1 /* 2 * Copyright (c) 1997, 2019, 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 "aot/aotLoader.hpp" 28 #include "classfile/classLoader.hpp" 29 #include "classfile/javaClasses.hpp" 30 #include "classfile/moduleEntry.hpp" 31 #include "classfile/systemDictionary.hpp" 32 #include "classfile/vmSymbols.hpp" 33 #include "code/codeCache.hpp" 34 #include "code/scopeDesc.hpp" 35 #include "compiler/compileBroker.hpp" 36 #include "compiler/compileTask.hpp" 37 #include "gc/shared/barrierSet.hpp" 38 #include "gc/shared/gcId.hpp" 39 #include "gc/shared/gcLocker.inline.hpp" 40 #include "gc/shared/workgroup.hpp" 41 #include "interpreter/interpreter.hpp" 42 #include "interpreter/linkResolver.hpp" 43 #include "interpreter/oopMapCache.hpp" 44 #include "jfr/jfrEvents.hpp" 45 #include "jvmtifiles/jvmtiEnv.hpp" 46 #include "logging/log.hpp" 47 #include "logging/logConfiguration.hpp" 48 #include "logging/logStream.hpp" 49 #include "memory/allocation.inline.hpp" 50 #include "memory/metaspaceShared.hpp" 51 #include "memory/oopFactory.hpp" 52 #include "memory/resourceArea.hpp" 53 #include "memory/universe.hpp" 54 #include "oops/access.inline.hpp" 55 #include "oops/instanceKlass.hpp" 56 #include "oops/objArrayOop.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "oops/symbol.hpp" 59 #include "oops/typeArrayOop.inline.hpp" 60 #include "oops/verifyOopClosure.hpp" 61 #include "prims/jvm_misc.hpp" 62 #include "prims/jvmtiExport.hpp" 63 #include "prims/jvmtiThreadState.hpp" 64 #include "runtime/arguments.hpp" 65 #include "runtime/atomic.hpp" 66 #include "runtime/biasedLocking.hpp" 67 #include "runtime/fieldDescriptor.inline.hpp" 68 #include "runtime/flags/jvmFlagConstraintList.hpp" 69 #include "runtime/flags/jvmFlagRangeList.hpp" 70 #include "runtime/flags/jvmFlagWriteableList.hpp" 71 #include "runtime/deoptimization.hpp" 72 #include "runtime/frame.inline.hpp" 73 #include "runtime/handles.inline.hpp" 74 #include "runtime/handshake.hpp" 75 #include "runtime/init.hpp" 76 #include "runtime/interfaceSupport.inline.hpp" 77 #include "runtime/java.hpp" 78 #include "runtime/javaCalls.hpp" 79 #include "runtime/jniHandles.inline.hpp" 80 #include "runtime/jniPeriodicChecker.hpp" 81 #include "runtime/memprofiler.hpp" 82 #include "runtime/mutexLocker.hpp" 83 #include "runtime/objectMonitor.hpp" 84 #include "runtime/orderAccess.hpp" 85 #include "runtime/osThread.hpp" 86 #include "runtime/prefetch.inline.hpp" 87 #include "runtime/safepoint.hpp" 88 #include "runtime/safepointMechanism.inline.hpp" 89 #include "runtime/safepointVerifiers.hpp" 90 #include "runtime/sharedRuntime.hpp" 91 #include "runtime/statSampler.hpp" 92 #include "runtime/stubRoutines.hpp" 93 #include "runtime/sweeper.hpp" 94 #include "runtime/task.hpp" 95 #include "runtime/thread.inline.hpp" 96 #include "runtime/threadCritical.hpp" 97 #include "runtime/threadSMR.inline.hpp" 98 #include "runtime/threadStatisticalInfo.hpp" 99 #include "runtime/timer.hpp" 100 #include "runtime/timerTrace.hpp" 101 #include "runtime/vframe.inline.hpp" 102 #include "runtime/vframeArray.hpp" 103 #include "runtime/vframe_hp.hpp" 104 #include "runtime/vmThread.hpp" 105 #include "runtime/vmOperations.hpp" 106 #include "runtime/vm_version.hpp" 107 #include "services/attachListener.hpp" 108 #include "services/management.hpp" 109 #include "services/memTracker.hpp" 110 #include "services/threadService.hpp" 111 #include "utilities/align.hpp" 112 #include "utilities/copy.hpp" 113 #include "utilities/defaultStream.hpp" 114 #include "utilities/dtrace.hpp" 115 #include "utilities/events.hpp" 116 #include "utilities/macros.hpp" 117 #include "utilities/preserveException.hpp" 118 #include "utilities/singleWriterSynchronizer.hpp" 119 #include "utilities/vmError.hpp" 120 #if INCLUDE_JVMCI 121 #include "jvmci/jvmci.hpp" 122 #include "jvmci/jvmciEnv.hpp" 123 #endif 124 #ifdef COMPILER1 125 #include "c1/c1_Compiler.hpp" 126 #endif 127 #ifdef COMPILER2 128 #include "opto/c2compiler.hpp" 129 #include "opto/idealGraphPrinter.hpp" 130 #endif 131 #if INCLUDE_RTM_OPT 132 #include "runtime/rtmLocking.hpp" 133 #endif 134 #if INCLUDE_JFR 135 #include "jfr/jfr.hpp" 136 #endif 137 138 // Initialization after module runtime initialization 139 void universe_post_module_init(); // must happen after call_initPhase2 140 141 #ifdef DTRACE_ENABLED 142 143 // Only bother with this argument setup if dtrace is available 144 145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) \ 149 { \ 150 ResourceMark rm(this); \ 151 int len = 0; \ 152 const char* name = (javathread)->get_thread_name(); \ 153 len = strlen(name); \ 154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 155 (char *) name, len, \ 156 java_lang_Thread::thread_id((javathread)->threadObj()), \ 157 (uintptr_t) (javathread)->osthread()->thread_id(), \ 158 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 159 } 160 161 #else // ndef DTRACE_ENABLED 162 163 #define DTRACE_THREAD_PROBE(probe, javathread) 164 165 #endif // ndef DTRACE_ENABLED 166 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY 168 // Current thread is maintained as a thread-local variable 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 170 #endif 171 172 // ======= Thread ======== 173 // Support for forcing alignment of thread objects for biased locking 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 175 if (UseBiasedLocking) { 176 const size_t alignment = markWord::biased_lock_alignment; 177 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 179 : AllocateHeap(aligned_size, flags, CURRENT_PC, 180 AllocFailStrategy::RETURN_NULL); 181 void* aligned_addr = align_up(real_malloc_addr, alignment); 182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 184 "JavaThread alignment code overflowed allocated storage"); 185 if (aligned_addr != real_malloc_addr) { 186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 187 p2i(real_malloc_addr), 188 p2i(aligned_addr)); 189 } 190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 191 return aligned_addr; 192 } else { 193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 195 } 196 } 197 198 void Thread::operator delete(void* p) { 199 if (UseBiasedLocking) { 200 FreeHeap(((Thread*) p)->_real_malloc_address); 201 } else { 202 FreeHeap(p); 203 } 204 } 205 206 void JavaThread::smr_delete() { 207 if (_on_thread_list) { 208 ThreadsSMRSupport::smr_delete(this); 209 } else { 210 delete this; 211 } 212 } 213 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 215 // JavaThread 216 217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;) 218 219 Thread::Thread() { 220 221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;) 222 223 // stack and get_thread 224 set_stack_base(NULL); 225 set_stack_size(0); 226 set_lgrp_id(-1); 227 DEBUG_ONLY(clear_suspendible_thread();) 228 229 // allocated data structures 230 set_osthread(NULL); 231 set_resource_area(new (mtThread)ResourceArea()); 232 DEBUG_ONLY(_current_resource_mark = NULL;) 233 set_handle_area(new (mtThread) HandleArea(NULL)); 234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 235 set_active_handles(NULL); 236 set_free_handle_block(NULL); 237 set_last_handle_mark(NULL); 238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 239 240 // Initial value of zero ==> never claimed. 241 _threads_do_token = 0; 242 _threads_hazard_ptr = NULL; 243 _threads_list_ptr = NULL; 244 _nested_threads_hazard_ptr_cnt = 0; 245 _rcu_counter = 0; 246 247 // the handle mark links itself to last_handle_mark 248 new HandleMark(this); 249 250 // plain initialization 251 debug_only(_owned_locks = NULL;) 252 NOT_PRODUCT(_no_safepoint_count = 0;) 253 NOT_PRODUCT(_skip_gcalot = false;) 254 _jvmti_env_iteration_count = 0; 255 set_allocated_bytes(0); 256 _vm_operation_started_count = 0; 257 _vm_operation_completed_count = 0; 258 _current_pending_monitor = NULL; 259 _current_pending_monitor_is_from_java = true; 260 _current_waiting_monitor = NULL; 261 _num_nested_signal = 0; 262 om_free_list = NULL; 263 om_free_count = 0; 264 om_free_provision = 32; 265 om_in_use_list = NULL; 266 om_in_use_count = 0; 267 268 #ifdef ASSERT 269 _visited_for_critical_count = false; 270 #endif 271 272 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 273 Monitor::_safepoint_check_sometimes); 274 _suspend_flags = 0; 275 276 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 277 _hashStateX = os::random(); 278 _hashStateY = 842502087; 279 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 280 _hashStateW = 273326509; 281 282 _OnTrap = 0; 283 _Stalled = 0; 284 _TypeTag = 0x2BAD; 285 286 // Many of the following fields are effectively final - immutable 287 // Note that nascent threads can't use the Native Monitor-Mutex 288 // construct until the _MutexEvent is initialized ... 289 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 290 // we might instead use a stack of ParkEvents that we could provision on-demand. 291 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 292 // and ::Release() 293 _ParkEvent = ParkEvent::Allocate(this); 294 _SleepEvent = ParkEvent::Allocate(this); 295 _MuxEvent = ParkEvent::Allocate(this); 296 297 #ifdef CHECK_UNHANDLED_OOPS 298 if (CheckUnhandledOops) { 299 _unhandled_oops = new UnhandledOops(this); 300 } 301 #endif // CHECK_UNHANDLED_OOPS 302 #ifdef ASSERT 303 if (UseBiasedLocking) { 304 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed"); 305 assert(this == _real_malloc_address || 306 this == align_up(_real_malloc_address, markWord::biased_lock_alignment), 307 "bug in forced alignment of thread objects"); 308 } 309 #endif // ASSERT 310 311 // Notify the barrier set that a thread is being created. The initial 312 // thread is created before the barrier set is available. The call to 313 // BarrierSet::on_thread_create() for this thread is therefore deferred 314 // to BarrierSet::set_barrier_set(). 315 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 316 if (barrier_set != NULL) { 317 barrier_set->on_thread_create(this); 318 } else { 319 // Only the main thread should be created before the barrier set 320 // and that happens just before Thread::current is set. No other thread 321 // can attach as the VM is not created yet, so they can't execute this code. 322 // If the main thread creates other threads before the barrier set that is an error. 323 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 324 } 325 } 326 327 void Thread::initialize_thread_current() { 328 #ifndef USE_LIBRARY_BASED_TLS_ONLY 329 assert(_thr_current == NULL, "Thread::current already initialized"); 330 _thr_current = this; 331 #endif 332 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 333 ThreadLocalStorage::set_thread(this); 334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 335 } 336 337 void Thread::clear_thread_current() { 338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 339 #ifndef USE_LIBRARY_BASED_TLS_ONLY 340 _thr_current = NULL; 341 #endif 342 ThreadLocalStorage::set_thread(NULL); 343 } 344 345 void Thread::record_stack_base_and_size() { 346 // Note: at this point, Thread object is not yet initialized. Do not rely on 347 // any members being initialized. Do not rely on Thread::current() being set. 348 // If possible, refrain from doing anything which may crash or assert since 349 // quite probably those crash dumps will be useless. 350 set_stack_base(os::current_stack_base()); 351 set_stack_size(os::current_stack_size()); 352 353 #ifdef SOLARIS 354 if (os::is_primordial_thread()) { 355 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 356 } 357 #endif 358 359 // Set stack limits after thread is initialized. 360 if (is_Java_thread()) { 361 ((JavaThread*) this)->set_stack_overflow_limit(); 362 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 363 } 364 } 365 366 #if INCLUDE_NMT 367 void Thread::register_thread_stack_with_NMT() { 368 MemTracker::record_thread_stack(stack_end(), stack_size()); 369 } 370 #endif // INCLUDE_NMT 371 372 void Thread::call_run() { 373 DEBUG_ONLY(_run_state = CALL_RUN;) 374 375 // At this point, Thread object should be fully initialized and 376 // Thread::current() should be set. 377 378 assert(Thread::current_or_null() != NULL, "current thread is unset"); 379 assert(Thread::current_or_null() == this, "current thread is wrong"); 380 381 // Perform common initialization actions 382 383 register_thread_stack_with_NMT(); 384 385 JFR_ONLY(Jfr::on_thread_start(this);) 386 387 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 388 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 389 os::current_thread_id(), p2i(stack_base() - stack_size()), 390 p2i(stack_base()), stack_size()/1024); 391 392 // Perform <ChildClass> initialization actions 393 DEBUG_ONLY(_run_state = PRE_RUN;) 394 this->pre_run(); 395 396 // Invoke <ChildClass>::run() 397 DEBUG_ONLY(_run_state = RUN;) 398 this->run(); 399 // Returned from <ChildClass>::run(). Thread finished. 400 401 // Perform common tear-down actions 402 403 assert(Thread::current_or_null() != NULL, "current thread is unset"); 404 assert(Thread::current_or_null() == this, "current thread is wrong"); 405 406 // Perform <ChildClass> tear-down actions 407 DEBUG_ONLY(_run_state = POST_RUN;) 408 this->post_run(); 409 410 // Note: at this point the thread object may already have deleted itself, 411 // so from here on do not dereference *this*. Not all thread types currently 412 // delete themselves when they terminate. But no thread should ever be deleted 413 // asynchronously with respect to its termination - that is what _run_state can 414 // be used to check. 415 416 assert(Thread::current_or_null() == NULL, "current thread still present"); 417 } 418 419 Thread::~Thread() { 420 421 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 422 // get started due to errors etc. Any active thread should at least reach post_run 423 // before it is deleted (usually in post_run()). 424 assert(_run_state == PRE_CALL_RUN || 425 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 426 "_run_state=%d", (int)_run_state); 427 428 // Notify the barrier set that a thread is being destroyed. Note that a barrier 429 // set might not be available if we encountered errors during bootstrapping. 430 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 431 if (barrier_set != NULL) { 432 barrier_set->on_thread_destroy(this); 433 } 434 435 // stack_base can be NULL if the thread is never started or exited before 436 // record_stack_base_and_size called. Although, we would like to ensure 437 // that all started threads do call record_stack_base_and_size(), there is 438 // not proper way to enforce that. 439 #if INCLUDE_NMT 440 if (_stack_base != NULL) { 441 MemTracker::release_thread_stack(stack_end(), stack_size()); 442 #ifdef ASSERT 443 set_stack_base(NULL); 444 #endif 445 } 446 #endif // INCLUDE_NMT 447 448 // deallocate data structures 449 delete resource_area(); 450 // since the handle marks are using the handle area, we have to deallocated the root 451 // handle mark before deallocating the thread's handle area, 452 assert(last_handle_mark() != NULL, "check we have an element"); 453 delete last_handle_mark(); 454 assert(last_handle_mark() == NULL, "check we have reached the end"); 455 456 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 457 // We NULL out the fields for good hygiene. 458 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 459 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 460 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 461 462 delete handle_area(); 463 delete metadata_handles(); 464 465 // SR_handler uses this as a termination indicator - 466 // needs to happen before os::free_thread() 467 delete _SR_lock; 468 _SR_lock = NULL; 469 470 // osthread() can be NULL, if creation of thread failed. 471 if (osthread() != NULL) os::free_thread(osthread()); 472 473 // Clear Thread::current if thread is deleting itself and it has not 474 // already been done. This must be done before the memory is deallocated. 475 // Needed to ensure JNI correctly detects non-attached threads. 476 if (this == Thread::current_or_null()) { 477 Thread::clear_thread_current(); 478 } 479 480 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 481 } 482 483 #ifdef ASSERT 484 // A JavaThread is considered "dangling" if it is not the current 485 // thread, has been added the Threads list, the system is not at a 486 // safepoint and the Thread is not "protected". 487 // 488 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 489 assert(!thread->is_Java_thread() || Thread::current() == thread || 490 !((JavaThread *) thread)->on_thread_list() || 491 SafepointSynchronize::is_at_safepoint() || 492 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 493 "possibility of dangling Thread pointer"); 494 } 495 #endif 496 497 ThreadPriority Thread::get_priority(const Thread* const thread) { 498 ThreadPriority priority; 499 // Can return an error! 500 (void)os::get_priority(thread, priority); 501 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 502 return priority; 503 } 504 505 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 506 debug_only(check_for_dangling_thread_pointer(thread);) 507 // Can return an error! 508 (void)os::set_priority(thread, priority); 509 } 510 511 512 void Thread::start(Thread* thread) { 513 // Start is different from resume in that its safety is guaranteed by context or 514 // being called from a Java method synchronized on the Thread object. 515 if (!DisableStartThread) { 516 if (thread->is_Java_thread()) { 517 // Initialize the thread state to RUNNABLE before starting this thread. 518 // Can not set it after the thread started because we do not know the 519 // exact thread state at that time. It could be in MONITOR_WAIT or 520 // in SLEEPING or some other state. 521 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 522 java_lang_Thread::RUNNABLE); 523 } 524 os::start_thread(thread); 525 } 526 } 527 528 // Enqueue a VM_Operation to do the job for us - sometime later 529 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 530 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 531 VMThread::execute(vm_stop); 532 } 533 534 535 // Check if an external suspend request has completed (or has been 536 // cancelled). Returns true if the thread is externally suspended and 537 // false otherwise. 538 // 539 // The bits parameter returns information about the code path through 540 // the routine. Useful for debugging: 541 // 542 // set in is_ext_suspend_completed(): 543 // 0x00000001 - routine was entered 544 // 0x00000010 - routine return false at end 545 // 0x00000100 - thread exited (return false) 546 // 0x00000200 - suspend request cancelled (return false) 547 // 0x00000400 - thread suspended (return true) 548 // 0x00001000 - thread is in a suspend equivalent state (return true) 549 // 0x00002000 - thread is native and walkable (return true) 550 // 0x00004000 - thread is native_trans and walkable (needed retry) 551 // 552 // set in wait_for_ext_suspend_completion(): 553 // 0x00010000 - routine was entered 554 // 0x00020000 - suspend request cancelled before loop (return false) 555 // 0x00040000 - thread suspended before loop (return true) 556 // 0x00080000 - suspend request cancelled in loop (return false) 557 // 0x00100000 - thread suspended in loop (return true) 558 // 0x00200000 - suspend not completed during retry loop (return false) 559 560 // Helper class for tracing suspend wait debug bits. 561 // 562 // 0x00000100 indicates that the target thread exited before it could 563 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 564 // 0x00080000 each indicate a cancelled suspend request so they don't 565 // count as wait failures either. 566 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 567 568 class TraceSuspendDebugBits : public StackObj { 569 private: 570 JavaThread * jt; 571 bool is_wait; 572 bool called_by_wait; // meaningful when !is_wait 573 uint32_t * bits; 574 575 public: 576 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 577 uint32_t *_bits) { 578 jt = _jt; 579 is_wait = _is_wait; 580 called_by_wait = _called_by_wait; 581 bits = _bits; 582 } 583 584 ~TraceSuspendDebugBits() { 585 if (!is_wait) { 586 #if 1 587 // By default, don't trace bits for is_ext_suspend_completed() calls. 588 // That trace is very chatty. 589 return; 590 #else 591 if (!called_by_wait) { 592 // If tracing for is_ext_suspend_completed() is enabled, then only 593 // trace calls to it from wait_for_ext_suspend_completion() 594 return; 595 } 596 #endif 597 } 598 599 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 600 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 601 MutexLocker ml(Threads_lock); // needed for get_thread_name() 602 ResourceMark rm; 603 604 tty->print_cr( 605 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 606 jt->get_thread_name(), *bits); 607 608 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 609 } 610 } 611 } 612 }; 613 #undef DEBUG_FALSE_BITS 614 615 616 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 617 uint32_t *bits) { 618 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 619 620 bool did_trans_retry = false; // only do thread_in_native_trans retry once 621 bool do_trans_retry; // flag to force the retry 622 623 *bits |= 0x00000001; 624 625 do { 626 do_trans_retry = false; 627 628 if (is_exiting()) { 629 // Thread is in the process of exiting. This is always checked 630 // first to reduce the risk of dereferencing a freed JavaThread. 631 *bits |= 0x00000100; 632 return false; 633 } 634 635 if (!is_external_suspend()) { 636 // Suspend request is cancelled. This is always checked before 637 // is_ext_suspended() to reduce the risk of a rogue resume 638 // confusing the thread that made the suspend request. 639 *bits |= 0x00000200; 640 return false; 641 } 642 643 if (is_ext_suspended()) { 644 // thread is suspended 645 *bits |= 0x00000400; 646 return true; 647 } 648 649 // Now that we no longer do hard suspends of threads running 650 // native code, the target thread can be changing thread state 651 // while we are in this routine: 652 // 653 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 654 // 655 // We save a copy of the thread state as observed at this moment 656 // and make our decision about suspend completeness based on the 657 // copy. This closes the race where the thread state is seen as 658 // _thread_in_native_trans in the if-thread_blocked check, but is 659 // seen as _thread_blocked in if-thread_in_native_trans check. 660 JavaThreadState save_state = thread_state(); 661 662 if (save_state == _thread_blocked && is_suspend_equivalent()) { 663 // If the thread's state is _thread_blocked and this blocking 664 // condition is known to be equivalent to a suspend, then we can 665 // consider the thread to be externally suspended. This means that 666 // the code that sets _thread_blocked has been modified to do 667 // self-suspension if the blocking condition releases. We also 668 // used to check for CONDVAR_WAIT here, but that is now covered by 669 // the _thread_blocked with self-suspension check. 670 // 671 // Return true since we wouldn't be here unless there was still an 672 // external suspend request. 673 *bits |= 0x00001000; 674 return true; 675 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 676 // Threads running native code will self-suspend on native==>VM/Java 677 // transitions. If its stack is walkable (should always be the case 678 // unless this function is called before the actual java_suspend() 679 // call), then the wait is done. 680 *bits |= 0x00002000; 681 return true; 682 } else if (!called_by_wait && !did_trans_retry && 683 save_state == _thread_in_native_trans && 684 frame_anchor()->walkable()) { 685 // The thread is transitioning from thread_in_native to another 686 // thread state. check_safepoint_and_suspend_for_native_trans() 687 // will force the thread to self-suspend. If it hasn't gotten 688 // there yet we may have caught the thread in-between the native 689 // code check above and the self-suspend. Lucky us. If we were 690 // called by wait_for_ext_suspend_completion(), then it 691 // will be doing the retries so we don't have to. 692 // 693 // Since we use the saved thread state in the if-statement above, 694 // there is a chance that the thread has already transitioned to 695 // _thread_blocked by the time we get here. In that case, we will 696 // make a single unnecessary pass through the logic below. This 697 // doesn't hurt anything since we still do the trans retry. 698 699 *bits |= 0x00004000; 700 701 // Once the thread leaves thread_in_native_trans for another 702 // thread state, we break out of this retry loop. We shouldn't 703 // need this flag to prevent us from getting back here, but 704 // sometimes paranoia is good. 705 did_trans_retry = true; 706 707 // We wait for the thread to transition to a more usable state. 708 for (int i = 1; i <= SuspendRetryCount; i++) { 709 // We used to do an "os::yield_all(i)" call here with the intention 710 // that yielding would increase on each retry. However, the parameter 711 // is ignored on Linux which means the yield didn't scale up. Waiting 712 // on the SR_lock below provides a much more predictable scale up for 713 // the delay. It also provides a simple/direct point to check for any 714 // safepoint requests from the VMThread 715 716 // temporarily drops SR_lock while doing wait with safepoint check 717 // (if we're a JavaThread - the WatcherThread can also call this) 718 // and increase delay with each retry 719 if (Thread::current()->is_Java_thread()) { 720 SR_lock()->wait(i * delay); 721 } else { 722 SR_lock()->wait_without_safepoint_check(i * delay); 723 } 724 725 // check the actual thread state instead of what we saved above 726 if (thread_state() != _thread_in_native_trans) { 727 // the thread has transitioned to another thread state so 728 // try all the checks (except this one) one more time. 729 do_trans_retry = true; 730 break; 731 } 732 } // end retry loop 733 734 735 } 736 } while (do_trans_retry); 737 738 *bits |= 0x00000010; 739 return false; 740 } 741 742 // Wait for an external suspend request to complete (or be cancelled). 743 // Returns true if the thread is externally suspended and false otherwise. 744 // 745 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 746 uint32_t *bits) { 747 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 748 false /* !called_by_wait */, bits); 749 750 // local flag copies to minimize SR_lock hold time 751 bool is_suspended; 752 bool pending; 753 uint32_t reset_bits; 754 755 // set a marker so is_ext_suspend_completed() knows we are the caller 756 *bits |= 0x00010000; 757 758 // We use reset_bits to reinitialize the bits value at the top of 759 // each retry loop. This allows the caller to make use of any 760 // unused bits for their own marking purposes. 761 reset_bits = *bits; 762 763 { 764 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 765 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 766 delay, bits); 767 pending = is_external_suspend(); 768 } 769 // must release SR_lock to allow suspension to complete 770 771 if (!pending) { 772 // A cancelled suspend request is the only false return from 773 // is_ext_suspend_completed() that keeps us from entering the 774 // retry loop. 775 *bits |= 0x00020000; 776 return false; 777 } 778 779 if (is_suspended) { 780 *bits |= 0x00040000; 781 return true; 782 } 783 784 for (int i = 1; i <= retries; i++) { 785 *bits = reset_bits; // reinit to only track last retry 786 787 // We used to do an "os::yield_all(i)" call here with the intention 788 // that yielding would increase on each retry. However, the parameter 789 // is ignored on Linux which means the yield didn't scale up. Waiting 790 // on the SR_lock below provides a much more predictable scale up for 791 // the delay. It also provides a simple/direct point to check for any 792 // safepoint requests from the VMThread 793 794 { 795 Thread* t = Thread::current(); 796 MonitorLocker ml(SR_lock(), 797 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 798 // wait with safepoint check (if we're a JavaThread - the WatcherThread 799 // can also call this) and increase delay with each retry 800 ml.wait(i * delay); 801 802 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 803 delay, bits); 804 805 // It is possible for the external suspend request to be cancelled 806 // (by a resume) before the actual suspend operation is completed. 807 // Refresh our local copy to see if we still need to wait. 808 pending = is_external_suspend(); 809 } 810 811 if (!pending) { 812 // A cancelled suspend request is the only false return from 813 // is_ext_suspend_completed() that keeps us from staying in the 814 // retry loop. 815 *bits |= 0x00080000; 816 return false; 817 } 818 819 if (is_suspended) { 820 *bits |= 0x00100000; 821 return true; 822 } 823 } // end retry loop 824 825 // thread did not suspend after all our retries 826 *bits |= 0x00200000; 827 return false; 828 } 829 830 // Called from API entry points which perform stack walking. If the 831 // associated JavaThread is the current thread, then wait_for_suspend 832 // is not used. Otherwise, it determines if we should wait for the 833 // "other" thread to complete external suspension. (NOTE: in future 834 // releases the suspension mechanism should be reimplemented so this 835 // is not necessary.) 836 // 837 bool 838 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 839 if (this != JavaThread::current()) { 840 // "other" threads require special handling. 841 if (wait_for_suspend) { 842 // We are allowed to wait for the external suspend to complete 843 // so give the other thread a chance to get suspended. 844 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 845 SuspendRetryDelay, bits)) { 846 // Didn't make it so let the caller know. 847 return false; 848 } 849 } 850 // We aren't allowed to wait for the external suspend to complete 851 // so if the other thread isn't externally suspended we need to 852 // let the caller know. 853 else if (!is_ext_suspend_completed_with_lock(bits)) { 854 return false; 855 } 856 } 857 858 return true; 859 } 860 861 void Thread::interrupt(Thread* thread) { 862 debug_only(check_for_dangling_thread_pointer(thread);) 863 os::interrupt(thread); 864 } 865 866 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 867 debug_only(check_for_dangling_thread_pointer(thread);) 868 // Note: If clear_interrupted==false, this simply fetches and 869 // returns the value of the field osthread()->interrupted(). 870 return os::is_interrupted(thread, clear_interrupted); 871 } 872 873 874 // GC Support 875 bool Thread::claim_par_threads_do(uintx claim_token) { 876 uintx token = _threads_do_token; 877 if (token != claim_token) { 878 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token); 879 if (res == token) { 880 return true; 881 } 882 guarantee(res == claim_token, "invariant"); 883 } 884 return false; 885 } 886 887 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 888 active_handles()->oops_do(f); 889 // Do oop for ThreadShadow 890 f->do_oop((oop*)&_pending_exception); 891 handle_area()->oops_do(f); 892 893 // We scan thread local monitor lists here, and the remaining global 894 // monitors in ObjectSynchronizer::oops_do(). 895 ObjectSynchronizer::thread_local_used_oops_do(this, f); 896 } 897 898 void Thread::metadata_handles_do(void f(Metadata*)) { 899 // Only walk the Handles in Thread. 900 if (metadata_handles() != NULL) { 901 for (int i = 0; i< metadata_handles()->length(); i++) { 902 f(metadata_handles()->at(i)); 903 } 904 } 905 } 906 907 void Thread::print_on(outputStream* st, bool print_extended_info) const { 908 // get_priority assumes osthread initialized 909 if (osthread() != NULL) { 910 int os_prio; 911 if (os::get_native_priority(this, &os_prio) == OS_OK) { 912 st->print("os_prio=%d ", os_prio); 913 } 914 915 st->print("cpu=%.2fms ", 916 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 917 ); 918 st->print("elapsed=%.2fs ", 919 _statistical_info.getElapsedTime() / 1000.0 920 ); 921 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 922 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 923 st->print("allocated=" SIZE_FORMAT "%s ", 924 byte_size_in_proper_unit(allocated_bytes), 925 proper_unit_for_byte_size(allocated_bytes) 926 ); 927 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 928 } 929 930 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 931 osthread()->print_on(st); 932 } 933 ThreadsSMRSupport::print_info_on(this, st); 934 st->print(" "); 935 debug_only(if (WizardMode) print_owned_locks_on(st);) 936 } 937 938 void Thread::print() const { print_on(tty); } 939 940 // Thread::print_on_error() is called by fatal error handler. Don't use 941 // any lock or allocate memory. 942 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 943 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 944 945 if (is_VM_thread()) { st->print("VMThread"); } 946 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 947 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 948 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 949 else { st->print("Thread"); } 950 951 if (is_Named_thread()) { 952 st->print(" \"%s\"", name()); 953 } 954 955 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 956 p2i(stack_end()), p2i(stack_base())); 957 958 if (osthread()) { 959 st->print(" [id=%d]", osthread()->thread_id()); 960 } 961 962 ThreadsSMRSupport::print_info_on(this, st); 963 } 964 965 void Thread::print_value_on(outputStream* st) const { 966 if (is_Named_thread()) { 967 st->print(" \"%s\" ", name()); 968 } 969 st->print(INTPTR_FORMAT, p2i(this)); // print address 970 } 971 972 #ifdef ASSERT 973 void Thread::print_owned_locks_on(outputStream* st) const { 974 Mutex* cur = _owned_locks; 975 if (cur == NULL) { 976 st->print(" (no locks) "); 977 } else { 978 st->print_cr(" Locks owned:"); 979 while (cur) { 980 cur->print_on(st); 981 cur = cur->next(); 982 } 983 } 984 } 985 986 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 987 void Thread::check_possible_safepoint() { 988 if (!is_Java_thread()) return; 989 990 if (_no_safepoint_count > 0) { 991 fatal("Possible safepoint reached by thread that does not allow it"); 992 } 993 #ifdef CHECK_UNHANDLED_OOPS 994 // Clear unhandled oops in JavaThreads so we get a crash right away. 995 clear_unhandled_oops(); 996 #endif // CHECK_UNHANDLED_OOPS 997 } 998 999 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 1000 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 1001 // no locks which allow_vm_block's are held 1002 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 1003 if (!is_Java_thread()) return; 1004 1005 check_possible_safepoint(); 1006 1007 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 1008 fatal("LEAF method calling lock?"); 1009 } 1010 1011 if (potential_vm_operation && !Universe::is_bootstrapping()) { 1012 // Make sure we do not hold any locks that the VM thread also uses. 1013 // This could potentially lead to deadlocks 1014 for (Mutex* cur = _owned_locks; cur; cur = cur->next()) { 1015 // Threads_lock is special, since the safepoint synchronization will not start before this is 1016 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1017 // since it is used to transfer control between JavaThreads and the VMThread 1018 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1019 if ((cur->allow_vm_block() && 1020 cur != Threads_lock && 1021 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1022 cur != VMOperationRequest_lock && 1023 cur != VMOperationQueue_lock) || 1024 cur->rank() == Mutex::special) { 1025 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1026 } 1027 } 1028 } 1029 1030 if (GCALotAtAllSafepoints) { 1031 // We could enter a safepoint here and thus have a gc 1032 InterfaceSupport::check_gc_alot(); 1033 } 1034 } 1035 #endif // ASSERT 1036 1037 bool Thread::is_in_stack(address adr) const { 1038 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1039 address end = os::current_stack_pointer(); 1040 // Allow non Java threads to call this without stack_base 1041 if (_stack_base == NULL) return true; 1042 if (stack_base() >= adr && adr >= end) return true; 1043 1044 return false; 1045 } 1046 1047 bool Thread::is_in_usable_stack(address adr) const { 1048 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1049 size_t usable_stack_size = _stack_size - stack_guard_size; 1050 1051 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1052 } 1053 1054 1055 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1056 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1057 // used for compilation in the future. If that change is made, the need for these methods 1058 // should be revisited, and they should be removed if possible. 1059 1060 bool Thread::is_lock_owned(address adr) const { 1061 return on_local_stack(adr); 1062 } 1063 1064 bool Thread::set_as_starting_thread() { 1065 assert(_starting_thread == NULL, "already initialized: " 1066 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1067 // NOTE: this must be called inside the main thread. 1068 DEBUG_ONLY(_starting_thread = this;) 1069 return os::create_main_thread((JavaThread*)this); 1070 } 1071 1072 static void initialize_class(Symbol* class_name, TRAPS) { 1073 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1074 InstanceKlass::cast(klass)->initialize(CHECK); 1075 } 1076 1077 1078 // Creates the initial ThreadGroup 1079 static Handle create_initial_thread_group(TRAPS) { 1080 Handle system_instance = JavaCalls::construct_new_instance( 1081 SystemDictionary::ThreadGroup_klass(), 1082 vmSymbols::void_method_signature(), 1083 CHECK_NH); 1084 Universe::set_system_thread_group(system_instance()); 1085 1086 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1087 Handle main_instance = JavaCalls::construct_new_instance( 1088 SystemDictionary::ThreadGroup_klass(), 1089 vmSymbols::threadgroup_string_void_signature(), 1090 system_instance, 1091 string, 1092 CHECK_NH); 1093 return main_instance; 1094 } 1095 1096 // Creates the initial Thread 1097 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1098 TRAPS) { 1099 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1100 assert(ik->is_initialized(), "must be"); 1101 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1102 1103 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1104 // constructor calls Thread.current(), which must be set here for the 1105 // initial thread. 1106 java_lang_Thread::set_thread(thread_oop(), thread); 1107 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1108 thread->set_threadObj(thread_oop()); 1109 1110 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1111 1112 JavaValue result(T_VOID); 1113 JavaCalls::call_special(&result, thread_oop, 1114 ik, 1115 vmSymbols::object_initializer_name(), 1116 vmSymbols::threadgroup_string_void_signature(), 1117 thread_group, 1118 string, 1119 CHECK_NULL); 1120 return thread_oop(); 1121 } 1122 1123 char java_runtime_name[128] = ""; 1124 char java_runtime_version[128] = ""; 1125 1126 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1127 static const char* get_java_runtime_name(TRAPS) { 1128 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1129 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1130 fieldDescriptor fd; 1131 bool found = k != NULL && 1132 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1133 vmSymbols::string_signature(), &fd); 1134 if (found) { 1135 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1136 if (name_oop == NULL) { 1137 return NULL; 1138 } 1139 const char* name = java_lang_String::as_utf8_string(name_oop, 1140 java_runtime_name, 1141 sizeof(java_runtime_name)); 1142 return name; 1143 } else { 1144 return NULL; 1145 } 1146 } 1147 1148 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1149 static const char* get_java_runtime_version(TRAPS) { 1150 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1151 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1152 fieldDescriptor fd; 1153 bool found = k != NULL && 1154 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1155 vmSymbols::string_signature(), &fd); 1156 if (found) { 1157 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1158 if (name_oop == NULL) { 1159 return NULL; 1160 } 1161 const char* name = java_lang_String::as_utf8_string(name_oop, 1162 java_runtime_version, 1163 sizeof(java_runtime_version)); 1164 return name; 1165 } else { 1166 return NULL; 1167 } 1168 } 1169 1170 // General purpose hook into Java code, run once when the VM is initialized. 1171 // The Java library method itself may be changed independently from the VM. 1172 static void call_postVMInitHook(TRAPS) { 1173 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1174 if (klass != NULL) { 1175 JavaValue result(T_VOID); 1176 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1177 vmSymbols::void_method_signature(), 1178 CHECK); 1179 } 1180 } 1181 1182 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1183 bool daemon, TRAPS) { 1184 assert(thread_group.not_null(), "thread group should be specified"); 1185 assert(threadObj() == NULL, "should only create Java thread object once"); 1186 1187 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1188 assert(ik->is_initialized(), "must be"); 1189 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1190 1191 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1192 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1193 // constructor calls Thread.current(), which must be set here. 1194 java_lang_Thread::set_thread(thread_oop(), this); 1195 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1196 set_threadObj(thread_oop()); 1197 1198 JavaValue result(T_VOID); 1199 if (thread_name != NULL) { 1200 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1201 // Thread gets assigned specified name and null target 1202 JavaCalls::call_special(&result, 1203 thread_oop, 1204 ik, 1205 vmSymbols::object_initializer_name(), 1206 vmSymbols::threadgroup_string_void_signature(), 1207 thread_group, 1208 name, 1209 THREAD); 1210 } else { 1211 // Thread gets assigned name "Thread-nnn" and null target 1212 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1213 JavaCalls::call_special(&result, 1214 thread_oop, 1215 ik, 1216 vmSymbols::object_initializer_name(), 1217 vmSymbols::threadgroup_runnable_void_signature(), 1218 thread_group, 1219 Handle(), 1220 THREAD); 1221 } 1222 1223 1224 if (daemon) { 1225 java_lang_Thread::set_daemon(thread_oop()); 1226 } 1227 1228 if (HAS_PENDING_EXCEPTION) { 1229 return; 1230 } 1231 1232 Klass* group = SystemDictionary::ThreadGroup_klass(); 1233 Handle threadObj(THREAD, this->threadObj()); 1234 1235 JavaCalls::call_special(&result, 1236 thread_group, 1237 group, 1238 vmSymbols::add_method_name(), 1239 vmSymbols::thread_void_signature(), 1240 threadObj, // Arg 1 1241 THREAD); 1242 } 1243 1244 // List of all NonJavaThreads and safe iteration over that list. 1245 1246 class NonJavaThread::List { 1247 public: 1248 NonJavaThread* volatile _head; 1249 SingleWriterSynchronizer _protect; 1250 1251 List() : _head(NULL), _protect() {} 1252 }; 1253 1254 NonJavaThread::List NonJavaThread::_the_list; 1255 1256 NonJavaThread::Iterator::Iterator() : 1257 _protect_enter(_the_list._protect.enter()), 1258 _current(OrderAccess::load_acquire(&_the_list._head)) 1259 {} 1260 1261 NonJavaThread::Iterator::~Iterator() { 1262 _the_list._protect.exit(_protect_enter); 1263 } 1264 1265 void NonJavaThread::Iterator::step() { 1266 assert(!end(), "precondition"); 1267 _current = OrderAccess::load_acquire(&_current->_next); 1268 } 1269 1270 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1271 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1272 } 1273 1274 NonJavaThread::~NonJavaThread() { } 1275 1276 void NonJavaThread::add_to_the_list() { 1277 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1278 // Initialize BarrierSet-related data before adding to list. 1279 BarrierSet::barrier_set()->on_thread_attach(this); 1280 OrderAccess::release_store(&_next, _the_list._head); 1281 OrderAccess::release_store(&_the_list._head, this); 1282 } 1283 1284 void NonJavaThread::remove_from_the_list() { 1285 { 1286 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1287 // Cleanup BarrierSet-related data before removing from list. 1288 BarrierSet::barrier_set()->on_thread_detach(this); 1289 NonJavaThread* volatile* p = &_the_list._head; 1290 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1291 if (t == this) { 1292 *p = _next; 1293 break; 1294 } 1295 } 1296 } 1297 // Wait for any in-progress iterators. Concurrent synchronize is not 1298 // allowed, so do it while holding a dedicated lock. Outside and distinct 1299 // from NJTList_lock in case an iteration attempts to lock it. 1300 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1301 _the_list._protect.synchronize(); 1302 _next = NULL; // Safe to drop the link now. 1303 } 1304 1305 void NonJavaThread::pre_run() { 1306 add_to_the_list(); 1307 1308 // This is slightly odd in that NamedThread is a subclass, but 1309 // in fact name() is defined in Thread 1310 assert(this->name() != NULL, "thread name was not set before it was started"); 1311 this->set_native_thread_name(this->name()); 1312 } 1313 1314 void NonJavaThread::post_run() { 1315 JFR_ONLY(Jfr::on_thread_exit(this);) 1316 remove_from_the_list(); 1317 // Ensure thread-local-storage is cleared before termination. 1318 Thread::clear_thread_current(); 1319 } 1320 1321 // NamedThread -- non-JavaThread subclasses with multiple 1322 // uniquely named instances should derive from this. 1323 NamedThread::NamedThread() : 1324 NonJavaThread(), 1325 _name(NULL), 1326 _processed_thread(NULL), 1327 _gc_id(GCId::undefined()) 1328 {} 1329 1330 NamedThread::~NamedThread() { 1331 if (_name != NULL) { 1332 FREE_C_HEAP_ARRAY(char, _name); 1333 _name = NULL; 1334 } 1335 } 1336 1337 void NamedThread::set_name(const char* format, ...) { 1338 guarantee(_name == NULL, "Only get to set name once."); 1339 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1340 guarantee(_name != NULL, "alloc failure"); 1341 va_list ap; 1342 va_start(ap, format); 1343 jio_vsnprintf(_name, max_name_len, format, ap); 1344 va_end(ap); 1345 } 1346 1347 void NamedThread::print_on(outputStream* st) const { 1348 st->print("\"%s\" ", name()); 1349 Thread::print_on(st); 1350 st->cr(); 1351 } 1352 1353 1354 // ======= WatcherThread ======== 1355 1356 // The watcher thread exists to simulate timer interrupts. It should 1357 // be replaced by an abstraction over whatever native support for 1358 // timer interrupts exists on the platform. 1359 1360 WatcherThread* WatcherThread::_watcher_thread = NULL; 1361 bool WatcherThread::_startable = false; 1362 volatile bool WatcherThread::_should_terminate = false; 1363 1364 WatcherThread::WatcherThread() : NonJavaThread() { 1365 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1366 if (os::create_thread(this, os::watcher_thread)) { 1367 _watcher_thread = this; 1368 1369 // Set the watcher thread to the highest OS priority which should not be 1370 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1371 // is created. The only normal thread using this priority is the reference 1372 // handler thread, which runs for very short intervals only. 1373 // If the VMThread's priority is not lower than the WatcherThread profiling 1374 // will be inaccurate. 1375 os::set_priority(this, MaxPriority); 1376 if (!DisableStartThread) { 1377 os::start_thread(this); 1378 } 1379 } 1380 } 1381 1382 int WatcherThread::sleep() const { 1383 // The WatcherThread does not participate in the safepoint protocol 1384 // for the PeriodicTask_lock because it is not a JavaThread. 1385 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1386 1387 if (_should_terminate) { 1388 // check for termination before we do any housekeeping or wait 1389 return 0; // we did not sleep. 1390 } 1391 1392 // remaining will be zero if there are no tasks, 1393 // causing the WatcherThread to sleep until a task is 1394 // enrolled 1395 int remaining = PeriodicTask::time_to_wait(); 1396 int time_slept = 0; 1397 1398 // we expect this to timeout - we only ever get unparked when 1399 // we should terminate or when a new task has been enrolled 1400 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1401 1402 jlong time_before_loop = os::javaTimeNanos(); 1403 1404 while (true) { 1405 bool timedout = ml.wait(remaining); 1406 jlong now = os::javaTimeNanos(); 1407 1408 if (remaining == 0) { 1409 // if we didn't have any tasks we could have waited for a long time 1410 // consider the time_slept zero and reset time_before_loop 1411 time_slept = 0; 1412 time_before_loop = now; 1413 } else { 1414 // need to recalculate since we might have new tasks in _tasks 1415 time_slept = (int) ((now - time_before_loop) / 1000000); 1416 } 1417 1418 // Change to task list or spurious wakeup of some kind 1419 if (timedout || _should_terminate) { 1420 break; 1421 } 1422 1423 remaining = PeriodicTask::time_to_wait(); 1424 if (remaining == 0) { 1425 // Last task was just disenrolled so loop around and wait until 1426 // another task gets enrolled 1427 continue; 1428 } 1429 1430 remaining -= time_slept; 1431 if (remaining <= 0) { 1432 break; 1433 } 1434 } 1435 1436 return time_slept; 1437 } 1438 1439 void WatcherThread::run() { 1440 assert(this == watcher_thread(), "just checking"); 1441 1442 this->set_active_handles(JNIHandleBlock::allocate_block()); 1443 while (true) { 1444 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1445 assert(watcher_thread() == this, "thread consistency check"); 1446 1447 // Calculate how long it'll be until the next PeriodicTask work 1448 // should be done, and sleep that amount of time. 1449 int time_waited = sleep(); 1450 1451 if (VMError::is_error_reported()) { 1452 // A fatal error has happened, the error handler(VMError::report_and_die) 1453 // should abort JVM after creating an error log file. However in some 1454 // rare cases, the error handler itself might deadlock. Here periodically 1455 // check for error reporting timeouts, and if it happens, just proceed to 1456 // abort the VM. 1457 1458 // This code is in WatcherThread because WatcherThread wakes up 1459 // periodically so the fatal error handler doesn't need to do anything; 1460 // also because the WatcherThread is less likely to crash than other 1461 // threads. 1462 1463 for (;;) { 1464 // Note: we use naked sleep in this loop because we want to avoid using 1465 // any kind of VM infrastructure which may be broken at this point. 1466 if (VMError::check_timeout()) { 1467 // We hit error reporting timeout. Error reporting was interrupted and 1468 // will be wrapping things up now (closing files etc). Give it some more 1469 // time, then quit the VM. 1470 os::naked_short_sleep(200); 1471 // Print a message to stderr. 1472 fdStream err(defaultStream::output_fd()); 1473 err.print_raw_cr("# [ timer expired, abort... ]"); 1474 // skip atexit/vm_exit/vm_abort hooks 1475 os::die(); 1476 } 1477 1478 // Wait a second, then recheck for timeout. 1479 os::naked_short_sleep(999); 1480 } 1481 } 1482 1483 if (_should_terminate) { 1484 // check for termination before posting the next tick 1485 break; 1486 } 1487 1488 PeriodicTask::real_time_tick(time_waited); 1489 } 1490 1491 // Signal that it is terminated 1492 { 1493 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1494 _watcher_thread = NULL; 1495 Terminator_lock->notify_all(); 1496 } 1497 } 1498 1499 void WatcherThread::start() { 1500 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1501 1502 if (watcher_thread() == NULL && _startable) { 1503 _should_terminate = false; 1504 // Create the single instance of WatcherThread 1505 new WatcherThread(); 1506 } 1507 } 1508 1509 void WatcherThread::make_startable() { 1510 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1511 _startable = true; 1512 } 1513 1514 void WatcherThread::stop() { 1515 { 1516 // Follow normal safepoint aware lock enter protocol since the 1517 // WatcherThread is stopped by another JavaThread. 1518 MutexLocker ml(PeriodicTask_lock); 1519 _should_terminate = true; 1520 1521 WatcherThread* watcher = watcher_thread(); 1522 if (watcher != NULL) { 1523 // unpark the WatcherThread so it can see that it should terminate 1524 watcher->unpark(); 1525 } 1526 } 1527 1528 MonitorLocker mu(Terminator_lock); 1529 1530 while (watcher_thread() != NULL) { 1531 // This wait should make safepoint checks, wait without a timeout, 1532 // and wait as a suspend-equivalent condition. 1533 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1534 } 1535 } 1536 1537 void WatcherThread::unpark() { 1538 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1539 PeriodicTask_lock->notify(); 1540 } 1541 1542 void WatcherThread::print_on(outputStream* st) const { 1543 st->print("\"%s\" ", name()); 1544 Thread::print_on(st); 1545 st->cr(); 1546 } 1547 1548 // ======= JavaThread ======== 1549 1550 #if INCLUDE_JVMCI 1551 1552 jlong* JavaThread::_jvmci_old_thread_counters; 1553 1554 bool jvmci_counters_include(JavaThread* thread) { 1555 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1556 } 1557 1558 void JavaThread::collect_counters(jlong* array, int length) { 1559 assert(length == JVMCICounterSize, "wrong value"); 1560 for (int i = 0; i < length; i++) { 1561 array[i] = _jvmci_old_thread_counters[i]; 1562 } 1563 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1564 if (jvmci_counters_include(tp)) { 1565 for (int i = 0; i < length; i++) { 1566 array[i] += tp->_jvmci_counters[i]; 1567 } 1568 } 1569 } 1570 } 1571 1572 // Attempt to enlarge the array for per thread counters. 1573 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1574 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1575 if (new_counters == NULL) { 1576 return NULL; 1577 } 1578 if (old_counters == NULL) { 1579 old_counters = new_counters; 1580 memset(old_counters, 0, sizeof(jlong) * new_size); 1581 } else { 1582 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1583 new_counters[i] = old_counters[i]; 1584 } 1585 if (new_size > current_size) { 1586 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1587 } 1588 FREE_C_HEAP_ARRAY(jlong, old_counters); 1589 } 1590 return new_counters; 1591 } 1592 1593 // Attempt to enlarge the array for per thread counters. 1594 bool JavaThread::resize_counters(int current_size, int new_size) { 1595 jlong* new_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1596 if (new_counters == NULL) { 1597 return false; 1598 } else { 1599 _jvmci_counters = new_counters; 1600 return true; 1601 } 1602 } 1603 1604 class VM_JVMCIResizeCounters : public VM_Operation { 1605 private: 1606 int _new_size; 1607 bool _failed; 1608 1609 public: 1610 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size), _failed(false) { } 1611 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; } 1612 bool allow_nested_vm_operations() const { return true; } 1613 void doit() { 1614 // Resize the old thread counters array 1615 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size); 1616 if (new_counters == NULL) { 1617 _failed = true; 1618 return; 1619 } else { 1620 JavaThread::_jvmci_old_thread_counters = new_counters; 1621 } 1622 1623 // Now resize each threads array 1624 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1625 if (!tp->resize_counters(JVMCICounterSize, _new_size)) { 1626 _failed = true; 1627 break; 1628 } 1629 } 1630 if (!_failed) { 1631 JVMCICounterSize = _new_size; 1632 } 1633 } 1634 1635 bool failed() { return _failed; } 1636 }; 1637 1638 bool JavaThread::resize_all_jvmci_counters(int new_size) { 1639 VM_JVMCIResizeCounters op(new_size); 1640 VMThread::execute(&op); 1641 return !op.failed(); 1642 } 1643 1644 #endif // INCLUDE_JVMCI 1645 1646 // A JavaThread is a normal Java thread 1647 1648 void JavaThread::initialize() { 1649 // Initialize fields 1650 1651 set_saved_exception_pc(NULL); 1652 set_threadObj(NULL); 1653 _anchor.clear(); 1654 set_entry_point(NULL); 1655 set_jni_functions(jni_functions()); 1656 set_callee_target(NULL); 1657 set_vm_result(NULL); 1658 set_vm_result_2(NULL); 1659 set_vframe_array_head(NULL); 1660 set_vframe_array_last(NULL); 1661 set_deferred_locals(NULL); 1662 set_deopt_mark(NULL); 1663 set_deopt_compiled_method(NULL); 1664 set_monitor_chunks(NULL); 1665 _on_thread_list = false; 1666 set_thread_state(_thread_new); 1667 _terminated = _not_terminated; 1668 _array_for_gc = NULL; 1669 _suspend_equivalent = false; 1670 _in_deopt_handler = 0; 1671 _doing_unsafe_access = false; 1672 _stack_guard_state = stack_guard_unused; 1673 #if INCLUDE_JVMCI 1674 _pending_monitorenter = false; 1675 _pending_deoptimization = -1; 1676 _pending_failed_speculation = 0; 1677 _pending_transfer_to_interpreter = false; 1678 _in_retryable_allocation = false; 1679 _jvmci._alternate_call_target = NULL; 1680 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1681 _jvmci_counters = NULL; 1682 if (JVMCICounterSize > 0) { 1683 resize_counters(0, (int) JVMCICounterSize); 1684 } 1685 #endif // INCLUDE_JVMCI 1686 _reserved_stack_activation = NULL; // stack base not known yet 1687 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1688 _exception_pc = 0; 1689 _exception_handler_pc = 0; 1690 _is_method_handle_return = 0; 1691 _jvmti_thread_state= NULL; 1692 _should_post_on_exceptions_flag = JNI_FALSE; 1693 _interp_only_mode = 0; 1694 _special_runtime_exit_condition = _no_async_condition; 1695 _pending_async_exception = NULL; 1696 _thread_stat = NULL; 1697 _thread_stat = new ThreadStatistics(); 1698 _jni_active_critical = 0; 1699 _pending_jni_exception_check_fn = NULL; 1700 _do_not_unlock_if_synchronized = false; 1701 _cached_monitor_info = NULL; 1702 _parker = Parker::Allocate(this); 1703 1704 // Setup safepoint state info for this thread 1705 ThreadSafepointState::create(this); 1706 1707 debug_only(_java_call_counter = 0); 1708 1709 // JVMTI PopFrame support 1710 _popframe_condition = popframe_inactive; 1711 _popframe_preserved_args = NULL; 1712 _popframe_preserved_args_size = 0; 1713 _frames_to_pop_failed_realloc = 0; 1714 1715 if (SafepointMechanism::uses_thread_local_poll()) { 1716 SafepointMechanism::initialize_header(this); 1717 } 1718 1719 _class_to_be_initialized = NULL; 1720 1721 pd_initialize(); 1722 } 1723 1724 JavaThread::JavaThread(bool is_attaching_via_jni) : 1725 Thread() { 1726 initialize(); 1727 if (is_attaching_via_jni) { 1728 _jni_attach_state = _attaching_via_jni; 1729 } else { 1730 _jni_attach_state = _not_attaching_via_jni; 1731 } 1732 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1733 } 1734 1735 bool JavaThread::reguard_stack(address cur_sp) { 1736 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1737 && _stack_guard_state != stack_guard_reserved_disabled) { 1738 return true; // Stack already guarded or guard pages not needed. 1739 } 1740 1741 if (register_stack_overflow()) { 1742 // For those architectures which have separate register and 1743 // memory stacks, we must check the register stack to see if 1744 // it has overflowed. 1745 return false; 1746 } 1747 1748 // Java code never executes within the yellow zone: the latter is only 1749 // there to provoke an exception during stack banging. If java code 1750 // is executing there, either StackShadowPages should be larger, or 1751 // some exception code in c1, c2 or the interpreter isn't unwinding 1752 // when it should. 1753 guarantee(cur_sp > stack_reserved_zone_base(), 1754 "not enough space to reguard - increase StackShadowPages"); 1755 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1756 enable_stack_yellow_reserved_zone(); 1757 if (reserved_stack_activation() != stack_base()) { 1758 set_reserved_stack_activation(stack_base()); 1759 } 1760 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1761 set_reserved_stack_activation(stack_base()); 1762 enable_stack_reserved_zone(); 1763 } 1764 return true; 1765 } 1766 1767 bool JavaThread::reguard_stack(void) { 1768 return reguard_stack(os::current_stack_pointer()); 1769 } 1770 1771 1772 void JavaThread::block_if_vm_exited() { 1773 if (_terminated == _vm_exited) { 1774 // _vm_exited is set at safepoint, and Threads_lock is never released 1775 // we will block here forever 1776 Threads_lock->lock(); 1777 ShouldNotReachHere(); 1778 } 1779 } 1780 1781 1782 // Remove this ifdef when C1 is ported to the compiler interface. 1783 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1784 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1785 1786 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1787 Thread() { 1788 initialize(); 1789 _jni_attach_state = _not_attaching_via_jni; 1790 set_entry_point(entry_point); 1791 // Create the native thread itself. 1792 // %note runtime_23 1793 os::ThreadType thr_type = os::java_thread; 1794 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1795 os::java_thread; 1796 os::create_thread(this, thr_type, stack_sz); 1797 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1798 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1799 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1800 // the exception consists of creating the exception object & initializing it, initialization 1801 // will leave the VM via a JavaCall and then all locks must be unlocked). 1802 // 1803 // The thread is still suspended when we reach here. Thread must be explicit started 1804 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1805 // by calling Threads:add. The reason why this is not done here, is because the thread 1806 // object must be fully initialized (take a look at JVM_Start) 1807 } 1808 1809 JavaThread::~JavaThread() { 1810 1811 // JSR166 -- return the parker to the free list 1812 Parker::Release(_parker); 1813 _parker = NULL; 1814 1815 // Free any remaining previous UnrollBlock 1816 vframeArray* old_array = vframe_array_last(); 1817 1818 if (old_array != NULL) { 1819 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1820 old_array->set_unroll_block(NULL); 1821 delete old_info; 1822 delete old_array; 1823 } 1824 1825 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1826 if (deferred != NULL) { 1827 // This can only happen if thread is destroyed before deoptimization occurs. 1828 assert(deferred->length() != 0, "empty array!"); 1829 do { 1830 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1831 deferred->remove_at(0); 1832 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1833 delete dlv; 1834 } while (deferred->length() != 0); 1835 delete deferred; 1836 } 1837 1838 // All Java related clean up happens in exit 1839 ThreadSafepointState::destroy(this); 1840 if (_thread_stat != NULL) delete _thread_stat; 1841 1842 #if INCLUDE_JVMCI 1843 if (JVMCICounterSize > 0) { 1844 if (jvmci_counters_include(this)) { 1845 for (int i = 0; i < JVMCICounterSize; i++) { 1846 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1847 } 1848 } 1849 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1850 } 1851 #endif // INCLUDE_JVMCI 1852 } 1853 1854 1855 // First JavaThread specific code executed by a new Java thread. 1856 void JavaThread::pre_run() { 1857 // empty - see comments in run() 1858 } 1859 1860 // The main routine called by a new Java thread. This isn't overridden 1861 // by subclasses, instead different subclasses define a different "entry_point" 1862 // which defines the actual logic for that kind of thread. 1863 void JavaThread::run() { 1864 // initialize thread-local alloc buffer related fields 1865 this->initialize_tlab(); 1866 1867 // Used to test validity of stack trace backs. 1868 // This can't be moved into pre_run() else we invalidate 1869 // the requirement that thread_main_inner is lower on 1870 // the stack. Consequently all the initialization logic 1871 // stays here in run() rather than pre_run(). 1872 this->record_base_of_stack_pointer(); 1873 1874 this->create_stack_guard_pages(); 1875 1876 this->cache_global_variables(); 1877 1878 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1879 // in the VM. Change thread state from _thread_new to _thread_in_vm 1880 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1881 // Before a thread is on the threads list it is always safe, so after leaving the 1882 // _thread_new we should emit a instruction barrier. The distance to modified code 1883 // from here is probably far enough, but this is consistent and safe. 1884 OrderAccess::cross_modify_fence(); 1885 1886 assert(JavaThread::current() == this, "sanity check"); 1887 assert(!Thread::current()->owns_locks(), "sanity check"); 1888 1889 DTRACE_THREAD_PROBE(start, this); 1890 1891 // This operation might block. We call that after all safepoint checks for a new thread has 1892 // been completed. 1893 this->set_active_handles(JNIHandleBlock::allocate_block()); 1894 1895 if (JvmtiExport::should_post_thread_life()) { 1896 JvmtiExport::post_thread_start(this); 1897 1898 } 1899 1900 // We call another function to do the rest so we are sure that the stack addresses used 1901 // from there will be lower than the stack base just computed. 1902 thread_main_inner(); 1903 } 1904 1905 void JavaThread::thread_main_inner() { 1906 assert(JavaThread::current() == this, "sanity check"); 1907 assert(this->threadObj() != NULL, "just checking"); 1908 1909 // Execute thread entry point unless this thread has a pending exception 1910 // or has been stopped before starting. 1911 // Note: Due to JVM_StopThread we can have pending exceptions already! 1912 if (!this->has_pending_exception() && 1913 !java_lang_Thread::is_stillborn(this->threadObj())) { 1914 { 1915 ResourceMark rm(this); 1916 this->set_native_thread_name(this->get_thread_name()); 1917 } 1918 HandleMark hm(this); 1919 this->entry_point()(this, this); 1920 } 1921 1922 DTRACE_THREAD_PROBE(stop, this); 1923 1924 // Cleanup is handled in post_run() 1925 } 1926 1927 // Shared teardown for all JavaThreads 1928 void JavaThread::post_run() { 1929 this->exit(false); 1930 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1931 // for any shared tear-down. 1932 this->smr_delete(); 1933 } 1934 1935 static void ensure_join(JavaThread* thread) { 1936 // We do not need to grab the Threads_lock, since we are operating on ourself. 1937 Handle threadObj(thread, thread->threadObj()); 1938 assert(threadObj.not_null(), "java thread object must exist"); 1939 ObjectLocker lock(threadObj, thread); 1940 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1941 thread->clear_pending_exception(); 1942 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1943 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1944 // Clear the native thread instance - this makes isAlive return false and allows the join() 1945 // to complete once we've done the notify_all below 1946 java_lang_Thread::set_thread(threadObj(), NULL); 1947 lock.notify_all(thread); 1948 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1949 thread->clear_pending_exception(); 1950 } 1951 1952 static bool is_daemon(oop threadObj) { 1953 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1954 } 1955 1956 // For any new cleanup additions, please check to see if they need to be applied to 1957 // cleanup_failed_attach_current_thread as well. 1958 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1959 assert(this == JavaThread::current(), "thread consistency check"); 1960 1961 elapsedTimer _timer_exit_phase1; 1962 elapsedTimer _timer_exit_phase2; 1963 elapsedTimer _timer_exit_phase3; 1964 elapsedTimer _timer_exit_phase4; 1965 1966 if (log_is_enabled(Debug, os, thread, timer)) { 1967 _timer_exit_phase1.start(); 1968 } 1969 1970 HandleMark hm(this); 1971 Handle uncaught_exception(this, this->pending_exception()); 1972 this->clear_pending_exception(); 1973 Handle threadObj(this, this->threadObj()); 1974 assert(threadObj.not_null(), "Java thread object should be created"); 1975 1976 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1977 { 1978 EXCEPTION_MARK; 1979 1980 CLEAR_PENDING_EXCEPTION; 1981 } 1982 if (!destroy_vm) { 1983 if (uncaught_exception.not_null()) { 1984 EXCEPTION_MARK; 1985 // Call method Thread.dispatchUncaughtException(). 1986 Klass* thread_klass = SystemDictionary::Thread_klass(); 1987 JavaValue result(T_VOID); 1988 JavaCalls::call_virtual(&result, 1989 threadObj, thread_klass, 1990 vmSymbols::dispatchUncaughtException_name(), 1991 vmSymbols::throwable_void_signature(), 1992 uncaught_exception, 1993 THREAD); 1994 if (HAS_PENDING_EXCEPTION) { 1995 ResourceMark rm(this); 1996 jio_fprintf(defaultStream::error_stream(), 1997 "\nException: %s thrown from the UncaughtExceptionHandler" 1998 " in thread \"%s\"\n", 1999 pending_exception()->klass()->external_name(), 2000 get_thread_name()); 2001 CLEAR_PENDING_EXCEPTION; 2002 } 2003 } 2004 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2005 2006 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2007 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2008 // is deprecated anyhow. 2009 if (!is_Compiler_thread()) { 2010 int count = 3; 2011 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2012 EXCEPTION_MARK; 2013 JavaValue result(T_VOID); 2014 Klass* thread_klass = SystemDictionary::Thread_klass(); 2015 JavaCalls::call_virtual(&result, 2016 threadObj, thread_klass, 2017 vmSymbols::exit_method_name(), 2018 vmSymbols::void_method_signature(), 2019 THREAD); 2020 CLEAR_PENDING_EXCEPTION; 2021 } 2022 } 2023 // notify JVMTI 2024 if (JvmtiExport::should_post_thread_life()) { 2025 JvmtiExport::post_thread_end(this); 2026 } 2027 2028 // We have notified the agents that we are exiting, before we go on, 2029 // we must check for a pending external suspend request and honor it 2030 // in order to not surprise the thread that made the suspend request. 2031 while (true) { 2032 { 2033 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2034 if (!is_external_suspend()) { 2035 set_terminated(_thread_exiting); 2036 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2037 break; 2038 } 2039 // Implied else: 2040 // Things get a little tricky here. We have a pending external 2041 // suspend request, but we are holding the SR_lock so we 2042 // can't just self-suspend. So we temporarily drop the lock 2043 // and then self-suspend. 2044 } 2045 2046 ThreadBlockInVM tbivm(this); 2047 java_suspend_self(); 2048 2049 // We're done with this suspend request, but we have to loop around 2050 // and check again. Eventually we will get SR_lock without a pending 2051 // external suspend request and will be able to mark ourselves as 2052 // exiting. 2053 } 2054 // no more external suspends are allowed at this point 2055 } else { 2056 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2057 // before_exit() has already posted JVMTI THREAD_END events 2058 } 2059 2060 if (log_is_enabled(Debug, os, thread, timer)) { 2061 _timer_exit_phase1.stop(); 2062 _timer_exit_phase2.start(); 2063 } 2064 2065 // Capture daemon status before the thread is marked as terminated. 2066 bool daemon = is_daemon(threadObj()); 2067 2068 // Notify waiters on thread object. This has to be done after exit() is called 2069 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2070 // group should have the destroyed bit set before waiters are notified). 2071 ensure_join(this); 2072 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2073 2074 if (log_is_enabled(Debug, os, thread, timer)) { 2075 _timer_exit_phase2.stop(); 2076 _timer_exit_phase3.start(); 2077 } 2078 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2079 // held by this thread must be released. The spec does not distinguish 2080 // between JNI-acquired and regular Java monitors. We can only see 2081 // regular Java monitors here if monitor enter-exit matching is broken. 2082 // 2083 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2084 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2085 if (exit_type == jni_detach) { 2086 // Sanity check even though JNI DetachCurrentThread() would have 2087 // returned JNI_ERR if there was a Java frame. JavaThread exit 2088 // should be done executing Java code by the time we get here. 2089 assert(!this->has_last_Java_frame(), 2090 "should not have a Java frame when detaching or exiting"); 2091 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2092 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2093 } 2094 2095 // These things needs to be done while we are still a Java Thread. Make sure that thread 2096 // is in a consistent state, in case GC happens 2097 JFR_ONLY(Jfr::on_thread_exit(this);) 2098 2099 if (active_handles() != NULL) { 2100 JNIHandleBlock* block = active_handles(); 2101 set_active_handles(NULL); 2102 JNIHandleBlock::release_block(block); 2103 } 2104 2105 if (free_handle_block() != NULL) { 2106 JNIHandleBlock* block = free_handle_block(); 2107 set_free_handle_block(NULL); 2108 JNIHandleBlock::release_block(block); 2109 } 2110 2111 // These have to be removed while this is still a valid thread. 2112 remove_stack_guard_pages(); 2113 2114 if (UseTLAB) { 2115 tlab().retire(); 2116 } 2117 2118 if (JvmtiEnv::environments_might_exist()) { 2119 JvmtiExport::cleanup_thread(this); 2120 } 2121 2122 // We must flush any deferred card marks and other various GC barrier 2123 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2124 // before removing a thread from the list of active threads. 2125 BarrierSet::barrier_set()->on_thread_detach(this); 2126 2127 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2128 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2129 os::current_thread_id()); 2130 2131 if (log_is_enabled(Debug, os, thread, timer)) { 2132 _timer_exit_phase3.stop(); 2133 _timer_exit_phase4.start(); 2134 } 2135 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2136 Threads::remove(this, daemon); 2137 2138 if (log_is_enabled(Debug, os, thread, timer)) { 2139 _timer_exit_phase4.stop(); 2140 ResourceMark rm(this); 2141 log_debug(os, thread, timer)("name='%s'" 2142 ", exit-phase1=" JLONG_FORMAT 2143 ", exit-phase2=" JLONG_FORMAT 2144 ", exit-phase3=" JLONG_FORMAT 2145 ", exit-phase4=" JLONG_FORMAT, 2146 get_thread_name(), 2147 _timer_exit_phase1.milliseconds(), 2148 _timer_exit_phase2.milliseconds(), 2149 _timer_exit_phase3.milliseconds(), 2150 _timer_exit_phase4.milliseconds()); 2151 } 2152 } 2153 2154 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2155 if (active_handles() != NULL) { 2156 JNIHandleBlock* block = active_handles(); 2157 set_active_handles(NULL); 2158 JNIHandleBlock::release_block(block); 2159 } 2160 2161 if (free_handle_block() != NULL) { 2162 JNIHandleBlock* block = free_handle_block(); 2163 set_free_handle_block(NULL); 2164 JNIHandleBlock::release_block(block); 2165 } 2166 2167 // These have to be removed while this is still a valid thread. 2168 remove_stack_guard_pages(); 2169 2170 if (UseTLAB) { 2171 tlab().retire(); 2172 } 2173 2174 BarrierSet::barrier_set()->on_thread_detach(this); 2175 2176 Threads::remove(this, is_daemon); 2177 this->smr_delete(); 2178 } 2179 2180 JavaThread* JavaThread::active() { 2181 Thread* thread = Thread::current(); 2182 if (thread->is_Java_thread()) { 2183 return (JavaThread*) thread; 2184 } else { 2185 assert(thread->is_VM_thread(), "this must be a vm thread"); 2186 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2187 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2188 assert(ret->is_Java_thread(), "must be a Java thread"); 2189 return ret; 2190 } 2191 } 2192 2193 bool JavaThread::is_lock_owned(address adr) const { 2194 if (Thread::is_lock_owned(adr)) return true; 2195 2196 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2197 if (chunk->contains(adr)) return true; 2198 } 2199 2200 return false; 2201 } 2202 2203 2204 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2205 chunk->set_next(monitor_chunks()); 2206 set_monitor_chunks(chunk); 2207 } 2208 2209 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2210 guarantee(monitor_chunks() != NULL, "must be non empty"); 2211 if (monitor_chunks() == chunk) { 2212 set_monitor_chunks(chunk->next()); 2213 } else { 2214 MonitorChunk* prev = monitor_chunks(); 2215 while (prev->next() != chunk) prev = prev->next(); 2216 prev->set_next(chunk->next()); 2217 } 2218 } 2219 2220 // JVM support. 2221 2222 // Note: this function shouldn't block if it's called in 2223 // _thread_in_native_trans state (such as from 2224 // check_special_condition_for_native_trans()). 2225 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2226 2227 if (has_last_Java_frame() && has_async_condition()) { 2228 // If we are at a polling page safepoint (not a poll return) 2229 // then we must defer async exception because live registers 2230 // will be clobbered by the exception path. Poll return is 2231 // ok because the call we a returning from already collides 2232 // with exception handling registers and so there is no issue. 2233 // (The exception handling path kills call result registers but 2234 // this is ok since the exception kills the result anyway). 2235 2236 if (is_at_poll_safepoint()) { 2237 // if the code we are returning to has deoptimized we must defer 2238 // the exception otherwise live registers get clobbered on the 2239 // exception path before deoptimization is able to retrieve them. 2240 // 2241 RegisterMap map(this, false); 2242 frame caller_fr = last_frame().sender(&map); 2243 assert(caller_fr.is_compiled_frame(), "what?"); 2244 if (caller_fr.is_deoptimized_frame()) { 2245 log_info(exceptions)("deferred async exception at compiled safepoint"); 2246 return; 2247 } 2248 } 2249 } 2250 2251 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2252 if (condition == _no_async_condition) { 2253 // Conditions have changed since has_special_runtime_exit_condition() 2254 // was called: 2255 // - if we were here only because of an external suspend request, 2256 // then that was taken care of above (or cancelled) so we are done 2257 // - if we were here because of another async request, then it has 2258 // been cleared between the has_special_runtime_exit_condition() 2259 // and now so again we are done 2260 return; 2261 } 2262 2263 // Check for pending async. exception 2264 if (_pending_async_exception != NULL) { 2265 // Only overwrite an already pending exception, if it is not a threadDeath. 2266 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2267 2268 // We cannot call Exceptions::_throw(...) here because we cannot block 2269 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2270 2271 LogTarget(Info, exceptions) lt; 2272 if (lt.is_enabled()) { 2273 ResourceMark rm; 2274 LogStream ls(lt); 2275 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2276 if (has_last_Java_frame()) { 2277 frame f = last_frame(); 2278 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2279 } 2280 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2281 } 2282 _pending_async_exception = NULL; 2283 clear_has_async_exception(); 2284 } 2285 } 2286 2287 if (check_unsafe_error && 2288 condition == _async_unsafe_access_error && !has_pending_exception()) { 2289 condition = _no_async_condition; // done 2290 switch (thread_state()) { 2291 case _thread_in_vm: { 2292 JavaThread* THREAD = this; 2293 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2294 } 2295 case _thread_in_native: { 2296 ThreadInVMfromNative tiv(this); 2297 JavaThread* THREAD = this; 2298 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2299 } 2300 case _thread_in_Java: { 2301 ThreadInVMfromJava tiv(this); 2302 JavaThread* THREAD = this; 2303 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2304 } 2305 default: 2306 ShouldNotReachHere(); 2307 } 2308 } 2309 2310 assert(condition == _no_async_condition || has_pending_exception() || 2311 (!check_unsafe_error && condition == _async_unsafe_access_error), 2312 "must have handled the async condition, if no exception"); 2313 } 2314 2315 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2316 2317 // Check for pending external suspend. 2318 if (is_external_suspend_with_lock()) { 2319 frame_anchor()->make_walkable(this); 2320 java_suspend_self_with_safepoint_check(); 2321 } 2322 2323 // We might be here for reasons in addition to the self-suspend request 2324 // so check for other async requests. 2325 if (check_asyncs) { 2326 check_and_handle_async_exceptions(); 2327 } 2328 2329 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2330 } 2331 2332 void JavaThread::send_thread_stop(oop java_throwable) { 2333 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2334 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2335 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2336 2337 // Do not throw asynchronous exceptions against the compiler thread 2338 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2339 if (!can_call_java()) return; 2340 2341 { 2342 // Actually throw the Throwable against the target Thread - however 2343 // only if there is no thread death exception installed already. 2344 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2345 // If the topmost frame is a runtime stub, then we are calling into 2346 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2347 // must deoptimize the caller before continuing, as the compiled exception handler table 2348 // may not be valid 2349 if (has_last_Java_frame()) { 2350 frame f = last_frame(); 2351 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2352 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2353 RegisterMap reg_map(this, UseBiasedLocking); 2354 frame compiled_frame = f.sender(®_map); 2355 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2356 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2357 } 2358 } 2359 } 2360 2361 // Set async. pending exception in thread. 2362 set_pending_async_exception(java_throwable); 2363 2364 if (log_is_enabled(Info, exceptions)) { 2365 ResourceMark rm; 2366 log_info(exceptions)("Pending Async. exception installed of type: %s", 2367 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2368 } 2369 // for AbortVMOnException flag 2370 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2371 } 2372 } 2373 2374 2375 // Interrupt thread so it will wake up from a potential wait() 2376 Thread::interrupt(this); 2377 } 2378 2379 // External suspension mechanism. 2380 // 2381 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2382 // to any VM_locks and it is at a transition 2383 // Self-suspension will happen on the transition out of the vm. 2384 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2385 // 2386 // Guarantees on return: 2387 // + Target thread will not execute any new bytecode (that's why we need to 2388 // force a safepoint) 2389 // + Target thread will not enter any new monitors 2390 // 2391 void JavaThread::java_suspend() { 2392 ThreadsListHandle tlh; 2393 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2394 return; 2395 } 2396 2397 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2398 if (!is_external_suspend()) { 2399 // a racing resume has cancelled us; bail out now 2400 return; 2401 } 2402 2403 // suspend is done 2404 uint32_t debug_bits = 0; 2405 // Warning: is_ext_suspend_completed() may temporarily drop the 2406 // SR_lock to allow the thread to reach a stable thread state if 2407 // it is currently in a transient thread state. 2408 if (is_ext_suspend_completed(false /* !called_by_wait */, 2409 SuspendRetryDelay, &debug_bits)) { 2410 return; 2411 } 2412 } 2413 2414 if (Thread::current() == this) { 2415 // Safely self-suspend. 2416 // If we don't do this explicitly it will implicitly happen 2417 // before we transition back to Java, and on some other thread-state 2418 // transition paths, but not as we exit a JVM TI SuspendThread call. 2419 // As SuspendThread(current) must not return (until resumed) we must 2420 // self-suspend here. 2421 ThreadBlockInVM tbivm(this); 2422 java_suspend_self(); 2423 } else { 2424 VM_ThreadSuspend vm_suspend; 2425 VMThread::execute(&vm_suspend); 2426 } 2427 } 2428 2429 // Part II of external suspension. 2430 // A JavaThread self suspends when it detects a pending external suspend 2431 // request. This is usually on transitions. It is also done in places 2432 // where continuing to the next transition would surprise the caller, 2433 // e.g., monitor entry. 2434 // 2435 // Returns the number of times that the thread self-suspended. 2436 // 2437 // Note: DO NOT call java_suspend_self() when you just want to block current 2438 // thread. java_suspend_self() is the second stage of cooperative 2439 // suspension for external suspend requests and should only be used 2440 // to complete an external suspend request. 2441 // 2442 int JavaThread::java_suspend_self() { 2443 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2444 int ret = 0; 2445 2446 // we are in the process of exiting so don't suspend 2447 if (is_exiting()) { 2448 clear_external_suspend(); 2449 return ret; 2450 } 2451 2452 assert(_anchor.walkable() || 2453 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2454 "must have walkable stack"); 2455 2456 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2457 2458 assert(!this->is_ext_suspended(), 2459 "a thread trying to self-suspend should not already be suspended"); 2460 2461 if (this->is_suspend_equivalent()) { 2462 // If we are self-suspending as a result of the lifting of a 2463 // suspend equivalent condition, then the suspend_equivalent 2464 // flag is not cleared until we set the ext_suspended flag so 2465 // that wait_for_ext_suspend_completion() returns consistent 2466 // results. 2467 this->clear_suspend_equivalent(); 2468 } 2469 2470 // A racing resume may have cancelled us before we grabbed SR_lock 2471 // above. Or another external suspend request could be waiting for us 2472 // by the time we return from SR_lock()->wait(). The thread 2473 // that requested the suspension may already be trying to walk our 2474 // stack and if we return now, we can change the stack out from under 2475 // it. This would be a "bad thing (TM)" and cause the stack walker 2476 // to crash. We stay self-suspended until there are no more pending 2477 // external suspend requests. 2478 while (is_external_suspend()) { 2479 ret++; 2480 this->set_ext_suspended(); 2481 2482 // _ext_suspended flag is cleared by java_resume() 2483 while (is_ext_suspended()) { 2484 ml.wait(); 2485 } 2486 } 2487 return ret; 2488 } 2489 2490 // Helper routine to set up the correct thread state before calling java_suspend_self. 2491 // This is called when regular thread-state transition helpers can't be used because 2492 // we can be in various states, in particular _thread_in_native_trans. 2493 // Because this thread is external suspended the safepoint code will count it as at 2494 // a safepoint, regardless of what its actual current thread-state is. But 2495 // is_ext_suspend_completed() may be waiting to see a thread transition from 2496 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2497 // to _thread_blocked. The problem with setting thread state directly is that a 2498 // safepoint could happen just after java_suspend_self() returns after being resumed, 2499 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2500 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2501 // However, not all initial-states are allowed when performing a safepoint check, as we 2502 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2503 // only _thread_in_native is possible when executing this code (based on our two callers). 2504 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2505 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2506 // and so we don't need the explicit safepoint check. 2507 2508 void JavaThread::java_suspend_self_with_safepoint_check() { 2509 assert(this == Thread::current(), "invariant"); 2510 JavaThreadState state = thread_state(); 2511 set_thread_state(_thread_blocked); 2512 java_suspend_self(); 2513 set_thread_state_fence(state); 2514 // Since we are not using a regular thread-state transition helper here, 2515 // we must manually emit the instruction barrier after leaving a safe state. 2516 OrderAccess::cross_modify_fence(); 2517 if (state != _thread_in_native) { 2518 SafepointMechanism::block_if_requested(this); 2519 } 2520 } 2521 2522 #ifdef ASSERT 2523 // Verify the JavaThread has not yet been published in the Threads::list, and 2524 // hence doesn't need protection from concurrent access at this stage. 2525 void JavaThread::verify_not_published() { 2526 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2527 // since an unpublished JavaThread doesn't participate in the 2528 // Thread-SMR protocol for keeping a ThreadsList alive. 2529 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2530 } 2531 #endif 2532 2533 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2534 // progress or when _suspend_flags is non-zero. 2535 // Current thread needs to self-suspend if there is a suspend request and/or 2536 // block if a safepoint is in progress. 2537 // Async exception ISN'T checked. 2538 // Note only the ThreadInVMfromNative transition can call this function 2539 // directly and when thread state is _thread_in_native_trans 2540 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2541 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2542 2543 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2544 2545 if (thread->is_external_suspend()) { 2546 thread->java_suspend_self_with_safepoint_check(); 2547 } else { 2548 SafepointMechanism::block_if_requested(thread); 2549 } 2550 2551 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2552 } 2553 2554 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2555 // progress or when _suspend_flags is non-zero. 2556 // Current thread needs to self-suspend if there is a suspend request and/or 2557 // block if a safepoint is in progress. 2558 // Also check for pending async exception (not including unsafe access error). 2559 // Note only the native==>VM/Java barriers can call this function and when 2560 // thread state is _thread_in_native_trans. 2561 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2562 check_safepoint_and_suspend_for_native_trans(thread); 2563 2564 if (thread->has_async_exception()) { 2565 // We are in _thread_in_native_trans state, don't handle unsafe 2566 // access error since that may block. 2567 thread->check_and_handle_async_exceptions(false); 2568 } 2569 } 2570 2571 // This is a variant of the normal 2572 // check_special_condition_for_native_trans with slightly different 2573 // semantics for use by critical native wrappers. It does all the 2574 // normal checks but also performs the transition back into 2575 // thread_in_Java state. This is required so that critical natives 2576 // can potentially block and perform a GC if they are the last thread 2577 // exiting the GCLocker. 2578 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2579 check_special_condition_for_native_trans(thread); 2580 2581 // Finish the transition 2582 thread->set_thread_state(_thread_in_Java); 2583 2584 if (thread->do_critical_native_unlock()) { 2585 ThreadInVMfromJavaNoAsyncException tiv(thread); 2586 GCLocker::unlock_critical(thread); 2587 thread->clear_critical_native_unlock(); 2588 } 2589 } 2590 2591 // We need to guarantee the Threads_lock here, since resumes are not 2592 // allowed during safepoint synchronization 2593 // Can only resume from an external suspension 2594 void JavaThread::java_resume() { 2595 assert_locked_or_safepoint(Threads_lock); 2596 2597 // Sanity check: thread is gone, has started exiting or the thread 2598 // was not externally suspended. 2599 ThreadsListHandle tlh; 2600 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2601 return; 2602 } 2603 2604 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2605 2606 clear_external_suspend(); 2607 2608 if (is_ext_suspended()) { 2609 clear_ext_suspended(); 2610 SR_lock()->notify_all(); 2611 } 2612 } 2613 2614 size_t JavaThread::_stack_red_zone_size = 0; 2615 size_t JavaThread::_stack_yellow_zone_size = 0; 2616 size_t JavaThread::_stack_reserved_zone_size = 0; 2617 size_t JavaThread::_stack_shadow_zone_size = 0; 2618 2619 void JavaThread::create_stack_guard_pages() { 2620 if (!os::uses_stack_guard_pages() || 2621 _stack_guard_state != stack_guard_unused || 2622 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2623 log_info(os, thread)("Stack guard page creation for thread " 2624 UINTX_FORMAT " disabled", os::current_thread_id()); 2625 return; 2626 } 2627 address low_addr = stack_end(); 2628 size_t len = stack_guard_zone_size(); 2629 2630 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2631 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2632 2633 int must_commit = os::must_commit_stack_guard_pages(); 2634 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2635 2636 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2637 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2638 return; 2639 } 2640 2641 if (os::guard_memory((char *) low_addr, len)) { 2642 _stack_guard_state = stack_guard_enabled; 2643 } else { 2644 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2645 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2646 if (os::uncommit_memory((char *) low_addr, len)) { 2647 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2648 } 2649 return; 2650 } 2651 2652 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2653 PTR_FORMAT "-" PTR_FORMAT ".", 2654 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2655 } 2656 2657 void JavaThread::remove_stack_guard_pages() { 2658 assert(Thread::current() == this, "from different thread"); 2659 if (_stack_guard_state == stack_guard_unused) return; 2660 address low_addr = stack_end(); 2661 size_t len = stack_guard_zone_size(); 2662 2663 if (os::must_commit_stack_guard_pages()) { 2664 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2665 _stack_guard_state = stack_guard_unused; 2666 } else { 2667 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2668 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2669 return; 2670 } 2671 } else { 2672 if (_stack_guard_state == stack_guard_unused) return; 2673 if (os::unguard_memory((char *) low_addr, len)) { 2674 _stack_guard_state = stack_guard_unused; 2675 } else { 2676 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2677 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2678 return; 2679 } 2680 } 2681 2682 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2683 PTR_FORMAT "-" PTR_FORMAT ".", 2684 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2685 } 2686 2687 void JavaThread::enable_stack_reserved_zone() { 2688 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2689 2690 // The base notation is from the stack's point of view, growing downward. 2691 // We need to adjust it to work correctly with guard_memory() 2692 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2693 2694 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2695 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2696 2697 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2698 _stack_guard_state = stack_guard_enabled; 2699 } else { 2700 warning("Attempt to guard stack reserved zone failed."); 2701 } 2702 enable_register_stack_guard(); 2703 } 2704 2705 void JavaThread::disable_stack_reserved_zone() { 2706 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2707 2708 // Simply return if called for a thread that does not use guard pages. 2709 if (_stack_guard_state != stack_guard_enabled) return; 2710 2711 // The base notation is from the stack's point of view, growing downward. 2712 // We need to adjust it to work correctly with guard_memory() 2713 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2714 2715 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2716 _stack_guard_state = stack_guard_reserved_disabled; 2717 } else { 2718 warning("Attempt to unguard stack reserved zone failed."); 2719 } 2720 disable_register_stack_guard(); 2721 } 2722 2723 void JavaThread::enable_stack_yellow_reserved_zone() { 2724 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2725 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2726 2727 // The base notation is from the stacks point of view, growing downward. 2728 // We need to adjust it to work correctly with guard_memory() 2729 address base = stack_red_zone_base(); 2730 2731 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2732 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2733 2734 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2735 _stack_guard_state = stack_guard_enabled; 2736 } else { 2737 warning("Attempt to guard stack yellow zone failed."); 2738 } 2739 enable_register_stack_guard(); 2740 } 2741 2742 void JavaThread::disable_stack_yellow_reserved_zone() { 2743 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2744 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2745 2746 // Simply return if called for a thread that does not use guard pages. 2747 if (_stack_guard_state == stack_guard_unused) return; 2748 2749 // The base notation is from the stacks point of view, growing downward. 2750 // We need to adjust it to work correctly with guard_memory() 2751 address base = stack_red_zone_base(); 2752 2753 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2754 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2755 } else { 2756 warning("Attempt to unguard stack yellow zone failed."); 2757 } 2758 disable_register_stack_guard(); 2759 } 2760 2761 void JavaThread::enable_stack_red_zone() { 2762 // The base notation is from the stacks point of view, growing downward. 2763 // We need to adjust it to work correctly with guard_memory() 2764 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2765 address base = stack_red_zone_base() - stack_red_zone_size(); 2766 2767 guarantee(base < stack_base(), "Error calculating stack red zone"); 2768 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2769 2770 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2771 warning("Attempt to guard stack red zone failed."); 2772 } 2773 } 2774 2775 void JavaThread::disable_stack_red_zone() { 2776 // The base notation is from the stacks point of view, growing downward. 2777 // We need to adjust it to work correctly with guard_memory() 2778 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2779 address base = stack_red_zone_base() - stack_red_zone_size(); 2780 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2781 warning("Attempt to unguard stack red zone failed."); 2782 } 2783 } 2784 2785 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2786 // ignore is there is no stack 2787 if (!has_last_Java_frame()) return; 2788 // traverse the stack frames. Starts from top frame. 2789 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2790 frame* fr = fst.current(); 2791 f(fr, fst.register_map()); 2792 } 2793 } 2794 2795 2796 #ifndef PRODUCT 2797 // Deoptimization 2798 // Function for testing deoptimization 2799 void JavaThread::deoptimize() { 2800 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2801 StackFrameStream fst(this, UseBiasedLocking); 2802 bool deopt = false; // Dump stack only if a deopt actually happens. 2803 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2804 // Iterate over all frames in the thread and deoptimize 2805 for (; !fst.is_done(); fst.next()) { 2806 if (fst.current()->can_be_deoptimized()) { 2807 2808 if (only_at) { 2809 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2810 // consists of comma or carriage return separated numbers so 2811 // search for the current bci in that string. 2812 address pc = fst.current()->pc(); 2813 nmethod* nm = (nmethod*) fst.current()->cb(); 2814 ScopeDesc* sd = nm->scope_desc_at(pc); 2815 char buffer[8]; 2816 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2817 size_t len = strlen(buffer); 2818 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2819 while (found != NULL) { 2820 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2821 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2822 // Check that the bci found is bracketed by terminators. 2823 break; 2824 } 2825 found = strstr(found + 1, buffer); 2826 } 2827 if (!found) { 2828 continue; 2829 } 2830 } 2831 2832 if (DebugDeoptimization && !deopt) { 2833 deopt = true; // One-time only print before deopt 2834 tty->print_cr("[BEFORE Deoptimization]"); 2835 trace_frames(); 2836 trace_stack(); 2837 } 2838 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2839 } 2840 } 2841 2842 if (DebugDeoptimization && deopt) { 2843 tty->print_cr("[AFTER Deoptimization]"); 2844 trace_frames(); 2845 } 2846 } 2847 2848 2849 // Make zombies 2850 void JavaThread::make_zombies() { 2851 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2852 if (fst.current()->can_be_deoptimized()) { 2853 // it is a Java nmethod 2854 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2855 nm->make_not_entrant(); 2856 } 2857 } 2858 } 2859 #endif // PRODUCT 2860 2861 2862 void JavaThread::deoptimize_marked_methods() { 2863 if (!has_last_Java_frame()) return; 2864 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2865 StackFrameStream fst(this, UseBiasedLocking); 2866 for (; !fst.is_done(); fst.next()) { 2867 if (fst.current()->should_be_deoptimized()) { 2868 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2869 } 2870 } 2871 } 2872 2873 // If the caller is a NamedThread, then remember, in the current scope, 2874 // the given JavaThread in its _processed_thread field. 2875 class RememberProcessedThread: public StackObj { 2876 NamedThread* _cur_thr; 2877 public: 2878 RememberProcessedThread(JavaThread* jthr) { 2879 Thread* thread = Thread::current(); 2880 if (thread->is_Named_thread()) { 2881 _cur_thr = (NamedThread *)thread; 2882 _cur_thr->set_processed_thread(jthr); 2883 } else { 2884 _cur_thr = NULL; 2885 } 2886 } 2887 2888 ~RememberProcessedThread() { 2889 if (_cur_thr) { 2890 _cur_thr->set_processed_thread(NULL); 2891 } 2892 } 2893 }; 2894 2895 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2896 // Verify that the deferred card marks have been flushed. 2897 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2898 2899 // Traverse the GCHandles 2900 Thread::oops_do(f, cf); 2901 2902 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2903 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2904 2905 if (has_last_Java_frame()) { 2906 // Record JavaThread to GC thread 2907 RememberProcessedThread rpt(this); 2908 2909 // traverse the registered growable array 2910 if (_array_for_gc != NULL) { 2911 for (int index = 0; index < _array_for_gc->length(); index++) { 2912 f->do_oop(_array_for_gc->adr_at(index)); 2913 } 2914 } 2915 2916 // Traverse the monitor chunks 2917 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2918 chunk->oops_do(f); 2919 } 2920 2921 // Traverse the execution stack 2922 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2923 fst.current()->oops_do(f, cf, fst.register_map()); 2924 } 2925 } 2926 2927 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2928 // If we have deferred set_locals there might be oops waiting to be 2929 // written 2930 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2931 if (list != NULL) { 2932 for (int i = 0; i < list->length(); i++) { 2933 list->at(i)->oops_do(f); 2934 } 2935 } 2936 2937 // Traverse instance variables at the end since the GC may be moving things 2938 // around using this function 2939 f->do_oop((oop*) &_threadObj); 2940 f->do_oop((oop*) &_vm_result); 2941 f->do_oop((oop*) &_exception_oop); 2942 f->do_oop((oop*) &_pending_async_exception); 2943 2944 if (jvmti_thread_state() != NULL) { 2945 jvmti_thread_state()->oops_do(f); 2946 } 2947 } 2948 2949 #ifdef ASSERT 2950 void JavaThread::verify_states_for_handshake() { 2951 // This checks that the thread has a correct frame state during a handshake. 2952 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2953 (has_last_Java_frame() && java_call_counter() > 0), 2954 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 2955 has_last_Java_frame(), java_call_counter()); 2956 } 2957 #endif 2958 2959 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2960 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2961 (has_last_Java_frame() && java_call_counter() > 0), 2962 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 2963 has_last_Java_frame(), java_call_counter()); 2964 2965 if (has_last_Java_frame()) { 2966 // Traverse the execution stack 2967 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2968 fst.current()->nmethods_do(cf); 2969 } 2970 } 2971 } 2972 2973 void JavaThread::metadata_do(MetadataClosure* f) { 2974 if (has_last_Java_frame()) { 2975 // Traverse the execution stack to call f() on the methods in the stack 2976 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2977 fst.current()->metadata_do(f); 2978 } 2979 } else if (is_Compiler_thread()) { 2980 // need to walk ciMetadata in current compile tasks to keep alive. 2981 CompilerThread* ct = (CompilerThread*)this; 2982 if (ct->env() != NULL) { 2983 ct->env()->metadata_do(f); 2984 } 2985 CompileTask* task = ct->task(); 2986 if (task != NULL) { 2987 task->metadata_do(f); 2988 } 2989 } 2990 } 2991 2992 // Printing 2993 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2994 switch (_thread_state) { 2995 case _thread_uninitialized: return "_thread_uninitialized"; 2996 case _thread_new: return "_thread_new"; 2997 case _thread_new_trans: return "_thread_new_trans"; 2998 case _thread_in_native: return "_thread_in_native"; 2999 case _thread_in_native_trans: return "_thread_in_native_trans"; 3000 case _thread_in_vm: return "_thread_in_vm"; 3001 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3002 case _thread_in_Java: return "_thread_in_Java"; 3003 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3004 case _thread_blocked: return "_thread_blocked"; 3005 case _thread_blocked_trans: return "_thread_blocked_trans"; 3006 default: return "unknown thread state"; 3007 } 3008 } 3009 3010 #ifndef PRODUCT 3011 void JavaThread::print_thread_state_on(outputStream *st) const { 3012 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3013 }; 3014 #endif // PRODUCT 3015 3016 // Called by Threads::print() for VM_PrintThreads operation 3017 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3018 st->print_raw("\""); 3019 st->print_raw(get_thread_name()); 3020 st->print_raw("\" "); 3021 oop thread_oop = threadObj(); 3022 if (thread_oop != NULL) { 3023 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3024 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3025 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3026 } 3027 Thread::print_on(st, print_extended_info); 3028 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3029 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3030 if (thread_oop != NULL) { 3031 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3032 } 3033 #ifndef PRODUCT 3034 _safepoint_state->print_on(st); 3035 #endif // PRODUCT 3036 if (is_Compiler_thread()) { 3037 CompileTask *task = ((CompilerThread*)this)->task(); 3038 if (task != NULL) { 3039 st->print(" Compiling: "); 3040 task->print(st, NULL, true, false); 3041 } else { 3042 st->print(" No compile task"); 3043 } 3044 st->cr(); 3045 } 3046 } 3047 3048 void JavaThread::print() const { print_on(tty); } 3049 3050 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3051 st->print("%s", get_thread_name_string(buf, buflen)); 3052 } 3053 3054 // Called by fatal error handler. The difference between this and 3055 // JavaThread::print() is that we can't grab lock or allocate memory. 3056 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3057 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3058 oop thread_obj = threadObj(); 3059 if (thread_obj != NULL) { 3060 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3061 } 3062 st->print(" ["); 3063 st->print("%s", _get_thread_state_name(_thread_state)); 3064 if (osthread()) { 3065 st->print(", id=%d", osthread()->thread_id()); 3066 } 3067 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3068 p2i(stack_end()), p2i(stack_base())); 3069 st->print("]"); 3070 3071 ThreadsSMRSupport::print_info_on(this, st); 3072 return; 3073 } 3074 3075 // Verification 3076 3077 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3078 3079 void JavaThread::verify() { 3080 // Verify oops in the thread. 3081 oops_do(&VerifyOopClosure::verify_oop, NULL); 3082 3083 // Verify the stack frames. 3084 frames_do(frame_verify); 3085 } 3086 3087 // CR 6300358 (sub-CR 2137150) 3088 // Most callers of this method assume that it can't return NULL but a 3089 // thread may not have a name whilst it is in the process of attaching to 3090 // the VM - see CR 6412693, and there are places where a JavaThread can be 3091 // seen prior to having it's threadObj set (eg JNI attaching threads and 3092 // if vm exit occurs during initialization). These cases can all be accounted 3093 // for such that this method never returns NULL. 3094 const char* JavaThread::get_thread_name() const { 3095 #ifdef ASSERT 3096 // early safepoints can hit while current thread does not yet have TLS 3097 if (!SafepointSynchronize::is_at_safepoint()) { 3098 Thread *cur = Thread::current(); 3099 if (!(cur->is_Java_thread() && cur == this)) { 3100 // Current JavaThreads are allowed to get their own name without 3101 // the Threads_lock. 3102 assert_locked_or_safepoint(Threads_lock); 3103 } 3104 } 3105 #endif // ASSERT 3106 return get_thread_name_string(); 3107 } 3108 3109 // Returns a non-NULL representation of this thread's name, or a suitable 3110 // descriptive string if there is no set name 3111 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3112 const char* name_str; 3113 oop thread_obj = threadObj(); 3114 if (thread_obj != NULL) { 3115 oop name = java_lang_Thread::name(thread_obj); 3116 if (name != NULL) { 3117 if (buf == NULL) { 3118 name_str = java_lang_String::as_utf8_string(name); 3119 } else { 3120 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3121 } 3122 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3123 name_str = "<no-name - thread is attaching>"; 3124 } else { 3125 name_str = Thread::name(); 3126 } 3127 } else { 3128 name_str = Thread::name(); 3129 } 3130 assert(name_str != NULL, "unexpected NULL thread name"); 3131 return name_str; 3132 } 3133 3134 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3135 3136 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3137 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3138 // Link Java Thread object <-> C++ Thread 3139 3140 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3141 // and put it into a new Handle. The Handle "thread_oop" can then 3142 // be used to pass the C++ thread object to other methods. 3143 3144 // Set the Java level thread object (jthread) field of the 3145 // new thread (a JavaThread *) to C++ thread object using the 3146 // "thread_oop" handle. 3147 3148 // Set the thread field (a JavaThread *) of the 3149 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3150 3151 Handle thread_oop(Thread::current(), 3152 JNIHandles::resolve_non_null(jni_thread)); 3153 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3154 "must be initialized"); 3155 set_threadObj(thread_oop()); 3156 java_lang_Thread::set_thread(thread_oop(), this); 3157 3158 if (prio == NoPriority) { 3159 prio = java_lang_Thread::priority(thread_oop()); 3160 assert(prio != NoPriority, "A valid priority should be present"); 3161 } 3162 3163 // Push the Java priority down to the native thread; needs Threads_lock 3164 Thread::set_priority(this, prio); 3165 3166 // Add the new thread to the Threads list and set it in motion. 3167 // We must have threads lock in order to call Threads::add. 3168 // It is crucial that we do not block before the thread is 3169 // added to the Threads list for if a GC happens, then the java_thread oop 3170 // will not be visited by GC. 3171 Threads::add(this); 3172 } 3173 3174 oop JavaThread::current_park_blocker() { 3175 // Support for JSR-166 locks 3176 oop thread_oop = threadObj(); 3177 if (thread_oop != NULL) { 3178 return java_lang_Thread::park_blocker(thread_oop); 3179 } 3180 return NULL; 3181 } 3182 3183 3184 void JavaThread::print_stack_on(outputStream* st) { 3185 if (!has_last_Java_frame()) return; 3186 ResourceMark rm; 3187 HandleMark hm; 3188 3189 RegisterMap reg_map(this); 3190 vframe* start_vf = last_java_vframe(®_map); 3191 int count = 0; 3192 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3193 if (f->is_java_frame()) { 3194 javaVFrame* jvf = javaVFrame::cast(f); 3195 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3196 3197 // Print out lock information 3198 if (JavaMonitorsInStackTrace) { 3199 jvf->print_lock_info_on(st, count); 3200 } 3201 } else { 3202 // Ignore non-Java frames 3203 } 3204 3205 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3206 count++; 3207 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3208 } 3209 } 3210 3211 3212 // JVMTI PopFrame support 3213 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3214 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3215 if (in_bytes(size_in_bytes) != 0) { 3216 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3217 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3218 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3219 } 3220 } 3221 3222 void* JavaThread::popframe_preserved_args() { 3223 return _popframe_preserved_args; 3224 } 3225 3226 ByteSize JavaThread::popframe_preserved_args_size() { 3227 return in_ByteSize(_popframe_preserved_args_size); 3228 } 3229 3230 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3231 int sz = in_bytes(popframe_preserved_args_size()); 3232 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3233 return in_WordSize(sz / wordSize); 3234 } 3235 3236 void JavaThread::popframe_free_preserved_args() { 3237 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3238 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3239 _popframe_preserved_args = NULL; 3240 _popframe_preserved_args_size = 0; 3241 } 3242 3243 #ifndef PRODUCT 3244 3245 void JavaThread::trace_frames() { 3246 tty->print_cr("[Describe stack]"); 3247 int frame_no = 1; 3248 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3249 tty->print(" %d. ", frame_no++); 3250 fst.current()->print_value_on(tty, this); 3251 tty->cr(); 3252 } 3253 } 3254 3255 class PrintAndVerifyOopClosure: public OopClosure { 3256 protected: 3257 template <class T> inline void do_oop_work(T* p) { 3258 oop obj = RawAccess<>::oop_load(p); 3259 if (obj == NULL) return; 3260 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3261 if (oopDesc::is_oop_or_null(obj)) { 3262 if (obj->is_objArray()) { 3263 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3264 } else { 3265 obj->print(); 3266 } 3267 } else { 3268 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3269 } 3270 tty->cr(); 3271 } 3272 public: 3273 virtual void do_oop(oop* p) { do_oop_work(p); } 3274 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3275 }; 3276 3277 #ifdef ASSERT 3278 // Print or validate the layout of stack frames 3279 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3280 ResourceMark rm; 3281 PRESERVE_EXCEPTION_MARK; 3282 FrameValues values; 3283 int frame_no = 0; 3284 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3285 fst.current()->describe(values, ++frame_no); 3286 if (depth == frame_no) break; 3287 } 3288 if (validate_only) { 3289 values.validate(); 3290 } else { 3291 tty->print_cr("[Describe stack layout]"); 3292 values.print(this); 3293 } 3294 } 3295 #endif 3296 3297 void JavaThread::trace_stack_from(vframe* start_vf) { 3298 ResourceMark rm; 3299 int vframe_no = 1; 3300 for (vframe* f = start_vf; f; f = f->sender()) { 3301 if (f->is_java_frame()) { 3302 javaVFrame::cast(f)->print_activation(vframe_no++); 3303 } else { 3304 f->print(); 3305 } 3306 if (vframe_no > StackPrintLimit) { 3307 tty->print_cr("...<more frames>..."); 3308 return; 3309 } 3310 } 3311 } 3312 3313 3314 void JavaThread::trace_stack() { 3315 if (!has_last_Java_frame()) return; 3316 ResourceMark rm; 3317 HandleMark hm; 3318 RegisterMap reg_map(this); 3319 trace_stack_from(last_java_vframe(®_map)); 3320 } 3321 3322 3323 #endif // PRODUCT 3324 3325 3326 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3327 assert(reg_map != NULL, "a map must be given"); 3328 frame f = last_frame(); 3329 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3330 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3331 } 3332 return NULL; 3333 } 3334 3335 3336 Klass* JavaThread::security_get_caller_class(int depth) { 3337 vframeStream vfst(this); 3338 vfst.security_get_caller_frame(depth); 3339 if (!vfst.at_end()) { 3340 return vfst.method()->method_holder(); 3341 } 3342 return NULL; 3343 } 3344 3345 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3346 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3347 CompileBroker::compiler_thread_loop(); 3348 } 3349 3350 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3351 NMethodSweeper::sweeper_loop(); 3352 } 3353 3354 // Create a CompilerThread 3355 CompilerThread::CompilerThread(CompileQueue* queue, 3356 CompilerCounters* counters) 3357 : JavaThread(&compiler_thread_entry) { 3358 _env = NULL; 3359 _log = NULL; 3360 _task = NULL; 3361 _queue = queue; 3362 _counters = counters; 3363 _buffer_blob = NULL; 3364 _compiler = NULL; 3365 3366 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3367 resource_area()->bias_to(mtCompiler); 3368 3369 #ifndef PRODUCT 3370 _ideal_graph_printer = NULL; 3371 #endif 3372 } 3373 3374 CompilerThread::~CompilerThread() { 3375 // Delete objects which were allocated on heap. 3376 delete _counters; 3377 } 3378 3379 bool CompilerThread::can_call_java() const { 3380 return _compiler != NULL && _compiler->is_jvmci(); 3381 } 3382 3383 // Create sweeper thread 3384 CodeCacheSweeperThread::CodeCacheSweeperThread() 3385 : JavaThread(&sweeper_thread_entry) { 3386 _scanned_compiled_method = NULL; 3387 } 3388 3389 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3390 JavaThread::oops_do(f, cf); 3391 if (_scanned_compiled_method != NULL && cf != NULL) { 3392 // Safepoints can occur when the sweeper is scanning an nmethod so 3393 // process it here to make sure it isn't unloaded in the middle of 3394 // a scan. 3395 cf->do_code_blob(_scanned_compiled_method); 3396 } 3397 } 3398 3399 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3400 JavaThread::nmethods_do(cf); 3401 if (_scanned_compiled_method != NULL && cf != NULL) { 3402 // Safepoints can occur when the sweeper is scanning an nmethod so 3403 // process it here to make sure it isn't unloaded in the middle of 3404 // a scan. 3405 cf->do_code_blob(_scanned_compiled_method); 3406 } 3407 } 3408 3409 3410 // ======= Threads ======== 3411 3412 // The Threads class links together all active threads, and provides 3413 // operations over all threads. It is protected by the Threads_lock, 3414 // which is also used in other global contexts like safepointing. 3415 // ThreadsListHandles are used to safely perform operations on one 3416 // or more threads without the risk of the thread exiting during the 3417 // operation. 3418 // 3419 // Note: The Threads_lock is currently more widely used than we 3420 // would like. We are actively migrating Threads_lock uses to other 3421 // mechanisms in order to reduce Threads_lock contention. 3422 3423 int Threads::_number_of_threads = 0; 3424 int Threads::_number_of_non_daemon_threads = 0; 3425 int Threads::_return_code = 0; 3426 uintx Threads::_thread_claim_token = 1; // Never zero. 3427 size_t JavaThread::_stack_size_at_create = 0; 3428 3429 #ifdef ASSERT 3430 bool Threads::_vm_complete = false; 3431 #endif 3432 3433 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3434 Prefetch::read((void*)addr, prefetch_interval); 3435 return *addr; 3436 } 3437 3438 // Possibly the ugliest for loop the world has seen. C++ does not allow 3439 // multiple types in the declaration section of the for loop. In this case 3440 // we are only dealing with pointers and hence can cast them. It looks ugly 3441 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3442 #define DO_JAVA_THREADS(LIST, X) \ 3443 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3444 *MACRO_list = (JavaThread*)(LIST), \ 3445 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3446 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3447 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3448 MACRO_current_p != MACRO_end; \ 3449 MACRO_current_p++, \ 3450 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3451 3452 // All JavaThreads 3453 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3454 3455 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3456 void Threads::non_java_threads_do(ThreadClosure* tc) { 3457 NoSafepointVerifier nsv; 3458 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3459 tc->do_thread(njti.current()); 3460 } 3461 } 3462 3463 // All JavaThreads 3464 void Threads::java_threads_do(ThreadClosure* tc) { 3465 assert_locked_or_safepoint(Threads_lock); 3466 // ALL_JAVA_THREADS iterates through all JavaThreads. 3467 ALL_JAVA_THREADS(p) { 3468 tc->do_thread(p); 3469 } 3470 } 3471 3472 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3473 assert_locked_or_safepoint(Threads_lock); 3474 java_threads_do(tc); 3475 tc->do_thread(VMThread::vm_thread()); 3476 } 3477 3478 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3479 void Threads::threads_do(ThreadClosure* tc) { 3480 assert_locked_or_safepoint(Threads_lock); 3481 java_threads_do(tc); 3482 non_java_threads_do(tc); 3483 } 3484 3485 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3486 uintx claim_token = Threads::thread_claim_token(); 3487 ALL_JAVA_THREADS(p) { 3488 if (p->claim_threads_do(is_par, claim_token)) { 3489 tc->do_thread(p); 3490 } 3491 } 3492 VMThread* vmt = VMThread::vm_thread(); 3493 if (vmt->claim_threads_do(is_par, claim_token)) { 3494 tc->do_thread(vmt); 3495 } 3496 } 3497 3498 // The system initialization in the library has three phases. 3499 // 3500 // Phase 1: java.lang.System class initialization 3501 // java.lang.System is a primordial class loaded and initialized 3502 // by the VM early during startup. java.lang.System.<clinit> 3503 // only does registerNatives and keeps the rest of the class 3504 // initialization work later until thread initialization completes. 3505 // 3506 // System.initPhase1 initializes the system properties, the static 3507 // fields in, out, and err. Set up java signal handlers, OS-specific 3508 // system settings, and thread group of the main thread. 3509 static void call_initPhase1(TRAPS) { 3510 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3511 JavaValue result(T_VOID); 3512 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3513 vmSymbols::void_method_signature(), CHECK); 3514 } 3515 3516 // Phase 2. Module system initialization 3517 // This will initialize the module system. Only java.base classes 3518 // can be loaded until phase 2 completes. 3519 // 3520 // Call System.initPhase2 after the compiler initialization and jsr292 3521 // classes get initialized because module initialization runs a lot of java 3522 // code, that for performance reasons, should be compiled. Also, this will 3523 // enable the startup code to use lambda and other language features in this 3524 // phase and onward. 3525 // 3526 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3527 static void call_initPhase2(TRAPS) { 3528 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3529 3530 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3531 3532 JavaValue result(T_INT); 3533 JavaCallArguments args; 3534 args.push_int(DisplayVMOutputToStderr); 3535 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3536 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3537 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3538 if (result.get_jint() != JNI_OK) { 3539 vm_exit_during_initialization(); // no message or exception 3540 } 3541 3542 universe_post_module_init(); 3543 } 3544 3545 // Phase 3. final setup - set security manager, system class loader and TCCL 3546 // 3547 // This will instantiate and set the security manager, set the system class 3548 // loader as well as the thread context class loader. The security manager 3549 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3550 // other modules or the application's classpath. 3551 static void call_initPhase3(TRAPS) { 3552 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3553 JavaValue result(T_VOID); 3554 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3555 vmSymbols::void_method_signature(), CHECK); 3556 } 3557 3558 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3559 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3560 3561 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3562 create_vm_init_libraries(); 3563 } 3564 3565 initialize_class(vmSymbols::java_lang_String(), CHECK); 3566 3567 // Inject CompactStrings value after the static initializers for String ran. 3568 java_lang_String::set_compact_strings(CompactStrings); 3569 3570 // Initialize java_lang.System (needed before creating the thread) 3571 initialize_class(vmSymbols::java_lang_System(), CHECK); 3572 // The VM creates & returns objects of this class. Make sure it's initialized. 3573 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3574 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3575 Handle thread_group = create_initial_thread_group(CHECK); 3576 Universe::set_main_thread_group(thread_group()); 3577 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3578 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3579 main_thread->set_threadObj(thread_object); 3580 3581 // Set thread status to running since main thread has 3582 // been started and running. 3583 java_lang_Thread::set_thread_status(thread_object, 3584 java_lang_Thread::RUNNABLE); 3585 3586 // The VM creates objects of this class. 3587 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3588 3589 #ifdef ASSERT 3590 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3591 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3592 #endif 3593 3594 // initialize the hardware-specific constants needed by Unsafe 3595 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3596 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3597 3598 // The VM preresolves methods to these classes. Make sure that they get initialized 3599 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3600 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3601 3602 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3603 call_initPhase1(CHECK); 3604 3605 // get the Java runtime name after java.lang.System is initialized 3606 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3607 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3608 3609 // an instance of OutOfMemory exception has been allocated earlier 3610 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3611 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3612 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3613 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3614 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3615 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3616 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3617 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3618 3619 // Eager box cache initialization only if AOT is on and any library is loaded. 3620 AOTLoader::initialize_box_caches(CHECK); 3621 } 3622 3623 void Threads::initialize_jsr292_core_classes(TRAPS) { 3624 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3625 3626 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3627 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3628 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3629 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3630 } 3631 3632 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3633 extern void JDK_Version_init(); 3634 3635 // Preinitialize version info. 3636 VM_Version::early_initialize(); 3637 3638 // Check version 3639 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3640 3641 // Initialize library-based TLS 3642 ThreadLocalStorage::init(); 3643 3644 // Initialize the output stream module 3645 ostream_init(); 3646 3647 // Process java launcher properties. 3648 Arguments::process_sun_java_launcher_properties(args); 3649 3650 // Initialize the os module 3651 os::init(); 3652 3653 // Record VM creation timing statistics 3654 TraceVmCreationTime create_vm_timer; 3655 create_vm_timer.start(); 3656 3657 // Initialize system properties. 3658 Arguments::init_system_properties(); 3659 3660 // So that JDK version can be used as a discriminator when parsing arguments 3661 JDK_Version_init(); 3662 3663 // Update/Initialize System properties after JDK version number is known 3664 Arguments::init_version_specific_system_properties(); 3665 3666 // Make sure to initialize log configuration *before* parsing arguments 3667 LogConfiguration::initialize(create_vm_timer.begin_time()); 3668 3669 // Parse arguments 3670 // Note: this internally calls os::init_container_support() 3671 jint parse_result = Arguments::parse(args); 3672 if (parse_result != JNI_OK) return parse_result; 3673 3674 os::init_before_ergo(); 3675 3676 jint ergo_result = Arguments::apply_ergo(); 3677 if (ergo_result != JNI_OK) return ergo_result; 3678 3679 // Final check of all ranges after ergonomics which may change values. 3680 if (!JVMFlagRangeList::check_ranges()) { 3681 return JNI_EINVAL; 3682 } 3683 3684 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3685 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3686 if (!constraint_result) { 3687 return JNI_EINVAL; 3688 } 3689 3690 JVMFlagWriteableList::mark_startup(); 3691 3692 if (PauseAtStartup) { 3693 os::pause(); 3694 } 3695 3696 HOTSPOT_VM_INIT_BEGIN(); 3697 3698 // Timing (must come after argument parsing) 3699 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3700 3701 // Initialize the os module after parsing the args 3702 jint os_init_2_result = os::init_2(); 3703 if (os_init_2_result != JNI_OK) return os_init_2_result; 3704 3705 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3706 // Initialize assert poison page mechanism. 3707 if (ShowRegistersOnAssert) { 3708 initialize_assert_poison(); 3709 } 3710 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3711 3712 SafepointMechanism::initialize(); 3713 3714 jint adjust_after_os_result = Arguments::adjust_after_os(); 3715 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3716 3717 // Initialize output stream logging 3718 ostream_init_log(); 3719 3720 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3721 // Must be before create_vm_init_agents() 3722 if (Arguments::init_libraries_at_startup()) { 3723 convert_vm_init_libraries_to_agents(); 3724 } 3725 3726 // Launch -agentlib/-agentpath and converted -Xrun agents 3727 if (Arguments::init_agents_at_startup()) { 3728 create_vm_init_agents(); 3729 } 3730 3731 // Initialize Threads state 3732 _number_of_threads = 0; 3733 _number_of_non_daemon_threads = 0; 3734 3735 // Initialize global data structures and create system classes in heap 3736 vm_init_globals(); 3737 3738 #if INCLUDE_JVMCI 3739 if (JVMCICounterSize > 0) { 3740 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3741 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3742 } else { 3743 JavaThread::_jvmci_old_thread_counters = NULL; 3744 } 3745 #endif // INCLUDE_JVMCI 3746 3747 // Attach the main thread to this os thread 3748 JavaThread* main_thread = new JavaThread(); 3749 main_thread->set_thread_state(_thread_in_vm); 3750 main_thread->initialize_thread_current(); 3751 // must do this before set_active_handles 3752 main_thread->record_stack_base_and_size(); 3753 main_thread->register_thread_stack_with_NMT(); 3754 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3755 3756 if (!main_thread->set_as_starting_thread()) { 3757 vm_shutdown_during_initialization( 3758 "Failed necessary internal allocation. Out of swap space"); 3759 main_thread->smr_delete(); 3760 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3761 return JNI_ENOMEM; 3762 } 3763 3764 // Enable guard page *after* os::create_main_thread(), otherwise it would 3765 // crash Linux VM, see notes in os_linux.cpp. 3766 main_thread->create_stack_guard_pages(); 3767 3768 // Initialize Java-Level synchronization subsystem 3769 ObjectMonitor::Initialize(); 3770 3771 // Initialize global modules 3772 jint status = init_globals(); 3773 if (status != JNI_OK) { 3774 main_thread->smr_delete(); 3775 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3776 return status; 3777 } 3778 3779 JFR_ONLY(Jfr::on_vm_init();) 3780 3781 // Should be done after the heap is fully created 3782 main_thread->cache_global_variables(); 3783 3784 HandleMark hm; 3785 3786 { MutexLocker mu(Threads_lock); 3787 Threads::add(main_thread); 3788 } 3789 3790 // Any JVMTI raw monitors entered in onload will transition into 3791 // real raw monitor. VM is setup enough here for raw monitor enter. 3792 JvmtiExport::transition_pending_onload_raw_monitors(); 3793 3794 // Create the VMThread 3795 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3796 3797 VMThread::create(); 3798 Thread* vmthread = VMThread::vm_thread(); 3799 3800 if (!os::create_thread(vmthread, os::vm_thread)) { 3801 vm_exit_during_initialization("Cannot create VM thread. " 3802 "Out of system resources."); 3803 } 3804 3805 // Wait for the VM thread to become ready, and VMThread::run to initialize 3806 // Monitors can have spurious returns, must always check another state flag 3807 { 3808 MonitorLocker ml(Notify_lock); 3809 os::start_thread(vmthread); 3810 while (vmthread->active_handles() == NULL) { 3811 ml.wait(); 3812 } 3813 } 3814 } 3815 3816 assert(Universe::is_fully_initialized(), "not initialized"); 3817 if (VerifyDuringStartup) { 3818 // Make sure we're starting with a clean slate. 3819 VM_Verify verify_op; 3820 VMThread::execute(&verify_op); 3821 } 3822 3823 // We need this to update the java.vm.info property in case any flags used 3824 // to initially define it have been changed. This is needed for both CDS and 3825 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3826 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3827 // This update must happen before we initialize the java classes, but 3828 // after any initialization logic that might modify the flags. 3829 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3830 3831 Thread* THREAD = Thread::current(); 3832 3833 // Always call even when there are not JVMTI environments yet, since environments 3834 // may be attached late and JVMTI must track phases of VM execution 3835 JvmtiExport::enter_early_start_phase(); 3836 3837 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3838 JvmtiExport::post_early_vm_start(); 3839 3840 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3841 3842 quicken_jni_functions(); 3843 3844 // No more stub generation allowed after that point. 3845 StubCodeDesc::freeze(); 3846 3847 // Set flag that basic initialization has completed. Used by exceptions and various 3848 // debug stuff, that does not work until all basic classes have been initialized. 3849 set_init_completed(); 3850 3851 LogConfiguration::post_initialize(); 3852 Metaspace::post_initialize(); 3853 3854 HOTSPOT_VM_INIT_END(); 3855 3856 // record VM initialization completion time 3857 #if INCLUDE_MANAGEMENT 3858 Management::record_vm_init_completed(); 3859 #endif // INCLUDE_MANAGEMENT 3860 3861 // Signal Dispatcher needs to be started before VMInit event is posted 3862 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3863 3864 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3865 if (!DisableAttachMechanism) { 3866 AttachListener::vm_start(); 3867 if (StartAttachListener || AttachListener::init_at_startup()) { 3868 AttachListener::init(); 3869 } 3870 } 3871 3872 // Launch -Xrun agents 3873 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3874 // back-end can launch with -Xdebug -Xrunjdwp. 3875 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3876 create_vm_init_libraries(); 3877 } 3878 3879 if (CleanChunkPoolAsync) { 3880 Chunk::start_chunk_pool_cleaner_task(); 3881 } 3882 3883 3884 // initialize compiler(s) 3885 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3886 #if INCLUDE_JVMCI 3887 bool force_JVMCI_intialization = false; 3888 if (EnableJVMCI) { 3889 // Initialize JVMCI eagerly when it is explicitly requested. 3890 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 3891 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 3892 3893 if (!force_JVMCI_intialization) { 3894 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3895 // compilations via JVMCI will not actually block until JVMCI is initialized. 3896 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3897 } 3898 } 3899 #endif 3900 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3901 // Postpone completion of compiler initialization to after JVMCI 3902 // is initialized to avoid timeouts of blocking compilations. 3903 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3904 CompileBroker::compilation_init_phase2(); 3905 } 3906 #endif 3907 3908 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3909 // It is done after compilers are initialized, because otherwise compilations of 3910 // signature polymorphic MH intrinsics can be missed 3911 // (see SystemDictionary::find_method_handle_intrinsic). 3912 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3913 3914 // This will initialize the module system. Only java.base classes can be 3915 // loaded until phase 2 completes 3916 call_initPhase2(CHECK_JNI_ERR); 3917 3918 // Always call even when there are not JVMTI environments yet, since environments 3919 // may be attached late and JVMTI must track phases of VM execution 3920 JvmtiExport::enter_start_phase(); 3921 3922 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3923 JvmtiExport::post_vm_start(); 3924 3925 // Final system initialization including security manager and system class loader 3926 call_initPhase3(CHECK_JNI_ERR); 3927 3928 // cache the system and platform class loaders 3929 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3930 3931 #if INCLUDE_CDS 3932 // capture the module path info from the ModuleEntryTable 3933 ClassLoader::initialize_module_path(THREAD); 3934 #endif 3935 3936 #if INCLUDE_JVMCI 3937 if (force_JVMCI_intialization) { 3938 JVMCI::initialize_compiler(CHECK_JNI_ERR); 3939 CompileBroker::compilation_init_phase2(); 3940 } 3941 #endif 3942 3943 // Always call even when there are not JVMTI environments yet, since environments 3944 // may be attached late and JVMTI must track phases of VM execution 3945 JvmtiExport::enter_live_phase(); 3946 3947 // Make perfmemory accessible 3948 PerfMemory::set_accessible(true); 3949 3950 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3951 JvmtiExport::post_vm_initialized(); 3952 3953 JFR_ONLY(Jfr::on_vm_start();) 3954 3955 #if INCLUDE_MANAGEMENT 3956 Management::initialize(THREAD); 3957 3958 if (HAS_PENDING_EXCEPTION) { 3959 // management agent fails to start possibly due to 3960 // configuration problem and is responsible for printing 3961 // stack trace if appropriate. Simply exit VM. 3962 vm_exit(1); 3963 } 3964 #endif // INCLUDE_MANAGEMENT 3965 3966 if (MemProfiling) MemProfiler::engage(); 3967 StatSampler::engage(); 3968 if (CheckJNICalls) JniPeriodicChecker::engage(); 3969 3970 BiasedLocking::init(); 3971 3972 #if INCLUDE_RTM_OPT 3973 RTMLockingCounters::init(); 3974 #endif 3975 3976 call_postVMInitHook(THREAD); 3977 // The Java side of PostVMInitHook.run must deal with all 3978 // exceptions and provide means of diagnosis. 3979 if (HAS_PENDING_EXCEPTION) { 3980 CLEAR_PENDING_EXCEPTION; 3981 } 3982 3983 { 3984 MutexLocker ml(PeriodicTask_lock); 3985 // Make sure the WatcherThread can be started by WatcherThread::start() 3986 // or by dynamic enrollment. 3987 WatcherThread::make_startable(); 3988 // Start up the WatcherThread if there are any periodic tasks 3989 // NOTE: All PeriodicTasks should be registered by now. If they 3990 // aren't, late joiners might appear to start slowly (we might 3991 // take a while to process their first tick). 3992 if (PeriodicTask::num_tasks() > 0) { 3993 WatcherThread::start(); 3994 } 3995 } 3996 3997 create_vm_timer.end(); 3998 #ifdef ASSERT 3999 _vm_complete = true; 4000 #endif 4001 4002 if (DumpSharedSpaces) { 4003 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4004 ShouldNotReachHere(); 4005 } 4006 4007 return JNI_OK; 4008 } 4009 4010 // type for the Agent_OnLoad and JVM_OnLoad entry points 4011 extern "C" { 4012 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4013 } 4014 // Find a command line agent library and return its entry point for 4015 // -agentlib: -agentpath: -Xrun 4016 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4017 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4018 const char *on_load_symbols[], 4019 size_t num_symbol_entries) { 4020 OnLoadEntry_t on_load_entry = NULL; 4021 void *library = NULL; 4022 4023 if (!agent->valid()) { 4024 char buffer[JVM_MAXPATHLEN]; 4025 char ebuf[1024] = ""; 4026 const char *name = agent->name(); 4027 const char *msg = "Could not find agent library "; 4028 4029 // First check to see if agent is statically linked into executable 4030 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4031 library = agent->os_lib(); 4032 } else if (agent->is_absolute_path()) { 4033 library = os::dll_load(name, ebuf, sizeof ebuf); 4034 if (library == NULL) { 4035 const char *sub_msg = " in absolute path, with error: "; 4036 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4037 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4038 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4039 // If we can't find the agent, exit. 4040 vm_exit_during_initialization(buf, NULL); 4041 FREE_C_HEAP_ARRAY(char, buf); 4042 } 4043 } else { 4044 // Try to load the agent from the standard dll directory 4045 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4046 name)) { 4047 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4048 } 4049 if (library == NULL) { // Try the library path directory. 4050 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4051 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4052 } 4053 if (library == NULL) { 4054 const char *sub_msg = " on the library path, with error: "; 4055 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4056 4057 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4058 strlen(ebuf) + strlen(sub_msg2) + 1; 4059 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4060 if (!agent->is_instrument_lib()) { 4061 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4062 } else { 4063 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4064 } 4065 // If we can't find the agent, exit. 4066 vm_exit_during_initialization(buf, NULL); 4067 FREE_C_HEAP_ARRAY(char, buf); 4068 } 4069 } 4070 } 4071 agent->set_os_lib(library); 4072 agent->set_valid(); 4073 } 4074 4075 // Find the OnLoad function. 4076 on_load_entry = 4077 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4078 false, 4079 on_load_symbols, 4080 num_symbol_entries)); 4081 return on_load_entry; 4082 } 4083 4084 // Find the JVM_OnLoad entry point 4085 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4086 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4087 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4088 } 4089 4090 // Find the Agent_OnLoad entry point 4091 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4092 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4093 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4094 } 4095 4096 // For backwards compatibility with -Xrun 4097 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4098 // treated like -agentpath: 4099 // Must be called before agent libraries are created 4100 void Threads::convert_vm_init_libraries_to_agents() { 4101 AgentLibrary* agent; 4102 AgentLibrary* next; 4103 4104 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4105 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4106 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4107 4108 // If there is an JVM_OnLoad function it will get called later, 4109 // otherwise see if there is an Agent_OnLoad 4110 if (on_load_entry == NULL) { 4111 on_load_entry = lookup_agent_on_load(agent); 4112 if (on_load_entry != NULL) { 4113 // switch it to the agent list -- so that Agent_OnLoad will be called, 4114 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4115 Arguments::convert_library_to_agent(agent); 4116 } else { 4117 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4118 } 4119 } 4120 } 4121 } 4122 4123 // Create agents for -agentlib: -agentpath: and converted -Xrun 4124 // Invokes Agent_OnLoad 4125 // Called very early -- before JavaThreads exist 4126 void Threads::create_vm_init_agents() { 4127 extern struct JavaVM_ main_vm; 4128 AgentLibrary* agent; 4129 4130 JvmtiExport::enter_onload_phase(); 4131 4132 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4133 // CDS dumping does not support native JVMTI agent. 4134 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4135 if (DumpSharedSpaces || DynamicDumpSharedSpaces) { 4136 if(!agent->is_instrument_lib()) { 4137 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4138 } else if (!AllowArchivingWithJavaAgent) { 4139 vm_exit_during_cds_dumping( 4140 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4141 } 4142 } 4143 4144 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4145 4146 if (on_load_entry != NULL) { 4147 // Invoke the Agent_OnLoad function 4148 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4149 if (err != JNI_OK) { 4150 vm_exit_during_initialization("agent library failed to init", agent->name()); 4151 } 4152 } else { 4153 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4154 } 4155 } 4156 4157 JvmtiExport::enter_primordial_phase(); 4158 } 4159 4160 extern "C" { 4161 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4162 } 4163 4164 void Threads::shutdown_vm_agents() { 4165 // Send any Agent_OnUnload notifications 4166 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4167 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4168 extern struct JavaVM_ main_vm; 4169 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4170 4171 // Find the Agent_OnUnload function. 4172 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4173 os::find_agent_function(agent, 4174 false, 4175 on_unload_symbols, 4176 num_symbol_entries)); 4177 4178 // Invoke the Agent_OnUnload function 4179 if (unload_entry != NULL) { 4180 JavaThread* thread = JavaThread::current(); 4181 ThreadToNativeFromVM ttn(thread); 4182 HandleMark hm(thread); 4183 (*unload_entry)(&main_vm); 4184 } 4185 } 4186 } 4187 4188 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4189 // Invokes JVM_OnLoad 4190 void Threads::create_vm_init_libraries() { 4191 extern struct JavaVM_ main_vm; 4192 AgentLibrary* agent; 4193 4194 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4195 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4196 4197 if (on_load_entry != NULL) { 4198 // Invoke the JVM_OnLoad function 4199 JavaThread* thread = JavaThread::current(); 4200 ThreadToNativeFromVM ttn(thread); 4201 HandleMark hm(thread); 4202 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4203 if (err != JNI_OK) { 4204 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4205 } 4206 } else { 4207 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4208 } 4209 } 4210 } 4211 4212 4213 // Last thread running calls java.lang.Shutdown.shutdown() 4214 void JavaThread::invoke_shutdown_hooks() { 4215 HandleMark hm(this); 4216 4217 // We could get here with a pending exception, if so clear it now. 4218 if (this->has_pending_exception()) { 4219 this->clear_pending_exception(); 4220 } 4221 4222 EXCEPTION_MARK; 4223 Klass* shutdown_klass = 4224 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4225 THREAD); 4226 if (shutdown_klass != NULL) { 4227 // SystemDictionary::resolve_or_null will return null if there was 4228 // an exception. If we cannot load the Shutdown class, just don't 4229 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4230 // won't be run. Note that if a shutdown hook was registered, 4231 // the Shutdown class would have already been loaded 4232 // (Runtime.addShutdownHook will load it). 4233 JavaValue result(T_VOID); 4234 JavaCalls::call_static(&result, 4235 shutdown_klass, 4236 vmSymbols::shutdown_name(), 4237 vmSymbols::void_method_signature(), 4238 THREAD); 4239 } 4240 CLEAR_PENDING_EXCEPTION; 4241 } 4242 4243 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4244 // the program falls off the end of main(). Another VM exit path is through 4245 // vm_exit() when the program calls System.exit() to return a value or when 4246 // there is a serious error in VM. The two shutdown paths are not exactly 4247 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4248 // and VM_Exit op at VM level. 4249 // 4250 // Shutdown sequence: 4251 // + Shutdown native memory tracking if it is on 4252 // + Wait until we are the last non-daemon thread to execute 4253 // <-- every thing is still working at this moment --> 4254 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4255 // shutdown hooks 4256 // + Call before_exit(), prepare for VM exit 4257 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4258 // currently the only user of this mechanism is File.deleteOnExit()) 4259 // > stop StatSampler, watcher thread, CMS threads, 4260 // post thread end and vm death events to JVMTI, 4261 // stop signal thread 4262 // + Call JavaThread::exit(), it will: 4263 // > release JNI handle blocks, remove stack guard pages 4264 // > remove this thread from Threads list 4265 // <-- no more Java code from this thread after this point --> 4266 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4267 // the compiler threads at safepoint 4268 // <-- do not use anything that could get blocked by Safepoint --> 4269 // + Disable tracing at JNI/JVM barriers 4270 // + Set _vm_exited flag for threads that are still running native code 4271 // + Call exit_globals() 4272 // > deletes tty 4273 // > deletes PerfMemory resources 4274 // + Delete this thread 4275 // + Return to caller 4276 4277 bool Threads::destroy_vm() { 4278 JavaThread* thread = JavaThread::current(); 4279 4280 #ifdef ASSERT 4281 _vm_complete = false; 4282 #endif 4283 // Wait until we are the last non-daemon thread to execute 4284 { MonitorLocker nu(Threads_lock); 4285 while (Threads::number_of_non_daemon_threads() > 1) 4286 // This wait should make safepoint checks, wait without a timeout, 4287 // and wait as a suspend-equivalent condition. 4288 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4289 } 4290 4291 EventShutdown e; 4292 if (e.should_commit()) { 4293 e.set_reason("No remaining non-daemon Java threads"); 4294 e.commit(); 4295 } 4296 4297 // Hang forever on exit if we are reporting an error. 4298 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4299 os::infinite_sleep(); 4300 } 4301 os::wait_for_keypress_at_exit(); 4302 4303 // run Java level shutdown hooks 4304 thread->invoke_shutdown_hooks(); 4305 4306 before_exit(thread); 4307 4308 thread->exit(true); 4309 4310 // Stop VM thread. 4311 { 4312 // 4945125 The vm thread comes to a safepoint during exit. 4313 // GC vm_operations can get caught at the safepoint, and the 4314 // heap is unparseable if they are caught. Grab the Heap_lock 4315 // to prevent this. The GC vm_operations will not be able to 4316 // queue until after the vm thread is dead. After this point, 4317 // we'll never emerge out of the safepoint before the VM exits. 4318 4319 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4320 4321 VMThread::wait_for_vm_thread_exit(); 4322 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4323 VMThread::destroy(); 4324 } 4325 4326 // Now, all Java threads are gone except daemon threads. Daemon threads 4327 // running Java code or in VM are stopped by the Safepoint. However, 4328 // daemon threads executing native code are still running. But they 4329 // will be stopped at native=>Java/VM barriers. Note that we can't 4330 // simply kill or suspend them, as it is inherently deadlock-prone. 4331 4332 VM_Exit::set_vm_exited(); 4333 4334 // Clean up ideal graph printers after the VMThread has started 4335 // the final safepoint which will block all the Compiler threads. 4336 // Note that this Thread has already logically exited so the 4337 // clean_up() function's use of a JavaThreadIteratorWithHandle 4338 // would be a problem except set_vm_exited() has remembered the 4339 // shutdown thread which is granted a policy exception. 4340 #if defined(COMPILER2) && !defined(PRODUCT) 4341 IdealGraphPrinter::clean_up(); 4342 #endif 4343 4344 notify_vm_shutdown(); 4345 4346 // exit_globals() will delete tty 4347 exit_globals(); 4348 4349 // We are after VM_Exit::set_vm_exited() so we can't call 4350 // thread->smr_delete() or we will block on the Threads_lock. 4351 // Deleting the shutdown thread here is safe because another 4352 // JavaThread cannot have an active ThreadsListHandle for 4353 // this JavaThread. 4354 delete thread; 4355 4356 #if INCLUDE_JVMCI 4357 if (JVMCICounterSize > 0) { 4358 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4359 } 4360 #endif 4361 4362 LogConfiguration::finalize(); 4363 4364 return true; 4365 } 4366 4367 4368 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4369 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4370 return is_supported_jni_version(version); 4371 } 4372 4373 4374 jboolean Threads::is_supported_jni_version(jint version) { 4375 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4376 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4377 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4378 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4379 if (version == JNI_VERSION_9) return JNI_TRUE; 4380 if (version == JNI_VERSION_10) return JNI_TRUE; 4381 return JNI_FALSE; 4382 } 4383 4384 4385 void Threads::add(JavaThread* p, bool force_daemon) { 4386 // The threads lock must be owned at this point 4387 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4388 4389 BarrierSet::barrier_set()->on_thread_attach(p); 4390 4391 // Once a JavaThread is added to the Threads list, smr_delete() has 4392 // to be used to delete it. Otherwise we can just delete it directly. 4393 p->set_on_thread_list(); 4394 4395 _number_of_threads++; 4396 oop threadObj = p->threadObj(); 4397 bool daemon = true; 4398 // Bootstrapping problem: threadObj can be null for initial 4399 // JavaThread (or for threads attached via JNI) 4400 if ((!force_daemon) && !is_daemon((threadObj))) { 4401 _number_of_non_daemon_threads++; 4402 daemon = false; 4403 } 4404 4405 ThreadService::add_thread(p, daemon); 4406 4407 // Maintain fast thread list 4408 ThreadsSMRSupport::add_thread(p); 4409 4410 // Possible GC point. 4411 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4412 } 4413 4414 void Threads::remove(JavaThread* p, bool is_daemon) { 4415 4416 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4417 ObjectSynchronizer::om_flush(p); 4418 4419 // Extra scope needed for Thread_lock, so we can check 4420 // that we do not remove thread without safepoint code notice 4421 { MonitorLocker ml(Threads_lock); 4422 4423 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4424 4425 // Maintain fast thread list 4426 ThreadsSMRSupport::remove_thread(p); 4427 4428 _number_of_threads--; 4429 if (!is_daemon) { 4430 _number_of_non_daemon_threads--; 4431 4432 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4433 // on destroy_vm will wake up. 4434 if (number_of_non_daemon_threads() == 1) { 4435 ml.notify_all(); 4436 } 4437 } 4438 ThreadService::remove_thread(p, is_daemon); 4439 4440 // Make sure that safepoint code disregard this thread. This is needed since 4441 // the thread might mess around with locks after this point. This can cause it 4442 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4443 // of this thread since it is removed from the queue. 4444 p->set_terminated_value(); 4445 } // unlock Threads_lock 4446 4447 // Since Events::log uses a lock, we grab it outside the Threads_lock 4448 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4449 } 4450 4451 // Operations on the Threads list for GC. These are not explicitly locked, 4452 // but the garbage collector must provide a safe context for them to run. 4453 // In particular, these things should never be called when the Threads_lock 4454 // is held by some other thread. (Note: the Safepoint abstraction also 4455 // uses the Threads_lock to guarantee this property. It also makes sure that 4456 // all threads gets blocked when exiting or starting). 4457 4458 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4459 ALL_JAVA_THREADS(p) { 4460 p->oops_do(f, cf); 4461 } 4462 VMThread::vm_thread()->oops_do(f, cf); 4463 } 4464 4465 void Threads::change_thread_claim_token() { 4466 if (++_thread_claim_token == 0) { 4467 // On overflow of the token counter, there is a risk of future 4468 // collisions between a new global token value and a stale token 4469 // for a thread, because not all iterations visit all threads. 4470 // (Though it's pretty much a theoretical concern for non-trivial 4471 // token counter sizes.) To deal with the possibility, reset all 4472 // the thread tokens to zero on global token overflow. 4473 struct ResetClaims : public ThreadClosure { 4474 virtual void do_thread(Thread* t) { 4475 t->claim_threads_do(false, 0); 4476 } 4477 } reset_claims; 4478 Threads::threads_do(&reset_claims); 4479 // On overflow, update the global token to non-zero, to 4480 // avoid the special "never claimed" initial thread value. 4481 _thread_claim_token = 1; 4482 } 4483 } 4484 4485 #ifdef ASSERT 4486 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4487 const uintx token = t->threads_do_token(); 4488 assert(token == expected, 4489 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4490 UINTX_FORMAT, kind, p2i(t), token, expected); 4491 } 4492 4493 void Threads::assert_all_threads_claimed() { 4494 ALL_JAVA_THREADS(p) { 4495 assert_thread_claimed("Thread", p, _thread_claim_token); 4496 } 4497 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4498 } 4499 #endif // ASSERT 4500 4501 class ParallelOopsDoThreadClosure : public ThreadClosure { 4502 private: 4503 OopClosure* _f; 4504 CodeBlobClosure* _cf; 4505 public: 4506 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4507 void do_thread(Thread* t) { 4508 t->oops_do(_f, _cf); 4509 } 4510 }; 4511 4512 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4513 ParallelOopsDoThreadClosure tc(f, cf); 4514 possibly_parallel_threads_do(is_par, &tc); 4515 } 4516 4517 void Threads::nmethods_do(CodeBlobClosure* cf) { 4518 ALL_JAVA_THREADS(p) { 4519 // This is used by the code cache sweeper to mark nmethods that are active 4520 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4521 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4522 if(!p->is_Code_cache_sweeper_thread()) { 4523 p->nmethods_do(cf); 4524 } 4525 } 4526 } 4527 4528 void Threads::metadata_do(MetadataClosure* f) { 4529 ALL_JAVA_THREADS(p) { 4530 p->metadata_do(f); 4531 } 4532 } 4533 4534 class ThreadHandlesClosure : public ThreadClosure { 4535 void (*_f)(Metadata*); 4536 public: 4537 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4538 virtual void do_thread(Thread* thread) { 4539 thread->metadata_handles_do(_f); 4540 } 4541 }; 4542 4543 void Threads::metadata_handles_do(void f(Metadata*)) { 4544 // Only walk the Handles in Thread. 4545 ThreadHandlesClosure handles_closure(f); 4546 threads_do(&handles_closure); 4547 } 4548 4549 // Get count Java threads that are waiting to enter the specified monitor. 4550 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4551 int count, 4552 address monitor) { 4553 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4554 4555 int i = 0; 4556 DO_JAVA_THREADS(t_list, p) { 4557 if (!p->can_call_java()) continue; 4558 4559 address pending = (address)p->current_pending_monitor(); 4560 if (pending == monitor) { // found a match 4561 if (i < count) result->append(p); // save the first count matches 4562 i++; 4563 } 4564 } 4565 4566 return result; 4567 } 4568 4569 4570 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4571 address owner) { 4572 // NULL owner means not locked so we can skip the search 4573 if (owner == NULL) return NULL; 4574 4575 DO_JAVA_THREADS(t_list, p) { 4576 // first, see if owner is the address of a Java thread 4577 if (owner == (address)p) return p; 4578 } 4579 4580 // Cannot assert on lack of success here since this function may be 4581 // used by code that is trying to report useful problem information 4582 // like deadlock detection. 4583 if (UseHeavyMonitors) return NULL; 4584 4585 // If we didn't find a matching Java thread and we didn't force use of 4586 // heavyweight monitors, then the owner is the stack address of the 4587 // Lock Word in the owning Java thread's stack. 4588 // 4589 JavaThread* the_owner = NULL; 4590 DO_JAVA_THREADS(t_list, q) { 4591 if (q->is_lock_owned(owner)) { 4592 the_owner = q; 4593 break; 4594 } 4595 } 4596 4597 // cannot assert on lack of success here; see above comment 4598 return the_owner; 4599 } 4600 4601 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4602 void Threads::print_on(outputStream* st, bool print_stacks, 4603 bool internal_format, bool print_concurrent_locks, 4604 bool print_extended_info) { 4605 char buf[32]; 4606 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4607 4608 st->print_cr("Full thread dump %s (%s %s):", 4609 VM_Version::vm_name(), 4610 VM_Version::vm_release(), 4611 VM_Version::vm_info_string()); 4612 st->cr(); 4613 4614 #if INCLUDE_SERVICES 4615 // Dump concurrent locks 4616 ConcurrentLocksDump concurrent_locks; 4617 if (print_concurrent_locks) { 4618 concurrent_locks.dump_at_safepoint(); 4619 } 4620 #endif // INCLUDE_SERVICES 4621 4622 ThreadsSMRSupport::print_info_on(st); 4623 st->cr(); 4624 4625 ALL_JAVA_THREADS(p) { 4626 ResourceMark rm; 4627 p->print_on(st, print_extended_info); 4628 if (print_stacks) { 4629 if (internal_format) { 4630 p->trace_stack(); 4631 } else { 4632 p->print_stack_on(st); 4633 } 4634 } 4635 st->cr(); 4636 #if INCLUDE_SERVICES 4637 if (print_concurrent_locks) { 4638 concurrent_locks.print_locks_on(p, st); 4639 } 4640 #endif // INCLUDE_SERVICES 4641 } 4642 4643 VMThread::vm_thread()->print_on(st); 4644 st->cr(); 4645 Universe::heap()->print_gc_threads_on(st); 4646 WatcherThread* wt = WatcherThread::watcher_thread(); 4647 if (wt != NULL) { 4648 wt->print_on(st); 4649 st->cr(); 4650 } 4651 4652 st->flush(); 4653 } 4654 4655 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4656 int buflen, bool* found_current) { 4657 if (this_thread != NULL) { 4658 bool is_current = (current == this_thread); 4659 *found_current = *found_current || is_current; 4660 st->print("%s", is_current ? "=>" : " "); 4661 4662 st->print(PTR_FORMAT, p2i(this_thread)); 4663 st->print(" "); 4664 this_thread->print_on_error(st, buf, buflen); 4665 st->cr(); 4666 } 4667 } 4668 4669 class PrintOnErrorClosure : public ThreadClosure { 4670 outputStream* _st; 4671 Thread* _current; 4672 char* _buf; 4673 int _buflen; 4674 bool* _found_current; 4675 public: 4676 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4677 int buflen, bool* found_current) : 4678 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4679 4680 virtual void do_thread(Thread* thread) { 4681 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4682 } 4683 }; 4684 4685 // Threads::print_on_error() is called by fatal error handler. It's possible 4686 // that VM is not at safepoint and/or current thread is inside signal handler. 4687 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4688 // memory (even in resource area), it might deadlock the error handler. 4689 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4690 int buflen) { 4691 ThreadsSMRSupport::print_info_on(st); 4692 st->cr(); 4693 4694 bool found_current = false; 4695 st->print_cr("Java Threads: ( => current thread )"); 4696 ALL_JAVA_THREADS(thread) { 4697 print_on_error(thread, st, current, buf, buflen, &found_current); 4698 } 4699 st->cr(); 4700 4701 st->print_cr("Other Threads:"); 4702 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4703 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4704 4705 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4706 Universe::heap()->gc_threads_do(&print_closure); 4707 4708 if (!found_current) { 4709 st->cr(); 4710 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4711 current->print_on_error(st, buf, buflen); 4712 st->cr(); 4713 } 4714 st->cr(); 4715 4716 st->print_cr("Threads with active compile tasks:"); 4717 print_threads_compiling(st, buf, buflen); 4718 } 4719 4720 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4721 ALL_JAVA_THREADS(thread) { 4722 if (thread->is_Compiler_thread()) { 4723 CompilerThread* ct = (CompilerThread*) thread; 4724 4725 // Keep task in local variable for NULL check. 4726 // ct->_task might be set to NULL by concurring compiler thread 4727 // because it completed the compilation. The task is never freed, 4728 // though, just returned to a free list. 4729 CompileTask* task = ct->task(); 4730 if (task != NULL) { 4731 thread->print_name_on_error(st, buf, buflen); 4732 st->print(" "); 4733 task->print(st, NULL, short_form, true); 4734 } 4735 } 4736 } 4737 } 4738 4739 4740 // Internal SpinLock and Mutex 4741 // Based on ParkEvent 4742 4743 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4744 // 4745 // We employ SpinLocks _only for low-contention, fixed-length 4746 // short-duration critical sections where we're concerned 4747 // about native mutex_t or HotSpot Mutex:: latency. 4748 // The mux construct provides a spin-then-block mutual exclusion 4749 // mechanism. 4750 // 4751 // Testing has shown that contention on the ListLock guarding gFreeList 4752 // is common. If we implement ListLock as a simple SpinLock it's common 4753 // for the JVM to devolve to yielding with little progress. This is true 4754 // despite the fact that the critical sections protected by ListLock are 4755 // extremely short. 4756 // 4757 // TODO-FIXME: ListLock should be of type SpinLock. 4758 // We should make this a 1st-class type, integrated into the lock 4759 // hierarchy as leaf-locks. Critically, the SpinLock structure 4760 // should have sufficient padding to avoid false-sharing and excessive 4761 // cache-coherency traffic. 4762 4763 4764 typedef volatile int SpinLockT; 4765 4766 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4767 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4768 return; // normal fast-path return 4769 } 4770 4771 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4772 int ctr = 0; 4773 int Yields = 0; 4774 for (;;) { 4775 while (*adr != 0) { 4776 ++ctr; 4777 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4778 if (Yields > 5) { 4779 os::naked_short_sleep(1); 4780 } else { 4781 os::naked_yield(); 4782 ++Yields; 4783 } 4784 } else { 4785 SpinPause(); 4786 } 4787 } 4788 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4789 } 4790 } 4791 4792 void Thread::SpinRelease(volatile int * adr) { 4793 assert(*adr != 0, "invariant"); 4794 OrderAccess::fence(); // guarantee at least release consistency. 4795 // Roach-motel semantics. 4796 // It's safe if subsequent LDs and STs float "up" into the critical section, 4797 // but prior LDs and STs within the critical section can't be allowed 4798 // to reorder or float past the ST that releases the lock. 4799 // Loads and stores in the critical section - which appear in program 4800 // order before the store that releases the lock - must also appear 4801 // before the store that releases the lock in memory visibility order. 4802 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4803 // the ST of 0 into the lock-word which releases the lock, so fence 4804 // more than covers this on all platforms. 4805 *adr = 0; 4806 } 4807 4808 // muxAcquire and muxRelease: 4809 // 4810 // * muxAcquire and muxRelease support a single-word lock-word construct. 4811 // The LSB of the word is set IFF the lock is held. 4812 // The remainder of the word points to the head of a singly-linked list 4813 // of threads blocked on the lock. 4814 // 4815 // * The current implementation of muxAcquire-muxRelease uses its own 4816 // dedicated Thread._MuxEvent instance. If we're interested in 4817 // minimizing the peak number of extant ParkEvent instances then 4818 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4819 // as certain invariants were satisfied. Specifically, care would need 4820 // to be taken with regards to consuming unpark() "permits". 4821 // A safe rule of thumb is that a thread would never call muxAcquire() 4822 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4823 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4824 // consume an unpark() permit intended for monitorenter, for instance. 4825 // One way around this would be to widen the restricted-range semaphore 4826 // implemented in park(). Another alternative would be to provide 4827 // multiple instances of the PlatformEvent() for each thread. One 4828 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4829 // 4830 // * Usage: 4831 // -- Only as leaf locks 4832 // -- for short-term locking only as muxAcquire does not perform 4833 // thread state transitions. 4834 // 4835 // Alternatives: 4836 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4837 // but with parking or spin-then-park instead of pure spinning. 4838 // * Use Taura-Oyama-Yonenzawa locks. 4839 // * It's possible to construct a 1-0 lock if we encode the lockword as 4840 // (List,LockByte). Acquire will CAS the full lockword while Release 4841 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4842 // acquiring threads use timers (ParkTimed) to detect and recover from 4843 // the stranding window. Thread/Node structures must be aligned on 256-byte 4844 // boundaries by using placement-new. 4845 // * Augment MCS with advisory back-link fields maintained with CAS(). 4846 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4847 // The validity of the backlinks must be ratified before we trust the value. 4848 // If the backlinks are invalid the exiting thread must back-track through the 4849 // the forward links, which are always trustworthy. 4850 // * Add a successor indication. The LockWord is currently encoded as 4851 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4852 // to provide the usual futile-wakeup optimization. 4853 // See RTStt for details. 4854 // 4855 4856 4857 const intptr_t LOCKBIT = 1; 4858 4859 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4860 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4861 if (w == 0) return; 4862 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4863 return; 4864 } 4865 4866 ParkEvent * const Self = Thread::current()->_MuxEvent; 4867 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4868 for (;;) { 4869 int its = (os::is_MP() ? 100 : 0) + 1; 4870 4871 // Optional spin phase: spin-then-park strategy 4872 while (--its >= 0) { 4873 w = *Lock; 4874 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4875 return; 4876 } 4877 } 4878 4879 Self->reset(); 4880 Self->OnList = intptr_t(Lock); 4881 // The following fence() isn't _strictly necessary as the subsequent 4882 // CAS() both serializes execution and ratifies the fetched *Lock value. 4883 OrderAccess::fence(); 4884 for (;;) { 4885 w = *Lock; 4886 if ((w & LOCKBIT) == 0) { 4887 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4888 Self->OnList = 0; // hygiene - allows stronger asserts 4889 return; 4890 } 4891 continue; // Interference -- *Lock changed -- Just retry 4892 } 4893 assert(w & LOCKBIT, "invariant"); 4894 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4895 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4896 } 4897 4898 while (Self->OnList != 0) { 4899 Self->park(); 4900 } 4901 } 4902 } 4903 4904 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4905 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4906 if (w == 0) return; 4907 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4908 return; 4909 } 4910 4911 ParkEvent * ReleaseAfter = NULL; 4912 if (ev == NULL) { 4913 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4914 } 4915 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4916 for (;;) { 4917 guarantee(ev->OnList == 0, "invariant"); 4918 int its = (os::is_MP() ? 100 : 0) + 1; 4919 4920 // Optional spin phase: spin-then-park strategy 4921 while (--its >= 0) { 4922 w = *Lock; 4923 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4924 if (ReleaseAfter != NULL) { 4925 ParkEvent::Release(ReleaseAfter); 4926 } 4927 return; 4928 } 4929 } 4930 4931 ev->reset(); 4932 ev->OnList = intptr_t(Lock); 4933 // The following fence() isn't _strictly necessary as the subsequent 4934 // CAS() both serializes execution and ratifies the fetched *Lock value. 4935 OrderAccess::fence(); 4936 for (;;) { 4937 w = *Lock; 4938 if ((w & LOCKBIT) == 0) { 4939 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4940 ev->OnList = 0; 4941 // We call ::Release while holding the outer lock, thus 4942 // artificially lengthening the critical section. 4943 // Consider deferring the ::Release() until the subsequent unlock(), 4944 // after we've dropped the outer lock. 4945 if (ReleaseAfter != NULL) { 4946 ParkEvent::Release(ReleaseAfter); 4947 } 4948 return; 4949 } 4950 continue; // Interference -- *Lock changed -- Just retry 4951 } 4952 assert(w & LOCKBIT, "invariant"); 4953 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4954 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4955 } 4956 4957 while (ev->OnList != 0) { 4958 ev->park(); 4959 } 4960 } 4961 } 4962 4963 // Release() must extract a successor from the list and then wake that thread. 4964 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4965 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4966 // Release() would : 4967 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4968 // (B) Extract a successor from the private list "in-hand" 4969 // (C) attempt to CAS() the residual back into *Lock over null. 4970 // If there were any newly arrived threads and the CAS() would fail. 4971 // In that case Release() would detach the RATs, re-merge the list in-hand 4972 // with the RATs and repeat as needed. Alternately, Release() might 4973 // detach and extract a successor, but then pass the residual list to the wakee. 4974 // The wakee would be responsible for reattaching and remerging before it 4975 // competed for the lock. 4976 // 4977 // Both "pop" and DMR are immune from ABA corruption -- there can be 4978 // multiple concurrent pushers, but only one popper or detacher. 4979 // This implementation pops from the head of the list. This is unfair, 4980 // but tends to provide excellent throughput as hot threads remain hot. 4981 // (We wake recently run threads first). 4982 // 4983 // All paths through muxRelease() will execute a CAS. 4984 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4985 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4986 // executed within the critical section are complete and globally visible before the 4987 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4988 void Thread::muxRelease(volatile intptr_t * Lock) { 4989 for (;;) { 4990 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4991 assert(w & LOCKBIT, "invariant"); 4992 if (w == LOCKBIT) return; 4993 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4994 assert(List != NULL, "invariant"); 4995 assert(List->OnList == intptr_t(Lock), "invariant"); 4996 ParkEvent * const nxt = List->ListNext; 4997 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4998 4999 // The following CAS() releases the lock and pops the head element. 5000 // The CAS() also ratifies the previously fetched lock-word value. 5001 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 5002 continue; 5003 } 5004 List->OnList = 0; 5005 OrderAccess::fence(); 5006 List->unpark(); 5007 return; 5008 } 5009 } 5010 5011 5012 void Threads::verify() { 5013 ALL_JAVA_THREADS(p) { 5014 p->verify(); 5015 } 5016 VMThread* thread = VMThread::vm_thread(); 5017 if (thread != NULL) thread->verify(); 5018 }