1 /* 2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "jvm.h" 27 #include "classfile/classLoader.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/barrierSet.hpp" 37 #include "gc/shared/gcId.hpp" 38 #include "gc/shared/gcLocker.inline.hpp" 39 #include "gc/shared/workgroup.hpp" 40 #include "interpreter/interpreter.hpp" 41 #include "interpreter/linkResolver.hpp" 42 #include "interpreter/oopMapCache.hpp" 43 #include "jfr/jfrEvents.hpp" 44 #include "jvmtifiles/jvmtiEnv.hpp" 45 #include "logging/log.hpp" 46 #include "logging/logConfiguration.hpp" 47 #include "logging/logStream.hpp" 48 #include "memory/allocation.inline.hpp" 49 #include "memory/metaspaceShared.hpp" 50 #include "memory/oopFactory.hpp" 51 #include "memory/resourceArea.hpp" 52 #include "memory/universe.hpp" 53 #include "oops/access.inline.hpp" 54 #include "oops/instanceKlass.hpp" 55 #include "oops/objArrayOop.hpp" 56 #include "oops/oop.inline.hpp" 57 #include "oops/symbol.hpp" 58 #include "oops/typeArrayOop.inline.hpp" 59 #include "oops/verifyOopClosure.hpp" 60 #include "prims/jvm_misc.hpp" 61 #include "prims/jvmtiExport.hpp" 62 #include "prims/jvmtiThreadState.hpp" 63 #include "runtime/arguments.hpp" 64 #include "runtime/atomic.hpp" 65 #include "runtime/biasedLocking.hpp" 66 #include "runtime/fieldDescriptor.inline.hpp" 67 #include "runtime/flags/jvmFlagConstraintList.hpp" 68 #include "runtime/flags/jvmFlagRangeList.hpp" 69 #include "runtime/flags/jvmFlagWriteableList.hpp" 70 #include "runtime/deoptimization.hpp" 71 #include "runtime/frame.inline.hpp" 72 #include "runtime/handles.inline.hpp" 73 #include "runtime/handshake.hpp" 74 #include "runtime/init.hpp" 75 #include "runtime/interfaceSupport.inline.hpp" 76 #include "runtime/java.hpp" 77 #include "runtime/javaCalls.hpp" 78 #include "runtime/jniHandles.inline.hpp" 79 #include "runtime/jniPeriodicChecker.hpp" 80 #include "runtime/memprofiler.hpp" 81 #include "runtime/mutexLocker.hpp" 82 #include "runtime/objectMonitor.hpp" 83 #include "runtime/orderAccess.hpp" 84 #include "runtime/osThread.hpp" 85 #include "runtime/prefetch.inline.hpp" 86 #include "runtime/safepoint.hpp" 87 #include "runtime/safepointMechanism.inline.hpp" 88 #include "runtime/safepointVerifiers.hpp" 89 #include "runtime/sharedRuntime.hpp" 90 #include "runtime/statSampler.hpp" 91 #include "runtime/stubRoutines.hpp" 92 #include "runtime/sweeper.hpp" 93 #include "runtime/task.hpp" 94 #include "runtime/thread.inline.hpp" 95 #include "runtime/threadCritical.hpp" 96 #include "runtime/threadSMR.inline.hpp" 97 #include "runtime/threadStatisticalInfo.hpp" 98 #include "runtime/timer.hpp" 99 #include "runtime/timerTrace.hpp" 100 #include "runtime/vframe.inline.hpp" 101 #include "runtime/vframeArray.hpp" 102 #include "runtime/vframe_hp.hpp" 103 #include "runtime/vmThread.hpp" 104 #include "runtime/vmOperations.hpp" 105 #include "runtime/vm_version.hpp" 106 #include "services/attachListener.hpp" 107 #include "services/management.hpp" 108 #include "services/memTracker.hpp" 109 #include "services/threadService.hpp" 110 #include "utilities/align.hpp" 111 #include "utilities/copy.hpp" 112 #include "utilities/defaultStream.hpp" 113 #include "utilities/dtrace.hpp" 114 #include "utilities/events.hpp" 115 #include "utilities/macros.hpp" 116 #include "utilities/preserveException.hpp" 117 #include "utilities/singleWriterSynchronizer.hpp" 118 #include "utilities/vmError.hpp" 119 #if INCLUDE_JVMCI 120 #include "jvmci/jvmci.hpp" 121 #include "jvmci/jvmciEnv.hpp" 122 #endif 123 #ifdef COMPILER1 124 #include "c1/c1_Compiler.hpp" 125 #endif 126 #ifdef COMPILER2 127 #include "opto/c2compiler.hpp" 128 #include "opto/idealGraphPrinter.hpp" 129 #endif 130 #if INCLUDE_RTM_OPT 131 #include "runtime/rtmLocking.hpp" 132 #endif 133 #if INCLUDE_JFR 134 #include "jfr/jfr.hpp" 135 #endif 136 137 // Initialization after module runtime initialization 138 void universe_post_module_init(); // must happen after call_initPhase2 139 140 #ifdef DTRACE_ENABLED 141 142 // Only bother with this argument setup if dtrace is available 143 144 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 145 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 146 147 #define DTRACE_THREAD_PROBE(probe, javathread) \ 148 { \ 149 ResourceMark rm(this); \ 150 int len = 0; \ 151 const char* name = (javathread)->get_thread_name(); \ 152 len = strlen(name); \ 153 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 154 (char *) name, len, \ 155 java_lang_Thread::thread_id((javathread)->threadObj()), \ 156 (uintptr_t) (javathread)->osthread()->thread_id(), \ 157 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 158 } 159 160 #else // ndef DTRACE_ENABLED 161 162 #define DTRACE_THREAD_PROBE(probe, javathread) 163 164 #endif // ndef DTRACE_ENABLED 165 166 #ifndef USE_LIBRARY_BASED_TLS_ONLY 167 // Current thread is maintained as a thread-local variable 168 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 169 #endif 170 171 // ======= Thread ======== 172 // Support for forcing alignment of thread objects for biased locking 173 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 174 if (UseBiasedLocking) { 175 const int alignment = markOopDesc::biased_lock_alignment; 176 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 177 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 178 : AllocateHeap(aligned_size, flags, CURRENT_PC, 179 AllocFailStrategy::RETURN_NULL); 180 void* aligned_addr = align_up(real_malloc_addr, alignment); 181 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 182 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 183 "JavaThread alignment code overflowed allocated storage"); 184 if (aligned_addr != real_malloc_addr) { 185 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 186 p2i(real_malloc_addr), 187 p2i(aligned_addr)); 188 } 189 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 190 return aligned_addr; 191 } else { 192 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 193 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 194 } 195 } 196 197 void Thread::operator delete(void* p) { 198 if (UseBiasedLocking) { 199 FreeHeap(((Thread*) p)->_real_malloc_address); 200 } else { 201 FreeHeap(p); 202 } 203 } 204 205 void JavaThread::smr_delete() { 206 if (_on_thread_list) { 207 ThreadsSMRSupport::smr_delete(this); 208 } else { 209 delete this; 210 } 211 } 212 213 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 214 // JavaThread 215 216 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;) 217 218 Thread::Thread() { 219 220 DEBUG_ONLY(_run_state = PRE_CALL_RUN;) 221 222 // stack and get_thread 223 set_stack_base(NULL); 224 set_stack_size(0); 225 set_self_raw_id(0); 226 set_lgrp_id(-1); 227 DEBUG_ONLY(clear_suspendible_thread();) 228 229 // allocated data structures 230 set_osthread(NULL); 231 set_resource_area(new (mtThread)ResourceArea()); 232 DEBUG_ONLY(_current_resource_mark = NULL;) 233 set_handle_area(new (mtThread) HandleArea(NULL)); 234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 235 set_active_handles(NULL); 236 set_free_handle_block(NULL); 237 set_last_handle_mark(NULL); 238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 239 240 // Initial value of zero ==> never claimed. 241 _threads_do_token = 0; 242 _threads_hazard_ptr = NULL; 243 _threads_list_ptr = NULL; 244 _nested_threads_hazard_ptr_cnt = 0; 245 _rcu_counter = 0; 246 247 // the handle mark links itself to last_handle_mark 248 new HandleMark(this); 249 250 // plain initialization 251 debug_only(_owned_locks = NULL;) 252 debug_only(_allow_allocation_count = 0;) 253 NOT_PRODUCT(_allow_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 _num_nested_signal = 0; 263 omFreeList = NULL; 264 omFreeCount = 0; 265 omFreeProvision = 32; 266 omInUseList = NULL; 267 omInUseCount = 0; 268 269 #ifdef ASSERT 270 _visited_for_critical_count = false; 271 #endif 272 273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 274 Monitor::_safepoint_check_sometimes); 275 _suspend_flags = 0; 276 277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 278 _hashStateX = os::random(); 279 _hashStateY = 842502087; 280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 281 _hashStateW = 273326509; 282 283 _OnTrap = 0; 284 _Stalled = 0; 285 _TypeTag = 0x2BAD; 286 287 // Many of the following fields are effectively final - immutable 288 // Note that nascent threads can't use the Native Monitor-Mutex 289 // construct until the _MutexEvent is initialized ... 290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 291 // we might instead use a stack of ParkEvents that we could provision on-demand. 292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 293 // and ::Release() 294 _ParkEvent = ParkEvent::Allocate(this); 295 _SleepEvent = 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((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 306 assert(this == _real_malloc_address || 307 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 308 "bug in forced alignment of thread objects"); 309 } 310 #endif // ASSERT 311 312 // Notify the barrier set that a thread is being created. The initial 313 // thread is created before the barrier set is available. The call to 314 // BarrierSet::on_thread_create() for this thread is therefore deferred 315 // to BarrierSet::set_barrier_set(). 316 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 317 if (barrier_set != NULL) { 318 barrier_set->on_thread_create(this); 319 } else { 320 // Only the main thread should be created before the barrier set 321 // and that happens just before Thread::current is set. No other thread 322 // can attach as the VM is not created yet, so they can't execute this code. 323 // If the main thread creates other threads before the barrier set that is an error. 324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 325 } 326 } 327 328 void Thread::initialize_thread_current() { 329 #ifndef USE_LIBRARY_BASED_TLS_ONLY 330 assert(_thr_current == NULL, "Thread::current already initialized"); 331 _thr_current = this; 332 #endif 333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 334 ThreadLocalStorage::set_thread(this); 335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 336 } 337 338 void Thread::clear_thread_current() { 339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 340 #ifndef USE_LIBRARY_BASED_TLS_ONLY 341 _thr_current = NULL; 342 #endif 343 ThreadLocalStorage::set_thread(NULL); 344 } 345 346 void Thread::record_stack_base_and_size() { 347 // Note: at this point, Thread object is not yet initialized. Do not rely on 348 // any members being initialized. Do not rely on Thread::current() being set. 349 // If possible, refrain from doing anything which may crash or assert since 350 // quite probably those crash dumps will be useless. 351 set_stack_base(os::current_stack_base()); 352 set_stack_size(os::current_stack_size()); 353 354 #ifdef SOLARIS 355 if (os::is_primordial_thread()) { 356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 357 } 358 #endif 359 360 // Set stack limits after thread is initialized. 361 if (is_Java_thread()) { 362 ((JavaThread*) this)->set_stack_overflow_limit(); 363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 364 } 365 } 366 367 #if INCLUDE_NMT 368 void Thread::register_thread_stack_with_NMT() { 369 MemTracker::record_thread_stack(stack_end(), stack_size()); 370 } 371 #endif // INCLUDE_NMT 372 373 void Thread::call_run() { 374 DEBUG_ONLY(_run_state = CALL_RUN;) 375 376 // At this point, Thread object should be fully initialized and 377 // Thread::current() should be set. 378 379 assert(Thread::current_or_null() != NULL, "current thread is unset"); 380 assert(Thread::current_or_null() == this, "current thread is wrong"); 381 382 // Perform common initialization actions 383 384 register_thread_stack_with_NMT(); 385 386 JFR_ONLY(Jfr::on_thread_start(this);) 387 388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 390 os::current_thread_id(), p2i(stack_base() - stack_size()), 391 p2i(stack_base()), stack_size()/1024); 392 393 // Perform <ChildClass> initialization actions 394 DEBUG_ONLY(_run_state = PRE_RUN;) 395 this->pre_run(); 396 397 // Invoke <ChildClass>::run() 398 DEBUG_ONLY(_run_state = RUN;) 399 this->run(); 400 // Returned from <ChildClass>::run(). Thread finished. 401 402 // Perform common tear-down actions 403 404 assert(Thread::current_or_null() != NULL, "current thread is unset"); 405 assert(Thread::current_or_null() == this, "current thread is wrong"); 406 407 // Perform <ChildClass> tear-down actions 408 DEBUG_ONLY(_run_state = POST_RUN;) 409 this->post_run(); 410 411 // Note: at this point the thread object may already have deleted itself, 412 // so from here on do not dereference *this*. Not all thread types currently 413 // delete themselves when they terminate. But no thread should ever be deleted 414 // asynchronously with respect to its termination - that is what _run_state can 415 // be used to check. 416 417 assert(Thread::current_or_null() == NULL, "current thread still present"); 418 } 419 420 Thread::~Thread() { 421 422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 423 // get started due to errors etc. Any active thread should at least reach post_run 424 // before it is deleted (usually in post_run()). 425 assert(_run_state == PRE_CALL_RUN || 426 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 427 "_run_state=%d", (int)_run_state); 428 429 // Notify the barrier set that a thread is being destroyed. Note that a barrier 430 // set might not be available if we encountered errors during bootstrapping. 431 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 432 if (barrier_set != NULL) { 433 barrier_set->on_thread_destroy(this); 434 } 435 436 // stack_base can be NULL if the thread is never started or exited before 437 // record_stack_base_and_size called. Although, we would like to ensure 438 // that all started threads do call record_stack_base_and_size(), there is 439 // not proper way to enforce that. 440 #if INCLUDE_NMT 441 if (_stack_base != NULL) { 442 MemTracker::release_thread_stack(stack_end(), stack_size()); 443 #ifdef ASSERT 444 set_stack_base(NULL); 445 #endif 446 } 447 #endif // INCLUDE_NMT 448 449 // deallocate data structures 450 delete resource_area(); 451 // since the handle marks are using the handle area, we have to deallocated the root 452 // handle mark before deallocating the thread's handle area, 453 assert(last_handle_mark() != NULL, "check we have an element"); 454 delete last_handle_mark(); 455 assert(last_handle_mark() == NULL, "check we have reached the end"); 456 457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 458 // We NULL out the fields for good hygiene. 459 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 460 ParkEvent::Release(_SleepEvent); _SleepEvent = 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 // Enqueue a VM_Operation to do the job for us - sometime later 530 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 531 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 532 VMThread::execute(vm_stop); 533 } 534 535 536 // Check if an external suspend request has completed (or has been 537 // cancelled). Returns true if the thread is externally suspended and 538 // false otherwise. 539 // 540 // The bits parameter returns information about the code path through 541 // the routine. Useful for debugging: 542 // 543 // set in is_ext_suspend_completed(): 544 // 0x00000001 - routine was entered 545 // 0x00000010 - routine return false at end 546 // 0x00000100 - thread exited (return false) 547 // 0x00000200 - suspend request cancelled (return false) 548 // 0x00000400 - thread suspended (return true) 549 // 0x00001000 - thread is in a suspend equivalent state (return true) 550 // 0x00002000 - thread is native and walkable (return true) 551 // 0x00004000 - thread is native_trans and walkable (needed retry) 552 // 553 // set in wait_for_ext_suspend_completion(): 554 // 0x00010000 - routine was entered 555 // 0x00020000 - suspend request cancelled before loop (return false) 556 // 0x00040000 - thread suspended before loop (return true) 557 // 0x00080000 - suspend request cancelled in loop (return false) 558 // 0x00100000 - thread suspended in loop (return true) 559 // 0x00200000 - suspend not completed during retry loop (return false) 560 561 // Helper class for tracing suspend wait debug bits. 562 // 563 // 0x00000100 indicates that the target thread exited before it could 564 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 565 // 0x00080000 each indicate a cancelled suspend request so they don't 566 // count as wait failures either. 567 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 568 569 class TraceSuspendDebugBits : public StackObj { 570 private: 571 JavaThread * jt; 572 bool is_wait; 573 bool called_by_wait; // meaningful when !is_wait 574 uint32_t * bits; 575 576 public: 577 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 578 uint32_t *_bits) { 579 jt = _jt; 580 is_wait = _is_wait; 581 called_by_wait = _called_by_wait; 582 bits = _bits; 583 } 584 585 ~TraceSuspendDebugBits() { 586 if (!is_wait) { 587 #if 1 588 // By default, don't trace bits for is_ext_suspend_completed() calls. 589 // That trace is very chatty. 590 return; 591 #else 592 if (!called_by_wait) { 593 // If tracing for is_ext_suspend_completed() is enabled, then only 594 // trace calls to it from wait_for_ext_suspend_completion() 595 return; 596 } 597 #endif 598 } 599 600 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 601 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 602 MutexLocker ml(Threads_lock); // needed for get_thread_name() 603 ResourceMark rm; 604 605 tty->print_cr( 606 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 607 jt->get_thread_name(), *bits); 608 609 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 610 } 611 } 612 } 613 }; 614 #undef DEBUG_FALSE_BITS 615 616 617 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 618 uint32_t *bits) { 619 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 620 621 bool did_trans_retry = false; // only do thread_in_native_trans retry once 622 bool do_trans_retry; // flag to force the retry 623 624 *bits |= 0x00000001; 625 626 do { 627 do_trans_retry = false; 628 629 if (is_exiting()) { 630 // Thread is in the process of exiting. This is always checked 631 // first to reduce the risk of dereferencing a freed JavaThread. 632 *bits |= 0x00000100; 633 return false; 634 } 635 636 if (!is_external_suspend()) { 637 // Suspend request is cancelled. This is always checked before 638 // is_ext_suspended() to reduce the risk of a rogue resume 639 // confusing the thread that made the suspend request. 640 *bits |= 0x00000200; 641 return false; 642 } 643 644 if (is_ext_suspended()) { 645 // thread is suspended 646 *bits |= 0x00000400; 647 return true; 648 } 649 650 // Now that we no longer do hard suspends of threads running 651 // native code, the target thread can be changing thread state 652 // while we are in this routine: 653 // 654 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 655 // 656 // We save a copy of the thread state as observed at this moment 657 // and make our decision about suspend completeness based on the 658 // copy. This closes the race where the thread state is seen as 659 // _thread_in_native_trans in the if-thread_blocked check, but is 660 // seen as _thread_blocked in if-thread_in_native_trans check. 661 JavaThreadState save_state = thread_state(); 662 663 if (save_state == _thread_blocked && is_suspend_equivalent()) { 664 // If the thread's state is _thread_blocked and this blocking 665 // condition is known to be equivalent to a suspend, then we can 666 // consider the thread to be externally suspended. This means that 667 // the code that sets _thread_blocked has been modified to do 668 // self-suspension if the blocking condition releases. We also 669 // used to check for CONDVAR_WAIT here, but that is now covered by 670 // the _thread_blocked with self-suspension check. 671 // 672 // Return true since we wouldn't be here unless there was still an 673 // external suspend request. 674 *bits |= 0x00001000; 675 return true; 676 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 677 // Threads running native code will self-suspend on native==>VM/Java 678 // transitions. If its stack is walkable (should always be the case 679 // unless this function is called before the actual java_suspend() 680 // call), then the wait is done. 681 *bits |= 0x00002000; 682 return true; 683 } else if (!called_by_wait && !did_trans_retry && 684 save_state == _thread_in_native_trans && 685 frame_anchor()->walkable()) { 686 // The thread is transitioning from thread_in_native to another 687 // thread state. check_safepoint_and_suspend_for_native_trans() 688 // will force the thread to self-suspend. If it hasn't gotten 689 // there yet we may have caught the thread in-between the native 690 // code check above and the self-suspend. Lucky us. If we were 691 // called by wait_for_ext_suspend_completion(), then it 692 // will be doing the retries so we don't have to. 693 // 694 // Since we use the saved thread state in the if-statement above, 695 // there is a chance that the thread has already transitioned to 696 // _thread_blocked by the time we get here. In that case, we will 697 // make a single unnecessary pass through the logic below. This 698 // doesn't hurt anything since we still do the trans retry. 699 700 *bits |= 0x00004000; 701 702 // Once the thread leaves thread_in_native_trans for another 703 // thread state, we break out of this retry loop. We shouldn't 704 // need this flag to prevent us from getting back here, but 705 // sometimes paranoia is good. 706 did_trans_retry = true; 707 708 // We wait for the thread to transition to a more usable state. 709 for (int i = 1; i <= SuspendRetryCount; i++) { 710 // We used to do an "os::yield_all(i)" call here with the intention 711 // that yielding would increase on each retry. However, the parameter 712 // is ignored on Linux which means the yield didn't scale up. Waiting 713 // on the SR_lock below provides a much more predictable scale up for 714 // the delay. It also provides a simple/direct point to check for any 715 // safepoint requests from the VMThread 716 717 // temporarily drops SR_lock while doing wait with safepoint check 718 // (if we're a JavaThread - the WatcherThread can also call this) 719 // and increase delay with each retry 720 if (Thread::current()->is_Java_thread()) { 721 SR_lock()->wait(i * delay); 722 } else { 723 SR_lock()->wait_without_safepoint_check(i * delay); 724 } 725 726 // check the actual thread state instead of what we saved above 727 if (thread_state() != _thread_in_native_trans) { 728 // the thread has transitioned to another thread state so 729 // try all the checks (except this one) one more time. 730 do_trans_retry = true; 731 break; 732 } 733 } // end retry loop 734 735 736 } 737 } while (do_trans_retry); 738 739 *bits |= 0x00000010; 740 return false; 741 } 742 743 // Wait for an external suspend request to complete (or be cancelled). 744 // Returns true if the thread is externally suspended and false otherwise. 745 // 746 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 747 uint32_t *bits) { 748 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 749 false /* !called_by_wait */, bits); 750 751 // local flag copies to minimize SR_lock hold time 752 bool is_suspended; 753 bool pending; 754 uint32_t reset_bits; 755 756 // set a marker so is_ext_suspend_completed() knows we are the caller 757 *bits |= 0x00010000; 758 759 // We use reset_bits to reinitialize the bits value at the top of 760 // each retry loop. This allows the caller to make use of any 761 // unused bits for their own marking purposes. 762 reset_bits = *bits; 763 764 { 765 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 766 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 767 delay, bits); 768 pending = is_external_suspend(); 769 } 770 // must release SR_lock to allow suspension to complete 771 772 if (!pending) { 773 // A cancelled suspend request is the only false return from 774 // is_ext_suspend_completed() that keeps us from entering the 775 // retry loop. 776 *bits |= 0x00020000; 777 return false; 778 } 779 780 if (is_suspended) { 781 *bits |= 0x00040000; 782 return true; 783 } 784 785 for (int i = 1; i <= retries; i++) { 786 *bits = reset_bits; // reinit to only track last retry 787 788 // We used to do an "os::yield_all(i)" call here with the intention 789 // that yielding would increase on each retry. However, the parameter 790 // is ignored on Linux which means the yield didn't scale up. Waiting 791 // on the SR_lock below provides a much more predictable scale up for 792 // the delay. It also provides a simple/direct point to check for any 793 // safepoint requests from the VMThread 794 795 { 796 Thread* t = Thread::current(); 797 MonitorLocker ml(SR_lock(), 798 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 799 // wait with safepoint check (if we're a JavaThread - the WatcherThread 800 // can also call this) and increase delay with each retry 801 ml.wait(i * delay); 802 803 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 804 delay, bits); 805 806 // It is possible for the external suspend request to be cancelled 807 // (by a resume) before the actual suspend operation is completed. 808 // Refresh our local copy to see if we still need to wait. 809 pending = is_external_suspend(); 810 } 811 812 if (!pending) { 813 // A cancelled suspend request is the only false return from 814 // is_ext_suspend_completed() that keeps us from staying in the 815 // retry loop. 816 *bits |= 0x00080000; 817 return false; 818 } 819 820 if (is_suspended) { 821 *bits |= 0x00100000; 822 return true; 823 } 824 } // end retry loop 825 826 // thread did not suspend after all our retries 827 *bits |= 0x00200000; 828 return false; 829 } 830 831 // Called from API entry points which perform stack walking. If the 832 // associated JavaThread is the current thread, then wait_for_suspend 833 // is not used. Otherwise, it determines if we should wait for the 834 // "other" thread to complete external suspension. (NOTE: in future 835 // releases the suspension mechanism should be reimplemented so this 836 // is not necessary.) 837 // 838 bool 839 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 840 if (this != JavaThread::current()) { 841 // "other" threads require special handling. 842 if (wait_for_suspend) { 843 // We are allowed to wait for the external suspend to complete 844 // so give the other thread a chance to get suspended. 845 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 846 SuspendRetryDelay, bits)) { 847 // Didn't make it so let the caller know. 848 return false; 849 } 850 } 851 // We aren't allowed to wait for the external suspend to complete 852 // so if the other thread isn't externally suspended we need to 853 // let the caller know. 854 else if (!is_ext_suspend_completed_with_lock(bits)) { 855 return false; 856 } 857 } 858 859 return true; 860 } 861 862 #ifndef PRODUCT 863 void JavaThread::record_jump(address target, address instr, const char* file, 864 int line) { 865 866 // This should not need to be atomic as the only way for simultaneous 867 // updates is via interrupts. Even then this should be rare or non-existent 868 // and we don't care that much anyway. 869 870 int index = _jmp_ring_index; 871 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 872 _jmp_ring[index]._target = (intptr_t) target; 873 _jmp_ring[index]._instruction = (intptr_t) instr; 874 _jmp_ring[index]._file = file; 875 _jmp_ring[index]._line = line; 876 } 877 #endif // PRODUCT 878 879 void Thread::interrupt(Thread* thread) { 880 debug_only(check_for_dangling_thread_pointer(thread);) 881 os::interrupt(thread); 882 } 883 884 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 885 debug_only(check_for_dangling_thread_pointer(thread);) 886 // Note: If clear_interrupted==false, this simply fetches and 887 // returns the value of the field osthread()->interrupted(). 888 return os::is_interrupted(thread, clear_interrupted); 889 } 890 891 892 // GC Support 893 bool Thread::claim_par_threads_do(uintx claim_token) { 894 uintx token = _threads_do_token; 895 if (token != claim_token) { 896 uintx res = Atomic::cmpxchg(claim_token, &_threads_do_token, token); 897 if (res == token) { 898 return true; 899 } 900 guarantee(res == claim_token, "invariant"); 901 } 902 return false; 903 } 904 905 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 906 active_handles()->oops_do(f); 907 // Do oop for ThreadShadow 908 f->do_oop((oop*)&_pending_exception); 909 handle_area()->oops_do(f); 910 911 // We scan thread local monitor lists here, and the remaining global 912 // monitors in ObjectSynchronizer::oops_do(). 913 ObjectSynchronizer::thread_local_used_oops_do(this, f); 914 } 915 916 void Thread::metadata_handles_do(void f(Metadata*)) { 917 // Only walk the Handles in Thread. 918 if (metadata_handles() != NULL) { 919 for (int i = 0; i< metadata_handles()->length(); i++) { 920 f(metadata_handles()->at(i)); 921 } 922 } 923 } 924 925 void Thread::print_on(outputStream* st, bool print_extended_info) const { 926 // get_priority assumes osthread initialized 927 if (osthread() != NULL) { 928 int os_prio; 929 if (os::get_native_priority(this, &os_prio) == OS_OK) { 930 st->print("os_prio=%d ", os_prio); 931 } 932 933 st->print("cpu=%.2fms ", 934 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 935 ); 936 st->print("elapsed=%.2fs ", 937 _statistical_info.getElapsedTime() / 1000.0 938 ); 939 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 940 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 941 st->print("allocated=" SIZE_FORMAT "%s ", 942 byte_size_in_proper_unit(allocated_bytes), 943 proper_unit_for_byte_size(allocated_bytes) 944 ); 945 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 946 } 947 948 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 949 osthread()->print_on(st); 950 } 951 ThreadsSMRSupport::print_info_on(this, st); 952 st->print(" "); 953 debug_only(if (WizardMode) print_owned_locks_on(st);) 954 } 955 956 // Thread::print_on_error() is called by fatal error handler. Don't use 957 // any lock or allocate memory. 958 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 959 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 960 961 if (is_VM_thread()) { st->print("VMThread"); } 962 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 963 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 964 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 965 else { st->print("Thread"); } 966 967 if (is_Named_thread()) { 968 st->print(" \"%s\"", name()); 969 } 970 971 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 972 p2i(stack_end()), p2i(stack_base())); 973 974 if (osthread()) { 975 st->print(" [id=%d]", osthread()->thread_id()); 976 } 977 978 ThreadsSMRSupport::print_info_on(this, st); 979 } 980 981 void Thread::print_value_on(outputStream* st) const { 982 if (is_Named_thread()) { 983 st->print(" \"%s\" ", name()); 984 } 985 st->print(INTPTR_FORMAT, p2i(this)); // print address 986 } 987 988 #ifdef ASSERT 989 void Thread::print_owned_locks_on(outputStream* st) const { 990 Monitor *cur = _owned_locks; 991 if (cur == NULL) { 992 st->print(" (no locks) "); 993 } else { 994 st->print_cr(" Locks owned:"); 995 while (cur) { 996 cur->print_on(st); 997 cur = cur->next(); 998 } 999 } 1000 } 1001 1002 static int ref_use_count = 0; 1003 1004 bool Thread::owns_locks_but_compiled_lock() const { 1005 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1006 if (cur != Compile_lock) return true; 1007 } 1008 return false; 1009 } 1010 1011 1012 #endif 1013 1014 #ifndef PRODUCT 1015 1016 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 1017 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 1018 // no locks which allow_vm_block's are held 1019 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 1020 // Check if current thread is allowed to block at a safepoint 1021 if (!(_allow_safepoint_count == 0)) { 1022 fatal("Possible safepoint reached by thread that does not allow it"); 1023 } 1024 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 1025 fatal("LEAF method calling lock?"); 1026 } 1027 1028 #ifdef ASSERT 1029 if (potential_vm_operation && is_Java_thread() 1030 && !Universe::is_bootstrapping()) { 1031 // Make sure we do not hold any locks that the VM thread also uses. 1032 // This could potentially lead to deadlocks 1033 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1034 // Threads_lock is special, since the safepoint synchronization will not start before this is 1035 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1036 // since it is used to transfer control between JavaThreads and the VMThread 1037 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1038 if ((cur->allow_vm_block() && 1039 cur != Threads_lock && 1040 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1041 cur != VMOperationRequest_lock && 1042 cur != VMOperationQueue_lock) || 1043 cur->rank() == Mutex::special) { 1044 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1045 } 1046 } 1047 } 1048 1049 if (GCALotAtAllSafepoints) { 1050 // We could enter a safepoint here and thus have a gc 1051 InterfaceSupport::check_gc_alot(); 1052 } 1053 #endif 1054 } 1055 #endif 1056 1057 bool Thread::is_in_stack(address adr) const { 1058 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1059 address end = os::current_stack_pointer(); 1060 // Allow non Java threads to call this without stack_base 1061 if (_stack_base == NULL) return true; 1062 if (stack_base() >= adr && adr >= end) return true; 1063 1064 return false; 1065 } 1066 1067 bool Thread::is_in_usable_stack(address adr) const { 1068 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1069 size_t usable_stack_size = _stack_size - stack_guard_size; 1070 1071 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1072 } 1073 1074 1075 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1076 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1077 // used for compilation in the future. If that change is made, the need for these methods 1078 // should be revisited, and they should be removed if possible. 1079 1080 bool Thread::is_lock_owned(address adr) const { 1081 return on_local_stack(adr); 1082 } 1083 1084 bool Thread::set_as_starting_thread() { 1085 assert(_starting_thread == NULL, "already initialized: " 1086 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1087 // NOTE: this must be called inside the main thread. 1088 DEBUG_ONLY(_starting_thread = this;) 1089 return os::create_main_thread((JavaThread*)this); 1090 } 1091 1092 static void initialize_class(Symbol* class_name, TRAPS) { 1093 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1094 InstanceKlass::cast(klass)->initialize(CHECK); 1095 } 1096 1097 1098 // Creates the initial ThreadGroup 1099 static Handle create_initial_thread_group(TRAPS) { 1100 Handle system_instance = JavaCalls::construct_new_instance( 1101 SystemDictionary::ThreadGroup_klass(), 1102 vmSymbols::void_method_signature(), 1103 CHECK_NH); 1104 Universe::set_system_thread_group(system_instance()); 1105 1106 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1107 Handle main_instance = JavaCalls::construct_new_instance( 1108 SystemDictionary::ThreadGroup_klass(), 1109 vmSymbols::threadgroup_string_void_signature(), 1110 system_instance, 1111 string, 1112 CHECK_NH); 1113 return main_instance; 1114 } 1115 1116 // Creates the initial Thread 1117 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1118 TRAPS) { 1119 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1120 assert(ik->is_initialized(), "must be"); 1121 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1122 1123 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1124 // constructor calls Thread.current(), which must be set here for the 1125 // initial thread. 1126 java_lang_Thread::set_thread(thread_oop(), thread); 1127 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1128 thread->set_threadObj(thread_oop()); 1129 1130 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1131 1132 JavaValue result(T_VOID); 1133 JavaCalls::call_special(&result, thread_oop, 1134 ik, 1135 vmSymbols::object_initializer_name(), 1136 vmSymbols::threadgroup_string_void_signature(), 1137 thread_group, 1138 string, 1139 CHECK_NULL); 1140 return thread_oop(); 1141 } 1142 1143 char java_runtime_name[128] = ""; 1144 char java_runtime_version[128] = ""; 1145 1146 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1147 static const char* get_java_runtime_name(TRAPS) { 1148 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1149 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1150 fieldDescriptor fd; 1151 bool found = k != NULL && 1152 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1153 vmSymbols::string_signature(), &fd); 1154 if (found) { 1155 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1156 if (name_oop == NULL) { 1157 return NULL; 1158 } 1159 const char* name = java_lang_String::as_utf8_string(name_oop, 1160 java_runtime_name, 1161 sizeof(java_runtime_name)); 1162 return name; 1163 } else { 1164 return NULL; 1165 } 1166 } 1167 1168 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1169 static const char* get_java_runtime_version(TRAPS) { 1170 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1171 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1172 fieldDescriptor fd; 1173 bool found = k != NULL && 1174 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1175 vmSymbols::string_signature(), &fd); 1176 if (found) { 1177 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1178 if (name_oop == NULL) { 1179 return NULL; 1180 } 1181 const char* name = java_lang_String::as_utf8_string(name_oop, 1182 java_runtime_version, 1183 sizeof(java_runtime_version)); 1184 return name; 1185 } else { 1186 return NULL; 1187 } 1188 } 1189 1190 // General purpose hook into Java code, run once when the VM is initialized. 1191 // The Java library method itself may be changed independently from the VM. 1192 static void call_postVMInitHook(TRAPS) { 1193 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1194 if (klass != NULL) { 1195 JavaValue result(T_VOID); 1196 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1197 vmSymbols::void_method_signature(), 1198 CHECK); 1199 } 1200 } 1201 1202 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1203 bool daemon, TRAPS) { 1204 assert(thread_group.not_null(), "thread group should be specified"); 1205 assert(threadObj() == NULL, "should only create Java thread object once"); 1206 1207 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1208 assert(ik->is_initialized(), "must be"); 1209 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1210 1211 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1212 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1213 // constructor calls Thread.current(), which must be set here. 1214 java_lang_Thread::set_thread(thread_oop(), this); 1215 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1216 set_threadObj(thread_oop()); 1217 1218 JavaValue result(T_VOID); 1219 if (thread_name != NULL) { 1220 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1221 // Thread gets assigned specified name and null target 1222 JavaCalls::call_special(&result, 1223 thread_oop, 1224 ik, 1225 vmSymbols::object_initializer_name(), 1226 vmSymbols::threadgroup_string_void_signature(), 1227 thread_group, 1228 name, 1229 THREAD); 1230 } else { 1231 // Thread gets assigned name "Thread-nnn" and null target 1232 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1233 JavaCalls::call_special(&result, 1234 thread_oop, 1235 ik, 1236 vmSymbols::object_initializer_name(), 1237 vmSymbols::threadgroup_runnable_void_signature(), 1238 thread_group, 1239 Handle(), 1240 THREAD); 1241 } 1242 1243 1244 if (daemon) { 1245 java_lang_Thread::set_daemon(thread_oop()); 1246 } 1247 1248 if (HAS_PENDING_EXCEPTION) { 1249 return; 1250 } 1251 1252 Klass* group = SystemDictionary::ThreadGroup_klass(); 1253 Handle threadObj(THREAD, this->threadObj()); 1254 1255 JavaCalls::call_special(&result, 1256 thread_group, 1257 group, 1258 vmSymbols::add_method_name(), 1259 vmSymbols::thread_void_signature(), 1260 threadObj, // Arg 1 1261 THREAD); 1262 } 1263 1264 // List of all NonJavaThreads and safe iteration over that list. 1265 1266 class NonJavaThread::List { 1267 public: 1268 NonJavaThread* volatile _head; 1269 SingleWriterSynchronizer _protect; 1270 1271 List() : _head(NULL), _protect() {} 1272 }; 1273 1274 NonJavaThread::List NonJavaThread::_the_list; 1275 1276 NonJavaThread::Iterator::Iterator() : 1277 _protect_enter(_the_list._protect.enter()), 1278 _current(OrderAccess::load_acquire(&_the_list._head)) 1279 {} 1280 1281 NonJavaThread::Iterator::~Iterator() { 1282 _the_list._protect.exit(_protect_enter); 1283 } 1284 1285 void NonJavaThread::Iterator::step() { 1286 assert(!end(), "precondition"); 1287 _current = OrderAccess::load_acquire(&_current->_next); 1288 } 1289 1290 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1291 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1292 } 1293 1294 NonJavaThread::~NonJavaThread() { } 1295 1296 void NonJavaThread::add_to_the_list() { 1297 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1298 // Initialize BarrierSet-related data before adding to list. 1299 BarrierSet::barrier_set()->on_thread_attach(this); 1300 OrderAccess::release_store(&_next, _the_list._head); 1301 OrderAccess::release_store(&_the_list._head, this); 1302 } 1303 1304 void NonJavaThread::remove_from_the_list() { 1305 { 1306 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1307 // Cleanup BarrierSet-related data before removing from list. 1308 BarrierSet::barrier_set()->on_thread_detach(this); 1309 NonJavaThread* volatile* p = &_the_list._head; 1310 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1311 if (t == this) { 1312 *p = _next; 1313 break; 1314 } 1315 } 1316 } 1317 // Wait for any in-progress iterators. Concurrent synchronize is not 1318 // allowed, so do it while holding a dedicated lock. Outside and distinct 1319 // from NJTList_lock in case an iteration attempts to lock it. 1320 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1321 _the_list._protect.synchronize(); 1322 _next = NULL; // Safe to drop the link now. 1323 } 1324 1325 void NonJavaThread::pre_run() { 1326 add_to_the_list(); 1327 1328 // This is slightly odd in that NamedThread is a subclass, but 1329 // in fact name() is defined in Thread 1330 assert(this->name() != NULL, "thread name was not set before it was started"); 1331 this->set_native_thread_name(this->name()); 1332 } 1333 1334 void NonJavaThread::post_run() { 1335 JFR_ONLY(Jfr::on_thread_exit(this);) 1336 remove_from_the_list(); 1337 // Ensure thread-local-storage is cleared before termination. 1338 Thread::clear_thread_current(); 1339 } 1340 1341 // NamedThread -- non-JavaThread subclasses with multiple 1342 // uniquely named instances should derive from this. 1343 NamedThread::NamedThread() : 1344 NonJavaThread(), 1345 _name(NULL), 1346 _processed_thread(NULL), 1347 _gc_id(GCId::undefined()) 1348 {} 1349 1350 NamedThread::~NamedThread() { 1351 if (_name != NULL) { 1352 FREE_C_HEAP_ARRAY(char, _name); 1353 _name = NULL; 1354 } 1355 } 1356 1357 void NamedThread::set_name(const char* format, ...) { 1358 guarantee(_name == NULL, "Only get to set name once."); 1359 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1360 guarantee(_name != NULL, "alloc failure"); 1361 va_list ap; 1362 va_start(ap, format); 1363 jio_vsnprintf(_name, max_name_len, format, ap); 1364 va_end(ap); 1365 } 1366 1367 void NamedThread::print_on(outputStream* st) const { 1368 st->print("\"%s\" ", name()); 1369 Thread::print_on(st); 1370 st->cr(); 1371 } 1372 1373 1374 // ======= WatcherThread ======== 1375 1376 // The watcher thread exists to simulate timer interrupts. It should 1377 // be replaced by an abstraction over whatever native support for 1378 // timer interrupts exists on the platform. 1379 1380 WatcherThread* WatcherThread::_watcher_thread = NULL; 1381 bool WatcherThread::_startable = false; 1382 volatile bool WatcherThread::_should_terminate = false; 1383 1384 WatcherThread::WatcherThread() : NonJavaThread() { 1385 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1386 if (os::create_thread(this, os::watcher_thread)) { 1387 _watcher_thread = this; 1388 1389 // Set the watcher thread to the highest OS priority which should not be 1390 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1391 // is created. The only normal thread using this priority is the reference 1392 // handler thread, which runs for very short intervals only. 1393 // If the VMThread's priority is not lower than the WatcherThread profiling 1394 // will be inaccurate. 1395 os::set_priority(this, MaxPriority); 1396 if (!DisableStartThread) { 1397 os::start_thread(this); 1398 } 1399 } 1400 } 1401 1402 int WatcherThread::sleep() const { 1403 // The WatcherThread does not participate in the safepoint protocol 1404 // for the PeriodicTask_lock because it is not a JavaThread. 1405 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1406 1407 if (_should_terminate) { 1408 // check for termination before we do any housekeeping or wait 1409 return 0; // we did not sleep. 1410 } 1411 1412 // remaining will be zero if there are no tasks, 1413 // causing the WatcherThread to sleep until a task is 1414 // enrolled 1415 int remaining = PeriodicTask::time_to_wait(); 1416 int time_slept = 0; 1417 1418 // we expect this to timeout - we only ever get unparked when 1419 // we should terminate or when a new task has been enrolled 1420 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1421 1422 jlong time_before_loop = os::javaTimeNanos(); 1423 1424 while (true) { 1425 bool timedout = ml.wait(remaining); 1426 jlong now = os::javaTimeNanos(); 1427 1428 if (remaining == 0) { 1429 // if we didn't have any tasks we could have waited for a long time 1430 // consider the time_slept zero and reset time_before_loop 1431 time_slept = 0; 1432 time_before_loop = now; 1433 } else { 1434 // need to recalculate since we might have new tasks in _tasks 1435 time_slept = (int) ((now - time_before_loop) / 1000000); 1436 } 1437 1438 // Change to task list or spurious wakeup of some kind 1439 if (timedout || _should_terminate) { 1440 break; 1441 } 1442 1443 remaining = PeriodicTask::time_to_wait(); 1444 if (remaining == 0) { 1445 // Last task was just disenrolled so loop around and wait until 1446 // another task gets enrolled 1447 continue; 1448 } 1449 1450 remaining -= time_slept; 1451 if (remaining <= 0) { 1452 break; 1453 } 1454 } 1455 1456 return time_slept; 1457 } 1458 1459 void WatcherThread::run() { 1460 assert(this == watcher_thread(), "just checking"); 1461 1462 this->set_active_handles(JNIHandleBlock::allocate_block()); 1463 while (true) { 1464 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1465 assert(watcher_thread() == this, "thread consistency check"); 1466 1467 // Calculate how long it'll be until the next PeriodicTask work 1468 // should be done, and sleep that amount of time. 1469 int time_waited = sleep(); 1470 1471 if (VMError::is_error_reported()) { 1472 // A fatal error has happened, the error handler(VMError::report_and_die) 1473 // should abort JVM after creating an error log file. However in some 1474 // rare cases, the error handler itself might deadlock. Here periodically 1475 // check for error reporting timeouts, and if it happens, just proceed to 1476 // abort the VM. 1477 1478 // This code is in WatcherThread because WatcherThread wakes up 1479 // periodically so the fatal error handler doesn't need to do anything; 1480 // also because the WatcherThread is less likely to crash than other 1481 // threads. 1482 1483 for (;;) { 1484 // Note: we use naked sleep in this loop because we want to avoid using 1485 // any kind of VM infrastructure which may be broken at this point. 1486 if (VMError::check_timeout()) { 1487 // We hit error reporting timeout. Error reporting was interrupted and 1488 // will be wrapping things up now (closing files etc). Give it some more 1489 // time, then quit the VM. 1490 os::naked_short_sleep(200); 1491 // Print a message to stderr. 1492 fdStream err(defaultStream::output_fd()); 1493 err.print_raw_cr("# [ timer expired, abort... ]"); 1494 // skip atexit/vm_exit/vm_abort hooks 1495 os::die(); 1496 } 1497 1498 // Wait a second, then recheck for timeout. 1499 os::naked_short_sleep(999); 1500 } 1501 } 1502 1503 if (_should_terminate) { 1504 // check for termination before posting the next tick 1505 break; 1506 } 1507 1508 PeriodicTask::real_time_tick(time_waited); 1509 } 1510 1511 // Signal that it is terminated 1512 { 1513 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1514 _watcher_thread = NULL; 1515 Terminator_lock->notify_all(); 1516 } 1517 } 1518 1519 void WatcherThread::start() { 1520 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1521 1522 if (watcher_thread() == NULL && _startable) { 1523 _should_terminate = false; 1524 // Create the single instance of WatcherThread 1525 new WatcherThread(); 1526 } 1527 } 1528 1529 void WatcherThread::make_startable() { 1530 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1531 _startable = true; 1532 } 1533 1534 void WatcherThread::stop() { 1535 { 1536 // Follow normal safepoint aware lock enter protocol since the 1537 // WatcherThread is stopped by another JavaThread. 1538 MutexLocker ml(PeriodicTask_lock); 1539 _should_terminate = true; 1540 1541 WatcherThread* watcher = watcher_thread(); 1542 if (watcher != NULL) { 1543 // unpark the WatcherThread so it can see that it should terminate 1544 watcher->unpark(); 1545 } 1546 } 1547 1548 MonitorLocker mu(Terminator_lock); 1549 1550 while (watcher_thread() != NULL) { 1551 // This wait should make safepoint checks, wait without a timeout, 1552 // and wait as a suspend-equivalent condition. 1553 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1554 } 1555 } 1556 1557 void WatcherThread::unpark() { 1558 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1559 PeriodicTask_lock->notify(); 1560 } 1561 1562 void WatcherThread::print_on(outputStream* st) const { 1563 st->print("\"%s\" ", name()); 1564 Thread::print_on(st); 1565 st->cr(); 1566 } 1567 1568 // ======= JavaThread ======== 1569 1570 #if INCLUDE_JVMCI 1571 1572 jlong* JavaThread::_jvmci_old_thread_counters; 1573 1574 bool jvmci_counters_include(JavaThread* thread) { 1575 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1576 } 1577 1578 void JavaThread::collect_counters(JVMCIEnv* jvmci_env, JVMCIPrimitiveArray array) { 1579 if (JVMCICounterSize > 0) { 1580 JavaThreadIteratorWithHandle jtiwh; 1581 int len = jvmci_env->get_length(array); 1582 for (int i = 0; i < len; i++) { 1583 jvmci_env->put_long_at(array, i, _jvmci_old_thread_counters[i]); 1584 } 1585 for (; JavaThread *tp = jtiwh.next(); ) { 1586 if (jvmci_counters_include(tp)) { 1587 for (int i = 0; i < len; i++) { 1588 jvmci_env->put_long_at(array, i, jvmci_env->get_long_at(array, i) + tp->_jvmci_counters[i]); 1589 } 1590 } 1591 } 1592 } 1593 } 1594 1595 #endif // INCLUDE_JVMCI 1596 1597 // A JavaThread is a normal Java thread 1598 1599 void JavaThread::initialize() { 1600 // Initialize fields 1601 1602 set_saved_exception_pc(NULL); 1603 set_threadObj(NULL); 1604 _anchor.clear(); 1605 set_entry_point(NULL); 1606 set_jni_functions(jni_functions()); 1607 set_callee_target(NULL); 1608 set_vm_result(NULL); 1609 set_vm_result_2(NULL); 1610 set_vframe_array_head(NULL); 1611 set_vframe_array_last(NULL); 1612 set_deferred_locals(NULL); 1613 set_deopt_mark(NULL); 1614 set_deopt_compiled_method(NULL); 1615 clear_must_deopt_id(); 1616 set_monitor_chunks(NULL); 1617 set_next(NULL); 1618 _on_thread_list = false; 1619 set_thread_state(_thread_new); 1620 _terminated = _not_terminated; 1621 _array_for_gc = NULL; 1622 _suspend_equivalent = false; 1623 _in_deopt_handler = 0; 1624 _doing_unsafe_access = false; 1625 _stack_guard_state = stack_guard_unused; 1626 #if INCLUDE_JVMCI 1627 _pending_monitorenter = false; 1628 _pending_deoptimization = -1; 1629 _pending_failed_speculation = 0; 1630 _pending_transfer_to_interpreter = false; 1631 _in_retryable_allocation = false; 1632 _jvmci._alternate_call_target = NULL; 1633 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1634 if (JVMCICounterSize > 0) { 1635 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1636 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1637 } else { 1638 _jvmci_counters = NULL; 1639 } 1640 #endif // INCLUDE_JVMCI 1641 _reserved_stack_activation = NULL; // stack base not known yet 1642 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1643 _exception_pc = 0; 1644 _exception_handler_pc = 0; 1645 _is_method_handle_return = 0; 1646 _jvmti_thread_state= NULL; 1647 _should_post_on_exceptions_flag = JNI_FALSE; 1648 _interp_only_mode = 0; 1649 _special_runtime_exit_condition = _no_async_condition; 1650 _pending_async_exception = NULL; 1651 _thread_stat = NULL; 1652 _thread_stat = new ThreadStatistics(); 1653 _blocked_on_compilation = false; 1654 _jni_active_critical = 0; 1655 _pending_jni_exception_check_fn = NULL; 1656 _do_not_unlock_if_synchronized = false; 1657 _cached_monitor_info = NULL; 1658 _parker = Parker::Allocate(this); 1659 1660 #ifndef PRODUCT 1661 _jmp_ring_index = 0; 1662 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1663 record_jump(NULL, NULL, NULL, 0); 1664 } 1665 #endif // PRODUCT 1666 1667 // Setup safepoint state info for this thread 1668 ThreadSafepointState::create(this); 1669 1670 debug_only(_java_call_counter = 0); 1671 1672 // JVMTI PopFrame support 1673 _popframe_condition = popframe_inactive; 1674 _popframe_preserved_args = NULL; 1675 _popframe_preserved_args_size = 0; 1676 _frames_to_pop_failed_realloc = 0; 1677 1678 if (SafepointMechanism::uses_thread_local_poll()) { 1679 SafepointMechanism::initialize_header(this); 1680 } 1681 1682 _class_to_be_initialized = NULL; 1683 1684 pd_initialize(); 1685 } 1686 1687 JavaThread::JavaThread(bool is_attaching_via_jni) : 1688 Thread() { 1689 initialize(); 1690 if (is_attaching_via_jni) { 1691 _jni_attach_state = _attaching_via_jni; 1692 } else { 1693 _jni_attach_state = _not_attaching_via_jni; 1694 } 1695 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1696 } 1697 1698 bool JavaThread::reguard_stack(address cur_sp) { 1699 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1700 && _stack_guard_state != stack_guard_reserved_disabled) { 1701 return true; // Stack already guarded or guard pages not needed. 1702 } 1703 1704 if (register_stack_overflow()) { 1705 // For those architectures which have separate register and 1706 // memory stacks, we must check the register stack to see if 1707 // it has overflowed. 1708 return false; 1709 } 1710 1711 // Java code never executes within the yellow zone: the latter is only 1712 // there to provoke an exception during stack banging. If java code 1713 // is executing there, either StackShadowPages should be larger, or 1714 // some exception code in c1, c2 or the interpreter isn't unwinding 1715 // when it should. 1716 guarantee(cur_sp > stack_reserved_zone_base(), 1717 "not enough space to reguard - increase StackShadowPages"); 1718 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1719 enable_stack_yellow_reserved_zone(); 1720 if (reserved_stack_activation() != stack_base()) { 1721 set_reserved_stack_activation(stack_base()); 1722 } 1723 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1724 set_reserved_stack_activation(stack_base()); 1725 enable_stack_reserved_zone(); 1726 } 1727 return true; 1728 } 1729 1730 bool JavaThread::reguard_stack(void) { 1731 return reguard_stack(os::current_stack_pointer()); 1732 } 1733 1734 1735 void JavaThread::block_if_vm_exited() { 1736 if (_terminated == _vm_exited) { 1737 // _vm_exited is set at safepoint, and Threads_lock is never released 1738 // we will block here forever 1739 Threads_lock->lock_without_safepoint_check(); 1740 ShouldNotReachHere(); 1741 } 1742 } 1743 1744 1745 // Remove this ifdef when C1 is ported to the compiler interface. 1746 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1747 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1748 1749 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1750 Thread() { 1751 initialize(); 1752 _jni_attach_state = _not_attaching_via_jni; 1753 set_entry_point(entry_point); 1754 // Create the native thread itself. 1755 // %note runtime_23 1756 os::ThreadType thr_type = os::java_thread; 1757 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1758 os::java_thread; 1759 os::create_thread(this, thr_type, stack_sz); 1760 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1761 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1762 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1763 // the exception consists of creating the exception object & initializing it, initialization 1764 // will leave the VM via a JavaCall and then all locks must be unlocked). 1765 // 1766 // The thread is still suspended when we reach here. Thread must be explicit started 1767 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1768 // by calling Threads:add. The reason why this is not done here, is because the thread 1769 // object must be fully initialized (take a look at JVM_Start) 1770 } 1771 1772 JavaThread::~JavaThread() { 1773 1774 // JSR166 -- return the parker to the free list 1775 Parker::Release(_parker); 1776 _parker = NULL; 1777 1778 // Free any remaining previous UnrollBlock 1779 vframeArray* old_array = vframe_array_last(); 1780 1781 if (old_array != NULL) { 1782 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1783 old_array->set_unroll_block(NULL); 1784 delete old_info; 1785 delete old_array; 1786 } 1787 1788 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1789 if (deferred != NULL) { 1790 // This can only happen if thread is destroyed before deoptimization occurs. 1791 assert(deferred->length() != 0, "empty array!"); 1792 do { 1793 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1794 deferred->remove_at(0); 1795 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1796 delete dlv; 1797 } while (deferred->length() != 0); 1798 delete deferred; 1799 } 1800 1801 // All Java related clean up happens in exit 1802 ThreadSafepointState::destroy(this); 1803 if (_thread_stat != NULL) delete _thread_stat; 1804 1805 #if INCLUDE_JVMCI 1806 if (JVMCICounterSize > 0) { 1807 if (jvmci_counters_include(this)) { 1808 for (int i = 0; i < JVMCICounterSize; i++) { 1809 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1810 } 1811 } 1812 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1813 } 1814 #endif // INCLUDE_JVMCI 1815 } 1816 1817 1818 // First JavaThread specific code executed by a new Java thread. 1819 void JavaThread::pre_run() { 1820 // empty - see comments in run() 1821 } 1822 1823 // The main routine called by a new Java thread. This isn't overridden 1824 // by subclasses, instead different subclasses define a different "entry_point" 1825 // which defines the actual logic for that kind of thread. 1826 void JavaThread::run() { 1827 // initialize thread-local alloc buffer related fields 1828 this->initialize_tlab(); 1829 1830 // Used to test validity of stack trace backs. 1831 // This can't be moved into pre_run() else we invalidate 1832 // the requirement that thread_main_inner is lower on 1833 // the stack. Consequently all the initialization logic 1834 // stays here in run() rather than pre_run(). 1835 this->record_base_of_stack_pointer(); 1836 1837 this->create_stack_guard_pages(); 1838 1839 this->cache_global_variables(); 1840 1841 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1842 // in the VM. Change thread state from _thread_new to _thread_in_vm 1843 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1844 // Before a thread is on the threads list it is always safe, so after leaving the 1845 // _thread_new we should emit a instruction barrier. The distance to modified code 1846 // from here is probably far enough, but this is consistent and safe. 1847 OrderAccess::cross_modify_fence(); 1848 1849 assert(JavaThread::current() == this, "sanity check"); 1850 assert(!Thread::current()->owns_locks(), "sanity check"); 1851 1852 DTRACE_THREAD_PROBE(start, this); 1853 1854 // This operation might block. We call that after all safepoint checks for a new thread has 1855 // been completed. 1856 this->set_active_handles(JNIHandleBlock::allocate_block()); 1857 1858 if (JvmtiExport::should_post_thread_life()) { 1859 JvmtiExport::post_thread_start(this); 1860 1861 } 1862 1863 // We call another function to do the rest so we are sure that the stack addresses used 1864 // from there will be lower than the stack base just computed. 1865 thread_main_inner(); 1866 } 1867 1868 void JavaThread::thread_main_inner() { 1869 assert(JavaThread::current() == this, "sanity check"); 1870 assert(this->threadObj() != NULL, "just checking"); 1871 1872 // Execute thread entry point unless this thread has a pending exception 1873 // or has been stopped before starting. 1874 // Note: Due to JVM_StopThread we can have pending exceptions already! 1875 if (!this->has_pending_exception() && 1876 !java_lang_Thread::is_stillborn(this->threadObj())) { 1877 { 1878 ResourceMark rm(this); 1879 this->set_native_thread_name(this->get_thread_name()); 1880 } 1881 HandleMark hm(this); 1882 this->entry_point()(this, this); 1883 } 1884 1885 DTRACE_THREAD_PROBE(stop, this); 1886 1887 // Cleanup is handled in post_run() 1888 } 1889 1890 // Shared teardown for all JavaThreads 1891 void JavaThread::post_run() { 1892 this->exit(false); 1893 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1894 // for any shared tear-down. 1895 this->smr_delete(); 1896 } 1897 1898 static void ensure_join(JavaThread* thread) { 1899 // We do not need to grab the Threads_lock, since we are operating on ourself. 1900 Handle threadObj(thread, thread->threadObj()); 1901 assert(threadObj.not_null(), "java thread object must exist"); 1902 ObjectLocker lock(threadObj, thread); 1903 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1904 thread->clear_pending_exception(); 1905 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1906 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1907 // Clear the native thread instance - this makes isAlive return false and allows the join() 1908 // to complete once we've done the notify_all below 1909 java_lang_Thread::set_thread(threadObj(), NULL); 1910 lock.notify_all(thread); 1911 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1912 thread->clear_pending_exception(); 1913 } 1914 1915 static bool is_daemon(oop threadObj) { 1916 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1917 } 1918 1919 // For any new cleanup additions, please check to see if they need to be applied to 1920 // cleanup_failed_attach_current_thread as well. 1921 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1922 assert(this == JavaThread::current(), "thread consistency check"); 1923 1924 elapsedTimer _timer_exit_phase1; 1925 elapsedTimer _timer_exit_phase2; 1926 elapsedTimer _timer_exit_phase3; 1927 elapsedTimer _timer_exit_phase4; 1928 1929 if (log_is_enabled(Debug, os, thread, timer)) { 1930 _timer_exit_phase1.start(); 1931 } 1932 1933 HandleMark hm(this); 1934 Handle uncaught_exception(this, this->pending_exception()); 1935 this->clear_pending_exception(); 1936 Handle threadObj(this, this->threadObj()); 1937 assert(threadObj.not_null(), "Java thread object should be created"); 1938 1939 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1940 { 1941 EXCEPTION_MARK; 1942 1943 CLEAR_PENDING_EXCEPTION; 1944 } 1945 if (!destroy_vm) { 1946 if (uncaught_exception.not_null()) { 1947 EXCEPTION_MARK; 1948 // Call method Thread.dispatchUncaughtException(). 1949 Klass* thread_klass = SystemDictionary::Thread_klass(); 1950 JavaValue result(T_VOID); 1951 JavaCalls::call_virtual(&result, 1952 threadObj, thread_klass, 1953 vmSymbols::dispatchUncaughtException_name(), 1954 vmSymbols::throwable_void_signature(), 1955 uncaught_exception, 1956 THREAD); 1957 if (HAS_PENDING_EXCEPTION) { 1958 ResourceMark rm(this); 1959 jio_fprintf(defaultStream::error_stream(), 1960 "\nException: %s thrown from the UncaughtExceptionHandler" 1961 " in thread \"%s\"\n", 1962 pending_exception()->klass()->external_name(), 1963 get_thread_name()); 1964 CLEAR_PENDING_EXCEPTION; 1965 } 1966 } 1967 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 1968 1969 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1970 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1971 // is deprecated anyhow. 1972 if (!is_Compiler_thread()) { 1973 int count = 3; 1974 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1975 EXCEPTION_MARK; 1976 JavaValue result(T_VOID); 1977 Klass* thread_klass = SystemDictionary::Thread_klass(); 1978 JavaCalls::call_virtual(&result, 1979 threadObj, thread_klass, 1980 vmSymbols::exit_method_name(), 1981 vmSymbols::void_method_signature(), 1982 THREAD); 1983 CLEAR_PENDING_EXCEPTION; 1984 } 1985 } 1986 // notify JVMTI 1987 if (JvmtiExport::should_post_thread_life()) { 1988 JvmtiExport::post_thread_end(this); 1989 } 1990 1991 // We have notified the agents that we are exiting, before we go on, 1992 // we must check for a pending external suspend request and honor it 1993 // in order to not surprise the thread that made the suspend request. 1994 while (true) { 1995 { 1996 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1997 if (!is_external_suspend()) { 1998 set_terminated(_thread_exiting); 1999 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2000 break; 2001 } 2002 // Implied else: 2003 // Things get a little tricky here. We have a pending external 2004 // suspend request, but we are holding the SR_lock so we 2005 // can't just self-suspend. So we temporarily drop the lock 2006 // and then self-suspend. 2007 } 2008 2009 ThreadBlockInVM tbivm(this); 2010 java_suspend_self(); 2011 2012 // We're done with this suspend request, but we have to loop around 2013 // and check again. Eventually we will get SR_lock without a pending 2014 // external suspend request and will be able to mark ourselves as 2015 // exiting. 2016 } 2017 // no more external suspends are allowed at this point 2018 } else { 2019 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2020 // before_exit() has already posted JVMTI THREAD_END events 2021 } 2022 2023 if (log_is_enabled(Debug, os, thread, timer)) { 2024 _timer_exit_phase1.stop(); 2025 _timer_exit_phase2.start(); 2026 } 2027 2028 // Capture daemon status before the thread is marked as terminated. 2029 bool daemon = is_daemon(threadObj()); 2030 2031 // Notify waiters on thread object. This has to be done after exit() is called 2032 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2033 // group should have the destroyed bit set before waiters are notified). 2034 ensure_join(this); 2035 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2036 2037 if (log_is_enabled(Debug, os, thread, timer)) { 2038 _timer_exit_phase2.stop(); 2039 _timer_exit_phase3.start(); 2040 } 2041 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2042 // held by this thread must be released. The spec does not distinguish 2043 // between JNI-acquired and regular Java monitors. We can only see 2044 // regular Java monitors here if monitor enter-exit matching is broken. 2045 // 2046 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2047 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2048 if (exit_type == jni_detach) { 2049 // Sanity check even though JNI DetachCurrentThread() would have 2050 // returned JNI_ERR if there was a Java frame. JavaThread exit 2051 // should be done executing Java code by the time we get here. 2052 assert(!this->has_last_Java_frame(), 2053 "should not have a Java frame when detaching or exiting"); 2054 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2055 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2056 } 2057 2058 // These things needs to be done while we are still a Java Thread. Make sure that thread 2059 // is in a consistent state, in case GC happens 2060 JFR_ONLY(Jfr::on_thread_exit(this);) 2061 2062 if (active_handles() != NULL) { 2063 JNIHandleBlock* block = active_handles(); 2064 set_active_handles(NULL); 2065 JNIHandleBlock::release_block(block); 2066 } 2067 2068 if (free_handle_block() != NULL) { 2069 JNIHandleBlock* block = free_handle_block(); 2070 set_free_handle_block(NULL); 2071 JNIHandleBlock::release_block(block); 2072 } 2073 2074 // These have to be removed while this is still a valid thread. 2075 remove_stack_guard_pages(); 2076 2077 if (UseTLAB) { 2078 tlab().retire(); 2079 } 2080 2081 if (JvmtiEnv::environments_might_exist()) { 2082 JvmtiExport::cleanup_thread(this); 2083 } 2084 2085 // We must flush any deferred card marks and other various GC barrier 2086 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2087 // before removing a thread from the list of active threads. 2088 BarrierSet::barrier_set()->on_thread_detach(this); 2089 2090 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2091 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2092 os::current_thread_id()); 2093 2094 if (log_is_enabled(Debug, os, thread, timer)) { 2095 _timer_exit_phase3.stop(); 2096 _timer_exit_phase4.start(); 2097 } 2098 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2099 Threads::remove(this, daemon); 2100 2101 if (log_is_enabled(Debug, os, thread, timer)) { 2102 _timer_exit_phase4.stop(); 2103 ResourceMark rm(this); 2104 log_debug(os, thread, timer)("name='%s'" 2105 ", exit-phase1=" JLONG_FORMAT 2106 ", exit-phase2=" JLONG_FORMAT 2107 ", exit-phase3=" JLONG_FORMAT 2108 ", exit-phase4=" JLONG_FORMAT, 2109 get_thread_name(), 2110 _timer_exit_phase1.milliseconds(), 2111 _timer_exit_phase2.milliseconds(), 2112 _timer_exit_phase3.milliseconds(), 2113 _timer_exit_phase4.milliseconds()); 2114 } 2115 } 2116 2117 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2118 if (active_handles() != NULL) { 2119 JNIHandleBlock* block = active_handles(); 2120 set_active_handles(NULL); 2121 JNIHandleBlock::release_block(block); 2122 } 2123 2124 if (free_handle_block() != NULL) { 2125 JNIHandleBlock* block = free_handle_block(); 2126 set_free_handle_block(NULL); 2127 JNIHandleBlock::release_block(block); 2128 } 2129 2130 // These have to be removed while this is still a valid thread. 2131 remove_stack_guard_pages(); 2132 2133 if (UseTLAB) { 2134 tlab().retire(); 2135 } 2136 2137 BarrierSet::barrier_set()->on_thread_detach(this); 2138 2139 Threads::remove(this, is_daemon); 2140 this->smr_delete(); 2141 } 2142 2143 JavaThread* JavaThread::active() { 2144 Thread* thread = Thread::current(); 2145 if (thread->is_Java_thread()) { 2146 return (JavaThread*) thread; 2147 } else { 2148 assert(thread->is_VM_thread(), "this must be a vm thread"); 2149 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2150 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2151 assert(ret->is_Java_thread(), "must be a Java thread"); 2152 return ret; 2153 } 2154 } 2155 2156 bool JavaThread::is_lock_owned(address adr) const { 2157 if (Thread::is_lock_owned(adr)) return true; 2158 2159 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2160 if (chunk->contains(adr)) return true; 2161 } 2162 2163 return false; 2164 } 2165 2166 2167 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2168 chunk->set_next(monitor_chunks()); 2169 set_monitor_chunks(chunk); 2170 } 2171 2172 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2173 guarantee(monitor_chunks() != NULL, "must be non empty"); 2174 if (monitor_chunks() == chunk) { 2175 set_monitor_chunks(chunk->next()); 2176 } else { 2177 MonitorChunk* prev = monitor_chunks(); 2178 while (prev->next() != chunk) prev = prev->next(); 2179 prev->set_next(chunk->next()); 2180 } 2181 } 2182 2183 // JVM support. 2184 2185 // Note: this function shouldn't block if it's called in 2186 // _thread_in_native_trans state (such as from 2187 // check_special_condition_for_native_trans()). 2188 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2189 2190 if (has_last_Java_frame() && has_async_condition()) { 2191 // If we are at a polling page safepoint (not a poll return) 2192 // then we must defer async exception because live registers 2193 // will be clobbered by the exception path. Poll return is 2194 // ok because the call we a returning from already collides 2195 // with exception handling registers and so there is no issue. 2196 // (The exception handling path kills call result registers but 2197 // this is ok since the exception kills the result anyway). 2198 2199 if (is_at_poll_safepoint()) { 2200 // if the code we are returning to has deoptimized we must defer 2201 // the exception otherwise live registers get clobbered on the 2202 // exception path before deoptimization is able to retrieve them. 2203 // 2204 RegisterMap map(this, false); 2205 frame caller_fr = last_frame().sender(&map); 2206 assert(caller_fr.is_compiled_frame(), "what?"); 2207 if (caller_fr.is_deoptimized_frame()) { 2208 log_info(exceptions)("deferred async exception at compiled safepoint"); 2209 return; 2210 } 2211 } 2212 } 2213 2214 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2215 if (condition == _no_async_condition) { 2216 // Conditions have changed since has_special_runtime_exit_condition() 2217 // was called: 2218 // - if we were here only because of an external suspend request, 2219 // then that was taken care of above (or cancelled) so we are done 2220 // - if we were here because of another async request, then it has 2221 // been cleared between the has_special_runtime_exit_condition() 2222 // and now so again we are done 2223 return; 2224 } 2225 2226 // Check for pending async. exception 2227 if (_pending_async_exception != NULL) { 2228 // Only overwrite an already pending exception, if it is not a threadDeath. 2229 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2230 2231 // We cannot call Exceptions::_throw(...) here because we cannot block 2232 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2233 2234 LogTarget(Info, exceptions) lt; 2235 if (lt.is_enabled()) { 2236 ResourceMark rm; 2237 LogStream ls(lt); 2238 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2239 if (has_last_Java_frame()) { 2240 frame f = last_frame(); 2241 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2242 } 2243 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2244 } 2245 _pending_async_exception = NULL; 2246 clear_has_async_exception(); 2247 } 2248 } 2249 2250 if (check_unsafe_error && 2251 condition == _async_unsafe_access_error && !has_pending_exception()) { 2252 condition = _no_async_condition; // done 2253 switch (thread_state()) { 2254 case _thread_in_vm: { 2255 JavaThread* THREAD = this; 2256 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2257 } 2258 case _thread_in_native: { 2259 ThreadInVMfromNative tiv(this); 2260 JavaThread* THREAD = this; 2261 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2262 } 2263 case _thread_in_Java: { 2264 ThreadInVMfromJava tiv(this); 2265 JavaThread* THREAD = this; 2266 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2267 } 2268 default: 2269 ShouldNotReachHere(); 2270 } 2271 } 2272 2273 assert(condition == _no_async_condition || has_pending_exception() || 2274 (!check_unsafe_error && condition == _async_unsafe_access_error), 2275 "must have handled the async condition, if no exception"); 2276 } 2277 2278 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2279 // 2280 // Check for pending external suspend. 2281 // If JNIEnv proxies are allowed, don't self-suspend if the target 2282 // thread is not the current thread. In older versions of jdbx, jdbx 2283 // threads could call into the VM with another thread's JNIEnv so we 2284 // can be here operating on behalf of a suspended thread (4432884). 2285 bool do_self_suspend = is_external_suspend_with_lock(); 2286 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2287 frame_anchor()->make_walkable(this); 2288 java_suspend_self_with_safepoint_check(); 2289 } 2290 2291 // We might be here for reasons in addition to the self-suspend request 2292 // so check for other async requests. 2293 if (check_asyncs) { 2294 check_and_handle_async_exceptions(); 2295 } 2296 2297 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2298 } 2299 2300 void JavaThread::send_thread_stop(oop java_throwable) { 2301 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2302 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2303 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2304 2305 // Do not throw asynchronous exceptions against the compiler thread 2306 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2307 if (!can_call_java()) return; 2308 2309 { 2310 // Actually throw the Throwable against the target Thread - however 2311 // only if there is no thread death exception installed already. 2312 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2313 // If the topmost frame is a runtime stub, then we are calling into 2314 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2315 // must deoptimize the caller before continuing, as the compiled exception handler table 2316 // may not be valid 2317 if (has_last_Java_frame()) { 2318 frame f = last_frame(); 2319 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2320 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2321 RegisterMap reg_map(this, UseBiasedLocking); 2322 frame compiled_frame = f.sender(®_map); 2323 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2324 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2325 } 2326 } 2327 } 2328 2329 // Set async. pending exception in thread. 2330 set_pending_async_exception(java_throwable); 2331 2332 if (log_is_enabled(Info, exceptions)) { 2333 ResourceMark rm; 2334 log_info(exceptions)("Pending Async. exception installed of type: %s", 2335 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2336 } 2337 // for AbortVMOnException flag 2338 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2339 } 2340 } 2341 2342 2343 // Interrupt thread so it will wake up from a potential wait() 2344 Thread::interrupt(this); 2345 } 2346 2347 // External suspension mechanism. 2348 // 2349 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2350 // to any VM_locks and it is at a transition 2351 // Self-suspension will happen on the transition out of the vm. 2352 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2353 // 2354 // Guarantees on return: 2355 // + Target thread will not execute any new bytecode (that's why we need to 2356 // force a safepoint) 2357 // + Target thread will not enter any new monitors 2358 // 2359 void JavaThread::java_suspend() { 2360 ThreadsListHandle tlh; 2361 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2362 return; 2363 } 2364 2365 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2366 if (!is_external_suspend()) { 2367 // a racing resume has cancelled us; bail out now 2368 return; 2369 } 2370 2371 // suspend is done 2372 uint32_t debug_bits = 0; 2373 // Warning: is_ext_suspend_completed() may temporarily drop the 2374 // SR_lock to allow the thread to reach a stable thread state if 2375 // it is currently in a transient thread state. 2376 if (is_ext_suspend_completed(false /* !called_by_wait */, 2377 SuspendRetryDelay, &debug_bits)) { 2378 return; 2379 } 2380 } 2381 2382 if (Thread::current() == this) { 2383 // Safely self-suspend. 2384 // If we don't do this explicitly it will implicitly happen 2385 // before we transition back to Java, and on some other thread-state 2386 // transition paths, but not as we exit a JVM TI SuspendThread call. 2387 // As SuspendThread(current) must not return (until resumed) we must 2388 // self-suspend here. 2389 ThreadBlockInVM tbivm(this); 2390 java_suspend_self(); 2391 } else { 2392 VM_ThreadSuspend vm_suspend; 2393 VMThread::execute(&vm_suspend); 2394 } 2395 } 2396 2397 // Part II of external suspension. 2398 // A JavaThread self suspends when it detects a pending external suspend 2399 // request. This is usually on transitions. It is also done in places 2400 // where continuing to the next transition would surprise the caller, 2401 // e.g., monitor entry. 2402 // 2403 // Returns the number of times that the thread self-suspended. 2404 // 2405 // Note: DO NOT call java_suspend_self() when you just want to block current 2406 // thread. java_suspend_self() is the second stage of cooperative 2407 // suspension for external suspend requests and should only be used 2408 // to complete an external suspend request. 2409 // 2410 int JavaThread::java_suspend_self() { 2411 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2412 int ret = 0; 2413 2414 // we are in the process of exiting so don't suspend 2415 if (is_exiting()) { 2416 clear_external_suspend(); 2417 return ret; 2418 } 2419 2420 assert(_anchor.walkable() || 2421 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2422 "must have walkable stack"); 2423 2424 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2425 2426 assert(!this->is_ext_suspended(), 2427 "a thread trying to self-suspend should not already be suspended"); 2428 2429 if (this->is_suspend_equivalent()) { 2430 // If we are self-suspending as a result of the lifting of a 2431 // suspend equivalent condition, then the suspend_equivalent 2432 // flag is not cleared until we set the ext_suspended flag so 2433 // that wait_for_ext_suspend_completion() returns consistent 2434 // results. 2435 this->clear_suspend_equivalent(); 2436 } 2437 2438 // A racing resume may have cancelled us before we grabbed SR_lock 2439 // above. Or another external suspend request could be waiting for us 2440 // by the time we return from SR_lock()->wait(). The thread 2441 // that requested the suspension may already be trying to walk our 2442 // stack and if we return now, we can change the stack out from under 2443 // it. This would be a "bad thing (TM)" and cause the stack walker 2444 // to crash. We stay self-suspended until there are no more pending 2445 // external suspend requests. 2446 while (is_external_suspend()) { 2447 ret++; 2448 this->set_ext_suspended(); 2449 2450 // _ext_suspended flag is cleared by java_resume() 2451 while (is_ext_suspended()) { 2452 ml.wait(); 2453 } 2454 } 2455 return ret; 2456 } 2457 2458 // Helper routine to set up the correct thread state before calling java_suspend_self. 2459 // This is called when regular thread-state transition helpers can't be used because 2460 // we can be in various states, in particular _thread_in_native_trans. 2461 // Because this thread is external suspended the safepoint code will count it as at 2462 // a safepoint, regardless of what its actual current thread-state is. But 2463 // is_ext_suspend_completed() may be waiting to see a thread transition from 2464 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2465 // to _thread_blocked. The problem with setting thread state directly is that a 2466 // safepoint could happen just after java_suspend_self() returns after being resumed, 2467 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2468 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2469 // However, not all initial-states are allowed when performing a safepoint check, as we 2470 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2471 // only _thread_in_native is possible when executing this code (based on our two callers). 2472 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2473 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2474 // and so we don't need the explicit safepoint check. 2475 2476 void JavaThread::java_suspend_self_with_safepoint_check() { 2477 assert(this == Thread::current(), "invariant"); 2478 JavaThreadState state = thread_state(); 2479 set_thread_state(_thread_blocked); 2480 java_suspend_self(); 2481 set_thread_state_fence(state); 2482 // Since we are not using a regular thread-state transition helper here, 2483 // we must manually emit the instruction barrier after leaving a safe state. 2484 OrderAccess::cross_modify_fence(); 2485 if (state != _thread_in_native) { 2486 SafepointMechanism::block_if_requested(this); 2487 } 2488 } 2489 2490 #ifdef ASSERT 2491 // Verify the JavaThread has not yet been published in the Threads::list, and 2492 // hence doesn't need protection from concurrent access at this stage. 2493 void JavaThread::verify_not_published() { 2494 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2495 // since an unpublished JavaThread doesn't participate in the 2496 // Thread-SMR protocol for keeping a ThreadsList alive. 2497 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2498 } 2499 #endif 2500 2501 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2502 // progress or when _suspend_flags is non-zero. 2503 // Current thread needs to self-suspend if there is a suspend request and/or 2504 // block if a safepoint is in progress. 2505 // Async exception ISN'T checked. 2506 // Note only the ThreadInVMfromNative transition can call this function 2507 // directly and when thread state is _thread_in_native_trans 2508 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2509 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2510 2511 JavaThread *curJT = JavaThread::current(); 2512 bool do_self_suspend = thread->is_external_suspend(); 2513 2514 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2515 2516 // If JNIEnv proxies are allowed, don't self-suspend if the target 2517 // thread is not the current thread. In older versions of jdbx, jdbx 2518 // threads could call into the VM with another thread's JNIEnv so we 2519 // can be here operating on behalf of a suspended thread (4432884). 2520 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2521 thread->java_suspend_self_with_safepoint_check(); 2522 } else { 2523 SafepointMechanism::block_if_requested(curJT); 2524 } 2525 2526 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2527 } 2528 2529 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2530 // progress or when _suspend_flags is non-zero. 2531 // Current thread needs to self-suspend if there is a suspend request and/or 2532 // block if a safepoint is in progress. 2533 // Also check for pending async exception (not including unsafe access error). 2534 // Note only the native==>VM/Java barriers can call this function and when 2535 // thread state is _thread_in_native_trans. 2536 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2537 check_safepoint_and_suspend_for_native_trans(thread); 2538 2539 if (thread->has_async_exception()) { 2540 // We are in _thread_in_native_trans state, don't handle unsafe 2541 // access error since that may block. 2542 thread->check_and_handle_async_exceptions(false); 2543 } 2544 } 2545 2546 // This is a variant of the normal 2547 // check_special_condition_for_native_trans with slightly different 2548 // semantics for use by critical native wrappers. It does all the 2549 // normal checks but also performs the transition back into 2550 // thread_in_Java state. This is required so that critical natives 2551 // can potentially block and perform a GC if they are the last thread 2552 // exiting the GCLocker. 2553 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2554 check_special_condition_for_native_trans(thread); 2555 2556 // Finish the transition 2557 thread->set_thread_state(_thread_in_Java); 2558 2559 if (thread->do_critical_native_unlock()) { 2560 ThreadInVMfromJavaNoAsyncException tiv(thread); 2561 GCLocker::unlock_critical(thread); 2562 thread->clear_critical_native_unlock(); 2563 } 2564 } 2565 2566 // We need to guarantee the Threads_lock here, since resumes are not 2567 // allowed during safepoint synchronization 2568 // Can only resume from an external suspension 2569 void JavaThread::java_resume() { 2570 assert_locked_or_safepoint(Threads_lock); 2571 2572 // Sanity check: thread is gone, has started exiting or the thread 2573 // was not externally suspended. 2574 ThreadsListHandle tlh; 2575 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2576 return; 2577 } 2578 2579 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2580 2581 clear_external_suspend(); 2582 2583 if (is_ext_suspended()) { 2584 clear_ext_suspended(); 2585 SR_lock()->notify_all(); 2586 } 2587 } 2588 2589 size_t JavaThread::_stack_red_zone_size = 0; 2590 size_t JavaThread::_stack_yellow_zone_size = 0; 2591 size_t JavaThread::_stack_reserved_zone_size = 0; 2592 size_t JavaThread::_stack_shadow_zone_size = 0; 2593 2594 void JavaThread::create_stack_guard_pages() { 2595 if (!os::uses_stack_guard_pages() || 2596 _stack_guard_state != stack_guard_unused || 2597 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2598 log_info(os, thread)("Stack guard page creation for thread " 2599 UINTX_FORMAT " disabled", os::current_thread_id()); 2600 return; 2601 } 2602 address low_addr = stack_end(); 2603 size_t len = stack_guard_zone_size(); 2604 2605 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2606 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2607 2608 int must_commit = os::must_commit_stack_guard_pages(); 2609 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2610 2611 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2612 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2613 return; 2614 } 2615 2616 if (os::guard_memory((char *) low_addr, len)) { 2617 _stack_guard_state = stack_guard_enabled; 2618 } else { 2619 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2620 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2621 if (os::uncommit_memory((char *) low_addr, len)) { 2622 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2623 } 2624 return; 2625 } 2626 2627 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2628 PTR_FORMAT "-" PTR_FORMAT ".", 2629 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2630 } 2631 2632 void JavaThread::remove_stack_guard_pages() { 2633 assert(Thread::current() == this, "from different thread"); 2634 if (_stack_guard_state == stack_guard_unused) return; 2635 address low_addr = stack_end(); 2636 size_t len = stack_guard_zone_size(); 2637 2638 if (os::must_commit_stack_guard_pages()) { 2639 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2640 _stack_guard_state = stack_guard_unused; 2641 } else { 2642 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2643 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2644 return; 2645 } 2646 } else { 2647 if (_stack_guard_state == stack_guard_unused) return; 2648 if (os::unguard_memory((char *) low_addr, len)) { 2649 _stack_guard_state = stack_guard_unused; 2650 } else { 2651 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2652 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2653 return; 2654 } 2655 } 2656 2657 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2658 PTR_FORMAT "-" PTR_FORMAT ".", 2659 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2660 } 2661 2662 void JavaThread::enable_stack_reserved_zone() { 2663 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2664 2665 // The base notation is from the stack's point of view, growing downward. 2666 // We need to adjust it to work correctly with guard_memory() 2667 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2668 2669 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2670 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2671 2672 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2673 _stack_guard_state = stack_guard_enabled; 2674 } else { 2675 warning("Attempt to guard stack reserved zone failed."); 2676 } 2677 enable_register_stack_guard(); 2678 } 2679 2680 void JavaThread::disable_stack_reserved_zone() { 2681 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2682 2683 // Simply return if called for a thread that does not use guard pages. 2684 if (_stack_guard_state != stack_guard_enabled) return; 2685 2686 // The base notation is from the stack's point of view, growing downward. 2687 // We need to adjust it to work correctly with guard_memory() 2688 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2689 2690 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2691 _stack_guard_state = stack_guard_reserved_disabled; 2692 } else { 2693 warning("Attempt to unguard stack reserved zone failed."); 2694 } 2695 disable_register_stack_guard(); 2696 } 2697 2698 void JavaThread::enable_stack_yellow_reserved_zone() { 2699 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2700 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2701 2702 // The base notation is from the stacks point of view, growing downward. 2703 // We need to adjust it to work correctly with guard_memory() 2704 address base = stack_red_zone_base(); 2705 2706 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2707 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2708 2709 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2710 _stack_guard_state = stack_guard_enabled; 2711 } else { 2712 warning("Attempt to guard stack yellow zone failed."); 2713 } 2714 enable_register_stack_guard(); 2715 } 2716 2717 void JavaThread::disable_stack_yellow_reserved_zone() { 2718 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2719 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2720 2721 // Simply return if called for a thread that does not use guard pages. 2722 if (_stack_guard_state == stack_guard_unused) return; 2723 2724 // The base notation is from the stacks point of view, growing downward. 2725 // We need to adjust it to work correctly with guard_memory() 2726 address base = stack_red_zone_base(); 2727 2728 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2729 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2730 } else { 2731 warning("Attempt to unguard stack yellow zone failed."); 2732 } 2733 disable_register_stack_guard(); 2734 } 2735 2736 void JavaThread::enable_stack_red_zone() { 2737 // The base notation is from the stacks point of view, growing downward. 2738 // We need to adjust it to work correctly with guard_memory() 2739 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2740 address base = stack_red_zone_base() - stack_red_zone_size(); 2741 2742 guarantee(base < stack_base(), "Error calculating stack red zone"); 2743 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2744 2745 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2746 warning("Attempt to guard stack red zone failed."); 2747 } 2748 } 2749 2750 void JavaThread::disable_stack_red_zone() { 2751 // The base notation is from the stacks point of view, growing downward. 2752 // We need to adjust it to work correctly with guard_memory() 2753 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2754 address base = stack_red_zone_base() - stack_red_zone_size(); 2755 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2756 warning("Attempt to unguard stack red zone failed."); 2757 } 2758 } 2759 2760 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2761 // ignore is there is no stack 2762 if (!has_last_Java_frame()) return; 2763 // traverse the stack frames. Starts from top frame. 2764 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2765 frame* fr = fst.current(); 2766 f(fr, fst.register_map()); 2767 } 2768 } 2769 2770 2771 #ifndef PRODUCT 2772 // Deoptimization 2773 // Function for testing deoptimization 2774 void JavaThread::deoptimize() { 2775 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2776 StackFrameStream fst(this, UseBiasedLocking); 2777 bool deopt = false; // Dump stack only if a deopt actually happens. 2778 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2779 // Iterate over all frames in the thread and deoptimize 2780 for (; !fst.is_done(); fst.next()) { 2781 if (fst.current()->can_be_deoptimized()) { 2782 2783 if (only_at) { 2784 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2785 // consists of comma or carriage return separated numbers so 2786 // search for the current bci in that string. 2787 address pc = fst.current()->pc(); 2788 nmethod* nm = (nmethod*) fst.current()->cb(); 2789 ScopeDesc* sd = nm->scope_desc_at(pc); 2790 char buffer[8]; 2791 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2792 size_t len = strlen(buffer); 2793 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2794 while (found != NULL) { 2795 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2796 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2797 // Check that the bci found is bracketed by terminators. 2798 break; 2799 } 2800 found = strstr(found + 1, buffer); 2801 } 2802 if (!found) { 2803 continue; 2804 } 2805 } 2806 2807 if (DebugDeoptimization && !deopt) { 2808 deopt = true; // One-time only print before deopt 2809 tty->print_cr("[BEFORE Deoptimization]"); 2810 trace_frames(); 2811 trace_stack(); 2812 } 2813 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2814 } 2815 } 2816 2817 if (DebugDeoptimization && deopt) { 2818 tty->print_cr("[AFTER Deoptimization]"); 2819 trace_frames(); 2820 } 2821 } 2822 2823 2824 // Make zombies 2825 void JavaThread::make_zombies() { 2826 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2827 if (fst.current()->can_be_deoptimized()) { 2828 // it is a Java nmethod 2829 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2830 nm->make_not_entrant(); 2831 } 2832 } 2833 } 2834 #endif // PRODUCT 2835 2836 2837 void JavaThread::deoptimized_wrt_marked_nmethods() { 2838 if (!has_last_Java_frame()) return; 2839 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2840 StackFrameStream fst(this, UseBiasedLocking); 2841 for (; !fst.is_done(); fst.next()) { 2842 if (fst.current()->should_be_deoptimized()) { 2843 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2844 } 2845 } 2846 } 2847 2848 2849 // If the caller is a NamedThread, then remember, in the current scope, 2850 // the given JavaThread in its _processed_thread field. 2851 class RememberProcessedThread: public StackObj { 2852 NamedThread* _cur_thr; 2853 public: 2854 RememberProcessedThread(JavaThread* jthr) { 2855 Thread* thread = Thread::current(); 2856 if (thread->is_Named_thread()) { 2857 _cur_thr = (NamedThread *)thread; 2858 _cur_thr->set_processed_thread(jthr); 2859 } else { 2860 _cur_thr = NULL; 2861 } 2862 } 2863 2864 ~RememberProcessedThread() { 2865 if (_cur_thr) { 2866 _cur_thr->set_processed_thread(NULL); 2867 } 2868 } 2869 }; 2870 2871 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2872 // Verify that the deferred card marks have been flushed. 2873 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2874 2875 // Traverse the GCHandles 2876 Thread::oops_do(f, cf); 2877 2878 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2879 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2880 2881 if (has_last_Java_frame()) { 2882 // Record JavaThread to GC thread 2883 RememberProcessedThread rpt(this); 2884 2885 // traverse the registered growable array 2886 if (_array_for_gc != NULL) { 2887 for (int index = 0; index < _array_for_gc->length(); index++) { 2888 f->do_oop(_array_for_gc->adr_at(index)); 2889 } 2890 } 2891 2892 // Traverse the monitor chunks 2893 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2894 chunk->oops_do(f); 2895 } 2896 2897 // Traverse the execution stack 2898 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2899 fst.current()->oops_do(f, cf, fst.register_map()); 2900 } 2901 } 2902 2903 // callee_target is never live across a gc point so NULL it here should 2904 // it still contain a methdOop. 2905 2906 set_callee_target(NULL); 2907 2908 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2909 // If we have deferred set_locals there might be oops waiting to be 2910 // written 2911 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2912 if (list != NULL) { 2913 for (int i = 0; i < list->length(); i++) { 2914 list->at(i)->oops_do(f); 2915 } 2916 } 2917 2918 // Traverse instance variables at the end since the GC may be moving things 2919 // around using this function 2920 f->do_oop((oop*) &_threadObj); 2921 f->do_oop((oop*) &_vm_result); 2922 f->do_oop((oop*) &_exception_oop); 2923 f->do_oop((oop*) &_pending_async_exception); 2924 2925 if (jvmti_thread_state() != NULL) { 2926 jvmti_thread_state()->oops_do(f); 2927 } 2928 } 2929 2930 #ifdef ASSERT 2931 void JavaThread::verify_states_for_handshake() { 2932 // This checks that the thread has a correct frame state during a handshake. 2933 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2934 (has_last_Java_frame() && java_call_counter() > 0), 2935 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 2936 has_last_Java_frame(), java_call_counter()); 2937 } 2938 #endif 2939 2940 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2941 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2942 (has_last_Java_frame() && java_call_counter() > 0), 2943 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 2944 has_last_Java_frame(), java_call_counter()); 2945 2946 if (has_last_Java_frame()) { 2947 // Traverse the execution stack 2948 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2949 fst.current()->nmethods_do(cf); 2950 } 2951 } 2952 } 2953 2954 void JavaThread::metadata_do(MetadataClosure* f) { 2955 if (has_last_Java_frame()) { 2956 // Traverse the execution stack to call f() on the methods in the stack 2957 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2958 fst.current()->metadata_do(f); 2959 } 2960 } else if (is_Compiler_thread()) { 2961 // need to walk ciMetadata in current compile tasks to keep alive. 2962 CompilerThread* ct = (CompilerThread*)this; 2963 if (ct->env() != NULL) { 2964 ct->env()->metadata_do(f); 2965 } 2966 CompileTask* task = ct->task(); 2967 if (task != NULL) { 2968 task->metadata_do(f); 2969 } 2970 } 2971 } 2972 2973 // Printing 2974 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2975 switch (_thread_state) { 2976 case _thread_uninitialized: return "_thread_uninitialized"; 2977 case _thread_new: return "_thread_new"; 2978 case _thread_new_trans: return "_thread_new_trans"; 2979 case _thread_in_native: return "_thread_in_native"; 2980 case _thread_in_native_trans: return "_thread_in_native_trans"; 2981 case _thread_in_vm: return "_thread_in_vm"; 2982 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2983 case _thread_in_Java: return "_thread_in_Java"; 2984 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2985 case _thread_blocked: return "_thread_blocked"; 2986 case _thread_blocked_trans: return "_thread_blocked_trans"; 2987 default: return "unknown thread state"; 2988 } 2989 } 2990 2991 #ifndef PRODUCT 2992 void JavaThread::print_thread_state_on(outputStream *st) const { 2993 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2994 }; 2995 void JavaThread::print_thread_state() const { 2996 print_thread_state_on(tty); 2997 } 2998 #endif // PRODUCT 2999 3000 // Called by Threads::print() for VM_PrintThreads operation 3001 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3002 st->print_raw("\""); 3003 st->print_raw(get_thread_name()); 3004 st->print_raw("\" "); 3005 oop thread_oop = threadObj(); 3006 if (thread_oop != NULL) { 3007 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3008 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3009 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3010 } 3011 Thread::print_on(st, print_extended_info); 3012 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3013 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3014 if (thread_oop != NULL) { 3015 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3016 } 3017 #ifndef PRODUCT 3018 _safepoint_state->print_on(st); 3019 #endif // PRODUCT 3020 if (is_Compiler_thread()) { 3021 CompileTask *task = ((CompilerThread*)this)->task(); 3022 if (task != NULL) { 3023 st->print(" Compiling: "); 3024 task->print(st, NULL, true, false); 3025 } else { 3026 st->print(" No compile task"); 3027 } 3028 st->cr(); 3029 } 3030 } 3031 3032 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3033 st->print("%s", get_thread_name_string(buf, buflen)); 3034 } 3035 3036 // Called by fatal error handler. The difference between this and 3037 // JavaThread::print() is that we can't grab lock or allocate memory. 3038 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3039 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3040 oop thread_obj = threadObj(); 3041 if (thread_obj != NULL) { 3042 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3043 } 3044 st->print(" ["); 3045 st->print("%s", _get_thread_state_name(_thread_state)); 3046 if (osthread()) { 3047 st->print(", id=%d", osthread()->thread_id()); 3048 } 3049 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3050 p2i(stack_end()), p2i(stack_base())); 3051 st->print("]"); 3052 3053 ThreadsSMRSupport::print_info_on(this, st); 3054 return; 3055 } 3056 3057 // Verification 3058 3059 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3060 3061 void JavaThread::verify() { 3062 // Verify oops in the thread. 3063 oops_do(&VerifyOopClosure::verify_oop, NULL); 3064 3065 // Verify the stack frames. 3066 frames_do(frame_verify); 3067 } 3068 3069 // CR 6300358 (sub-CR 2137150) 3070 // Most callers of this method assume that it can't return NULL but a 3071 // thread may not have a name whilst it is in the process of attaching to 3072 // the VM - see CR 6412693, and there are places where a JavaThread can be 3073 // seen prior to having it's threadObj set (eg JNI attaching threads and 3074 // if vm exit occurs during initialization). These cases can all be accounted 3075 // for such that this method never returns NULL. 3076 const char* JavaThread::get_thread_name() const { 3077 #ifdef ASSERT 3078 // early safepoints can hit while current thread does not yet have TLS 3079 if (!SafepointSynchronize::is_at_safepoint()) { 3080 Thread *cur = Thread::current(); 3081 if (!(cur->is_Java_thread() && cur == this)) { 3082 // Current JavaThreads are allowed to get their own name without 3083 // the Threads_lock. 3084 assert_locked_or_safepoint(Threads_lock); 3085 } 3086 } 3087 #endif // ASSERT 3088 return get_thread_name_string(); 3089 } 3090 3091 // Returns a non-NULL representation of this thread's name, or a suitable 3092 // descriptive string if there is no set name 3093 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3094 const char* name_str; 3095 oop thread_obj = threadObj(); 3096 if (thread_obj != NULL) { 3097 oop name = java_lang_Thread::name(thread_obj); 3098 if (name != NULL) { 3099 if (buf == NULL) { 3100 name_str = java_lang_String::as_utf8_string(name); 3101 } else { 3102 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3103 } 3104 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3105 name_str = "<no-name - thread is attaching>"; 3106 } else { 3107 name_str = Thread::name(); 3108 } 3109 } else { 3110 name_str = Thread::name(); 3111 } 3112 assert(name_str != NULL, "unexpected NULL thread name"); 3113 return name_str; 3114 } 3115 3116 3117 const char* JavaThread::get_threadgroup_name() const { 3118 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3119 oop thread_obj = threadObj(); 3120 if (thread_obj != NULL) { 3121 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3122 if (thread_group != NULL) { 3123 // ThreadGroup.name can be null 3124 return java_lang_ThreadGroup::name(thread_group); 3125 } 3126 } 3127 return NULL; 3128 } 3129 3130 const char* JavaThread::get_parent_name() const { 3131 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3132 oop thread_obj = threadObj(); 3133 if (thread_obj != NULL) { 3134 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3135 if (thread_group != NULL) { 3136 oop parent = java_lang_ThreadGroup::parent(thread_group); 3137 if (parent != NULL) { 3138 // ThreadGroup.name can be null 3139 return java_lang_ThreadGroup::name(parent); 3140 } 3141 } 3142 } 3143 return NULL; 3144 } 3145 3146 ThreadPriority JavaThread::java_priority() const { 3147 oop thr_oop = threadObj(); 3148 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3149 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3150 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3151 return priority; 3152 } 3153 3154 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3155 3156 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3157 // Link Java Thread object <-> C++ Thread 3158 3159 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3160 // and put it into a new Handle. The Handle "thread_oop" can then 3161 // be used to pass the C++ thread object to other methods. 3162 3163 // Set the Java level thread object (jthread) field of the 3164 // new thread (a JavaThread *) to C++ thread object using the 3165 // "thread_oop" handle. 3166 3167 // Set the thread field (a JavaThread *) of the 3168 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3169 3170 Handle thread_oop(Thread::current(), 3171 JNIHandles::resolve_non_null(jni_thread)); 3172 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3173 "must be initialized"); 3174 set_threadObj(thread_oop()); 3175 java_lang_Thread::set_thread(thread_oop(), this); 3176 3177 if (prio == NoPriority) { 3178 prio = java_lang_Thread::priority(thread_oop()); 3179 assert(prio != NoPriority, "A valid priority should be present"); 3180 } 3181 3182 // Push the Java priority down to the native thread; needs Threads_lock 3183 Thread::set_priority(this, prio); 3184 3185 // Add the new thread to the Threads list and set it in motion. 3186 // We must have threads lock in order to call Threads::add. 3187 // It is crucial that we do not block before the thread is 3188 // added to the Threads list for if a GC happens, then the java_thread oop 3189 // will not be visited by GC. 3190 Threads::add(this); 3191 } 3192 3193 oop JavaThread::current_park_blocker() { 3194 // Support for JSR-166 locks 3195 oop thread_oop = threadObj(); 3196 if (thread_oop != NULL && 3197 JDK_Version::current().supports_thread_park_blocker()) { 3198 return java_lang_Thread::park_blocker(thread_oop); 3199 } 3200 return NULL; 3201 } 3202 3203 3204 void JavaThread::print_stack_on(outputStream* st) { 3205 if (!has_last_Java_frame()) return; 3206 ResourceMark rm; 3207 HandleMark hm; 3208 3209 RegisterMap reg_map(this); 3210 vframe* start_vf = last_java_vframe(®_map); 3211 int count = 0; 3212 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3213 if (f->is_java_frame()) { 3214 javaVFrame* jvf = javaVFrame::cast(f); 3215 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3216 3217 // Print out lock information 3218 if (JavaMonitorsInStackTrace) { 3219 jvf->print_lock_info_on(st, count); 3220 } 3221 } else { 3222 // Ignore non-Java frames 3223 } 3224 3225 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3226 count++; 3227 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3228 } 3229 } 3230 3231 3232 // JVMTI PopFrame support 3233 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3234 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3235 if (in_bytes(size_in_bytes) != 0) { 3236 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3237 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3238 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3239 } 3240 } 3241 3242 void* JavaThread::popframe_preserved_args() { 3243 return _popframe_preserved_args; 3244 } 3245 3246 ByteSize JavaThread::popframe_preserved_args_size() { 3247 return in_ByteSize(_popframe_preserved_args_size); 3248 } 3249 3250 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3251 int sz = in_bytes(popframe_preserved_args_size()); 3252 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3253 return in_WordSize(sz / wordSize); 3254 } 3255 3256 void JavaThread::popframe_free_preserved_args() { 3257 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3258 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3259 _popframe_preserved_args = NULL; 3260 _popframe_preserved_args_size = 0; 3261 } 3262 3263 #ifndef PRODUCT 3264 3265 void JavaThread::trace_frames() { 3266 tty->print_cr("[Describe stack]"); 3267 int frame_no = 1; 3268 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3269 tty->print(" %d. ", frame_no++); 3270 fst.current()->print_value_on(tty, this); 3271 tty->cr(); 3272 } 3273 } 3274 3275 class PrintAndVerifyOopClosure: public OopClosure { 3276 protected: 3277 template <class T> inline void do_oop_work(T* p) { 3278 oop obj = RawAccess<>::oop_load(p); 3279 if (obj == NULL) return; 3280 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3281 if (oopDesc::is_oop_or_null(obj)) { 3282 if (obj->is_objArray()) { 3283 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3284 } else { 3285 obj->print(); 3286 } 3287 } else { 3288 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3289 } 3290 tty->cr(); 3291 } 3292 public: 3293 virtual void do_oop(oop* p) { do_oop_work(p); } 3294 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3295 }; 3296 3297 3298 static void oops_print(frame* f, const RegisterMap *map) { 3299 PrintAndVerifyOopClosure print; 3300 f->print_value(); 3301 f->oops_do(&print, NULL, (RegisterMap*)map); 3302 } 3303 3304 // Print our all the locations that contain oops and whether they are 3305 // valid or not. This useful when trying to find the oldest frame 3306 // where an oop has gone bad since the frame walk is from youngest to 3307 // oldest. 3308 void JavaThread::trace_oops() { 3309 tty->print_cr("[Trace oops]"); 3310 frames_do(oops_print); 3311 } 3312 3313 3314 #ifdef ASSERT 3315 // Print or validate the layout of stack frames 3316 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3317 ResourceMark rm; 3318 PRESERVE_EXCEPTION_MARK; 3319 FrameValues values; 3320 int frame_no = 0; 3321 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3322 fst.current()->describe(values, ++frame_no); 3323 if (depth == frame_no) break; 3324 } 3325 if (validate_only) { 3326 values.validate(); 3327 } else { 3328 tty->print_cr("[Describe stack layout]"); 3329 values.print(this); 3330 } 3331 } 3332 #endif 3333 3334 void JavaThread::trace_stack_from(vframe* start_vf) { 3335 ResourceMark rm; 3336 int vframe_no = 1; 3337 for (vframe* f = start_vf; f; f = f->sender()) { 3338 if (f->is_java_frame()) { 3339 javaVFrame::cast(f)->print_activation(vframe_no++); 3340 } else { 3341 f->print(); 3342 } 3343 if (vframe_no > StackPrintLimit) { 3344 tty->print_cr("...<more frames>..."); 3345 return; 3346 } 3347 } 3348 } 3349 3350 3351 void JavaThread::trace_stack() { 3352 if (!has_last_Java_frame()) return; 3353 ResourceMark rm; 3354 HandleMark hm; 3355 RegisterMap reg_map(this); 3356 trace_stack_from(last_java_vframe(®_map)); 3357 } 3358 3359 3360 #endif // PRODUCT 3361 3362 3363 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3364 assert(reg_map != NULL, "a map must be given"); 3365 frame f = last_frame(); 3366 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3367 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3368 } 3369 return NULL; 3370 } 3371 3372 3373 Klass* JavaThread::security_get_caller_class(int depth) { 3374 vframeStream vfst(this); 3375 vfst.security_get_caller_frame(depth); 3376 if (!vfst.at_end()) { 3377 return vfst.method()->method_holder(); 3378 } 3379 return NULL; 3380 } 3381 3382 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3383 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3384 CompileBroker::compiler_thread_loop(); 3385 } 3386 3387 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3388 NMethodSweeper::sweeper_loop(); 3389 } 3390 3391 // Create a CompilerThread 3392 CompilerThread::CompilerThread(CompileQueue* queue, 3393 CompilerCounters* counters) 3394 : JavaThread(&compiler_thread_entry) { 3395 _env = NULL; 3396 _log = NULL; 3397 _task = NULL; 3398 _queue = queue; 3399 _counters = counters; 3400 _buffer_blob = NULL; 3401 _compiler = NULL; 3402 3403 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3404 resource_area()->bias_to(mtCompiler); 3405 3406 #ifndef PRODUCT 3407 _ideal_graph_printer = NULL; 3408 #endif 3409 } 3410 3411 CompilerThread::~CompilerThread() { 3412 // Delete objects which were allocated on heap. 3413 delete _counters; 3414 } 3415 3416 bool CompilerThread::can_call_java() const { 3417 return _compiler != NULL && _compiler->is_jvmci(); 3418 } 3419 3420 // Create sweeper thread 3421 CodeCacheSweeperThread::CodeCacheSweeperThread() 3422 : JavaThread(&sweeper_thread_entry) { 3423 _scanned_compiled_method = NULL; 3424 } 3425 3426 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3427 JavaThread::oops_do(f, cf); 3428 if (_scanned_compiled_method != NULL && cf != NULL) { 3429 // Safepoints can occur when the sweeper is scanning an nmethod so 3430 // process it here to make sure it isn't unloaded in the middle of 3431 // a scan. 3432 cf->do_code_blob(_scanned_compiled_method); 3433 } 3434 } 3435 3436 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3437 JavaThread::nmethods_do(cf); 3438 if (_scanned_compiled_method != NULL && cf != NULL) { 3439 // Safepoints can occur when the sweeper is scanning an nmethod so 3440 // process it here to make sure it isn't unloaded in the middle of 3441 // a scan. 3442 cf->do_code_blob(_scanned_compiled_method); 3443 } 3444 } 3445 3446 3447 // ======= Threads ======== 3448 3449 // The Threads class links together all active threads, and provides 3450 // operations over all threads. It is protected by the Threads_lock, 3451 // which is also used in other global contexts like safepointing. 3452 // ThreadsListHandles are used to safely perform operations on one 3453 // or more threads without the risk of the thread exiting during the 3454 // operation. 3455 // 3456 // Note: The Threads_lock is currently more widely used than we 3457 // would like. We are actively migrating Threads_lock uses to other 3458 // mechanisms in order to reduce Threads_lock contention. 3459 3460 JavaThread* Threads::_thread_list = NULL; 3461 int Threads::_number_of_threads = 0; 3462 int Threads::_number_of_non_daemon_threads = 0; 3463 int Threads::_return_code = 0; 3464 uintx Threads::_thread_claim_token = 1; // Never zero. 3465 size_t JavaThread::_stack_size_at_create = 0; 3466 3467 #ifdef ASSERT 3468 bool Threads::_vm_complete = false; 3469 #endif 3470 3471 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3472 Prefetch::read((void*)addr, prefetch_interval); 3473 return *addr; 3474 } 3475 3476 // Possibly the ugliest for loop the world has seen. C++ does not allow 3477 // multiple types in the declaration section of the for loop. In this case 3478 // we are only dealing with pointers and hence can cast them. It looks ugly 3479 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3480 #define DO_JAVA_THREADS(LIST, X) \ 3481 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3482 *MACRO_list = (JavaThread*)(LIST), \ 3483 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3484 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3485 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3486 MACRO_current_p != MACRO_end; \ 3487 MACRO_current_p++, \ 3488 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3489 3490 // All JavaThreads 3491 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3492 3493 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3494 void Threads::non_java_threads_do(ThreadClosure* tc) { 3495 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3496 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3497 tc->do_thread(njti.current()); 3498 } 3499 } 3500 3501 // All JavaThreads 3502 void Threads::java_threads_do(ThreadClosure* tc) { 3503 assert_locked_or_safepoint(Threads_lock); 3504 // ALL_JAVA_THREADS iterates through all JavaThreads. 3505 ALL_JAVA_THREADS(p) { 3506 tc->do_thread(p); 3507 } 3508 } 3509 3510 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3511 assert_locked_or_safepoint(Threads_lock); 3512 java_threads_do(tc); 3513 tc->do_thread(VMThread::vm_thread()); 3514 } 3515 3516 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3517 void Threads::threads_do(ThreadClosure* tc) { 3518 assert_locked_or_safepoint(Threads_lock); 3519 java_threads_do(tc); 3520 non_java_threads_do(tc); 3521 } 3522 3523 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3524 uintx claim_token = Threads::thread_claim_token(); 3525 ALL_JAVA_THREADS(p) { 3526 if (p->claim_threads_do(is_par, claim_token)) { 3527 tc->do_thread(p); 3528 } 3529 } 3530 VMThread* vmt = VMThread::vm_thread(); 3531 if (vmt->claim_threads_do(is_par, claim_token)) { 3532 tc->do_thread(vmt); 3533 } 3534 } 3535 3536 // The system initialization in the library has three phases. 3537 // 3538 // Phase 1: java.lang.System class initialization 3539 // java.lang.System is a primordial class loaded and initialized 3540 // by the VM early during startup. java.lang.System.<clinit> 3541 // only does registerNatives and keeps the rest of the class 3542 // initialization work later until thread initialization completes. 3543 // 3544 // System.initPhase1 initializes the system properties, the static 3545 // fields in, out, and err. Set up java signal handlers, OS-specific 3546 // system settings, and thread group of the main thread. 3547 static void call_initPhase1(TRAPS) { 3548 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3549 JavaValue result(T_VOID); 3550 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3551 vmSymbols::void_method_signature(), CHECK); 3552 } 3553 3554 // Phase 2. Module system initialization 3555 // This will initialize the module system. Only java.base classes 3556 // can be loaded until phase 2 completes. 3557 // 3558 // Call System.initPhase2 after the compiler initialization and jsr292 3559 // classes get initialized because module initialization runs a lot of java 3560 // code, that for performance reasons, should be compiled. Also, this will 3561 // enable the startup code to use lambda and other language features in this 3562 // phase and onward. 3563 // 3564 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3565 static void call_initPhase2(TRAPS) { 3566 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3567 3568 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3569 3570 JavaValue result(T_INT); 3571 JavaCallArguments args; 3572 args.push_int(DisplayVMOutputToStderr); 3573 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3574 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3575 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3576 if (result.get_jint() != JNI_OK) { 3577 vm_exit_during_initialization(); // no message or exception 3578 } 3579 3580 universe_post_module_init(); 3581 } 3582 3583 // Phase 3. final setup - set security manager, system class loader and TCCL 3584 // 3585 // This will instantiate and set the security manager, set the system class 3586 // loader as well as the thread context class loader. The security manager 3587 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3588 // other modules or the application's classpath. 3589 static void call_initPhase3(TRAPS) { 3590 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3591 JavaValue result(T_VOID); 3592 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3593 vmSymbols::void_method_signature(), CHECK); 3594 } 3595 3596 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3597 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3598 3599 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3600 create_vm_init_libraries(); 3601 } 3602 3603 initialize_class(vmSymbols::java_lang_String(), CHECK); 3604 3605 // Inject CompactStrings value after the static initializers for String ran. 3606 java_lang_String::set_compact_strings(CompactStrings); 3607 3608 // Initialize java_lang.System (needed before creating the thread) 3609 initialize_class(vmSymbols::java_lang_System(), CHECK); 3610 // The VM creates & returns objects of this class. Make sure it's initialized. 3611 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3612 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3613 Handle thread_group = create_initial_thread_group(CHECK); 3614 Universe::set_main_thread_group(thread_group()); 3615 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3616 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3617 main_thread->set_threadObj(thread_object); 3618 3619 // Set thread status to running since main thread has 3620 // been started and running. 3621 java_lang_Thread::set_thread_status(thread_object, 3622 java_lang_Thread::RUNNABLE); 3623 3624 // The VM creates objects of this class. 3625 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3626 3627 #ifdef ASSERT 3628 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3629 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3630 #endif 3631 3632 // initialize the hardware-specific constants needed by Unsafe 3633 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3634 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3635 3636 // The VM preresolves methods to these classes. Make sure that they get initialized 3637 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3638 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3639 3640 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3641 call_initPhase1(CHECK); 3642 3643 // get the Java runtime name after java.lang.System is initialized 3644 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3645 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3646 3647 // an instance of OutOfMemory exception has been allocated earlier 3648 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3649 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3650 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3651 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3652 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3653 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3654 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3655 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3656 } 3657 3658 void Threads::initialize_jsr292_core_classes(TRAPS) { 3659 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3660 3661 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3662 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3663 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3664 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3665 } 3666 3667 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3668 extern void JDK_Version_init(); 3669 3670 // Preinitialize version info. 3671 VM_Version::early_initialize(); 3672 3673 // Check version 3674 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3675 3676 // Initialize library-based TLS 3677 ThreadLocalStorage::init(); 3678 3679 // Initialize the output stream module 3680 ostream_init(); 3681 3682 // Process java launcher properties. 3683 Arguments::process_sun_java_launcher_properties(args); 3684 3685 // Initialize the os module 3686 os::init(); 3687 3688 // Record VM creation timing statistics 3689 TraceVmCreationTime create_vm_timer; 3690 create_vm_timer.start(); 3691 3692 // Initialize system properties. 3693 Arguments::init_system_properties(); 3694 3695 // So that JDK version can be used as a discriminator when parsing arguments 3696 JDK_Version_init(); 3697 3698 // Update/Initialize System properties after JDK version number is known 3699 Arguments::init_version_specific_system_properties(); 3700 3701 // Make sure to initialize log configuration *before* parsing arguments 3702 LogConfiguration::initialize(create_vm_timer.begin_time()); 3703 3704 // Parse arguments 3705 // Note: this internally calls os::init_container_support() 3706 jint parse_result = Arguments::parse(args); 3707 if (parse_result != JNI_OK) return parse_result; 3708 3709 os::init_before_ergo(); 3710 3711 jint ergo_result = Arguments::apply_ergo(); 3712 if (ergo_result != JNI_OK) return ergo_result; 3713 3714 // Final check of all ranges after ergonomics which may change values. 3715 if (!JVMFlagRangeList::check_ranges()) { 3716 return JNI_EINVAL; 3717 } 3718 3719 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3720 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3721 if (!constraint_result) { 3722 return JNI_EINVAL; 3723 } 3724 3725 JVMFlagWriteableList::mark_startup(); 3726 3727 if (PauseAtStartup) { 3728 os::pause(); 3729 } 3730 3731 HOTSPOT_VM_INIT_BEGIN(); 3732 3733 // Timing (must come after argument parsing) 3734 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3735 3736 // Initialize the os module after parsing the args 3737 jint os_init_2_result = os::init_2(); 3738 if (os_init_2_result != JNI_OK) return os_init_2_result; 3739 3740 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3741 // Initialize assert poison page mechanism. 3742 if (ShowRegistersOnAssert) { 3743 initialize_assert_poison(); 3744 } 3745 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3746 3747 SafepointMechanism::initialize(); 3748 3749 jint adjust_after_os_result = Arguments::adjust_after_os(); 3750 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3751 3752 // Initialize output stream logging 3753 ostream_init_log(); 3754 3755 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3756 // Must be before create_vm_init_agents() 3757 if (Arguments::init_libraries_at_startup()) { 3758 convert_vm_init_libraries_to_agents(); 3759 } 3760 3761 // Launch -agentlib/-agentpath and converted -Xrun agents 3762 if (Arguments::init_agents_at_startup()) { 3763 create_vm_init_agents(); 3764 } 3765 3766 // Initialize Threads state 3767 _thread_list = NULL; 3768 _number_of_threads = 0; 3769 _number_of_non_daemon_threads = 0; 3770 3771 // Initialize global data structures and create system classes in heap 3772 vm_init_globals(); 3773 3774 #if INCLUDE_JVMCI 3775 if (JVMCICounterSize > 0) { 3776 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3777 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3778 } else { 3779 JavaThread::_jvmci_old_thread_counters = NULL; 3780 } 3781 #endif // INCLUDE_JVMCI 3782 3783 // Attach the main thread to this os thread 3784 JavaThread* main_thread = new JavaThread(); 3785 main_thread->set_thread_state(_thread_in_vm); 3786 main_thread->initialize_thread_current(); 3787 // must do this before set_active_handles 3788 main_thread->record_stack_base_and_size(); 3789 main_thread->register_thread_stack_with_NMT(); 3790 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3791 3792 if (!main_thread->set_as_starting_thread()) { 3793 vm_shutdown_during_initialization( 3794 "Failed necessary internal allocation. Out of swap space"); 3795 main_thread->smr_delete(); 3796 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3797 return JNI_ENOMEM; 3798 } 3799 3800 // Enable guard page *after* os::create_main_thread(), otherwise it would 3801 // crash Linux VM, see notes in os_linux.cpp. 3802 main_thread->create_stack_guard_pages(); 3803 3804 // Initialize Java-Level synchronization subsystem 3805 ObjectMonitor::Initialize(); 3806 3807 // Initialize global modules 3808 jint status = init_globals(); 3809 if (status != JNI_OK) { 3810 main_thread->smr_delete(); 3811 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3812 return status; 3813 } 3814 3815 JFR_ONLY(Jfr::on_vm_init();) 3816 3817 // Should be done after the heap is fully created 3818 main_thread->cache_global_variables(); 3819 3820 HandleMark hm; 3821 3822 { MutexLocker mu(Threads_lock); 3823 Threads::add(main_thread); 3824 } 3825 3826 // Any JVMTI raw monitors entered in onload will transition into 3827 // real raw monitor. VM is setup enough here for raw monitor enter. 3828 JvmtiExport::transition_pending_onload_raw_monitors(); 3829 3830 // Create the VMThread 3831 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3832 3833 VMThread::create(); 3834 Thread* vmthread = VMThread::vm_thread(); 3835 3836 if (!os::create_thread(vmthread, os::vm_thread)) { 3837 vm_exit_during_initialization("Cannot create VM thread. " 3838 "Out of system resources."); 3839 } 3840 3841 // Wait for the VM thread to become ready, and VMThread::run to initialize 3842 // Monitors can have spurious returns, must always check another state flag 3843 { 3844 MonitorLocker ml(Notify_lock); 3845 os::start_thread(vmthread); 3846 while (vmthread->active_handles() == NULL) { 3847 ml.wait(); 3848 } 3849 } 3850 } 3851 3852 assert(Universe::is_fully_initialized(), "not initialized"); 3853 if (VerifyDuringStartup) { 3854 // Make sure we're starting with a clean slate. 3855 VM_Verify verify_op; 3856 VMThread::execute(&verify_op); 3857 } 3858 3859 // We need this to update the java.vm.info property in case any flags used 3860 // to initially define it have been changed. This is needed for both CDS and 3861 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3862 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3863 // This update must happen before we initialize the java classes, but 3864 // after any initialization logic that might modify the flags. 3865 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3866 3867 Thread* THREAD = Thread::current(); 3868 3869 // Always call even when there are not JVMTI environments yet, since environments 3870 // may be attached late and JVMTI must track phases of VM execution 3871 JvmtiExport::enter_early_start_phase(); 3872 3873 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3874 JvmtiExport::post_early_vm_start(); 3875 3876 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3877 3878 quicken_jni_functions(); 3879 3880 // No more stub generation allowed after that point. 3881 StubCodeDesc::freeze(); 3882 3883 // Set flag that basic initialization has completed. Used by exceptions and various 3884 // debug stuff, that does not work until all basic classes have been initialized. 3885 set_init_completed(); 3886 3887 LogConfiguration::post_initialize(); 3888 Metaspace::post_initialize(); 3889 3890 HOTSPOT_VM_INIT_END(); 3891 3892 // record VM initialization completion time 3893 #if INCLUDE_MANAGEMENT 3894 Management::record_vm_init_completed(); 3895 #endif // INCLUDE_MANAGEMENT 3896 3897 // Signal Dispatcher needs to be started before VMInit event is posted 3898 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3899 3900 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3901 if (!DisableAttachMechanism) { 3902 AttachListener::vm_start(); 3903 if (StartAttachListener || AttachListener::init_at_startup()) { 3904 AttachListener::init(); 3905 } 3906 } 3907 3908 // Launch -Xrun agents 3909 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3910 // back-end can launch with -Xdebug -Xrunjdwp. 3911 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3912 create_vm_init_libraries(); 3913 } 3914 3915 if (CleanChunkPoolAsync) { 3916 Chunk::start_chunk_pool_cleaner_task(); 3917 } 3918 3919 // initialize compiler(s) 3920 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3921 #if INCLUDE_JVMCI 3922 bool force_JVMCI_intialization = false; 3923 if (EnableJVMCI) { 3924 // Initialize JVMCI eagerly when it is explicitly requested. 3925 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 3926 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 3927 3928 if (!force_JVMCI_intialization) { 3929 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3930 // compilations via JVMCI will not actually block until JVMCI is initialized. 3931 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3932 } 3933 } 3934 #endif 3935 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3936 // Postpone completion of compiler initialization to after JVMCI 3937 // is initialized to avoid timeouts of blocking compilations. 3938 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3939 CompileBroker::compilation_init_phase2(); 3940 } 3941 #endif 3942 3943 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3944 // It is done after compilers are initialized, because otherwise compilations of 3945 // signature polymorphic MH intrinsics can be missed 3946 // (see SystemDictionary::find_method_handle_intrinsic). 3947 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3948 3949 // This will initialize the module system. Only java.base classes can be 3950 // loaded until phase 2 completes 3951 call_initPhase2(CHECK_JNI_ERR); 3952 3953 // Always call even when there are not JVMTI environments yet, since environments 3954 // may be attached late and JVMTI must track phases of VM execution 3955 JvmtiExport::enter_start_phase(); 3956 3957 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3958 JvmtiExport::post_vm_start(); 3959 3960 // Final system initialization including security manager and system class loader 3961 call_initPhase3(CHECK_JNI_ERR); 3962 3963 // cache the system and platform class loaders 3964 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3965 3966 #if INCLUDE_CDS 3967 if (DumpSharedSpaces) { 3968 // capture the module path info from the ModuleEntryTable 3969 ClassLoader::initialize_module_path(THREAD); 3970 } 3971 #endif 3972 3973 #if INCLUDE_JVMCI 3974 if (force_JVMCI_intialization) { 3975 JVMCI::initialize_compiler(CHECK_JNI_ERR); 3976 CompileBroker::compilation_init_phase2(); 3977 } 3978 #endif 3979 3980 // Always call even when there are not JVMTI environments yet, since environments 3981 // may be attached late and JVMTI must track phases of VM execution 3982 JvmtiExport::enter_live_phase(); 3983 3984 // Make perfmemory accessible 3985 PerfMemory::set_accessible(true); 3986 3987 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3988 JvmtiExport::post_vm_initialized(); 3989 3990 JFR_ONLY(Jfr::on_vm_start();) 3991 3992 #if INCLUDE_MANAGEMENT 3993 Management::initialize(THREAD); 3994 3995 if (HAS_PENDING_EXCEPTION) { 3996 // management agent fails to start possibly due to 3997 // configuration problem and is responsible for printing 3998 // stack trace if appropriate. Simply exit VM. 3999 vm_exit(1); 4000 } 4001 #endif // INCLUDE_MANAGEMENT 4002 4003 if (MemProfiling) MemProfiler::engage(); 4004 StatSampler::engage(); 4005 if (CheckJNICalls) JniPeriodicChecker::engage(); 4006 4007 BiasedLocking::init(); 4008 4009 #if INCLUDE_RTM_OPT 4010 RTMLockingCounters::init(); 4011 #endif 4012 4013 if (JDK_Version::current().post_vm_init_hook_enabled()) { 4014 call_postVMInitHook(THREAD); 4015 // The Java side of PostVMInitHook.run must deal with all 4016 // exceptions and provide means of diagnosis. 4017 if (HAS_PENDING_EXCEPTION) { 4018 CLEAR_PENDING_EXCEPTION; 4019 } 4020 } 4021 4022 { 4023 MutexLocker ml(PeriodicTask_lock); 4024 // Make sure the WatcherThread can be started by WatcherThread::start() 4025 // or by dynamic enrollment. 4026 WatcherThread::make_startable(); 4027 // Start up the WatcherThread if there are any periodic tasks 4028 // NOTE: All PeriodicTasks should be registered by now. If they 4029 // aren't, late joiners might appear to start slowly (we might 4030 // take a while to process their first tick). 4031 if (PeriodicTask::num_tasks() > 0) { 4032 WatcherThread::start(); 4033 } 4034 } 4035 4036 create_vm_timer.end(); 4037 #ifdef ASSERT 4038 _vm_complete = true; 4039 #endif 4040 4041 if (DumpSharedSpaces) { 4042 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4043 ShouldNotReachHere(); 4044 } 4045 4046 return JNI_OK; 4047 } 4048 4049 // type for the Agent_OnLoad and JVM_OnLoad entry points 4050 extern "C" { 4051 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4052 } 4053 // Find a command line agent library and return its entry point for 4054 // -agentlib: -agentpath: -Xrun 4055 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4056 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4057 const char *on_load_symbols[], 4058 size_t num_symbol_entries) { 4059 OnLoadEntry_t on_load_entry = NULL; 4060 void *library = NULL; 4061 4062 if (!agent->valid()) { 4063 char buffer[JVM_MAXPATHLEN]; 4064 char ebuf[1024] = ""; 4065 const char *name = agent->name(); 4066 const char *msg = "Could not find agent library "; 4067 4068 // First check to see if agent is statically linked into executable 4069 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4070 library = agent->os_lib(); 4071 } else if (agent->is_absolute_path()) { 4072 library = os::dll_load(name, ebuf, sizeof ebuf); 4073 if (library == NULL) { 4074 const char *sub_msg = " in absolute path, with error: "; 4075 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4076 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4077 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4078 // If we can't find the agent, exit. 4079 vm_exit_during_initialization(buf, NULL); 4080 FREE_C_HEAP_ARRAY(char, buf); 4081 } 4082 } else { 4083 // Try to load the agent from the standard dll directory 4084 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4085 name)) { 4086 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4087 } 4088 if (library == NULL) { // Try the library path directory. 4089 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4090 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4091 } 4092 if (library == NULL) { 4093 const char *sub_msg = " on the library path, with error: "; 4094 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4095 4096 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4097 strlen(ebuf) + strlen(sub_msg2) + 1; 4098 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4099 if (!agent->is_instrument_lib()) { 4100 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4101 } else { 4102 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4103 } 4104 // If we can't find the agent, exit. 4105 vm_exit_during_initialization(buf, NULL); 4106 FREE_C_HEAP_ARRAY(char, buf); 4107 } 4108 } 4109 } 4110 agent->set_os_lib(library); 4111 agent->set_valid(); 4112 } 4113 4114 // Find the OnLoad function. 4115 on_load_entry = 4116 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4117 false, 4118 on_load_symbols, 4119 num_symbol_entries)); 4120 return on_load_entry; 4121 } 4122 4123 // Find the JVM_OnLoad entry point 4124 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4125 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4126 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4127 } 4128 4129 // Find the Agent_OnLoad entry point 4130 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4131 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4132 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4133 } 4134 4135 // For backwards compatibility with -Xrun 4136 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4137 // treated like -agentpath: 4138 // Must be called before agent libraries are created 4139 void Threads::convert_vm_init_libraries_to_agents() { 4140 AgentLibrary* agent; 4141 AgentLibrary* next; 4142 4143 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4144 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4145 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4146 4147 // If there is an JVM_OnLoad function it will get called later, 4148 // otherwise see if there is an Agent_OnLoad 4149 if (on_load_entry == NULL) { 4150 on_load_entry = lookup_agent_on_load(agent); 4151 if (on_load_entry != NULL) { 4152 // switch it to the agent list -- so that Agent_OnLoad will be called, 4153 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4154 Arguments::convert_library_to_agent(agent); 4155 } else { 4156 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4157 } 4158 } 4159 } 4160 } 4161 4162 // Create agents for -agentlib: -agentpath: and converted -Xrun 4163 // Invokes Agent_OnLoad 4164 // Called very early -- before JavaThreads exist 4165 void Threads::create_vm_init_agents() { 4166 extern struct JavaVM_ main_vm; 4167 AgentLibrary* agent; 4168 4169 JvmtiExport::enter_onload_phase(); 4170 4171 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4172 // CDS dumping does not support native JVMTI agent. 4173 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4174 if (DumpSharedSpaces) { 4175 if(!agent->is_instrument_lib()) { 4176 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4177 } else if (!AllowArchivingWithJavaAgent) { 4178 vm_exit_during_cds_dumping( 4179 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4180 } 4181 } 4182 4183 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4184 4185 if (on_load_entry != NULL) { 4186 // Invoke the Agent_OnLoad function 4187 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4188 if (err != JNI_OK) { 4189 vm_exit_during_initialization("agent library failed to init", agent->name()); 4190 } 4191 } else { 4192 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4193 } 4194 } 4195 4196 JvmtiExport::enter_primordial_phase(); 4197 } 4198 4199 extern "C" { 4200 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4201 } 4202 4203 void Threads::shutdown_vm_agents() { 4204 // Send any Agent_OnUnload notifications 4205 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4206 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4207 extern struct JavaVM_ main_vm; 4208 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4209 4210 // Find the Agent_OnUnload function. 4211 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4212 os::find_agent_function(agent, 4213 false, 4214 on_unload_symbols, 4215 num_symbol_entries)); 4216 4217 // Invoke the Agent_OnUnload function 4218 if (unload_entry != NULL) { 4219 JavaThread* thread = JavaThread::current(); 4220 ThreadToNativeFromVM ttn(thread); 4221 HandleMark hm(thread); 4222 (*unload_entry)(&main_vm); 4223 } 4224 } 4225 } 4226 4227 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4228 // Invokes JVM_OnLoad 4229 void Threads::create_vm_init_libraries() { 4230 extern struct JavaVM_ main_vm; 4231 AgentLibrary* agent; 4232 4233 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4234 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4235 4236 if (on_load_entry != NULL) { 4237 // Invoke the JVM_OnLoad function 4238 JavaThread* thread = JavaThread::current(); 4239 ThreadToNativeFromVM ttn(thread); 4240 HandleMark hm(thread); 4241 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4242 if (err != JNI_OK) { 4243 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4244 } 4245 } else { 4246 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4247 } 4248 } 4249 } 4250 4251 4252 // Last thread running calls java.lang.Shutdown.shutdown() 4253 void JavaThread::invoke_shutdown_hooks() { 4254 HandleMark hm(this); 4255 4256 // We could get here with a pending exception, if so clear it now. 4257 if (this->has_pending_exception()) { 4258 this->clear_pending_exception(); 4259 } 4260 4261 EXCEPTION_MARK; 4262 Klass* shutdown_klass = 4263 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4264 THREAD); 4265 if (shutdown_klass != NULL) { 4266 // SystemDictionary::resolve_or_null will return null if there was 4267 // an exception. If we cannot load the Shutdown class, just don't 4268 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4269 // won't be run. Note that if a shutdown hook was registered, 4270 // the Shutdown class would have already been loaded 4271 // (Runtime.addShutdownHook will load it). 4272 JavaValue result(T_VOID); 4273 JavaCalls::call_static(&result, 4274 shutdown_klass, 4275 vmSymbols::shutdown_name(), 4276 vmSymbols::void_method_signature(), 4277 THREAD); 4278 } 4279 CLEAR_PENDING_EXCEPTION; 4280 } 4281 4282 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4283 // the program falls off the end of main(). Another VM exit path is through 4284 // vm_exit() when the program calls System.exit() to return a value or when 4285 // there is a serious error in VM. The two shutdown paths are not exactly 4286 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4287 // and VM_Exit op at VM level. 4288 // 4289 // Shutdown sequence: 4290 // + Shutdown native memory tracking if it is on 4291 // + Wait until we are the last non-daemon thread to execute 4292 // <-- every thing is still working at this moment --> 4293 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4294 // shutdown hooks 4295 // + Call before_exit(), prepare for VM exit 4296 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4297 // currently the only user of this mechanism is File.deleteOnExit()) 4298 // > stop StatSampler, watcher thread, CMS threads, 4299 // post thread end and vm death events to JVMTI, 4300 // stop signal thread 4301 // + Call JavaThread::exit(), it will: 4302 // > release JNI handle blocks, remove stack guard pages 4303 // > remove this thread from Threads list 4304 // <-- no more Java code from this thread after this point --> 4305 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4306 // the compiler threads at safepoint 4307 // <-- do not use anything that could get blocked by Safepoint --> 4308 // + Disable tracing at JNI/JVM barriers 4309 // + Set _vm_exited flag for threads that are still running native code 4310 // + Call exit_globals() 4311 // > deletes tty 4312 // > deletes PerfMemory resources 4313 // + Delete this thread 4314 // + Return to caller 4315 4316 bool Threads::destroy_vm() { 4317 JavaThread* thread = JavaThread::current(); 4318 4319 #ifdef ASSERT 4320 _vm_complete = false; 4321 #endif 4322 // Wait until we are the last non-daemon thread to execute 4323 { MonitorLocker nu(Threads_lock); 4324 while (Threads::number_of_non_daemon_threads() > 1) 4325 // This wait should make safepoint checks, wait without a timeout, 4326 // and wait as a suspend-equivalent condition. 4327 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4328 } 4329 4330 EventShutdown e; 4331 if (e.should_commit()) { 4332 e.set_reason("No remaining non-daemon Java threads"); 4333 e.commit(); 4334 } 4335 4336 // Hang forever on exit if we are reporting an error. 4337 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4338 os::infinite_sleep(); 4339 } 4340 os::wait_for_keypress_at_exit(); 4341 4342 // run Java level shutdown hooks 4343 thread->invoke_shutdown_hooks(); 4344 4345 before_exit(thread); 4346 4347 thread->exit(true); 4348 4349 // Stop VM thread. 4350 { 4351 // 4945125 The vm thread comes to a safepoint during exit. 4352 // GC vm_operations can get caught at the safepoint, and the 4353 // heap is unparseable if they are caught. Grab the Heap_lock 4354 // to prevent this. The GC vm_operations will not be able to 4355 // queue until after the vm thread is dead. After this point, 4356 // we'll never emerge out of the safepoint before the VM exits. 4357 4358 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4359 4360 VMThread::wait_for_vm_thread_exit(); 4361 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4362 VMThread::destroy(); 4363 } 4364 4365 // Now, all Java threads are gone except daemon threads. Daemon threads 4366 // running Java code or in VM are stopped by the Safepoint. However, 4367 // daemon threads executing native code are still running. But they 4368 // will be stopped at native=>Java/VM barriers. Note that we can't 4369 // simply kill or suspend them, as it is inherently deadlock-prone. 4370 4371 VM_Exit::set_vm_exited(); 4372 4373 // Clean up ideal graph printers after the VMThread has started 4374 // the final safepoint which will block all the Compiler threads. 4375 // Note that this Thread has already logically exited so the 4376 // clean_up() function's use of a JavaThreadIteratorWithHandle 4377 // would be a problem except set_vm_exited() has remembered the 4378 // shutdown thread which is granted a policy exception. 4379 #if defined(COMPILER2) && !defined(PRODUCT) 4380 IdealGraphPrinter::clean_up(); 4381 #endif 4382 4383 notify_vm_shutdown(); 4384 4385 // exit_globals() will delete tty 4386 exit_globals(); 4387 4388 // We are after VM_Exit::set_vm_exited() so we can't call 4389 // thread->smr_delete() or we will block on the Threads_lock. 4390 // Deleting the shutdown thread here is safe because another 4391 // JavaThread cannot have an active ThreadsListHandle for 4392 // this JavaThread. 4393 delete thread; 4394 4395 #if INCLUDE_JVMCI 4396 if (JVMCICounterSize > 0) { 4397 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4398 } 4399 #endif 4400 4401 LogConfiguration::finalize(); 4402 4403 return true; 4404 } 4405 4406 4407 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4408 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4409 return is_supported_jni_version(version); 4410 } 4411 4412 4413 jboolean Threads::is_supported_jni_version(jint version) { 4414 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4415 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4416 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4417 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4418 if (version == JNI_VERSION_9) return JNI_TRUE; 4419 if (version == JNI_VERSION_10) return JNI_TRUE; 4420 return JNI_FALSE; 4421 } 4422 4423 4424 void Threads::add(JavaThread* p, bool force_daemon) { 4425 // The threads lock must be owned at this point 4426 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4427 4428 BarrierSet::barrier_set()->on_thread_attach(p); 4429 4430 p->set_next(_thread_list); 4431 _thread_list = p; 4432 4433 // Once a JavaThread is added to the Threads list, smr_delete() has 4434 // to be used to delete it. Otherwise we can just delete it directly. 4435 p->set_on_thread_list(); 4436 4437 _number_of_threads++; 4438 oop threadObj = p->threadObj(); 4439 bool daemon = true; 4440 // Bootstrapping problem: threadObj can be null for initial 4441 // JavaThread (or for threads attached via JNI) 4442 if ((!force_daemon) && !is_daemon((threadObj))) { 4443 _number_of_non_daemon_threads++; 4444 daemon = false; 4445 } 4446 4447 ThreadService::add_thread(p, daemon); 4448 4449 // Maintain fast thread list 4450 ThreadsSMRSupport::add_thread(p); 4451 4452 // Possible GC point. 4453 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4454 } 4455 4456 void Threads::remove(JavaThread* p, bool is_daemon) { 4457 4458 // Reclaim the ObjectMonitors from the omInUseList and omFreeList of the moribund thread. 4459 ObjectSynchronizer::omFlush(p); 4460 4461 // Extra scope needed for Thread_lock, so we can check 4462 // that we do not remove thread without safepoint code notice 4463 { MonitorLocker ml(Threads_lock); 4464 4465 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4466 4467 // Maintain fast thread list 4468 ThreadsSMRSupport::remove_thread(p); 4469 4470 JavaThread* current = _thread_list; 4471 JavaThread* prev = NULL; 4472 4473 while (current != p) { 4474 prev = current; 4475 current = current->next(); 4476 } 4477 4478 if (prev) { 4479 prev->set_next(current->next()); 4480 } else { 4481 _thread_list = p->next(); 4482 } 4483 4484 _number_of_threads--; 4485 if (!is_daemon) { 4486 _number_of_non_daemon_threads--; 4487 4488 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4489 // on destroy_vm will wake up. 4490 if (number_of_non_daemon_threads() == 1) { 4491 ml.notify_all(); 4492 } 4493 } 4494 ThreadService::remove_thread(p, is_daemon); 4495 4496 // Make sure that safepoint code disregard this thread. This is needed since 4497 // the thread might mess around with locks after this point. This can cause it 4498 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4499 // of this thread since it is removed from the queue. 4500 p->set_terminated_value(); 4501 } // unlock Threads_lock 4502 4503 // Since Events::log uses a lock, we grab it outside the Threads_lock 4504 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4505 } 4506 4507 // Operations on the Threads list for GC. These are not explicitly locked, 4508 // but the garbage collector must provide a safe context for them to run. 4509 // In particular, these things should never be called when the Threads_lock 4510 // is held by some other thread. (Note: the Safepoint abstraction also 4511 // uses the Threads_lock to guarantee this property. It also makes sure that 4512 // all threads gets blocked when exiting or starting). 4513 4514 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4515 ALL_JAVA_THREADS(p) { 4516 p->oops_do(f, cf); 4517 } 4518 VMThread::vm_thread()->oops_do(f, cf); 4519 } 4520 4521 void Threads::change_thread_claim_token() { 4522 if (++_thread_claim_token == 0) { 4523 // On overflow of the token counter, there is a risk of future 4524 // collisions between a new global token value and a stale token 4525 // for a thread, because not all iterations visit all threads. 4526 // (Though it's pretty much a theoretical concern for non-trivial 4527 // token counter sizes.) To deal with the possibility, reset all 4528 // the thread tokens to zero on global token overflow. 4529 struct ResetClaims : public ThreadClosure { 4530 virtual void do_thread(Thread* t) { 4531 t->claim_threads_do(false, 0); 4532 } 4533 } reset_claims; 4534 Threads::threads_do(&reset_claims); 4535 // On overflow, update the global token to non-zero, to 4536 // avoid the special "never claimed" initial thread value. 4537 _thread_claim_token = 1; 4538 } 4539 } 4540 4541 #ifdef ASSERT 4542 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4543 const uintx token = t->threads_do_token(); 4544 assert(token == expected, 4545 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4546 UINTX_FORMAT, kind, p2i(t), token, expected); 4547 } 4548 4549 void Threads::assert_all_threads_claimed() { 4550 ALL_JAVA_THREADS(p) { 4551 assert_thread_claimed("Thread", p, _thread_claim_token); 4552 } 4553 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4554 } 4555 #endif // ASSERT 4556 4557 class ParallelOopsDoThreadClosure : public ThreadClosure { 4558 private: 4559 OopClosure* _f; 4560 CodeBlobClosure* _cf; 4561 public: 4562 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4563 void do_thread(Thread* t) { 4564 t->oops_do(_f, _cf); 4565 } 4566 }; 4567 4568 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4569 ParallelOopsDoThreadClosure tc(f, cf); 4570 possibly_parallel_threads_do(is_par, &tc); 4571 } 4572 4573 void Threads::nmethods_do(CodeBlobClosure* cf) { 4574 ALL_JAVA_THREADS(p) { 4575 // This is used by the code cache sweeper to mark nmethods that are active 4576 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4577 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4578 if(!p->is_Code_cache_sweeper_thread()) { 4579 p->nmethods_do(cf); 4580 } 4581 } 4582 } 4583 4584 void Threads::metadata_do(MetadataClosure* f) { 4585 ALL_JAVA_THREADS(p) { 4586 p->metadata_do(f); 4587 } 4588 } 4589 4590 class ThreadHandlesClosure : public ThreadClosure { 4591 void (*_f)(Metadata*); 4592 public: 4593 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4594 virtual void do_thread(Thread* thread) { 4595 thread->metadata_handles_do(_f); 4596 } 4597 }; 4598 4599 void Threads::metadata_handles_do(void f(Metadata*)) { 4600 // Only walk the Handles in Thread. 4601 ThreadHandlesClosure handles_closure(f); 4602 threads_do(&handles_closure); 4603 } 4604 4605 void Threads::deoptimized_wrt_marked_nmethods() { 4606 ALL_JAVA_THREADS(p) { 4607 p->deoptimized_wrt_marked_nmethods(); 4608 } 4609 } 4610 4611 4612 // Get count Java threads that are waiting to enter the specified monitor. 4613 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4614 int count, 4615 address monitor) { 4616 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4617 4618 int i = 0; 4619 DO_JAVA_THREADS(t_list, p) { 4620 if (!p->can_call_java()) continue; 4621 4622 address pending = (address)p->current_pending_monitor(); 4623 if (pending == monitor) { // found a match 4624 if (i < count) result->append(p); // save the first count matches 4625 i++; 4626 } 4627 } 4628 4629 return result; 4630 } 4631 4632 4633 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4634 address owner) { 4635 // NULL owner means not locked so we can skip the search 4636 if (owner == NULL) return NULL; 4637 4638 DO_JAVA_THREADS(t_list, p) { 4639 // first, see if owner is the address of a Java thread 4640 if (owner == (address)p) return p; 4641 } 4642 4643 // Cannot assert on lack of success here since this function may be 4644 // used by code that is trying to report useful problem information 4645 // like deadlock detection. 4646 if (UseHeavyMonitors) return NULL; 4647 4648 // If we didn't find a matching Java thread and we didn't force use of 4649 // heavyweight monitors, then the owner is the stack address of the 4650 // Lock Word in the owning Java thread's stack. 4651 // 4652 JavaThread* the_owner = NULL; 4653 DO_JAVA_THREADS(t_list, q) { 4654 if (q->is_lock_owned(owner)) { 4655 the_owner = q; 4656 break; 4657 } 4658 } 4659 4660 // cannot assert on lack of success here; see above comment 4661 return the_owner; 4662 } 4663 4664 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4665 void Threads::print_on(outputStream* st, bool print_stacks, 4666 bool internal_format, bool print_concurrent_locks, 4667 bool print_extended_info) { 4668 char buf[32]; 4669 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4670 4671 st->print_cr("Full thread dump %s (%s %s):", 4672 VM_Version::vm_name(), 4673 VM_Version::vm_release(), 4674 VM_Version::vm_info_string()); 4675 st->cr(); 4676 4677 #if INCLUDE_SERVICES 4678 // Dump concurrent locks 4679 ConcurrentLocksDump concurrent_locks; 4680 if (print_concurrent_locks) { 4681 concurrent_locks.dump_at_safepoint(); 4682 } 4683 #endif // INCLUDE_SERVICES 4684 4685 ThreadsSMRSupport::print_info_on(st); 4686 st->cr(); 4687 4688 ALL_JAVA_THREADS(p) { 4689 ResourceMark rm; 4690 p->print_on(st, print_extended_info); 4691 if (print_stacks) { 4692 if (internal_format) { 4693 p->trace_stack(); 4694 } else { 4695 p->print_stack_on(st); 4696 } 4697 } 4698 st->cr(); 4699 #if INCLUDE_SERVICES 4700 if (print_concurrent_locks) { 4701 concurrent_locks.print_locks_on(p, st); 4702 } 4703 #endif // INCLUDE_SERVICES 4704 } 4705 4706 VMThread::vm_thread()->print_on(st); 4707 st->cr(); 4708 Universe::heap()->print_gc_threads_on(st); 4709 WatcherThread* wt = WatcherThread::watcher_thread(); 4710 if (wt != NULL) { 4711 wt->print_on(st); 4712 st->cr(); 4713 } 4714 4715 st->flush(); 4716 } 4717 4718 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4719 int buflen, bool* found_current) { 4720 if (this_thread != NULL) { 4721 bool is_current = (current == this_thread); 4722 *found_current = *found_current || is_current; 4723 st->print("%s", is_current ? "=>" : " "); 4724 4725 st->print(PTR_FORMAT, p2i(this_thread)); 4726 st->print(" "); 4727 this_thread->print_on_error(st, buf, buflen); 4728 st->cr(); 4729 } 4730 } 4731 4732 class PrintOnErrorClosure : public ThreadClosure { 4733 outputStream* _st; 4734 Thread* _current; 4735 char* _buf; 4736 int _buflen; 4737 bool* _found_current; 4738 public: 4739 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4740 int buflen, bool* found_current) : 4741 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4742 4743 virtual void do_thread(Thread* thread) { 4744 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4745 } 4746 }; 4747 4748 // Threads::print_on_error() is called by fatal error handler. It's possible 4749 // that VM is not at safepoint and/or current thread is inside signal handler. 4750 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4751 // memory (even in resource area), it might deadlock the error handler. 4752 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4753 int buflen) { 4754 ThreadsSMRSupport::print_info_on(st); 4755 st->cr(); 4756 4757 bool found_current = false; 4758 st->print_cr("Java Threads: ( => current thread )"); 4759 ALL_JAVA_THREADS(thread) { 4760 print_on_error(thread, st, current, buf, buflen, &found_current); 4761 } 4762 st->cr(); 4763 4764 st->print_cr("Other Threads:"); 4765 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4766 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4767 4768 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4769 Universe::heap()->gc_threads_do(&print_closure); 4770 4771 if (!found_current) { 4772 st->cr(); 4773 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4774 current->print_on_error(st, buf, buflen); 4775 st->cr(); 4776 } 4777 st->cr(); 4778 4779 st->print_cr("Threads with active compile tasks:"); 4780 print_threads_compiling(st, buf, buflen); 4781 } 4782 4783 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4784 ALL_JAVA_THREADS(thread) { 4785 if (thread->is_Compiler_thread()) { 4786 CompilerThread* ct = (CompilerThread*) thread; 4787 4788 // Keep task in local variable for NULL check. 4789 // ct->_task might be set to NULL by concurring compiler thread 4790 // because it completed the compilation. The task is never freed, 4791 // though, just returned to a free list. 4792 CompileTask* task = ct->task(); 4793 if (task != NULL) { 4794 thread->print_name_on_error(st, buf, buflen); 4795 st->print(" "); 4796 task->print(st, NULL, short_form, true); 4797 } 4798 } 4799 } 4800 } 4801 4802 4803 // Internal SpinLock and Mutex 4804 // Based on ParkEvent 4805 4806 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4807 // 4808 // We employ SpinLocks _only for low-contention, fixed-length 4809 // short-duration critical sections where we're concerned 4810 // about native mutex_t or HotSpot Mutex:: latency. 4811 // The mux construct provides a spin-then-block mutual exclusion 4812 // mechanism. 4813 // 4814 // Testing has shown that contention on the ListLock guarding gFreeList 4815 // is common. If we implement ListLock as a simple SpinLock it's common 4816 // for the JVM to devolve to yielding with little progress. This is true 4817 // despite the fact that the critical sections protected by ListLock are 4818 // extremely short. 4819 // 4820 // TODO-FIXME: ListLock should be of type SpinLock. 4821 // We should make this a 1st-class type, integrated into the lock 4822 // hierarchy as leaf-locks. Critically, the SpinLock structure 4823 // should have sufficient padding to avoid false-sharing and excessive 4824 // cache-coherency traffic. 4825 4826 4827 typedef volatile int SpinLockT; 4828 4829 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4830 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4831 return; // normal fast-path return 4832 } 4833 4834 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4835 int ctr = 0; 4836 int Yields = 0; 4837 for (;;) { 4838 while (*adr != 0) { 4839 ++ctr; 4840 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4841 if (Yields > 5) { 4842 os::naked_short_sleep(1); 4843 } else { 4844 os::naked_yield(); 4845 ++Yields; 4846 } 4847 } else { 4848 SpinPause(); 4849 } 4850 } 4851 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4852 } 4853 } 4854 4855 void Thread::SpinRelease(volatile int * adr) { 4856 assert(*adr != 0, "invariant"); 4857 OrderAccess::fence(); // guarantee at least release consistency. 4858 // Roach-motel semantics. 4859 // It's safe if subsequent LDs and STs float "up" into the critical section, 4860 // but prior LDs and STs within the critical section can't be allowed 4861 // to reorder or float past the ST that releases the lock. 4862 // Loads and stores in the critical section - which appear in program 4863 // order before the store that releases the lock - must also appear 4864 // before the store that releases the lock in memory visibility order. 4865 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4866 // the ST of 0 into the lock-word which releases the lock, so fence 4867 // more than covers this on all platforms. 4868 *adr = 0; 4869 } 4870 4871 // muxAcquire and muxRelease: 4872 // 4873 // * muxAcquire and muxRelease support a single-word lock-word construct. 4874 // The LSB of the word is set IFF the lock is held. 4875 // The remainder of the word points to the head of a singly-linked list 4876 // of threads blocked on the lock. 4877 // 4878 // * The current implementation of muxAcquire-muxRelease uses its own 4879 // dedicated Thread._MuxEvent instance. If we're interested in 4880 // minimizing the peak number of extant ParkEvent instances then 4881 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4882 // as certain invariants were satisfied. Specifically, care would need 4883 // to be taken with regards to consuming unpark() "permits". 4884 // A safe rule of thumb is that a thread would never call muxAcquire() 4885 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4886 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4887 // consume an unpark() permit intended for monitorenter, for instance. 4888 // One way around this would be to widen the restricted-range semaphore 4889 // implemented in park(). Another alternative would be to provide 4890 // multiple instances of the PlatformEvent() for each thread. One 4891 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4892 // 4893 // * Usage: 4894 // -- Only as leaf locks 4895 // -- for short-term locking only as muxAcquire does not perform 4896 // thread state transitions. 4897 // 4898 // Alternatives: 4899 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4900 // but with parking or spin-then-park instead of pure spinning. 4901 // * Use Taura-Oyama-Yonenzawa locks. 4902 // * It's possible to construct a 1-0 lock if we encode the lockword as 4903 // (List,LockByte). Acquire will CAS the full lockword while Release 4904 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4905 // acquiring threads use timers (ParkTimed) to detect and recover from 4906 // the stranding window. Thread/Node structures must be aligned on 256-byte 4907 // boundaries by using placement-new. 4908 // * Augment MCS with advisory back-link fields maintained with CAS(). 4909 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4910 // The validity of the backlinks must be ratified before we trust the value. 4911 // If the backlinks are invalid the exiting thread must back-track through the 4912 // the forward links, which are always trustworthy. 4913 // * Add a successor indication. The LockWord is currently encoded as 4914 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4915 // to provide the usual futile-wakeup optimization. 4916 // See RTStt for details. 4917 // 4918 4919 4920 const intptr_t LOCKBIT = 1; 4921 4922 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4923 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4924 if (w == 0) return; 4925 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4926 return; 4927 } 4928 4929 ParkEvent * const Self = Thread::current()->_MuxEvent; 4930 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4931 for (;;) { 4932 int its = (os::is_MP() ? 100 : 0) + 1; 4933 4934 // Optional spin phase: spin-then-park strategy 4935 while (--its >= 0) { 4936 w = *Lock; 4937 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4938 return; 4939 } 4940 } 4941 4942 Self->reset(); 4943 Self->OnList = intptr_t(Lock); 4944 // The following fence() isn't _strictly necessary as the subsequent 4945 // CAS() both serializes execution and ratifies the fetched *Lock value. 4946 OrderAccess::fence(); 4947 for (;;) { 4948 w = *Lock; 4949 if ((w & LOCKBIT) == 0) { 4950 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4951 Self->OnList = 0; // hygiene - allows stronger asserts 4952 return; 4953 } 4954 continue; // Interference -- *Lock changed -- Just retry 4955 } 4956 assert(w & LOCKBIT, "invariant"); 4957 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4958 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4959 } 4960 4961 while (Self->OnList != 0) { 4962 Self->park(); 4963 } 4964 } 4965 } 4966 4967 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4968 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4969 if (w == 0) return; 4970 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4971 return; 4972 } 4973 4974 ParkEvent * ReleaseAfter = NULL; 4975 if (ev == NULL) { 4976 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4977 } 4978 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4979 for (;;) { 4980 guarantee(ev->OnList == 0, "invariant"); 4981 int its = (os::is_MP() ? 100 : 0) + 1; 4982 4983 // Optional spin phase: spin-then-park strategy 4984 while (--its >= 0) { 4985 w = *Lock; 4986 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4987 if (ReleaseAfter != NULL) { 4988 ParkEvent::Release(ReleaseAfter); 4989 } 4990 return; 4991 } 4992 } 4993 4994 ev->reset(); 4995 ev->OnList = intptr_t(Lock); 4996 // The following fence() isn't _strictly necessary as the subsequent 4997 // CAS() both serializes execution and ratifies the fetched *Lock value. 4998 OrderAccess::fence(); 4999 for (;;) { 5000 w = *Lock; 5001 if ((w & LOCKBIT) == 0) { 5002 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 5003 ev->OnList = 0; 5004 // We call ::Release while holding the outer lock, thus 5005 // artificially lengthening the critical section. 5006 // Consider deferring the ::Release() until the subsequent unlock(), 5007 // after we've dropped the outer lock. 5008 if (ReleaseAfter != NULL) { 5009 ParkEvent::Release(ReleaseAfter); 5010 } 5011 return; 5012 } 5013 continue; // Interference -- *Lock changed -- Just retry 5014 } 5015 assert(w & LOCKBIT, "invariant"); 5016 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5017 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 5018 } 5019 5020 while (ev->OnList != 0) { 5021 ev->park(); 5022 } 5023 } 5024 } 5025 5026 // Release() must extract a successor from the list and then wake that thread. 5027 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5028 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5029 // Release() would : 5030 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5031 // (B) Extract a successor from the private list "in-hand" 5032 // (C) attempt to CAS() the residual back into *Lock over null. 5033 // If there were any newly arrived threads and the CAS() would fail. 5034 // In that case Release() would detach the RATs, re-merge the list in-hand 5035 // with the RATs and repeat as needed. Alternately, Release() might 5036 // detach and extract a successor, but then pass the residual list to the wakee. 5037 // The wakee would be responsible for reattaching and remerging before it 5038 // competed for the lock. 5039 // 5040 // Both "pop" and DMR are immune from ABA corruption -- there can be 5041 // multiple concurrent pushers, but only one popper or detacher. 5042 // This implementation pops from the head of the list. This is unfair, 5043 // but tends to provide excellent throughput as hot threads remain hot. 5044 // (We wake recently run threads first). 5045 // 5046 // All paths through muxRelease() will execute a CAS. 5047 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5048 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5049 // executed within the critical section are complete and globally visible before the 5050 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5051 void Thread::muxRelease(volatile intptr_t * Lock) { 5052 for (;;) { 5053 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 5054 assert(w & LOCKBIT, "invariant"); 5055 if (w == LOCKBIT) return; 5056 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5057 assert(List != NULL, "invariant"); 5058 assert(List->OnList == intptr_t(Lock), "invariant"); 5059 ParkEvent * const nxt = List->ListNext; 5060 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5061 5062 // The following CAS() releases the lock and pops the head element. 5063 // The CAS() also ratifies the previously fetched lock-word value. 5064 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 5065 continue; 5066 } 5067 List->OnList = 0; 5068 OrderAccess::fence(); 5069 List->unpark(); 5070 return; 5071 } 5072 } 5073 5074 5075 void Threads::verify() { 5076 ALL_JAVA_THREADS(p) { 5077 p->verify(); 5078 } 5079 VMThread* thread = VMThread::vm_thread(); 5080 if (thread != NULL) thread->verify(); 5081 }