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/vmOperations.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_verifier = 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. The initial 310 // thread is created before the barrier set is available. The call to 311 // BarrierSet::on_thread_create() for this thread 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 #ifdef ASSERT 318 static bool initial_thread_created = false; 319 assert(!initial_thread_created, "creating thread before barrier set"); 320 initial_thread_created = true; 321 #endif // ASSERT 322 } 323 } 324 325 void Thread::initialize_thread_current() { 326 #ifndef USE_LIBRARY_BASED_TLS_ONLY 327 assert(_thr_current == NULL, "Thread::current already initialized"); 328 _thr_current = this; 329 #endif 330 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 331 ThreadLocalStorage::set_thread(this); 332 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 333 } 334 335 void Thread::clear_thread_current() { 336 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 337 #ifndef USE_LIBRARY_BASED_TLS_ONLY 338 _thr_current = NULL; 339 #endif 340 ThreadLocalStorage::set_thread(NULL); 341 } 342 343 void Thread::record_stack_base_and_size() { 344 // Note: at this point, Thread object is not yet initialized. Do not rely on 345 // any members being initialized. Do not rely on Thread::current() being set. 346 // If possible, refrain from doing anything which may crash or assert since 347 // quite probably those crash dumps will be useless. 348 set_stack_base(os::current_stack_base()); 349 set_stack_size(os::current_stack_size()); 350 351 #ifdef SOLARIS 352 if (os::is_primordial_thread()) { 353 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 354 } 355 #endif 356 357 // Set stack limits after thread is initialized. 358 if (is_Java_thread()) { 359 ((JavaThread*) this)->set_stack_overflow_limit(); 360 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 361 } 362 } 363 364 #if INCLUDE_NMT 365 void Thread::register_thread_stack_with_NMT() { 366 MemTracker::record_thread_stack(stack_end(), stack_size()); 367 } 368 #endif // INCLUDE_NMT 369 370 void Thread::call_run() { 371 // At this point, Thread object should be fully initialized and 372 // Thread::current() should be set. 373 374 register_thread_stack_with_NMT(); 375 376 JFR_ONLY(Jfr::on_thread_start(this);) 377 378 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 379 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 380 os::current_thread_id(), p2i(stack_base() - stack_size()), 381 p2i(stack_base()), stack_size()/1024); 382 383 // Invoke <ChildClass>::run() 384 this->run(); 385 // Returned from <ChildClass>::run(). Thread finished. 386 387 // Note: at this point the thread object may already have deleted itself. 388 // So from here on do not dereference *this*. 389 390 // If a thread has not deleted itself ("delete this") as part of its 391 // termination sequence, we have to ensure thread-local-storage is 392 // cleared before we actually terminate. No threads should ever be 393 // deleted asynchronously with respect to their termination. 394 if (Thread::current_or_null_safe() != NULL) { 395 assert(Thread::current_or_null_safe() == this, "current thread is wrong"); 396 Thread::clear_thread_current(); 397 } 398 399 } 400 401 Thread::~Thread() { 402 // Notify the barrier set that a thread is being destroyed. Note that a barrier 403 // set might not be available if we encountered errors during bootstrapping. 404 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 405 if (barrier_set != NULL) { 406 barrier_set->on_thread_destroy(this); 407 } 408 409 // stack_base can be NULL if the thread is never started or exited before 410 // record_stack_base_and_size called. Although, we would like to ensure 411 // that all started threads do call record_stack_base_and_size(), there is 412 // not proper way to enforce that. 413 #if INCLUDE_NMT 414 if (_stack_base != NULL) { 415 MemTracker::release_thread_stack(stack_end(), stack_size()); 416 #ifdef ASSERT 417 set_stack_base(NULL); 418 #endif 419 } 420 #endif // INCLUDE_NMT 421 422 // deallocate data structures 423 delete resource_area(); 424 // since the handle marks are using the handle area, we have to deallocated the root 425 // handle mark before deallocating the thread's handle area, 426 assert(last_handle_mark() != NULL, "check we have an element"); 427 delete last_handle_mark(); 428 assert(last_handle_mark() == NULL, "check we have reached the end"); 429 430 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 431 // We NULL out the fields for good hygiene. 432 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 433 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 434 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 435 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 436 437 delete handle_area(); 438 delete metadata_handles(); 439 440 // SR_handler uses this as a termination indicator - 441 // needs to happen before os::free_thread() 442 delete _SR_lock; 443 _SR_lock = NULL; 444 445 // osthread() can be NULL, if creation of thread failed. 446 if (osthread() != NULL) os::free_thread(osthread()); 447 448 // clear Thread::current if thread is deleting itself. 449 // Needed to ensure JNI correctly detects non-attached threads. 450 if (this == Thread::current()) { 451 Thread::clear_thread_current(); 452 } 453 454 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 455 } 456 457 #ifdef ASSERT 458 // A JavaThread is considered "dangling" if it is not the current 459 // thread, has been added the Threads list, the system is not at a 460 // safepoint and the Thread is not "protected". 461 // 462 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 463 assert(!thread->is_Java_thread() || Thread::current() == thread || 464 !((JavaThread *) thread)->on_thread_list() || 465 SafepointSynchronize::is_at_safepoint() || 466 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 467 "possibility of dangling Thread pointer"); 468 } 469 #endif 470 471 ThreadPriority Thread::get_priority(const Thread* const thread) { 472 ThreadPriority priority; 473 // Can return an error! 474 (void)os::get_priority(thread, priority); 475 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 476 return priority; 477 } 478 479 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 480 debug_only(check_for_dangling_thread_pointer(thread);) 481 // Can return an error! 482 (void)os::set_priority(thread, priority); 483 } 484 485 486 void Thread::start(Thread* thread) { 487 // Start is different from resume in that its safety is guaranteed by context or 488 // being called from a Java method synchronized on the Thread object. 489 if (!DisableStartThread) { 490 if (thread->is_Java_thread()) { 491 // Initialize the thread state to RUNNABLE before starting this thread. 492 // Can not set it after the thread started because we do not know the 493 // exact thread state at that time. It could be in MONITOR_WAIT or 494 // in SLEEPING or some other state. 495 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 496 java_lang_Thread::RUNNABLE); 497 } 498 os::start_thread(thread); 499 } 500 } 501 502 // Enqueue a VM_Operation to do the job for us - sometime later 503 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 504 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 505 VMThread::execute(vm_stop); 506 } 507 508 509 // Check if an external suspend request has completed (or has been 510 // cancelled). Returns true if the thread is externally suspended and 511 // false otherwise. 512 // 513 // The bits parameter returns information about the code path through 514 // the routine. Useful for debugging: 515 // 516 // set in is_ext_suspend_completed(): 517 // 0x00000001 - routine was entered 518 // 0x00000010 - routine return false at end 519 // 0x00000100 - thread exited (return false) 520 // 0x00000200 - suspend request cancelled (return false) 521 // 0x00000400 - thread suspended (return true) 522 // 0x00001000 - thread is in a suspend equivalent state (return true) 523 // 0x00002000 - thread is native and walkable (return true) 524 // 0x00004000 - thread is native_trans and walkable (needed retry) 525 // 526 // set in wait_for_ext_suspend_completion(): 527 // 0x00010000 - routine was entered 528 // 0x00020000 - suspend request cancelled before loop (return false) 529 // 0x00040000 - thread suspended before loop (return true) 530 // 0x00080000 - suspend request cancelled in loop (return false) 531 // 0x00100000 - thread suspended in loop (return true) 532 // 0x00200000 - suspend not completed during retry loop (return false) 533 534 // Helper class for tracing suspend wait debug bits. 535 // 536 // 0x00000100 indicates that the target thread exited before it could 537 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 538 // 0x00080000 each indicate a cancelled suspend request so they don't 539 // count as wait failures either. 540 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 541 542 class TraceSuspendDebugBits : public StackObj { 543 private: 544 JavaThread * jt; 545 bool is_wait; 546 bool called_by_wait; // meaningful when !is_wait 547 uint32_t * bits; 548 549 public: 550 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 551 uint32_t *_bits) { 552 jt = _jt; 553 is_wait = _is_wait; 554 called_by_wait = _called_by_wait; 555 bits = _bits; 556 } 557 558 ~TraceSuspendDebugBits() { 559 if (!is_wait) { 560 #if 1 561 // By default, don't trace bits for is_ext_suspend_completed() calls. 562 // That trace is very chatty. 563 return; 564 #else 565 if (!called_by_wait) { 566 // If tracing for is_ext_suspend_completed() is enabled, then only 567 // trace calls to it from wait_for_ext_suspend_completion() 568 return; 569 } 570 #endif 571 } 572 573 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 574 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 575 MutexLocker ml(Threads_lock); // needed for get_thread_name() 576 ResourceMark rm; 577 578 tty->print_cr( 579 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 580 jt->get_thread_name(), *bits); 581 582 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 583 } 584 } 585 } 586 }; 587 #undef DEBUG_FALSE_BITS 588 589 590 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 591 uint32_t *bits) { 592 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 593 594 bool did_trans_retry = false; // only do thread_in_native_trans retry once 595 bool do_trans_retry; // flag to force the retry 596 597 *bits |= 0x00000001; 598 599 do { 600 do_trans_retry = false; 601 602 if (is_exiting()) { 603 // Thread is in the process of exiting. This is always checked 604 // first to reduce the risk of dereferencing a freed JavaThread. 605 *bits |= 0x00000100; 606 return false; 607 } 608 609 if (!is_external_suspend()) { 610 // Suspend request is cancelled. This is always checked before 611 // is_ext_suspended() to reduce the risk of a rogue resume 612 // confusing the thread that made the suspend request. 613 *bits |= 0x00000200; 614 return false; 615 } 616 617 if (is_ext_suspended()) { 618 // thread is suspended 619 *bits |= 0x00000400; 620 return true; 621 } 622 623 // Now that we no longer do hard suspends of threads running 624 // native code, the target thread can be changing thread state 625 // while we are in this routine: 626 // 627 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 628 // 629 // We save a copy of the thread state as observed at this moment 630 // and make our decision about suspend completeness based on the 631 // copy. This closes the race where the thread state is seen as 632 // _thread_in_native_trans in the if-thread_blocked check, but is 633 // seen as _thread_blocked in if-thread_in_native_trans check. 634 JavaThreadState save_state = thread_state(); 635 636 if (save_state == _thread_blocked && is_suspend_equivalent()) { 637 // If the thread's state is _thread_blocked and this blocking 638 // condition is known to be equivalent to a suspend, then we can 639 // consider the thread to be externally suspended. This means that 640 // the code that sets _thread_blocked has been modified to do 641 // self-suspension if the blocking condition releases. We also 642 // used to check for CONDVAR_WAIT here, but that is now covered by 643 // the _thread_blocked with self-suspension check. 644 // 645 // Return true since we wouldn't be here unless there was still an 646 // external suspend request. 647 *bits |= 0x00001000; 648 return true; 649 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 650 // Threads running native code will self-suspend on native==>VM/Java 651 // transitions. If its stack is walkable (should always be the case 652 // unless this function is called before the actual java_suspend() 653 // call), then the wait is done. 654 *bits |= 0x00002000; 655 return true; 656 } else if (!called_by_wait && !did_trans_retry && 657 save_state == _thread_in_native_trans && 658 frame_anchor()->walkable()) { 659 // The thread is transitioning from thread_in_native to another 660 // thread state. check_safepoint_and_suspend_for_native_trans() 661 // will force the thread to self-suspend. If it hasn't gotten 662 // there yet we may have caught the thread in-between the native 663 // code check above and the self-suspend. Lucky us. If we were 664 // called by wait_for_ext_suspend_completion(), then it 665 // will be doing the retries so we don't have to. 666 // 667 // Since we use the saved thread state in the if-statement above, 668 // there is a chance that the thread has already transitioned to 669 // _thread_blocked by the time we get here. In that case, we will 670 // make a single unnecessary pass through the logic below. This 671 // doesn't hurt anything since we still do the trans retry. 672 673 *bits |= 0x00004000; 674 675 // Once the thread leaves thread_in_native_trans for another 676 // thread state, we break out of this retry loop. We shouldn't 677 // need this flag to prevent us from getting back here, but 678 // sometimes paranoia is good. 679 did_trans_retry = true; 680 681 // We wait for the thread to transition to a more usable state. 682 for (int i = 1; i <= SuspendRetryCount; i++) { 683 // We used to do an "os::yield_all(i)" call here with the intention 684 // that yielding would increase on each retry. However, the parameter 685 // is ignored on Linux which means the yield didn't scale up. Waiting 686 // on the SR_lock below provides a much more predictable scale up for 687 // the delay. It also provides a simple/direct point to check for any 688 // safepoint requests from the VMThread 689 690 // temporarily drops SR_lock while doing wait with safepoint check 691 // (if we're a JavaThread - the WatcherThread can also call this) 692 // and increase delay with each retry 693 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 694 695 // check the actual thread state instead of what we saved above 696 if (thread_state() != _thread_in_native_trans) { 697 // the thread has transitioned to another thread state so 698 // try all the checks (except this one) one more time. 699 do_trans_retry = true; 700 break; 701 } 702 } // end retry loop 703 704 705 } 706 } while (do_trans_retry); 707 708 *bits |= 0x00000010; 709 return false; 710 } 711 712 // Wait for an external suspend request to complete (or be cancelled). 713 // Returns true if the thread is externally suspended and false otherwise. 714 // 715 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 716 uint32_t *bits) { 717 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 718 false /* !called_by_wait */, bits); 719 720 // local flag copies to minimize SR_lock hold time 721 bool is_suspended; 722 bool pending; 723 uint32_t reset_bits; 724 725 // set a marker so is_ext_suspend_completed() knows we are the caller 726 *bits |= 0x00010000; 727 728 // We use reset_bits to reinitialize the bits value at the top of 729 // each retry loop. This allows the caller to make use of any 730 // unused bits for their own marking purposes. 731 reset_bits = *bits; 732 733 { 734 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 735 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 736 delay, bits); 737 pending = is_external_suspend(); 738 } 739 // must release SR_lock to allow suspension to complete 740 741 if (!pending) { 742 // A cancelled suspend request is the only false return from 743 // is_ext_suspend_completed() that keeps us from entering the 744 // retry loop. 745 *bits |= 0x00020000; 746 return false; 747 } 748 749 if (is_suspended) { 750 *bits |= 0x00040000; 751 return true; 752 } 753 754 for (int i = 1; i <= retries; i++) { 755 *bits = reset_bits; // reinit to only track last retry 756 757 // We used to do an "os::yield_all(i)" call here with the intention 758 // that yielding would increase on each retry. However, the parameter 759 // is ignored on Linux which means the yield didn't scale up. Waiting 760 // on the SR_lock below provides a much more predictable scale up for 761 // the delay. It also provides a simple/direct point to check for any 762 // safepoint requests from the VMThread 763 764 { 765 MutexLocker ml(SR_lock()); 766 // wait with safepoint check (if we're a JavaThread - the WatcherThread 767 // can also call this) and increase delay with each retry 768 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 769 770 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 771 delay, bits); 772 773 // It is possible for the external suspend request to be cancelled 774 // (by a resume) before the actual suspend operation is completed. 775 // Refresh our local copy to see if we still need to wait. 776 pending = is_external_suspend(); 777 } 778 779 if (!pending) { 780 // A cancelled suspend request is the only false return from 781 // is_ext_suspend_completed() that keeps us from staying in the 782 // retry loop. 783 *bits |= 0x00080000; 784 return false; 785 } 786 787 if (is_suspended) { 788 *bits |= 0x00100000; 789 return true; 790 } 791 } // end retry loop 792 793 // thread did not suspend after all our retries 794 *bits |= 0x00200000; 795 return false; 796 } 797 798 // Called from API entry points which perform stack walking. If the 799 // associated JavaThread is the current thread, then wait_for_suspend 800 // is not used. Otherwise, it determines if we should wait for the 801 // "other" thread to complete external suspension. (NOTE: in future 802 // releases the suspension mechanism should be reimplemented so this 803 // is not necessary.) 804 // 805 bool 806 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 807 if (this != JavaThread::current()) { 808 // "other" threads require special handling. 809 if (wait_for_suspend) { 810 // We are allowed to wait for the external suspend to complete 811 // so give the other thread a chance to get suspended. 812 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 813 SuspendRetryDelay, bits)) { 814 // Didn't make it so let the caller know. 815 return false; 816 } 817 } 818 // We aren't allowed to wait for the external suspend to complete 819 // so if the other thread isn't externally suspended we need to 820 // let the caller know. 821 else if (!is_ext_suspend_completed_with_lock(bits)) { 822 return false; 823 } 824 } 825 826 return true; 827 } 828 829 #ifndef PRODUCT 830 void JavaThread::record_jump(address target, address instr, const char* file, 831 int line) { 832 833 // This should not need to be atomic as the only way for simultaneous 834 // updates is via interrupts. Even then this should be rare or non-existent 835 // and we don't care that much anyway. 836 837 int index = _jmp_ring_index; 838 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 839 _jmp_ring[index]._target = (intptr_t) target; 840 _jmp_ring[index]._instruction = (intptr_t) instr; 841 _jmp_ring[index]._file = file; 842 _jmp_ring[index]._line = line; 843 } 844 #endif // PRODUCT 845 846 void Thread::interrupt(Thread* thread) { 847 debug_only(check_for_dangling_thread_pointer(thread);) 848 os::interrupt(thread); 849 } 850 851 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 852 debug_only(check_for_dangling_thread_pointer(thread);) 853 // Note: If clear_interrupted==false, this simply fetches and 854 // returns the value of the field osthread()->interrupted(). 855 return os::is_interrupted(thread, clear_interrupted); 856 } 857 858 859 // GC Support 860 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 861 int thread_parity = _oops_do_parity; 862 if (thread_parity != strong_roots_parity) { 863 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 864 if (res == thread_parity) { 865 return true; 866 } else { 867 guarantee(res == strong_roots_parity, "Or else what?"); 868 return false; 869 } 870 } 871 return false; 872 } 873 874 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 875 active_handles()->oops_do(f); 876 // Do oop for ThreadShadow 877 f->do_oop((oop*)&_pending_exception); 878 handle_area()->oops_do(f); 879 880 // We scan thread local monitor lists here, and the remaining global 881 // monitors in ObjectSynchronizer::oops_do(). 882 ObjectSynchronizer::thread_local_used_oops_do(this, f); 883 } 884 885 void Thread::metadata_handles_do(void f(Metadata*)) { 886 // Only walk the Handles in Thread. 887 if (metadata_handles() != NULL) { 888 for (int i = 0; i< metadata_handles()->length(); i++) { 889 f(metadata_handles()->at(i)); 890 } 891 } 892 } 893 894 void Thread::print_on(outputStream* st, bool print_extended_info) const { 895 // get_priority assumes osthread initialized 896 if (osthread() != NULL) { 897 int os_prio; 898 if (os::get_native_priority(this, &os_prio) == OS_OK) { 899 st->print("os_prio=%d ", os_prio); 900 } 901 902 st->print("cpu=%.2fms ", 903 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 904 ); 905 st->print("elapsed=%.2fs ", 906 _statistical_info.getElapsedTime() / 1000.0 907 ); 908 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 909 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 910 st->print("allocated=" SIZE_FORMAT "%s ", 911 byte_size_in_proper_unit(allocated_bytes), 912 proper_unit_for_byte_size(allocated_bytes) 913 ); 914 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 915 } 916 917 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 918 osthread()->print_on(st); 919 } 920 ThreadsSMRSupport::print_info_on(this, st); 921 st->print(" "); 922 debug_only(if (WizardMode) print_owned_locks_on(st);) 923 } 924 925 // Thread::print_on_error() is called by fatal error handler. Don't use 926 // any lock or allocate memory. 927 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 928 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 929 930 if (is_VM_thread()) { st->print("VMThread"); } 931 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 932 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 933 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 934 else { st->print("Thread"); } 935 936 if (is_Named_thread()) { 937 st->print(" \"%s\"", name()); 938 } 939 940 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 941 p2i(stack_end()), p2i(stack_base())); 942 943 if (osthread()) { 944 st->print(" [id=%d]", osthread()->thread_id()); 945 } 946 947 ThreadsSMRSupport::print_info_on(this, st); 948 } 949 950 void Thread::print_value_on(outputStream* st) const { 951 if (is_Named_thread()) { 952 st->print(" \"%s\" ", name()); 953 } 954 st->print(INTPTR_FORMAT, p2i(this)); // print address 955 } 956 957 #ifdef ASSERT 958 void Thread::print_owned_locks_on(outputStream* st) const { 959 Monitor *cur = _owned_locks; 960 if (cur == NULL) { 961 st->print(" (no locks) "); 962 } else { 963 st->print_cr(" Locks owned:"); 964 while (cur) { 965 cur->print_on(st); 966 cur = cur->next(); 967 } 968 } 969 } 970 971 static int ref_use_count = 0; 972 973 bool Thread::owns_locks_but_compiled_lock() const { 974 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 975 if (cur != Compile_lock) return true; 976 } 977 return false; 978 } 979 980 981 #endif 982 983 #ifndef PRODUCT 984 985 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 986 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 987 // no locks which allow_vm_block's are held 988 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 989 // Check if current thread is allowed to block at a safepoint 990 if (!(_allow_safepoint_count == 0)) { 991 fatal("Possible safepoint reached by thread that does not allow it"); 992 } 993 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 994 fatal("LEAF method calling lock?"); 995 } 996 997 #ifdef ASSERT 998 if (potential_vm_operation && is_Java_thread() 999 && !Universe::is_bootstrapping()) { 1000 // Make sure we do not hold any locks that the VM thread also uses. 1001 // This could potentially lead to deadlocks 1002 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1003 // Threads_lock is special, since the safepoint synchronization will not start before this is 1004 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1005 // since it is used to transfer control between JavaThreads and the VMThread 1006 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1007 if ((cur->allow_vm_block() && 1008 cur != Threads_lock && 1009 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1010 cur != VMOperationRequest_lock && 1011 cur != VMOperationQueue_lock) || 1012 cur->rank() == Mutex::special) { 1013 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1014 } 1015 } 1016 } 1017 1018 if (GCALotAtAllSafepoints) { 1019 // We could enter a safepoint here and thus have a gc 1020 InterfaceSupport::check_gc_alot(); 1021 } 1022 #endif 1023 } 1024 #endif 1025 1026 bool Thread::is_in_stack(address adr) const { 1027 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1028 address end = os::current_stack_pointer(); 1029 // Allow non Java threads to call this without stack_base 1030 if (_stack_base == NULL) return true; 1031 if (stack_base() >= adr && adr >= end) return true; 1032 1033 return false; 1034 } 1035 1036 bool Thread::is_in_usable_stack(address adr) const { 1037 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1038 size_t usable_stack_size = _stack_size - stack_guard_size; 1039 1040 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1041 } 1042 1043 1044 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1045 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1046 // used for compilation in the future. If that change is made, the need for these methods 1047 // should be revisited, and they should be removed if possible. 1048 1049 bool Thread::is_lock_owned(address adr) const { 1050 return on_local_stack(adr); 1051 } 1052 1053 bool Thread::set_as_starting_thread() { 1054 // NOTE: this must be called inside the main thread. 1055 return os::create_main_thread((JavaThread*)this); 1056 } 1057 1058 static void initialize_class(Symbol* class_name, TRAPS) { 1059 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1060 InstanceKlass::cast(klass)->initialize(CHECK); 1061 } 1062 1063 1064 // Creates the initial ThreadGroup 1065 static Handle create_initial_thread_group(TRAPS) { 1066 Handle system_instance = JavaCalls::construct_new_instance( 1067 SystemDictionary::ThreadGroup_klass(), 1068 vmSymbols::void_method_signature(), 1069 CHECK_NH); 1070 Universe::set_system_thread_group(system_instance()); 1071 1072 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1073 Handle main_instance = JavaCalls::construct_new_instance( 1074 SystemDictionary::ThreadGroup_klass(), 1075 vmSymbols::threadgroup_string_void_signature(), 1076 system_instance, 1077 string, 1078 CHECK_NH); 1079 return main_instance; 1080 } 1081 1082 // Creates the initial Thread 1083 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1084 TRAPS) { 1085 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1086 assert(ik->is_initialized(), "must be"); 1087 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1088 1089 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1090 // constructor calls Thread.current(), which must be set here for the 1091 // initial thread. 1092 java_lang_Thread::set_thread(thread_oop(), thread); 1093 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1094 thread->set_threadObj(thread_oop()); 1095 1096 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1097 1098 JavaValue result(T_VOID); 1099 JavaCalls::call_special(&result, thread_oop, 1100 ik, 1101 vmSymbols::object_initializer_name(), 1102 vmSymbols::threadgroup_string_void_signature(), 1103 thread_group, 1104 string, 1105 CHECK_NULL); 1106 return thread_oop(); 1107 } 1108 1109 char java_runtime_name[128] = ""; 1110 char java_runtime_version[128] = ""; 1111 1112 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1113 static const char* get_java_runtime_name(TRAPS) { 1114 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1115 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1116 fieldDescriptor fd; 1117 bool found = k != NULL && 1118 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1119 vmSymbols::string_signature(), &fd); 1120 if (found) { 1121 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1122 if (name_oop == NULL) { 1123 return NULL; 1124 } 1125 const char* name = java_lang_String::as_utf8_string(name_oop, 1126 java_runtime_name, 1127 sizeof(java_runtime_name)); 1128 return name; 1129 } else { 1130 return NULL; 1131 } 1132 } 1133 1134 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1135 static const char* get_java_runtime_version(TRAPS) { 1136 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1137 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1138 fieldDescriptor fd; 1139 bool found = k != NULL && 1140 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1141 vmSymbols::string_signature(), &fd); 1142 if (found) { 1143 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1144 if (name_oop == NULL) { 1145 return NULL; 1146 } 1147 const char* name = java_lang_String::as_utf8_string(name_oop, 1148 java_runtime_version, 1149 sizeof(java_runtime_version)); 1150 return name; 1151 } else { 1152 return NULL; 1153 } 1154 } 1155 1156 // General purpose hook into Java code, run once when the VM is initialized. 1157 // The Java library method itself may be changed independently from the VM. 1158 static void call_postVMInitHook(TRAPS) { 1159 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1160 if (klass != NULL) { 1161 JavaValue result(T_VOID); 1162 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1163 vmSymbols::void_method_signature(), 1164 CHECK); 1165 } 1166 } 1167 1168 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1169 bool daemon, TRAPS) { 1170 assert(thread_group.not_null(), "thread group should be specified"); 1171 assert(threadObj() == NULL, "should only create Java thread object once"); 1172 1173 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1174 assert(ik->is_initialized(), "must be"); 1175 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1176 1177 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1178 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1179 // constructor calls Thread.current(), which must be set here. 1180 java_lang_Thread::set_thread(thread_oop(), this); 1181 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1182 set_threadObj(thread_oop()); 1183 1184 JavaValue result(T_VOID); 1185 if (thread_name != NULL) { 1186 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1187 // Thread gets assigned specified name and null target 1188 JavaCalls::call_special(&result, 1189 thread_oop, 1190 ik, 1191 vmSymbols::object_initializer_name(), 1192 vmSymbols::threadgroup_string_void_signature(), 1193 thread_group, 1194 name, 1195 THREAD); 1196 } else { 1197 // Thread gets assigned name "Thread-nnn" and null target 1198 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1199 JavaCalls::call_special(&result, 1200 thread_oop, 1201 ik, 1202 vmSymbols::object_initializer_name(), 1203 vmSymbols::threadgroup_runnable_void_signature(), 1204 thread_group, 1205 Handle(), 1206 THREAD); 1207 } 1208 1209 1210 if (daemon) { 1211 java_lang_Thread::set_daemon(thread_oop()); 1212 } 1213 1214 if (HAS_PENDING_EXCEPTION) { 1215 return; 1216 } 1217 1218 Klass* group = SystemDictionary::ThreadGroup_klass(); 1219 Handle threadObj(THREAD, this->threadObj()); 1220 1221 JavaCalls::call_special(&result, 1222 thread_group, 1223 group, 1224 vmSymbols::add_method_name(), 1225 vmSymbols::thread_void_signature(), 1226 threadObj, // Arg 1 1227 THREAD); 1228 } 1229 1230 // List of all NonJavaThreads and safe iteration over that list. 1231 1232 class NonJavaThread::List { 1233 public: 1234 NonJavaThread* volatile _head; 1235 SingleWriterSynchronizer _protect; 1236 1237 List() : _head(NULL), _protect() {} 1238 }; 1239 1240 NonJavaThread::List NonJavaThread::_the_list; 1241 1242 NonJavaThread::Iterator::Iterator() : 1243 _protect_enter(_the_list._protect.enter()), 1244 _current(OrderAccess::load_acquire(&_the_list._head)) 1245 {} 1246 1247 NonJavaThread::Iterator::~Iterator() { 1248 _the_list._protect.exit(_protect_enter); 1249 } 1250 1251 void NonJavaThread::Iterator::step() { 1252 assert(!end(), "precondition"); 1253 _current = OrderAccess::load_acquire(&_current->_next); 1254 } 1255 1256 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1257 // Add this thread to _the_list. 1258 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1259 _next = _the_list._head; 1260 OrderAccess::release_store(&_the_list._head, this); 1261 } 1262 1263 NonJavaThread::~NonJavaThread() { 1264 JFR_ONLY(Jfr::on_thread_exit(this);) 1265 // Remove this thread from _the_list. 1266 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1267 NonJavaThread* volatile* p = &_the_list._head; 1268 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1269 if (t == this) { 1270 *p = this->_next; 1271 // Wait for any in-progress iterators. 1272 _the_list._protect.synchronize(); 1273 break; 1274 } 1275 } 1276 } 1277 1278 // NamedThread -- non-JavaThread subclasses with multiple 1279 // uniquely named instances should derive from this. 1280 NamedThread::NamedThread() : 1281 NonJavaThread(), 1282 _name(NULL), 1283 _processed_thread(NULL), 1284 _gc_id(GCId::undefined()) 1285 {} 1286 1287 NamedThread::~NamedThread() { 1288 if (_name != NULL) { 1289 FREE_C_HEAP_ARRAY(char, _name); 1290 _name = NULL; 1291 } 1292 } 1293 1294 void NamedThread::set_name(const char* format, ...) { 1295 guarantee(_name == NULL, "Only get to set name once."); 1296 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1297 guarantee(_name != NULL, "alloc failure"); 1298 va_list ap; 1299 va_start(ap, format); 1300 jio_vsnprintf(_name, max_name_len, format, ap); 1301 va_end(ap); 1302 } 1303 1304 void NamedThread::initialize_named_thread() { 1305 set_native_thread_name(name()); 1306 } 1307 1308 void NamedThread::print_on(outputStream* st) const { 1309 st->print("\"%s\" ", name()); 1310 Thread::print_on(st); 1311 st->cr(); 1312 } 1313 1314 1315 // ======= WatcherThread ======== 1316 1317 // The watcher thread exists to simulate timer interrupts. It should 1318 // be replaced by an abstraction over whatever native support for 1319 // timer interrupts exists on the platform. 1320 1321 WatcherThread* WatcherThread::_watcher_thread = NULL; 1322 bool WatcherThread::_startable = false; 1323 volatile bool WatcherThread::_should_terminate = false; 1324 1325 WatcherThread::WatcherThread() : NonJavaThread() { 1326 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1327 if (os::create_thread(this, os::watcher_thread)) { 1328 _watcher_thread = this; 1329 1330 // Set the watcher thread to the highest OS priority which should not be 1331 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1332 // is created. The only normal thread using this priority is the reference 1333 // handler thread, which runs for very short intervals only. 1334 // If the VMThread's priority is not lower than the WatcherThread profiling 1335 // will be inaccurate. 1336 os::set_priority(this, MaxPriority); 1337 if (!DisableStartThread) { 1338 os::start_thread(this); 1339 } 1340 } 1341 } 1342 1343 int WatcherThread::sleep() const { 1344 // The WatcherThread does not participate in the safepoint protocol 1345 // for the PeriodicTask_lock because it is not a JavaThread. 1346 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1347 1348 if (_should_terminate) { 1349 // check for termination before we do any housekeeping or wait 1350 return 0; // we did not sleep. 1351 } 1352 1353 // remaining will be zero if there are no tasks, 1354 // causing the WatcherThread to sleep until a task is 1355 // enrolled 1356 int remaining = PeriodicTask::time_to_wait(); 1357 int time_slept = 0; 1358 1359 // we expect this to timeout - we only ever get unparked when 1360 // we should terminate or when a new task has been enrolled 1361 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1362 1363 jlong time_before_loop = os::javaTimeNanos(); 1364 1365 while (true) { 1366 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1367 remaining); 1368 jlong now = os::javaTimeNanos(); 1369 1370 if (remaining == 0) { 1371 // if we didn't have any tasks we could have waited for a long time 1372 // consider the time_slept zero and reset time_before_loop 1373 time_slept = 0; 1374 time_before_loop = now; 1375 } else { 1376 // need to recalculate since we might have new tasks in _tasks 1377 time_slept = (int) ((now - time_before_loop) / 1000000); 1378 } 1379 1380 // Change to task list or spurious wakeup of some kind 1381 if (timedout || _should_terminate) { 1382 break; 1383 } 1384 1385 remaining = PeriodicTask::time_to_wait(); 1386 if (remaining == 0) { 1387 // Last task was just disenrolled so loop around and wait until 1388 // another task gets enrolled 1389 continue; 1390 } 1391 1392 remaining -= time_slept; 1393 if (remaining <= 0) { 1394 break; 1395 } 1396 } 1397 1398 return time_slept; 1399 } 1400 1401 void WatcherThread::run() { 1402 assert(this == watcher_thread(), "just checking"); 1403 1404 this->set_native_thread_name(this->name()); 1405 this->set_active_handles(JNIHandleBlock::allocate_block()); 1406 while (true) { 1407 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1408 assert(watcher_thread() == this, "thread consistency check"); 1409 1410 // Calculate how long it'll be until the next PeriodicTask work 1411 // should be done, and sleep that amount of time. 1412 int time_waited = sleep(); 1413 1414 if (VMError::is_error_reported()) { 1415 // A fatal error has happened, the error handler(VMError::report_and_die) 1416 // should abort JVM after creating an error log file. However in some 1417 // rare cases, the error handler itself might deadlock. Here periodically 1418 // check for error reporting timeouts, and if it happens, just proceed to 1419 // abort the VM. 1420 1421 // This code is in WatcherThread because WatcherThread wakes up 1422 // periodically so the fatal error handler doesn't need to do anything; 1423 // also because the WatcherThread is less likely to crash than other 1424 // threads. 1425 1426 for (;;) { 1427 // Note: we use naked sleep in this loop because we want to avoid using 1428 // any kind of VM infrastructure which may be broken at this point. 1429 if (VMError::check_timeout()) { 1430 // We hit error reporting timeout. Error reporting was interrupted and 1431 // will be wrapping things up now (closing files etc). Give it some more 1432 // time, then quit the VM. 1433 os::naked_short_sleep(200); 1434 // Print a message to stderr. 1435 fdStream err(defaultStream::output_fd()); 1436 err.print_raw_cr("# [ timer expired, abort... ]"); 1437 // skip atexit/vm_exit/vm_abort hooks 1438 os::die(); 1439 } 1440 1441 // Wait a second, then recheck for timeout. 1442 os::naked_short_sleep(999); 1443 } 1444 } 1445 1446 if (_should_terminate) { 1447 // check for termination before posting the next tick 1448 break; 1449 } 1450 1451 PeriodicTask::real_time_tick(time_waited); 1452 } 1453 1454 // Signal that it is terminated 1455 { 1456 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1457 _watcher_thread = NULL; 1458 Terminator_lock->notify(); 1459 } 1460 } 1461 1462 void WatcherThread::start() { 1463 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1464 1465 if (watcher_thread() == NULL && _startable) { 1466 _should_terminate = false; 1467 // Create the single instance of WatcherThread 1468 new WatcherThread(); 1469 } 1470 } 1471 1472 void WatcherThread::make_startable() { 1473 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1474 _startable = true; 1475 } 1476 1477 void WatcherThread::stop() { 1478 { 1479 // Follow normal safepoint aware lock enter protocol since the 1480 // WatcherThread is stopped by another JavaThread. 1481 MutexLocker ml(PeriodicTask_lock); 1482 _should_terminate = true; 1483 1484 WatcherThread* watcher = watcher_thread(); 1485 if (watcher != NULL) { 1486 // unpark the WatcherThread so it can see that it should terminate 1487 watcher->unpark(); 1488 } 1489 } 1490 1491 MutexLocker mu(Terminator_lock); 1492 1493 while (watcher_thread() != NULL) { 1494 // This wait should make safepoint checks, wait without a timeout, 1495 // and wait as a suspend-equivalent condition. 1496 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1497 Mutex::_as_suspend_equivalent_flag); 1498 } 1499 } 1500 1501 void WatcherThread::unpark() { 1502 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1503 PeriodicTask_lock->notify(); 1504 } 1505 1506 void WatcherThread::print_on(outputStream* st) const { 1507 st->print("\"%s\" ", name()); 1508 Thread::print_on(st); 1509 st->cr(); 1510 } 1511 1512 // ======= JavaThread ======== 1513 1514 #if INCLUDE_JVMCI 1515 1516 jlong* JavaThread::_jvmci_old_thread_counters; 1517 1518 bool jvmci_counters_include(JavaThread* thread) { 1519 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1520 } 1521 1522 void JavaThread::collect_counters(typeArrayOop array) { 1523 if (JVMCICounterSize > 0) { 1524 JavaThreadIteratorWithHandle jtiwh; 1525 for (int i = 0; i < array->length(); i++) { 1526 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1527 } 1528 for (; JavaThread *tp = jtiwh.next(); ) { 1529 if (jvmci_counters_include(tp)) { 1530 for (int i = 0; i < array->length(); i++) { 1531 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1532 } 1533 } 1534 } 1535 } 1536 } 1537 1538 #endif // INCLUDE_JVMCI 1539 1540 // A JavaThread is a normal Java thread 1541 1542 void JavaThread::initialize() { 1543 // Initialize fields 1544 1545 set_saved_exception_pc(NULL); 1546 set_threadObj(NULL); 1547 _anchor.clear(); 1548 set_entry_point(NULL); 1549 set_jni_functions(jni_functions()); 1550 set_callee_target(NULL); 1551 set_vm_result(NULL); 1552 set_vm_result_2(NULL); 1553 set_vframe_array_head(NULL); 1554 set_vframe_array_last(NULL); 1555 set_deferred_locals(NULL); 1556 set_deopt_mark(NULL); 1557 set_deopt_compiled_method(NULL); 1558 clear_must_deopt_id(); 1559 set_monitor_chunks(NULL); 1560 set_next(NULL); 1561 _on_thread_list = false; 1562 set_thread_state(_thread_new); 1563 _terminated = _not_terminated; 1564 _array_for_gc = NULL; 1565 _suspend_equivalent = false; 1566 _in_deopt_handler = 0; 1567 _doing_unsafe_access = false; 1568 _stack_guard_state = stack_guard_unused; 1569 #if INCLUDE_JVMCI 1570 _pending_monitorenter = false; 1571 _pending_deoptimization = -1; 1572 _pending_failed_speculation = 0; 1573 _pending_transfer_to_interpreter = false; 1574 _adjusting_comp_level = false; 1575 _in_retryable_allocation = false; 1576 _jvmci._alternate_call_target = NULL; 1577 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1578 if (JVMCICounterSize > 0) { 1579 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1580 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1581 } else { 1582 _jvmci_counters = NULL; 1583 } 1584 #endif // INCLUDE_JVMCI 1585 _reserved_stack_activation = NULL; // stack base not known yet 1586 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1587 _exception_pc = 0; 1588 _exception_handler_pc = 0; 1589 _is_method_handle_return = 0; 1590 _jvmti_thread_state= NULL; 1591 _should_post_on_exceptions_flag = JNI_FALSE; 1592 _interp_only_mode = 0; 1593 _special_runtime_exit_condition = _no_async_condition; 1594 _pending_async_exception = NULL; 1595 _thread_stat = NULL; 1596 _thread_stat = new ThreadStatistics(); 1597 _blocked_on_compilation = false; 1598 _jni_active_critical = 0; 1599 _pending_jni_exception_check_fn = NULL; 1600 _do_not_unlock_if_synchronized = false; 1601 _cached_monitor_info = NULL; 1602 _parker = Parker::Allocate(this); 1603 1604 #ifndef PRODUCT 1605 _jmp_ring_index = 0; 1606 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1607 record_jump(NULL, NULL, NULL, 0); 1608 } 1609 #endif // PRODUCT 1610 1611 // Setup safepoint state info for this thread 1612 ThreadSafepointState::create(this); 1613 1614 debug_only(_java_call_counter = 0); 1615 1616 // JVMTI PopFrame support 1617 _popframe_condition = popframe_inactive; 1618 _popframe_preserved_args = NULL; 1619 _popframe_preserved_args_size = 0; 1620 _frames_to_pop_failed_realloc = 0; 1621 1622 if (SafepointMechanism::uses_thread_local_poll()) { 1623 SafepointMechanism::initialize_header(this); 1624 } 1625 1626 pd_initialize(); 1627 } 1628 1629 JavaThread::JavaThread(bool is_attaching_via_jni) : 1630 Thread() { 1631 initialize(); 1632 if (is_attaching_via_jni) { 1633 _jni_attach_state = _attaching_via_jni; 1634 } else { 1635 _jni_attach_state = _not_attaching_via_jni; 1636 } 1637 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1638 } 1639 1640 bool JavaThread::reguard_stack(address cur_sp) { 1641 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1642 && _stack_guard_state != stack_guard_reserved_disabled) { 1643 return true; // Stack already guarded or guard pages not needed. 1644 } 1645 1646 if (register_stack_overflow()) { 1647 // For those architectures which have separate register and 1648 // memory stacks, we must check the register stack to see if 1649 // it has overflowed. 1650 return false; 1651 } 1652 1653 // Java code never executes within the yellow zone: the latter is only 1654 // there to provoke an exception during stack banging. If java code 1655 // is executing there, either StackShadowPages should be larger, or 1656 // some exception code in c1, c2 or the interpreter isn't unwinding 1657 // when it should. 1658 guarantee(cur_sp > stack_reserved_zone_base(), 1659 "not enough space to reguard - increase StackShadowPages"); 1660 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1661 enable_stack_yellow_reserved_zone(); 1662 if (reserved_stack_activation() != stack_base()) { 1663 set_reserved_stack_activation(stack_base()); 1664 } 1665 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1666 set_reserved_stack_activation(stack_base()); 1667 enable_stack_reserved_zone(); 1668 } 1669 return true; 1670 } 1671 1672 bool JavaThread::reguard_stack(void) { 1673 return reguard_stack(os::current_stack_pointer()); 1674 } 1675 1676 1677 void JavaThread::block_if_vm_exited() { 1678 if (_terminated == _vm_exited) { 1679 // _vm_exited is set at safepoint, and Threads_lock is never released 1680 // we will block here forever 1681 Threads_lock->lock_without_safepoint_check(); 1682 ShouldNotReachHere(); 1683 } 1684 } 1685 1686 1687 // Remove this ifdef when C1 is ported to the compiler interface. 1688 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1689 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1690 1691 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1692 Thread() { 1693 initialize(); 1694 _jni_attach_state = _not_attaching_via_jni; 1695 set_entry_point(entry_point); 1696 // Create the native thread itself. 1697 // %note runtime_23 1698 os::ThreadType thr_type = os::java_thread; 1699 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1700 os::java_thread; 1701 os::create_thread(this, thr_type, stack_sz); 1702 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1703 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1704 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1705 // the exception consists of creating the exception object & initializing it, initialization 1706 // will leave the VM via a JavaCall and then all locks must be unlocked). 1707 // 1708 // The thread is still suspended when we reach here. Thread must be explicit started 1709 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1710 // by calling Threads:add. The reason why this is not done here, is because the thread 1711 // object must be fully initialized (take a look at JVM_Start) 1712 } 1713 1714 JavaThread::~JavaThread() { 1715 1716 // JSR166 -- return the parker to the free list 1717 Parker::Release(_parker); 1718 _parker = NULL; 1719 1720 // Free any remaining previous UnrollBlock 1721 vframeArray* old_array = vframe_array_last(); 1722 1723 if (old_array != NULL) { 1724 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1725 old_array->set_unroll_block(NULL); 1726 delete old_info; 1727 delete old_array; 1728 } 1729 1730 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1731 if (deferred != NULL) { 1732 // This can only happen if thread is destroyed before deoptimization occurs. 1733 assert(deferred->length() != 0, "empty array!"); 1734 do { 1735 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1736 deferred->remove_at(0); 1737 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1738 delete dlv; 1739 } while (deferred->length() != 0); 1740 delete deferred; 1741 } 1742 1743 // All Java related clean up happens in exit 1744 ThreadSafepointState::destroy(this); 1745 if (_thread_stat != NULL) delete _thread_stat; 1746 1747 #if INCLUDE_JVMCI 1748 if (JVMCICounterSize > 0) { 1749 if (jvmci_counters_include(this)) { 1750 for (int i = 0; i < JVMCICounterSize; i++) { 1751 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1752 } 1753 } 1754 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1755 } 1756 #endif // INCLUDE_JVMCI 1757 } 1758 1759 1760 // The first routine called by a new Java thread 1761 void JavaThread::run() { 1762 // initialize thread-local alloc buffer related fields 1763 this->initialize_tlab(); 1764 1765 // used to test validity of stack trace backs 1766 this->record_base_of_stack_pointer(); 1767 1768 this->create_stack_guard_pages(); 1769 1770 this->cache_global_variables(); 1771 1772 // Thread is now sufficient initialized to be handled by the safepoint code as being 1773 // in the VM. Change thread state from _thread_new to _thread_in_vm 1774 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1775 1776 assert(JavaThread::current() == this, "sanity check"); 1777 assert(!Thread::current()->owns_locks(), "sanity check"); 1778 1779 DTRACE_THREAD_PROBE(start, this); 1780 1781 // This operation might block. We call that after all safepoint checks for a new thread has 1782 // been completed. 1783 this->set_active_handles(JNIHandleBlock::allocate_block()); 1784 1785 if (JvmtiExport::should_post_thread_life()) { 1786 JvmtiExport::post_thread_start(this); 1787 1788 } 1789 1790 // We call another function to do the rest so we are sure that the stack addresses used 1791 // from there will be lower than the stack base just computed 1792 thread_main_inner(); 1793 1794 // Note, thread is no longer valid at this point! 1795 } 1796 1797 1798 void JavaThread::thread_main_inner() { 1799 assert(JavaThread::current() == this, "sanity check"); 1800 assert(this->threadObj() != NULL, "just checking"); 1801 1802 // Execute thread entry point unless this thread has a pending exception 1803 // or has been stopped before starting. 1804 // Note: Due to JVM_StopThread we can have pending exceptions already! 1805 if (!this->has_pending_exception() && 1806 !java_lang_Thread::is_stillborn(this->threadObj())) { 1807 { 1808 ResourceMark rm(this); 1809 this->set_native_thread_name(this->get_thread_name()); 1810 } 1811 HandleMark hm(this); 1812 this->entry_point()(this, this); 1813 } 1814 1815 DTRACE_THREAD_PROBE(stop, this); 1816 1817 this->exit(false); 1818 this->smr_delete(); 1819 } 1820 1821 1822 static void ensure_join(JavaThread* thread) { 1823 // We do not need to grab the Threads_lock, since we are operating on ourself. 1824 Handle threadObj(thread, thread->threadObj()); 1825 assert(threadObj.not_null(), "java thread object must exist"); 1826 ObjectLocker lock(threadObj, thread); 1827 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1828 thread->clear_pending_exception(); 1829 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1830 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1831 // Clear the native thread instance - this makes isAlive return false and allows the join() 1832 // to complete once we've done the notify_all below 1833 java_lang_Thread::set_thread(threadObj(), NULL); 1834 lock.notify_all(thread); 1835 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1836 thread->clear_pending_exception(); 1837 } 1838 1839 static bool is_daemon(oop threadObj) { 1840 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1841 } 1842 1843 // For any new cleanup additions, please check to see if they need to be applied to 1844 // cleanup_failed_attach_current_thread as well. 1845 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1846 assert(this == JavaThread::current(), "thread consistency check"); 1847 1848 elapsedTimer _timer_exit_phase1; 1849 elapsedTimer _timer_exit_phase2; 1850 elapsedTimer _timer_exit_phase3; 1851 elapsedTimer _timer_exit_phase4; 1852 1853 if (log_is_enabled(Debug, os, thread, timer)) { 1854 _timer_exit_phase1.start(); 1855 } 1856 1857 HandleMark hm(this); 1858 Handle uncaught_exception(this, this->pending_exception()); 1859 this->clear_pending_exception(); 1860 Handle threadObj(this, this->threadObj()); 1861 assert(threadObj.not_null(), "Java thread object should be created"); 1862 1863 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1864 { 1865 EXCEPTION_MARK; 1866 1867 CLEAR_PENDING_EXCEPTION; 1868 } 1869 if (!destroy_vm) { 1870 if (uncaught_exception.not_null()) { 1871 EXCEPTION_MARK; 1872 // Call method Thread.dispatchUncaughtException(). 1873 Klass* thread_klass = SystemDictionary::Thread_klass(); 1874 JavaValue result(T_VOID); 1875 JavaCalls::call_virtual(&result, 1876 threadObj, thread_klass, 1877 vmSymbols::dispatchUncaughtException_name(), 1878 vmSymbols::throwable_void_signature(), 1879 uncaught_exception, 1880 THREAD); 1881 if (HAS_PENDING_EXCEPTION) { 1882 ResourceMark rm(this); 1883 jio_fprintf(defaultStream::error_stream(), 1884 "\nException: %s thrown from the UncaughtExceptionHandler" 1885 " in thread \"%s\"\n", 1886 pending_exception()->klass()->external_name(), 1887 get_thread_name()); 1888 CLEAR_PENDING_EXCEPTION; 1889 } 1890 } 1891 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 1892 1893 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1894 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1895 // is deprecated anyhow. 1896 if (!is_Compiler_thread()) { 1897 int count = 3; 1898 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1899 EXCEPTION_MARK; 1900 JavaValue result(T_VOID); 1901 Klass* thread_klass = SystemDictionary::Thread_klass(); 1902 JavaCalls::call_virtual(&result, 1903 threadObj, thread_klass, 1904 vmSymbols::exit_method_name(), 1905 vmSymbols::void_method_signature(), 1906 THREAD); 1907 CLEAR_PENDING_EXCEPTION; 1908 } 1909 } 1910 // notify JVMTI 1911 if (JvmtiExport::should_post_thread_life()) { 1912 JvmtiExport::post_thread_end(this); 1913 } 1914 1915 // We have notified the agents that we are exiting, before we go on, 1916 // we must check for a pending external suspend request and honor it 1917 // in order to not surprise the thread that made the suspend request. 1918 while (true) { 1919 { 1920 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1921 if (!is_external_suspend()) { 1922 set_terminated(_thread_exiting); 1923 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 1924 break; 1925 } 1926 // Implied else: 1927 // Things get a little tricky here. We have a pending external 1928 // suspend request, but we are holding the SR_lock so we 1929 // can't just self-suspend. So we temporarily drop the lock 1930 // and then self-suspend. 1931 } 1932 1933 ThreadBlockInVM tbivm(this); 1934 java_suspend_self(); 1935 1936 // We're done with this suspend request, but we have to loop around 1937 // and check again. Eventually we will get SR_lock without a pending 1938 // external suspend request and will be able to mark ourselves as 1939 // exiting. 1940 } 1941 // no more external suspends are allowed at this point 1942 } else { 1943 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 1944 // before_exit() has already posted JVMTI THREAD_END events 1945 } 1946 1947 if (log_is_enabled(Debug, os, thread, timer)) { 1948 _timer_exit_phase1.stop(); 1949 _timer_exit_phase2.start(); 1950 } 1951 // Notify waiters on thread object. This has to be done after exit() is called 1952 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1953 // group should have the destroyed bit set before waiters are notified). 1954 ensure_join(this); 1955 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1956 1957 if (log_is_enabled(Debug, os, thread, timer)) { 1958 _timer_exit_phase2.stop(); 1959 _timer_exit_phase3.start(); 1960 } 1961 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1962 // held by this thread must be released. The spec does not distinguish 1963 // between JNI-acquired and regular Java monitors. We can only see 1964 // regular Java monitors here if monitor enter-exit matching is broken. 1965 // 1966 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1967 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1968 if (exit_type == jni_detach) { 1969 // Sanity check even though JNI DetachCurrentThread() would have 1970 // returned JNI_ERR if there was a Java frame. JavaThread exit 1971 // should be done executing Java code by the time we get here. 1972 assert(!this->has_last_Java_frame(), 1973 "should not have a Java frame when detaching or exiting"); 1974 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1975 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1976 } 1977 1978 // These things needs to be done while we are still a Java Thread. Make sure that thread 1979 // is in a consistent state, in case GC happens 1980 JFR_ONLY(Jfr::on_thread_exit(this);) 1981 1982 if (active_handles() != NULL) { 1983 JNIHandleBlock* block = active_handles(); 1984 set_active_handles(NULL); 1985 JNIHandleBlock::release_block(block); 1986 } 1987 1988 if (free_handle_block() != NULL) { 1989 JNIHandleBlock* block = free_handle_block(); 1990 set_free_handle_block(NULL); 1991 JNIHandleBlock::release_block(block); 1992 } 1993 1994 // These have to be removed while this is still a valid thread. 1995 remove_stack_guard_pages(); 1996 1997 if (UseTLAB) { 1998 tlab().retire(); 1999 } 2000 2001 if (JvmtiEnv::environments_might_exist()) { 2002 JvmtiExport::cleanup_thread(this); 2003 } 2004 2005 // We must flush any deferred card marks and other various GC barrier 2006 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2007 // before removing a thread from the list of active threads. 2008 BarrierSet::barrier_set()->on_thread_detach(this); 2009 2010 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2011 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2012 os::current_thread_id()); 2013 2014 if (log_is_enabled(Debug, os, thread, timer)) { 2015 _timer_exit_phase3.stop(); 2016 _timer_exit_phase4.start(); 2017 } 2018 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2019 Threads::remove(this); 2020 2021 if (log_is_enabled(Debug, os, thread, timer)) { 2022 _timer_exit_phase4.stop(); 2023 ResourceMark rm(this); 2024 log_debug(os, thread, timer)("name='%s'" 2025 ", exit-phase1=" JLONG_FORMAT 2026 ", exit-phase2=" JLONG_FORMAT 2027 ", exit-phase3=" JLONG_FORMAT 2028 ", exit-phase4=" JLONG_FORMAT, 2029 get_thread_name(), 2030 _timer_exit_phase1.milliseconds(), 2031 _timer_exit_phase2.milliseconds(), 2032 _timer_exit_phase3.milliseconds(), 2033 _timer_exit_phase4.milliseconds()); 2034 } 2035 } 2036 2037 void JavaThread::cleanup_failed_attach_current_thread() { 2038 if (active_handles() != NULL) { 2039 JNIHandleBlock* block = active_handles(); 2040 set_active_handles(NULL); 2041 JNIHandleBlock::release_block(block); 2042 } 2043 2044 if (free_handle_block() != NULL) { 2045 JNIHandleBlock* block = free_handle_block(); 2046 set_free_handle_block(NULL); 2047 JNIHandleBlock::release_block(block); 2048 } 2049 2050 // These have to be removed while this is still a valid thread. 2051 remove_stack_guard_pages(); 2052 2053 if (UseTLAB) { 2054 tlab().retire(); 2055 } 2056 2057 BarrierSet::barrier_set()->on_thread_detach(this); 2058 2059 Threads::remove(this); 2060 this->smr_delete(); 2061 } 2062 2063 JavaThread* JavaThread::active() { 2064 Thread* thread = Thread::current(); 2065 if (thread->is_Java_thread()) { 2066 return (JavaThread*) thread; 2067 } else { 2068 assert(thread->is_VM_thread(), "this must be a vm thread"); 2069 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2070 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2071 assert(ret->is_Java_thread(), "must be a Java thread"); 2072 return ret; 2073 } 2074 } 2075 2076 bool JavaThread::is_lock_owned(address adr) const { 2077 if (Thread::is_lock_owned(adr)) return true; 2078 2079 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2080 if (chunk->contains(adr)) return true; 2081 } 2082 2083 return false; 2084 } 2085 2086 2087 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2088 chunk->set_next(monitor_chunks()); 2089 set_monitor_chunks(chunk); 2090 } 2091 2092 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2093 guarantee(monitor_chunks() != NULL, "must be non empty"); 2094 if (monitor_chunks() == chunk) { 2095 set_monitor_chunks(chunk->next()); 2096 } else { 2097 MonitorChunk* prev = monitor_chunks(); 2098 while (prev->next() != chunk) prev = prev->next(); 2099 prev->set_next(chunk->next()); 2100 } 2101 } 2102 2103 // JVM support. 2104 2105 // Note: this function shouldn't block if it's called in 2106 // _thread_in_native_trans state (such as from 2107 // check_special_condition_for_native_trans()). 2108 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2109 2110 if (has_last_Java_frame() && has_async_condition()) { 2111 // If we are at a polling page safepoint (not a poll return) 2112 // then we must defer async exception because live registers 2113 // will be clobbered by the exception path. Poll return is 2114 // ok because the call we a returning from already collides 2115 // with exception handling registers and so there is no issue. 2116 // (The exception handling path kills call result registers but 2117 // this is ok since the exception kills the result anyway). 2118 2119 if (is_at_poll_safepoint()) { 2120 // if the code we are returning to has deoptimized we must defer 2121 // the exception otherwise live registers get clobbered on the 2122 // exception path before deoptimization is able to retrieve them. 2123 // 2124 RegisterMap map(this, false); 2125 frame caller_fr = last_frame().sender(&map); 2126 assert(caller_fr.is_compiled_frame(), "what?"); 2127 if (caller_fr.is_deoptimized_frame()) { 2128 log_info(exceptions)("deferred async exception at compiled safepoint"); 2129 return; 2130 } 2131 } 2132 } 2133 2134 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2135 if (condition == _no_async_condition) { 2136 // Conditions have changed since has_special_runtime_exit_condition() 2137 // was called: 2138 // - if we were here only because of an external suspend request, 2139 // then that was taken care of above (or cancelled) so we are done 2140 // - if we were here because of another async request, then it has 2141 // been cleared between the has_special_runtime_exit_condition() 2142 // and now so again we are done 2143 return; 2144 } 2145 2146 // Check for pending async. exception 2147 if (_pending_async_exception != NULL) { 2148 // Only overwrite an already pending exception, if it is not a threadDeath. 2149 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2150 2151 // We cannot call Exceptions::_throw(...) here because we cannot block 2152 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2153 2154 LogTarget(Info, exceptions) lt; 2155 if (lt.is_enabled()) { 2156 ResourceMark rm; 2157 LogStream ls(lt); 2158 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2159 if (has_last_Java_frame()) { 2160 frame f = last_frame(); 2161 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2162 } 2163 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2164 } 2165 _pending_async_exception = NULL; 2166 clear_has_async_exception(); 2167 } 2168 } 2169 2170 if (check_unsafe_error && 2171 condition == _async_unsafe_access_error && !has_pending_exception()) { 2172 condition = _no_async_condition; // done 2173 switch (thread_state()) { 2174 case _thread_in_vm: { 2175 JavaThread* THREAD = this; 2176 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2177 } 2178 case _thread_in_native: { 2179 ThreadInVMfromNative tiv(this); 2180 JavaThread* THREAD = this; 2181 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2182 } 2183 case _thread_in_Java: { 2184 ThreadInVMfromJava tiv(this); 2185 JavaThread* THREAD = this; 2186 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2187 } 2188 default: 2189 ShouldNotReachHere(); 2190 } 2191 } 2192 2193 assert(condition == _no_async_condition || has_pending_exception() || 2194 (!check_unsafe_error && condition == _async_unsafe_access_error), 2195 "must have handled the async condition, if no exception"); 2196 } 2197 2198 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2199 // 2200 // Check for pending external suspend. Internal suspend requests do 2201 // not use handle_special_runtime_exit_condition(). 2202 // If JNIEnv proxies are allowed, don't self-suspend if the target 2203 // thread is not the current thread. In older versions of jdbx, jdbx 2204 // threads could call into the VM with another thread's JNIEnv so we 2205 // can be here operating on behalf of a suspended thread (4432884). 2206 bool do_self_suspend = is_external_suspend_with_lock(); 2207 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2208 // 2209 // Because thread is external suspended the safepoint code will count 2210 // thread as at a safepoint. This can be odd because we can be here 2211 // as _thread_in_Java which would normally transition to _thread_blocked 2212 // at a safepoint. We would like to mark the thread as _thread_blocked 2213 // before calling java_suspend_self like all other callers of it but 2214 // we must then observe proper safepoint protocol. (We can't leave 2215 // _thread_blocked with a safepoint in progress). However we can be 2216 // here as _thread_in_native_trans so we can't use a normal transition 2217 // constructor/destructor pair because they assert on that type of 2218 // transition. We could do something like: 2219 // 2220 // JavaThreadState state = thread_state(); 2221 // set_thread_state(_thread_in_vm); 2222 // { 2223 // ThreadBlockInVM tbivm(this); 2224 // java_suspend_self() 2225 // } 2226 // set_thread_state(_thread_in_vm_trans); 2227 // if (safepoint) block; 2228 // set_thread_state(state); 2229 // 2230 // but that is pretty messy. Instead we just go with the way the 2231 // code has worked before and note that this is the only path to 2232 // java_suspend_self that doesn't put the thread in _thread_blocked 2233 // mode. 2234 2235 frame_anchor()->make_walkable(this); 2236 java_suspend_self(); 2237 2238 // We might be here for reasons in addition to the self-suspend request 2239 // so check for other async requests. 2240 } 2241 2242 if (check_asyncs) { 2243 check_and_handle_async_exceptions(); 2244 } 2245 2246 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2247 } 2248 2249 void JavaThread::send_thread_stop(oop java_throwable) { 2250 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2251 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2252 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2253 2254 // Do not throw asynchronous exceptions against the compiler thread 2255 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2256 if (!can_call_java()) return; 2257 2258 { 2259 // Actually throw the Throwable against the target Thread - however 2260 // only if there is no thread death exception installed already. 2261 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2262 // If the topmost frame is a runtime stub, then we are calling into 2263 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2264 // must deoptimize the caller before continuing, as the compiled exception handler table 2265 // may not be valid 2266 if (has_last_Java_frame()) { 2267 frame f = last_frame(); 2268 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2269 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2270 RegisterMap reg_map(this, UseBiasedLocking); 2271 frame compiled_frame = f.sender(®_map); 2272 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2273 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2274 } 2275 } 2276 } 2277 2278 // Set async. pending exception in thread. 2279 set_pending_async_exception(java_throwable); 2280 2281 if (log_is_enabled(Info, exceptions)) { 2282 ResourceMark rm; 2283 log_info(exceptions)("Pending Async. exception installed of type: %s", 2284 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2285 } 2286 // for AbortVMOnException flag 2287 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2288 } 2289 } 2290 2291 2292 // Interrupt thread so it will wake up from a potential wait() 2293 Thread::interrupt(this); 2294 } 2295 2296 // External suspension mechanism. 2297 // 2298 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2299 // to any VM_locks and it is at a transition 2300 // Self-suspension will happen on the transition out of the vm. 2301 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2302 // 2303 // Guarantees on return: 2304 // + Target thread will not execute any new bytecode (that's why we need to 2305 // force a safepoint) 2306 // + Target thread will not enter any new monitors 2307 // 2308 void JavaThread::java_suspend() { 2309 ThreadsListHandle tlh; 2310 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2311 return; 2312 } 2313 2314 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2315 if (!is_external_suspend()) { 2316 // a racing resume has cancelled us; bail out now 2317 return; 2318 } 2319 2320 // suspend is done 2321 uint32_t debug_bits = 0; 2322 // Warning: is_ext_suspend_completed() may temporarily drop the 2323 // SR_lock to allow the thread to reach a stable thread state if 2324 // it is currently in a transient thread state. 2325 if (is_ext_suspend_completed(false /* !called_by_wait */, 2326 SuspendRetryDelay, &debug_bits)) { 2327 return; 2328 } 2329 } 2330 2331 VM_ThreadSuspend vm_suspend; 2332 VMThread::execute(&vm_suspend); 2333 } 2334 2335 // Part II of external suspension. 2336 // A JavaThread self suspends when it detects a pending external suspend 2337 // request. This is usually on transitions. It is also done in places 2338 // where continuing to the next transition would surprise the caller, 2339 // e.g., monitor entry. 2340 // 2341 // Returns the number of times that the thread self-suspended. 2342 // 2343 // Note: DO NOT call java_suspend_self() when you just want to block current 2344 // thread. java_suspend_self() is the second stage of cooperative 2345 // suspension for external suspend requests and should only be used 2346 // to complete an external suspend request. 2347 // 2348 int JavaThread::java_suspend_self() { 2349 int ret = 0; 2350 2351 // we are in the process of exiting so don't suspend 2352 if (is_exiting()) { 2353 clear_external_suspend(); 2354 return ret; 2355 } 2356 2357 assert(_anchor.walkable() || 2358 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2359 "must have walkable stack"); 2360 2361 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2362 2363 assert(!this->is_ext_suspended(), 2364 "a thread trying to self-suspend should not already be suspended"); 2365 2366 if (this->is_suspend_equivalent()) { 2367 // If we are self-suspending as a result of the lifting of a 2368 // suspend equivalent condition, then the suspend_equivalent 2369 // flag is not cleared until we set the ext_suspended flag so 2370 // that wait_for_ext_suspend_completion() returns consistent 2371 // results. 2372 this->clear_suspend_equivalent(); 2373 } 2374 2375 // A racing resume may have cancelled us before we grabbed SR_lock 2376 // above. Or another external suspend request could be waiting for us 2377 // by the time we return from SR_lock()->wait(). The thread 2378 // that requested the suspension may already be trying to walk our 2379 // stack and if we return now, we can change the stack out from under 2380 // it. This would be a "bad thing (TM)" and cause the stack walker 2381 // to crash. We stay self-suspended until there are no more pending 2382 // external suspend requests. 2383 while (is_external_suspend()) { 2384 ret++; 2385 this->set_ext_suspended(); 2386 2387 // _ext_suspended flag is cleared by java_resume() 2388 while (is_ext_suspended()) { 2389 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2390 } 2391 } 2392 2393 return ret; 2394 } 2395 2396 #ifdef ASSERT 2397 // Verify the JavaThread has not yet been published in the Threads::list, and 2398 // hence doesn't need protection from concurrent access at this stage. 2399 void JavaThread::verify_not_published() { 2400 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2401 // since an unpublished JavaThread doesn't participate in the 2402 // Thread-SMR protocol for keeping a ThreadsList alive. 2403 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2404 } 2405 #endif 2406 2407 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2408 // progress or when _suspend_flags is non-zero. 2409 // Current thread needs to self-suspend if there is a suspend request and/or 2410 // block if a safepoint is in progress. 2411 // Async exception ISN'T checked. 2412 // Note only the ThreadInVMfromNative transition can call this function 2413 // directly and when thread state is _thread_in_native_trans 2414 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2415 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2416 2417 JavaThread *curJT = JavaThread::current(); 2418 bool do_self_suspend = thread->is_external_suspend(); 2419 2420 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2421 2422 // If JNIEnv proxies are allowed, don't self-suspend if the target 2423 // thread is not the current thread. In older versions of jdbx, jdbx 2424 // threads could call into the VM with another thread's JNIEnv so we 2425 // can be here operating on behalf of a suspended thread (4432884). 2426 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2427 JavaThreadState state = thread->thread_state(); 2428 2429 // We mark this thread_blocked state as a suspend-equivalent so 2430 // that a caller to is_ext_suspend_completed() won't be confused. 2431 // The suspend-equivalent state is cleared by java_suspend_self(). 2432 thread->set_suspend_equivalent(); 2433 2434 // If the safepoint code sees the _thread_in_native_trans state, it will 2435 // wait until the thread changes to other thread state. There is no 2436 // guarantee on how soon we can obtain the SR_lock and complete the 2437 // self-suspend request. It would be a bad idea to let safepoint wait for 2438 // too long. Temporarily change the state to _thread_blocked to 2439 // let the VM thread know that this thread is ready for GC. The problem 2440 // of changing thread state is that safepoint could happen just after 2441 // java_suspend_self() returns after being resumed, and VM thread will 2442 // see the _thread_blocked state. We must check for safepoint 2443 // after restoring the state and make sure we won't leave while a safepoint 2444 // is in progress. 2445 thread->set_thread_state(_thread_blocked); 2446 thread->java_suspend_self(); 2447 thread->set_thread_state(state); 2448 2449 InterfaceSupport::serialize_thread_state_with_handler(thread); 2450 } 2451 2452 SafepointMechanism::block_if_requested(curJT); 2453 2454 if (thread->is_deopt_suspend()) { 2455 thread->clear_deopt_suspend(); 2456 RegisterMap map(thread, false); 2457 frame f = thread->last_frame(); 2458 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2459 f = f.sender(&map); 2460 } 2461 if (f.id() == thread->must_deopt_id()) { 2462 thread->clear_must_deopt_id(); 2463 f.deoptimize(thread); 2464 } else { 2465 fatal("missed deoptimization!"); 2466 } 2467 } 2468 2469 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2470 } 2471 2472 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2473 // progress or when _suspend_flags is non-zero. 2474 // Current thread needs to self-suspend if there is a suspend request and/or 2475 // block if a safepoint is in progress. 2476 // Also check for pending async exception (not including unsafe access error). 2477 // Note only the native==>VM/Java barriers can call this function and when 2478 // thread state is _thread_in_native_trans. 2479 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2480 check_safepoint_and_suspend_for_native_trans(thread); 2481 2482 if (thread->has_async_exception()) { 2483 // We are in _thread_in_native_trans state, don't handle unsafe 2484 // access error since that may block. 2485 thread->check_and_handle_async_exceptions(false); 2486 } 2487 } 2488 2489 // This is a variant of the normal 2490 // check_special_condition_for_native_trans with slightly different 2491 // semantics for use by critical native wrappers. It does all the 2492 // normal checks but also performs the transition back into 2493 // thread_in_Java state. This is required so that critical natives 2494 // can potentially block and perform a GC if they are the last thread 2495 // exiting the GCLocker. 2496 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2497 check_special_condition_for_native_trans(thread); 2498 2499 // Finish the transition 2500 thread->set_thread_state(_thread_in_Java); 2501 2502 if (thread->do_critical_native_unlock()) { 2503 ThreadInVMfromJavaNoAsyncException tiv(thread); 2504 GCLocker::unlock_critical(thread); 2505 thread->clear_critical_native_unlock(); 2506 } 2507 } 2508 2509 // We need to guarantee the Threads_lock here, since resumes are not 2510 // allowed during safepoint synchronization 2511 // Can only resume from an external suspension 2512 void JavaThread::java_resume() { 2513 assert_locked_or_safepoint(Threads_lock); 2514 2515 // Sanity check: thread is gone, has started exiting or the thread 2516 // was not externally suspended. 2517 ThreadsListHandle tlh; 2518 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2519 return; 2520 } 2521 2522 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2523 2524 clear_external_suspend(); 2525 2526 if (is_ext_suspended()) { 2527 clear_ext_suspended(); 2528 SR_lock()->notify_all(); 2529 } 2530 } 2531 2532 size_t JavaThread::_stack_red_zone_size = 0; 2533 size_t JavaThread::_stack_yellow_zone_size = 0; 2534 size_t JavaThread::_stack_reserved_zone_size = 0; 2535 size_t JavaThread::_stack_shadow_zone_size = 0; 2536 2537 void JavaThread::create_stack_guard_pages() { 2538 if (!os::uses_stack_guard_pages() || 2539 _stack_guard_state != stack_guard_unused || 2540 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2541 log_info(os, thread)("Stack guard page creation for thread " 2542 UINTX_FORMAT " disabled", os::current_thread_id()); 2543 return; 2544 } 2545 address low_addr = stack_end(); 2546 size_t len = stack_guard_zone_size(); 2547 2548 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2549 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2550 2551 int must_commit = os::must_commit_stack_guard_pages(); 2552 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2553 2554 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2555 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2556 return; 2557 } 2558 2559 if (os::guard_memory((char *) low_addr, len)) { 2560 _stack_guard_state = stack_guard_enabled; 2561 } else { 2562 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2563 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2564 if (os::uncommit_memory((char *) low_addr, len)) { 2565 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2566 } 2567 return; 2568 } 2569 2570 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2571 PTR_FORMAT "-" PTR_FORMAT ".", 2572 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2573 } 2574 2575 void JavaThread::remove_stack_guard_pages() { 2576 assert(Thread::current() == this, "from different thread"); 2577 if (_stack_guard_state == stack_guard_unused) return; 2578 address low_addr = stack_end(); 2579 size_t len = stack_guard_zone_size(); 2580 2581 if (os::must_commit_stack_guard_pages()) { 2582 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2583 _stack_guard_state = stack_guard_unused; 2584 } else { 2585 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2586 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2587 return; 2588 } 2589 } else { 2590 if (_stack_guard_state == stack_guard_unused) return; 2591 if (os::unguard_memory((char *) low_addr, len)) { 2592 _stack_guard_state = stack_guard_unused; 2593 } else { 2594 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2595 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2596 return; 2597 } 2598 } 2599 2600 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2601 PTR_FORMAT "-" PTR_FORMAT ".", 2602 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2603 } 2604 2605 void JavaThread::enable_stack_reserved_zone() { 2606 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2607 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2608 2609 // The base notation is from the stack's point of view, growing downward. 2610 // We need to adjust it to work correctly with guard_memory() 2611 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2612 2613 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2614 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2615 2616 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2617 _stack_guard_state = stack_guard_enabled; 2618 } else { 2619 warning("Attempt to guard stack reserved zone failed."); 2620 } 2621 enable_register_stack_guard(); 2622 } 2623 2624 void JavaThread::disable_stack_reserved_zone() { 2625 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2626 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2627 2628 // Simply return if called for a thread that does not use guard pages. 2629 if (_stack_guard_state == stack_guard_unused) return; 2630 2631 // The base notation is from the stack's point of view, growing downward. 2632 // We need to adjust it to work correctly with guard_memory() 2633 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2634 2635 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2636 _stack_guard_state = stack_guard_reserved_disabled; 2637 } else { 2638 warning("Attempt to unguard stack reserved zone failed."); 2639 } 2640 disable_register_stack_guard(); 2641 } 2642 2643 void JavaThread::enable_stack_yellow_reserved_zone() { 2644 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2645 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2646 2647 // The base notation is from the stacks point of view, growing downward. 2648 // We need to adjust it to work correctly with guard_memory() 2649 address base = stack_red_zone_base(); 2650 2651 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2652 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2653 2654 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2655 _stack_guard_state = stack_guard_enabled; 2656 } else { 2657 warning("Attempt to guard stack yellow zone failed."); 2658 } 2659 enable_register_stack_guard(); 2660 } 2661 2662 void JavaThread::disable_stack_yellow_reserved_zone() { 2663 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2664 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2665 2666 // Simply return if called for a thread that does not use guard pages. 2667 if (_stack_guard_state == stack_guard_unused) return; 2668 2669 // The base notation is from the stacks point of view, growing downward. 2670 // We need to adjust it to work correctly with guard_memory() 2671 address base = stack_red_zone_base(); 2672 2673 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2674 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2675 } else { 2676 warning("Attempt to unguard stack yellow zone failed."); 2677 } 2678 disable_register_stack_guard(); 2679 } 2680 2681 void JavaThread::enable_stack_red_zone() { 2682 // The base notation is from the stacks point of view, growing downward. 2683 // We need to adjust it to work correctly with guard_memory() 2684 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2685 address base = stack_red_zone_base() - stack_red_zone_size(); 2686 2687 guarantee(base < stack_base(), "Error calculating stack red zone"); 2688 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2689 2690 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2691 warning("Attempt to guard stack red zone failed."); 2692 } 2693 } 2694 2695 void JavaThread::disable_stack_red_zone() { 2696 // The base notation is from the stacks point of view, growing downward. 2697 // We need to adjust it to work correctly with guard_memory() 2698 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2699 address base = stack_red_zone_base() - stack_red_zone_size(); 2700 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2701 warning("Attempt to unguard stack red zone failed."); 2702 } 2703 } 2704 2705 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2706 // ignore is there is no stack 2707 if (!has_last_Java_frame()) return; 2708 // traverse the stack frames. Starts from top frame. 2709 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2710 frame* fr = fst.current(); 2711 f(fr, fst.register_map()); 2712 } 2713 } 2714 2715 2716 #ifndef PRODUCT 2717 // Deoptimization 2718 // Function for testing deoptimization 2719 void JavaThread::deoptimize() { 2720 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2721 StackFrameStream fst(this, UseBiasedLocking); 2722 bool deopt = false; // Dump stack only if a deopt actually happens. 2723 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2724 // Iterate over all frames in the thread and deoptimize 2725 for (; !fst.is_done(); fst.next()) { 2726 if (fst.current()->can_be_deoptimized()) { 2727 2728 if (only_at) { 2729 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2730 // consists of comma or carriage return separated numbers so 2731 // search for the current bci in that string. 2732 address pc = fst.current()->pc(); 2733 nmethod* nm = (nmethod*) fst.current()->cb(); 2734 ScopeDesc* sd = nm->scope_desc_at(pc); 2735 char buffer[8]; 2736 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2737 size_t len = strlen(buffer); 2738 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2739 while (found != NULL) { 2740 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2741 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2742 // Check that the bci found is bracketed by terminators. 2743 break; 2744 } 2745 found = strstr(found + 1, buffer); 2746 } 2747 if (!found) { 2748 continue; 2749 } 2750 } 2751 2752 if (DebugDeoptimization && !deopt) { 2753 deopt = true; // One-time only print before deopt 2754 tty->print_cr("[BEFORE Deoptimization]"); 2755 trace_frames(); 2756 trace_stack(); 2757 } 2758 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2759 } 2760 } 2761 2762 if (DebugDeoptimization && deopt) { 2763 tty->print_cr("[AFTER Deoptimization]"); 2764 trace_frames(); 2765 } 2766 } 2767 2768 2769 // Make zombies 2770 void JavaThread::make_zombies() { 2771 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2772 if (fst.current()->can_be_deoptimized()) { 2773 // it is a Java nmethod 2774 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2775 nm->make_not_entrant(); 2776 } 2777 } 2778 } 2779 #endif // PRODUCT 2780 2781 2782 void JavaThread::deoptimized_wrt_marked_nmethods() { 2783 if (!has_last_Java_frame()) return; 2784 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2785 StackFrameStream fst(this, UseBiasedLocking); 2786 for (; !fst.is_done(); fst.next()) { 2787 if (fst.current()->should_be_deoptimized()) { 2788 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2789 } 2790 } 2791 } 2792 2793 2794 // If the caller is a NamedThread, then remember, in the current scope, 2795 // the given JavaThread in its _processed_thread field. 2796 class RememberProcessedThread: public StackObj { 2797 NamedThread* _cur_thr; 2798 public: 2799 RememberProcessedThread(JavaThread* jthr) { 2800 Thread* thread = Thread::current(); 2801 if (thread->is_Named_thread()) { 2802 _cur_thr = (NamedThread *)thread; 2803 _cur_thr->set_processed_thread(jthr); 2804 } else { 2805 _cur_thr = NULL; 2806 } 2807 } 2808 2809 ~RememberProcessedThread() { 2810 if (_cur_thr) { 2811 _cur_thr->set_processed_thread(NULL); 2812 } 2813 } 2814 }; 2815 2816 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2817 // Verify that the deferred card marks have been flushed. 2818 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2819 2820 // Traverse the GCHandles 2821 Thread::oops_do(f, cf); 2822 2823 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2824 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2825 2826 if (has_last_Java_frame()) { 2827 // Record JavaThread to GC thread 2828 RememberProcessedThread rpt(this); 2829 2830 // traverse the registered growable array 2831 if (_array_for_gc != NULL) { 2832 for (int index = 0; index < _array_for_gc->length(); index++) { 2833 f->do_oop(_array_for_gc->adr_at(index)); 2834 } 2835 } 2836 2837 // Traverse the monitor chunks 2838 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2839 chunk->oops_do(f); 2840 } 2841 2842 // Traverse the execution stack 2843 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2844 fst.current()->oops_do(f, cf, fst.register_map()); 2845 } 2846 } 2847 2848 // callee_target is never live across a gc point so NULL it here should 2849 // it still contain a methdOop. 2850 2851 set_callee_target(NULL); 2852 2853 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2854 // If we have deferred set_locals there might be oops waiting to be 2855 // written 2856 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2857 if (list != NULL) { 2858 for (int i = 0; i < list->length(); i++) { 2859 list->at(i)->oops_do(f); 2860 } 2861 } 2862 2863 // Traverse instance variables at the end since the GC may be moving things 2864 // around using this function 2865 f->do_oop((oop*) &_threadObj); 2866 f->do_oop((oop*) &_vm_result); 2867 f->do_oop((oop*) &_exception_oop); 2868 f->do_oop((oop*) &_pending_async_exception); 2869 2870 if (jvmti_thread_state() != NULL) { 2871 jvmti_thread_state()->oops_do(f); 2872 } 2873 } 2874 2875 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2876 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2877 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2878 2879 if (has_last_Java_frame()) { 2880 // Traverse the execution stack 2881 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2882 fst.current()->nmethods_do(cf); 2883 } 2884 } 2885 } 2886 2887 void JavaThread::metadata_do(void f(Metadata*)) { 2888 if (has_last_Java_frame()) { 2889 // Traverse the execution stack to call f() on the methods in the stack 2890 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2891 fst.current()->metadata_do(f); 2892 } 2893 } else if (is_Compiler_thread()) { 2894 // need to walk ciMetadata in current compile tasks to keep alive. 2895 CompilerThread* ct = (CompilerThread*)this; 2896 if (ct->env() != NULL) { 2897 ct->env()->metadata_do(f); 2898 } 2899 CompileTask* task = ct->task(); 2900 if (task != NULL) { 2901 task->metadata_do(f); 2902 } 2903 } 2904 } 2905 2906 // Printing 2907 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2908 switch (_thread_state) { 2909 case _thread_uninitialized: return "_thread_uninitialized"; 2910 case _thread_new: return "_thread_new"; 2911 case _thread_new_trans: return "_thread_new_trans"; 2912 case _thread_in_native: return "_thread_in_native"; 2913 case _thread_in_native_trans: return "_thread_in_native_trans"; 2914 case _thread_in_vm: return "_thread_in_vm"; 2915 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2916 case _thread_in_Java: return "_thread_in_Java"; 2917 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2918 case _thread_blocked: return "_thread_blocked"; 2919 case _thread_blocked_trans: return "_thread_blocked_trans"; 2920 default: return "unknown thread state"; 2921 } 2922 } 2923 2924 #ifndef PRODUCT 2925 void JavaThread::print_thread_state_on(outputStream *st) const { 2926 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2927 }; 2928 void JavaThread::print_thread_state() const { 2929 print_thread_state_on(tty); 2930 } 2931 #endif // PRODUCT 2932 2933 // Called by Threads::print() for VM_PrintThreads operation 2934 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2935 st->print_raw("\""); 2936 st->print_raw(get_thread_name()); 2937 st->print_raw("\" "); 2938 oop thread_oop = threadObj(); 2939 if (thread_oop != NULL) { 2940 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2941 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2942 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2943 } 2944 Thread::print_on(st, print_extended_info); 2945 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2946 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2947 if (thread_oop != NULL) { 2948 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2949 } 2950 #ifndef PRODUCT 2951 _safepoint_state->print_on(st); 2952 #endif // PRODUCT 2953 if (is_Compiler_thread()) { 2954 CompileTask *task = ((CompilerThread*)this)->task(); 2955 if (task != NULL) { 2956 st->print(" Compiling: "); 2957 task->print(st, NULL, true, false); 2958 } else { 2959 st->print(" No compile task"); 2960 } 2961 st->cr(); 2962 } 2963 } 2964 2965 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2966 st->print("%s", get_thread_name_string(buf, buflen)); 2967 } 2968 2969 // Called by fatal error handler. The difference between this and 2970 // JavaThread::print() is that we can't grab lock or allocate memory. 2971 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2972 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2973 oop thread_obj = threadObj(); 2974 if (thread_obj != NULL) { 2975 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2976 } 2977 st->print(" ["); 2978 st->print("%s", _get_thread_state_name(_thread_state)); 2979 if (osthread()) { 2980 st->print(", id=%d", osthread()->thread_id()); 2981 } 2982 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2983 p2i(stack_end()), p2i(stack_base())); 2984 st->print("]"); 2985 2986 ThreadsSMRSupport::print_info_on(this, st); 2987 return; 2988 } 2989 2990 // Verification 2991 2992 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2993 2994 void JavaThread::verify() { 2995 // Verify oops in the thread. 2996 oops_do(&VerifyOopClosure::verify_oop, NULL); 2997 2998 // Verify the stack frames. 2999 frames_do(frame_verify); 3000 } 3001 3002 // CR 6300358 (sub-CR 2137150) 3003 // Most callers of this method assume that it can't return NULL but a 3004 // thread may not have a name whilst it is in the process of attaching to 3005 // the VM - see CR 6412693, and there are places where a JavaThread can be 3006 // seen prior to having it's threadObj set (eg JNI attaching threads and 3007 // if vm exit occurs during initialization). These cases can all be accounted 3008 // for such that this method never returns NULL. 3009 const char* JavaThread::get_thread_name() const { 3010 #ifdef ASSERT 3011 // early safepoints can hit while current thread does not yet have TLS 3012 if (!SafepointSynchronize::is_at_safepoint()) { 3013 Thread *cur = Thread::current(); 3014 if (!(cur->is_Java_thread() && cur == this)) { 3015 // Current JavaThreads are allowed to get their own name without 3016 // the Threads_lock. 3017 assert_locked_or_safepoint(Threads_lock); 3018 } 3019 } 3020 #endif // ASSERT 3021 return get_thread_name_string(); 3022 } 3023 3024 // Returns a non-NULL representation of this thread's name, or a suitable 3025 // descriptive string if there is no set name 3026 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3027 const char* name_str; 3028 oop thread_obj = threadObj(); 3029 if (thread_obj != NULL) { 3030 oop name = java_lang_Thread::name(thread_obj); 3031 if (name != NULL) { 3032 if (buf == NULL) { 3033 name_str = java_lang_String::as_utf8_string(name); 3034 } else { 3035 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3036 } 3037 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3038 name_str = "<no-name - thread is attaching>"; 3039 } else { 3040 name_str = Thread::name(); 3041 } 3042 } else { 3043 name_str = Thread::name(); 3044 } 3045 assert(name_str != NULL, "unexpected NULL thread name"); 3046 return name_str; 3047 } 3048 3049 3050 const char* JavaThread::get_threadgroup_name() const { 3051 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3052 oop thread_obj = threadObj(); 3053 if (thread_obj != NULL) { 3054 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3055 if (thread_group != NULL) { 3056 // ThreadGroup.name can be null 3057 return java_lang_ThreadGroup::name(thread_group); 3058 } 3059 } 3060 return NULL; 3061 } 3062 3063 const char* JavaThread::get_parent_name() const { 3064 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3065 oop thread_obj = threadObj(); 3066 if (thread_obj != NULL) { 3067 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3068 if (thread_group != NULL) { 3069 oop parent = java_lang_ThreadGroup::parent(thread_group); 3070 if (parent != NULL) { 3071 // ThreadGroup.name can be null 3072 return java_lang_ThreadGroup::name(parent); 3073 } 3074 } 3075 } 3076 return NULL; 3077 } 3078 3079 ThreadPriority JavaThread::java_priority() const { 3080 oop thr_oop = threadObj(); 3081 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3082 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3083 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3084 return priority; 3085 } 3086 3087 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3088 3089 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3090 // Link Java Thread object <-> C++ Thread 3091 3092 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3093 // and put it into a new Handle. The Handle "thread_oop" can then 3094 // be used to pass the C++ thread object to other methods. 3095 3096 // Set the Java level thread object (jthread) field of the 3097 // new thread (a JavaThread *) to C++ thread object using the 3098 // "thread_oop" handle. 3099 3100 // Set the thread field (a JavaThread *) of the 3101 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3102 3103 Handle thread_oop(Thread::current(), 3104 JNIHandles::resolve_non_null(jni_thread)); 3105 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3106 "must be initialized"); 3107 set_threadObj(thread_oop()); 3108 java_lang_Thread::set_thread(thread_oop(), this); 3109 3110 if (prio == NoPriority) { 3111 prio = java_lang_Thread::priority(thread_oop()); 3112 assert(prio != NoPriority, "A valid priority should be present"); 3113 } 3114 3115 // Push the Java priority down to the native thread; needs Threads_lock 3116 Thread::set_priority(this, prio); 3117 3118 // Add the new thread to the Threads list and set it in motion. 3119 // We must have threads lock in order to call Threads::add. 3120 // It is crucial that we do not block before the thread is 3121 // added to the Threads list for if a GC happens, then the java_thread oop 3122 // will not be visited by GC. 3123 Threads::add(this); 3124 } 3125 3126 oop JavaThread::current_park_blocker() { 3127 // Support for JSR-166 locks 3128 oop thread_oop = threadObj(); 3129 if (thread_oop != NULL && 3130 JDK_Version::current().supports_thread_park_blocker()) { 3131 return java_lang_Thread::park_blocker(thread_oop); 3132 } 3133 return NULL; 3134 } 3135 3136 3137 void JavaThread::print_stack_on(outputStream* st) { 3138 if (!has_last_Java_frame()) return; 3139 ResourceMark rm; 3140 HandleMark hm; 3141 3142 RegisterMap reg_map(this); 3143 vframe* start_vf = last_java_vframe(®_map); 3144 int count = 0; 3145 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3146 if (f->is_java_frame()) { 3147 javaVFrame* jvf = javaVFrame::cast(f); 3148 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3149 3150 // Print out lock information 3151 if (JavaMonitorsInStackTrace) { 3152 jvf->print_lock_info_on(st, count); 3153 } 3154 } else { 3155 // Ignore non-Java frames 3156 } 3157 3158 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3159 count++; 3160 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3161 } 3162 } 3163 3164 3165 // JVMTI PopFrame support 3166 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3167 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3168 if (in_bytes(size_in_bytes) != 0) { 3169 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3170 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3171 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3172 } 3173 } 3174 3175 void* JavaThread::popframe_preserved_args() { 3176 return _popframe_preserved_args; 3177 } 3178 3179 ByteSize JavaThread::popframe_preserved_args_size() { 3180 return in_ByteSize(_popframe_preserved_args_size); 3181 } 3182 3183 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3184 int sz = in_bytes(popframe_preserved_args_size()); 3185 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3186 return in_WordSize(sz / wordSize); 3187 } 3188 3189 void JavaThread::popframe_free_preserved_args() { 3190 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3191 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3192 _popframe_preserved_args = NULL; 3193 _popframe_preserved_args_size = 0; 3194 } 3195 3196 #ifndef PRODUCT 3197 3198 void JavaThread::trace_frames() { 3199 tty->print_cr("[Describe stack]"); 3200 int frame_no = 1; 3201 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3202 tty->print(" %d. ", frame_no++); 3203 fst.current()->print_value_on(tty, this); 3204 tty->cr(); 3205 } 3206 } 3207 3208 class PrintAndVerifyOopClosure: public OopClosure { 3209 protected: 3210 template <class T> inline void do_oop_work(T* p) { 3211 oop obj = RawAccess<>::oop_load(p); 3212 if (obj == NULL) return; 3213 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3214 if (oopDesc::is_oop_or_null(obj)) { 3215 if (obj->is_objArray()) { 3216 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3217 } else { 3218 obj->print(); 3219 } 3220 } else { 3221 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3222 } 3223 tty->cr(); 3224 } 3225 public: 3226 virtual void do_oop(oop* p) { do_oop_work(p); } 3227 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3228 }; 3229 3230 3231 static void oops_print(frame* f, const RegisterMap *map) { 3232 PrintAndVerifyOopClosure print; 3233 f->print_value(); 3234 f->oops_do(&print, NULL, (RegisterMap*)map); 3235 } 3236 3237 // Print our all the locations that contain oops and whether they are 3238 // valid or not. This useful when trying to find the oldest frame 3239 // where an oop has gone bad since the frame walk is from youngest to 3240 // oldest. 3241 void JavaThread::trace_oops() { 3242 tty->print_cr("[Trace oops]"); 3243 frames_do(oops_print); 3244 } 3245 3246 3247 #ifdef ASSERT 3248 // Print or validate the layout of stack frames 3249 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3250 ResourceMark rm; 3251 PRESERVE_EXCEPTION_MARK; 3252 FrameValues values; 3253 int frame_no = 0; 3254 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3255 fst.current()->describe(values, ++frame_no); 3256 if (depth == frame_no) break; 3257 } 3258 if (validate_only) { 3259 values.validate(); 3260 } else { 3261 tty->print_cr("[Describe stack layout]"); 3262 values.print(this); 3263 } 3264 } 3265 #endif 3266 3267 void JavaThread::trace_stack_from(vframe* start_vf) { 3268 ResourceMark rm; 3269 int vframe_no = 1; 3270 for (vframe* f = start_vf; f; f = f->sender()) { 3271 if (f->is_java_frame()) { 3272 javaVFrame::cast(f)->print_activation(vframe_no++); 3273 } else { 3274 f->print(); 3275 } 3276 if (vframe_no > StackPrintLimit) { 3277 tty->print_cr("...<more frames>..."); 3278 return; 3279 } 3280 } 3281 } 3282 3283 3284 void JavaThread::trace_stack() { 3285 if (!has_last_Java_frame()) return; 3286 ResourceMark rm; 3287 HandleMark hm; 3288 RegisterMap reg_map(this); 3289 trace_stack_from(last_java_vframe(®_map)); 3290 } 3291 3292 3293 #endif // PRODUCT 3294 3295 3296 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3297 assert(reg_map != NULL, "a map must be given"); 3298 frame f = last_frame(); 3299 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3300 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3301 } 3302 return NULL; 3303 } 3304 3305 3306 Klass* JavaThread::security_get_caller_class(int depth) { 3307 vframeStream vfst(this); 3308 vfst.security_get_caller_frame(depth); 3309 if (!vfst.at_end()) { 3310 return vfst.method()->method_holder(); 3311 } 3312 return NULL; 3313 } 3314 3315 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3316 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3317 CompileBroker::compiler_thread_loop(); 3318 } 3319 3320 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3321 NMethodSweeper::sweeper_loop(); 3322 } 3323 3324 // Create a CompilerThread 3325 CompilerThread::CompilerThread(CompileQueue* queue, 3326 CompilerCounters* counters) 3327 : JavaThread(&compiler_thread_entry) { 3328 _env = NULL; 3329 _log = NULL; 3330 _task = NULL; 3331 _queue = queue; 3332 _counters = counters; 3333 _buffer_blob = NULL; 3334 _compiler = NULL; 3335 3336 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3337 resource_area()->bias_to(mtCompiler); 3338 3339 #ifndef PRODUCT 3340 _ideal_graph_printer = NULL; 3341 #endif 3342 } 3343 3344 CompilerThread::~CompilerThread() { 3345 // Delete objects which were allocated on heap. 3346 delete _counters; 3347 } 3348 3349 bool CompilerThread::can_call_java() const { 3350 return _compiler != NULL && _compiler->is_jvmci(); 3351 } 3352 3353 // Create sweeper thread 3354 CodeCacheSweeperThread::CodeCacheSweeperThread() 3355 : JavaThread(&sweeper_thread_entry) { 3356 _scanned_compiled_method = NULL; 3357 } 3358 3359 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3360 JavaThread::oops_do(f, cf); 3361 if (_scanned_compiled_method != NULL && cf != NULL) { 3362 // Safepoints can occur when the sweeper is scanning an nmethod so 3363 // process it here to make sure it isn't unloaded in the middle of 3364 // a scan. 3365 cf->do_code_blob(_scanned_compiled_method); 3366 } 3367 } 3368 3369 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3370 JavaThread::nmethods_do(cf); 3371 if (_scanned_compiled_method != NULL && cf != NULL) { 3372 // Safepoints can occur when the sweeper is scanning an nmethod so 3373 // process it here to make sure it isn't unloaded in the middle of 3374 // a scan. 3375 cf->do_code_blob(_scanned_compiled_method); 3376 } 3377 } 3378 3379 3380 // ======= Threads ======== 3381 3382 // The Threads class links together all active threads, and provides 3383 // operations over all threads. It is protected by the Threads_lock, 3384 // which is also used in other global contexts like safepointing. 3385 // ThreadsListHandles are used to safely perform operations on one 3386 // or more threads without the risk of the thread exiting during the 3387 // operation. 3388 // 3389 // Note: The Threads_lock is currently more widely used than we 3390 // would like. We are actively migrating Threads_lock uses to other 3391 // mechanisms in order to reduce Threads_lock contention. 3392 3393 JavaThread* Threads::_thread_list = NULL; 3394 int Threads::_number_of_threads = 0; 3395 int Threads::_number_of_non_daemon_threads = 0; 3396 int Threads::_return_code = 0; 3397 int Threads::_thread_claim_parity = 0; 3398 size_t JavaThread::_stack_size_at_create = 0; 3399 3400 #ifdef ASSERT 3401 bool Threads::_vm_complete = false; 3402 #endif 3403 3404 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3405 Prefetch::read((void*)addr, prefetch_interval); 3406 return *addr; 3407 } 3408 3409 // Possibly the ugliest for loop the world has seen. C++ does not allow 3410 // multiple types in the declaration section of the for loop. In this case 3411 // we are only dealing with pointers and hence can cast them. It looks ugly 3412 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3413 #define DO_JAVA_THREADS(LIST, X) \ 3414 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3415 *MACRO_list = (JavaThread*)(LIST), \ 3416 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3417 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3418 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3419 MACRO_current_p != MACRO_end; \ 3420 MACRO_current_p++, \ 3421 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3422 3423 // All JavaThreads 3424 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3425 3426 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3427 void Threads::non_java_threads_do(ThreadClosure* tc) { 3428 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3429 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3430 tc->do_thread(njti.current()); 3431 } 3432 } 3433 3434 // All JavaThreads 3435 void Threads::java_threads_do(ThreadClosure* tc) { 3436 assert_locked_or_safepoint(Threads_lock); 3437 // ALL_JAVA_THREADS iterates through all JavaThreads. 3438 ALL_JAVA_THREADS(p) { 3439 tc->do_thread(p); 3440 } 3441 } 3442 3443 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3444 assert_locked_or_safepoint(Threads_lock); 3445 java_threads_do(tc); 3446 tc->do_thread(VMThread::vm_thread()); 3447 } 3448 3449 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3450 void Threads::threads_do(ThreadClosure* tc) { 3451 assert_locked_or_safepoint(Threads_lock); 3452 java_threads_do(tc); 3453 non_java_threads_do(tc); 3454 } 3455 3456 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3457 int cp = Threads::thread_claim_parity(); 3458 ALL_JAVA_THREADS(p) { 3459 if (p->claim_oops_do(is_par, cp)) { 3460 tc->do_thread(p); 3461 } 3462 } 3463 VMThread* vmt = VMThread::vm_thread(); 3464 if (vmt->claim_oops_do(is_par, cp)) { 3465 tc->do_thread(vmt); 3466 } 3467 } 3468 3469 // The system initialization in the library has three phases. 3470 // 3471 // Phase 1: java.lang.System class initialization 3472 // java.lang.System is a primordial class loaded and initialized 3473 // by the VM early during startup. java.lang.System.<clinit> 3474 // only does registerNatives and keeps the rest of the class 3475 // initialization work later until thread initialization completes. 3476 // 3477 // System.initPhase1 initializes the system properties, the static 3478 // fields in, out, and err. Set up java signal handlers, OS-specific 3479 // system settings, and thread group of the main thread. 3480 static void call_initPhase1(TRAPS) { 3481 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3482 JavaValue result(T_VOID); 3483 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3484 vmSymbols::void_method_signature(), CHECK); 3485 } 3486 3487 // Phase 2. Module system initialization 3488 // This will initialize the module system. Only java.base classes 3489 // can be loaded until phase 2 completes. 3490 // 3491 // Call System.initPhase2 after the compiler initialization and jsr292 3492 // classes get initialized because module initialization runs a lot of java 3493 // code, that for performance reasons, should be compiled. Also, this will 3494 // enable the startup code to use lambda and other language features in this 3495 // phase and onward. 3496 // 3497 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3498 static void call_initPhase2(TRAPS) { 3499 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3500 3501 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3502 3503 JavaValue result(T_INT); 3504 JavaCallArguments args; 3505 args.push_int(DisplayVMOutputToStderr); 3506 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3507 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3508 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3509 if (result.get_jint() != JNI_OK) { 3510 vm_exit_during_initialization(); // no message or exception 3511 } 3512 3513 universe_post_module_init(); 3514 } 3515 3516 // Phase 3. final setup - set security manager, system class loader and TCCL 3517 // 3518 // This will instantiate and set the security manager, set the system class 3519 // loader as well as the thread context class loader. The security manager 3520 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3521 // other modules or the application's classpath. 3522 static void call_initPhase3(TRAPS) { 3523 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3524 JavaValue result(T_VOID); 3525 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3526 vmSymbols::void_method_signature(), CHECK); 3527 } 3528 3529 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3530 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3531 3532 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3533 create_vm_init_libraries(); 3534 } 3535 3536 initialize_class(vmSymbols::java_lang_String(), CHECK); 3537 3538 // Inject CompactStrings value after the static initializers for String ran. 3539 java_lang_String::set_compact_strings(CompactStrings); 3540 3541 // Initialize java_lang.System (needed before creating the thread) 3542 initialize_class(vmSymbols::java_lang_System(), CHECK); 3543 // The VM creates & returns objects of this class. Make sure it's initialized. 3544 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3545 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3546 Handle thread_group = create_initial_thread_group(CHECK); 3547 Universe::set_main_thread_group(thread_group()); 3548 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3549 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3550 main_thread->set_threadObj(thread_object); 3551 // Set thread status to running since main thread has 3552 // been started and running. 3553 java_lang_Thread::set_thread_status(thread_object, 3554 java_lang_Thread::RUNNABLE); 3555 3556 // The VM creates objects of this class. 3557 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3558 3559 // The VM preresolves methods to these classes. Make sure that they get initialized 3560 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3561 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3562 3563 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3564 call_initPhase1(CHECK); 3565 3566 // get the Java runtime name after java.lang.System is initialized 3567 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3568 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3569 3570 // an instance of OutOfMemory exception has been allocated earlier 3571 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3572 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3573 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3574 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3575 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3576 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3577 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3578 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3579 } 3580 3581 void Threads::initialize_jsr292_core_classes(TRAPS) { 3582 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3583 3584 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3585 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3586 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3587 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3588 } 3589 3590 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3591 extern void JDK_Version_init(); 3592 3593 // Preinitialize version info. 3594 VM_Version::early_initialize(); 3595 3596 // Check version 3597 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3598 3599 // Initialize library-based TLS 3600 ThreadLocalStorage::init(); 3601 3602 // Initialize the output stream module 3603 ostream_init(); 3604 3605 // Process java launcher properties. 3606 Arguments::process_sun_java_launcher_properties(args); 3607 3608 // Initialize the os module 3609 os::init(); 3610 3611 // Record VM creation timing statistics 3612 TraceVmCreationTime create_vm_timer; 3613 create_vm_timer.start(); 3614 3615 // Initialize system properties. 3616 Arguments::init_system_properties(); 3617 3618 // So that JDK version can be used as a discriminator when parsing arguments 3619 JDK_Version_init(); 3620 3621 // Update/Initialize System properties after JDK version number is known 3622 Arguments::init_version_specific_system_properties(); 3623 3624 // Make sure to initialize log configuration *before* parsing arguments 3625 LogConfiguration::initialize(create_vm_timer.begin_time()); 3626 3627 // Parse arguments 3628 // Note: this internally calls os::init_container_support() 3629 jint parse_result = Arguments::parse(args); 3630 if (parse_result != JNI_OK) return parse_result; 3631 3632 os::init_before_ergo(); 3633 3634 jint ergo_result = Arguments::apply_ergo(); 3635 if (ergo_result != JNI_OK) return ergo_result; 3636 3637 // Final check of all ranges after ergonomics which may change values. 3638 if (!JVMFlagRangeList::check_ranges()) { 3639 return JNI_EINVAL; 3640 } 3641 3642 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3643 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3644 if (!constraint_result) { 3645 return JNI_EINVAL; 3646 } 3647 3648 JVMFlagWriteableList::mark_startup(); 3649 3650 if (PauseAtStartup) { 3651 os::pause(); 3652 } 3653 3654 HOTSPOT_VM_INIT_BEGIN(); 3655 3656 // Timing (must come after argument parsing) 3657 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3658 3659 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3660 // Initialize assert poison page mechanism. 3661 if (ShowRegistersOnAssert) { 3662 initialize_assert_poison(); 3663 } 3664 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3665 3666 // Initialize the os module after parsing the args 3667 jint os_init_2_result = os::init_2(); 3668 if (os_init_2_result != JNI_OK) return os_init_2_result; 3669 3670 SafepointMechanism::initialize(); 3671 3672 jint adjust_after_os_result = Arguments::adjust_after_os(); 3673 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3674 3675 // Initialize output stream logging 3676 ostream_init_log(); 3677 3678 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3679 // Must be before create_vm_init_agents() 3680 if (Arguments::init_libraries_at_startup()) { 3681 convert_vm_init_libraries_to_agents(); 3682 } 3683 3684 // Launch -agentlib/-agentpath and converted -Xrun agents 3685 if (Arguments::init_agents_at_startup()) { 3686 create_vm_init_agents(); 3687 } 3688 3689 // Initialize Threads state 3690 _thread_list = NULL; 3691 _number_of_threads = 0; 3692 _number_of_non_daemon_threads = 0; 3693 3694 // Initialize global data structures and create system classes in heap 3695 vm_init_globals(); 3696 3697 #if INCLUDE_JVMCI 3698 if (JVMCICounterSize > 0) { 3699 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3700 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3701 } else { 3702 JavaThread::_jvmci_old_thread_counters = NULL; 3703 } 3704 #endif // INCLUDE_JVMCI 3705 3706 // Attach the main thread to this os thread 3707 JavaThread* main_thread = new JavaThread(); 3708 main_thread->set_thread_state(_thread_in_vm); 3709 main_thread->initialize_thread_current(); 3710 // must do this before set_active_handles 3711 main_thread->record_stack_base_and_size(); 3712 main_thread->register_thread_stack_with_NMT(); 3713 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3714 3715 if (!main_thread->set_as_starting_thread()) { 3716 vm_shutdown_during_initialization( 3717 "Failed necessary internal allocation. Out of swap space"); 3718 main_thread->smr_delete(); 3719 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3720 return JNI_ENOMEM; 3721 } 3722 3723 // Enable guard page *after* os::create_main_thread(), otherwise it would 3724 // crash Linux VM, see notes in os_linux.cpp. 3725 main_thread->create_stack_guard_pages(); 3726 3727 // Initialize Java-Level synchronization subsystem 3728 ObjectMonitor::Initialize(); 3729 3730 // Initialize global modules 3731 jint status = init_globals(); 3732 if (status != JNI_OK) { 3733 main_thread->smr_delete(); 3734 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3735 return status; 3736 } 3737 3738 JFR_ONLY(Jfr::on_vm_init();) 3739 3740 // Should be done after the heap is fully created 3741 main_thread->cache_global_variables(); 3742 3743 HandleMark hm; 3744 3745 { MutexLocker mu(Threads_lock); 3746 Threads::add(main_thread); 3747 } 3748 3749 // Any JVMTI raw monitors entered in onload will transition into 3750 // real raw monitor. VM is setup enough here for raw monitor enter. 3751 JvmtiExport::transition_pending_onload_raw_monitors(); 3752 3753 // Create the VMThread 3754 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3755 3756 VMThread::create(); 3757 Thread* vmthread = VMThread::vm_thread(); 3758 3759 if (!os::create_thread(vmthread, os::vm_thread)) { 3760 vm_exit_during_initialization("Cannot create VM thread. " 3761 "Out of system resources."); 3762 } 3763 3764 // Wait for the VM thread to become ready, and VMThread::run to initialize 3765 // Monitors can have spurious returns, must always check another state flag 3766 { 3767 MutexLocker ml(Notify_lock); 3768 os::start_thread(vmthread); 3769 while (vmthread->active_handles() == NULL) { 3770 Notify_lock->wait(); 3771 } 3772 } 3773 } 3774 3775 assert(Universe::is_fully_initialized(), "not initialized"); 3776 if (VerifyDuringStartup) { 3777 // Make sure we're starting with a clean slate. 3778 VM_Verify verify_op; 3779 VMThread::execute(&verify_op); 3780 } 3781 3782 // We need this to update the java.vm.info property in case any flags used 3783 // to initially define it have been changed. This is needed for both CDS and 3784 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3785 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3786 // This update must happen before we initialize the java classes, but 3787 // after any initialization logic that might modify the flags. 3788 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3789 3790 Thread* THREAD = Thread::current(); 3791 3792 // Always call even when there are not JVMTI environments yet, since environments 3793 // may be attached late and JVMTI must track phases of VM execution 3794 JvmtiExport::enter_early_start_phase(); 3795 3796 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3797 JvmtiExport::post_early_vm_start(); 3798 3799 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3800 3801 quicken_jni_functions(); 3802 3803 // No more stub generation allowed after that point. 3804 StubCodeDesc::freeze(); 3805 3806 // Set flag that basic initialization has completed. Used by exceptions and various 3807 // debug stuff, that does not work until all basic classes have been initialized. 3808 set_init_completed(); 3809 3810 LogConfiguration::post_initialize(); 3811 Metaspace::post_initialize(); 3812 3813 HOTSPOT_VM_INIT_END(); 3814 3815 // record VM initialization completion time 3816 #if INCLUDE_MANAGEMENT 3817 Management::record_vm_init_completed(); 3818 #endif // INCLUDE_MANAGEMENT 3819 3820 // Signal Dispatcher needs to be started before VMInit event is posted 3821 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3822 3823 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3824 if (!DisableAttachMechanism) { 3825 AttachListener::vm_start(); 3826 if (StartAttachListener || AttachListener::init_at_startup()) { 3827 AttachListener::init(); 3828 } 3829 } 3830 3831 // Launch -Xrun agents 3832 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3833 // back-end can launch with -Xdebug -Xrunjdwp. 3834 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3835 create_vm_init_libraries(); 3836 } 3837 3838 if (CleanChunkPoolAsync) { 3839 Chunk::start_chunk_pool_cleaner_task(); 3840 } 3841 3842 // initialize compiler(s) 3843 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3844 #if INCLUDE_JVMCI 3845 bool force_JVMCI_intialization = false; 3846 if (EnableJVMCI) { 3847 // Initialize JVMCI eagerly when it is explicitly requested. 3848 // Or when JVMCIPrintProperties is enabled. 3849 // The JVMCI Java initialization code will read this flag and 3850 // do the printing if it's set. 3851 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3852 3853 if (!force_JVMCI_intialization) { 3854 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3855 // compilations via JVMCI will not actually block until JVMCI is initialized. 3856 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3857 } 3858 } 3859 #endif 3860 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3861 // Postpone completion of compiler initialization to after JVMCI 3862 // is initialized to avoid timeouts of blocking compilations. 3863 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3864 CompileBroker::compilation_init_phase2(); 3865 } 3866 #endif 3867 3868 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3869 // It is done after compilers are initialized, because otherwise compilations of 3870 // signature polymorphic MH intrinsics can be missed 3871 // (see SystemDictionary::find_method_handle_intrinsic). 3872 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3873 3874 // This will initialize the module system. Only java.base classes can be 3875 // loaded until phase 2 completes 3876 call_initPhase2(CHECK_JNI_ERR); 3877 3878 // Always call even when there are not JVMTI environments yet, since environments 3879 // may be attached late and JVMTI must track phases of VM execution 3880 JvmtiExport::enter_start_phase(); 3881 3882 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3883 JvmtiExport::post_vm_start(); 3884 3885 // Final system initialization including security manager and system class loader 3886 call_initPhase3(CHECK_JNI_ERR); 3887 3888 // cache the system and platform class loaders 3889 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3890 3891 #if INCLUDE_CDS 3892 if (DumpSharedSpaces) { 3893 // capture the module path info from the ModuleEntryTable 3894 ClassLoader::initialize_module_path(THREAD); 3895 } 3896 #endif 3897 3898 #if INCLUDE_JVMCI 3899 if (force_JVMCI_intialization) { 3900 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3901 CompileBroker::compilation_init_phase2(); 3902 } 3903 #endif 3904 3905 // Always call even when there are not JVMTI environments yet, since environments 3906 // may be attached late and JVMTI must track phases of VM execution 3907 JvmtiExport::enter_live_phase(); 3908 3909 // Make perfmemory accessible 3910 PerfMemory::set_accessible(true); 3911 3912 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3913 JvmtiExport::post_vm_initialized(); 3914 3915 JFR_ONLY(Jfr::on_vm_start();) 3916 3917 #if INCLUDE_MANAGEMENT 3918 Management::initialize(THREAD); 3919 3920 if (HAS_PENDING_EXCEPTION) { 3921 // management agent fails to start possibly due to 3922 // configuration problem and is responsible for printing 3923 // stack trace if appropriate. Simply exit VM. 3924 vm_exit(1); 3925 } 3926 #endif // INCLUDE_MANAGEMENT 3927 3928 if (MemProfiling) MemProfiler::engage(); 3929 StatSampler::engage(); 3930 if (CheckJNICalls) JniPeriodicChecker::engage(); 3931 3932 BiasedLocking::init(); 3933 3934 #if INCLUDE_RTM_OPT 3935 RTMLockingCounters::init(); 3936 #endif 3937 3938 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3939 call_postVMInitHook(THREAD); 3940 // The Java side of PostVMInitHook.run must deal with all 3941 // exceptions and provide means of diagnosis. 3942 if (HAS_PENDING_EXCEPTION) { 3943 CLEAR_PENDING_EXCEPTION; 3944 } 3945 } 3946 3947 { 3948 MutexLocker ml(PeriodicTask_lock); 3949 // Make sure the WatcherThread can be started by WatcherThread::start() 3950 // or by dynamic enrollment. 3951 WatcherThread::make_startable(); 3952 // Start up the WatcherThread if there are any periodic tasks 3953 // NOTE: All PeriodicTasks should be registered by now. If they 3954 // aren't, late joiners might appear to start slowly (we might 3955 // take a while to process their first tick). 3956 if (PeriodicTask::num_tasks() > 0) { 3957 WatcherThread::start(); 3958 } 3959 } 3960 3961 create_vm_timer.end(); 3962 #ifdef ASSERT 3963 _vm_complete = true; 3964 #endif 3965 3966 if (DumpSharedSpaces) { 3967 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3968 ShouldNotReachHere(); 3969 } 3970 3971 return JNI_OK; 3972 } 3973 3974 // type for the Agent_OnLoad and JVM_OnLoad entry points 3975 extern "C" { 3976 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3977 } 3978 // Find a command line agent library and return its entry point for 3979 // -agentlib: -agentpath: -Xrun 3980 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3981 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3982 const char *on_load_symbols[], 3983 size_t num_symbol_entries) { 3984 OnLoadEntry_t on_load_entry = NULL; 3985 void *library = NULL; 3986 3987 if (!agent->valid()) { 3988 char buffer[JVM_MAXPATHLEN]; 3989 char ebuf[1024] = ""; 3990 const char *name = agent->name(); 3991 const char *msg = "Could not find agent library "; 3992 3993 // First check to see if agent is statically linked into executable 3994 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3995 library = agent->os_lib(); 3996 } else if (agent->is_absolute_path()) { 3997 library = os::dll_load(name, ebuf, sizeof ebuf); 3998 if (library == NULL) { 3999 const char *sub_msg = " in absolute path, with error: "; 4000 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4001 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4002 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4003 // If we can't find the agent, exit. 4004 vm_exit_during_initialization(buf, NULL); 4005 FREE_C_HEAP_ARRAY(char, buf); 4006 } 4007 } else { 4008 // Try to load the agent from the standard dll directory 4009 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4010 name)) { 4011 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4012 } 4013 if (library == NULL) { // Try the library path directory. 4014 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4015 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4016 } 4017 if (library == NULL) { 4018 const char *sub_msg = " on the library path, with error: "; 4019 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4020 4021 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4022 strlen(ebuf) + strlen(sub_msg2) + 1; 4023 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4024 if (!agent->is_instrument_lib()) { 4025 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4026 } else { 4027 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4028 } 4029 // If we can't find the agent, exit. 4030 vm_exit_during_initialization(buf, NULL); 4031 FREE_C_HEAP_ARRAY(char, buf); 4032 } 4033 } 4034 } 4035 agent->set_os_lib(library); 4036 agent->set_valid(); 4037 } 4038 4039 // Find the OnLoad function. 4040 on_load_entry = 4041 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4042 false, 4043 on_load_symbols, 4044 num_symbol_entries)); 4045 return on_load_entry; 4046 } 4047 4048 // Find the JVM_OnLoad entry point 4049 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4050 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4051 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4052 } 4053 4054 // Find the Agent_OnLoad entry point 4055 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4056 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4057 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4058 } 4059 4060 // For backwards compatibility with -Xrun 4061 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4062 // treated like -agentpath: 4063 // Must be called before agent libraries are created 4064 void Threads::convert_vm_init_libraries_to_agents() { 4065 AgentLibrary* agent; 4066 AgentLibrary* next; 4067 4068 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4069 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4070 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4071 4072 // If there is an JVM_OnLoad function it will get called later, 4073 // otherwise see if there is an Agent_OnLoad 4074 if (on_load_entry == NULL) { 4075 on_load_entry = lookup_agent_on_load(agent); 4076 if (on_load_entry != NULL) { 4077 // switch it to the agent list -- so that Agent_OnLoad will be called, 4078 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4079 Arguments::convert_library_to_agent(agent); 4080 } else { 4081 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4082 } 4083 } 4084 } 4085 } 4086 4087 // Create agents for -agentlib: -agentpath: and converted -Xrun 4088 // Invokes Agent_OnLoad 4089 // Called very early -- before JavaThreads exist 4090 void Threads::create_vm_init_agents() { 4091 extern struct JavaVM_ main_vm; 4092 AgentLibrary* agent; 4093 4094 JvmtiExport::enter_onload_phase(); 4095 4096 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4097 // CDS dumping does not support native JVMTI agent. 4098 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4099 if (DumpSharedSpaces) { 4100 if(!agent->is_instrument_lib()) { 4101 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4102 } else if (!AllowArchivingWithJavaAgent) { 4103 vm_exit_during_cds_dumping( 4104 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4105 } 4106 } 4107 4108 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4109 4110 if (on_load_entry != NULL) { 4111 // Invoke the Agent_OnLoad function 4112 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4113 if (err != JNI_OK) { 4114 vm_exit_during_initialization("agent library failed to init", agent->name()); 4115 } 4116 } else { 4117 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4118 } 4119 } 4120 4121 JvmtiExport::enter_primordial_phase(); 4122 } 4123 4124 extern "C" { 4125 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4126 } 4127 4128 void Threads::shutdown_vm_agents() { 4129 // Send any Agent_OnUnload notifications 4130 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4131 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4132 extern struct JavaVM_ main_vm; 4133 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4134 4135 // Find the Agent_OnUnload function. 4136 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4137 os::find_agent_function(agent, 4138 false, 4139 on_unload_symbols, 4140 num_symbol_entries)); 4141 4142 // Invoke the Agent_OnUnload function 4143 if (unload_entry != NULL) { 4144 JavaThread* thread = JavaThread::current(); 4145 ThreadToNativeFromVM ttn(thread); 4146 HandleMark hm(thread); 4147 (*unload_entry)(&main_vm); 4148 } 4149 } 4150 } 4151 4152 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4153 // Invokes JVM_OnLoad 4154 void Threads::create_vm_init_libraries() { 4155 extern struct JavaVM_ main_vm; 4156 AgentLibrary* agent; 4157 4158 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4159 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4160 4161 if (on_load_entry != NULL) { 4162 // Invoke the JVM_OnLoad function 4163 JavaThread* thread = JavaThread::current(); 4164 ThreadToNativeFromVM ttn(thread); 4165 HandleMark hm(thread); 4166 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4167 if (err != JNI_OK) { 4168 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4169 } 4170 } else { 4171 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4172 } 4173 } 4174 } 4175 4176 4177 // Last thread running calls java.lang.Shutdown.shutdown() 4178 void JavaThread::invoke_shutdown_hooks() { 4179 HandleMark hm(this); 4180 4181 // We could get here with a pending exception, if so clear it now. 4182 if (this->has_pending_exception()) { 4183 this->clear_pending_exception(); 4184 } 4185 4186 EXCEPTION_MARK; 4187 Klass* shutdown_klass = 4188 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4189 THREAD); 4190 if (shutdown_klass != NULL) { 4191 // SystemDictionary::resolve_or_null will return null if there was 4192 // an exception. If we cannot load the Shutdown class, just don't 4193 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4194 // won't be run. Note that if a shutdown hook was registered, 4195 // the Shutdown class would have already been loaded 4196 // (Runtime.addShutdownHook will load it). 4197 JavaValue result(T_VOID); 4198 JavaCalls::call_static(&result, 4199 shutdown_klass, 4200 vmSymbols::shutdown_method_name(), 4201 vmSymbols::void_method_signature(), 4202 THREAD); 4203 } 4204 CLEAR_PENDING_EXCEPTION; 4205 } 4206 4207 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4208 // the program falls off the end of main(). Another VM exit path is through 4209 // vm_exit() when the program calls System.exit() to return a value or when 4210 // there is a serious error in VM. The two shutdown paths are not exactly 4211 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4212 // and VM_Exit op at VM level. 4213 // 4214 // Shutdown sequence: 4215 // + Shutdown native memory tracking if it is on 4216 // + Wait until we are the last non-daemon thread to execute 4217 // <-- every thing is still working at this moment --> 4218 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4219 // shutdown hooks 4220 // + Call before_exit(), prepare for VM exit 4221 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4222 // currently the only user of this mechanism is File.deleteOnExit()) 4223 // > stop StatSampler, watcher thread, CMS threads, 4224 // post thread end and vm death events to JVMTI, 4225 // stop signal thread 4226 // + Call JavaThread::exit(), it will: 4227 // > release JNI handle blocks, remove stack guard pages 4228 // > remove this thread from Threads list 4229 // <-- no more Java code from this thread after this point --> 4230 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4231 // the compiler threads at safepoint 4232 // <-- do not use anything that could get blocked by Safepoint --> 4233 // + Disable tracing at JNI/JVM barriers 4234 // + Set _vm_exited flag for threads that are still running native code 4235 // + Call exit_globals() 4236 // > deletes tty 4237 // > deletes PerfMemory resources 4238 // + Delete this thread 4239 // + Return to caller 4240 4241 bool Threads::destroy_vm() { 4242 JavaThread* thread = JavaThread::current(); 4243 4244 #ifdef ASSERT 4245 _vm_complete = false; 4246 #endif 4247 // Wait until we are the last non-daemon thread to execute 4248 { MutexLocker nu(Threads_lock); 4249 while (Threads::number_of_non_daemon_threads() > 1) 4250 // This wait should make safepoint checks, wait without a timeout, 4251 // and wait as a suspend-equivalent condition. 4252 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4253 Mutex::_as_suspend_equivalent_flag); 4254 } 4255 4256 EventShutdown e; 4257 if (e.should_commit()) { 4258 e.set_reason("No remaining non-daemon Java threads"); 4259 e.commit(); 4260 } 4261 4262 // Hang forever on exit if we are reporting an error. 4263 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4264 os::infinite_sleep(); 4265 } 4266 os::wait_for_keypress_at_exit(); 4267 4268 // run Java level shutdown hooks 4269 thread->invoke_shutdown_hooks(); 4270 4271 before_exit(thread); 4272 4273 thread->exit(true); 4274 4275 // Stop VM thread. 4276 { 4277 // 4945125 The vm thread comes to a safepoint during exit. 4278 // GC vm_operations can get caught at the safepoint, and the 4279 // heap is unparseable if they are caught. Grab the Heap_lock 4280 // to prevent this. The GC vm_operations will not be able to 4281 // queue until after the vm thread is dead. After this point, 4282 // we'll never emerge out of the safepoint before the VM exits. 4283 4284 MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4285 4286 VMThread::wait_for_vm_thread_exit(); 4287 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4288 VMThread::destroy(); 4289 } 4290 4291 // Now, all Java threads are gone except daemon threads. Daemon threads 4292 // running Java code or in VM are stopped by the Safepoint. However, 4293 // daemon threads executing native code are still running. But they 4294 // will be stopped at native=>Java/VM barriers. Note that we can't 4295 // simply kill or suspend them, as it is inherently deadlock-prone. 4296 4297 VM_Exit::set_vm_exited(); 4298 4299 // Clean up ideal graph printers after the VMThread has started 4300 // the final safepoint which will block all the Compiler threads. 4301 // Note that this Thread has already logically exited so the 4302 // clean_up() function's use of a JavaThreadIteratorWithHandle 4303 // would be a problem except set_vm_exited() has remembered the 4304 // shutdown thread which is granted a policy exception. 4305 #if defined(COMPILER2) && !defined(PRODUCT) 4306 IdealGraphPrinter::clean_up(); 4307 #endif 4308 4309 notify_vm_shutdown(); 4310 4311 // exit_globals() will delete tty 4312 exit_globals(); 4313 4314 // We are after VM_Exit::set_vm_exited() so we can't call 4315 // thread->smr_delete() or we will block on the Threads_lock. 4316 // Deleting the shutdown thread here is safe because another 4317 // JavaThread cannot have an active ThreadsListHandle for 4318 // this JavaThread. 4319 delete thread; 4320 4321 #if INCLUDE_JVMCI 4322 if (JVMCICounterSize > 0) { 4323 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4324 } 4325 #endif 4326 4327 LogConfiguration::finalize(); 4328 4329 return true; 4330 } 4331 4332 4333 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4334 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4335 return is_supported_jni_version(version); 4336 } 4337 4338 4339 jboolean Threads::is_supported_jni_version(jint version) { 4340 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4341 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4342 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4343 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4344 if (version == JNI_VERSION_9) return JNI_TRUE; 4345 if (version == JNI_VERSION_10) return JNI_TRUE; 4346 return JNI_FALSE; 4347 } 4348 4349 4350 void Threads::add(JavaThread* p, bool force_daemon) { 4351 // The threads lock must be owned at this point 4352 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4353 4354 BarrierSet::barrier_set()->on_thread_attach(p); 4355 4356 p->set_next(_thread_list); 4357 _thread_list = p; 4358 4359 // Once a JavaThread is added to the Threads list, smr_delete() has 4360 // to be used to delete it. Otherwise we can just delete it directly. 4361 p->set_on_thread_list(); 4362 4363 _number_of_threads++; 4364 oop threadObj = p->threadObj(); 4365 bool daemon = true; 4366 // Bootstrapping problem: threadObj can be null for initial 4367 // JavaThread (or for threads attached via JNI) 4368 if ((!force_daemon) && !is_daemon((threadObj))) { 4369 _number_of_non_daemon_threads++; 4370 daemon = false; 4371 } 4372 4373 ThreadService::add_thread(p, daemon); 4374 4375 // Maintain fast thread list 4376 ThreadsSMRSupport::add_thread(p); 4377 4378 // Possible GC point. 4379 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4380 } 4381 4382 void Threads::remove(JavaThread* p) { 4383 4384 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4385 ObjectSynchronizer::omFlush(p); 4386 4387 // Extra scope needed for Thread_lock, so we can check 4388 // that we do not remove thread without safepoint code notice 4389 { MutexLocker ml(Threads_lock); 4390 4391 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4392 4393 // Maintain fast thread list 4394 ThreadsSMRSupport::remove_thread(p); 4395 4396 JavaThread* current = _thread_list; 4397 JavaThread* prev = NULL; 4398 4399 while (current != p) { 4400 prev = current; 4401 current = current->next(); 4402 } 4403 4404 if (prev) { 4405 prev->set_next(current->next()); 4406 } else { 4407 _thread_list = p->next(); 4408 } 4409 4410 _number_of_threads--; 4411 oop threadObj = p->threadObj(); 4412 bool daemon = true; 4413 if (!is_daemon(threadObj)) { 4414 _number_of_non_daemon_threads--; 4415 daemon = false; 4416 4417 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4418 // on destroy_vm will wake up. 4419 if (number_of_non_daemon_threads() == 1) { 4420 Threads_lock->notify_all(); 4421 } 4422 } 4423 ThreadService::remove_thread(p, daemon); 4424 4425 // Make sure that safepoint code disregard this thread. This is needed since 4426 // the thread might mess around with locks after this point. This can cause it 4427 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4428 // of this thread since it is removed from the queue. 4429 p->set_terminated_value(); 4430 } // unlock Threads_lock 4431 4432 // Since Events::log uses a lock, we grab it outside the Threads_lock 4433 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4434 } 4435 4436 // Operations on the Threads list for GC. These are not explicitly locked, 4437 // but the garbage collector must provide a safe context for them to run. 4438 // In particular, these things should never be called when the Threads_lock 4439 // is held by some other thread. (Note: the Safepoint abstraction also 4440 // uses the Threads_lock to guarantee this property. It also makes sure that 4441 // all threads gets blocked when exiting or starting). 4442 4443 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4444 ALL_JAVA_THREADS(p) { 4445 p->oops_do(f, cf); 4446 } 4447 VMThread::vm_thread()->oops_do(f, cf); 4448 } 4449 4450 void Threads::change_thread_claim_parity() { 4451 // Set the new claim parity. 4452 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4453 "Not in range."); 4454 _thread_claim_parity++; 4455 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4456 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4457 "Not in range."); 4458 } 4459 4460 #ifdef ASSERT 4461 void Threads::assert_all_threads_claimed() { 4462 ALL_JAVA_THREADS(p) { 4463 const int thread_parity = p->oops_do_parity(); 4464 assert((thread_parity == _thread_claim_parity), 4465 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4466 } 4467 VMThread* vmt = VMThread::vm_thread(); 4468 const int thread_parity = vmt->oops_do_parity(); 4469 assert((thread_parity == _thread_claim_parity), 4470 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4471 } 4472 #endif // ASSERT 4473 4474 class ParallelOopsDoThreadClosure : public ThreadClosure { 4475 private: 4476 OopClosure* _f; 4477 CodeBlobClosure* _cf; 4478 public: 4479 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4480 void do_thread(Thread* t) { 4481 t->oops_do(_f, _cf); 4482 } 4483 }; 4484 4485 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4486 ParallelOopsDoThreadClosure tc(f, cf); 4487 possibly_parallel_threads_do(is_par, &tc); 4488 } 4489 4490 void Threads::nmethods_do(CodeBlobClosure* cf) { 4491 ALL_JAVA_THREADS(p) { 4492 // This is used by the code cache sweeper to mark nmethods that are active 4493 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4494 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4495 if(!p->is_Code_cache_sweeper_thread()) { 4496 p->nmethods_do(cf); 4497 } 4498 } 4499 } 4500 4501 void Threads::metadata_do(void f(Metadata*)) { 4502 ALL_JAVA_THREADS(p) { 4503 p->metadata_do(f); 4504 } 4505 } 4506 4507 class ThreadHandlesClosure : public ThreadClosure { 4508 void (*_f)(Metadata*); 4509 public: 4510 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4511 virtual void do_thread(Thread* thread) { 4512 thread->metadata_handles_do(_f); 4513 } 4514 }; 4515 4516 void Threads::metadata_handles_do(void f(Metadata*)) { 4517 // Only walk the Handles in Thread. 4518 ThreadHandlesClosure handles_closure(f); 4519 threads_do(&handles_closure); 4520 } 4521 4522 void Threads::deoptimized_wrt_marked_nmethods() { 4523 ALL_JAVA_THREADS(p) { 4524 p->deoptimized_wrt_marked_nmethods(); 4525 } 4526 } 4527 4528 4529 // Get count Java threads that are waiting to enter the specified monitor. 4530 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4531 int count, 4532 address monitor) { 4533 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4534 4535 int i = 0; 4536 DO_JAVA_THREADS(t_list, p) { 4537 if (!p->can_call_java()) continue; 4538 4539 address pending = (address)p->current_pending_monitor(); 4540 if (pending == monitor) { // found a match 4541 if (i < count) result->append(p); // save the first count matches 4542 i++; 4543 } 4544 } 4545 4546 return result; 4547 } 4548 4549 4550 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4551 address owner) { 4552 // NULL owner means not locked so we can skip the search 4553 if (owner == NULL) return NULL; 4554 4555 DO_JAVA_THREADS(t_list, p) { 4556 // first, see if owner is the address of a Java thread 4557 if (owner == (address)p) return p; 4558 } 4559 4560 // Cannot assert on lack of success here since this function may be 4561 // used by code that is trying to report useful problem information 4562 // like deadlock detection. 4563 if (UseHeavyMonitors) return NULL; 4564 4565 // If we didn't find a matching Java thread and we didn't force use of 4566 // heavyweight monitors, then the owner is the stack address of the 4567 // Lock Word in the owning Java thread's stack. 4568 // 4569 JavaThread* the_owner = NULL; 4570 DO_JAVA_THREADS(t_list, q) { 4571 if (q->is_lock_owned(owner)) { 4572 the_owner = q; 4573 break; 4574 } 4575 } 4576 4577 // cannot assert on lack of success here; see above comment 4578 return the_owner; 4579 } 4580 4581 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4582 void Threads::print_on(outputStream* st, bool print_stacks, 4583 bool internal_format, bool print_concurrent_locks, 4584 bool print_extended_info) { 4585 char buf[32]; 4586 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4587 4588 st->print_cr("Full thread dump %s (%s %s):", 4589 VM_Version::vm_name(), 4590 VM_Version::vm_release(), 4591 VM_Version::vm_info_string()); 4592 st->cr(); 4593 4594 #if INCLUDE_SERVICES 4595 // Dump concurrent locks 4596 ConcurrentLocksDump concurrent_locks; 4597 if (print_concurrent_locks) { 4598 concurrent_locks.dump_at_safepoint(); 4599 } 4600 #endif // INCLUDE_SERVICES 4601 4602 ThreadsSMRSupport::print_info_on(st); 4603 st->cr(); 4604 4605 ALL_JAVA_THREADS(p) { 4606 ResourceMark rm; 4607 p->print_on(st, print_extended_info); 4608 if (print_stacks) { 4609 if (internal_format) { 4610 p->trace_stack(); 4611 } else { 4612 p->print_stack_on(st); 4613 } 4614 } 4615 st->cr(); 4616 #if INCLUDE_SERVICES 4617 if (print_concurrent_locks) { 4618 concurrent_locks.print_locks_on(p, st); 4619 } 4620 #endif // INCLUDE_SERVICES 4621 } 4622 4623 VMThread::vm_thread()->print_on(st); 4624 st->cr(); 4625 Universe::heap()->print_gc_threads_on(st); 4626 WatcherThread* wt = WatcherThread::watcher_thread(); 4627 if (wt != NULL) { 4628 wt->print_on(st); 4629 st->cr(); 4630 } 4631 4632 st->flush(); 4633 } 4634 4635 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4636 int buflen, bool* found_current) { 4637 if (this_thread != NULL) { 4638 bool is_current = (current == this_thread); 4639 *found_current = *found_current || is_current; 4640 st->print("%s", is_current ? "=>" : " "); 4641 4642 st->print(PTR_FORMAT, p2i(this_thread)); 4643 st->print(" "); 4644 this_thread->print_on_error(st, buf, buflen); 4645 st->cr(); 4646 } 4647 } 4648 4649 class PrintOnErrorClosure : public ThreadClosure { 4650 outputStream* _st; 4651 Thread* _current; 4652 char* _buf; 4653 int _buflen; 4654 bool* _found_current; 4655 public: 4656 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4657 int buflen, bool* found_current) : 4658 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4659 4660 virtual void do_thread(Thread* thread) { 4661 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4662 } 4663 }; 4664 4665 // Threads::print_on_error() is called by fatal error handler. It's possible 4666 // that VM is not at safepoint and/or current thread is inside signal handler. 4667 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4668 // memory (even in resource area), it might deadlock the error handler. 4669 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4670 int buflen) { 4671 ThreadsSMRSupport::print_info_on(st); 4672 st->cr(); 4673 4674 bool found_current = false; 4675 st->print_cr("Java Threads: ( => current thread )"); 4676 ALL_JAVA_THREADS(thread) { 4677 print_on_error(thread, st, current, buf, buflen, &found_current); 4678 } 4679 st->cr(); 4680 4681 st->print_cr("Other Threads:"); 4682 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4683 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4684 4685 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4686 Universe::heap()->gc_threads_do(&print_closure); 4687 4688 if (!found_current) { 4689 st->cr(); 4690 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4691 current->print_on_error(st, buf, buflen); 4692 st->cr(); 4693 } 4694 st->cr(); 4695 4696 st->print_cr("Threads with active compile tasks:"); 4697 print_threads_compiling(st, buf, buflen); 4698 } 4699 4700 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4701 ALL_JAVA_THREADS(thread) { 4702 if (thread->is_Compiler_thread()) { 4703 CompilerThread* ct = (CompilerThread*) thread; 4704 4705 // Keep task in local variable for NULL check. 4706 // ct->_task might be set to NULL by concurring compiler thread 4707 // because it completed the compilation. The task is never freed, 4708 // though, just returned to a free list. 4709 CompileTask* task = ct->task(); 4710 if (task != NULL) { 4711 thread->print_name_on_error(st, buf, buflen); 4712 st->print(" "); 4713 task->print(st, NULL, true, true); 4714 } 4715 } 4716 } 4717 } 4718 4719 4720 // Internal SpinLock and Mutex 4721 // Based on ParkEvent 4722 4723 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4724 // 4725 // We employ SpinLocks _only for low-contention, fixed-length 4726 // short-duration critical sections where we're concerned 4727 // about native mutex_t or HotSpot Mutex:: latency. 4728 // The mux construct provides a spin-then-block mutual exclusion 4729 // mechanism. 4730 // 4731 // Testing has shown that contention on the ListLock guarding gFreeList 4732 // is common. If we implement ListLock as a simple SpinLock it's common 4733 // for the JVM to devolve to yielding with little progress. This is true 4734 // despite the fact that the critical sections protected by ListLock are 4735 // extremely short. 4736 // 4737 // TODO-FIXME: ListLock should be of type SpinLock. 4738 // We should make this a 1st-class type, integrated into the lock 4739 // hierarchy as leaf-locks. Critically, the SpinLock structure 4740 // should have sufficient padding to avoid false-sharing and excessive 4741 // cache-coherency traffic. 4742 4743 4744 typedef volatile int SpinLockT; 4745 4746 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4747 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4748 return; // normal fast-path return 4749 } 4750 4751 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4752 int ctr = 0; 4753 int Yields = 0; 4754 for (;;) { 4755 while (*adr != 0) { 4756 ++ctr; 4757 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4758 if (Yields > 5) { 4759 os::naked_short_sleep(1); 4760 } else { 4761 os::naked_yield(); 4762 ++Yields; 4763 } 4764 } else { 4765 SpinPause(); 4766 } 4767 } 4768 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4769 } 4770 } 4771 4772 void Thread::SpinRelease(volatile int * adr) { 4773 assert(*adr != 0, "invariant"); 4774 OrderAccess::fence(); // guarantee at least release consistency. 4775 // Roach-motel semantics. 4776 // It's safe if subsequent LDs and STs float "up" into the critical section, 4777 // but prior LDs and STs within the critical section can't be allowed 4778 // to reorder or float past the ST that releases the lock. 4779 // Loads and stores in the critical section - which appear in program 4780 // order before the store that releases the lock - must also appear 4781 // before the store that releases the lock in memory visibility order. 4782 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4783 // the ST of 0 into the lock-word which releases the lock, so fence 4784 // more than covers this on all platforms. 4785 *adr = 0; 4786 } 4787 4788 // muxAcquire and muxRelease: 4789 // 4790 // * muxAcquire and muxRelease support a single-word lock-word construct. 4791 // The LSB of the word is set IFF the lock is held. 4792 // The remainder of the word points to the head of a singly-linked list 4793 // of threads blocked on the lock. 4794 // 4795 // * The current implementation of muxAcquire-muxRelease uses its own 4796 // dedicated Thread._MuxEvent instance. If we're interested in 4797 // minimizing the peak number of extant ParkEvent instances then 4798 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4799 // as certain invariants were satisfied. Specifically, care would need 4800 // to be taken with regards to consuming unpark() "permits". 4801 // A safe rule of thumb is that a thread would never call muxAcquire() 4802 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4803 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4804 // consume an unpark() permit intended for monitorenter, for instance. 4805 // One way around this would be to widen the restricted-range semaphore 4806 // implemented in park(). Another alternative would be to provide 4807 // multiple instances of the PlatformEvent() for each thread. One 4808 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4809 // 4810 // * Usage: 4811 // -- Only as leaf locks 4812 // -- for short-term locking only as muxAcquire does not perform 4813 // thread state transitions. 4814 // 4815 // Alternatives: 4816 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4817 // but with parking or spin-then-park instead of pure spinning. 4818 // * Use Taura-Oyama-Yonenzawa locks. 4819 // * It's possible to construct a 1-0 lock if we encode the lockword as 4820 // (List,LockByte). Acquire will CAS the full lockword while Release 4821 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4822 // acquiring threads use timers (ParkTimed) to detect and recover from 4823 // the stranding window. Thread/Node structures must be aligned on 256-byte 4824 // boundaries by using placement-new. 4825 // * Augment MCS with advisory back-link fields maintained with CAS(). 4826 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4827 // The validity of the backlinks must be ratified before we trust the value. 4828 // If the backlinks are invalid the exiting thread must back-track through the 4829 // the forward links, which are always trustworthy. 4830 // * Add a successor indication. The LockWord is currently encoded as 4831 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4832 // to provide the usual futile-wakeup optimization. 4833 // See RTStt for details. 4834 // 4835 4836 4837 const intptr_t LOCKBIT = 1; 4838 4839 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4840 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4841 if (w == 0) return; 4842 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4843 return; 4844 } 4845 4846 ParkEvent * const Self = Thread::current()->_MuxEvent; 4847 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4848 for (;;) { 4849 int its = (os::is_MP() ? 100 : 0) + 1; 4850 4851 // Optional spin phase: spin-then-park strategy 4852 while (--its >= 0) { 4853 w = *Lock; 4854 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4855 return; 4856 } 4857 } 4858 4859 Self->reset(); 4860 Self->OnList = intptr_t(Lock); 4861 // The following fence() isn't _strictly necessary as the subsequent 4862 // CAS() both serializes execution and ratifies the fetched *Lock value. 4863 OrderAccess::fence(); 4864 for (;;) { 4865 w = *Lock; 4866 if ((w & LOCKBIT) == 0) { 4867 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4868 Self->OnList = 0; // hygiene - allows stronger asserts 4869 return; 4870 } 4871 continue; // Interference -- *Lock changed -- Just retry 4872 } 4873 assert(w & LOCKBIT, "invariant"); 4874 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4875 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4876 } 4877 4878 while (Self->OnList != 0) { 4879 Self->park(); 4880 } 4881 } 4882 } 4883 4884 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4885 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4886 if (w == 0) return; 4887 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4888 return; 4889 } 4890 4891 ParkEvent * ReleaseAfter = NULL; 4892 if (ev == NULL) { 4893 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4894 } 4895 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4896 for (;;) { 4897 guarantee(ev->OnList == 0, "invariant"); 4898 int its = (os::is_MP() ? 100 : 0) + 1; 4899 4900 // Optional spin phase: spin-then-park strategy 4901 while (--its >= 0) { 4902 w = *Lock; 4903 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4904 if (ReleaseAfter != NULL) { 4905 ParkEvent::Release(ReleaseAfter); 4906 } 4907 return; 4908 } 4909 } 4910 4911 ev->reset(); 4912 ev->OnList = intptr_t(Lock); 4913 // The following fence() isn't _strictly necessary as the subsequent 4914 // CAS() both serializes execution and ratifies the fetched *Lock value. 4915 OrderAccess::fence(); 4916 for (;;) { 4917 w = *Lock; 4918 if ((w & LOCKBIT) == 0) { 4919 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4920 ev->OnList = 0; 4921 // We call ::Release while holding the outer lock, thus 4922 // artificially lengthening the critical section. 4923 // Consider deferring the ::Release() until the subsequent unlock(), 4924 // after we've dropped the outer lock. 4925 if (ReleaseAfter != NULL) { 4926 ParkEvent::Release(ReleaseAfter); 4927 } 4928 return; 4929 } 4930 continue; // Interference -- *Lock changed -- Just retry 4931 } 4932 assert(w & LOCKBIT, "invariant"); 4933 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4934 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4935 } 4936 4937 while (ev->OnList != 0) { 4938 ev->park(); 4939 } 4940 } 4941 } 4942 4943 // Release() must extract a successor from the list and then wake that thread. 4944 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4945 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4946 // Release() would : 4947 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4948 // (B) Extract a successor from the private list "in-hand" 4949 // (C) attempt to CAS() the residual back into *Lock over null. 4950 // If there were any newly arrived threads and the CAS() would fail. 4951 // In that case Release() would detach the RATs, re-merge the list in-hand 4952 // with the RATs and repeat as needed. Alternately, Release() might 4953 // detach and extract a successor, but then pass the residual list to the wakee. 4954 // The wakee would be responsible for reattaching and remerging before it 4955 // competed for the lock. 4956 // 4957 // Both "pop" and DMR are immune from ABA corruption -- there can be 4958 // multiple concurrent pushers, but only one popper or detacher. 4959 // This implementation pops from the head of the list. This is unfair, 4960 // but tends to provide excellent throughput as hot threads remain hot. 4961 // (We wake recently run threads first). 4962 // 4963 // All paths through muxRelease() will execute a CAS. 4964 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4965 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4966 // executed within the critical section are complete and globally visible before the 4967 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4968 void Thread::muxRelease(volatile intptr_t * Lock) { 4969 for (;;) { 4970 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4971 assert(w & LOCKBIT, "invariant"); 4972 if (w == LOCKBIT) return; 4973 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4974 assert(List != NULL, "invariant"); 4975 assert(List->OnList == intptr_t(Lock), "invariant"); 4976 ParkEvent * const nxt = List->ListNext; 4977 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4978 4979 // The following CAS() releases the lock and pops the head element. 4980 // The CAS() also ratifies the previously fetched lock-word value. 4981 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4982 continue; 4983 } 4984 List->OnList = 0; 4985 OrderAccess::fence(); 4986 List->unpark(); 4987 return; 4988 } 4989 } 4990 4991 4992 void Threads::verify() { 4993 ALL_JAVA_THREADS(p) { 4994 p->verify(); 4995 } 4996 VMThread* thread = VMThread::vm_thread(); 4997 if (thread != NULL) thread->verify(); 4998 }