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 assert(_stack_base != NULL, "current_stack_base failed for %s", name()); 353 set_stack_size(os::current_stack_size()); 354 355 #ifdef SOLARIS 356 if (os::is_primordial_thread()) { 357 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 358 } 359 #endif 360 361 // Set stack limits after thread is initialized. 362 if (is_Java_thread()) { 363 ((JavaThread*) this)->set_stack_overflow_limit(); 364 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 365 } 366 } 367 368 #if INCLUDE_NMT 369 void Thread::register_thread_stack_with_NMT() { 370 MemTracker::record_thread_stack(stack_end(), stack_size()); 371 } 372 #endif // INCLUDE_NMT 373 374 void Thread::call_run() { 375 DEBUG_ONLY(_run_state = CALL_RUN;) 376 377 // At this point, Thread object should be fully initialized and 378 // Thread::current() should be set. 379 380 assert(Thread::current_or_null() != NULL, "current thread is unset"); 381 assert(Thread::current_or_null() == this, "current thread is wrong"); 382 383 // Perform common initialization actions 384 385 register_thread_stack_with_NMT(); 386 387 JFR_ONLY(Jfr::on_thread_start(this);) 388 389 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 390 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 391 os::current_thread_id(), p2i(stack_end()), 392 p2i(stack_base()), stack_size()/1024); 393 394 // Perform <ChildClass> initialization actions 395 DEBUG_ONLY(_run_state = PRE_RUN;) 396 this->pre_run(); 397 398 // Invoke <ChildClass>::run() 399 DEBUG_ONLY(_run_state = RUN;) 400 this->run(); 401 // Returned from <ChildClass>::run(). Thread finished. 402 403 // Perform common tear-down actions 404 405 assert(Thread::current_or_null() != NULL, "current thread is unset"); 406 assert(Thread::current_or_null() == this, "current thread is wrong"); 407 408 // Perform <ChildClass> tear-down actions 409 DEBUG_ONLY(_run_state = POST_RUN;) 410 this->post_run(); 411 412 // Note: at this point the thread object may already have deleted itself, 413 // so from here on do not dereference *this*. Not all thread types currently 414 // delete themselves when they terminate. But no thread should ever be deleted 415 // asynchronously with respect to its termination - that is what _run_state can 416 // be used to check. 417 418 assert(Thread::current_or_null() == NULL, "current thread still present"); 419 } 420 421 Thread::~Thread() { 422 423 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 424 // get started due to errors etc. Any active thread should at least reach post_run 425 // before it is deleted (usually in post_run()). 426 assert(_run_state == PRE_CALL_RUN || 427 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 428 "_run_state=%d", (int)_run_state); 429 430 // Notify the barrier set that a thread is being destroyed. Note that a barrier 431 // set might not be available if we encountered errors during bootstrapping. 432 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 433 if (barrier_set != NULL) { 434 barrier_set->on_thread_destroy(this); 435 } 436 437 // stack_base can be NULL if the thread is never started or exited before 438 // record_stack_base_and_size called. Although, we would like to ensure 439 // that all started threads do call record_stack_base_and_size(), there is 440 // not proper way to enforce that. 441 #if INCLUDE_NMT 442 if (_stack_base != NULL) { 443 MemTracker::release_thread_stack(stack_end(), stack_size()); 444 #ifdef ASSERT 445 set_stack_base(NULL); 446 #endif 447 } 448 #endif // INCLUDE_NMT 449 450 // deallocate data structures 451 delete resource_area(); 452 // since the handle marks are using the handle area, we have to deallocated the root 453 // handle mark before deallocating the thread's handle area, 454 assert(last_handle_mark() != NULL, "check we have an element"); 455 delete last_handle_mark(); 456 assert(last_handle_mark() == NULL, "check we have reached the end"); 457 458 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 459 // We NULL out the fields for good hygiene. 460 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 461 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 462 463 delete handle_area(); 464 delete metadata_handles(); 465 466 // SR_handler uses this as a termination indicator - 467 // needs to happen before os::free_thread() 468 delete _SR_lock; 469 _SR_lock = NULL; 470 471 // osthread() can be NULL, if creation of thread failed. 472 if (osthread() != NULL) os::free_thread(osthread()); 473 474 // Clear Thread::current if thread is deleting itself and it has not 475 // already been done. This must be done before the memory is deallocated. 476 // Needed to ensure JNI correctly detects non-attached threads. 477 if (this == Thread::current_or_null()) { 478 Thread::clear_thread_current(); 479 } 480 481 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 482 } 483 484 #ifdef ASSERT 485 // A JavaThread is considered "dangling" if it is not the current 486 // thread, has been added the Threads list, the system is not at a 487 // safepoint and the Thread is not "protected". 488 // 489 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 490 assert(!thread->is_Java_thread() || Thread::current() == thread || 491 !((JavaThread *) thread)->on_thread_list() || 492 SafepointSynchronize::is_at_safepoint() || 493 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 494 "possibility of dangling Thread pointer"); 495 } 496 #endif 497 498 ThreadPriority Thread::get_priority(const Thread* const thread) { 499 ThreadPriority priority; 500 // Can return an error! 501 (void)os::get_priority(thread, priority); 502 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 503 return priority; 504 } 505 506 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 507 debug_only(check_for_dangling_thread_pointer(thread);) 508 // Can return an error! 509 (void)os::set_priority(thread, priority); 510 } 511 512 513 void Thread::start(Thread* thread) { 514 // Start is different from resume in that its safety is guaranteed by context or 515 // being called from a Java method synchronized on the Thread object. 516 if (!DisableStartThread) { 517 if (thread->is_Java_thread()) { 518 // Initialize the thread state to RUNNABLE before starting this thread. 519 // Can not set it after the thread started because we do not know the 520 // exact thread state at that time. It could be in MONITOR_WAIT or 521 // in SLEEPING or some other state. 522 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 523 java_lang_Thread::RUNNABLE); 524 } 525 os::start_thread(thread); 526 } 527 } 528 529 class InstallAsyncExceptionClosure : public HandshakeClosure { 530 Handle _throwable; // The Throwable thrown at the target Thread 531 public: 532 InstallAsyncExceptionClosure(Handle throwable) : HandshakeClosure("InstallAsyncException"), _throwable(throwable) {} 533 534 void do_thread(Thread* thr) { 535 JavaThread* target = (JavaThread*)thr; 536 // Note that this now allows multiple ThreadDeath exceptions to be 537 // thrown at a thread. 538 // The target thread has run and has not exited yet. 539 target->send_thread_stop(_throwable()); 540 } 541 }; 542 543 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 544 Handle throwable(Thread::current(), java_throwable); 545 JavaThread* target = java_lang_Thread::thread(java_thread); 546 InstallAsyncExceptionClosure vm_stop(throwable); 547 Handshake::execute(&vm_stop, target); 548 } 549 550 551 // Check if an external suspend request has completed (or has been 552 // cancelled). Returns true if the thread is externally suspended and 553 // false otherwise. 554 // 555 // The bits parameter returns information about the code path through 556 // the routine. Useful for debugging: 557 // 558 // set in is_ext_suspend_completed(): 559 // 0x00000001 - routine was entered 560 // 0x00000010 - routine return false at end 561 // 0x00000100 - thread exited (return false) 562 // 0x00000200 - suspend request cancelled (return false) 563 // 0x00000400 - thread suspended (return true) 564 // 0x00001000 - thread is in a suspend equivalent state (return true) 565 // 0x00002000 - thread is native and walkable (return true) 566 // 0x00004000 - thread is native_trans and walkable (needed retry) 567 // 568 // set in wait_for_ext_suspend_completion(): 569 // 0x00010000 - routine was entered 570 // 0x00020000 - suspend request cancelled before loop (return false) 571 // 0x00040000 - thread suspended before loop (return true) 572 // 0x00080000 - suspend request cancelled in loop (return false) 573 // 0x00100000 - thread suspended in loop (return true) 574 // 0x00200000 - suspend not completed during retry loop (return false) 575 576 // Helper class for tracing suspend wait debug bits. 577 // 578 // 0x00000100 indicates that the target thread exited before it could 579 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 580 // 0x00080000 each indicate a cancelled suspend request so they don't 581 // count as wait failures either. 582 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 583 584 class TraceSuspendDebugBits : public StackObj { 585 private: 586 JavaThread * jt; 587 bool is_wait; 588 bool called_by_wait; // meaningful when !is_wait 589 uint32_t * bits; 590 591 public: 592 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 593 uint32_t *_bits) { 594 jt = _jt; 595 is_wait = _is_wait; 596 called_by_wait = _called_by_wait; 597 bits = _bits; 598 } 599 600 ~TraceSuspendDebugBits() { 601 if (!is_wait) { 602 #if 1 603 // By default, don't trace bits for is_ext_suspend_completed() calls. 604 // That trace is very chatty. 605 return; 606 #else 607 if (!called_by_wait) { 608 // If tracing for is_ext_suspend_completed() is enabled, then only 609 // trace calls to it from wait_for_ext_suspend_completion() 610 return; 611 } 612 #endif 613 } 614 615 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 616 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 617 MutexLocker ml(Threads_lock); // needed for get_thread_name() 618 ResourceMark rm; 619 620 tty->print_cr( 621 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 622 jt->get_thread_name(), *bits); 623 624 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 625 } 626 } 627 } 628 }; 629 #undef DEBUG_FALSE_BITS 630 631 632 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 633 uint32_t *bits) { 634 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 635 636 bool did_trans_retry = false; // only do thread_in_native_trans retry once 637 bool do_trans_retry; // flag to force the retry 638 639 *bits |= 0x00000001; 640 641 do { 642 do_trans_retry = false; 643 644 if (is_exiting()) { 645 // Thread is in the process of exiting. This is always checked 646 // first to reduce the risk of dereferencing a freed JavaThread. 647 *bits |= 0x00000100; 648 return false; 649 } 650 651 if (!is_external_suspend()) { 652 // Suspend request is cancelled. This is always checked before 653 // is_ext_suspended() to reduce the risk of a rogue resume 654 // confusing the thread that made the suspend request. 655 *bits |= 0x00000200; 656 return false; 657 } 658 659 if (is_ext_suspended()) { 660 // thread is suspended 661 *bits |= 0x00000400; 662 return true; 663 } 664 665 // Now that we no longer do hard suspends of threads running 666 // native code, the target thread can be changing thread state 667 // while we are in this routine: 668 // 669 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 670 // 671 // We save a copy of the thread state as observed at this moment 672 // and make our decision about suspend completeness based on the 673 // copy. This closes the race where the thread state is seen as 674 // _thread_in_native_trans in the if-thread_blocked check, but is 675 // seen as _thread_blocked in if-thread_in_native_trans check. 676 JavaThreadState save_state = thread_state(); 677 678 if (save_state == _thread_blocked && is_suspend_equivalent()) { 679 // If the thread's state is _thread_blocked and this blocking 680 // condition is known to be equivalent to a suspend, then we can 681 // consider the thread to be externally suspended. This means that 682 // the code that sets _thread_blocked has been modified to do 683 // self-suspension if the blocking condition releases. We also 684 // used to check for CONDVAR_WAIT here, but that is now covered by 685 // the _thread_blocked with self-suspension check. 686 // 687 // Return true since we wouldn't be here unless there was still an 688 // external suspend request. 689 *bits |= 0x00001000; 690 return true; 691 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 692 // Threads running native code will self-suspend on native==>VM/Java 693 // transitions. If its stack is walkable (should always be the case 694 // unless this function is called before the actual java_suspend() 695 // call), then the wait is done. 696 *bits |= 0x00002000; 697 return true; 698 } else if (!called_by_wait && !did_trans_retry && 699 save_state == _thread_in_native_trans && 700 frame_anchor()->walkable()) { 701 // The thread is transitioning from thread_in_native to another 702 // thread state. check_safepoint_and_suspend_for_native_trans() 703 // will force the thread to self-suspend. If it hasn't gotten 704 // there yet we may have caught the thread in-between the native 705 // code check above and the self-suspend. Lucky us. If we were 706 // called by wait_for_ext_suspend_completion(), then it 707 // will be doing the retries so we don't have to. 708 // 709 // Since we use the saved thread state in the if-statement above, 710 // there is a chance that the thread has already transitioned to 711 // _thread_blocked by the time we get here. In that case, we will 712 // make a single unnecessary pass through the logic below. This 713 // doesn't hurt anything since we still do the trans retry. 714 715 *bits |= 0x00004000; 716 717 // Once the thread leaves thread_in_native_trans for another 718 // thread state, we break out of this retry loop. We shouldn't 719 // need this flag to prevent us from getting back here, but 720 // sometimes paranoia is good. 721 did_trans_retry = true; 722 723 // We wait for the thread to transition to a more usable state. 724 for (int i = 1; i <= SuspendRetryCount; i++) { 725 // We used to do an "os::yield_all(i)" call here with the intention 726 // that yielding would increase on each retry. However, the parameter 727 // is ignored on Linux which means the yield didn't scale up. Waiting 728 // on the SR_lock below provides a much more predictable scale up for 729 // the delay. It also provides a simple/direct point to check for any 730 // safepoint requests from the VMThread 731 732 // temporarily drops SR_lock while doing wait with safepoint check 733 // (if we're a JavaThread - the WatcherThread can also call this) 734 // and increase delay with each retry 735 if (Thread::current()->is_Java_thread()) { 736 SR_lock()->wait(i * delay); 737 } else { 738 SR_lock()->wait_without_safepoint_check(i * delay); 739 } 740 741 // check the actual thread state instead of what we saved above 742 if (thread_state() != _thread_in_native_trans) { 743 // the thread has transitioned to another thread state so 744 // try all the checks (except this one) one more time. 745 do_trans_retry = true; 746 break; 747 } 748 } // end retry loop 749 750 751 } 752 } while (do_trans_retry); 753 754 *bits |= 0x00000010; 755 return false; 756 } 757 758 // Wait for an external suspend request to complete (or be cancelled). 759 // Returns true if the thread is externally suspended and false otherwise. 760 // 761 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 762 uint32_t *bits) { 763 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 764 false /* !called_by_wait */, bits); 765 766 // local flag copies to minimize SR_lock hold time 767 bool is_suspended; 768 bool pending; 769 uint32_t reset_bits; 770 771 // set a marker so is_ext_suspend_completed() knows we are the caller 772 *bits |= 0x00010000; 773 774 // We use reset_bits to reinitialize the bits value at the top of 775 // each retry loop. This allows the caller to make use of any 776 // unused bits for their own marking purposes. 777 reset_bits = *bits; 778 779 { 780 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 781 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 782 delay, bits); 783 pending = is_external_suspend(); 784 } 785 // must release SR_lock to allow suspension to complete 786 787 if (!pending) { 788 // A cancelled suspend request is the only false return from 789 // is_ext_suspend_completed() that keeps us from entering the 790 // retry loop. 791 *bits |= 0x00020000; 792 return false; 793 } 794 795 if (is_suspended) { 796 *bits |= 0x00040000; 797 return true; 798 } 799 800 for (int i = 1; i <= retries; i++) { 801 *bits = reset_bits; // reinit to only track last retry 802 803 // We used to do an "os::yield_all(i)" call here with the intention 804 // that yielding would increase on each retry. However, the parameter 805 // is ignored on Linux which means the yield didn't scale up. Waiting 806 // on the SR_lock below provides a much more predictable scale up for 807 // the delay. It also provides a simple/direct point to check for any 808 // safepoint requests from the VMThread 809 810 { 811 Thread* t = Thread::current(); 812 MonitorLocker ml(SR_lock(), 813 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 814 // wait with safepoint check (if we're a JavaThread - the WatcherThread 815 // can also call this) and increase delay with each retry 816 ml.wait(i * delay); 817 818 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 819 delay, bits); 820 821 // It is possible for the external suspend request to be cancelled 822 // (by a resume) before the actual suspend operation is completed. 823 // Refresh our local copy to see if we still need to wait. 824 pending = is_external_suspend(); 825 } 826 827 if (!pending) { 828 // A cancelled suspend request is the only false return from 829 // is_ext_suspend_completed() that keeps us from staying in the 830 // retry loop. 831 *bits |= 0x00080000; 832 return false; 833 } 834 835 if (is_suspended) { 836 *bits |= 0x00100000; 837 return true; 838 } 839 } // end retry loop 840 841 // thread did not suspend after all our retries 842 *bits |= 0x00200000; 843 return false; 844 } 845 846 // Called from API entry points which perform stack walking. If the 847 // associated JavaThread is the current thread, then wait_for_suspend 848 // is not used. Otherwise, it determines if we should wait for the 849 // "other" thread to complete external suspension. (NOTE: in future 850 // releases the suspension mechanism should be reimplemented so this 851 // is not necessary.) 852 // 853 bool 854 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 855 if (this != JavaThread::current()) { 856 // "other" threads require special handling. 857 if (wait_for_suspend) { 858 // We are allowed to wait for the external suspend to complete 859 // so give the other thread a chance to get suspended. 860 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 861 SuspendRetryDelay, bits)) { 862 // Didn't make it so let the caller know. 863 return false; 864 } 865 } 866 // We aren't allowed to wait for the external suspend to complete 867 // so if the other thread isn't externally suspended we need to 868 // let the caller know. 869 else if (!is_ext_suspend_completed_with_lock(bits)) { 870 return false; 871 } 872 } 873 874 return true; 875 } 876 877 // GC Support 878 bool Thread::claim_par_threads_do(uintx claim_token) { 879 uintx token = _threads_do_token; 880 if (token != claim_token) { 881 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token); 882 if (res == token) { 883 return true; 884 } 885 guarantee(res == claim_token, "invariant"); 886 } 887 return false; 888 } 889 890 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 891 if (active_handles() != NULL) { 892 active_handles()->oops_do(f); 893 } 894 // Do oop for ThreadShadow 895 f->do_oop((oop*)&_pending_exception); 896 handle_area()->oops_do(f); 897 898 // We scan thread local monitor lists here, and the remaining global 899 // monitors in ObjectSynchronizer::oops_do(). 900 ObjectSynchronizer::thread_local_used_oops_do(this, f); 901 } 902 903 void Thread::metadata_handles_do(void f(Metadata*)) { 904 // Only walk the Handles in Thread. 905 if (metadata_handles() != NULL) { 906 for (int i = 0; i< metadata_handles()->length(); i++) { 907 f(metadata_handles()->at(i)); 908 } 909 } 910 } 911 912 void Thread::print_on(outputStream* st, bool print_extended_info) const { 913 // get_priority assumes osthread initialized 914 if (osthread() != NULL) { 915 int os_prio; 916 if (os::get_native_priority(this, &os_prio) == OS_OK) { 917 st->print("os_prio=%d ", os_prio); 918 } 919 920 st->print("cpu=%.2fms ", 921 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 922 ); 923 st->print("elapsed=%.2fs ", 924 _statistical_info.getElapsedTime() / 1000.0 925 ); 926 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 927 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 928 st->print("allocated=" SIZE_FORMAT "%s ", 929 byte_size_in_proper_unit(allocated_bytes), 930 proper_unit_for_byte_size(allocated_bytes) 931 ); 932 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 933 } 934 935 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 936 osthread()->print_on(st); 937 } 938 ThreadsSMRSupport::print_info_on(this, st); 939 st->print(" "); 940 debug_only(if (WizardMode) print_owned_locks_on(st);) 941 } 942 943 void Thread::print() const { print_on(tty); } 944 945 // Thread::print_on_error() is called by fatal error handler. Don't use 946 // any lock or allocate memory. 947 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 948 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 949 950 if (is_VM_thread()) { st->print("VMThread"); } 951 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 952 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 953 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 954 else { st->print("Thread"); } 955 956 if (is_Named_thread()) { 957 st->print(" \"%s\"", name()); 958 } 959 960 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 961 p2i(stack_end()), p2i(stack_base())); 962 963 if (osthread()) { 964 st->print(" [id=%d]", osthread()->thread_id()); 965 } 966 967 ThreadsSMRSupport::print_info_on(this, st); 968 } 969 970 void Thread::print_value_on(outputStream* st) const { 971 if (is_Named_thread()) { 972 st->print(" \"%s\" ", name()); 973 } 974 st->print(INTPTR_FORMAT, p2i(this)); // print address 975 } 976 977 #ifdef ASSERT 978 void Thread::print_owned_locks_on(outputStream* st) const { 979 Mutex* cur = _owned_locks; 980 if (cur == NULL) { 981 st->print(" (no locks) "); 982 } else { 983 st->print_cr(" Locks owned:"); 984 while (cur) { 985 cur->print_on(st); 986 cur = cur->next(); 987 } 988 } 989 } 990 991 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 992 void Thread::check_possible_safepoint() { 993 if (!is_Java_thread()) return; 994 995 if (_no_safepoint_count > 0) { 996 print_owned_locks(); 997 fatal("Possible safepoint reached by thread that does not allow it"); 998 } 999 #ifdef CHECK_UNHANDLED_OOPS 1000 // Clear unhandled oops in JavaThreads so we get a crash right away. 1001 clear_unhandled_oops(); 1002 #endif // CHECK_UNHANDLED_OOPS 1003 } 1004 1005 void Thread::check_for_valid_safepoint_state() { 1006 if (!is_Java_thread()) return; 1007 1008 // Check NoSafepointVerifier, which is implied by locks taken that can be 1009 // shared with the VM thread. This makes sure that no locks with allow_vm_block 1010 // are held. 1011 check_possible_safepoint(); 1012 1013 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 1014 fatal("LEAF method calling lock?"); 1015 } 1016 1017 if (GCALotAtAllSafepoints) { 1018 // We could enter a safepoint here and thus have a gc 1019 InterfaceSupport::check_gc_alot(); 1020 } 1021 } 1022 #endif // ASSERT 1023 1024 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1025 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1026 // used for compilation in the future. If that change is made, the need for these methods 1027 // should be revisited, and they should be removed if possible. 1028 1029 bool Thread::is_lock_owned(address adr) const { 1030 return is_in_full_stack(adr); 1031 } 1032 1033 bool Thread::set_as_starting_thread() { 1034 assert(_starting_thread == NULL, "already initialized: " 1035 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1036 // NOTE: this must be called inside the main thread. 1037 DEBUG_ONLY(_starting_thread = this;) 1038 return os::create_main_thread((JavaThread*)this); 1039 } 1040 1041 static void initialize_class(Symbol* class_name, TRAPS) { 1042 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1043 InstanceKlass::cast(klass)->initialize(CHECK); 1044 } 1045 1046 1047 // Creates the initial ThreadGroup 1048 static Handle create_initial_thread_group(TRAPS) { 1049 Handle system_instance = JavaCalls::construct_new_instance( 1050 SystemDictionary::ThreadGroup_klass(), 1051 vmSymbols::void_method_signature(), 1052 CHECK_NH); 1053 Universe::set_system_thread_group(system_instance()); 1054 1055 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1056 Handle main_instance = JavaCalls::construct_new_instance( 1057 SystemDictionary::ThreadGroup_klass(), 1058 vmSymbols::threadgroup_string_void_signature(), 1059 system_instance, 1060 string, 1061 CHECK_NH); 1062 return main_instance; 1063 } 1064 1065 // Creates the initial Thread 1066 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1067 TRAPS) { 1068 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1069 assert(ik->is_initialized(), "must be"); 1070 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1071 1072 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1073 // constructor calls Thread.current(), which must be set here for the 1074 // initial thread. 1075 java_lang_Thread::set_thread(thread_oop(), thread); 1076 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1077 thread->set_threadObj(thread_oop()); 1078 1079 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1080 1081 JavaValue result(T_VOID); 1082 JavaCalls::call_special(&result, thread_oop, 1083 ik, 1084 vmSymbols::object_initializer_name(), 1085 vmSymbols::threadgroup_string_void_signature(), 1086 thread_group, 1087 string, 1088 CHECK_NULL); 1089 return thread_oop(); 1090 } 1091 1092 char java_runtime_name[128] = ""; 1093 char java_runtime_version[128] = ""; 1094 char java_runtime_vendor_version[128] = ""; 1095 char java_runtime_vendor_vm_bug_url[128] = ""; 1096 1097 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1098 static const char* get_java_runtime_name(TRAPS) { 1099 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1100 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1101 fieldDescriptor fd; 1102 bool found = k != NULL && 1103 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1104 vmSymbols::string_signature(), &fd); 1105 if (found) { 1106 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1107 if (name_oop == NULL) { 1108 return NULL; 1109 } 1110 const char* name = java_lang_String::as_utf8_string(name_oop, 1111 java_runtime_name, 1112 sizeof(java_runtime_name)); 1113 return name; 1114 } else { 1115 return NULL; 1116 } 1117 } 1118 1119 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1120 static const char* get_java_runtime_version(TRAPS) { 1121 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1122 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1123 fieldDescriptor fd; 1124 bool found = k != NULL && 1125 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1126 vmSymbols::string_signature(), &fd); 1127 if (found) { 1128 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1129 if (name_oop == NULL) { 1130 return NULL; 1131 } 1132 const char* name = java_lang_String::as_utf8_string(name_oop, 1133 java_runtime_version, 1134 sizeof(java_runtime_version)); 1135 return name; 1136 } else { 1137 return NULL; 1138 } 1139 } 1140 1141 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION 1142 static const char* get_java_runtime_vendor_version(TRAPS) { 1143 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1144 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1145 fieldDescriptor fd; 1146 bool found = k != NULL && 1147 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(), 1148 vmSymbols::string_signature(), &fd); 1149 if (found) { 1150 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1151 if (name_oop == NULL) { 1152 return NULL; 1153 } 1154 const char* name = java_lang_String::as_utf8_string(name_oop, 1155 java_runtime_vendor_version, 1156 sizeof(java_runtime_vendor_version)); 1157 return name; 1158 } else { 1159 return NULL; 1160 } 1161 } 1162 1163 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG 1164 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) { 1165 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1166 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1167 fieldDescriptor fd; 1168 bool found = k != NULL && 1169 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(), 1170 vmSymbols::string_signature(), &fd); 1171 if (found) { 1172 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1173 if (name_oop == NULL) { 1174 return NULL; 1175 } 1176 const char* name = java_lang_String::as_utf8_string(name_oop, 1177 java_runtime_vendor_vm_bug_url, 1178 sizeof(java_runtime_vendor_vm_bug_url)); 1179 return name; 1180 } else { 1181 return NULL; 1182 } 1183 } 1184 1185 // General purpose hook into Java code, run once when the VM is initialized. 1186 // The Java library method itself may be changed independently from the VM. 1187 static void call_postVMInitHook(TRAPS) { 1188 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1189 if (klass != NULL) { 1190 JavaValue result(T_VOID); 1191 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1192 vmSymbols::void_method_signature(), 1193 CHECK); 1194 } 1195 } 1196 1197 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1198 bool daemon, TRAPS) { 1199 assert(thread_group.not_null(), "thread group should be specified"); 1200 assert(threadObj() == NULL, "should only create Java thread object once"); 1201 1202 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1203 assert(ik->is_initialized(), "must be"); 1204 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1205 1206 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1207 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1208 // constructor calls Thread.current(), which must be set here. 1209 java_lang_Thread::set_thread(thread_oop(), this); 1210 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1211 set_threadObj(thread_oop()); 1212 1213 JavaValue result(T_VOID); 1214 if (thread_name != NULL) { 1215 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1216 // Thread gets assigned specified name and null target 1217 JavaCalls::call_special(&result, 1218 thread_oop, 1219 ik, 1220 vmSymbols::object_initializer_name(), 1221 vmSymbols::threadgroup_string_void_signature(), 1222 thread_group, 1223 name, 1224 THREAD); 1225 } else { 1226 // Thread gets assigned name "Thread-nnn" and null target 1227 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1228 JavaCalls::call_special(&result, 1229 thread_oop, 1230 ik, 1231 vmSymbols::object_initializer_name(), 1232 vmSymbols::threadgroup_runnable_void_signature(), 1233 thread_group, 1234 Handle(), 1235 THREAD); 1236 } 1237 1238 1239 if (daemon) { 1240 java_lang_Thread::set_daemon(thread_oop()); 1241 } 1242 1243 if (HAS_PENDING_EXCEPTION) { 1244 return; 1245 } 1246 1247 Klass* group = SystemDictionary::ThreadGroup_klass(); 1248 Handle threadObj(THREAD, this->threadObj()); 1249 1250 JavaCalls::call_special(&result, 1251 thread_group, 1252 group, 1253 vmSymbols::add_method_name(), 1254 vmSymbols::thread_void_signature(), 1255 threadObj, // Arg 1 1256 THREAD); 1257 } 1258 1259 // List of all NonJavaThreads and safe iteration over that list. 1260 1261 class NonJavaThread::List { 1262 public: 1263 NonJavaThread* volatile _head; 1264 SingleWriterSynchronizer _protect; 1265 1266 List() : _head(NULL), _protect() {} 1267 }; 1268 1269 NonJavaThread::List NonJavaThread::_the_list; 1270 1271 NonJavaThread::Iterator::Iterator() : 1272 _protect_enter(_the_list._protect.enter()), 1273 _current(Atomic::load_acquire(&_the_list._head)) 1274 {} 1275 1276 NonJavaThread::Iterator::~Iterator() { 1277 _the_list._protect.exit(_protect_enter); 1278 } 1279 1280 void NonJavaThread::Iterator::step() { 1281 assert(!end(), "precondition"); 1282 _current = Atomic::load_acquire(&_current->_next); 1283 } 1284 1285 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1286 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1287 } 1288 1289 NonJavaThread::~NonJavaThread() { } 1290 1291 void NonJavaThread::add_to_the_list() { 1292 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1293 // Initialize BarrierSet-related data before adding to list. 1294 BarrierSet::barrier_set()->on_thread_attach(this); 1295 Atomic::release_store(&_next, _the_list._head); 1296 Atomic::release_store(&_the_list._head, this); 1297 } 1298 1299 void NonJavaThread::remove_from_the_list() { 1300 { 1301 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1302 // Cleanup BarrierSet-related data before removing from list. 1303 BarrierSet::barrier_set()->on_thread_detach(this); 1304 NonJavaThread* volatile* p = &_the_list._head; 1305 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1306 if (t == this) { 1307 *p = _next; 1308 break; 1309 } 1310 } 1311 } 1312 // Wait for any in-progress iterators. Concurrent synchronize is not 1313 // allowed, so do it while holding a dedicated lock. Outside and distinct 1314 // from NJTList_lock in case an iteration attempts to lock it. 1315 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1316 _the_list._protect.synchronize(); 1317 _next = NULL; // Safe to drop the link now. 1318 } 1319 1320 void NonJavaThread::pre_run() { 1321 add_to_the_list(); 1322 1323 // This is slightly odd in that NamedThread is a subclass, but 1324 // in fact name() is defined in Thread 1325 assert(this->name() != NULL, "thread name was not set before it was started"); 1326 this->set_native_thread_name(this->name()); 1327 } 1328 1329 void NonJavaThread::post_run() { 1330 JFR_ONLY(Jfr::on_thread_exit(this);) 1331 remove_from_the_list(); 1332 // Ensure thread-local-storage is cleared before termination. 1333 Thread::clear_thread_current(); 1334 } 1335 1336 // NamedThread -- non-JavaThread subclasses with multiple 1337 // uniquely named instances should derive from this. 1338 NamedThread::NamedThread() : 1339 NonJavaThread(), 1340 _name(NULL), 1341 _processed_thread(NULL), 1342 _gc_id(GCId::undefined()) 1343 {} 1344 1345 NamedThread::~NamedThread() { 1346 FREE_C_HEAP_ARRAY(char, _name); 1347 } 1348 1349 void NamedThread::set_name(const char* format, ...) { 1350 guarantee(_name == NULL, "Only get to set name once."); 1351 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1352 va_list ap; 1353 va_start(ap, format); 1354 jio_vsnprintf(_name, max_name_len, format, ap); 1355 va_end(ap); 1356 } 1357 1358 void NamedThread::print_on(outputStream* st) const { 1359 st->print("\"%s\" ", name()); 1360 Thread::print_on(st); 1361 st->cr(); 1362 } 1363 1364 1365 // ======= WatcherThread ======== 1366 1367 // The watcher thread exists to simulate timer interrupts. It should 1368 // be replaced by an abstraction over whatever native support for 1369 // timer interrupts exists on the platform. 1370 1371 WatcherThread* WatcherThread::_watcher_thread = NULL; 1372 bool WatcherThread::_startable = false; 1373 volatile bool WatcherThread::_should_terminate = false; 1374 1375 WatcherThread::WatcherThread() : NonJavaThread() { 1376 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1377 if (os::create_thread(this, os::watcher_thread)) { 1378 _watcher_thread = this; 1379 1380 // Set the watcher thread to the highest OS priority which should not be 1381 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1382 // is created. The only normal thread using this priority is the reference 1383 // handler thread, which runs for very short intervals only. 1384 // If the VMThread's priority is not lower than the WatcherThread profiling 1385 // will be inaccurate. 1386 os::set_priority(this, MaxPriority); 1387 if (!DisableStartThread) { 1388 os::start_thread(this); 1389 } 1390 } 1391 } 1392 1393 int WatcherThread::sleep() const { 1394 // The WatcherThread does not participate in the safepoint protocol 1395 // for the PeriodicTask_lock because it is not a JavaThread. 1396 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1397 1398 if (_should_terminate) { 1399 // check for termination before we do any housekeeping or wait 1400 return 0; // we did not sleep. 1401 } 1402 1403 // remaining will be zero if there are no tasks, 1404 // causing the WatcherThread to sleep until a task is 1405 // enrolled 1406 int remaining = PeriodicTask::time_to_wait(); 1407 int time_slept = 0; 1408 1409 // we expect this to timeout - we only ever get unparked when 1410 // we should terminate or when a new task has been enrolled 1411 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1412 1413 jlong time_before_loop = os::javaTimeNanos(); 1414 1415 while (true) { 1416 bool timedout = ml.wait(remaining); 1417 jlong now = os::javaTimeNanos(); 1418 1419 if (remaining == 0) { 1420 // if we didn't have any tasks we could have waited for a long time 1421 // consider the time_slept zero and reset time_before_loop 1422 time_slept = 0; 1423 time_before_loop = now; 1424 } else { 1425 // need to recalculate since we might have new tasks in _tasks 1426 time_slept = (int) ((now - time_before_loop) / 1000000); 1427 } 1428 1429 // Change to task list or spurious wakeup of some kind 1430 if (timedout || _should_terminate) { 1431 break; 1432 } 1433 1434 remaining = PeriodicTask::time_to_wait(); 1435 if (remaining == 0) { 1436 // Last task was just disenrolled so loop around and wait until 1437 // another task gets enrolled 1438 continue; 1439 } 1440 1441 remaining -= time_slept; 1442 if (remaining <= 0) { 1443 break; 1444 } 1445 } 1446 1447 return time_slept; 1448 } 1449 1450 void WatcherThread::run() { 1451 assert(this == watcher_thread(), "just checking"); 1452 1453 this->set_active_handles(JNIHandleBlock::allocate_block()); 1454 while (true) { 1455 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1456 assert(watcher_thread() == this, "thread consistency check"); 1457 1458 // Calculate how long it'll be until the next PeriodicTask work 1459 // should be done, and sleep that amount of time. 1460 int time_waited = sleep(); 1461 1462 if (VMError::is_error_reported()) { 1463 // A fatal error has happened, the error handler(VMError::report_and_die) 1464 // should abort JVM after creating an error log file. However in some 1465 // rare cases, the error handler itself might deadlock. Here periodically 1466 // check for error reporting timeouts, and if it happens, just proceed to 1467 // abort the VM. 1468 1469 // This code is in WatcherThread because WatcherThread wakes up 1470 // periodically so the fatal error handler doesn't need to do anything; 1471 // also because the WatcherThread is less likely to crash than other 1472 // threads. 1473 1474 for (;;) { 1475 // Note: we use naked sleep in this loop because we want to avoid using 1476 // any kind of VM infrastructure which may be broken at this point. 1477 if (VMError::check_timeout()) { 1478 // We hit error reporting timeout. Error reporting was interrupted and 1479 // will be wrapping things up now (closing files etc). Give it some more 1480 // time, then quit the VM. 1481 os::naked_short_sleep(200); 1482 // Print a message to stderr. 1483 fdStream err(defaultStream::output_fd()); 1484 err.print_raw_cr("# [ timer expired, abort... ]"); 1485 // skip atexit/vm_exit/vm_abort hooks 1486 os::die(); 1487 } 1488 1489 // Wait a second, then recheck for timeout. 1490 os::naked_short_sleep(999); 1491 } 1492 } 1493 1494 if (_should_terminate) { 1495 // check for termination before posting the next tick 1496 break; 1497 } 1498 1499 PeriodicTask::real_time_tick(time_waited); 1500 } 1501 1502 // Signal that it is terminated 1503 { 1504 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1505 _watcher_thread = NULL; 1506 Terminator_lock->notify_all(); 1507 } 1508 } 1509 1510 void WatcherThread::start() { 1511 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1512 1513 if (watcher_thread() == NULL && _startable) { 1514 _should_terminate = false; 1515 // Create the single instance of WatcherThread 1516 new WatcherThread(); 1517 } 1518 } 1519 1520 void WatcherThread::make_startable() { 1521 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1522 _startable = true; 1523 } 1524 1525 void WatcherThread::stop() { 1526 { 1527 // Follow normal safepoint aware lock enter protocol since the 1528 // WatcherThread is stopped by another JavaThread. 1529 MutexLocker ml(PeriodicTask_lock); 1530 _should_terminate = true; 1531 1532 WatcherThread* watcher = watcher_thread(); 1533 if (watcher != NULL) { 1534 // unpark the WatcherThread so it can see that it should terminate 1535 watcher->unpark(); 1536 } 1537 } 1538 1539 MonitorLocker mu(Terminator_lock); 1540 1541 while (watcher_thread() != NULL) { 1542 // This wait should make safepoint checks, wait without a timeout, 1543 // and wait as a suspend-equivalent condition. 1544 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1545 } 1546 } 1547 1548 void WatcherThread::unpark() { 1549 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1550 PeriodicTask_lock->notify(); 1551 } 1552 1553 void WatcherThread::print_on(outputStream* st) const { 1554 st->print("\"%s\" ", name()); 1555 Thread::print_on(st); 1556 st->cr(); 1557 } 1558 1559 // ======= JavaThread ======== 1560 1561 #if INCLUDE_JVMCI 1562 1563 jlong* JavaThread::_jvmci_old_thread_counters; 1564 1565 bool jvmci_counters_include(JavaThread* thread) { 1566 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1567 } 1568 1569 void JavaThread::collect_counters(jlong* array, int length) { 1570 assert(length == JVMCICounterSize, "wrong value"); 1571 for (int i = 0; i < length; i++) { 1572 array[i] = _jvmci_old_thread_counters[i]; 1573 } 1574 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1575 if (jvmci_counters_include(tp)) { 1576 for (int i = 0; i < length; i++) { 1577 array[i] += tp->_jvmci_counters[i]; 1578 } 1579 } 1580 } 1581 } 1582 1583 // Attempt to enlarge the array for per thread counters. 1584 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1585 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1586 if (old_counters == NULL) { 1587 old_counters = new_counters; 1588 memset(old_counters, 0, sizeof(jlong) * new_size); 1589 } else { 1590 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1591 new_counters[i] = old_counters[i]; 1592 } 1593 if (new_size > current_size) { 1594 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1595 } 1596 FREE_C_HEAP_ARRAY(jlong, old_counters); 1597 } 1598 return new_counters; 1599 } 1600 1601 // Attempt to enlarge the array for per thread counters. 1602 void JavaThread::resize_counters(int current_size, int new_size) { 1603 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1604 } 1605 1606 class VM_JVMCIResizeCounters : public VM_Operation { 1607 private: 1608 int _new_size; 1609 1610 public: 1611 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { } 1612 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; } 1613 bool allow_nested_vm_operations() const { return true; } 1614 void doit() { 1615 // Resize the old thread counters array 1616 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size); 1617 JavaThread::_jvmci_old_thread_counters = new_counters; 1618 1619 // Now resize each threads array 1620 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1621 tp->resize_counters(JVMCICounterSize, _new_size); 1622 } 1623 JVMCICounterSize = _new_size; 1624 } 1625 }; 1626 1627 void JavaThread::resize_all_jvmci_counters(int new_size) { 1628 VM_JVMCIResizeCounters op(new_size); 1629 VMThread::execute(&op); 1630 } 1631 1632 #endif // INCLUDE_JVMCI 1633 1634 // A JavaThread is a normal Java thread 1635 1636 void JavaThread::initialize() { 1637 // Initialize fields 1638 1639 set_saved_exception_pc(NULL); 1640 set_threadObj(NULL); 1641 _anchor.clear(); 1642 set_entry_point(NULL); 1643 set_jni_functions(jni_functions()); 1644 set_callee_target(NULL); 1645 set_vm_result(NULL); 1646 set_vm_result_2(NULL); 1647 set_vframe_array_head(NULL); 1648 set_vframe_array_last(NULL); 1649 set_deferred_locals(NULL); 1650 set_deopt_mark(NULL); 1651 set_deopt_compiled_method(NULL); 1652 set_monitor_chunks(NULL); 1653 _on_thread_list = false; 1654 _thread_state = _thread_new; 1655 _terminated = _not_terminated; 1656 _array_for_gc = NULL; 1657 _suspend_equivalent = false; 1658 _in_deopt_handler = 0; 1659 _doing_unsafe_access = false; 1660 _stack_guard_state = stack_guard_unused; 1661 #if INCLUDE_JVMCI 1662 _pending_monitorenter = false; 1663 _pending_deoptimization = -1; 1664 _pending_failed_speculation = 0; 1665 _pending_transfer_to_interpreter = false; 1666 _in_retryable_allocation = false; 1667 _jvmci._alternate_call_target = NULL; 1668 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1669 _jvmci_counters = NULL; 1670 if (JVMCICounterSize > 0) { 1671 resize_counters(0, (int) JVMCICounterSize); 1672 } 1673 #endif // INCLUDE_JVMCI 1674 _reserved_stack_activation = NULL; // stack base not known yet 1675 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1676 _exception_pc = 0; 1677 _exception_handler_pc = 0; 1678 _is_method_handle_return = 0; 1679 _jvmti_thread_state= NULL; 1680 _should_post_on_exceptions_flag = JNI_FALSE; 1681 _interp_only_mode = 0; 1682 _special_runtime_exit_condition = _no_async_condition; 1683 _pending_async_exception = NULL; 1684 _thread_stat = NULL; 1685 _thread_stat = new ThreadStatistics(); 1686 _jni_active_critical = 0; 1687 _pending_jni_exception_check_fn = NULL; 1688 _do_not_unlock_if_synchronized = false; 1689 _cached_monitor_info = NULL; 1690 _parker = Parker::Allocate(this); 1691 _SleepEvent = ParkEvent::Allocate(this); 1692 // Setup safepoint state info for this thread 1693 ThreadSafepointState::create(this); 1694 1695 debug_only(_java_call_counter = 0); 1696 1697 // JVMTI PopFrame support 1698 _popframe_condition = popframe_inactive; 1699 _popframe_preserved_args = NULL; 1700 _popframe_preserved_args_size = 0; 1701 _frames_to_pop_failed_realloc = 0; 1702 1703 SafepointMechanism::initialize_header(this); 1704 1705 _class_to_be_initialized = NULL; 1706 1707 pd_initialize(); 1708 } 1709 1710 JavaThread::JavaThread(bool is_attaching_via_jni) : 1711 Thread() { 1712 initialize(); 1713 if (is_attaching_via_jni) { 1714 _jni_attach_state = _attaching_via_jni; 1715 } else { 1716 _jni_attach_state = _not_attaching_via_jni; 1717 } 1718 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1719 } 1720 1721 1722 // interrupt support 1723 1724 void JavaThread::interrupt() { 1725 debug_only(check_for_dangling_thread_pointer(this);) 1726 1727 // For Windows _interrupt_event 1728 osthread()->set_interrupted(true); 1729 1730 // For Thread.sleep 1731 _SleepEvent->unpark(); 1732 1733 // For JSR166 LockSupport.park 1734 parker()->unpark(); 1735 1736 // For ObjectMonitor and JvmtiRawMonitor 1737 _ParkEvent->unpark(); 1738 } 1739 1740 1741 bool JavaThread::is_interrupted(bool clear_interrupted) { 1742 debug_only(check_for_dangling_thread_pointer(this);) 1743 1744 if (threadObj() == NULL) { 1745 // If there is no j.l.Thread then it is impossible to have 1746 // been interrupted. We can find NULL during VM initialization 1747 // or when a JNI thread is still in the process of attaching. 1748 // In such cases this must be the current thread. 1749 assert(this == Thread::current(), "invariant"); 1750 return false; 1751 } 1752 1753 bool interrupted = java_lang_Thread::interrupted(threadObj()); 1754 1755 // NOTE that since there is no "lock" around the interrupt and 1756 // is_interrupted operations, there is the possibility that the 1757 // interrupted flag will be "false" but that the 1758 // low-level events will be in the signaled state. This is 1759 // intentional. The effect of this is that Object.wait() and 1760 // LockSupport.park() will appear to have a spurious wakeup, which 1761 // is allowed and not harmful, and the possibility is so rare that 1762 // it is not worth the added complexity to add yet another lock. 1763 // For the sleep event an explicit reset is performed on entry 1764 // to JavaThread::sleep, so there is no early return. It has also been 1765 // recommended not to put the interrupted flag into the "event" 1766 // structure because it hides the issue. 1767 // Also, because there is no lock, we must only clear the interrupt 1768 // state if we are going to report that we were interrupted; otherwise 1769 // an interrupt that happens just after we read the field would be lost. 1770 if (interrupted && clear_interrupted) { 1771 assert(this == Thread::current(), "only the current thread can clear"); 1772 java_lang_Thread::set_interrupted(threadObj(), false); 1773 osthread()->set_interrupted(false); 1774 } 1775 1776 return interrupted; 1777 } 1778 1779 bool JavaThread::reguard_stack(address cur_sp) { 1780 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1781 && _stack_guard_state != stack_guard_reserved_disabled) { 1782 return true; // Stack already guarded or guard pages not needed. 1783 } 1784 1785 if (register_stack_overflow()) { 1786 // For those architectures which have separate register and 1787 // memory stacks, we must check the register stack to see if 1788 // it has overflowed. 1789 return false; 1790 } 1791 1792 // Java code never executes within the yellow zone: the latter is only 1793 // there to provoke an exception during stack banging. If java code 1794 // is executing there, either StackShadowPages should be larger, or 1795 // some exception code in c1, c2 or the interpreter isn't unwinding 1796 // when it should. 1797 guarantee(cur_sp > stack_reserved_zone_base(), 1798 "not enough space to reguard - increase StackShadowPages"); 1799 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1800 enable_stack_yellow_reserved_zone(); 1801 if (reserved_stack_activation() != stack_base()) { 1802 set_reserved_stack_activation(stack_base()); 1803 } 1804 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1805 set_reserved_stack_activation(stack_base()); 1806 enable_stack_reserved_zone(); 1807 } 1808 return true; 1809 } 1810 1811 bool JavaThread::reguard_stack(void) { 1812 return reguard_stack(os::current_stack_pointer()); 1813 } 1814 1815 void JavaThread::block_if_vm_exited() { 1816 if (_terminated == _vm_exited) { 1817 // _vm_exited is set at safepoint, and Threads_lock is never released 1818 // we will block here forever. 1819 // Here we can be doing a jump from a safe state to an unsafe state without 1820 // proper transition, but it happens after the final safepoint has begun. 1821 set_thread_state(_thread_in_vm); 1822 Threads_lock->lock(); 1823 ShouldNotReachHere(); 1824 } 1825 } 1826 1827 1828 // Remove this ifdef when C1 is ported to the compiler interface. 1829 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1830 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1831 1832 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1833 Thread() { 1834 initialize(); 1835 _jni_attach_state = _not_attaching_via_jni; 1836 set_entry_point(entry_point); 1837 // Create the native thread itself. 1838 // %note runtime_23 1839 os::ThreadType thr_type = os::java_thread; 1840 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1841 os::java_thread; 1842 os::create_thread(this, thr_type, stack_sz); 1843 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1844 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1845 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1846 // the exception consists of creating the exception object & initializing it, initialization 1847 // will leave the VM via a JavaCall and then all locks must be unlocked). 1848 // 1849 // The thread is still suspended when we reach here. Thread must be explicit started 1850 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1851 // by calling Threads:add. The reason why this is not done here, is because the thread 1852 // object must be fully initialized (take a look at JVM_Start) 1853 } 1854 1855 JavaThread::~JavaThread() { 1856 1857 // JSR166 -- return the parker to the free list 1858 Parker::Release(_parker); 1859 _parker = NULL; 1860 1861 // Return the sleep event to the free list 1862 ParkEvent::Release(_SleepEvent); 1863 _SleepEvent = NULL; 1864 1865 // Free any remaining previous UnrollBlock 1866 vframeArray* old_array = vframe_array_last(); 1867 1868 if (old_array != NULL) { 1869 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1870 old_array->set_unroll_block(NULL); 1871 delete old_info; 1872 delete old_array; 1873 } 1874 1875 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1876 if (deferred != NULL) { 1877 // This can only happen if thread is destroyed before deoptimization occurs. 1878 assert(deferred->length() != 0, "empty array!"); 1879 do { 1880 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1881 deferred->remove_at(0); 1882 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1883 delete dlv; 1884 } while (deferred->length() != 0); 1885 delete deferred; 1886 } 1887 1888 // All Java related clean up happens in exit 1889 ThreadSafepointState::destroy(this); 1890 if (_thread_stat != NULL) delete _thread_stat; 1891 1892 #if INCLUDE_JVMCI 1893 if (JVMCICounterSize > 0) { 1894 if (jvmci_counters_include(this)) { 1895 for (int i = 0; i < JVMCICounterSize; i++) { 1896 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1897 } 1898 } 1899 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1900 } 1901 #endif // INCLUDE_JVMCI 1902 } 1903 1904 1905 // First JavaThread specific code executed by a new Java thread. 1906 void JavaThread::pre_run() { 1907 // empty - see comments in run() 1908 } 1909 1910 // The main routine called by a new Java thread. This isn't overridden 1911 // by subclasses, instead different subclasses define a different "entry_point" 1912 // which defines the actual logic for that kind of thread. 1913 void JavaThread::run() { 1914 // initialize thread-local alloc buffer related fields 1915 this->initialize_tlab(); 1916 1917 // Used to test validity of stack trace backs. 1918 // This can't be moved into pre_run() else we invalidate 1919 // the requirement that thread_main_inner is lower on 1920 // the stack. Consequently all the initialization logic 1921 // stays here in run() rather than pre_run(). 1922 this->record_base_of_stack_pointer(); 1923 1924 this->create_stack_guard_pages(); 1925 1926 this->cache_global_variables(); 1927 1928 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1929 // in the VM. Change thread state from _thread_new to _thread_in_vm 1930 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1931 // Before a thread is on the threads list it is always safe, so after leaving the 1932 // _thread_new we should emit a instruction barrier. The distance to modified code 1933 // from here is probably far enough, but this is consistent and safe. 1934 OrderAccess::cross_modify_fence(); 1935 1936 assert(JavaThread::current() == this, "sanity check"); 1937 assert(!Thread::current()->owns_locks(), "sanity check"); 1938 1939 DTRACE_THREAD_PROBE(start, this); 1940 1941 // This operation might block. We call that after all safepoint checks for a new thread has 1942 // been completed. 1943 this->set_active_handles(JNIHandleBlock::allocate_block()); 1944 1945 if (JvmtiExport::should_post_thread_life()) { 1946 JvmtiExport::post_thread_start(this); 1947 1948 } 1949 1950 // We call another function to do the rest so we are sure that the stack addresses used 1951 // from there will be lower than the stack base just computed. 1952 thread_main_inner(); 1953 } 1954 1955 void JavaThread::thread_main_inner() { 1956 assert(JavaThread::current() == this, "sanity check"); 1957 assert(this->threadObj() != NULL, "just checking"); 1958 1959 // Execute thread entry point unless this thread has a pending exception 1960 // or has been stopped before starting. 1961 // Note: Due to JVM_StopThread we can have pending exceptions already! 1962 if (!this->has_pending_exception() && 1963 !java_lang_Thread::is_stillborn(this->threadObj())) { 1964 { 1965 ResourceMark rm(this); 1966 this->set_native_thread_name(this->get_thread_name()); 1967 } 1968 HandleMark hm(this); 1969 this->entry_point()(this, this); 1970 } 1971 1972 DTRACE_THREAD_PROBE(stop, this); 1973 1974 // Cleanup is handled in post_run() 1975 } 1976 1977 // Shared teardown for all JavaThreads 1978 void JavaThread::post_run() { 1979 this->exit(false); 1980 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1981 // for any shared tear-down. 1982 this->smr_delete(); 1983 } 1984 1985 static void ensure_join(JavaThread* thread) { 1986 // We do not need to grab the Threads_lock, since we are operating on ourself. 1987 Handle threadObj(thread, thread->threadObj()); 1988 assert(threadObj.not_null(), "java thread object must exist"); 1989 ObjectLocker lock(threadObj, thread); 1990 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1991 thread->clear_pending_exception(); 1992 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1993 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1994 // Clear the native thread instance - this makes isAlive return false and allows the join() 1995 // to complete once we've done the notify_all below 1996 java_lang_Thread::set_thread(threadObj(), NULL); 1997 lock.notify_all(thread); 1998 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1999 thread->clear_pending_exception(); 2000 } 2001 2002 static bool is_daemon(oop threadObj) { 2003 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 2004 } 2005 2006 // For any new cleanup additions, please check to see if they need to be applied to 2007 // cleanup_failed_attach_current_thread as well. 2008 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 2009 assert(this == JavaThread::current(), "thread consistency check"); 2010 2011 elapsedTimer _timer_exit_phase1; 2012 elapsedTimer _timer_exit_phase2; 2013 elapsedTimer _timer_exit_phase3; 2014 elapsedTimer _timer_exit_phase4; 2015 2016 if (log_is_enabled(Debug, os, thread, timer)) { 2017 _timer_exit_phase1.start(); 2018 } 2019 2020 HandleMark hm(this); 2021 Handle uncaught_exception(this, this->pending_exception()); 2022 this->clear_pending_exception(); 2023 Handle threadObj(this, this->threadObj()); 2024 assert(threadObj.not_null(), "Java thread object should be created"); 2025 2026 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 2027 { 2028 EXCEPTION_MARK; 2029 2030 CLEAR_PENDING_EXCEPTION; 2031 } 2032 if (!destroy_vm) { 2033 if (uncaught_exception.not_null()) { 2034 EXCEPTION_MARK; 2035 // Call method Thread.dispatchUncaughtException(). 2036 Klass* thread_klass = SystemDictionary::Thread_klass(); 2037 JavaValue result(T_VOID); 2038 JavaCalls::call_virtual(&result, 2039 threadObj, thread_klass, 2040 vmSymbols::dispatchUncaughtException_name(), 2041 vmSymbols::throwable_void_signature(), 2042 uncaught_exception, 2043 THREAD); 2044 if (HAS_PENDING_EXCEPTION) { 2045 ResourceMark rm(this); 2046 jio_fprintf(defaultStream::error_stream(), 2047 "\nException: %s thrown from the UncaughtExceptionHandler" 2048 " in thread \"%s\"\n", 2049 pending_exception()->klass()->external_name(), 2050 get_thread_name()); 2051 CLEAR_PENDING_EXCEPTION; 2052 } 2053 } 2054 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2055 2056 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2057 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2058 // is deprecated anyhow. 2059 if (!is_Compiler_thread()) { 2060 int count = 3; 2061 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2062 EXCEPTION_MARK; 2063 JavaValue result(T_VOID); 2064 Klass* thread_klass = SystemDictionary::Thread_klass(); 2065 JavaCalls::call_virtual(&result, 2066 threadObj, thread_klass, 2067 vmSymbols::exit_method_name(), 2068 vmSymbols::void_method_signature(), 2069 THREAD); 2070 CLEAR_PENDING_EXCEPTION; 2071 } 2072 } 2073 // notify JVMTI 2074 if (JvmtiExport::should_post_thread_life()) { 2075 JvmtiExport::post_thread_end(this); 2076 } 2077 2078 // We have notified the agents that we are exiting, before we go on, 2079 // we must check for a pending external suspend request and honor it 2080 // in order to not surprise the thread that made the suspend request. 2081 while (true) { 2082 { 2083 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2084 if (!is_external_suspend()) { 2085 set_terminated(_thread_exiting); 2086 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2087 break; 2088 } 2089 // Implied else: 2090 // Things get a little tricky here. We have a pending external 2091 // suspend request, but we are holding the SR_lock so we 2092 // can't just self-suspend. So we temporarily drop the lock 2093 // and then self-suspend. 2094 } 2095 2096 ThreadBlockInVM tbivm(this); 2097 java_suspend_self(); 2098 2099 // We're done with this suspend request, but we have to loop around 2100 // and check again. Eventually we will get SR_lock without a pending 2101 // external suspend request and will be able to mark ourselves as 2102 // exiting. 2103 } 2104 // no more external suspends are allowed at this point 2105 } else { 2106 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2107 // before_exit() has already posted JVMTI THREAD_END events 2108 } 2109 2110 if (log_is_enabled(Debug, os, thread, timer)) { 2111 _timer_exit_phase1.stop(); 2112 _timer_exit_phase2.start(); 2113 } 2114 2115 // Capture daemon status before the thread is marked as terminated. 2116 bool daemon = is_daemon(threadObj()); 2117 2118 // Notify waiters on thread object. This has to be done after exit() is called 2119 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2120 // group should have the destroyed bit set before waiters are notified). 2121 ensure_join(this); 2122 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2123 2124 if (log_is_enabled(Debug, os, thread, timer)) { 2125 _timer_exit_phase2.stop(); 2126 _timer_exit_phase3.start(); 2127 } 2128 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2129 // held by this thread must be released. The spec does not distinguish 2130 // between JNI-acquired and regular Java monitors. We can only see 2131 // regular Java monitors here if monitor enter-exit matching is broken. 2132 // 2133 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2134 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2135 if (exit_type == jni_detach) { 2136 // Sanity check even though JNI DetachCurrentThread() would have 2137 // returned JNI_ERR if there was a Java frame. JavaThread exit 2138 // should be done executing Java code by the time we get here. 2139 assert(!this->has_last_Java_frame(), 2140 "should not have a Java frame when detaching or exiting"); 2141 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2142 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2143 } 2144 2145 // These things needs to be done while we are still a Java Thread. Make sure that thread 2146 // is in a consistent state, in case GC happens 2147 JFR_ONLY(Jfr::on_thread_exit(this);) 2148 2149 if (active_handles() != NULL) { 2150 JNIHandleBlock* block = active_handles(); 2151 set_active_handles(NULL); 2152 JNIHandleBlock::release_block(block); 2153 } 2154 2155 if (free_handle_block() != NULL) { 2156 JNIHandleBlock* block = free_handle_block(); 2157 set_free_handle_block(NULL); 2158 JNIHandleBlock::release_block(block); 2159 } 2160 2161 // These have to be removed while this is still a valid thread. 2162 remove_stack_guard_pages(); 2163 2164 if (UseTLAB) { 2165 tlab().retire(); 2166 } 2167 2168 if (JvmtiEnv::environments_might_exist()) { 2169 JvmtiExport::cleanup_thread(this); 2170 } 2171 2172 // We must flush any deferred card marks and other various GC barrier 2173 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2174 // before removing a thread from the list of active threads. 2175 BarrierSet::barrier_set()->on_thread_detach(this); 2176 2177 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2178 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2179 os::current_thread_id()); 2180 2181 if (log_is_enabled(Debug, os, thread, timer)) { 2182 _timer_exit_phase3.stop(); 2183 _timer_exit_phase4.start(); 2184 } 2185 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2186 Threads::remove(this, daemon); 2187 2188 if (log_is_enabled(Debug, os, thread, timer)) { 2189 _timer_exit_phase4.stop(); 2190 ResourceMark rm(this); 2191 log_debug(os, thread, timer)("name='%s'" 2192 ", exit-phase1=" JLONG_FORMAT 2193 ", exit-phase2=" JLONG_FORMAT 2194 ", exit-phase3=" JLONG_FORMAT 2195 ", exit-phase4=" JLONG_FORMAT, 2196 get_thread_name(), 2197 _timer_exit_phase1.milliseconds(), 2198 _timer_exit_phase2.milliseconds(), 2199 _timer_exit_phase3.milliseconds(), 2200 _timer_exit_phase4.milliseconds()); 2201 } 2202 } 2203 2204 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2205 if (active_handles() != NULL) { 2206 JNIHandleBlock* block = active_handles(); 2207 set_active_handles(NULL); 2208 JNIHandleBlock::release_block(block); 2209 } 2210 2211 if (free_handle_block() != NULL) { 2212 JNIHandleBlock* block = free_handle_block(); 2213 set_free_handle_block(NULL); 2214 JNIHandleBlock::release_block(block); 2215 } 2216 2217 // These have to be removed while this is still a valid thread. 2218 remove_stack_guard_pages(); 2219 2220 if (UseTLAB) { 2221 tlab().retire(); 2222 } 2223 2224 BarrierSet::barrier_set()->on_thread_detach(this); 2225 2226 Threads::remove(this, is_daemon); 2227 this->smr_delete(); 2228 } 2229 2230 JavaThread* JavaThread::active() { 2231 Thread* thread = Thread::current(); 2232 if (thread->is_Java_thread()) { 2233 return (JavaThread*) thread; 2234 } else { 2235 assert(thread->is_VM_thread(), "this must be a vm thread"); 2236 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2237 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2238 assert(ret->is_Java_thread(), "must be a Java thread"); 2239 return ret; 2240 } 2241 } 2242 2243 bool JavaThread::is_lock_owned(address adr) const { 2244 if (Thread::is_lock_owned(adr)) return true; 2245 2246 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2247 if (chunk->contains(adr)) return true; 2248 } 2249 2250 return false; 2251 } 2252 2253 2254 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2255 chunk->set_next(monitor_chunks()); 2256 set_monitor_chunks(chunk); 2257 } 2258 2259 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2260 guarantee(monitor_chunks() != NULL, "must be non empty"); 2261 if (monitor_chunks() == chunk) { 2262 set_monitor_chunks(chunk->next()); 2263 } else { 2264 MonitorChunk* prev = monitor_chunks(); 2265 while (prev->next() != chunk) prev = prev->next(); 2266 prev->set_next(chunk->next()); 2267 } 2268 } 2269 2270 // JVM support. 2271 2272 // Note: this function shouldn't block if it's called in 2273 // _thread_in_native_trans state (such as from 2274 // check_special_condition_for_native_trans()). 2275 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2276 2277 if (has_last_Java_frame() && has_async_condition()) { 2278 // If we are at a polling page safepoint (not a poll return) 2279 // then we must defer async exception because live registers 2280 // will be clobbered by the exception path. Poll return is 2281 // ok because the call we a returning from already collides 2282 // with exception handling registers and so there is no issue. 2283 // (The exception handling path kills call result registers but 2284 // this is ok since the exception kills the result anyway). 2285 2286 if (is_at_poll_safepoint()) { 2287 // if the code we are returning to has deoptimized we must defer 2288 // the exception otherwise live registers get clobbered on the 2289 // exception path before deoptimization is able to retrieve them. 2290 // 2291 RegisterMap map(this, false); 2292 frame caller_fr = last_frame().sender(&map); 2293 assert(caller_fr.is_compiled_frame(), "what?"); 2294 if (caller_fr.is_deoptimized_frame()) { 2295 log_info(exceptions)("deferred async exception at compiled safepoint"); 2296 return; 2297 } 2298 } 2299 } 2300 2301 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2302 if (condition == _no_async_condition) { 2303 // Conditions have changed since has_special_runtime_exit_condition() 2304 // was called: 2305 // - if we were here only because of an external suspend request, 2306 // then that was taken care of above (or cancelled) so we are done 2307 // - if we were here because of another async request, then it has 2308 // been cleared between the has_special_runtime_exit_condition() 2309 // and now so again we are done 2310 return; 2311 } 2312 2313 // Check for pending async. exception 2314 if (_pending_async_exception != NULL) { 2315 // Only overwrite an already pending exception, if it is not a threadDeath. 2316 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2317 2318 // We cannot call Exceptions::_throw(...) here because we cannot block 2319 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2320 2321 LogTarget(Info, exceptions) lt; 2322 if (lt.is_enabled()) { 2323 ResourceMark rm; 2324 LogStream ls(lt); 2325 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2326 if (has_last_Java_frame()) { 2327 frame f = last_frame(); 2328 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2329 } 2330 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2331 } 2332 _pending_async_exception = NULL; 2333 clear_has_async_exception(); 2334 } 2335 } 2336 2337 if (check_unsafe_error && 2338 condition == _async_unsafe_access_error && !has_pending_exception()) { 2339 condition = _no_async_condition; // done 2340 switch (thread_state()) { 2341 case _thread_in_vm: { 2342 JavaThread* THREAD = this; 2343 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2344 } 2345 case _thread_in_native: { 2346 ThreadInVMfromNative tiv(this); 2347 JavaThread* THREAD = this; 2348 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2349 } 2350 case _thread_in_Java: { 2351 ThreadInVMfromJava tiv(this); 2352 JavaThread* THREAD = this; 2353 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2354 } 2355 default: 2356 ShouldNotReachHere(); 2357 } 2358 } 2359 2360 assert(condition == _no_async_condition || has_pending_exception() || 2361 (!check_unsafe_error && condition == _async_unsafe_access_error), 2362 "must have handled the async condition, if no exception"); 2363 } 2364 2365 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2366 2367 // Check for pending external suspend. 2368 if (is_external_suspend_with_lock()) { 2369 frame_anchor()->make_walkable(this); 2370 java_suspend_self_with_safepoint_check(); 2371 } 2372 2373 // We might be here for reasons in addition to the self-suspend request 2374 // so check for other async requests. 2375 if (check_asyncs) { 2376 check_and_handle_async_exceptions(); 2377 } 2378 2379 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2380 } 2381 2382 void JavaThread::send_thread_stop(oop java_throwable) { 2383 ResourceMark rm; 2384 assert(Thread::current()->is_VM_thread() || Thread::current() == this, "should be in the vm thread"); 2385 2386 // Do not throw asynchronous exceptions against the compiler thread 2387 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2388 if (!can_call_java()) return; 2389 2390 { 2391 // Actually throw the Throwable against the target Thread - however 2392 // only if there is no thread death exception installed already. 2393 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2394 // If the topmost frame is a runtime stub, then we are calling into 2395 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2396 // must deoptimize the caller before continuing, as the compiled exception handler table 2397 // may not be valid 2398 if (has_last_Java_frame()) { 2399 frame f = last_frame(); 2400 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2401 RegisterMap reg_map(this, false); 2402 frame compiled_frame = f.sender(®_map); 2403 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2404 Deoptimization::deoptimize(this, compiled_frame); 2405 } 2406 } 2407 } 2408 2409 // Set async. pending exception in thread. 2410 set_pending_async_exception(java_throwable); 2411 2412 if (log_is_enabled(Info, exceptions)) { 2413 ResourceMark rm; 2414 log_info(exceptions)("Pending Async. exception installed of type: %s", 2415 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2416 } 2417 // for AbortVMOnException flag 2418 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2419 } 2420 } 2421 2422 2423 // Interrupt thread so it will wake up from a potential wait()/sleep()/park() 2424 java_lang_Thread::set_interrupted(threadObj(), true); 2425 this->interrupt(); 2426 } 2427 2428 // External suspension mechanism. 2429 // 2430 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2431 // to any VM_locks and it is at a transition 2432 // Self-suspension will happen on the transition out of the vm. 2433 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2434 // 2435 // Guarantees on return: 2436 // + Target thread will not execute any new bytecode (that's why we need to 2437 // force a safepoint) 2438 // + Target thread will not enter any new monitors 2439 // 2440 void JavaThread::java_suspend() { 2441 ThreadsListHandle tlh; 2442 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2443 return; 2444 } 2445 2446 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2447 if (!is_external_suspend()) { 2448 // a racing resume has cancelled us; bail out now 2449 return; 2450 } 2451 2452 // suspend is done 2453 uint32_t debug_bits = 0; 2454 // Warning: is_ext_suspend_completed() may temporarily drop the 2455 // SR_lock to allow the thread to reach a stable thread state if 2456 // it is currently in a transient thread state. 2457 if (is_ext_suspend_completed(false /* !called_by_wait */, 2458 SuspendRetryDelay, &debug_bits)) { 2459 return; 2460 } 2461 } 2462 2463 if (Thread::current() == this) { 2464 // Safely self-suspend. 2465 // If we don't do this explicitly it will implicitly happen 2466 // before we transition back to Java, and on some other thread-state 2467 // transition paths, but not as we exit a JVM TI SuspendThread call. 2468 // As SuspendThread(current) must not return (until resumed) we must 2469 // self-suspend here. 2470 ThreadBlockInVM tbivm(this); 2471 java_suspend_self(); 2472 } else { 2473 VM_ThreadSuspend vm_suspend; 2474 VMThread::execute(&vm_suspend); 2475 } 2476 } 2477 2478 // Part II of external suspension. 2479 // A JavaThread self suspends when it detects a pending external suspend 2480 // request. This is usually on transitions. It is also done in places 2481 // where continuing to the next transition would surprise the caller, 2482 // e.g., monitor entry. 2483 // 2484 // Returns the number of times that the thread self-suspended. 2485 // 2486 // Note: DO NOT call java_suspend_self() when you just want to block current 2487 // thread. java_suspend_self() is the second stage of cooperative 2488 // suspension for external suspend requests and should only be used 2489 // to complete an external suspend request. 2490 // 2491 int JavaThread::java_suspend_self() { 2492 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2493 int ret = 0; 2494 2495 // we are in the process of exiting so don't suspend 2496 if (is_exiting()) { 2497 clear_external_suspend(); 2498 return ret; 2499 } 2500 2501 assert(_anchor.walkable() || 2502 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2503 "must have walkable stack"); 2504 2505 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2506 2507 assert(!this->is_ext_suspended(), 2508 "a thread trying to self-suspend should not already be suspended"); 2509 2510 if (this->is_suspend_equivalent()) { 2511 // If we are self-suspending as a result of the lifting of a 2512 // suspend equivalent condition, then the suspend_equivalent 2513 // flag is not cleared until we set the ext_suspended flag so 2514 // that wait_for_ext_suspend_completion() returns consistent 2515 // results. 2516 this->clear_suspend_equivalent(); 2517 } 2518 2519 // A racing resume may have cancelled us before we grabbed SR_lock 2520 // above. Or another external suspend request could be waiting for us 2521 // by the time we return from SR_lock()->wait(). The thread 2522 // that requested the suspension may already be trying to walk our 2523 // stack and if we return now, we can change the stack out from under 2524 // it. This would be a "bad thing (TM)" and cause the stack walker 2525 // to crash. We stay self-suspended until there are no more pending 2526 // external suspend requests. 2527 while (is_external_suspend()) { 2528 ret++; 2529 this->set_ext_suspended(); 2530 2531 // _ext_suspended flag is cleared by java_resume() 2532 while (is_ext_suspended()) { 2533 ml.wait(); 2534 } 2535 } 2536 return ret; 2537 } 2538 2539 // Helper routine to set up the correct thread state before calling java_suspend_self. 2540 // This is called when regular thread-state transition helpers can't be used because 2541 // we can be in various states, in particular _thread_in_native_trans. 2542 // Because this thread is external suspended the safepoint code will count it as at 2543 // a safepoint, regardless of what its actual current thread-state is. But 2544 // is_ext_suspend_completed() may be waiting to see a thread transition from 2545 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2546 // to _thread_blocked. The problem with setting thread state directly is that a 2547 // safepoint could happen just after java_suspend_self() returns after being resumed, 2548 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2549 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2550 // However, not all initial-states are allowed when performing a safepoint check, as we 2551 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2552 // only _thread_in_native is possible when executing this code (based on our two callers). 2553 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2554 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2555 // and so we don't need the explicit safepoint check. 2556 2557 void JavaThread::java_suspend_self_with_safepoint_check() { 2558 assert(this == Thread::current(), "invariant"); 2559 JavaThreadState state = thread_state(); 2560 set_thread_state(_thread_blocked); 2561 java_suspend_self(); 2562 set_thread_state_fence(state); 2563 // Since we are not using a regular thread-state transition helper here, 2564 // we must manually emit the instruction barrier after leaving a safe state. 2565 OrderAccess::cross_modify_fence(); 2566 if (state != _thread_in_native) { 2567 SafepointMechanism::block_if_requested(this); 2568 } 2569 } 2570 2571 #ifdef ASSERT 2572 // Verify the JavaThread has not yet been published in the Threads::list, and 2573 // hence doesn't need protection from concurrent access at this stage. 2574 void JavaThread::verify_not_published() { 2575 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2576 // since an unpublished JavaThread doesn't participate in the 2577 // Thread-SMR protocol for keeping a ThreadsList alive. 2578 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2579 } 2580 #endif 2581 2582 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2583 // progress or when _suspend_flags is non-zero. 2584 // Current thread needs to self-suspend if there is a suspend request and/or 2585 // block if a safepoint is in progress. 2586 // Async exception ISN'T checked. 2587 // Note only the ThreadInVMfromNative transition can call this function 2588 // directly and when thread state is _thread_in_native_trans 2589 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2590 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2591 2592 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2593 2594 if (thread->is_external_suspend()) { 2595 thread->java_suspend_self_with_safepoint_check(); 2596 } else { 2597 SafepointMechanism::block_if_requested(thread); 2598 } 2599 2600 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2601 } 2602 2603 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2604 // progress or when _suspend_flags is non-zero. 2605 // Current thread needs to self-suspend if there is a suspend request and/or 2606 // block if a safepoint is in progress. 2607 // Also check for pending async exception (not including unsafe access error). 2608 // Note only the native==>VM/Java barriers can call this function and when 2609 // thread state is _thread_in_native_trans. 2610 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2611 check_safepoint_and_suspend_for_native_trans(thread); 2612 2613 if (thread->has_async_exception()) { 2614 // We are in _thread_in_native_trans state, don't handle unsafe 2615 // access error since that may block. 2616 thread->check_and_handle_async_exceptions(false); 2617 } 2618 } 2619 2620 // This is a variant of the normal 2621 // check_special_condition_for_native_trans with slightly different 2622 // semantics for use by critical native wrappers. It does all the 2623 // normal checks but also performs the transition back into 2624 // thread_in_Java state. This is required so that critical natives 2625 // can potentially block and perform a GC if they are the last thread 2626 // exiting the GCLocker. 2627 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2628 check_special_condition_for_native_trans(thread); 2629 2630 // Finish the transition 2631 thread->set_thread_state(_thread_in_Java); 2632 2633 if (thread->do_critical_native_unlock()) { 2634 ThreadInVMfromJavaNoAsyncException tiv(thread); 2635 GCLocker::unlock_critical(thread); 2636 thread->clear_critical_native_unlock(); 2637 } 2638 } 2639 2640 // We need to guarantee the Threads_lock here, since resumes are not 2641 // allowed during safepoint synchronization 2642 // Can only resume from an external suspension 2643 void JavaThread::java_resume() { 2644 assert_locked_or_safepoint(Threads_lock); 2645 2646 // Sanity check: thread is gone, has started exiting or the thread 2647 // was not externally suspended. 2648 ThreadsListHandle tlh; 2649 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2650 return; 2651 } 2652 2653 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2654 2655 clear_external_suspend(); 2656 2657 if (is_ext_suspended()) { 2658 clear_ext_suspended(); 2659 SR_lock()->notify_all(); 2660 } 2661 } 2662 2663 size_t JavaThread::_stack_red_zone_size = 0; 2664 size_t JavaThread::_stack_yellow_zone_size = 0; 2665 size_t JavaThread::_stack_reserved_zone_size = 0; 2666 size_t JavaThread::_stack_shadow_zone_size = 0; 2667 2668 void JavaThread::create_stack_guard_pages() { 2669 if (!os::uses_stack_guard_pages() || 2670 _stack_guard_state != stack_guard_unused || 2671 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2672 log_info(os, thread)("Stack guard page creation for thread " 2673 UINTX_FORMAT " disabled", os::current_thread_id()); 2674 return; 2675 } 2676 address low_addr = stack_end(); 2677 size_t len = stack_guard_zone_size(); 2678 2679 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2680 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2681 2682 int must_commit = os::must_commit_stack_guard_pages(); 2683 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2684 2685 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2686 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2687 return; 2688 } 2689 2690 if (os::guard_memory((char *) low_addr, len)) { 2691 _stack_guard_state = stack_guard_enabled; 2692 } else { 2693 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2694 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2695 if (os::uncommit_memory((char *) low_addr, len)) { 2696 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2697 } 2698 return; 2699 } 2700 2701 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2702 PTR_FORMAT "-" PTR_FORMAT ".", 2703 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2704 } 2705 2706 void JavaThread::remove_stack_guard_pages() { 2707 assert(Thread::current() == this, "from different thread"); 2708 if (_stack_guard_state == stack_guard_unused) return; 2709 address low_addr = stack_end(); 2710 size_t len = stack_guard_zone_size(); 2711 2712 if (os::must_commit_stack_guard_pages()) { 2713 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2714 _stack_guard_state = stack_guard_unused; 2715 } else { 2716 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2717 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2718 return; 2719 } 2720 } else { 2721 if (_stack_guard_state == stack_guard_unused) return; 2722 if (os::unguard_memory((char *) low_addr, len)) { 2723 _stack_guard_state = stack_guard_unused; 2724 } else { 2725 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2726 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2727 return; 2728 } 2729 } 2730 2731 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2732 PTR_FORMAT "-" PTR_FORMAT ".", 2733 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2734 } 2735 2736 void JavaThread::enable_stack_reserved_zone() { 2737 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2738 2739 // The base notation is from the stack's point of view, growing downward. 2740 // We need to adjust it to work correctly with guard_memory() 2741 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2742 2743 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2744 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2745 2746 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2747 _stack_guard_state = stack_guard_enabled; 2748 } else { 2749 warning("Attempt to guard stack reserved zone failed."); 2750 } 2751 enable_register_stack_guard(); 2752 } 2753 2754 void JavaThread::disable_stack_reserved_zone() { 2755 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2756 2757 // Simply return if called for a thread that does not use guard pages. 2758 if (_stack_guard_state != stack_guard_enabled) return; 2759 2760 // The base notation is from the stack's point of view, growing downward. 2761 // We need to adjust it to work correctly with guard_memory() 2762 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2763 2764 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2765 _stack_guard_state = stack_guard_reserved_disabled; 2766 } else { 2767 warning("Attempt to unguard stack reserved zone failed."); 2768 } 2769 disable_register_stack_guard(); 2770 } 2771 2772 void JavaThread::enable_stack_yellow_reserved_zone() { 2773 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2774 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2775 2776 // The base notation is from the stacks point of view, growing downward. 2777 // We need to adjust it to work correctly with guard_memory() 2778 address base = stack_red_zone_base(); 2779 2780 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2781 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2782 2783 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2784 _stack_guard_state = stack_guard_enabled; 2785 } else { 2786 warning("Attempt to guard stack yellow zone failed."); 2787 } 2788 enable_register_stack_guard(); 2789 } 2790 2791 void JavaThread::disable_stack_yellow_reserved_zone() { 2792 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2793 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2794 2795 // Simply return if called for a thread that does not use guard pages. 2796 if (_stack_guard_state == stack_guard_unused) return; 2797 2798 // The base notation is from the stacks point of view, growing downward. 2799 // We need to adjust it to work correctly with guard_memory() 2800 address base = stack_red_zone_base(); 2801 2802 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2803 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2804 } else { 2805 warning("Attempt to unguard stack yellow zone failed."); 2806 } 2807 disable_register_stack_guard(); 2808 } 2809 2810 void JavaThread::enable_stack_red_zone() { 2811 // The base notation is from the stacks point of view, growing downward. 2812 // We need to adjust it to work correctly with guard_memory() 2813 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2814 address base = stack_red_zone_base() - stack_red_zone_size(); 2815 2816 guarantee(base < stack_base(), "Error calculating stack red zone"); 2817 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2818 2819 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2820 warning("Attempt to guard stack red zone failed."); 2821 } 2822 } 2823 2824 void JavaThread::disable_stack_red_zone() { 2825 // The base notation is from the stacks point of view, growing downward. 2826 // We need to adjust it to work correctly with guard_memory() 2827 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2828 address base = stack_red_zone_base() - stack_red_zone_size(); 2829 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2830 warning("Attempt to unguard stack red zone failed."); 2831 } 2832 } 2833 2834 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2835 // ignore is there is no stack 2836 if (!has_last_Java_frame()) return; 2837 // traverse the stack frames. Starts from top frame. 2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2839 frame* fr = fst.current(); 2840 f(fr, fst.register_map()); 2841 } 2842 } 2843 2844 2845 #ifndef PRODUCT 2846 // Deoptimization 2847 // Function for testing deoptimization 2848 void JavaThread::deoptimize() { 2849 StackFrameStream fst(this, false); 2850 bool deopt = false; // Dump stack only if a deopt actually happens. 2851 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2852 // Iterate over all frames in the thread and deoptimize 2853 for (; !fst.is_done(); fst.next()) { 2854 if (fst.current()->can_be_deoptimized()) { 2855 2856 if (only_at) { 2857 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2858 // consists of comma or carriage return separated numbers so 2859 // search for the current bci in that string. 2860 address pc = fst.current()->pc(); 2861 nmethod* nm = (nmethod*) fst.current()->cb(); 2862 ScopeDesc* sd = nm->scope_desc_at(pc); 2863 char buffer[8]; 2864 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2865 size_t len = strlen(buffer); 2866 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2867 while (found != NULL) { 2868 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2869 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2870 // Check that the bci found is bracketed by terminators. 2871 break; 2872 } 2873 found = strstr(found + 1, buffer); 2874 } 2875 if (!found) { 2876 continue; 2877 } 2878 } 2879 2880 if (DebugDeoptimization && !deopt) { 2881 deopt = true; // One-time only print before deopt 2882 tty->print_cr("[BEFORE Deoptimization]"); 2883 trace_frames(); 2884 trace_stack(); 2885 } 2886 Deoptimization::deoptimize(this, *fst.current()); 2887 } 2888 } 2889 2890 if (DebugDeoptimization && deopt) { 2891 tty->print_cr("[AFTER Deoptimization]"); 2892 trace_frames(); 2893 } 2894 } 2895 2896 2897 // Make zombies 2898 void JavaThread::make_zombies() { 2899 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2900 if (fst.current()->can_be_deoptimized()) { 2901 // it is a Java nmethod 2902 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2903 nm->make_not_entrant(); 2904 } 2905 } 2906 } 2907 #endif // PRODUCT 2908 2909 2910 void JavaThread::deoptimize_marked_methods() { 2911 if (!has_last_Java_frame()) return; 2912 StackFrameStream fst(this, false); 2913 for (; !fst.is_done(); fst.next()) { 2914 if (fst.current()->should_be_deoptimized()) { 2915 Deoptimization::deoptimize(this, *fst.current()); 2916 } 2917 } 2918 } 2919 2920 // If the caller is a NamedThread, then remember, in the current scope, 2921 // the given JavaThread in its _processed_thread field. 2922 class RememberProcessedThread: public StackObj { 2923 NamedThread* _cur_thr; 2924 public: 2925 RememberProcessedThread(JavaThread* jthr) { 2926 Thread* thread = Thread::current(); 2927 if (thread->is_Named_thread()) { 2928 _cur_thr = (NamedThread *)thread; 2929 _cur_thr->set_processed_thread(jthr); 2930 } else { 2931 _cur_thr = NULL; 2932 } 2933 } 2934 2935 ~RememberProcessedThread() { 2936 if (_cur_thr) { 2937 _cur_thr->set_processed_thread(NULL); 2938 } 2939 } 2940 }; 2941 2942 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2943 // Verify that the deferred card marks have been flushed. 2944 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2945 2946 // Traverse the GCHandles 2947 Thread::oops_do(f, cf); 2948 2949 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2950 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2951 2952 if (has_last_Java_frame()) { 2953 // Record JavaThread to GC thread 2954 RememberProcessedThread rpt(this); 2955 2956 // traverse the registered growable array 2957 if (_array_for_gc != NULL) { 2958 for (int index = 0; index < _array_for_gc->length(); index++) { 2959 f->do_oop(_array_for_gc->adr_at(index)); 2960 } 2961 } 2962 2963 // Traverse the monitor chunks 2964 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2965 chunk->oops_do(f); 2966 } 2967 2968 // Traverse the execution stack 2969 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2970 fst.current()->oops_do(f, cf, fst.register_map()); 2971 } 2972 } 2973 2974 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2975 // If we have deferred set_locals there might be oops waiting to be 2976 // written 2977 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2978 if (list != NULL) { 2979 for (int i = 0; i < list->length(); i++) { 2980 list->at(i)->oops_do(f); 2981 } 2982 } 2983 2984 // Traverse instance variables at the end since the GC may be moving things 2985 // around using this function 2986 f->do_oop((oop*) &_threadObj); 2987 f->do_oop((oop*) &_vm_result); 2988 f->do_oop((oop*) &_exception_oop); 2989 f->do_oop((oop*) &_pending_async_exception); 2990 2991 if (jvmti_thread_state() != NULL) { 2992 jvmti_thread_state()->oops_do(f, cf); 2993 } 2994 } 2995 2996 #ifdef ASSERT 2997 void JavaThread::verify_states_for_handshake() { 2998 // This checks that the thread has a correct frame state during a handshake. 2999 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3000 (has_last_Java_frame() && java_call_counter() > 0), 3001 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3002 has_last_Java_frame(), java_call_counter()); 3003 } 3004 #endif 3005 3006 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 3007 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3008 (has_last_Java_frame() && java_call_counter() > 0), 3009 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3010 has_last_Java_frame(), java_call_counter()); 3011 3012 if (has_last_Java_frame()) { 3013 // Traverse the execution stack 3014 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3015 fst.current()->nmethods_do(cf); 3016 } 3017 } 3018 3019 if (jvmti_thread_state() != NULL) { 3020 jvmti_thread_state()->nmethods_do(cf); 3021 } 3022 } 3023 3024 void JavaThread::metadata_do(MetadataClosure* f) { 3025 if (has_last_Java_frame()) { 3026 // Traverse the execution stack to call f() on the methods in the stack 3027 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3028 fst.current()->metadata_do(f); 3029 } 3030 } else if (is_Compiler_thread()) { 3031 // need to walk ciMetadata in current compile tasks to keep alive. 3032 CompilerThread* ct = (CompilerThread*)this; 3033 if (ct->env() != NULL) { 3034 ct->env()->metadata_do(f); 3035 } 3036 CompileTask* task = ct->task(); 3037 if (task != NULL) { 3038 task->metadata_do(f); 3039 } 3040 } 3041 } 3042 3043 // Printing 3044 const char* _get_thread_state_name(JavaThreadState _thread_state) { 3045 switch (_thread_state) { 3046 case _thread_uninitialized: return "_thread_uninitialized"; 3047 case _thread_new: return "_thread_new"; 3048 case _thread_new_trans: return "_thread_new_trans"; 3049 case _thread_in_native: return "_thread_in_native"; 3050 case _thread_in_native_trans: return "_thread_in_native_trans"; 3051 case _thread_in_vm: return "_thread_in_vm"; 3052 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3053 case _thread_in_Java: return "_thread_in_Java"; 3054 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3055 case _thread_blocked: return "_thread_blocked"; 3056 case _thread_blocked_trans: return "_thread_blocked_trans"; 3057 default: return "unknown thread state"; 3058 } 3059 } 3060 3061 #ifndef PRODUCT 3062 void JavaThread::print_thread_state_on(outputStream *st) const { 3063 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3064 }; 3065 #endif // PRODUCT 3066 3067 // Called by Threads::print() for VM_PrintThreads operation 3068 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3069 st->print_raw("\""); 3070 st->print_raw(get_thread_name()); 3071 st->print_raw("\" "); 3072 oop thread_oop = threadObj(); 3073 if (thread_oop != NULL) { 3074 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3075 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3076 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3077 } 3078 Thread::print_on(st, print_extended_info); 3079 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3080 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3081 if (thread_oop != NULL) { 3082 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3083 } 3084 #ifndef PRODUCT 3085 _safepoint_state->print_on(st); 3086 #endif // PRODUCT 3087 if (is_Compiler_thread()) { 3088 CompileTask *task = ((CompilerThread*)this)->task(); 3089 if (task != NULL) { 3090 st->print(" Compiling: "); 3091 task->print(st, NULL, true, false); 3092 } else { 3093 st->print(" No compile task"); 3094 } 3095 st->cr(); 3096 } 3097 } 3098 3099 void JavaThread::print() const { print_on(tty); } 3100 3101 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3102 st->print("%s", get_thread_name_string(buf, buflen)); 3103 } 3104 3105 // Called by fatal error handler. The difference between this and 3106 // JavaThread::print() is that we can't grab lock or allocate memory. 3107 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3108 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3109 oop thread_obj = threadObj(); 3110 if (thread_obj != NULL) { 3111 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3112 } 3113 st->print(" ["); 3114 st->print("%s", _get_thread_state_name(_thread_state)); 3115 if (osthread()) { 3116 st->print(", id=%d", osthread()->thread_id()); 3117 } 3118 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3119 p2i(stack_end()), p2i(stack_base())); 3120 st->print("]"); 3121 3122 ThreadsSMRSupport::print_info_on(this, st); 3123 return; 3124 } 3125 3126 // Verification 3127 3128 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3129 3130 void JavaThread::verify() { 3131 // Verify oops in the thread. 3132 oops_do(&VerifyOopClosure::verify_oop, NULL); 3133 3134 // Verify the stack frames. 3135 frames_do(frame_verify); 3136 } 3137 3138 // CR 6300358 (sub-CR 2137150) 3139 // Most callers of this method assume that it can't return NULL but a 3140 // thread may not have a name whilst it is in the process of attaching to 3141 // the VM - see CR 6412693, and there are places where a JavaThread can be 3142 // seen prior to having it's threadObj set (eg JNI attaching threads and 3143 // if vm exit occurs during initialization). These cases can all be accounted 3144 // for such that this method never returns NULL. 3145 const char* JavaThread::get_thread_name() const { 3146 #ifdef ASSERT 3147 // early safepoints can hit while current thread does not yet have TLS 3148 if (!SafepointSynchronize::is_at_safepoint()) { 3149 Thread *cur = Thread::current(); 3150 if (!(cur->is_Java_thread() && cur == this)) { 3151 // Current JavaThreads are allowed to get their own name without 3152 // the Threads_lock. 3153 assert_locked_or_safepoint_or_handshake(Threads_lock, this); 3154 } 3155 } 3156 #endif // ASSERT 3157 return get_thread_name_string(); 3158 } 3159 3160 // Returns a non-NULL representation of this thread's name, or a suitable 3161 // descriptive string if there is no set name 3162 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3163 const char* name_str; 3164 oop thread_obj = threadObj(); 3165 if (thread_obj != NULL) { 3166 oop name = java_lang_Thread::name(thread_obj); 3167 if (name != NULL) { 3168 if (buf == NULL) { 3169 name_str = java_lang_String::as_utf8_string(name); 3170 } else { 3171 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3172 } 3173 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3174 name_str = "<no-name - thread is attaching>"; 3175 } else { 3176 name_str = Thread::name(); 3177 } 3178 } else { 3179 name_str = Thread::name(); 3180 } 3181 assert(name_str != NULL, "unexpected NULL thread name"); 3182 return name_str; 3183 } 3184 3185 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3186 3187 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3188 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3189 // Link Java Thread object <-> C++ Thread 3190 3191 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3192 // and put it into a new Handle. The Handle "thread_oop" can then 3193 // be used to pass the C++ thread object to other methods. 3194 3195 // Set the Java level thread object (jthread) field of the 3196 // new thread (a JavaThread *) to C++ thread object using the 3197 // "thread_oop" handle. 3198 3199 // Set the thread field (a JavaThread *) of the 3200 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3201 3202 Handle thread_oop(Thread::current(), 3203 JNIHandles::resolve_non_null(jni_thread)); 3204 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3205 "must be initialized"); 3206 set_threadObj(thread_oop()); 3207 java_lang_Thread::set_thread(thread_oop(), this); 3208 3209 if (prio == NoPriority) { 3210 prio = java_lang_Thread::priority(thread_oop()); 3211 assert(prio != NoPriority, "A valid priority should be present"); 3212 } 3213 3214 // Push the Java priority down to the native thread; needs Threads_lock 3215 Thread::set_priority(this, prio); 3216 3217 // Add the new thread to the Threads list and set it in motion. 3218 // We must have threads lock in order to call Threads::add. 3219 // It is crucial that we do not block before the thread is 3220 // added to the Threads list for if a GC happens, then the java_thread oop 3221 // will not be visited by GC. 3222 Threads::add(this); 3223 } 3224 3225 oop JavaThread::current_park_blocker() { 3226 // Support for JSR-166 locks 3227 oop thread_oop = threadObj(); 3228 if (thread_oop != NULL) { 3229 return java_lang_Thread::park_blocker(thread_oop); 3230 } 3231 return NULL; 3232 } 3233 3234 3235 void JavaThread::print_stack_on(outputStream* st) { 3236 if (!has_last_Java_frame()) return; 3237 ResourceMark rm; 3238 HandleMark hm; 3239 3240 RegisterMap reg_map(this); 3241 vframe* start_vf = last_java_vframe(®_map); 3242 int count = 0; 3243 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3244 if (f->is_java_frame()) { 3245 javaVFrame* jvf = javaVFrame::cast(f); 3246 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3247 3248 // Print out lock information 3249 if (JavaMonitorsInStackTrace) { 3250 jvf->print_lock_info_on(st, count); 3251 } 3252 } else { 3253 // Ignore non-Java frames 3254 } 3255 3256 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3257 count++; 3258 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3259 } 3260 } 3261 3262 3263 // JVMTI PopFrame support 3264 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3265 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3266 if (in_bytes(size_in_bytes) != 0) { 3267 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3268 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3269 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3270 } 3271 } 3272 3273 void* JavaThread::popframe_preserved_args() { 3274 return _popframe_preserved_args; 3275 } 3276 3277 ByteSize JavaThread::popframe_preserved_args_size() { 3278 return in_ByteSize(_popframe_preserved_args_size); 3279 } 3280 3281 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3282 int sz = in_bytes(popframe_preserved_args_size()); 3283 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3284 return in_WordSize(sz / wordSize); 3285 } 3286 3287 void JavaThread::popframe_free_preserved_args() { 3288 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3289 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args); 3290 _popframe_preserved_args = NULL; 3291 _popframe_preserved_args_size = 0; 3292 } 3293 3294 #ifndef PRODUCT 3295 3296 void JavaThread::trace_frames() { 3297 tty->print_cr("[Describe stack]"); 3298 int frame_no = 1; 3299 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3300 tty->print(" %d. ", frame_no++); 3301 fst.current()->print_value_on(tty, this); 3302 tty->cr(); 3303 } 3304 } 3305 3306 class PrintAndVerifyOopClosure: public OopClosure { 3307 protected: 3308 template <class T> inline void do_oop_work(T* p) { 3309 oop obj = RawAccess<>::oop_load(p); 3310 if (obj == NULL) return; 3311 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3312 if (oopDesc::is_oop_or_null(obj)) { 3313 if (obj->is_objArray()) { 3314 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3315 } else { 3316 obj->print(); 3317 } 3318 } else { 3319 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3320 } 3321 tty->cr(); 3322 } 3323 public: 3324 virtual void do_oop(oop* p) { do_oop_work(p); } 3325 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3326 }; 3327 3328 #ifdef ASSERT 3329 // Print or validate the layout of stack frames 3330 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3331 ResourceMark rm; 3332 PRESERVE_EXCEPTION_MARK; 3333 FrameValues values; 3334 int frame_no = 0; 3335 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3336 fst.current()->describe(values, ++frame_no); 3337 if (depth == frame_no) break; 3338 } 3339 if (validate_only) { 3340 values.validate(); 3341 } else { 3342 tty->print_cr("[Describe stack layout]"); 3343 values.print(this); 3344 } 3345 } 3346 #endif 3347 3348 void JavaThread::trace_stack_from(vframe* start_vf) { 3349 ResourceMark rm; 3350 int vframe_no = 1; 3351 for (vframe* f = start_vf; f; f = f->sender()) { 3352 if (f->is_java_frame()) { 3353 javaVFrame::cast(f)->print_activation(vframe_no++); 3354 } else { 3355 f->print(); 3356 } 3357 if (vframe_no > StackPrintLimit) { 3358 tty->print_cr("...<more frames>..."); 3359 return; 3360 } 3361 } 3362 } 3363 3364 3365 void JavaThread::trace_stack() { 3366 if (!has_last_Java_frame()) return; 3367 ResourceMark rm; 3368 HandleMark hm; 3369 RegisterMap reg_map(this); 3370 trace_stack_from(last_java_vframe(®_map)); 3371 } 3372 3373 3374 #endif // PRODUCT 3375 3376 3377 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3378 assert(reg_map != NULL, "a map must be given"); 3379 frame f = last_frame(); 3380 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3381 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3382 } 3383 return NULL; 3384 } 3385 3386 3387 Klass* JavaThread::security_get_caller_class(int depth) { 3388 vframeStream vfst(this); 3389 vfst.security_get_caller_frame(depth); 3390 if (!vfst.at_end()) { 3391 return vfst.method()->method_holder(); 3392 } 3393 return NULL; 3394 } 3395 3396 // java.lang.Thread.sleep support 3397 // Returns true if sleep time elapsed as expected, and false 3398 // if the thread was interrupted. 3399 bool JavaThread::sleep(jlong millis) { 3400 assert(this == Thread::current(), "thread consistency check"); 3401 3402 ParkEvent * const slp = this->_SleepEvent; 3403 // Because there can be races with thread interruption sending an unpark() 3404 // to the event, we explicitly reset it here to avoid an immediate return. 3405 // The actual interrupt state will be checked before we park(). 3406 slp->reset(); 3407 // Thread interruption establishes a happens-before ordering in the 3408 // Java Memory Model, so we need to ensure we synchronize with the 3409 // interrupt state. 3410 OrderAccess::fence(); 3411 3412 jlong prevtime = os::javaTimeNanos(); 3413 3414 for (;;) { 3415 // interruption has precedence over timing out 3416 if (this->is_interrupted(true)) { 3417 return false; 3418 } 3419 3420 if (millis <= 0) { 3421 return true; 3422 } 3423 3424 { 3425 ThreadBlockInVM tbivm(this); 3426 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 3427 3428 this->set_suspend_equivalent(); 3429 // cleared by handle_special_suspend_equivalent_condition() or 3430 // java_suspend_self() via check_and_wait_while_suspended() 3431 3432 slp->park(millis); 3433 3434 // were we externally suspended while we were waiting? 3435 this->check_and_wait_while_suspended(); 3436 } 3437 3438 // Update elapsed time tracking 3439 jlong newtime = os::javaTimeNanos(); 3440 if (newtime - prevtime < 0) { 3441 // time moving backwards, should only happen if no monotonic clock 3442 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3443 assert(!os::supports_monotonic_clock(), 3444 "unexpected time moving backwards detected in JavaThread::sleep()"); 3445 } else { 3446 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3447 } 3448 prevtime = newtime; 3449 } 3450 } 3451 3452 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3453 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3454 CompileBroker::compiler_thread_loop(); 3455 } 3456 3457 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3458 NMethodSweeper::sweeper_loop(); 3459 } 3460 3461 // Create a CompilerThread 3462 CompilerThread::CompilerThread(CompileQueue* queue, 3463 CompilerCounters* counters) 3464 : JavaThread(&compiler_thread_entry) { 3465 _env = NULL; 3466 _log = NULL; 3467 _task = NULL; 3468 _queue = queue; 3469 _counters = counters; 3470 _buffer_blob = NULL; 3471 _compiler = NULL; 3472 3473 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3474 resource_area()->bias_to(mtCompiler); 3475 3476 #ifndef PRODUCT 3477 _ideal_graph_printer = NULL; 3478 #endif 3479 } 3480 3481 CompilerThread::~CompilerThread() { 3482 // Delete objects which were allocated on heap. 3483 delete _counters; 3484 } 3485 3486 bool CompilerThread::can_call_java() const { 3487 return _compiler != NULL && _compiler->is_jvmci(); 3488 } 3489 3490 // Create sweeper thread 3491 CodeCacheSweeperThread::CodeCacheSweeperThread() 3492 : JavaThread(&sweeper_thread_entry) { 3493 _scanned_compiled_method = NULL; 3494 } 3495 3496 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3497 JavaThread::oops_do(f, cf); 3498 if (_scanned_compiled_method != NULL && cf != NULL) { 3499 // Safepoints can occur when the sweeper is scanning an nmethod so 3500 // process it here to make sure it isn't unloaded in the middle of 3501 // a scan. 3502 cf->do_code_blob(_scanned_compiled_method); 3503 } 3504 } 3505 3506 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3507 JavaThread::nmethods_do(cf); 3508 if (_scanned_compiled_method != NULL && cf != NULL) { 3509 // Safepoints can occur when the sweeper is scanning an nmethod so 3510 // process it here to make sure it isn't unloaded in the middle of 3511 // a scan. 3512 cf->do_code_blob(_scanned_compiled_method); 3513 } 3514 } 3515 3516 3517 // ======= Threads ======== 3518 3519 // The Threads class links together all active threads, and provides 3520 // operations over all threads. It is protected by the Threads_lock, 3521 // which is also used in other global contexts like safepointing. 3522 // ThreadsListHandles are used to safely perform operations on one 3523 // or more threads without the risk of the thread exiting during the 3524 // operation. 3525 // 3526 // Note: The Threads_lock is currently more widely used than we 3527 // would like. We are actively migrating Threads_lock uses to other 3528 // mechanisms in order to reduce Threads_lock contention. 3529 3530 int Threads::_number_of_threads = 0; 3531 int Threads::_number_of_non_daemon_threads = 0; 3532 int Threads::_return_code = 0; 3533 uintx Threads::_thread_claim_token = 1; // Never zero. 3534 size_t JavaThread::_stack_size_at_create = 0; 3535 3536 #ifdef ASSERT 3537 bool Threads::_vm_complete = false; 3538 #endif 3539 3540 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3541 Prefetch::read((void*)addr, prefetch_interval); 3542 return *addr; 3543 } 3544 3545 // Possibly the ugliest for loop the world has seen. C++ does not allow 3546 // multiple types in the declaration section of the for loop. In this case 3547 // we are only dealing with pointers and hence can cast them. It looks ugly 3548 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3549 #define DO_JAVA_THREADS(LIST, X) \ 3550 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3551 *MACRO_list = (JavaThread*)(LIST), \ 3552 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3553 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3554 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3555 MACRO_current_p != MACRO_end; \ 3556 MACRO_current_p++, \ 3557 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3558 3559 // All JavaThreads 3560 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3561 3562 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3563 void Threads::non_java_threads_do(ThreadClosure* tc) { 3564 NoSafepointVerifier nsv; 3565 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3566 tc->do_thread(njti.current()); 3567 } 3568 } 3569 3570 // All JavaThreads 3571 void Threads::java_threads_do(ThreadClosure* tc) { 3572 assert_locked_or_safepoint(Threads_lock); 3573 // ALL_JAVA_THREADS iterates through all JavaThreads. 3574 ALL_JAVA_THREADS(p) { 3575 tc->do_thread(p); 3576 } 3577 } 3578 3579 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3580 assert_locked_or_safepoint(Threads_lock); 3581 java_threads_do(tc); 3582 tc->do_thread(VMThread::vm_thread()); 3583 } 3584 3585 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3586 void Threads::threads_do(ThreadClosure* tc) { 3587 assert_locked_or_safepoint(Threads_lock); 3588 java_threads_do(tc); 3589 non_java_threads_do(tc); 3590 } 3591 3592 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3593 uintx claim_token = Threads::thread_claim_token(); 3594 ALL_JAVA_THREADS(p) { 3595 if (p->claim_threads_do(is_par, claim_token)) { 3596 tc->do_thread(p); 3597 } 3598 } 3599 VMThread* vmt = VMThread::vm_thread(); 3600 if (vmt->claim_threads_do(is_par, claim_token)) { 3601 tc->do_thread(vmt); 3602 } 3603 } 3604 3605 // The system initialization in the library has three phases. 3606 // 3607 // Phase 1: java.lang.System class initialization 3608 // java.lang.System is a primordial class loaded and initialized 3609 // by the VM early during startup. java.lang.System.<clinit> 3610 // only does registerNatives and keeps the rest of the class 3611 // initialization work later until thread initialization completes. 3612 // 3613 // System.initPhase1 initializes the system properties, the static 3614 // fields in, out, and err. Set up java signal handlers, OS-specific 3615 // system settings, and thread group of the main thread. 3616 static void call_initPhase1(TRAPS) { 3617 Klass* klass = SystemDictionary::System_klass(); 3618 JavaValue result(T_VOID); 3619 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3620 vmSymbols::void_method_signature(), CHECK); 3621 } 3622 3623 // Phase 2. Module system initialization 3624 // This will initialize the module system. Only java.base classes 3625 // can be loaded until phase 2 completes. 3626 // 3627 // Call System.initPhase2 after the compiler initialization and jsr292 3628 // classes get initialized because module initialization runs a lot of java 3629 // code, that for performance reasons, should be compiled. Also, this will 3630 // enable the startup code to use lambda and other language features in this 3631 // phase and onward. 3632 // 3633 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3634 static void call_initPhase2(TRAPS) { 3635 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3636 3637 Klass* klass = SystemDictionary::System_klass(); 3638 3639 JavaValue result(T_INT); 3640 JavaCallArguments args; 3641 args.push_int(DisplayVMOutputToStderr); 3642 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3643 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3644 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3645 if (result.get_jint() != JNI_OK) { 3646 vm_exit_during_initialization(); // no message or exception 3647 } 3648 3649 universe_post_module_init(); 3650 } 3651 3652 // Phase 3. final setup - set security manager, system class loader and TCCL 3653 // 3654 // This will instantiate and set the security manager, set the system class 3655 // loader as well as the thread context class loader. The security manager 3656 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3657 // other modules or the application's classpath. 3658 static void call_initPhase3(TRAPS) { 3659 Klass* klass = SystemDictionary::System_klass(); 3660 JavaValue result(T_VOID); 3661 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3662 vmSymbols::void_method_signature(), CHECK); 3663 } 3664 3665 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3666 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3667 3668 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3669 create_vm_init_libraries(); 3670 } 3671 3672 initialize_class(vmSymbols::java_lang_String(), CHECK); 3673 3674 // Inject CompactStrings value after the static initializers for String ran. 3675 java_lang_String::set_compact_strings(CompactStrings); 3676 3677 // Initialize java_lang.System (needed before creating the thread) 3678 initialize_class(vmSymbols::java_lang_System(), CHECK); 3679 // The VM creates & returns objects of this class. Make sure it's initialized. 3680 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3681 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3682 Handle thread_group = create_initial_thread_group(CHECK); 3683 Universe::set_main_thread_group(thread_group()); 3684 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3685 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3686 main_thread->set_threadObj(thread_object); 3687 3688 // Set thread status to running since main thread has 3689 // been started and running. 3690 java_lang_Thread::set_thread_status(thread_object, 3691 java_lang_Thread::RUNNABLE); 3692 3693 // The VM creates objects of this class. 3694 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3695 3696 #ifdef ASSERT 3697 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3698 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3699 #endif 3700 3701 // initialize the hardware-specific constants needed by Unsafe 3702 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3703 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3704 3705 // The VM preresolves methods to these classes. Make sure that they get initialized 3706 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3707 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3708 3709 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3710 call_initPhase1(CHECK); 3711 3712 // get the Java runtime name, version, and vendor info after java.lang.System is initialized 3713 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3714 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3715 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD)); 3716 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD)); 3717 3718 // an instance of OutOfMemory exception has been allocated earlier 3719 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3720 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3721 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3722 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3723 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3724 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3725 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3726 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3727 3728 // Eager box cache initialization only if AOT is on and any library is loaded. 3729 AOTLoader::initialize_box_caches(CHECK); 3730 } 3731 3732 void Threads::initialize_jsr292_core_classes(TRAPS) { 3733 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3734 3735 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3736 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3737 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3738 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3739 } 3740 3741 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3742 extern void JDK_Version_init(); 3743 3744 // Preinitialize version info. 3745 VM_Version::early_initialize(); 3746 3747 // Check version 3748 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3749 3750 // Initialize library-based TLS 3751 ThreadLocalStorage::init(); 3752 3753 // Initialize the output stream module 3754 ostream_init(); 3755 3756 // Process java launcher properties. 3757 Arguments::process_sun_java_launcher_properties(args); 3758 3759 // Initialize the os module 3760 os::init(); 3761 3762 // Record VM creation timing statistics 3763 TraceVmCreationTime create_vm_timer; 3764 create_vm_timer.start(); 3765 3766 // Initialize system properties. 3767 Arguments::init_system_properties(); 3768 3769 // So that JDK version can be used as a discriminator when parsing arguments 3770 JDK_Version_init(); 3771 3772 // Update/Initialize System properties after JDK version number is known 3773 Arguments::init_version_specific_system_properties(); 3774 3775 // Make sure to initialize log configuration *before* parsing arguments 3776 LogConfiguration::initialize(create_vm_timer.begin_time()); 3777 3778 // Parse arguments 3779 // Note: this internally calls os::init_container_support() 3780 jint parse_result = Arguments::parse(args); 3781 if (parse_result != JNI_OK) return parse_result; 3782 3783 os::init_before_ergo(); 3784 3785 jint ergo_result = Arguments::apply_ergo(); 3786 if (ergo_result != JNI_OK) return ergo_result; 3787 3788 // Final check of all ranges after ergonomics which may change values. 3789 if (!JVMFlagRangeList::check_ranges()) { 3790 return JNI_EINVAL; 3791 } 3792 3793 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3794 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3795 if (!constraint_result) { 3796 return JNI_EINVAL; 3797 } 3798 3799 if (PauseAtStartup) { 3800 os::pause(); 3801 } 3802 3803 HOTSPOT_VM_INIT_BEGIN(); 3804 3805 // Timing (must come after argument parsing) 3806 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3807 3808 // Initialize the os module after parsing the args 3809 jint os_init_2_result = os::init_2(); 3810 if (os_init_2_result != JNI_OK) return os_init_2_result; 3811 3812 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3813 // Initialize assert poison page mechanism. 3814 if (ShowRegistersOnAssert) { 3815 initialize_assert_poison(); 3816 } 3817 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3818 3819 SafepointMechanism::initialize(); 3820 3821 jint adjust_after_os_result = Arguments::adjust_after_os(); 3822 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3823 3824 // Initialize output stream logging 3825 ostream_init_log(); 3826 3827 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3828 // Must be before create_vm_init_agents() 3829 if (Arguments::init_libraries_at_startup()) { 3830 convert_vm_init_libraries_to_agents(); 3831 } 3832 3833 // Launch -agentlib/-agentpath and converted -Xrun agents 3834 if (Arguments::init_agents_at_startup()) { 3835 create_vm_init_agents(); 3836 } 3837 3838 // Initialize Threads state 3839 _number_of_threads = 0; 3840 _number_of_non_daemon_threads = 0; 3841 3842 // Initialize global data structures and create system classes in heap 3843 vm_init_globals(); 3844 3845 #if INCLUDE_JVMCI 3846 if (JVMCICounterSize > 0) { 3847 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3848 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3849 } else { 3850 JavaThread::_jvmci_old_thread_counters = NULL; 3851 } 3852 #endif // INCLUDE_JVMCI 3853 3854 // Attach the main thread to this os thread 3855 JavaThread* main_thread = new JavaThread(); 3856 main_thread->set_thread_state(_thread_in_vm); 3857 main_thread->initialize_thread_current(); 3858 // must do this before set_active_handles 3859 main_thread->record_stack_base_and_size(); 3860 main_thread->register_thread_stack_with_NMT(); 3861 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3862 3863 if (!main_thread->set_as_starting_thread()) { 3864 vm_shutdown_during_initialization( 3865 "Failed necessary internal allocation. Out of swap space"); 3866 main_thread->smr_delete(); 3867 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3868 return JNI_ENOMEM; 3869 } 3870 3871 // Enable guard page *after* os::create_main_thread(), otherwise it would 3872 // crash Linux VM, see notes in os_linux.cpp. 3873 main_thread->create_stack_guard_pages(); 3874 3875 // Initialize Java-Level synchronization subsystem 3876 ObjectMonitor::Initialize(); 3877 3878 // Initialize global modules 3879 jint status = init_globals(); 3880 if (status != JNI_OK) { 3881 main_thread->smr_delete(); 3882 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3883 return status; 3884 } 3885 3886 JFR_ONLY(Jfr::on_create_vm_1();) 3887 3888 // Should be done after the heap is fully created 3889 main_thread->cache_global_variables(); 3890 3891 HandleMark hm; 3892 3893 { MutexLocker mu(Threads_lock); 3894 Threads::add(main_thread); 3895 } 3896 3897 // Any JVMTI raw monitors entered in onload will transition into 3898 // real raw monitor. VM is setup enough here for raw monitor enter. 3899 JvmtiExport::transition_pending_onload_raw_monitors(); 3900 3901 // Create the VMThread 3902 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3903 3904 VMThread::create(); 3905 Thread* vmthread = VMThread::vm_thread(); 3906 3907 if (!os::create_thread(vmthread, os::vm_thread)) { 3908 vm_exit_during_initialization("Cannot create VM thread. " 3909 "Out of system resources."); 3910 } 3911 3912 // Wait for the VM thread to become ready, and VMThread::run to initialize 3913 // Monitors can have spurious returns, must always check another state flag 3914 { 3915 MonitorLocker ml(Notify_lock); 3916 os::start_thread(vmthread); 3917 while (vmthread->active_handles() == NULL) { 3918 ml.wait(); 3919 } 3920 } 3921 } 3922 3923 assert(Universe::is_fully_initialized(), "not initialized"); 3924 if (VerifyDuringStartup) { 3925 // Make sure we're starting with a clean slate. 3926 VM_Verify verify_op; 3927 VMThread::execute(&verify_op); 3928 } 3929 3930 // We need this to update the java.vm.info property in case any flags used 3931 // to initially define it have been changed. This is needed for both CDS and 3932 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3933 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3934 // This update must happen before we initialize the java classes, but 3935 // after any initialization logic that might modify the flags. 3936 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3937 3938 Thread* THREAD = Thread::current(); 3939 3940 // Always call even when there are not JVMTI environments yet, since environments 3941 // may be attached late and JVMTI must track phases of VM execution 3942 JvmtiExport::enter_early_start_phase(); 3943 3944 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3945 JvmtiExport::post_early_vm_start(); 3946 3947 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3948 3949 quicken_jni_functions(); 3950 3951 // No more stub generation allowed after that point. 3952 StubCodeDesc::freeze(); 3953 3954 // Set flag that basic initialization has completed. Used by exceptions and various 3955 // debug stuff, that does not work until all basic classes have been initialized. 3956 set_init_completed(); 3957 3958 LogConfiguration::post_initialize(); 3959 Metaspace::post_initialize(); 3960 3961 HOTSPOT_VM_INIT_END(); 3962 3963 // record VM initialization completion time 3964 #if INCLUDE_MANAGEMENT 3965 Management::record_vm_init_completed(); 3966 #endif // INCLUDE_MANAGEMENT 3967 3968 // Signal Dispatcher needs to be started before VMInit event is posted 3969 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3970 3971 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3972 if (!DisableAttachMechanism) { 3973 AttachListener::vm_start(); 3974 if (StartAttachListener || AttachListener::init_at_startup()) { 3975 AttachListener::init(); 3976 } 3977 } 3978 3979 // Launch -Xrun agents 3980 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3981 // back-end can launch with -Xdebug -Xrunjdwp. 3982 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3983 create_vm_init_libraries(); 3984 } 3985 3986 if (CleanChunkPoolAsync) { 3987 Chunk::start_chunk_pool_cleaner_task(); 3988 } 3989 3990 // Start the service thread 3991 // The service thread enqueues JVMTI deferred events and does various hashtable 3992 // and other cleanups. Needs to start before the compilers start posting events. 3993 ServiceThread::initialize(); 3994 3995 // initialize compiler(s) 3996 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3997 #if INCLUDE_JVMCI 3998 bool force_JVMCI_intialization = false; 3999 if (EnableJVMCI) { 4000 // Initialize JVMCI eagerly when it is explicitly requested. 4001 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 4002 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 4003 4004 if (!force_JVMCI_intialization) { 4005 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4006 // compilations via JVMCI will not actually block until JVMCI is initialized. 4007 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4008 } 4009 } 4010 #endif 4011 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 4012 // Postpone completion of compiler initialization to after JVMCI 4013 // is initialized to avoid timeouts of blocking compilations. 4014 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 4015 CompileBroker::compilation_init_phase2(); 4016 } 4017 #endif 4018 4019 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4020 // It is done after compilers are initialized, because otherwise compilations of 4021 // signature polymorphic MH intrinsics can be missed 4022 // (see SystemDictionary::find_method_handle_intrinsic). 4023 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4024 4025 // This will initialize the module system. Only java.base classes can be 4026 // loaded until phase 2 completes 4027 call_initPhase2(CHECK_JNI_ERR); 4028 4029 JFR_ONLY(Jfr::on_create_vm_2();) 4030 4031 // Always call even when there are not JVMTI environments yet, since environments 4032 // may be attached late and JVMTI must track phases of VM execution 4033 JvmtiExport::enter_start_phase(); 4034 4035 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4036 JvmtiExport::post_vm_start(); 4037 4038 // Final system initialization including security manager and system class loader 4039 call_initPhase3(CHECK_JNI_ERR); 4040 4041 // cache the system and platform class loaders 4042 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4043 4044 #if INCLUDE_CDS 4045 // capture the module path info from the ModuleEntryTable 4046 ClassLoader::initialize_module_path(THREAD); 4047 #endif 4048 4049 #if INCLUDE_JVMCI 4050 if (force_JVMCI_intialization) { 4051 JVMCI::initialize_compiler(CHECK_JNI_ERR); 4052 CompileBroker::compilation_init_phase2(); 4053 } 4054 #endif 4055 4056 // Always call even when there are not JVMTI environments yet, since environments 4057 // may be attached late and JVMTI must track phases of VM execution 4058 JvmtiExport::enter_live_phase(); 4059 4060 // Make perfmemory accessible 4061 PerfMemory::set_accessible(true); 4062 4063 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4064 JvmtiExport::post_vm_initialized(); 4065 4066 JFR_ONLY(Jfr::on_create_vm_3();) 4067 4068 #if INCLUDE_MANAGEMENT 4069 Management::initialize(THREAD); 4070 4071 if (HAS_PENDING_EXCEPTION) { 4072 // management agent fails to start possibly due to 4073 // configuration problem and is responsible for printing 4074 // stack trace if appropriate. Simply exit VM. 4075 vm_exit(1); 4076 } 4077 #endif // INCLUDE_MANAGEMENT 4078 4079 if (MemProfiling) MemProfiler::engage(); 4080 StatSampler::engage(); 4081 if (CheckJNICalls) JniPeriodicChecker::engage(); 4082 4083 BiasedLocking::init(); 4084 4085 #if INCLUDE_RTM_OPT 4086 RTMLockingCounters::init(); 4087 #endif 4088 4089 call_postVMInitHook(THREAD); 4090 // The Java side of PostVMInitHook.run must deal with all 4091 // exceptions and provide means of diagnosis. 4092 if (HAS_PENDING_EXCEPTION) { 4093 CLEAR_PENDING_EXCEPTION; 4094 } 4095 4096 { 4097 MutexLocker ml(PeriodicTask_lock); 4098 // Make sure the WatcherThread can be started by WatcherThread::start() 4099 // or by dynamic enrollment. 4100 WatcherThread::make_startable(); 4101 // Start up the WatcherThread if there are any periodic tasks 4102 // NOTE: All PeriodicTasks should be registered by now. If they 4103 // aren't, late joiners might appear to start slowly (we might 4104 // take a while to process their first tick). 4105 if (PeriodicTask::num_tasks() > 0) { 4106 WatcherThread::start(); 4107 } 4108 } 4109 4110 create_vm_timer.end(); 4111 #ifdef ASSERT 4112 _vm_complete = true; 4113 #endif 4114 4115 if (DumpSharedSpaces) { 4116 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4117 ShouldNotReachHere(); 4118 } 4119 4120 return JNI_OK; 4121 } 4122 4123 // type for the Agent_OnLoad and JVM_OnLoad entry points 4124 extern "C" { 4125 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4126 } 4127 // Find a command line agent library and return its entry point for 4128 // -agentlib: -agentpath: -Xrun 4129 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4130 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4131 const char *on_load_symbols[], 4132 size_t num_symbol_entries) { 4133 OnLoadEntry_t on_load_entry = NULL; 4134 void *library = NULL; 4135 4136 if (!agent->valid()) { 4137 char buffer[JVM_MAXPATHLEN]; 4138 char ebuf[1024] = ""; 4139 const char *name = agent->name(); 4140 const char *msg = "Could not find agent library "; 4141 4142 // First check to see if agent is statically linked into executable 4143 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4144 library = agent->os_lib(); 4145 } else if (agent->is_absolute_path()) { 4146 library = os::dll_load(name, ebuf, sizeof ebuf); 4147 if (library == NULL) { 4148 const char *sub_msg = " in absolute path, with error: "; 4149 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4150 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4151 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4152 // If we can't find the agent, exit. 4153 vm_exit_during_initialization(buf, NULL); 4154 FREE_C_HEAP_ARRAY(char, buf); 4155 } 4156 } else { 4157 // Try to load the agent from the standard dll directory 4158 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4159 name)) { 4160 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4161 } 4162 if (library == NULL) { // Try the library path directory. 4163 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4164 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4165 } 4166 if (library == NULL) { 4167 const char *sub_msg = " on the library path, with error: "; 4168 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4169 4170 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4171 strlen(ebuf) + strlen(sub_msg2) + 1; 4172 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4173 if (!agent->is_instrument_lib()) { 4174 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4175 } else { 4176 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4177 } 4178 // If we can't find the agent, exit. 4179 vm_exit_during_initialization(buf, NULL); 4180 FREE_C_HEAP_ARRAY(char, buf); 4181 } 4182 } 4183 } 4184 agent->set_os_lib(library); 4185 agent->set_valid(); 4186 } 4187 4188 // Find the OnLoad function. 4189 on_load_entry = 4190 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4191 false, 4192 on_load_symbols, 4193 num_symbol_entries)); 4194 return on_load_entry; 4195 } 4196 4197 // Find the JVM_OnLoad entry point 4198 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4199 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4200 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4201 } 4202 4203 // Find the Agent_OnLoad entry point 4204 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4205 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4206 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4207 } 4208 4209 // For backwards compatibility with -Xrun 4210 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4211 // treated like -agentpath: 4212 // Must be called before agent libraries are created 4213 void Threads::convert_vm_init_libraries_to_agents() { 4214 AgentLibrary* agent; 4215 AgentLibrary* next; 4216 4217 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4218 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4219 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4220 4221 // If there is an JVM_OnLoad function it will get called later, 4222 // otherwise see if there is an Agent_OnLoad 4223 if (on_load_entry == NULL) { 4224 on_load_entry = lookup_agent_on_load(agent); 4225 if (on_load_entry != NULL) { 4226 // switch it to the agent list -- so that Agent_OnLoad will be called, 4227 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4228 Arguments::convert_library_to_agent(agent); 4229 } else { 4230 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4231 } 4232 } 4233 } 4234 } 4235 4236 // Create agents for -agentlib: -agentpath: and converted -Xrun 4237 // Invokes Agent_OnLoad 4238 // Called very early -- before JavaThreads exist 4239 void Threads::create_vm_init_agents() { 4240 extern struct JavaVM_ main_vm; 4241 AgentLibrary* agent; 4242 4243 JvmtiExport::enter_onload_phase(); 4244 4245 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4246 // CDS dumping does not support native JVMTI agent. 4247 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4248 if (Arguments::is_dumping_archive()) { 4249 if(!agent->is_instrument_lib()) { 4250 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4251 } else if (!AllowArchivingWithJavaAgent) { 4252 vm_exit_during_cds_dumping( 4253 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4254 } 4255 } 4256 4257 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4258 4259 if (on_load_entry != NULL) { 4260 // Invoke the Agent_OnLoad function 4261 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4262 if (err != JNI_OK) { 4263 vm_exit_during_initialization("agent library failed to init", agent->name()); 4264 } 4265 } else { 4266 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4267 } 4268 } 4269 4270 JvmtiExport::enter_primordial_phase(); 4271 } 4272 4273 extern "C" { 4274 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4275 } 4276 4277 void Threads::shutdown_vm_agents() { 4278 // Send any Agent_OnUnload notifications 4279 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4280 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4281 extern struct JavaVM_ main_vm; 4282 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4283 4284 // Find the Agent_OnUnload function. 4285 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4286 os::find_agent_function(agent, 4287 false, 4288 on_unload_symbols, 4289 num_symbol_entries)); 4290 4291 // Invoke the Agent_OnUnload function 4292 if (unload_entry != NULL) { 4293 JavaThread* thread = JavaThread::current(); 4294 ThreadToNativeFromVM ttn(thread); 4295 HandleMark hm(thread); 4296 (*unload_entry)(&main_vm); 4297 } 4298 } 4299 } 4300 4301 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4302 // Invokes JVM_OnLoad 4303 void Threads::create_vm_init_libraries() { 4304 extern struct JavaVM_ main_vm; 4305 AgentLibrary* agent; 4306 4307 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4308 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4309 4310 if (on_load_entry != NULL) { 4311 // Invoke the JVM_OnLoad function 4312 JavaThread* thread = JavaThread::current(); 4313 ThreadToNativeFromVM ttn(thread); 4314 HandleMark hm(thread); 4315 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4316 if (err != JNI_OK) { 4317 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4318 } 4319 } else { 4320 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4321 } 4322 } 4323 } 4324 4325 4326 // Last thread running calls java.lang.Shutdown.shutdown() 4327 void JavaThread::invoke_shutdown_hooks() { 4328 HandleMark hm(this); 4329 4330 // Link all classes for dynamic CDS dumping before vm exit. 4331 // Same operation is being done in JVM_BeforeHalt for handling the 4332 // case where the application calls System.exit(). 4333 if (DynamicDumpSharedSpaces) { 4334 MetaspaceShared::link_and_cleanup_shared_classes(this); 4335 } 4336 4337 // We could get here with a pending exception, if so clear it now. 4338 if (this->has_pending_exception()) { 4339 this->clear_pending_exception(); 4340 } 4341 4342 EXCEPTION_MARK; 4343 Klass* shutdown_klass = 4344 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4345 THREAD); 4346 if (shutdown_klass != NULL) { 4347 // SystemDictionary::resolve_or_null will return null if there was 4348 // an exception. If we cannot load the Shutdown class, just don't 4349 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4350 // won't be run. Note that if a shutdown hook was registered, 4351 // the Shutdown class would have already been loaded 4352 // (Runtime.addShutdownHook will load it). 4353 JavaValue result(T_VOID); 4354 JavaCalls::call_static(&result, 4355 shutdown_klass, 4356 vmSymbols::shutdown_name(), 4357 vmSymbols::void_method_signature(), 4358 THREAD); 4359 } 4360 CLEAR_PENDING_EXCEPTION; 4361 } 4362 4363 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4364 // the program falls off the end of main(). Another VM exit path is through 4365 // vm_exit() when the program calls System.exit() to return a value or when 4366 // there is a serious error in VM. The two shutdown paths are not exactly 4367 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4368 // and VM_Exit op at VM level. 4369 // 4370 // Shutdown sequence: 4371 // + Shutdown native memory tracking if it is on 4372 // + Wait until we are the last non-daemon thread to execute 4373 // <-- every thing is still working at this moment --> 4374 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4375 // shutdown hooks 4376 // + Call before_exit(), prepare for VM exit 4377 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4378 // currently the only user of this mechanism is File.deleteOnExit()) 4379 // > stop StatSampler, watcher thread, 4380 // post thread end and vm death events to JVMTI, 4381 // stop signal thread 4382 // + Call JavaThread::exit(), it will: 4383 // > release JNI handle blocks, remove stack guard pages 4384 // > remove this thread from Threads list 4385 // <-- no more Java code from this thread after this point --> 4386 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4387 // the compiler threads at safepoint 4388 // <-- do not use anything that could get blocked by Safepoint --> 4389 // + Disable tracing at JNI/JVM barriers 4390 // + Set _vm_exited flag for threads that are still running native code 4391 // + Call exit_globals() 4392 // > deletes tty 4393 // > deletes PerfMemory resources 4394 // + Delete this thread 4395 // + Return to caller 4396 4397 bool Threads::destroy_vm() { 4398 JavaThread* thread = JavaThread::current(); 4399 4400 #ifdef ASSERT 4401 _vm_complete = false; 4402 #endif 4403 // Wait until we are the last non-daemon thread to execute 4404 { MonitorLocker nu(Threads_lock); 4405 while (Threads::number_of_non_daemon_threads() > 1) 4406 // This wait should make safepoint checks, wait without a timeout, 4407 // and wait as a suspend-equivalent condition. 4408 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4409 } 4410 4411 EventShutdown e; 4412 if (e.should_commit()) { 4413 e.set_reason("No remaining non-daemon Java threads"); 4414 e.commit(); 4415 } 4416 4417 // Hang forever on exit if we are reporting an error. 4418 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4419 os::infinite_sleep(); 4420 } 4421 os::wait_for_keypress_at_exit(); 4422 4423 // run Java level shutdown hooks 4424 thread->invoke_shutdown_hooks(); 4425 4426 before_exit(thread); 4427 4428 thread->exit(true); 4429 4430 // Stop VM thread. 4431 { 4432 // 4945125 The vm thread comes to a safepoint during exit. 4433 // GC vm_operations can get caught at the safepoint, and the 4434 // heap is unparseable if they are caught. Grab the Heap_lock 4435 // to prevent this. The GC vm_operations will not be able to 4436 // queue until after the vm thread is dead. After this point, 4437 // we'll never emerge out of the safepoint before the VM exits. 4438 4439 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4440 4441 VMThread::wait_for_vm_thread_exit(); 4442 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4443 VMThread::destroy(); 4444 } 4445 4446 // Now, all Java threads are gone except daemon threads. Daemon threads 4447 // running Java code or in VM are stopped by the Safepoint. However, 4448 // daemon threads executing native code are still running. But they 4449 // will be stopped at native=>Java/VM barriers. Note that we can't 4450 // simply kill or suspend them, as it is inherently deadlock-prone. 4451 4452 VM_Exit::set_vm_exited(); 4453 4454 // Clean up ideal graph printers after the VMThread has started 4455 // the final safepoint which will block all the Compiler threads. 4456 // Note that this Thread has already logically exited so the 4457 // clean_up() function's use of a JavaThreadIteratorWithHandle 4458 // would be a problem except set_vm_exited() has remembered the 4459 // shutdown thread which is granted a policy exception. 4460 #if defined(COMPILER2) && !defined(PRODUCT) 4461 IdealGraphPrinter::clean_up(); 4462 #endif 4463 4464 notify_vm_shutdown(); 4465 4466 // exit_globals() will delete tty 4467 exit_globals(); 4468 4469 // We are after VM_Exit::set_vm_exited() so we can't call 4470 // thread->smr_delete() or we will block on the Threads_lock. 4471 // Deleting the shutdown thread here is safe because another 4472 // JavaThread cannot have an active ThreadsListHandle for 4473 // this JavaThread. 4474 delete thread; 4475 4476 #if INCLUDE_JVMCI 4477 if (JVMCICounterSize > 0) { 4478 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4479 } 4480 #endif 4481 4482 LogConfiguration::finalize(); 4483 4484 return true; 4485 } 4486 4487 4488 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4489 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4490 return is_supported_jni_version(version); 4491 } 4492 4493 4494 jboolean Threads::is_supported_jni_version(jint version) { 4495 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4496 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4497 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4498 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4499 if (version == JNI_VERSION_9) return JNI_TRUE; 4500 if (version == JNI_VERSION_10) return JNI_TRUE; 4501 return JNI_FALSE; 4502 } 4503 4504 4505 void Threads::add(JavaThread* p, bool force_daemon) { 4506 // The threads lock must be owned at this point 4507 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4508 4509 BarrierSet::barrier_set()->on_thread_attach(p); 4510 4511 // Once a JavaThread is added to the Threads list, smr_delete() has 4512 // to be used to delete it. Otherwise we can just delete it directly. 4513 p->set_on_thread_list(); 4514 4515 _number_of_threads++; 4516 oop threadObj = p->threadObj(); 4517 bool daemon = true; 4518 // Bootstrapping problem: threadObj can be null for initial 4519 // JavaThread (or for threads attached via JNI) 4520 if ((!force_daemon) && !is_daemon((threadObj))) { 4521 _number_of_non_daemon_threads++; 4522 daemon = false; 4523 } 4524 4525 ThreadService::add_thread(p, daemon); 4526 4527 // Maintain fast thread list 4528 ThreadsSMRSupport::add_thread(p); 4529 4530 // Possible GC point. 4531 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4532 } 4533 4534 void Threads::remove(JavaThread* p, bool is_daemon) { 4535 4536 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4537 ObjectSynchronizer::om_flush(p); 4538 4539 // Extra scope needed for Thread_lock, so we can check 4540 // that we do not remove thread without safepoint code notice 4541 { MonitorLocker ml(Threads_lock); 4542 4543 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4544 4545 // Maintain fast thread list 4546 ThreadsSMRSupport::remove_thread(p); 4547 4548 _number_of_threads--; 4549 if (!is_daemon) { 4550 _number_of_non_daemon_threads--; 4551 4552 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4553 // on destroy_vm will wake up. 4554 if (number_of_non_daemon_threads() == 1) { 4555 ml.notify_all(); 4556 } 4557 } 4558 ThreadService::remove_thread(p, is_daemon); 4559 4560 // Make sure that safepoint code disregard this thread. This is needed since 4561 // the thread might mess around with locks after this point. This can cause it 4562 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4563 // of this thread since it is removed from the queue. 4564 p->set_terminated_value(); 4565 } // unlock Threads_lock 4566 4567 // Since Events::log uses a lock, we grab it outside the Threads_lock 4568 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4569 } 4570 4571 // Operations on the Threads list for GC. These are not explicitly locked, 4572 // but the garbage collector must provide a safe context for them to run. 4573 // In particular, these things should never be called when the Threads_lock 4574 // is held by some other thread. (Note: the Safepoint abstraction also 4575 // uses the Threads_lock to guarantee this property. It also makes sure that 4576 // all threads gets blocked when exiting or starting). 4577 4578 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4579 ALL_JAVA_THREADS(p) { 4580 p->oops_do(f, cf); 4581 } 4582 VMThread::vm_thread()->oops_do(f, cf); 4583 } 4584 4585 void Threads::change_thread_claim_token() { 4586 if (++_thread_claim_token == 0) { 4587 // On overflow of the token counter, there is a risk of future 4588 // collisions between a new global token value and a stale token 4589 // for a thread, because not all iterations visit all threads. 4590 // (Though it's pretty much a theoretical concern for non-trivial 4591 // token counter sizes.) To deal with the possibility, reset all 4592 // the thread tokens to zero on global token overflow. 4593 struct ResetClaims : public ThreadClosure { 4594 virtual void do_thread(Thread* t) { 4595 t->claim_threads_do(false, 0); 4596 } 4597 } reset_claims; 4598 Threads::threads_do(&reset_claims); 4599 // On overflow, update the global token to non-zero, to 4600 // avoid the special "never claimed" initial thread value. 4601 _thread_claim_token = 1; 4602 } 4603 } 4604 4605 #ifdef ASSERT 4606 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4607 const uintx token = t->threads_do_token(); 4608 assert(token == expected, 4609 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4610 UINTX_FORMAT, kind, p2i(t), token, expected); 4611 } 4612 4613 void Threads::assert_all_threads_claimed() { 4614 ALL_JAVA_THREADS(p) { 4615 assert_thread_claimed("Thread", p, _thread_claim_token); 4616 } 4617 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4618 } 4619 #endif // ASSERT 4620 4621 class ParallelOopsDoThreadClosure : public ThreadClosure { 4622 private: 4623 OopClosure* _f; 4624 CodeBlobClosure* _cf; 4625 public: 4626 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4627 void do_thread(Thread* t) { 4628 t->oops_do(_f, _cf); 4629 } 4630 }; 4631 4632 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4633 ParallelOopsDoThreadClosure tc(f, cf); 4634 possibly_parallel_threads_do(is_par, &tc); 4635 } 4636 4637 void Threads::nmethods_do(CodeBlobClosure* cf) { 4638 ALL_JAVA_THREADS(p) { 4639 // This is used by the code cache sweeper to mark nmethods that are active 4640 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4641 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4642 if(!p->is_Code_cache_sweeper_thread()) { 4643 p->nmethods_do(cf); 4644 } 4645 } 4646 } 4647 4648 void Threads::metadata_do(MetadataClosure* f) { 4649 ALL_JAVA_THREADS(p) { 4650 p->metadata_do(f); 4651 } 4652 } 4653 4654 class ThreadHandlesClosure : public ThreadClosure { 4655 void (*_f)(Metadata*); 4656 public: 4657 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4658 virtual void do_thread(Thread* thread) { 4659 thread->metadata_handles_do(_f); 4660 } 4661 }; 4662 4663 void Threads::metadata_handles_do(void f(Metadata*)) { 4664 // Only walk the Handles in Thread. 4665 ThreadHandlesClosure handles_closure(f); 4666 threads_do(&handles_closure); 4667 } 4668 4669 // Get count Java threads that are waiting to enter the specified monitor. 4670 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4671 int count, 4672 address monitor) { 4673 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4674 4675 int i = 0; 4676 DO_JAVA_THREADS(t_list, p) { 4677 if (!p->can_call_java()) continue; 4678 4679 address pending = (address)p->current_pending_monitor(); 4680 if (pending == monitor) { // found a match 4681 if (i < count) result->append(p); // save the first count matches 4682 i++; 4683 } 4684 } 4685 4686 return result; 4687 } 4688 4689 4690 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4691 address owner) { 4692 // NULL owner means not locked so we can skip the search 4693 if (owner == NULL) return NULL; 4694 4695 DO_JAVA_THREADS(t_list, p) { 4696 // first, see if owner is the address of a Java thread 4697 if (owner == (address)p) return p; 4698 } 4699 4700 // Cannot assert on lack of success here since this function may be 4701 // used by code that is trying to report useful problem information 4702 // like deadlock detection. 4703 if (UseHeavyMonitors) return NULL; 4704 4705 // If we didn't find a matching Java thread and we didn't force use of 4706 // heavyweight monitors, then the owner is the stack address of the 4707 // Lock Word in the owning Java thread's stack. 4708 // 4709 JavaThread* the_owner = NULL; 4710 DO_JAVA_THREADS(t_list, q) { 4711 if (q->is_lock_owned(owner)) { 4712 the_owner = q; 4713 break; 4714 } 4715 } 4716 4717 // cannot assert on lack of success here; see above comment 4718 return the_owner; 4719 } 4720 4721 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4722 void Threads::print_on(outputStream* st, bool print_stacks, 4723 bool internal_format, bool print_concurrent_locks, 4724 bool print_extended_info) { 4725 char buf[32]; 4726 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4727 4728 st->print_cr("Full thread dump %s (%s %s):", 4729 VM_Version::vm_name(), 4730 VM_Version::vm_release(), 4731 VM_Version::vm_info_string()); 4732 st->cr(); 4733 4734 #if INCLUDE_SERVICES 4735 // Dump concurrent locks 4736 ConcurrentLocksDump concurrent_locks; 4737 if (print_concurrent_locks) { 4738 concurrent_locks.dump_at_safepoint(); 4739 } 4740 #endif // INCLUDE_SERVICES 4741 4742 ThreadsSMRSupport::print_info_on(st); 4743 st->cr(); 4744 4745 ALL_JAVA_THREADS(p) { 4746 ResourceMark rm; 4747 p->print_on(st, print_extended_info); 4748 if (print_stacks) { 4749 if (internal_format) { 4750 p->trace_stack(); 4751 } else { 4752 p->print_stack_on(st); 4753 } 4754 } 4755 st->cr(); 4756 #if INCLUDE_SERVICES 4757 if (print_concurrent_locks) { 4758 concurrent_locks.print_locks_on(p, st); 4759 } 4760 #endif // INCLUDE_SERVICES 4761 } 4762 4763 VMThread::vm_thread()->print_on(st); 4764 st->cr(); 4765 Universe::heap()->print_gc_threads_on(st); 4766 WatcherThread* wt = WatcherThread::watcher_thread(); 4767 if (wt != NULL) { 4768 wt->print_on(st); 4769 st->cr(); 4770 } 4771 4772 st->flush(); 4773 } 4774 4775 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4776 int buflen, bool* found_current) { 4777 if (this_thread != NULL) { 4778 bool is_current = (current == this_thread); 4779 *found_current = *found_current || is_current; 4780 st->print("%s", is_current ? "=>" : " "); 4781 4782 st->print(PTR_FORMAT, p2i(this_thread)); 4783 st->print(" "); 4784 this_thread->print_on_error(st, buf, buflen); 4785 st->cr(); 4786 } 4787 } 4788 4789 class PrintOnErrorClosure : public ThreadClosure { 4790 outputStream* _st; 4791 Thread* _current; 4792 char* _buf; 4793 int _buflen; 4794 bool* _found_current; 4795 public: 4796 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4797 int buflen, bool* found_current) : 4798 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4799 4800 virtual void do_thread(Thread* thread) { 4801 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4802 } 4803 }; 4804 4805 // Threads::print_on_error() is called by fatal error handler. It's possible 4806 // that VM is not at safepoint and/or current thread is inside signal handler. 4807 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4808 // memory (even in resource area), it might deadlock the error handler. 4809 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4810 int buflen) { 4811 ThreadsSMRSupport::print_info_on(st); 4812 st->cr(); 4813 4814 bool found_current = false; 4815 st->print_cr("Java Threads: ( => current thread )"); 4816 ALL_JAVA_THREADS(thread) { 4817 print_on_error(thread, st, current, buf, buflen, &found_current); 4818 } 4819 st->cr(); 4820 4821 st->print_cr("Other Threads:"); 4822 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4823 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4824 4825 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4826 Universe::heap()->gc_threads_do(&print_closure); 4827 4828 if (!found_current) { 4829 st->cr(); 4830 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4831 current->print_on_error(st, buf, buflen); 4832 st->cr(); 4833 } 4834 st->cr(); 4835 4836 st->print_cr("Threads with active compile tasks:"); 4837 print_threads_compiling(st, buf, buflen); 4838 } 4839 4840 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4841 ALL_JAVA_THREADS(thread) { 4842 if (thread->is_Compiler_thread()) { 4843 CompilerThread* ct = (CompilerThread*) thread; 4844 4845 // Keep task in local variable for NULL check. 4846 // ct->_task might be set to NULL by concurring compiler thread 4847 // because it completed the compilation. The task is never freed, 4848 // though, just returned to a free list. 4849 CompileTask* task = ct->task(); 4850 if (task != NULL) { 4851 thread->print_name_on_error(st, buf, buflen); 4852 st->print(" "); 4853 task->print(st, NULL, short_form, true); 4854 } 4855 } 4856 } 4857 } 4858 4859 4860 // Internal SpinLock and Mutex 4861 // Based on ParkEvent 4862 4863 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4864 // 4865 // We employ SpinLocks _only for low-contention, fixed-length 4866 // short-duration critical sections where we're concerned 4867 // about native mutex_t or HotSpot Mutex:: latency. 4868 // The mux construct provides a spin-then-block mutual exclusion 4869 // mechanism. 4870 // 4871 // Testing has shown that contention on the ListLock guarding gFreeList 4872 // is common. If we implement ListLock as a simple SpinLock it's common 4873 // for the JVM to devolve to yielding with little progress. This is true 4874 // despite the fact that the critical sections protected by ListLock are 4875 // extremely short. 4876 // 4877 // TODO-FIXME: ListLock should be of type SpinLock. 4878 // We should make this a 1st-class type, integrated into the lock 4879 // hierarchy as leaf-locks. Critically, the SpinLock structure 4880 // should have sufficient padding to avoid false-sharing and excessive 4881 // cache-coherency traffic. 4882 4883 4884 typedef volatile int SpinLockT; 4885 4886 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4887 if (Atomic::cmpxchg(adr, 0, 1) == 0) { 4888 return; // normal fast-path return 4889 } 4890 4891 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4892 int ctr = 0; 4893 int Yields = 0; 4894 for (;;) { 4895 while (*adr != 0) { 4896 ++ctr; 4897 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4898 if (Yields > 5) { 4899 os::naked_short_sleep(1); 4900 } else { 4901 os::naked_yield(); 4902 ++Yields; 4903 } 4904 } else { 4905 SpinPause(); 4906 } 4907 } 4908 if (Atomic::cmpxchg(adr, 0, 1) == 0) return; 4909 } 4910 } 4911 4912 void Thread::SpinRelease(volatile int * adr) { 4913 assert(*adr != 0, "invariant"); 4914 OrderAccess::fence(); // guarantee at least release consistency. 4915 // Roach-motel semantics. 4916 // It's safe if subsequent LDs and STs float "up" into the critical section, 4917 // but prior LDs and STs within the critical section can't be allowed 4918 // to reorder or float past the ST that releases the lock. 4919 // Loads and stores in the critical section - which appear in program 4920 // order before the store that releases the lock - must also appear 4921 // before the store that releases the lock in memory visibility order. 4922 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4923 // the ST of 0 into the lock-word which releases the lock, so fence 4924 // more than covers this on all platforms. 4925 *adr = 0; 4926 } 4927 4928 // muxAcquire and muxRelease: 4929 // 4930 // * muxAcquire and muxRelease support a single-word lock-word construct. 4931 // The LSB of the word is set IFF the lock is held. 4932 // The remainder of the word points to the head of a singly-linked list 4933 // of threads blocked on the lock. 4934 // 4935 // * The current implementation of muxAcquire-muxRelease uses its own 4936 // dedicated Thread._MuxEvent instance. If we're interested in 4937 // minimizing the peak number of extant ParkEvent instances then 4938 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4939 // as certain invariants were satisfied. Specifically, care would need 4940 // to be taken with regards to consuming unpark() "permits". 4941 // A safe rule of thumb is that a thread would never call muxAcquire() 4942 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4943 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4944 // consume an unpark() permit intended for monitorenter, for instance. 4945 // One way around this would be to widen the restricted-range semaphore 4946 // implemented in park(). Another alternative would be to provide 4947 // multiple instances of the PlatformEvent() for each thread. One 4948 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4949 // 4950 // * Usage: 4951 // -- Only as leaf locks 4952 // -- for short-term locking only as muxAcquire does not perform 4953 // thread state transitions. 4954 // 4955 // Alternatives: 4956 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4957 // but with parking or spin-then-park instead of pure spinning. 4958 // * Use Taura-Oyama-Yonenzawa locks. 4959 // * It's possible to construct a 1-0 lock if we encode the lockword as 4960 // (List,LockByte). Acquire will CAS the full lockword while Release 4961 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4962 // acquiring threads use timers (ParkTimed) to detect and recover from 4963 // the stranding window. Thread/Node structures must be aligned on 256-byte 4964 // boundaries by using placement-new. 4965 // * Augment MCS with advisory back-link fields maintained with CAS(). 4966 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4967 // The validity of the backlinks must be ratified before we trust the value. 4968 // If the backlinks are invalid the exiting thread must back-track through the 4969 // the forward links, which are always trustworthy. 4970 // * Add a successor indication. The LockWord is currently encoded as 4971 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4972 // to provide the usual futile-wakeup optimization. 4973 // See RTStt for details. 4974 // 4975 4976 4977 const intptr_t LOCKBIT = 1; 4978 4979 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4980 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT); 4981 if (w == 0) return; 4982 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4983 return; 4984 } 4985 4986 ParkEvent * const Self = Thread::current()->_MuxEvent; 4987 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4988 for (;;) { 4989 int its = (os::is_MP() ? 100 : 0) + 1; 4990 4991 // Optional spin phase: spin-then-park strategy 4992 while (--its >= 0) { 4993 w = *Lock; 4994 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4995 return; 4996 } 4997 } 4998 4999 Self->reset(); 5000 Self->OnList = intptr_t(Lock); 5001 // The following fence() isn't _strictly necessary as the subsequent 5002 // CAS() both serializes execution and ratifies the fetched *Lock value. 5003 OrderAccess::fence(); 5004 for (;;) { 5005 w = *Lock; 5006 if ((w & LOCKBIT) == 0) { 5007 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5008 Self->OnList = 0; // hygiene - allows stronger asserts 5009 return; 5010 } 5011 continue; // Interference -- *Lock changed -- Just retry 5012 } 5013 assert(w & LOCKBIT, "invariant"); 5014 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5015 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break; 5016 } 5017 5018 while (Self->OnList != 0) { 5019 Self->park(); 5020 } 5021 } 5022 } 5023 5024 // Release() must extract a successor from the list and then wake that thread. 5025 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5026 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5027 // Release() would : 5028 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5029 // (B) Extract a successor from the private list "in-hand" 5030 // (C) attempt to CAS() the residual back into *Lock over null. 5031 // If there were any newly arrived threads and the CAS() would fail. 5032 // In that case Release() would detach the RATs, re-merge the list in-hand 5033 // with the RATs and repeat as needed. Alternately, Release() might 5034 // detach and extract a successor, but then pass the residual list to the wakee. 5035 // The wakee would be responsible for reattaching and remerging before it 5036 // competed for the lock. 5037 // 5038 // Both "pop" and DMR are immune from ABA corruption -- there can be 5039 // multiple concurrent pushers, but only one popper or detacher. 5040 // This implementation pops from the head of the list. This is unfair, 5041 // but tends to provide excellent throughput as hot threads remain hot. 5042 // (We wake recently run threads first). 5043 // 5044 // All paths through muxRelease() will execute a CAS. 5045 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5046 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5047 // executed within the critical section are complete and globally visible before the 5048 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5049 void Thread::muxRelease(volatile intptr_t * Lock) { 5050 for (;;) { 5051 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0); 5052 assert(w & LOCKBIT, "invariant"); 5053 if (w == LOCKBIT) return; 5054 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5055 assert(List != NULL, "invariant"); 5056 assert(List->OnList == intptr_t(Lock), "invariant"); 5057 ParkEvent * const nxt = List->ListNext; 5058 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5059 5060 // The following CAS() releases the lock and pops the head element. 5061 // The CAS() also ratifies the previously fetched lock-word value. 5062 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) { 5063 continue; 5064 } 5065 List->OnList = 0; 5066 OrderAccess::fence(); 5067 List->unpark(); 5068 return; 5069 } 5070 } 5071 5072 5073 void Threads::verify() { 5074 ALL_JAVA_THREADS(p) { 5075 p->verify(); 5076 } 5077 VMThread* thread = VMThread::vm_thread(); 5078 if (thread != NULL) thread->verify(); 5079 }