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 // Set stack limits after thread is initialized. 355 if (is_Java_thread()) { 356 ((JavaThread*) this)->set_stack_overflow_limit(); 357 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 358 } 359 } 360 361 #if INCLUDE_NMT 362 void Thread::register_thread_stack_with_NMT() { 363 MemTracker::record_thread_stack(stack_end(), stack_size()); 364 } 365 #endif // INCLUDE_NMT 366 367 void Thread::call_run() { 368 DEBUG_ONLY(_run_state = CALL_RUN;) 369 370 // At this point, Thread object should be fully initialized and 371 // Thread::current() should be set. 372 373 assert(Thread::current_or_null() != NULL, "current thread is unset"); 374 assert(Thread::current_or_null() == this, "current thread is wrong"); 375 376 // Perform common initialization actions 377 378 register_thread_stack_with_NMT(); 379 380 JFR_ONLY(Jfr::on_thread_start(this);) 381 382 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 383 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 384 os::current_thread_id(), p2i(stack_end()), 385 p2i(stack_base()), stack_size()/1024); 386 387 // Perform <ChildClass> initialization actions 388 DEBUG_ONLY(_run_state = PRE_RUN;) 389 this->pre_run(); 390 391 // Invoke <ChildClass>::run() 392 DEBUG_ONLY(_run_state = RUN;) 393 this->run(); 394 // Returned from <ChildClass>::run(). Thread finished. 395 396 // Perform common tear-down actions 397 398 assert(Thread::current_or_null() != NULL, "current thread is unset"); 399 assert(Thread::current_or_null() == this, "current thread is wrong"); 400 401 // Perform <ChildClass> tear-down actions 402 DEBUG_ONLY(_run_state = POST_RUN;) 403 this->post_run(); 404 405 // Note: at this point the thread object may already have deleted itself, 406 // so from here on do not dereference *this*. Not all thread types currently 407 // delete themselves when they terminate. But no thread should ever be deleted 408 // asynchronously with respect to its termination - that is what _run_state can 409 // be used to check. 410 411 assert(Thread::current_or_null() == NULL, "current thread still present"); 412 } 413 414 Thread::~Thread() { 415 416 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 417 // get started due to errors etc. Any active thread should at least reach post_run 418 // before it is deleted (usually in post_run()). 419 assert(_run_state == PRE_CALL_RUN || 420 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 421 "_run_state=%d", (int)_run_state); 422 423 // Notify the barrier set that a thread is being destroyed. Note that a barrier 424 // set might not be available if we encountered errors during bootstrapping. 425 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 426 if (barrier_set != NULL) { 427 barrier_set->on_thread_destroy(this); 428 } 429 430 // stack_base can be NULL if the thread is never started or exited before 431 // record_stack_base_and_size called. Although, we would like to ensure 432 // that all started threads do call record_stack_base_and_size(), there is 433 // not proper way to enforce that. 434 #if INCLUDE_NMT 435 if (_stack_base != NULL) { 436 MemTracker::release_thread_stack(stack_end(), stack_size()); 437 #ifdef ASSERT 438 set_stack_base(NULL); 439 #endif 440 } 441 #endif // INCLUDE_NMT 442 443 // deallocate data structures 444 delete resource_area(); 445 // since the handle marks are using the handle area, we have to deallocated the root 446 // handle mark before deallocating the thread's handle area, 447 assert(last_handle_mark() != NULL, "check we have an element"); 448 delete last_handle_mark(); 449 assert(last_handle_mark() == NULL, "check we have reached the end"); 450 451 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 452 // We NULL out the fields for good hygiene. 453 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 454 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 455 456 delete handle_area(); 457 delete metadata_handles(); 458 459 // SR_handler uses this as a termination indicator - 460 // needs to happen before os::free_thread() 461 delete _SR_lock; 462 _SR_lock = NULL; 463 464 // osthread() can be NULL, if creation of thread failed. 465 if (osthread() != NULL) os::free_thread(osthread()); 466 467 // Clear Thread::current if thread is deleting itself and it has not 468 // already been done. This must be done before the memory is deallocated. 469 // Needed to ensure JNI correctly detects non-attached threads. 470 if (this == Thread::current_or_null()) { 471 Thread::clear_thread_current(); 472 } 473 474 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 475 } 476 477 #ifdef ASSERT 478 // A JavaThread is considered "dangling" if it is not the current 479 // thread, has been added the Threads list, the system is not at a 480 // safepoint and the Thread is not "protected". 481 // 482 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 483 assert(!thread->is_Java_thread() || Thread::current() == thread || 484 !((JavaThread *) thread)->on_thread_list() || 485 SafepointSynchronize::is_at_safepoint() || 486 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 487 "possibility of dangling Thread pointer"); 488 } 489 #endif 490 491 ThreadPriority Thread::get_priority(const Thread* const thread) { 492 ThreadPriority priority; 493 // Can return an error! 494 (void)os::get_priority(thread, priority); 495 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 496 return priority; 497 } 498 499 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 500 debug_only(check_for_dangling_thread_pointer(thread);) 501 // Can return an error! 502 (void)os::set_priority(thread, priority); 503 } 504 505 506 void Thread::start(Thread* thread) { 507 // Start is different from resume in that its safety is guaranteed by context or 508 // being called from a Java method synchronized on the Thread object. 509 if (!DisableStartThread) { 510 if (thread->is_Java_thread()) { 511 // Initialize the thread state to RUNNABLE before starting this thread. 512 // Can not set it after the thread started because we do not know the 513 // exact thread state at that time. It could be in MONITOR_WAIT or 514 // in SLEEPING or some other state. 515 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 516 java_lang_Thread::RUNNABLE); 517 } 518 os::start_thread(thread); 519 } 520 } 521 522 class InstallAsyncExceptionClosure : public HandshakeClosure { 523 Handle _throwable; // The Throwable thrown at the target Thread 524 public: 525 InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {} 526 527 void do_thread(Thread* thr) { 528 JavaThread* target = (JavaThread*)thr; 529 // Note that this now allows multiple ThreadDeath exceptions to be 530 // thrown at a thread. 531 // The target thread has run and has not exited yet. 532 target->send_thread_stop(_throwable()); 533 } 534 }; 535 536 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 537 Handle throwable(Thread::current(), java_throwable); 538 JavaThread* target = java_lang_Thread::thread(java_thread); 539 InstallAsyncExceptionClosure vm_stop(throwable); 540 Handshake::execute(&vm_stop, target); 541 } 542 543 544 // Check if an external suspend request has completed (or has been 545 // cancelled). Returns true if the thread is externally suspended and 546 // false otherwise. 547 // 548 // The bits parameter returns information about the code path through 549 // the routine. Useful for debugging: 550 // 551 // set in is_ext_suspend_completed(): 552 // 0x00000001 - routine was entered 553 // 0x00000010 - routine return false at end 554 // 0x00000100 - thread exited (return false) 555 // 0x00000200 - suspend request cancelled (return false) 556 // 0x00000400 - thread suspended (return true) 557 // 0x00001000 - thread is in a suspend equivalent state (return true) 558 // 0x00002000 - thread is native and walkable (return true) 559 // 0x00004000 - thread is native_trans and walkable (needed retry) 560 // 561 // set in wait_for_ext_suspend_completion(): 562 // 0x00010000 - routine was entered 563 // 0x00020000 - suspend request cancelled before loop (return false) 564 // 0x00040000 - thread suspended before loop (return true) 565 // 0x00080000 - suspend request cancelled in loop (return false) 566 // 0x00100000 - thread suspended in loop (return true) 567 // 0x00200000 - suspend not completed during retry loop (return false) 568 569 // Helper class for tracing suspend wait debug bits. 570 // 571 // 0x00000100 indicates that the target thread exited before it could 572 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 573 // 0x00080000 each indicate a cancelled suspend request so they don't 574 // count as wait failures either. 575 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 576 577 class TraceSuspendDebugBits : public StackObj { 578 private: 579 JavaThread * jt; 580 bool is_wait; 581 bool called_by_wait; // meaningful when !is_wait 582 uint32_t * bits; 583 584 public: 585 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 586 uint32_t *_bits) { 587 jt = _jt; 588 is_wait = _is_wait; 589 called_by_wait = _called_by_wait; 590 bits = _bits; 591 } 592 593 ~TraceSuspendDebugBits() { 594 if (!is_wait) { 595 #if 1 596 // By default, don't trace bits for is_ext_suspend_completed() calls. 597 // That trace is very chatty. 598 return; 599 #else 600 if (!called_by_wait) { 601 // If tracing for is_ext_suspend_completed() is enabled, then only 602 // trace calls to it from wait_for_ext_suspend_completion() 603 return; 604 } 605 #endif 606 } 607 608 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 609 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 610 MutexLocker ml(Threads_lock); // needed for get_thread_name() 611 ResourceMark rm; 612 613 tty->print_cr( 614 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 615 jt->get_thread_name(), *bits); 616 617 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 618 } 619 } 620 } 621 }; 622 #undef DEBUG_FALSE_BITS 623 624 625 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 626 uint32_t *bits) { 627 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 628 629 bool did_trans_retry = false; // only do thread_in_native_trans retry once 630 bool do_trans_retry; // flag to force the retry 631 632 *bits |= 0x00000001; 633 634 do { 635 do_trans_retry = false; 636 637 if (is_exiting()) { 638 // Thread is in the process of exiting. This is always checked 639 // first to reduce the risk of dereferencing a freed JavaThread. 640 *bits |= 0x00000100; 641 return false; 642 } 643 644 if (!is_external_suspend()) { 645 // Suspend request is cancelled. This is always checked before 646 // is_ext_suspended() to reduce the risk of a rogue resume 647 // confusing the thread that made the suspend request. 648 *bits |= 0x00000200; 649 return false; 650 } 651 652 if (is_ext_suspended()) { 653 // thread is suspended 654 *bits |= 0x00000400; 655 return true; 656 } 657 658 // Now that we no longer do hard suspends of threads running 659 // native code, the target thread can be changing thread state 660 // while we are in this routine: 661 // 662 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 663 // 664 // We save a copy of the thread state as observed at this moment 665 // and make our decision about suspend completeness based on the 666 // copy. This closes the race where the thread state is seen as 667 // _thread_in_native_trans in the if-thread_blocked check, but is 668 // seen as _thread_blocked in if-thread_in_native_trans check. 669 JavaThreadState save_state = thread_state(); 670 671 if (save_state == _thread_blocked && is_suspend_equivalent()) { 672 // If the thread's state is _thread_blocked and this blocking 673 // condition is known to be equivalent to a suspend, then we can 674 // consider the thread to be externally suspended. This means that 675 // the code that sets _thread_blocked has been modified to do 676 // self-suspension if the blocking condition releases. We also 677 // used to check for CONDVAR_WAIT here, but that is now covered by 678 // the _thread_blocked with self-suspension check. 679 // 680 // Return true since we wouldn't be here unless there was still an 681 // external suspend request. 682 *bits |= 0x00001000; 683 return true; 684 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 685 // Threads running native code will self-suspend on native==>VM/Java 686 // transitions. If its stack is walkable (should always be the case 687 // unless this function is called before the actual java_suspend() 688 // call), then the wait is done. 689 *bits |= 0x00002000; 690 return true; 691 } else if (!called_by_wait && !did_trans_retry && 692 save_state == _thread_in_native_trans && 693 frame_anchor()->walkable()) { 694 // The thread is transitioning from thread_in_native to another 695 // thread state. check_safepoint_and_suspend_for_native_trans() 696 // will force the thread to self-suspend. If it hasn't gotten 697 // there yet we may have caught the thread in-between the native 698 // code check above and the self-suspend. Lucky us. If we were 699 // called by wait_for_ext_suspend_completion(), then it 700 // will be doing the retries so we don't have to. 701 // 702 // Since we use the saved thread state in the if-statement above, 703 // there is a chance that the thread has already transitioned to 704 // _thread_blocked by the time we get here. In that case, we will 705 // make a single unnecessary pass through the logic below. This 706 // doesn't hurt anything since we still do the trans retry. 707 708 *bits |= 0x00004000; 709 710 // Once the thread leaves thread_in_native_trans for another 711 // thread state, we break out of this retry loop. We shouldn't 712 // need this flag to prevent us from getting back here, but 713 // sometimes paranoia is good. 714 did_trans_retry = true; 715 716 // We wait for the thread to transition to a more usable state. 717 for (int i = 1; i <= SuspendRetryCount; i++) { 718 // We used to do an "os::yield_all(i)" call here with the intention 719 // that yielding would increase on each retry. However, the parameter 720 // is ignored on Linux which means the yield didn't scale up. Waiting 721 // on the SR_lock below provides a much more predictable scale up for 722 // the delay. It also provides a simple/direct point to check for any 723 // safepoint requests from the VMThread 724 725 // temporarily drops SR_lock while doing wait with safepoint check 726 // (if we're a JavaThread - the WatcherThread can also call this) 727 // and increase delay with each retry 728 if (Thread::current()->is_Java_thread()) { 729 SR_lock()->wait(i * delay); 730 } else { 731 SR_lock()->wait_without_safepoint_check(i * delay); 732 } 733 734 // check the actual thread state instead of what we saved above 735 if (thread_state() != _thread_in_native_trans) { 736 // the thread has transitioned to another thread state so 737 // try all the checks (except this one) one more time. 738 do_trans_retry = true; 739 break; 740 } 741 } // end retry loop 742 743 744 } 745 } while (do_trans_retry); 746 747 *bits |= 0x00000010; 748 return false; 749 } 750 751 // Wait for an external suspend request to complete (or be cancelled). 752 // Returns true if the thread is externally suspended and false otherwise. 753 // 754 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 755 uint32_t *bits) { 756 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 757 false /* !called_by_wait */, bits); 758 759 // local flag copies to minimize SR_lock hold time 760 bool is_suspended; 761 bool pending; 762 uint32_t reset_bits; 763 764 // set a marker so is_ext_suspend_completed() knows we are the caller 765 *bits |= 0x00010000; 766 767 // We use reset_bits to reinitialize the bits value at the top of 768 // each retry loop. This allows the caller to make use of any 769 // unused bits for their own marking purposes. 770 reset_bits = *bits; 771 772 { 773 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 774 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 775 delay, bits); 776 pending = is_external_suspend(); 777 } 778 // must release SR_lock to allow suspension to complete 779 780 if (!pending) { 781 // A cancelled suspend request is the only false return from 782 // is_ext_suspend_completed() that keeps us from entering the 783 // retry loop. 784 *bits |= 0x00020000; 785 return false; 786 } 787 788 if (is_suspended) { 789 *bits |= 0x00040000; 790 return true; 791 } 792 793 for (int i = 1; i <= retries; i++) { 794 *bits = reset_bits; // reinit to only track last retry 795 796 // We used to do an "os::yield_all(i)" call here with the intention 797 // that yielding would increase on each retry. However, the parameter 798 // is ignored on Linux which means the yield didn't scale up. Waiting 799 // on the SR_lock below provides a much more predictable scale up for 800 // the delay. It also provides a simple/direct point to check for any 801 // safepoint requests from the VMThread 802 803 { 804 Thread* t = Thread::current(); 805 MonitorLocker ml(SR_lock(), 806 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 807 // wait with safepoint check (if we're a JavaThread - the WatcherThread 808 // can also call this) and increase delay with each retry 809 ml.wait(i * delay); 810 811 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 812 delay, bits); 813 814 // It is possible for the external suspend request to be cancelled 815 // (by a resume) before the actual suspend operation is completed. 816 // Refresh our local copy to see if we still need to wait. 817 pending = is_external_suspend(); 818 } 819 820 if (!pending) { 821 // A cancelled suspend request is the only false return from 822 // is_ext_suspend_completed() that keeps us from staying in the 823 // retry loop. 824 *bits |= 0x00080000; 825 return false; 826 } 827 828 if (is_suspended) { 829 *bits |= 0x00100000; 830 return true; 831 } 832 } // end retry loop 833 834 // thread did not suspend after all our retries 835 *bits |= 0x00200000; 836 return false; 837 } 838 839 // Called from API entry points which perform stack walking. If the 840 // associated JavaThread is the current thread, then wait_for_suspend 841 // is not used. Otherwise, it determines if we should wait for the 842 // "other" thread to complete external suspension. (NOTE: in future 843 // releases the suspension mechanism should be reimplemented so this 844 // is not necessary.) 845 // 846 bool 847 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 848 if (this != JavaThread::current()) { 849 // "other" threads require special handling. 850 if (wait_for_suspend) { 851 // We are allowed to wait for the external suspend to complete 852 // so give the other thread a chance to get suspended. 853 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 854 SuspendRetryDelay, bits)) { 855 // Didn't make it so let the caller know. 856 return false; 857 } 858 } 859 // We aren't allowed to wait for the external suspend to complete 860 // so if the other thread isn't externally suspended we need to 861 // let the caller know. 862 else if (!is_ext_suspend_completed_with_lock(bits)) { 863 return false; 864 } 865 } 866 867 return true; 868 } 869 870 // GC Support 871 bool Thread::claim_par_threads_do(uintx claim_token) { 872 uintx token = _threads_do_token; 873 if (token != claim_token) { 874 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token); 875 if (res == token) { 876 return true; 877 } 878 guarantee(res == claim_token, "invariant"); 879 } 880 return false; 881 } 882 883 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 884 if (active_handles() != NULL) { 885 active_handles()->oops_do(f); 886 } 887 // Do oop for ThreadShadow 888 f->do_oop((oop*)&_pending_exception); 889 handle_area()->oops_do(f); 890 891 // We scan thread local monitor lists here, and the remaining global 892 // monitors in ObjectSynchronizer::oops_do(). 893 ObjectSynchronizer::thread_local_used_oops_do(this, f); 894 } 895 896 void Thread::metadata_handles_do(void f(Metadata*)) { 897 // Only walk the Handles in Thread. 898 if (metadata_handles() != NULL) { 899 for (int i = 0; i< metadata_handles()->length(); i++) { 900 f(metadata_handles()->at(i)); 901 } 902 } 903 } 904 905 void Thread::print_on(outputStream* st, bool print_extended_info) const { 906 // get_priority assumes osthread initialized 907 if (osthread() != NULL) { 908 int os_prio; 909 if (os::get_native_priority(this, &os_prio) == OS_OK) { 910 st->print("os_prio=%d ", os_prio); 911 } 912 913 st->print("cpu=%.2fms ", 914 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 915 ); 916 st->print("elapsed=%.2fs ", 917 _statistical_info.getElapsedTime() / 1000.0 918 ); 919 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 920 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 921 st->print("allocated=" SIZE_FORMAT "%s ", 922 byte_size_in_proper_unit(allocated_bytes), 923 proper_unit_for_byte_size(allocated_bytes) 924 ); 925 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 926 } 927 928 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 929 osthread()->print_on(st); 930 } 931 ThreadsSMRSupport::print_info_on(this, st); 932 st->print(" "); 933 debug_only(if (WizardMode) print_owned_locks_on(st);) 934 } 935 936 void Thread::print() const { print_on(tty); } 937 938 // Thread::print_on_error() is called by fatal error handler. Don't use 939 // any lock or allocate memory. 940 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 941 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 942 943 if (is_VM_thread()) { st->print("VMThread"); } 944 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 945 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 946 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 947 else { st->print("Thread"); } 948 949 if (is_Named_thread()) { 950 st->print(" \"%s\"", name()); 951 } 952 953 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 954 p2i(stack_end()), p2i(stack_base())); 955 956 if (osthread()) { 957 st->print(" [id=%d]", osthread()->thread_id()); 958 } 959 960 ThreadsSMRSupport::print_info_on(this, st); 961 } 962 963 void Thread::print_value_on(outputStream* st) const { 964 if (is_Named_thread()) { 965 st->print(" \"%s\" ", name()); 966 } 967 st->print(INTPTR_FORMAT, p2i(this)); // print address 968 } 969 970 #ifdef ASSERT 971 void Thread::print_owned_locks_on(outputStream* st) const { 972 Mutex* cur = _owned_locks; 973 if (cur == NULL) { 974 st->print(" (no locks) "); 975 } else { 976 st->print_cr(" Locks owned:"); 977 while (cur) { 978 cur->print_on(st); 979 cur = cur->next(); 980 } 981 } 982 } 983 984 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 985 void Thread::check_possible_safepoint() { 986 if (!is_Java_thread()) return; 987 988 if (_no_safepoint_count > 0) { 989 print_owned_locks(); 990 fatal("Possible safepoint reached by thread that does not allow it"); 991 } 992 #ifdef CHECK_UNHANDLED_OOPS 993 // Clear unhandled oops in JavaThreads so we get a crash right away. 994 clear_unhandled_oops(); 995 #endif // CHECK_UNHANDLED_OOPS 996 } 997 998 void Thread::check_for_valid_safepoint_state() { 999 if (!is_Java_thread()) return; 1000 1001 // Check NoSafepointVerifier, which is implied by locks taken that can be 1002 // shared with the VM thread. This makes sure that no locks with allow_vm_block 1003 // are held. 1004 check_possible_safepoint(); 1005 1006 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 1007 fatal("LEAF method calling lock?"); 1008 } 1009 1010 if (GCALotAtAllSafepoints) { 1011 // We could enter a safepoint here and thus have a gc 1012 InterfaceSupport::check_gc_alot(); 1013 } 1014 } 1015 #endif // ASSERT 1016 1017 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1018 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1019 // used for compilation in the future. If that change is made, the need for these methods 1020 // should be revisited, and they should be removed if possible. 1021 1022 bool Thread::is_lock_owned(address adr) const { 1023 return is_in_full_stack(adr); 1024 } 1025 1026 bool Thread::set_as_starting_thread() { 1027 assert(_starting_thread == NULL, "already initialized: " 1028 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1029 // NOTE: this must be called inside the main thread. 1030 DEBUG_ONLY(_starting_thread = this;) 1031 return os::create_main_thread((JavaThread*)this); 1032 } 1033 1034 static void initialize_class(Symbol* class_name, TRAPS) { 1035 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1036 InstanceKlass::cast(klass)->initialize(CHECK); 1037 } 1038 1039 1040 // Creates the initial ThreadGroup 1041 static Handle create_initial_thread_group(TRAPS) { 1042 Handle system_instance = JavaCalls::construct_new_instance( 1043 SystemDictionary::ThreadGroup_klass(), 1044 vmSymbols::void_method_signature(), 1045 CHECK_NH); 1046 Universe::set_system_thread_group(system_instance()); 1047 1048 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1049 Handle main_instance = JavaCalls::construct_new_instance( 1050 SystemDictionary::ThreadGroup_klass(), 1051 vmSymbols::threadgroup_string_void_signature(), 1052 system_instance, 1053 string, 1054 CHECK_NH); 1055 return main_instance; 1056 } 1057 1058 // Creates the initial Thread 1059 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1060 TRAPS) { 1061 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1062 assert(ik->is_initialized(), "must be"); 1063 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1064 1065 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1066 // constructor calls Thread.current(), which must be set here for the 1067 // initial thread. 1068 java_lang_Thread::set_thread(thread_oop(), thread); 1069 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1070 thread->set_threadObj(thread_oop()); 1071 1072 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1073 1074 JavaValue result(T_VOID); 1075 JavaCalls::call_special(&result, thread_oop, 1076 ik, 1077 vmSymbols::object_initializer_name(), 1078 vmSymbols::threadgroup_string_void_signature(), 1079 thread_group, 1080 string, 1081 CHECK_NULL); 1082 return thread_oop(); 1083 } 1084 1085 char java_runtime_name[128] = ""; 1086 char java_runtime_version[128] = ""; 1087 char java_runtime_vendor_version[128] = ""; 1088 char java_runtime_vendor_vm_bug_url[128] = ""; 1089 1090 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1091 static const char* get_java_runtime_name(TRAPS) { 1092 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1093 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1094 fieldDescriptor fd; 1095 bool found = k != NULL && 1096 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1097 vmSymbols::string_signature(), &fd); 1098 if (found) { 1099 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1100 if (name_oop == NULL) { 1101 return NULL; 1102 } 1103 const char* name = java_lang_String::as_utf8_string(name_oop, 1104 java_runtime_name, 1105 sizeof(java_runtime_name)); 1106 return name; 1107 } else { 1108 return NULL; 1109 } 1110 } 1111 1112 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1113 static const char* get_java_runtime_version(TRAPS) { 1114 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1115 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1116 fieldDescriptor fd; 1117 bool found = k != NULL && 1118 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1119 vmSymbols::string_signature(), &fd); 1120 if (found) { 1121 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1122 if (name_oop == NULL) { 1123 return NULL; 1124 } 1125 const char* name = java_lang_String::as_utf8_string(name_oop, 1126 java_runtime_version, 1127 sizeof(java_runtime_version)); 1128 return name; 1129 } else { 1130 return NULL; 1131 } 1132 } 1133 1134 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION 1135 static const char* get_java_runtime_vendor_version(TRAPS) { 1136 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1137 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1138 fieldDescriptor fd; 1139 bool found = k != NULL && 1140 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(), 1141 vmSymbols::string_signature(), &fd); 1142 if (found) { 1143 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1144 if (name_oop == NULL) { 1145 return NULL; 1146 } 1147 const char* name = java_lang_String::as_utf8_string(name_oop, 1148 java_runtime_vendor_version, 1149 sizeof(java_runtime_vendor_version)); 1150 return name; 1151 } else { 1152 return NULL; 1153 } 1154 } 1155 1156 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG 1157 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) { 1158 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1159 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1160 fieldDescriptor fd; 1161 bool found = k != NULL && 1162 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(), 1163 vmSymbols::string_signature(), &fd); 1164 if (found) { 1165 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1166 if (name_oop == NULL) { 1167 return NULL; 1168 } 1169 const char* name = java_lang_String::as_utf8_string(name_oop, 1170 java_runtime_vendor_vm_bug_url, 1171 sizeof(java_runtime_vendor_vm_bug_url)); 1172 return name; 1173 } else { 1174 return NULL; 1175 } 1176 } 1177 1178 // General purpose hook into Java code, run once when the VM is initialized. 1179 // The Java library method itself may be changed independently from the VM. 1180 static void call_postVMInitHook(TRAPS) { 1181 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1182 if (klass != NULL) { 1183 JavaValue result(T_VOID); 1184 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1185 vmSymbols::void_method_signature(), 1186 CHECK); 1187 } 1188 } 1189 1190 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1191 bool daemon, TRAPS) { 1192 assert(thread_group.not_null(), "thread group should be specified"); 1193 assert(threadObj() == NULL, "should only create Java thread object once"); 1194 1195 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1196 assert(ik->is_initialized(), "must be"); 1197 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1198 1199 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1200 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1201 // constructor calls Thread.current(), which must be set here. 1202 java_lang_Thread::set_thread(thread_oop(), this); 1203 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1204 set_threadObj(thread_oop()); 1205 1206 JavaValue result(T_VOID); 1207 if (thread_name != NULL) { 1208 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1209 // Thread gets assigned specified name and null target 1210 JavaCalls::call_special(&result, 1211 thread_oop, 1212 ik, 1213 vmSymbols::object_initializer_name(), 1214 vmSymbols::threadgroup_string_void_signature(), 1215 thread_group, 1216 name, 1217 THREAD); 1218 } else { 1219 // Thread gets assigned name "Thread-nnn" and null target 1220 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1221 JavaCalls::call_special(&result, 1222 thread_oop, 1223 ik, 1224 vmSymbols::object_initializer_name(), 1225 vmSymbols::threadgroup_runnable_void_signature(), 1226 thread_group, 1227 Handle(), 1228 THREAD); 1229 } 1230 1231 1232 if (daemon) { 1233 java_lang_Thread::set_daemon(thread_oop()); 1234 } 1235 1236 if (HAS_PENDING_EXCEPTION) { 1237 return; 1238 } 1239 1240 Klass* group = SystemDictionary::ThreadGroup_klass(); 1241 Handle threadObj(THREAD, this->threadObj()); 1242 1243 JavaCalls::call_special(&result, 1244 thread_group, 1245 group, 1246 vmSymbols::add_method_name(), 1247 vmSymbols::thread_void_signature(), 1248 threadObj, // Arg 1 1249 THREAD); 1250 } 1251 1252 // List of all NonJavaThreads and safe iteration over that list. 1253 1254 class NonJavaThread::List { 1255 public: 1256 NonJavaThread* volatile _head; 1257 SingleWriterSynchronizer _protect; 1258 1259 List() : _head(NULL), _protect() {} 1260 }; 1261 1262 NonJavaThread::List NonJavaThread::_the_list; 1263 1264 NonJavaThread::Iterator::Iterator() : 1265 _protect_enter(_the_list._protect.enter()), 1266 _current(Atomic::load_acquire(&_the_list._head)) 1267 {} 1268 1269 NonJavaThread::Iterator::~Iterator() { 1270 _the_list._protect.exit(_protect_enter); 1271 } 1272 1273 void NonJavaThread::Iterator::step() { 1274 assert(!end(), "precondition"); 1275 _current = Atomic::load_acquire(&_current->_next); 1276 } 1277 1278 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1279 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1280 } 1281 1282 NonJavaThread::~NonJavaThread() { } 1283 1284 void NonJavaThread::add_to_the_list() { 1285 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1286 // Initialize BarrierSet-related data before adding to list. 1287 BarrierSet::barrier_set()->on_thread_attach(this); 1288 Atomic::release_store(&_next, _the_list._head); 1289 Atomic::release_store(&_the_list._head, this); 1290 } 1291 1292 void NonJavaThread::remove_from_the_list() { 1293 { 1294 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1295 // Cleanup BarrierSet-related data before removing from list. 1296 BarrierSet::barrier_set()->on_thread_detach(this); 1297 NonJavaThread* volatile* p = &_the_list._head; 1298 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1299 if (t == this) { 1300 *p = _next; 1301 break; 1302 } 1303 } 1304 } 1305 // Wait for any in-progress iterators. Concurrent synchronize is not 1306 // allowed, so do it while holding a dedicated lock. Outside and distinct 1307 // from NJTList_lock in case an iteration attempts to lock it. 1308 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1309 _the_list._protect.synchronize(); 1310 _next = NULL; // Safe to drop the link now. 1311 } 1312 1313 void NonJavaThread::pre_run() { 1314 add_to_the_list(); 1315 1316 // This is slightly odd in that NamedThread is a subclass, but 1317 // in fact name() is defined in Thread 1318 assert(this->name() != NULL, "thread name was not set before it was started"); 1319 this->set_native_thread_name(this->name()); 1320 } 1321 1322 void NonJavaThread::post_run() { 1323 JFR_ONLY(Jfr::on_thread_exit(this);) 1324 remove_from_the_list(); 1325 // Ensure thread-local-storage is cleared before termination. 1326 Thread::clear_thread_current(); 1327 } 1328 1329 // NamedThread -- non-JavaThread subclasses with multiple 1330 // uniquely named instances should derive from this. 1331 NamedThread::NamedThread() : 1332 NonJavaThread(), 1333 _name(NULL), 1334 _processed_thread(NULL), 1335 _gc_id(GCId::undefined()) 1336 {} 1337 1338 NamedThread::~NamedThread() { 1339 FREE_C_HEAP_ARRAY(char, _name); 1340 } 1341 1342 void NamedThread::set_name(const char* format, ...) { 1343 guarantee(_name == NULL, "Only get to set name once."); 1344 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1345 va_list ap; 1346 va_start(ap, format); 1347 jio_vsnprintf(_name, max_name_len, format, ap); 1348 va_end(ap); 1349 } 1350 1351 void NamedThread::print_on(outputStream* st) const { 1352 st->print("\"%s\" ", name()); 1353 Thread::print_on(st); 1354 st->cr(); 1355 } 1356 1357 1358 // ======= WatcherThread ======== 1359 1360 // The watcher thread exists to simulate timer interrupts. It should 1361 // be replaced by an abstraction over whatever native support for 1362 // timer interrupts exists on the platform. 1363 1364 WatcherThread* WatcherThread::_watcher_thread = NULL; 1365 bool WatcherThread::_startable = false; 1366 volatile bool WatcherThread::_should_terminate = false; 1367 1368 WatcherThread::WatcherThread() : NonJavaThread() { 1369 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1370 if (os::create_thread(this, os::watcher_thread)) { 1371 _watcher_thread = this; 1372 1373 // Set the watcher thread to the highest OS priority which should not be 1374 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1375 // is created. The only normal thread using this priority is the reference 1376 // handler thread, which runs for very short intervals only. 1377 // If the VMThread's priority is not lower than the WatcherThread profiling 1378 // will be inaccurate. 1379 os::set_priority(this, MaxPriority); 1380 if (!DisableStartThread) { 1381 os::start_thread(this); 1382 } 1383 } 1384 } 1385 1386 int WatcherThread::sleep() const { 1387 // The WatcherThread does not participate in the safepoint protocol 1388 // for the PeriodicTask_lock because it is not a JavaThread. 1389 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1390 1391 if (_should_terminate) { 1392 // check for termination before we do any housekeeping or wait 1393 return 0; // we did not sleep. 1394 } 1395 1396 // remaining will be zero if there are no tasks, 1397 // causing the WatcherThread to sleep until a task is 1398 // enrolled 1399 int remaining = PeriodicTask::time_to_wait(); 1400 int time_slept = 0; 1401 1402 // we expect this to timeout - we only ever get unparked when 1403 // we should terminate or when a new task has been enrolled 1404 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1405 1406 jlong time_before_loop = os::javaTimeNanos(); 1407 1408 while (true) { 1409 bool timedout = ml.wait(remaining); 1410 jlong now = os::javaTimeNanos(); 1411 1412 if (remaining == 0) { 1413 // if we didn't have any tasks we could have waited for a long time 1414 // consider the time_slept zero and reset time_before_loop 1415 time_slept = 0; 1416 time_before_loop = now; 1417 } else { 1418 // need to recalculate since we might have new tasks in _tasks 1419 time_slept = (int) ((now - time_before_loop) / 1000000); 1420 } 1421 1422 // Change to task list or spurious wakeup of some kind 1423 if (timedout || _should_terminate) { 1424 break; 1425 } 1426 1427 remaining = PeriodicTask::time_to_wait(); 1428 if (remaining == 0) { 1429 // Last task was just disenrolled so loop around and wait until 1430 // another task gets enrolled 1431 continue; 1432 } 1433 1434 remaining -= time_slept; 1435 if (remaining <= 0) { 1436 break; 1437 } 1438 } 1439 1440 return time_slept; 1441 } 1442 1443 void WatcherThread::run() { 1444 assert(this == watcher_thread(), "just checking"); 1445 1446 this->set_active_handles(JNIHandleBlock::allocate_block()); 1447 while (true) { 1448 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1449 assert(watcher_thread() == this, "thread consistency check"); 1450 1451 // Calculate how long it'll be until the next PeriodicTask work 1452 // should be done, and sleep that amount of time. 1453 int time_waited = sleep(); 1454 1455 if (VMError::is_error_reported()) { 1456 // A fatal error has happened, the error handler(VMError::report_and_die) 1457 // should abort JVM after creating an error log file. However in some 1458 // rare cases, the error handler itself might deadlock. Here periodically 1459 // check for error reporting timeouts, and if it happens, just proceed to 1460 // abort the VM. 1461 1462 // This code is in WatcherThread because WatcherThread wakes up 1463 // periodically so the fatal error handler doesn't need to do anything; 1464 // also because the WatcherThread is less likely to crash than other 1465 // threads. 1466 1467 for (;;) { 1468 // Note: we use naked sleep in this loop because we want to avoid using 1469 // any kind of VM infrastructure which may be broken at this point. 1470 if (VMError::check_timeout()) { 1471 // We hit error reporting timeout. Error reporting was interrupted and 1472 // will be wrapping things up now (closing files etc). Give it some more 1473 // time, then quit the VM. 1474 os::naked_short_sleep(200); 1475 // Print a message to stderr. 1476 fdStream err(defaultStream::output_fd()); 1477 err.print_raw_cr("# [ timer expired, abort... ]"); 1478 // skip atexit/vm_exit/vm_abort hooks 1479 os::die(); 1480 } 1481 1482 // Wait a second, then recheck for timeout. 1483 os::naked_short_sleep(999); 1484 } 1485 } 1486 1487 if (_should_terminate) { 1488 // check for termination before posting the next tick 1489 break; 1490 } 1491 1492 PeriodicTask::real_time_tick(time_waited); 1493 } 1494 1495 // Signal that it is terminated 1496 { 1497 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1498 _watcher_thread = NULL; 1499 Terminator_lock->notify_all(); 1500 } 1501 } 1502 1503 void WatcherThread::start() { 1504 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1505 1506 if (watcher_thread() == NULL && _startable) { 1507 _should_terminate = false; 1508 // Create the single instance of WatcherThread 1509 new WatcherThread(); 1510 } 1511 } 1512 1513 void WatcherThread::make_startable() { 1514 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1515 _startable = true; 1516 } 1517 1518 void WatcherThread::stop() { 1519 { 1520 // Follow normal safepoint aware lock enter protocol since the 1521 // WatcherThread is stopped by another JavaThread. 1522 MutexLocker ml(PeriodicTask_lock); 1523 _should_terminate = true; 1524 1525 WatcherThread* watcher = watcher_thread(); 1526 if (watcher != NULL) { 1527 // unpark the WatcherThread so it can see that it should terminate 1528 watcher->unpark(); 1529 } 1530 } 1531 1532 MonitorLocker mu(Terminator_lock); 1533 1534 while (watcher_thread() != NULL) { 1535 // This wait should make safepoint checks, wait without a timeout, 1536 // and wait as a suspend-equivalent condition. 1537 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1538 } 1539 } 1540 1541 void WatcherThread::unpark() { 1542 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1543 PeriodicTask_lock->notify(); 1544 } 1545 1546 void WatcherThread::print_on(outputStream* st) const { 1547 st->print("\"%s\" ", name()); 1548 Thread::print_on(st); 1549 st->cr(); 1550 } 1551 1552 // ======= JavaThread ======== 1553 1554 #if INCLUDE_JVMCI 1555 1556 jlong* JavaThread::_jvmci_old_thread_counters; 1557 1558 bool jvmci_counters_include(JavaThread* thread) { 1559 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1560 } 1561 1562 void JavaThread::collect_counters(jlong* array, int length) { 1563 assert(length == JVMCICounterSize, "wrong value"); 1564 for (int i = 0; i < length; i++) { 1565 array[i] = _jvmci_old_thread_counters[i]; 1566 } 1567 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1568 if (jvmci_counters_include(tp)) { 1569 for (int i = 0; i < length; i++) { 1570 array[i] += tp->_jvmci_counters[i]; 1571 } 1572 } 1573 } 1574 } 1575 1576 // Attempt to enlarge the array for per thread counters. 1577 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1578 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1579 if (old_counters == NULL) { 1580 old_counters = new_counters; 1581 memset(old_counters, 0, sizeof(jlong) * new_size); 1582 } else { 1583 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1584 new_counters[i] = old_counters[i]; 1585 } 1586 if (new_size > current_size) { 1587 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1588 } 1589 FREE_C_HEAP_ARRAY(jlong, old_counters); 1590 } 1591 return new_counters; 1592 } 1593 1594 // Attempt to enlarge the array for per thread counters. 1595 void JavaThread::resize_counters(int current_size, int new_size) { 1596 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1597 } 1598 1599 class VM_JVMCIResizeCounters : public VM_Operation { 1600 private: 1601 int _new_size; 1602 1603 public: 1604 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { } 1605 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; } 1606 bool allow_nested_vm_operations() const { return true; } 1607 void doit() { 1608 // Resize the old thread counters array 1609 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size); 1610 JavaThread::_jvmci_old_thread_counters = new_counters; 1611 1612 // Now resize each threads array 1613 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1614 tp->resize_counters(JVMCICounterSize, _new_size); 1615 } 1616 JVMCICounterSize = _new_size; 1617 } 1618 }; 1619 1620 void JavaThread::resize_all_jvmci_counters(int new_size) { 1621 VM_JVMCIResizeCounters op(new_size); 1622 VMThread::execute(&op); 1623 } 1624 1625 #endif // INCLUDE_JVMCI 1626 1627 // A JavaThread is a normal Java thread 1628 1629 void JavaThread::initialize() { 1630 // Initialize fields 1631 1632 set_saved_exception_pc(NULL); 1633 set_threadObj(NULL); 1634 _anchor.clear(); 1635 set_entry_point(NULL); 1636 set_jni_functions(jni_functions()); 1637 set_callee_target(NULL); 1638 set_vm_result(NULL); 1639 set_vm_result_2(NULL); 1640 set_vframe_array_head(NULL); 1641 set_vframe_array_last(NULL); 1642 set_deferred_locals(NULL); 1643 set_deopt_mark(NULL); 1644 set_deopt_compiled_method(NULL); 1645 set_monitor_chunks(NULL); 1646 _on_thread_list = false; 1647 _thread_state = _thread_new; 1648 _terminated = _not_terminated; 1649 _array_for_gc = NULL; 1650 _suspend_equivalent = false; 1651 _in_deopt_handler = 0; 1652 _doing_unsafe_access = false; 1653 _stack_guard_state = stack_guard_unused; 1654 #if INCLUDE_JVMCI 1655 _pending_monitorenter = false; 1656 _pending_deoptimization = -1; 1657 _pending_failed_speculation = 0; 1658 _pending_transfer_to_interpreter = false; 1659 _in_retryable_allocation = false; 1660 _jvmci._alternate_call_target = NULL; 1661 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1662 _jvmci_counters = NULL; 1663 if (JVMCICounterSize > 0) { 1664 resize_counters(0, (int) JVMCICounterSize); 1665 } 1666 #endif // INCLUDE_JVMCI 1667 _reserved_stack_activation = NULL; // stack base not known yet 1668 set_exception_oop(oop()); 1669 _exception_pc = 0; 1670 _exception_handler_pc = 0; 1671 _is_method_handle_return = 0; 1672 _jvmti_thread_state= NULL; 1673 _should_post_on_exceptions_flag = JNI_FALSE; 1674 _interp_only_mode = 0; 1675 _special_runtime_exit_condition = _no_async_condition; 1676 _pending_async_exception = NULL; 1677 _thread_stat = NULL; 1678 _thread_stat = new ThreadStatistics(); 1679 _jni_active_critical = 0; 1680 _pending_jni_exception_check_fn = NULL; 1681 _do_not_unlock_if_synchronized = false; 1682 _cached_monitor_info = NULL; 1683 _parker = Parker::Allocate(this); 1684 _SleepEvent = ParkEvent::Allocate(this); 1685 // Setup safepoint state info for this thread 1686 ThreadSafepointState::create(this); 1687 _handshake.set_handshakee(this); 1688 1689 debug_only(_java_call_counter = 0); 1690 1691 // JVMTI PopFrame support 1692 _popframe_condition = popframe_inactive; 1693 _popframe_preserved_args = NULL; 1694 _popframe_preserved_args_size = 0; 1695 _frames_to_pop_failed_realloc = 0; 1696 1697 SafepointMechanism::initialize_header(this); 1698 1699 _class_to_be_initialized = NULL; 1700 1701 pd_initialize(); 1702 } 1703 1704 JavaThread::JavaThread(bool is_attaching_via_jni) : 1705 Thread() { 1706 initialize(); 1707 if (is_attaching_via_jni) { 1708 _jni_attach_state = _attaching_via_jni; 1709 } else { 1710 _jni_attach_state = _not_attaching_via_jni; 1711 } 1712 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1713 } 1714 1715 1716 // interrupt support 1717 1718 void JavaThread::interrupt() { 1719 debug_only(check_for_dangling_thread_pointer(this);) 1720 1721 // For Windows _interrupt_event 1722 osthread()->set_interrupted(true); 1723 1724 // For Thread.sleep 1725 _SleepEvent->unpark(); 1726 1727 // For JSR166 LockSupport.park 1728 parker()->unpark(); 1729 1730 // For ObjectMonitor and JvmtiRawMonitor 1731 _ParkEvent->unpark(); 1732 } 1733 1734 1735 bool JavaThread::is_interrupted(bool clear_interrupted) { 1736 debug_only(check_for_dangling_thread_pointer(this);) 1737 1738 if (threadObj() == NULL) { 1739 // If there is no j.l.Thread then it is impossible to have 1740 // been interrupted. We can find NULL during VM initialization 1741 // or when a JNI thread is still in the process of attaching. 1742 // In such cases this must be the current thread. 1743 assert(this == Thread::current(), "invariant"); 1744 return false; 1745 } 1746 1747 bool interrupted = java_lang_Thread::interrupted(threadObj()); 1748 1749 // NOTE that since there is no "lock" around the interrupt and 1750 // is_interrupted operations, there is the possibility that the 1751 // interrupted flag will be "false" but that the 1752 // low-level events will be in the signaled state. This is 1753 // intentional. The effect of this is that Object.wait() and 1754 // LockSupport.park() will appear to have a spurious wakeup, which 1755 // is allowed and not harmful, and the possibility is so rare that 1756 // it is not worth the added complexity to add yet another lock. 1757 // For the sleep event an explicit reset is performed on entry 1758 // to JavaThread::sleep, so there is no early return. It has also been 1759 // recommended not to put the interrupted flag into the "event" 1760 // structure because it hides the issue. 1761 // Also, because there is no lock, we must only clear the interrupt 1762 // state if we are going to report that we were interrupted; otherwise 1763 // an interrupt that happens just after we read the field would be lost. 1764 if (interrupted && clear_interrupted) { 1765 assert(this == Thread::current(), "only the current thread can clear"); 1766 java_lang_Thread::set_interrupted(threadObj(), false); 1767 osthread()->set_interrupted(false); 1768 } 1769 1770 return interrupted; 1771 } 1772 1773 bool JavaThread::reguard_stack(address cur_sp) { 1774 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1775 && _stack_guard_state != stack_guard_reserved_disabled) { 1776 return true; // Stack already guarded or guard pages not needed. 1777 } 1778 1779 if (register_stack_overflow()) { 1780 // For those architectures which have separate register and 1781 // memory stacks, we must check the register stack to see if 1782 // it has overflowed. 1783 return false; 1784 } 1785 1786 // Java code never executes within the yellow zone: the latter is only 1787 // there to provoke an exception during stack banging. If java code 1788 // is executing there, either StackShadowPages should be larger, or 1789 // some exception code in c1, c2 or the interpreter isn't unwinding 1790 // when it should. 1791 guarantee(cur_sp > stack_reserved_zone_base(), 1792 "not enough space to reguard - increase StackShadowPages"); 1793 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1794 enable_stack_yellow_reserved_zone(); 1795 if (reserved_stack_activation() != stack_base()) { 1796 set_reserved_stack_activation(stack_base()); 1797 } 1798 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1799 set_reserved_stack_activation(stack_base()); 1800 enable_stack_reserved_zone(); 1801 } 1802 return true; 1803 } 1804 1805 bool JavaThread::reguard_stack(void) { 1806 return reguard_stack(os::current_stack_pointer()); 1807 } 1808 1809 void JavaThread::block_if_vm_exited() { 1810 if (_terminated == _vm_exited) { 1811 // _vm_exited is set at safepoint, and Threads_lock is never released 1812 // we will block here forever. 1813 // Here we can be doing a jump from a safe state to an unsafe state without 1814 // proper transition, but it happens after the final safepoint has begun. 1815 set_thread_state(_thread_in_vm); 1816 Threads_lock->lock(); 1817 ShouldNotReachHere(); 1818 } 1819 } 1820 1821 1822 // Remove this ifdef when C1 is ported to the compiler interface. 1823 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1824 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1825 1826 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1827 Thread() { 1828 initialize(); 1829 _jni_attach_state = _not_attaching_via_jni; 1830 set_entry_point(entry_point); 1831 // Create the native thread itself. 1832 // %note runtime_23 1833 os::ThreadType thr_type = os::java_thread; 1834 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1835 os::java_thread; 1836 os::create_thread(this, thr_type, stack_sz); 1837 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1838 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1839 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1840 // the exception consists of creating the exception object & initializing it, initialization 1841 // will leave the VM via a JavaCall and then all locks must be unlocked). 1842 // 1843 // The thread is still suspended when we reach here. Thread must be explicit started 1844 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1845 // by calling Threads:add. The reason why this is not done here, is because the thread 1846 // object must be fully initialized (take a look at JVM_Start) 1847 } 1848 1849 JavaThread::~JavaThread() { 1850 1851 // JSR166 -- return the parker to the free list 1852 Parker::Release(_parker); 1853 _parker = NULL; 1854 1855 // Return the sleep event to the free list 1856 ParkEvent::Release(_SleepEvent); 1857 _SleepEvent = NULL; 1858 1859 // Free any remaining previous UnrollBlock 1860 vframeArray* old_array = vframe_array_last(); 1861 1862 if (old_array != NULL) { 1863 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1864 old_array->set_unroll_block(NULL); 1865 delete old_info; 1866 delete old_array; 1867 } 1868 1869 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1870 if (deferred != NULL) { 1871 // This can only happen if thread is destroyed before deoptimization occurs. 1872 assert(deferred->length() != 0, "empty array!"); 1873 do { 1874 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1875 deferred->remove_at(0); 1876 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1877 delete dlv; 1878 } while (deferred->length() != 0); 1879 delete deferred; 1880 } 1881 1882 // All Java related clean up happens in exit 1883 ThreadSafepointState::destroy(this); 1884 if (_thread_stat != NULL) delete _thread_stat; 1885 1886 #if INCLUDE_JVMCI 1887 if (JVMCICounterSize > 0) { 1888 if (jvmci_counters_include(this)) { 1889 for (int i = 0; i < JVMCICounterSize; i++) { 1890 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1891 } 1892 } 1893 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1894 } 1895 #endif // INCLUDE_JVMCI 1896 } 1897 1898 1899 // First JavaThread specific code executed by a new Java thread. 1900 void JavaThread::pre_run() { 1901 // empty - see comments in run() 1902 } 1903 1904 // The main routine called by a new Java thread. This isn't overridden 1905 // by subclasses, instead different subclasses define a different "entry_point" 1906 // which defines the actual logic for that kind of thread. 1907 void JavaThread::run() { 1908 // initialize thread-local alloc buffer related fields 1909 this->initialize_tlab(); 1910 1911 // Used to test validity of stack trace backs. 1912 // This can't be moved into pre_run() else we invalidate 1913 // the requirement that thread_main_inner is lower on 1914 // the stack. Consequently all the initialization logic 1915 // stays here in run() rather than pre_run(). 1916 this->record_base_of_stack_pointer(); 1917 1918 this->create_stack_guard_pages(); 1919 1920 this->cache_global_variables(); 1921 1922 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1923 // in the VM. Change thread state from _thread_new to _thread_in_vm 1924 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1925 // Before a thread is on the threads list it is always safe, so after leaving the 1926 // _thread_new we should emit a instruction barrier. The distance to modified code 1927 // from here is probably far enough, but this is consistent and safe. 1928 OrderAccess::cross_modify_fence(); 1929 1930 assert(JavaThread::current() == this, "sanity check"); 1931 assert(!Thread::current()->owns_locks(), "sanity check"); 1932 1933 DTRACE_THREAD_PROBE(start, this); 1934 1935 // This operation might block. We call that after all safepoint checks for a new thread has 1936 // been completed. 1937 this->set_active_handles(JNIHandleBlock::allocate_block()); 1938 1939 if (JvmtiExport::should_post_thread_life()) { 1940 JvmtiExport::post_thread_start(this); 1941 1942 } 1943 1944 // We call another function to do the rest so we are sure that the stack addresses used 1945 // from there will be lower than the stack base just computed. 1946 thread_main_inner(); 1947 } 1948 1949 void JavaThread::thread_main_inner() { 1950 assert(JavaThread::current() == this, "sanity check"); 1951 assert(this->threadObj() != NULL, "just checking"); 1952 1953 // Execute thread entry point unless this thread has a pending exception 1954 // or has been stopped before starting. 1955 // Note: Due to JVM_StopThread we can have pending exceptions already! 1956 if (!this->has_pending_exception() && 1957 !java_lang_Thread::is_stillborn(this->threadObj())) { 1958 { 1959 ResourceMark rm(this); 1960 this->set_native_thread_name(this->get_thread_name()); 1961 } 1962 HandleMark hm(this); 1963 this->entry_point()(this, this); 1964 } 1965 1966 DTRACE_THREAD_PROBE(stop, this); 1967 1968 // Cleanup is handled in post_run() 1969 } 1970 1971 // Shared teardown for all JavaThreads 1972 void JavaThread::post_run() { 1973 this->exit(false); 1974 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1975 // for any shared tear-down. 1976 this->smr_delete(); 1977 } 1978 1979 static void ensure_join(JavaThread* thread) { 1980 // We do not need to grab the Threads_lock, since we are operating on ourself. 1981 Handle threadObj(thread, thread->threadObj()); 1982 assert(threadObj.not_null(), "java thread object must exist"); 1983 ObjectLocker lock(threadObj, thread); 1984 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1985 thread->clear_pending_exception(); 1986 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1987 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1988 // Clear the native thread instance - this makes isAlive return false and allows the join() 1989 // to complete once we've done the notify_all below 1990 java_lang_Thread::set_thread(threadObj(), NULL); 1991 lock.notify_all(thread); 1992 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1993 thread->clear_pending_exception(); 1994 } 1995 1996 static bool is_daemon(oop threadObj) { 1997 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1998 } 1999 2000 // For any new cleanup additions, please check to see if they need to be applied to 2001 // cleanup_failed_attach_current_thread as well. 2002 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 2003 assert(this == JavaThread::current(), "thread consistency check"); 2004 2005 elapsedTimer _timer_exit_phase1; 2006 elapsedTimer _timer_exit_phase2; 2007 elapsedTimer _timer_exit_phase3; 2008 elapsedTimer _timer_exit_phase4; 2009 2010 if (log_is_enabled(Debug, os, thread, timer)) { 2011 _timer_exit_phase1.start(); 2012 } 2013 2014 HandleMark hm(this); 2015 Handle uncaught_exception(this, this->pending_exception()); 2016 this->clear_pending_exception(); 2017 Handle threadObj(this, this->threadObj()); 2018 assert(threadObj.not_null(), "Java thread object should be created"); 2019 2020 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 2021 { 2022 EXCEPTION_MARK; 2023 2024 CLEAR_PENDING_EXCEPTION; 2025 } 2026 if (!destroy_vm) { 2027 if (uncaught_exception.not_null()) { 2028 EXCEPTION_MARK; 2029 // Call method Thread.dispatchUncaughtException(). 2030 Klass* thread_klass = SystemDictionary::Thread_klass(); 2031 JavaValue result(T_VOID); 2032 JavaCalls::call_virtual(&result, 2033 threadObj, thread_klass, 2034 vmSymbols::dispatchUncaughtException_name(), 2035 vmSymbols::throwable_void_signature(), 2036 uncaught_exception, 2037 THREAD); 2038 if (HAS_PENDING_EXCEPTION) { 2039 ResourceMark rm(this); 2040 jio_fprintf(defaultStream::error_stream(), 2041 "\nException: %s thrown from the UncaughtExceptionHandler" 2042 " in thread \"%s\"\n", 2043 pending_exception()->klass()->external_name(), 2044 get_thread_name()); 2045 CLEAR_PENDING_EXCEPTION; 2046 } 2047 } 2048 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2049 2050 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2051 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2052 // is deprecated anyhow. 2053 if (!is_Compiler_thread()) { 2054 int count = 3; 2055 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2056 EXCEPTION_MARK; 2057 JavaValue result(T_VOID); 2058 Klass* thread_klass = SystemDictionary::Thread_klass(); 2059 JavaCalls::call_virtual(&result, 2060 threadObj, thread_klass, 2061 vmSymbols::exit_method_name(), 2062 vmSymbols::void_method_signature(), 2063 THREAD); 2064 CLEAR_PENDING_EXCEPTION; 2065 } 2066 } 2067 // notify JVMTI 2068 if (JvmtiExport::should_post_thread_life()) { 2069 JvmtiExport::post_thread_end(this); 2070 } 2071 2072 // We have notified the agents that we are exiting, before we go on, 2073 // we must check for a pending external suspend request and honor it 2074 // in order to not surprise the thread that made the suspend request. 2075 while (true) { 2076 { 2077 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2078 if (!is_external_suspend()) { 2079 set_terminated(_thread_exiting); 2080 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2081 break; 2082 } 2083 // Implied else: 2084 // Things get a little tricky here. We have a pending external 2085 // suspend request, but we are holding the SR_lock so we 2086 // can't just self-suspend. So we temporarily drop the lock 2087 // and then self-suspend. 2088 } 2089 2090 ThreadBlockInVM tbivm(this); 2091 java_suspend_self(); 2092 2093 // We're done with this suspend request, but we have to loop around 2094 // and check again. Eventually we will get SR_lock without a pending 2095 // external suspend request and will be able to mark ourselves as 2096 // exiting. 2097 } 2098 // no more external suspends are allowed at this point 2099 } else { 2100 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2101 // before_exit() has already posted JVMTI THREAD_END events 2102 } 2103 2104 if (log_is_enabled(Debug, os, thread, timer)) { 2105 _timer_exit_phase1.stop(); 2106 _timer_exit_phase2.start(); 2107 } 2108 2109 // Capture daemon status before the thread is marked as terminated. 2110 bool daemon = is_daemon(threadObj()); 2111 2112 // Notify waiters on thread object. This has to be done after exit() is called 2113 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2114 // group should have the destroyed bit set before waiters are notified). 2115 ensure_join(this); 2116 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2117 2118 if (log_is_enabled(Debug, os, thread, timer)) { 2119 _timer_exit_phase2.stop(); 2120 _timer_exit_phase3.start(); 2121 } 2122 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2123 // held by this thread must be released. The spec does not distinguish 2124 // between JNI-acquired and regular Java monitors. We can only see 2125 // regular Java monitors here if monitor enter-exit matching is broken. 2126 // 2127 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2128 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2129 if (exit_type == jni_detach) { 2130 // Sanity check even though JNI DetachCurrentThread() would have 2131 // returned JNI_ERR if there was a Java frame. JavaThread exit 2132 // should be done executing Java code by the time we get here. 2133 assert(!this->has_last_Java_frame(), 2134 "should not have a Java frame when detaching or exiting"); 2135 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2136 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2137 } 2138 2139 // These things needs to be done while we are still a Java Thread. Make sure that thread 2140 // is in a consistent state, in case GC happens 2141 JFR_ONLY(Jfr::on_thread_exit(this);) 2142 2143 if (active_handles() != NULL) { 2144 JNIHandleBlock* block = active_handles(); 2145 set_active_handles(NULL); 2146 JNIHandleBlock::release_block(block); 2147 } 2148 2149 if (free_handle_block() != NULL) { 2150 JNIHandleBlock* block = free_handle_block(); 2151 set_free_handle_block(NULL); 2152 JNIHandleBlock::release_block(block); 2153 } 2154 2155 // These have to be removed while this is still a valid thread. 2156 remove_stack_guard_pages(); 2157 2158 if (UseTLAB) { 2159 tlab().retire(); 2160 } 2161 2162 if (JvmtiEnv::environments_might_exist()) { 2163 JvmtiExport::cleanup_thread(this); 2164 } 2165 2166 // We need to cache the thread name for logging purposes below as once 2167 // we have called on_thread_detach this thread must not access any oops. 2168 char* thread_name = NULL; 2169 if (log_is_enabled(Debug, os, thread, timer)) { 2170 ResourceMark rm(this); 2171 thread_name = os::strdup(get_thread_name()); 2172 } 2173 2174 // We must flush any deferred card marks and other various GC barrier 2175 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2176 // before removing a thread from the list of active threads. 2177 BarrierSet::barrier_set()->on_thread_detach(this); 2178 2179 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2180 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2181 os::current_thread_id()); 2182 2183 if (log_is_enabled(Debug, os, thread, timer)) { 2184 _timer_exit_phase3.stop(); 2185 _timer_exit_phase4.start(); 2186 } 2187 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2188 Threads::remove(this, daemon); 2189 2190 if (log_is_enabled(Debug, os, thread, timer)) { 2191 _timer_exit_phase4.stop(); 2192 log_debug(os, thread, timer)("name='%s'" 2193 ", exit-phase1=" JLONG_FORMAT 2194 ", exit-phase2=" JLONG_FORMAT 2195 ", exit-phase3=" JLONG_FORMAT 2196 ", exit-phase4=" JLONG_FORMAT, 2197 thread_name, 2198 _timer_exit_phase1.milliseconds(), 2199 _timer_exit_phase2.milliseconds(), 2200 _timer_exit_phase3.milliseconds(), 2201 _timer_exit_phase4.milliseconds()); 2202 os::free(thread_name); 2203 } 2204 } 2205 2206 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2207 if (active_handles() != NULL) { 2208 JNIHandleBlock* block = active_handles(); 2209 set_active_handles(NULL); 2210 JNIHandleBlock::release_block(block); 2211 } 2212 2213 if (free_handle_block() != NULL) { 2214 JNIHandleBlock* block = free_handle_block(); 2215 set_free_handle_block(NULL); 2216 JNIHandleBlock::release_block(block); 2217 } 2218 2219 // These have to be removed while this is still a valid thread. 2220 remove_stack_guard_pages(); 2221 2222 if (UseTLAB) { 2223 tlab().retire(); 2224 } 2225 2226 BarrierSet::barrier_set()->on_thread_detach(this); 2227 2228 Threads::remove(this, is_daemon); 2229 this->smr_delete(); 2230 } 2231 2232 JavaThread* JavaThread::active() { 2233 Thread* thread = Thread::current(); 2234 if (thread->is_Java_thread()) { 2235 return (JavaThread*) thread; 2236 } else { 2237 assert(thread->is_VM_thread(), "this must be a vm thread"); 2238 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2239 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2240 assert(ret->is_Java_thread(), "must be a Java thread"); 2241 return ret; 2242 } 2243 } 2244 2245 bool JavaThread::is_lock_owned(address adr) const { 2246 if (Thread::is_lock_owned(adr)) return true; 2247 2248 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2249 if (chunk->contains(adr)) return true; 2250 } 2251 2252 return false; 2253 } 2254 2255 oop JavaThread::exception_oop() const { 2256 return Atomic::load(&_exception_oop); 2257 } 2258 2259 void JavaThread::set_exception_oop(oop o) { 2260 Atomic::store(&_exception_oop, o); 2261 } 2262 2263 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2264 chunk->set_next(monitor_chunks()); 2265 set_monitor_chunks(chunk); 2266 } 2267 2268 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2269 guarantee(monitor_chunks() != NULL, "must be non empty"); 2270 if (monitor_chunks() == chunk) { 2271 set_monitor_chunks(chunk->next()); 2272 } else { 2273 MonitorChunk* prev = monitor_chunks(); 2274 while (prev->next() != chunk) prev = prev->next(); 2275 prev->set_next(chunk->next()); 2276 } 2277 } 2278 2279 // JVM support. 2280 2281 // Note: this function shouldn't block if it's called in 2282 // _thread_in_native_trans state (such as from 2283 // check_special_condition_for_native_trans()). 2284 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2285 2286 if (has_last_Java_frame() && has_async_condition()) { 2287 // If we are at a polling page safepoint (not a poll return) 2288 // then we must defer async exception because live registers 2289 // will be clobbered by the exception path. Poll return is 2290 // ok because the call we a returning from already collides 2291 // with exception handling registers and so there is no issue. 2292 // (The exception handling path kills call result registers but 2293 // this is ok since the exception kills the result anyway). 2294 2295 if (is_at_poll_safepoint()) { 2296 // if the code we are returning to has deoptimized we must defer 2297 // the exception otherwise live registers get clobbered on the 2298 // exception path before deoptimization is able to retrieve them. 2299 // 2300 RegisterMap map(this, false); 2301 frame caller_fr = last_frame().sender(&map); 2302 assert(caller_fr.is_compiled_frame(), "what?"); 2303 if (caller_fr.is_deoptimized_frame()) { 2304 log_info(exceptions)("deferred async exception at compiled safepoint"); 2305 return; 2306 } 2307 } 2308 } 2309 2310 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2311 if (condition == _no_async_condition) { 2312 // Conditions have changed since has_special_runtime_exit_condition() 2313 // was called: 2314 // - if we were here only because of an external suspend request, 2315 // then that was taken care of above (or cancelled) so we are done 2316 // - if we were here because of another async request, then it has 2317 // been cleared between the has_special_runtime_exit_condition() 2318 // and now so again we are done 2319 return; 2320 } 2321 2322 // Check for pending async. exception 2323 if (_pending_async_exception != NULL) { 2324 // Only overwrite an already pending exception, if it is not a threadDeath. 2325 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2326 2327 // We cannot call Exceptions::_throw(...) here because we cannot block 2328 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2329 2330 LogTarget(Info, exceptions) lt; 2331 if (lt.is_enabled()) { 2332 ResourceMark rm; 2333 LogStream ls(lt); 2334 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2335 if (has_last_Java_frame()) { 2336 frame f = last_frame(); 2337 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2338 } 2339 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2340 } 2341 _pending_async_exception = NULL; 2342 clear_has_async_exception(); 2343 } 2344 } 2345 2346 if (check_unsafe_error && 2347 condition == _async_unsafe_access_error && !has_pending_exception()) { 2348 condition = _no_async_condition; // done 2349 switch (thread_state()) { 2350 case _thread_in_vm: { 2351 JavaThread* THREAD = this; 2352 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2353 } 2354 case _thread_in_native: { 2355 ThreadInVMfromNative tiv(this); 2356 JavaThread* THREAD = this; 2357 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2358 } 2359 case _thread_in_Java: { 2360 ThreadInVMfromJava tiv(this); 2361 JavaThread* THREAD = this; 2362 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2363 } 2364 default: 2365 ShouldNotReachHere(); 2366 } 2367 } 2368 2369 assert(condition == _no_async_condition || has_pending_exception() || 2370 (!check_unsafe_error && condition == _async_unsafe_access_error), 2371 "must have handled the async condition, if no exception"); 2372 } 2373 2374 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2375 2376 // Check for pending external suspend. 2377 if (is_external_suspend_with_lock()) { 2378 frame_anchor()->make_walkable(this); 2379 java_suspend_self_with_safepoint_check(); 2380 } 2381 2382 // We might be here for reasons in addition to the self-suspend request 2383 // so check for other async requests. 2384 if (check_asyncs) { 2385 check_and_handle_async_exceptions(); 2386 } 2387 2388 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2389 } 2390 2391 void JavaThread::send_thread_stop(oop java_throwable) { 2392 ResourceMark rm; 2393 assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread"); 2394 2395 // Do not throw asynchronous exceptions against the compiler thread 2396 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2397 if (!can_call_java()) return; 2398 2399 { 2400 // Actually throw the Throwable against the target Thread - however 2401 // only if there is no thread death exception installed already. 2402 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2403 // If the topmost frame is a runtime stub, then we are calling into 2404 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2405 // must deoptimize the caller before continuing, as the compiled exception handler table 2406 // may not be valid 2407 if (has_last_Java_frame()) { 2408 frame f = last_frame(); 2409 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2410 RegisterMap reg_map(this, false); 2411 frame compiled_frame = f.sender(®_map); 2412 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2413 Deoptimization::deoptimize(this, compiled_frame); 2414 } 2415 } 2416 } 2417 2418 // Set async. pending exception in thread. 2419 set_pending_async_exception(java_throwable); 2420 2421 if (log_is_enabled(Info, exceptions)) { 2422 ResourceMark rm; 2423 log_info(exceptions)("Pending Async. exception installed of type: %s", 2424 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2425 } 2426 // for AbortVMOnException flag 2427 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2428 } 2429 } 2430 2431 2432 // Interrupt thread so it will wake up from a potential wait()/sleep()/park() 2433 java_lang_Thread::set_interrupted(threadObj(), true); 2434 this->interrupt(); 2435 } 2436 2437 // External suspension mechanism. 2438 // 2439 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2440 // to any VM_locks and it is at a transition 2441 // Self-suspension will happen on the transition out of the vm. 2442 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2443 // 2444 // Guarantees on return: 2445 // + Target thread will not execute any new bytecode (that's why we need to 2446 // force a safepoint) 2447 // + Target thread will not enter any new monitors 2448 // 2449 void JavaThread::java_suspend() { 2450 ThreadsListHandle tlh; 2451 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2452 return; 2453 } 2454 2455 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2456 if (!is_external_suspend()) { 2457 // a racing resume has cancelled us; bail out now 2458 return; 2459 } 2460 2461 // suspend is done 2462 uint32_t debug_bits = 0; 2463 // Warning: is_ext_suspend_completed() may temporarily drop the 2464 // SR_lock to allow the thread to reach a stable thread state if 2465 // it is currently in a transient thread state. 2466 if (is_ext_suspend_completed(false /* !called_by_wait */, 2467 SuspendRetryDelay, &debug_bits)) { 2468 return; 2469 } 2470 } 2471 2472 if (Thread::current() == this) { 2473 // Safely self-suspend. 2474 // If we don't do this explicitly it will implicitly happen 2475 // before we transition back to Java, and on some other thread-state 2476 // transition paths, but not as we exit a JVM TI SuspendThread call. 2477 // As SuspendThread(current) must not return (until resumed) we must 2478 // self-suspend here. 2479 ThreadBlockInVM tbivm(this); 2480 java_suspend_self(); 2481 } else { 2482 VM_ThreadSuspend vm_suspend; 2483 VMThread::execute(&vm_suspend); 2484 } 2485 } 2486 2487 // Part II of external suspension. 2488 // A JavaThread self suspends when it detects a pending external suspend 2489 // request. This is usually on transitions. It is also done in places 2490 // where continuing to the next transition would surprise the caller, 2491 // e.g., monitor entry. 2492 // 2493 // Returns the number of times that the thread self-suspended. 2494 // 2495 // Note: DO NOT call java_suspend_self() when you just want to block current 2496 // thread. java_suspend_self() is the second stage of cooperative 2497 // suspension for external suspend requests and should only be used 2498 // to complete an external suspend request. 2499 // 2500 int JavaThread::java_suspend_self() { 2501 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2502 int ret = 0; 2503 2504 // we are in the process of exiting so don't suspend 2505 if (is_exiting()) { 2506 clear_external_suspend(); 2507 return ret; 2508 } 2509 2510 assert(_anchor.walkable() || 2511 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2512 "must have walkable stack"); 2513 2514 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2515 2516 assert(!this->is_ext_suspended(), 2517 "a thread trying to self-suspend should not already be suspended"); 2518 2519 if (this->is_suspend_equivalent()) { 2520 // If we are self-suspending as a result of the lifting of a 2521 // suspend equivalent condition, then the suspend_equivalent 2522 // flag is not cleared until we set the ext_suspended flag so 2523 // that wait_for_ext_suspend_completion() returns consistent 2524 // results. 2525 this->clear_suspend_equivalent(); 2526 } 2527 2528 // A racing resume may have cancelled us before we grabbed SR_lock 2529 // above. Or another external suspend request could be waiting for us 2530 // by the time we return from SR_lock()->wait(). The thread 2531 // that requested the suspension may already be trying to walk our 2532 // stack and if we return now, we can change the stack out from under 2533 // it. This would be a "bad thing (TM)" and cause the stack walker 2534 // to crash. We stay self-suspended until there are no more pending 2535 // external suspend requests. 2536 while (is_external_suspend()) { 2537 ret++; 2538 this->set_ext_suspended(); 2539 2540 // _ext_suspended flag is cleared by java_resume() 2541 while (is_ext_suspended()) { 2542 ml.wait(); 2543 } 2544 } 2545 return ret; 2546 } 2547 2548 // Helper routine to set up the correct thread state before calling java_suspend_self. 2549 // This is called when regular thread-state transition helpers can't be used because 2550 // we can be in various states, in particular _thread_in_native_trans. 2551 // Because this thread is external suspended the safepoint code will count it as at 2552 // a safepoint, regardless of what its actual current thread-state is. But 2553 // is_ext_suspend_completed() may be waiting to see a thread transition from 2554 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2555 // to _thread_blocked. The problem with setting thread state directly is that a 2556 // safepoint could happen just after java_suspend_self() returns after being resumed, 2557 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2558 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2559 // However, not all initial-states are allowed when performing a safepoint check, as we 2560 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2561 // only _thread_in_native is possible when executing this code (based on our two callers). 2562 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2563 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2564 // and so we don't need the explicit safepoint check. 2565 2566 void JavaThread::java_suspend_self_with_safepoint_check() { 2567 assert(this == Thread::current(), "invariant"); 2568 JavaThreadState state = thread_state(); 2569 set_thread_state(_thread_blocked); 2570 java_suspend_self(); 2571 set_thread_state_fence(state); 2572 // Since we are not using a regular thread-state transition helper here, 2573 // we must manually emit the instruction barrier after leaving a safe state. 2574 OrderAccess::cross_modify_fence(); 2575 if (state != _thread_in_native) { 2576 SafepointMechanism::block_if_requested(this); 2577 } 2578 } 2579 2580 #ifdef ASSERT 2581 // Verify the JavaThread has not yet been published in the Threads::list, and 2582 // hence doesn't need protection from concurrent access at this stage. 2583 void JavaThread::verify_not_published() { 2584 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2585 // since an unpublished JavaThread doesn't participate in the 2586 // Thread-SMR protocol for keeping a ThreadsList alive. 2587 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2588 } 2589 #endif 2590 2591 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2592 // progress or when _suspend_flags is non-zero. 2593 // Current thread needs to self-suspend if there is a suspend request and/or 2594 // block if a safepoint is in progress. 2595 // Async exception ISN'T checked. 2596 // Note only the ThreadInVMfromNative transition can call this function 2597 // directly and when thread state is _thread_in_native_trans 2598 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2599 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2600 2601 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2602 2603 if (thread->is_external_suspend()) { 2604 thread->java_suspend_self_with_safepoint_check(); 2605 } else { 2606 SafepointMechanism::block_if_requested(thread); 2607 } 2608 2609 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2610 } 2611 2612 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2613 // progress or when _suspend_flags is non-zero. 2614 // Current thread needs to self-suspend if there is a suspend request and/or 2615 // block if a safepoint is in progress. 2616 // Also check for pending async exception (not including unsafe access error). 2617 // Note only the native==>VM/Java barriers can call this function and when 2618 // thread state is _thread_in_native_trans. 2619 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2620 check_safepoint_and_suspend_for_native_trans(thread); 2621 2622 if (thread->has_async_exception()) { 2623 // We are in _thread_in_native_trans state, don't handle unsafe 2624 // access error since that may block. 2625 thread->check_and_handle_async_exceptions(false); 2626 } 2627 } 2628 2629 // This is a variant of the normal 2630 // check_special_condition_for_native_trans with slightly different 2631 // semantics for use by critical native wrappers. It does all the 2632 // normal checks but also performs the transition back into 2633 // thread_in_Java state. This is required so that critical natives 2634 // can potentially block and perform a GC if they are the last thread 2635 // exiting the GCLocker. 2636 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2637 check_special_condition_for_native_trans(thread); 2638 2639 // Finish the transition 2640 thread->set_thread_state(_thread_in_Java); 2641 2642 if (thread->do_critical_native_unlock()) { 2643 ThreadInVMfromJavaNoAsyncException tiv(thread); 2644 GCLocker::unlock_critical(thread); 2645 thread->clear_critical_native_unlock(); 2646 } 2647 } 2648 2649 // We need to guarantee the Threads_lock here, since resumes are not 2650 // allowed during safepoint synchronization 2651 // Can only resume from an external suspension 2652 void JavaThread::java_resume() { 2653 assert_locked_or_safepoint(Threads_lock); 2654 2655 // Sanity check: thread is gone, has started exiting or the thread 2656 // was not externally suspended. 2657 ThreadsListHandle tlh; 2658 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2659 return; 2660 } 2661 2662 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2663 2664 clear_external_suspend(); 2665 2666 if (is_ext_suspended()) { 2667 clear_ext_suspended(); 2668 SR_lock()->notify_all(); 2669 } 2670 } 2671 2672 size_t JavaThread::_stack_red_zone_size = 0; 2673 size_t JavaThread::_stack_yellow_zone_size = 0; 2674 size_t JavaThread::_stack_reserved_zone_size = 0; 2675 size_t JavaThread::_stack_shadow_zone_size = 0; 2676 2677 void JavaThread::create_stack_guard_pages() { 2678 if (!os::uses_stack_guard_pages() || 2679 _stack_guard_state != stack_guard_unused || 2680 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2681 log_info(os, thread)("Stack guard page creation for thread " 2682 UINTX_FORMAT " disabled", os::current_thread_id()); 2683 return; 2684 } 2685 address low_addr = stack_end(); 2686 size_t len = stack_guard_zone_size(); 2687 2688 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2689 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2690 2691 int must_commit = os::must_commit_stack_guard_pages(); 2692 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2693 2694 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2695 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2696 return; 2697 } 2698 2699 if (os::guard_memory((char *) low_addr, len)) { 2700 _stack_guard_state = stack_guard_enabled; 2701 } else { 2702 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2703 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2704 if (os::uncommit_memory((char *) low_addr, len)) { 2705 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2706 } 2707 return; 2708 } 2709 2710 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2711 PTR_FORMAT "-" PTR_FORMAT ".", 2712 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2713 } 2714 2715 void JavaThread::remove_stack_guard_pages() { 2716 assert(Thread::current() == this, "from different thread"); 2717 if (_stack_guard_state == stack_guard_unused) return; 2718 address low_addr = stack_end(); 2719 size_t len = stack_guard_zone_size(); 2720 2721 if (os::must_commit_stack_guard_pages()) { 2722 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2723 _stack_guard_state = stack_guard_unused; 2724 } else { 2725 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2726 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2727 return; 2728 } 2729 } else { 2730 if (_stack_guard_state == stack_guard_unused) return; 2731 if (os::unguard_memory((char *) low_addr, len)) { 2732 _stack_guard_state = stack_guard_unused; 2733 } else { 2734 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2735 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2736 return; 2737 } 2738 } 2739 2740 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2741 PTR_FORMAT "-" PTR_FORMAT ".", 2742 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2743 } 2744 2745 void JavaThread::enable_stack_reserved_zone() { 2746 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2747 2748 // The base notation is from the stack's point of view, growing downward. 2749 // We need to adjust it to work correctly with guard_memory() 2750 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2751 2752 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2753 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2754 2755 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2756 _stack_guard_state = stack_guard_enabled; 2757 } else { 2758 warning("Attempt to guard stack reserved zone failed."); 2759 } 2760 enable_register_stack_guard(); 2761 } 2762 2763 void JavaThread::disable_stack_reserved_zone() { 2764 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2765 2766 // Simply return if called for a thread that does not use guard pages. 2767 if (_stack_guard_state != stack_guard_enabled) return; 2768 2769 // The base notation is from the stack's point of view, growing downward. 2770 // We need to adjust it to work correctly with guard_memory() 2771 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2772 2773 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2774 _stack_guard_state = stack_guard_reserved_disabled; 2775 } else { 2776 warning("Attempt to unguard stack reserved zone failed."); 2777 } 2778 disable_register_stack_guard(); 2779 } 2780 2781 void JavaThread::enable_stack_yellow_reserved_zone() { 2782 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2783 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2784 2785 // The base notation is from the stacks point of view, growing downward. 2786 // We need to adjust it to work correctly with guard_memory() 2787 address base = stack_red_zone_base(); 2788 2789 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2790 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2791 2792 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2793 _stack_guard_state = stack_guard_enabled; 2794 } else { 2795 warning("Attempt to guard stack yellow zone failed."); 2796 } 2797 enable_register_stack_guard(); 2798 } 2799 2800 void JavaThread::disable_stack_yellow_reserved_zone() { 2801 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2802 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2803 2804 // Simply return if called for a thread that does not use guard pages. 2805 if (_stack_guard_state == stack_guard_unused) return; 2806 2807 // The base notation is from the stacks point of view, growing downward. 2808 // We need to adjust it to work correctly with guard_memory() 2809 address base = stack_red_zone_base(); 2810 2811 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2812 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2813 } else { 2814 warning("Attempt to unguard stack yellow zone failed."); 2815 } 2816 disable_register_stack_guard(); 2817 } 2818 2819 void JavaThread::enable_stack_red_zone() { 2820 // The base notation is from the stacks point of view, growing downward. 2821 // We need to adjust it to work correctly with guard_memory() 2822 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2823 address base = stack_red_zone_base() - stack_red_zone_size(); 2824 2825 guarantee(base < stack_base(), "Error calculating stack red zone"); 2826 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2827 2828 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2829 warning("Attempt to guard stack red zone failed."); 2830 } 2831 } 2832 2833 void JavaThread::disable_stack_red_zone() { 2834 // The base notation is from the stacks point of view, growing downward. 2835 // We need to adjust it to work correctly with guard_memory() 2836 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2837 address base = stack_red_zone_base() - stack_red_zone_size(); 2838 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2839 warning("Attempt to unguard stack red zone failed."); 2840 } 2841 } 2842 2843 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2844 // ignore is there is no stack 2845 if (!has_last_Java_frame()) return; 2846 // traverse the stack frames. Starts from top frame. 2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2848 frame* fr = fst.current(); 2849 f(fr, fst.register_map()); 2850 } 2851 } 2852 2853 2854 #ifndef PRODUCT 2855 // Deoptimization 2856 // Function for testing deoptimization 2857 void JavaThread::deoptimize() { 2858 StackFrameStream fst(this, false); 2859 bool deopt = false; // Dump stack only if a deopt actually happens. 2860 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2861 // Iterate over all frames in the thread and deoptimize 2862 for (; !fst.is_done(); fst.next()) { 2863 if (fst.current()->can_be_deoptimized()) { 2864 2865 if (only_at) { 2866 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2867 // consists of comma or carriage return separated numbers so 2868 // search for the current bci in that string. 2869 address pc = fst.current()->pc(); 2870 nmethod* nm = (nmethod*) fst.current()->cb(); 2871 ScopeDesc* sd = nm->scope_desc_at(pc); 2872 char buffer[8]; 2873 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2874 size_t len = strlen(buffer); 2875 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2876 while (found != NULL) { 2877 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2878 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2879 // Check that the bci found is bracketed by terminators. 2880 break; 2881 } 2882 found = strstr(found + 1, buffer); 2883 } 2884 if (!found) { 2885 continue; 2886 } 2887 } 2888 2889 if (DebugDeoptimization && !deopt) { 2890 deopt = true; // One-time only print before deopt 2891 tty->print_cr("[BEFORE Deoptimization]"); 2892 trace_frames(); 2893 trace_stack(); 2894 } 2895 Deoptimization::deoptimize(this, *fst.current()); 2896 } 2897 } 2898 2899 if (DebugDeoptimization && deopt) { 2900 tty->print_cr("[AFTER Deoptimization]"); 2901 trace_frames(); 2902 } 2903 } 2904 2905 2906 // Make zombies 2907 void JavaThread::make_zombies() { 2908 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2909 if (fst.current()->can_be_deoptimized()) { 2910 // it is a Java nmethod 2911 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2912 nm->make_not_entrant(); 2913 } 2914 } 2915 } 2916 #endif // PRODUCT 2917 2918 2919 void JavaThread::deoptimize_marked_methods() { 2920 if (!has_last_Java_frame()) return; 2921 StackFrameStream fst(this, false); 2922 for (; !fst.is_done(); fst.next()) { 2923 if (fst.current()->should_be_deoptimized()) { 2924 Deoptimization::deoptimize(this, *fst.current()); 2925 } 2926 } 2927 } 2928 2929 // If the caller is a NamedThread, then remember, in the current scope, 2930 // the given JavaThread in its _processed_thread field. 2931 class RememberProcessedThread: public StackObj { 2932 NamedThread* _cur_thr; 2933 public: 2934 RememberProcessedThread(JavaThread* jthr) { 2935 Thread* thread = Thread::current(); 2936 if (thread->is_Named_thread()) { 2937 _cur_thr = (NamedThread *)thread; 2938 _cur_thr->set_processed_thread(jthr); 2939 } else { 2940 _cur_thr = NULL; 2941 } 2942 } 2943 2944 ~RememberProcessedThread() { 2945 if (_cur_thr) { 2946 _cur_thr->set_processed_thread(NULL); 2947 } 2948 } 2949 }; 2950 2951 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2952 // Verify that the deferred card marks have been flushed. 2953 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2954 2955 // Traverse the GCHandles 2956 Thread::oops_do(f, cf); 2957 2958 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2959 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2960 2961 if (has_last_Java_frame()) { 2962 // Record JavaThread to GC thread 2963 RememberProcessedThread rpt(this); 2964 2965 // traverse the registered growable array 2966 if (_array_for_gc != NULL) { 2967 for (int index = 0; index < _array_for_gc->length(); index++) { 2968 f->do_oop(_array_for_gc->adr_at(index)); 2969 } 2970 } 2971 2972 // Traverse the monitor chunks 2973 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2974 chunk->oops_do(f); 2975 } 2976 2977 // Traverse the execution stack 2978 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2979 fst.current()->oops_do(f, cf, fst.register_map()); 2980 } 2981 } 2982 2983 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2984 // If we have deferred set_locals there might be oops waiting to be 2985 // written 2986 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2987 if (list != NULL) { 2988 for (int i = 0; i < list->length(); i++) { 2989 list->at(i)->oops_do(f); 2990 } 2991 } 2992 2993 // Traverse instance variables at the end since the GC may be moving things 2994 // around using this function 2995 f->do_oop((oop*) &_threadObj); 2996 f->do_oop((oop*) &_vm_result); 2997 f->do_oop((oop*) &_exception_oop); 2998 f->do_oop((oop*) &_pending_async_exception); 2999 3000 if (jvmti_thread_state() != NULL) { 3001 jvmti_thread_state()->oops_do(f, cf); 3002 } 3003 } 3004 3005 #ifdef ASSERT 3006 void JavaThread::verify_states_for_handshake() { 3007 // This checks that the thread has a correct frame state during a handshake. 3008 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3009 (has_last_Java_frame() && java_call_counter() > 0), 3010 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3011 has_last_Java_frame(), java_call_counter()); 3012 } 3013 #endif 3014 3015 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 3016 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3017 (has_last_Java_frame() && java_call_counter() > 0), 3018 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3019 has_last_Java_frame(), java_call_counter()); 3020 3021 if (has_last_Java_frame()) { 3022 // Traverse the execution stack 3023 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3024 fst.current()->nmethods_do(cf); 3025 } 3026 } 3027 3028 if (jvmti_thread_state() != NULL) { 3029 jvmti_thread_state()->nmethods_do(cf); 3030 } 3031 } 3032 3033 void JavaThread::metadata_do(MetadataClosure* f) { 3034 if (has_last_Java_frame()) { 3035 // Traverse the execution stack to call f() on the methods in the stack 3036 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3037 fst.current()->metadata_do(f); 3038 } 3039 } else if (is_Compiler_thread()) { 3040 // need to walk ciMetadata in current compile tasks to keep alive. 3041 CompilerThread* ct = (CompilerThread*)this; 3042 if (ct->env() != NULL) { 3043 ct->env()->metadata_do(f); 3044 } 3045 CompileTask* task = ct->task(); 3046 if (task != NULL) { 3047 task->metadata_do(f); 3048 } 3049 } 3050 } 3051 3052 // Printing 3053 const char* _get_thread_state_name(JavaThreadState _thread_state) { 3054 switch (_thread_state) { 3055 case _thread_uninitialized: return "_thread_uninitialized"; 3056 case _thread_new: return "_thread_new"; 3057 case _thread_new_trans: return "_thread_new_trans"; 3058 case _thread_in_native: return "_thread_in_native"; 3059 case _thread_in_native_trans: return "_thread_in_native_trans"; 3060 case _thread_in_vm: return "_thread_in_vm"; 3061 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3062 case _thread_in_Java: return "_thread_in_Java"; 3063 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3064 case _thread_blocked: return "_thread_blocked"; 3065 case _thread_blocked_trans: return "_thread_blocked_trans"; 3066 default: return "unknown thread state"; 3067 } 3068 } 3069 3070 #ifndef PRODUCT 3071 void JavaThread::print_thread_state_on(outputStream *st) const { 3072 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3073 }; 3074 #endif // PRODUCT 3075 3076 // Called by Threads::print() for VM_PrintThreads operation 3077 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3078 st->print_raw("\""); 3079 st->print_raw(get_thread_name()); 3080 st->print_raw("\" "); 3081 oop thread_oop = threadObj(); 3082 if (thread_oop != NULL) { 3083 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3084 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3085 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3086 } 3087 Thread::print_on(st, print_extended_info); 3088 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3089 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3090 if (thread_oop != NULL) { 3091 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3092 } 3093 #ifndef PRODUCT 3094 _safepoint_state->print_on(st); 3095 #endif // PRODUCT 3096 if (is_Compiler_thread()) { 3097 CompileTask *task = ((CompilerThread*)this)->task(); 3098 if (task != NULL) { 3099 st->print(" Compiling: "); 3100 task->print(st, NULL, true, false); 3101 } else { 3102 st->print(" No compile task"); 3103 } 3104 st->cr(); 3105 } 3106 } 3107 3108 void JavaThread::print() const { print_on(tty); } 3109 3110 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3111 st->print("%s", get_thread_name_string(buf, buflen)); 3112 } 3113 3114 // Called by fatal error handler. The difference between this and 3115 // JavaThread::print() is that we can't grab lock or allocate memory. 3116 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3117 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3118 oop thread_obj = threadObj(); 3119 if (thread_obj != NULL) { 3120 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3121 } 3122 st->print(" ["); 3123 st->print("%s", _get_thread_state_name(_thread_state)); 3124 if (osthread()) { 3125 st->print(", id=%d", osthread()->thread_id()); 3126 } 3127 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3128 p2i(stack_end()), p2i(stack_base())); 3129 st->print("]"); 3130 3131 ThreadsSMRSupport::print_info_on(this, st); 3132 return; 3133 } 3134 3135 // Verification 3136 3137 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3138 3139 void JavaThread::verify() { 3140 // Verify oops in the thread. 3141 oops_do(&VerifyOopClosure::verify_oop, NULL); 3142 3143 // Verify the stack frames. 3144 frames_do(frame_verify); 3145 } 3146 3147 // CR 6300358 (sub-CR 2137150) 3148 // Most callers of this method assume that it can't return NULL but a 3149 // thread may not have a name whilst it is in the process of attaching to 3150 // the VM - see CR 6412693, and there are places where a JavaThread can be 3151 // seen prior to having it's threadObj set (eg JNI attaching threads and 3152 // if vm exit occurs during initialization). These cases can all be accounted 3153 // for such that this method never returns NULL. 3154 const char* JavaThread::get_thread_name() const { 3155 #ifdef ASSERT 3156 // early safepoints can hit while current thread does not yet have TLS 3157 if (!SafepointSynchronize::is_at_safepoint()) { 3158 Thread *cur = Thread::current(); 3159 if (!(cur->is_Java_thread() && cur == this)) { 3160 // Current JavaThreads are allowed to get their own name without 3161 // the Threads_lock. 3162 assert_locked_or_safepoint_or_handshake(Threads_lock, this); 3163 } 3164 } 3165 #endif // ASSERT 3166 return get_thread_name_string(); 3167 } 3168 3169 // Returns a non-NULL representation of this thread's name, or a suitable 3170 // descriptive string if there is no set name 3171 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3172 const char* name_str; 3173 oop thread_obj = threadObj(); 3174 if (thread_obj != NULL) { 3175 oop name = java_lang_Thread::name(thread_obj); 3176 if (name != NULL) { 3177 if (buf == NULL) { 3178 name_str = java_lang_String::as_utf8_string(name); 3179 } else { 3180 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3181 } 3182 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3183 name_str = "<no-name - thread is attaching>"; 3184 } else { 3185 name_str = Thread::name(); 3186 } 3187 } else { 3188 name_str = Thread::name(); 3189 } 3190 assert(name_str != NULL, "unexpected NULL thread name"); 3191 return name_str; 3192 } 3193 3194 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3195 3196 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3197 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3198 // Link Java Thread object <-> C++ Thread 3199 3200 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3201 // and put it into a new Handle. The Handle "thread_oop" can then 3202 // be used to pass the C++ thread object to other methods. 3203 3204 // Set the Java level thread object (jthread) field of the 3205 // new thread (a JavaThread *) to C++ thread object using the 3206 // "thread_oop" handle. 3207 3208 // Set the thread field (a JavaThread *) of the 3209 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3210 3211 Handle thread_oop(Thread::current(), 3212 JNIHandles::resolve_non_null(jni_thread)); 3213 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3214 "must be initialized"); 3215 set_threadObj(thread_oop()); 3216 java_lang_Thread::set_thread(thread_oop(), this); 3217 3218 if (prio == NoPriority) { 3219 prio = java_lang_Thread::priority(thread_oop()); 3220 assert(prio != NoPriority, "A valid priority should be present"); 3221 } 3222 3223 // Push the Java priority down to the native thread; needs Threads_lock 3224 Thread::set_priority(this, prio); 3225 3226 // Add the new thread to the Threads list and set it in motion. 3227 // We must have threads lock in order to call Threads::add. 3228 // It is crucial that we do not block before the thread is 3229 // added to the Threads list for if a GC happens, then the java_thread oop 3230 // will not be visited by GC. 3231 Threads::add(this); 3232 } 3233 3234 oop JavaThread::current_park_blocker() { 3235 // Support for JSR-166 locks 3236 oop thread_oop = threadObj(); 3237 if (thread_oop != NULL) { 3238 return java_lang_Thread::park_blocker(thread_oop); 3239 } 3240 return NULL; 3241 } 3242 3243 3244 void JavaThread::print_stack_on(outputStream* st) { 3245 if (!has_last_Java_frame()) return; 3246 ResourceMark rm; 3247 HandleMark hm; 3248 3249 RegisterMap reg_map(this); 3250 vframe* start_vf = last_java_vframe(®_map); 3251 int count = 0; 3252 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3253 if (f->is_java_frame()) { 3254 javaVFrame* jvf = javaVFrame::cast(f); 3255 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3256 3257 // Print out lock information 3258 if (JavaMonitorsInStackTrace) { 3259 jvf->print_lock_info_on(st, count); 3260 } 3261 } else { 3262 // Ignore non-Java frames 3263 } 3264 3265 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3266 count++; 3267 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3268 } 3269 } 3270 3271 3272 // JVMTI PopFrame support 3273 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3274 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3275 if (in_bytes(size_in_bytes) != 0) { 3276 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3277 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3278 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3279 } 3280 } 3281 3282 void* JavaThread::popframe_preserved_args() { 3283 return _popframe_preserved_args; 3284 } 3285 3286 ByteSize JavaThread::popframe_preserved_args_size() { 3287 return in_ByteSize(_popframe_preserved_args_size); 3288 } 3289 3290 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3291 int sz = in_bytes(popframe_preserved_args_size()); 3292 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3293 return in_WordSize(sz / wordSize); 3294 } 3295 3296 void JavaThread::popframe_free_preserved_args() { 3297 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3298 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args); 3299 _popframe_preserved_args = NULL; 3300 _popframe_preserved_args_size = 0; 3301 } 3302 3303 #ifndef PRODUCT 3304 3305 void JavaThread::trace_frames() { 3306 tty->print_cr("[Describe stack]"); 3307 int frame_no = 1; 3308 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3309 tty->print(" %d. ", frame_no++); 3310 fst.current()->print_value_on(tty, this); 3311 tty->cr(); 3312 } 3313 } 3314 3315 class PrintAndVerifyOopClosure: public OopClosure { 3316 protected: 3317 template <class T> inline void do_oop_work(T* p) { 3318 oop obj = RawAccess<>::oop_load(p); 3319 if (obj == NULL) return; 3320 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3321 if (oopDesc::is_oop_or_null(obj)) { 3322 if (obj->is_objArray()) { 3323 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3324 } else { 3325 obj->print(); 3326 } 3327 } else { 3328 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3329 } 3330 tty->cr(); 3331 } 3332 public: 3333 virtual void do_oop(oop* p) { do_oop_work(p); } 3334 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3335 }; 3336 3337 #ifdef ASSERT 3338 // Print or validate the layout of stack frames 3339 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3340 ResourceMark rm; 3341 PRESERVE_EXCEPTION_MARK; 3342 FrameValues values; 3343 int frame_no = 0; 3344 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3345 fst.current()->describe(values, ++frame_no); 3346 if (depth == frame_no) break; 3347 } 3348 if (validate_only) { 3349 values.validate(); 3350 } else { 3351 tty->print_cr("[Describe stack layout]"); 3352 values.print(this); 3353 } 3354 } 3355 #endif 3356 3357 void JavaThread::trace_stack_from(vframe* start_vf) { 3358 ResourceMark rm; 3359 int vframe_no = 1; 3360 for (vframe* f = start_vf; f; f = f->sender()) { 3361 if (f->is_java_frame()) { 3362 javaVFrame::cast(f)->print_activation(vframe_no++); 3363 } else { 3364 f->print(); 3365 } 3366 if (vframe_no > StackPrintLimit) { 3367 tty->print_cr("...<more frames>..."); 3368 return; 3369 } 3370 } 3371 } 3372 3373 3374 void JavaThread::trace_stack() { 3375 if (!has_last_Java_frame()) return; 3376 ResourceMark rm; 3377 HandleMark hm; 3378 RegisterMap reg_map(this); 3379 trace_stack_from(last_java_vframe(®_map)); 3380 } 3381 3382 3383 #endif // PRODUCT 3384 3385 3386 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3387 assert(reg_map != NULL, "a map must be given"); 3388 frame f = last_frame(); 3389 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3390 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3391 } 3392 return NULL; 3393 } 3394 3395 3396 Klass* JavaThread::security_get_caller_class(int depth) { 3397 vframeStream vfst(this); 3398 vfst.security_get_caller_frame(depth); 3399 if (!vfst.at_end()) { 3400 return vfst.method()->method_holder(); 3401 } 3402 return NULL; 3403 } 3404 3405 // java.lang.Thread.sleep support 3406 // Returns true if sleep time elapsed as expected, and false 3407 // if the thread was interrupted. 3408 bool JavaThread::sleep(jlong millis) { 3409 assert(this == Thread::current(), "thread consistency check"); 3410 3411 ParkEvent * const slp = this->_SleepEvent; 3412 // Because there can be races with thread interruption sending an unpark() 3413 // to the event, we explicitly reset it here to avoid an immediate return. 3414 // The actual interrupt state will be checked before we park(). 3415 slp->reset(); 3416 // Thread interruption establishes a happens-before ordering in the 3417 // Java Memory Model, so we need to ensure we synchronize with the 3418 // interrupt state. 3419 OrderAccess::fence(); 3420 3421 jlong prevtime = os::javaTimeNanos(); 3422 3423 for (;;) { 3424 // interruption has precedence over timing out 3425 if (this->is_interrupted(true)) { 3426 return false; 3427 } 3428 3429 if (millis <= 0) { 3430 return true; 3431 } 3432 3433 { 3434 ThreadBlockInVM tbivm(this); 3435 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 3436 3437 this->set_suspend_equivalent(); 3438 // cleared by handle_special_suspend_equivalent_condition() or 3439 // java_suspend_self() via check_and_wait_while_suspended() 3440 3441 slp->park(millis); 3442 3443 // were we externally suspended while we were waiting? 3444 this->check_and_wait_while_suspended(); 3445 } 3446 3447 // Update elapsed time tracking 3448 jlong newtime = os::javaTimeNanos(); 3449 if (newtime - prevtime < 0) { 3450 // time moving backwards, should only happen if no monotonic clock 3451 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3452 assert(!os::supports_monotonic_clock(), 3453 "unexpected time moving backwards detected in JavaThread::sleep()"); 3454 } else { 3455 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3456 } 3457 prevtime = newtime; 3458 } 3459 } 3460 3461 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3462 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3463 CompileBroker::compiler_thread_loop(); 3464 } 3465 3466 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3467 NMethodSweeper::sweeper_loop(); 3468 } 3469 3470 // Create a CompilerThread 3471 CompilerThread::CompilerThread(CompileQueue* queue, 3472 CompilerCounters* counters) 3473 : JavaThread(&compiler_thread_entry) { 3474 _env = NULL; 3475 _log = NULL; 3476 _task = NULL; 3477 _queue = queue; 3478 _counters = counters; 3479 _buffer_blob = NULL; 3480 _compiler = NULL; 3481 3482 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3483 resource_area()->bias_to(mtCompiler); 3484 3485 #ifndef PRODUCT 3486 _ideal_graph_printer = NULL; 3487 #endif 3488 } 3489 3490 CompilerThread::~CompilerThread() { 3491 // Delete objects which were allocated on heap. 3492 delete _counters; 3493 } 3494 3495 bool CompilerThread::can_call_java() const { 3496 return _compiler != NULL && _compiler->is_jvmci(); 3497 } 3498 3499 // Create sweeper thread 3500 CodeCacheSweeperThread::CodeCacheSweeperThread() 3501 : JavaThread(&sweeper_thread_entry) { 3502 _scanned_compiled_method = NULL; 3503 } 3504 3505 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3506 JavaThread::oops_do(f, cf); 3507 if (_scanned_compiled_method != NULL && cf != NULL) { 3508 // Safepoints can occur when the sweeper is scanning an nmethod so 3509 // process it here to make sure it isn't unloaded in the middle of 3510 // a scan. 3511 cf->do_code_blob(_scanned_compiled_method); 3512 } 3513 } 3514 3515 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3516 JavaThread::nmethods_do(cf); 3517 if (_scanned_compiled_method != NULL && cf != NULL) { 3518 // Safepoints can occur when the sweeper is scanning an nmethod so 3519 // process it here to make sure it isn't unloaded in the middle of 3520 // a scan. 3521 cf->do_code_blob(_scanned_compiled_method); 3522 } 3523 } 3524 3525 3526 // ======= Threads ======== 3527 3528 // The Threads class links together all active threads, and provides 3529 // operations over all threads. It is protected by the Threads_lock, 3530 // which is also used in other global contexts like safepointing. 3531 // ThreadsListHandles are used to safely perform operations on one 3532 // or more threads without the risk of the thread exiting during the 3533 // operation. 3534 // 3535 // Note: The Threads_lock is currently more widely used than we 3536 // would like. We are actively migrating Threads_lock uses to other 3537 // mechanisms in order to reduce Threads_lock contention. 3538 3539 int Threads::_number_of_threads = 0; 3540 int Threads::_number_of_non_daemon_threads = 0; 3541 int Threads::_return_code = 0; 3542 uintx Threads::_thread_claim_token = 1; // Never zero. 3543 size_t JavaThread::_stack_size_at_create = 0; 3544 3545 #ifdef ASSERT 3546 bool Threads::_vm_complete = false; 3547 #endif 3548 3549 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3550 Prefetch::read((void*)addr, prefetch_interval); 3551 return *addr; 3552 } 3553 3554 // Possibly the ugliest for loop the world has seen. C++ does not allow 3555 // multiple types in the declaration section of the for loop. In this case 3556 // we are only dealing with pointers and hence can cast them. It looks ugly 3557 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3558 #define DO_JAVA_THREADS(LIST, X) \ 3559 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3560 *MACRO_list = (JavaThread*)(LIST), \ 3561 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3562 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3563 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3564 MACRO_current_p != MACRO_end; \ 3565 MACRO_current_p++, \ 3566 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3567 3568 // All JavaThreads 3569 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3570 3571 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3572 void Threads::non_java_threads_do(ThreadClosure* tc) { 3573 NoSafepointVerifier nsv; 3574 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3575 tc->do_thread(njti.current()); 3576 } 3577 } 3578 3579 // All JavaThreads 3580 void Threads::java_threads_do(ThreadClosure* tc) { 3581 assert_locked_or_safepoint(Threads_lock); 3582 // ALL_JAVA_THREADS iterates through all JavaThreads. 3583 ALL_JAVA_THREADS(p) { 3584 tc->do_thread(p); 3585 } 3586 } 3587 3588 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3589 assert_locked_or_safepoint(Threads_lock); 3590 java_threads_do(tc); 3591 tc->do_thread(VMThread::vm_thread()); 3592 } 3593 3594 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3595 void Threads::threads_do(ThreadClosure* tc) { 3596 assert_locked_or_safepoint(Threads_lock); 3597 java_threads_do(tc); 3598 non_java_threads_do(tc); 3599 } 3600 3601 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3602 uintx claim_token = Threads::thread_claim_token(); 3603 ALL_JAVA_THREADS(p) { 3604 if (p->claim_threads_do(is_par, claim_token)) { 3605 tc->do_thread(p); 3606 } 3607 } 3608 VMThread* vmt = VMThread::vm_thread(); 3609 if (vmt->claim_threads_do(is_par, claim_token)) { 3610 tc->do_thread(vmt); 3611 } 3612 } 3613 3614 // The system initialization in the library has three phases. 3615 // 3616 // Phase 1: java.lang.System class initialization 3617 // java.lang.System is a primordial class loaded and initialized 3618 // by the VM early during startup. java.lang.System.<clinit> 3619 // only does registerNatives and keeps the rest of the class 3620 // initialization work later until thread initialization completes. 3621 // 3622 // System.initPhase1 initializes the system properties, the static 3623 // fields in, out, and err. Set up java signal handlers, OS-specific 3624 // system settings, and thread group of the main thread. 3625 static void call_initPhase1(TRAPS) { 3626 Klass* klass = SystemDictionary::System_klass(); 3627 JavaValue result(T_VOID); 3628 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3629 vmSymbols::void_method_signature(), CHECK); 3630 } 3631 3632 // Phase 2. Module system initialization 3633 // This will initialize the module system. Only java.base classes 3634 // can be loaded until phase 2 completes. 3635 // 3636 // Call System.initPhase2 after the compiler initialization and jsr292 3637 // classes get initialized because module initialization runs a lot of java 3638 // code, that for performance reasons, should be compiled. Also, this will 3639 // enable the startup code to use lambda and other language features in this 3640 // phase and onward. 3641 // 3642 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3643 static void call_initPhase2(TRAPS) { 3644 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3645 3646 Klass* klass = SystemDictionary::System_klass(); 3647 3648 JavaValue result(T_INT); 3649 JavaCallArguments args; 3650 args.push_int(DisplayVMOutputToStderr); 3651 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3652 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3653 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3654 if (result.get_jint() != JNI_OK) { 3655 vm_exit_during_initialization(); // no message or exception 3656 } 3657 3658 universe_post_module_init(); 3659 } 3660 3661 // Phase 3. final setup - set security manager, system class loader and TCCL 3662 // 3663 // This will instantiate and set the security manager, set the system class 3664 // loader as well as the thread context class loader. The security manager 3665 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3666 // other modules or the application's classpath. 3667 static void call_initPhase3(TRAPS) { 3668 Klass* klass = SystemDictionary::System_klass(); 3669 JavaValue result(T_VOID); 3670 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3671 vmSymbols::void_method_signature(), CHECK); 3672 } 3673 3674 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3675 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3676 3677 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3678 create_vm_init_libraries(); 3679 } 3680 3681 initialize_class(vmSymbols::java_lang_String(), CHECK); 3682 3683 // Inject CompactStrings value after the static initializers for String ran. 3684 java_lang_String::set_compact_strings(CompactStrings); 3685 3686 // Initialize java_lang.System (needed before creating the thread) 3687 initialize_class(vmSymbols::java_lang_System(), CHECK); 3688 // The VM creates & returns objects of this class. Make sure it's initialized. 3689 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3690 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3691 Handle thread_group = create_initial_thread_group(CHECK); 3692 Universe::set_main_thread_group(thread_group()); 3693 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3694 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3695 main_thread->set_threadObj(thread_object); 3696 3697 // Set thread status to running since main thread has 3698 // been started and running. 3699 java_lang_Thread::set_thread_status(thread_object, 3700 java_lang_Thread::RUNNABLE); 3701 3702 // The VM creates objects of this class. 3703 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3704 3705 #ifdef ASSERT 3706 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3707 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3708 #endif 3709 3710 // initialize the hardware-specific constants needed by Unsafe 3711 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3712 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3713 3714 // The VM preresolves methods to these classes. Make sure that they get initialized 3715 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3716 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3717 3718 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3719 call_initPhase1(CHECK); 3720 3721 // get the Java runtime name, version, and vendor info after java.lang.System is initialized 3722 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3723 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3724 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD)); 3725 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD)); 3726 3727 // an instance of OutOfMemory exception has been allocated earlier 3728 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3729 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3730 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3731 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3732 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3733 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3734 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3735 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3736 3737 // Eager box cache initialization only if AOT is on and any library is loaded. 3738 AOTLoader::initialize_box_caches(CHECK); 3739 } 3740 3741 void Threads::initialize_jsr292_core_classes(TRAPS) { 3742 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3743 3744 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3745 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3746 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3747 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3748 } 3749 3750 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3751 extern void JDK_Version_init(); 3752 3753 // Preinitialize version info. 3754 VM_Version::early_initialize(); 3755 3756 // Check version 3757 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3758 3759 // Initialize library-based TLS 3760 ThreadLocalStorage::init(); 3761 3762 // Initialize the output stream module 3763 ostream_init(); 3764 3765 // Process java launcher properties. 3766 Arguments::process_sun_java_launcher_properties(args); 3767 3768 // Initialize the os module 3769 os::init(); 3770 3771 // Record VM creation timing statistics 3772 TraceVmCreationTime create_vm_timer; 3773 create_vm_timer.start(); 3774 3775 // Initialize system properties. 3776 Arguments::init_system_properties(); 3777 3778 // So that JDK version can be used as a discriminator when parsing arguments 3779 JDK_Version_init(); 3780 3781 // Update/Initialize System properties after JDK version number is known 3782 Arguments::init_version_specific_system_properties(); 3783 3784 // Make sure to initialize log configuration *before* parsing arguments 3785 LogConfiguration::initialize(create_vm_timer.begin_time()); 3786 3787 // Parse arguments 3788 // Note: this internally calls os::init_container_support() 3789 jint parse_result = Arguments::parse(args); 3790 if (parse_result != JNI_OK) return parse_result; 3791 3792 os::init_before_ergo(); 3793 3794 jint ergo_result = Arguments::apply_ergo(); 3795 if (ergo_result != JNI_OK) return ergo_result; 3796 3797 // Final check of all ranges after ergonomics which may change values. 3798 if (!JVMFlagRangeList::check_ranges()) { 3799 return JNI_EINVAL; 3800 } 3801 3802 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3803 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3804 if (!constraint_result) { 3805 return JNI_EINVAL; 3806 } 3807 3808 if (PauseAtStartup) { 3809 os::pause(); 3810 } 3811 3812 HOTSPOT_VM_INIT_BEGIN(); 3813 3814 // Timing (must come after argument parsing) 3815 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3816 3817 // Initialize the os module after parsing the args 3818 jint os_init_2_result = os::init_2(); 3819 if (os_init_2_result != JNI_OK) return os_init_2_result; 3820 3821 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3822 // Initialize assert poison page mechanism. 3823 if (ShowRegistersOnAssert) { 3824 initialize_assert_poison(); 3825 } 3826 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3827 3828 SafepointMechanism::initialize(); 3829 3830 jint adjust_after_os_result = Arguments::adjust_after_os(); 3831 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3832 3833 // Initialize output stream logging 3834 ostream_init_log(); 3835 3836 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3837 // Must be before create_vm_init_agents() 3838 if (Arguments::init_libraries_at_startup()) { 3839 convert_vm_init_libraries_to_agents(); 3840 } 3841 3842 // Launch -agentlib/-agentpath and converted -Xrun agents 3843 if (Arguments::init_agents_at_startup()) { 3844 create_vm_init_agents(); 3845 } 3846 3847 // Initialize Threads state 3848 _number_of_threads = 0; 3849 _number_of_non_daemon_threads = 0; 3850 3851 // Initialize global data structures and create system classes in heap 3852 vm_init_globals(); 3853 3854 #if INCLUDE_JVMCI 3855 if (JVMCICounterSize > 0) { 3856 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3857 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3858 } else { 3859 JavaThread::_jvmci_old_thread_counters = NULL; 3860 } 3861 #endif // INCLUDE_JVMCI 3862 3863 // Attach the main thread to this os thread 3864 JavaThread* main_thread = new JavaThread(); 3865 main_thread->set_thread_state(_thread_in_vm); 3866 main_thread->initialize_thread_current(); 3867 // must do this before set_active_handles 3868 main_thread->record_stack_base_and_size(); 3869 main_thread->register_thread_stack_with_NMT(); 3870 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3871 3872 if (!main_thread->set_as_starting_thread()) { 3873 vm_shutdown_during_initialization( 3874 "Failed necessary internal allocation. Out of swap space"); 3875 main_thread->smr_delete(); 3876 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3877 return JNI_ENOMEM; 3878 } 3879 3880 // Enable guard page *after* os::create_main_thread(), otherwise it would 3881 // crash Linux VM, see notes in os_linux.cpp. 3882 main_thread->create_stack_guard_pages(); 3883 3884 // Initialize Java-Level synchronization subsystem 3885 ObjectMonitor::Initialize(); 3886 3887 // Initialize global modules 3888 jint status = init_globals(); 3889 if (status != JNI_OK) { 3890 main_thread->smr_delete(); 3891 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3892 return status; 3893 } 3894 3895 JFR_ONLY(Jfr::on_create_vm_1();) 3896 3897 // Should be done after the heap is fully created 3898 main_thread->cache_global_variables(); 3899 3900 HandleMark hm; 3901 3902 { MutexLocker mu(Threads_lock); 3903 Threads::add(main_thread); 3904 } 3905 3906 // Any JVMTI raw monitors entered in onload will transition into 3907 // real raw monitor. VM is setup enough here for raw monitor enter. 3908 JvmtiExport::transition_pending_onload_raw_monitors(); 3909 3910 // Create the VMThread 3911 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3912 3913 VMThread::create(); 3914 Thread* vmthread = VMThread::vm_thread(); 3915 3916 if (!os::create_thread(vmthread, os::vm_thread)) { 3917 vm_exit_during_initialization("Cannot create VM thread. " 3918 "Out of system resources."); 3919 } 3920 3921 // Wait for the VM thread to become ready, and VMThread::run to initialize 3922 // Monitors can have spurious returns, must always check another state flag 3923 { 3924 MonitorLocker ml(Notify_lock); 3925 os::start_thread(vmthread); 3926 while (vmthread->active_handles() == NULL) { 3927 ml.wait(); 3928 } 3929 } 3930 } 3931 3932 assert(Universe::is_fully_initialized(), "not initialized"); 3933 if (VerifyDuringStartup) { 3934 // Make sure we're starting with a clean slate. 3935 VM_Verify verify_op; 3936 VMThread::execute(&verify_op); 3937 } 3938 3939 // We need this to update the java.vm.info property in case any flags used 3940 // to initially define it have been changed. This is needed for both CDS and 3941 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3942 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3943 // This update must happen before we initialize the java classes, but 3944 // after any initialization logic that might modify the flags. 3945 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3946 3947 Thread* THREAD = Thread::current(); 3948 3949 // Always call even when there are not JVMTI environments yet, since environments 3950 // may be attached late and JVMTI must track phases of VM execution 3951 JvmtiExport::enter_early_start_phase(); 3952 3953 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3954 JvmtiExport::post_early_vm_start(); 3955 3956 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3957 3958 quicken_jni_functions(); 3959 3960 // No more stub generation allowed after that point. 3961 StubCodeDesc::freeze(); 3962 3963 // Set flag that basic initialization has completed. Used by exceptions and various 3964 // debug stuff, that does not work until all basic classes have been initialized. 3965 set_init_completed(); 3966 3967 LogConfiguration::post_initialize(); 3968 Metaspace::post_initialize(); 3969 3970 HOTSPOT_VM_INIT_END(); 3971 3972 // record VM initialization completion time 3973 #if INCLUDE_MANAGEMENT 3974 Management::record_vm_init_completed(); 3975 #endif // INCLUDE_MANAGEMENT 3976 3977 // Signal Dispatcher needs to be started before VMInit event is posted 3978 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3979 3980 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3981 if (!DisableAttachMechanism) { 3982 AttachListener::vm_start(); 3983 if (StartAttachListener || AttachListener::init_at_startup()) { 3984 AttachListener::init(); 3985 } 3986 } 3987 3988 // Launch -Xrun agents 3989 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3990 // back-end can launch with -Xdebug -Xrunjdwp. 3991 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3992 create_vm_init_libraries(); 3993 } 3994 3995 if (CleanChunkPoolAsync) { 3996 Chunk::start_chunk_pool_cleaner_task(); 3997 } 3998 3999 // Start the service thread 4000 // The service thread enqueues JVMTI deferred events and does various hashtable 4001 // and other cleanups. Needs to start before the compilers start posting events. 4002 ServiceThread::initialize(); 4003 4004 // initialize compiler(s) 4005 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 4006 #if INCLUDE_JVMCI 4007 bool force_JVMCI_intialization = false; 4008 if (EnableJVMCI) { 4009 // Initialize JVMCI eagerly when it is explicitly requested. 4010 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 4011 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 4012 4013 if (!force_JVMCI_intialization) { 4014 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4015 // compilations via JVMCI will not actually block until JVMCI is initialized. 4016 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4017 } 4018 } 4019 #endif 4020 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 4021 // Postpone completion of compiler initialization to after JVMCI 4022 // is initialized to avoid timeouts of blocking compilations. 4023 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 4024 CompileBroker::compilation_init_phase2(); 4025 } 4026 #endif 4027 4028 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4029 // It is done after compilers are initialized, because otherwise compilations of 4030 // signature polymorphic MH intrinsics can be missed 4031 // (see SystemDictionary::find_method_handle_intrinsic). 4032 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4033 4034 // This will initialize the module system. Only java.base classes can be 4035 // loaded until phase 2 completes 4036 call_initPhase2(CHECK_JNI_ERR); 4037 4038 JFR_ONLY(Jfr::on_create_vm_2();) 4039 4040 // Always call even when there are not JVMTI environments yet, since environments 4041 // may be attached late and JVMTI must track phases of VM execution 4042 JvmtiExport::enter_start_phase(); 4043 4044 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4045 JvmtiExport::post_vm_start(); 4046 4047 // Final system initialization including security manager and system class loader 4048 call_initPhase3(CHECK_JNI_ERR); 4049 4050 // cache the system and platform class loaders 4051 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4052 4053 #if INCLUDE_CDS 4054 // capture the module path info from the ModuleEntryTable 4055 ClassLoader::initialize_module_path(THREAD); 4056 #endif 4057 4058 #if INCLUDE_JVMCI 4059 if (force_JVMCI_intialization) { 4060 JVMCI::initialize_compiler(CHECK_JNI_ERR); 4061 CompileBroker::compilation_init_phase2(); 4062 } 4063 #endif 4064 4065 // Always call even when there are not JVMTI environments yet, since environments 4066 // may be attached late and JVMTI must track phases of VM execution 4067 JvmtiExport::enter_live_phase(); 4068 4069 // Make perfmemory accessible 4070 PerfMemory::set_accessible(true); 4071 4072 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4073 JvmtiExport::post_vm_initialized(); 4074 4075 JFR_ONLY(Jfr::on_create_vm_3();) 4076 4077 #if INCLUDE_MANAGEMENT 4078 Management::initialize(THREAD); 4079 4080 if (HAS_PENDING_EXCEPTION) { 4081 // management agent fails to start possibly due to 4082 // configuration problem and is responsible for printing 4083 // stack trace if appropriate. Simply exit VM. 4084 vm_exit(1); 4085 } 4086 #endif // INCLUDE_MANAGEMENT 4087 4088 if (MemProfiling) MemProfiler::engage(); 4089 StatSampler::engage(); 4090 if (CheckJNICalls) JniPeriodicChecker::engage(); 4091 4092 BiasedLocking::init(); 4093 4094 #if INCLUDE_RTM_OPT 4095 RTMLockingCounters::init(); 4096 #endif 4097 4098 call_postVMInitHook(THREAD); 4099 // The Java side of PostVMInitHook.run must deal with all 4100 // exceptions and provide means of diagnosis. 4101 if (HAS_PENDING_EXCEPTION) { 4102 CLEAR_PENDING_EXCEPTION; 4103 } 4104 4105 { 4106 MutexLocker ml(PeriodicTask_lock); 4107 // Make sure the WatcherThread can be started by WatcherThread::start() 4108 // or by dynamic enrollment. 4109 WatcherThread::make_startable(); 4110 // Start up the WatcherThread if there are any periodic tasks 4111 // NOTE: All PeriodicTasks should be registered by now. If they 4112 // aren't, late joiners might appear to start slowly (we might 4113 // take a while to process their first tick). 4114 if (PeriodicTask::num_tasks() > 0) { 4115 WatcherThread::start(); 4116 } 4117 } 4118 4119 create_vm_timer.end(); 4120 #ifdef ASSERT 4121 _vm_complete = true; 4122 #endif 4123 4124 if (DumpSharedSpaces) { 4125 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4126 ShouldNotReachHere(); 4127 } 4128 4129 return JNI_OK; 4130 } 4131 4132 // type for the Agent_OnLoad and JVM_OnLoad entry points 4133 extern "C" { 4134 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4135 } 4136 // Find a command line agent library and return its entry point for 4137 // -agentlib: -agentpath: -Xrun 4138 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4139 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4140 const char *on_load_symbols[], 4141 size_t num_symbol_entries) { 4142 OnLoadEntry_t on_load_entry = NULL; 4143 void *library = NULL; 4144 4145 if (!agent->valid()) { 4146 char buffer[JVM_MAXPATHLEN]; 4147 char ebuf[1024] = ""; 4148 const char *name = agent->name(); 4149 const char *msg = "Could not find agent library "; 4150 4151 // First check to see if agent is statically linked into executable 4152 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4153 library = agent->os_lib(); 4154 } else if (agent->is_absolute_path()) { 4155 library = os::dll_load(name, ebuf, sizeof ebuf); 4156 if (library == NULL) { 4157 const char *sub_msg = " in absolute path, with error: "; 4158 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4159 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4160 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4161 // If we can't find the agent, exit. 4162 vm_exit_during_initialization(buf, NULL); 4163 FREE_C_HEAP_ARRAY(char, buf); 4164 } 4165 } else { 4166 // Try to load the agent from the standard dll directory 4167 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4168 name)) { 4169 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4170 } 4171 if (library == NULL) { // Try the library path directory. 4172 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4173 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4174 } 4175 if (library == NULL) { 4176 const char *sub_msg = " on the library path, with error: "; 4177 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4178 4179 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4180 strlen(ebuf) + strlen(sub_msg2) + 1; 4181 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4182 if (!agent->is_instrument_lib()) { 4183 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4184 } else { 4185 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4186 } 4187 // If we can't find the agent, exit. 4188 vm_exit_during_initialization(buf, NULL); 4189 FREE_C_HEAP_ARRAY(char, buf); 4190 } 4191 } 4192 } 4193 agent->set_os_lib(library); 4194 agent->set_valid(); 4195 } 4196 4197 // Find the OnLoad function. 4198 on_load_entry = 4199 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4200 false, 4201 on_load_symbols, 4202 num_symbol_entries)); 4203 return on_load_entry; 4204 } 4205 4206 // Find the JVM_OnLoad entry point 4207 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4208 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4209 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4210 } 4211 4212 // Find the Agent_OnLoad entry point 4213 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4214 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4215 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4216 } 4217 4218 // For backwards compatibility with -Xrun 4219 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4220 // treated like -agentpath: 4221 // Must be called before agent libraries are created 4222 void Threads::convert_vm_init_libraries_to_agents() { 4223 AgentLibrary* agent; 4224 AgentLibrary* next; 4225 4226 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4227 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4228 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4229 4230 // If there is an JVM_OnLoad function it will get called later, 4231 // otherwise see if there is an Agent_OnLoad 4232 if (on_load_entry == NULL) { 4233 on_load_entry = lookup_agent_on_load(agent); 4234 if (on_load_entry != NULL) { 4235 // switch it to the agent list -- so that Agent_OnLoad will be called, 4236 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4237 Arguments::convert_library_to_agent(agent); 4238 } else { 4239 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4240 } 4241 } 4242 } 4243 } 4244 4245 // Create agents for -agentlib: -agentpath: and converted -Xrun 4246 // Invokes Agent_OnLoad 4247 // Called very early -- before JavaThreads exist 4248 void Threads::create_vm_init_agents() { 4249 extern struct JavaVM_ main_vm; 4250 AgentLibrary* agent; 4251 4252 JvmtiExport::enter_onload_phase(); 4253 4254 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4255 // CDS dumping does not support native JVMTI agent. 4256 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4257 if (Arguments::is_dumping_archive()) { 4258 if(!agent->is_instrument_lib()) { 4259 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4260 } else if (!AllowArchivingWithJavaAgent) { 4261 vm_exit_during_cds_dumping( 4262 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4263 } 4264 } 4265 4266 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4267 4268 if (on_load_entry != NULL) { 4269 // Invoke the Agent_OnLoad function 4270 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4271 if (err != JNI_OK) { 4272 vm_exit_during_initialization("agent library failed to init", agent->name()); 4273 } 4274 } else { 4275 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4276 } 4277 } 4278 4279 JvmtiExport::enter_primordial_phase(); 4280 } 4281 4282 extern "C" { 4283 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4284 } 4285 4286 void Threads::shutdown_vm_agents() { 4287 // Send any Agent_OnUnload notifications 4288 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4289 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4290 extern struct JavaVM_ main_vm; 4291 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4292 4293 // Find the Agent_OnUnload function. 4294 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4295 os::find_agent_function(agent, 4296 false, 4297 on_unload_symbols, 4298 num_symbol_entries)); 4299 4300 // Invoke the Agent_OnUnload function 4301 if (unload_entry != NULL) { 4302 JavaThread* thread = JavaThread::current(); 4303 ThreadToNativeFromVM ttn(thread); 4304 HandleMark hm(thread); 4305 (*unload_entry)(&main_vm); 4306 } 4307 } 4308 } 4309 4310 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4311 // Invokes JVM_OnLoad 4312 void Threads::create_vm_init_libraries() { 4313 extern struct JavaVM_ main_vm; 4314 AgentLibrary* agent; 4315 4316 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4317 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4318 4319 if (on_load_entry != NULL) { 4320 // Invoke the JVM_OnLoad function 4321 JavaThread* thread = JavaThread::current(); 4322 ThreadToNativeFromVM ttn(thread); 4323 HandleMark hm(thread); 4324 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4325 if (err != JNI_OK) { 4326 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4327 } 4328 } else { 4329 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4330 } 4331 } 4332 } 4333 4334 4335 // Last thread running calls java.lang.Shutdown.shutdown() 4336 void JavaThread::invoke_shutdown_hooks() { 4337 HandleMark hm(this); 4338 4339 // Link all classes for dynamic CDS dumping before vm exit. 4340 // Same operation is being done in JVM_BeforeHalt for handling the 4341 // case where the application calls System.exit(). 4342 if (DynamicDumpSharedSpaces) { 4343 MetaspaceShared::link_and_cleanup_shared_classes(this); 4344 } 4345 4346 // We could get here with a pending exception, if so clear it now. 4347 if (this->has_pending_exception()) { 4348 this->clear_pending_exception(); 4349 } 4350 4351 EXCEPTION_MARK; 4352 Klass* shutdown_klass = 4353 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4354 THREAD); 4355 if (shutdown_klass != NULL) { 4356 // SystemDictionary::resolve_or_null will return null if there was 4357 // an exception. If we cannot load the Shutdown class, just don't 4358 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4359 // won't be run. Note that if a shutdown hook was registered, 4360 // the Shutdown class would have already been loaded 4361 // (Runtime.addShutdownHook will load it). 4362 JavaValue result(T_VOID); 4363 JavaCalls::call_static(&result, 4364 shutdown_klass, 4365 vmSymbols::shutdown_name(), 4366 vmSymbols::void_method_signature(), 4367 THREAD); 4368 } 4369 CLEAR_PENDING_EXCEPTION; 4370 } 4371 4372 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4373 // the program falls off the end of main(). Another VM exit path is through 4374 // vm_exit() when the program calls System.exit() to return a value or when 4375 // there is a serious error in VM. The two shutdown paths are not exactly 4376 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4377 // and VM_Exit op at VM level. 4378 // 4379 // Shutdown sequence: 4380 // + Shutdown native memory tracking if it is on 4381 // + Wait until we are the last non-daemon thread to execute 4382 // <-- every thing is still working at this moment --> 4383 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4384 // shutdown hooks 4385 // + Call before_exit(), prepare for VM exit 4386 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4387 // currently the only user of this mechanism is File.deleteOnExit()) 4388 // > stop StatSampler, watcher thread, 4389 // post thread end and vm death events to JVMTI, 4390 // stop signal thread 4391 // + Call JavaThread::exit(), it will: 4392 // > release JNI handle blocks, remove stack guard pages 4393 // > remove this thread from Threads list 4394 // <-- no more Java code from this thread after this point --> 4395 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4396 // the compiler threads at safepoint 4397 // <-- do not use anything that could get blocked by Safepoint --> 4398 // + Disable tracing at JNI/JVM barriers 4399 // + Set _vm_exited flag for threads that are still running native code 4400 // + Call exit_globals() 4401 // > deletes tty 4402 // > deletes PerfMemory resources 4403 // + Delete this thread 4404 // + Return to caller 4405 4406 bool Threads::destroy_vm() { 4407 JavaThread* thread = JavaThread::current(); 4408 4409 #ifdef ASSERT 4410 _vm_complete = false; 4411 #endif 4412 // Wait until we are the last non-daemon thread to execute 4413 { MonitorLocker nu(Threads_lock); 4414 while (Threads::number_of_non_daemon_threads() > 1) 4415 // This wait should make safepoint checks, wait without a timeout, 4416 // and wait as a suspend-equivalent condition. 4417 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4418 } 4419 4420 EventShutdown e; 4421 if (e.should_commit()) { 4422 e.set_reason("No remaining non-daemon Java threads"); 4423 e.commit(); 4424 } 4425 4426 // Hang forever on exit if we are reporting an error. 4427 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4428 os::infinite_sleep(); 4429 } 4430 os::wait_for_keypress_at_exit(); 4431 4432 // run Java level shutdown hooks 4433 thread->invoke_shutdown_hooks(); 4434 4435 before_exit(thread); 4436 4437 thread->exit(true); 4438 4439 // We are no longer on the main thread list but could still be in a 4440 // secondary list where another thread may try to interact with us. 4441 // So wait until all such interactions are complete before we bring 4442 // the VM to the termination safepoint. Normally this would be done 4443 // using thread->smr_delete() below where we delete the thread, but 4444 // we can't call that after the termination safepoint is active as 4445 // we will deadlock on the Threads_lock. Once all interactions are 4446 // complete it is safe to directly delete the thread at any time. 4447 ThreadsSMRSupport::wait_until_not_protected(thread); 4448 4449 // Stop VM thread. 4450 { 4451 // 4945125 The vm thread comes to a safepoint during exit. 4452 // GC vm_operations can get caught at the safepoint, and the 4453 // heap is unparseable if they are caught. Grab the Heap_lock 4454 // to prevent this. The GC vm_operations will not be able to 4455 // queue until after the vm thread is dead. After this point, 4456 // we'll never emerge out of the safepoint before the VM exits. 4457 4458 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4459 4460 VMThread::wait_for_vm_thread_exit(); 4461 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4462 VMThread::destroy(); 4463 } 4464 4465 // Now, all Java threads are gone except daemon threads. Daemon threads 4466 // running Java code or in VM are stopped by the Safepoint. However, 4467 // daemon threads executing native code are still running. But they 4468 // will be stopped at native=>Java/VM barriers. Note that we can't 4469 // simply kill or suspend them, as it is inherently deadlock-prone. 4470 4471 VM_Exit::set_vm_exited(); 4472 4473 // Clean up ideal graph printers after the VMThread has started 4474 // the final safepoint which will block all the Compiler threads. 4475 // Note that this Thread has already logically exited so the 4476 // clean_up() function's use of a JavaThreadIteratorWithHandle 4477 // would be a problem except set_vm_exited() has remembered the 4478 // shutdown thread which is granted a policy exception. 4479 #if defined(COMPILER2) && !defined(PRODUCT) 4480 IdealGraphPrinter::clean_up(); 4481 #endif 4482 4483 notify_vm_shutdown(); 4484 4485 // exit_globals() will delete tty 4486 exit_globals(); 4487 4488 // Deleting the shutdown thread here is safe. See comment on 4489 // wait_until_not_protected() above. 4490 delete thread; 4491 4492 #if INCLUDE_JVMCI 4493 if (JVMCICounterSize > 0) { 4494 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4495 } 4496 #endif 4497 4498 LogConfiguration::finalize(); 4499 4500 return true; 4501 } 4502 4503 4504 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4505 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4506 return is_supported_jni_version(version); 4507 } 4508 4509 4510 jboolean Threads::is_supported_jni_version(jint version) { 4511 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4512 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4513 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4514 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4515 if (version == JNI_VERSION_9) return JNI_TRUE; 4516 if (version == JNI_VERSION_10) return JNI_TRUE; 4517 return JNI_FALSE; 4518 } 4519 4520 4521 void Threads::add(JavaThread* p, bool force_daemon) { 4522 // The threads lock must be owned at this point 4523 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4524 4525 BarrierSet::barrier_set()->on_thread_attach(p); 4526 4527 // Once a JavaThread is added to the Threads list, smr_delete() has 4528 // to be used to delete it. Otherwise we can just delete it directly. 4529 p->set_on_thread_list(); 4530 4531 _number_of_threads++; 4532 oop threadObj = p->threadObj(); 4533 bool daemon = true; 4534 // Bootstrapping problem: threadObj can be null for initial 4535 // JavaThread (or for threads attached via JNI) 4536 if ((!force_daemon) && !is_daemon((threadObj))) { 4537 _number_of_non_daemon_threads++; 4538 daemon = false; 4539 } 4540 4541 ThreadService::add_thread(p, daemon); 4542 4543 // Maintain fast thread list 4544 ThreadsSMRSupport::add_thread(p); 4545 4546 // Possible GC point. 4547 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4548 } 4549 4550 void Threads::remove(JavaThread* p, bool is_daemon) { 4551 4552 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4553 ObjectSynchronizer::om_flush(p); 4554 4555 // Extra scope needed for Thread_lock, so we can check 4556 // that we do not remove thread without safepoint code notice 4557 { MonitorLocker ml(Threads_lock); 4558 4559 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4560 4561 // Maintain fast thread list 4562 ThreadsSMRSupport::remove_thread(p); 4563 4564 _number_of_threads--; 4565 if (!is_daemon) { 4566 _number_of_non_daemon_threads--; 4567 4568 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4569 // on destroy_vm will wake up. 4570 if (number_of_non_daemon_threads() == 1) { 4571 ml.notify_all(); 4572 } 4573 } 4574 ThreadService::remove_thread(p, is_daemon); 4575 4576 // Make sure that safepoint code disregard this thread. This is needed since 4577 // the thread might mess around with locks after this point. This can cause it 4578 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4579 // of this thread since it is removed from the queue. 4580 p->set_terminated_value(); 4581 } // unlock Threads_lock 4582 4583 // Since Events::log uses a lock, we grab it outside the Threads_lock 4584 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4585 } 4586 4587 // Operations on the Threads list for GC. These are not explicitly locked, 4588 // but the garbage collector must provide a safe context for them to run. 4589 // In particular, these things should never be called when the Threads_lock 4590 // is held by some other thread. (Note: the Safepoint abstraction also 4591 // uses the Threads_lock to guarantee this property. It also makes sure that 4592 // all threads gets blocked when exiting or starting). 4593 4594 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4595 ALL_JAVA_THREADS(p) { 4596 p->oops_do(f, cf); 4597 } 4598 VMThread::vm_thread()->oops_do(f, cf); 4599 } 4600 4601 void Threads::change_thread_claim_token() { 4602 if (++_thread_claim_token == 0) { 4603 // On overflow of the token counter, there is a risk of future 4604 // collisions between a new global token value and a stale token 4605 // for a thread, because not all iterations visit all threads. 4606 // (Though it's pretty much a theoretical concern for non-trivial 4607 // token counter sizes.) To deal with the possibility, reset all 4608 // the thread tokens to zero on global token overflow. 4609 struct ResetClaims : public ThreadClosure { 4610 virtual void do_thread(Thread* t) { 4611 t->claim_threads_do(false, 0); 4612 } 4613 } reset_claims; 4614 Threads::threads_do(&reset_claims); 4615 // On overflow, update the global token to non-zero, to 4616 // avoid the special "never claimed" initial thread value. 4617 _thread_claim_token = 1; 4618 } 4619 } 4620 4621 #ifdef ASSERT 4622 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4623 const uintx token = t->threads_do_token(); 4624 assert(token == expected, 4625 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4626 UINTX_FORMAT, kind, p2i(t), token, expected); 4627 } 4628 4629 void Threads::assert_all_threads_claimed() { 4630 ALL_JAVA_THREADS(p) { 4631 assert_thread_claimed("Thread", p, _thread_claim_token); 4632 } 4633 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4634 } 4635 #endif // ASSERT 4636 4637 class ParallelOopsDoThreadClosure : public ThreadClosure { 4638 private: 4639 OopClosure* _f; 4640 CodeBlobClosure* _cf; 4641 public: 4642 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4643 void do_thread(Thread* t) { 4644 t->oops_do(_f, _cf); 4645 } 4646 }; 4647 4648 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4649 ParallelOopsDoThreadClosure tc(f, cf); 4650 possibly_parallel_threads_do(is_par, &tc); 4651 } 4652 4653 void Threads::nmethods_do(CodeBlobClosure* cf) { 4654 ALL_JAVA_THREADS(p) { 4655 // This is used by the code cache sweeper to mark nmethods that are active 4656 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4657 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4658 if(!p->is_Code_cache_sweeper_thread()) { 4659 p->nmethods_do(cf); 4660 } 4661 } 4662 } 4663 4664 void Threads::metadata_do(MetadataClosure* f) { 4665 ALL_JAVA_THREADS(p) { 4666 p->metadata_do(f); 4667 } 4668 } 4669 4670 class ThreadHandlesClosure : public ThreadClosure { 4671 void (*_f)(Metadata*); 4672 public: 4673 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4674 virtual void do_thread(Thread* thread) { 4675 thread->metadata_handles_do(_f); 4676 } 4677 }; 4678 4679 void Threads::metadata_handles_do(void f(Metadata*)) { 4680 // Only walk the Handles in Thread. 4681 ThreadHandlesClosure handles_closure(f); 4682 threads_do(&handles_closure); 4683 } 4684 4685 // Get count Java threads that are waiting to enter the specified monitor. 4686 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4687 int count, 4688 address monitor) { 4689 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4690 4691 int i = 0; 4692 DO_JAVA_THREADS(t_list, p) { 4693 if (!p->can_call_java()) continue; 4694 4695 address pending = (address)p->current_pending_monitor(); 4696 if (pending == monitor) { // found a match 4697 if (i < count) result->append(p); // save the first count matches 4698 i++; 4699 } 4700 } 4701 4702 return result; 4703 } 4704 4705 4706 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4707 address owner) { 4708 // NULL owner means not locked so we can skip the search 4709 if (owner == NULL) return NULL; 4710 4711 DO_JAVA_THREADS(t_list, p) { 4712 // first, see if owner is the address of a Java thread 4713 if (owner == (address)p) return p; 4714 } 4715 4716 // Cannot assert on lack of success here since this function may be 4717 // used by code that is trying to report useful problem information 4718 // like deadlock detection. 4719 if (UseHeavyMonitors) return NULL; 4720 4721 // If we didn't find a matching Java thread and we didn't force use of 4722 // heavyweight monitors, then the owner is the stack address of the 4723 // Lock Word in the owning Java thread's stack. 4724 // 4725 JavaThread* the_owner = NULL; 4726 DO_JAVA_THREADS(t_list, q) { 4727 if (q->is_lock_owned(owner)) { 4728 the_owner = q; 4729 break; 4730 } 4731 } 4732 4733 // cannot assert on lack of success here; see above comment 4734 return the_owner; 4735 } 4736 4737 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4738 void Threads::print_on(outputStream* st, bool print_stacks, 4739 bool internal_format, bool print_concurrent_locks, 4740 bool print_extended_info) { 4741 char buf[32]; 4742 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4743 4744 st->print_cr("Full thread dump %s (%s %s):", 4745 VM_Version::vm_name(), 4746 VM_Version::vm_release(), 4747 VM_Version::vm_info_string()); 4748 st->cr(); 4749 4750 #if INCLUDE_SERVICES 4751 // Dump concurrent locks 4752 ConcurrentLocksDump concurrent_locks; 4753 if (print_concurrent_locks) { 4754 concurrent_locks.dump_at_safepoint(); 4755 } 4756 #endif // INCLUDE_SERVICES 4757 4758 ThreadsSMRSupport::print_info_on(st); 4759 st->cr(); 4760 4761 ALL_JAVA_THREADS(p) { 4762 ResourceMark rm; 4763 p->print_on(st, print_extended_info); 4764 if (print_stacks) { 4765 if (internal_format) { 4766 p->trace_stack(); 4767 } else { 4768 p->print_stack_on(st); 4769 } 4770 } 4771 st->cr(); 4772 #if INCLUDE_SERVICES 4773 if (print_concurrent_locks) { 4774 concurrent_locks.print_locks_on(p, st); 4775 } 4776 #endif // INCLUDE_SERVICES 4777 } 4778 4779 VMThread::vm_thread()->print_on(st); 4780 st->cr(); 4781 Universe::heap()->print_gc_threads_on(st); 4782 WatcherThread* wt = WatcherThread::watcher_thread(); 4783 if (wt != NULL) { 4784 wt->print_on(st); 4785 st->cr(); 4786 } 4787 4788 st->flush(); 4789 } 4790 4791 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4792 int buflen, bool* found_current) { 4793 if (this_thread != NULL) { 4794 bool is_current = (current == this_thread); 4795 *found_current = *found_current || is_current; 4796 st->print("%s", is_current ? "=>" : " "); 4797 4798 st->print(PTR_FORMAT, p2i(this_thread)); 4799 st->print(" "); 4800 this_thread->print_on_error(st, buf, buflen); 4801 st->cr(); 4802 } 4803 } 4804 4805 class PrintOnErrorClosure : public ThreadClosure { 4806 outputStream* _st; 4807 Thread* _current; 4808 char* _buf; 4809 int _buflen; 4810 bool* _found_current; 4811 public: 4812 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4813 int buflen, bool* found_current) : 4814 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4815 4816 virtual void do_thread(Thread* thread) { 4817 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4818 } 4819 }; 4820 4821 // Threads::print_on_error() is called by fatal error handler. It's possible 4822 // that VM is not at safepoint and/or current thread is inside signal handler. 4823 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4824 // memory (even in resource area), it might deadlock the error handler. 4825 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4826 int buflen) { 4827 ThreadsSMRSupport::print_info_on(st); 4828 st->cr(); 4829 4830 bool found_current = false; 4831 st->print_cr("Java Threads: ( => current thread )"); 4832 ALL_JAVA_THREADS(thread) { 4833 print_on_error(thread, st, current, buf, buflen, &found_current); 4834 } 4835 st->cr(); 4836 4837 st->print_cr("Other Threads:"); 4838 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4839 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4840 4841 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4842 Universe::heap()->gc_threads_do(&print_closure); 4843 4844 if (!found_current) { 4845 st->cr(); 4846 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4847 current->print_on_error(st, buf, buflen); 4848 st->cr(); 4849 } 4850 st->cr(); 4851 4852 st->print_cr("Threads with active compile tasks:"); 4853 print_threads_compiling(st, buf, buflen); 4854 } 4855 4856 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4857 ALL_JAVA_THREADS(thread) { 4858 if (thread->is_Compiler_thread()) { 4859 CompilerThread* ct = (CompilerThread*) thread; 4860 4861 // Keep task in local variable for NULL check. 4862 // ct->_task might be set to NULL by concurring compiler thread 4863 // because it completed the compilation. The task is never freed, 4864 // though, just returned to a free list. 4865 CompileTask* task = ct->task(); 4866 if (task != NULL) { 4867 thread->print_name_on_error(st, buf, buflen); 4868 st->print(" "); 4869 task->print(st, NULL, short_form, true); 4870 } 4871 } 4872 } 4873 } 4874 4875 4876 // Internal SpinLock and Mutex 4877 // Based on ParkEvent 4878 4879 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4880 // 4881 // We employ SpinLocks _only for low-contention, fixed-length 4882 // short-duration critical sections where we're concerned 4883 // about native mutex_t or HotSpot Mutex:: latency. 4884 // The mux construct provides a spin-then-block mutual exclusion 4885 // mechanism. 4886 // 4887 // Testing has shown that contention on the ListLock guarding gFreeList 4888 // is common. If we implement ListLock as a simple SpinLock it's common 4889 // for the JVM to devolve to yielding with little progress. This is true 4890 // despite the fact that the critical sections protected by ListLock are 4891 // extremely short. 4892 // 4893 // TODO-FIXME: ListLock should be of type SpinLock. 4894 // We should make this a 1st-class type, integrated into the lock 4895 // hierarchy as leaf-locks. Critically, the SpinLock structure 4896 // should have sufficient padding to avoid false-sharing and excessive 4897 // cache-coherency traffic. 4898 4899 4900 typedef volatile int SpinLockT; 4901 4902 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4903 if (Atomic::cmpxchg(adr, 0, 1) == 0) { 4904 return; // normal fast-path return 4905 } 4906 4907 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4908 int ctr = 0; 4909 int Yields = 0; 4910 for (;;) { 4911 while (*adr != 0) { 4912 ++ctr; 4913 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4914 if (Yields > 5) { 4915 os::naked_short_sleep(1); 4916 } else { 4917 os::naked_yield(); 4918 ++Yields; 4919 } 4920 } else { 4921 SpinPause(); 4922 } 4923 } 4924 if (Atomic::cmpxchg(adr, 0, 1) == 0) return; 4925 } 4926 } 4927 4928 void Thread::SpinRelease(volatile int * adr) { 4929 assert(*adr != 0, "invariant"); 4930 OrderAccess::fence(); // guarantee at least release consistency. 4931 // Roach-motel semantics. 4932 // It's safe if subsequent LDs and STs float "up" into the critical section, 4933 // but prior LDs and STs within the critical section can't be allowed 4934 // to reorder or float past the ST that releases the lock. 4935 // Loads and stores in the critical section - which appear in program 4936 // order before the store that releases the lock - must also appear 4937 // before the store that releases the lock in memory visibility order. 4938 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4939 // the ST of 0 into the lock-word which releases the lock, so fence 4940 // more than covers this on all platforms. 4941 *adr = 0; 4942 } 4943 4944 // muxAcquire and muxRelease: 4945 // 4946 // * muxAcquire and muxRelease support a single-word lock-word construct. 4947 // The LSB of the word is set IFF the lock is held. 4948 // The remainder of the word points to the head of a singly-linked list 4949 // of threads blocked on the lock. 4950 // 4951 // * The current implementation of muxAcquire-muxRelease uses its own 4952 // dedicated Thread._MuxEvent instance. If we're interested in 4953 // minimizing the peak number of extant ParkEvent instances then 4954 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4955 // as certain invariants were satisfied. Specifically, care would need 4956 // to be taken with regards to consuming unpark() "permits". 4957 // A safe rule of thumb is that a thread would never call muxAcquire() 4958 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4959 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4960 // consume an unpark() permit intended for monitorenter, for instance. 4961 // One way around this would be to widen the restricted-range semaphore 4962 // implemented in park(). Another alternative would be to provide 4963 // multiple instances of the PlatformEvent() for each thread. One 4964 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4965 // 4966 // * Usage: 4967 // -- Only as leaf locks 4968 // -- for short-term locking only as muxAcquire does not perform 4969 // thread state transitions. 4970 // 4971 // Alternatives: 4972 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4973 // but with parking or spin-then-park instead of pure spinning. 4974 // * Use Taura-Oyama-Yonenzawa locks. 4975 // * It's possible to construct a 1-0 lock if we encode the lockword as 4976 // (List,LockByte). Acquire will CAS the full lockword while Release 4977 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4978 // acquiring threads use timers (ParkTimed) to detect and recover from 4979 // the stranding window. Thread/Node structures must be aligned on 256-byte 4980 // boundaries by using placement-new. 4981 // * Augment MCS with advisory back-link fields maintained with CAS(). 4982 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4983 // The validity of the backlinks must be ratified before we trust the value. 4984 // If the backlinks are invalid the exiting thread must back-track through the 4985 // the forward links, which are always trustworthy. 4986 // * Add a successor indication. The LockWord is currently encoded as 4987 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4988 // to provide the usual futile-wakeup optimization. 4989 // See RTStt for details. 4990 // 4991 4992 4993 const intptr_t LOCKBIT = 1; 4994 4995 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4996 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT); 4997 if (w == 0) return; 4998 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4999 return; 5000 } 5001 5002 ParkEvent * const Self = Thread::current()->_MuxEvent; 5003 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 5004 for (;;) { 5005 int its = (os::is_MP() ? 100 : 0) + 1; 5006 5007 // Optional spin phase: spin-then-park strategy 5008 while (--its >= 0) { 5009 w = *Lock; 5010 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5011 return; 5012 } 5013 } 5014 5015 Self->reset(); 5016 Self->OnList = intptr_t(Lock); 5017 // The following fence() isn't _strictly necessary as the subsequent 5018 // CAS() both serializes execution and ratifies the fetched *Lock value. 5019 OrderAccess::fence(); 5020 for (;;) { 5021 w = *Lock; 5022 if ((w & LOCKBIT) == 0) { 5023 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5024 Self->OnList = 0; // hygiene - allows stronger asserts 5025 return; 5026 } 5027 continue; // Interference -- *Lock changed -- Just retry 5028 } 5029 assert(w & LOCKBIT, "invariant"); 5030 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5031 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break; 5032 } 5033 5034 while (Self->OnList != 0) { 5035 Self->park(); 5036 } 5037 } 5038 } 5039 5040 // Release() must extract a successor from the list and then wake that thread. 5041 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5042 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5043 // Release() would : 5044 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5045 // (B) Extract a successor from the private list "in-hand" 5046 // (C) attempt to CAS() the residual back into *Lock over null. 5047 // If there were any newly arrived threads and the CAS() would fail. 5048 // In that case Release() would detach the RATs, re-merge the list in-hand 5049 // with the RATs and repeat as needed. Alternately, Release() might 5050 // detach and extract a successor, but then pass the residual list to the wakee. 5051 // The wakee would be responsible for reattaching and remerging before it 5052 // competed for the lock. 5053 // 5054 // Both "pop" and DMR are immune from ABA corruption -- there can be 5055 // multiple concurrent pushers, but only one popper or detacher. 5056 // This implementation pops from the head of the list. This is unfair, 5057 // but tends to provide excellent throughput as hot threads remain hot. 5058 // (We wake recently run threads first). 5059 // 5060 // All paths through muxRelease() will execute a CAS. 5061 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5062 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5063 // executed within the critical section are complete and globally visible before the 5064 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5065 void Thread::muxRelease(volatile intptr_t * Lock) { 5066 for (;;) { 5067 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0); 5068 assert(w & LOCKBIT, "invariant"); 5069 if (w == LOCKBIT) return; 5070 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5071 assert(List != NULL, "invariant"); 5072 assert(List->OnList == intptr_t(Lock), "invariant"); 5073 ParkEvent * const nxt = List->ListNext; 5074 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5075 5076 // The following CAS() releases the lock and pops the head element. 5077 // The CAS() also ratifies the previously fetched lock-word value. 5078 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) { 5079 continue; 5080 } 5081 List->OnList = 0; 5082 OrderAccess::fence(); 5083 List->unpark(); 5084 return; 5085 } 5086 } 5087 5088 5089 void Threads::verify() { 5090 ALL_JAVA_THREADS(p) { 5091 p->verify(); 5092 } 5093 VMThread* thread = VMThread::vm_thread(); 5094 if (thread != NULL) thread->verify(); 5095 }