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