2749 deopt = true; // One-time only print before deopt 2750 tty->print_cr("[BEFORE Deoptimization]"); 2751 trace_frames(); 2752 trace_stack(); 2753 } 2754 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2755 } 2756 } 2757 2758 if (DebugDeoptimization && deopt) { 2759 tty->print_cr("[AFTER Deoptimization]"); 2760 trace_frames(); 2761 } 2762 } 2763 2764 2765 // Make zombies 2766 void JavaThread::make_zombies() { 2767 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2768 if (fst.current()->can_be_deoptimized()) { 2769 // it is a Java nmethod 2770 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2771 nm->make_not_entrant(); 2772 } 2773 } 2774 } 2775 #endif // PRODUCT 2776 2777 2778 void JavaThread::deoptimized_wrt_marked_nmethods() { 2779 if (!has_last_Java_frame()) return; 2780 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2781 StackFrameStream fst(this, UseBiasedLocking); 2782 for (; !fst.is_done(); fst.next()) { 2783 if (fst.current()->should_be_deoptimized()) { 2784 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2785 } 2786 } 2787 } 2788 2789 2790 // If the caller is a NamedThread, then remember, in the current scope, 2791 // the given JavaThread in its _processed_thread field. 2792 class RememberProcessedThread: public StackObj { 2793 NamedThread* _cur_thr; 2794 public: 2795 RememberProcessedThread(JavaThread* jthr) { 2796 Thread* thread = Thread::current(); 2797 if (thread->is_Named_thread()) { 2798 _cur_thr = (NamedThread *)thread; 2799 _cur_thr->set_processed_thread(jthr); 2800 } else { 2801 _cur_thr = NULL; 2802 } 2803 } 2804 2805 ~RememberProcessedThread() { 2806 if (_cur_thr) { 2807 _cur_thr->set_processed_thread(NULL); 2808 } 2809 } 2810 }; 2811 2812 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2813 // Verify that the deferred card marks have been flushed. 2814 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2815 2816 // Traverse the GCHandles 2817 Thread::oops_do(f, cf); 2818 2819 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2820 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2821 2822 if (has_last_Java_frame()) { 2823 // Record JavaThread to GC thread 2824 RememberProcessedThread rpt(this); 2825 2826 // traverse the registered growable array 2827 if (_array_for_gc != NULL) { 2828 for (int index = 0; index < _array_for_gc->length(); index++) { 2829 f->do_oop(_array_for_gc->adr_at(index)); 2830 } 2831 } 2832 2833 // Traverse the monitor chunks 2834 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2835 chunk->oops_do(f); 2836 } 2837 2838 // Traverse the execution stack 2839 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2840 fst.current()->oops_do(f, cf, fst.register_map()); 2841 } 2842 } 2843 2844 // callee_target is never live across a gc point so NULL it here should 2845 // it still contain a methdOop. 2846 2847 set_callee_target(NULL); 2848 2849 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2850 // If we have deferred set_locals there might be oops waiting to be 2851 // written 2852 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2853 if (list != NULL) { 2854 for (int i = 0; i < list->length(); i++) { 2855 list->at(i)->oops_do(f); 2856 } 2857 } 2858 2859 // Traverse instance variables at the end since the GC may be moving things 2860 // around using this function 2861 f->do_oop((oop*) &_threadObj); 2862 f->do_oop((oop*) &_vm_result); 2863 f->do_oop((oop*) &_exception_oop); 2864 f->do_oop((oop*) &_pending_async_exception); 2865 2866 if (jvmti_thread_state() != NULL) { 2867 jvmti_thread_state()->oops_do(f); 2868 } 2869 } 2870 2871 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2872 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2873 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2874 2875 if (has_last_Java_frame()) { 2876 // Traverse the execution stack 2877 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2878 fst.current()->nmethods_do(cf); 2879 } 2880 } 2881 } 2882 2883 void JavaThread::metadata_do(void f(Metadata*)) { 2884 if (has_last_Java_frame()) { 2885 // Traverse the execution stack to call f() on the methods in the stack 2886 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2887 fst.current()->metadata_do(f); 2888 } 2889 } else if (is_Compiler_thread()) { 2890 // need to walk ciMetadata in current compile tasks to keep alive. 2891 CompilerThread* ct = (CompilerThread*)this; 2892 if (ct->env() != NULL) { 2893 ct->env()->metadata_do(f); 2894 } 2895 CompileTask* task = ct->task(); 2896 if (task != NULL) { 2897 task->metadata_do(f); 2898 } 2899 } 2900 } 2901 2902 // Printing 2903 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2904 switch (_thread_state) { 2905 case _thread_uninitialized: return "_thread_uninitialized"; 2906 case _thread_new: return "_thread_new"; 2907 case _thread_new_trans: return "_thread_new_trans"; 2908 case _thread_in_native: return "_thread_in_native"; 2909 case _thread_in_native_trans: return "_thread_in_native_trans"; 2910 case _thread_in_vm: return "_thread_in_vm"; 2911 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2912 case _thread_in_Java: return "_thread_in_Java"; 2913 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2914 case _thread_blocked: return "_thread_blocked"; 2915 case _thread_blocked_trans: return "_thread_blocked_trans"; 2916 default: return "unknown thread state"; 2917 } 2918 } 2919 2920 #ifndef PRODUCT 2921 void JavaThread::print_thread_state_on(outputStream *st) const { 2922 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2923 }; 2924 void JavaThread::print_thread_state() const { 2925 print_thread_state_on(tty); 2926 } 2927 #endif // PRODUCT 2928 2929 // Called by Threads::print() for VM_PrintThreads operation 2930 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2931 st->print_raw("\""); 2932 st->print_raw(get_thread_name()); 2933 st->print_raw("\" "); 2934 oop thread_oop = threadObj(); 2935 if (thread_oop != NULL) { 2936 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2937 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2938 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2939 } 2940 Thread::print_on(st, print_extended_info); 2941 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2942 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2943 if (thread_oop != NULL) { 2944 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2945 } 2946 #ifndef PRODUCT 2947 _safepoint_state->print_on(st); 2948 #endif // PRODUCT 2949 if (is_Compiler_thread()) { 2950 CompileTask *task = ((CompilerThread*)this)->task(); 2951 if (task != NULL) { 2952 st->print(" Compiling: "); 2953 task->print(st, NULL, true, false); 2954 } else { 2955 st->print(" No compile task"); 2956 } 2957 st->cr(); 2958 } 2959 } 2960 2961 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2962 st->print("%s", get_thread_name_string(buf, buflen)); 2963 } 2964 2965 // Called by fatal error handler. The difference between this and 2966 // JavaThread::print() is that we can't grab lock or allocate memory. 2967 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2968 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2969 oop thread_obj = threadObj(); 2970 if (thread_obj != NULL) { 2971 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2972 } 2973 st->print(" ["); 2974 st->print("%s", _get_thread_state_name(_thread_state)); 2975 if (osthread()) { 2976 st->print(", id=%d", osthread()->thread_id()); 2977 } 2978 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2979 p2i(stack_end()), p2i(stack_base())); 2980 st->print("]"); 2981 2982 ThreadsSMRSupport::print_info_on(this, st); 2983 return; 2984 } 2985 2986 // Verification 2987 2988 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2989 2990 void JavaThread::verify() { 2991 // Verify oops in the thread. 2992 oops_do(&VerifyOopClosure::verify_oop, NULL); 2993 2994 // Verify the stack frames. 2995 frames_do(frame_verify); 2996 } 2997 2998 // CR 6300358 (sub-CR 2137150) 2999 // Most callers of this method assume that it can't return NULL but a 3000 // thread may not have a name whilst it is in the process of attaching to 3001 // the VM - see CR 6412693, and there are places where a JavaThread can be 3002 // seen prior to having it's threadObj set (eg JNI attaching threads and 3003 // if vm exit occurs during initialization). These cases can all be accounted 3004 // for such that this method never returns NULL. 3005 const char* JavaThread::get_thread_name() const { 3006 #ifdef ASSERT 3007 // early safepoints can hit while current thread does not yet have TLS 3008 if (!SafepointSynchronize::is_at_safepoint()) { 3009 Thread *cur = Thread::current(); 3010 if (!(cur->is_Java_thread() && cur == this)) { 3011 // Current JavaThreads are allowed to get their own name without 3012 // the Threads_lock. 3013 assert_locked_or_safepoint(Threads_lock); 3014 } 3015 } 3016 #endif // ASSERT 3017 return get_thread_name_string(); 3018 } 3019 3020 // Returns a non-NULL representation of this thread's name, or a suitable 3021 // descriptive string if there is no set name 3022 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3023 const char* name_str; 3024 oop thread_obj = threadObj(); 3025 if (thread_obj != NULL) { 3026 oop name = java_lang_Thread::name(thread_obj); 3027 if (name != NULL) { 3028 if (buf == NULL) { 3029 name_str = java_lang_String::as_utf8_string(name); 3030 } else { 3031 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3032 } 3033 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3034 name_str = "<no-name - thread is attaching>"; 3035 } else { 3036 name_str = Thread::name(); 3037 } 3038 } else { 3039 name_str = Thread::name(); 3040 } 3041 assert(name_str != NULL, "unexpected NULL thread name"); 3042 return name_str; 3043 } 3044 3045 3046 const char* JavaThread::get_threadgroup_name() const { 3047 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3048 oop thread_obj = threadObj(); 3049 if (thread_obj != NULL) { 3050 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3051 if (thread_group != NULL) { 3052 // ThreadGroup.name can be null 3053 return java_lang_ThreadGroup::name(thread_group); 3054 } 3055 } 3056 return NULL; 3057 } 3058 3059 const char* JavaThread::get_parent_name() const { 3060 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3061 oop thread_obj = threadObj(); 3062 if (thread_obj != NULL) { 3063 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3064 if (thread_group != NULL) { 3065 oop parent = java_lang_ThreadGroup::parent(thread_group); 3066 if (parent != NULL) { 3067 // ThreadGroup.name can be null 3068 return java_lang_ThreadGroup::name(parent); 3069 } 3070 } 3071 } 3072 return NULL; 3073 } 3074 3075 ThreadPriority JavaThread::java_priority() const { 3076 oop thr_oop = threadObj(); 3077 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3078 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3079 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3080 return priority; 3081 } 3082 3083 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3084 3085 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3086 // Link Java Thread object <-> C++ Thread 3087 3088 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3089 // and put it into a new Handle. The Handle "thread_oop" can then 3090 // be used to pass the C++ thread object to other methods. 3091 3092 // Set the Java level thread object (jthread) field of the 3093 // new thread (a JavaThread *) to C++ thread object using the 3094 // "thread_oop" handle. 3095 3096 // Set the thread field (a JavaThread *) of the 3097 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3098 3099 Handle thread_oop(Thread::current(), 3100 JNIHandles::resolve_non_null(jni_thread)); 3101 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3102 "must be initialized"); 3103 set_threadObj(thread_oop()); 3104 java_lang_Thread::set_thread(thread_oop(), this); 3105 3106 if (prio == NoPriority) { 3107 prio = java_lang_Thread::priority(thread_oop()); 3108 assert(prio != NoPriority, "A valid priority should be present"); 3109 } 3110 3111 // Push the Java priority down to the native thread; needs Threads_lock 3112 Thread::set_priority(this, prio); 3113 3114 // Add the new thread to the Threads list and set it in motion. 3115 // We must have threads lock in order to call Threads::add. 3116 // It is crucial that we do not block before the thread is 3117 // added to the Threads list for if a GC happens, then the java_thread oop 3118 // will not be visited by GC. 3119 Threads::add(this); 3120 } 3121 3122 oop JavaThread::current_park_blocker() { 3123 // Support for JSR-166 locks 3124 oop thread_oop = threadObj(); 3125 if (thread_oop != NULL && 3126 JDK_Version::current().supports_thread_park_blocker()) { 3127 return java_lang_Thread::park_blocker(thread_oop); 3128 } 3129 return NULL; 3130 } 3131 3132 3133 void JavaThread::print_stack_on(outputStream* st) { 3134 if (!has_last_Java_frame()) return; 3135 ResourceMark rm; 3136 HandleMark hm; 3137 3138 RegisterMap reg_map(this); 3139 vframe* start_vf = last_java_vframe(®_map); 3140 int count = 0; 3141 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3142 if (f->is_java_frame()) { 3143 javaVFrame* jvf = javaVFrame::cast(f); 3144 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3145 3146 // Print out lock information 3147 if (JavaMonitorsInStackTrace) { 3148 jvf->print_lock_info_on(st, count); 3149 } 3150 } else { 3151 // Ignore non-Java frames 3152 } 3153 3154 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3155 count++; 3156 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3157 } 3158 } 3159 3160 3161 // JVMTI PopFrame support 3162 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3163 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3164 if (in_bytes(size_in_bytes) != 0) { 3165 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3166 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3167 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3168 } 3169 } 3170 3171 void* JavaThread::popframe_preserved_args() { 3172 return _popframe_preserved_args; 3173 } 3174 3175 ByteSize JavaThread::popframe_preserved_args_size() { 3176 return in_ByteSize(_popframe_preserved_args_size); 3177 } 3178 3179 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3180 int sz = in_bytes(popframe_preserved_args_size()); 3181 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3182 return in_WordSize(sz / wordSize); 3183 } 3184 3185 void JavaThread::popframe_free_preserved_args() { 3186 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3187 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3188 _popframe_preserved_args = NULL; 3189 _popframe_preserved_args_size = 0; 3190 } 3191 3192 #ifndef PRODUCT 3193 3194 void JavaThread::trace_frames() { 3195 tty->print_cr("[Describe stack]"); 3196 int frame_no = 1; 3197 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3198 tty->print(" %d. ", frame_no++); 3199 fst.current()->print_value_on(tty, this); 3200 tty->cr(); 3201 } 3202 } 3203 3204 class PrintAndVerifyOopClosure: public OopClosure { 3205 protected: 3206 template <class T> inline void do_oop_work(T* p) { 3207 oop obj = RawAccess<>::oop_load(p); 3208 if (obj == NULL) return; 3209 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3210 if (oopDesc::is_oop_or_null(obj)) { 3211 if (obj->is_objArray()) { 3212 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3213 } else { 3214 obj->print(); 3215 } 3216 } else { 3217 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3218 } 3219 tty->cr(); 3220 } 3221 public: 3222 virtual void do_oop(oop* p) { do_oop_work(p); } 3223 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3224 }; 3225 3226 3227 static void oops_print(frame* f, const RegisterMap *map) { 3228 PrintAndVerifyOopClosure print; 3229 f->print_value(); 3230 f->oops_do(&print, NULL, (RegisterMap*)map); 3231 } 3232 3233 // Print our all the locations that contain oops and whether they are 3234 // valid or not. This useful when trying to find the oldest frame 3235 // where an oop has gone bad since the frame walk is from youngest to 3236 // oldest. 3237 void JavaThread::trace_oops() { 3238 tty->print_cr("[Trace oops]"); 3239 frames_do(oops_print); 3240 } 3241 3242 3243 #ifdef ASSERT 3244 // Print or validate the layout of stack frames 3245 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3246 ResourceMark rm; 3247 PRESERVE_EXCEPTION_MARK; 3248 FrameValues values; 3249 int frame_no = 0; 3250 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3251 fst.current()->describe(values, ++frame_no); 3252 if (depth == frame_no) break; 3253 } 3254 if (validate_only) { 3255 values.validate(); 3256 } else { 3257 tty->print_cr("[Describe stack layout]"); 3258 values.print(this); 3259 } 3260 } 3261 #endif 3262 3263 void JavaThread::trace_stack_from(vframe* start_vf) { 3264 ResourceMark rm; 3265 int vframe_no = 1; 3266 for (vframe* f = start_vf; f; f = f->sender()) { 3267 if (f->is_java_frame()) { 3268 javaVFrame::cast(f)->print_activation(vframe_no++); 3269 } else { 3270 f->print(); 3271 } 3272 if (vframe_no > StackPrintLimit) { 3273 tty->print_cr("...<more frames>..."); 3274 return; 3275 } 3276 } 3277 } 3278 3279 3280 void JavaThread::trace_stack() { 3281 if (!has_last_Java_frame()) return; 3282 ResourceMark rm; 3283 HandleMark hm; 3284 RegisterMap reg_map(this); 3285 trace_stack_from(last_java_vframe(®_map)); 3286 } 3287 3288 3289 #endif // PRODUCT 3290 3291 3292 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3293 assert(reg_map != NULL, "a map must be given"); 3294 frame f = last_frame(); 3295 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3296 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3297 } 3298 return NULL; 3299 } 3300 3301 3302 Klass* JavaThread::security_get_caller_class(int depth) { 3303 vframeStream vfst(this); 3304 vfst.security_get_caller_frame(depth); 3305 if (!vfst.at_end()) { 3306 return vfst.method()->method_holder(); 3307 } 3308 return NULL; 3309 } 3310 3311 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3312 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3313 CompileBroker::compiler_thread_loop(); 3314 } 3315 3316 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3317 NMethodSweeper::sweeper_loop(); 3318 } 3319 3320 // Create a CompilerThread 3321 CompilerThread::CompilerThread(CompileQueue* queue, 3322 CompilerCounters* counters) 3323 : JavaThread(&compiler_thread_entry) { 3324 _env = NULL; 3325 _log = NULL; 3326 _task = NULL; 3327 _queue = queue; 3328 _counters = counters; 3329 _buffer_blob = NULL; 3330 _compiler = NULL; 3331 3332 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3333 resource_area()->bias_to(mtCompiler); 3334 3335 #ifndef PRODUCT 3336 _ideal_graph_printer = NULL; 3337 #endif 3338 } 3339 3340 CompilerThread::~CompilerThread() { 3341 // Delete objects which were allocated on heap. 3342 delete _counters; 3343 } 3344 3345 bool CompilerThread::can_call_java() const { 3346 return _compiler != NULL && _compiler->is_jvmci(); 3347 } 3348 3349 // Create sweeper thread 3350 CodeCacheSweeperThread::CodeCacheSweeperThread() 3351 : JavaThread(&sweeper_thread_entry) { 3352 _scanned_compiled_method = NULL; 3353 } 3354 3355 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3356 JavaThread::oops_do(f, cf); 3357 if (_scanned_compiled_method != NULL && cf != NULL) { 3358 // Safepoints can occur when the sweeper is scanning an nmethod so 3359 // process it here to make sure it isn't unloaded in the middle of 3360 // a scan. 3361 cf->do_code_blob(_scanned_compiled_method); 3362 } 3363 } 3364 3365 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3366 JavaThread::nmethods_do(cf); 3367 if (_scanned_compiled_method != NULL && cf != NULL) { 3368 // Safepoints can occur when the sweeper is scanning an nmethod so 3369 // process it here to make sure it isn't unloaded in the middle of 3370 // a scan. 3371 cf->do_code_blob(_scanned_compiled_method); 3372 } 3373 } 3374 3375 3376 // ======= Threads ======== 3377 3378 // The Threads class links together all active threads, and provides 3379 // operations over all threads. It is protected by the Threads_lock, 3380 // which is also used in other global contexts like safepointing. 3381 // ThreadsListHandles are used to safely perform operations on one 3382 // or more threads without the risk of the thread exiting during the 3383 // operation. 3384 // 3385 // Note: The Threads_lock is currently more widely used than we 3386 // would like. We are actively migrating Threads_lock uses to other 3387 // mechanisms in order to reduce Threads_lock contention. 3388 3389 JavaThread* Threads::_thread_list = NULL; 3390 int Threads::_number_of_threads = 0; 3391 int Threads::_number_of_non_daemon_threads = 0; 3392 int Threads::_return_code = 0; 3393 int Threads::_thread_claim_parity = 0; 3394 size_t JavaThread::_stack_size_at_create = 0; 3395 3396 #ifdef ASSERT 3397 bool Threads::_vm_complete = false; 3398 size_t Threads::_threads_before_barrier_set = 0; 3399 #endif 3400 3401 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3402 Prefetch::read((void*)addr, prefetch_interval); 3403 return *addr; 3404 } 3405 3406 // Possibly the ugliest for loop the world has seen. C++ does not allow 3407 // multiple types in the declaration section of the for loop. In this case 3408 // we are only dealing with pointers and hence can cast them. It looks ugly 3409 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3410 #define DO_JAVA_THREADS(LIST, X) \ 3411 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3412 *MACRO_list = (JavaThread*)(LIST), \ 3413 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3414 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3415 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3416 MACRO_current_p != MACRO_end; \ 3417 MACRO_current_p++, \ 3418 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3419 3420 // All JavaThreads 3421 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3422 3423 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3424 void Threads::non_java_threads_do(ThreadClosure* tc) { 3425 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3426 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3427 tc->do_thread(njti.current()); 3428 } 3429 } 3430 3431 // All JavaThreads 3432 void Threads::java_threads_do(ThreadClosure* tc) { 3433 assert_locked_or_safepoint(Threads_lock); 3434 // ALL_JAVA_THREADS iterates through all JavaThreads. 3435 ALL_JAVA_THREADS(p) { 3436 tc->do_thread(p); 3437 } 3438 } 3439 3440 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3441 assert_locked_or_safepoint(Threads_lock); 3442 java_threads_do(tc); 3443 tc->do_thread(VMThread::vm_thread()); 3444 } 3445 3446 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3447 void Threads::threads_do(ThreadClosure* tc) { 3448 assert_locked_or_safepoint(Threads_lock); 3449 java_threads_do(tc); 3450 non_java_threads_do(tc); 3451 } 3452 3453 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3454 int cp = Threads::thread_claim_parity(); 3455 ALL_JAVA_THREADS(p) { 3456 if (p->claim_oops_do(is_par, cp)) { 3457 tc->do_thread(p); 3458 } 3459 } 3460 VMThread* vmt = VMThread::vm_thread(); 3461 if (vmt->claim_oops_do(is_par, cp)) { 3462 tc->do_thread(vmt); 3463 } 3464 } 3465 3466 // The system initialization in the library has three phases. 3467 // 3468 // Phase 1: java.lang.System class initialization 3469 // java.lang.System is a primordial class loaded and initialized 3470 // by the VM early during startup. java.lang.System.<clinit> 3471 // only does registerNatives and keeps the rest of the class 3472 // initialization work later until thread initialization completes. 3473 // 3474 // System.initPhase1 initializes the system properties, the static 3475 // fields in, out, and err. Set up java signal handlers, OS-specific 3476 // system settings, and thread group of the main thread. 3477 static void call_initPhase1(TRAPS) { 3478 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3479 JavaValue result(T_VOID); 3480 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3481 vmSymbols::void_method_signature(), CHECK); 3482 } 3483 3484 // Phase 2. Module system initialization 3485 // This will initialize the module system. Only java.base classes 3486 // can be loaded until phase 2 completes. 3487 // 3488 // Call System.initPhase2 after the compiler initialization and jsr292 3489 // classes get initialized because module initialization runs a lot of java 3490 // code, that for performance reasons, should be compiled. Also, this will 3491 // enable the startup code to use lambda and other language features in this 3492 // phase and onward. 3493 // 3494 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3495 static void call_initPhase2(TRAPS) { 3496 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3497 3498 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3499 3500 JavaValue result(T_INT); 3501 JavaCallArguments args; 3502 args.push_int(DisplayVMOutputToStderr); 3503 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3504 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3505 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3506 if (result.get_jint() != JNI_OK) { 3507 vm_exit_during_initialization(); // no message or exception 3508 } 3509 3510 universe_post_module_init(); 3511 } 3512 3513 // Phase 3. final setup - set security manager, system class loader and TCCL 3514 // 3515 // This will instantiate and set the security manager, set the system class 3516 // loader as well as the thread context class loader. The security manager 3517 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3518 // other modules or the application's classpath. 3519 static void call_initPhase3(TRAPS) { 3520 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3521 JavaValue result(T_VOID); 3522 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3523 vmSymbols::void_method_signature(), CHECK); 3524 } 3525 3526 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3527 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3528 3529 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3530 create_vm_init_libraries(); 3531 } 3532 3533 initialize_class(vmSymbols::java_lang_String(), CHECK); 3534 3535 // Inject CompactStrings value after the static initializers for String ran. 3536 java_lang_String::set_compact_strings(CompactStrings); 3537 3538 // Initialize java_lang.System (needed before creating the thread) 3539 initialize_class(vmSymbols::java_lang_System(), CHECK); 3540 // The VM creates & returns objects of this class. Make sure it's initialized. 3541 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3542 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3543 Handle thread_group = create_initial_thread_group(CHECK); 3544 Universe::set_main_thread_group(thread_group()); 3545 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3546 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3547 main_thread->set_threadObj(thread_object); 3548 // Set thread status to running since main thread has 3549 // been started and running. 3550 java_lang_Thread::set_thread_status(thread_object, 3551 java_lang_Thread::RUNNABLE); 3552 3553 // The VM creates objects of this class. 3554 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3555 3556 // The VM preresolves methods to these classes. Make sure that they get initialized 3557 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3558 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3559 3560 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3561 call_initPhase1(CHECK); 3562 3563 // get the Java runtime name after java.lang.System is initialized 3564 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3565 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3566 3567 // an instance of OutOfMemory exception has been allocated earlier 3568 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3569 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3570 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3571 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3572 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3573 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3574 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3575 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3576 } 3577 3578 void Threads::initialize_jsr292_core_classes(TRAPS) { 3579 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3580 3581 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3582 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3583 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3584 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3585 } 3586 3587 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3588 extern void JDK_Version_init(); 3589 3590 // Preinitialize version info. 3591 VM_Version::early_initialize(); 3592 3593 // Check version 3594 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3595 3596 // Initialize library-based TLS 3597 ThreadLocalStorage::init(); 3598 3599 // Initialize the output stream module 3600 ostream_init(); 3601 3602 // Process java launcher properties. 3603 Arguments::process_sun_java_launcher_properties(args); 3604 3605 // Initialize the os module 3606 os::init(); 3607 3608 // Record VM creation timing statistics 3609 TraceVmCreationTime create_vm_timer; 3610 create_vm_timer.start(); 3611 3612 // Initialize system properties. 3613 Arguments::init_system_properties(); 3614 3615 // So that JDK version can be used as a discriminator when parsing arguments 3616 JDK_Version_init(); 3617 3618 // Update/Initialize System properties after JDK version number is known 3619 Arguments::init_version_specific_system_properties(); 3620 3621 // Make sure to initialize log configuration *before* parsing arguments 3622 LogConfiguration::initialize(create_vm_timer.begin_time()); 3623 3624 // Parse arguments 3625 // Note: this internally calls os::init_container_support() 3626 jint parse_result = Arguments::parse(args); 3627 if (parse_result != JNI_OK) return parse_result; 3628 3629 os::init_before_ergo(); 3630 3631 jint ergo_result = Arguments::apply_ergo(); 3632 if (ergo_result != JNI_OK) return ergo_result; 3633 3634 // Final check of all ranges after ergonomics which may change values. 3635 if (!JVMFlagRangeList::check_ranges()) { 3636 return JNI_EINVAL; 3637 } 3638 3639 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3640 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3641 if (!constraint_result) { 3642 return JNI_EINVAL; 3643 } 3644 3645 JVMFlagWriteableList::mark_startup(); 3646 3647 if (PauseAtStartup) { 3648 os::pause(); 3649 } 3650 3651 HOTSPOT_VM_INIT_BEGIN(); 3652 3653 // Timing (must come after argument parsing) 3654 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3655 3656 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3657 // Initialize assert poison page mechanism. 3658 if (ShowRegistersOnAssert) { 3659 initialize_assert_poison(); 3660 } 3661 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3662 3663 // Initialize the os module after parsing the args 3664 jint os_init_2_result = os::init_2(); 3665 if (os_init_2_result != JNI_OK) return os_init_2_result; 3666 3667 SafepointMechanism::initialize(); 3668 3669 jint adjust_after_os_result = Arguments::adjust_after_os(); 3670 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3671 3672 // Initialize output stream logging 3673 ostream_init_log(); 3674 3675 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3676 // Must be before create_vm_init_agents() 3677 if (Arguments::init_libraries_at_startup()) { 3678 convert_vm_init_libraries_to_agents(); 3679 } 3680 3681 // Launch -agentlib/-agentpath and converted -Xrun agents 3682 if (Arguments::init_agents_at_startup()) { 3683 create_vm_init_agents(); 3684 } 3685 3686 // Initialize Threads state 3687 _thread_list = NULL; 3688 _number_of_threads = 0; 3689 _number_of_non_daemon_threads = 0; 3690 3691 // Initialize global data structures and create system classes in heap 3692 vm_init_globals(); 3693 3694 #if INCLUDE_JVMCI 3695 if (JVMCICounterSize > 0) { 3696 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3697 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3698 } else { 3699 JavaThread::_jvmci_old_thread_counters = NULL; 3700 } 3701 #endif // INCLUDE_JVMCI 3702 3703 // Attach the main thread to this os thread 3704 JavaThread* main_thread = new JavaThread(); 3705 main_thread->set_thread_state(_thread_in_vm); 3706 main_thread->initialize_thread_current(); 3707 // must do this before set_active_handles 3708 main_thread->record_stack_base_and_size(); 3709 main_thread->register_thread_stack_with_NMT(); 3710 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3711 3712 if (!main_thread->set_as_starting_thread()) { 3713 vm_shutdown_during_initialization( 3714 "Failed necessary internal allocation. Out of swap space"); 3715 main_thread->smr_delete(); 3716 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3717 return JNI_ENOMEM; 3718 } 3719 3720 // Enable guard page *after* os::create_main_thread(), otherwise it would 3721 // crash Linux VM, see notes in os_linux.cpp. 3722 main_thread->create_stack_guard_pages(); 3723 3724 // Initialize Java-Level synchronization subsystem 3725 ObjectMonitor::Initialize(); 3726 3727 // Initialize global modules 3728 jint status = init_globals(); 3729 if (status != JNI_OK) { 3730 main_thread->smr_delete(); 3731 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3732 return status; 3733 } 3734 3735 JFR_ONLY(Jfr::on_vm_init();) 3736 3737 // Should be done after the heap is fully created 3738 main_thread->cache_global_variables(); 3739 3740 HandleMark hm; 3741 3742 { MutexLocker mu(Threads_lock); 3743 Threads::add(main_thread); 3744 } 3745 3746 // Any JVMTI raw monitors entered in onload will transition into 3747 // real raw monitor. VM is setup enough here for raw monitor enter. 3748 JvmtiExport::transition_pending_onload_raw_monitors(); 3749 3750 // Create the VMThread 3751 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3752 3753 VMThread::create(); 3754 Thread* vmthread = VMThread::vm_thread(); 3755 3756 if (!os::create_thread(vmthread, os::vm_thread)) { 3757 vm_exit_during_initialization("Cannot create VM thread. " 3758 "Out of system resources."); 3759 } 3760 3761 // Wait for the VM thread to become ready, and VMThread::run to initialize 3762 // Monitors can have spurious returns, must always check another state flag 3763 { 3764 MutexLocker ml(Notify_lock); 3765 os::start_thread(vmthread); 3766 while (vmthread->active_handles() == NULL) { 3767 Notify_lock->wait(); 3768 } 3769 } 3770 } 3771 3772 assert(Universe::is_fully_initialized(), "not initialized"); 3773 if (VerifyDuringStartup) { 3774 // Make sure we're starting with a clean slate. 3775 VM_Verify verify_op; 3776 VMThread::execute(&verify_op); 3777 } 3778 3779 // We need this to update the java.vm.info property in case any flags used 3780 // to initially define it have been changed. This is needed for both CDS and 3781 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3782 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3783 // This update must happen before we initialize the java classes, but 3784 // after any initialization logic that might modify the flags. 3785 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3786 3787 Thread* THREAD = Thread::current(); 3788 3789 // Always call even when there are not JVMTI environments yet, since environments 3790 // may be attached late and JVMTI must track phases of VM execution 3791 JvmtiExport::enter_early_start_phase(); 3792 3793 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3794 JvmtiExport::post_early_vm_start(); 3795 3796 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3797 3798 quicken_jni_functions(); 3799 3800 // No more stub generation allowed after that point. 3801 StubCodeDesc::freeze(); 3802 3803 // Set flag that basic initialization has completed. Used by exceptions and various 3804 // debug stuff, that does not work until all basic classes have been initialized. 3805 set_init_completed(); 3806 3807 LogConfiguration::post_initialize(); 3808 Metaspace::post_initialize(); 3809 3810 HOTSPOT_VM_INIT_END(); 3811 3812 // record VM initialization completion time 3813 #if INCLUDE_MANAGEMENT 3814 Management::record_vm_init_completed(); 3815 #endif // INCLUDE_MANAGEMENT 3816 3817 // Signal Dispatcher needs to be started before VMInit event is posted 3818 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3819 3820 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3821 if (!DisableAttachMechanism) { 3822 AttachListener::vm_start(); 3823 if (StartAttachListener || AttachListener::init_at_startup()) { 3824 AttachListener::init(); 3825 } 3826 } 3827 3828 // Launch -Xrun agents 3829 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3830 // back-end can launch with -Xdebug -Xrunjdwp. 3831 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3832 create_vm_init_libraries(); 3833 } 3834 3835 if (CleanChunkPoolAsync) { 3836 Chunk::start_chunk_pool_cleaner_task(); 3837 } 3838 3839 // initialize compiler(s) 3840 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3841 #if INCLUDE_JVMCI 3842 bool force_JVMCI_intialization = false; 3843 if (EnableJVMCI) { 3844 // Initialize JVMCI eagerly when it is explicitly requested. 3845 // Or when JVMCIPrintProperties is enabled. 3846 // The JVMCI Java initialization code will read this flag and 3847 // do the printing if it's set. 3848 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3849 3850 if (!force_JVMCI_intialization) { 3851 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3852 // compilations via JVMCI will not actually block until JVMCI is initialized. 3853 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3854 } 3855 } 3856 #endif 3857 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3858 // Postpone completion of compiler initialization to after JVMCI 3859 // is initialized to avoid timeouts of blocking compilations. 3860 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3861 CompileBroker::compilation_init_phase2(); 3862 } 3863 #endif 3864 3865 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3866 // It is done after compilers are initialized, because otherwise compilations of 3867 // signature polymorphic MH intrinsics can be missed 3868 // (see SystemDictionary::find_method_handle_intrinsic). 3869 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3870 3871 // This will initialize the module system. Only java.base classes can be 3872 // loaded until phase 2 completes 3873 call_initPhase2(CHECK_JNI_ERR); 3874 3875 // Always call even when there are not JVMTI environments yet, since environments 3876 // may be attached late and JVMTI must track phases of VM execution 3877 JvmtiExport::enter_start_phase(); 3878 3879 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3880 JvmtiExport::post_vm_start(); 3881 3882 // Final system initialization including security manager and system class loader 3883 call_initPhase3(CHECK_JNI_ERR); 3884 3885 // cache the system and platform class loaders 3886 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3887 3888 #if INCLUDE_CDS 3889 if (DumpSharedSpaces) { 3890 // capture the module path info from the ModuleEntryTable 3891 ClassLoader::initialize_module_path(THREAD); 3892 } 3893 #endif 3894 3895 #if INCLUDE_JVMCI 3896 if (force_JVMCI_intialization) { 3897 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3898 CompileBroker::compilation_init_phase2(); 3899 } 3900 #endif 3901 3902 // Always call even when there are not JVMTI environments yet, since environments 3903 // may be attached late and JVMTI must track phases of VM execution 3904 JvmtiExport::enter_live_phase(); 3905 3906 // Make perfmemory accessible 3907 PerfMemory::set_accessible(true); 3908 3909 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3910 JvmtiExport::post_vm_initialized(); 3911 3912 JFR_ONLY(Jfr::on_vm_start();) 3913 3914 #if INCLUDE_MANAGEMENT 3915 Management::initialize(THREAD); 3916 3917 if (HAS_PENDING_EXCEPTION) { 3918 // management agent fails to start possibly due to 3919 // configuration problem and is responsible for printing 3920 // stack trace if appropriate. Simply exit VM. 3921 vm_exit(1); 3922 } 3923 #endif // INCLUDE_MANAGEMENT 3924 3925 if (MemProfiling) MemProfiler::engage(); 3926 StatSampler::engage(); 3927 if (CheckJNICalls) JniPeriodicChecker::engage(); 3928 3929 BiasedLocking::init(); 3930 3931 #if INCLUDE_RTM_OPT 3932 RTMLockingCounters::init(); 3933 #endif 3934 3935 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3936 call_postVMInitHook(THREAD); 3937 // The Java side of PostVMInitHook.run must deal with all 3938 // exceptions and provide means of diagnosis. 3939 if (HAS_PENDING_EXCEPTION) { 3940 CLEAR_PENDING_EXCEPTION; 3941 } 3942 } 3943 3944 { 3945 MutexLocker ml(PeriodicTask_lock); 3946 // Make sure the WatcherThread can be started by WatcherThread::start() 3947 // or by dynamic enrollment. 3948 WatcherThread::make_startable(); 3949 // Start up the WatcherThread if there are any periodic tasks 3950 // NOTE: All PeriodicTasks should be registered by now. If they 3951 // aren't, late joiners might appear to start slowly (we might 3952 // take a while to process their first tick). 3953 if (PeriodicTask::num_tasks() > 0) { 3954 WatcherThread::start(); 3955 } 3956 } 3957 3958 create_vm_timer.end(); 3959 #ifdef ASSERT 3960 _vm_complete = true; 3961 #endif 3962 3963 if (DumpSharedSpaces) { 3964 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3965 ShouldNotReachHere(); 3966 } 3967 3968 return JNI_OK; 3969 } 3970 3971 // type for the Agent_OnLoad and JVM_OnLoad entry points 3972 extern "C" { 3973 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3974 } 3975 // Find a command line agent library and return its entry point for 3976 // -agentlib: -agentpath: -Xrun 3977 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3978 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3979 const char *on_load_symbols[], 3980 size_t num_symbol_entries) { 3981 OnLoadEntry_t on_load_entry = NULL; 3982 void *library = NULL; 3983 3984 if (!agent->valid()) { 3985 char buffer[JVM_MAXPATHLEN]; 3986 char ebuf[1024] = ""; 3987 const char *name = agent->name(); 3988 const char *msg = "Could not find agent library "; 3989 3990 // First check to see if agent is statically linked into executable 3991 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3992 library = agent->os_lib(); 3993 } else if (agent->is_absolute_path()) { 3994 library = os::dll_load(name, ebuf, sizeof ebuf); 3995 if (library == NULL) { 3996 const char *sub_msg = " in absolute path, with error: "; 3997 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3998 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3999 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4000 // If we can't find the agent, exit. 4001 vm_exit_during_initialization(buf, NULL); 4002 FREE_C_HEAP_ARRAY(char, buf); 4003 } 4004 } else { 4005 // Try to load the agent from the standard dll directory 4006 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4007 name)) { 4008 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4009 } 4010 if (library == NULL) { // Try the library path directory. 4011 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4012 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4013 } 4014 if (library == NULL) { 4015 const char *sub_msg = " on the library path, with error: "; 4016 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4017 4018 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4019 strlen(ebuf) + strlen(sub_msg2) + 1; 4020 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4021 if (!agent->is_instrument_lib()) { 4022 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4023 } else { 4024 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4025 } 4026 // If we can't find the agent, exit. 4027 vm_exit_during_initialization(buf, NULL); 4028 FREE_C_HEAP_ARRAY(char, buf); 4029 } 4030 } 4031 } 4032 agent->set_os_lib(library); 4033 agent->set_valid(); 4034 } 4035 4036 // Find the OnLoad function. 4037 on_load_entry = 4038 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4039 false, 4040 on_load_symbols, 4041 num_symbol_entries)); 4042 return on_load_entry; 4043 } 4044 4045 // Find the JVM_OnLoad entry point 4046 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4047 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4048 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4049 } 4050 4051 // Find the Agent_OnLoad entry point 4052 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4053 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4054 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4055 } 4056 4057 // For backwards compatibility with -Xrun 4058 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4059 // treated like -agentpath: 4060 // Must be called before agent libraries are created 4061 void Threads::convert_vm_init_libraries_to_agents() { 4062 AgentLibrary* agent; 4063 AgentLibrary* next; 4064 4065 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4066 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4067 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4068 4069 // If there is an JVM_OnLoad function it will get called later, 4070 // otherwise see if there is an Agent_OnLoad 4071 if (on_load_entry == NULL) { 4072 on_load_entry = lookup_agent_on_load(agent); 4073 if (on_load_entry != NULL) { 4074 // switch it to the agent list -- so that Agent_OnLoad will be called, 4075 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4076 Arguments::convert_library_to_agent(agent); 4077 } else { 4078 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4079 } 4080 } 4081 } 4082 } 4083 4084 // Create agents for -agentlib: -agentpath: and converted -Xrun 4085 // Invokes Agent_OnLoad 4086 // Called very early -- before JavaThreads exist 4087 void Threads::create_vm_init_agents() { 4088 extern struct JavaVM_ main_vm; 4089 AgentLibrary* agent; 4090 4091 JvmtiExport::enter_onload_phase(); 4092 4093 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4094 // CDS dumping does not support native JVMTI agent. 4095 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4096 if (DumpSharedSpaces) { 4097 if(!agent->is_instrument_lib()) { 4098 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4099 } else if (!AllowArchivingWithJavaAgent) { 4100 vm_exit_during_cds_dumping( 4101 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4102 } 4103 } 4104 4105 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4106 4107 if (on_load_entry != NULL) { 4108 // Invoke the Agent_OnLoad function 4109 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4110 if (err != JNI_OK) { 4111 vm_exit_during_initialization("agent library failed to init", agent->name()); 4112 } 4113 } else { 4114 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4115 } 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 MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag); 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 st->print(" "); 4710 task->print(st, NULL, true, true); 4711 } 4712 } 4713 } 4714 } 4715 4716 4717 // Internal SpinLock and Mutex 4718 // Based on ParkEvent 4719 4720 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4721 // 4722 // We employ SpinLocks _only for low-contention, fixed-length 4723 // short-duration critical sections where we're concerned 4724 // about native mutex_t or HotSpot Mutex:: latency. 4725 // The mux construct provides a spin-then-block mutual exclusion 4726 // mechanism. 4727 // 4728 // Testing has shown that contention on the ListLock guarding gFreeList 4729 // is common. If we implement ListLock as a simple SpinLock it's common 4730 // for the JVM to devolve to yielding with little progress. This is true 4731 // despite the fact that the critical sections protected by ListLock are 4732 // extremely short. 4733 // 4734 // TODO-FIXME: ListLock should be of type SpinLock. 4735 // We should make this a 1st-class type, integrated into the lock 4736 // hierarchy as leaf-locks. Critically, the SpinLock structure 4737 // should have sufficient padding to avoid false-sharing and excessive 4738 // cache-coherency traffic. 4739 4740 4741 typedef volatile int SpinLockT; 4742 4743 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4744 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4745 return; // normal fast-path return 4746 } 4747 4748 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4749 int ctr = 0; 4750 int Yields = 0; 4751 for (;;) { 4752 while (*adr != 0) { 4753 ++ctr; 4754 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4755 if (Yields > 5) { 4756 os::naked_short_sleep(1); 4757 } else { 4758 os::naked_yield(); 4759 ++Yields; 4760 } 4761 } else { 4762 SpinPause(); 4763 } 4764 } 4765 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4766 } 4767 } 4768 4769 void Thread::SpinRelease(volatile int * adr) { 4770 assert(*adr != 0, "invariant"); 4771 OrderAccess::fence(); // guarantee at least release consistency. 4772 // Roach-motel semantics. 4773 // It's safe if subsequent LDs and STs float "up" into the critical section, 4774 // but prior LDs and STs within the critical section can't be allowed 4775 // to reorder or float past the ST that releases the lock. 4776 // Loads and stores in the critical section - which appear in program 4777 // order before the store that releases the lock - must also appear 4778 // before the store that releases the lock in memory visibility order. 4779 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4780 // the ST of 0 into the lock-word which releases the lock, so fence 4781 // more than covers this on all platforms. 4782 *adr = 0; 4783 } 4784 4785 // muxAcquire and muxRelease: 4786 // 4787 // * muxAcquire and muxRelease support a single-word lock-word construct. 4788 // The LSB of the word is set IFF the lock is held. 4789 // The remainder of the word points to the head of a singly-linked list 4790 // of threads blocked on the lock. 4791 // 4792 // * The current implementation of muxAcquire-muxRelease uses its own 4793 // dedicated Thread._MuxEvent instance. If we're interested in 4794 // minimizing the peak number of extant ParkEvent instances then 4795 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4796 // as certain invariants were satisfied. Specifically, care would need 4797 // to be taken with regards to consuming unpark() "permits". 4798 // A safe rule of thumb is that a thread would never call muxAcquire() 4799 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4800 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4801 // consume an unpark() permit intended for monitorenter, for instance. 4802 // One way around this would be to widen the restricted-range semaphore 4803 // implemented in park(). Another alternative would be to provide 4804 // multiple instances of the PlatformEvent() for each thread. One 4805 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4806 // 4807 // * Usage: 4808 // -- Only as leaf locks 4809 // -- for short-term locking only as muxAcquire does not perform 4810 // thread state transitions. 4811 // 4812 // Alternatives: 4813 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4814 // but with parking or spin-then-park instead of pure spinning. 4815 // * Use Taura-Oyama-Yonenzawa locks. 4816 // * It's possible to construct a 1-0 lock if we encode the lockword as 4817 // (List,LockByte). Acquire will CAS the full lockword while Release 4818 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4819 // acquiring threads use timers (ParkTimed) to detect and recover from 4820 // the stranding window. Thread/Node structures must be aligned on 256-byte 4821 // boundaries by using placement-new. 4822 // * Augment MCS with advisory back-link fields maintained with CAS(). 4823 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4824 // The validity of the backlinks must be ratified before we trust the value. 4825 // If the backlinks are invalid the exiting thread must back-track through the 4826 // the forward links, which are always trustworthy. 4827 // * Add a successor indication. The LockWord is currently encoded as 4828 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4829 // to provide the usual futile-wakeup optimization. 4830 // See RTStt for details. 4831 // 4832 4833 4834 const intptr_t LOCKBIT = 1; 4835 4836 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4837 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4838 if (w == 0) return; 4839 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4840 return; 4841 } 4842 4843 ParkEvent * const Self = Thread::current()->_MuxEvent; 4844 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4845 for (;;) { 4846 int its = (os::is_MP() ? 100 : 0) + 1; 4847 4848 // Optional spin phase: spin-then-park strategy 4849 while (--its >= 0) { 4850 w = *Lock; 4851 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4852 return; 4853 } 4854 } 4855 4856 Self->reset(); 4857 Self->OnList = intptr_t(Lock); 4858 // The following fence() isn't _strictly necessary as the subsequent 4859 // CAS() both serializes execution and ratifies the fetched *Lock value. 4860 OrderAccess::fence(); 4861 for (;;) { 4862 w = *Lock; 4863 if ((w & LOCKBIT) == 0) { 4864 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4865 Self->OnList = 0; // hygiene - allows stronger asserts 4866 return; 4867 } 4868 continue; // Interference -- *Lock changed -- Just retry 4869 } 4870 assert(w & LOCKBIT, "invariant"); 4871 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4872 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4873 } 4874 4875 while (Self->OnList != 0) { 4876 Self->park(); 4877 } 4878 } 4879 } 4880 4881 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4882 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4883 if (w == 0) return; 4884 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4885 return; 4886 } 4887 4888 ParkEvent * ReleaseAfter = NULL; 4889 if (ev == NULL) { 4890 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4891 } 4892 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4893 for (;;) { 4894 guarantee(ev->OnList == 0, "invariant"); 4895 int its = (os::is_MP() ? 100 : 0) + 1; 4896 4897 // Optional spin phase: spin-then-park strategy 4898 while (--its >= 0) { 4899 w = *Lock; 4900 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4901 if (ReleaseAfter != NULL) { 4902 ParkEvent::Release(ReleaseAfter); 4903 } 4904 return; 4905 } 4906 } 4907 4908 ev->reset(); 4909 ev->OnList = intptr_t(Lock); 4910 // The following fence() isn't _strictly necessary as the subsequent 4911 // CAS() both serializes execution and ratifies the fetched *Lock value. 4912 OrderAccess::fence(); 4913 for (;;) { 4914 w = *Lock; 4915 if ((w & LOCKBIT) == 0) { 4916 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4917 ev->OnList = 0; 4918 // We call ::Release while holding the outer lock, thus 4919 // artificially lengthening the critical section. 4920 // Consider deferring the ::Release() until the subsequent unlock(), 4921 // after we've dropped the outer lock. 4922 if (ReleaseAfter != NULL) { 4923 ParkEvent::Release(ReleaseAfter); 4924 } 4925 return; 4926 } 4927 continue; // Interference -- *Lock changed -- Just retry 4928 } 4929 assert(w & LOCKBIT, "invariant"); 4930 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4931 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4932 } 4933 4934 while (ev->OnList != 0) { 4935 ev->park(); 4936 } 4937 } 4938 } 4939 4940 // Release() must extract a successor from the list and then wake that thread. 4941 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4942 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4943 // Release() would : 4944 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4945 // (B) Extract a successor from the private list "in-hand" 4946 // (C) attempt to CAS() the residual back into *Lock over null. 4947 // If there were any newly arrived threads and the CAS() would fail. 4948 // In that case Release() would detach the RATs, re-merge the list in-hand 4949 // with the RATs and repeat as needed. Alternately, Release() might 4950 // detach and extract a successor, but then pass the residual list to the wakee. 4951 // The wakee would be responsible for reattaching and remerging before it 4952 // competed for the lock. 4953 // 4954 // Both "pop" and DMR are immune from ABA corruption -- there can be 4955 // multiple concurrent pushers, but only one popper or detacher. 4956 // This implementation pops from the head of the list. This is unfair, 4957 // but tends to provide excellent throughput as hot threads remain hot. 4958 // (We wake recently run threads first). 4959 // 4960 // All paths through muxRelease() will execute a CAS. 4961 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4962 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4963 // executed within the critical section are complete and globally visible before the 4964 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4965 void Thread::muxRelease(volatile intptr_t * Lock) { 4966 for (;;) { 4967 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4968 assert(w & LOCKBIT, "invariant"); 4969 if (w == LOCKBIT) return; 4970 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4971 assert(List != NULL, "invariant"); 4972 assert(List->OnList == intptr_t(Lock), "invariant"); 4973 ParkEvent * const nxt = List->ListNext; 4974 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4975 4976 // The following CAS() releases the lock and pops the head element. 4977 // The CAS() also ratifies the previously fetched lock-word value. 4978 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4979 continue; 4980 } 4981 List->OnList = 0; 4982 OrderAccess::fence(); 4983 List->unpark(); 4984 return; 4985 } 4986 } 4987 4988 4989 void Threads::verify() { 4990 ALL_JAVA_THREADS(p) { 4991 p->verify(); 4992 } 4993 VMThread* thread = VMThread::vm_thread(); 4994 if (thread != NULL) thread->verify(); 4995 }