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/jvmciCompiler.hpp" 121 #include "jvmci/jvmciRuntime.hpp" 122 #include "logging/logHandle.hpp" 123 #endif 124 #ifdef COMPILER1 125 #include "c1/c1_Compiler.hpp" 126 #endif 127 #ifdef COMPILER2 128 #include "opto/c2compiler.hpp" 129 #include "opto/idealGraphPrinter.hpp" 130 #endif 131 #if INCLUDE_RTM_OPT 132 #include "runtime/rtmLocking.hpp" 133 #endif 134 #if INCLUDE_JFR 135 #include "jfr/jfr.hpp" 136 #endif 137 138 // Initialization after module runtime initialization 139 void universe_post_module_init(); // must happen after call_initPhase2 140 141 #ifdef DTRACE_ENABLED 142 143 // Only bother with this argument setup if dtrace is available 144 145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) \ 149 { \ 150 ResourceMark rm(this); \ 151 int len = 0; \ 152 const char* name = (javathread)->get_thread_name(); \ 153 len = strlen(name); \ 154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 155 (char *) name, len, \ 156 java_lang_Thread::thread_id((javathread)->threadObj()), \ 157 (uintptr_t) (javathread)->osthread()->thread_id(), \ 158 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 159 } 160 161 #else // ndef DTRACE_ENABLED 162 163 #define DTRACE_THREAD_PROBE(probe, javathread) 164 165 #endif // ndef DTRACE_ENABLED 166 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY 168 // Current thread is maintained as a thread-local variable 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 170 #endif 171 172 // ======= Thread ======== 173 // Support for forcing alignment of thread objects for biased locking 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 175 if (UseBiasedLocking) { 176 const int alignment = markOopDesc::biased_lock_alignment; 177 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 179 : AllocateHeap(aligned_size, flags, CURRENT_PC, 180 AllocFailStrategy::RETURN_NULL); 181 void* aligned_addr = align_up(real_malloc_addr, alignment); 182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 184 "JavaThread alignment code overflowed allocated storage"); 185 if (aligned_addr != real_malloc_addr) { 186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 187 p2i(real_malloc_addr), 188 p2i(aligned_addr)); 189 } 190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 191 return aligned_addr; 192 } else { 193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 195 } 196 } 197 198 void Thread::operator delete(void* p) { 199 if (UseBiasedLocking) { 200 FreeHeap(((Thread*) p)->_real_malloc_address); 201 } else { 202 FreeHeap(p); 203 } 204 } 205 206 void JavaThread::smr_delete() { 207 if (_on_thread_list) { 208 ThreadsSMRSupport::smr_delete(this); 209 } else { 210 delete this; 211 } 212 } 213 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 215 // JavaThread 216 217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;) 218 219 Thread::Thread() { 220 221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;) 222 223 // stack and get_thread 224 set_stack_base(NULL); 225 set_stack_size(0); 226 set_self_raw_id(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 240 241 // This initial value ==> never claimed. 242 _oops_do_parity = 0; 243 _threads_hazard_ptr = NULL; 244 _threads_list_ptr = NULL; 245 _nested_threads_hazard_ptr_cnt = 0; 246 _rcu_counter = 0; 247 248 // the handle mark links itself to last_handle_mark 249 new HandleMark(this); 250 251 // plain initialization 252 debug_only(_owned_locks = NULL;) 253 debug_only(_allow_allocation_count = 0;) 254 NOT_PRODUCT(_allow_safepoint_count = 0;) 255 NOT_PRODUCT(_skip_gcalot = false;) 256 _jvmti_env_iteration_count = 0; 257 set_allocated_bytes(0); 258 _vm_operation_started_count = 0; 259 _vm_operation_completed_count = 0; 260 _current_pending_monitor = NULL; 261 _current_pending_monitor_is_from_java = true; 262 _current_waiting_monitor = NULL; 263 _num_nested_signal = 0; 264 omFreeList = NULL; 265 omFreeCount = 0; 266 omFreeProvision = 32; 267 omInUseList = NULL; 268 omInUseCount = 0; 269 270 #ifdef ASSERT 271 _visited_for_critical_count = false; 272 #endif 273 274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 275 Monitor::_safepoint_check_sometimes); 276 _suspend_flags = 0; 277 278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 279 _hashStateX = os::random(); 280 _hashStateY = 842502087; 281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 282 _hashStateW = 273326509; 283 284 _OnTrap = 0; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _SleepEvent = ParkEvent::Allocate(this); 297 _MuxEvent = ParkEvent::Allocate(this); 298 299 #ifdef CHECK_UNHANDLED_OOPS 300 if (CheckUnhandledOops) { 301 _unhandled_oops = new UnhandledOops(this); 302 } 303 #endif // CHECK_UNHANDLED_OOPS 304 #ifdef ASSERT 305 if (UseBiasedLocking) { 306 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 307 assert(this == _real_malloc_address || 308 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 309 "bug in forced alignment of thread objects"); 310 } 311 #endif // ASSERT 312 313 // Notify the barrier set that a thread is being created. The initial 314 // thread is created before the barrier set is available. The call to 315 // BarrierSet::on_thread_create() for this thread is therefore deferred 316 // to BarrierSet::set_barrier_set(). 317 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 318 if (barrier_set != NULL) { 319 barrier_set->on_thread_create(this); 320 } else { 321 // Only the main thread should be created before the barrier set 322 // and that happens just before Thread::current is set. No other thread 323 // can attach as the VM is not created yet, so they can't execute this code. 324 // If the main thread creates other threads before the barrier set that is an error. 325 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 326 } 327 } 328 329 void Thread::initialize_thread_current() { 330 #ifndef USE_LIBRARY_BASED_TLS_ONLY 331 assert(_thr_current == NULL, "Thread::current already initialized"); 332 _thr_current = this; 333 #endif 334 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 335 ThreadLocalStorage::set_thread(this); 336 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 337 } 338 339 void Thread::clear_thread_current() { 340 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 341 #ifndef USE_LIBRARY_BASED_TLS_ONLY 342 _thr_current = NULL; 343 #endif 344 ThreadLocalStorage::set_thread(NULL); 345 } 346 347 void Thread::record_stack_base_and_size() { 348 // Note: at this point, Thread object is not yet initialized. Do not rely on 349 // any members being initialized. Do not rely on Thread::current() being set. 350 // If possible, refrain from doing anything which may crash or assert since 351 // quite probably those crash dumps will be useless. 352 set_stack_base(os::current_stack_base()); 353 set_stack_size(os::current_stack_size()); 354 355 #ifdef SOLARIS 356 if (os::is_primordial_thread()) { 357 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 358 } 359 #endif 360 361 // Set stack limits after thread is initialized. 362 if (is_Java_thread()) { 363 ((JavaThread*) this)->set_stack_overflow_limit(); 364 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 365 } 366 } 367 368 #if INCLUDE_NMT 369 void Thread::register_thread_stack_with_NMT() { 370 MemTracker::record_thread_stack(stack_end(), stack_size()); 371 } 372 #endif // INCLUDE_NMT 373 374 void Thread::call_run() { 375 DEBUG_ONLY(_run_state = CALL_RUN;) 376 377 // At this point, Thread object should be fully initialized and 378 // Thread::current() should be set. 379 380 assert(Thread::current_or_null() != NULL, "current thread is unset"); 381 assert(Thread::current_or_null() == this, "current thread is wrong"); 382 383 // Perform common initialization actions 384 385 register_thread_stack_with_NMT(); 386 387 JFR_ONLY(Jfr::on_thread_start(this);) 388 389 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 390 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 391 os::current_thread_id(), p2i(stack_base() - stack_size()), 392 p2i(stack_base()), stack_size()/1024); 393 394 // Perform <ChildClass> initialization actions 395 DEBUG_ONLY(_run_state = PRE_RUN;) 396 this->pre_run(); 397 398 // Invoke <ChildClass>::run() 399 DEBUG_ONLY(_run_state = RUN;) 400 this->run(); 401 // Returned from <ChildClass>::run(). Thread finished. 402 403 // Perform common tear-down actions 404 405 assert(Thread::current_or_null() != NULL, "current thread is unset"); 406 assert(Thread::current_or_null() == this, "current thread is wrong"); 407 408 // Perform <ChildClass> tear-down actions 409 DEBUG_ONLY(_run_state = POST_RUN;) 410 this->post_run(); 411 412 // Note: at this point the thread object may already have deleted itself, 413 // so from here on do not dereference *this*. Not all thread types currently 414 // delete themselves when they terminate. But no thread should ever be deleted 415 // asynchronously with respect to its termination - that is what _run_state can 416 // be used to check. 417 418 assert(Thread::current_or_null() == NULL, "current thread still present"); 419 } 420 421 Thread::~Thread() { 422 423 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 424 // get started due to errors etc. Any active thread should at least reach post_run 425 // before it is deleted (usually in post_run()). 426 assert(_run_state == PRE_CALL_RUN || 427 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 428 "_run_state=%d", (int)_run_state); 429 430 // Notify the barrier set that a thread is being destroyed. Note that a barrier 431 // set might not be available if we encountered errors during bootstrapping. 432 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 433 if (barrier_set != NULL) { 434 barrier_set->on_thread_destroy(this); 435 } 436 437 // stack_base can be NULL if the thread is never started or exited before 438 // record_stack_base_and_size called. Although, we would like to ensure 439 // that all started threads do call record_stack_base_and_size(), there is 440 // not proper way to enforce that. 441 #if INCLUDE_NMT 442 if (_stack_base != NULL) { 443 MemTracker::release_thread_stack(stack_end(), stack_size()); 444 #ifdef ASSERT 445 set_stack_base(NULL); 446 #endif 447 } 448 #endif // INCLUDE_NMT 449 450 // deallocate data structures 451 delete resource_area(); 452 // since the handle marks are using the handle area, we have to deallocated the root 453 // handle mark before deallocating the thread's handle area, 454 assert(last_handle_mark() != NULL, "check we have an element"); 455 delete last_handle_mark(); 456 assert(last_handle_mark() == NULL, "check we have reached the end"); 457 458 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 459 // We NULL out the fields for good hygiene. 460 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 461 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 462 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 463 464 delete handle_area(); 465 delete metadata_handles(); 466 467 // SR_handler uses this as a termination indicator - 468 // needs to happen before os::free_thread() 469 delete _SR_lock; 470 _SR_lock = NULL; 471 472 // osthread() can be NULL, if creation of thread failed. 473 if (osthread() != NULL) os::free_thread(osthread()); 474 475 // Clear Thread::current if thread is deleting itself and it has not 476 // already been done. This must be done before the memory is deallocated. 477 // Needed to ensure JNI correctly detects non-attached threads. 478 if (this == Thread::current_or_null()) { 479 Thread::clear_thread_current(); 480 } 481 482 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 483 } 484 485 #ifdef ASSERT 486 // A JavaThread is considered "dangling" if it is not the current 487 // thread, has been added the Threads list, the system is not at a 488 // safepoint and the Thread is not "protected". 489 // 490 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 491 assert(!thread->is_Java_thread() || Thread::current() == thread || 492 !((JavaThread *) thread)->on_thread_list() || 493 SafepointSynchronize::is_at_safepoint() || 494 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 495 "possibility of dangling Thread pointer"); 496 } 497 #endif 498 499 ThreadPriority Thread::get_priority(const Thread* const thread) { 500 ThreadPriority priority; 501 // Can return an error! 502 (void)os::get_priority(thread, priority); 503 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 504 return priority; 505 } 506 507 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 508 debug_only(check_for_dangling_thread_pointer(thread);) 509 // Can return an error! 510 (void)os::set_priority(thread, priority); 511 } 512 513 514 void Thread::start(Thread* thread) { 515 // Start is different from resume in that its safety is guaranteed by context or 516 // being called from a Java method synchronized on the Thread object. 517 if (!DisableStartThread) { 518 if (thread->is_Java_thread()) { 519 // Initialize the thread state to RUNNABLE before starting this thread. 520 // Can not set it after the thread started because we do not know the 521 // exact thread state at that time. It could be in MONITOR_WAIT or 522 // in SLEEPING or some other state. 523 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 524 java_lang_Thread::RUNNABLE); 525 } 526 os::start_thread(thread); 527 } 528 } 529 530 // Enqueue a VM_Operation to do the job for us - sometime later 531 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 532 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 533 VMThread::execute(vm_stop); 534 } 535 536 537 // Check if an external suspend request has completed (or has been 538 // cancelled). Returns true if the thread is externally suspended and 539 // false otherwise. 540 // 541 // The bits parameter returns information about the code path through 542 // the routine. Useful for debugging: 543 // 544 // set in is_ext_suspend_completed(): 545 // 0x00000001 - routine was entered 546 // 0x00000010 - routine return false at end 547 // 0x00000100 - thread exited (return false) 548 // 0x00000200 - suspend request cancelled (return false) 549 // 0x00000400 - thread suspended (return true) 550 // 0x00001000 - thread is in a suspend equivalent state (return true) 551 // 0x00002000 - thread is native and walkable (return true) 552 // 0x00004000 - thread is native_trans and walkable (needed retry) 553 // 554 // set in wait_for_ext_suspend_completion(): 555 // 0x00010000 - routine was entered 556 // 0x00020000 - suspend request cancelled before loop (return false) 557 // 0x00040000 - thread suspended before loop (return true) 558 // 0x00080000 - suspend request cancelled in loop (return false) 559 // 0x00100000 - thread suspended in loop (return true) 560 // 0x00200000 - suspend not completed during retry loop (return false) 561 562 // Helper class for tracing suspend wait debug bits. 563 // 564 // 0x00000100 indicates that the target thread exited before it could 565 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 566 // 0x00080000 each indicate a cancelled suspend request so they don't 567 // count as wait failures either. 568 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 569 570 class TraceSuspendDebugBits : public StackObj { 571 private: 572 JavaThread * jt; 573 bool is_wait; 574 bool called_by_wait; // meaningful when !is_wait 575 uint32_t * bits; 576 577 public: 578 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 579 uint32_t *_bits) { 580 jt = _jt; 581 is_wait = _is_wait; 582 called_by_wait = _called_by_wait; 583 bits = _bits; 584 } 585 586 ~TraceSuspendDebugBits() { 587 if (!is_wait) { 588 #if 1 589 // By default, don't trace bits for is_ext_suspend_completed() calls. 590 // That trace is very chatty. 591 return; 592 #else 593 if (!called_by_wait) { 594 // If tracing for is_ext_suspend_completed() is enabled, then only 595 // trace calls to it from wait_for_ext_suspend_completion() 596 return; 597 } 598 #endif 599 } 600 601 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 602 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 603 MutexLocker ml(Threads_lock); // needed for get_thread_name() 604 ResourceMark rm; 605 606 tty->print_cr( 607 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 608 jt->get_thread_name(), *bits); 609 610 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 611 } 612 } 613 } 614 }; 615 #undef DEBUG_FALSE_BITS 616 617 618 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 619 uint32_t *bits) { 620 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 621 622 bool did_trans_retry = false; // only do thread_in_native_trans retry once 623 bool do_trans_retry; // flag to force the retry 624 625 *bits |= 0x00000001; 626 627 do { 628 do_trans_retry = false; 629 630 if (is_exiting()) { 631 // Thread is in the process of exiting. This is always checked 632 // first to reduce the risk of dereferencing a freed JavaThread. 633 *bits |= 0x00000100; 634 return false; 635 } 636 637 if (!is_external_suspend()) { 638 // Suspend request is cancelled. This is always checked before 639 // is_ext_suspended() to reduce the risk of a rogue resume 640 // confusing the thread that made the suspend request. 641 *bits |= 0x00000200; 642 return false; 643 } 644 645 if (is_ext_suspended()) { 646 // thread is suspended 647 *bits |= 0x00000400; 648 return true; 649 } 650 651 // Now that we no longer do hard suspends of threads running 652 // native code, the target thread can be changing thread state 653 // while we are in this routine: 654 // 655 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 656 // 657 // We save a copy of the thread state as observed at this moment 658 // and make our decision about suspend completeness based on the 659 // copy. This closes the race where the thread state is seen as 660 // _thread_in_native_trans in the if-thread_blocked check, but is 661 // seen as _thread_blocked in if-thread_in_native_trans check. 662 JavaThreadState save_state = thread_state(); 663 664 if (save_state == _thread_blocked && is_suspend_equivalent()) { 665 // If the thread's state is _thread_blocked and this blocking 666 // condition is known to be equivalent to a suspend, then we can 667 // consider the thread to be externally suspended. This means that 668 // the code that sets _thread_blocked has been modified to do 669 // self-suspension if the blocking condition releases. We also 670 // used to check for CONDVAR_WAIT here, but that is now covered by 671 // the _thread_blocked with self-suspension check. 672 // 673 // Return true since we wouldn't be here unless there was still an 674 // external suspend request. 675 *bits |= 0x00001000; 676 return true; 677 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 678 // Threads running native code will self-suspend on native==>VM/Java 679 // transitions. If its stack is walkable (should always be the case 680 // unless this function is called before the actual java_suspend() 681 // call), then the wait is done. 682 *bits |= 0x00002000; 683 return true; 684 } else if (!called_by_wait && !did_trans_retry && 685 save_state == _thread_in_native_trans && 686 frame_anchor()->walkable()) { 687 // The thread is transitioning from thread_in_native to another 688 // thread state. check_safepoint_and_suspend_for_native_trans() 689 // will force the thread to self-suspend. If it hasn't gotten 690 // there yet we may have caught the thread in-between the native 691 // code check above and the self-suspend. Lucky us. If we were 692 // called by wait_for_ext_suspend_completion(), then it 693 // will be doing the retries so we don't have to. 694 // 695 // Since we use the saved thread state in the if-statement above, 696 // there is a chance that the thread has already transitioned to 697 // _thread_blocked by the time we get here. In that case, we will 698 // make a single unnecessary pass through the logic below. This 699 // doesn't hurt anything since we still do the trans retry. 700 701 *bits |= 0x00004000; 702 703 // Once the thread leaves thread_in_native_trans for another 704 // thread state, we break out of this retry loop. We shouldn't 705 // need this flag to prevent us from getting back here, but 706 // sometimes paranoia is good. 707 did_trans_retry = true; 708 709 // We wait for the thread to transition to a more usable state. 710 for (int i = 1; i <= SuspendRetryCount; i++) { 711 // We used to do an "os::yield_all(i)" call here with the intention 712 // that yielding would increase on each retry. However, the parameter 713 // is ignored on Linux which means the yield didn't scale up. Waiting 714 // on the SR_lock below provides a much more predictable scale up for 715 // the delay. It also provides a simple/direct point to check for any 716 // safepoint requests from the VMThread 717 718 // temporarily drops SR_lock while doing wait with safepoint check 719 // (if we're a JavaThread - the WatcherThread can also call this) 720 // and increase delay with each retry 721 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 722 723 // check the actual thread state instead of what we saved above 724 if (thread_state() != _thread_in_native_trans) { 725 // the thread has transitioned to another thread state so 726 // try all the checks (except this one) one more time. 727 do_trans_retry = true; 728 break; 729 } 730 } // end retry loop 731 732 733 } 734 } while (do_trans_retry); 735 736 *bits |= 0x00000010; 737 return false; 738 } 739 740 // Wait for an external suspend request to complete (or be cancelled). 741 // Returns true if the thread is externally suspended and false otherwise. 742 // 743 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 744 uint32_t *bits) { 745 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 746 false /* !called_by_wait */, bits); 747 748 // local flag copies to minimize SR_lock hold time 749 bool is_suspended; 750 bool pending; 751 uint32_t reset_bits; 752 753 // set a marker so is_ext_suspend_completed() knows we are the caller 754 *bits |= 0x00010000; 755 756 // We use reset_bits to reinitialize the bits value at the top of 757 // each retry loop. This allows the caller to make use of any 758 // unused bits for their own marking purposes. 759 reset_bits = *bits; 760 761 { 762 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 763 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 764 delay, bits); 765 pending = is_external_suspend(); 766 } 767 // must release SR_lock to allow suspension to complete 768 769 if (!pending) { 770 // A cancelled suspend request is the only false return from 771 // is_ext_suspend_completed() that keeps us from entering the 772 // retry loop. 773 *bits |= 0x00020000; 774 return false; 775 } 776 777 if (is_suspended) { 778 *bits |= 0x00040000; 779 return true; 780 } 781 782 for (int i = 1; i <= retries; i++) { 783 *bits = reset_bits; // reinit to only track last retry 784 785 // We used to do an "os::yield_all(i)" call here with the intention 786 // that yielding would increase on each retry. However, the parameter 787 // is ignored on Linux which means the yield didn't scale up. Waiting 788 // on the SR_lock below provides a much more predictable scale up for 789 // the delay. It also provides a simple/direct point to check for any 790 // safepoint requests from the VMThread 791 792 { 793 MutexLocker ml(SR_lock()); 794 // wait with safepoint check (if we're a JavaThread - the WatcherThread 795 // can also call this) and increase delay with each retry 796 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 797 798 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 799 delay, bits); 800 801 // It is possible for the external suspend request to be cancelled 802 // (by a resume) before the actual suspend operation is completed. 803 // Refresh our local copy to see if we still need to wait. 804 pending = is_external_suspend(); 805 } 806 807 if (!pending) { 808 // A cancelled suspend request is the only false return from 809 // is_ext_suspend_completed() that keeps us from staying in the 810 // retry loop. 811 *bits |= 0x00080000; 812 return false; 813 } 814 815 if (is_suspended) { 816 *bits |= 0x00100000; 817 return true; 818 } 819 } // end retry loop 820 821 // thread did not suspend after all our retries 822 *bits |= 0x00200000; 823 return false; 824 } 825 826 // Called from API entry points which perform stack walking. If the 827 // associated JavaThread is the current thread, then wait_for_suspend 828 // is not used. Otherwise, it determines if we should wait for the 829 // "other" thread to complete external suspension. (NOTE: in future 830 // releases the suspension mechanism should be reimplemented so this 831 // is not necessary.) 832 // 833 bool 834 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 835 if (this != JavaThread::current()) { 836 // "other" threads require special handling. 837 if (wait_for_suspend) { 838 // We are allowed to wait for the external suspend to complete 839 // so give the other thread a chance to get suspended. 840 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 841 SuspendRetryDelay, bits)) { 842 // Didn't make it so let the caller know. 843 return false; 844 } 845 } 846 // We aren't allowed to wait for the external suspend to complete 847 // so if the other thread isn't externally suspended we need to 848 // let the caller know. 849 else if (!is_ext_suspend_completed_with_lock(bits)) { 850 return false; 851 } 852 } 853 854 return true; 855 } 856 857 #ifndef PRODUCT 858 void JavaThread::record_jump(address target, address instr, const char* file, 859 int line) { 860 861 // This should not need to be atomic as the only way for simultaneous 862 // updates is via interrupts. Even then this should be rare or non-existent 863 // and we don't care that much anyway. 864 865 int index = _jmp_ring_index; 866 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 867 _jmp_ring[index]._target = (intptr_t) target; 868 _jmp_ring[index]._instruction = (intptr_t) instr; 869 _jmp_ring[index]._file = file; 870 _jmp_ring[index]._line = line; 871 } 872 #endif // PRODUCT 873 874 void Thread::interrupt(Thread* thread) { 875 debug_only(check_for_dangling_thread_pointer(thread);) 876 os::interrupt(thread); 877 } 878 879 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 880 debug_only(check_for_dangling_thread_pointer(thread);) 881 // Note: If clear_interrupted==false, this simply fetches and 882 // returns the value of the field osthread()->interrupted(). 883 return os::is_interrupted(thread, clear_interrupted); 884 } 885 886 887 // GC Support 888 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 889 int thread_parity = _oops_do_parity; 890 if (thread_parity != strong_roots_parity) { 891 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 892 if (res == thread_parity) { 893 return true; 894 } else { 895 guarantee(res == strong_roots_parity, "Or else what?"); 896 return false; 897 } 898 } 899 return false; 900 } 901 902 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 903 active_handles()->oops_do(f); 904 // Do oop for ThreadShadow 905 f->do_oop((oop*)&_pending_exception); 906 handle_area()->oops_do(f); 907 908 // We scan thread local monitor lists here, and the remaining global 909 // monitors in ObjectSynchronizer::oops_do(). 910 ObjectSynchronizer::thread_local_used_oops_do(this, f); 911 } 912 913 void Thread::metadata_handles_do(void f(Metadata*)) { 914 // Only walk the Handles in Thread. 915 if (metadata_handles() != NULL) { 916 for (int i = 0; i< metadata_handles()->length(); i++) { 917 f(metadata_handles()->at(i)); 918 } 919 } 920 } 921 922 void Thread::print_on(outputStream* st, bool print_extended_info) const { 923 // get_priority assumes osthread initialized 924 if (osthread() != NULL) { 925 int os_prio; 926 if (os::get_native_priority(this, &os_prio) == OS_OK) { 927 st->print("os_prio=%d ", os_prio); 928 } 929 930 st->print("cpu=%.2fms ", 931 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 932 ); 933 st->print("elapsed=%.2fs ", 934 _statistical_info.getElapsedTime() / 1000.0 935 ); 936 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 937 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 938 st->print("allocated=" SIZE_FORMAT "%s ", 939 byte_size_in_proper_unit(allocated_bytes), 940 proper_unit_for_byte_size(allocated_bytes) 941 ); 942 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 943 } 944 945 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 946 osthread()->print_on(st); 947 } 948 ThreadsSMRSupport::print_info_on(this, st); 949 st->print(" "); 950 debug_only(if (WizardMode) print_owned_locks_on(st);) 951 } 952 953 // Thread::print_on_error() is called by fatal error handler. Don't use 954 // any lock or allocate memory. 955 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 956 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 957 958 if (is_VM_thread()) { st->print("VMThread"); } 959 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 960 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 961 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 962 else { st->print("Thread"); } 963 964 if (is_Named_thread()) { 965 st->print(" \"%s\"", name()); 966 } 967 968 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 969 p2i(stack_end()), p2i(stack_base())); 970 971 if (osthread()) { 972 st->print(" [id=%d]", osthread()->thread_id()); 973 } 974 975 ThreadsSMRSupport::print_info_on(this, st); 976 } 977 978 void Thread::print_value_on(outputStream* st) const { 979 if (is_Named_thread()) { 980 st->print(" \"%s\" ", name()); 981 } 982 st->print(INTPTR_FORMAT, p2i(this)); // print address 983 } 984 985 #ifdef ASSERT 986 void Thread::print_owned_locks_on(outputStream* st) const { 987 Monitor *cur = _owned_locks; 988 if (cur == NULL) { 989 st->print(" (no locks) "); 990 } else { 991 st->print_cr(" Locks owned:"); 992 while (cur) { 993 cur->print_on(st); 994 cur = cur->next(); 995 } 996 } 997 } 998 999 static int ref_use_count = 0; 1000 1001 bool Thread::owns_locks_but_compiled_lock() const { 1002 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1003 if (cur != Compile_lock) return true; 1004 } 1005 return false; 1006 } 1007 1008 1009 #endif 1010 1011 #ifndef PRODUCT 1012 1013 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 1014 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 1015 // no locks which allow_vm_block's are held 1016 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 1017 // Check if current thread is allowed to block at a safepoint 1018 if (!(_allow_safepoint_count == 0)) { 1019 fatal("Possible safepoint reached by thread that does not allow it"); 1020 } 1021 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 1022 fatal("LEAF method calling lock?"); 1023 } 1024 1025 #ifdef ASSERT 1026 if (potential_vm_operation && is_Java_thread() 1027 && !Universe::is_bootstrapping()) { 1028 // Make sure we do not hold any locks that the VM thread also uses. 1029 // This could potentially lead to deadlocks 1030 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1031 // Threads_lock is special, since the safepoint synchronization will not start before this is 1032 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1033 // since it is used to transfer control between JavaThreads and the VMThread 1034 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1035 if ((cur->allow_vm_block() && 1036 cur != Threads_lock && 1037 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1038 cur != VMOperationRequest_lock && 1039 cur != VMOperationQueue_lock) || 1040 cur->rank() == Mutex::special) { 1041 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1042 } 1043 } 1044 } 1045 1046 if (GCALotAtAllSafepoints) { 1047 // We could enter a safepoint here and thus have a gc 1048 InterfaceSupport::check_gc_alot(); 1049 } 1050 #endif 1051 } 1052 #endif 1053 1054 bool Thread::is_in_stack(address adr) const { 1055 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1056 address end = os::current_stack_pointer(); 1057 // Allow non Java threads to call this without stack_base 1058 if (_stack_base == NULL) return true; 1059 if (stack_base() >= adr && adr >= end) return true; 1060 1061 return false; 1062 } 1063 1064 bool Thread::is_in_usable_stack(address adr) const { 1065 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1066 size_t usable_stack_size = _stack_size - stack_guard_size; 1067 1068 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1069 } 1070 1071 1072 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1073 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1074 // used for compilation in the future. If that change is made, the need for these methods 1075 // should be revisited, and they should be removed if possible. 1076 1077 bool Thread::is_lock_owned(address adr) const { 1078 return on_local_stack(adr); 1079 } 1080 1081 bool Thread::set_as_starting_thread() { 1082 assert(_starting_thread == NULL, "already initialized: " 1083 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1084 // NOTE: this must be called inside the main thread. 1085 DEBUG_ONLY(_starting_thread = this;) 1086 return os::create_main_thread((JavaThread*)this); 1087 } 1088 1089 static void initialize_class(Symbol* class_name, TRAPS) { 1090 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1091 InstanceKlass::cast(klass)->initialize(CHECK); 1092 } 1093 1094 1095 // Creates the initial ThreadGroup 1096 static Handle create_initial_thread_group(TRAPS) { 1097 Handle system_instance = JavaCalls::construct_new_instance( 1098 SystemDictionary::ThreadGroup_klass(), 1099 vmSymbols::void_method_signature(), 1100 CHECK_NH); 1101 Universe::set_system_thread_group(system_instance()); 1102 1103 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1104 Handle main_instance = JavaCalls::construct_new_instance( 1105 SystemDictionary::ThreadGroup_klass(), 1106 vmSymbols::threadgroup_string_void_signature(), 1107 system_instance, 1108 string, 1109 CHECK_NH); 1110 return main_instance; 1111 } 1112 1113 // Creates the initial Thread 1114 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1115 TRAPS) { 1116 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1117 assert(ik->is_initialized(), "must be"); 1118 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1119 1120 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1121 // constructor calls Thread.current(), which must be set here for the 1122 // initial thread. 1123 java_lang_Thread::set_thread(thread_oop(), thread); 1124 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1125 thread->set_threadObj(thread_oop()); 1126 1127 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1128 1129 JavaValue result(T_VOID); 1130 JavaCalls::call_special(&result, thread_oop, 1131 ik, 1132 vmSymbols::object_initializer_name(), 1133 vmSymbols::threadgroup_string_void_signature(), 1134 thread_group, 1135 string, 1136 CHECK_NULL); 1137 return thread_oop(); 1138 } 1139 1140 char java_runtime_name[128] = ""; 1141 char java_runtime_version[128] = ""; 1142 1143 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1144 static const char* get_java_runtime_name(TRAPS) { 1145 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1146 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1147 fieldDescriptor fd; 1148 bool found = k != NULL && 1149 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1150 vmSymbols::string_signature(), &fd); 1151 if (found) { 1152 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1153 if (name_oop == NULL) { 1154 return NULL; 1155 } 1156 const char* name = java_lang_String::as_utf8_string(name_oop, 1157 java_runtime_name, 1158 sizeof(java_runtime_name)); 1159 return name; 1160 } else { 1161 return NULL; 1162 } 1163 } 1164 1165 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1166 static const char* get_java_runtime_version(TRAPS) { 1167 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1168 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1169 fieldDescriptor fd; 1170 bool found = k != NULL && 1171 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1172 vmSymbols::string_signature(), &fd); 1173 if (found) { 1174 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1175 if (name_oop == NULL) { 1176 return NULL; 1177 } 1178 const char* name = java_lang_String::as_utf8_string(name_oop, 1179 java_runtime_version, 1180 sizeof(java_runtime_version)); 1181 return name; 1182 } else { 1183 return NULL; 1184 } 1185 } 1186 1187 // General purpose hook into Java code, run once when the VM is initialized. 1188 // The Java library method itself may be changed independently from the VM. 1189 static void call_postVMInitHook(TRAPS) { 1190 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1191 if (klass != NULL) { 1192 JavaValue result(T_VOID); 1193 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1194 vmSymbols::void_method_signature(), 1195 CHECK); 1196 } 1197 } 1198 1199 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1200 bool daemon, TRAPS) { 1201 assert(thread_group.not_null(), "thread group should be specified"); 1202 assert(threadObj() == NULL, "should only create Java thread object once"); 1203 1204 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1205 assert(ik->is_initialized(), "must be"); 1206 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1207 1208 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1209 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1210 // constructor calls Thread.current(), which must be set here. 1211 java_lang_Thread::set_thread(thread_oop(), this); 1212 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1213 set_threadObj(thread_oop()); 1214 1215 JavaValue result(T_VOID); 1216 if (thread_name != NULL) { 1217 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1218 // Thread gets assigned specified name and null target 1219 JavaCalls::call_special(&result, 1220 thread_oop, 1221 ik, 1222 vmSymbols::object_initializer_name(), 1223 vmSymbols::threadgroup_string_void_signature(), 1224 thread_group, 1225 name, 1226 THREAD); 1227 } else { 1228 // Thread gets assigned name "Thread-nnn" and null target 1229 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1230 JavaCalls::call_special(&result, 1231 thread_oop, 1232 ik, 1233 vmSymbols::object_initializer_name(), 1234 vmSymbols::threadgroup_runnable_void_signature(), 1235 thread_group, 1236 Handle(), 1237 THREAD); 1238 } 1239 1240 1241 if (daemon) { 1242 java_lang_Thread::set_daemon(thread_oop()); 1243 } 1244 1245 if (HAS_PENDING_EXCEPTION) { 1246 return; 1247 } 1248 1249 Klass* group = SystemDictionary::ThreadGroup_klass(); 1250 Handle threadObj(THREAD, this->threadObj()); 1251 1252 JavaCalls::call_special(&result, 1253 thread_group, 1254 group, 1255 vmSymbols::add_method_name(), 1256 vmSymbols::thread_void_signature(), 1257 threadObj, // Arg 1 1258 THREAD); 1259 } 1260 1261 // List of all NonJavaThreads and safe iteration over that list. 1262 1263 class NonJavaThread::List { 1264 public: 1265 NonJavaThread* volatile _head; 1266 SingleWriterSynchronizer _protect; 1267 1268 List() : _head(NULL), _protect() {} 1269 }; 1270 1271 NonJavaThread::List NonJavaThread::_the_list; 1272 1273 NonJavaThread::Iterator::Iterator() : 1274 _protect_enter(_the_list._protect.enter()), 1275 _current(OrderAccess::load_acquire(&_the_list._head)) 1276 {} 1277 1278 NonJavaThread::Iterator::~Iterator() { 1279 _the_list._protect.exit(_protect_enter); 1280 } 1281 1282 void NonJavaThread::Iterator::step() { 1283 assert(!end(), "precondition"); 1284 _current = OrderAccess::load_acquire(&_current->_next); 1285 } 1286 1287 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1288 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1289 } 1290 1291 NonJavaThread::~NonJavaThread() { } 1292 1293 void NonJavaThread::add_to_the_list() { 1294 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1295 _next = _the_list._head; 1296 OrderAccess::release_store(&_the_list._head, this); 1297 } 1298 1299 void NonJavaThread::remove_from_the_list() { 1300 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1301 NonJavaThread* volatile* p = &_the_list._head; 1302 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1303 if (t == this) { 1304 *p = this->_next; 1305 // Wait for any in-progress iterators. Concurrent synchronize is 1306 // not allowed, so do it while holding the list lock. 1307 _the_list._protect.synchronize(); 1308 break; 1309 } 1310 } 1311 } 1312 1313 void NonJavaThread::pre_run() { 1314 assert(BarrierSet::barrier_set() != NULL, "invariant"); 1315 add_to_the_list(); 1316 1317 // This is slightly odd in that NamedThread is a subclass, but 1318 // in fact name() is defined in Thread 1319 assert(this->name() != NULL, "thread name was not set before it was started"); 1320 this->set_native_thread_name(this->name()); 1321 } 1322 1323 void NonJavaThread::post_run() { 1324 JFR_ONLY(Jfr::on_thread_exit(this);) 1325 remove_from_the_list(); 1326 // Ensure thread-local-storage is cleared before termination. 1327 Thread::clear_thread_current(); 1328 } 1329 1330 // NamedThread -- non-JavaThread subclasses with multiple 1331 // uniquely named instances should derive from this. 1332 NamedThread::NamedThread() : 1333 NonJavaThread(), 1334 _name(NULL), 1335 _processed_thread(NULL), 1336 _gc_id(GCId::undefined()) 1337 {} 1338 1339 NamedThread::~NamedThread() { 1340 if (_name != NULL) { 1341 FREE_C_HEAP_ARRAY(char, _name); 1342 _name = NULL; 1343 } 1344 } 1345 1346 void NamedThread::set_name(const char* format, ...) { 1347 guarantee(_name == NULL, "Only get to set name once."); 1348 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1349 guarantee(_name != NULL, "alloc failure"); 1350 va_list ap; 1351 va_start(ap, format); 1352 jio_vsnprintf(_name, max_name_len, format, ap); 1353 va_end(ap); 1354 } 1355 1356 void NamedThread::print_on(outputStream* st) const { 1357 st->print("\"%s\" ", name()); 1358 Thread::print_on(st); 1359 st->cr(); 1360 } 1361 1362 1363 // ======= WatcherThread ======== 1364 1365 // The watcher thread exists to simulate timer interrupts. It should 1366 // be replaced by an abstraction over whatever native support for 1367 // timer interrupts exists on the platform. 1368 1369 WatcherThread* WatcherThread::_watcher_thread = NULL; 1370 bool WatcherThread::_startable = false; 1371 volatile bool WatcherThread::_should_terminate = false; 1372 1373 WatcherThread::WatcherThread() : NonJavaThread() { 1374 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1375 if (os::create_thread(this, os::watcher_thread)) { 1376 _watcher_thread = this; 1377 1378 // Set the watcher thread to the highest OS priority which should not be 1379 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1380 // is created. The only normal thread using this priority is the reference 1381 // handler thread, which runs for very short intervals only. 1382 // If the VMThread's priority is not lower than the WatcherThread profiling 1383 // will be inaccurate. 1384 os::set_priority(this, MaxPriority); 1385 if (!DisableStartThread) { 1386 os::start_thread(this); 1387 } 1388 } 1389 } 1390 1391 int WatcherThread::sleep() const { 1392 // The WatcherThread does not participate in the safepoint protocol 1393 // for the PeriodicTask_lock because it is not a JavaThread. 1394 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1395 1396 if (_should_terminate) { 1397 // check for termination before we do any housekeeping or wait 1398 return 0; // we did not sleep. 1399 } 1400 1401 // remaining will be zero if there are no tasks, 1402 // causing the WatcherThread to sleep until a task is 1403 // enrolled 1404 int remaining = PeriodicTask::time_to_wait(); 1405 int time_slept = 0; 1406 1407 // we expect this to timeout - we only ever get unparked when 1408 // we should terminate or when a new task has been enrolled 1409 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1410 1411 jlong time_before_loop = os::javaTimeNanos(); 1412 1413 while (true) { 1414 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1415 remaining); 1416 jlong now = os::javaTimeNanos(); 1417 1418 if (remaining == 0) { 1419 // if we didn't have any tasks we could have waited for a long time 1420 // consider the time_slept zero and reset time_before_loop 1421 time_slept = 0; 1422 time_before_loop = now; 1423 } else { 1424 // need to recalculate since we might have new tasks in _tasks 1425 time_slept = (int) ((now - time_before_loop) / 1000000); 1426 } 1427 1428 // Change to task list or spurious wakeup of some kind 1429 if (timedout || _should_terminate) { 1430 break; 1431 } 1432 1433 remaining = PeriodicTask::time_to_wait(); 1434 if (remaining == 0) { 1435 // Last task was just disenrolled so loop around and wait until 1436 // another task gets enrolled 1437 continue; 1438 } 1439 1440 remaining -= time_slept; 1441 if (remaining <= 0) { 1442 break; 1443 } 1444 } 1445 1446 return time_slept; 1447 } 1448 1449 void WatcherThread::run() { 1450 assert(this == watcher_thread(), "just checking"); 1451 1452 this->set_active_handles(JNIHandleBlock::allocate_block()); 1453 while (true) { 1454 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1455 assert(watcher_thread() == this, "thread consistency check"); 1456 1457 // Calculate how long it'll be until the next PeriodicTask work 1458 // should be done, and sleep that amount of time. 1459 int time_waited = sleep(); 1460 1461 if (VMError::is_error_reported()) { 1462 // A fatal error has happened, the error handler(VMError::report_and_die) 1463 // should abort JVM after creating an error log file. However in some 1464 // rare cases, the error handler itself might deadlock. Here periodically 1465 // check for error reporting timeouts, and if it happens, just proceed to 1466 // abort the VM. 1467 1468 // This code is in WatcherThread because WatcherThread wakes up 1469 // periodically so the fatal error handler doesn't need to do anything; 1470 // also because the WatcherThread is less likely to crash than other 1471 // threads. 1472 1473 for (;;) { 1474 // Note: we use naked sleep in this loop because we want to avoid using 1475 // any kind of VM infrastructure which may be broken at this point. 1476 if (VMError::check_timeout()) { 1477 // We hit error reporting timeout. Error reporting was interrupted and 1478 // will be wrapping things up now (closing files etc). Give it some more 1479 // time, then quit the VM. 1480 os::naked_short_sleep(200); 1481 // Print a message to stderr. 1482 fdStream err(defaultStream::output_fd()); 1483 err.print_raw_cr("# [ timer expired, abort... ]"); 1484 // skip atexit/vm_exit/vm_abort hooks 1485 os::die(); 1486 } 1487 1488 // Wait a second, then recheck for timeout. 1489 os::naked_short_sleep(999); 1490 } 1491 } 1492 1493 if (_should_terminate) { 1494 // check for termination before posting the next tick 1495 break; 1496 } 1497 1498 PeriodicTask::real_time_tick(time_waited); 1499 } 1500 1501 // Signal that it is terminated 1502 { 1503 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1504 _watcher_thread = NULL; 1505 Terminator_lock->notify(); 1506 } 1507 } 1508 1509 void WatcherThread::start() { 1510 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1511 1512 if (watcher_thread() == NULL && _startable) { 1513 _should_terminate = false; 1514 // Create the single instance of WatcherThread 1515 new WatcherThread(); 1516 } 1517 } 1518 1519 void WatcherThread::make_startable() { 1520 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1521 _startable = true; 1522 } 1523 1524 void WatcherThread::stop() { 1525 { 1526 // Follow normal safepoint aware lock enter protocol since the 1527 // WatcherThread is stopped by another JavaThread. 1528 MutexLocker ml(PeriodicTask_lock); 1529 _should_terminate = true; 1530 1531 WatcherThread* watcher = watcher_thread(); 1532 if (watcher != NULL) { 1533 // unpark the WatcherThread so it can see that it should terminate 1534 watcher->unpark(); 1535 } 1536 } 1537 1538 MutexLocker mu(Terminator_lock); 1539 1540 while (watcher_thread() != NULL) { 1541 // This wait should make safepoint checks, wait without a timeout, 1542 // and wait as a suspend-equivalent condition. 1543 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1544 Mutex::_as_suspend_equivalent_flag); 1545 } 1546 } 1547 1548 void WatcherThread::unpark() { 1549 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1550 PeriodicTask_lock->notify(); 1551 } 1552 1553 void WatcherThread::print_on(outputStream* st) const { 1554 st->print("\"%s\" ", name()); 1555 Thread::print_on(st); 1556 st->cr(); 1557 } 1558 1559 // ======= JavaThread ======== 1560 1561 #if INCLUDE_JVMCI 1562 1563 jlong* JavaThread::_jvmci_old_thread_counters; 1564 1565 bool jvmci_counters_include(JavaThread* thread) { 1566 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1567 } 1568 1569 void JavaThread::collect_counters(typeArrayOop array) { 1570 if (JVMCICounterSize > 0) { 1571 JavaThreadIteratorWithHandle jtiwh; 1572 for (int i = 0; i < array->length(); i++) { 1573 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1574 } 1575 for (; JavaThread *tp = jtiwh.next(); ) { 1576 if (jvmci_counters_include(tp)) { 1577 for (int i = 0; i < array->length(); i++) { 1578 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1579 } 1580 } 1581 } 1582 } 1583 } 1584 1585 #endif // INCLUDE_JVMCI 1586 1587 // A JavaThread is a normal Java thread 1588 1589 void JavaThread::initialize() { 1590 // Initialize fields 1591 1592 set_saved_exception_pc(NULL); 1593 set_threadObj(NULL); 1594 _anchor.clear(); 1595 set_entry_point(NULL); 1596 set_jni_functions(jni_functions()); 1597 set_callee_target(NULL); 1598 set_vm_result(NULL); 1599 set_vm_result_2(NULL); 1600 set_vframe_array_head(NULL); 1601 set_vframe_array_last(NULL); 1602 set_deferred_locals(NULL); 1603 set_deopt_mark(NULL); 1604 set_deopt_compiled_method(NULL); 1605 clear_must_deopt_id(); 1606 set_monitor_chunks(NULL); 1607 set_next(NULL); 1608 _on_thread_list = false; 1609 set_thread_state(_thread_new); 1610 _terminated = _not_terminated; 1611 _array_for_gc = NULL; 1612 _suspend_equivalent = false; 1613 _in_deopt_handler = 0; 1614 _doing_unsafe_access = false; 1615 _stack_guard_state = stack_guard_unused; 1616 #if INCLUDE_JVMCI 1617 _pending_monitorenter = false; 1618 _pending_deoptimization = -1; 1619 _pending_failed_speculation = 0; 1620 _pending_transfer_to_interpreter = false; 1621 _adjusting_comp_level = false; 1622 _in_retryable_allocation = false; 1623 _jvmci._alternate_call_target = NULL; 1624 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1625 if (JVMCICounterSize > 0) { 1626 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1627 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1628 } else { 1629 _jvmci_counters = NULL; 1630 } 1631 #endif // INCLUDE_JVMCI 1632 _reserved_stack_activation = NULL; // stack base not known yet 1633 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1634 _exception_pc = 0; 1635 _exception_handler_pc = 0; 1636 _is_method_handle_return = 0; 1637 _jvmti_thread_state= NULL; 1638 _should_post_on_exceptions_flag = JNI_FALSE; 1639 _interp_only_mode = 0; 1640 _special_runtime_exit_condition = _no_async_condition; 1641 _pending_async_exception = NULL; 1642 _thread_stat = NULL; 1643 _thread_stat = new ThreadStatistics(); 1644 _blocked_on_compilation = false; 1645 _jni_active_critical = 0; 1646 _pending_jni_exception_check_fn = NULL; 1647 _do_not_unlock_if_synchronized = false; 1648 _cached_monitor_info = NULL; 1649 _parker = Parker::Allocate(this); 1650 1651 #ifndef PRODUCT 1652 _jmp_ring_index = 0; 1653 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1654 record_jump(NULL, NULL, NULL, 0); 1655 } 1656 #endif // PRODUCT 1657 1658 // Setup safepoint state info for this thread 1659 ThreadSafepointState::create(this); 1660 1661 debug_only(_java_call_counter = 0); 1662 1663 // JVMTI PopFrame support 1664 _popframe_condition = popframe_inactive; 1665 _popframe_preserved_args = NULL; 1666 _popframe_preserved_args_size = 0; 1667 _frames_to_pop_failed_realloc = 0; 1668 1669 if (SafepointMechanism::uses_thread_local_poll()) { 1670 SafepointMechanism::initialize_header(this); 1671 } 1672 1673 _class_to_be_initialized = NULL; 1674 1675 pd_initialize(); 1676 } 1677 1678 JavaThread::JavaThread(bool is_attaching_via_jni) : 1679 Thread() { 1680 initialize(); 1681 if (is_attaching_via_jni) { 1682 _jni_attach_state = _attaching_via_jni; 1683 } else { 1684 _jni_attach_state = _not_attaching_via_jni; 1685 } 1686 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1687 } 1688 1689 bool JavaThread::reguard_stack(address cur_sp) { 1690 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1691 && _stack_guard_state != stack_guard_reserved_disabled) { 1692 return true; // Stack already guarded or guard pages not needed. 1693 } 1694 1695 if (register_stack_overflow()) { 1696 // For those architectures which have separate register and 1697 // memory stacks, we must check the register stack to see if 1698 // it has overflowed. 1699 return false; 1700 } 1701 1702 // Java code never executes within the yellow zone: the latter is only 1703 // there to provoke an exception during stack banging. If java code 1704 // is executing there, either StackShadowPages should be larger, or 1705 // some exception code in c1, c2 or the interpreter isn't unwinding 1706 // when it should. 1707 guarantee(cur_sp > stack_reserved_zone_base(), 1708 "not enough space to reguard - increase StackShadowPages"); 1709 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1710 enable_stack_yellow_reserved_zone(); 1711 if (reserved_stack_activation() != stack_base()) { 1712 set_reserved_stack_activation(stack_base()); 1713 } 1714 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1715 set_reserved_stack_activation(stack_base()); 1716 enable_stack_reserved_zone(); 1717 } 1718 return true; 1719 } 1720 1721 bool JavaThread::reguard_stack(void) { 1722 return reguard_stack(os::current_stack_pointer()); 1723 } 1724 1725 1726 void JavaThread::block_if_vm_exited() { 1727 if (_terminated == _vm_exited) { 1728 // _vm_exited is set at safepoint, and Threads_lock is never released 1729 // we will block here forever 1730 Threads_lock->lock_without_safepoint_check(); 1731 ShouldNotReachHere(); 1732 } 1733 } 1734 1735 1736 // Remove this ifdef when C1 is ported to the compiler interface. 1737 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1738 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1739 1740 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1741 Thread() { 1742 initialize(); 1743 _jni_attach_state = _not_attaching_via_jni; 1744 set_entry_point(entry_point); 1745 // Create the native thread itself. 1746 // %note runtime_23 1747 os::ThreadType thr_type = os::java_thread; 1748 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1749 os::java_thread; 1750 os::create_thread(this, thr_type, stack_sz); 1751 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1752 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1753 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1754 // the exception consists of creating the exception object & initializing it, initialization 1755 // will leave the VM via a JavaCall and then all locks must be unlocked). 1756 // 1757 // The thread is still suspended when we reach here. Thread must be explicit started 1758 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1759 // by calling Threads:add. The reason why this is not done here, is because the thread 1760 // object must be fully initialized (take a look at JVM_Start) 1761 } 1762 1763 JavaThread::~JavaThread() { 1764 1765 // JSR166 -- return the parker to the free list 1766 Parker::Release(_parker); 1767 _parker = NULL; 1768 1769 // Free any remaining previous UnrollBlock 1770 vframeArray* old_array = vframe_array_last(); 1771 1772 if (old_array != NULL) { 1773 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1774 old_array->set_unroll_block(NULL); 1775 delete old_info; 1776 delete old_array; 1777 } 1778 1779 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1780 if (deferred != NULL) { 1781 // This can only happen if thread is destroyed before deoptimization occurs. 1782 assert(deferred->length() != 0, "empty array!"); 1783 do { 1784 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1785 deferred->remove_at(0); 1786 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1787 delete dlv; 1788 } while (deferred->length() != 0); 1789 delete deferred; 1790 } 1791 1792 // All Java related clean up happens in exit 1793 ThreadSafepointState::destroy(this); 1794 if (_thread_stat != NULL) delete _thread_stat; 1795 1796 #if INCLUDE_JVMCI 1797 if (JVMCICounterSize > 0) { 1798 if (jvmci_counters_include(this)) { 1799 for (int i = 0; i < JVMCICounterSize; i++) { 1800 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1801 } 1802 } 1803 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1804 } 1805 #endif // INCLUDE_JVMCI 1806 } 1807 1808 1809 // First JavaThread specific code executed by a new Java thread. 1810 void JavaThread::pre_run() { 1811 // empty - see comments in run() 1812 } 1813 1814 // The main routine called by a new Java thread. This isn't overridden 1815 // by subclasses, instead different subclasses define a different "entry_point" 1816 // which defines the actual logic for that kind of thread. 1817 void JavaThread::run() { 1818 // initialize thread-local alloc buffer related fields 1819 this->initialize_tlab(); 1820 1821 // Used to test validity of stack trace backs. 1822 // This can't be moved into pre_run() else we invalidate 1823 // the requirement that thread_main_inner is lower on 1824 // the stack. Consequently all the initialization logic 1825 // stays here in run() rather than pre_run(). 1826 this->record_base_of_stack_pointer(); 1827 1828 this->create_stack_guard_pages(); 1829 1830 this->cache_global_variables(); 1831 1832 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1833 // in the VM. Change thread state from _thread_new to _thread_in_vm 1834 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1835 1836 assert(JavaThread::current() == this, "sanity check"); 1837 assert(!Thread::current()->owns_locks(), "sanity check"); 1838 1839 DTRACE_THREAD_PROBE(start, this); 1840 1841 // This operation might block. We call that after all safepoint checks for a new thread has 1842 // been completed. 1843 this->set_active_handles(JNIHandleBlock::allocate_block()); 1844 1845 if (JvmtiExport::should_post_thread_life()) { 1846 JvmtiExport::post_thread_start(this); 1847 1848 } 1849 1850 // We call another function to do the rest so we are sure that the stack addresses used 1851 // from there will be lower than the stack base just computed. 1852 thread_main_inner(); 1853 } 1854 1855 void JavaThread::thread_main_inner() { 1856 assert(JavaThread::current() == this, "sanity check"); 1857 assert(this->threadObj() != NULL, "just checking"); 1858 1859 // Execute thread entry point unless this thread has a pending exception 1860 // or has been stopped before starting. 1861 // Note: Due to JVM_StopThread we can have pending exceptions already! 1862 if (!this->has_pending_exception() && 1863 !java_lang_Thread::is_stillborn(this->threadObj())) { 1864 { 1865 ResourceMark rm(this); 1866 this->set_native_thread_name(this->get_thread_name()); 1867 } 1868 HandleMark hm(this); 1869 this->entry_point()(this, this); 1870 } 1871 1872 DTRACE_THREAD_PROBE(stop, this); 1873 1874 // Cleanup is handled in post_run() 1875 } 1876 1877 // Shared teardown for all JavaThreads 1878 void JavaThread::post_run() { 1879 this->exit(false); 1880 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1881 // for any shared tear-down. 1882 this->smr_delete(); 1883 } 1884 1885 static void ensure_join(JavaThread* thread) { 1886 // We do not need to grab the Threads_lock, since we are operating on ourself. 1887 Handle threadObj(thread, thread->threadObj()); 1888 assert(threadObj.not_null(), "java thread object must exist"); 1889 ObjectLocker lock(threadObj, thread); 1890 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1891 thread->clear_pending_exception(); 1892 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1893 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1894 // Clear the native thread instance - this makes isAlive return false and allows the join() 1895 // to complete once we've done the notify_all below 1896 java_lang_Thread::set_thread(threadObj(), NULL); 1897 lock.notify_all(thread); 1898 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1899 thread->clear_pending_exception(); 1900 } 1901 1902 static bool is_daemon(oop threadObj) { 1903 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1904 } 1905 1906 // For any new cleanup additions, please check to see if they need to be applied to 1907 // cleanup_failed_attach_current_thread as well. 1908 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1909 assert(this == JavaThread::current(), "thread consistency check"); 1910 1911 elapsedTimer _timer_exit_phase1; 1912 elapsedTimer _timer_exit_phase2; 1913 elapsedTimer _timer_exit_phase3; 1914 elapsedTimer _timer_exit_phase4; 1915 1916 if (log_is_enabled(Debug, os, thread, timer)) { 1917 _timer_exit_phase1.start(); 1918 } 1919 1920 HandleMark hm(this); 1921 Handle uncaught_exception(this, this->pending_exception()); 1922 this->clear_pending_exception(); 1923 Handle threadObj(this, this->threadObj()); 1924 assert(threadObj.not_null(), "Java thread object should be created"); 1925 1926 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1927 { 1928 EXCEPTION_MARK; 1929 1930 CLEAR_PENDING_EXCEPTION; 1931 } 1932 if (!destroy_vm) { 1933 if (uncaught_exception.not_null()) { 1934 EXCEPTION_MARK; 1935 // Call method Thread.dispatchUncaughtException(). 1936 Klass* thread_klass = SystemDictionary::Thread_klass(); 1937 JavaValue result(T_VOID); 1938 JavaCalls::call_virtual(&result, 1939 threadObj, thread_klass, 1940 vmSymbols::dispatchUncaughtException_name(), 1941 vmSymbols::throwable_void_signature(), 1942 uncaught_exception, 1943 THREAD); 1944 if (HAS_PENDING_EXCEPTION) { 1945 ResourceMark rm(this); 1946 jio_fprintf(defaultStream::error_stream(), 1947 "\nException: %s thrown from the UncaughtExceptionHandler" 1948 " in thread \"%s\"\n", 1949 pending_exception()->klass()->external_name(), 1950 get_thread_name()); 1951 CLEAR_PENDING_EXCEPTION; 1952 } 1953 } 1954 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 1955 1956 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1957 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1958 // is deprecated anyhow. 1959 if (!is_Compiler_thread()) { 1960 int count = 3; 1961 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1962 EXCEPTION_MARK; 1963 JavaValue result(T_VOID); 1964 Klass* thread_klass = SystemDictionary::Thread_klass(); 1965 JavaCalls::call_virtual(&result, 1966 threadObj, thread_klass, 1967 vmSymbols::exit_method_name(), 1968 vmSymbols::void_method_signature(), 1969 THREAD); 1970 CLEAR_PENDING_EXCEPTION; 1971 } 1972 } 1973 // notify JVMTI 1974 if (JvmtiExport::should_post_thread_life()) { 1975 JvmtiExport::post_thread_end(this); 1976 } 1977 1978 // We have notified the agents that we are exiting, before we go on, 1979 // we must check for a pending external suspend request and honor it 1980 // in order to not surprise the thread that made the suspend request. 1981 while (true) { 1982 { 1983 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1984 if (!is_external_suspend()) { 1985 set_terminated(_thread_exiting); 1986 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 1987 break; 1988 } 1989 // Implied else: 1990 // Things get a little tricky here. We have a pending external 1991 // suspend request, but we are holding the SR_lock so we 1992 // can't just self-suspend. So we temporarily drop the lock 1993 // and then self-suspend. 1994 } 1995 1996 ThreadBlockInVM tbivm(this); 1997 java_suspend_self(); 1998 1999 // We're done with this suspend request, but we have to loop around 2000 // and check again. Eventually we will get SR_lock without a pending 2001 // external suspend request and will be able to mark ourselves as 2002 // exiting. 2003 } 2004 // no more external suspends are allowed at this point 2005 } else { 2006 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2007 // before_exit() has already posted JVMTI THREAD_END events 2008 } 2009 2010 if (log_is_enabled(Debug, os, thread, timer)) { 2011 _timer_exit_phase1.stop(); 2012 _timer_exit_phase2.start(); 2013 } 2014 // Notify waiters on thread object. This has to be done after exit() is called 2015 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2016 // group should have the destroyed bit set before waiters are notified). 2017 ensure_join(this); 2018 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2019 2020 if (log_is_enabled(Debug, os, thread, timer)) { 2021 _timer_exit_phase2.stop(); 2022 _timer_exit_phase3.start(); 2023 } 2024 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2025 // held by this thread must be released. The spec does not distinguish 2026 // between JNI-acquired and regular Java monitors. We can only see 2027 // regular Java monitors here if monitor enter-exit matching is broken. 2028 // 2029 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2030 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2031 if (exit_type == jni_detach) { 2032 // Sanity check even though JNI DetachCurrentThread() would have 2033 // returned JNI_ERR if there was a Java frame. JavaThread exit 2034 // should be done executing Java code by the time we get here. 2035 assert(!this->has_last_Java_frame(), 2036 "should not have a Java frame when detaching or exiting"); 2037 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2038 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2039 } 2040 2041 // These things needs to be done while we are still a Java Thread. Make sure that thread 2042 // is in a consistent state, in case GC happens 2043 JFR_ONLY(Jfr::on_thread_exit(this);) 2044 2045 if (active_handles() != NULL) { 2046 JNIHandleBlock* block = active_handles(); 2047 set_active_handles(NULL); 2048 JNIHandleBlock::release_block(block); 2049 } 2050 2051 if (free_handle_block() != NULL) { 2052 JNIHandleBlock* block = free_handle_block(); 2053 set_free_handle_block(NULL); 2054 JNIHandleBlock::release_block(block); 2055 } 2056 2057 // These have to be removed while this is still a valid thread. 2058 remove_stack_guard_pages(); 2059 2060 if (UseTLAB) { 2061 tlab().retire(); 2062 } 2063 2064 if (JvmtiEnv::environments_might_exist()) { 2065 JvmtiExport::cleanup_thread(this); 2066 } 2067 2068 // We must flush any deferred card marks and other various GC barrier 2069 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2070 // before removing a thread from the list of active threads. 2071 BarrierSet::barrier_set()->on_thread_detach(this); 2072 2073 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2074 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2075 os::current_thread_id()); 2076 2077 if (log_is_enabled(Debug, os, thread, timer)) { 2078 _timer_exit_phase3.stop(); 2079 _timer_exit_phase4.start(); 2080 } 2081 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2082 Threads::remove(this); 2083 2084 if (log_is_enabled(Debug, os, thread, timer)) { 2085 _timer_exit_phase4.stop(); 2086 ResourceMark rm(this); 2087 log_debug(os, thread, timer)("name='%s'" 2088 ", exit-phase1=" JLONG_FORMAT 2089 ", exit-phase2=" JLONG_FORMAT 2090 ", exit-phase3=" JLONG_FORMAT 2091 ", exit-phase4=" JLONG_FORMAT, 2092 get_thread_name(), 2093 _timer_exit_phase1.milliseconds(), 2094 _timer_exit_phase2.milliseconds(), 2095 _timer_exit_phase3.milliseconds(), 2096 _timer_exit_phase4.milliseconds()); 2097 } 2098 } 2099 2100 void JavaThread::cleanup_failed_attach_current_thread() { 2101 if (active_handles() != NULL) { 2102 JNIHandleBlock* block = active_handles(); 2103 set_active_handles(NULL); 2104 JNIHandleBlock::release_block(block); 2105 } 2106 2107 if (free_handle_block() != NULL) { 2108 JNIHandleBlock* block = free_handle_block(); 2109 set_free_handle_block(NULL); 2110 JNIHandleBlock::release_block(block); 2111 } 2112 2113 // These have to be removed while this is still a valid thread. 2114 remove_stack_guard_pages(); 2115 2116 if (UseTLAB) { 2117 tlab().retire(); 2118 } 2119 2120 BarrierSet::barrier_set()->on_thread_detach(this); 2121 2122 Threads::remove(this); 2123 this->smr_delete(); 2124 } 2125 2126 JavaThread* JavaThread::active() { 2127 Thread* thread = Thread::current(); 2128 if (thread->is_Java_thread()) { 2129 return (JavaThread*) thread; 2130 } else { 2131 assert(thread->is_VM_thread(), "this must be a vm thread"); 2132 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2133 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2134 assert(ret->is_Java_thread(), "must be a Java thread"); 2135 return ret; 2136 } 2137 } 2138 2139 bool JavaThread::is_lock_owned(address adr) const { 2140 if (Thread::is_lock_owned(adr)) return true; 2141 2142 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2143 if (chunk->contains(adr)) return true; 2144 } 2145 2146 return false; 2147 } 2148 2149 2150 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2151 chunk->set_next(monitor_chunks()); 2152 set_monitor_chunks(chunk); 2153 } 2154 2155 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2156 guarantee(monitor_chunks() != NULL, "must be non empty"); 2157 if (monitor_chunks() == chunk) { 2158 set_monitor_chunks(chunk->next()); 2159 } else { 2160 MonitorChunk* prev = monitor_chunks(); 2161 while (prev->next() != chunk) prev = prev->next(); 2162 prev->set_next(chunk->next()); 2163 } 2164 } 2165 2166 // JVM support. 2167 2168 // Note: this function shouldn't block if it's called in 2169 // _thread_in_native_trans state (such as from 2170 // check_special_condition_for_native_trans()). 2171 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2172 2173 if (has_last_Java_frame() && has_async_condition()) { 2174 // If we are at a polling page safepoint (not a poll return) 2175 // then we must defer async exception because live registers 2176 // will be clobbered by the exception path. Poll return is 2177 // ok because the call we a returning from already collides 2178 // with exception handling registers and so there is no issue. 2179 // (The exception handling path kills call result registers but 2180 // this is ok since the exception kills the result anyway). 2181 2182 if (is_at_poll_safepoint()) { 2183 // if the code we are returning to has deoptimized we must defer 2184 // the exception otherwise live registers get clobbered on the 2185 // exception path before deoptimization is able to retrieve them. 2186 // 2187 RegisterMap map(this, false); 2188 frame caller_fr = last_frame().sender(&map); 2189 assert(caller_fr.is_compiled_frame(), "what?"); 2190 if (caller_fr.is_deoptimized_frame()) { 2191 log_info(exceptions)("deferred async exception at compiled safepoint"); 2192 return; 2193 } 2194 } 2195 } 2196 2197 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2198 if (condition == _no_async_condition) { 2199 // Conditions have changed since has_special_runtime_exit_condition() 2200 // was called: 2201 // - if we were here only because of an external suspend request, 2202 // then that was taken care of above (or cancelled) so we are done 2203 // - if we were here because of another async request, then it has 2204 // been cleared between the has_special_runtime_exit_condition() 2205 // and now so again we are done 2206 return; 2207 } 2208 2209 // Check for pending async. exception 2210 if (_pending_async_exception != NULL) { 2211 // Only overwrite an already pending exception, if it is not a threadDeath. 2212 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2213 2214 // We cannot call Exceptions::_throw(...) here because we cannot block 2215 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2216 2217 LogTarget(Info, exceptions) lt; 2218 if (lt.is_enabled()) { 2219 ResourceMark rm; 2220 LogStream ls(lt); 2221 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2222 if (has_last_Java_frame()) { 2223 frame f = last_frame(); 2224 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2225 } 2226 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2227 } 2228 _pending_async_exception = NULL; 2229 clear_has_async_exception(); 2230 } 2231 } 2232 2233 if (check_unsafe_error && 2234 condition == _async_unsafe_access_error && !has_pending_exception()) { 2235 condition = _no_async_condition; // done 2236 switch (thread_state()) { 2237 case _thread_in_vm: { 2238 JavaThread* THREAD = this; 2239 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2240 } 2241 case _thread_in_native: { 2242 ThreadInVMfromNative tiv(this); 2243 JavaThread* THREAD = this; 2244 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2245 } 2246 case _thread_in_Java: { 2247 ThreadInVMfromJava tiv(this); 2248 JavaThread* THREAD = this; 2249 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2250 } 2251 default: 2252 ShouldNotReachHere(); 2253 } 2254 } 2255 2256 assert(condition == _no_async_condition || has_pending_exception() || 2257 (!check_unsafe_error && condition == _async_unsafe_access_error), 2258 "must have handled the async condition, if no exception"); 2259 } 2260 2261 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2262 // 2263 // Check for pending external suspend. Internal suspend requests do 2264 // not use handle_special_runtime_exit_condition(). 2265 // If JNIEnv proxies are allowed, don't self-suspend if the target 2266 // thread is not the current thread. In older versions of jdbx, jdbx 2267 // threads could call into the VM with another thread's JNIEnv so we 2268 // can be here operating on behalf of a suspended thread (4432884). 2269 bool do_self_suspend = is_external_suspend_with_lock(); 2270 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2271 // 2272 // Because thread is external suspended the safepoint code will count 2273 // thread as at a safepoint. This can be odd because we can be here 2274 // as _thread_in_Java which would normally transition to _thread_blocked 2275 // at a safepoint. We would like to mark the thread as _thread_blocked 2276 // before calling java_suspend_self like all other callers of it but 2277 // we must then observe proper safepoint protocol. (We can't leave 2278 // _thread_blocked with a safepoint in progress). However we can be 2279 // here as _thread_in_native_trans so we can't use a normal transition 2280 // constructor/destructor pair because they assert on that type of 2281 // transition. We could do something like: 2282 // 2283 // JavaThreadState state = thread_state(); 2284 // set_thread_state(_thread_in_vm); 2285 // { 2286 // ThreadBlockInVM tbivm(this); 2287 // java_suspend_self() 2288 // } 2289 // set_thread_state(_thread_in_vm_trans); 2290 // if (safepoint) block; 2291 // set_thread_state(state); 2292 // 2293 // but that is pretty messy. Instead we just go with the way the 2294 // code has worked before and note that this is the only path to 2295 // java_suspend_self that doesn't put the thread in _thread_blocked 2296 // mode. 2297 2298 frame_anchor()->make_walkable(this); 2299 java_suspend_self(); 2300 2301 // We might be here for reasons in addition to the self-suspend request 2302 // so check for other async requests. 2303 } 2304 2305 if (check_asyncs) { 2306 check_and_handle_async_exceptions(); 2307 } 2308 2309 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2310 } 2311 2312 void JavaThread::send_thread_stop(oop java_throwable) { 2313 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2314 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2315 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2316 2317 // Do not throw asynchronous exceptions against the compiler thread 2318 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2319 if (!can_call_java()) return; 2320 2321 { 2322 // Actually throw the Throwable against the target Thread - however 2323 // only if there is no thread death exception installed already. 2324 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2325 // If the topmost frame is a runtime stub, then we are calling into 2326 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2327 // must deoptimize the caller before continuing, as the compiled exception handler table 2328 // may not be valid 2329 if (has_last_Java_frame()) { 2330 frame f = last_frame(); 2331 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2332 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2333 RegisterMap reg_map(this, UseBiasedLocking); 2334 frame compiled_frame = f.sender(®_map); 2335 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2336 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2337 } 2338 } 2339 } 2340 2341 // Set async. pending exception in thread. 2342 set_pending_async_exception(java_throwable); 2343 2344 if (log_is_enabled(Info, exceptions)) { 2345 ResourceMark rm; 2346 log_info(exceptions)("Pending Async. exception installed of type: %s", 2347 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2348 } 2349 // for AbortVMOnException flag 2350 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2351 } 2352 } 2353 2354 2355 // Interrupt thread so it will wake up from a potential wait() 2356 Thread::interrupt(this); 2357 } 2358 2359 // External suspension mechanism. 2360 // 2361 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2362 // to any VM_locks and it is at a transition 2363 // Self-suspension will happen on the transition out of the vm. 2364 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2365 // 2366 // Guarantees on return: 2367 // + Target thread will not execute any new bytecode (that's why we need to 2368 // force a safepoint) 2369 // + Target thread will not enter any new monitors 2370 // 2371 void JavaThread::java_suspend() { 2372 ThreadsListHandle tlh; 2373 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2374 return; 2375 } 2376 2377 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2378 if (!is_external_suspend()) { 2379 // a racing resume has cancelled us; bail out now 2380 return; 2381 } 2382 2383 // suspend is done 2384 uint32_t debug_bits = 0; 2385 // Warning: is_ext_suspend_completed() may temporarily drop the 2386 // SR_lock to allow the thread to reach a stable thread state if 2387 // it is currently in a transient thread state. 2388 if (is_ext_suspend_completed(false /* !called_by_wait */, 2389 SuspendRetryDelay, &debug_bits)) { 2390 return; 2391 } 2392 } 2393 2394 if (Thread::current() == this) { 2395 // Safely self-suspend. 2396 // If we don't do this explicitly it will implicitly happen 2397 // before we transition back to Java, and on some other thread-state 2398 // transition paths, but not as we exit a JVM TI SuspendThread call. 2399 // As SuspendThread(current) must not return (until resumed) we must 2400 // self-suspend here. 2401 ThreadBlockInVM tbivm(this); 2402 java_suspend_self(); 2403 } else { 2404 VM_ThreadSuspend vm_suspend; 2405 VMThread::execute(&vm_suspend); 2406 } 2407 } 2408 2409 // Part II of external suspension. 2410 // A JavaThread self suspends when it detects a pending external suspend 2411 // request. This is usually on transitions. It is also done in places 2412 // where continuing to the next transition would surprise the caller, 2413 // e.g., monitor entry. 2414 // 2415 // Returns the number of times that the thread self-suspended. 2416 // 2417 // Note: DO NOT call java_suspend_self() when you just want to block current 2418 // thread. java_suspend_self() is the second stage of cooperative 2419 // suspension for external suspend requests and should only be used 2420 // to complete an external suspend request. 2421 // 2422 int JavaThread::java_suspend_self() { 2423 int ret = 0; 2424 2425 // we are in the process of exiting so don't suspend 2426 if (is_exiting()) { 2427 clear_external_suspend(); 2428 return ret; 2429 } 2430 2431 assert(_anchor.walkable() || 2432 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2433 "must have walkable stack"); 2434 2435 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2436 2437 assert(!this->is_ext_suspended(), 2438 "a thread trying to self-suspend should not already be suspended"); 2439 2440 if (this->is_suspend_equivalent()) { 2441 // If we are self-suspending as a result of the lifting of a 2442 // suspend equivalent condition, then the suspend_equivalent 2443 // flag is not cleared until we set the ext_suspended flag so 2444 // that wait_for_ext_suspend_completion() returns consistent 2445 // results. 2446 this->clear_suspend_equivalent(); 2447 } 2448 2449 // A racing resume may have cancelled us before we grabbed SR_lock 2450 // above. Or another external suspend request could be waiting for us 2451 // by the time we return from SR_lock()->wait(). The thread 2452 // that requested the suspension may already be trying to walk our 2453 // stack and if we return now, we can change the stack out from under 2454 // it. This would be a "bad thing (TM)" and cause the stack walker 2455 // to crash. We stay self-suspended until there are no more pending 2456 // external suspend requests. 2457 while (is_external_suspend()) { 2458 ret++; 2459 this->set_ext_suspended(); 2460 2461 // _ext_suspended flag is cleared by java_resume() 2462 while (is_ext_suspended()) { 2463 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2464 } 2465 } 2466 2467 return ret; 2468 } 2469 2470 #ifdef ASSERT 2471 // Verify the JavaThread has not yet been published in the Threads::list, and 2472 // hence doesn't need protection from concurrent access at this stage. 2473 void JavaThread::verify_not_published() { 2474 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2475 // since an unpublished JavaThread doesn't participate in the 2476 // Thread-SMR protocol for keeping a ThreadsList alive. 2477 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2478 } 2479 #endif 2480 2481 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2482 // progress or when _suspend_flags is non-zero. 2483 // Current thread needs to self-suspend if there is a suspend request and/or 2484 // block if a safepoint is in progress. 2485 // Async exception ISN'T checked. 2486 // Note only the ThreadInVMfromNative transition can call this function 2487 // directly and when thread state is _thread_in_native_trans 2488 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2489 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2490 2491 JavaThread *curJT = JavaThread::current(); 2492 bool do_self_suspend = thread->is_external_suspend(); 2493 2494 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2495 2496 // If JNIEnv proxies are allowed, don't self-suspend if the target 2497 // thread is not the current thread. In older versions of jdbx, jdbx 2498 // threads could call into the VM with another thread's JNIEnv so we 2499 // can be here operating on behalf of a suspended thread (4432884). 2500 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2501 JavaThreadState state = thread->thread_state(); 2502 2503 // We mark this thread_blocked state as a suspend-equivalent so 2504 // that a caller to is_ext_suspend_completed() won't be confused. 2505 // The suspend-equivalent state is cleared by java_suspend_self(). 2506 thread->set_suspend_equivalent(); 2507 2508 // If the safepoint code sees the _thread_in_native_trans state, it will 2509 // wait until the thread changes to other thread state. There is no 2510 // guarantee on how soon we can obtain the SR_lock and complete the 2511 // self-suspend request. It would be a bad idea to let safepoint wait for 2512 // too long. Temporarily change the state to _thread_blocked to 2513 // let the VM thread know that this thread is ready for GC. The problem 2514 // of changing thread state is that safepoint could happen just after 2515 // java_suspend_self() returns after being resumed, and VM thread will 2516 // see the _thread_blocked state. We must check for safepoint 2517 // after restoring the state and make sure we won't leave while a safepoint 2518 // is in progress. 2519 thread->set_thread_state(_thread_blocked); 2520 thread->java_suspend_self(); 2521 thread->set_thread_state(state); 2522 2523 InterfaceSupport::serialize_thread_state_with_handler(thread); 2524 } 2525 2526 SafepointMechanism::block_if_requested(curJT); 2527 2528 if (thread->is_deopt_suspend()) { 2529 thread->clear_deopt_suspend(); 2530 RegisterMap map(thread, false); 2531 frame f = thread->last_frame(); 2532 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2533 f = f.sender(&map); 2534 } 2535 if (f.id() == thread->must_deopt_id()) { 2536 thread->clear_must_deopt_id(); 2537 f.deoptimize(thread); 2538 } else { 2539 fatal("missed deoptimization!"); 2540 } 2541 } 2542 2543 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2544 } 2545 2546 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2547 // progress or when _suspend_flags is non-zero. 2548 // Current thread needs to self-suspend if there is a suspend request and/or 2549 // block if a safepoint is in progress. 2550 // Also check for pending async exception (not including unsafe access error). 2551 // Note only the native==>VM/Java barriers can call this function and when 2552 // thread state is _thread_in_native_trans. 2553 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2554 check_safepoint_and_suspend_for_native_trans(thread); 2555 2556 if (thread->has_async_exception()) { 2557 // We are in _thread_in_native_trans state, don't handle unsafe 2558 // access error since that may block. 2559 thread->check_and_handle_async_exceptions(false); 2560 } 2561 } 2562 2563 // This is a variant of the normal 2564 // check_special_condition_for_native_trans with slightly different 2565 // semantics for use by critical native wrappers. It does all the 2566 // normal checks but also performs the transition back into 2567 // thread_in_Java state. This is required so that critical natives 2568 // can potentially block and perform a GC if they are the last thread 2569 // exiting the GCLocker. 2570 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2571 check_special_condition_for_native_trans(thread); 2572 2573 // Finish the transition 2574 thread->set_thread_state(_thread_in_Java); 2575 2576 if (thread->do_critical_native_unlock()) { 2577 ThreadInVMfromJavaNoAsyncException tiv(thread); 2578 GCLocker::unlock_critical(thread); 2579 thread->clear_critical_native_unlock(); 2580 } 2581 } 2582 2583 // We need to guarantee the Threads_lock here, since resumes are not 2584 // allowed during safepoint synchronization 2585 // Can only resume from an external suspension 2586 void JavaThread::java_resume() { 2587 assert_locked_or_safepoint(Threads_lock); 2588 2589 // Sanity check: thread is gone, has started exiting or the thread 2590 // was not externally suspended. 2591 ThreadsListHandle tlh; 2592 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2593 return; 2594 } 2595 2596 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2597 2598 clear_external_suspend(); 2599 2600 if (is_ext_suspended()) { 2601 clear_ext_suspended(); 2602 SR_lock()->notify_all(); 2603 } 2604 } 2605 2606 size_t JavaThread::_stack_red_zone_size = 0; 2607 size_t JavaThread::_stack_yellow_zone_size = 0; 2608 size_t JavaThread::_stack_reserved_zone_size = 0; 2609 size_t JavaThread::_stack_shadow_zone_size = 0; 2610 2611 void JavaThread::create_stack_guard_pages() { 2612 if (!os::uses_stack_guard_pages() || 2613 _stack_guard_state != stack_guard_unused || 2614 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2615 log_info(os, thread)("Stack guard page creation for thread " 2616 UINTX_FORMAT " disabled", os::current_thread_id()); 2617 return; 2618 } 2619 address low_addr = stack_end(); 2620 size_t len = stack_guard_zone_size(); 2621 2622 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2623 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2624 2625 int must_commit = os::must_commit_stack_guard_pages(); 2626 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2627 2628 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2629 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2630 return; 2631 } 2632 2633 if (os::guard_memory((char *) low_addr, len)) { 2634 _stack_guard_state = stack_guard_enabled; 2635 } else { 2636 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2637 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2638 if (os::uncommit_memory((char *) low_addr, len)) { 2639 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2640 } 2641 return; 2642 } 2643 2644 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2645 PTR_FORMAT "-" PTR_FORMAT ".", 2646 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2647 } 2648 2649 void JavaThread::remove_stack_guard_pages() { 2650 assert(Thread::current() == this, "from different thread"); 2651 if (_stack_guard_state == stack_guard_unused) return; 2652 address low_addr = stack_end(); 2653 size_t len = stack_guard_zone_size(); 2654 2655 if (os::must_commit_stack_guard_pages()) { 2656 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2657 _stack_guard_state = stack_guard_unused; 2658 } else { 2659 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2660 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2661 return; 2662 } 2663 } else { 2664 if (_stack_guard_state == stack_guard_unused) return; 2665 if (os::unguard_memory((char *) low_addr, len)) { 2666 _stack_guard_state = stack_guard_unused; 2667 } else { 2668 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2669 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2670 return; 2671 } 2672 } 2673 2674 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2675 PTR_FORMAT "-" PTR_FORMAT ".", 2676 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2677 } 2678 2679 void JavaThread::enable_stack_reserved_zone() { 2680 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2681 2682 // The base notation is from the stack's point of view, growing downward. 2683 // We need to adjust it to work correctly with guard_memory() 2684 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2685 2686 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2687 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2688 2689 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2690 _stack_guard_state = stack_guard_enabled; 2691 } else { 2692 warning("Attempt to guard stack reserved zone failed."); 2693 } 2694 enable_register_stack_guard(); 2695 } 2696 2697 void JavaThread::disable_stack_reserved_zone() { 2698 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2699 2700 // Simply return if called for a thread that does not use guard pages. 2701 if (_stack_guard_state != stack_guard_enabled) return; 2702 2703 // The base notation is from the stack's point of view, growing downward. 2704 // We need to adjust it to work correctly with guard_memory() 2705 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2706 2707 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2708 _stack_guard_state = stack_guard_reserved_disabled; 2709 } else { 2710 warning("Attempt to unguard stack reserved zone failed."); 2711 } 2712 disable_register_stack_guard(); 2713 } 2714 2715 void JavaThread::enable_stack_yellow_reserved_zone() { 2716 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2717 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2718 2719 // The base notation is from the stacks point of view, growing downward. 2720 // We need to adjust it to work correctly with guard_memory() 2721 address base = stack_red_zone_base(); 2722 2723 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2724 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2725 2726 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2727 _stack_guard_state = stack_guard_enabled; 2728 } else { 2729 warning("Attempt to guard stack yellow zone failed."); 2730 } 2731 enable_register_stack_guard(); 2732 } 2733 2734 void JavaThread::disable_stack_yellow_reserved_zone() { 2735 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2736 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2737 2738 // Simply return if called for a thread that does not use guard pages. 2739 if (_stack_guard_state == stack_guard_unused) return; 2740 2741 // The base notation is from the stacks point of view, growing downward. 2742 // We need to adjust it to work correctly with guard_memory() 2743 address base = stack_red_zone_base(); 2744 2745 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2746 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2747 } else { 2748 warning("Attempt to unguard stack yellow zone failed."); 2749 } 2750 disable_register_stack_guard(); 2751 } 2752 2753 void JavaThread::enable_stack_red_zone() { 2754 // The base notation is from the stacks point of view, growing downward. 2755 // We need to adjust it to work correctly with guard_memory() 2756 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2757 address base = stack_red_zone_base() - stack_red_zone_size(); 2758 2759 guarantee(base < stack_base(), "Error calculating stack red zone"); 2760 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2761 2762 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2763 warning("Attempt to guard stack red zone failed."); 2764 } 2765 } 2766 2767 void JavaThread::disable_stack_red_zone() { 2768 // The base notation is from the stacks point of view, growing downward. 2769 // We need to adjust it to work correctly with guard_memory() 2770 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2771 address base = stack_red_zone_base() - stack_red_zone_size(); 2772 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2773 warning("Attempt to unguard stack red zone failed."); 2774 } 2775 } 2776 2777 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2778 // ignore is there is no stack 2779 if (!has_last_Java_frame()) return; 2780 // traverse the stack frames. Starts from top frame. 2781 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2782 frame* fr = fst.current(); 2783 f(fr, fst.register_map()); 2784 } 2785 } 2786 2787 2788 #ifndef PRODUCT 2789 // Deoptimization 2790 // Function for testing deoptimization 2791 void JavaThread::deoptimize() { 2792 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2793 StackFrameStream fst(this, UseBiasedLocking); 2794 bool deopt = false; // Dump stack only if a deopt actually happens. 2795 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2796 // Iterate over all frames in the thread and deoptimize 2797 for (; !fst.is_done(); fst.next()) { 2798 if (fst.current()->can_be_deoptimized()) { 2799 2800 if (only_at) { 2801 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2802 // consists of comma or carriage return separated numbers so 2803 // search for the current bci in that string. 2804 address pc = fst.current()->pc(); 2805 nmethod* nm = (nmethod*) fst.current()->cb(); 2806 ScopeDesc* sd = nm->scope_desc_at(pc); 2807 char buffer[8]; 2808 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2809 size_t len = strlen(buffer); 2810 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2811 while (found != NULL) { 2812 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2813 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2814 // Check that the bci found is bracketed by terminators. 2815 break; 2816 } 2817 found = strstr(found + 1, buffer); 2818 } 2819 if (!found) { 2820 continue; 2821 } 2822 } 2823 2824 if (DebugDeoptimization && !deopt) { 2825 deopt = true; // One-time only print before deopt 2826 tty->print_cr("[BEFORE Deoptimization]"); 2827 trace_frames(); 2828 trace_stack(); 2829 } 2830 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2831 } 2832 } 2833 2834 if (DebugDeoptimization && deopt) { 2835 tty->print_cr("[AFTER Deoptimization]"); 2836 trace_frames(); 2837 } 2838 } 2839 2840 2841 // Make zombies 2842 void JavaThread::make_zombies() { 2843 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2844 if (fst.current()->can_be_deoptimized()) { 2845 // it is a Java nmethod 2846 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2847 nm->make_not_entrant(); 2848 } 2849 } 2850 } 2851 #endif // PRODUCT 2852 2853 2854 void JavaThread::deoptimized_wrt_marked_nmethods() { 2855 if (!has_last_Java_frame()) return; 2856 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2857 StackFrameStream fst(this, UseBiasedLocking); 2858 for (; !fst.is_done(); fst.next()) { 2859 if (fst.current()->should_be_deoptimized()) { 2860 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2861 } 2862 } 2863 } 2864 2865 2866 // If the caller is a NamedThread, then remember, in the current scope, 2867 // the given JavaThread in its _processed_thread field. 2868 class RememberProcessedThread: public StackObj { 2869 NamedThread* _cur_thr; 2870 public: 2871 RememberProcessedThread(JavaThread* jthr) { 2872 Thread* thread = Thread::current(); 2873 if (thread->is_Named_thread()) { 2874 _cur_thr = (NamedThread *)thread; 2875 _cur_thr->set_processed_thread(jthr); 2876 } else { 2877 _cur_thr = NULL; 2878 } 2879 } 2880 2881 ~RememberProcessedThread() { 2882 if (_cur_thr) { 2883 _cur_thr->set_processed_thread(NULL); 2884 } 2885 } 2886 }; 2887 2888 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2889 // Verify that the deferred card marks have been flushed. 2890 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2891 2892 // Traverse the GCHandles 2893 Thread::oops_do(f, cf); 2894 2895 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2896 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2897 2898 if (has_last_Java_frame()) { 2899 // Record JavaThread to GC thread 2900 RememberProcessedThread rpt(this); 2901 2902 // traverse the registered growable array 2903 if (_array_for_gc != NULL) { 2904 for (int index = 0; index < _array_for_gc->length(); index++) { 2905 f->do_oop(_array_for_gc->adr_at(index)); 2906 } 2907 } 2908 2909 // Traverse the monitor chunks 2910 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2911 chunk->oops_do(f); 2912 } 2913 2914 // Traverse the execution stack 2915 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2916 fst.current()->oops_do(f, cf, fst.register_map()); 2917 } 2918 } 2919 2920 // callee_target is never live across a gc point so NULL it here should 2921 // it still contain a methdOop. 2922 2923 set_callee_target(NULL); 2924 2925 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2926 // If we have deferred set_locals there might be oops waiting to be 2927 // written 2928 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2929 if (list != NULL) { 2930 for (int i = 0; i < list->length(); i++) { 2931 list->at(i)->oops_do(f); 2932 } 2933 } 2934 2935 // Traverse instance variables at the end since the GC may be moving things 2936 // around using this function 2937 f->do_oop((oop*) &_threadObj); 2938 f->do_oop((oop*) &_vm_result); 2939 f->do_oop((oop*) &_exception_oop); 2940 f->do_oop((oop*) &_pending_async_exception); 2941 2942 if (jvmti_thread_state() != NULL) { 2943 jvmti_thread_state()->oops_do(f); 2944 } 2945 } 2946 2947 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2948 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2949 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2950 2951 if (has_last_Java_frame()) { 2952 // Traverse the execution stack 2953 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2954 fst.current()->nmethods_do(cf); 2955 } 2956 } 2957 } 2958 2959 void JavaThread::metadata_do(void f(Metadata*)) { 2960 if (has_last_Java_frame()) { 2961 // Traverse the execution stack to call f() on the methods in the stack 2962 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2963 fst.current()->metadata_do(f); 2964 } 2965 } else if (is_Compiler_thread()) { 2966 // need to walk ciMetadata in current compile tasks to keep alive. 2967 CompilerThread* ct = (CompilerThread*)this; 2968 if (ct->env() != NULL) { 2969 ct->env()->metadata_do(f); 2970 } 2971 CompileTask* task = ct->task(); 2972 if (task != NULL) { 2973 task->metadata_do(f); 2974 } 2975 } 2976 } 2977 2978 // Printing 2979 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2980 switch (_thread_state) { 2981 case _thread_uninitialized: return "_thread_uninitialized"; 2982 case _thread_new: return "_thread_new"; 2983 case _thread_new_trans: return "_thread_new_trans"; 2984 case _thread_in_native: return "_thread_in_native"; 2985 case _thread_in_native_trans: return "_thread_in_native_trans"; 2986 case _thread_in_vm: return "_thread_in_vm"; 2987 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2988 case _thread_in_Java: return "_thread_in_Java"; 2989 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2990 case _thread_blocked: return "_thread_blocked"; 2991 case _thread_blocked_trans: return "_thread_blocked_trans"; 2992 default: return "unknown thread state"; 2993 } 2994 } 2995 2996 #ifndef PRODUCT 2997 void JavaThread::print_thread_state_on(outputStream *st) const { 2998 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2999 }; 3000 void JavaThread::print_thread_state() const { 3001 print_thread_state_on(tty); 3002 } 3003 #endif // PRODUCT 3004 3005 // Called by Threads::print() for VM_PrintThreads operation 3006 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3007 st->print_raw("\""); 3008 st->print_raw(get_thread_name()); 3009 st->print_raw("\" "); 3010 oop thread_oop = threadObj(); 3011 if (thread_oop != NULL) { 3012 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3013 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3014 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3015 } 3016 Thread::print_on(st, print_extended_info); 3017 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3018 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3019 if (thread_oop != NULL) { 3020 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3021 } 3022 #ifndef PRODUCT 3023 _safepoint_state->print_on(st); 3024 #endif // PRODUCT 3025 if (is_Compiler_thread()) { 3026 CompileTask *task = ((CompilerThread*)this)->task(); 3027 if (task != NULL) { 3028 st->print(" Compiling: "); 3029 task->print(st, NULL, true, false); 3030 } else { 3031 st->print(" No compile task"); 3032 } 3033 st->cr(); 3034 } 3035 } 3036 3037 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3038 st->print("%s", get_thread_name_string(buf, buflen)); 3039 } 3040 3041 // Called by fatal error handler. The difference between this and 3042 // JavaThread::print() is that we can't grab lock or allocate memory. 3043 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3044 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3045 oop thread_obj = threadObj(); 3046 if (thread_obj != NULL) { 3047 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3048 } 3049 st->print(" ["); 3050 st->print("%s", _get_thread_state_name(_thread_state)); 3051 if (osthread()) { 3052 st->print(", id=%d", osthread()->thread_id()); 3053 } 3054 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3055 p2i(stack_end()), p2i(stack_base())); 3056 st->print("]"); 3057 3058 ThreadsSMRSupport::print_info_on(this, st); 3059 return; 3060 } 3061 3062 // Verification 3063 3064 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3065 3066 void JavaThread::verify() { 3067 // Verify oops in the thread. 3068 oops_do(&VerifyOopClosure::verify_oop, NULL); 3069 3070 // Verify the stack frames. 3071 frames_do(frame_verify); 3072 } 3073 3074 // CR 6300358 (sub-CR 2137150) 3075 // Most callers of this method assume that it can't return NULL but a 3076 // thread may not have a name whilst it is in the process of attaching to 3077 // the VM - see CR 6412693, and there are places where a JavaThread can be 3078 // seen prior to having it's threadObj set (eg JNI attaching threads and 3079 // if vm exit occurs during initialization). These cases can all be accounted 3080 // for such that this method never returns NULL. 3081 const char* JavaThread::get_thread_name() const { 3082 #ifdef ASSERT 3083 // early safepoints can hit while current thread does not yet have TLS 3084 if (!SafepointSynchronize::is_at_safepoint()) { 3085 Thread *cur = Thread::current(); 3086 if (!(cur->is_Java_thread() && cur == this)) { 3087 // Current JavaThreads are allowed to get their own name without 3088 // the Threads_lock. 3089 assert_locked_or_safepoint(Threads_lock); 3090 } 3091 } 3092 #endif // ASSERT 3093 return get_thread_name_string(); 3094 } 3095 3096 // Returns a non-NULL representation of this thread's name, or a suitable 3097 // descriptive string if there is no set name 3098 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3099 const char* name_str; 3100 oop thread_obj = threadObj(); 3101 if (thread_obj != NULL) { 3102 oop name = java_lang_Thread::name(thread_obj); 3103 if (name != NULL) { 3104 if (buf == NULL) { 3105 name_str = java_lang_String::as_utf8_string(name); 3106 } else { 3107 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3108 } 3109 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3110 name_str = "<no-name - thread is attaching>"; 3111 } else { 3112 name_str = Thread::name(); 3113 } 3114 } else { 3115 name_str = Thread::name(); 3116 } 3117 assert(name_str != NULL, "unexpected NULL thread name"); 3118 return name_str; 3119 } 3120 3121 3122 const char* JavaThread::get_threadgroup_name() const { 3123 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3124 oop thread_obj = threadObj(); 3125 if (thread_obj != NULL) { 3126 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3127 if (thread_group != NULL) { 3128 // ThreadGroup.name can be null 3129 return java_lang_ThreadGroup::name(thread_group); 3130 } 3131 } 3132 return NULL; 3133 } 3134 3135 const char* JavaThread::get_parent_name() const { 3136 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3137 oop thread_obj = threadObj(); 3138 if (thread_obj != NULL) { 3139 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3140 if (thread_group != NULL) { 3141 oop parent = java_lang_ThreadGroup::parent(thread_group); 3142 if (parent != NULL) { 3143 // ThreadGroup.name can be null 3144 return java_lang_ThreadGroup::name(parent); 3145 } 3146 } 3147 } 3148 return NULL; 3149 } 3150 3151 ThreadPriority JavaThread::java_priority() const { 3152 oop thr_oop = threadObj(); 3153 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3154 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3155 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3156 return priority; 3157 } 3158 3159 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3160 3161 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3162 // Link Java Thread object <-> C++ Thread 3163 3164 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3165 // and put it into a new Handle. The Handle "thread_oop" can then 3166 // be used to pass the C++ thread object to other methods. 3167 3168 // Set the Java level thread object (jthread) field of the 3169 // new thread (a JavaThread *) to C++ thread object using the 3170 // "thread_oop" handle. 3171 3172 // Set the thread field (a JavaThread *) of the 3173 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3174 3175 Handle thread_oop(Thread::current(), 3176 JNIHandles::resolve_non_null(jni_thread)); 3177 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3178 "must be initialized"); 3179 set_threadObj(thread_oop()); 3180 java_lang_Thread::set_thread(thread_oop(), this); 3181 3182 if (prio == NoPriority) { 3183 prio = java_lang_Thread::priority(thread_oop()); 3184 assert(prio != NoPriority, "A valid priority should be present"); 3185 } 3186 3187 // Push the Java priority down to the native thread; needs Threads_lock 3188 Thread::set_priority(this, prio); 3189 3190 // Add the new thread to the Threads list and set it in motion. 3191 // We must have threads lock in order to call Threads::add. 3192 // It is crucial that we do not block before the thread is 3193 // added to the Threads list for if a GC happens, then the java_thread oop 3194 // will not be visited by GC. 3195 Threads::add(this); 3196 } 3197 3198 oop JavaThread::current_park_blocker() { 3199 // Support for JSR-166 locks 3200 oop thread_oop = threadObj(); 3201 if (thread_oop != NULL && 3202 JDK_Version::current().supports_thread_park_blocker()) { 3203 return java_lang_Thread::park_blocker(thread_oop); 3204 } 3205 return NULL; 3206 } 3207 3208 3209 void JavaThread::print_stack_on(outputStream* st) { 3210 if (!has_last_Java_frame()) return; 3211 ResourceMark rm; 3212 HandleMark hm; 3213 3214 RegisterMap reg_map(this); 3215 vframe* start_vf = last_java_vframe(®_map); 3216 int count = 0; 3217 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3218 if (f->is_java_frame()) { 3219 javaVFrame* jvf = javaVFrame::cast(f); 3220 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3221 3222 // Print out lock information 3223 if (JavaMonitorsInStackTrace) { 3224 jvf->print_lock_info_on(st, count); 3225 } 3226 } else { 3227 // Ignore non-Java frames 3228 } 3229 3230 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3231 count++; 3232 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3233 } 3234 } 3235 3236 3237 // JVMTI PopFrame support 3238 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3239 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3240 if (in_bytes(size_in_bytes) != 0) { 3241 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3242 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3243 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3244 } 3245 } 3246 3247 void* JavaThread::popframe_preserved_args() { 3248 return _popframe_preserved_args; 3249 } 3250 3251 ByteSize JavaThread::popframe_preserved_args_size() { 3252 return in_ByteSize(_popframe_preserved_args_size); 3253 } 3254 3255 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3256 int sz = in_bytes(popframe_preserved_args_size()); 3257 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3258 return in_WordSize(sz / wordSize); 3259 } 3260 3261 void JavaThread::popframe_free_preserved_args() { 3262 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3263 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3264 _popframe_preserved_args = NULL; 3265 _popframe_preserved_args_size = 0; 3266 } 3267 3268 #ifndef PRODUCT 3269 3270 void JavaThread::trace_frames() { 3271 tty->print_cr("[Describe stack]"); 3272 int frame_no = 1; 3273 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3274 tty->print(" %d. ", frame_no++); 3275 fst.current()->print_value_on(tty, this); 3276 tty->cr(); 3277 } 3278 } 3279 3280 class PrintAndVerifyOopClosure: public OopClosure { 3281 protected: 3282 template <class T> inline void do_oop_work(T* p) { 3283 oop obj = RawAccess<>::oop_load(p); 3284 if (obj == NULL) return; 3285 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3286 if (oopDesc::is_oop_or_null(obj)) { 3287 if (obj->is_objArray()) { 3288 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3289 } else { 3290 obj->print(); 3291 } 3292 } else { 3293 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3294 } 3295 tty->cr(); 3296 } 3297 public: 3298 virtual void do_oop(oop* p) { do_oop_work(p); } 3299 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3300 }; 3301 3302 3303 static void oops_print(frame* f, const RegisterMap *map) { 3304 PrintAndVerifyOopClosure print; 3305 f->print_value(); 3306 f->oops_do(&print, NULL, (RegisterMap*)map); 3307 } 3308 3309 // Print our all the locations that contain oops and whether they are 3310 // valid or not. This useful when trying to find the oldest frame 3311 // where an oop has gone bad since the frame walk is from youngest to 3312 // oldest. 3313 void JavaThread::trace_oops() { 3314 tty->print_cr("[Trace oops]"); 3315 frames_do(oops_print); 3316 } 3317 3318 3319 #ifdef ASSERT 3320 // Print or validate the layout of stack frames 3321 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3322 ResourceMark rm; 3323 PRESERVE_EXCEPTION_MARK; 3324 FrameValues values; 3325 int frame_no = 0; 3326 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3327 fst.current()->describe(values, ++frame_no); 3328 if (depth == frame_no) break; 3329 } 3330 if (validate_only) { 3331 values.validate(); 3332 } else { 3333 tty->print_cr("[Describe stack layout]"); 3334 values.print(this); 3335 } 3336 } 3337 #endif 3338 3339 void JavaThread::trace_stack_from(vframe* start_vf) { 3340 ResourceMark rm; 3341 int vframe_no = 1; 3342 for (vframe* f = start_vf; f; f = f->sender()) { 3343 if (f->is_java_frame()) { 3344 javaVFrame::cast(f)->print_activation(vframe_no++); 3345 } else { 3346 f->print(); 3347 } 3348 if (vframe_no > StackPrintLimit) { 3349 tty->print_cr("...<more frames>..."); 3350 return; 3351 } 3352 } 3353 } 3354 3355 3356 void JavaThread::trace_stack() { 3357 if (!has_last_Java_frame()) return; 3358 ResourceMark rm; 3359 HandleMark hm; 3360 RegisterMap reg_map(this); 3361 trace_stack_from(last_java_vframe(®_map)); 3362 } 3363 3364 3365 #endif // PRODUCT 3366 3367 3368 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3369 assert(reg_map != NULL, "a map must be given"); 3370 frame f = last_frame(); 3371 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3372 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3373 } 3374 return NULL; 3375 } 3376 3377 3378 Klass* JavaThread::security_get_caller_class(int depth) { 3379 vframeStream vfst(this); 3380 vfst.security_get_caller_frame(depth); 3381 if (!vfst.at_end()) { 3382 return vfst.method()->method_holder(); 3383 } 3384 return NULL; 3385 } 3386 3387 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3388 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3389 CompileBroker::compiler_thread_loop(); 3390 } 3391 3392 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3393 NMethodSweeper::sweeper_loop(); 3394 } 3395 3396 // Create a CompilerThread 3397 CompilerThread::CompilerThread(CompileQueue* queue, 3398 CompilerCounters* counters) 3399 : JavaThread(&compiler_thread_entry) { 3400 _env = NULL; 3401 _log = NULL; 3402 _task = NULL; 3403 _queue = queue; 3404 _counters = counters; 3405 _buffer_blob = NULL; 3406 _compiler = NULL; 3407 3408 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3409 resource_area()->bias_to(mtCompiler); 3410 3411 #ifndef PRODUCT 3412 _ideal_graph_printer = NULL; 3413 #endif 3414 } 3415 3416 CompilerThread::~CompilerThread() { 3417 // Delete objects which were allocated on heap. 3418 delete _counters; 3419 } 3420 3421 bool CompilerThread::can_call_java() const { 3422 return _compiler != NULL && _compiler->is_jvmci(); 3423 } 3424 3425 // Create sweeper thread 3426 CodeCacheSweeperThread::CodeCacheSweeperThread() 3427 : JavaThread(&sweeper_thread_entry) { 3428 _scanned_compiled_method = NULL; 3429 } 3430 3431 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3432 JavaThread::oops_do(f, cf); 3433 if (_scanned_compiled_method != NULL && cf != NULL) { 3434 // Safepoints can occur when the sweeper is scanning an nmethod so 3435 // process it here to make sure it isn't unloaded in the middle of 3436 // a scan. 3437 cf->do_code_blob(_scanned_compiled_method); 3438 } 3439 } 3440 3441 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3442 JavaThread::nmethods_do(cf); 3443 if (_scanned_compiled_method != NULL && cf != NULL) { 3444 // Safepoints can occur when the sweeper is scanning an nmethod so 3445 // process it here to make sure it isn't unloaded in the middle of 3446 // a scan. 3447 cf->do_code_blob(_scanned_compiled_method); 3448 } 3449 } 3450 3451 3452 // ======= Threads ======== 3453 3454 // The Threads class links together all active threads, and provides 3455 // operations over all threads. It is protected by the Threads_lock, 3456 // which is also used in other global contexts like safepointing. 3457 // ThreadsListHandles are used to safely perform operations on one 3458 // or more threads without the risk of the thread exiting during the 3459 // operation. 3460 // 3461 // Note: The Threads_lock is currently more widely used than we 3462 // would like. We are actively migrating Threads_lock uses to other 3463 // mechanisms in order to reduce Threads_lock contention. 3464 3465 JavaThread* Threads::_thread_list = NULL; 3466 int Threads::_number_of_threads = 0; 3467 int Threads::_number_of_non_daemon_threads = 0; 3468 int Threads::_return_code = 0; 3469 int Threads::_thread_claim_parity = 0; 3470 size_t JavaThread::_stack_size_at_create = 0; 3471 3472 #ifdef ASSERT 3473 bool Threads::_vm_complete = false; 3474 #endif 3475 3476 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3477 Prefetch::read((void*)addr, prefetch_interval); 3478 return *addr; 3479 } 3480 3481 // Possibly the ugliest for loop the world has seen. C++ does not allow 3482 // multiple types in the declaration section of the for loop. In this case 3483 // we are only dealing with pointers and hence can cast them. It looks ugly 3484 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3485 #define DO_JAVA_THREADS(LIST, X) \ 3486 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3487 *MACRO_list = (JavaThread*)(LIST), \ 3488 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3489 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3490 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3491 MACRO_current_p != MACRO_end; \ 3492 MACRO_current_p++, \ 3493 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3494 3495 // All JavaThreads 3496 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3497 3498 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3499 void Threads::non_java_threads_do(ThreadClosure* tc) { 3500 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3501 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3502 tc->do_thread(njti.current()); 3503 } 3504 } 3505 3506 // All JavaThreads 3507 void Threads::java_threads_do(ThreadClosure* tc) { 3508 assert_locked_or_safepoint(Threads_lock); 3509 // ALL_JAVA_THREADS iterates through all JavaThreads. 3510 ALL_JAVA_THREADS(p) { 3511 tc->do_thread(p); 3512 } 3513 } 3514 3515 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3516 assert_locked_or_safepoint(Threads_lock); 3517 java_threads_do(tc); 3518 tc->do_thread(VMThread::vm_thread()); 3519 } 3520 3521 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3522 void Threads::threads_do(ThreadClosure* tc) { 3523 assert_locked_or_safepoint(Threads_lock); 3524 java_threads_do(tc); 3525 non_java_threads_do(tc); 3526 } 3527 3528 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3529 int cp = Threads::thread_claim_parity(); 3530 ALL_JAVA_THREADS(p) { 3531 if (p->claim_oops_do(is_par, cp)) { 3532 tc->do_thread(p); 3533 } 3534 } 3535 VMThread* vmt = VMThread::vm_thread(); 3536 if (vmt->claim_oops_do(is_par, cp)) { 3537 tc->do_thread(vmt); 3538 } 3539 } 3540 3541 // The system initialization in the library has three phases. 3542 // 3543 // Phase 1: java.lang.System class initialization 3544 // java.lang.System is a primordial class loaded and initialized 3545 // by the VM early during startup. java.lang.System.<clinit> 3546 // only does registerNatives and keeps the rest of the class 3547 // initialization work later until thread initialization completes. 3548 // 3549 // System.initPhase1 initializes the system properties, the static 3550 // fields in, out, and err. Set up java signal handlers, OS-specific 3551 // system settings, and thread group of the main thread. 3552 static void call_initPhase1(TRAPS) { 3553 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3554 JavaValue result(T_VOID); 3555 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3556 vmSymbols::void_method_signature(), CHECK); 3557 } 3558 3559 // Phase 2. Module system initialization 3560 // This will initialize the module system. Only java.base classes 3561 // can be loaded until phase 2 completes. 3562 // 3563 // Call System.initPhase2 after the compiler initialization and jsr292 3564 // classes get initialized because module initialization runs a lot of java 3565 // code, that for performance reasons, should be compiled. Also, this will 3566 // enable the startup code to use lambda and other language features in this 3567 // phase and onward. 3568 // 3569 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3570 static void call_initPhase2(TRAPS) { 3571 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3572 3573 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3574 3575 JavaValue result(T_INT); 3576 JavaCallArguments args; 3577 args.push_int(DisplayVMOutputToStderr); 3578 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3579 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3580 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3581 if (result.get_jint() != JNI_OK) { 3582 vm_exit_during_initialization(); // no message or exception 3583 } 3584 3585 universe_post_module_init(); 3586 } 3587 3588 // Phase 3. final setup - set security manager, system class loader and TCCL 3589 // 3590 // This will instantiate and set the security manager, set the system class 3591 // loader as well as the thread context class loader. The security manager 3592 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3593 // other modules or the application's classpath. 3594 static void call_initPhase3(TRAPS) { 3595 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3596 JavaValue result(T_VOID); 3597 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3598 vmSymbols::void_method_signature(), CHECK); 3599 } 3600 3601 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3602 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3603 3604 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3605 create_vm_init_libraries(); 3606 } 3607 3608 initialize_class(vmSymbols::java_lang_String(), CHECK); 3609 3610 // Inject CompactStrings value after the static initializers for String ran. 3611 java_lang_String::set_compact_strings(CompactStrings); 3612 3613 // Initialize java_lang.System (needed before creating the thread) 3614 initialize_class(vmSymbols::java_lang_System(), CHECK); 3615 // The VM creates & returns objects of this class. Make sure it's initialized. 3616 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3617 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3618 Handle thread_group = create_initial_thread_group(CHECK); 3619 Universe::set_main_thread_group(thread_group()); 3620 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3621 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3622 main_thread->set_threadObj(thread_object); 3623 // Set thread status to running since main thread has 3624 // been started and running. 3625 java_lang_Thread::set_thread_status(thread_object, 3626 java_lang_Thread::RUNNABLE); 3627 3628 // The VM creates objects of this class. 3629 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3630 3631 // The VM preresolves methods to these classes. Make sure that they get initialized 3632 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3633 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3634 3635 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3636 call_initPhase1(CHECK); 3637 3638 // get the Java runtime name after java.lang.System is initialized 3639 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3640 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3641 3642 // an instance of OutOfMemory exception has been allocated earlier 3643 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3644 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3645 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3646 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3647 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3648 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3649 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3650 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3651 } 3652 3653 void Threads::initialize_jsr292_core_classes(TRAPS) { 3654 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3655 3656 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3657 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3658 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3659 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3660 } 3661 3662 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3663 extern void JDK_Version_init(); 3664 3665 // Preinitialize version info. 3666 VM_Version::early_initialize(); 3667 3668 // Check version 3669 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3670 3671 // Initialize library-based TLS 3672 ThreadLocalStorage::init(); 3673 3674 // Initialize the output stream module 3675 ostream_init(); 3676 3677 // Process java launcher properties. 3678 Arguments::process_sun_java_launcher_properties(args); 3679 3680 // Initialize the os module 3681 os::init(); 3682 3683 // Record VM creation timing statistics 3684 TraceVmCreationTime create_vm_timer; 3685 create_vm_timer.start(); 3686 3687 // Initialize system properties. 3688 Arguments::init_system_properties(); 3689 3690 // So that JDK version can be used as a discriminator when parsing arguments 3691 JDK_Version_init(); 3692 3693 // Update/Initialize System properties after JDK version number is known 3694 Arguments::init_version_specific_system_properties(); 3695 3696 // Make sure to initialize log configuration *before* parsing arguments 3697 LogConfiguration::initialize(create_vm_timer.begin_time()); 3698 3699 // Parse arguments 3700 // Note: this internally calls os::init_container_support() 3701 jint parse_result = Arguments::parse(args); 3702 if (parse_result != JNI_OK) return parse_result; 3703 3704 os::init_before_ergo(); 3705 3706 jint ergo_result = Arguments::apply_ergo(); 3707 if (ergo_result != JNI_OK) return ergo_result; 3708 3709 // Final check of all ranges after ergonomics which may change values. 3710 if (!JVMFlagRangeList::check_ranges()) { 3711 return JNI_EINVAL; 3712 } 3713 3714 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3715 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3716 if (!constraint_result) { 3717 return JNI_EINVAL; 3718 } 3719 3720 JVMFlagWriteableList::mark_startup(); 3721 3722 if (PauseAtStartup) { 3723 os::pause(); 3724 } 3725 3726 HOTSPOT_VM_INIT_BEGIN(); 3727 3728 // Timing (must come after argument parsing) 3729 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3730 3731 // Initialize the os module after parsing the args 3732 jint os_init_2_result = os::init_2(); 3733 if (os_init_2_result != JNI_OK) return os_init_2_result; 3734 3735 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3736 // Initialize assert poison page mechanism. 3737 if (ShowRegistersOnAssert) { 3738 initialize_assert_poison(); 3739 } 3740 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3741 3742 SafepointMechanism::initialize(); 3743 3744 jint adjust_after_os_result = Arguments::adjust_after_os(); 3745 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3746 3747 // Initialize output stream logging 3748 ostream_init_log(); 3749 3750 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3751 // Must be before create_vm_init_agents() 3752 if (Arguments::init_libraries_at_startup()) { 3753 convert_vm_init_libraries_to_agents(); 3754 } 3755 3756 // Launch -agentlib/-agentpath and converted -Xrun agents 3757 if (Arguments::init_agents_at_startup()) { 3758 create_vm_init_agents(); 3759 } 3760 3761 // Initialize Threads state 3762 _thread_list = NULL; 3763 _number_of_threads = 0; 3764 _number_of_non_daemon_threads = 0; 3765 3766 // Initialize global data structures and create system classes in heap 3767 vm_init_globals(); 3768 3769 #if INCLUDE_JVMCI 3770 if (JVMCICounterSize > 0) { 3771 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3772 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3773 } else { 3774 JavaThread::_jvmci_old_thread_counters = NULL; 3775 } 3776 #endif // INCLUDE_JVMCI 3777 3778 // Attach the main thread to this os thread 3779 JavaThread* main_thread = new JavaThread(); 3780 main_thread->set_thread_state(_thread_in_vm); 3781 main_thread->initialize_thread_current(); 3782 // must do this before set_active_handles 3783 main_thread->record_stack_base_and_size(); 3784 main_thread->register_thread_stack_with_NMT(); 3785 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3786 3787 if (!main_thread->set_as_starting_thread()) { 3788 vm_shutdown_during_initialization( 3789 "Failed necessary internal allocation. Out of swap space"); 3790 main_thread->smr_delete(); 3791 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3792 return JNI_ENOMEM; 3793 } 3794 3795 // Enable guard page *after* os::create_main_thread(), otherwise it would 3796 // crash Linux VM, see notes in os_linux.cpp. 3797 main_thread->create_stack_guard_pages(); 3798 3799 // Initialize Java-Level synchronization subsystem 3800 ObjectMonitor::Initialize(); 3801 3802 // Initialize global modules 3803 jint status = init_globals(); 3804 if (status != JNI_OK) { 3805 main_thread->smr_delete(); 3806 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3807 return status; 3808 } 3809 3810 JFR_ONLY(Jfr::on_vm_init();) 3811 3812 // Should be done after the heap is fully created 3813 main_thread->cache_global_variables(); 3814 3815 HandleMark hm; 3816 3817 { MutexLocker mu(Threads_lock); 3818 Threads::add(main_thread); 3819 } 3820 3821 // Any JVMTI raw monitors entered in onload will transition into 3822 // real raw monitor. VM is setup enough here for raw monitor enter. 3823 JvmtiExport::transition_pending_onload_raw_monitors(); 3824 3825 // Create the VMThread 3826 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3827 3828 VMThread::create(); 3829 Thread* vmthread = VMThread::vm_thread(); 3830 3831 if (!os::create_thread(vmthread, os::vm_thread)) { 3832 vm_exit_during_initialization("Cannot create VM thread. " 3833 "Out of system resources."); 3834 } 3835 3836 // Wait for the VM thread to become ready, and VMThread::run to initialize 3837 // Monitors can have spurious returns, must always check another state flag 3838 { 3839 MutexLocker ml(Notify_lock); 3840 os::start_thread(vmthread); 3841 while (vmthread->active_handles() == NULL) { 3842 Notify_lock->wait(); 3843 } 3844 } 3845 } 3846 3847 assert(Universe::is_fully_initialized(), "not initialized"); 3848 if (VerifyDuringStartup) { 3849 // Make sure we're starting with a clean slate. 3850 VM_Verify verify_op; 3851 VMThread::execute(&verify_op); 3852 } 3853 3854 // We need this to update the java.vm.info property in case any flags used 3855 // to initially define it have been changed. This is needed for both CDS and 3856 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3857 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3858 // This update must happen before we initialize the java classes, but 3859 // after any initialization logic that might modify the flags. 3860 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3861 3862 Thread* THREAD = Thread::current(); 3863 3864 // Always call even when there are not JVMTI environments yet, since environments 3865 // may be attached late and JVMTI must track phases of VM execution 3866 JvmtiExport::enter_early_start_phase(); 3867 3868 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3869 JvmtiExport::post_early_vm_start(); 3870 3871 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3872 3873 quicken_jni_functions(); 3874 3875 // No more stub generation allowed after that point. 3876 StubCodeDesc::freeze(); 3877 3878 // Set flag that basic initialization has completed. Used by exceptions and various 3879 // debug stuff, that does not work until all basic classes have been initialized. 3880 set_init_completed(); 3881 3882 LogConfiguration::post_initialize(); 3883 Metaspace::post_initialize(); 3884 3885 HOTSPOT_VM_INIT_END(); 3886 3887 // record VM initialization completion time 3888 #if INCLUDE_MANAGEMENT 3889 Management::record_vm_init_completed(); 3890 #endif // INCLUDE_MANAGEMENT 3891 3892 // Signal Dispatcher needs to be started before VMInit event is posted 3893 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3894 3895 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3896 if (!DisableAttachMechanism) { 3897 AttachListener::vm_start(); 3898 if (StartAttachListener || AttachListener::init_at_startup()) { 3899 AttachListener::init(); 3900 } 3901 } 3902 3903 // Launch -Xrun agents 3904 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3905 // back-end can launch with -Xdebug -Xrunjdwp. 3906 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3907 create_vm_init_libraries(); 3908 } 3909 3910 if (CleanChunkPoolAsync) { 3911 Chunk::start_chunk_pool_cleaner_task(); 3912 } 3913 3914 // initialize compiler(s) 3915 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3916 #if INCLUDE_JVMCI 3917 bool force_JVMCI_intialization = false; 3918 if (EnableJVMCI) { 3919 // Initialize JVMCI eagerly when it is explicitly requested. 3920 // Or when JVMCIPrintProperties is enabled. 3921 // The JVMCI Java initialization code will read this flag and 3922 // do the printing if it's set. 3923 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3924 3925 if (!force_JVMCI_intialization) { 3926 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3927 // compilations via JVMCI will not actually block until JVMCI is initialized. 3928 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3929 } 3930 } 3931 #endif 3932 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3933 // Postpone completion of compiler initialization to after JVMCI 3934 // is initialized to avoid timeouts of blocking compilations. 3935 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3936 CompileBroker::compilation_init_phase2(); 3937 } 3938 #endif 3939 3940 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3941 // It is done after compilers are initialized, because otherwise compilations of 3942 // signature polymorphic MH intrinsics can be missed 3943 // (see SystemDictionary::find_method_handle_intrinsic). 3944 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3945 3946 // This will initialize the module system. Only java.base classes can be 3947 // loaded until phase 2 completes 3948 call_initPhase2(CHECK_JNI_ERR); 3949 3950 // Always call even when there are not JVMTI environments yet, since environments 3951 // may be attached late and JVMTI must track phases of VM execution 3952 JvmtiExport::enter_start_phase(); 3953 3954 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3955 JvmtiExport::post_vm_start(); 3956 3957 // Final system initialization including security manager and system class loader 3958 call_initPhase3(CHECK_JNI_ERR); 3959 3960 // cache the system and platform class loaders 3961 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3962 3963 #if INCLUDE_CDS 3964 if (DumpSharedSpaces) { 3965 // capture the module path info from the ModuleEntryTable 3966 ClassLoader::initialize_module_path(THREAD); 3967 } 3968 #endif 3969 3970 #if INCLUDE_JVMCI 3971 if (force_JVMCI_intialization) { 3972 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3973 CompileBroker::compilation_init_phase2(); 3974 } 3975 #endif 3976 3977 // Always call even when there are not JVMTI environments yet, since environments 3978 // may be attached late and JVMTI must track phases of VM execution 3979 JvmtiExport::enter_live_phase(); 3980 3981 // Make perfmemory accessible 3982 PerfMemory::set_accessible(true); 3983 3984 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3985 JvmtiExport::post_vm_initialized(); 3986 3987 JFR_ONLY(Jfr::on_vm_start();) 3988 3989 #if INCLUDE_MANAGEMENT 3990 Management::initialize(THREAD); 3991 3992 if (HAS_PENDING_EXCEPTION) { 3993 // management agent fails to start possibly due to 3994 // configuration problem and is responsible for printing 3995 // stack trace if appropriate. Simply exit VM. 3996 vm_exit(1); 3997 } 3998 #endif // INCLUDE_MANAGEMENT 3999 4000 if (MemProfiling) MemProfiler::engage(); 4001 StatSampler::engage(); 4002 if (CheckJNICalls) JniPeriodicChecker::engage(); 4003 4004 BiasedLocking::init(); 4005 4006 #if INCLUDE_RTM_OPT 4007 RTMLockingCounters::init(); 4008 #endif 4009 4010 if (JDK_Version::current().post_vm_init_hook_enabled()) { 4011 call_postVMInitHook(THREAD); 4012 // The Java side of PostVMInitHook.run must deal with all 4013 // exceptions and provide means of diagnosis. 4014 if (HAS_PENDING_EXCEPTION) { 4015 CLEAR_PENDING_EXCEPTION; 4016 } 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_method_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 { MutexLocker 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 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4325 Mutex::_as_suspend_equivalent_flag); 4326 } 4327 4328 EventShutdown e; 4329 if (e.should_commit()) { 4330 e.set_reason("No remaining non-daemon Java threads"); 4331 e.commit(); 4332 } 4333 4334 // Hang forever on exit if we are reporting an error. 4335 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4336 os::infinite_sleep(); 4337 } 4338 os::wait_for_keypress_at_exit(); 4339 4340 // run Java level shutdown hooks 4341 thread->invoke_shutdown_hooks(); 4342 4343 before_exit(thread); 4344 4345 thread->exit(true); 4346 4347 // Stop VM thread. 4348 { 4349 // 4945125 The vm thread comes to a safepoint during exit. 4350 // GC vm_operations can get caught at the safepoint, and the 4351 // heap is unparseable if they are caught. Grab the Heap_lock 4352 // to prevent this. The GC vm_operations will not be able to 4353 // queue until after the vm thread is dead. After this point, 4354 // we'll never emerge out of the safepoint before the VM exits. 4355 4356 MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4357 4358 VMThread::wait_for_vm_thread_exit(); 4359 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4360 VMThread::destroy(); 4361 } 4362 4363 // Now, all Java threads are gone except daemon threads. Daemon threads 4364 // running Java code or in VM are stopped by the Safepoint. However, 4365 // daemon threads executing native code are still running. But they 4366 // will be stopped at native=>Java/VM barriers. Note that we can't 4367 // simply kill or suspend them, as it is inherently deadlock-prone. 4368 4369 VM_Exit::set_vm_exited(); 4370 4371 // Clean up ideal graph printers after the VMThread has started 4372 // the final safepoint which will block all the Compiler threads. 4373 // Note that this Thread has already logically exited so the 4374 // clean_up() function's use of a JavaThreadIteratorWithHandle 4375 // would be a problem except set_vm_exited() has remembered the 4376 // shutdown thread which is granted a policy exception. 4377 #if defined(COMPILER2) && !defined(PRODUCT) 4378 IdealGraphPrinter::clean_up(); 4379 #endif 4380 4381 notify_vm_shutdown(); 4382 4383 // exit_globals() will delete tty 4384 exit_globals(); 4385 4386 // We are after VM_Exit::set_vm_exited() so we can't call 4387 // thread->smr_delete() or we will block on the Threads_lock. 4388 // Deleting the shutdown thread here is safe because another 4389 // JavaThread cannot have an active ThreadsListHandle for 4390 // this JavaThread. 4391 delete thread; 4392 4393 #if INCLUDE_JVMCI 4394 if (JVMCICounterSize > 0) { 4395 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4396 } 4397 #endif 4398 4399 LogConfiguration::finalize(); 4400 4401 return true; 4402 } 4403 4404 4405 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4406 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4407 return is_supported_jni_version(version); 4408 } 4409 4410 4411 jboolean Threads::is_supported_jni_version(jint version) { 4412 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4413 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4414 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4415 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4416 if (version == JNI_VERSION_9) return JNI_TRUE; 4417 if (version == JNI_VERSION_10) return JNI_TRUE; 4418 return JNI_FALSE; 4419 } 4420 4421 4422 void Threads::add(JavaThread* p, bool force_daemon) { 4423 // The threads lock must be owned at this point 4424 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4425 4426 BarrierSet::barrier_set()->on_thread_attach(p); 4427 4428 p->set_next(_thread_list); 4429 _thread_list = p; 4430 4431 // Once a JavaThread is added to the Threads list, smr_delete() has 4432 // to be used to delete it. Otherwise we can just delete it directly. 4433 p->set_on_thread_list(); 4434 4435 _number_of_threads++; 4436 oop threadObj = p->threadObj(); 4437 bool daemon = true; 4438 // Bootstrapping problem: threadObj can be null for initial 4439 // JavaThread (or for threads attached via JNI) 4440 if ((!force_daemon) && !is_daemon((threadObj))) { 4441 _number_of_non_daemon_threads++; 4442 daemon = false; 4443 } 4444 4445 ThreadService::add_thread(p, daemon); 4446 4447 // Maintain fast thread list 4448 ThreadsSMRSupport::add_thread(p); 4449 4450 // Possible GC point. 4451 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4452 } 4453 4454 void Threads::remove(JavaThread* p) { 4455 4456 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4457 ObjectSynchronizer::omFlush(p); 4458 4459 // Extra scope needed for Thread_lock, so we can check 4460 // that we do not remove thread without safepoint code notice 4461 { MutexLocker ml(Threads_lock); 4462 4463 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4464 4465 // Maintain fast thread list 4466 ThreadsSMRSupport::remove_thread(p); 4467 4468 JavaThread* current = _thread_list; 4469 JavaThread* prev = NULL; 4470 4471 while (current != p) { 4472 prev = current; 4473 current = current->next(); 4474 } 4475 4476 if (prev) { 4477 prev->set_next(current->next()); 4478 } else { 4479 _thread_list = p->next(); 4480 } 4481 4482 _number_of_threads--; 4483 oop threadObj = p->threadObj(); 4484 bool daemon = true; 4485 if (!is_daemon(threadObj)) { 4486 _number_of_non_daemon_threads--; 4487 daemon = false; 4488 4489 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4490 // on destroy_vm will wake up. 4491 if (number_of_non_daemon_threads() == 1) { 4492 Threads_lock->notify_all(); 4493 } 4494 } 4495 ThreadService::remove_thread(p, daemon); 4496 4497 // Make sure that safepoint code disregard this thread. This is needed since 4498 // the thread might mess around with locks after this point. This can cause it 4499 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4500 // of this thread since it is removed from the queue. 4501 p->set_terminated_value(); 4502 } // unlock Threads_lock 4503 4504 // Since Events::log uses a lock, we grab it outside the Threads_lock 4505 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4506 } 4507 4508 // Operations on the Threads list for GC. These are not explicitly locked, 4509 // but the garbage collector must provide a safe context for them to run. 4510 // In particular, these things should never be called when the Threads_lock 4511 // is held by some other thread. (Note: the Safepoint abstraction also 4512 // uses the Threads_lock to guarantee this property. It also makes sure that 4513 // all threads gets blocked when exiting or starting). 4514 4515 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4516 ALL_JAVA_THREADS(p) { 4517 p->oops_do(f, cf); 4518 } 4519 VMThread::vm_thread()->oops_do(f, cf); 4520 } 4521 4522 void Threads::change_thread_claim_parity() { 4523 // Set the new claim parity. 4524 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4525 "Not in range."); 4526 _thread_claim_parity++; 4527 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4528 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4529 "Not in range."); 4530 } 4531 4532 #ifdef ASSERT 4533 void Threads::assert_all_threads_claimed() { 4534 ALL_JAVA_THREADS(p) { 4535 const int thread_parity = p->oops_do_parity(); 4536 assert((thread_parity == _thread_claim_parity), 4537 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4538 } 4539 VMThread* vmt = VMThread::vm_thread(); 4540 const int thread_parity = vmt->oops_do_parity(); 4541 assert((thread_parity == _thread_claim_parity), 4542 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4543 } 4544 #endif // ASSERT 4545 4546 class ParallelOopsDoThreadClosure : public ThreadClosure { 4547 private: 4548 OopClosure* _f; 4549 CodeBlobClosure* _cf; 4550 public: 4551 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4552 void do_thread(Thread* t) { 4553 t->oops_do(_f, _cf); 4554 } 4555 }; 4556 4557 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4558 ParallelOopsDoThreadClosure tc(f, cf); 4559 possibly_parallel_threads_do(is_par, &tc); 4560 } 4561 4562 void Threads::nmethods_do(CodeBlobClosure* cf) { 4563 ALL_JAVA_THREADS(p) { 4564 // This is used by the code cache sweeper to mark nmethods that are active 4565 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4566 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4567 if(!p->is_Code_cache_sweeper_thread()) { 4568 p->nmethods_do(cf); 4569 } 4570 } 4571 } 4572 4573 void Threads::metadata_do(void f(Metadata*)) { 4574 ALL_JAVA_THREADS(p) { 4575 p->metadata_do(f); 4576 } 4577 } 4578 4579 class ThreadHandlesClosure : public ThreadClosure { 4580 void (*_f)(Metadata*); 4581 public: 4582 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4583 virtual void do_thread(Thread* thread) { 4584 thread->metadata_handles_do(_f); 4585 } 4586 }; 4587 4588 void Threads::metadata_handles_do(void f(Metadata*)) { 4589 // Only walk the Handles in Thread. 4590 ThreadHandlesClosure handles_closure(f); 4591 threads_do(&handles_closure); 4592 } 4593 4594 void Threads::deoptimized_wrt_marked_nmethods() { 4595 ALL_JAVA_THREADS(p) { 4596 p->deoptimized_wrt_marked_nmethods(); 4597 } 4598 } 4599 4600 4601 // Get count Java threads that are waiting to enter the specified monitor. 4602 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4603 int count, 4604 address monitor) { 4605 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4606 4607 int i = 0; 4608 DO_JAVA_THREADS(t_list, p) { 4609 if (!p->can_call_java()) continue; 4610 4611 address pending = (address)p->current_pending_monitor(); 4612 if (pending == monitor) { // found a match 4613 if (i < count) result->append(p); // save the first count matches 4614 i++; 4615 } 4616 } 4617 4618 return result; 4619 } 4620 4621 4622 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4623 address owner) { 4624 // NULL owner means not locked so we can skip the search 4625 if (owner == NULL) return NULL; 4626 4627 DO_JAVA_THREADS(t_list, p) { 4628 // first, see if owner is the address of a Java thread 4629 if (owner == (address)p) return p; 4630 } 4631 4632 // Cannot assert on lack of success here since this function may be 4633 // used by code that is trying to report useful problem information 4634 // like deadlock detection. 4635 if (UseHeavyMonitors) return NULL; 4636 4637 // If we didn't find a matching Java thread and we didn't force use of 4638 // heavyweight monitors, then the owner is the stack address of the 4639 // Lock Word in the owning Java thread's stack. 4640 // 4641 JavaThread* the_owner = NULL; 4642 DO_JAVA_THREADS(t_list, q) { 4643 if (q->is_lock_owned(owner)) { 4644 the_owner = q; 4645 break; 4646 } 4647 } 4648 4649 // cannot assert on lack of success here; see above comment 4650 return the_owner; 4651 } 4652 4653 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4654 void Threads::print_on(outputStream* st, bool print_stacks, 4655 bool internal_format, bool print_concurrent_locks, 4656 bool print_extended_info) { 4657 char buf[32]; 4658 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4659 4660 st->print_cr("Full thread dump %s (%s %s):", 4661 VM_Version::vm_name(), 4662 VM_Version::vm_release(), 4663 VM_Version::vm_info_string()); 4664 st->cr(); 4665 4666 #if INCLUDE_SERVICES 4667 // Dump concurrent locks 4668 ConcurrentLocksDump concurrent_locks; 4669 if (print_concurrent_locks) { 4670 concurrent_locks.dump_at_safepoint(); 4671 } 4672 #endif // INCLUDE_SERVICES 4673 4674 ThreadsSMRSupport::print_info_on(st); 4675 st->cr(); 4676 4677 ALL_JAVA_THREADS(p) { 4678 ResourceMark rm; 4679 p->print_on(st, print_extended_info); 4680 if (print_stacks) { 4681 if (internal_format) { 4682 p->trace_stack(); 4683 } else { 4684 p->print_stack_on(st); 4685 } 4686 } 4687 st->cr(); 4688 #if INCLUDE_SERVICES 4689 if (print_concurrent_locks) { 4690 concurrent_locks.print_locks_on(p, st); 4691 } 4692 #endif // INCLUDE_SERVICES 4693 } 4694 4695 VMThread::vm_thread()->print_on(st); 4696 st->cr(); 4697 Universe::heap()->print_gc_threads_on(st); 4698 WatcherThread* wt = WatcherThread::watcher_thread(); 4699 if (wt != NULL) { 4700 wt->print_on(st); 4701 st->cr(); 4702 } 4703 4704 st->flush(); 4705 } 4706 4707 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4708 int buflen, bool* found_current) { 4709 if (this_thread != NULL) { 4710 bool is_current = (current == this_thread); 4711 *found_current = *found_current || is_current; 4712 st->print("%s", is_current ? "=>" : " "); 4713 4714 st->print(PTR_FORMAT, p2i(this_thread)); 4715 st->print(" "); 4716 this_thread->print_on_error(st, buf, buflen); 4717 st->cr(); 4718 } 4719 } 4720 4721 class PrintOnErrorClosure : public ThreadClosure { 4722 outputStream* _st; 4723 Thread* _current; 4724 char* _buf; 4725 int _buflen; 4726 bool* _found_current; 4727 public: 4728 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4729 int buflen, bool* found_current) : 4730 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4731 4732 virtual void do_thread(Thread* thread) { 4733 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4734 } 4735 }; 4736 4737 // Threads::print_on_error() is called by fatal error handler. It's possible 4738 // that VM is not at safepoint and/or current thread is inside signal handler. 4739 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4740 // memory (even in resource area), it might deadlock the error handler. 4741 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4742 int buflen) { 4743 ThreadsSMRSupport::print_info_on(st); 4744 st->cr(); 4745 4746 bool found_current = false; 4747 st->print_cr("Java Threads: ( => current thread )"); 4748 ALL_JAVA_THREADS(thread) { 4749 print_on_error(thread, st, current, buf, buflen, &found_current); 4750 } 4751 st->cr(); 4752 4753 st->print_cr("Other Threads:"); 4754 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4755 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4756 4757 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4758 Universe::heap()->gc_threads_do(&print_closure); 4759 4760 if (!found_current) { 4761 st->cr(); 4762 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4763 current->print_on_error(st, buf, buflen); 4764 st->cr(); 4765 } 4766 st->cr(); 4767 4768 st->print_cr("Threads with active compile tasks:"); 4769 print_threads_compiling(st, buf, buflen); 4770 } 4771 4772 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4773 ALL_JAVA_THREADS(thread) { 4774 if (thread->is_Compiler_thread()) { 4775 CompilerThread* ct = (CompilerThread*) thread; 4776 4777 // Keep task in local variable for NULL check. 4778 // ct->_task might be set to NULL by concurring compiler thread 4779 // because it completed the compilation. The task is never freed, 4780 // though, just returned to a free list. 4781 CompileTask* task = ct->task(); 4782 if (task != NULL) { 4783 thread->print_name_on_error(st, buf, buflen); 4784 st->print(" "); 4785 task->print(st, NULL, true, true); 4786 } 4787 } 4788 } 4789 } 4790 4791 4792 // Internal SpinLock and Mutex 4793 // Based on ParkEvent 4794 4795 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4796 // 4797 // We employ SpinLocks _only for low-contention, fixed-length 4798 // short-duration critical sections where we're concerned 4799 // about native mutex_t or HotSpot Mutex:: latency. 4800 // The mux construct provides a spin-then-block mutual exclusion 4801 // mechanism. 4802 // 4803 // Testing has shown that contention on the ListLock guarding gFreeList 4804 // is common. If we implement ListLock as a simple SpinLock it's common 4805 // for the JVM to devolve to yielding with little progress. This is true 4806 // despite the fact that the critical sections protected by ListLock are 4807 // extremely short. 4808 // 4809 // TODO-FIXME: ListLock should be of type SpinLock. 4810 // We should make this a 1st-class type, integrated into the lock 4811 // hierarchy as leaf-locks. Critically, the SpinLock structure 4812 // should have sufficient padding to avoid false-sharing and excessive 4813 // cache-coherency traffic. 4814 4815 4816 typedef volatile int SpinLockT; 4817 4818 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4819 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4820 return; // normal fast-path return 4821 } 4822 4823 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4824 int ctr = 0; 4825 int Yields = 0; 4826 for (;;) { 4827 while (*adr != 0) { 4828 ++ctr; 4829 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4830 if (Yields > 5) { 4831 os::naked_short_sleep(1); 4832 } else { 4833 os::naked_yield(); 4834 ++Yields; 4835 } 4836 } else { 4837 SpinPause(); 4838 } 4839 } 4840 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4841 } 4842 } 4843 4844 void Thread::SpinRelease(volatile int * adr) { 4845 assert(*adr != 0, "invariant"); 4846 OrderAccess::fence(); // guarantee at least release consistency. 4847 // Roach-motel semantics. 4848 // It's safe if subsequent LDs and STs float "up" into the critical section, 4849 // but prior LDs and STs within the critical section can't be allowed 4850 // to reorder or float past the ST that releases the lock. 4851 // Loads and stores in the critical section - which appear in program 4852 // order before the store that releases the lock - must also appear 4853 // before the store that releases the lock in memory visibility order. 4854 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4855 // the ST of 0 into the lock-word which releases the lock, so fence 4856 // more than covers this on all platforms. 4857 *adr = 0; 4858 } 4859 4860 // muxAcquire and muxRelease: 4861 // 4862 // * muxAcquire and muxRelease support a single-word lock-word construct. 4863 // The LSB of the word is set IFF the lock is held. 4864 // The remainder of the word points to the head of a singly-linked list 4865 // of threads blocked on the lock. 4866 // 4867 // * The current implementation of muxAcquire-muxRelease uses its own 4868 // dedicated Thread._MuxEvent instance. If we're interested in 4869 // minimizing the peak number of extant ParkEvent instances then 4870 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4871 // as certain invariants were satisfied. Specifically, care would need 4872 // to be taken with regards to consuming unpark() "permits". 4873 // A safe rule of thumb is that a thread would never call muxAcquire() 4874 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4875 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4876 // consume an unpark() permit intended for monitorenter, for instance. 4877 // One way around this would be to widen the restricted-range semaphore 4878 // implemented in park(). Another alternative would be to provide 4879 // multiple instances of the PlatformEvent() for each thread. One 4880 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4881 // 4882 // * Usage: 4883 // -- Only as leaf locks 4884 // -- for short-term locking only as muxAcquire does not perform 4885 // thread state transitions. 4886 // 4887 // Alternatives: 4888 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4889 // but with parking or spin-then-park instead of pure spinning. 4890 // * Use Taura-Oyama-Yonenzawa locks. 4891 // * It's possible to construct a 1-0 lock if we encode the lockword as 4892 // (List,LockByte). Acquire will CAS the full lockword while Release 4893 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4894 // acquiring threads use timers (ParkTimed) to detect and recover from 4895 // the stranding window. Thread/Node structures must be aligned on 256-byte 4896 // boundaries by using placement-new. 4897 // * Augment MCS with advisory back-link fields maintained with CAS(). 4898 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4899 // The validity of the backlinks must be ratified before we trust the value. 4900 // If the backlinks are invalid the exiting thread must back-track through the 4901 // the forward links, which are always trustworthy. 4902 // * Add a successor indication. The LockWord is currently encoded as 4903 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4904 // to provide the usual futile-wakeup optimization. 4905 // See RTStt for details. 4906 // 4907 4908 4909 const intptr_t LOCKBIT = 1; 4910 4911 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4912 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4913 if (w == 0) return; 4914 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4915 return; 4916 } 4917 4918 ParkEvent * const Self = Thread::current()->_MuxEvent; 4919 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4920 for (;;) { 4921 int its = (os::is_MP() ? 100 : 0) + 1; 4922 4923 // Optional spin phase: spin-then-park strategy 4924 while (--its >= 0) { 4925 w = *Lock; 4926 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4927 return; 4928 } 4929 } 4930 4931 Self->reset(); 4932 Self->OnList = intptr_t(Lock); 4933 // The following fence() isn't _strictly necessary as the subsequent 4934 // CAS() both serializes execution and ratifies the fetched *Lock value. 4935 OrderAccess::fence(); 4936 for (;;) { 4937 w = *Lock; 4938 if ((w & LOCKBIT) == 0) { 4939 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4940 Self->OnList = 0; // hygiene - allows stronger asserts 4941 return; 4942 } 4943 continue; // Interference -- *Lock changed -- Just retry 4944 } 4945 assert(w & LOCKBIT, "invariant"); 4946 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4947 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4948 } 4949 4950 while (Self->OnList != 0) { 4951 Self->park(); 4952 } 4953 } 4954 } 4955 4956 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4957 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4958 if (w == 0) return; 4959 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4960 return; 4961 } 4962 4963 ParkEvent * ReleaseAfter = NULL; 4964 if (ev == NULL) { 4965 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4966 } 4967 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4968 for (;;) { 4969 guarantee(ev->OnList == 0, "invariant"); 4970 int its = (os::is_MP() ? 100 : 0) + 1; 4971 4972 // Optional spin phase: spin-then-park strategy 4973 while (--its >= 0) { 4974 w = *Lock; 4975 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4976 if (ReleaseAfter != NULL) { 4977 ParkEvent::Release(ReleaseAfter); 4978 } 4979 return; 4980 } 4981 } 4982 4983 ev->reset(); 4984 ev->OnList = intptr_t(Lock); 4985 // The following fence() isn't _strictly necessary as the subsequent 4986 // CAS() both serializes execution and ratifies the fetched *Lock value. 4987 OrderAccess::fence(); 4988 for (;;) { 4989 w = *Lock; 4990 if ((w & LOCKBIT) == 0) { 4991 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4992 ev->OnList = 0; 4993 // We call ::Release while holding the outer lock, thus 4994 // artificially lengthening the critical section. 4995 // Consider deferring the ::Release() until the subsequent unlock(), 4996 // after we've dropped the outer lock. 4997 if (ReleaseAfter != NULL) { 4998 ParkEvent::Release(ReleaseAfter); 4999 } 5000 return; 5001 } 5002 continue; // Interference -- *Lock changed -- Just retry 5003 } 5004 assert(w & LOCKBIT, "invariant"); 5005 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5006 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 5007 } 5008 5009 while (ev->OnList != 0) { 5010 ev->park(); 5011 } 5012 } 5013 } 5014 5015 // Release() must extract a successor from the list and then wake that thread. 5016 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5017 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5018 // Release() would : 5019 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5020 // (B) Extract a successor from the private list "in-hand" 5021 // (C) attempt to CAS() the residual back into *Lock over null. 5022 // If there were any newly arrived threads and the CAS() would fail. 5023 // In that case Release() would detach the RATs, re-merge the list in-hand 5024 // with the RATs and repeat as needed. Alternately, Release() might 5025 // detach and extract a successor, but then pass the residual list to the wakee. 5026 // The wakee would be responsible for reattaching and remerging before it 5027 // competed for the lock. 5028 // 5029 // Both "pop" and DMR are immune from ABA corruption -- there can be 5030 // multiple concurrent pushers, but only one popper or detacher. 5031 // This implementation pops from the head of the list. This is unfair, 5032 // but tends to provide excellent throughput as hot threads remain hot. 5033 // (We wake recently run threads first). 5034 // 5035 // All paths through muxRelease() will execute a CAS. 5036 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5037 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5038 // executed within the critical section are complete and globally visible before the 5039 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5040 void Thread::muxRelease(volatile intptr_t * Lock) { 5041 for (;;) { 5042 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 5043 assert(w & LOCKBIT, "invariant"); 5044 if (w == LOCKBIT) return; 5045 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5046 assert(List != NULL, "invariant"); 5047 assert(List->OnList == intptr_t(Lock), "invariant"); 5048 ParkEvent * const nxt = List->ListNext; 5049 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5050 5051 // The following CAS() releases the lock and pops the head element. 5052 // The CAS() also ratifies the previously fetched lock-word value. 5053 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 5054 continue; 5055 } 5056 List->OnList = 0; 5057 OrderAccess::fence(); 5058 List->unpark(); 5059 return; 5060 } 5061 } 5062 5063 5064 void Threads::verify() { 5065 ALL_JAVA_THREADS(p) { 5066 p->verify(); 5067 } 5068 VMThread* thread = VMThread::vm_thread(); 5069 if (thread != NULL) thread->verify(); 5070 }