1 /* 2 * Copyright (c) 1997, 2020, 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/iterator.hpp" 51 #include "memory/metaspaceShared.hpp" 52 #include "memory/oopFactory.hpp" 53 #include "memory/resourceArea.hpp" 54 #include "memory/universe.hpp" 55 #include "oops/access.inline.hpp" 56 #include "oops/instanceKlass.hpp" 57 #include "oops/objArrayOop.hpp" 58 #include "oops/oop.inline.hpp" 59 #include "oops/symbol.hpp" 60 #include "oops/typeArrayOop.inline.hpp" 61 #include "oops/verifyOopClosure.hpp" 62 #include "prims/jvm_misc.hpp" 63 #include "prims/jvmtiExport.hpp" 64 #include "prims/jvmtiThreadState.hpp" 65 #include "runtime/arguments.hpp" 66 #include "runtime/atomic.hpp" 67 #include "runtime/biasedLocking.hpp" 68 #include "runtime/fieldDescriptor.inline.hpp" 69 #include "runtime/flags/jvmFlagConstraintList.hpp" 70 #include "runtime/flags/jvmFlagRangeList.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/serviceThread.hpp" 91 #include "runtime/sharedRuntime.hpp" 92 #include "runtime/statSampler.hpp" 93 #include "runtime/stubRoutines.hpp" 94 #include "runtime/sweeper.hpp" 95 #include "runtime/task.hpp" 96 #include "runtime/thread.inline.hpp" 97 #include "runtime/threadCritical.hpp" 98 #include "runtime/threadSMR.inline.hpp" 99 #include "runtime/threadStatisticalInfo.hpp" 100 #include "runtime/timer.hpp" 101 #include "runtime/timerTrace.hpp" 102 #include "runtime/vframe.inline.hpp" 103 #include "runtime/vframeArray.hpp" 104 #include "runtime/vframe_hp.hpp" 105 #include "runtime/vmThread.hpp" 106 #include "runtime/vmOperations.hpp" 107 #include "runtime/vm_version.hpp" 108 #include "services/attachListener.hpp" 109 #include "services/management.hpp" 110 #include "services/memTracker.hpp" 111 #include "services/threadService.hpp" 112 #include "utilities/align.hpp" 113 #include "utilities/copy.hpp" 114 #include "utilities/defaultStream.hpp" 115 #include "utilities/dtrace.hpp" 116 #include "utilities/events.hpp" 117 #include "utilities/macros.hpp" 118 #include "utilities/preserveException.hpp" 119 #include "utilities/singleWriterSynchronizer.hpp" 120 #include "utilities/vmError.hpp" 121 #if INCLUDE_JVMCI 122 #include "jvmci/jvmci.hpp" 123 #include "jvmci/jvmciEnv.hpp" 124 #endif 125 #ifdef COMPILER1 126 #include "c1/c1_Compiler.hpp" 127 #endif 128 #ifdef COMPILER2 129 #include "opto/c2compiler.hpp" 130 #include "opto/idealGraphPrinter.hpp" 131 #endif 132 #if INCLUDE_RTM_OPT 133 #include "runtime/rtmLocking.hpp" 134 #endif 135 #if INCLUDE_JFR 136 #include "jfr/jfr.hpp" 137 #endif 138 139 // Initialization after module runtime initialization 140 void universe_post_module_init(); // must happen after call_initPhase2 141 142 #ifdef DTRACE_ENABLED 143 144 // Only bother with this argument setup if dtrace is available 145 146 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 147 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 148 149 #define DTRACE_THREAD_PROBE(probe, javathread) \ 150 { \ 151 ResourceMark rm(this); \ 152 int len = 0; \ 153 const char* name = (javathread)->get_thread_name(); \ 154 len = strlen(name); \ 155 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 156 (char *) name, len, \ 157 java_lang_Thread::thread_id((javathread)->threadObj()), \ 158 (uintptr_t) (javathread)->osthread()->thread_id(), \ 159 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 160 } 161 162 #else // ndef DTRACE_ENABLED 163 164 #define DTRACE_THREAD_PROBE(probe, javathread) 165 166 #endif // ndef DTRACE_ENABLED 167 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY 169 // Current thread is maintained as a thread-local variable 170 THREAD_LOCAL Thread* Thread::_thr_current = NULL; 171 #endif 172 173 // ======= Thread ======== 174 // Support for forcing alignment of thread objects for biased locking 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 176 if (UseBiasedLocking) { 177 const size_t alignment = markWord::biased_lock_alignment; 178 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 180 : AllocateHeap(aligned_size, flags, CURRENT_PC, 181 AllocFailStrategy::RETURN_NULL); 182 void* aligned_addr = align_up(real_malloc_addr, alignment); 183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 185 "JavaThread alignment code overflowed allocated storage"); 186 if (aligned_addr != real_malloc_addr) { 187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 188 p2i(real_malloc_addr), 189 p2i(aligned_addr)); 190 } 191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 192 return aligned_addr; 193 } else { 194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 196 } 197 } 198 199 void Thread::operator delete(void* p) { 200 if (UseBiasedLocking) { 201 FreeHeap(((Thread*) p)->_real_malloc_address); 202 } else { 203 FreeHeap(p); 204 } 205 } 206 207 void JavaThread::smr_delete() { 208 if (_on_thread_list) { 209 ThreadsSMRSupport::smr_delete(this); 210 } else { 211 delete this; 212 } 213 } 214 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 216 // JavaThread 217 218 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;) 219 220 Thread::Thread() { 221 222 DEBUG_ONLY(_run_state = PRE_CALL_RUN;) 223 224 // stack and get_thread 225 set_stack_base(NULL); 226 set_stack_size(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 240 241 // Initial value of zero ==> never claimed. 242 _threads_do_token = 0; 243 _threads_hazard_ptr = NULL; 244 _threads_list_ptr = NULL; 245 _nested_threads_hazard_ptr_cnt = 0; 246 _rcu_counter = 0; 247 248 // the handle mark links itself to last_handle_mark 249 new HandleMark(this); 250 251 // plain initialization 252 debug_only(_owned_locks = NULL;) 253 NOT_PRODUCT(_no_safepoint_count = 0;) 254 NOT_PRODUCT(_skip_gcalot = false;) 255 _jvmti_env_iteration_count = 0; 256 set_allocated_bytes(0); 257 _vm_operation_started_count = 0; 258 _vm_operation_completed_count = 0; 259 _current_pending_monitor = NULL; 260 _current_pending_monitor_is_from_java = true; 261 _current_waiting_monitor = NULL; 262 _current_pending_raw_monitor = NULL; 263 _num_nested_signal = 0; 264 om_free_list = NULL; 265 om_free_count = 0; 266 om_free_provision = 32; 267 om_in_use_list = NULL; 268 om_in_use_count = 0; 269 270 #ifdef ASSERT 271 _visited_for_critical_count = false; 272 #endif 273 274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 275 Monitor::_safepoint_check_sometimes); 276 _suspend_flags = 0; 277 278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 279 _hashStateX = os::random(); 280 _hashStateY = 842502087; 281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 282 _hashStateW = 273326509; 283 284 _OnTrap = 0; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _MuxEvent = ParkEvent::Allocate(this); 297 298 #ifdef CHECK_UNHANDLED_OOPS 299 if (CheckUnhandledOops) { 300 _unhandled_oops = new UnhandledOops(this); 301 } 302 #endif // CHECK_UNHANDLED_OOPS 303 #ifdef ASSERT 304 if (UseBiasedLocking) { 305 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed"); 306 assert(this == _real_malloc_address || 307 this == align_up(_real_malloc_address, markWord::biased_lock_alignment), 308 "bug in forced alignment of thread objects"); 309 } 310 #endif // ASSERT 311 312 // Notify the barrier set that a thread is being created. The initial 313 // thread is created before the barrier set is available. The call to 314 // BarrierSet::on_thread_create() for this thread is therefore deferred 315 // to BarrierSet::set_barrier_set(). 316 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 317 if (barrier_set != NULL) { 318 barrier_set->on_thread_create(this); 319 } else { 320 // Only the main thread should be created before the barrier set 321 // and that happens just before Thread::current is set. No other thread 322 // can attach as the VM is not created yet, so they can't execute this code. 323 // If the main thread creates other threads before the barrier set that is an error. 324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 325 } 326 } 327 328 void Thread::initialize_thread_current() { 329 #ifndef USE_LIBRARY_BASED_TLS_ONLY 330 assert(_thr_current == NULL, "Thread::current already initialized"); 331 _thr_current = this; 332 #endif 333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 334 ThreadLocalStorage::set_thread(this); 335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 336 } 337 338 void Thread::clear_thread_current() { 339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 340 #ifndef USE_LIBRARY_BASED_TLS_ONLY 341 _thr_current = NULL; 342 #endif 343 ThreadLocalStorage::set_thread(NULL); 344 } 345 346 void Thread::record_stack_base_and_size() { 347 // Note: at this point, Thread object is not yet initialized. Do not rely on 348 // any members being initialized. Do not rely on Thread::current() being set. 349 // If possible, refrain from doing anything which may crash or assert since 350 // quite probably those crash dumps will be useless. 351 set_stack_base(os::current_stack_base()); 352 set_stack_size(os::current_stack_size()); 353 354 #ifdef SOLARIS 355 if (os::is_primordial_thread()) { 356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 357 } 358 #endif 359 360 // Set stack limits after thread is initialized. 361 if (is_Java_thread()) { 362 ((JavaThread*) this)->set_stack_overflow_limit(); 363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 364 } 365 } 366 367 #if INCLUDE_NMT 368 void Thread::register_thread_stack_with_NMT() { 369 MemTracker::record_thread_stack(stack_end(), stack_size()); 370 } 371 #endif // INCLUDE_NMT 372 373 void Thread::call_run() { 374 DEBUG_ONLY(_run_state = CALL_RUN;) 375 376 // At this point, Thread object should be fully initialized and 377 // Thread::current() should be set. 378 379 assert(Thread::current_or_null() != NULL, "current thread is unset"); 380 assert(Thread::current_or_null() == this, "current thread is wrong"); 381 382 // Perform common initialization actions 383 384 register_thread_stack_with_NMT(); 385 386 JFR_ONLY(Jfr::on_thread_start(this);) 387 388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 390 os::current_thread_id(), p2i(stack_end()), 391 p2i(stack_base()), stack_size()/1024); 392 393 // Perform <ChildClass> initialization actions 394 DEBUG_ONLY(_run_state = PRE_RUN;) 395 this->pre_run(); 396 397 // Invoke <ChildClass>::run() 398 DEBUG_ONLY(_run_state = RUN;) 399 this->run(); 400 // Returned from <ChildClass>::run(). Thread finished. 401 402 // Perform common tear-down actions 403 404 assert(Thread::current_or_null() != NULL, "current thread is unset"); 405 assert(Thread::current_or_null() == this, "current thread is wrong"); 406 407 // Perform <ChildClass> tear-down actions 408 DEBUG_ONLY(_run_state = POST_RUN;) 409 this->post_run(); 410 411 // Note: at this point the thread object may already have deleted itself, 412 // so from here on do not dereference *this*. Not all thread types currently 413 // delete themselves when they terminate. But no thread should ever be deleted 414 // asynchronously with respect to its termination - that is what _run_state can 415 // be used to check. 416 417 assert(Thread::current_or_null() == NULL, "current thread still present"); 418 } 419 420 Thread::~Thread() { 421 422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 423 // get started due to errors etc. Any active thread should at least reach post_run 424 // before it is deleted (usually in post_run()). 425 assert(_run_state == PRE_CALL_RUN || 426 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 427 "_run_state=%d", (int)_run_state); 428 429 // Notify the barrier set that a thread is being destroyed. Note that a barrier 430 // set might not be available if we encountered errors during bootstrapping. 431 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 432 if (barrier_set != NULL) { 433 barrier_set->on_thread_destroy(this); 434 } 435 436 // stack_base can be NULL if the thread is never started or exited before 437 // record_stack_base_and_size called. Although, we would like to ensure 438 // that all started threads do call record_stack_base_and_size(), there is 439 // not proper way to enforce that. 440 #if INCLUDE_NMT 441 if (_stack_base != NULL) { 442 MemTracker::release_thread_stack(stack_end(), stack_size()); 443 #ifdef ASSERT 444 set_stack_base(NULL); 445 #endif 446 } 447 #endif // INCLUDE_NMT 448 449 // deallocate data structures 450 delete resource_area(); 451 // since the handle marks are using the handle area, we have to deallocated the root 452 // handle mark before deallocating the thread's handle area, 453 assert(last_handle_mark() != NULL, "check we have an element"); 454 delete last_handle_mark(); 455 assert(last_handle_mark() == NULL, "check we have reached the end"); 456 457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 458 // We NULL out the fields for good hygiene. 459 ParkEvent::Release(_ParkEvent); _ParkEvent = 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 class InstallAsyncExceptionClosure : public HandshakeClosure { 529 Handle _throwable; // The Throwable thrown at the target Thread 530 public: 531 InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {} 532 533 void do_thread(Thread* thr) { 534 JavaThread* target = (JavaThread*)thr; 535 // Note that this now allows multiple ThreadDeath exceptions to be 536 // thrown at a thread. 537 // The target thread has run and has not exited yet. 538 target->send_thread_stop(_throwable()); 539 } 540 }; 541 542 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 543 Handle throwable(Thread::current(), java_throwable); 544 JavaThread* target = java_lang_Thread::thread(java_thread); 545 InstallAsyncExceptionClosure vm_stop(throwable); 546 Handshake::execute(&vm_stop, target); 547 } 548 549 550 // Check if an external suspend request has completed (or has been 551 // cancelled). Returns true if the thread is externally suspended and 552 // false otherwise. 553 // 554 // The bits parameter returns information about the code path through 555 // the routine. Useful for debugging: 556 // 557 // set in is_ext_suspend_completed(): 558 // 0x00000001 - routine was entered 559 // 0x00000010 - routine return false at end 560 // 0x00000100 - thread exited (return false) 561 // 0x00000200 - suspend request cancelled (return false) 562 // 0x00000400 - thread suspended (return true) 563 // 0x00001000 - thread is in a suspend equivalent state (return true) 564 // 0x00002000 - thread is native and walkable (return true) 565 // 0x00004000 - thread is native_trans and walkable (needed retry) 566 // 567 // set in wait_for_ext_suspend_completion(): 568 // 0x00010000 - routine was entered 569 // 0x00020000 - suspend request cancelled before loop (return false) 570 // 0x00040000 - thread suspended before loop (return true) 571 // 0x00080000 - suspend request cancelled in loop (return false) 572 // 0x00100000 - thread suspended in loop (return true) 573 // 0x00200000 - suspend not completed during retry loop (return false) 574 575 // Helper class for tracing suspend wait debug bits. 576 // 577 // 0x00000100 indicates that the target thread exited before it could 578 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 579 // 0x00080000 each indicate a cancelled suspend request so they don't 580 // count as wait failures either. 581 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 582 583 class TraceSuspendDebugBits : public StackObj { 584 private: 585 JavaThread * jt; 586 bool is_wait; 587 bool called_by_wait; // meaningful when !is_wait 588 uint32_t * bits; 589 590 public: 591 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 592 uint32_t *_bits) { 593 jt = _jt; 594 is_wait = _is_wait; 595 called_by_wait = _called_by_wait; 596 bits = _bits; 597 } 598 599 ~TraceSuspendDebugBits() { 600 if (!is_wait) { 601 #if 1 602 // By default, don't trace bits for is_ext_suspend_completed() calls. 603 // That trace is very chatty. 604 return; 605 #else 606 if (!called_by_wait) { 607 // If tracing for is_ext_suspend_completed() is enabled, then only 608 // trace calls to it from wait_for_ext_suspend_completion() 609 return; 610 } 611 #endif 612 } 613 614 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 615 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 616 MutexLocker ml(Threads_lock); // needed for get_thread_name() 617 ResourceMark rm; 618 619 tty->print_cr( 620 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 621 jt->get_thread_name(), *bits); 622 623 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 624 } 625 } 626 } 627 }; 628 #undef DEBUG_FALSE_BITS 629 630 631 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 632 uint32_t *bits) { 633 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 634 635 bool did_trans_retry = false; // only do thread_in_native_trans retry once 636 bool do_trans_retry; // flag to force the retry 637 638 *bits |= 0x00000001; 639 640 do { 641 do_trans_retry = false; 642 643 if (is_exiting()) { 644 // Thread is in the process of exiting. This is always checked 645 // first to reduce the risk of dereferencing a freed JavaThread. 646 *bits |= 0x00000100; 647 return false; 648 } 649 650 if (!is_external_suspend()) { 651 // Suspend request is cancelled. This is always checked before 652 // is_ext_suspended() to reduce the risk of a rogue resume 653 // confusing the thread that made the suspend request. 654 *bits |= 0x00000200; 655 return false; 656 } 657 658 if (is_ext_suspended()) { 659 // thread is suspended 660 *bits |= 0x00000400; 661 return true; 662 } 663 664 // Now that we no longer do hard suspends of threads running 665 // native code, the target thread can be changing thread state 666 // while we are in this routine: 667 // 668 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 669 // 670 // We save a copy of the thread state as observed at this moment 671 // and make our decision about suspend completeness based on the 672 // copy. This closes the race where the thread state is seen as 673 // _thread_in_native_trans in the if-thread_blocked check, but is 674 // seen as _thread_blocked in if-thread_in_native_trans check. 675 JavaThreadState save_state = thread_state(); 676 677 if (save_state == _thread_blocked && is_suspend_equivalent()) { 678 // If the thread's state is _thread_blocked and this blocking 679 // condition is known to be equivalent to a suspend, then we can 680 // consider the thread to be externally suspended. This means that 681 // the code that sets _thread_blocked has been modified to do 682 // self-suspension if the blocking condition releases. We also 683 // used to check for CONDVAR_WAIT here, but that is now covered by 684 // the _thread_blocked with self-suspension check. 685 // 686 // Return true since we wouldn't be here unless there was still an 687 // external suspend request. 688 *bits |= 0x00001000; 689 return true; 690 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 691 // Threads running native code will self-suspend on native==>VM/Java 692 // transitions. If its stack is walkable (should always be the case 693 // unless this function is called before the actual java_suspend() 694 // call), then the wait is done. 695 *bits |= 0x00002000; 696 return true; 697 } else if (!called_by_wait && !did_trans_retry && 698 save_state == _thread_in_native_trans && 699 frame_anchor()->walkable()) { 700 // The thread is transitioning from thread_in_native to another 701 // thread state. check_safepoint_and_suspend_for_native_trans() 702 // will force the thread to self-suspend. If it hasn't gotten 703 // there yet we may have caught the thread in-between the native 704 // code check above and the self-suspend. Lucky us. If we were 705 // called by wait_for_ext_suspend_completion(), then it 706 // will be doing the retries so we don't have to. 707 // 708 // Since we use the saved thread state in the if-statement above, 709 // there is a chance that the thread has already transitioned to 710 // _thread_blocked by the time we get here. In that case, we will 711 // make a single unnecessary pass through the logic below. This 712 // doesn't hurt anything since we still do the trans retry. 713 714 *bits |= 0x00004000; 715 716 // Once the thread leaves thread_in_native_trans for another 717 // thread state, we break out of this retry loop. We shouldn't 718 // need this flag to prevent us from getting back here, but 719 // sometimes paranoia is good. 720 did_trans_retry = true; 721 722 // We wait for the thread to transition to a more usable state. 723 for (int i = 1; i <= SuspendRetryCount; i++) { 724 // We used to do an "os::yield_all(i)" call here with the intention 725 // that yielding would increase on each retry. However, the parameter 726 // is ignored on Linux which means the yield didn't scale up. Waiting 727 // on the SR_lock below provides a much more predictable scale up for 728 // the delay. It also provides a simple/direct point to check for any 729 // safepoint requests from the VMThread 730 731 // temporarily drops SR_lock while doing wait with safepoint check 732 // (if we're a JavaThread - the WatcherThread can also call this) 733 // and increase delay with each retry 734 if (Thread::current()->is_Java_thread()) { 735 SR_lock()->wait(i * delay); 736 } else { 737 SR_lock()->wait_without_safepoint_check(i * delay); 738 } 739 740 // check the actual thread state instead of what we saved above 741 if (thread_state() != _thread_in_native_trans) { 742 // the thread has transitioned to another thread state so 743 // try all the checks (except this one) one more time. 744 do_trans_retry = true; 745 break; 746 } 747 } // end retry loop 748 749 750 } 751 } while (do_trans_retry); 752 753 *bits |= 0x00000010; 754 return false; 755 } 756 757 // Wait for an external suspend request to complete (or be cancelled). 758 // Returns true if the thread is externally suspended and false otherwise. 759 // 760 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 761 uint32_t *bits) { 762 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 763 false /* !called_by_wait */, bits); 764 765 // local flag copies to minimize SR_lock hold time 766 bool is_suspended; 767 bool pending; 768 uint32_t reset_bits; 769 770 // set a marker so is_ext_suspend_completed() knows we are the caller 771 *bits |= 0x00010000; 772 773 // We use reset_bits to reinitialize the bits value at the top of 774 // each retry loop. This allows the caller to make use of any 775 // unused bits for their own marking purposes. 776 reset_bits = *bits; 777 778 { 779 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 780 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 781 delay, bits); 782 pending = is_external_suspend(); 783 } 784 // must release SR_lock to allow suspension to complete 785 786 if (!pending) { 787 // A cancelled suspend request is the only false return from 788 // is_ext_suspend_completed() that keeps us from entering the 789 // retry loop. 790 *bits |= 0x00020000; 791 return false; 792 } 793 794 if (is_suspended) { 795 *bits |= 0x00040000; 796 return true; 797 } 798 799 for (int i = 1; i <= retries; i++) { 800 *bits = reset_bits; // reinit to only track last retry 801 802 // We used to do an "os::yield_all(i)" call here with the intention 803 // that yielding would increase on each retry. However, the parameter 804 // is ignored on Linux which means the yield didn't scale up. Waiting 805 // on the SR_lock below provides a much more predictable scale up for 806 // the delay. It also provides a simple/direct point to check for any 807 // safepoint requests from the VMThread 808 809 { 810 Thread* t = Thread::current(); 811 MonitorLocker ml(SR_lock(), 812 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 813 // wait with safepoint check (if we're a JavaThread - the WatcherThread 814 // can also call this) and increase delay with each retry 815 ml.wait(i * delay); 816 817 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 818 delay, bits); 819 820 // It is possible for the external suspend request to be cancelled 821 // (by a resume) before the actual suspend operation is completed. 822 // Refresh our local copy to see if we still need to wait. 823 pending = is_external_suspend(); 824 } 825 826 if (!pending) { 827 // A cancelled suspend request is the only false return from 828 // is_ext_suspend_completed() that keeps us from staying in the 829 // retry loop. 830 *bits |= 0x00080000; 831 return false; 832 } 833 834 if (is_suspended) { 835 *bits |= 0x00100000; 836 return true; 837 } 838 } // end retry loop 839 840 // thread did not suspend after all our retries 841 *bits |= 0x00200000; 842 return false; 843 } 844 845 // Called from API entry points which perform stack walking. If the 846 // associated JavaThread is the current thread, then wait_for_suspend 847 // is not used. Otherwise, it determines if we should wait for the 848 // "other" thread to complete external suspension. (NOTE: in future 849 // releases the suspension mechanism should be reimplemented so this 850 // is not necessary.) 851 // 852 bool 853 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 854 if (this != JavaThread::current()) { 855 // "other" threads require special handling. 856 if (wait_for_suspend) { 857 // We are allowed to wait for the external suspend to complete 858 // so give the other thread a chance to get suspended. 859 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 860 SuspendRetryDelay, bits)) { 861 // Didn't make it so let the caller know. 862 return false; 863 } 864 } 865 // We aren't allowed to wait for the external suspend to complete 866 // so if the other thread isn't externally suspended we need to 867 // let the caller know. 868 else if (!is_ext_suspend_completed_with_lock(bits)) { 869 return false; 870 } 871 } 872 873 return true; 874 } 875 876 // GC Support 877 bool Thread::claim_par_threads_do(uintx claim_token) { 878 uintx token = _threads_do_token; 879 if (token != claim_token) { 880 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token); 881 if (res == token) { 882 return true; 883 } 884 guarantee(res == claim_token, "invariant"); 885 } 886 return false; 887 } 888 889 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 890 if (active_handles() != NULL) { 891 active_handles()->oops_do(f); 892 } 893 // Do oop for ThreadShadow 894 f->do_oop((oop*)&_pending_exception); 895 handle_area()->oops_do(f); 896 897 // We scan thread local monitor lists here, and the remaining global 898 // monitors in ObjectSynchronizer::oops_do(). 899 ObjectSynchronizer::thread_local_used_oops_do(this, f); 900 } 901 902 void Thread::metadata_handles_do(void f(Metadata*)) { 903 // Only walk the Handles in Thread. 904 if (metadata_handles() != NULL) { 905 for (int i = 0; i< metadata_handles()->length(); i++) { 906 f(metadata_handles()->at(i)); 907 } 908 } 909 } 910 911 void Thread::print_on(outputStream* st, bool print_extended_info) const { 912 // get_priority assumes osthread initialized 913 if (osthread() != NULL) { 914 int os_prio; 915 if (os::get_native_priority(this, &os_prio) == OS_OK) { 916 st->print("os_prio=%d ", os_prio); 917 } 918 919 st->print("cpu=%.2fms ", 920 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 921 ); 922 st->print("elapsed=%.2fs ", 923 _statistical_info.getElapsedTime() / 1000.0 924 ); 925 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 926 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 927 st->print("allocated=" SIZE_FORMAT "%s ", 928 byte_size_in_proper_unit(allocated_bytes), 929 proper_unit_for_byte_size(allocated_bytes) 930 ); 931 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 932 } 933 934 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 935 osthread()->print_on(st); 936 } 937 ThreadsSMRSupport::print_info_on(this, st); 938 st->print(" "); 939 debug_only(if (WizardMode) print_owned_locks_on(st);) 940 } 941 942 void Thread::print() const { print_on(tty); } 943 944 // Thread::print_on_error() is called by fatal error handler. Don't use 945 // any lock or allocate memory. 946 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 947 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 948 949 if (is_VM_thread()) { st->print("VMThread"); } 950 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 951 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 952 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 953 else { st->print("Thread"); } 954 955 if (is_Named_thread()) { 956 st->print(" \"%s\"", name()); 957 } 958 959 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 960 p2i(stack_end()), p2i(stack_base())); 961 962 if (osthread()) { 963 st->print(" [id=%d]", osthread()->thread_id()); 964 } 965 966 ThreadsSMRSupport::print_info_on(this, st); 967 } 968 969 void Thread::print_value_on(outputStream* st) const { 970 if (is_Named_thread()) { 971 st->print(" \"%s\" ", name()); 972 } 973 st->print(INTPTR_FORMAT, p2i(this)); // print address 974 } 975 976 #ifdef ASSERT 977 void Thread::print_owned_locks_on(outputStream* st) const { 978 Mutex* cur = _owned_locks; 979 if (cur == NULL) { 980 st->print(" (no locks) "); 981 } else { 982 st->print_cr(" Locks owned:"); 983 while (cur) { 984 cur->print_on(st); 985 cur = cur->next(); 986 } 987 } 988 } 989 990 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 991 void Thread::check_possible_safepoint() { 992 if (!is_Java_thread()) return; 993 994 if (_no_safepoint_count > 0) { 995 print_owned_locks(); 996 fatal("Possible safepoint reached by thread that does not allow it"); 997 } 998 #ifdef CHECK_UNHANDLED_OOPS 999 // Clear unhandled oops in JavaThreads so we get a crash right away. 1000 clear_unhandled_oops(); 1001 #endif // CHECK_UNHANDLED_OOPS 1002 } 1003 1004 void Thread::check_for_valid_safepoint_state() { 1005 if (!is_Java_thread()) return; 1006 1007 // Check NoSafepointVerifier, which is implied by locks taken that can be 1008 // shared with the VM thread. This makes sure that no locks with allow_vm_block 1009 // are held. 1010 check_possible_safepoint(); 1011 1012 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 1013 fatal("LEAF method calling lock?"); 1014 } 1015 1016 if (GCALotAtAllSafepoints) { 1017 // We could enter a safepoint here and thus have a gc 1018 InterfaceSupport::check_gc_alot(); 1019 } 1020 } 1021 #endif // ASSERT 1022 1023 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1024 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1025 // used for compilation in the future. If that change is made, the need for these methods 1026 // should be revisited, and they should be removed if possible. 1027 1028 bool Thread::is_lock_owned(address adr) const { 1029 return is_in_full_stack(adr); 1030 } 1031 1032 bool Thread::set_as_starting_thread() { 1033 assert(_starting_thread == NULL, "already initialized: " 1034 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1035 // NOTE: this must be called inside the main thread. 1036 DEBUG_ONLY(_starting_thread = this;) 1037 return os::create_main_thread((JavaThread*)this); 1038 } 1039 1040 static void initialize_class(Symbol* class_name, TRAPS) { 1041 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1042 InstanceKlass::cast(klass)->initialize(CHECK); 1043 } 1044 1045 1046 // Creates the initial ThreadGroup 1047 static Handle create_initial_thread_group(TRAPS) { 1048 Handle system_instance = JavaCalls::construct_new_instance( 1049 SystemDictionary::ThreadGroup_klass(), 1050 vmSymbols::void_method_signature(), 1051 CHECK_NH); 1052 Universe::set_system_thread_group(system_instance()); 1053 1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1055 Handle main_instance = JavaCalls::construct_new_instance( 1056 SystemDictionary::ThreadGroup_klass(), 1057 vmSymbols::threadgroup_string_void_signature(), 1058 system_instance, 1059 string, 1060 CHECK_NH); 1061 return main_instance; 1062 } 1063 1064 // Creates the initial Thread 1065 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1066 TRAPS) { 1067 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1068 assert(ik->is_initialized(), "must be"); 1069 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1070 1071 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1072 // constructor calls Thread.current(), which must be set here for the 1073 // initial thread. 1074 java_lang_Thread::set_thread(thread_oop(), thread); 1075 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1076 thread->set_threadObj(thread_oop()); 1077 1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1079 1080 JavaValue result(T_VOID); 1081 JavaCalls::call_special(&result, thread_oop, 1082 ik, 1083 vmSymbols::object_initializer_name(), 1084 vmSymbols::threadgroup_string_void_signature(), 1085 thread_group, 1086 string, 1087 CHECK_NULL); 1088 return thread_oop(); 1089 } 1090 1091 char java_runtime_name[128] = ""; 1092 char java_runtime_version[128] = ""; 1093 char java_runtime_vendor_version[128] = ""; 1094 char java_runtime_vendor_vm_bug_url[128] = ""; 1095 1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1097 static const char* get_java_runtime_name(TRAPS) { 1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1100 fieldDescriptor fd; 1101 bool found = k != NULL && 1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1103 vmSymbols::string_signature(), &fd); 1104 if (found) { 1105 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1106 if (name_oop == NULL) { 1107 return NULL; 1108 } 1109 const char* name = java_lang_String::as_utf8_string(name_oop, 1110 java_runtime_name, 1111 sizeof(java_runtime_name)); 1112 return name; 1113 } else { 1114 return NULL; 1115 } 1116 } 1117 1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1119 static const char* get_java_runtime_version(TRAPS) { 1120 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1121 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1122 fieldDescriptor fd; 1123 bool found = k != NULL && 1124 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1125 vmSymbols::string_signature(), &fd); 1126 if (found) { 1127 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1128 if (name_oop == NULL) { 1129 return NULL; 1130 } 1131 const char* name = java_lang_String::as_utf8_string(name_oop, 1132 java_runtime_version, 1133 sizeof(java_runtime_version)); 1134 return name; 1135 } else { 1136 return NULL; 1137 } 1138 } 1139 1140 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION 1141 static const char* get_java_runtime_vendor_version(TRAPS) { 1142 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1143 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1144 fieldDescriptor fd; 1145 bool found = k != NULL && 1146 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(), 1147 vmSymbols::string_signature(), &fd); 1148 if (found) { 1149 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1150 if (name_oop == NULL) { 1151 return NULL; 1152 } 1153 const char* name = java_lang_String::as_utf8_string(name_oop, 1154 java_runtime_vendor_version, 1155 sizeof(java_runtime_vendor_version)); 1156 return name; 1157 } else { 1158 return NULL; 1159 } 1160 } 1161 1162 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG 1163 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) { 1164 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1165 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1166 fieldDescriptor fd; 1167 bool found = k != NULL && 1168 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(), 1169 vmSymbols::string_signature(), &fd); 1170 if (found) { 1171 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1172 if (name_oop == NULL) { 1173 return NULL; 1174 } 1175 const char* name = java_lang_String::as_utf8_string(name_oop, 1176 java_runtime_vendor_vm_bug_url, 1177 sizeof(java_runtime_vendor_vm_bug_url)); 1178 return name; 1179 } else { 1180 return NULL; 1181 } 1182 } 1183 1184 // General purpose hook into Java code, run once when the VM is initialized. 1185 // The Java library method itself may be changed independently from the VM. 1186 static void call_postVMInitHook(TRAPS) { 1187 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1188 if (klass != NULL) { 1189 JavaValue result(T_VOID); 1190 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1191 vmSymbols::void_method_signature(), 1192 CHECK); 1193 } 1194 } 1195 1196 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1197 bool daemon, TRAPS) { 1198 assert(thread_group.not_null(), "thread group should be specified"); 1199 assert(threadObj() == NULL, "should only create Java thread object once"); 1200 1201 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1202 assert(ik->is_initialized(), "must be"); 1203 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1204 1205 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1206 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1207 // constructor calls Thread.current(), which must be set here. 1208 java_lang_Thread::set_thread(thread_oop(), this); 1209 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1210 set_threadObj(thread_oop()); 1211 1212 JavaValue result(T_VOID); 1213 if (thread_name != NULL) { 1214 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1215 // Thread gets assigned specified name and null target 1216 JavaCalls::call_special(&result, 1217 thread_oop, 1218 ik, 1219 vmSymbols::object_initializer_name(), 1220 vmSymbols::threadgroup_string_void_signature(), 1221 thread_group, 1222 name, 1223 THREAD); 1224 } else { 1225 // Thread gets assigned name "Thread-nnn" and null target 1226 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1227 JavaCalls::call_special(&result, 1228 thread_oop, 1229 ik, 1230 vmSymbols::object_initializer_name(), 1231 vmSymbols::threadgroup_runnable_void_signature(), 1232 thread_group, 1233 Handle(), 1234 THREAD); 1235 } 1236 1237 1238 if (daemon) { 1239 java_lang_Thread::set_daemon(thread_oop()); 1240 } 1241 1242 if (HAS_PENDING_EXCEPTION) { 1243 return; 1244 } 1245 1246 Klass* group = SystemDictionary::ThreadGroup_klass(); 1247 Handle threadObj(THREAD, this->threadObj()); 1248 1249 JavaCalls::call_special(&result, 1250 thread_group, 1251 group, 1252 vmSymbols::add_method_name(), 1253 vmSymbols::thread_void_signature(), 1254 threadObj, // Arg 1 1255 THREAD); 1256 } 1257 1258 // List of all NonJavaThreads and safe iteration over that list. 1259 1260 class NonJavaThread::List { 1261 public: 1262 NonJavaThread* volatile _head; 1263 SingleWriterSynchronizer _protect; 1264 1265 List() : _head(NULL), _protect() {} 1266 }; 1267 1268 NonJavaThread::List NonJavaThread::_the_list; 1269 1270 NonJavaThread::Iterator::Iterator() : 1271 _protect_enter(_the_list._protect.enter()), 1272 _current(Atomic::load_acquire(&_the_list._head)) 1273 {} 1274 1275 NonJavaThread::Iterator::~Iterator() { 1276 _the_list._protect.exit(_protect_enter); 1277 } 1278 1279 void NonJavaThread::Iterator::step() { 1280 assert(!end(), "precondition"); 1281 _current = Atomic::load_acquire(&_current->_next); 1282 } 1283 1284 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1285 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1286 } 1287 1288 NonJavaThread::~NonJavaThread() { } 1289 1290 void NonJavaThread::add_to_the_list() { 1291 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1292 // Initialize BarrierSet-related data before adding to list. 1293 BarrierSet::barrier_set()->on_thread_attach(this); 1294 Atomic::release_store(&_next, _the_list._head); 1295 Atomic::release_store(&_the_list._head, this); 1296 } 1297 1298 void NonJavaThread::remove_from_the_list() { 1299 { 1300 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1301 // Cleanup BarrierSet-related data before removing from list. 1302 BarrierSet::barrier_set()->on_thread_detach(this); 1303 NonJavaThread* volatile* p = &_the_list._head; 1304 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1305 if (t == this) { 1306 *p = _next; 1307 break; 1308 } 1309 } 1310 } 1311 // Wait for any in-progress iterators. Concurrent synchronize is not 1312 // allowed, so do it while holding a dedicated lock. Outside and distinct 1313 // from NJTList_lock in case an iteration attempts to lock it. 1314 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1315 _the_list._protect.synchronize(); 1316 _next = NULL; // Safe to drop the link now. 1317 } 1318 1319 void NonJavaThread::pre_run() { 1320 add_to_the_list(); 1321 1322 // This is slightly odd in that NamedThread is a subclass, but 1323 // in fact name() is defined in Thread 1324 assert(this->name() != NULL, "thread name was not set before it was started"); 1325 this->set_native_thread_name(this->name()); 1326 } 1327 1328 void NonJavaThread::post_run() { 1329 JFR_ONLY(Jfr::on_thread_exit(this);) 1330 remove_from_the_list(); 1331 // Ensure thread-local-storage is cleared before termination. 1332 Thread::clear_thread_current(); 1333 } 1334 1335 // NamedThread -- non-JavaThread subclasses with multiple 1336 // uniquely named instances should derive from this. 1337 NamedThread::NamedThread() : 1338 NonJavaThread(), 1339 _name(NULL), 1340 _processed_thread(NULL), 1341 _gc_id(GCId::undefined()) 1342 {} 1343 1344 NamedThread::~NamedThread() { 1345 FREE_C_HEAP_ARRAY(char, _name); 1346 } 1347 1348 void NamedThread::set_name(const char* format, ...) { 1349 guarantee(_name == NULL, "Only get to set name once."); 1350 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1351 va_list ap; 1352 va_start(ap, format); 1353 jio_vsnprintf(_name, max_name_len, format, ap); 1354 va_end(ap); 1355 } 1356 1357 void NamedThread::print_on(outputStream* st) const { 1358 st->print("\"%s\" ", name()); 1359 Thread::print_on(st); 1360 st->cr(); 1361 } 1362 1363 1364 // ======= WatcherThread ======== 1365 1366 // The watcher thread exists to simulate timer interrupts. It should 1367 // be replaced by an abstraction over whatever native support for 1368 // timer interrupts exists on the platform. 1369 1370 WatcherThread* WatcherThread::_watcher_thread = NULL; 1371 bool WatcherThread::_startable = false; 1372 volatile bool WatcherThread::_should_terminate = false; 1373 1374 WatcherThread::WatcherThread() : NonJavaThread() { 1375 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1376 if (os::create_thread(this, os::watcher_thread)) { 1377 _watcher_thread = this; 1378 1379 // Set the watcher thread to the highest OS priority which should not be 1380 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1381 // is created. The only normal thread using this priority is the reference 1382 // handler thread, which runs for very short intervals only. 1383 // If the VMThread's priority is not lower than the WatcherThread profiling 1384 // will be inaccurate. 1385 os::set_priority(this, MaxPriority); 1386 if (!DisableStartThread) { 1387 os::start_thread(this); 1388 } 1389 } 1390 } 1391 1392 int WatcherThread::sleep() const { 1393 // The WatcherThread does not participate in the safepoint protocol 1394 // for the PeriodicTask_lock because it is not a JavaThread. 1395 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1396 1397 if (_should_terminate) { 1398 // check for termination before we do any housekeeping or wait 1399 return 0; // we did not sleep. 1400 } 1401 1402 // remaining will be zero if there are no tasks, 1403 // causing the WatcherThread to sleep until a task is 1404 // enrolled 1405 int remaining = PeriodicTask::time_to_wait(); 1406 int time_slept = 0; 1407 1408 // we expect this to timeout - we only ever get unparked when 1409 // we should terminate or when a new task has been enrolled 1410 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1411 1412 jlong time_before_loop = os::javaTimeNanos(); 1413 1414 while (true) { 1415 bool timedout = ml.wait(remaining); 1416 jlong now = os::javaTimeNanos(); 1417 1418 if (remaining == 0) { 1419 // if we didn't have any tasks we could have waited for a long time 1420 // consider the time_slept zero and reset time_before_loop 1421 time_slept = 0; 1422 time_before_loop = now; 1423 } else { 1424 // need to recalculate since we might have new tasks in _tasks 1425 time_slept = (int) ((now - time_before_loop) / 1000000); 1426 } 1427 1428 // Change to task list or spurious wakeup of some kind 1429 if (timedout || _should_terminate) { 1430 break; 1431 } 1432 1433 remaining = PeriodicTask::time_to_wait(); 1434 if (remaining == 0) { 1435 // Last task was just disenrolled so loop around and wait until 1436 // another task gets enrolled 1437 continue; 1438 } 1439 1440 remaining -= time_slept; 1441 if (remaining <= 0) { 1442 break; 1443 } 1444 } 1445 1446 return time_slept; 1447 } 1448 1449 void WatcherThread::run() { 1450 assert(this == watcher_thread(), "just checking"); 1451 1452 this->set_active_handles(JNIHandleBlock::allocate_block()); 1453 while (true) { 1454 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1455 assert(watcher_thread() == this, "thread consistency check"); 1456 1457 // Calculate how long it'll be until the next PeriodicTask work 1458 // should be done, and sleep that amount of time. 1459 int time_waited = sleep(); 1460 1461 if (VMError::is_error_reported()) { 1462 // A fatal error has happened, the error handler(VMError::report_and_die) 1463 // should abort JVM after creating an error log file. However in some 1464 // rare cases, the error handler itself might deadlock. Here periodically 1465 // check for error reporting timeouts, and if it happens, just proceed to 1466 // abort the VM. 1467 1468 // This code is in WatcherThread because WatcherThread wakes up 1469 // periodically so the fatal error handler doesn't need to do anything; 1470 // also because the WatcherThread is less likely to crash than other 1471 // threads. 1472 1473 for (;;) { 1474 // Note: we use naked sleep in this loop because we want to avoid using 1475 // any kind of VM infrastructure which may be broken at this point. 1476 if (VMError::check_timeout()) { 1477 // We hit error reporting timeout. Error reporting was interrupted and 1478 // will be wrapping things up now (closing files etc). Give it some more 1479 // time, then quit the VM. 1480 os::naked_short_sleep(200); 1481 // Print a message to stderr. 1482 fdStream err(defaultStream::output_fd()); 1483 err.print_raw_cr("# [ timer expired, abort... ]"); 1484 // skip atexit/vm_exit/vm_abort hooks 1485 os::die(); 1486 } 1487 1488 // Wait a second, then recheck for timeout. 1489 os::naked_short_sleep(999); 1490 } 1491 } 1492 1493 if (_should_terminate) { 1494 // check for termination before posting the next tick 1495 break; 1496 } 1497 1498 PeriodicTask::real_time_tick(time_waited); 1499 } 1500 1501 // Signal that it is terminated 1502 { 1503 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1504 _watcher_thread = NULL; 1505 Terminator_lock->notify_all(); 1506 } 1507 } 1508 1509 void WatcherThread::start() { 1510 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1511 1512 if (watcher_thread() == NULL && _startable) { 1513 _should_terminate = false; 1514 // Create the single instance of WatcherThread 1515 new WatcherThread(); 1516 } 1517 } 1518 1519 void WatcherThread::make_startable() { 1520 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1521 _startable = true; 1522 } 1523 1524 void WatcherThread::stop() { 1525 { 1526 // Follow normal safepoint aware lock enter protocol since the 1527 // WatcherThread is stopped by another JavaThread. 1528 MutexLocker ml(PeriodicTask_lock); 1529 _should_terminate = true; 1530 1531 WatcherThread* watcher = watcher_thread(); 1532 if (watcher != NULL) { 1533 // unpark the WatcherThread so it can see that it should terminate 1534 watcher->unpark(); 1535 } 1536 } 1537 1538 MonitorLocker mu(Terminator_lock); 1539 1540 while (watcher_thread() != NULL) { 1541 // This wait should make safepoint checks, wait without a timeout, 1542 // and wait as a suspend-equivalent condition. 1543 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1544 } 1545 } 1546 1547 void WatcherThread::unpark() { 1548 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1549 PeriodicTask_lock->notify(); 1550 } 1551 1552 void WatcherThread::print_on(outputStream* st) const { 1553 st->print("\"%s\" ", name()); 1554 Thread::print_on(st); 1555 st->cr(); 1556 } 1557 1558 // ======= JavaThread ======== 1559 1560 #if INCLUDE_JVMCI 1561 1562 jlong* JavaThread::_jvmci_old_thread_counters; 1563 1564 bool jvmci_counters_include(JavaThread* thread) { 1565 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1566 } 1567 1568 void JavaThread::collect_counters(jlong* array, int length) { 1569 assert(length == JVMCICounterSize, "wrong value"); 1570 for (int i = 0; i < length; i++) { 1571 array[i] = _jvmci_old_thread_counters[i]; 1572 } 1573 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1574 if (jvmci_counters_include(tp)) { 1575 for (int i = 0; i < length; i++) { 1576 array[i] += tp->_jvmci_counters[i]; 1577 } 1578 } 1579 } 1580 } 1581 1582 // Attempt to enlarge the array for per thread counters. 1583 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1584 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1585 if (old_counters == NULL) { 1586 old_counters = new_counters; 1587 memset(old_counters, 0, sizeof(jlong) * new_size); 1588 } else { 1589 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1590 new_counters[i] = old_counters[i]; 1591 } 1592 if (new_size > current_size) { 1593 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1594 } 1595 FREE_C_HEAP_ARRAY(jlong, old_counters); 1596 } 1597 return new_counters; 1598 } 1599 1600 // Attempt to enlarge the array for per thread counters. 1601 void JavaThread::resize_counters(int current_size, int new_size) { 1602 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1603 } 1604 1605 class VM_JVMCIResizeCounters : public VM_Operation { 1606 private: 1607 int _new_size; 1608 1609 public: 1610 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { } 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 JavaThread::_jvmci_old_thread_counters = new_counters; 1617 1618 // Now resize each threads array 1619 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1620 tp->resize_counters(JVMCICounterSize, _new_size); 1621 } 1622 JVMCICounterSize = _new_size; 1623 } 1624 }; 1625 1626 void JavaThread::resize_all_jvmci_counters(int new_size) { 1627 VM_JVMCIResizeCounters op(new_size); 1628 VMThread::execute(&op); 1629 } 1630 1631 #endif // INCLUDE_JVMCI 1632 1633 // A JavaThread is a normal Java thread 1634 1635 void JavaThread::initialize() { 1636 // Initialize fields 1637 1638 set_saved_exception_pc(NULL); 1639 set_threadObj(NULL); 1640 _anchor.clear(); 1641 set_entry_point(NULL); 1642 set_jni_functions(jni_functions()); 1643 set_callee_target(NULL); 1644 set_vm_result(NULL); 1645 set_vm_result_2(NULL); 1646 set_vframe_array_head(NULL); 1647 set_vframe_array_last(NULL); 1648 set_deferred_locals(NULL); 1649 set_deopt_mark(NULL); 1650 set_deopt_compiled_method(NULL); 1651 set_monitor_chunks(NULL); 1652 _on_thread_list = false; 1653 _thread_state = _thread_new; 1654 _terminated = _not_terminated; 1655 _array_for_gc = NULL; 1656 _suspend_equivalent = false; 1657 _in_deopt_handler = 0; 1658 _doing_unsafe_access = false; 1659 _stack_guard_state = stack_guard_unused; 1660 #if INCLUDE_JVMCI 1661 _pending_monitorenter = false; 1662 _pending_deoptimization = -1; 1663 _pending_failed_speculation = 0; 1664 _pending_transfer_to_interpreter = false; 1665 _in_retryable_allocation = false; 1666 _jvmci._alternate_call_target = NULL; 1667 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1668 _jvmci_counters = NULL; 1669 if (JVMCICounterSize > 0) { 1670 resize_counters(0, (int) JVMCICounterSize); 1671 } 1672 #endif // INCLUDE_JVMCI 1673 _reserved_stack_activation = NULL; // stack base not known yet 1674 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1675 _exception_pc = 0; 1676 _exception_handler_pc = 0; 1677 _is_method_handle_return = 0; 1678 _jvmti_thread_state= NULL; 1679 _should_post_on_exceptions_flag = JNI_FALSE; 1680 _interp_only_mode = 0; 1681 _special_runtime_exit_condition = _no_async_condition; 1682 _pending_async_exception = NULL; 1683 _thread_stat = NULL; 1684 _thread_stat = new ThreadStatistics(); 1685 _jni_active_critical = 0; 1686 _pending_jni_exception_check_fn = NULL; 1687 _do_not_unlock_if_synchronized = false; 1688 _cached_monitor_info = NULL; 1689 _parker = Parker::Allocate(this); 1690 _SleepEvent = ParkEvent::Allocate(this); 1691 // Setup safepoint state info for this thread 1692 ThreadSafepointState::create(this); 1693 _handshake.set_handshakee(this); 1694 1695 debug_only(_java_call_counter = 0); 1696 1697 // JVMTI PopFrame support 1698 _popframe_condition = popframe_inactive; 1699 _popframe_preserved_args = NULL; 1700 _popframe_preserved_args_size = 0; 1701 _frames_to_pop_failed_realloc = 0; 1702 1703 SafepointMechanism::initialize_header(this); 1704 1705 _class_to_be_initialized = NULL; 1706 1707 pd_initialize(); 1708 } 1709 1710 JavaThread::JavaThread(bool is_attaching_via_jni) : 1711 Thread() { 1712 initialize(); 1713 if (is_attaching_via_jni) { 1714 _jni_attach_state = _attaching_via_jni; 1715 } else { 1716 _jni_attach_state = _not_attaching_via_jni; 1717 } 1718 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1719 } 1720 1721 1722 // interrupt support 1723 1724 void JavaThread::interrupt() { 1725 debug_only(check_for_dangling_thread_pointer(this);) 1726 1727 // For Windows _interrupt_event 1728 osthread()->set_interrupted(true); 1729 1730 // For Thread.sleep 1731 _SleepEvent->unpark(); 1732 1733 // For JSR166 LockSupport.park 1734 parker()->unpark(); 1735 1736 // For ObjectMonitor and JvmtiRawMonitor 1737 _ParkEvent->unpark(); 1738 } 1739 1740 1741 bool JavaThread::is_interrupted(bool clear_interrupted) { 1742 debug_only(check_for_dangling_thread_pointer(this);) 1743 1744 if (threadObj() == NULL) { 1745 // If there is no j.l.Thread then it is impossible to have 1746 // been interrupted. We can find NULL during VM initialization 1747 // or when a JNI thread is still in the process of attaching. 1748 // In such cases this must be the current thread. 1749 assert(this == Thread::current(), "invariant"); 1750 return false; 1751 } 1752 1753 bool interrupted = java_lang_Thread::interrupted(threadObj()); 1754 1755 // NOTE that since there is no "lock" around the interrupt and 1756 // is_interrupted operations, there is the possibility that the 1757 // interrupted flag will be "false" but that the 1758 // low-level events will be in the signaled state. This is 1759 // intentional. The effect of this is that Object.wait() and 1760 // LockSupport.park() will appear to have a spurious wakeup, which 1761 // is allowed and not harmful, and the possibility is so rare that 1762 // it is not worth the added complexity to add yet another lock. 1763 // For the sleep event an explicit reset is performed on entry 1764 // to JavaThread::sleep, so there is no early return. It has also been 1765 // recommended not to put the interrupted flag into the "event" 1766 // structure because it hides the issue. 1767 // Also, because there is no lock, we must only clear the interrupt 1768 // state if we are going to report that we were interrupted; otherwise 1769 // an interrupt that happens just after we read the field would be lost. 1770 if (interrupted && clear_interrupted) { 1771 assert(this == Thread::current(), "only the current thread can clear"); 1772 java_lang_Thread::set_interrupted(threadObj(), false); 1773 osthread()->set_interrupted(false); 1774 } 1775 1776 return interrupted; 1777 } 1778 1779 bool JavaThread::reguard_stack(address cur_sp) { 1780 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1781 && _stack_guard_state != stack_guard_reserved_disabled) { 1782 return true; // Stack already guarded or guard pages not needed. 1783 } 1784 1785 if (register_stack_overflow()) { 1786 // For those architectures which have separate register and 1787 // memory stacks, we must check the register stack to see if 1788 // it has overflowed. 1789 return false; 1790 } 1791 1792 // Java code never executes within the yellow zone: the latter is only 1793 // there to provoke an exception during stack banging. If java code 1794 // is executing there, either StackShadowPages should be larger, or 1795 // some exception code in c1, c2 or the interpreter isn't unwinding 1796 // when it should. 1797 guarantee(cur_sp > stack_reserved_zone_base(), 1798 "not enough space to reguard - increase StackShadowPages"); 1799 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1800 enable_stack_yellow_reserved_zone(); 1801 if (reserved_stack_activation() != stack_base()) { 1802 set_reserved_stack_activation(stack_base()); 1803 } 1804 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1805 set_reserved_stack_activation(stack_base()); 1806 enable_stack_reserved_zone(); 1807 } 1808 return true; 1809 } 1810 1811 bool JavaThread::reguard_stack(void) { 1812 return reguard_stack(os::current_stack_pointer()); 1813 } 1814 1815 void JavaThread::block_if_vm_exited() { 1816 if (_terminated == _vm_exited) { 1817 // _vm_exited is set at safepoint, and Threads_lock is never released 1818 // we will block here forever. 1819 // Here we can be doing a jump from a safe state to an unsafe state without 1820 // proper transition, but it happens after the final safepoint has begun. 1821 set_thread_state(_thread_in_vm); 1822 Threads_lock->lock(); 1823 ShouldNotReachHere(); 1824 } 1825 } 1826 1827 1828 // Remove this ifdef when C1 is ported to the compiler interface. 1829 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1830 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1831 1832 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1833 Thread() { 1834 initialize(); 1835 _jni_attach_state = _not_attaching_via_jni; 1836 set_entry_point(entry_point); 1837 // Create the native thread itself. 1838 // %note runtime_23 1839 os::ThreadType thr_type = os::java_thread; 1840 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1841 os::java_thread; 1842 os::create_thread(this, thr_type, stack_sz); 1843 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1844 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1845 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1846 // the exception consists of creating the exception object & initializing it, initialization 1847 // will leave the VM via a JavaCall and then all locks must be unlocked). 1848 // 1849 // The thread is still suspended when we reach here. Thread must be explicit started 1850 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1851 // by calling Threads:add. The reason why this is not done here, is because the thread 1852 // object must be fully initialized (take a look at JVM_Start) 1853 } 1854 1855 JavaThread::~JavaThread() { 1856 1857 // JSR166 -- return the parker to the free list 1858 Parker::Release(_parker); 1859 _parker = NULL; 1860 1861 // Return the sleep event to the free list 1862 ParkEvent::Release(_SleepEvent); 1863 _SleepEvent = NULL; 1864 1865 // Free any remaining previous UnrollBlock 1866 vframeArray* old_array = vframe_array_last(); 1867 1868 if (old_array != NULL) { 1869 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1870 old_array->set_unroll_block(NULL); 1871 delete old_info; 1872 delete old_array; 1873 } 1874 1875 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1876 if (deferred != NULL) { 1877 // This can only happen if thread is destroyed before deoptimization occurs. 1878 assert(deferred->length() != 0, "empty array!"); 1879 do { 1880 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1881 deferred->remove_at(0); 1882 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1883 delete dlv; 1884 } while (deferred->length() != 0); 1885 delete deferred; 1886 } 1887 1888 // All Java related clean up happens in exit 1889 ThreadSafepointState::destroy(this); 1890 if (_thread_stat != NULL) delete _thread_stat; 1891 1892 #if INCLUDE_JVMCI 1893 if (JVMCICounterSize > 0) { 1894 if (jvmci_counters_include(this)) { 1895 for (int i = 0; i < JVMCICounterSize; i++) { 1896 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1897 } 1898 } 1899 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1900 } 1901 #endif // INCLUDE_JVMCI 1902 } 1903 1904 1905 // First JavaThread specific code executed by a new Java thread. 1906 void JavaThread::pre_run() { 1907 // empty - see comments in run() 1908 } 1909 1910 // The main routine called by a new Java thread. This isn't overridden 1911 // by subclasses, instead different subclasses define a different "entry_point" 1912 // which defines the actual logic for that kind of thread. 1913 void JavaThread::run() { 1914 // initialize thread-local alloc buffer related fields 1915 this->initialize_tlab(); 1916 1917 // Used to test validity of stack trace backs. 1918 // This can't be moved into pre_run() else we invalidate 1919 // the requirement that thread_main_inner is lower on 1920 // the stack. Consequently all the initialization logic 1921 // stays here in run() rather than pre_run(). 1922 this->record_base_of_stack_pointer(); 1923 1924 this->create_stack_guard_pages(); 1925 1926 this->cache_global_variables(); 1927 1928 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1929 // in the VM. Change thread state from _thread_new to _thread_in_vm 1930 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1931 // Before a thread is on the threads list it is always safe, so after leaving the 1932 // _thread_new we should emit a instruction barrier. The distance to modified code 1933 // from here is probably far enough, but this is consistent and safe. 1934 OrderAccess::cross_modify_fence(); 1935 1936 assert(JavaThread::current() == this, "sanity check"); 1937 assert(!Thread::current()->owns_locks(), "sanity check"); 1938 1939 DTRACE_THREAD_PROBE(start, this); 1940 1941 // This operation might block. We call that after all safepoint checks for a new thread has 1942 // been completed. 1943 this->set_active_handles(JNIHandleBlock::allocate_block()); 1944 1945 if (JvmtiExport::should_post_thread_life()) { 1946 JvmtiExport::post_thread_start(this); 1947 1948 } 1949 1950 // We call another function to do the rest so we are sure that the stack addresses used 1951 // from there will be lower than the stack base just computed. 1952 thread_main_inner(); 1953 } 1954 1955 void JavaThread::thread_main_inner() { 1956 assert(JavaThread::current() == this, "sanity check"); 1957 assert(this->threadObj() != NULL, "just checking"); 1958 1959 // Execute thread entry point unless this thread has a pending exception 1960 // or has been stopped before starting. 1961 // Note: Due to JVM_StopThread we can have pending exceptions already! 1962 if (!this->has_pending_exception() && 1963 !java_lang_Thread::is_stillborn(this->threadObj())) { 1964 { 1965 ResourceMark rm(this); 1966 this->set_native_thread_name(this->get_thread_name()); 1967 } 1968 HandleMark hm(this); 1969 this->entry_point()(this, this); 1970 } 1971 1972 DTRACE_THREAD_PROBE(stop, this); 1973 1974 // Cleanup is handled in post_run() 1975 } 1976 1977 // Shared teardown for all JavaThreads 1978 void JavaThread::post_run() { 1979 this->exit(false); 1980 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1981 // for any shared tear-down. 1982 this->smr_delete(); 1983 } 1984 1985 static void ensure_join(JavaThread* thread) { 1986 // We do not need to grab the Threads_lock, since we are operating on ourself. 1987 Handle threadObj(thread, thread->threadObj()); 1988 assert(threadObj.not_null(), "java thread object must exist"); 1989 ObjectLocker lock(threadObj, thread); 1990 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1991 thread->clear_pending_exception(); 1992 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1993 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1994 // Clear the native thread instance - this makes isAlive return false and allows the join() 1995 // to complete once we've done the notify_all below 1996 java_lang_Thread::set_thread(threadObj(), NULL); 1997 lock.notify_all(thread); 1998 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1999 thread->clear_pending_exception(); 2000 } 2001 2002 static bool is_daemon(oop threadObj) { 2003 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 2004 } 2005 2006 // For any new cleanup additions, please check to see if they need to be applied to 2007 // cleanup_failed_attach_current_thread as well. 2008 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 2009 assert(this == JavaThread::current(), "thread consistency check"); 2010 2011 elapsedTimer _timer_exit_phase1; 2012 elapsedTimer _timer_exit_phase2; 2013 elapsedTimer _timer_exit_phase3; 2014 elapsedTimer _timer_exit_phase4; 2015 2016 if (log_is_enabled(Debug, os, thread, timer)) { 2017 _timer_exit_phase1.start(); 2018 } 2019 2020 HandleMark hm(this); 2021 Handle uncaught_exception(this, this->pending_exception()); 2022 this->clear_pending_exception(); 2023 Handle threadObj(this, this->threadObj()); 2024 assert(threadObj.not_null(), "Java thread object should be created"); 2025 2026 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 2027 { 2028 EXCEPTION_MARK; 2029 2030 CLEAR_PENDING_EXCEPTION; 2031 } 2032 if (!destroy_vm) { 2033 if (uncaught_exception.not_null()) { 2034 EXCEPTION_MARK; 2035 // Call method Thread.dispatchUncaughtException(). 2036 Klass* thread_klass = SystemDictionary::Thread_klass(); 2037 JavaValue result(T_VOID); 2038 JavaCalls::call_virtual(&result, 2039 threadObj, thread_klass, 2040 vmSymbols::dispatchUncaughtException_name(), 2041 vmSymbols::throwable_void_signature(), 2042 uncaught_exception, 2043 THREAD); 2044 if (HAS_PENDING_EXCEPTION) { 2045 ResourceMark rm(this); 2046 jio_fprintf(defaultStream::error_stream(), 2047 "\nException: %s thrown from the UncaughtExceptionHandler" 2048 " in thread \"%s\"\n", 2049 pending_exception()->klass()->external_name(), 2050 get_thread_name()); 2051 CLEAR_PENDING_EXCEPTION; 2052 } 2053 } 2054 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2055 2056 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2057 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2058 // is deprecated anyhow. 2059 if (!is_Compiler_thread()) { 2060 int count = 3; 2061 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2062 EXCEPTION_MARK; 2063 JavaValue result(T_VOID); 2064 Klass* thread_klass = SystemDictionary::Thread_klass(); 2065 JavaCalls::call_virtual(&result, 2066 threadObj, thread_klass, 2067 vmSymbols::exit_method_name(), 2068 vmSymbols::void_method_signature(), 2069 THREAD); 2070 CLEAR_PENDING_EXCEPTION; 2071 } 2072 } 2073 // notify JVMTI 2074 if (JvmtiExport::should_post_thread_life()) { 2075 JvmtiExport::post_thread_end(this); 2076 } 2077 2078 // We have notified the agents that we are exiting, before we go on, 2079 // we must check for a pending external suspend request and honor it 2080 // in order to not surprise the thread that made the suspend request. 2081 while (true) { 2082 { 2083 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2084 if (!is_external_suspend()) { 2085 set_terminated(_thread_exiting); 2086 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2087 break; 2088 } 2089 // Implied else: 2090 // Things get a little tricky here. We have a pending external 2091 // suspend request, but we are holding the SR_lock so we 2092 // can't just self-suspend. So we temporarily drop the lock 2093 // and then self-suspend. 2094 } 2095 2096 ThreadBlockInVM tbivm(this); 2097 java_suspend_self(); 2098 2099 // We're done with this suspend request, but we have to loop around 2100 // and check again. Eventually we will get SR_lock without a pending 2101 // external suspend request and will be able to mark ourselves as 2102 // exiting. 2103 } 2104 // no more external suspends are allowed at this point 2105 } else { 2106 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2107 // before_exit() has already posted JVMTI THREAD_END events 2108 } 2109 2110 if (log_is_enabled(Debug, os, thread, timer)) { 2111 _timer_exit_phase1.stop(); 2112 _timer_exit_phase2.start(); 2113 } 2114 2115 // Capture daemon status before the thread is marked as terminated. 2116 bool daemon = is_daemon(threadObj()); 2117 2118 // Notify waiters on thread object. This has to be done after exit() is called 2119 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2120 // group should have the destroyed bit set before waiters are notified). 2121 ensure_join(this); 2122 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2123 2124 if (log_is_enabled(Debug, os, thread, timer)) { 2125 _timer_exit_phase2.stop(); 2126 _timer_exit_phase3.start(); 2127 } 2128 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2129 // held by this thread must be released. The spec does not distinguish 2130 // between JNI-acquired and regular Java monitors. We can only see 2131 // regular Java monitors here if monitor enter-exit matching is broken. 2132 // 2133 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2134 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2135 if (exit_type == jni_detach) { 2136 // Sanity check even though JNI DetachCurrentThread() would have 2137 // returned JNI_ERR if there was a Java frame. JavaThread exit 2138 // should be done executing Java code by the time we get here. 2139 assert(!this->has_last_Java_frame(), 2140 "should not have a Java frame when detaching or exiting"); 2141 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2142 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2143 } 2144 2145 // These things needs to be done while we are still a Java Thread. Make sure that thread 2146 // is in a consistent state, in case GC happens 2147 JFR_ONLY(Jfr::on_thread_exit(this);) 2148 2149 if (active_handles() != NULL) { 2150 JNIHandleBlock* block = active_handles(); 2151 set_active_handles(NULL); 2152 JNIHandleBlock::release_block(block); 2153 } 2154 2155 if (free_handle_block() != NULL) { 2156 JNIHandleBlock* block = free_handle_block(); 2157 set_free_handle_block(NULL); 2158 JNIHandleBlock::release_block(block); 2159 } 2160 2161 // These have to be removed while this is still a valid thread. 2162 remove_stack_guard_pages(); 2163 2164 if (UseTLAB) { 2165 tlab().retire(); 2166 } 2167 2168 if (JvmtiEnv::environments_might_exist()) { 2169 JvmtiExport::cleanup_thread(this); 2170 } 2171 2172 // We need to cache the thread name for logging purposes below as once 2173 // we have called on_thread_detach this thread must not access any oops. 2174 char* thread_name = NULL; 2175 if (log_is_enabled(Debug, os, thread, timer)) { 2176 ResourceMark rm(this); 2177 thread_name = os::strdup(get_thread_name()); 2178 } 2179 2180 // We must flush any deferred card marks and other various GC barrier 2181 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2182 // before removing a thread from the list of active threads. 2183 BarrierSet::barrier_set()->on_thread_detach(this); 2184 2185 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2186 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2187 os::current_thread_id()); 2188 2189 if (log_is_enabled(Debug, os, thread, timer)) { 2190 _timer_exit_phase3.stop(); 2191 _timer_exit_phase4.start(); 2192 } 2193 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2194 Threads::remove(this, daemon); 2195 2196 if (log_is_enabled(Debug, os, thread, timer)) { 2197 _timer_exit_phase4.stop(); 2198 log_debug(os, thread, timer)("name='%s'" 2199 ", exit-phase1=" JLONG_FORMAT 2200 ", exit-phase2=" JLONG_FORMAT 2201 ", exit-phase3=" JLONG_FORMAT 2202 ", exit-phase4=" JLONG_FORMAT, 2203 thread_name, 2204 _timer_exit_phase1.milliseconds(), 2205 _timer_exit_phase2.milliseconds(), 2206 _timer_exit_phase3.milliseconds(), 2207 _timer_exit_phase4.milliseconds()); 2208 os::free(thread_name); 2209 } 2210 } 2211 2212 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2213 if (active_handles() != NULL) { 2214 JNIHandleBlock* block = active_handles(); 2215 set_active_handles(NULL); 2216 JNIHandleBlock::release_block(block); 2217 } 2218 2219 if (free_handle_block() != NULL) { 2220 JNIHandleBlock* block = free_handle_block(); 2221 set_free_handle_block(NULL); 2222 JNIHandleBlock::release_block(block); 2223 } 2224 2225 // These have to be removed while this is still a valid thread. 2226 remove_stack_guard_pages(); 2227 2228 if (UseTLAB) { 2229 tlab().retire(); 2230 } 2231 2232 BarrierSet::barrier_set()->on_thread_detach(this); 2233 2234 Threads::remove(this, is_daemon); 2235 this->smr_delete(); 2236 } 2237 2238 JavaThread* JavaThread::active() { 2239 Thread* thread = Thread::current(); 2240 if (thread->is_Java_thread()) { 2241 return (JavaThread*) thread; 2242 } else { 2243 assert(thread->is_VM_thread(), "this must be a vm thread"); 2244 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2245 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2246 assert(ret->is_Java_thread(), "must be a Java thread"); 2247 return ret; 2248 } 2249 } 2250 2251 bool JavaThread::is_lock_owned(address adr) const { 2252 if (Thread::is_lock_owned(adr)) return true; 2253 2254 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2255 if (chunk->contains(adr)) return true; 2256 } 2257 2258 return false; 2259 } 2260 2261 2262 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2263 chunk->set_next(monitor_chunks()); 2264 set_monitor_chunks(chunk); 2265 } 2266 2267 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2268 guarantee(monitor_chunks() != NULL, "must be non empty"); 2269 if (monitor_chunks() == chunk) { 2270 set_monitor_chunks(chunk->next()); 2271 } else { 2272 MonitorChunk* prev = monitor_chunks(); 2273 while (prev->next() != chunk) prev = prev->next(); 2274 prev->set_next(chunk->next()); 2275 } 2276 } 2277 2278 // JVM support. 2279 2280 // Note: this function shouldn't block if it's called in 2281 // _thread_in_native_trans state (such as from 2282 // check_special_condition_for_native_trans()). 2283 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2284 2285 if (has_last_Java_frame() && has_async_condition()) { 2286 // If we are at a polling page safepoint (not a poll return) 2287 // then we must defer async exception because live registers 2288 // will be clobbered by the exception path. Poll return is 2289 // ok because the call we a returning from already collides 2290 // with exception handling registers and so there is no issue. 2291 // (The exception handling path kills call result registers but 2292 // this is ok since the exception kills the result anyway). 2293 2294 if (is_at_poll_safepoint()) { 2295 // if the code we are returning to has deoptimized we must defer 2296 // the exception otherwise live registers get clobbered on the 2297 // exception path before deoptimization is able to retrieve them. 2298 // 2299 RegisterMap map(this, false); 2300 frame caller_fr = last_frame().sender(&map); 2301 assert(caller_fr.is_compiled_frame(), "what?"); 2302 if (caller_fr.is_deoptimized_frame()) { 2303 log_info(exceptions)("deferred async exception at compiled safepoint"); 2304 return; 2305 } 2306 } 2307 } 2308 2309 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2310 if (condition == _no_async_condition) { 2311 // Conditions have changed since has_special_runtime_exit_condition() 2312 // was called: 2313 // - if we were here only because of an external suspend request, 2314 // then that was taken care of above (or cancelled) so we are done 2315 // - if we were here because of another async request, then it has 2316 // been cleared between the has_special_runtime_exit_condition() 2317 // and now so again we are done 2318 return; 2319 } 2320 2321 // Check for pending async. exception 2322 if (_pending_async_exception != NULL) { 2323 // Only overwrite an already pending exception, if it is not a threadDeath. 2324 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2325 2326 // We cannot call Exceptions::_throw(...) here because we cannot block 2327 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2328 2329 LogTarget(Info, exceptions) lt; 2330 if (lt.is_enabled()) { 2331 ResourceMark rm; 2332 LogStream ls(lt); 2333 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2334 if (has_last_Java_frame()) { 2335 frame f = last_frame(); 2336 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2337 } 2338 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2339 } 2340 _pending_async_exception = NULL; 2341 clear_has_async_exception(); 2342 } 2343 } 2344 2345 if (check_unsafe_error && 2346 condition == _async_unsafe_access_error && !has_pending_exception()) { 2347 condition = _no_async_condition; // done 2348 switch (thread_state()) { 2349 case _thread_in_vm: { 2350 JavaThread* THREAD = this; 2351 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2352 } 2353 case _thread_in_native: { 2354 ThreadInVMfromNative tiv(this); 2355 JavaThread* THREAD = this; 2356 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2357 } 2358 case _thread_in_Java: { 2359 ThreadInVMfromJava tiv(this); 2360 JavaThread* THREAD = this; 2361 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2362 } 2363 default: 2364 ShouldNotReachHere(); 2365 } 2366 } 2367 2368 assert(condition == _no_async_condition || has_pending_exception() || 2369 (!check_unsafe_error && condition == _async_unsafe_access_error), 2370 "must have handled the async condition, if no exception"); 2371 } 2372 2373 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2374 2375 // Check for pending external suspend. 2376 if (is_external_suspend_with_lock()) { 2377 frame_anchor()->make_walkable(this); 2378 java_suspend_self_with_safepoint_check(); 2379 } 2380 2381 // We might be here for reasons in addition to the self-suspend request 2382 // so check for other async requests. 2383 if (check_asyncs) { 2384 check_and_handle_async_exceptions(); 2385 } 2386 2387 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2388 } 2389 2390 void JavaThread::send_thread_stop(oop java_throwable) { 2391 ResourceMark rm; 2392 assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread"); 2393 2394 // Do not throw asynchronous exceptions against the compiler thread 2395 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2396 if (!can_call_java()) return; 2397 2398 { 2399 // Actually throw the Throwable against the target Thread - however 2400 // only if there is no thread death exception installed already. 2401 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2402 // If the topmost frame is a runtime stub, then we are calling into 2403 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2404 // must deoptimize the caller before continuing, as the compiled exception handler table 2405 // may not be valid 2406 if (has_last_Java_frame()) { 2407 frame f = last_frame(); 2408 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2409 RegisterMap reg_map(this, false); 2410 frame compiled_frame = f.sender(®_map); 2411 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2412 Deoptimization::deoptimize(this, compiled_frame); 2413 } 2414 } 2415 } 2416 2417 // Set async. pending exception in thread. 2418 set_pending_async_exception(java_throwable); 2419 2420 if (log_is_enabled(Info, exceptions)) { 2421 ResourceMark rm; 2422 log_info(exceptions)("Pending Async. exception installed of type: %s", 2423 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2424 } 2425 // for AbortVMOnException flag 2426 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2427 } 2428 } 2429 2430 2431 // Interrupt thread so it will wake up from a potential wait()/sleep()/park() 2432 java_lang_Thread::set_interrupted(threadObj(), true); 2433 this->interrupt(); 2434 } 2435 2436 // External suspension mechanism. 2437 // 2438 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2439 // to any VM_locks and it is at a transition 2440 // Self-suspension will happen on the transition out of the vm. 2441 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2442 // 2443 // Guarantees on return: 2444 // + Target thread will not execute any new bytecode (that's why we need to 2445 // force a safepoint) 2446 // + Target thread will not enter any new monitors 2447 // 2448 void JavaThread::java_suspend() { 2449 ThreadsListHandle tlh; 2450 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2451 return; 2452 } 2453 2454 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2455 if (!is_external_suspend()) { 2456 // a racing resume has cancelled us; bail out now 2457 return; 2458 } 2459 2460 // suspend is done 2461 uint32_t debug_bits = 0; 2462 // Warning: is_ext_suspend_completed() may temporarily drop the 2463 // SR_lock to allow the thread to reach a stable thread state if 2464 // it is currently in a transient thread state. 2465 if (is_ext_suspend_completed(false /* !called_by_wait */, 2466 SuspendRetryDelay, &debug_bits)) { 2467 return; 2468 } 2469 } 2470 2471 if (Thread::current() == this) { 2472 // Safely self-suspend. 2473 // If we don't do this explicitly it will implicitly happen 2474 // before we transition back to Java, and on some other thread-state 2475 // transition paths, but not as we exit a JVM TI SuspendThread call. 2476 // As SuspendThread(current) must not return (until resumed) we must 2477 // self-suspend here. 2478 ThreadBlockInVM tbivm(this); 2479 java_suspend_self(); 2480 } else { 2481 VM_ThreadSuspend vm_suspend; 2482 VMThread::execute(&vm_suspend); 2483 } 2484 } 2485 2486 // Part II of external suspension. 2487 // A JavaThread self suspends when it detects a pending external suspend 2488 // request. This is usually on transitions. It is also done in places 2489 // where continuing to the next transition would surprise the caller, 2490 // e.g., monitor entry. 2491 // 2492 // Returns the number of times that the thread self-suspended. 2493 // 2494 // Note: DO NOT call java_suspend_self() when you just want to block current 2495 // thread. java_suspend_self() is the second stage of cooperative 2496 // suspension for external suspend requests and should only be used 2497 // to complete an external suspend request. 2498 // 2499 int JavaThread::java_suspend_self() { 2500 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2501 int ret = 0; 2502 2503 // we are in the process of exiting so don't suspend 2504 if (is_exiting()) { 2505 clear_external_suspend(); 2506 return ret; 2507 } 2508 2509 assert(_anchor.walkable() || 2510 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2511 "must have walkable stack"); 2512 2513 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2514 2515 assert(!this->is_ext_suspended(), 2516 "a thread trying to self-suspend should not already be suspended"); 2517 2518 if (this->is_suspend_equivalent()) { 2519 // If we are self-suspending as a result of the lifting of a 2520 // suspend equivalent condition, then the suspend_equivalent 2521 // flag is not cleared until we set the ext_suspended flag so 2522 // that wait_for_ext_suspend_completion() returns consistent 2523 // results. 2524 this->clear_suspend_equivalent(); 2525 } 2526 2527 // A racing resume may have cancelled us before we grabbed SR_lock 2528 // above. Or another external suspend request could be waiting for us 2529 // by the time we return from SR_lock()->wait(). The thread 2530 // that requested the suspension may already be trying to walk our 2531 // stack and if we return now, we can change the stack out from under 2532 // it. This would be a "bad thing (TM)" and cause the stack walker 2533 // to crash. We stay self-suspended until there are no more pending 2534 // external suspend requests. 2535 while (is_external_suspend()) { 2536 ret++; 2537 this->set_ext_suspended(); 2538 2539 // _ext_suspended flag is cleared by java_resume() 2540 while (is_ext_suspended()) { 2541 ml.wait(); 2542 } 2543 } 2544 return ret; 2545 } 2546 2547 // Helper routine to set up the correct thread state before calling java_suspend_self. 2548 // This is called when regular thread-state transition helpers can't be used because 2549 // we can be in various states, in particular _thread_in_native_trans. 2550 // Because this thread is external suspended the safepoint code will count it as at 2551 // a safepoint, regardless of what its actual current thread-state is. But 2552 // is_ext_suspend_completed() may be waiting to see a thread transition from 2553 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2554 // to _thread_blocked. The problem with setting thread state directly is that a 2555 // safepoint could happen just after java_suspend_self() returns after being resumed, 2556 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2557 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2558 // However, not all initial-states are allowed when performing a safepoint check, as we 2559 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2560 // only _thread_in_native is possible when executing this code (based on our two callers). 2561 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2562 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2563 // and so we don't need the explicit safepoint check. 2564 2565 void JavaThread::java_suspend_self_with_safepoint_check() { 2566 assert(this == Thread::current(), "invariant"); 2567 JavaThreadState state = thread_state(); 2568 set_thread_state(_thread_blocked); 2569 java_suspend_self(); 2570 set_thread_state_fence(state); 2571 // Since we are not using a regular thread-state transition helper here, 2572 // we must manually emit the instruction barrier after leaving a safe state. 2573 OrderAccess::cross_modify_fence(); 2574 if (state != _thread_in_native) { 2575 SafepointMechanism::block_if_requested(this); 2576 } 2577 } 2578 2579 #ifdef ASSERT 2580 // Verify the JavaThread has not yet been published in the Threads::list, and 2581 // hence doesn't need protection from concurrent access at this stage. 2582 void JavaThread::verify_not_published() { 2583 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2584 // since an unpublished JavaThread doesn't participate in the 2585 // Thread-SMR protocol for keeping a ThreadsList alive. 2586 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2587 } 2588 #endif 2589 2590 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2591 // progress or when _suspend_flags is non-zero. 2592 // Current thread needs to self-suspend if there is a suspend request and/or 2593 // block if a safepoint is in progress. 2594 // Async exception ISN'T checked. 2595 // Note only the ThreadInVMfromNative transition can call this function 2596 // directly and when thread state is _thread_in_native_trans 2597 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2598 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2599 2600 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2601 2602 if (thread->is_external_suspend()) { 2603 thread->java_suspend_self_with_safepoint_check(); 2604 } else { 2605 SafepointMechanism::block_if_requested(thread); 2606 } 2607 2608 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2609 } 2610 2611 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2612 // progress or when _suspend_flags is non-zero. 2613 // Current thread needs to self-suspend if there is a suspend request and/or 2614 // block if a safepoint is in progress. 2615 // Also check for pending async exception (not including unsafe access error). 2616 // Note only the native==>VM/Java barriers can call this function and when 2617 // thread state is _thread_in_native_trans. 2618 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2619 check_safepoint_and_suspend_for_native_trans(thread); 2620 2621 if (thread->has_async_exception()) { 2622 // We are in _thread_in_native_trans state, don't handle unsafe 2623 // access error since that may block. 2624 thread->check_and_handle_async_exceptions(false); 2625 } 2626 } 2627 2628 // This is a variant of the normal 2629 // check_special_condition_for_native_trans with slightly different 2630 // semantics for use by critical native wrappers. It does all the 2631 // normal checks but also performs the transition back into 2632 // thread_in_Java state. This is required so that critical natives 2633 // can potentially block and perform a GC if they are the last thread 2634 // exiting the GCLocker. 2635 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2636 check_special_condition_for_native_trans(thread); 2637 2638 // Finish the transition 2639 thread->set_thread_state(_thread_in_Java); 2640 2641 if (thread->do_critical_native_unlock()) { 2642 ThreadInVMfromJavaNoAsyncException tiv(thread); 2643 GCLocker::unlock_critical(thread); 2644 thread->clear_critical_native_unlock(); 2645 } 2646 } 2647 2648 // We need to guarantee the Threads_lock here, since resumes are not 2649 // allowed during safepoint synchronization 2650 // Can only resume from an external suspension 2651 void JavaThread::java_resume() { 2652 assert_locked_or_safepoint(Threads_lock); 2653 2654 // Sanity check: thread is gone, has started exiting or the thread 2655 // was not externally suspended. 2656 ThreadsListHandle tlh; 2657 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2658 return; 2659 } 2660 2661 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2662 2663 clear_external_suspend(); 2664 2665 if (is_ext_suspended()) { 2666 clear_ext_suspended(); 2667 SR_lock()->notify_all(); 2668 } 2669 } 2670 2671 size_t JavaThread::_stack_red_zone_size = 0; 2672 size_t JavaThread::_stack_yellow_zone_size = 0; 2673 size_t JavaThread::_stack_reserved_zone_size = 0; 2674 size_t JavaThread::_stack_shadow_zone_size = 0; 2675 2676 void JavaThread::create_stack_guard_pages() { 2677 if (!os::uses_stack_guard_pages() || 2678 _stack_guard_state != stack_guard_unused || 2679 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2680 log_info(os, thread)("Stack guard page creation for thread " 2681 UINTX_FORMAT " disabled", os::current_thread_id()); 2682 return; 2683 } 2684 address low_addr = stack_end(); 2685 size_t len = stack_guard_zone_size(); 2686 2687 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2688 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2689 2690 int must_commit = os::must_commit_stack_guard_pages(); 2691 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2692 2693 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2694 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2695 return; 2696 } 2697 2698 if (os::guard_memory((char *) low_addr, len)) { 2699 _stack_guard_state = stack_guard_enabled; 2700 } else { 2701 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2702 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2703 if (os::uncommit_memory((char *) low_addr, len)) { 2704 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2705 } 2706 return; 2707 } 2708 2709 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2710 PTR_FORMAT "-" PTR_FORMAT ".", 2711 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2712 } 2713 2714 void JavaThread::remove_stack_guard_pages() { 2715 assert(Thread::current() == this, "from different thread"); 2716 if (_stack_guard_state == stack_guard_unused) return; 2717 address low_addr = stack_end(); 2718 size_t len = stack_guard_zone_size(); 2719 2720 if (os::must_commit_stack_guard_pages()) { 2721 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2722 _stack_guard_state = stack_guard_unused; 2723 } else { 2724 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2725 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2726 return; 2727 } 2728 } else { 2729 if (_stack_guard_state == stack_guard_unused) return; 2730 if (os::unguard_memory((char *) low_addr, len)) { 2731 _stack_guard_state = stack_guard_unused; 2732 } else { 2733 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2734 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2735 return; 2736 } 2737 } 2738 2739 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2740 PTR_FORMAT "-" PTR_FORMAT ".", 2741 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2742 } 2743 2744 void JavaThread::enable_stack_reserved_zone() { 2745 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2746 2747 // The base notation is from the stack's point of view, growing downward. 2748 // We need to adjust it to work correctly with guard_memory() 2749 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2750 2751 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2752 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2753 2754 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2755 _stack_guard_state = stack_guard_enabled; 2756 } else { 2757 warning("Attempt to guard stack reserved zone failed."); 2758 } 2759 enable_register_stack_guard(); 2760 } 2761 2762 void JavaThread::disable_stack_reserved_zone() { 2763 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2764 2765 // Simply return if called for a thread that does not use guard pages. 2766 if (_stack_guard_state != stack_guard_enabled) return; 2767 2768 // The base notation is from the stack's point of view, growing downward. 2769 // We need to adjust it to work correctly with guard_memory() 2770 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2771 2772 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2773 _stack_guard_state = stack_guard_reserved_disabled; 2774 } else { 2775 warning("Attempt to unguard stack reserved zone failed."); 2776 } 2777 disable_register_stack_guard(); 2778 } 2779 2780 void JavaThread::enable_stack_yellow_reserved_zone() { 2781 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2782 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2783 2784 // The base notation is from the stacks point of view, growing downward. 2785 // We need to adjust it to work correctly with guard_memory() 2786 address base = stack_red_zone_base(); 2787 2788 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2789 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2790 2791 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2792 _stack_guard_state = stack_guard_enabled; 2793 } else { 2794 warning("Attempt to guard stack yellow zone failed."); 2795 } 2796 enable_register_stack_guard(); 2797 } 2798 2799 void JavaThread::disable_stack_yellow_reserved_zone() { 2800 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2801 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2802 2803 // Simply return if called for a thread that does not use guard pages. 2804 if (_stack_guard_state == stack_guard_unused) return; 2805 2806 // The base notation is from the stacks point of view, growing downward. 2807 // We need to adjust it to work correctly with guard_memory() 2808 address base = stack_red_zone_base(); 2809 2810 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2811 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2812 } else { 2813 warning("Attempt to unguard stack yellow zone failed."); 2814 } 2815 disable_register_stack_guard(); 2816 } 2817 2818 void JavaThread::enable_stack_red_zone() { 2819 // The base notation is from the stacks point of view, growing downward. 2820 // We need to adjust it to work correctly with guard_memory() 2821 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2822 address base = stack_red_zone_base() - stack_red_zone_size(); 2823 2824 guarantee(base < stack_base(), "Error calculating stack red zone"); 2825 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2826 2827 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2828 warning("Attempt to guard stack red zone failed."); 2829 } 2830 } 2831 2832 void JavaThread::disable_stack_red_zone() { 2833 // The base notation is from the stacks point of view, growing downward. 2834 // We need to adjust it to work correctly with guard_memory() 2835 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2836 address base = stack_red_zone_base() - stack_red_zone_size(); 2837 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2838 warning("Attempt to unguard stack red zone failed."); 2839 } 2840 } 2841 2842 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2843 // ignore is there is no stack 2844 if (!has_last_Java_frame()) return; 2845 // traverse the stack frames. Starts from top frame. 2846 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2847 frame* fr = fst.current(); 2848 f(fr, fst.register_map()); 2849 } 2850 } 2851 2852 2853 #ifndef PRODUCT 2854 // Deoptimization 2855 // Function for testing deoptimization 2856 void JavaThread::deoptimize() { 2857 StackFrameStream fst(this, false); 2858 bool deopt = false; // Dump stack only if a deopt actually happens. 2859 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2860 // Iterate over all frames in the thread and deoptimize 2861 for (; !fst.is_done(); fst.next()) { 2862 if (fst.current()->can_be_deoptimized()) { 2863 2864 if (only_at) { 2865 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2866 // consists of comma or carriage return separated numbers so 2867 // search for the current bci in that string. 2868 address pc = fst.current()->pc(); 2869 nmethod* nm = (nmethod*) fst.current()->cb(); 2870 ScopeDesc* sd = nm->scope_desc_at(pc); 2871 char buffer[8]; 2872 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2873 size_t len = strlen(buffer); 2874 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2875 while (found != NULL) { 2876 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2877 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2878 // Check that the bci found is bracketed by terminators. 2879 break; 2880 } 2881 found = strstr(found + 1, buffer); 2882 } 2883 if (!found) { 2884 continue; 2885 } 2886 } 2887 2888 if (DebugDeoptimization && !deopt) { 2889 deopt = true; // One-time only print before deopt 2890 tty->print_cr("[BEFORE Deoptimization]"); 2891 trace_frames(); 2892 trace_stack(); 2893 } 2894 Deoptimization::deoptimize(this, *fst.current()); 2895 } 2896 } 2897 2898 if (DebugDeoptimization && deopt) { 2899 tty->print_cr("[AFTER Deoptimization]"); 2900 trace_frames(); 2901 } 2902 } 2903 2904 2905 // Make zombies 2906 void JavaThread::make_zombies() { 2907 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2908 if (fst.current()->can_be_deoptimized()) { 2909 // it is a Java nmethod 2910 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2911 nm->make_not_entrant(); 2912 } 2913 } 2914 } 2915 #endif // PRODUCT 2916 2917 2918 void JavaThread::deoptimize_marked_methods() { 2919 if (!has_last_Java_frame()) return; 2920 StackFrameStream fst(this, false); 2921 for (; !fst.is_done(); fst.next()) { 2922 if (fst.current()->should_be_deoptimized()) { 2923 Deoptimization::deoptimize(this, *fst.current()); 2924 } 2925 } 2926 } 2927 2928 // If the caller is a NamedThread, then remember, in the current scope, 2929 // the given JavaThread in its _processed_thread field. 2930 class RememberProcessedThread: public StackObj { 2931 NamedThread* _cur_thr; 2932 public: 2933 RememberProcessedThread(JavaThread* jthr) { 2934 Thread* thread = Thread::current(); 2935 if (thread->is_Named_thread()) { 2936 _cur_thr = (NamedThread *)thread; 2937 _cur_thr->set_processed_thread(jthr); 2938 } else { 2939 _cur_thr = NULL; 2940 } 2941 } 2942 2943 ~RememberProcessedThread() { 2944 if (_cur_thr) { 2945 _cur_thr->set_processed_thread(NULL); 2946 } 2947 } 2948 }; 2949 2950 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2951 // Verify that the deferred card marks have been flushed. 2952 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2953 2954 // Traverse the GCHandles 2955 Thread::oops_do(f, cf); 2956 2957 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2958 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2959 2960 if (has_last_Java_frame()) { 2961 // Record JavaThread to GC thread 2962 RememberProcessedThread rpt(this); 2963 2964 // traverse the registered growable array 2965 if (_array_for_gc != NULL) { 2966 for (int index = 0; index < _array_for_gc->length(); index++) { 2967 f->do_oop(_array_for_gc->adr_at(index)); 2968 } 2969 } 2970 2971 // Traverse the monitor chunks 2972 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2973 chunk->oops_do(f); 2974 } 2975 2976 // Traverse the execution stack 2977 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2978 fst.current()->oops_do(f, cf, fst.register_map()); 2979 } 2980 } 2981 2982 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2983 // If we have deferred set_locals there might be oops waiting to be 2984 // written 2985 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2986 if (list != NULL) { 2987 for (int i = 0; i < list->length(); i++) { 2988 list->at(i)->oops_do(f); 2989 } 2990 } 2991 2992 // Traverse instance variables at the end since the GC may be moving things 2993 // around using this function 2994 f->do_oop((oop*) &_threadObj); 2995 f->do_oop((oop*) &_vm_result); 2996 f->do_oop((oop*) &_exception_oop); 2997 f->do_oop((oop*) &_pending_async_exception); 2998 2999 if (jvmti_thread_state() != NULL) { 3000 jvmti_thread_state()->oops_do(f, cf); 3001 } 3002 } 3003 3004 #ifdef ASSERT 3005 void JavaThread::verify_states_for_handshake() { 3006 // This checks that the thread has a correct frame state during a handshake. 3007 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3008 (has_last_Java_frame() && java_call_counter() > 0), 3009 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3010 has_last_Java_frame(), java_call_counter()); 3011 } 3012 #endif 3013 3014 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 3015 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3016 (has_last_Java_frame() && java_call_counter() > 0), 3017 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3018 has_last_Java_frame(), java_call_counter()); 3019 3020 if (has_last_Java_frame()) { 3021 // Traverse the execution stack 3022 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3023 fst.current()->nmethods_do(cf); 3024 } 3025 } 3026 3027 if (jvmti_thread_state() != NULL) { 3028 jvmti_thread_state()->nmethods_do(cf); 3029 } 3030 } 3031 3032 void JavaThread::metadata_do(MetadataClosure* f) { 3033 if (has_last_Java_frame()) { 3034 // Traverse the execution stack to call f() on the methods in the stack 3035 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3036 fst.current()->metadata_do(f); 3037 } 3038 } else if (is_Compiler_thread()) { 3039 // need to walk ciMetadata in current compile tasks to keep alive. 3040 CompilerThread* ct = (CompilerThread*)this; 3041 if (ct->env() != NULL) { 3042 ct->env()->metadata_do(f); 3043 } 3044 CompileTask* task = ct->task(); 3045 if (task != NULL) { 3046 task->metadata_do(f); 3047 } 3048 } 3049 } 3050 3051 // Printing 3052 const char* _get_thread_state_name(JavaThreadState _thread_state) { 3053 switch (_thread_state) { 3054 case _thread_uninitialized: return "_thread_uninitialized"; 3055 case _thread_new: return "_thread_new"; 3056 case _thread_new_trans: return "_thread_new_trans"; 3057 case _thread_in_native: return "_thread_in_native"; 3058 case _thread_in_native_trans: return "_thread_in_native_trans"; 3059 case _thread_in_vm: return "_thread_in_vm"; 3060 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3061 case _thread_in_Java: return "_thread_in_Java"; 3062 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3063 case _thread_blocked: return "_thread_blocked"; 3064 case _thread_blocked_trans: return "_thread_blocked_trans"; 3065 default: return "unknown thread state"; 3066 } 3067 } 3068 3069 #ifndef PRODUCT 3070 void JavaThread::print_thread_state_on(outputStream *st) const { 3071 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3072 }; 3073 #endif // PRODUCT 3074 3075 // Called by Threads::print() for VM_PrintThreads operation 3076 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3077 st->print_raw("\""); 3078 st->print_raw(get_thread_name()); 3079 st->print_raw("\" "); 3080 oop thread_oop = threadObj(); 3081 if (thread_oop != NULL) { 3082 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3083 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3084 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3085 } 3086 Thread::print_on(st, print_extended_info); 3087 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3088 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3089 if (thread_oop != NULL) { 3090 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3091 } 3092 #ifndef PRODUCT 3093 _safepoint_state->print_on(st); 3094 #endif // PRODUCT 3095 if (is_Compiler_thread()) { 3096 CompileTask *task = ((CompilerThread*)this)->task(); 3097 if (task != NULL) { 3098 st->print(" Compiling: "); 3099 task->print(st, NULL, true, false); 3100 } else { 3101 st->print(" No compile task"); 3102 } 3103 st->cr(); 3104 } 3105 } 3106 3107 void JavaThread::print() const { print_on(tty); } 3108 3109 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3110 st->print("%s", get_thread_name_string(buf, buflen)); 3111 } 3112 3113 // Called by fatal error handler. The difference between this and 3114 // JavaThread::print() is that we can't grab lock or allocate memory. 3115 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3116 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3117 oop thread_obj = threadObj(); 3118 if (thread_obj != NULL) { 3119 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3120 } 3121 st->print(" ["); 3122 st->print("%s", _get_thread_state_name(_thread_state)); 3123 if (osthread()) { 3124 st->print(", id=%d", osthread()->thread_id()); 3125 } 3126 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3127 p2i(stack_end()), p2i(stack_base())); 3128 st->print("]"); 3129 3130 ThreadsSMRSupport::print_info_on(this, st); 3131 return; 3132 } 3133 3134 // Verification 3135 3136 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3137 3138 void JavaThread::verify() { 3139 // Verify oops in the thread. 3140 oops_do(&VerifyOopClosure::verify_oop, NULL); 3141 3142 // Verify the stack frames. 3143 frames_do(frame_verify); 3144 } 3145 3146 // CR 6300358 (sub-CR 2137150) 3147 // Most callers of this method assume that it can't return NULL but a 3148 // thread may not have a name whilst it is in the process of attaching to 3149 // the VM - see CR 6412693, and there are places where a JavaThread can be 3150 // seen prior to having it's threadObj set (eg JNI attaching threads and 3151 // if vm exit occurs during initialization). These cases can all be accounted 3152 // for such that this method never returns NULL. 3153 const char* JavaThread::get_thread_name() const { 3154 #ifdef ASSERT 3155 // early safepoints can hit while current thread does not yet have TLS 3156 if (!SafepointSynchronize::is_at_safepoint()) { 3157 Thread *cur = Thread::current(); 3158 if (!(cur->is_Java_thread() && cur == this)) { 3159 // Current JavaThreads are allowed to get their own name without 3160 // the Threads_lock. 3161 assert_locked_or_safepoint_or_handshake(Threads_lock, this); 3162 } 3163 } 3164 #endif // ASSERT 3165 return get_thread_name_string(); 3166 } 3167 3168 // Returns a non-NULL representation of this thread's name, or a suitable 3169 // descriptive string if there is no set name 3170 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3171 const char* name_str; 3172 oop thread_obj = threadObj(); 3173 if (thread_obj != NULL) { 3174 oop name = java_lang_Thread::name(thread_obj); 3175 if (name != NULL) { 3176 if (buf == NULL) { 3177 name_str = java_lang_String::as_utf8_string(name); 3178 } else { 3179 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3180 } 3181 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3182 name_str = "<no-name - thread is attaching>"; 3183 } else { 3184 name_str = Thread::name(); 3185 } 3186 } else { 3187 name_str = Thread::name(); 3188 } 3189 assert(name_str != NULL, "unexpected NULL thread name"); 3190 return name_str; 3191 } 3192 3193 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3194 3195 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3196 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3197 // Link Java Thread object <-> C++ Thread 3198 3199 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3200 // and put it into a new Handle. The Handle "thread_oop" can then 3201 // be used to pass the C++ thread object to other methods. 3202 3203 // Set the Java level thread object (jthread) field of the 3204 // new thread (a JavaThread *) to C++ thread object using the 3205 // "thread_oop" handle. 3206 3207 // Set the thread field (a JavaThread *) of the 3208 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3209 3210 Handle thread_oop(Thread::current(), 3211 JNIHandles::resolve_non_null(jni_thread)); 3212 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3213 "must be initialized"); 3214 set_threadObj(thread_oop()); 3215 java_lang_Thread::set_thread(thread_oop(), this); 3216 3217 if (prio == NoPriority) { 3218 prio = java_lang_Thread::priority(thread_oop()); 3219 assert(prio != NoPriority, "A valid priority should be present"); 3220 } 3221 3222 // Push the Java priority down to the native thread; needs Threads_lock 3223 Thread::set_priority(this, prio); 3224 3225 // Add the new thread to the Threads list and set it in motion. 3226 // We must have threads lock in order to call Threads::add. 3227 // It is crucial that we do not block before the thread is 3228 // added to the Threads list for if a GC happens, then the java_thread oop 3229 // will not be visited by GC. 3230 Threads::add(this); 3231 } 3232 3233 oop JavaThread::current_park_blocker() { 3234 // Support for JSR-166 locks 3235 oop thread_oop = threadObj(); 3236 if (thread_oop != NULL) { 3237 return java_lang_Thread::park_blocker(thread_oop); 3238 } 3239 return NULL; 3240 } 3241 3242 3243 void JavaThread::print_stack_on(outputStream* st) { 3244 if (!has_last_Java_frame()) return; 3245 ResourceMark rm; 3246 HandleMark hm; 3247 3248 RegisterMap reg_map(this); 3249 vframe* start_vf = last_java_vframe(®_map); 3250 int count = 0; 3251 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3252 if (f->is_java_frame()) { 3253 javaVFrame* jvf = javaVFrame::cast(f); 3254 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3255 3256 // Print out lock information 3257 if (JavaMonitorsInStackTrace) { 3258 jvf->print_lock_info_on(st, count); 3259 } 3260 } else { 3261 // Ignore non-Java frames 3262 } 3263 3264 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3265 count++; 3266 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3267 } 3268 } 3269 3270 3271 // JVMTI PopFrame support 3272 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3273 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3274 if (in_bytes(size_in_bytes) != 0) { 3275 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3276 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3277 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3278 } 3279 } 3280 3281 void* JavaThread::popframe_preserved_args() { 3282 return _popframe_preserved_args; 3283 } 3284 3285 ByteSize JavaThread::popframe_preserved_args_size() { 3286 return in_ByteSize(_popframe_preserved_args_size); 3287 } 3288 3289 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3290 int sz = in_bytes(popframe_preserved_args_size()); 3291 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3292 return in_WordSize(sz / wordSize); 3293 } 3294 3295 void JavaThread::popframe_free_preserved_args() { 3296 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3297 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args); 3298 _popframe_preserved_args = NULL; 3299 _popframe_preserved_args_size = 0; 3300 } 3301 3302 #ifndef PRODUCT 3303 3304 void JavaThread::trace_frames() { 3305 tty->print_cr("[Describe stack]"); 3306 int frame_no = 1; 3307 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3308 tty->print(" %d. ", frame_no++); 3309 fst.current()->print_value_on(tty, this); 3310 tty->cr(); 3311 } 3312 } 3313 3314 class PrintAndVerifyOopClosure: public OopClosure { 3315 protected: 3316 template <class T> inline void do_oop_work(T* p) { 3317 oop obj = RawAccess<>::oop_load(p); 3318 if (obj == NULL) return; 3319 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3320 if (oopDesc::is_oop_or_null(obj)) { 3321 if (obj->is_objArray()) { 3322 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3323 } else { 3324 obj->print(); 3325 } 3326 } else { 3327 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3328 } 3329 tty->cr(); 3330 } 3331 public: 3332 virtual void do_oop(oop* p) { do_oop_work(p); } 3333 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3334 }; 3335 3336 #ifdef ASSERT 3337 // Print or validate the layout of stack frames 3338 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3339 ResourceMark rm; 3340 PRESERVE_EXCEPTION_MARK; 3341 FrameValues values; 3342 int frame_no = 0; 3343 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3344 fst.current()->describe(values, ++frame_no); 3345 if (depth == frame_no) break; 3346 } 3347 if (validate_only) { 3348 values.validate(); 3349 } else { 3350 tty->print_cr("[Describe stack layout]"); 3351 values.print(this); 3352 } 3353 } 3354 #endif 3355 3356 void JavaThread::trace_stack_from(vframe* start_vf) { 3357 ResourceMark rm; 3358 int vframe_no = 1; 3359 for (vframe* f = start_vf; f; f = f->sender()) { 3360 if (f->is_java_frame()) { 3361 javaVFrame::cast(f)->print_activation(vframe_no++); 3362 } else { 3363 f->print(); 3364 } 3365 if (vframe_no > StackPrintLimit) { 3366 tty->print_cr("...<more frames>..."); 3367 return; 3368 } 3369 } 3370 } 3371 3372 3373 void JavaThread::trace_stack() { 3374 if (!has_last_Java_frame()) return; 3375 ResourceMark rm; 3376 HandleMark hm; 3377 RegisterMap reg_map(this); 3378 trace_stack_from(last_java_vframe(®_map)); 3379 } 3380 3381 3382 #endif // PRODUCT 3383 3384 3385 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3386 assert(reg_map != NULL, "a map must be given"); 3387 frame f = last_frame(); 3388 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3389 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3390 } 3391 return NULL; 3392 } 3393 3394 3395 Klass* JavaThread::security_get_caller_class(int depth) { 3396 vframeStream vfst(this); 3397 vfst.security_get_caller_frame(depth); 3398 if (!vfst.at_end()) { 3399 return vfst.method()->method_holder(); 3400 } 3401 return NULL; 3402 } 3403 3404 // java.lang.Thread.sleep support 3405 // Returns true if sleep time elapsed as expected, and false 3406 // if the thread was interrupted. 3407 bool JavaThread::sleep(jlong millis) { 3408 assert(this == Thread::current(), "thread consistency check"); 3409 3410 ParkEvent * const slp = this->_SleepEvent; 3411 // Because there can be races with thread interruption sending an unpark() 3412 // to the event, we explicitly reset it here to avoid an immediate return. 3413 // The actual interrupt state will be checked before we park(). 3414 slp->reset(); 3415 // Thread interruption establishes a happens-before ordering in the 3416 // Java Memory Model, so we need to ensure we synchronize with the 3417 // interrupt state. 3418 OrderAccess::fence(); 3419 3420 jlong prevtime = os::javaTimeNanos(); 3421 3422 for (;;) { 3423 // interruption has precedence over timing out 3424 if (this->is_interrupted(true)) { 3425 return false; 3426 } 3427 3428 if (millis <= 0) { 3429 return true; 3430 } 3431 3432 { 3433 ThreadBlockInVM tbivm(this); 3434 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 3435 3436 this->set_suspend_equivalent(); 3437 // cleared by handle_special_suspend_equivalent_condition() or 3438 // java_suspend_self() via check_and_wait_while_suspended() 3439 3440 slp->park(millis); 3441 3442 // were we externally suspended while we were waiting? 3443 this->check_and_wait_while_suspended(); 3444 } 3445 3446 // Update elapsed time tracking 3447 jlong newtime = os::javaTimeNanos(); 3448 if (newtime - prevtime < 0) { 3449 // time moving backwards, should only happen if no monotonic clock 3450 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3451 assert(!os::supports_monotonic_clock(), 3452 "unexpected time moving backwards detected in JavaThread::sleep()"); 3453 } else { 3454 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3455 } 3456 prevtime = newtime; 3457 } 3458 } 3459 3460 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3461 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3462 CompileBroker::compiler_thread_loop(); 3463 } 3464 3465 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3466 NMethodSweeper::sweeper_loop(); 3467 } 3468 3469 // Create a CompilerThread 3470 CompilerThread::CompilerThread(CompileQueue* queue, 3471 CompilerCounters* counters) 3472 : JavaThread(&compiler_thread_entry) { 3473 _env = NULL; 3474 _log = NULL; 3475 _task = NULL; 3476 _queue = queue; 3477 _counters = counters; 3478 _buffer_blob = NULL; 3479 _compiler = NULL; 3480 3481 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3482 resource_area()->bias_to(mtCompiler); 3483 3484 #ifndef PRODUCT 3485 _ideal_graph_printer = NULL; 3486 #endif 3487 } 3488 3489 CompilerThread::~CompilerThread() { 3490 // Delete objects which were allocated on heap. 3491 delete _counters; 3492 } 3493 3494 bool CompilerThread::can_call_java() const { 3495 return _compiler != NULL && _compiler->is_jvmci(); 3496 } 3497 3498 // Create sweeper thread 3499 CodeCacheSweeperThread::CodeCacheSweeperThread() 3500 : JavaThread(&sweeper_thread_entry) { 3501 _scanned_compiled_method = NULL; 3502 } 3503 3504 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3505 JavaThread::oops_do(f, cf); 3506 if (_scanned_compiled_method != NULL && cf != NULL) { 3507 // Safepoints can occur when the sweeper is scanning an nmethod so 3508 // process it here to make sure it isn't unloaded in the middle of 3509 // a scan. 3510 cf->do_code_blob(_scanned_compiled_method); 3511 } 3512 } 3513 3514 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3515 JavaThread::nmethods_do(cf); 3516 if (_scanned_compiled_method != NULL && cf != NULL) { 3517 // Safepoints can occur when the sweeper is scanning an nmethod so 3518 // process it here to make sure it isn't unloaded in the middle of 3519 // a scan. 3520 cf->do_code_blob(_scanned_compiled_method); 3521 } 3522 } 3523 3524 3525 // ======= Threads ======== 3526 3527 // The Threads class links together all active threads, and provides 3528 // operations over all threads. It is protected by the Threads_lock, 3529 // which is also used in other global contexts like safepointing. 3530 // ThreadsListHandles are used to safely perform operations on one 3531 // or more threads without the risk of the thread exiting during the 3532 // operation. 3533 // 3534 // Note: The Threads_lock is currently more widely used than we 3535 // would like. We are actively migrating Threads_lock uses to other 3536 // mechanisms in order to reduce Threads_lock contention. 3537 3538 int Threads::_number_of_threads = 0; 3539 int Threads::_number_of_non_daemon_threads = 0; 3540 int Threads::_return_code = 0; 3541 uintx Threads::_thread_claim_token = 1; // Never zero. 3542 size_t JavaThread::_stack_size_at_create = 0; 3543 3544 #ifdef ASSERT 3545 bool Threads::_vm_complete = false; 3546 #endif 3547 3548 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3549 Prefetch::read((void*)addr, prefetch_interval); 3550 return *addr; 3551 } 3552 3553 // Possibly the ugliest for loop the world has seen. C++ does not allow 3554 // multiple types in the declaration section of the for loop. In this case 3555 // we are only dealing with pointers and hence can cast them. It looks ugly 3556 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3557 #define DO_JAVA_THREADS(LIST, X) \ 3558 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3559 *MACRO_list = (JavaThread*)(LIST), \ 3560 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3561 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3562 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3563 MACRO_current_p != MACRO_end; \ 3564 MACRO_current_p++, \ 3565 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3566 3567 // All JavaThreads 3568 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3569 3570 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3571 void Threads::non_java_threads_do(ThreadClosure* tc) { 3572 NoSafepointVerifier nsv; 3573 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3574 tc->do_thread(njti.current()); 3575 } 3576 } 3577 3578 // All JavaThreads 3579 void Threads::java_threads_do(ThreadClosure* tc) { 3580 assert_locked_or_safepoint(Threads_lock); 3581 // ALL_JAVA_THREADS iterates through all JavaThreads. 3582 ALL_JAVA_THREADS(p) { 3583 tc->do_thread(p); 3584 } 3585 } 3586 3587 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3588 assert_locked_or_safepoint(Threads_lock); 3589 java_threads_do(tc); 3590 tc->do_thread(VMThread::vm_thread()); 3591 } 3592 3593 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3594 void Threads::threads_do(ThreadClosure* tc) { 3595 assert_locked_or_safepoint(Threads_lock); 3596 java_threads_do(tc); 3597 non_java_threads_do(tc); 3598 } 3599 3600 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3601 uintx claim_token = Threads::thread_claim_token(); 3602 ALL_JAVA_THREADS(p) { 3603 if (p->claim_threads_do(is_par, claim_token)) { 3604 tc->do_thread(p); 3605 } 3606 } 3607 VMThread* vmt = VMThread::vm_thread(); 3608 if (vmt->claim_threads_do(is_par, claim_token)) { 3609 tc->do_thread(vmt); 3610 } 3611 } 3612 3613 // The system initialization in the library has three phases. 3614 // 3615 // Phase 1: java.lang.System class initialization 3616 // java.lang.System is a primordial class loaded and initialized 3617 // by the VM early during startup. java.lang.System.<clinit> 3618 // only does registerNatives and keeps the rest of the class 3619 // initialization work later until thread initialization completes. 3620 // 3621 // System.initPhase1 initializes the system properties, the static 3622 // fields in, out, and err. Set up java signal handlers, OS-specific 3623 // system settings, and thread group of the main thread. 3624 static void call_initPhase1(TRAPS) { 3625 Klass* klass = SystemDictionary::System_klass(); 3626 JavaValue result(T_VOID); 3627 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3628 vmSymbols::void_method_signature(), CHECK); 3629 } 3630 3631 // Phase 2. Module system initialization 3632 // This will initialize the module system. Only java.base classes 3633 // can be loaded until phase 2 completes. 3634 // 3635 // Call System.initPhase2 after the compiler initialization and jsr292 3636 // classes get initialized because module initialization runs a lot of java 3637 // code, that for performance reasons, should be compiled. Also, this will 3638 // enable the startup code to use lambda and other language features in this 3639 // phase and onward. 3640 // 3641 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3642 static void call_initPhase2(TRAPS) { 3643 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3644 3645 Klass* klass = SystemDictionary::System_klass(); 3646 3647 JavaValue result(T_INT); 3648 JavaCallArguments args; 3649 args.push_int(DisplayVMOutputToStderr); 3650 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3651 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3652 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3653 if (result.get_jint() != JNI_OK) { 3654 vm_exit_during_initialization(); // no message or exception 3655 } 3656 3657 universe_post_module_init(); 3658 } 3659 3660 // Phase 3. final setup - set security manager, system class loader and TCCL 3661 // 3662 // This will instantiate and set the security manager, set the system class 3663 // loader as well as the thread context class loader. The security manager 3664 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3665 // other modules or the application's classpath. 3666 static void call_initPhase3(TRAPS) { 3667 Klass* klass = SystemDictionary::System_klass(); 3668 JavaValue result(T_VOID); 3669 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3670 vmSymbols::void_method_signature(), CHECK); 3671 } 3672 3673 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3674 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3675 3676 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3677 create_vm_init_libraries(); 3678 } 3679 3680 initialize_class(vmSymbols::java_lang_String(), CHECK); 3681 3682 // Inject CompactStrings value after the static initializers for String ran. 3683 java_lang_String::set_compact_strings(CompactStrings); 3684 3685 // Initialize java_lang.System (needed before creating the thread) 3686 initialize_class(vmSymbols::java_lang_System(), CHECK); 3687 // The VM creates & returns objects of this class. Make sure it's initialized. 3688 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3689 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3690 Handle thread_group = create_initial_thread_group(CHECK); 3691 Universe::set_main_thread_group(thread_group()); 3692 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3693 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3694 main_thread->set_threadObj(thread_object); 3695 3696 // Set thread status to running since main thread has 3697 // been started and running. 3698 java_lang_Thread::set_thread_status(thread_object, 3699 java_lang_Thread::RUNNABLE); 3700 3701 // The VM creates objects of this class. 3702 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3703 3704 #ifdef ASSERT 3705 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3706 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3707 #endif 3708 3709 // initialize the hardware-specific constants needed by Unsafe 3710 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3711 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3712 3713 // The VM preresolves methods to these classes. Make sure that they get initialized 3714 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3715 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3716 3717 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3718 call_initPhase1(CHECK); 3719 3720 // get the Java runtime name, version, and vendor info after java.lang.System is initialized 3721 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3722 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3723 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD)); 3724 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD)); 3725 3726 // an instance of OutOfMemory exception has been allocated earlier 3727 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3728 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3729 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3730 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3731 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3732 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3733 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3734 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3735 3736 // Eager box cache initialization only if AOT is on and any library is loaded. 3737 AOTLoader::initialize_box_caches(CHECK); 3738 } 3739 3740 void Threads::initialize_jsr292_core_classes(TRAPS) { 3741 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3742 3743 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3744 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3745 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3746 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3747 } 3748 3749 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3750 extern void JDK_Version_init(); 3751 3752 // Preinitialize version info. 3753 VM_Version::early_initialize(); 3754 3755 // Check version 3756 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3757 3758 // Initialize library-based TLS 3759 ThreadLocalStorage::init(); 3760 3761 // Initialize the output stream module 3762 ostream_init(); 3763 3764 // Process java launcher properties. 3765 Arguments::process_sun_java_launcher_properties(args); 3766 3767 // Initialize the os module 3768 os::init(); 3769 3770 // Record VM creation timing statistics 3771 TraceVmCreationTime create_vm_timer; 3772 create_vm_timer.start(); 3773 3774 // Initialize system properties. 3775 Arguments::init_system_properties(); 3776 3777 // So that JDK version can be used as a discriminator when parsing arguments 3778 JDK_Version_init(); 3779 3780 // Update/Initialize System properties after JDK version number is known 3781 Arguments::init_version_specific_system_properties(); 3782 3783 // Make sure to initialize log configuration *before* parsing arguments 3784 LogConfiguration::initialize(create_vm_timer.begin_time()); 3785 3786 // Parse arguments 3787 // Note: this internally calls os::init_container_support() 3788 jint parse_result = Arguments::parse(args); 3789 if (parse_result != JNI_OK) return parse_result; 3790 3791 os::init_before_ergo(); 3792 3793 jint ergo_result = Arguments::apply_ergo(); 3794 if (ergo_result != JNI_OK) return ergo_result; 3795 3796 // Final check of all ranges after ergonomics which may change values. 3797 if (!JVMFlagRangeList::check_ranges()) { 3798 return JNI_EINVAL; 3799 } 3800 3801 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3802 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3803 if (!constraint_result) { 3804 return JNI_EINVAL; 3805 } 3806 3807 if (PauseAtStartup) { 3808 os::pause(); 3809 } 3810 3811 HOTSPOT_VM_INIT_BEGIN(); 3812 3813 // Timing (must come after argument parsing) 3814 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3815 3816 // Initialize the os module after parsing the args 3817 jint os_init_2_result = os::init_2(); 3818 if (os_init_2_result != JNI_OK) return os_init_2_result; 3819 3820 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3821 // Initialize assert poison page mechanism. 3822 if (ShowRegistersOnAssert) { 3823 initialize_assert_poison(); 3824 } 3825 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3826 3827 SafepointMechanism::initialize(); 3828 3829 jint adjust_after_os_result = Arguments::adjust_after_os(); 3830 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3831 3832 // Initialize output stream logging 3833 ostream_init_log(); 3834 3835 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3836 // Must be before create_vm_init_agents() 3837 if (Arguments::init_libraries_at_startup()) { 3838 convert_vm_init_libraries_to_agents(); 3839 } 3840 3841 // Launch -agentlib/-agentpath and converted -Xrun agents 3842 if (Arguments::init_agents_at_startup()) { 3843 create_vm_init_agents(); 3844 } 3845 3846 // Initialize Threads state 3847 _number_of_threads = 0; 3848 _number_of_non_daemon_threads = 0; 3849 3850 // Initialize global data structures and create system classes in heap 3851 vm_init_globals(); 3852 3853 #if INCLUDE_JVMCI 3854 if (JVMCICounterSize > 0) { 3855 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3856 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3857 } else { 3858 JavaThread::_jvmci_old_thread_counters = NULL; 3859 } 3860 #endif // INCLUDE_JVMCI 3861 3862 // Attach the main thread to this os thread 3863 JavaThread* main_thread = new JavaThread(); 3864 main_thread->set_thread_state(_thread_in_vm); 3865 main_thread->initialize_thread_current(); 3866 // must do this before set_active_handles 3867 main_thread->record_stack_base_and_size(); 3868 main_thread->register_thread_stack_with_NMT(); 3869 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3870 3871 if (!main_thread->set_as_starting_thread()) { 3872 vm_shutdown_during_initialization( 3873 "Failed necessary internal allocation. Out of swap space"); 3874 main_thread->smr_delete(); 3875 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3876 return JNI_ENOMEM; 3877 } 3878 3879 // Enable guard page *after* os::create_main_thread(), otherwise it would 3880 // crash Linux VM, see notes in os_linux.cpp. 3881 main_thread->create_stack_guard_pages(); 3882 3883 // Initialize Java-Level synchronization subsystem 3884 ObjectMonitor::Initialize(); 3885 3886 // Initialize global modules 3887 jint status = init_globals(); 3888 if (status != JNI_OK) { 3889 main_thread->smr_delete(); 3890 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3891 return status; 3892 } 3893 3894 JFR_ONLY(Jfr::on_create_vm_1();) 3895 3896 // Should be done after the heap is fully created 3897 main_thread->cache_global_variables(); 3898 3899 HandleMark hm; 3900 3901 { MutexLocker mu(Threads_lock); 3902 Threads::add(main_thread); 3903 } 3904 3905 // Any JVMTI raw monitors entered in onload will transition into 3906 // real raw monitor. VM is setup enough here for raw monitor enter. 3907 JvmtiExport::transition_pending_onload_raw_monitors(); 3908 3909 // Create the VMThread 3910 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3911 3912 VMThread::create(); 3913 Thread* vmthread = VMThread::vm_thread(); 3914 3915 if (!os::create_thread(vmthread, os::vm_thread)) { 3916 vm_exit_during_initialization("Cannot create VM thread. " 3917 "Out of system resources."); 3918 } 3919 3920 // Wait for the VM thread to become ready, and VMThread::run to initialize 3921 // Monitors can have spurious returns, must always check another state flag 3922 { 3923 MonitorLocker ml(Notify_lock); 3924 os::start_thread(vmthread); 3925 while (vmthread->active_handles() == NULL) { 3926 ml.wait(); 3927 } 3928 } 3929 } 3930 3931 assert(Universe::is_fully_initialized(), "not initialized"); 3932 if (VerifyDuringStartup) { 3933 // Make sure we're starting with a clean slate. 3934 VM_Verify verify_op; 3935 VMThread::execute(&verify_op); 3936 } 3937 3938 // We need this to update the java.vm.info property in case any flags used 3939 // to initially define it have been changed. This is needed for both CDS and 3940 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3941 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3942 // This update must happen before we initialize the java classes, but 3943 // after any initialization logic that might modify the flags. 3944 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3945 3946 Thread* THREAD = Thread::current(); 3947 3948 // Always call even when there are not JVMTI environments yet, since environments 3949 // may be attached late and JVMTI must track phases of VM execution 3950 JvmtiExport::enter_early_start_phase(); 3951 3952 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3953 JvmtiExport::post_early_vm_start(); 3954 3955 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3956 3957 quicken_jni_functions(); 3958 3959 // No more stub generation allowed after that point. 3960 StubCodeDesc::freeze(); 3961 3962 // Set flag that basic initialization has completed. Used by exceptions and various 3963 // debug stuff, that does not work until all basic classes have been initialized. 3964 set_init_completed(); 3965 3966 LogConfiguration::post_initialize(); 3967 Metaspace::post_initialize(); 3968 3969 HOTSPOT_VM_INIT_END(); 3970 3971 // record VM initialization completion time 3972 #if INCLUDE_MANAGEMENT 3973 Management::record_vm_init_completed(); 3974 #endif // INCLUDE_MANAGEMENT 3975 3976 // Signal Dispatcher needs to be started before VMInit event is posted 3977 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3978 3979 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3980 if (!DisableAttachMechanism) { 3981 AttachListener::vm_start(); 3982 if (StartAttachListener || AttachListener::init_at_startup()) { 3983 AttachListener::init(); 3984 } 3985 } 3986 3987 // Launch -Xrun agents 3988 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3989 // back-end can launch with -Xdebug -Xrunjdwp. 3990 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3991 create_vm_init_libraries(); 3992 } 3993 3994 if (CleanChunkPoolAsync) { 3995 Chunk::start_chunk_pool_cleaner_task(); 3996 } 3997 3998 // Start the service thread 3999 // The service thread enqueues JVMTI deferred events and does various hashtable 4000 // and other cleanups. Needs to start before the compilers start posting events. 4001 ServiceThread::initialize(); 4002 4003 // initialize compiler(s) 4004 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 4005 #if INCLUDE_JVMCI 4006 bool force_JVMCI_intialization = false; 4007 if (EnableJVMCI) { 4008 // Initialize JVMCI eagerly when it is explicitly requested. 4009 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 4010 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 4011 4012 if (!force_JVMCI_intialization) { 4013 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4014 // compilations via JVMCI will not actually block until JVMCI is initialized. 4015 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4016 } 4017 } 4018 #endif 4019 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 4020 // Postpone completion of compiler initialization to after JVMCI 4021 // is initialized to avoid timeouts of blocking compilations. 4022 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 4023 CompileBroker::compilation_init_phase2(); 4024 } 4025 #endif 4026 4027 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4028 // It is done after compilers are initialized, because otherwise compilations of 4029 // signature polymorphic MH intrinsics can be missed 4030 // (see SystemDictionary::find_method_handle_intrinsic). 4031 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4032 4033 // This will initialize the module system. Only java.base classes can be 4034 // loaded until phase 2 completes 4035 call_initPhase2(CHECK_JNI_ERR); 4036 4037 JFR_ONLY(Jfr::on_create_vm_2();) 4038 4039 // Always call even when there are not JVMTI environments yet, since environments 4040 // may be attached late and JVMTI must track phases of VM execution 4041 JvmtiExport::enter_start_phase(); 4042 4043 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4044 JvmtiExport::post_vm_start(); 4045 4046 // Final system initialization including security manager and system class loader 4047 call_initPhase3(CHECK_JNI_ERR); 4048 4049 // cache the system and platform class loaders 4050 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4051 4052 #if INCLUDE_CDS 4053 // capture the module path info from the ModuleEntryTable 4054 ClassLoader::initialize_module_path(THREAD); 4055 #endif 4056 4057 #if INCLUDE_JVMCI 4058 if (force_JVMCI_intialization) { 4059 JVMCI::initialize_compiler(CHECK_JNI_ERR); 4060 CompileBroker::compilation_init_phase2(); 4061 } 4062 #endif 4063 4064 // Always call even when there are not JVMTI environments yet, since environments 4065 // may be attached late and JVMTI must track phases of VM execution 4066 JvmtiExport::enter_live_phase(); 4067 4068 // Make perfmemory accessible 4069 PerfMemory::set_accessible(true); 4070 4071 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4072 JvmtiExport::post_vm_initialized(); 4073 4074 JFR_ONLY(Jfr::on_create_vm_3();) 4075 4076 #if INCLUDE_MANAGEMENT 4077 Management::initialize(THREAD); 4078 4079 if (HAS_PENDING_EXCEPTION) { 4080 // management agent fails to start possibly due to 4081 // configuration problem and is responsible for printing 4082 // stack trace if appropriate. Simply exit VM. 4083 vm_exit(1); 4084 } 4085 #endif // INCLUDE_MANAGEMENT 4086 4087 if (MemProfiling) MemProfiler::engage(); 4088 StatSampler::engage(); 4089 if (CheckJNICalls) JniPeriodicChecker::engage(); 4090 4091 BiasedLocking::init(); 4092 4093 #if INCLUDE_RTM_OPT 4094 RTMLockingCounters::init(); 4095 #endif 4096 4097 call_postVMInitHook(THREAD); 4098 // The Java side of PostVMInitHook.run must deal with all 4099 // exceptions and provide means of diagnosis. 4100 if (HAS_PENDING_EXCEPTION) { 4101 CLEAR_PENDING_EXCEPTION; 4102 } 4103 4104 { 4105 MutexLocker ml(PeriodicTask_lock); 4106 // Make sure the WatcherThread can be started by WatcherThread::start() 4107 // or by dynamic enrollment. 4108 WatcherThread::make_startable(); 4109 // Start up the WatcherThread if there are any periodic tasks 4110 // NOTE: All PeriodicTasks should be registered by now. If they 4111 // aren't, late joiners might appear to start slowly (we might 4112 // take a while to process their first tick). 4113 if (PeriodicTask::num_tasks() > 0) { 4114 WatcherThread::start(); 4115 } 4116 } 4117 4118 create_vm_timer.end(); 4119 #ifdef ASSERT 4120 _vm_complete = true; 4121 #endif 4122 4123 if (DumpSharedSpaces) { 4124 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4125 ShouldNotReachHere(); 4126 } 4127 4128 return JNI_OK; 4129 } 4130 4131 // type for the Agent_OnLoad and JVM_OnLoad entry points 4132 extern "C" { 4133 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4134 } 4135 // Find a command line agent library and return its entry point for 4136 // -agentlib: -agentpath: -Xrun 4137 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4138 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4139 const char *on_load_symbols[], 4140 size_t num_symbol_entries) { 4141 OnLoadEntry_t on_load_entry = NULL; 4142 void *library = NULL; 4143 4144 if (!agent->valid()) { 4145 char buffer[JVM_MAXPATHLEN]; 4146 char ebuf[1024] = ""; 4147 const char *name = agent->name(); 4148 const char *msg = "Could not find agent library "; 4149 4150 // First check to see if agent is statically linked into executable 4151 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4152 library = agent->os_lib(); 4153 } else if (agent->is_absolute_path()) { 4154 library = os::dll_load(name, ebuf, sizeof ebuf); 4155 if (library == NULL) { 4156 const char *sub_msg = " in absolute path, with error: "; 4157 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4158 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4159 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4160 // If we can't find the agent, exit. 4161 vm_exit_during_initialization(buf, NULL); 4162 FREE_C_HEAP_ARRAY(char, buf); 4163 } 4164 } else { 4165 // Try to load the agent from the standard dll directory 4166 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4167 name)) { 4168 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4169 } 4170 if (library == NULL) { // Try the library path directory. 4171 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4172 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4173 } 4174 if (library == NULL) { 4175 const char *sub_msg = " on the library path, with error: "; 4176 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4177 4178 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4179 strlen(ebuf) + strlen(sub_msg2) + 1; 4180 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4181 if (!agent->is_instrument_lib()) { 4182 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4183 } else { 4184 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4185 } 4186 // If we can't find the agent, exit. 4187 vm_exit_during_initialization(buf, NULL); 4188 FREE_C_HEAP_ARRAY(char, buf); 4189 } 4190 } 4191 } 4192 agent->set_os_lib(library); 4193 agent->set_valid(); 4194 } 4195 4196 // Find the OnLoad function. 4197 on_load_entry = 4198 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4199 false, 4200 on_load_symbols, 4201 num_symbol_entries)); 4202 return on_load_entry; 4203 } 4204 4205 // Find the JVM_OnLoad entry point 4206 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4207 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4208 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4209 } 4210 4211 // Find the Agent_OnLoad entry point 4212 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4213 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4214 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4215 } 4216 4217 // For backwards compatibility with -Xrun 4218 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4219 // treated like -agentpath: 4220 // Must be called before agent libraries are created 4221 void Threads::convert_vm_init_libraries_to_agents() { 4222 AgentLibrary* agent; 4223 AgentLibrary* next; 4224 4225 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4226 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4227 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4228 4229 // If there is an JVM_OnLoad function it will get called later, 4230 // otherwise see if there is an Agent_OnLoad 4231 if (on_load_entry == NULL) { 4232 on_load_entry = lookup_agent_on_load(agent); 4233 if (on_load_entry != NULL) { 4234 // switch it to the agent list -- so that Agent_OnLoad will be called, 4235 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4236 Arguments::convert_library_to_agent(agent); 4237 } else { 4238 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4239 } 4240 } 4241 } 4242 } 4243 4244 // Create agents for -agentlib: -agentpath: and converted -Xrun 4245 // Invokes Agent_OnLoad 4246 // Called very early -- before JavaThreads exist 4247 void Threads::create_vm_init_agents() { 4248 extern struct JavaVM_ main_vm; 4249 AgentLibrary* agent; 4250 4251 JvmtiExport::enter_onload_phase(); 4252 4253 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4254 // CDS dumping does not support native JVMTI agent. 4255 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4256 if (Arguments::is_dumping_archive()) { 4257 if(!agent->is_instrument_lib()) { 4258 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4259 } else if (!AllowArchivingWithJavaAgent) { 4260 vm_exit_during_cds_dumping( 4261 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4262 } 4263 } 4264 4265 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4266 4267 if (on_load_entry != NULL) { 4268 // Invoke the Agent_OnLoad function 4269 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4270 if (err != JNI_OK) { 4271 vm_exit_during_initialization("agent library failed to init", agent->name()); 4272 } 4273 } else { 4274 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4275 } 4276 } 4277 4278 JvmtiExport::enter_primordial_phase(); 4279 } 4280 4281 extern "C" { 4282 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4283 } 4284 4285 void Threads::shutdown_vm_agents() { 4286 // Send any Agent_OnUnload notifications 4287 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4288 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4289 extern struct JavaVM_ main_vm; 4290 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4291 4292 // Find the Agent_OnUnload function. 4293 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4294 os::find_agent_function(agent, 4295 false, 4296 on_unload_symbols, 4297 num_symbol_entries)); 4298 4299 // Invoke the Agent_OnUnload function 4300 if (unload_entry != NULL) { 4301 JavaThread* thread = JavaThread::current(); 4302 ThreadToNativeFromVM ttn(thread); 4303 HandleMark hm(thread); 4304 (*unload_entry)(&main_vm); 4305 } 4306 } 4307 } 4308 4309 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4310 // Invokes JVM_OnLoad 4311 void Threads::create_vm_init_libraries() { 4312 extern struct JavaVM_ main_vm; 4313 AgentLibrary* agent; 4314 4315 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4316 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4317 4318 if (on_load_entry != NULL) { 4319 // Invoke the JVM_OnLoad function 4320 JavaThread* thread = JavaThread::current(); 4321 ThreadToNativeFromVM ttn(thread); 4322 HandleMark hm(thread); 4323 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4324 if (err != JNI_OK) { 4325 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4326 } 4327 } else { 4328 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4329 } 4330 } 4331 } 4332 4333 4334 // Last thread running calls java.lang.Shutdown.shutdown() 4335 void JavaThread::invoke_shutdown_hooks() { 4336 HandleMark hm(this); 4337 4338 // Link all classes for dynamic CDS dumping before vm exit. 4339 // Same operation is being done in JVM_BeforeHalt for handling the 4340 // case where the application calls System.exit(). 4341 if (DynamicDumpSharedSpaces) { 4342 MetaspaceShared::link_and_cleanup_shared_classes(this); 4343 } 4344 4345 // We could get here with a pending exception, if so clear it now. 4346 if (this->has_pending_exception()) { 4347 this->clear_pending_exception(); 4348 } 4349 4350 EXCEPTION_MARK; 4351 Klass* shutdown_klass = 4352 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4353 THREAD); 4354 if (shutdown_klass != NULL) { 4355 // SystemDictionary::resolve_or_null will return null if there was 4356 // an exception. If we cannot load the Shutdown class, just don't 4357 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4358 // won't be run. Note that if a shutdown hook was registered, 4359 // the Shutdown class would have already been loaded 4360 // (Runtime.addShutdownHook will load it). 4361 JavaValue result(T_VOID); 4362 JavaCalls::call_static(&result, 4363 shutdown_klass, 4364 vmSymbols::shutdown_name(), 4365 vmSymbols::void_method_signature(), 4366 THREAD); 4367 } 4368 CLEAR_PENDING_EXCEPTION; 4369 } 4370 4371 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4372 // the program falls off the end of main(). Another VM exit path is through 4373 // vm_exit() when the program calls System.exit() to return a value or when 4374 // there is a serious error in VM. The two shutdown paths are not exactly 4375 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4376 // and VM_Exit op at VM level. 4377 // 4378 // Shutdown sequence: 4379 // + Shutdown native memory tracking if it is on 4380 // + Wait until we are the last non-daemon thread to execute 4381 // <-- every thing is still working at this moment --> 4382 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4383 // shutdown hooks 4384 // + Call before_exit(), prepare for VM exit 4385 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4386 // currently the only user of this mechanism is File.deleteOnExit()) 4387 // > stop StatSampler, watcher thread, 4388 // post thread end and vm death events to JVMTI, 4389 // stop signal thread 4390 // + Call JavaThread::exit(), it will: 4391 // > release JNI handle blocks, remove stack guard pages 4392 // > remove this thread from Threads list 4393 // <-- no more Java code from this thread after this point --> 4394 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4395 // the compiler threads at safepoint 4396 // <-- do not use anything that could get blocked by Safepoint --> 4397 // + Disable tracing at JNI/JVM barriers 4398 // + Set _vm_exited flag for threads that are still running native code 4399 // + Call exit_globals() 4400 // > deletes tty 4401 // > deletes PerfMemory resources 4402 // + Delete this thread 4403 // + Return to caller 4404 4405 bool Threads::destroy_vm() { 4406 JavaThread* thread = JavaThread::current(); 4407 4408 #ifdef ASSERT 4409 _vm_complete = false; 4410 #endif 4411 // Wait until we are the last non-daemon thread to execute 4412 { MonitorLocker nu(Threads_lock); 4413 while (Threads::number_of_non_daemon_threads() > 1) 4414 // This wait should make safepoint checks, wait without a timeout, 4415 // and wait as a suspend-equivalent condition. 4416 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4417 } 4418 4419 EventShutdown e; 4420 if (e.should_commit()) { 4421 e.set_reason("No remaining non-daemon Java threads"); 4422 e.commit(); 4423 } 4424 4425 // Hang forever on exit if we are reporting an error. 4426 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4427 os::infinite_sleep(); 4428 } 4429 os::wait_for_keypress_at_exit(); 4430 4431 // run Java level shutdown hooks 4432 thread->invoke_shutdown_hooks(); 4433 4434 before_exit(thread); 4435 4436 thread->exit(true); 4437 4438 // We are no longer on the main thread list but could still be in a 4439 // secondary list where another thread may try to interact with us. 4440 // So wait until all such interactions are complete before we bring 4441 // the VM to the termination safepoint. Normally this would be done 4442 // using thread->smr_delete() below where we delete the thread, but 4443 // we can't call that after the termination safepoint is active as 4444 // we will deadlock on the Threads_lock. Once all interactions are 4445 // complete it is safe to directly delete the thread at any time. 4446 ThreadsSMRSupport::wait_until_not_protected(thread); 4447 4448 // Stop VM thread. 4449 { 4450 // 4945125 The vm thread comes to a safepoint during exit. 4451 // GC vm_operations can get caught at the safepoint, and the 4452 // heap is unparseable if they are caught. Grab the Heap_lock 4453 // to prevent this. The GC vm_operations will not be able to 4454 // queue until after the vm thread is dead. After this point, 4455 // we'll never emerge out of the safepoint before the VM exits. 4456 4457 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4458 4459 VMThread::wait_for_vm_thread_exit(); 4460 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4461 VMThread::destroy(); 4462 } 4463 4464 // Now, all Java threads are gone except daemon threads. Daemon threads 4465 // running Java code or in VM are stopped by the Safepoint. However, 4466 // daemon threads executing native code are still running. But they 4467 // will be stopped at native=>Java/VM barriers. Note that we can't 4468 // simply kill or suspend them, as it is inherently deadlock-prone. 4469 4470 VM_Exit::set_vm_exited(); 4471 4472 // Clean up ideal graph printers after the VMThread has started 4473 // the final safepoint which will block all the Compiler threads. 4474 // Note that this Thread has already logically exited so the 4475 // clean_up() function's use of a JavaThreadIteratorWithHandle 4476 // would be a problem except set_vm_exited() has remembered the 4477 // shutdown thread which is granted a policy exception. 4478 #if defined(COMPILER2) && !defined(PRODUCT) 4479 IdealGraphPrinter::clean_up(); 4480 #endif 4481 4482 notify_vm_shutdown(); 4483 4484 // exit_globals() will delete tty 4485 exit_globals(); 4486 4487 // Deleting the shutdown thread here is safe. See comment on 4488 // wait_until_not_protected() above. 4489 delete thread; 4490 4491 #if INCLUDE_JVMCI 4492 if (JVMCICounterSize > 0) { 4493 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4494 } 4495 #endif 4496 4497 LogConfiguration::finalize(); 4498 4499 return true; 4500 } 4501 4502 4503 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4504 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4505 return is_supported_jni_version(version); 4506 } 4507 4508 4509 jboolean Threads::is_supported_jni_version(jint version) { 4510 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4511 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4512 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4513 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4514 if (version == JNI_VERSION_9) return JNI_TRUE; 4515 if (version == JNI_VERSION_10) return JNI_TRUE; 4516 return JNI_FALSE; 4517 } 4518 4519 4520 void Threads::add(JavaThread* p, bool force_daemon) { 4521 // The threads lock must be owned at this point 4522 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4523 4524 BarrierSet::barrier_set()->on_thread_attach(p); 4525 4526 // Once a JavaThread is added to the Threads list, smr_delete() has 4527 // to be used to delete it. Otherwise we can just delete it directly. 4528 p->set_on_thread_list(); 4529 4530 _number_of_threads++; 4531 oop threadObj = p->threadObj(); 4532 bool daemon = true; 4533 // Bootstrapping problem: threadObj can be null for initial 4534 // JavaThread (or for threads attached via JNI) 4535 if ((!force_daemon) && !is_daemon((threadObj))) { 4536 _number_of_non_daemon_threads++; 4537 daemon = false; 4538 } 4539 4540 ThreadService::add_thread(p, daemon); 4541 4542 // Maintain fast thread list 4543 ThreadsSMRSupport::add_thread(p); 4544 4545 // Possible GC point. 4546 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4547 } 4548 4549 void Threads::remove(JavaThread* p, bool is_daemon) { 4550 4551 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4552 ObjectSynchronizer::om_flush(p); 4553 4554 // Extra scope needed for Thread_lock, so we can check 4555 // that we do not remove thread without safepoint code notice 4556 { MonitorLocker ml(Threads_lock); 4557 4558 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4559 4560 // Maintain fast thread list 4561 ThreadsSMRSupport::remove_thread(p); 4562 4563 _number_of_threads--; 4564 if (!is_daemon) { 4565 _number_of_non_daemon_threads--; 4566 4567 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4568 // on destroy_vm will wake up. 4569 if (number_of_non_daemon_threads() == 1) { 4570 ml.notify_all(); 4571 } 4572 } 4573 ThreadService::remove_thread(p, is_daemon); 4574 4575 // Make sure that safepoint code disregard this thread. This is needed since 4576 // the thread might mess around with locks after this point. This can cause it 4577 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4578 // of this thread since it is removed from the queue. 4579 p->set_terminated_value(); 4580 } // unlock Threads_lock 4581 4582 // Since Events::log uses a lock, we grab it outside the Threads_lock 4583 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4584 } 4585 4586 // Operations on the Threads list for GC. These are not explicitly locked, 4587 // but the garbage collector must provide a safe context for them to run. 4588 // In particular, these things should never be called when the Threads_lock 4589 // is held by some other thread. (Note: the Safepoint abstraction also 4590 // uses the Threads_lock to guarantee this property. It also makes sure that 4591 // all threads gets blocked when exiting or starting). 4592 4593 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4594 ALL_JAVA_THREADS(p) { 4595 p->oops_do(f, cf); 4596 } 4597 VMThread::vm_thread()->oops_do(f, cf); 4598 } 4599 4600 void Threads::change_thread_claim_token() { 4601 if (++_thread_claim_token == 0) { 4602 // On overflow of the token counter, there is a risk of future 4603 // collisions between a new global token value and a stale token 4604 // for a thread, because not all iterations visit all threads. 4605 // (Though it's pretty much a theoretical concern for non-trivial 4606 // token counter sizes.) To deal with the possibility, reset all 4607 // the thread tokens to zero on global token overflow. 4608 struct ResetClaims : public ThreadClosure { 4609 virtual void do_thread(Thread* t) { 4610 t->claim_threads_do(false, 0); 4611 } 4612 } reset_claims; 4613 Threads::threads_do(&reset_claims); 4614 // On overflow, update the global token to non-zero, to 4615 // avoid the special "never claimed" initial thread value. 4616 _thread_claim_token = 1; 4617 } 4618 } 4619 4620 #ifdef ASSERT 4621 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4622 const uintx token = t->threads_do_token(); 4623 assert(token == expected, 4624 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4625 UINTX_FORMAT, kind, p2i(t), token, expected); 4626 } 4627 4628 void Threads::assert_all_threads_claimed() { 4629 ALL_JAVA_THREADS(p) { 4630 assert_thread_claimed("Thread", p, _thread_claim_token); 4631 } 4632 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4633 } 4634 #endif // ASSERT 4635 4636 class ParallelOopsDoThreadClosure : public ThreadClosure { 4637 private: 4638 OopClosure* _f; 4639 CodeBlobClosure* _cf; 4640 public: 4641 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4642 void do_thread(Thread* t) { 4643 t->oops_do(_f, _cf); 4644 } 4645 }; 4646 4647 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4648 ParallelOopsDoThreadClosure tc(f, cf); 4649 possibly_parallel_threads_do(is_par, &tc); 4650 } 4651 4652 void Threads::nmethods_do(CodeBlobClosure* cf) { 4653 ALL_JAVA_THREADS(p) { 4654 // This is used by the code cache sweeper to mark nmethods that are active 4655 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4656 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4657 if(!p->is_Code_cache_sweeper_thread()) { 4658 p->nmethods_do(cf); 4659 } 4660 } 4661 } 4662 4663 void Threads::metadata_do(MetadataClosure* f) { 4664 ALL_JAVA_THREADS(p) { 4665 p->metadata_do(f); 4666 } 4667 } 4668 4669 class ThreadHandlesClosure : public ThreadClosure { 4670 void (*_f)(Metadata*); 4671 public: 4672 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4673 virtual void do_thread(Thread* thread) { 4674 thread->metadata_handles_do(_f); 4675 } 4676 }; 4677 4678 void Threads::metadata_handles_do(void f(Metadata*)) { 4679 // Only walk the Handles in Thread. 4680 ThreadHandlesClosure handles_closure(f); 4681 threads_do(&handles_closure); 4682 } 4683 4684 // Get count Java threads that are waiting to enter the specified monitor. 4685 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4686 int count, 4687 address monitor) { 4688 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4689 4690 int i = 0; 4691 DO_JAVA_THREADS(t_list, p) { 4692 if (!p->can_call_java()) continue; 4693 4694 address pending = (address)p->current_pending_monitor(); 4695 if (pending == monitor) { // found a match 4696 if (i < count) result->append(p); // save the first count matches 4697 i++; 4698 } 4699 } 4700 4701 return result; 4702 } 4703 4704 4705 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4706 address owner) { 4707 // NULL owner means not locked so we can skip the search 4708 if (owner == NULL) return NULL; 4709 4710 DO_JAVA_THREADS(t_list, p) { 4711 // first, see if owner is the address of a Java thread 4712 if (owner == (address)p) return p; 4713 } 4714 4715 // Cannot assert on lack of success here since this function may be 4716 // used by code that is trying to report useful problem information 4717 // like deadlock detection. 4718 if (UseHeavyMonitors) return NULL; 4719 4720 // If we didn't find a matching Java thread and we didn't force use of 4721 // heavyweight monitors, then the owner is the stack address of the 4722 // Lock Word in the owning Java thread's stack. 4723 // 4724 JavaThread* the_owner = NULL; 4725 DO_JAVA_THREADS(t_list, q) { 4726 if (q->is_lock_owned(owner)) { 4727 the_owner = q; 4728 break; 4729 } 4730 } 4731 4732 // cannot assert on lack of success here; see above comment 4733 return the_owner; 4734 } 4735 4736 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4737 void Threads::print_on(outputStream* st, bool print_stacks, 4738 bool internal_format, bool print_concurrent_locks, 4739 bool print_extended_info) { 4740 char buf[32]; 4741 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4742 4743 st->print_cr("Full thread dump %s (%s %s):", 4744 VM_Version::vm_name(), 4745 VM_Version::vm_release(), 4746 VM_Version::vm_info_string()); 4747 st->cr(); 4748 4749 #if INCLUDE_SERVICES 4750 // Dump concurrent locks 4751 ConcurrentLocksDump concurrent_locks; 4752 if (print_concurrent_locks) { 4753 concurrent_locks.dump_at_safepoint(); 4754 } 4755 #endif // INCLUDE_SERVICES 4756 4757 ThreadsSMRSupport::print_info_on(st); 4758 st->cr(); 4759 4760 ALL_JAVA_THREADS(p) { 4761 ResourceMark rm; 4762 p->print_on(st, print_extended_info); 4763 if (print_stacks) { 4764 if (internal_format) { 4765 p->trace_stack(); 4766 } else { 4767 p->print_stack_on(st); 4768 } 4769 } 4770 st->cr(); 4771 #if INCLUDE_SERVICES 4772 if (print_concurrent_locks) { 4773 concurrent_locks.print_locks_on(p, st); 4774 } 4775 #endif // INCLUDE_SERVICES 4776 } 4777 4778 VMThread::vm_thread()->print_on(st); 4779 st->cr(); 4780 Universe::heap()->print_gc_threads_on(st); 4781 WatcherThread* wt = WatcherThread::watcher_thread(); 4782 if (wt != NULL) { 4783 wt->print_on(st); 4784 st->cr(); 4785 } 4786 4787 st->flush(); 4788 } 4789 4790 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4791 int buflen, bool* found_current) { 4792 if (this_thread != NULL) { 4793 bool is_current = (current == this_thread); 4794 *found_current = *found_current || is_current; 4795 st->print("%s", is_current ? "=>" : " "); 4796 4797 st->print(PTR_FORMAT, p2i(this_thread)); 4798 st->print(" "); 4799 this_thread->print_on_error(st, buf, buflen); 4800 st->cr(); 4801 } 4802 } 4803 4804 class PrintOnErrorClosure : public ThreadClosure { 4805 outputStream* _st; 4806 Thread* _current; 4807 char* _buf; 4808 int _buflen; 4809 bool* _found_current; 4810 public: 4811 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4812 int buflen, bool* found_current) : 4813 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4814 4815 virtual void do_thread(Thread* thread) { 4816 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4817 } 4818 }; 4819 4820 // Threads::print_on_error() is called by fatal error handler. It's possible 4821 // that VM is not at safepoint and/or current thread is inside signal handler. 4822 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4823 // memory (even in resource area), it might deadlock the error handler. 4824 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4825 int buflen) { 4826 ThreadsSMRSupport::print_info_on(st); 4827 st->cr(); 4828 4829 bool found_current = false; 4830 st->print_cr("Java Threads: ( => current thread )"); 4831 ALL_JAVA_THREADS(thread) { 4832 print_on_error(thread, st, current, buf, buflen, &found_current); 4833 } 4834 st->cr(); 4835 4836 st->print_cr("Other Threads:"); 4837 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4838 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4839 4840 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4841 Universe::heap()->gc_threads_do(&print_closure); 4842 4843 if (!found_current) { 4844 st->cr(); 4845 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4846 current->print_on_error(st, buf, buflen); 4847 st->cr(); 4848 } 4849 st->cr(); 4850 4851 st->print_cr("Threads with active compile tasks:"); 4852 print_threads_compiling(st, buf, buflen); 4853 } 4854 4855 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4856 ALL_JAVA_THREADS(thread) { 4857 if (thread->is_Compiler_thread()) { 4858 CompilerThread* ct = (CompilerThread*) thread; 4859 4860 // Keep task in local variable for NULL check. 4861 // ct->_task might be set to NULL by concurring compiler thread 4862 // because it completed the compilation. The task is never freed, 4863 // though, just returned to a free list. 4864 CompileTask* task = ct->task(); 4865 if (task != NULL) { 4866 thread->print_name_on_error(st, buf, buflen); 4867 st->print(" "); 4868 task->print(st, NULL, short_form, true); 4869 } 4870 } 4871 } 4872 } 4873 4874 4875 // Internal SpinLock and Mutex 4876 // Based on ParkEvent 4877 4878 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4879 // 4880 // We employ SpinLocks _only for low-contention, fixed-length 4881 // short-duration critical sections where we're concerned 4882 // about native mutex_t or HotSpot Mutex:: latency. 4883 // The mux construct provides a spin-then-block mutual exclusion 4884 // mechanism. 4885 // 4886 // Testing has shown that contention on the ListLock guarding gFreeList 4887 // is common. If we implement ListLock as a simple SpinLock it's common 4888 // for the JVM to devolve to yielding with little progress. This is true 4889 // despite the fact that the critical sections protected by ListLock are 4890 // extremely short. 4891 // 4892 // TODO-FIXME: ListLock should be of type SpinLock. 4893 // We should make this a 1st-class type, integrated into the lock 4894 // hierarchy as leaf-locks. Critically, the SpinLock structure 4895 // should have sufficient padding to avoid false-sharing and excessive 4896 // cache-coherency traffic. 4897 4898 4899 typedef volatile int SpinLockT; 4900 4901 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4902 if (Atomic::cmpxchg(adr, 0, 1) == 0) { 4903 return; // normal fast-path return 4904 } 4905 4906 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4907 int ctr = 0; 4908 int Yields = 0; 4909 for (;;) { 4910 while (*adr != 0) { 4911 ++ctr; 4912 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4913 if (Yields > 5) { 4914 os::naked_short_sleep(1); 4915 } else { 4916 os::naked_yield(); 4917 ++Yields; 4918 } 4919 } else { 4920 SpinPause(); 4921 } 4922 } 4923 if (Atomic::cmpxchg(adr, 0, 1) == 0) return; 4924 } 4925 } 4926 4927 void Thread::SpinRelease(volatile int * adr) { 4928 assert(*adr != 0, "invariant"); 4929 OrderAccess::fence(); // guarantee at least release consistency. 4930 // Roach-motel semantics. 4931 // It's safe if subsequent LDs and STs float "up" into the critical section, 4932 // but prior LDs and STs within the critical section can't be allowed 4933 // to reorder or float past the ST that releases the lock. 4934 // Loads and stores in the critical section - which appear in program 4935 // order before the store that releases the lock - must also appear 4936 // before the store that releases the lock in memory visibility order. 4937 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4938 // the ST of 0 into the lock-word which releases the lock, so fence 4939 // more than covers this on all platforms. 4940 *adr = 0; 4941 } 4942 4943 // muxAcquire and muxRelease: 4944 // 4945 // * muxAcquire and muxRelease support a single-word lock-word construct. 4946 // The LSB of the word is set IFF the lock is held. 4947 // The remainder of the word points to the head of a singly-linked list 4948 // of threads blocked on the lock. 4949 // 4950 // * The current implementation of muxAcquire-muxRelease uses its own 4951 // dedicated Thread._MuxEvent instance. If we're interested in 4952 // minimizing the peak number of extant ParkEvent instances then 4953 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4954 // as certain invariants were satisfied. Specifically, care would need 4955 // to be taken with regards to consuming unpark() "permits". 4956 // A safe rule of thumb is that a thread would never call muxAcquire() 4957 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4958 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4959 // consume an unpark() permit intended for monitorenter, for instance. 4960 // One way around this would be to widen the restricted-range semaphore 4961 // implemented in park(). Another alternative would be to provide 4962 // multiple instances of the PlatformEvent() for each thread. One 4963 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4964 // 4965 // * Usage: 4966 // -- Only as leaf locks 4967 // -- for short-term locking only as muxAcquire does not perform 4968 // thread state transitions. 4969 // 4970 // Alternatives: 4971 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4972 // but with parking or spin-then-park instead of pure spinning. 4973 // * Use Taura-Oyama-Yonenzawa locks. 4974 // * It's possible to construct a 1-0 lock if we encode the lockword as 4975 // (List,LockByte). Acquire will CAS the full lockword while Release 4976 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4977 // acquiring threads use timers (ParkTimed) to detect and recover from 4978 // the stranding window. Thread/Node structures must be aligned on 256-byte 4979 // boundaries by using placement-new. 4980 // * Augment MCS with advisory back-link fields maintained with CAS(). 4981 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4982 // The validity of the backlinks must be ratified before we trust the value. 4983 // If the backlinks are invalid the exiting thread must back-track through the 4984 // the forward links, which are always trustworthy. 4985 // * Add a successor indication. The LockWord is currently encoded as 4986 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4987 // to provide the usual futile-wakeup optimization. 4988 // See RTStt for details. 4989 // 4990 4991 4992 const intptr_t LOCKBIT = 1; 4993 4994 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4995 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT); 4996 if (w == 0) return; 4997 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4998 return; 4999 } 5000 5001 ParkEvent * const Self = Thread::current()->_MuxEvent; 5002 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 5003 for (;;) { 5004 int its = (os::is_MP() ? 100 : 0) + 1; 5005 5006 // Optional spin phase: spin-then-park strategy 5007 while (--its >= 0) { 5008 w = *Lock; 5009 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5010 return; 5011 } 5012 } 5013 5014 Self->reset(); 5015 Self->OnList = intptr_t(Lock); 5016 // The following fence() isn't _strictly necessary as the subsequent 5017 // CAS() both serializes execution and ratifies the fetched *Lock value. 5018 OrderAccess::fence(); 5019 for (;;) { 5020 w = *Lock; 5021 if ((w & LOCKBIT) == 0) { 5022 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5023 Self->OnList = 0; // hygiene - allows stronger asserts 5024 return; 5025 } 5026 continue; // Interference -- *Lock changed -- Just retry 5027 } 5028 assert(w & LOCKBIT, "invariant"); 5029 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5030 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break; 5031 } 5032 5033 while (Self->OnList != 0) { 5034 Self->park(); 5035 } 5036 } 5037 } 5038 5039 // Release() must extract a successor from the list and then wake that thread. 5040 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5041 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5042 // Release() would : 5043 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5044 // (B) Extract a successor from the private list "in-hand" 5045 // (C) attempt to CAS() the residual back into *Lock over null. 5046 // If there were any newly arrived threads and the CAS() would fail. 5047 // In that case Release() would detach the RATs, re-merge the list in-hand 5048 // with the RATs and repeat as needed. Alternately, Release() might 5049 // detach and extract a successor, but then pass the residual list to the wakee. 5050 // The wakee would be responsible for reattaching and remerging before it 5051 // competed for the lock. 5052 // 5053 // Both "pop" and DMR are immune from ABA corruption -- there can be 5054 // multiple concurrent pushers, but only one popper or detacher. 5055 // This implementation pops from the head of the list. This is unfair, 5056 // but tends to provide excellent throughput as hot threads remain hot. 5057 // (We wake recently run threads first). 5058 // 5059 // All paths through muxRelease() will execute a CAS. 5060 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5061 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5062 // executed within the critical section are complete and globally visible before the 5063 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5064 void Thread::muxRelease(volatile intptr_t * Lock) { 5065 for (;;) { 5066 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0); 5067 assert(w & LOCKBIT, "invariant"); 5068 if (w == LOCKBIT) return; 5069 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5070 assert(List != NULL, "invariant"); 5071 assert(List->OnList == intptr_t(Lock), "invariant"); 5072 ParkEvent * const nxt = List->ListNext; 5073 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5074 5075 // The following CAS() releases the lock and pops the head element. 5076 // The CAS() also ratifies the previously fetched lock-word value. 5077 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) { 5078 continue; 5079 } 5080 List->OnList = 0; 5081 OrderAccess::fence(); 5082 List->unpark(); 5083 return; 5084 } 5085 } 5086 5087 5088 void Threads::verify() { 5089 ALL_JAVA_THREADS(p) { 5090 p->verify(); 5091 } 5092 VMThread* thread = VMThread::vm_thread(); 5093 if (thread != NULL) thread->verify(); 5094 }