rev 57156 : imported patch 8234796-v3
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 "aot/aotLoader.hpp" 28 #include "classfile/classLoader.hpp" 29 #include "classfile/javaClasses.hpp" 30 #include "classfile/moduleEntry.hpp" 31 #include "classfile/systemDictionary.hpp" 32 #include "classfile/vmSymbols.hpp" 33 #include "code/codeCache.hpp" 34 #include "code/scopeDesc.hpp" 35 #include "compiler/compileBroker.hpp" 36 #include "compiler/compileTask.hpp" 37 #include "gc/shared/barrierSet.hpp" 38 #include "gc/shared/gcId.hpp" 39 #include "gc/shared/gcLocker.inline.hpp" 40 #include "gc/shared/workgroup.hpp" 41 #include "interpreter/interpreter.hpp" 42 #include "interpreter/linkResolver.hpp" 43 #include "interpreter/oopMapCache.hpp" 44 #include "jfr/jfrEvents.hpp" 45 #include "jvmtifiles/jvmtiEnv.hpp" 46 #include "logging/log.hpp" 47 #include "logging/logConfiguration.hpp" 48 #include "logging/logStream.hpp" 49 #include "memory/allocation.inline.hpp" 50 #include "memory/metaspaceShared.hpp" 51 #include "memory/oopFactory.hpp" 52 #include "memory/resourceArea.hpp" 53 #include "memory/universe.hpp" 54 #include "oops/access.inline.hpp" 55 #include "oops/instanceKlass.hpp" 56 #include "oops/objArrayOop.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "oops/symbol.hpp" 59 #include "oops/typeArrayOop.inline.hpp" 60 #include "oops/verifyOopClosure.hpp" 61 #include "prims/jvm_misc.hpp" 62 #include "prims/jvmtiExport.hpp" 63 #include "prims/jvmtiThreadState.hpp" 64 #include "runtime/arguments.hpp" 65 #include "runtime/atomic.hpp" 66 #include "runtime/biasedLocking.hpp" 67 #include "runtime/fieldDescriptor.inline.hpp" 68 #include "runtime/flags/jvmFlagConstraintList.hpp" 69 #include "runtime/flags/jvmFlagRangeList.hpp" 70 #include "runtime/flags/jvmFlagWriteableList.hpp" 71 #include "runtime/deoptimization.hpp" 72 #include "runtime/frame.inline.hpp" 73 #include "runtime/handles.inline.hpp" 74 #include "runtime/handshake.hpp" 75 #include "runtime/init.hpp" 76 #include "runtime/interfaceSupport.inline.hpp" 77 #include "runtime/java.hpp" 78 #include "runtime/javaCalls.hpp" 79 #include "runtime/jniHandles.inline.hpp" 80 #include "runtime/jniPeriodicChecker.hpp" 81 #include "runtime/memprofiler.hpp" 82 #include "runtime/mutexLocker.hpp" 83 #include "runtime/objectMonitor.hpp" 84 #include "runtime/orderAccess.hpp" 85 #include "runtime/osThread.hpp" 86 #include "runtime/prefetch.inline.hpp" 87 #include "runtime/safepoint.hpp" 88 #include "runtime/safepointMechanism.inline.hpp" 89 #include "runtime/safepointVerifiers.hpp" 90 #include "runtime/sharedRuntime.hpp" 91 #include "runtime/statSampler.hpp" 92 #include "runtime/stubRoutines.hpp" 93 #include "runtime/sweeper.hpp" 94 #include "runtime/task.hpp" 95 #include "runtime/thread.inline.hpp" 96 #include "runtime/threadCritical.hpp" 97 #include "runtime/threadSMR.inline.hpp" 98 #include "runtime/threadStatisticalInfo.hpp" 99 #include "runtime/timer.hpp" 100 #include "runtime/timerTrace.hpp" 101 #include "runtime/vframe.inline.hpp" 102 #include "runtime/vframeArray.hpp" 103 #include "runtime/vframe_hp.hpp" 104 #include "runtime/vmThread.hpp" 105 #include "runtime/vmOperations.hpp" 106 #include "runtime/vm_version.hpp" 107 #include "services/attachListener.hpp" 108 #include "services/management.hpp" 109 #include "services/memTracker.hpp" 110 #include "services/threadService.hpp" 111 #include "utilities/align.hpp" 112 #include "utilities/copy.hpp" 113 #include "utilities/defaultStream.hpp" 114 #include "utilities/dtrace.hpp" 115 #include "utilities/events.hpp" 116 #include "utilities/macros.hpp" 117 #include "utilities/preserveException.hpp" 118 #include "utilities/singleWriterSynchronizer.hpp" 119 #include "utilities/vmError.hpp" 120 #if INCLUDE_JVMCI 121 #include "jvmci/jvmci.hpp" 122 #include "jvmci/jvmciEnv.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 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 size_t alignment = markWord::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_lgrp_id(-1); 227 DEBUG_ONLY(clear_suspendible_thread();) 228 229 // allocated data structures 230 set_osthread(NULL); 231 set_resource_area(new (mtThread)ResourceArea()); 232 DEBUG_ONLY(_current_resource_mark = NULL;) 233 set_handle_area(new (mtThread) HandleArea(NULL)); 234 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 235 set_active_handles(NULL); 236 set_free_handle_block(NULL); 237 set_last_handle_mark(NULL); 238 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 239 240 // Initial value of zero ==> never claimed. 241 _threads_do_token = 0; 242 _threads_hazard_ptr = NULL; 243 _threads_list_ptr = NULL; 244 _nested_threads_hazard_ptr_cnt = 0; 245 _rcu_counter = 0; 246 247 // the handle mark links itself to last_handle_mark 248 new HandleMark(this); 249 250 // plain initialization 251 debug_only(_owned_locks = NULL;) 252 NOT_PRODUCT(_no_safepoint_count = 0;) 253 NOT_PRODUCT(_skip_gcalot = false;) 254 _jvmti_env_iteration_count = 0; 255 set_allocated_bytes(0); 256 _vm_operation_started_count = 0; 257 _vm_operation_completed_count = 0; 258 _current_pending_monitor = NULL; 259 _current_pending_monitor_is_from_java = true; 260 _current_waiting_monitor = NULL; 261 _current_pending_raw_monitor = NULL; 262 _num_nested_signal = 0; 263 om_free_list = NULL; 264 om_free_count = 0; 265 om_free_provision = 32; 266 om_in_use_list = NULL; 267 om_in_use_count = 0; 268 269 #ifdef ASSERT 270 _visited_for_critical_count = false; 271 #endif 272 273 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 274 Monitor::_safepoint_check_sometimes); 275 _suspend_flags = 0; 276 277 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 278 _hashStateX = os::random(); 279 _hashStateY = 842502087; 280 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 281 _hashStateW = 273326509; 282 283 _OnTrap = 0; 284 _Stalled = 0; 285 _TypeTag = 0x2BAD; 286 287 // Many of the following fields are effectively final - immutable 288 // Note that nascent threads can't use the Native Monitor-Mutex 289 // construct until the _MutexEvent is initialized ... 290 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 291 // we might instead use a stack of ParkEvents that we could provision on-demand. 292 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 293 // and ::Release() 294 _ParkEvent = ParkEvent::Allocate(this); 295 _MuxEvent = ParkEvent::Allocate(this); 296 297 #ifdef CHECK_UNHANDLED_OOPS 298 if (CheckUnhandledOops) { 299 _unhandled_oops = new UnhandledOops(this); 300 } 301 #endif // CHECK_UNHANDLED_OOPS 302 #ifdef ASSERT 303 if (UseBiasedLocking) { 304 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed"); 305 assert(this == _real_malloc_address || 306 this == align_up(_real_malloc_address, markWord::biased_lock_alignment), 307 "bug in forced alignment of thread objects"); 308 } 309 #endif // ASSERT 310 311 // Notify the barrier set that a thread is being created. The initial 312 // thread is created before the barrier set is available. The call to 313 // BarrierSet::on_thread_create() for this thread is therefore deferred 314 // to BarrierSet::set_barrier_set(). 315 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 316 if (barrier_set != NULL) { 317 barrier_set->on_thread_create(this); 318 } else { 319 // Only the main thread should be created before the barrier set 320 // and that happens just before Thread::current is set. No other thread 321 // can attach as the VM is not created yet, so they can't execute this code. 322 // If the main thread creates other threads before the barrier set that is an error. 323 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 324 } 325 } 326 327 void Thread::initialize_thread_current() { 328 #ifndef USE_LIBRARY_BASED_TLS_ONLY 329 assert(_thr_current == NULL, "Thread::current already initialized"); 330 _thr_current = this; 331 #endif 332 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 333 ThreadLocalStorage::set_thread(this); 334 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 335 } 336 337 void Thread::clear_thread_current() { 338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 339 #ifndef USE_LIBRARY_BASED_TLS_ONLY 340 _thr_current = NULL; 341 #endif 342 ThreadLocalStorage::set_thread(NULL); 343 } 344 345 void Thread::record_stack_base_and_size() { 346 // Note: at this point, Thread object is not yet initialized. Do not rely on 347 // any members being initialized. Do not rely on Thread::current() being set. 348 // If possible, refrain from doing anything which may crash or assert since 349 // quite probably those crash dumps will be useless. 350 set_stack_base(os::current_stack_base()); 351 set_stack_size(os::current_stack_size()); 352 353 #ifdef SOLARIS 354 if (os::is_primordial_thread()) { 355 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 356 } 357 #endif 358 359 // Set stack limits after thread is initialized. 360 if (is_Java_thread()) { 361 ((JavaThread*) this)->set_stack_overflow_limit(); 362 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 363 } 364 } 365 366 #if INCLUDE_NMT 367 void Thread::register_thread_stack_with_NMT() { 368 MemTracker::record_thread_stack(stack_end(), stack_size()); 369 } 370 #endif // INCLUDE_NMT 371 372 void Thread::call_run() { 373 DEBUG_ONLY(_run_state = CALL_RUN;) 374 375 // At this point, Thread object should be fully initialized and 376 // Thread::current() should be set. 377 378 assert(Thread::current_or_null() != NULL, "current thread is unset"); 379 assert(Thread::current_or_null() == this, "current thread is wrong"); 380 381 // Perform common initialization actions 382 383 register_thread_stack_with_NMT(); 384 385 JFR_ONLY(Jfr::on_thread_start(this);) 386 387 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 388 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 389 os::current_thread_id(), p2i(stack_base() - stack_size()), 390 p2i(stack_base()), stack_size()/1024); 391 392 // Perform <ChildClass> initialization actions 393 DEBUG_ONLY(_run_state = PRE_RUN;) 394 this->pre_run(); 395 396 // Invoke <ChildClass>::run() 397 DEBUG_ONLY(_run_state = RUN;) 398 this->run(); 399 // Returned from <ChildClass>::run(). Thread finished. 400 401 // Perform common tear-down actions 402 403 assert(Thread::current_or_null() != NULL, "current thread is unset"); 404 assert(Thread::current_or_null() == this, "current thread is wrong"); 405 406 // Perform <ChildClass> tear-down actions 407 DEBUG_ONLY(_run_state = POST_RUN;) 408 this->post_run(); 409 410 // Note: at this point the thread object may already have deleted itself, 411 // so from here on do not dereference *this*. Not all thread types currently 412 // delete themselves when they terminate. But no thread should ever be deleted 413 // asynchronously with respect to its termination - that is what _run_state can 414 // be used to check. 415 416 assert(Thread::current_or_null() == NULL, "current thread still present"); 417 } 418 419 Thread::~Thread() { 420 421 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 422 // get started due to errors etc. Any active thread should at least reach post_run 423 // before it is deleted (usually in post_run()). 424 assert(_run_state == PRE_CALL_RUN || 425 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 426 "_run_state=%d", (int)_run_state); 427 428 // Notify the barrier set that a thread is being destroyed. Note that a barrier 429 // set might not be available if we encountered errors during bootstrapping. 430 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 431 if (barrier_set != NULL) { 432 barrier_set->on_thread_destroy(this); 433 } 434 435 // stack_base can be NULL if the thread is never started or exited before 436 // record_stack_base_and_size called. Although, we would like to ensure 437 // that all started threads do call record_stack_base_and_size(), there is 438 // not proper way to enforce that. 439 #if INCLUDE_NMT 440 if (_stack_base != NULL) { 441 MemTracker::release_thread_stack(stack_end(), stack_size()); 442 #ifdef ASSERT 443 set_stack_base(NULL); 444 #endif 445 } 446 #endif // INCLUDE_NMT 447 448 // deallocate data structures 449 delete resource_area(); 450 // since the handle marks are using the handle area, we have to deallocated the root 451 // handle mark before deallocating the thread's handle area, 452 assert(last_handle_mark() != NULL, "check we have an element"); 453 delete last_handle_mark(); 454 assert(last_handle_mark() == NULL, "check we have reached the end"); 455 456 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 457 // We NULL out the fields for good hygiene. 458 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 459 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 460 461 delete handle_area(); 462 delete metadata_handles(); 463 464 // SR_handler uses this as a termination indicator - 465 // needs to happen before os::free_thread() 466 delete _SR_lock; 467 _SR_lock = NULL; 468 469 // osthread() can be NULL, if creation of thread failed. 470 if (osthread() != NULL) os::free_thread(osthread()); 471 472 // Clear Thread::current if thread is deleting itself and it has not 473 // already been done. This must be done before the memory is deallocated. 474 // Needed to ensure JNI correctly detects non-attached threads. 475 if (this == Thread::current_or_null()) { 476 Thread::clear_thread_current(); 477 } 478 479 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 480 } 481 482 #ifdef ASSERT 483 // A JavaThread is considered "dangling" if it is not the current 484 // thread, has been added the Threads list, the system is not at a 485 // safepoint and the Thread is not "protected". 486 // 487 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 488 assert(!thread->is_Java_thread() || Thread::current() == thread || 489 !((JavaThread *) thread)->on_thread_list() || 490 SafepointSynchronize::is_at_safepoint() || 491 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 492 "possibility of dangling Thread pointer"); 493 } 494 #endif 495 496 ThreadPriority Thread::get_priority(const Thread* const thread) { 497 ThreadPriority priority; 498 // Can return an error! 499 (void)os::get_priority(thread, priority); 500 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 501 return priority; 502 } 503 504 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 505 debug_only(check_for_dangling_thread_pointer(thread);) 506 // Can return an error! 507 (void)os::set_priority(thread, priority); 508 } 509 510 511 void Thread::start(Thread* thread) { 512 // Start is different from resume in that its safety is guaranteed by context or 513 // being called from a Java method synchronized on the Thread object. 514 if (!DisableStartThread) { 515 if (thread->is_Java_thread()) { 516 // Initialize the thread state to RUNNABLE before starting this thread. 517 // Can not set it after the thread started because we do not know the 518 // exact thread state at that time. It could be in MONITOR_WAIT or 519 // in SLEEPING or some other state. 520 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 521 java_lang_Thread::RUNNABLE); 522 } 523 os::start_thread(thread); 524 } 525 } 526 527 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 528 VM_ThreadStop vm_stop(java_thread, java_throwable); 529 VMThread::execute(&vm_stop); 530 } 531 532 533 // Check if an external suspend request has completed (or has been 534 // cancelled). Returns true if the thread is externally suspended and 535 // false otherwise. 536 // 537 // The bits parameter returns information about the code path through 538 // the routine. Useful for debugging: 539 // 540 // set in is_ext_suspend_completed(): 541 // 0x00000001 - routine was entered 542 // 0x00000010 - routine return false at end 543 // 0x00000100 - thread exited (return false) 544 // 0x00000200 - suspend request cancelled (return false) 545 // 0x00000400 - thread suspended (return true) 546 // 0x00001000 - thread is in a suspend equivalent state (return true) 547 // 0x00002000 - thread is native and walkable (return true) 548 // 0x00004000 - thread is native_trans and walkable (needed retry) 549 // 550 // set in wait_for_ext_suspend_completion(): 551 // 0x00010000 - routine was entered 552 // 0x00020000 - suspend request cancelled before loop (return false) 553 // 0x00040000 - thread suspended before loop (return true) 554 // 0x00080000 - suspend request cancelled in loop (return false) 555 // 0x00100000 - thread suspended in loop (return true) 556 // 0x00200000 - suspend not completed during retry loop (return false) 557 558 // Helper class for tracing suspend wait debug bits. 559 // 560 // 0x00000100 indicates that the target thread exited before it could 561 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 562 // 0x00080000 each indicate a cancelled suspend request so they don't 563 // count as wait failures either. 564 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 565 566 class TraceSuspendDebugBits : public StackObj { 567 private: 568 JavaThread * jt; 569 bool is_wait; 570 bool called_by_wait; // meaningful when !is_wait 571 uint32_t * bits; 572 573 public: 574 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 575 uint32_t *_bits) { 576 jt = _jt; 577 is_wait = _is_wait; 578 called_by_wait = _called_by_wait; 579 bits = _bits; 580 } 581 582 ~TraceSuspendDebugBits() { 583 if (!is_wait) { 584 #if 1 585 // By default, don't trace bits for is_ext_suspend_completed() calls. 586 // That trace is very chatty. 587 return; 588 #else 589 if (!called_by_wait) { 590 // If tracing for is_ext_suspend_completed() is enabled, then only 591 // trace calls to it from wait_for_ext_suspend_completion() 592 return; 593 } 594 #endif 595 } 596 597 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 598 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 599 MutexLocker ml(Threads_lock); // needed for get_thread_name() 600 ResourceMark rm; 601 602 tty->print_cr( 603 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 604 jt->get_thread_name(), *bits); 605 606 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 607 } 608 } 609 } 610 }; 611 #undef DEBUG_FALSE_BITS 612 613 614 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 615 uint32_t *bits) { 616 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 617 618 bool did_trans_retry = false; // only do thread_in_native_trans retry once 619 bool do_trans_retry; // flag to force the retry 620 621 *bits |= 0x00000001; 622 623 do { 624 do_trans_retry = false; 625 626 if (is_exiting()) { 627 // Thread is in the process of exiting. This is always checked 628 // first to reduce the risk of dereferencing a freed JavaThread. 629 *bits |= 0x00000100; 630 return false; 631 } 632 633 if (!is_external_suspend()) { 634 // Suspend request is cancelled. This is always checked before 635 // is_ext_suspended() to reduce the risk of a rogue resume 636 // confusing the thread that made the suspend request. 637 *bits |= 0x00000200; 638 return false; 639 } 640 641 if (is_ext_suspended()) { 642 // thread is suspended 643 *bits |= 0x00000400; 644 return true; 645 } 646 647 // Now that we no longer do hard suspends of threads running 648 // native code, the target thread can be changing thread state 649 // while we are in this routine: 650 // 651 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 652 // 653 // We save a copy of the thread state as observed at this moment 654 // and make our decision about suspend completeness based on the 655 // copy. This closes the race where the thread state is seen as 656 // _thread_in_native_trans in the if-thread_blocked check, but is 657 // seen as _thread_blocked in if-thread_in_native_trans check. 658 JavaThreadState save_state = thread_state(); 659 660 if (save_state == _thread_blocked && is_suspend_equivalent()) { 661 // If the thread's state is _thread_blocked and this blocking 662 // condition is known to be equivalent to a suspend, then we can 663 // consider the thread to be externally suspended. This means that 664 // the code that sets _thread_blocked has been modified to do 665 // self-suspension if the blocking condition releases. We also 666 // used to check for CONDVAR_WAIT here, but that is now covered by 667 // the _thread_blocked with self-suspension check. 668 // 669 // Return true since we wouldn't be here unless there was still an 670 // external suspend request. 671 *bits |= 0x00001000; 672 return true; 673 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 674 // Threads running native code will self-suspend on native==>VM/Java 675 // transitions. If its stack is walkable (should always be the case 676 // unless this function is called before the actual java_suspend() 677 // call), then the wait is done. 678 *bits |= 0x00002000; 679 return true; 680 } else if (!called_by_wait && !did_trans_retry && 681 save_state == _thread_in_native_trans && 682 frame_anchor()->walkable()) { 683 // The thread is transitioning from thread_in_native to another 684 // thread state. check_safepoint_and_suspend_for_native_trans() 685 // will force the thread to self-suspend. If it hasn't gotten 686 // there yet we may have caught the thread in-between the native 687 // code check above and the self-suspend. Lucky us. If we were 688 // called by wait_for_ext_suspend_completion(), then it 689 // will be doing the retries so we don't have to. 690 // 691 // Since we use the saved thread state in the if-statement above, 692 // there is a chance that the thread has already transitioned to 693 // _thread_blocked by the time we get here. In that case, we will 694 // make a single unnecessary pass through the logic below. This 695 // doesn't hurt anything since we still do the trans retry. 696 697 *bits |= 0x00004000; 698 699 // Once the thread leaves thread_in_native_trans for another 700 // thread state, we break out of this retry loop. We shouldn't 701 // need this flag to prevent us from getting back here, but 702 // sometimes paranoia is good. 703 did_trans_retry = true; 704 705 // We wait for the thread to transition to a more usable state. 706 for (int i = 1; i <= SuspendRetryCount; i++) { 707 // We used to do an "os::yield_all(i)" call here with the intention 708 // that yielding would increase on each retry. However, the parameter 709 // is ignored on Linux which means the yield didn't scale up. Waiting 710 // on the SR_lock below provides a much more predictable scale up for 711 // the delay. It also provides a simple/direct point to check for any 712 // safepoint requests from the VMThread 713 714 // temporarily drops SR_lock while doing wait with safepoint check 715 // (if we're a JavaThread - the WatcherThread can also call this) 716 // and increase delay with each retry 717 if (Thread::current()->is_Java_thread()) { 718 SR_lock()->wait(i * delay); 719 } else { 720 SR_lock()->wait_without_safepoint_check(i * delay); 721 } 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 MutexLocker 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 Thread* t = Thread::current(); 794 MonitorLocker ml(SR_lock(), 795 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 796 // wait with safepoint check (if we're a JavaThread - the WatcherThread 797 // can also call this) and increase delay with each retry 798 ml.wait(i * delay); 799 800 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 801 delay, bits); 802 803 // It is possible for the external suspend request to be cancelled 804 // (by a resume) before the actual suspend operation is completed. 805 // Refresh our local copy to see if we still need to wait. 806 pending = is_external_suspend(); 807 } 808 809 if (!pending) { 810 // A cancelled suspend request is the only false return from 811 // is_ext_suspend_completed() that keeps us from staying in the 812 // retry loop. 813 *bits |= 0x00080000; 814 return false; 815 } 816 817 if (is_suspended) { 818 *bits |= 0x00100000; 819 return true; 820 } 821 } // end retry loop 822 823 // thread did not suspend after all our retries 824 *bits |= 0x00200000; 825 return false; 826 } 827 828 // Called from API entry points which perform stack walking. If the 829 // associated JavaThread is the current thread, then wait_for_suspend 830 // is not used. Otherwise, it determines if we should wait for the 831 // "other" thread to complete external suspension. (NOTE: in future 832 // releases the suspension mechanism should be reimplemented so this 833 // is not necessary.) 834 // 835 bool 836 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 837 if (this != JavaThread::current()) { 838 // "other" threads require special handling. 839 if (wait_for_suspend) { 840 // We are allowed to wait for the external suspend to complete 841 // so give the other thread a chance to get suspended. 842 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 843 SuspendRetryDelay, bits)) { 844 // Didn't make it so let the caller know. 845 return false; 846 } 847 } 848 // We aren't allowed to wait for the external suspend to complete 849 // so if the other thread isn't externally suspended we need to 850 // let the caller know. 851 else if (!is_ext_suspend_completed_with_lock(bits)) { 852 return false; 853 } 854 } 855 856 return true; 857 } 858 859 // GC Support 860 bool Thread::claim_par_threads_do(uintx claim_token) { 861 uintx token = _threads_do_token; 862 if (token != claim_token) { 863 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token); 864 if (res == token) { 865 return true; 866 } 867 guarantee(res == claim_token, "invariant"); 868 } 869 return false; 870 } 871 872 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 873 active_handles()->oops_do(f); 874 // Do oop for ThreadShadow 875 f->do_oop((oop*)&_pending_exception); 876 handle_area()->oops_do(f); 877 878 // We scan thread local monitor lists here, and the remaining global 879 // monitors in ObjectSynchronizer::oops_do(). 880 ObjectSynchronizer::thread_local_used_oops_do(this, f); 881 } 882 883 void Thread::metadata_handles_do(void f(Metadata*)) { 884 // Only walk the Handles in Thread. 885 if (metadata_handles() != NULL) { 886 for (int i = 0; i< metadata_handles()->length(); i++) { 887 f(metadata_handles()->at(i)); 888 } 889 } 890 } 891 892 void Thread::print_on(outputStream* st, bool print_extended_info) const { 893 // get_priority assumes osthread initialized 894 if (osthread() != NULL) { 895 int os_prio; 896 if (os::get_native_priority(this, &os_prio) == OS_OK) { 897 st->print("os_prio=%d ", os_prio); 898 } 899 900 st->print("cpu=%.2fms ", 901 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 902 ); 903 st->print("elapsed=%.2fs ", 904 _statistical_info.getElapsedTime() / 1000.0 905 ); 906 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 907 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 908 st->print("allocated=" SIZE_FORMAT "%s ", 909 byte_size_in_proper_unit(allocated_bytes), 910 proper_unit_for_byte_size(allocated_bytes) 911 ); 912 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 913 } 914 915 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 916 osthread()->print_on(st); 917 } 918 ThreadsSMRSupport::print_info_on(this, st); 919 st->print(" "); 920 debug_only(if (WizardMode) print_owned_locks_on(st);) 921 } 922 923 void Thread::print() const { print_on(tty); } 924 925 // Thread::print_on_error() is called by fatal error handler. Don't use 926 // any lock or allocate memory. 927 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 928 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 929 930 if (is_VM_thread()) { st->print("VMThread"); } 931 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 932 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 933 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 934 else { st->print("Thread"); } 935 936 if (is_Named_thread()) { 937 st->print(" \"%s\"", name()); 938 } 939 940 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 941 p2i(stack_end()), p2i(stack_base())); 942 943 if (osthread()) { 944 st->print(" [id=%d]", osthread()->thread_id()); 945 } 946 947 ThreadsSMRSupport::print_info_on(this, st); 948 } 949 950 void Thread::print_value_on(outputStream* st) const { 951 if (is_Named_thread()) { 952 st->print(" \"%s\" ", name()); 953 } 954 st->print(INTPTR_FORMAT, p2i(this)); // print address 955 } 956 957 #ifdef ASSERT 958 void Thread::print_owned_locks_on(outputStream* st) const { 959 Mutex* cur = _owned_locks; 960 if (cur == NULL) { 961 st->print(" (no locks) "); 962 } else { 963 st->print_cr(" Locks owned:"); 964 while (cur) { 965 cur->print_on(st); 966 cur = cur->next(); 967 } 968 } 969 } 970 971 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 972 void Thread::check_possible_safepoint() { 973 if (!is_Java_thread()) return; 974 975 if (_no_safepoint_count > 0) { 976 print_owned_locks(); 977 fatal("Possible safepoint reached by thread that does not allow it"); 978 } 979 #ifdef CHECK_UNHANDLED_OOPS 980 // Clear unhandled oops in JavaThreads so we get a crash right away. 981 clear_unhandled_oops(); 982 #endif // CHECK_UNHANDLED_OOPS 983 } 984 985 void Thread::check_for_valid_safepoint_state() { 986 if (!is_Java_thread()) return; 987 988 // Check NoSafepointVerifier, which is implied by locks taken that can be 989 // shared with the VM thread. This makes sure that no locks with allow_vm_block 990 // are held. 991 check_possible_safepoint(); 992 993 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 994 fatal("LEAF method calling lock?"); 995 } 996 997 if (GCALotAtAllSafepoints) { 998 // We could enter a safepoint here and thus have a gc 999 InterfaceSupport::check_gc_alot(); 1000 } 1001 } 1002 #endif // ASSERT 1003 1004 bool Thread::is_in_stack(address adr) const { 1005 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1006 address end = os::current_stack_pointer(); 1007 // Allow non Java threads to call this without stack_base 1008 if (_stack_base == NULL) return true; 1009 if (stack_base() > adr && adr >= end) return true; 1010 1011 return false; 1012 } 1013 1014 bool Thread::is_in_usable_stack(address adr) const { 1015 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1016 size_t usable_stack_size = _stack_size - stack_guard_size; 1017 1018 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1019 } 1020 1021 1022 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1023 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1024 // used for compilation in the future. If that change is made, the need for these methods 1025 // should be revisited, and they should be removed if possible. 1026 1027 bool Thread::is_lock_owned(address adr) const { 1028 return on_local_stack(adr); 1029 } 1030 1031 bool Thread::set_as_starting_thread() { 1032 assert(_starting_thread == NULL, "already initialized: " 1033 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1034 // NOTE: this must be called inside the main thread. 1035 DEBUG_ONLY(_starting_thread = this;) 1036 return os::create_main_thread((JavaThread*)this); 1037 } 1038 1039 static void initialize_class(Symbol* class_name, TRAPS) { 1040 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1041 InstanceKlass::cast(klass)->initialize(CHECK); 1042 } 1043 1044 1045 // Creates the initial ThreadGroup 1046 static Handle create_initial_thread_group(TRAPS) { 1047 Handle system_instance = JavaCalls::construct_new_instance( 1048 SystemDictionary::ThreadGroup_klass(), 1049 vmSymbols::void_method_signature(), 1050 CHECK_NH); 1051 Universe::set_system_thread_group(system_instance()); 1052 1053 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1054 Handle main_instance = JavaCalls::construct_new_instance( 1055 SystemDictionary::ThreadGroup_klass(), 1056 vmSymbols::threadgroup_string_void_signature(), 1057 system_instance, 1058 string, 1059 CHECK_NH); 1060 return main_instance; 1061 } 1062 1063 // Creates the initial Thread 1064 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1065 TRAPS) { 1066 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1067 assert(ik->is_initialized(), "must be"); 1068 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1069 1070 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1071 // constructor calls Thread.current(), which must be set here for the 1072 // initial thread. 1073 java_lang_Thread::set_thread(thread_oop(), thread); 1074 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1075 thread->set_threadObj(thread_oop()); 1076 1077 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1078 1079 JavaValue result(T_VOID); 1080 JavaCalls::call_special(&result, thread_oop, 1081 ik, 1082 vmSymbols::object_initializer_name(), 1083 vmSymbols::threadgroup_string_void_signature(), 1084 thread_group, 1085 string, 1086 CHECK_NULL); 1087 return thread_oop(); 1088 } 1089 1090 char java_runtime_name[128] = ""; 1091 char java_runtime_version[128] = ""; 1092 char java_runtime_vendor_version[128] = ""; 1093 char java_runtime_vendor_vm_bug_url[128] = ""; 1094 1095 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1096 static const char* get_java_runtime_name(TRAPS) { 1097 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1098 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1099 fieldDescriptor fd; 1100 bool found = k != NULL && 1101 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1102 vmSymbols::string_signature(), &fd); 1103 if (found) { 1104 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1105 if (name_oop == NULL) { 1106 return NULL; 1107 } 1108 const char* name = java_lang_String::as_utf8_string(name_oop, 1109 java_runtime_name, 1110 sizeof(java_runtime_name)); 1111 return name; 1112 } else { 1113 return NULL; 1114 } 1115 } 1116 1117 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1118 static const char* get_java_runtime_version(TRAPS) { 1119 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1120 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1121 fieldDescriptor fd; 1122 bool found = k != NULL && 1123 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1124 vmSymbols::string_signature(), &fd); 1125 if (found) { 1126 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1127 if (name_oop == NULL) { 1128 return NULL; 1129 } 1130 const char* name = java_lang_String::as_utf8_string(name_oop, 1131 java_runtime_version, 1132 sizeof(java_runtime_version)); 1133 return name; 1134 } else { 1135 return NULL; 1136 } 1137 } 1138 1139 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION 1140 static const char* get_java_runtime_vendor_version(TRAPS) { 1141 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1142 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1143 fieldDescriptor fd; 1144 bool found = k != NULL && 1145 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(), 1146 vmSymbols::string_signature(), &fd); 1147 if (found) { 1148 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1149 if (name_oop == NULL) { 1150 return NULL; 1151 } 1152 const char* name = java_lang_String::as_utf8_string(name_oop, 1153 java_runtime_vendor_version, 1154 sizeof(java_runtime_vendor_version)); 1155 return name; 1156 } else { 1157 return NULL; 1158 } 1159 } 1160 1161 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG 1162 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) { 1163 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1164 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1165 fieldDescriptor fd; 1166 bool found = k != NULL && 1167 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(), 1168 vmSymbols::string_signature(), &fd); 1169 if (found) { 1170 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1171 if (name_oop == NULL) { 1172 return NULL; 1173 } 1174 const char* name = java_lang_String::as_utf8_string(name_oop, 1175 java_runtime_vendor_vm_bug_url, 1176 sizeof(java_runtime_vendor_vm_bug_url)); 1177 return name; 1178 } else { 1179 return NULL; 1180 } 1181 } 1182 1183 // General purpose hook into Java code, run once when the VM is initialized. 1184 // The Java library method itself may be changed independently from the VM. 1185 static void call_postVMInitHook(TRAPS) { 1186 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1187 if (klass != NULL) { 1188 JavaValue result(T_VOID); 1189 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1190 vmSymbols::void_method_signature(), 1191 CHECK); 1192 } 1193 } 1194 1195 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1196 bool daemon, TRAPS) { 1197 assert(thread_group.not_null(), "thread group should be specified"); 1198 assert(threadObj() == NULL, "should only create Java thread object once"); 1199 1200 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1201 assert(ik->is_initialized(), "must be"); 1202 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1203 1204 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1205 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1206 // constructor calls Thread.current(), which must be set here. 1207 java_lang_Thread::set_thread(thread_oop(), this); 1208 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1209 set_threadObj(thread_oop()); 1210 1211 JavaValue result(T_VOID); 1212 if (thread_name != NULL) { 1213 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1214 // Thread gets assigned specified name and null target 1215 JavaCalls::call_special(&result, 1216 thread_oop, 1217 ik, 1218 vmSymbols::object_initializer_name(), 1219 vmSymbols::threadgroup_string_void_signature(), 1220 thread_group, 1221 name, 1222 THREAD); 1223 } else { 1224 // Thread gets assigned name "Thread-nnn" and null target 1225 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1226 JavaCalls::call_special(&result, 1227 thread_oop, 1228 ik, 1229 vmSymbols::object_initializer_name(), 1230 vmSymbols::threadgroup_runnable_void_signature(), 1231 thread_group, 1232 Handle(), 1233 THREAD); 1234 } 1235 1236 1237 if (daemon) { 1238 java_lang_Thread::set_daemon(thread_oop()); 1239 } 1240 1241 if (HAS_PENDING_EXCEPTION) { 1242 return; 1243 } 1244 1245 Klass* group = SystemDictionary::ThreadGroup_klass(); 1246 Handle threadObj(THREAD, this->threadObj()); 1247 1248 JavaCalls::call_special(&result, 1249 thread_group, 1250 group, 1251 vmSymbols::add_method_name(), 1252 vmSymbols::thread_void_signature(), 1253 threadObj, // Arg 1 1254 THREAD); 1255 } 1256 1257 // List of all NonJavaThreads and safe iteration over that list. 1258 1259 class NonJavaThread::List { 1260 public: 1261 NonJavaThread* volatile _head; 1262 SingleWriterSynchronizer _protect; 1263 1264 List() : _head(NULL), _protect() {} 1265 }; 1266 1267 NonJavaThread::List NonJavaThread::_the_list; 1268 1269 NonJavaThread::Iterator::Iterator() : 1270 _protect_enter(_the_list._protect.enter()), 1271 _current(Atomic::load_acquire(&_the_list._head)) 1272 {} 1273 1274 NonJavaThread::Iterator::~Iterator() { 1275 _the_list._protect.exit(_protect_enter); 1276 } 1277 1278 void NonJavaThread::Iterator::step() { 1279 assert(!end(), "precondition"); 1280 _current = Atomic::load_acquire(&_current->_next); 1281 } 1282 1283 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1284 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1285 } 1286 1287 NonJavaThread::~NonJavaThread() { } 1288 1289 void NonJavaThread::add_to_the_list() { 1290 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1291 // Initialize BarrierSet-related data before adding to list. 1292 BarrierSet::barrier_set()->on_thread_attach(this); 1293 Atomic::release_store(&_next, _the_list._head); 1294 Atomic::release_store(&_the_list._head, this); 1295 } 1296 1297 void NonJavaThread::remove_from_the_list() { 1298 { 1299 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1300 // Cleanup BarrierSet-related data before removing from list. 1301 BarrierSet::barrier_set()->on_thread_detach(this); 1302 NonJavaThread* volatile* p = &_the_list._head; 1303 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1304 if (t == this) { 1305 *p = _next; 1306 break; 1307 } 1308 } 1309 } 1310 // Wait for any in-progress iterators. Concurrent synchronize is not 1311 // allowed, so do it while holding a dedicated lock. Outside and distinct 1312 // from NJTList_lock in case an iteration attempts to lock it. 1313 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1314 _the_list._protect.synchronize(); 1315 _next = NULL; // Safe to drop the link now. 1316 } 1317 1318 void NonJavaThread::pre_run() { 1319 add_to_the_list(); 1320 1321 // This is slightly odd in that NamedThread is a subclass, but 1322 // in fact name() is defined in Thread 1323 assert(this->name() != NULL, "thread name was not set before it was started"); 1324 this->set_native_thread_name(this->name()); 1325 } 1326 1327 void NonJavaThread::post_run() { 1328 JFR_ONLY(Jfr::on_thread_exit(this);) 1329 remove_from_the_list(); 1330 // Ensure thread-local-storage is cleared before termination. 1331 Thread::clear_thread_current(); 1332 } 1333 1334 // NamedThread -- non-JavaThread subclasses with multiple 1335 // uniquely named instances should derive from this. 1336 NamedThread::NamedThread() : 1337 NonJavaThread(), 1338 _name(NULL), 1339 _processed_thread(NULL), 1340 _gc_id(GCId::undefined()) 1341 {} 1342 1343 NamedThread::~NamedThread() { 1344 FREE_C_HEAP_ARRAY(char, _name); 1345 } 1346 1347 void NamedThread::set_name(const char* format, ...) { 1348 guarantee(_name == NULL, "Only get to set name once."); 1349 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1350 va_list ap; 1351 va_start(ap, format); 1352 jio_vsnprintf(_name, max_name_len, format, ap); 1353 va_end(ap); 1354 } 1355 1356 void NamedThread::print_on(outputStream* st) const { 1357 st->print("\"%s\" ", name()); 1358 Thread::print_on(st); 1359 st->cr(); 1360 } 1361 1362 1363 // ======= WatcherThread ======== 1364 1365 // The watcher thread exists to simulate timer interrupts. It should 1366 // be replaced by an abstraction over whatever native support for 1367 // timer interrupts exists on the platform. 1368 1369 WatcherThread* WatcherThread::_watcher_thread = NULL; 1370 bool WatcherThread::_startable = false; 1371 volatile bool WatcherThread::_should_terminate = false; 1372 1373 WatcherThread::WatcherThread() : NonJavaThread() { 1374 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1375 if (os::create_thread(this, os::watcher_thread)) { 1376 _watcher_thread = this; 1377 1378 // Set the watcher thread to the highest OS priority which should not be 1379 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1380 // is created. The only normal thread using this priority is the reference 1381 // handler thread, which runs for very short intervals only. 1382 // If the VMThread's priority is not lower than the WatcherThread profiling 1383 // will be inaccurate. 1384 os::set_priority(this, MaxPriority); 1385 if (!DisableStartThread) { 1386 os::start_thread(this); 1387 } 1388 } 1389 } 1390 1391 int WatcherThread::sleep() const { 1392 // The WatcherThread does not participate in the safepoint protocol 1393 // for the PeriodicTask_lock because it is not a JavaThread. 1394 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1395 1396 if (_should_terminate) { 1397 // check for termination before we do any housekeeping or wait 1398 return 0; // we did not sleep. 1399 } 1400 1401 // remaining will be zero if there are no tasks, 1402 // causing the WatcherThread to sleep until a task is 1403 // enrolled 1404 int remaining = PeriodicTask::time_to_wait(); 1405 int time_slept = 0; 1406 1407 // we expect this to timeout - we only ever get unparked when 1408 // we should terminate or when a new task has been enrolled 1409 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1410 1411 jlong time_before_loop = os::javaTimeNanos(); 1412 1413 while (true) { 1414 bool timedout = ml.wait(remaining); 1415 jlong now = os::javaTimeNanos(); 1416 1417 if (remaining == 0) { 1418 // if we didn't have any tasks we could have waited for a long time 1419 // consider the time_slept zero and reset time_before_loop 1420 time_slept = 0; 1421 time_before_loop = now; 1422 } else { 1423 // need to recalculate since we might have new tasks in _tasks 1424 time_slept = (int) ((now - time_before_loop) / 1000000); 1425 } 1426 1427 // Change to task list or spurious wakeup of some kind 1428 if (timedout || _should_terminate) { 1429 break; 1430 } 1431 1432 remaining = PeriodicTask::time_to_wait(); 1433 if (remaining == 0) { 1434 // Last task was just disenrolled so loop around and wait until 1435 // another task gets enrolled 1436 continue; 1437 } 1438 1439 remaining -= time_slept; 1440 if (remaining <= 0) { 1441 break; 1442 } 1443 } 1444 1445 return time_slept; 1446 } 1447 1448 void WatcherThread::run() { 1449 assert(this == watcher_thread(), "just checking"); 1450 1451 this->set_active_handles(JNIHandleBlock::allocate_block()); 1452 while (true) { 1453 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1454 assert(watcher_thread() == this, "thread consistency check"); 1455 1456 // Calculate how long it'll be until the next PeriodicTask work 1457 // should be done, and sleep that amount of time. 1458 int time_waited = sleep(); 1459 1460 if (VMError::is_error_reported()) { 1461 // A fatal error has happened, the error handler(VMError::report_and_die) 1462 // should abort JVM after creating an error log file. However in some 1463 // rare cases, the error handler itself might deadlock. Here periodically 1464 // check for error reporting timeouts, and if it happens, just proceed to 1465 // abort the VM. 1466 1467 // This code is in WatcherThread because WatcherThread wakes up 1468 // periodically so the fatal error handler doesn't need to do anything; 1469 // also because the WatcherThread is less likely to crash than other 1470 // threads. 1471 1472 for (;;) { 1473 // Note: we use naked sleep in this loop because we want to avoid using 1474 // any kind of VM infrastructure which may be broken at this point. 1475 if (VMError::check_timeout()) { 1476 // We hit error reporting timeout. Error reporting was interrupted and 1477 // will be wrapping things up now (closing files etc). Give it some more 1478 // time, then quit the VM. 1479 os::naked_short_sleep(200); 1480 // Print a message to stderr. 1481 fdStream err(defaultStream::output_fd()); 1482 err.print_raw_cr("# [ timer expired, abort... ]"); 1483 // skip atexit/vm_exit/vm_abort hooks 1484 os::die(); 1485 } 1486 1487 // Wait a second, then recheck for timeout. 1488 os::naked_short_sleep(999); 1489 } 1490 } 1491 1492 if (_should_terminate) { 1493 // check for termination before posting the next tick 1494 break; 1495 } 1496 1497 PeriodicTask::real_time_tick(time_waited); 1498 } 1499 1500 // Signal that it is terminated 1501 { 1502 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1503 _watcher_thread = NULL; 1504 Terminator_lock->notify_all(); 1505 } 1506 } 1507 1508 void WatcherThread::start() { 1509 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1510 1511 if (watcher_thread() == NULL && _startable) { 1512 _should_terminate = false; 1513 // Create the single instance of WatcherThread 1514 new WatcherThread(); 1515 } 1516 } 1517 1518 void WatcherThread::make_startable() { 1519 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1520 _startable = true; 1521 } 1522 1523 void WatcherThread::stop() { 1524 { 1525 // Follow normal safepoint aware lock enter protocol since the 1526 // WatcherThread is stopped by another JavaThread. 1527 MutexLocker ml(PeriodicTask_lock); 1528 _should_terminate = true; 1529 1530 WatcherThread* watcher = watcher_thread(); 1531 if (watcher != NULL) { 1532 // unpark the WatcherThread so it can see that it should terminate 1533 watcher->unpark(); 1534 } 1535 } 1536 1537 MonitorLocker mu(Terminator_lock); 1538 1539 while (watcher_thread() != NULL) { 1540 // This wait should make safepoint checks, wait without a timeout, 1541 // and wait as a suspend-equivalent condition. 1542 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1543 } 1544 } 1545 1546 void WatcherThread::unpark() { 1547 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1548 PeriodicTask_lock->notify(); 1549 } 1550 1551 void WatcherThread::print_on(outputStream* st) const { 1552 st->print("\"%s\" ", name()); 1553 Thread::print_on(st); 1554 st->cr(); 1555 } 1556 1557 // ======= JavaThread ======== 1558 1559 #if INCLUDE_JVMCI 1560 1561 jlong* JavaThread::_jvmci_old_thread_counters; 1562 1563 bool jvmci_counters_include(JavaThread* thread) { 1564 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1565 } 1566 1567 void JavaThread::collect_counters(jlong* array, int length) { 1568 assert(length == JVMCICounterSize, "wrong value"); 1569 for (int i = 0; i < length; i++) { 1570 array[i] = _jvmci_old_thread_counters[i]; 1571 } 1572 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1573 if (jvmci_counters_include(tp)) { 1574 for (int i = 0; i < length; i++) { 1575 array[i] += tp->_jvmci_counters[i]; 1576 } 1577 } 1578 } 1579 } 1580 1581 // Attempt to enlarge the array for per thread counters. 1582 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1583 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1584 if (old_counters == NULL) { 1585 old_counters = new_counters; 1586 memset(old_counters, 0, sizeof(jlong) * new_size); 1587 } else { 1588 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1589 new_counters[i] = old_counters[i]; 1590 } 1591 if (new_size > current_size) { 1592 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1593 } 1594 FREE_C_HEAP_ARRAY(jlong, old_counters); 1595 } 1596 return new_counters; 1597 } 1598 1599 // Attempt to enlarge the array for per thread counters. 1600 void JavaThread::resize_counters(int current_size, int new_size) { 1601 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1602 } 1603 1604 class VM_JVMCIResizeCounters : public VM_Operation { 1605 private: 1606 int _new_size; 1607 1608 public: 1609 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { } 1610 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; } 1611 bool allow_nested_vm_operations() const { return true; } 1612 void doit() { 1613 // Resize the old thread counters array 1614 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size); 1615 JavaThread::_jvmci_old_thread_counters = new_counters; 1616 1617 // Now resize each threads array 1618 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1619 tp->resize_counters(JVMCICounterSize, _new_size); 1620 } 1621 JVMCICounterSize = _new_size; 1622 } 1623 }; 1624 1625 void JavaThread::resize_all_jvmci_counters(int new_size) { 1626 VM_JVMCIResizeCounters op(new_size); 1627 VMThread::execute(&op); 1628 } 1629 1630 #endif // INCLUDE_JVMCI 1631 1632 // A JavaThread is a normal Java thread 1633 1634 void JavaThread::initialize() { 1635 // Initialize fields 1636 1637 set_saved_exception_pc(NULL); 1638 set_threadObj(NULL); 1639 _anchor.clear(); 1640 set_entry_point(NULL); 1641 set_jni_functions(jni_functions()); 1642 set_callee_target(NULL); 1643 set_vm_result(NULL); 1644 set_vm_result_2(NULL); 1645 set_vframe_array_head(NULL); 1646 set_vframe_array_last(NULL); 1647 set_deferred_locals(NULL); 1648 set_deopt_mark(NULL); 1649 set_deopt_compiled_method(NULL); 1650 set_monitor_chunks(NULL); 1651 _on_thread_list = false; 1652 set_thread_state(_thread_new); 1653 _terminated = _not_terminated; 1654 _array_for_gc = NULL; 1655 _suspend_equivalent = false; 1656 _in_deopt_handler = 0; 1657 _doing_unsafe_access = false; 1658 _stack_guard_state = stack_guard_unused; 1659 #if INCLUDE_JVMCI 1660 _pending_monitorenter = false; 1661 _pending_deoptimization = -1; 1662 _pending_failed_speculation = 0; 1663 _pending_transfer_to_interpreter = false; 1664 _in_retryable_allocation = false; 1665 _jvmci._alternate_call_target = NULL; 1666 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1667 _jvmci_counters = NULL; 1668 if (JVMCICounterSize > 0) { 1669 resize_counters(0, (int) JVMCICounterSize); 1670 } 1671 #endif // INCLUDE_JVMCI 1672 _reserved_stack_activation = NULL; // stack base not known yet 1673 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1674 _exception_pc = 0; 1675 _exception_handler_pc = 0; 1676 _is_method_handle_return = 0; 1677 _jvmti_thread_state= NULL; 1678 _should_post_on_exceptions_flag = JNI_FALSE; 1679 _interp_only_mode = 0; 1680 _special_runtime_exit_condition = _no_async_condition; 1681 _pending_async_exception = NULL; 1682 _thread_stat = NULL; 1683 _thread_stat = new ThreadStatistics(); 1684 _jni_active_critical = 0; 1685 _pending_jni_exception_check_fn = NULL; 1686 _do_not_unlock_if_synchronized = false; 1687 _cached_monitor_info = NULL; 1688 _parker = Parker::Allocate(this); 1689 _SleepEvent = ParkEvent::Allocate(this); 1690 // Setup safepoint state info for this thread 1691 ThreadSafepointState::create(this); 1692 1693 debug_only(_java_call_counter = 0); 1694 1695 // JVMTI PopFrame support 1696 _popframe_condition = popframe_inactive; 1697 _popframe_preserved_args = NULL; 1698 _popframe_preserved_args_size = 0; 1699 _frames_to_pop_failed_realloc = 0; 1700 1701 if (SafepointMechanism::uses_thread_local_poll()) { 1702 SafepointMechanism::initialize_header(this); 1703 } 1704 1705 _class_to_be_initialized = NULL; 1706 1707 pd_initialize(); 1708 } 1709 1710 JavaThread::JavaThread(bool is_attaching_via_jni) : 1711 Thread() { 1712 initialize(); 1713 if (is_attaching_via_jni) { 1714 _jni_attach_state = _attaching_via_jni; 1715 } else { 1716 _jni_attach_state = _not_attaching_via_jni; 1717 } 1718 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1719 } 1720 1721 1722 // interrupt support 1723 1724 void JavaThread::interrupt() { 1725 debug_only(check_for_dangling_thread_pointer(this);) 1726 1727 // For Windows _interrupt_event 1728 osthread()->set_interrupted(true); 1729 1730 // For Thread.sleep 1731 _SleepEvent->unpark(); 1732 1733 // For JSR166 LockSupport.park 1734 parker()->unpark(); 1735 1736 // For ObjectMonitor and JvmtiRawMonitor 1737 _ParkEvent->unpark(); 1738 } 1739 1740 1741 bool JavaThread::is_interrupted(bool clear_interrupted) { 1742 debug_only(check_for_dangling_thread_pointer(this);) 1743 1744 if (threadObj() == NULL) { 1745 // If there is no j.l.Thread then it is impossible to have 1746 // been interrupted. We can find NULL during VM initialization 1747 // or when a JNI thread is still in the process of attaching. 1748 // In such cases this must be the current thread. 1749 assert(this == Thread::current(), "invariant"); 1750 return false; 1751 } 1752 1753 bool interrupted = java_lang_Thread::interrupted(threadObj()); 1754 1755 // NOTE that since there is no "lock" around the interrupt and 1756 // is_interrupted operations, there is the possibility that the 1757 // interrupted flag will be "false" but that the 1758 // low-level events will be in the signaled state. This is 1759 // intentional. The effect of this is that Object.wait() and 1760 // LockSupport.park() will appear to have a spurious wakeup, which 1761 // is allowed and not harmful, and the possibility is so rare that 1762 // it is not worth the added complexity to add yet another lock. 1763 // For the sleep event an explicit reset is performed on entry 1764 // to JavaThread::sleep, so there is no early return. It has also been 1765 // recommended not to put the interrupted flag into the "event" 1766 // structure because it hides the issue. 1767 // Also, because there is no lock, we must only clear the interrupt 1768 // state if we are going to report that we were interrupted; otherwise 1769 // an interrupt that happens just after we read the field would be lost. 1770 if (interrupted && clear_interrupted) { 1771 assert(this == Thread::current(), "only the current thread can clear"); 1772 java_lang_Thread::set_interrupted(threadObj(), false); 1773 osthread()->set_interrupted(false); 1774 } 1775 1776 return interrupted; 1777 } 1778 1779 bool JavaThread::reguard_stack(address cur_sp) { 1780 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1781 && _stack_guard_state != stack_guard_reserved_disabled) { 1782 return true; // Stack already guarded or guard pages not needed. 1783 } 1784 1785 if (register_stack_overflow()) { 1786 // For those architectures which have separate register and 1787 // memory stacks, we must check the register stack to see if 1788 // it has overflowed. 1789 return false; 1790 } 1791 1792 // Java code never executes within the yellow zone: the latter is only 1793 // there to provoke an exception during stack banging. If java code 1794 // is executing there, either StackShadowPages should be larger, or 1795 // some exception code in c1, c2 or the interpreter isn't unwinding 1796 // when it should. 1797 guarantee(cur_sp > stack_reserved_zone_base(), 1798 "not enough space to reguard - increase StackShadowPages"); 1799 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1800 enable_stack_yellow_reserved_zone(); 1801 if (reserved_stack_activation() != stack_base()) { 1802 set_reserved_stack_activation(stack_base()); 1803 } 1804 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1805 set_reserved_stack_activation(stack_base()); 1806 enable_stack_reserved_zone(); 1807 } 1808 return true; 1809 } 1810 1811 bool JavaThread::reguard_stack(void) { 1812 return reguard_stack(os::current_stack_pointer()); 1813 } 1814 1815 1816 void JavaThread::block_if_vm_exited() { 1817 if (_terminated == _vm_exited) { 1818 // _vm_exited is set at safepoint, and Threads_lock is never released 1819 // we will block here forever. 1820 // Here we can be doing a jump from a safe state to an unsafe state without 1821 // proper transition, but it happens after the final safepoint has begun. 1822 set_thread_state(_thread_in_vm); 1823 Threads_lock->lock(); 1824 ShouldNotReachHere(); 1825 } 1826 } 1827 1828 1829 // Remove this ifdef when C1 is ported to the compiler interface. 1830 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1831 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1832 1833 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1834 Thread() { 1835 initialize(); 1836 _jni_attach_state = _not_attaching_via_jni; 1837 set_entry_point(entry_point); 1838 // Create the native thread itself. 1839 // %note runtime_23 1840 os::ThreadType thr_type = os::java_thread; 1841 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1842 os::java_thread; 1843 os::create_thread(this, thr_type, stack_sz); 1844 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1845 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1846 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1847 // the exception consists of creating the exception object & initializing it, initialization 1848 // will leave the VM via a JavaCall and then all locks must be unlocked). 1849 // 1850 // The thread is still suspended when we reach here. Thread must be explicit started 1851 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1852 // by calling Threads:add. The reason why this is not done here, is because the thread 1853 // object must be fully initialized (take a look at JVM_Start) 1854 } 1855 1856 JavaThread::~JavaThread() { 1857 1858 // JSR166 -- return the parker to the free list 1859 Parker::Release(_parker); 1860 _parker = NULL; 1861 1862 // Return the sleep event to the free list 1863 ParkEvent::Release(_SleepEvent); 1864 _SleepEvent = NULL; 1865 1866 // Free any remaining previous UnrollBlock 1867 vframeArray* old_array = vframe_array_last(); 1868 1869 if (old_array != NULL) { 1870 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1871 old_array->set_unroll_block(NULL); 1872 delete old_info; 1873 delete old_array; 1874 } 1875 1876 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1877 if (deferred != NULL) { 1878 // This can only happen if thread is destroyed before deoptimization occurs. 1879 assert(deferred->length() != 0, "empty array!"); 1880 do { 1881 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1882 deferred->remove_at(0); 1883 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1884 delete dlv; 1885 } while (deferred->length() != 0); 1886 delete deferred; 1887 } 1888 1889 // All Java related clean up happens in exit 1890 ThreadSafepointState::destroy(this); 1891 if (_thread_stat != NULL) delete _thread_stat; 1892 1893 #if INCLUDE_JVMCI 1894 if (JVMCICounterSize > 0) { 1895 if (jvmci_counters_include(this)) { 1896 for (int i = 0; i < JVMCICounterSize; i++) { 1897 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1898 } 1899 } 1900 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1901 } 1902 #endif // INCLUDE_JVMCI 1903 } 1904 1905 1906 // First JavaThread specific code executed by a new Java thread. 1907 void JavaThread::pre_run() { 1908 // empty - see comments in run() 1909 } 1910 1911 // The main routine called by a new Java thread. This isn't overridden 1912 // by subclasses, instead different subclasses define a different "entry_point" 1913 // which defines the actual logic for that kind of thread. 1914 void JavaThread::run() { 1915 // initialize thread-local alloc buffer related fields 1916 this->initialize_tlab(); 1917 1918 // Used to test validity of stack trace backs. 1919 // This can't be moved into pre_run() else we invalidate 1920 // the requirement that thread_main_inner is lower on 1921 // the stack. Consequently all the initialization logic 1922 // stays here in run() rather than pre_run(). 1923 this->record_base_of_stack_pointer(); 1924 1925 this->create_stack_guard_pages(); 1926 1927 this->cache_global_variables(); 1928 1929 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1930 // in the VM. Change thread state from _thread_new to _thread_in_vm 1931 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1932 // Before a thread is on the threads list it is always safe, so after leaving the 1933 // _thread_new we should emit a instruction barrier. The distance to modified code 1934 // from here is probably far enough, but this is consistent and safe. 1935 OrderAccess::cross_modify_fence(); 1936 1937 assert(JavaThread::current() == this, "sanity check"); 1938 assert(!Thread::current()->owns_locks(), "sanity check"); 1939 1940 DTRACE_THREAD_PROBE(start, this); 1941 1942 // This operation might block. We call that after all safepoint checks for a new thread has 1943 // been completed. 1944 this->set_active_handles(JNIHandleBlock::allocate_block()); 1945 1946 if (JvmtiExport::should_post_thread_life()) { 1947 JvmtiExport::post_thread_start(this); 1948 1949 } 1950 1951 // We call another function to do the rest so we are sure that the stack addresses used 1952 // from there will be lower than the stack base just computed. 1953 thread_main_inner(); 1954 } 1955 1956 void JavaThread::thread_main_inner() { 1957 assert(JavaThread::current() == this, "sanity check"); 1958 assert(this->threadObj() != NULL, "just checking"); 1959 1960 // Execute thread entry point unless this thread has a pending exception 1961 // or has been stopped before starting. 1962 // Note: Due to JVM_StopThread we can have pending exceptions already! 1963 if (!this->has_pending_exception() && 1964 !java_lang_Thread::is_stillborn(this->threadObj())) { 1965 { 1966 ResourceMark rm(this); 1967 this->set_native_thread_name(this->get_thread_name()); 1968 } 1969 HandleMark hm(this); 1970 this->entry_point()(this, this); 1971 } 1972 1973 DTRACE_THREAD_PROBE(stop, this); 1974 1975 // Cleanup is handled in post_run() 1976 } 1977 1978 // Shared teardown for all JavaThreads 1979 void JavaThread::post_run() { 1980 this->exit(false); 1981 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1982 // for any shared tear-down. 1983 this->smr_delete(); 1984 } 1985 1986 static void ensure_join(JavaThread* thread) { 1987 // We do not need to grab the Threads_lock, since we are operating on ourself. 1988 Handle threadObj(thread, thread->threadObj()); 1989 assert(threadObj.not_null(), "java thread object must exist"); 1990 ObjectLocker lock(threadObj, thread); 1991 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1992 thread->clear_pending_exception(); 1993 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1994 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1995 // Clear the native thread instance - this makes isAlive return false and allows the join() 1996 // to complete once we've done the notify_all below 1997 java_lang_Thread::set_thread(threadObj(), NULL); 1998 lock.notify_all(thread); 1999 // Ignore pending exception (ThreadDeath), since we are exiting anyway 2000 thread->clear_pending_exception(); 2001 } 2002 2003 static bool is_daemon(oop threadObj) { 2004 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 2005 } 2006 2007 // For any new cleanup additions, please check to see if they need to be applied to 2008 // cleanup_failed_attach_current_thread as well. 2009 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 2010 assert(this == JavaThread::current(), "thread consistency check"); 2011 2012 elapsedTimer _timer_exit_phase1; 2013 elapsedTimer _timer_exit_phase2; 2014 elapsedTimer _timer_exit_phase3; 2015 elapsedTimer _timer_exit_phase4; 2016 2017 if (log_is_enabled(Debug, os, thread, timer)) { 2018 _timer_exit_phase1.start(); 2019 } 2020 2021 HandleMark hm(this); 2022 Handle uncaught_exception(this, this->pending_exception()); 2023 this->clear_pending_exception(); 2024 Handle threadObj(this, this->threadObj()); 2025 assert(threadObj.not_null(), "Java thread object should be created"); 2026 2027 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 2028 { 2029 EXCEPTION_MARK; 2030 2031 CLEAR_PENDING_EXCEPTION; 2032 } 2033 if (!destroy_vm) { 2034 if (uncaught_exception.not_null()) { 2035 EXCEPTION_MARK; 2036 // Call method Thread.dispatchUncaughtException(). 2037 Klass* thread_klass = SystemDictionary::Thread_klass(); 2038 JavaValue result(T_VOID); 2039 JavaCalls::call_virtual(&result, 2040 threadObj, thread_klass, 2041 vmSymbols::dispatchUncaughtException_name(), 2042 vmSymbols::throwable_void_signature(), 2043 uncaught_exception, 2044 THREAD); 2045 if (HAS_PENDING_EXCEPTION) { 2046 ResourceMark rm(this); 2047 jio_fprintf(defaultStream::error_stream(), 2048 "\nException: %s thrown from the UncaughtExceptionHandler" 2049 " in thread \"%s\"\n", 2050 pending_exception()->klass()->external_name(), 2051 get_thread_name()); 2052 CLEAR_PENDING_EXCEPTION; 2053 } 2054 } 2055 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2056 2057 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2058 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2059 // is deprecated anyhow. 2060 if (!is_Compiler_thread()) { 2061 int count = 3; 2062 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2063 EXCEPTION_MARK; 2064 JavaValue result(T_VOID); 2065 Klass* thread_klass = SystemDictionary::Thread_klass(); 2066 JavaCalls::call_virtual(&result, 2067 threadObj, thread_klass, 2068 vmSymbols::exit_method_name(), 2069 vmSymbols::void_method_signature(), 2070 THREAD); 2071 CLEAR_PENDING_EXCEPTION; 2072 } 2073 } 2074 // notify JVMTI 2075 if (JvmtiExport::should_post_thread_life()) { 2076 JvmtiExport::post_thread_end(this); 2077 } 2078 2079 // We have notified the agents that we are exiting, before we go on, 2080 // we must check for a pending external suspend request and honor it 2081 // in order to not surprise the thread that made the suspend request. 2082 while (true) { 2083 { 2084 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2085 if (!is_external_suspend()) { 2086 set_terminated(_thread_exiting); 2087 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2088 break; 2089 } 2090 // Implied else: 2091 // Things get a little tricky here. We have a pending external 2092 // suspend request, but we are holding the SR_lock so we 2093 // can't just self-suspend. So we temporarily drop the lock 2094 // and then self-suspend. 2095 } 2096 2097 ThreadBlockInVM tbivm(this); 2098 java_suspend_self(); 2099 2100 // We're done with this suspend request, but we have to loop around 2101 // and check again. Eventually we will get SR_lock without a pending 2102 // external suspend request and will be able to mark ourselves as 2103 // exiting. 2104 } 2105 // no more external suspends are allowed at this point 2106 } else { 2107 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2108 // before_exit() has already posted JVMTI THREAD_END events 2109 } 2110 2111 if (log_is_enabled(Debug, os, thread, timer)) { 2112 _timer_exit_phase1.stop(); 2113 _timer_exit_phase2.start(); 2114 } 2115 2116 // Capture daemon status before the thread is marked as terminated. 2117 bool daemon = is_daemon(threadObj()); 2118 2119 // Notify waiters on thread object. This has to be done after exit() is called 2120 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2121 // group should have the destroyed bit set before waiters are notified). 2122 ensure_join(this); 2123 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2124 2125 if (log_is_enabled(Debug, os, thread, timer)) { 2126 _timer_exit_phase2.stop(); 2127 _timer_exit_phase3.start(); 2128 } 2129 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2130 // held by this thread must be released. The spec does not distinguish 2131 // between JNI-acquired and regular Java monitors. We can only see 2132 // regular Java monitors here if monitor enter-exit matching is broken. 2133 // 2134 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2135 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2136 if (exit_type == jni_detach) { 2137 // Sanity check even though JNI DetachCurrentThread() would have 2138 // returned JNI_ERR if there was a Java frame. JavaThread exit 2139 // should be done executing Java code by the time we get here. 2140 assert(!this->has_last_Java_frame(), 2141 "should not have a Java frame when detaching or exiting"); 2142 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2143 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2144 } 2145 2146 // These things needs to be done while we are still a Java Thread. Make sure that thread 2147 // is in a consistent state, in case GC happens 2148 JFR_ONLY(Jfr::on_thread_exit(this);) 2149 2150 if (active_handles() != NULL) { 2151 JNIHandleBlock* block = active_handles(); 2152 set_active_handles(NULL); 2153 JNIHandleBlock::release_block(block); 2154 } 2155 2156 if (free_handle_block() != NULL) { 2157 JNIHandleBlock* block = free_handle_block(); 2158 set_free_handle_block(NULL); 2159 JNIHandleBlock::release_block(block); 2160 } 2161 2162 // These have to be removed while this is still a valid thread. 2163 remove_stack_guard_pages(); 2164 2165 if (UseTLAB) { 2166 tlab().retire(); 2167 } 2168 2169 if (JvmtiEnv::environments_might_exist()) { 2170 JvmtiExport::cleanup_thread(this); 2171 } 2172 2173 // We must flush any deferred card marks and other various GC barrier 2174 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2175 // before removing a thread from the list of active threads. 2176 BarrierSet::barrier_set()->on_thread_detach(this); 2177 2178 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2179 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2180 os::current_thread_id()); 2181 2182 if (log_is_enabled(Debug, os, thread, timer)) { 2183 _timer_exit_phase3.stop(); 2184 _timer_exit_phase4.start(); 2185 } 2186 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2187 Threads::remove(this, daemon); 2188 2189 if (log_is_enabled(Debug, os, thread, timer)) { 2190 _timer_exit_phase4.stop(); 2191 ResourceMark rm(this); 2192 log_debug(os, thread, timer)("name='%s'" 2193 ", exit-phase1=" JLONG_FORMAT 2194 ", exit-phase2=" JLONG_FORMAT 2195 ", exit-phase3=" JLONG_FORMAT 2196 ", exit-phase4=" JLONG_FORMAT, 2197 get_thread_name(), 2198 _timer_exit_phase1.milliseconds(), 2199 _timer_exit_phase2.milliseconds(), 2200 _timer_exit_phase3.milliseconds(), 2201 _timer_exit_phase4.milliseconds()); 2202 } 2203 } 2204 2205 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2206 if (active_handles() != NULL) { 2207 JNIHandleBlock* block = active_handles(); 2208 set_active_handles(NULL); 2209 JNIHandleBlock::release_block(block); 2210 } 2211 2212 if (free_handle_block() != NULL) { 2213 JNIHandleBlock* block = free_handle_block(); 2214 set_free_handle_block(NULL); 2215 JNIHandleBlock::release_block(block); 2216 } 2217 2218 // These have to be removed while this is still a valid thread. 2219 remove_stack_guard_pages(); 2220 2221 if (UseTLAB) { 2222 tlab().retire(); 2223 } 2224 2225 BarrierSet::barrier_set()->on_thread_detach(this); 2226 2227 Threads::remove(this, is_daemon); 2228 this->smr_delete(); 2229 } 2230 2231 JavaThread* JavaThread::active() { 2232 Thread* thread = Thread::current(); 2233 if (thread->is_Java_thread()) { 2234 return (JavaThread*) thread; 2235 } else { 2236 assert(thread->is_VM_thread(), "this must be a vm thread"); 2237 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2238 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2239 assert(ret->is_Java_thread(), "must be a Java thread"); 2240 return ret; 2241 } 2242 } 2243 2244 bool JavaThread::is_lock_owned(address adr) const { 2245 if (Thread::is_lock_owned(adr)) return true; 2246 2247 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2248 if (chunk->contains(adr)) return true; 2249 } 2250 2251 return false; 2252 } 2253 2254 2255 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2256 chunk->set_next(monitor_chunks()); 2257 set_monitor_chunks(chunk); 2258 } 2259 2260 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2261 guarantee(monitor_chunks() != NULL, "must be non empty"); 2262 if (monitor_chunks() == chunk) { 2263 set_monitor_chunks(chunk->next()); 2264 } else { 2265 MonitorChunk* prev = monitor_chunks(); 2266 while (prev->next() != chunk) prev = prev->next(); 2267 prev->set_next(chunk->next()); 2268 } 2269 } 2270 2271 // JVM support. 2272 2273 // Note: this function shouldn't block if it's called in 2274 // _thread_in_native_trans state (such as from 2275 // check_special_condition_for_native_trans()). 2276 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2277 2278 if (has_last_Java_frame() && has_async_condition()) { 2279 // If we are at a polling page safepoint (not a poll return) 2280 // then we must defer async exception because live registers 2281 // will be clobbered by the exception path. Poll return is 2282 // ok because the call we a returning from already collides 2283 // with exception handling registers and so there is no issue. 2284 // (The exception handling path kills call result registers but 2285 // this is ok since the exception kills the result anyway). 2286 2287 if (is_at_poll_safepoint()) { 2288 // if the code we are returning to has deoptimized we must defer 2289 // the exception otherwise live registers get clobbered on the 2290 // exception path before deoptimization is able to retrieve them. 2291 // 2292 RegisterMap map(this, false); 2293 frame caller_fr = last_frame().sender(&map); 2294 assert(caller_fr.is_compiled_frame(), "what?"); 2295 if (caller_fr.is_deoptimized_frame()) { 2296 log_info(exceptions)("deferred async exception at compiled safepoint"); 2297 return; 2298 } 2299 } 2300 } 2301 2302 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2303 if (condition == _no_async_condition) { 2304 // Conditions have changed since has_special_runtime_exit_condition() 2305 // was called: 2306 // - if we were here only because of an external suspend request, 2307 // then that was taken care of above (or cancelled) so we are done 2308 // - if we were here because of another async request, then it has 2309 // been cleared between the has_special_runtime_exit_condition() 2310 // and now so again we are done 2311 return; 2312 } 2313 2314 // Check for pending async. exception 2315 if (_pending_async_exception != NULL) { 2316 // Only overwrite an already pending exception, if it is not a threadDeath. 2317 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2318 2319 // We cannot call Exceptions::_throw(...) here because we cannot block 2320 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2321 2322 LogTarget(Info, exceptions) lt; 2323 if (lt.is_enabled()) { 2324 ResourceMark rm; 2325 LogStream ls(lt); 2326 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2327 if (has_last_Java_frame()) { 2328 frame f = last_frame(); 2329 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2330 } 2331 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2332 } 2333 _pending_async_exception = NULL; 2334 clear_has_async_exception(); 2335 } 2336 } 2337 2338 if (check_unsafe_error && 2339 condition == _async_unsafe_access_error && !has_pending_exception()) { 2340 condition = _no_async_condition; // done 2341 switch (thread_state()) { 2342 case _thread_in_vm: { 2343 JavaThread* THREAD = this; 2344 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2345 } 2346 case _thread_in_native: { 2347 ThreadInVMfromNative tiv(this); 2348 JavaThread* THREAD = this; 2349 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2350 } 2351 case _thread_in_Java: { 2352 ThreadInVMfromJava tiv(this); 2353 JavaThread* THREAD = this; 2354 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2355 } 2356 default: 2357 ShouldNotReachHere(); 2358 } 2359 } 2360 2361 assert(condition == _no_async_condition || has_pending_exception() || 2362 (!check_unsafe_error && condition == _async_unsafe_access_error), 2363 "must have handled the async condition, if no exception"); 2364 } 2365 2366 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2367 2368 // Check for pending external suspend. 2369 if (is_external_suspend_with_lock()) { 2370 frame_anchor()->make_walkable(this); 2371 java_suspend_self_with_safepoint_check(); 2372 } 2373 2374 // We might be here for reasons in addition to the self-suspend request 2375 // so check for other async requests. 2376 if (check_asyncs) { 2377 check_and_handle_async_exceptions(); 2378 } 2379 2380 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2381 } 2382 2383 void JavaThread::send_thread_stop(oop java_throwable) { 2384 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2385 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2386 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2387 2388 // Do not throw asynchronous exceptions against the compiler thread 2389 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2390 if (!can_call_java()) return; 2391 2392 { 2393 // Actually throw the Throwable against the target Thread - however 2394 // only if there is no thread death exception installed already. 2395 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2396 // If the topmost frame is a runtime stub, then we are calling into 2397 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2398 // must deoptimize the caller before continuing, as the compiled exception handler table 2399 // may not be valid 2400 if (has_last_Java_frame()) { 2401 frame f = last_frame(); 2402 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2403 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2404 RegisterMap reg_map(this, UseBiasedLocking); 2405 frame compiled_frame = f.sender(®_map); 2406 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2407 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2408 } 2409 } 2410 } 2411 2412 // Set async. pending exception in thread. 2413 set_pending_async_exception(java_throwable); 2414 2415 if (log_is_enabled(Info, exceptions)) { 2416 ResourceMark rm; 2417 log_info(exceptions)("Pending Async. exception installed of type: %s", 2418 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2419 } 2420 // for AbortVMOnException flag 2421 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2422 } 2423 } 2424 2425 2426 // Interrupt thread so it will wake up from a potential wait()/sleep()/park() 2427 java_lang_Thread::set_interrupted(threadObj(), true); 2428 this->interrupt(); 2429 } 2430 2431 // External suspension mechanism. 2432 // 2433 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2434 // to any VM_locks and it is at a transition 2435 // Self-suspension will happen on the transition out of the vm. 2436 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2437 // 2438 // Guarantees on return: 2439 // + Target thread will not execute any new bytecode (that's why we need to 2440 // force a safepoint) 2441 // + Target thread will not enter any new monitors 2442 // 2443 void JavaThread::java_suspend() { 2444 ThreadsListHandle tlh; 2445 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2446 return; 2447 } 2448 2449 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2450 if (!is_external_suspend()) { 2451 // a racing resume has cancelled us; bail out now 2452 return; 2453 } 2454 2455 // suspend is done 2456 uint32_t debug_bits = 0; 2457 // Warning: is_ext_suspend_completed() may temporarily drop the 2458 // SR_lock to allow the thread to reach a stable thread state if 2459 // it is currently in a transient thread state. 2460 if (is_ext_suspend_completed(false /* !called_by_wait */, 2461 SuspendRetryDelay, &debug_bits)) { 2462 return; 2463 } 2464 } 2465 2466 if (Thread::current() == this) { 2467 // Safely self-suspend. 2468 // If we don't do this explicitly it will implicitly happen 2469 // before we transition back to Java, and on some other thread-state 2470 // transition paths, but not as we exit a JVM TI SuspendThread call. 2471 // As SuspendThread(current) must not return (until resumed) we must 2472 // self-suspend here. 2473 ThreadBlockInVM tbivm(this); 2474 java_suspend_self(); 2475 } else { 2476 VM_ThreadSuspend vm_suspend; 2477 VMThread::execute(&vm_suspend); 2478 } 2479 } 2480 2481 // Part II of external suspension. 2482 // A JavaThread self suspends when it detects a pending external suspend 2483 // request. This is usually on transitions. It is also done in places 2484 // where continuing to the next transition would surprise the caller, 2485 // e.g., monitor entry. 2486 // 2487 // Returns the number of times that the thread self-suspended. 2488 // 2489 // Note: DO NOT call java_suspend_self() when you just want to block current 2490 // thread. java_suspend_self() is the second stage of cooperative 2491 // suspension for external suspend requests and should only be used 2492 // to complete an external suspend request. 2493 // 2494 int JavaThread::java_suspend_self() { 2495 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2496 int ret = 0; 2497 2498 // we are in the process of exiting so don't suspend 2499 if (is_exiting()) { 2500 clear_external_suspend(); 2501 return ret; 2502 } 2503 2504 assert(_anchor.walkable() || 2505 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2506 "must have walkable stack"); 2507 2508 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2509 2510 assert(!this->is_ext_suspended(), 2511 "a thread trying to self-suspend should not already be suspended"); 2512 2513 if (this->is_suspend_equivalent()) { 2514 // If we are self-suspending as a result of the lifting of a 2515 // suspend equivalent condition, then the suspend_equivalent 2516 // flag is not cleared until we set the ext_suspended flag so 2517 // that wait_for_ext_suspend_completion() returns consistent 2518 // results. 2519 this->clear_suspend_equivalent(); 2520 } 2521 2522 // A racing resume may have cancelled us before we grabbed SR_lock 2523 // above. Or another external suspend request could be waiting for us 2524 // by the time we return from SR_lock()->wait(). The thread 2525 // that requested the suspension may already be trying to walk our 2526 // stack and if we return now, we can change the stack out from under 2527 // it. This would be a "bad thing (TM)" and cause the stack walker 2528 // to crash. We stay self-suspended until there are no more pending 2529 // external suspend requests. 2530 while (is_external_suspend()) { 2531 ret++; 2532 this->set_ext_suspended(); 2533 2534 // _ext_suspended flag is cleared by java_resume() 2535 while (is_ext_suspended()) { 2536 ml.wait(); 2537 } 2538 } 2539 return ret; 2540 } 2541 2542 // Helper routine to set up the correct thread state before calling java_suspend_self. 2543 // This is called when regular thread-state transition helpers can't be used because 2544 // we can be in various states, in particular _thread_in_native_trans. 2545 // Because this thread is external suspended the safepoint code will count it as at 2546 // a safepoint, regardless of what its actual current thread-state is. But 2547 // is_ext_suspend_completed() may be waiting to see a thread transition from 2548 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2549 // to _thread_blocked. The problem with setting thread state directly is that a 2550 // safepoint could happen just after java_suspend_self() returns after being resumed, 2551 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2552 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2553 // However, not all initial-states are allowed when performing a safepoint check, as we 2554 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2555 // only _thread_in_native is possible when executing this code (based on our two callers). 2556 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2557 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2558 // and so we don't need the explicit safepoint check. 2559 2560 void JavaThread::java_suspend_self_with_safepoint_check() { 2561 assert(this == Thread::current(), "invariant"); 2562 JavaThreadState state = thread_state(); 2563 set_thread_state(_thread_blocked); 2564 java_suspend_self(); 2565 set_thread_state_fence(state); 2566 // Since we are not using a regular thread-state transition helper here, 2567 // we must manually emit the instruction barrier after leaving a safe state. 2568 OrderAccess::cross_modify_fence(); 2569 if (state != _thread_in_native) { 2570 SafepointMechanism::block_if_requested(this); 2571 } 2572 } 2573 2574 #ifdef ASSERT 2575 // Verify the JavaThread has not yet been published in the Threads::list, and 2576 // hence doesn't need protection from concurrent access at this stage. 2577 void JavaThread::verify_not_published() { 2578 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2579 // since an unpublished JavaThread doesn't participate in the 2580 // Thread-SMR protocol for keeping a ThreadsList alive. 2581 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2582 } 2583 #endif 2584 2585 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2586 // progress or when _suspend_flags is non-zero. 2587 // Current thread needs to self-suspend if there is a suspend request and/or 2588 // block if a safepoint is in progress. 2589 // Async exception ISN'T checked. 2590 // Note only the ThreadInVMfromNative transition can call this function 2591 // directly and when thread state is _thread_in_native_trans 2592 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2593 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2594 2595 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2596 2597 if (thread->is_external_suspend()) { 2598 thread->java_suspend_self_with_safepoint_check(); 2599 } else { 2600 SafepointMechanism::block_if_requested(thread); 2601 } 2602 2603 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2604 } 2605 2606 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2607 // progress or when _suspend_flags is non-zero. 2608 // Current thread needs to self-suspend if there is a suspend request and/or 2609 // block if a safepoint is in progress. 2610 // Also check for pending async exception (not including unsafe access error). 2611 // Note only the native==>VM/Java barriers can call this function and when 2612 // thread state is _thread_in_native_trans. 2613 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2614 check_safepoint_and_suspend_for_native_trans(thread); 2615 2616 if (thread->has_async_exception()) { 2617 // We are in _thread_in_native_trans state, don't handle unsafe 2618 // access error since that may block. 2619 thread->check_and_handle_async_exceptions(false); 2620 } 2621 } 2622 2623 // This is a variant of the normal 2624 // check_special_condition_for_native_trans with slightly different 2625 // semantics for use by critical native wrappers. It does all the 2626 // normal checks but also performs the transition back into 2627 // thread_in_Java state. This is required so that critical natives 2628 // can potentially block and perform a GC if they are the last thread 2629 // exiting the GCLocker. 2630 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2631 check_special_condition_for_native_trans(thread); 2632 2633 // Finish the transition 2634 thread->set_thread_state(_thread_in_Java); 2635 2636 if (thread->do_critical_native_unlock()) { 2637 ThreadInVMfromJavaNoAsyncException tiv(thread); 2638 GCLocker::unlock_critical(thread); 2639 thread->clear_critical_native_unlock(); 2640 } 2641 } 2642 2643 // We need to guarantee the Threads_lock here, since resumes are not 2644 // allowed during safepoint synchronization 2645 // Can only resume from an external suspension 2646 void JavaThread::java_resume() { 2647 assert_locked_or_safepoint(Threads_lock); 2648 2649 // Sanity check: thread is gone, has started exiting or the thread 2650 // was not externally suspended. 2651 ThreadsListHandle tlh; 2652 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2653 return; 2654 } 2655 2656 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2657 2658 clear_external_suspend(); 2659 2660 if (is_ext_suspended()) { 2661 clear_ext_suspended(); 2662 SR_lock()->notify_all(); 2663 } 2664 } 2665 2666 size_t JavaThread::_stack_red_zone_size = 0; 2667 size_t JavaThread::_stack_yellow_zone_size = 0; 2668 size_t JavaThread::_stack_reserved_zone_size = 0; 2669 size_t JavaThread::_stack_shadow_zone_size = 0; 2670 2671 void JavaThread::create_stack_guard_pages() { 2672 if (!os::uses_stack_guard_pages() || 2673 _stack_guard_state != stack_guard_unused || 2674 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2675 log_info(os, thread)("Stack guard page creation for thread " 2676 UINTX_FORMAT " disabled", os::current_thread_id()); 2677 return; 2678 } 2679 address low_addr = stack_end(); 2680 size_t len = stack_guard_zone_size(); 2681 2682 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2683 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2684 2685 int must_commit = os::must_commit_stack_guard_pages(); 2686 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2687 2688 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2689 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2690 return; 2691 } 2692 2693 if (os::guard_memory((char *) low_addr, len)) { 2694 _stack_guard_state = stack_guard_enabled; 2695 } else { 2696 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2697 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2698 if (os::uncommit_memory((char *) low_addr, len)) { 2699 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2700 } 2701 return; 2702 } 2703 2704 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2705 PTR_FORMAT "-" PTR_FORMAT ".", 2706 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2707 } 2708 2709 void JavaThread::remove_stack_guard_pages() { 2710 assert(Thread::current() == this, "from different thread"); 2711 if (_stack_guard_state == stack_guard_unused) return; 2712 address low_addr = stack_end(); 2713 size_t len = stack_guard_zone_size(); 2714 2715 if (os::must_commit_stack_guard_pages()) { 2716 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2717 _stack_guard_state = stack_guard_unused; 2718 } else { 2719 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2720 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2721 return; 2722 } 2723 } else { 2724 if (_stack_guard_state == stack_guard_unused) return; 2725 if (os::unguard_memory((char *) low_addr, len)) { 2726 _stack_guard_state = stack_guard_unused; 2727 } else { 2728 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2729 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2730 return; 2731 } 2732 } 2733 2734 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2735 PTR_FORMAT "-" PTR_FORMAT ".", 2736 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2737 } 2738 2739 void JavaThread::enable_stack_reserved_zone() { 2740 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2741 2742 // The base notation is from the stack's point of view, growing downward. 2743 // We need to adjust it to work correctly with guard_memory() 2744 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2745 2746 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2747 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2748 2749 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2750 _stack_guard_state = stack_guard_enabled; 2751 } else { 2752 warning("Attempt to guard stack reserved zone failed."); 2753 } 2754 enable_register_stack_guard(); 2755 } 2756 2757 void JavaThread::disable_stack_reserved_zone() { 2758 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2759 2760 // Simply return if called for a thread that does not use guard pages. 2761 if (_stack_guard_state != stack_guard_enabled) return; 2762 2763 // The base notation is from the stack's point of view, growing downward. 2764 // We need to adjust it to work correctly with guard_memory() 2765 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2766 2767 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2768 _stack_guard_state = stack_guard_reserved_disabled; 2769 } else { 2770 warning("Attempt to unguard stack reserved zone failed."); 2771 } 2772 disable_register_stack_guard(); 2773 } 2774 2775 void JavaThread::enable_stack_yellow_reserved_zone() { 2776 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2777 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2778 2779 // The base notation is from the stacks point of view, growing downward. 2780 // We need to adjust it to work correctly with guard_memory() 2781 address base = stack_red_zone_base(); 2782 2783 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2784 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2785 2786 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2787 _stack_guard_state = stack_guard_enabled; 2788 } else { 2789 warning("Attempt to guard stack yellow zone failed."); 2790 } 2791 enable_register_stack_guard(); 2792 } 2793 2794 void JavaThread::disable_stack_yellow_reserved_zone() { 2795 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2796 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2797 2798 // Simply return if called for a thread that does not use guard pages. 2799 if (_stack_guard_state == stack_guard_unused) return; 2800 2801 // The base notation is from the stacks point of view, growing downward. 2802 // We need to adjust it to work correctly with guard_memory() 2803 address base = stack_red_zone_base(); 2804 2805 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2806 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2807 } else { 2808 warning("Attempt to unguard stack yellow zone failed."); 2809 } 2810 disable_register_stack_guard(); 2811 } 2812 2813 void JavaThread::enable_stack_red_zone() { 2814 // The base notation is from the stacks point of view, growing downward. 2815 // We need to adjust it to work correctly with guard_memory() 2816 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2817 address base = stack_red_zone_base() - stack_red_zone_size(); 2818 2819 guarantee(base < stack_base(), "Error calculating stack red zone"); 2820 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2821 2822 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2823 warning("Attempt to guard stack red zone failed."); 2824 } 2825 } 2826 2827 void JavaThread::disable_stack_red_zone() { 2828 // The base notation is from the stacks point of view, growing downward. 2829 // We need to adjust it to work correctly with guard_memory() 2830 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2831 address base = stack_red_zone_base() - stack_red_zone_size(); 2832 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2833 warning("Attempt to unguard stack red zone failed."); 2834 } 2835 } 2836 2837 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2838 // ignore is there is no stack 2839 if (!has_last_Java_frame()) return; 2840 // traverse the stack frames. Starts from top frame. 2841 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2842 frame* fr = fst.current(); 2843 f(fr, fst.register_map()); 2844 } 2845 } 2846 2847 2848 #ifndef PRODUCT 2849 // Deoptimization 2850 // Function for testing deoptimization 2851 void JavaThread::deoptimize() { 2852 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2853 StackFrameStream fst(this, UseBiasedLocking); 2854 bool deopt = false; // Dump stack only if a deopt actually happens. 2855 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2856 // Iterate over all frames in the thread and deoptimize 2857 for (; !fst.is_done(); fst.next()) { 2858 if (fst.current()->can_be_deoptimized()) { 2859 2860 if (only_at) { 2861 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2862 // consists of comma or carriage return separated numbers so 2863 // search for the current bci in that string. 2864 address pc = fst.current()->pc(); 2865 nmethod* nm = (nmethod*) fst.current()->cb(); 2866 ScopeDesc* sd = nm->scope_desc_at(pc); 2867 char buffer[8]; 2868 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2869 size_t len = strlen(buffer); 2870 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2871 while (found != NULL) { 2872 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2873 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2874 // Check that the bci found is bracketed by terminators. 2875 break; 2876 } 2877 found = strstr(found + 1, buffer); 2878 } 2879 if (!found) { 2880 continue; 2881 } 2882 } 2883 2884 if (DebugDeoptimization && !deopt) { 2885 deopt = true; // One-time only print before deopt 2886 tty->print_cr("[BEFORE Deoptimization]"); 2887 trace_frames(); 2888 trace_stack(); 2889 } 2890 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2891 } 2892 } 2893 2894 if (DebugDeoptimization && deopt) { 2895 tty->print_cr("[AFTER Deoptimization]"); 2896 trace_frames(); 2897 } 2898 } 2899 2900 2901 // Make zombies 2902 void JavaThread::make_zombies() { 2903 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2904 if (fst.current()->can_be_deoptimized()) { 2905 // it is a Java nmethod 2906 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2907 nm->make_not_entrant(); 2908 } 2909 } 2910 } 2911 #endif // PRODUCT 2912 2913 2914 void JavaThread::deoptimize_marked_methods() { 2915 if (!has_last_Java_frame()) return; 2916 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2917 StackFrameStream fst(this, UseBiasedLocking); 2918 for (; !fst.is_done(); fst.next()) { 2919 if (fst.current()->should_be_deoptimized()) { 2920 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2921 } 2922 } 2923 } 2924 2925 // If the caller is a NamedThread, then remember, in the current scope, 2926 // the given JavaThread in its _processed_thread field. 2927 class RememberProcessedThread: public StackObj { 2928 NamedThread* _cur_thr; 2929 public: 2930 RememberProcessedThread(JavaThread* jthr) { 2931 Thread* thread = Thread::current(); 2932 if (thread->is_Named_thread()) { 2933 _cur_thr = (NamedThread *)thread; 2934 _cur_thr->set_processed_thread(jthr); 2935 } else { 2936 _cur_thr = NULL; 2937 } 2938 } 2939 2940 ~RememberProcessedThread() { 2941 if (_cur_thr) { 2942 _cur_thr->set_processed_thread(NULL); 2943 } 2944 } 2945 }; 2946 2947 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2948 // Verify that the deferred card marks have been flushed. 2949 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2950 2951 // Traverse the GCHandles 2952 Thread::oops_do(f, cf); 2953 2954 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2955 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2956 2957 if (has_last_Java_frame()) { 2958 // Record JavaThread to GC thread 2959 RememberProcessedThread rpt(this); 2960 2961 // traverse the registered growable array 2962 if (_array_for_gc != NULL) { 2963 for (int index = 0; index < _array_for_gc->length(); index++) { 2964 f->do_oop(_array_for_gc->adr_at(index)); 2965 } 2966 } 2967 2968 // Traverse the monitor chunks 2969 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2970 chunk->oops_do(f); 2971 } 2972 2973 // Traverse the execution stack 2974 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2975 fst.current()->oops_do(f, cf, fst.register_map()); 2976 } 2977 } 2978 2979 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2980 // If we have deferred set_locals there might be oops waiting to be 2981 // written 2982 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2983 if (list != NULL) { 2984 for (int i = 0; i < list->length(); i++) { 2985 list->at(i)->oops_do(f); 2986 } 2987 } 2988 2989 // Traverse instance variables at the end since the GC may be moving things 2990 // around using this function 2991 f->do_oop((oop*) &_threadObj); 2992 f->do_oop((oop*) &_vm_result); 2993 f->do_oop((oop*) &_exception_oop); 2994 f->do_oop((oop*) &_pending_async_exception); 2995 2996 if (jvmti_thread_state() != NULL) { 2997 jvmti_thread_state()->oops_do(f); 2998 } 2999 } 3000 3001 #ifdef ASSERT 3002 void JavaThread::verify_states_for_handshake() { 3003 // This checks that the thread has a correct frame state during a handshake. 3004 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3005 (has_last_Java_frame() && java_call_counter() > 0), 3006 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3007 has_last_Java_frame(), java_call_counter()); 3008 } 3009 #endif 3010 3011 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 3012 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3013 (has_last_Java_frame() && java_call_counter() > 0), 3014 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3015 has_last_Java_frame(), java_call_counter()); 3016 3017 if (has_last_Java_frame()) { 3018 // Traverse the execution stack 3019 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3020 fst.current()->nmethods_do(cf); 3021 } 3022 } 3023 } 3024 3025 void JavaThread::metadata_do(MetadataClosure* f) { 3026 if (has_last_Java_frame()) { 3027 // Traverse the execution stack to call f() on the methods in the stack 3028 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3029 fst.current()->metadata_do(f); 3030 } 3031 } else if (is_Compiler_thread()) { 3032 // need to walk ciMetadata in current compile tasks to keep alive. 3033 CompilerThread* ct = (CompilerThread*)this; 3034 if (ct->env() != NULL) { 3035 ct->env()->metadata_do(f); 3036 } 3037 CompileTask* task = ct->task(); 3038 if (task != NULL) { 3039 task->metadata_do(f); 3040 } 3041 } 3042 } 3043 3044 // Printing 3045 const char* _get_thread_state_name(JavaThreadState _thread_state) { 3046 switch (_thread_state) { 3047 case _thread_uninitialized: return "_thread_uninitialized"; 3048 case _thread_new: return "_thread_new"; 3049 case _thread_new_trans: return "_thread_new_trans"; 3050 case _thread_in_native: return "_thread_in_native"; 3051 case _thread_in_native_trans: return "_thread_in_native_trans"; 3052 case _thread_in_vm: return "_thread_in_vm"; 3053 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3054 case _thread_in_Java: return "_thread_in_Java"; 3055 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3056 case _thread_blocked: return "_thread_blocked"; 3057 case _thread_blocked_trans: return "_thread_blocked_trans"; 3058 default: return "unknown thread state"; 3059 } 3060 } 3061 3062 #ifndef PRODUCT 3063 void JavaThread::print_thread_state_on(outputStream *st) const { 3064 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3065 }; 3066 #endif // PRODUCT 3067 3068 // Called by Threads::print() for VM_PrintThreads operation 3069 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3070 st->print_raw("\""); 3071 st->print_raw(get_thread_name()); 3072 st->print_raw("\" "); 3073 oop thread_oop = threadObj(); 3074 if (thread_oop != NULL) { 3075 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3076 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3077 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3078 } 3079 Thread::print_on(st, print_extended_info); 3080 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3081 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3082 if (thread_oop != NULL) { 3083 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3084 } 3085 #ifndef PRODUCT 3086 _safepoint_state->print_on(st); 3087 #endif // PRODUCT 3088 if (is_Compiler_thread()) { 3089 CompileTask *task = ((CompilerThread*)this)->task(); 3090 if (task != NULL) { 3091 st->print(" Compiling: "); 3092 task->print(st, NULL, true, false); 3093 } else { 3094 st->print(" No compile task"); 3095 } 3096 st->cr(); 3097 } 3098 } 3099 3100 void JavaThread::print() const { print_on(tty); } 3101 3102 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3103 st->print("%s", get_thread_name_string(buf, buflen)); 3104 } 3105 3106 // Called by fatal error handler. The difference between this and 3107 // JavaThread::print() is that we can't grab lock or allocate memory. 3108 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3109 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3110 oop thread_obj = threadObj(); 3111 if (thread_obj != NULL) { 3112 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3113 } 3114 st->print(" ["); 3115 st->print("%s", _get_thread_state_name(_thread_state)); 3116 if (osthread()) { 3117 st->print(", id=%d", osthread()->thread_id()); 3118 } 3119 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3120 p2i(stack_end()), p2i(stack_base())); 3121 st->print("]"); 3122 3123 ThreadsSMRSupport::print_info_on(this, st); 3124 return; 3125 } 3126 3127 // Verification 3128 3129 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3130 3131 void JavaThread::verify() { 3132 // Verify oops in the thread. 3133 oops_do(&VerifyOopClosure::verify_oop, NULL); 3134 3135 // Verify the stack frames. 3136 frames_do(frame_verify); 3137 } 3138 3139 // CR 6300358 (sub-CR 2137150) 3140 // Most callers of this method assume that it can't return NULL but a 3141 // thread may not have a name whilst it is in the process of attaching to 3142 // the VM - see CR 6412693, and there are places where a JavaThread can be 3143 // seen prior to having it's threadObj set (eg JNI attaching threads and 3144 // if vm exit occurs during initialization). These cases can all be accounted 3145 // for such that this method never returns NULL. 3146 const char* JavaThread::get_thread_name() const { 3147 #ifdef ASSERT 3148 // early safepoints can hit while current thread does not yet have TLS 3149 if (!SafepointSynchronize::is_at_safepoint()) { 3150 Thread *cur = Thread::current(); 3151 if (!(cur->is_Java_thread() && cur == this)) { 3152 // Current JavaThreads are allowed to get their own name without 3153 // the Threads_lock. 3154 assert_locked_or_safepoint(Threads_lock); 3155 } 3156 } 3157 #endif // ASSERT 3158 return get_thread_name_string(); 3159 } 3160 3161 // Returns a non-NULL representation of this thread's name, or a suitable 3162 // descriptive string if there is no set name 3163 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3164 const char* name_str; 3165 oop thread_obj = threadObj(); 3166 if (thread_obj != NULL) { 3167 oop name = java_lang_Thread::name(thread_obj); 3168 if (name != NULL) { 3169 if (buf == NULL) { 3170 name_str = java_lang_String::as_utf8_string(name); 3171 } else { 3172 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3173 } 3174 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3175 name_str = "<no-name - thread is attaching>"; 3176 } else { 3177 name_str = Thread::name(); 3178 } 3179 } else { 3180 name_str = Thread::name(); 3181 } 3182 assert(name_str != NULL, "unexpected NULL thread name"); 3183 return name_str; 3184 } 3185 3186 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3187 3188 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3189 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3190 // Link Java Thread object <-> C++ Thread 3191 3192 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3193 // and put it into a new Handle. The Handle "thread_oop" can then 3194 // be used to pass the C++ thread object to other methods. 3195 3196 // Set the Java level thread object (jthread) field of the 3197 // new thread (a JavaThread *) to C++ thread object using the 3198 // "thread_oop" handle. 3199 3200 // Set the thread field (a JavaThread *) of the 3201 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3202 3203 Handle thread_oop(Thread::current(), 3204 JNIHandles::resolve_non_null(jni_thread)); 3205 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3206 "must be initialized"); 3207 set_threadObj(thread_oop()); 3208 java_lang_Thread::set_thread(thread_oop(), this); 3209 3210 if (prio == NoPriority) { 3211 prio = java_lang_Thread::priority(thread_oop()); 3212 assert(prio != NoPriority, "A valid priority should be present"); 3213 } 3214 3215 // Push the Java priority down to the native thread; needs Threads_lock 3216 Thread::set_priority(this, prio); 3217 3218 // Add the new thread to the Threads list and set it in motion. 3219 // We must have threads lock in order to call Threads::add. 3220 // It is crucial that we do not block before the thread is 3221 // added to the Threads list for if a GC happens, then the java_thread oop 3222 // will not be visited by GC. 3223 Threads::add(this); 3224 } 3225 3226 oop JavaThread::current_park_blocker() { 3227 // Support for JSR-166 locks 3228 oop thread_oop = threadObj(); 3229 if (thread_oop != NULL) { 3230 return java_lang_Thread::park_blocker(thread_oop); 3231 } 3232 return NULL; 3233 } 3234 3235 3236 void JavaThread::print_stack_on(outputStream* st) { 3237 if (!has_last_Java_frame()) return; 3238 ResourceMark rm; 3239 HandleMark hm; 3240 3241 RegisterMap reg_map(this); 3242 vframe* start_vf = last_java_vframe(®_map); 3243 int count = 0; 3244 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3245 if (f->is_java_frame()) { 3246 javaVFrame* jvf = javaVFrame::cast(f); 3247 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3248 3249 // Print out lock information 3250 if (JavaMonitorsInStackTrace) { 3251 jvf->print_lock_info_on(st, count); 3252 } 3253 } else { 3254 // Ignore non-Java frames 3255 } 3256 3257 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3258 count++; 3259 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3260 } 3261 } 3262 3263 3264 // JVMTI PopFrame support 3265 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3266 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3267 if (in_bytes(size_in_bytes) != 0) { 3268 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3269 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3270 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3271 } 3272 } 3273 3274 void* JavaThread::popframe_preserved_args() { 3275 return _popframe_preserved_args; 3276 } 3277 3278 ByteSize JavaThread::popframe_preserved_args_size() { 3279 return in_ByteSize(_popframe_preserved_args_size); 3280 } 3281 3282 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3283 int sz = in_bytes(popframe_preserved_args_size()); 3284 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3285 return in_WordSize(sz / wordSize); 3286 } 3287 3288 void JavaThread::popframe_free_preserved_args() { 3289 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3290 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args); 3291 _popframe_preserved_args = NULL; 3292 _popframe_preserved_args_size = 0; 3293 } 3294 3295 #ifndef PRODUCT 3296 3297 void JavaThread::trace_frames() { 3298 tty->print_cr("[Describe stack]"); 3299 int frame_no = 1; 3300 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3301 tty->print(" %d. ", frame_no++); 3302 fst.current()->print_value_on(tty, this); 3303 tty->cr(); 3304 } 3305 } 3306 3307 class PrintAndVerifyOopClosure: public OopClosure { 3308 protected: 3309 template <class T> inline void do_oop_work(T* p) { 3310 oop obj = RawAccess<>::oop_load(p); 3311 if (obj == NULL) return; 3312 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3313 if (oopDesc::is_oop_or_null(obj)) { 3314 if (obj->is_objArray()) { 3315 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3316 } else { 3317 obj->print(); 3318 } 3319 } else { 3320 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3321 } 3322 tty->cr(); 3323 } 3324 public: 3325 virtual void do_oop(oop* p) { do_oop_work(p); } 3326 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3327 }; 3328 3329 #ifdef ASSERT 3330 // Print or validate the layout of stack frames 3331 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3332 ResourceMark rm; 3333 PRESERVE_EXCEPTION_MARK; 3334 FrameValues values; 3335 int frame_no = 0; 3336 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3337 fst.current()->describe(values, ++frame_no); 3338 if (depth == frame_no) break; 3339 } 3340 if (validate_only) { 3341 values.validate(); 3342 } else { 3343 tty->print_cr("[Describe stack layout]"); 3344 values.print(this); 3345 } 3346 } 3347 #endif 3348 3349 void JavaThread::trace_stack_from(vframe* start_vf) { 3350 ResourceMark rm; 3351 int vframe_no = 1; 3352 for (vframe* f = start_vf; f; f = f->sender()) { 3353 if (f->is_java_frame()) { 3354 javaVFrame::cast(f)->print_activation(vframe_no++); 3355 } else { 3356 f->print(); 3357 } 3358 if (vframe_no > StackPrintLimit) { 3359 tty->print_cr("...<more frames>..."); 3360 return; 3361 } 3362 } 3363 } 3364 3365 3366 void JavaThread::trace_stack() { 3367 if (!has_last_Java_frame()) return; 3368 ResourceMark rm; 3369 HandleMark hm; 3370 RegisterMap reg_map(this); 3371 trace_stack_from(last_java_vframe(®_map)); 3372 } 3373 3374 3375 #endif // PRODUCT 3376 3377 3378 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3379 assert(reg_map != NULL, "a map must be given"); 3380 frame f = last_frame(); 3381 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3382 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3383 } 3384 return NULL; 3385 } 3386 3387 3388 Klass* JavaThread::security_get_caller_class(int depth) { 3389 vframeStream vfst(this); 3390 vfst.security_get_caller_frame(depth); 3391 if (!vfst.at_end()) { 3392 return vfst.method()->method_holder(); 3393 } 3394 return NULL; 3395 } 3396 3397 // java.lang.Thread.sleep support 3398 // Returns true if sleep time elapsed as expected, and false 3399 // if the thread was interrupted. 3400 bool JavaThread::sleep(jlong millis) { 3401 assert(this == Thread::current(), "thread consistency check"); 3402 3403 ParkEvent * const slp = this->_SleepEvent; 3404 // Because there can be races with thread interruption sending an unpark() 3405 // to the event, we explicitly reset it here to avoid an immediate return. 3406 // The actual interrupt state will be checked before we park(). 3407 slp->reset(); 3408 // Thread interruption establishes a happens-before ordering in the 3409 // Java Memory Model, so we need to ensure we synchronize with the 3410 // interrupt state. 3411 OrderAccess::fence(); 3412 3413 jlong prevtime = os::javaTimeNanos(); 3414 3415 for (;;) { 3416 // interruption has precedence over timing out 3417 if (this->is_interrupted(true)) { 3418 return false; 3419 } 3420 3421 if (millis <= 0) { 3422 return true; 3423 } 3424 3425 { 3426 ThreadBlockInVM tbivm(this); 3427 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 3428 3429 this->set_suspend_equivalent(); 3430 // cleared by handle_special_suspend_equivalent_condition() or 3431 // java_suspend_self() via check_and_wait_while_suspended() 3432 3433 slp->park(millis); 3434 3435 // were we externally suspended while we were waiting? 3436 this->check_and_wait_while_suspended(); 3437 } 3438 3439 // Update elapsed time tracking 3440 jlong newtime = os::javaTimeNanos(); 3441 if (newtime - prevtime < 0) { 3442 // time moving backwards, should only happen if no monotonic clock 3443 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3444 assert(!os::supports_monotonic_clock(), 3445 "unexpected time moving backwards detected in JavaThread::sleep()"); 3446 } else { 3447 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3448 } 3449 prevtime = newtime; 3450 } 3451 } 3452 3453 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3454 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3455 CompileBroker::compiler_thread_loop(); 3456 } 3457 3458 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3459 NMethodSweeper::sweeper_loop(); 3460 } 3461 3462 // Create a CompilerThread 3463 CompilerThread::CompilerThread(CompileQueue* queue, 3464 CompilerCounters* counters) 3465 : JavaThread(&compiler_thread_entry) { 3466 _env = NULL; 3467 _log = NULL; 3468 _task = NULL; 3469 _queue = queue; 3470 _counters = counters; 3471 _buffer_blob = NULL; 3472 _compiler = NULL; 3473 3474 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3475 resource_area()->bias_to(mtCompiler); 3476 3477 #ifndef PRODUCT 3478 _ideal_graph_printer = NULL; 3479 #endif 3480 } 3481 3482 CompilerThread::~CompilerThread() { 3483 // Delete objects which were allocated on heap. 3484 delete _counters; 3485 } 3486 3487 bool CompilerThread::can_call_java() const { 3488 return _compiler != NULL && _compiler->is_jvmci(); 3489 } 3490 3491 // Create sweeper thread 3492 CodeCacheSweeperThread::CodeCacheSweeperThread() 3493 : JavaThread(&sweeper_thread_entry) { 3494 _scanned_compiled_method = NULL; 3495 } 3496 3497 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3498 JavaThread::oops_do(f, cf); 3499 if (_scanned_compiled_method != NULL && cf != NULL) { 3500 // Safepoints can occur when the sweeper is scanning an nmethod so 3501 // process it here to make sure it isn't unloaded in the middle of 3502 // a scan. 3503 cf->do_code_blob(_scanned_compiled_method); 3504 } 3505 } 3506 3507 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3508 JavaThread::nmethods_do(cf); 3509 if (_scanned_compiled_method != NULL && cf != NULL) { 3510 // Safepoints can occur when the sweeper is scanning an nmethod so 3511 // process it here to make sure it isn't unloaded in the middle of 3512 // a scan. 3513 cf->do_code_blob(_scanned_compiled_method); 3514 } 3515 } 3516 3517 3518 // ======= Threads ======== 3519 3520 // The Threads class links together all active threads, and provides 3521 // operations over all threads. It is protected by the Threads_lock, 3522 // which is also used in other global contexts like safepointing. 3523 // ThreadsListHandles are used to safely perform operations on one 3524 // or more threads without the risk of the thread exiting during the 3525 // operation. 3526 // 3527 // Note: The Threads_lock is currently more widely used than we 3528 // would like. We are actively migrating Threads_lock uses to other 3529 // mechanisms in order to reduce Threads_lock contention. 3530 3531 int Threads::_number_of_threads = 0; 3532 int Threads::_number_of_non_daemon_threads = 0; 3533 int Threads::_return_code = 0; 3534 uintx Threads::_thread_claim_token = 1; // Never zero. 3535 size_t JavaThread::_stack_size_at_create = 0; 3536 3537 #ifdef ASSERT 3538 bool Threads::_vm_complete = false; 3539 #endif 3540 3541 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3542 Prefetch::read((void*)addr, prefetch_interval); 3543 return *addr; 3544 } 3545 3546 // Possibly the ugliest for loop the world has seen. C++ does not allow 3547 // multiple types in the declaration section of the for loop. In this case 3548 // we are only dealing with pointers and hence can cast them. It looks ugly 3549 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3550 #define DO_JAVA_THREADS(LIST, X) \ 3551 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3552 *MACRO_list = (JavaThread*)(LIST), \ 3553 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3554 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3555 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3556 MACRO_current_p != MACRO_end; \ 3557 MACRO_current_p++, \ 3558 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3559 3560 // All JavaThreads 3561 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3562 3563 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3564 void Threads::non_java_threads_do(ThreadClosure* tc) { 3565 NoSafepointVerifier nsv; 3566 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3567 tc->do_thread(njti.current()); 3568 } 3569 } 3570 3571 // All JavaThreads 3572 void Threads::java_threads_do(ThreadClosure* tc) { 3573 assert_locked_or_safepoint(Threads_lock); 3574 // ALL_JAVA_THREADS iterates through all JavaThreads. 3575 ALL_JAVA_THREADS(p) { 3576 tc->do_thread(p); 3577 } 3578 } 3579 3580 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3581 assert_locked_or_safepoint(Threads_lock); 3582 java_threads_do(tc); 3583 tc->do_thread(VMThread::vm_thread()); 3584 } 3585 3586 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3587 void Threads::threads_do(ThreadClosure* tc) { 3588 assert_locked_or_safepoint(Threads_lock); 3589 java_threads_do(tc); 3590 non_java_threads_do(tc); 3591 } 3592 3593 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3594 uintx claim_token = Threads::thread_claim_token(); 3595 ALL_JAVA_THREADS(p) { 3596 if (p->claim_threads_do(is_par, claim_token)) { 3597 tc->do_thread(p); 3598 } 3599 } 3600 VMThread* vmt = VMThread::vm_thread(); 3601 if (vmt->claim_threads_do(is_par, claim_token)) { 3602 tc->do_thread(vmt); 3603 } 3604 } 3605 3606 // The system initialization in the library has three phases. 3607 // 3608 // Phase 1: java.lang.System class initialization 3609 // java.lang.System is a primordial class loaded and initialized 3610 // by the VM early during startup. java.lang.System.<clinit> 3611 // only does registerNatives and keeps the rest of the class 3612 // initialization work later until thread initialization completes. 3613 // 3614 // System.initPhase1 initializes the system properties, the static 3615 // fields in, out, and err. Set up java signal handlers, OS-specific 3616 // system settings, and thread group of the main thread. 3617 static void call_initPhase1(TRAPS) { 3618 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3619 JavaValue result(T_VOID); 3620 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3621 vmSymbols::void_method_signature(), CHECK); 3622 } 3623 3624 // Phase 2. Module system initialization 3625 // This will initialize the module system. Only java.base classes 3626 // can be loaded until phase 2 completes. 3627 // 3628 // Call System.initPhase2 after the compiler initialization and jsr292 3629 // classes get initialized because module initialization runs a lot of java 3630 // code, that for performance reasons, should be compiled. Also, this will 3631 // enable the startup code to use lambda and other language features in this 3632 // phase and onward. 3633 // 3634 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3635 static void call_initPhase2(TRAPS) { 3636 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3637 3638 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3639 3640 JavaValue result(T_INT); 3641 JavaCallArguments args; 3642 args.push_int(DisplayVMOutputToStderr); 3643 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3644 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3645 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3646 if (result.get_jint() != JNI_OK) { 3647 vm_exit_during_initialization(); // no message or exception 3648 } 3649 3650 universe_post_module_init(); 3651 } 3652 3653 // Phase 3. final setup - set security manager, system class loader and TCCL 3654 // 3655 // This will instantiate and set the security manager, set the system class 3656 // loader as well as the thread context class loader. The security manager 3657 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3658 // other modules or the application's classpath. 3659 static void call_initPhase3(TRAPS) { 3660 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3661 JavaValue result(T_VOID); 3662 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3663 vmSymbols::void_method_signature(), CHECK); 3664 } 3665 3666 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3667 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3668 3669 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3670 create_vm_init_libraries(); 3671 } 3672 3673 initialize_class(vmSymbols::java_lang_String(), CHECK); 3674 3675 // Inject CompactStrings value after the static initializers for String ran. 3676 java_lang_String::set_compact_strings(CompactStrings); 3677 3678 // Initialize java_lang.System (needed before creating the thread) 3679 initialize_class(vmSymbols::java_lang_System(), CHECK); 3680 // The VM creates & returns objects of this class. Make sure it's initialized. 3681 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3682 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3683 Handle thread_group = create_initial_thread_group(CHECK); 3684 Universe::set_main_thread_group(thread_group()); 3685 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3686 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3687 main_thread->set_threadObj(thread_object); 3688 3689 // Set thread status to running since main thread has 3690 // been started and running. 3691 java_lang_Thread::set_thread_status(thread_object, 3692 java_lang_Thread::RUNNABLE); 3693 3694 // The VM creates objects of this class. 3695 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3696 3697 #ifdef ASSERT 3698 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3699 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3700 #endif 3701 3702 // initialize the hardware-specific constants needed by Unsafe 3703 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3704 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3705 3706 // The VM preresolves methods to these classes. Make sure that they get initialized 3707 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3708 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3709 3710 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3711 call_initPhase1(CHECK); 3712 3713 // get the Java runtime name, version, and vendor info after java.lang.System is initialized 3714 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3715 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3716 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD)); 3717 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD)); 3718 3719 // an instance of OutOfMemory exception has been allocated earlier 3720 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3721 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3722 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3723 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3724 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3725 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3726 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3727 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3728 3729 // Eager box cache initialization only if AOT is on and any library is loaded. 3730 AOTLoader::initialize_box_caches(CHECK); 3731 } 3732 3733 void Threads::initialize_jsr292_core_classes(TRAPS) { 3734 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3735 3736 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3737 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3738 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3739 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3740 } 3741 3742 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3743 extern void JDK_Version_init(); 3744 3745 // Preinitialize version info. 3746 VM_Version::early_initialize(); 3747 3748 // Check version 3749 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3750 3751 // Initialize library-based TLS 3752 ThreadLocalStorage::init(); 3753 3754 // Initialize the output stream module 3755 ostream_init(); 3756 3757 // Process java launcher properties. 3758 Arguments::process_sun_java_launcher_properties(args); 3759 3760 // Initialize the os module 3761 os::init(); 3762 3763 // Record VM creation timing statistics 3764 TraceVmCreationTime create_vm_timer; 3765 create_vm_timer.start(); 3766 3767 // Initialize system properties. 3768 Arguments::init_system_properties(); 3769 3770 // So that JDK version can be used as a discriminator when parsing arguments 3771 JDK_Version_init(); 3772 3773 // Update/Initialize System properties after JDK version number is known 3774 Arguments::init_version_specific_system_properties(); 3775 3776 // Make sure to initialize log configuration *before* parsing arguments 3777 LogConfiguration::initialize(create_vm_timer.begin_time()); 3778 3779 // Parse arguments 3780 // Note: this internally calls os::init_container_support() 3781 jint parse_result = Arguments::parse(args); 3782 if (parse_result != JNI_OK) return parse_result; 3783 3784 os::init_before_ergo(); 3785 3786 jint ergo_result = Arguments::apply_ergo(); 3787 if (ergo_result != JNI_OK) return ergo_result; 3788 3789 // Final check of all ranges after ergonomics which may change values. 3790 if (!JVMFlagRangeList::check_ranges()) { 3791 return JNI_EINVAL; 3792 } 3793 3794 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3795 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3796 if (!constraint_result) { 3797 return JNI_EINVAL; 3798 } 3799 3800 JVMFlagWriteableList::mark_startup(); 3801 3802 if (PauseAtStartup) { 3803 os::pause(); 3804 } 3805 3806 HOTSPOT_VM_INIT_BEGIN(); 3807 3808 // Timing (must come after argument parsing) 3809 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3810 3811 // Initialize the os module after parsing the args 3812 jint os_init_2_result = os::init_2(); 3813 if (os_init_2_result != JNI_OK) return os_init_2_result; 3814 3815 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3816 // Initialize assert poison page mechanism. 3817 if (ShowRegistersOnAssert) { 3818 initialize_assert_poison(); 3819 } 3820 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3821 3822 SafepointMechanism::initialize(); 3823 3824 jint adjust_after_os_result = Arguments::adjust_after_os(); 3825 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3826 3827 // Initialize output stream logging 3828 ostream_init_log(); 3829 3830 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3831 // Must be before create_vm_init_agents() 3832 if (Arguments::init_libraries_at_startup()) { 3833 convert_vm_init_libraries_to_agents(); 3834 } 3835 3836 // Launch -agentlib/-agentpath and converted -Xrun agents 3837 if (Arguments::init_agents_at_startup()) { 3838 create_vm_init_agents(); 3839 } 3840 3841 // Initialize Threads state 3842 _number_of_threads = 0; 3843 _number_of_non_daemon_threads = 0; 3844 3845 // Initialize global data structures and create system classes in heap 3846 vm_init_globals(); 3847 3848 #if INCLUDE_JVMCI 3849 if (JVMCICounterSize > 0) { 3850 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3851 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3852 } else { 3853 JavaThread::_jvmci_old_thread_counters = NULL; 3854 } 3855 #endif // INCLUDE_JVMCI 3856 3857 // Attach the main thread to this os thread 3858 JavaThread* main_thread = new JavaThread(); 3859 main_thread->set_thread_state(_thread_in_vm); 3860 main_thread->initialize_thread_current(); 3861 // must do this before set_active_handles 3862 main_thread->record_stack_base_and_size(); 3863 main_thread->register_thread_stack_with_NMT(); 3864 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3865 3866 if (!main_thread->set_as_starting_thread()) { 3867 vm_shutdown_during_initialization( 3868 "Failed necessary internal allocation. Out of swap space"); 3869 main_thread->smr_delete(); 3870 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3871 return JNI_ENOMEM; 3872 } 3873 3874 // Enable guard page *after* os::create_main_thread(), otherwise it would 3875 // crash Linux VM, see notes in os_linux.cpp. 3876 main_thread->create_stack_guard_pages(); 3877 3878 // Initialize Java-Level synchronization subsystem 3879 ObjectMonitor::Initialize(); 3880 3881 // Initialize global modules 3882 jint status = init_globals(); 3883 if (status != JNI_OK) { 3884 main_thread->smr_delete(); 3885 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3886 return status; 3887 } 3888 3889 JFR_ONLY(Jfr::on_create_vm_1();) 3890 3891 // Should be done after the heap is fully created 3892 main_thread->cache_global_variables(); 3893 3894 HandleMark hm; 3895 3896 { MutexLocker mu(Threads_lock); 3897 Threads::add(main_thread); 3898 } 3899 3900 // Any JVMTI raw monitors entered in onload will transition into 3901 // real raw monitor. VM is setup enough here for raw monitor enter. 3902 JvmtiExport::transition_pending_onload_raw_monitors(); 3903 3904 // Create the VMThread 3905 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3906 3907 VMThread::create(); 3908 Thread* vmthread = VMThread::vm_thread(); 3909 3910 if (!os::create_thread(vmthread, os::vm_thread)) { 3911 vm_exit_during_initialization("Cannot create VM thread. " 3912 "Out of system resources."); 3913 } 3914 3915 // Wait for the VM thread to become ready, and VMThread::run to initialize 3916 // Monitors can have spurious returns, must always check another state flag 3917 { 3918 MonitorLocker ml(Notify_lock); 3919 os::start_thread(vmthread); 3920 while (vmthread->active_handles() == NULL) { 3921 ml.wait(); 3922 } 3923 } 3924 } 3925 3926 assert(Universe::is_fully_initialized(), "not initialized"); 3927 if (VerifyDuringStartup) { 3928 // Make sure we're starting with a clean slate. 3929 VM_Verify verify_op; 3930 VMThread::execute(&verify_op); 3931 } 3932 3933 // We need this to update the java.vm.info property in case any flags used 3934 // to initially define it have been changed. This is needed for both CDS and 3935 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3936 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3937 // This update must happen before we initialize the java classes, but 3938 // after any initialization logic that might modify the flags. 3939 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3940 3941 Thread* THREAD = Thread::current(); 3942 3943 // Always call even when there are not JVMTI environments yet, since environments 3944 // may be attached late and JVMTI must track phases of VM execution 3945 JvmtiExport::enter_early_start_phase(); 3946 3947 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3948 JvmtiExport::post_early_vm_start(); 3949 3950 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3951 3952 quicken_jni_functions(); 3953 3954 // No more stub generation allowed after that point. 3955 StubCodeDesc::freeze(); 3956 3957 // Set flag that basic initialization has completed. Used by exceptions and various 3958 // debug stuff, that does not work until all basic classes have been initialized. 3959 set_init_completed(); 3960 3961 LogConfiguration::post_initialize(); 3962 Metaspace::post_initialize(); 3963 3964 HOTSPOT_VM_INIT_END(); 3965 3966 // record VM initialization completion time 3967 #if INCLUDE_MANAGEMENT 3968 Management::record_vm_init_completed(); 3969 #endif // INCLUDE_MANAGEMENT 3970 3971 // Signal Dispatcher needs to be started before VMInit event is posted 3972 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3973 3974 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3975 if (!DisableAttachMechanism) { 3976 AttachListener::vm_start(); 3977 if (StartAttachListener || AttachListener::init_at_startup()) { 3978 AttachListener::init(); 3979 } 3980 } 3981 3982 // Launch -Xrun agents 3983 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3984 // back-end can launch with -Xdebug -Xrunjdwp. 3985 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3986 create_vm_init_libraries(); 3987 } 3988 3989 if (CleanChunkPoolAsync) { 3990 Chunk::start_chunk_pool_cleaner_task(); 3991 } 3992 3993 3994 // initialize compiler(s) 3995 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3996 #if INCLUDE_JVMCI 3997 bool force_JVMCI_intialization = false; 3998 if (EnableJVMCI) { 3999 // Initialize JVMCI eagerly when it is explicitly requested. 4000 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 4001 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 4002 4003 if (!force_JVMCI_intialization) { 4004 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4005 // compilations via JVMCI will not actually block until JVMCI is initialized. 4006 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4007 } 4008 } 4009 #endif 4010 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 4011 // Postpone completion of compiler initialization to after JVMCI 4012 // is initialized to avoid timeouts of blocking compilations. 4013 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 4014 CompileBroker::compilation_init_phase2(); 4015 } 4016 #endif 4017 4018 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4019 // It is done after compilers are initialized, because otherwise compilations of 4020 // signature polymorphic MH intrinsics can be missed 4021 // (see SystemDictionary::find_method_handle_intrinsic). 4022 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4023 4024 // This will initialize the module system. Only java.base classes can be 4025 // loaded until phase 2 completes 4026 call_initPhase2(CHECK_JNI_ERR); 4027 4028 JFR_ONLY(Jfr::on_create_vm_2();) 4029 4030 // Always call even when there are not JVMTI environments yet, since environments 4031 // may be attached late and JVMTI must track phases of VM execution 4032 JvmtiExport::enter_start_phase(); 4033 4034 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4035 JvmtiExport::post_vm_start(); 4036 4037 // Final system initialization including security manager and system class loader 4038 call_initPhase3(CHECK_JNI_ERR); 4039 4040 // cache the system and platform class loaders 4041 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4042 4043 #if INCLUDE_CDS 4044 // capture the module path info from the ModuleEntryTable 4045 ClassLoader::initialize_module_path(THREAD); 4046 #endif 4047 4048 #if INCLUDE_JVMCI 4049 if (force_JVMCI_intialization) { 4050 JVMCI::initialize_compiler(CHECK_JNI_ERR); 4051 CompileBroker::compilation_init_phase2(); 4052 } 4053 #endif 4054 4055 // Always call even when there are not JVMTI environments yet, since environments 4056 // may be attached late and JVMTI must track phases of VM execution 4057 JvmtiExport::enter_live_phase(); 4058 4059 // Make perfmemory accessible 4060 PerfMemory::set_accessible(true); 4061 4062 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4063 JvmtiExport::post_vm_initialized(); 4064 4065 JFR_ONLY(Jfr::on_create_vm_3();) 4066 4067 #if INCLUDE_MANAGEMENT 4068 Management::initialize(THREAD); 4069 4070 if (HAS_PENDING_EXCEPTION) { 4071 // management agent fails to start possibly due to 4072 // configuration problem and is responsible for printing 4073 // stack trace if appropriate. Simply exit VM. 4074 vm_exit(1); 4075 } 4076 #endif // INCLUDE_MANAGEMENT 4077 4078 if (MemProfiling) MemProfiler::engage(); 4079 StatSampler::engage(); 4080 if (CheckJNICalls) JniPeriodicChecker::engage(); 4081 4082 BiasedLocking::init(); 4083 4084 #if INCLUDE_RTM_OPT 4085 RTMLockingCounters::init(); 4086 #endif 4087 4088 call_postVMInitHook(THREAD); 4089 // The Java side of PostVMInitHook.run must deal with all 4090 // exceptions and provide means of diagnosis. 4091 if (HAS_PENDING_EXCEPTION) { 4092 CLEAR_PENDING_EXCEPTION; 4093 } 4094 4095 { 4096 MutexLocker ml(PeriodicTask_lock); 4097 // Make sure the WatcherThread can be started by WatcherThread::start() 4098 // or by dynamic enrollment. 4099 WatcherThread::make_startable(); 4100 // Start up the WatcherThread if there are any periodic tasks 4101 // NOTE: All PeriodicTasks should be registered by now. If they 4102 // aren't, late joiners might appear to start slowly (we might 4103 // take a while to process their first tick). 4104 if (PeriodicTask::num_tasks() > 0) { 4105 WatcherThread::start(); 4106 } 4107 } 4108 4109 create_vm_timer.end(); 4110 #ifdef ASSERT 4111 _vm_complete = true; 4112 #endif 4113 4114 if (DumpSharedSpaces) { 4115 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4116 ShouldNotReachHere(); 4117 } 4118 4119 return JNI_OK; 4120 } 4121 4122 // type for the Agent_OnLoad and JVM_OnLoad entry points 4123 extern "C" { 4124 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4125 } 4126 // Find a command line agent library and return its entry point for 4127 // -agentlib: -agentpath: -Xrun 4128 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4129 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4130 const char *on_load_symbols[], 4131 size_t num_symbol_entries) { 4132 OnLoadEntry_t on_load_entry = NULL; 4133 void *library = NULL; 4134 4135 if (!agent->valid()) { 4136 char buffer[JVM_MAXPATHLEN]; 4137 char ebuf[1024] = ""; 4138 const char *name = agent->name(); 4139 const char *msg = "Could not find agent library "; 4140 4141 // First check to see if agent is statically linked into executable 4142 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4143 library = agent->os_lib(); 4144 } else if (agent->is_absolute_path()) { 4145 library = os::dll_load(name, ebuf, sizeof ebuf); 4146 if (library == NULL) { 4147 const char *sub_msg = " in absolute path, with error: "; 4148 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4149 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4150 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4151 // If we can't find the agent, exit. 4152 vm_exit_during_initialization(buf, NULL); 4153 FREE_C_HEAP_ARRAY(char, buf); 4154 } 4155 } else { 4156 // Try to load the agent from the standard dll directory 4157 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4158 name)) { 4159 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4160 } 4161 if (library == NULL) { // Try the library path directory. 4162 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4163 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4164 } 4165 if (library == NULL) { 4166 const char *sub_msg = " on the library path, with error: "; 4167 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4168 4169 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4170 strlen(ebuf) + strlen(sub_msg2) + 1; 4171 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4172 if (!agent->is_instrument_lib()) { 4173 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4174 } else { 4175 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4176 } 4177 // If we can't find the agent, exit. 4178 vm_exit_during_initialization(buf, NULL); 4179 FREE_C_HEAP_ARRAY(char, buf); 4180 } 4181 } 4182 } 4183 agent->set_os_lib(library); 4184 agent->set_valid(); 4185 } 4186 4187 // Find the OnLoad function. 4188 on_load_entry = 4189 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4190 false, 4191 on_load_symbols, 4192 num_symbol_entries)); 4193 return on_load_entry; 4194 } 4195 4196 // Find the JVM_OnLoad entry point 4197 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4198 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4199 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4200 } 4201 4202 // Find the Agent_OnLoad entry point 4203 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4204 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4205 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4206 } 4207 4208 // For backwards compatibility with -Xrun 4209 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4210 // treated like -agentpath: 4211 // Must be called before agent libraries are created 4212 void Threads::convert_vm_init_libraries_to_agents() { 4213 AgentLibrary* agent; 4214 AgentLibrary* next; 4215 4216 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4217 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4218 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4219 4220 // If there is an JVM_OnLoad function it will get called later, 4221 // otherwise see if there is an Agent_OnLoad 4222 if (on_load_entry == NULL) { 4223 on_load_entry = lookup_agent_on_load(agent); 4224 if (on_load_entry != NULL) { 4225 // switch it to the agent list -- so that Agent_OnLoad will be called, 4226 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4227 Arguments::convert_library_to_agent(agent); 4228 } else { 4229 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4230 } 4231 } 4232 } 4233 } 4234 4235 // Create agents for -agentlib: -agentpath: and converted -Xrun 4236 // Invokes Agent_OnLoad 4237 // Called very early -- before JavaThreads exist 4238 void Threads::create_vm_init_agents() { 4239 extern struct JavaVM_ main_vm; 4240 AgentLibrary* agent; 4241 4242 JvmtiExport::enter_onload_phase(); 4243 4244 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4245 // CDS dumping does not support native JVMTI agent. 4246 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4247 if (Arguments::is_dumping_archive()) { 4248 if(!agent->is_instrument_lib()) { 4249 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4250 } else if (!AllowArchivingWithJavaAgent) { 4251 vm_exit_during_cds_dumping( 4252 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4253 } 4254 } 4255 4256 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4257 4258 if (on_load_entry != NULL) { 4259 // Invoke the Agent_OnLoad function 4260 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4261 if (err != JNI_OK) { 4262 vm_exit_during_initialization("agent library failed to init", agent->name()); 4263 } 4264 } else { 4265 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4266 } 4267 } 4268 4269 JvmtiExport::enter_primordial_phase(); 4270 } 4271 4272 extern "C" { 4273 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4274 } 4275 4276 void Threads::shutdown_vm_agents() { 4277 // Send any Agent_OnUnload notifications 4278 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4279 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4280 extern struct JavaVM_ main_vm; 4281 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4282 4283 // Find the Agent_OnUnload function. 4284 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4285 os::find_agent_function(agent, 4286 false, 4287 on_unload_symbols, 4288 num_symbol_entries)); 4289 4290 // Invoke the Agent_OnUnload function 4291 if (unload_entry != NULL) { 4292 JavaThread* thread = JavaThread::current(); 4293 ThreadToNativeFromVM ttn(thread); 4294 HandleMark hm(thread); 4295 (*unload_entry)(&main_vm); 4296 } 4297 } 4298 } 4299 4300 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4301 // Invokes JVM_OnLoad 4302 void Threads::create_vm_init_libraries() { 4303 extern struct JavaVM_ main_vm; 4304 AgentLibrary* agent; 4305 4306 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4307 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4308 4309 if (on_load_entry != NULL) { 4310 // Invoke the JVM_OnLoad function 4311 JavaThread* thread = JavaThread::current(); 4312 ThreadToNativeFromVM ttn(thread); 4313 HandleMark hm(thread); 4314 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4315 if (err != JNI_OK) { 4316 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4317 } 4318 } else { 4319 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4320 } 4321 } 4322 } 4323 4324 4325 // Last thread running calls java.lang.Shutdown.shutdown() 4326 void JavaThread::invoke_shutdown_hooks() { 4327 HandleMark hm(this); 4328 4329 // We could get here with a pending exception, if so clear it now. 4330 if (this->has_pending_exception()) { 4331 this->clear_pending_exception(); 4332 } 4333 4334 EXCEPTION_MARK; 4335 Klass* shutdown_klass = 4336 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4337 THREAD); 4338 if (shutdown_klass != NULL) { 4339 // SystemDictionary::resolve_or_null will return null if there was 4340 // an exception. If we cannot load the Shutdown class, just don't 4341 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4342 // won't be run. Note that if a shutdown hook was registered, 4343 // the Shutdown class would have already been loaded 4344 // (Runtime.addShutdownHook will load it). 4345 JavaValue result(T_VOID); 4346 JavaCalls::call_static(&result, 4347 shutdown_klass, 4348 vmSymbols::shutdown_name(), 4349 vmSymbols::void_method_signature(), 4350 THREAD); 4351 } 4352 CLEAR_PENDING_EXCEPTION; 4353 } 4354 4355 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4356 // the program falls off the end of main(). Another VM exit path is through 4357 // vm_exit() when the program calls System.exit() to return a value or when 4358 // there is a serious error in VM. The two shutdown paths are not exactly 4359 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4360 // and VM_Exit op at VM level. 4361 // 4362 // Shutdown sequence: 4363 // + Shutdown native memory tracking if it is on 4364 // + Wait until we are the last non-daemon thread to execute 4365 // <-- every thing is still working at this moment --> 4366 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4367 // shutdown hooks 4368 // + Call before_exit(), prepare for VM exit 4369 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4370 // currently the only user of this mechanism is File.deleteOnExit()) 4371 // > stop StatSampler, watcher thread, 4372 // post thread end and vm death events to JVMTI, 4373 // stop signal thread 4374 // + Call JavaThread::exit(), it will: 4375 // > release JNI handle blocks, remove stack guard pages 4376 // > remove this thread from Threads list 4377 // <-- no more Java code from this thread after this point --> 4378 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4379 // the compiler threads at safepoint 4380 // <-- do not use anything that could get blocked by Safepoint --> 4381 // + Disable tracing at JNI/JVM barriers 4382 // + Set _vm_exited flag for threads that are still running native code 4383 // + Call exit_globals() 4384 // > deletes tty 4385 // > deletes PerfMemory resources 4386 // + Delete this thread 4387 // + Return to caller 4388 4389 bool Threads::destroy_vm() { 4390 JavaThread* thread = JavaThread::current(); 4391 4392 #ifdef ASSERT 4393 _vm_complete = false; 4394 #endif 4395 // Wait until we are the last non-daemon thread to execute 4396 { MonitorLocker nu(Threads_lock); 4397 while (Threads::number_of_non_daemon_threads() > 1) 4398 // This wait should make safepoint checks, wait without a timeout, 4399 // and wait as a suspend-equivalent condition. 4400 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4401 } 4402 4403 EventShutdown e; 4404 if (e.should_commit()) { 4405 e.set_reason("No remaining non-daemon Java threads"); 4406 e.commit(); 4407 } 4408 4409 // Hang forever on exit if we are reporting an error. 4410 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4411 os::infinite_sleep(); 4412 } 4413 os::wait_for_keypress_at_exit(); 4414 4415 // run Java level shutdown hooks 4416 thread->invoke_shutdown_hooks(); 4417 4418 before_exit(thread); 4419 4420 thread->exit(true); 4421 4422 // Stop VM thread. 4423 { 4424 // 4945125 The vm thread comes to a safepoint during exit. 4425 // GC vm_operations can get caught at the safepoint, and the 4426 // heap is unparseable if they are caught. Grab the Heap_lock 4427 // to prevent this. The GC vm_operations will not be able to 4428 // queue until after the vm thread is dead. After this point, 4429 // we'll never emerge out of the safepoint before the VM exits. 4430 4431 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4432 4433 VMThread::wait_for_vm_thread_exit(); 4434 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4435 VMThread::destroy(); 4436 } 4437 4438 // Now, all Java threads are gone except daemon threads. Daemon threads 4439 // running Java code or in VM are stopped by the Safepoint. However, 4440 // daemon threads executing native code are still running. But they 4441 // will be stopped at native=>Java/VM barriers. Note that we can't 4442 // simply kill or suspend them, as it is inherently deadlock-prone. 4443 4444 VM_Exit::set_vm_exited(); 4445 4446 // Clean up ideal graph printers after the VMThread has started 4447 // the final safepoint which will block all the Compiler threads. 4448 // Note that this Thread has already logically exited so the 4449 // clean_up() function's use of a JavaThreadIteratorWithHandle 4450 // would be a problem except set_vm_exited() has remembered the 4451 // shutdown thread which is granted a policy exception. 4452 #if defined(COMPILER2) && !defined(PRODUCT) 4453 IdealGraphPrinter::clean_up(); 4454 #endif 4455 4456 notify_vm_shutdown(); 4457 4458 // exit_globals() will delete tty 4459 exit_globals(); 4460 4461 // We are after VM_Exit::set_vm_exited() so we can't call 4462 // thread->smr_delete() or we will block on the Threads_lock. 4463 // Deleting the shutdown thread here is safe because another 4464 // JavaThread cannot have an active ThreadsListHandle for 4465 // this JavaThread. 4466 delete thread; 4467 4468 #if INCLUDE_JVMCI 4469 if (JVMCICounterSize > 0) { 4470 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4471 } 4472 #endif 4473 4474 LogConfiguration::finalize(); 4475 4476 return true; 4477 } 4478 4479 4480 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4481 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4482 return is_supported_jni_version(version); 4483 } 4484 4485 4486 jboolean Threads::is_supported_jni_version(jint version) { 4487 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4488 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4489 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4490 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4491 if (version == JNI_VERSION_9) return JNI_TRUE; 4492 if (version == JNI_VERSION_10) return JNI_TRUE; 4493 return JNI_FALSE; 4494 } 4495 4496 4497 void Threads::add(JavaThread* p, bool force_daemon) { 4498 // The threads lock must be owned at this point 4499 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4500 4501 BarrierSet::barrier_set()->on_thread_attach(p); 4502 4503 // Once a JavaThread is added to the Threads list, smr_delete() has 4504 // to be used to delete it. Otherwise we can just delete it directly. 4505 p->set_on_thread_list(); 4506 4507 _number_of_threads++; 4508 oop threadObj = p->threadObj(); 4509 bool daemon = true; 4510 // Bootstrapping problem: threadObj can be null for initial 4511 // JavaThread (or for threads attached via JNI) 4512 if ((!force_daemon) && !is_daemon((threadObj))) { 4513 _number_of_non_daemon_threads++; 4514 daemon = false; 4515 } 4516 4517 ThreadService::add_thread(p, daemon); 4518 4519 // Maintain fast thread list 4520 ThreadsSMRSupport::add_thread(p); 4521 4522 // Possible GC point. 4523 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4524 } 4525 4526 void Threads::remove(JavaThread* p, bool is_daemon) { 4527 4528 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4529 ObjectSynchronizer::om_flush(p); 4530 4531 // Extra scope needed for Thread_lock, so we can check 4532 // that we do not remove thread without safepoint code notice 4533 { MonitorLocker ml(Threads_lock); 4534 4535 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4536 4537 // Maintain fast thread list 4538 ThreadsSMRSupport::remove_thread(p); 4539 4540 _number_of_threads--; 4541 if (!is_daemon) { 4542 _number_of_non_daemon_threads--; 4543 4544 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4545 // on destroy_vm will wake up. 4546 if (number_of_non_daemon_threads() == 1) { 4547 ml.notify_all(); 4548 } 4549 } 4550 ThreadService::remove_thread(p, is_daemon); 4551 4552 // Make sure that safepoint code disregard this thread. This is needed since 4553 // the thread might mess around with locks after this point. This can cause it 4554 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4555 // of this thread since it is removed from the queue. 4556 p->set_terminated_value(); 4557 } // unlock Threads_lock 4558 4559 // Since Events::log uses a lock, we grab it outside the Threads_lock 4560 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4561 } 4562 4563 // Operations on the Threads list for GC. These are not explicitly locked, 4564 // but the garbage collector must provide a safe context for them to run. 4565 // In particular, these things should never be called when the Threads_lock 4566 // is held by some other thread. (Note: the Safepoint abstraction also 4567 // uses the Threads_lock to guarantee this property. It also makes sure that 4568 // all threads gets blocked when exiting or starting). 4569 4570 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4571 ALL_JAVA_THREADS(p) { 4572 p->oops_do(f, cf); 4573 } 4574 VMThread::vm_thread()->oops_do(f, cf); 4575 } 4576 4577 void Threads::change_thread_claim_token() { 4578 if (++_thread_claim_token == 0) { 4579 // On overflow of the token counter, there is a risk of future 4580 // collisions between a new global token value and a stale token 4581 // for a thread, because not all iterations visit all threads. 4582 // (Though it's pretty much a theoretical concern for non-trivial 4583 // token counter sizes.) To deal with the possibility, reset all 4584 // the thread tokens to zero on global token overflow. 4585 struct ResetClaims : public ThreadClosure { 4586 virtual void do_thread(Thread* t) { 4587 t->claim_threads_do(false, 0); 4588 } 4589 } reset_claims; 4590 Threads::threads_do(&reset_claims); 4591 // On overflow, update the global token to non-zero, to 4592 // avoid the special "never claimed" initial thread value. 4593 _thread_claim_token = 1; 4594 } 4595 } 4596 4597 #ifdef ASSERT 4598 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4599 const uintx token = t->threads_do_token(); 4600 assert(token == expected, 4601 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4602 UINTX_FORMAT, kind, p2i(t), token, expected); 4603 } 4604 4605 void Threads::assert_all_threads_claimed() { 4606 ALL_JAVA_THREADS(p) { 4607 assert_thread_claimed("Thread", p, _thread_claim_token); 4608 } 4609 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4610 } 4611 #endif // ASSERT 4612 4613 class ParallelOopsDoThreadClosure : public ThreadClosure { 4614 private: 4615 OopClosure* _f; 4616 CodeBlobClosure* _cf; 4617 public: 4618 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4619 void do_thread(Thread* t) { 4620 t->oops_do(_f, _cf); 4621 } 4622 }; 4623 4624 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4625 ParallelOopsDoThreadClosure tc(f, cf); 4626 possibly_parallel_threads_do(is_par, &tc); 4627 } 4628 4629 void Threads::nmethods_do(CodeBlobClosure* cf) { 4630 ALL_JAVA_THREADS(p) { 4631 // This is used by the code cache sweeper to mark nmethods that are active 4632 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4633 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4634 if(!p->is_Code_cache_sweeper_thread()) { 4635 p->nmethods_do(cf); 4636 } 4637 } 4638 } 4639 4640 void Threads::metadata_do(MetadataClosure* f) { 4641 ALL_JAVA_THREADS(p) { 4642 p->metadata_do(f); 4643 } 4644 } 4645 4646 class ThreadHandlesClosure : public ThreadClosure { 4647 void (*_f)(Metadata*); 4648 public: 4649 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4650 virtual void do_thread(Thread* thread) { 4651 thread->metadata_handles_do(_f); 4652 } 4653 }; 4654 4655 void Threads::metadata_handles_do(void f(Metadata*)) { 4656 // Only walk the Handles in Thread. 4657 ThreadHandlesClosure handles_closure(f); 4658 threads_do(&handles_closure); 4659 } 4660 4661 // Get count Java threads that are waiting to enter the specified monitor. 4662 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4663 int count, 4664 address monitor) { 4665 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4666 4667 int i = 0; 4668 DO_JAVA_THREADS(t_list, p) { 4669 if (!p->can_call_java()) continue; 4670 4671 address pending = (address)p->current_pending_monitor(); 4672 if (pending == monitor) { // found a match 4673 if (i < count) result->append(p); // save the first count matches 4674 i++; 4675 } 4676 } 4677 4678 return result; 4679 } 4680 4681 4682 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4683 address owner) { 4684 // NULL owner means not locked so we can skip the search 4685 if (owner == NULL) return NULL; 4686 4687 DO_JAVA_THREADS(t_list, p) { 4688 // first, see if owner is the address of a Java thread 4689 if (owner == (address)p) return p; 4690 } 4691 4692 // Cannot assert on lack of success here since this function may be 4693 // used by code that is trying to report useful problem information 4694 // like deadlock detection. 4695 if (UseHeavyMonitors) return NULL; 4696 4697 // If we didn't find a matching Java thread and we didn't force use of 4698 // heavyweight monitors, then the owner is the stack address of the 4699 // Lock Word in the owning Java thread's stack. 4700 // 4701 JavaThread* the_owner = NULL; 4702 DO_JAVA_THREADS(t_list, q) { 4703 if (q->is_lock_owned(owner)) { 4704 the_owner = q; 4705 break; 4706 } 4707 } 4708 4709 // cannot assert on lack of success here; see above comment 4710 return the_owner; 4711 } 4712 4713 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4714 void Threads::print_on(outputStream* st, bool print_stacks, 4715 bool internal_format, bool print_concurrent_locks, 4716 bool print_extended_info) { 4717 char buf[32]; 4718 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4719 4720 st->print_cr("Full thread dump %s (%s %s):", 4721 VM_Version::vm_name(), 4722 VM_Version::vm_release(), 4723 VM_Version::vm_info_string()); 4724 st->cr(); 4725 4726 #if INCLUDE_SERVICES 4727 // Dump concurrent locks 4728 ConcurrentLocksDump concurrent_locks; 4729 if (print_concurrent_locks) { 4730 concurrent_locks.dump_at_safepoint(); 4731 } 4732 #endif // INCLUDE_SERVICES 4733 4734 ThreadsSMRSupport::print_info_on(st); 4735 st->cr(); 4736 4737 ALL_JAVA_THREADS(p) { 4738 ResourceMark rm; 4739 p->print_on(st, print_extended_info); 4740 if (print_stacks) { 4741 if (internal_format) { 4742 p->trace_stack(); 4743 } else { 4744 p->print_stack_on(st); 4745 } 4746 } 4747 st->cr(); 4748 #if INCLUDE_SERVICES 4749 if (print_concurrent_locks) { 4750 concurrent_locks.print_locks_on(p, st); 4751 } 4752 #endif // INCLUDE_SERVICES 4753 } 4754 4755 VMThread::vm_thread()->print_on(st); 4756 st->cr(); 4757 Universe::heap()->print_gc_threads_on(st); 4758 WatcherThread* wt = WatcherThread::watcher_thread(); 4759 if (wt != NULL) { 4760 wt->print_on(st); 4761 st->cr(); 4762 } 4763 4764 st->flush(); 4765 } 4766 4767 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4768 int buflen, bool* found_current) { 4769 if (this_thread != NULL) { 4770 bool is_current = (current == this_thread); 4771 *found_current = *found_current || is_current; 4772 st->print("%s", is_current ? "=>" : " "); 4773 4774 st->print(PTR_FORMAT, p2i(this_thread)); 4775 st->print(" "); 4776 this_thread->print_on_error(st, buf, buflen); 4777 st->cr(); 4778 } 4779 } 4780 4781 class PrintOnErrorClosure : public ThreadClosure { 4782 outputStream* _st; 4783 Thread* _current; 4784 char* _buf; 4785 int _buflen; 4786 bool* _found_current; 4787 public: 4788 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4789 int buflen, bool* found_current) : 4790 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4791 4792 virtual void do_thread(Thread* thread) { 4793 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4794 } 4795 }; 4796 4797 // Threads::print_on_error() is called by fatal error handler. It's possible 4798 // that VM is not at safepoint and/or current thread is inside signal handler. 4799 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4800 // memory (even in resource area), it might deadlock the error handler. 4801 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4802 int buflen) { 4803 ThreadsSMRSupport::print_info_on(st); 4804 st->cr(); 4805 4806 bool found_current = false; 4807 st->print_cr("Java Threads: ( => current thread )"); 4808 ALL_JAVA_THREADS(thread) { 4809 print_on_error(thread, st, current, buf, buflen, &found_current); 4810 } 4811 st->cr(); 4812 4813 st->print_cr("Other Threads:"); 4814 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4815 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4816 4817 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4818 Universe::heap()->gc_threads_do(&print_closure); 4819 4820 if (!found_current) { 4821 st->cr(); 4822 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4823 current->print_on_error(st, buf, buflen); 4824 st->cr(); 4825 } 4826 st->cr(); 4827 4828 st->print_cr("Threads with active compile tasks:"); 4829 print_threads_compiling(st, buf, buflen); 4830 } 4831 4832 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4833 ALL_JAVA_THREADS(thread) { 4834 if (thread->is_Compiler_thread()) { 4835 CompilerThread* ct = (CompilerThread*) thread; 4836 4837 // Keep task in local variable for NULL check. 4838 // ct->_task might be set to NULL by concurring compiler thread 4839 // because it completed the compilation. The task is never freed, 4840 // though, just returned to a free list. 4841 CompileTask* task = ct->task(); 4842 if (task != NULL) { 4843 thread->print_name_on_error(st, buf, buflen); 4844 st->print(" "); 4845 task->print(st, NULL, short_form, true); 4846 } 4847 } 4848 } 4849 } 4850 4851 4852 // Internal SpinLock and Mutex 4853 // Based on ParkEvent 4854 4855 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4856 // 4857 // We employ SpinLocks _only for low-contention, fixed-length 4858 // short-duration critical sections where we're concerned 4859 // about native mutex_t or HotSpot Mutex:: latency. 4860 // The mux construct provides a spin-then-block mutual exclusion 4861 // mechanism. 4862 // 4863 // Testing has shown that contention on the ListLock guarding gFreeList 4864 // is common. If we implement ListLock as a simple SpinLock it's common 4865 // for the JVM to devolve to yielding with little progress. This is true 4866 // despite the fact that the critical sections protected by ListLock are 4867 // extremely short. 4868 // 4869 // TODO-FIXME: ListLock should be of type SpinLock. 4870 // We should make this a 1st-class type, integrated into the lock 4871 // hierarchy as leaf-locks. Critically, the SpinLock structure 4872 // should have sufficient padding to avoid false-sharing and excessive 4873 // cache-coherency traffic. 4874 4875 4876 typedef volatile int SpinLockT; 4877 4878 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4879 if (Atomic::cmpxchg(adr, 0, 1) == 0) { 4880 return; // normal fast-path return 4881 } 4882 4883 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4884 int ctr = 0; 4885 int Yields = 0; 4886 for (;;) { 4887 while (*adr != 0) { 4888 ++ctr; 4889 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4890 if (Yields > 5) { 4891 os::naked_short_sleep(1); 4892 } else { 4893 os::naked_yield(); 4894 ++Yields; 4895 } 4896 } else { 4897 SpinPause(); 4898 } 4899 } 4900 if (Atomic::cmpxchg(adr, 0, 1) == 0) return; 4901 } 4902 } 4903 4904 void Thread::SpinRelease(volatile int * adr) { 4905 assert(*adr != 0, "invariant"); 4906 OrderAccess::fence(); // guarantee at least release consistency. 4907 // Roach-motel semantics. 4908 // It's safe if subsequent LDs and STs float "up" into the critical section, 4909 // but prior LDs and STs within the critical section can't be allowed 4910 // to reorder or float past the ST that releases the lock. 4911 // Loads and stores in the critical section - which appear in program 4912 // order before the store that releases the lock - must also appear 4913 // before the store that releases the lock in memory visibility order. 4914 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4915 // the ST of 0 into the lock-word which releases the lock, so fence 4916 // more than covers this on all platforms. 4917 *adr = 0; 4918 } 4919 4920 // muxAcquire and muxRelease: 4921 // 4922 // * muxAcquire and muxRelease support a single-word lock-word construct. 4923 // The LSB of the word is set IFF the lock is held. 4924 // The remainder of the word points to the head of a singly-linked list 4925 // of threads blocked on the lock. 4926 // 4927 // * The current implementation of muxAcquire-muxRelease uses its own 4928 // dedicated Thread._MuxEvent instance. If we're interested in 4929 // minimizing the peak number of extant ParkEvent instances then 4930 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4931 // as certain invariants were satisfied. Specifically, care would need 4932 // to be taken with regards to consuming unpark() "permits". 4933 // A safe rule of thumb is that a thread would never call muxAcquire() 4934 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4935 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4936 // consume an unpark() permit intended for monitorenter, for instance. 4937 // One way around this would be to widen the restricted-range semaphore 4938 // implemented in park(). Another alternative would be to provide 4939 // multiple instances of the PlatformEvent() for each thread. One 4940 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4941 // 4942 // * Usage: 4943 // -- Only as leaf locks 4944 // -- for short-term locking only as muxAcquire does not perform 4945 // thread state transitions. 4946 // 4947 // Alternatives: 4948 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4949 // but with parking or spin-then-park instead of pure spinning. 4950 // * Use Taura-Oyama-Yonenzawa locks. 4951 // * It's possible to construct a 1-0 lock if we encode the lockword as 4952 // (List,LockByte). Acquire will CAS the full lockword while Release 4953 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4954 // acquiring threads use timers (ParkTimed) to detect and recover from 4955 // the stranding window. Thread/Node structures must be aligned on 256-byte 4956 // boundaries by using placement-new. 4957 // * Augment MCS with advisory back-link fields maintained with CAS(). 4958 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4959 // The validity of the backlinks must be ratified before we trust the value. 4960 // If the backlinks are invalid the exiting thread must back-track through the 4961 // the forward links, which are always trustworthy. 4962 // * Add a successor indication. The LockWord is currently encoded as 4963 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4964 // to provide the usual futile-wakeup optimization. 4965 // See RTStt for details. 4966 // 4967 4968 4969 const intptr_t LOCKBIT = 1; 4970 4971 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4972 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT); 4973 if (w == 0) return; 4974 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4975 return; 4976 } 4977 4978 ParkEvent * const Self = Thread::current()->_MuxEvent; 4979 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4980 for (;;) { 4981 int its = (os::is_MP() ? 100 : 0) + 1; 4982 4983 // Optional spin phase: spin-then-park strategy 4984 while (--its >= 0) { 4985 w = *Lock; 4986 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4987 return; 4988 } 4989 } 4990 4991 Self->reset(); 4992 Self->OnList = intptr_t(Lock); 4993 // The following fence() isn't _strictly necessary as the subsequent 4994 // CAS() both serializes execution and ratifies the fetched *Lock value. 4995 OrderAccess::fence(); 4996 for (;;) { 4997 w = *Lock; 4998 if ((w & LOCKBIT) == 0) { 4999 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5000 Self->OnList = 0; // hygiene - allows stronger asserts 5001 return; 5002 } 5003 continue; // Interference -- *Lock changed -- Just retry 5004 } 5005 assert(w & LOCKBIT, "invariant"); 5006 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5007 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break; 5008 } 5009 5010 while (Self->OnList != 0) { 5011 Self->park(); 5012 } 5013 } 5014 } 5015 5016 // Release() must extract a successor from the list and then wake that thread. 5017 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5018 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5019 // Release() would : 5020 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5021 // (B) Extract a successor from the private list "in-hand" 5022 // (C) attempt to CAS() the residual back into *Lock over null. 5023 // If there were any newly arrived threads and the CAS() would fail. 5024 // In that case Release() would detach the RATs, re-merge the list in-hand 5025 // with the RATs and repeat as needed. Alternately, Release() might 5026 // detach and extract a successor, but then pass the residual list to the wakee. 5027 // The wakee would be responsible for reattaching and remerging before it 5028 // competed for the lock. 5029 // 5030 // Both "pop" and DMR are immune from ABA corruption -- there can be 5031 // multiple concurrent pushers, but only one popper or detacher. 5032 // This implementation pops from the head of the list. This is unfair, 5033 // but tends to provide excellent throughput as hot threads remain hot. 5034 // (We wake recently run threads first). 5035 // 5036 // All paths through muxRelease() will execute a CAS. 5037 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5038 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5039 // executed within the critical section are complete and globally visible before the 5040 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5041 void Thread::muxRelease(volatile intptr_t * Lock) { 5042 for (;;) { 5043 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0); 5044 assert(w & LOCKBIT, "invariant"); 5045 if (w == LOCKBIT) return; 5046 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5047 assert(List != NULL, "invariant"); 5048 assert(List->OnList == intptr_t(Lock), "invariant"); 5049 ParkEvent * const nxt = List->ListNext; 5050 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5051 5052 // The following CAS() releases the lock and pops the head element. 5053 // The CAS() also ratifies the previously fetched lock-word value. 5054 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) { 5055 continue; 5056 } 5057 List->OnList = 0; 5058 OrderAccess::fence(); 5059 List->unpark(); 5060 return; 5061 } 5062 } 5063 5064 5065 void Threads::verify() { 5066 ALL_JAVA_THREADS(p) { 5067 p->verify(); 5068 } 5069 VMThread* thread = VMThread::vm_thread(); 5070 if (thread != NULL) thread->verify(); 5071 } --- EOF ---