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