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/iterator.hpp" 51 #include "memory/metaspaceShared.hpp" 52 #include "memory/oopFactory.hpp" 53 #include "memory/resourceArea.hpp" 54 #include "memory/universe.hpp" 55 #include "oops/access.inline.hpp" 56 #include "oops/instanceKlass.hpp" 57 #include "oops/objArrayOop.hpp" 58 #include "oops/oop.inline.hpp" 59 #include "oops/symbol.hpp" 60 #include "oops/typeArrayOop.inline.hpp" 61 #include "oops/verifyOopClosure.hpp" 62 #include "prims/jvm_misc.hpp" 63 #include "prims/jvmtiExport.hpp" 64 #include "prims/jvmtiThreadState.hpp" 65 #include "runtime/arguments.hpp" 66 #include "runtime/atomic.hpp" 67 #include "runtime/biasedLocking.hpp" 68 #include "runtime/fieldDescriptor.inline.hpp" 69 #include "runtime/flags/jvmFlagConstraintList.hpp" 70 #include "runtime/flags/jvmFlagRangeList.hpp" 71 #include "runtime/flags/jvmFlagWriteableList.hpp" 72 #include "runtime/deoptimization.hpp" 73 #include "runtime/frame.inline.hpp" 74 #include "runtime/handles.inline.hpp" 75 #include "runtime/handshake.hpp" 76 #include "runtime/init.hpp" 77 #include "runtime/interfaceSupport.inline.hpp" 78 #include "runtime/java.hpp" 79 #include "runtime/javaCalls.hpp" 80 #include "runtime/jniHandles.inline.hpp" 81 #include "runtime/jniPeriodicChecker.hpp" 82 #include "runtime/memprofiler.hpp" 83 #include "runtime/mutexLocker.hpp" 84 #include "runtime/objectMonitor.hpp" 85 #include "runtime/orderAccess.hpp" 86 #include "runtime/osThread.hpp" 87 #include "runtime/prefetch.inline.hpp" 88 #include "runtime/safepoint.hpp" 89 #include "runtime/safepointMechanism.inline.hpp" 90 #include "runtime/safepointVerifiers.hpp" 91 #include "runtime/sharedRuntime.hpp" 92 #include "runtime/statSampler.hpp" 93 #include "runtime/stubRoutines.hpp" 94 #include "runtime/sweeper.hpp" 95 #include "runtime/task.hpp" 96 #include "runtime/thread.inline.hpp" 97 #include "runtime/threadCritical.hpp" 98 #include "runtime/threadSMR.inline.hpp" 99 #include "runtime/threadStatisticalInfo.hpp" 100 #include "runtime/timer.hpp" 101 #include "runtime/timerTrace.hpp" 102 #include "runtime/vframe.inline.hpp" 103 #include "runtime/vframeArray.hpp" 104 #include "runtime/vframe_hp.hpp" 105 #include "runtime/vmThread.hpp" 106 #include "runtime/vmOperations.hpp" 107 #include "runtime/vm_version.hpp" 108 #include "services/attachListener.hpp" 109 #include "services/management.hpp" 110 #include "services/memTracker.hpp" 111 #include "services/threadService.hpp" 112 #include "utilities/align.hpp" 113 #include "utilities/copy.hpp" 114 #include "utilities/defaultStream.hpp" 115 #include "utilities/dtrace.hpp" 116 #include "utilities/events.hpp" 117 #include "utilities/macros.hpp" 118 #include "utilities/preserveException.hpp" 119 #include "utilities/singleWriterSynchronizer.hpp" 120 #include "utilities/vmError.hpp" 121 #if INCLUDE_JVMCI 122 #include "jvmci/jvmci.hpp" 123 #include "jvmci/jvmciEnv.hpp" 124 #endif 125 #ifdef COMPILER1 126 #include "c1/c1_Compiler.hpp" 127 #endif 128 #ifdef COMPILER2 129 #include "opto/c2compiler.hpp" 130 #include "opto/idealGraphPrinter.hpp" 131 #endif 132 #if INCLUDE_RTM_OPT 133 #include "runtime/rtmLocking.hpp" 134 #endif 135 #if INCLUDE_JFR 136 #include "jfr/jfr.hpp" 137 #endif 138 139 // Initialization after module runtime initialization 140 void universe_post_module_init(); // must happen after call_initPhase2 141 142 #ifdef DTRACE_ENABLED 143 144 // Only bother with this argument setup if dtrace is available 145 146 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 147 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 148 149 #define DTRACE_THREAD_PROBE(probe, javathread) \ 150 { \ 151 ResourceMark rm(this); \ 152 int len = 0; \ 153 const char* name = (javathread)->get_thread_name(); \ 154 len = strlen(name); \ 155 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 156 (char *) name, len, \ 157 java_lang_Thread::thread_id((javathread)->threadObj()), \ 158 (uintptr_t) (javathread)->osthread()->thread_id(), \ 159 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 160 } 161 162 #else // ndef DTRACE_ENABLED 163 164 #define DTRACE_THREAD_PROBE(probe, javathread) 165 166 #endif // ndef DTRACE_ENABLED 167 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY 169 // Current thread is maintained as a thread-local variable 170 THREAD_LOCAL Thread* Thread::_thr_current = NULL; 171 #endif 172 173 // ======= Thread ======== 174 // Support for forcing alignment of thread objects for biased locking 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 176 if (UseBiasedLocking) { 177 const size_t alignment = markWord::biased_lock_alignment; 178 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 180 : AllocateHeap(aligned_size, flags, CURRENT_PC, 181 AllocFailStrategy::RETURN_NULL); 182 void* aligned_addr = align_up(real_malloc_addr, alignment); 183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 185 "JavaThread alignment code overflowed allocated storage"); 186 if (aligned_addr != real_malloc_addr) { 187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 188 p2i(real_malloc_addr), 189 p2i(aligned_addr)); 190 } 191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 192 return aligned_addr; 193 } else { 194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 196 } 197 } 198 199 void Thread::operator delete(void* p) { 200 if (UseBiasedLocking) { 201 FreeHeap(((Thread*) p)->_real_malloc_address); 202 } else { 203 FreeHeap(p); 204 } 205 } 206 207 void JavaThread::smr_delete() { 208 if (_on_thread_list) { 209 ThreadsSMRSupport::smr_delete(this); 210 } else { 211 delete this; 212 } 213 } 214 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 216 // JavaThread 217 218 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;) 219 220 Thread::Thread() { 221 222 DEBUG_ONLY(_run_state = PRE_CALL_RUN;) 223 224 // stack and get_thread 225 set_stack_base(NULL); 226 set_stack_size(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 240 241 // Initial value of zero ==> never claimed. 242 _threads_do_token = 0; 243 _threads_hazard_ptr = NULL; 244 _threads_list_ptr = NULL; 245 _nested_threads_hazard_ptr_cnt = 0; 246 _rcu_counter = 0; 247 248 // the handle mark links itself to last_handle_mark 249 new HandleMark(this); 250 251 // plain initialization 252 debug_only(_owned_locks = NULL;) 253 NOT_PRODUCT(_no_safepoint_count = 0;) 254 NOT_PRODUCT(_skip_gcalot = false;) 255 _jvmti_env_iteration_count = 0; 256 set_allocated_bytes(0); 257 _vm_operation_started_count = 0; 258 _vm_operation_completed_count = 0; 259 _current_pending_monitor = NULL; 260 _current_pending_monitor_is_from_java = true; 261 _current_waiting_monitor = NULL; 262 _current_pending_raw_monitor = NULL; 263 _num_nested_signal = 0; 264 om_free_list = NULL; 265 om_free_count = 0; 266 om_free_provision = 32; 267 om_in_use_list = NULL; 268 om_in_use_count = 0; 269 270 #ifdef ASSERT 271 _visited_for_critical_count = false; 272 #endif 273 274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 275 Monitor::_safepoint_check_sometimes); 276 _suspend_flags = 0; 277 278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 279 _hashStateX = os::random(); 280 _hashStateY = 842502087; 281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 282 _hashStateW = 273326509; 283 284 _OnTrap = 0; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _MuxEvent = ParkEvent::Allocate(this); 297 298 #ifdef CHECK_UNHANDLED_OOPS 299 if (CheckUnhandledOops) { 300 _unhandled_oops = new UnhandledOops(this); 301 } 302 #endif // CHECK_UNHANDLED_OOPS 303 #ifdef ASSERT 304 if (UseBiasedLocking) { 305 assert(is_aligned(this, markWord::biased_lock_alignment), "forced alignment of thread object failed"); 306 assert(this == _real_malloc_address || 307 this == align_up(_real_malloc_address, markWord::biased_lock_alignment), 308 "bug in forced alignment of thread objects"); 309 } 310 #endif // ASSERT 311 312 // Notify the barrier set that a thread is being created. The initial 313 // thread is created before the barrier set is available. The call to 314 // BarrierSet::on_thread_create() for this thread is therefore deferred 315 // to BarrierSet::set_barrier_set(). 316 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 317 if (barrier_set != NULL) { 318 barrier_set->on_thread_create(this); 319 } else { 320 // Only the main thread should be created before the barrier set 321 // and that happens just before Thread::current is set. No other thread 322 // can attach as the VM is not created yet, so they can't execute this code. 323 // If the main thread creates other threads before the barrier set that is an error. 324 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 325 } 326 } 327 328 void Thread::initialize_thread_current() { 329 #ifndef USE_LIBRARY_BASED_TLS_ONLY 330 assert(_thr_current == NULL, "Thread::current already initialized"); 331 _thr_current = this; 332 #endif 333 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 334 ThreadLocalStorage::set_thread(this); 335 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 336 } 337 338 void Thread::clear_thread_current() { 339 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 340 #ifndef USE_LIBRARY_BASED_TLS_ONLY 341 _thr_current = NULL; 342 #endif 343 ThreadLocalStorage::set_thread(NULL); 344 } 345 346 void Thread::record_stack_base_and_size() { 347 // Note: at this point, Thread object is not yet initialized. Do not rely on 348 // any members being initialized. Do not rely on Thread::current() being set. 349 // If possible, refrain from doing anything which may crash or assert since 350 // quite probably those crash dumps will be useless. 351 set_stack_base(os::current_stack_base()); 352 set_stack_size(os::current_stack_size()); 353 354 #ifdef SOLARIS 355 if (os::is_primordial_thread()) { 356 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 357 } 358 #endif 359 360 // Set stack limits after thread is initialized. 361 if (is_Java_thread()) { 362 ((JavaThread*) this)->set_stack_overflow_limit(); 363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 364 } 365 } 366 367 #if INCLUDE_NMT 368 void Thread::register_thread_stack_with_NMT() { 369 MemTracker::record_thread_stack(stack_end(), stack_size()); 370 } 371 #endif // INCLUDE_NMT 372 373 void Thread::call_run() { 374 DEBUG_ONLY(_run_state = CALL_RUN;) 375 376 // At this point, Thread object should be fully initialized and 377 // Thread::current() should be set. 378 379 assert(Thread::current_or_null() != NULL, "current thread is unset"); 380 assert(Thread::current_or_null() == this, "current thread is wrong"); 381 382 // Perform common initialization actions 383 384 register_thread_stack_with_NMT(); 385 386 JFR_ONLY(Jfr::on_thread_start(this);) 387 388 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 389 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 390 os::current_thread_id(), p2i(stack_base() - stack_size()), 391 p2i(stack_base()), stack_size()/1024); 392 393 // Perform <ChildClass> initialization actions 394 DEBUG_ONLY(_run_state = PRE_RUN;) 395 this->pre_run(); 396 397 // Invoke <ChildClass>::run() 398 DEBUG_ONLY(_run_state = RUN;) 399 this->run(); 400 // Returned from <ChildClass>::run(). Thread finished. 401 402 // Perform common tear-down actions 403 404 assert(Thread::current_or_null() != NULL, "current thread is unset"); 405 assert(Thread::current_or_null() == this, "current thread is wrong"); 406 407 // Perform <ChildClass> tear-down actions 408 DEBUG_ONLY(_run_state = POST_RUN;) 409 this->post_run(); 410 411 // Note: at this point the thread object may already have deleted itself, 412 // so from here on do not dereference *this*. Not all thread types currently 413 // delete themselves when they terminate. But no thread should ever be deleted 414 // asynchronously with respect to its termination - that is what _run_state can 415 // be used to check. 416 417 assert(Thread::current_or_null() == NULL, "current thread still present"); 418 } 419 420 Thread::~Thread() { 421 422 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 423 // get started due to errors etc. Any active thread should at least reach post_run 424 // before it is deleted (usually in post_run()). 425 assert(_run_state == PRE_CALL_RUN || 426 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 427 "_run_state=%d", (int)_run_state); 428 429 // Notify the barrier set that a thread is being destroyed. Note that a barrier 430 // set might not be available if we encountered errors during bootstrapping. 431 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 432 if (barrier_set != NULL) { 433 barrier_set->on_thread_destroy(this); 434 } 435 436 // stack_base can be NULL if the thread is never started or exited before 437 // record_stack_base_and_size called. Although, we would like to ensure 438 // that all started threads do call record_stack_base_and_size(), there is 439 // not proper way to enforce that. 440 #if INCLUDE_NMT 441 if (_stack_base != NULL) { 442 MemTracker::release_thread_stack(stack_end(), stack_size()); 443 #ifdef ASSERT 444 set_stack_base(NULL); 445 #endif 446 } 447 #endif // INCLUDE_NMT 448 449 // deallocate data structures 450 delete resource_area(); 451 // since the handle marks are using the handle area, we have to deallocated the root 452 // handle mark before deallocating the thread's handle area, 453 assert(last_handle_mark() != NULL, "check we have an element"); 454 delete last_handle_mark(); 455 assert(last_handle_mark() == NULL, "check we have reached the end"); 456 457 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 458 // We NULL out the fields for good hygiene. 459 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 460 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 461 462 delete handle_area(); 463 delete metadata_handles(); 464 465 // SR_handler uses this as a termination indicator - 466 // needs to happen before os::free_thread() 467 delete _SR_lock; 468 _SR_lock = NULL; 469 470 // osthread() can be NULL, if creation of thread failed. 471 if (osthread() != NULL) os::free_thread(osthread()); 472 473 // Clear Thread::current if thread is deleting itself and it has not 474 // already been done. This must be done before the memory is deallocated. 475 // Needed to ensure JNI correctly detects non-attached threads. 476 if (this == Thread::current_or_null()) { 477 Thread::clear_thread_current(); 478 } 479 480 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 481 } 482 483 #ifdef ASSERT 484 // A JavaThread is considered "dangling" if it is not the current 485 // thread, has been added the Threads list, the system is not at a 486 // safepoint and the Thread is not "protected". 487 // 488 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 489 assert(!thread->is_Java_thread() || Thread::current() == thread || 490 !((JavaThread *) thread)->on_thread_list() || 491 SafepointSynchronize::is_at_safepoint() || 492 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 493 "possibility of dangling Thread pointer"); 494 } 495 #endif 496 497 ThreadPriority Thread::get_priority(const Thread* const thread) { 498 ThreadPriority priority; 499 // Can return an error! 500 (void)os::get_priority(thread, priority); 501 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 502 return priority; 503 } 504 505 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 506 debug_only(check_for_dangling_thread_pointer(thread);) 507 // Can return an error! 508 (void)os::set_priority(thread, priority); 509 } 510 511 512 void Thread::start(Thread* thread) { 513 // Start is different from resume in that its safety is guaranteed by context or 514 // being called from a Java method synchronized on the Thread object. 515 if (!DisableStartThread) { 516 if (thread->is_Java_thread()) { 517 // Initialize the thread state to RUNNABLE before starting this thread. 518 // Can not set it after the thread started because we do not know the 519 // exact thread state at that time. It could be in MONITOR_WAIT or 520 // in SLEEPING or some other state. 521 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 522 java_lang_Thread::RUNNABLE); 523 } 524 os::start_thread(thread); 525 } 526 } 527 528 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 529 VM_ThreadStop vm_stop(java_thread, java_throwable); 530 VMThread::execute(&vm_stop); 531 } 532 533 534 // Check if an external suspend request has completed (or has been 535 // cancelled). Returns true if the thread is externally suspended and 536 // false otherwise. 537 // 538 // The bits parameter returns information about the code path through 539 // the routine. Useful for debugging: 540 // 541 // set in is_ext_suspend_completed(): 542 // 0x00000001 - routine was entered 543 // 0x00000010 - routine return false at end 544 // 0x00000100 - thread exited (return false) 545 // 0x00000200 - suspend request cancelled (return false) 546 // 0x00000400 - thread suspended (return true) 547 // 0x00001000 - thread is in a suspend equivalent state (return true) 548 // 0x00002000 - thread is native and walkable (return true) 549 // 0x00004000 - thread is native_trans and walkable (needed retry) 550 // 551 // set in wait_for_ext_suspend_completion(): 552 // 0x00010000 - routine was entered 553 // 0x00020000 - suspend request cancelled before loop (return false) 554 // 0x00040000 - thread suspended before loop (return true) 555 // 0x00080000 - suspend request cancelled in loop (return false) 556 // 0x00100000 - thread suspended in loop (return true) 557 // 0x00200000 - suspend not completed during retry loop (return false) 558 559 // Helper class for tracing suspend wait debug bits. 560 // 561 // 0x00000100 indicates that the target thread exited before it could 562 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 563 // 0x00080000 each indicate a cancelled suspend request so they don't 564 // count as wait failures either. 565 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 566 567 class TraceSuspendDebugBits : public StackObj { 568 private: 569 JavaThread * jt; 570 bool is_wait; 571 bool called_by_wait; // meaningful when !is_wait 572 uint32_t * bits; 573 574 public: 575 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 576 uint32_t *_bits) { 577 jt = _jt; 578 is_wait = _is_wait; 579 called_by_wait = _called_by_wait; 580 bits = _bits; 581 } 582 583 ~TraceSuspendDebugBits() { 584 if (!is_wait) { 585 #if 1 586 // By default, don't trace bits for is_ext_suspend_completed() calls. 587 // That trace is very chatty. 588 return; 589 #else 590 if (!called_by_wait) { 591 // If tracing for is_ext_suspend_completed() is enabled, then only 592 // trace calls to it from wait_for_ext_suspend_completion() 593 return; 594 } 595 #endif 596 } 597 598 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 599 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 600 MutexLocker ml(Threads_lock); // needed for get_thread_name() 601 ResourceMark rm; 602 603 tty->print_cr( 604 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 605 jt->get_thread_name(), *bits); 606 607 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 608 } 609 } 610 } 611 }; 612 #undef DEBUG_FALSE_BITS 613 614 615 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 616 uint32_t *bits) { 617 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 618 619 bool did_trans_retry = false; // only do thread_in_native_trans retry once 620 bool do_trans_retry; // flag to force the retry 621 622 *bits |= 0x00000001; 623 624 do { 625 do_trans_retry = false; 626 627 if (is_exiting()) { 628 // Thread is in the process of exiting. This is always checked 629 // first to reduce the risk of dereferencing a freed JavaThread. 630 *bits |= 0x00000100; 631 return false; 632 } 633 634 if (!is_external_suspend()) { 635 // Suspend request is cancelled. This is always checked before 636 // is_ext_suspended() to reduce the risk of a rogue resume 637 // confusing the thread that made the suspend request. 638 *bits |= 0x00000200; 639 return false; 640 } 641 642 if (is_ext_suspended()) { 643 // thread is suspended 644 *bits |= 0x00000400; 645 return true; 646 } 647 648 // Now that we no longer do hard suspends of threads running 649 // native code, the target thread can be changing thread state 650 // while we are in this routine: 651 // 652 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 653 // 654 // We save a copy of the thread state as observed at this moment 655 // and make our decision about suspend completeness based on the 656 // copy. This closes the race where the thread state is seen as 657 // _thread_in_native_trans in the if-thread_blocked check, but is 658 // seen as _thread_blocked in if-thread_in_native_trans check. 659 JavaThreadState save_state = thread_state(); 660 661 if (save_state == _thread_blocked && is_suspend_equivalent()) { 662 // If the thread's state is _thread_blocked and this blocking 663 // condition is known to be equivalent to a suspend, then we can 664 // consider the thread to be externally suspended. This means that 665 // the code that sets _thread_blocked has been modified to do 666 // self-suspension if the blocking condition releases. We also 667 // used to check for CONDVAR_WAIT here, but that is now covered by 668 // the _thread_blocked with self-suspension check. 669 // 670 // Return true since we wouldn't be here unless there was still an 671 // external suspend request. 672 *bits |= 0x00001000; 673 return true; 674 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 675 // Threads running native code will self-suspend on native==>VM/Java 676 // transitions. If its stack is walkable (should always be the case 677 // unless this function is called before the actual java_suspend() 678 // call), then the wait is done. 679 *bits |= 0x00002000; 680 return true; 681 } else if (!called_by_wait && !did_trans_retry && 682 save_state == _thread_in_native_trans && 683 frame_anchor()->walkable()) { 684 // The thread is transitioning from thread_in_native to another 685 // thread state. check_safepoint_and_suspend_for_native_trans() 686 // will force the thread to self-suspend. If it hasn't gotten 687 // there yet we may have caught the thread in-between the native 688 // code check above and the self-suspend. Lucky us. If we were 689 // called by wait_for_ext_suspend_completion(), then it 690 // will be doing the retries so we don't have to. 691 // 692 // Since we use the saved thread state in the if-statement above, 693 // there is a chance that the thread has already transitioned to 694 // _thread_blocked by the time we get here. In that case, we will 695 // make a single unnecessary pass through the logic below. This 696 // doesn't hurt anything since we still do the trans retry. 697 698 *bits |= 0x00004000; 699 700 // Once the thread leaves thread_in_native_trans for another 701 // thread state, we break out of this retry loop. We shouldn't 702 // need this flag to prevent us from getting back here, but 703 // sometimes paranoia is good. 704 did_trans_retry = true; 705 706 // We wait for the thread to transition to a more usable state. 707 for (int i = 1; i <= SuspendRetryCount; i++) { 708 // We used to do an "os::yield_all(i)" call here with the intention 709 // that yielding would increase on each retry. However, the parameter 710 // is ignored on Linux which means the yield didn't scale up. Waiting 711 // on the SR_lock below provides a much more predictable scale up for 712 // the delay. It also provides a simple/direct point to check for any 713 // safepoint requests from the VMThread 714 715 // temporarily drops SR_lock while doing wait with safepoint check 716 // (if we're a JavaThread - the WatcherThread can also call this) 717 // and increase delay with each retry 718 if (Thread::current()->is_Java_thread()) { 719 SR_lock()->wait(i * delay); 720 } else { 721 SR_lock()->wait_without_safepoint_check(i * delay); 722 } 723 724 // check the actual thread state instead of what we saved above 725 if (thread_state() != _thread_in_native_trans) { 726 // the thread has transitioned to another thread state so 727 // try all the checks (except this one) one more time. 728 do_trans_retry = true; 729 break; 730 } 731 } // end retry loop 732 733 734 } 735 } while (do_trans_retry); 736 737 *bits |= 0x00000010; 738 return false; 739 } 740 741 // Wait for an external suspend request to complete (or be cancelled). 742 // Returns true if the thread is externally suspended and false otherwise. 743 // 744 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 745 uint32_t *bits) { 746 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 747 false /* !called_by_wait */, bits); 748 749 // local flag copies to minimize SR_lock hold time 750 bool is_suspended; 751 bool pending; 752 uint32_t reset_bits; 753 754 // set a marker so is_ext_suspend_completed() knows we are the caller 755 *bits |= 0x00010000; 756 757 // We use reset_bits to reinitialize the bits value at the top of 758 // each retry loop. This allows the caller to make use of any 759 // unused bits for their own marking purposes. 760 reset_bits = *bits; 761 762 { 763 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 764 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 765 delay, bits); 766 pending = is_external_suspend(); 767 } 768 // must release SR_lock to allow suspension to complete 769 770 if (!pending) { 771 // A cancelled suspend request is the only false return from 772 // is_ext_suspend_completed() that keeps us from entering the 773 // retry loop. 774 *bits |= 0x00020000; 775 return false; 776 } 777 778 if (is_suspended) { 779 *bits |= 0x00040000; 780 return true; 781 } 782 783 for (int i = 1; i <= retries; i++) { 784 *bits = reset_bits; // reinit to only track last retry 785 786 // We used to do an "os::yield_all(i)" call here with the intention 787 // that yielding would increase on each retry. However, the parameter 788 // is ignored on Linux which means the yield didn't scale up. Waiting 789 // on the SR_lock below provides a much more predictable scale up for 790 // the delay. It also provides a simple/direct point to check for any 791 // safepoint requests from the VMThread 792 793 { 794 Thread* t = Thread::current(); 795 MonitorLocker ml(SR_lock(), 796 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 797 // wait with safepoint check (if we're a JavaThread - the WatcherThread 798 // can also call this) and increase delay with each retry 799 ml.wait(i * delay); 800 801 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 802 delay, bits); 803 804 // It is possible for the external suspend request to be cancelled 805 // (by a resume) before the actual suspend operation is completed. 806 // Refresh our local copy to see if we still need to wait. 807 pending = is_external_suspend(); 808 } 809 810 if (!pending) { 811 // A cancelled suspend request is the only false return from 812 // is_ext_suspend_completed() that keeps us from staying in the 813 // retry loop. 814 *bits |= 0x00080000; 815 return false; 816 } 817 818 if (is_suspended) { 819 *bits |= 0x00100000; 820 return true; 821 } 822 } // end retry loop 823 824 // thread did not suspend after all our retries 825 *bits |= 0x00200000; 826 return false; 827 } 828 829 // Called from API entry points which perform stack walking. If the 830 // associated JavaThread is the current thread, then wait_for_suspend 831 // is not used. Otherwise, it determines if we should wait for the 832 // "other" thread to complete external suspension. (NOTE: in future 833 // releases the suspension mechanism should be reimplemented so this 834 // is not necessary.) 835 // 836 bool 837 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 838 if (this != JavaThread::current()) { 839 // "other" threads require special handling. 840 if (wait_for_suspend) { 841 // We are allowed to wait for the external suspend to complete 842 // so give the other thread a chance to get suspended. 843 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 844 SuspendRetryDelay, bits)) { 845 // Didn't make it so let the caller know. 846 return false; 847 } 848 } 849 // We aren't allowed to wait for the external suspend to complete 850 // so if the other thread isn't externally suspended we need to 851 // let the caller know. 852 else if (!is_ext_suspend_completed_with_lock(bits)) { 853 return false; 854 } 855 } 856 857 return true; 858 } 859 860 // GC Support 861 bool Thread::claim_par_threads_do(uintx claim_token) { 862 uintx token = _threads_do_token; 863 if (token != claim_token) { 864 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token); 865 if (res == token) { 866 return true; 867 } 868 guarantee(res == claim_token, "invariant"); 869 } 870 return false; 871 } 872 873 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 874 active_handles()->oops_do(f); 875 // Do oop for ThreadShadow 876 f->do_oop((oop*)&_pending_exception); 877 handle_area()->oops_do(f); 878 879 // We scan thread local monitor lists here, and the remaining global 880 // monitors in ObjectSynchronizer::oops_do(). 881 ObjectSynchronizer::thread_local_used_oops_do(this, f); 882 } 883 884 void Thread::metadata_handles_do(void f(Metadata*)) { 885 // Only walk the Handles in Thread. 886 if (metadata_handles() != NULL) { 887 for (int i = 0; i< metadata_handles()->length(); i++) { 888 f(metadata_handles()->at(i)); 889 } 890 } 891 } 892 893 void Thread::print_on(outputStream* st, bool print_extended_info) const { 894 // get_priority assumes osthread initialized 895 if (osthread() != NULL) { 896 int os_prio; 897 if (os::get_native_priority(this, &os_prio) == OS_OK) { 898 st->print("os_prio=%d ", os_prio); 899 } 900 901 st->print("cpu=%.2fms ", 902 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 903 ); 904 st->print("elapsed=%.2fs ", 905 _statistical_info.getElapsedTime() / 1000.0 906 ); 907 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 908 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 909 st->print("allocated=" SIZE_FORMAT "%s ", 910 byte_size_in_proper_unit(allocated_bytes), 911 proper_unit_for_byte_size(allocated_bytes) 912 ); 913 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 914 } 915 916 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 917 osthread()->print_on(st); 918 } 919 ThreadsSMRSupport::print_info_on(this, st); 920 st->print(" "); 921 debug_only(if (WizardMode) print_owned_locks_on(st);) 922 } 923 924 void Thread::print() const { print_on(tty); } 925 926 // Thread::print_on_error() is called by fatal error handler. Don't use 927 // any lock or allocate memory. 928 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 929 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 930 931 if (is_VM_thread()) { st->print("VMThread"); } 932 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 933 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 934 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 935 else { st->print("Thread"); } 936 937 if (is_Named_thread()) { 938 st->print(" \"%s\"", name()); 939 } 940 941 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 942 p2i(stack_end()), p2i(stack_base())); 943 944 if (osthread()) { 945 st->print(" [id=%d]", osthread()->thread_id()); 946 } 947 948 ThreadsSMRSupport::print_info_on(this, st); 949 } 950 951 void Thread::print_value_on(outputStream* st) const { 952 if (is_Named_thread()) { 953 st->print(" \"%s\" ", name()); 954 } 955 st->print(INTPTR_FORMAT, p2i(this)); // print address 956 } 957 958 #ifdef ASSERT 959 void Thread::print_owned_locks_on(outputStream* st) const { 960 Mutex* cur = _owned_locks; 961 if (cur == NULL) { 962 st->print(" (no locks) "); 963 } else { 964 st->print_cr(" Locks owned:"); 965 while (cur) { 966 cur->print_on(st); 967 cur = cur->next(); 968 } 969 } 970 } 971 972 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 973 void Thread::check_possible_safepoint() { 974 if (!is_Java_thread()) return; 975 976 if (_no_safepoint_count > 0) { 977 print_owned_locks(); 978 fatal("Possible safepoint reached by thread that does not allow it"); 979 } 980 #ifdef CHECK_UNHANDLED_OOPS 981 // Clear unhandled oops in JavaThreads so we get a crash right away. 982 clear_unhandled_oops(); 983 #endif // CHECK_UNHANDLED_OOPS 984 } 985 986 void Thread::check_for_valid_safepoint_state() { 987 if (!is_Java_thread()) return; 988 989 // Check NoSafepointVerifier, which is implied by locks taken that can be 990 // shared with the VM thread. This makes sure that no locks with allow_vm_block 991 // are held. 992 check_possible_safepoint(); 993 994 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 995 fatal("LEAF method calling lock?"); 996 } 997 998 if (GCALotAtAllSafepoints) { 999 // We could enter a safepoint here and thus have a gc 1000 InterfaceSupport::check_gc_alot(); 1001 } 1002 } 1003 #endif // ASSERT 1004 1005 bool Thread::is_in_stack(address adr) const { 1006 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1007 address end = os::current_stack_pointer(); 1008 // Allow non Java threads to call this without stack_base 1009 if (_stack_base == NULL) return true; 1010 if (stack_base() > adr && adr >= end) return true; 1011 1012 return false; 1013 } 1014 1015 bool Thread::is_in_usable_stack(address adr) const { 1016 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1017 size_t usable_stack_size = _stack_size - stack_guard_size; 1018 1019 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1020 } 1021 1022 1023 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1024 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1025 // used for compilation in the future. If that change is made, the need for these methods 1026 // should be revisited, and they should be removed if possible. 1027 1028 bool Thread::is_lock_owned(address adr) const { 1029 return on_local_stack(adr); 1030 } 1031 1032 bool Thread::set_as_starting_thread() { 1033 assert(_starting_thread == NULL, "already initialized: " 1034 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1035 // NOTE: this must be called inside the main thread. 1036 DEBUG_ONLY(_starting_thread = this;) 1037 return os::create_main_thread((JavaThread*)this); 1038 } 1039 1040 static void initialize_class(Symbol* class_name, TRAPS) { 1041 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1042 InstanceKlass::cast(klass)->initialize(CHECK); 1043 } 1044 1045 1046 // Creates the initial ThreadGroup 1047 static Handle create_initial_thread_group(TRAPS) { 1048 Handle system_instance = JavaCalls::construct_new_instance( 1049 SystemDictionary::ThreadGroup_klass(), 1050 vmSymbols::void_method_signature(), 1051 CHECK_NH); 1052 Universe::set_system_thread_group(system_instance()); 1053 1054 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1055 Handle main_instance = JavaCalls::construct_new_instance( 1056 SystemDictionary::ThreadGroup_klass(), 1057 vmSymbols::threadgroup_string_void_signature(), 1058 system_instance, 1059 string, 1060 CHECK_NH); 1061 return main_instance; 1062 } 1063 1064 // Creates the initial Thread 1065 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1066 TRAPS) { 1067 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1068 assert(ik->is_initialized(), "must be"); 1069 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1070 1071 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1072 // constructor calls Thread.current(), which must be set here for the 1073 // initial thread. 1074 java_lang_Thread::set_thread(thread_oop(), thread); 1075 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1076 thread->set_threadObj(thread_oop()); 1077 1078 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1079 1080 JavaValue result(T_VOID); 1081 JavaCalls::call_special(&result, thread_oop, 1082 ik, 1083 vmSymbols::object_initializer_name(), 1084 vmSymbols::threadgroup_string_void_signature(), 1085 thread_group, 1086 string, 1087 CHECK_NULL); 1088 return thread_oop(); 1089 } 1090 1091 char java_runtime_name[128] = ""; 1092 char java_runtime_version[128] = ""; 1093 char java_runtime_vendor_version[128] = ""; 1094 char java_runtime_vendor_vm_bug_url[128] = ""; 1095 1096 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1097 static const char* get_java_runtime_name(TRAPS) { 1098 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1099 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1100 fieldDescriptor fd; 1101 bool found = k != NULL && 1102 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1103 vmSymbols::string_signature(), &fd); 1104 if (found) { 1105 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1106 if (name_oop == NULL) { 1107 return NULL; 1108 } 1109 const char* name = java_lang_String::as_utf8_string(name_oop, 1110 java_runtime_name, 1111 sizeof(java_runtime_name)); 1112 return name; 1113 } else { 1114 return NULL; 1115 } 1116 } 1117 1118 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1119 static const char* get_java_runtime_version(TRAPS) { 1120 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1121 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1122 fieldDescriptor fd; 1123 bool found = k != NULL && 1124 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1125 vmSymbols::string_signature(), &fd); 1126 if (found) { 1127 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1128 if (name_oop == NULL) { 1129 return NULL; 1130 } 1131 const char* name = java_lang_String::as_utf8_string(name_oop, 1132 java_runtime_version, 1133 sizeof(java_runtime_version)); 1134 return name; 1135 } else { 1136 return NULL; 1137 } 1138 } 1139 1140 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION 1141 static const char* get_java_runtime_vendor_version(TRAPS) { 1142 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1143 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1144 fieldDescriptor fd; 1145 bool found = k != NULL && 1146 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(), 1147 vmSymbols::string_signature(), &fd); 1148 if (found) { 1149 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1150 if (name_oop == NULL) { 1151 return NULL; 1152 } 1153 const char* name = java_lang_String::as_utf8_string(name_oop, 1154 java_runtime_vendor_version, 1155 sizeof(java_runtime_vendor_version)); 1156 return name; 1157 } else { 1158 return NULL; 1159 } 1160 } 1161 1162 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG 1163 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) { 1164 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1165 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1166 fieldDescriptor fd; 1167 bool found = k != NULL && 1168 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(), 1169 vmSymbols::string_signature(), &fd); 1170 if (found) { 1171 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1172 if (name_oop == NULL) { 1173 return NULL; 1174 } 1175 const char* name = java_lang_String::as_utf8_string(name_oop, 1176 java_runtime_vendor_vm_bug_url, 1177 sizeof(java_runtime_vendor_vm_bug_url)); 1178 return name; 1179 } else { 1180 return NULL; 1181 } 1182 } 1183 1184 // General purpose hook into Java code, run once when the VM is initialized. 1185 // The Java library method itself may be changed independently from the VM. 1186 static void call_postVMInitHook(TRAPS) { 1187 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1188 if (klass != NULL) { 1189 JavaValue result(T_VOID); 1190 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1191 vmSymbols::void_method_signature(), 1192 CHECK); 1193 } 1194 } 1195 1196 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1197 bool daemon, TRAPS) { 1198 assert(thread_group.not_null(), "thread group should be specified"); 1199 assert(threadObj() == NULL, "should only create Java thread object once"); 1200 1201 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1202 assert(ik->is_initialized(), "must be"); 1203 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1204 1205 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1206 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1207 // constructor calls Thread.current(), which must be set here. 1208 java_lang_Thread::set_thread(thread_oop(), this); 1209 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1210 set_threadObj(thread_oop()); 1211 1212 JavaValue result(T_VOID); 1213 if (thread_name != NULL) { 1214 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1215 // Thread gets assigned specified name and null target 1216 JavaCalls::call_special(&result, 1217 thread_oop, 1218 ik, 1219 vmSymbols::object_initializer_name(), 1220 vmSymbols::threadgroup_string_void_signature(), 1221 thread_group, 1222 name, 1223 THREAD); 1224 } else { 1225 // Thread gets assigned name "Thread-nnn" and null target 1226 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1227 JavaCalls::call_special(&result, 1228 thread_oop, 1229 ik, 1230 vmSymbols::object_initializer_name(), 1231 vmSymbols::threadgroup_runnable_void_signature(), 1232 thread_group, 1233 Handle(), 1234 THREAD); 1235 } 1236 1237 1238 if (daemon) { 1239 java_lang_Thread::set_daemon(thread_oop()); 1240 } 1241 1242 if (HAS_PENDING_EXCEPTION) { 1243 return; 1244 } 1245 1246 Klass* group = SystemDictionary::ThreadGroup_klass(); 1247 Handle threadObj(THREAD, this->threadObj()); 1248 1249 JavaCalls::call_special(&result, 1250 thread_group, 1251 group, 1252 vmSymbols::add_method_name(), 1253 vmSymbols::thread_void_signature(), 1254 threadObj, // Arg 1 1255 THREAD); 1256 } 1257 1258 // List of all NonJavaThreads and safe iteration over that list. 1259 1260 class NonJavaThread::List { 1261 public: 1262 NonJavaThread* volatile _head; 1263 SingleWriterSynchronizer _protect; 1264 1265 List() : _head(NULL), _protect() {} 1266 }; 1267 1268 NonJavaThread::List NonJavaThread::_the_list; 1269 1270 NonJavaThread::Iterator::Iterator() : 1271 _protect_enter(_the_list._protect.enter()), 1272 _current(Atomic::load_acquire(&_the_list._head)) 1273 {} 1274 1275 NonJavaThread::Iterator::~Iterator() { 1276 _the_list._protect.exit(_protect_enter); 1277 } 1278 1279 void NonJavaThread::Iterator::step() { 1280 assert(!end(), "precondition"); 1281 _current = Atomic::load_acquire(&_current->_next); 1282 } 1283 1284 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1285 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1286 } 1287 1288 NonJavaThread::~NonJavaThread() { } 1289 1290 void NonJavaThread::add_to_the_list() { 1291 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1292 // Initialize BarrierSet-related data before adding to list. 1293 BarrierSet::barrier_set()->on_thread_attach(this); 1294 Atomic::release_store(&_next, _the_list._head); 1295 Atomic::release_store(&_the_list._head, this); 1296 } 1297 1298 void NonJavaThread::remove_from_the_list() { 1299 { 1300 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1301 // Cleanup BarrierSet-related data before removing from list. 1302 BarrierSet::barrier_set()->on_thread_detach(this); 1303 NonJavaThread* volatile* p = &_the_list._head; 1304 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1305 if (t == this) { 1306 *p = _next; 1307 break; 1308 } 1309 } 1310 } 1311 // Wait for any in-progress iterators. Concurrent synchronize is not 1312 // allowed, so do it while holding a dedicated lock. Outside and distinct 1313 // from NJTList_lock in case an iteration attempts to lock it. 1314 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1315 _the_list._protect.synchronize(); 1316 _next = NULL; // Safe to drop the link now. 1317 } 1318 1319 void NonJavaThread::pre_run() { 1320 add_to_the_list(); 1321 1322 // This is slightly odd in that NamedThread is a subclass, but 1323 // in fact name() is defined in Thread 1324 assert(this->name() != NULL, "thread name was not set before it was started"); 1325 this->set_native_thread_name(this->name()); 1326 } 1327 1328 void NonJavaThread::post_run() { 1329 JFR_ONLY(Jfr::on_thread_exit(this);) 1330 remove_from_the_list(); 1331 // Ensure thread-local-storage is cleared before termination. 1332 Thread::clear_thread_current(); 1333 } 1334 1335 // NamedThread -- non-JavaThread subclasses with multiple 1336 // uniquely named instances should derive from this. 1337 NamedThread::NamedThread() : 1338 NonJavaThread(), 1339 _name(NULL), 1340 _processed_thread(NULL), 1341 _gc_id(GCId::undefined()) 1342 {} 1343 1344 NamedThread::~NamedThread() { 1345 FREE_C_HEAP_ARRAY(char, _name); 1346 } 1347 1348 void NamedThread::set_name(const char* format, ...) { 1349 guarantee(_name == NULL, "Only get to set name once."); 1350 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1351 va_list ap; 1352 va_start(ap, format); 1353 jio_vsnprintf(_name, max_name_len, format, ap); 1354 va_end(ap); 1355 } 1356 1357 void NamedThread::print_on(outputStream* st) const { 1358 st->print("\"%s\" ", name()); 1359 Thread::print_on(st); 1360 st->cr(); 1361 } 1362 1363 1364 // ======= WatcherThread ======== 1365 1366 // The watcher thread exists to simulate timer interrupts. It should 1367 // be replaced by an abstraction over whatever native support for 1368 // timer interrupts exists on the platform. 1369 1370 WatcherThread* WatcherThread::_watcher_thread = NULL; 1371 bool WatcherThread::_startable = false; 1372 volatile bool WatcherThread::_should_terminate = false; 1373 1374 WatcherThread::WatcherThread() : NonJavaThread() { 1375 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1376 if (os::create_thread(this, os::watcher_thread)) { 1377 _watcher_thread = this; 1378 1379 // Set the watcher thread to the highest OS priority which should not be 1380 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1381 // is created. The only normal thread using this priority is the reference 1382 // handler thread, which runs for very short intervals only. 1383 // If the VMThread's priority is not lower than the WatcherThread profiling 1384 // will be inaccurate. 1385 os::set_priority(this, MaxPriority); 1386 if (!DisableStartThread) { 1387 os::start_thread(this); 1388 } 1389 } 1390 } 1391 1392 int WatcherThread::sleep() const { 1393 // The WatcherThread does not participate in the safepoint protocol 1394 // for the PeriodicTask_lock because it is not a JavaThread. 1395 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1396 1397 if (_should_terminate) { 1398 // check for termination before we do any housekeeping or wait 1399 return 0; // we did not sleep. 1400 } 1401 1402 // remaining will be zero if there are no tasks, 1403 // causing the WatcherThread to sleep until a task is 1404 // enrolled 1405 int remaining = PeriodicTask::time_to_wait(); 1406 int time_slept = 0; 1407 1408 // we expect this to timeout - we only ever get unparked when 1409 // we should terminate or when a new task has been enrolled 1410 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1411 1412 jlong time_before_loop = os::javaTimeNanos(); 1413 1414 while (true) { 1415 bool timedout = ml.wait(remaining); 1416 jlong now = os::javaTimeNanos(); 1417 1418 if (remaining == 0) { 1419 // if we didn't have any tasks we could have waited for a long time 1420 // consider the time_slept zero and reset time_before_loop 1421 time_slept = 0; 1422 time_before_loop = now; 1423 } else { 1424 // need to recalculate since we might have new tasks in _tasks 1425 time_slept = (int) ((now - time_before_loop) / 1000000); 1426 } 1427 1428 // Change to task list or spurious wakeup of some kind 1429 if (timedout || _should_terminate) { 1430 break; 1431 } 1432 1433 remaining = PeriodicTask::time_to_wait(); 1434 if (remaining == 0) { 1435 // Last task was just disenrolled so loop around and wait until 1436 // another task gets enrolled 1437 continue; 1438 } 1439 1440 remaining -= time_slept; 1441 if (remaining <= 0) { 1442 break; 1443 } 1444 } 1445 1446 return time_slept; 1447 } 1448 1449 void WatcherThread::run() { 1450 assert(this == watcher_thread(), "just checking"); 1451 1452 this->set_active_handles(JNIHandleBlock::allocate_block()); 1453 while (true) { 1454 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1455 assert(watcher_thread() == this, "thread consistency check"); 1456 1457 // Calculate how long it'll be until the next PeriodicTask work 1458 // should be done, and sleep that amount of time. 1459 int time_waited = sleep(); 1460 1461 if (VMError::is_error_reported()) { 1462 // A fatal error has happened, the error handler(VMError::report_and_die) 1463 // should abort JVM after creating an error log file. However in some 1464 // rare cases, the error handler itself might deadlock. Here periodically 1465 // check for error reporting timeouts, and if it happens, just proceed to 1466 // abort the VM. 1467 1468 // This code is in WatcherThread because WatcherThread wakes up 1469 // periodically so the fatal error handler doesn't need to do anything; 1470 // also because the WatcherThread is less likely to crash than other 1471 // threads. 1472 1473 for (;;) { 1474 // Note: we use naked sleep in this loop because we want to avoid using 1475 // any kind of VM infrastructure which may be broken at this point. 1476 if (VMError::check_timeout()) { 1477 // We hit error reporting timeout. Error reporting was interrupted and 1478 // will be wrapping things up now (closing files etc). Give it some more 1479 // time, then quit the VM. 1480 os::naked_short_sleep(200); 1481 // Print a message to stderr. 1482 fdStream err(defaultStream::output_fd()); 1483 err.print_raw_cr("# [ timer expired, abort... ]"); 1484 // skip atexit/vm_exit/vm_abort hooks 1485 os::die(); 1486 } 1487 1488 // Wait a second, then recheck for timeout. 1489 os::naked_short_sleep(999); 1490 } 1491 } 1492 1493 if (_should_terminate) { 1494 // check for termination before posting the next tick 1495 break; 1496 } 1497 1498 PeriodicTask::real_time_tick(time_waited); 1499 } 1500 1501 // Signal that it is terminated 1502 { 1503 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1504 _watcher_thread = NULL; 1505 Terminator_lock->notify_all(); 1506 } 1507 } 1508 1509 void WatcherThread::start() { 1510 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1511 1512 if (watcher_thread() == NULL && _startable) { 1513 _should_terminate = false; 1514 // Create the single instance of WatcherThread 1515 new WatcherThread(); 1516 } 1517 } 1518 1519 void WatcherThread::make_startable() { 1520 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1521 _startable = true; 1522 } 1523 1524 void WatcherThread::stop() { 1525 { 1526 // Follow normal safepoint aware lock enter protocol since the 1527 // WatcherThread is stopped by another JavaThread. 1528 MutexLocker ml(PeriodicTask_lock); 1529 _should_terminate = true; 1530 1531 WatcherThread* watcher = watcher_thread(); 1532 if (watcher != NULL) { 1533 // unpark the WatcherThread so it can see that it should terminate 1534 watcher->unpark(); 1535 } 1536 } 1537 1538 MonitorLocker mu(Terminator_lock); 1539 1540 while (watcher_thread() != NULL) { 1541 // This wait should make safepoint checks, wait without a timeout, 1542 // and wait as a suspend-equivalent condition. 1543 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1544 } 1545 } 1546 1547 void WatcherThread::unpark() { 1548 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1549 PeriodicTask_lock->notify(); 1550 } 1551 1552 void WatcherThread::print_on(outputStream* st) const { 1553 st->print("\"%s\" ", name()); 1554 Thread::print_on(st); 1555 st->cr(); 1556 } 1557 1558 // ======= JavaThread ======== 1559 1560 #if INCLUDE_JVMCI 1561 1562 jlong* JavaThread::_jvmci_old_thread_counters; 1563 1564 bool jvmci_counters_include(JavaThread* thread) { 1565 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1566 } 1567 1568 void JavaThread::collect_counters(jlong* array, int length) { 1569 assert(length == JVMCICounterSize, "wrong value"); 1570 for (int i = 0; i < length; i++) { 1571 array[i] = _jvmci_old_thread_counters[i]; 1572 } 1573 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1574 if (jvmci_counters_include(tp)) { 1575 for (int i = 0; i < length; i++) { 1576 array[i] += tp->_jvmci_counters[i]; 1577 } 1578 } 1579 } 1580 } 1581 1582 // Attempt to enlarge the array for per thread counters. 1583 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1584 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1585 if (old_counters == NULL) { 1586 old_counters = new_counters; 1587 memset(old_counters, 0, sizeof(jlong) * new_size); 1588 } else { 1589 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1590 new_counters[i] = old_counters[i]; 1591 } 1592 if (new_size > current_size) { 1593 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1594 } 1595 FREE_C_HEAP_ARRAY(jlong, old_counters); 1596 } 1597 return new_counters; 1598 } 1599 1600 // Attempt to enlarge the array for per thread counters. 1601 void JavaThread::resize_counters(int current_size, int new_size) { 1602 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1603 } 1604 1605 class VM_JVMCIResizeCounters : public VM_Operation { 1606 private: 1607 int _new_size; 1608 1609 public: 1610 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { } 1611 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; } 1612 bool allow_nested_vm_operations() const { return true; } 1613 void doit() { 1614 // Resize the old thread counters array 1615 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size); 1616 JavaThread::_jvmci_old_thread_counters = new_counters; 1617 1618 // Now resize each threads array 1619 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1620 tp->resize_counters(JVMCICounterSize, _new_size); 1621 } 1622 JVMCICounterSize = _new_size; 1623 } 1624 }; 1625 1626 void JavaThread::resize_all_jvmci_counters(int new_size) { 1627 VM_JVMCIResizeCounters op(new_size); 1628 VMThread::execute(&op); 1629 } 1630 1631 #endif // INCLUDE_JVMCI 1632 1633 // A JavaThread is a normal Java thread 1634 1635 void JavaThread::initialize() { 1636 // Initialize fields 1637 1638 set_saved_exception_pc(NULL); 1639 set_threadObj(NULL); 1640 _anchor.clear(); 1641 set_entry_point(NULL); 1642 set_jni_functions(jni_functions()); 1643 set_callee_target(NULL); 1644 set_vm_result(NULL); 1645 set_vm_result_2(NULL); 1646 set_vframe_array_head(NULL); 1647 set_vframe_array_last(NULL); 1648 set_deferred_locals(NULL); 1649 set_deopt_mark(NULL); 1650 set_deopt_compiled_method(NULL); 1651 set_monitor_chunks(NULL); 1652 _on_thread_list = false; 1653 _thread_state = _thread_new; 1654 _terminated = _not_terminated; 1655 _array_for_gc = NULL; 1656 _suspend_equivalent = false; 1657 _in_deopt_handler = 0; 1658 _doing_unsafe_access = false; 1659 _stack_guard_state = stack_guard_unused; 1660 #if INCLUDE_JVMCI 1661 _pending_monitorenter = false; 1662 _pending_deoptimization = -1; 1663 _pending_failed_speculation = 0; 1664 _pending_transfer_to_interpreter = false; 1665 _in_retryable_allocation = false; 1666 _jvmci._alternate_call_target = NULL; 1667 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1668 _jvmci_counters = NULL; 1669 if (JVMCICounterSize > 0) { 1670 resize_counters(0, (int) JVMCICounterSize); 1671 } 1672 #endif // INCLUDE_JVMCI 1673 _reserved_stack_activation = NULL; // stack base not known yet 1674 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1675 _exception_pc = 0; 1676 _exception_handler_pc = 0; 1677 _is_method_handle_return = 0; 1678 _jvmti_thread_state= NULL; 1679 _should_post_on_exceptions_flag = JNI_FALSE; 1680 _interp_only_mode = 0; 1681 _special_runtime_exit_condition = _no_async_condition; 1682 _pending_async_exception = NULL; 1683 _thread_stat = NULL; 1684 _thread_stat = new ThreadStatistics(); 1685 _jni_active_critical = 0; 1686 _pending_jni_exception_check_fn = NULL; 1687 _do_not_unlock_if_synchronized = false; 1688 _cached_monitor_info = NULL; 1689 _parker = Parker::Allocate(this); 1690 _SleepEvent = ParkEvent::Allocate(this); 1691 // Setup safepoint state info for this thread 1692 ThreadSafepointState::create(this); 1693 1694 debug_only(_java_call_counter = 0); 1695 1696 // JVMTI PopFrame support 1697 _popframe_condition = popframe_inactive; 1698 _popframe_preserved_args = NULL; 1699 _popframe_preserved_args_size = 0; 1700 _frames_to_pop_failed_realloc = 0; 1701 1702 if (SafepointMechanism::uses_thread_local_poll()) { 1703 SafepointMechanism::initialize_header(this); 1704 } 1705 1706 _class_to_be_initialized = NULL; 1707 1708 pd_initialize(); 1709 } 1710 1711 JavaThread::JavaThread(bool is_attaching_via_jni) : 1712 Thread() { 1713 initialize(); 1714 if (is_attaching_via_jni) { 1715 _jni_attach_state = _attaching_via_jni; 1716 } else { 1717 _jni_attach_state = _not_attaching_via_jni; 1718 } 1719 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1720 } 1721 1722 1723 // interrupt support 1724 1725 void JavaThread::interrupt() { 1726 debug_only(check_for_dangling_thread_pointer(this);) 1727 1728 // For Windows _interrupt_event 1729 osthread()->set_interrupted(true); 1730 1731 // For Thread.sleep 1732 _SleepEvent->unpark(); 1733 1734 // For JSR166 LockSupport.park 1735 parker()->unpark(); 1736 1737 // For ObjectMonitor and JvmtiRawMonitor 1738 _ParkEvent->unpark(); 1739 } 1740 1741 1742 bool JavaThread::is_interrupted(bool clear_interrupted) { 1743 debug_only(check_for_dangling_thread_pointer(this);) 1744 1745 if (threadObj() == NULL) { 1746 // If there is no j.l.Thread then it is impossible to have 1747 // been interrupted. We can find NULL during VM initialization 1748 // or when a JNI thread is still in the process of attaching. 1749 // In such cases this must be the current thread. 1750 assert(this == Thread::current(), "invariant"); 1751 return false; 1752 } 1753 1754 bool interrupted = java_lang_Thread::interrupted(threadObj()); 1755 1756 // NOTE that since there is no "lock" around the interrupt and 1757 // is_interrupted operations, there is the possibility that the 1758 // interrupted flag will be "false" but that the 1759 // low-level events will be in the signaled state. This is 1760 // intentional. The effect of this is that Object.wait() and 1761 // LockSupport.park() will appear to have a spurious wakeup, which 1762 // is allowed and not harmful, and the possibility is so rare that 1763 // it is not worth the added complexity to add yet another lock. 1764 // For the sleep event an explicit reset is performed on entry 1765 // to JavaThread::sleep, so there is no early return. It has also been 1766 // recommended not to put the interrupted flag into the "event" 1767 // structure because it hides the issue. 1768 // Also, because there is no lock, we must only clear the interrupt 1769 // state if we are going to report that we were interrupted; otherwise 1770 // an interrupt that happens just after we read the field would be lost. 1771 if (interrupted && clear_interrupted) { 1772 assert(this == Thread::current(), "only the current thread can clear"); 1773 java_lang_Thread::set_interrupted(threadObj(), false); 1774 osthread()->set_interrupted(false); 1775 } 1776 1777 return interrupted; 1778 } 1779 1780 bool JavaThread::reguard_stack(address cur_sp) { 1781 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1782 && _stack_guard_state != stack_guard_reserved_disabled) { 1783 return true; // Stack already guarded or guard pages not needed. 1784 } 1785 1786 if (register_stack_overflow()) { 1787 // For those architectures which have separate register and 1788 // memory stacks, we must check the register stack to see if 1789 // it has overflowed. 1790 return false; 1791 } 1792 1793 // Java code never executes within the yellow zone: the latter is only 1794 // there to provoke an exception during stack banging. If java code 1795 // is executing there, either StackShadowPages should be larger, or 1796 // some exception code in c1, c2 or the interpreter isn't unwinding 1797 // when it should. 1798 guarantee(cur_sp > stack_reserved_zone_base(), 1799 "not enough space to reguard - increase StackShadowPages"); 1800 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1801 enable_stack_yellow_reserved_zone(); 1802 if (reserved_stack_activation() != stack_base()) { 1803 set_reserved_stack_activation(stack_base()); 1804 } 1805 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1806 set_reserved_stack_activation(stack_base()); 1807 enable_stack_reserved_zone(); 1808 } 1809 return true; 1810 } 1811 1812 bool JavaThread::reguard_stack(void) { 1813 return reguard_stack(os::current_stack_pointer()); 1814 } 1815 1816 1817 void JavaThread::block_if_vm_exited() { 1818 if (_terminated == _vm_exited) { 1819 // _vm_exited is set at safepoint, and Threads_lock is never released 1820 // we will block here forever. 1821 // Here we can be doing a jump from a safe state to an unsafe state without 1822 // proper transition, but it happens after the final safepoint has begun. 1823 set_thread_state(_thread_in_vm); 1824 Threads_lock->lock(); 1825 ShouldNotReachHere(); 1826 } 1827 } 1828 1829 1830 // Remove this ifdef when C1 is ported to the compiler interface. 1831 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1832 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1833 1834 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1835 Thread() { 1836 initialize(); 1837 _jni_attach_state = _not_attaching_via_jni; 1838 set_entry_point(entry_point); 1839 // Create the native thread itself. 1840 // %note runtime_23 1841 os::ThreadType thr_type = os::java_thread; 1842 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1843 os::java_thread; 1844 os::create_thread(this, thr_type, stack_sz); 1845 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1846 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1847 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1848 // the exception consists of creating the exception object & initializing it, initialization 1849 // will leave the VM via a JavaCall and then all locks must be unlocked). 1850 // 1851 // The thread is still suspended when we reach here. Thread must be explicit started 1852 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1853 // by calling Threads:add. The reason why this is not done here, is because the thread 1854 // object must be fully initialized (take a look at JVM_Start) 1855 } 1856 1857 JavaThread::~JavaThread() { 1858 1859 // JSR166 -- return the parker to the free list 1860 Parker::Release(_parker); 1861 _parker = NULL; 1862 1863 // Return the sleep event to the free list 1864 ParkEvent::Release(_SleepEvent); 1865 _SleepEvent = NULL; 1866 1867 // Free any remaining previous UnrollBlock 1868 vframeArray* old_array = vframe_array_last(); 1869 1870 if (old_array != NULL) { 1871 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1872 old_array->set_unroll_block(NULL); 1873 delete old_info; 1874 delete old_array; 1875 } 1876 1877 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1878 if (deferred != NULL) { 1879 // This can only happen if thread is destroyed before deoptimization occurs. 1880 assert(deferred->length() != 0, "empty array!"); 1881 do { 1882 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1883 deferred->remove_at(0); 1884 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1885 delete dlv; 1886 } while (deferred->length() != 0); 1887 delete deferred; 1888 } 1889 1890 // All Java related clean up happens in exit 1891 ThreadSafepointState::destroy(this); 1892 if (_thread_stat != NULL) delete _thread_stat; 1893 1894 #if INCLUDE_JVMCI 1895 if (JVMCICounterSize > 0) { 1896 if (jvmci_counters_include(this)) { 1897 for (int i = 0; i < JVMCICounterSize; i++) { 1898 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1899 } 1900 } 1901 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1902 } 1903 #endif // INCLUDE_JVMCI 1904 } 1905 1906 1907 // First JavaThread specific code executed by a new Java thread. 1908 void JavaThread::pre_run() { 1909 // empty - see comments in run() 1910 } 1911 1912 // The main routine called by a new Java thread. This isn't overridden 1913 // by subclasses, instead different subclasses define a different "entry_point" 1914 // which defines the actual logic for that kind of thread. 1915 void JavaThread::run() { 1916 // initialize thread-local alloc buffer related fields 1917 this->initialize_tlab(); 1918 1919 // Used to test validity of stack trace backs. 1920 // This can't be moved into pre_run() else we invalidate 1921 // the requirement that thread_main_inner is lower on 1922 // the stack. Consequently all the initialization logic 1923 // stays here in run() rather than pre_run(). 1924 this->record_base_of_stack_pointer(); 1925 1926 this->create_stack_guard_pages(); 1927 1928 this->cache_global_variables(); 1929 1930 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1931 // in the VM. Change thread state from _thread_new to _thread_in_vm 1932 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1933 // Before a thread is on the threads list it is always safe, so after leaving the 1934 // _thread_new we should emit a instruction barrier. The distance to modified code 1935 // from here is probably far enough, but this is consistent and safe. 1936 OrderAccess::cross_modify_fence(); 1937 1938 assert(JavaThread::current() == this, "sanity check"); 1939 assert(!Thread::current()->owns_locks(), "sanity check"); 1940 1941 DTRACE_THREAD_PROBE(start, this); 1942 1943 // This operation might block. We call that after all safepoint checks for a new thread has 1944 // been completed. 1945 this->set_active_handles(JNIHandleBlock::allocate_block()); 1946 1947 if (JvmtiExport::should_post_thread_life()) { 1948 JvmtiExport::post_thread_start(this); 1949 1950 } 1951 1952 // We call another function to do the rest so we are sure that the stack addresses used 1953 // from there will be lower than the stack base just computed. 1954 thread_main_inner(); 1955 } 1956 1957 void JavaThread::thread_main_inner() { 1958 assert(JavaThread::current() == this, "sanity check"); 1959 assert(this->threadObj() != NULL, "just checking"); 1960 1961 // Execute thread entry point unless this thread has a pending exception 1962 // or has been stopped before starting. 1963 // Note: Due to JVM_StopThread we can have pending exceptions already! 1964 if (!this->has_pending_exception() && 1965 !java_lang_Thread::is_stillborn(this->threadObj())) { 1966 { 1967 ResourceMark rm(this); 1968 this->set_native_thread_name(this->get_thread_name()); 1969 } 1970 HandleMark hm(this); 1971 this->entry_point()(this, this); 1972 } 1973 1974 DTRACE_THREAD_PROBE(stop, this); 1975 1976 // Cleanup is handled in post_run() 1977 } 1978 1979 // Shared teardown for all JavaThreads 1980 void JavaThread::post_run() { 1981 this->exit(false); 1982 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1983 // for any shared tear-down. 1984 this->smr_delete(); 1985 } 1986 1987 static void ensure_join(JavaThread* thread) { 1988 // We do not need to grab the Threads_lock, since we are operating on ourself. 1989 Handle threadObj(thread, thread->threadObj()); 1990 assert(threadObj.not_null(), "java thread object must exist"); 1991 ObjectLocker lock(threadObj, thread); 1992 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1993 thread->clear_pending_exception(); 1994 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1995 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1996 // Clear the native thread instance - this makes isAlive return false and allows the join() 1997 // to complete once we've done the notify_all below 1998 java_lang_Thread::set_thread(threadObj(), NULL); 1999 lock.notify_all(thread); 2000 // Ignore pending exception (ThreadDeath), since we are exiting anyway 2001 thread->clear_pending_exception(); 2002 } 2003 2004 static bool is_daemon(oop threadObj) { 2005 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 2006 } 2007 2008 // For any new cleanup additions, please check to see if they need to be applied to 2009 // cleanup_failed_attach_current_thread as well. 2010 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 2011 assert(this == JavaThread::current(), "thread consistency check"); 2012 2013 elapsedTimer _timer_exit_phase1; 2014 elapsedTimer _timer_exit_phase2; 2015 elapsedTimer _timer_exit_phase3; 2016 elapsedTimer _timer_exit_phase4; 2017 2018 if (log_is_enabled(Debug, os, thread, timer)) { 2019 _timer_exit_phase1.start(); 2020 } 2021 2022 HandleMark hm(this); 2023 Handle uncaught_exception(this, this->pending_exception()); 2024 this->clear_pending_exception(); 2025 Handle threadObj(this, this->threadObj()); 2026 assert(threadObj.not_null(), "Java thread object should be created"); 2027 2028 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 2029 { 2030 EXCEPTION_MARK; 2031 2032 CLEAR_PENDING_EXCEPTION; 2033 } 2034 if (!destroy_vm) { 2035 if (uncaught_exception.not_null()) { 2036 EXCEPTION_MARK; 2037 // Call method Thread.dispatchUncaughtException(). 2038 Klass* thread_klass = SystemDictionary::Thread_klass(); 2039 JavaValue result(T_VOID); 2040 JavaCalls::call_virtual(&result, 2041 threadObj, thread_klass, 2042 vmSymbols::dispatchUncaughtException_name(), 2043 vmSymbols::throwable_void_signature(), 2044 uncaught_exception, 2045 THREAD); 2046 if (HAS_PENDING_EXCEPTION) { 2047 ResourceMark rm(this); 2048 jio_fprintf(defaultStream::error_stream(), 2049 "\nException: %s thrown from the UncaughtExceptionHandler" 2050 " in thread \"%s\"\n", 2051 pending_exception()->klass()->external_name(), 2052 get_thread_name()); 2053 CLEAR_PENDING_EXCEPTION; 2054 } 2055 } 2056 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2057 2058 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2059 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2060 // is deprecated anyhow. 2061 if (!is_Compiler_thread()) { 2062 int count = 3; 2063 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2064 EXCEPTION_MARK; 2065 JavaValue result(T_VOID); 2066 Klass* thread_klass = SystemDictionary::Thread_klass(); 2067 JavaCalls::call_virtual(&result, 2068 threadObj, thread_klass, 2069 vmSymbols::exit_method_name(), 2070 vmSymbols::void_method_signature(), 2071 THREAD); 2072 CLEAR_PENDING_EXCEPTION; 2073 } 2074 } 2075 // notify JVMTI 2076 if (JvmtiExport::should_post_thread_life()) { 2077 JvmtiExport::post_thread_end(this); 2078 } 2079 2080 // We have notified the agents that we are exiting, before we go on, 2081 // we must check for a pending external suspend request and honor it 2082 // in order to not surprise the thread that made the suspend request. 2083 while (true) { 2084 { 2085 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2086 if (!is_external_suspend()) { 2087 set_terminated(_thread_exiting); 2088 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2089 break; 2090 } 2091 // Implied else: 2092 // Things get a little tricky here. We have a pending external 2093 // suspend request, but we are holding the SR_lock so we 2094 // can't just self-suspend. So we temporarily drop the lock 2095 // and then self-suspend. 2096 } 2097 2098 ThreadBlockInVM tbivm(this); 2099 java_suspend_self(); 2100 2101 // We're done with this suspend request, but we have to loop around 2102 // and check again. Eventually we will get SR_lock without a pending 2103 // external suspend request and will be able to mark ourselves as 2104 // exiting. 2105 } 2106 // no more external suspends are allowed at this point 2107 } else { 2108 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2109 // before_exit() has already posted JVMTI THREAD_END events 2110 } 2111 2112 if (log_is_enabled(Debug, os, thread, timer)) { 2113 _timer_exit_phase1.stop(); 2114 _timer_exit_phase2.start(); 2115 } 2116 2117 // Capture daemon status before the thread is marked as terminated. 2118 bool daemon = is_daemon(threadObj()); 2119 2120 // Notify waiters on thread object. This has to be done after exit() is called 2121 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2122 // group should have the destroyed bit set before waiters are notified). 2123 ensure_join(this); 2124 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2125 2126 if (log_is_enabled(Debug, os, thread, timer)) { 2127 _timer_exit_phase2.stop(); 2128 _timer_exit_phase3.start(); 2129 } 2130 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2131 // held by this thread must be released. The spec does not distinguish 2132 // between JNI-acquired and regular Java monitors. We can only see 2133 // regular Java monitors here if monitor enter-exit matching is broken. 2134 // 2135 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2136 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2137 if (exit_type == jni_detach) { 2138 // Sanity check even though JNI DetachCurrentThread() would have 2139 // returned JNI_ERR if there was a Java frame. JavaThread exit 2140 // should be done executing Java code by the time we get here. 2141 assert(!this->has_last_Java_frame(), 2142 "should not have a Java frame when detaching or exiting"); 2143 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2144 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2145 } 2146 2147 // These things needs to be done while we are still a Java Thread. Make sure that thread 2148 // is in a consistent state, in case GC happens 2149 JFR_ONLY(Jfr::on_thread_exit(this);) 2150 2151 if (active_handles() != NULL) { 2152 JNIHandleBlock* block = active_handles(); 2153 set_active_handles(NULL); 2154 JNIHandleBlock::release_block(block); 2155 } 2156 2157 if (free_handle_block() != NULL) { 2158 JNIHandleBlock* block = free_handle_block(); 2159 set_free_handle_block(NULL); 2160 JNIHandleBlock::release_block(block); 2161 } 2162 2163 // These have to be removed while this is still a valid thread. 2164 remove_stack_guard_pages(); 2165 2166 if (UseTLAB) { 2167 tlab().retire(); 2168 } 2169 2170 if (JvmtiEnv::environments_might_exist()) { 2171 JvmtiExport::cleanup_thread(this); 2172 } 2173 2174 // We must flush any deferred card marks and other various GC barrier 2175 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2176 // before removing a thread from the list of active threads. 2177 BarrierSet::barrier_set()->on_thread_detach(this); 2178 2179 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2180 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2181 os::current_thread_id()); 2182 2183 if (log_is_enabled(Debug, os, thread, timer)) { 2184 _timer_exit_phase3.stop(); 2185 _timer_exit_phase4.start(); 2186 } 2187 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2188 Threads::remove(this, daemon); 2189 2190 if (log_is_enabled(Debug, os, thread, timer)) { 2191 _timer_exit_phase4.stop(); 2192 ResourceMark rm(this); 2193 log_debug(os, thread, timer)("name='%s'" 2194 ", exit-phase1=" JLONG_FORMAT 2195 ", exit-phase2=" JLONG_FORMAT 2196 ", exit-phase3=" JLONG_FORMAT 2197 ", exit-phase4=" JLONG_FORMAT, 2198 get_thread_name(), 2199 _timer_exit_phase1.milliseconds(), 2200 _timer_exit_phase2.milliseconds(), 2201 _timer_exit_phase3.milliseconds(), 2202 _timer_exit_phase4.milliseconds()); 2203 } 2204 } 2205 2206 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2207 if (active_handles() != NULL) { 2208 JNIHandleBlock* block = active_handles(); 2209 set_active_handles(NULL); 2210 JNIHandleBlock::release_block(block); 2211 } 2212 2213 if (free_handle_block() != NULL) { 2214 JNIHandleBlock* block = free_handle_block(); 2215 set_free_handle_block(NULL); 2216 JNIHandleBlock::release_block(block); 2217 } 2218 2219 // These have to be removed while this is still a valid thread. 2220 remove_stack_guard_pages(); 2221 2222 if (UseTLAB) { 2223 tlab().retire(); 2224 } 2225 2226 BarrierSet::barrier_set()->on_thread_detach(this); 2227 2228 Threads::remove(this, is_daemon); 2229 this->smr_delete(); 2230 } 2231 2232 JavaThread* JavaThread::active() { 2233 Thread* thread = Thread::current(); 2234 if (thread->is_Java_thread()) { 2235 return (JavaThread*) thread; 2236 } else { 2237 assert(thread->is_VM_thread(), "this must be a vm thread"); 2238 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2239 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2240 assert(ret->is_Java_thread(), "must be a Java thread"); 2241 return ret; 2242 } 2243 } 2244 2245 bool JavaThread::is_lock_owned(address adr) const { 2246 if (Thread::is_lock_owned(adr)) return true; 2247 2248 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2249 if (chunk->contains(adr)) return true; 2250 } 2251 2252 return false; 2253 } 2254 2255 2256 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2257 chunk->set_next(monitor_chunks()); 2258 set_monitor_chunks(chunk); 2259 } 2260 2261 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2262 guarantee(monitor_chunks() != NULL, "must be non empty"); 2263 if (monitor_chunks() == chunk) { 2264 set_monitor_chunks(chunk->next()); 2265 } else { 2266 MonitorChunk* prev = monitor_chunks(); 2267 while (prev->next() != chunk) prev = prev->next(); 2268 prev->set_next(chunk->next()); 2269 } 2270 } 2271 2272 // JVM support. 2273 2274 // Note: this function shouldn't block if it's called in 2275 // _thread_in_native_trans state (such as from 2276 // check_special_condition_for_native_trans()). 2277 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2278 2279 if (has_last_Java_frame() && has_async_condition()) { 2280 // If we are at a polling page safepoint (not a poll return) 2281 // then we must defer async exception because live registers 2282 // will be clobbered by the exception path. Poll return is 2283 // ok because the call we a returning from already collides 2284 // with exception handling registers and so there is no issue. 2285 // (The exception handling path kills call result registers but 2286 // this is ok since the exception kills the result anyway). 2287 2288 if (is_at_poll_safepoint()) { 2289 // if the code we are returning to has deoptimized we must defer 2290 // the exception otherwise live registers get clobbered on the 2291 // exception path before deoptimization is able to retrieve them. 2292 // 2293 RegisterMap map(this, false); 2294 frame caller_fr = last_frame().sender(&map); 2295 assert(caller_fr.is_compiled_frame(), "what?"); 2296 if (caller_fr.is_deoptimized_frame()) { 2297 log_info(exceptions)("deferred async exception at compiled safepoint"); 2298 return; 2299 } 2300 } 2301 } 2302 2303 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2304 if (condition == _no_async_condition) { 2305 // Conditions have changed since has_special_runtime_exit_condition() 2306 // was called: 2307 // - if we were here only because of an external suspend request, 2308 // then that was taken care of above (or cancelled) so we are done 2309 // - if we were here because of another async request, then it has 2310 // been cleared between the has_special_runtime_exit_condition() 2311 // and now so again we are done 2312 return; 2313 } 2314 2315 // Check for pending async. exception 2316 if (_pending_async_exception != NULL) { 2317 // Only overwrite an already pending exception, if it is not a threadDeath. 2318 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2319 2320 // We cannot call Exceptions::_throw(...) here because we cannot block 2321 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2322 2323 LogTarget(Info, exceptions) lt; 2324 if (lt.is_enabled()) { 2325 ResourceMark rm; 2326 LogStream ls(lt); 2327 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2328 if (has_last_Java_frame()) { 2329 frame f = last_frame(); 2330 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2331 } 2332 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2333 } 2334 _pending_async_exception = NULL; 2335 clear_has_async_exception(); 2336 } 2337 } 2338 2339 if (check_unsafe_error && 2340 condition == _async_unsafe_access_error && !has_pending_exception()) { 2341 condition = _no_async_condition; // done 2342 switch (thread_state()) { 2343 case _thread_in_vm: { 2344 JavaThread* THREAD = this; 2345 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2346 } 2347 case _thread_in_native: { 2348 ThreadInVMfromNative tiv(this); 2349 JavaThread* THREAD = this; 2350 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2351 } 2352 case _thread_in_Java: { 2353 ThreadInVMfromJava tiv(this); 2354 JavaThread* THREAD = this; 2355 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2356 } 2357 default: 2358 ShouldNotReachHere(); 2359 } 2360 } 2361 2362 assert(condition == _no_async_condition || has_pending_exception() || 2363 (!check_unsafe_error && condition == _async_unsafe_access_error), 2364 "must have handled the async condition, if no exception"); 2365 } 2366 2367 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2368 2369 // Check for pending external suspend. 2370 if (is_external_suspend_with_lock()) { 2371 frame_anchor()->make_walkable(this); 2372 java_suspend_self_with_safepoint_check(); 2373 } 2374 2375 // We might be here for reasons in addition to the self-suspend request 2376 // so check for other async requests. 2377 if (check_asyncs) { 2378 check_and_handle_async_exceptions(); 2379 } 2380 2381 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2382 } 2383 2384 void JavaThread::send_thread_stop(oop java_throwable) { 2385 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2386 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2387 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2388 2389 // Do not throw asynchronous exceptions against the compiler thread 2390 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2391 if (!can_call_java()) return; 2392 2393 { 2394 // Actually throw the Throwable against the target Thread - however 2395 // only if there is no thread death exception installed already. 2396 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2397 // If the topmost frame is a runtime stub, then we are calling into 2398 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2399 // must deoptimize the caller before continuing, as the compiled exception handler table 2400 // may not be valid 2401 if (has_last_Java_frame()) { 2402 frame f = last_frame(); 2403 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2404 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2405 RegisterMap reg_map(this, UseBiasedLocking); 2406 frame compiled_frame = f.sender(®_map); 2407 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2408 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2409 } 2410 } 2411 } 2412 2413 // Set async. pending exception in thread. 2414 set_pending_async_exception(java_throwable); 2415 2416 if (log_is_enabled(Info, exceptions)) { 2417 ResourceMark rm; 2418 log_info(exceptions)("Pending Async. exception installed of type: %s", 2419 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2420 } 2421 // for AbortVMOnException flag 2422 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2423 } 2424 } 2425 2426 2427 // Interrupt thread so it will wake up from a potential wait()/sleep()/park() 2428 java_lang_Thread::set_interrupted(threadObj(), true); 2429 this->interrupt(); 2430 } 2431 2432 // External suspension mechanism. 2433 // 2434 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2435 // to any VM_locks and it is at a transition 2436 // Self-suspension will happen on the transition out of the vm. 2437 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2438 // 2439 // Guarantees on return: 2440 // + Target thread will not execute any new bytecode (that's why we need to 2441 // force a safepoint) 2442 // + Target thread will not enter any new monitors 2443 // 2444 void JavaThread::java_suspend() { 2445 ThreadsListHandle tlh; 2446 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2447 return; 2448 } 2449 2450 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2451 if (!is_external_suspend()) { 2452 // a racing resume has cancelled us; bail out now 2453 return; 2454 } 2455 2456 // suspend is done 2457 uint32_t debug_bits = 0; 2458 // Warning: is_ext_suspend_completed() may temporarily drop the 2459 // SR_lock to allow the thread to reach a stable thread state if 2460 // it is currently in a transient thread state. 2461 if (is_ext_suspend_completed(false /* !called_by_wait */, 2462 SuspendRetryDelay, &debug_bits)) { 2463 return; 2464 } 2465 } 2466 2467 if (Thread::current() == this) { 2468 // Safely self-suspend. 2469 // If we don't do this explicitly it will implicitly happen 2470 // before we transition back to Java, and on some other thread-state 2471 // transition paths, but not as we exit a JVM TI SuspendThread call. 2472 // As SuspendThread(current) must not return (until resumed) we must 2473 // self-suspend here. 2474 ThreadBlockInVM tbivm(this); 2475 java_suspend_self(); 2476 } else { 2477 VM_ThreadSuspend vm_suspend; 2478 VMThread::execute(&vm_suspend); 2479 } 2480 } 2481 2482 // Part II of external suspension. 2483 // A JavaThread self suspends when it detects a pending external suspend 2484 // request. This is usually on transitions. It is also done in places 2485 // where continuing to the next transition would surprise the caller, 2486 // e.g., monitor entry. 2487 // 2488 // Returns the number of times that the thread self-suspended. 2489 // 2490 // Note: DO NOT call java_suspend_self() when you just want to block current 2491 // thread. java_suspend_self() is the second stage of cooperative 2492 // suspension for external suspend requests and should only be used 2493 // to complete an external suspend request. 2494 // 2495 int JavaThread::java_suspend_self() { 2496 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2497 int ret = 0; 2498 2499 // we are in the process of exiting so don't suspend 2500 if (is_exiting()) { 2501 clear_external_suspend(); 2502 return ret; 2503 } 2504 2505 assert(_anchor.walkable() || 2506 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2507 "must have walkable stack"); 2508 2509 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2510 2511 assert(!this->is_ext_suspended(), 2512 "a thread trying to self-suspend should not already be suspended"); 2513 2514 if (this->is_suspend_equivalent()) { 2515 // If we are self-suspending as a result of the lifting of a 2516 // suspend equivalent condition, then the suspend_equivalent 2517 // flag is not cleared until we set the ext_suspended flag so 2518 // that wait_for_ext_suspend_completion() returns consistent 2519 // results. 2520 this->clear_suspend_equivalent(); 2521 } 2522 2523 // A racing resume may have cancelled us before we grabbed SR_lock 2524 // above. Or another external suspend request could be waiting for us 2525 // by the time we return from SR_lock()->wait(). The thread 2526 // that requested the suspension may already be trying to walk our 2527 // stack and if we return now, we can change the stack out from under 2528 // it. This would be a "bad thing (TM)" and cause the stack walker 2529 // to crash. We stay self-suspended until there are no more pending 2530 // external suspend requests. 2531 while (is_external_suspend()) { 2532 ret++; 2533 this->set_ext_suspended(); 2534 2535 // _ext_suspended flag is cleared by java_resume() 2536 while (is_ext_suspended()) { 2537 ml.wait(); 2538 } 2539 } 2540 return ret; 2541 } 2542 2543 // Helper routine to set up the correct thread state before calling java_suspend_self. 2544 // This is called when regular thread-state transition helpers can't be used because 2545 // we can be in various states, in particular _thread_in_native_trans. 2546 // Because this thread is external suspended the safepoint code will count it as at 2547 // a safepoint, regardless of what its actual current thread-state is. But 2548 // is_ext_suspend_completed() may be waiting to see a thread transition from 2549 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2550 // to _thread_blocked. The problem with setting thread state directly is that a 2551 // safepoint could happen just after java_suspend_self() returns after being resumed, 2552 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2553 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2554 // However, not all initial-states are allowed when performing a safepoint check, as we 2555 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2556 // only _thread_in_native is possible when executing this code (based on our two callers). 2557 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2558 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2559 // and so we don't need the explicit safepoint check. 2560 2561 void JavaThread::java_suspend_self_with_safepoint_check() { 2562 assert(this == Thread::current(), "invariant"); 2563 JavaThreadState state = thread_state(); 2564 set_thread_state(_thread_blocked); 2565 java_suspend_self(); 2566 set_thread_state_fence(state); 2567 // Since we are not using a regular thread-state transition helper here, 2568 // we must manually emit the instruction barrier after leaving a safe state. 2569 OrderAccess::cross_modify_fence(); 2570 if (state != _thread_in_native) { 2571 SafepointMechanism::block_if_requested(this); 2572 } 2573 } 2574 2575 #ifdef ASSERT 2576 // Verify the JavaThread has not yet been published in the Threads::list, and 2577 // hence doesn't need protection from concurrent access at this stage. 2578 void JavaThread::verify_not_published() { 2579 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2580 // since an unpublished JavaThread doesn't participate in the 2581 // Thread-SMR protocol for keeping a ThreadsList alive. 2582 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2583 } 2584 #endif 2585 2586 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2587 // progress or when _suspend_flags is non-zero. 2588 // Current thread needs to self-suspend if there is a suspend request and/or 2589 // block if a safepoint is in progress. 2590 // Async exception ISN'T checked. 2591 // Note only the ThreadInVMfromNative transition can call this function 2592 // directly and when thread state is _thread_in_native_trans 2593 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2594 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2595 2596 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2597 2598 if (thread->is_external_suspend()) { 2599 thread->java_suspend_self_with_safepoint_check(); 2600 } else { 2601 SafepointMechanism::block_if_requested(thread); 2602 } 2603 2604 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2605 } 2606 2607 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2608 // progress or when _suspend_flags is non-zero. 2609 // Current thread needs to self-suspend if there is a suspend request and/or 2610 // block if a safepoint is in progress. 2611 // Also check for pending async exception (not including unsafe access error). 2612 // Note only the native==>VM/Java barriers can call this function and when 2613 // thread state is _thread_in_native_trans. 2614 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2615 check_safepoint_and_suspend_for_native_trans(thread); 2616 2617 if (thread->has_async_exception()) { 2618 // We are in _thread_in_native_trans state, don't handle unsafe 2619 // access error since that may block. 2620 thread->check_and_handle_async_exceptions(false); 2621 } 2622 } 2623 2624 // This is a variant of the normal 2625 // check_special_condition_for_native_trans with slightly different 2626 // semantics for use by critical native wrappers. It does all the 2627 // normal checks but also performs the transition back into 2628 // thread_in_Java state. This is required so that critical natives 2629 // can potentially block and perform a GC if they are the last thread 2630 // exiting the GCLocker. 2631 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2632 check_special_condition_for_native_trans(thread); 2633 2634 // Finish the transition 2635 thread->set_thread_state(_thread_in_Java); 2636 2637 if (thread->do_critical_native_unlock()) { 2638 ThreadInVMfromJavaNoAsyncException tiv(thread); 2639 GCLocker::unlock_critical(thread); 2640 thread->clear_critical_native_unlock(); 2641 } 2642 } 2643 2644 // We need to guarantee the Threads_lock here, since resumes are not 2645 // allowed during safepoint synchronization 2646 // Can only resume from an external suspension 2647 void JavaThread::java_resume() { 2648 assert_locked_or_safepoint(Threads_lock); 2649 2650 // Sanity check: thread is gone, has started exiting or the thread 2651 // was not externally suspended. 2652 ThreadsListHandle tlh; 2653 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2654 return; 2655 } 2656 2657 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2658 2659 clear_external_suspend(); 2660 2661 if (is_ext_suspended()) { 2662 clear_ext_suspended(); 2663 SR_lock()->notify_all(); 2664 } 2665 } 2666 2667 size_t JavaThread::_stack_red_zone_size = 0; 2668 size_t JavaThread::_stack_yellow_zone_size = 0; 2669 size_t JavaThread::_stack_reserved_zone_size = 0; 2670 size_t JavaThread::_stack_shadow_zone_size = 0; 2671 2672 void JavaThread::create_stack_guard_pages() { 2673 if (!os::uses_stack_guard_pages() || 2674 _stack_guard_state != stack_guard_unused || 2675 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2676 log_info(os, thread)("Stack guard page creation for thread " 2677 UINTX_FORMAT " disabled", os::current_thread_id()); 2678 return; 2679 } 2680 address low_addr = stack_end(); 2681 size_t len = stack_guard_zone_size(); 2682 2683 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2684 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2685 2686 int must_commit = os::must_commit_stack_guard_pages(); 2687 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2688 2689 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2690 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2691 return; 2692 } 2693 2694 if (os::guard_memory((char *) low_addr, len)) { 2695 _stack_guard_state = stack_guard_enabled; 2696 } else { 2697 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2698 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2699 if (os::uncommit_memory((char *) low_addr, len)) { 2700 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2701 } 2702 return; 2703 } 2704 2705 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2706 PTR_FORMAT "-" PTR_FORMAT ".", 2707 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2708 } 2709 2710 void JavaThread::remove_stack_guard_pages() { 2711 assert(Thread::current() == this, "from different thread"); 2712 if (_stack_guard_state == stack_guard_unused) return; 2713 address low_addr = stack_end(); 2714 size_t len = stack_guard_zone_size(); 2715 2716 if (os::must_commit_stack_guard_pages()) { 2717 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2718 _stack_guard_state = stack_guard_unused; 2719 } else { 2720 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2721 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2722 return; 2723 } 2724 } else { 2725 if (_stack_guard_state == stack_guard_unused) return; 2726 if (os::unguard_memory((char *) low_addr, len)) { 2727 _stack_guard_state = stack_guard_unused; 2728 } else { 2729 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2730 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2731 return; 2732 } 2733 } 2734 2735 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2736 PTR_FORMAT "-" PTR_FORMAT ".", 2737 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2738 } 2739 2740 void JavaThread::enable_stack_reserved_zone() { 2741 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2742 2743 // The base notation is from the stack's point of view, growing downward. 2744 // We need to adjust it to work correctly with guard_memory() 2745 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2746 2747 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2748 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2749 2750 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2751 _stack_guard_state = stack_guard_enabled; 2752 } else { 2753 warning("Attempt to guard stack reserved zone failed."); 2754 } 2755 enable_register_stack_guard(); 2756 } 2757 2758 void JavaThread::disable_stack_reserved_zone() { 2759 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2760 2761 // Simply return if called for a thread that does not use guard pages. 2762 if (_stack_guard_state != stack_guard_enabled) return; 2763 2764 // The base notation is from the stack's point of view, growing downward. 2765 // We need to adjust it to work correctly with guard_memory() 2766 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2767 2768 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2769 _stack_guard_state = stack_guard_reserved_disabled; 2770 } else { 2771 warning("Attempt to unguard stack reserved zone failed."); 2772 } 2773 disable_register_stack_guard(); 2774 } 2775 2776 void JavaThread::enable_stack_yellow_reserved_zone() { 2777 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2778 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2779 2780 // The base notation is from the stacks point of view, growing downward. 2781 // We need to adjust it to work correctly with guard_memory() 2782 address base = stack_red_zone_base(); 2783 2784 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2785 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2786 2787 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2788 _stack_guard_state = stack_guard_enabled; 2789 } else { 2790 warning("Attempt to guard stack yellow zone failed."); 2791 } 2792 enable_register_stack_guard(); 2793 } 2794 2795 void JavaThread::disable_stack_yellow_reserved_zone() { 2796 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2797 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2798 2799 // Simply return if called for a thread that does not use guard pages. 2800 if (_stack_guard_state == stack_guard_unused) return; 2801 2802 // The base notation is from the stacks point of view, growing downward. 2803 // We need to adjust it to work correctly with guard_memory() 2804 address base = stack_red_zone_base(); 2805 2806 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2807 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2808 } else { 2809 warning("Attempt to unguard stack yellow zone failed."); 2810 } 2811 disable_register_stack_guard(); 2812 } 2813 2814 void JavaThread::enable_stack_red_zone() { 2815 // The base notation is from the stacks point of view, growing downward. 2816 // We need to adjust it to work correctly with guard_memory() 2817 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2818 address base = stack_red_zone_base() - stack_red_zone_size(); 2819 2820 guarantee(base < stack_base(), "Error calculating stack red zone"); 2821 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2822 2823 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2824 warning("Attempt to guard stack red zone failed."); 2825 } 2826 } 2827 2828 void JavaThread::disable_stack_red_zone() { 2829 // The base notation is from the stacks point of view, growing downward. 2830 // We need to adjust it to work correctly with guard_memory() 2831 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2832 address base = stack_red_zone_base() - stack_red_zone_size(); 2833 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2834 warning("Attempt to unguard stack red zone failed."); 2835 } 2836 } 2837 2838 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2839 // ignore is there is no stack 2840 if (!has_last_Java_frame()) return; 2841 // traverse the stack frames. Starts from top frame. 2842 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2843 frame* fr = fst.current(); 2844 f(fr, fst.register_map()); 2845 } 2846 } 2847 2848 2849 #ifndef PRODUCT 2850 // Deoptimization 2851 // Function for testing deoptimization 2852 void JavaThread::deoptimize() { 2853 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2854 StackFrameStream fst(this, UseBiasedLocking); 2855 bool deopt = false; // Dump stack only if a deopt actually happens. 2856 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2857 // Iterate over all frames in the thread and deoptimize 2858 for (; !fst.is_done(); fst.next()) { 2859 if (fst.current()->can_be_deoptimized()) { 2860 2861 if (only_at) { 2862 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2863 // consists of comma or carriage return separated numbers so 2864 // search for the current bci in that string. 2865 address pc = fst.current()->pc(); 2866 nmethod* nm = (nmethod*) fst.current()->cb(); 2867 ScopeDesc* sd = nm->scope_desc_at(pc); 2868 char buffer[8]; 2869 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2870 size_t len = strlen(buffer); 2871 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2872 while (found != NULL) { 2873 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2874 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2875 // Check that the bci found is bracketed by terminators. 2876 break; 2877 } 2878 found = strstr(found + 1, buffer); 2879 } 2880 if (!found) { 2881 continue; 2882 } 2883 } 2884 2885 if (DebugDeoptimization && !deopt) { 2886 deopt = true; // One-time only print before deopt 2887 tty->print_cr("[BEFORE Deoptimization]"); 2888 trace_frames(); 2889 trace_stack(); 2890 } 2891 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2892 } 2893 } 2894 2895 if (DebugDeoptimization && deopt) { 2896 tty->print_cr("[AFTER Deoptimization]"); 2897 trace_frames(); 2898 } 2899 } 2900 2901 2902 // Make zombies 2903 void JavaThread::make_zombies() { 2904 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2905 if (fst.current()->can_be_deoptimized()) { 2906 // it is a Java nmethod 2907 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2908 nm->make_not_entrant(); 2909 } 2910 } 2911 } 2912 #endif // PRODUCT 2913 2914 2915 void JavaThread::deoptimize_marked_methods() { 2916 if (!has_last_Java_frame()) return; 2917 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2918 StackFrameStream fst(this, UseBiasedLocking); 2919 for (; !fst.is_done(); fst.next()) { 2920 if (fst.current()->should_be_deoptimized()) { 2921 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2922 } 2923 } 2924 } 2925 2926 // If the caller is a NamedThread, then remember, in the current scope, 2927 // the given JavaThread in its _processed_thread field. 2928 class RememberProcessedThread: public StackObj { 2929 NamedThread* _cur_thr; 2930 public: 2931 RememberProcessedThread(JavaThread* jthr) { 2932 Thread* thread = Thread::current(); 2933 if (thread->is_Named_thread()) { 2934 _cur_thr = (NamedThread *)thread; 2935 _cur_thr->set_processed_thread(jthr); 2936 } else { 2937 _cur_thr = NULL; 2938 } 2939 } 2940 2941 ~RememberProcessedThread() { 2942 if (_cur_thr) { 2943 _cur_thr->set_processed_thread(NULL); 2944 } 2945 } 2946 }; 2947 2948 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2949 // Verify that the deferred card marks have been flushed. 2950 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2951 2952 // Traverse the GCHandles 2953 Thread::oops_do(f, cf); 2954 2955 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2956 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2957 2958 if (has_last_Java_frame()) { 2959 // Record JavaThread to GC thread 2960 RememberProcessedThread rpt(this); 2961 2962 // traverse the registered growable array 2963 if (_array_for_gc != NULL) { 2964 for (int index = 0; index < _array_for_gc->length(); index++) { 2965 f->do_oop(_array_for_gc->adr_at(index)); 2966 } 2967 } 2968 2969 // Traverse the monitor chunks 2970 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2971 chunk->oops_do(f); 2972 } 2973 2974 // Traverse the execution stack 2975 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2976 fst.current()->oops_do(f, cf, fst.register_map()); 2977 } 2978 } 2979 2980 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2981 // If we have deferred set_locals there might be oops waiting to be 2982 // written 2983 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2984 if (list != NULL) { 2985 for (int i = 0; i < list->length(); i++) { 2986 list->at(i)->oops_do(f); 2987 } 2988 } 2989 2990 // Traverse instance variables at the end since the GC may be moving things 2991 // around using this function 2992 f->do_oop((oop*) &_threadObj); 2993 f->do_oop((oop*) &_vm_result); 2994 f->do_oop((oop*) &_exception_oop); 2995 f->do_oop((oop*) &_pending_async_exception); 2996 2997 if (jvmti_thread_state() != NULL) { 2998 jvmti_thread_state()->oops_do(f); 2999 } 3000 } 3001 3002 #ifdef ASSERT 3003 void JavaThread::verify_states_for_handshake() { 3004 // This checks that the thread has a correct frame state during a handshake. 3005 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3006 (has_last_Java_frame() && java_call_counter() > 0), 3007 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3008 has_last_Java_frame(), java_call_counter()); 3009 } 3010 #endif 3011 3012 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 3013 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3014 (has_last_Java_frame() && java_call_counter() > 0), 3015 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3016 has_last_Java_frame(), java_call_counter()); 3017 3018 if (has_last_Java_frame()) { 3019 // Traverse the execution stack 3020 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3021 fst.current()->nmethods_do(cf); 3022 } 3023 } 3024 } 3025 3026 void JavaThread::metadata_do(MetadataClosure* f) { 3027 if (has_last_Java_frame()) { 3028 // Traverse the execution stack to call f() on the methods in the stack 3029 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3030 fst.current()->metadata_do(f); 3031 } 3032 } else if (is_Compiler_thread()) { 3033 // need to walk ciMetadata in current compile tasks to keep alive. 3034 CompilerThread* ct = (CompilerThread*)this; 3035 if (ct->env() != NULL) { 3036 ct->env()->metadata_do(f); 3037 } 3038 CompileTask* task = ct->task(); 3039 if (task != NULL) { 3040 task->metadata_do(f); 3041 } 3042 } 3043 } 3044 3045 // Printing 3046 const char* _get_thread_state_name(JavaThreadState _thread_state) { 3047 switch (_thread_state) { 3048 case _thread_uninitialized: return "_thread_uninitialized"; 3049 case _thread_new: return "_thread_new"; 3050 case _thread_new_trans: return "_thread_new_trans"; 3051 case _thread_in_native: return "_thread_in_native"; 3052 case _thread_in_native_trans: return "_thread_in_native_trans"; 3053 case _thread_in_vm: return "_thread_in_vm"; 3054 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3055 case _thread_in_Java: return "_thread_in_Java"; 3056 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3057 case _thread_blocked: return "_thread_blocked"; 3058 case _thread_blocked_trans: return "_thread_blocked_trans"; 3059 default: return "unknown thread state"; 3060 } 3061 } 3062 3063 #ifndef PRODUCT 3064 void JavaThread::print_thread_state_on(outputStream *st) const { 3065 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3066 }; 3067 #endif // PRODUCT 3068 3069 // Called by Threads::print() for VM_PrintThreads operation 3070 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3071 st->print_raw("\""); 3072 st->print_raw(get_thread_name()); 3073 st->print_raw("\" "); 3074 oop thread_oop = threadObj(); 3075 if (thread_oop != NULL) { 3076 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3077 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3078 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3079 } 3080 Thread::print_on(st, print_extended_info); 3081 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3082 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3083 if (thread_oop != NULL) { 3084 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3085 } 3086 #ifndef PRODUCT 3087 _safepoint_state->print_on(st); 3088 #endif // PRODUCT 3089 if (is_Compiler_thread()) { 3090 CompileTask *task = ((CompilerThread*)this)->task(); 3091 if (task != NULL) { 3092 st->print(" Compiling: "); 3093 task->print(st, NULL, true, false); 3094 } else { 3095 st->print(" No compile task"); 3096 } 3097 st->cr(); 3098 } 3099 } 3100 3101 void JavaThread::print() const { print_on(tty); } 3102 3103 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3104 st->print("%s", get_thread_name_string(buf, buflen)); 3105 } 3106 3107 // Called by fatal error handler. The difference between this and 3108 // JavaThread::print() is that we can't grab lock or allocate memory. 3109 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3110 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3111 oop thread_obj = threadObj(); 3112 if (thread_obj != NULL) { 3113 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3114 } 3115 st->print(" ["); 3116 st->print("%s", _get_thread_state_name(_thread_state)); 3117 if (osthread()) { 3118 st->print(", id=%d", osthread()->thread_id()); 3119 } 3120 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3121 p2i(stack_end()), p2i(stack_base())); 3122 st->print("]"); 3123 3124 ThreadsSMRSupport::print_info_on(this, st); 3125 return; 3126 } 3127 3128 // Verification 3129 3130 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3131 3132 void JavaThread::verify() { 3133 // Verify oops in the thread. 3134 oops_do(&VerifyOopClosure::verify_oop, NULL); 3135 3136 // Verify the stack frames. 3137 frames_do(frame_verify); 3138 } 3139 3140 // CR 6300358 (sub-CR 2137150) 3141 // Most callers of this method assume that it can't return NULL but a 3142 // thread may not have a name whilst it is in the process of attaching to 3143 // the VM - see CR 6412693, and there are places where a JavaThread can be 3144 // seen prior to having it's threadObj set (eg JNI attaching threads and 3145 // if vm exit occurs during initialization). These cases can all be accounted 3146 // for such that this method never returns NULL. 3147 const char* JavaThread::get_thread_name() const { 3148 #ifdef ASSERT 3149 // early safepoints can hit while current thread does not yet have TLS 3150 if (!SafepointSynchronize::is_at_safepoint()) { 3151 Thread *cur = Thread::current(); 3152 if (!(cur->is_Java_thread() && cur == this)) { 3153 // Current JavaThreads are allowed to get their own name without 3154 // the Threads_lock. 3155 assert_locked_or_safepoint(Threads_lock); 3156 } 3157 } 3158 #endif // ASSERT 3159 return get_thread_name_string(); 3160 } 3161 3162 // Returns a non-NULL representation of this thread's name, or a suitable 3163 // descriptive string if there is no set name 3164 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3165 const char* name_str; 3166 oop thread_obj = threadObj(); 3167 if (thread_obj != NULL) { 3168 oop name = java_lang_Thread::name(thread_obj); 3169 if (name != NULL) { 3170 if (buf == NULL) { 3171 name_str = java_lang_String::as_utf8_string(name); 3172 } else { 3173 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3174 } 3175 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3176 name_str = "<no-name - thread is attaching>"; 3177 } else { 3178 name_str = Thread::name(); 3179 } 3180 } else { 3181 name_str = Thread::name(); 3182 } 3183 assert(name_str != NULL, "unexpected NULL thread name"); 3184 return name_str; 3185 } 3186 3187 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3188 3189 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3190 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3191 // Link Java Thread object <-> C++ Thread 3192 3193 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3194 // and put it into a new Handle. The Handle "thread_oop" can then 3195 // be used to pass the C++ thread object to other methods. 3196 3197 // Set the Java level thread object (jthread) field of the 3198 // new thread (a JavaThread *) to C++ thread object using the 3199 // "thread_oop" handle. 3200 3201 // Set the thread field (a JavaThread *) of the 3202 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3203 3204 Handle thread_oop(Thread::current(), 3205 JNIHandles::resolve_non_null(jni_thread)); 3206 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3207 "must be initialized"); 3208 set_threadObj(thread_oop()); 3209 java_lang_Thread::set_thread(thread_oop(), this); 3210 3211 if (prio == NoPriority) { 3212 prio = java_lang_Thread::priority(thread_oop()); 3213 assert(prio != NoPriority, "A valid priority should be present"); 3214 } 3215 3216 // Push the Java priority down to the native thread; needs Threads_lock 3217 Thread::set_priority(this, prio); 3218 3219 // Add the new thread to the Threads list and set it in motion. 3220 // We must have threads lock in order to call Threads::add. 3221 // It is crucial that we do not block before the thread is 3222 // added to the Threads list for if a GC happens, then the java_thread oop 3223 // will not be visited by GC. 3224 Threads::add(this); 3225 } 3226 3227 oop JavaThread::current_park_blocker() { 3228 // Support for JSR-166 locks 3229 oop thread_oop = threadObj(); 3230 if (thread_oop != NULL) { 3231 return java_lang_Thread::park_blocker(thread_oop); 3232 } 3233 return NULL; 3234 } 3235 3236 3237 void JavaThread::print_stack_on(outputStream* st) { 3238 if (!has_last_Java_frame()) return; 3239 ResourceMark rm; 3240 HandleMark hm; 3241 3242 RegisterMap reg_map(this); 3243 vframe* start_vf = last_java_vframe(®_map); 3244 int count = 0; 3245 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3246 if (f->is_java_frame()) { 3247 javaVFrame* jvf = javaVFrame::cast(f); 3248 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3249 3250 // Print out lock information 3251 if (JavaMonitorsInStackTrace) { 3252 jvf->print_lock_info_on(st, count); 3253 } 3254 } else { 3255 // Ignore non-Java frames 3256 } 3257 3258 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3259 count++; 3260 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3261 } 3262 } 3263 3264 3265 // JVMTI PopFrame support 3266 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3267 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3268 if (in_bytes(size_in_bytes) != 0) { 3269 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3270 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3271 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3272 } 3273 } 3274 3275 void* JavaThread::popframe_preserved_args() { 3276 return _popframe_preserved_args; 3277 } 3278 3279 ByteSize JavaThread::popframe_preserved_args_size() { 3280 return in_ByteSize(_popframe_preserved_args_size); 3281 } 3282 3283 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3284 int sz = in_bytes(popframe_preserved_args_size()); 3285 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3286 return in_WordSize(sz / wordSize); 3287 } 3288 3289 void JavaThread::popframe_free_preserved_args() { 3290 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3291 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args); 3292 _popframe_preserved_args = NULL; 3293 _popframe_preserved_args_size = 0; 3294 } 3295 3296 #ifndef PRODUCT 3297 3298 void JavaThread::trace_frames() { 3299 tty->print_cr("[Describe stack]"); 3300 int frame_no = 1; 3301 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3302 tty->print(" %d. ", frame_no++); 3303 fst.current()->print_value_on(tty, this); 3304 tty->cr(); 3305 } 3306 } 3307 3308 class PrintAndVerifyOopClosure: public OopClosure { 3309 protected: 3310 template <class T> inline void do_oop_work(T* p) { 3311 oop obj = RawAccess<>::oop_load(p); 3312 if (obj == NULL) return; 3313 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3314 if (oopDesc::is_oop_or_null(obj)) { 3315 if (obj->is_objArray()) { 3316 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3317 } else { 3318 obj->print(); 3319 } 3320 } else { 3321 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3322 } 3323 tty->cr(); 3324 } 3325 public: 3326 virtual void do_oop(oop* p) { do_oop_work(p); } 3327 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3328 }; 3329 3330 #ifdef ASSERT 3331 // Print or validate the layout of stack frames 3332 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3333 ResourceMark rm; 3334 PRESERVE_EXCEPTION_MARK; 3335 FrameValues values; 3336 int frame_no = 0; 3337 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3338 fst.current()->describe(values, ++frame_no); 3339 if (depth == frame_no) break; 3340 } 3341 if (validate_only) { 3342 values.validate(); 3343 } else { 3344 tty->print_cr("[Describe stack layout]"); 3345 values.print(this); 3346 } 3347 } 3348 #endif 3349 3350 void JavaThread::trace_stack_from(vframe* start_vf) { 3351 ResourceMark rm; 3352 int vframe_no = 1; 3353 for (vframe* f = start_vf; f; f = f->sender()) { 3354 if (f->is_java_frame()) { 3355 javaVFrame::cast(f)->print_activation(vframe_no++); 3356 } else { 3357 f->print(); 3358 } 3359 if (vframe_no > StackPrintLimit) { 3360 tty->print_cr("...<more frames>..."); 3361 return; 3362 } 3363 } 3364 } 3365 3366 3367 void JavaThread::trace_stack() { 3368 if (!has_last_Java_frame()) return; 3369 ResourceMark rm; 3370 HandleMark hm; 3371 RegisterMap reg_map(this); 3372 trace_stack_from(last_java_vframe(®_map)); 3373 } 3374 3375 3376 #endif // PRODUCT 3377 3378 3379 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3380 assert(reg_map != NULL, "a map must be given"); 3381 frame f = last_frame(); 3382 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3383 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3384 } 3385 return NULL; 3386 } 3387 3388 3389 Klass* JavaThread::security_get_caller_class(int depth) { 3390 vframeStream vfst(this); 3391 vfst.security_get_caller_frame(depth); 3392 if (!vfst.at_end()) { 3393 return vfst.method()->method_holder(); 3394 } 3395 return NULL; 3396 } 3397 3398 // java.lang.Thread.sleep support 3399 // Returns true if sleep time elapsed as expected, and false 3400 // if the thread was interrupted. 3401 bool JavaThread::sleep(jlong millis) { 3402 assert(this == Thread::current(), "thread consistency check"); 3403 3404 ParkEvent * const slp = this->_SleepEvent; 3405 // Because there can be races with thread interruption sending an unpark() 3406 // to the event, we explicitly reset it here to avoid an immediate return. 3407 // The actual interrupt state will be checked before we park(). 3408 slp->reset(); 3409 // Thread interruption establishes a happens-before ordering in the 3410 // Java Memory Model, so we need to ensure we synchronize with the 3411 // interrupt state. 3412 OrderAccess::fence(); 3413 3414 jlong prevtime = os::javaTimeNanos(); 3415 3416 for (;;) { 3417 // interruption has precedence over timing out 3418 if (this->is_interrupted(true)) { 3419 return false; 3420 } 3421 3422 if (millis <= 0) { 3423 return true; 3424 } 3425 3426 { 3427 ThreadBlockInVM tbivm(this); 3428 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 3429 3430 this->set_suspend_equivalent(); 3431 // cleared by handle_special_suspend_equivalent_condition() or 3432 // java_suspend_self() via check_and_wait_while_suspended() 3433 3434 slp->park(millis); 3435 3436 // were we externally suspended while we were waiting? 3437 this->check_and_wait_while_suspended(); 3438 } 3439 3440 // Update elapsed time tracking 3441 jlong newtime = os::javaTimeNanos(); 3442 if (newtime - prevtime < 0) { 3443 // time moving backwards, should only happen if no monotonic clock 3444 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3445 assert(!os::supports_monotonic_clock(), 3446 "unexpected time moving backwards detected in JavaThread::sleep()"); 3447 } else { 3448 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3449 } 3450 prevtime = newtime; 3451 } 3452 } 3453 3454 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3455 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3456 CompileBroker::compiler_thread_loop(); 3457 } 3458 3459 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3460 NMethodSweeper::sweeper_loop(); 3461 } 3462 3463 // Create a CompilerThread 3464 CompilerThread::CompilerThread(CompileQueue* queue, 3465 CompilerCounters* counters) 3466 : JavaThread(&compiler_thread_entry) { 3467 _env = NULL; 3468 _log = NULL; 3469 _task = NULL; 3470 _queue = queue; 3471 _counters = counters; 3472 _buffer_blob = NULL; 3473 _compiler = NULL; 3474 3475 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3476 resource_area()->bias_to(mtCompiler); 3477 3478 #ifndef PRODUCT 3479 _ideal_graph_printer = NULL; 3480 #endif 3481 } 3482 3483 CompilerThread::~CompilerThread() { 3484 // Delete objects which were allocated on heap. 3485 delete _counters; 3486 } 3487 3488 bool CompilerThread::can_call_java() const { 3489 return _compiler != NULL && _compiler->is_jvmci(); 3490 } 3491 3492 // Create sweeper thread 3493 CodeCacheSweeperThread::CodeCacheSweeperThread() 3494 : JavaThread(&sweeper_thread_entry) { 3495 _scanned_compiled_method = NULL; 3496 } 3497 3498 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3499 JavaThread::oops_do(f, cf); 3500 if (_scanned_compiled_method != NULL && cf != NULL) { 3501 // Safepoints can occur when the sweeper is scanning an nmethod so 3502 // process it here to make sure it isn't unloaded in the middle of 3503 // a scan. 3504 cf->do_code_blob(_scanned_compiled_method); 3505 } 3506 } 3507 3508 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3509 JavaThread::nmethods_do(cf); 3510 if (_scanned_compiled_method != NULL && cf != NULL) { 3511 // Safepoints can occur when the sweeper is scanning an nmethod so 3512 // process it here to make sure it isn't unloaded in the middle of 3513 // a scan. 3514 cf->do_code_blob(_scanned_compiled_method); 3515 } 3516 } 3517 3518 3519 // ======= Threads ======== 3520 3521 // The Threads class links together all active threads, and provides 3522 // operations over all threads. It is protected by the Threads_lock, 3523 // which is also used in other global contexts like safepointing. 3524 // ThreadsListHandles are used to safely perform operations on one 3525 // or more threads without the risk of the thread exiting during the 3526 // operation. 3527 // 3528 // Note: The Threads_lock is currently more widely used than we 3529 // would like. We are actively migrating Threads_lock uses to other 3530 // mechanisms in order to reduce Threads_lock contention. 3531 3532 int Threads::_number_of_threads = 0; 3533 int Threads::_number_of_non_daemon_threads = 0; 3534 int Threads::_return_code = 0; 3535 uintx Threads::_thread_claim_token = 1; // Never zero. 3536 size_t JavaThread::_stack_size_at_create = 0; 3537 3538 #ifdef ASSERT 3539 bool Threads::_vm_complete = false; 3540 #endif 3541 3542 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3543 Prefetch::read((void*)addr, prefetch_interval); 3544 return *addr; 3545 } 3546 3547 // Possibly the ugliest for loop the world has seen. C++ does not allow 3548 // multiple types in the declaration section of the for loop. In this case 3549 // we are only dealing with pointers and hence can cast them. It looks ugly 3550 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3551 #define DO_JAVA_THREADS(LIST, X) \ 3552 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3553 *MACRO_list = (JavaThread*)(LIST), \ 3554 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3555 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3556 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3557 MACRO_current_p != MACRO_end; \ 3558 MACRO_current_p++, \ 3559 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3560 3561 // All JavaThreads 3562 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3563 3564 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3565 void Threads::non_java_threads_do(ThreadClosure* tc) { 3566 NoSafepointVerifier nsv; 3567 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3568 tc->do_thread(njti.current()); 3569 } 3570 } 3571 3572 // All JavaThreads 3573 void Threads::java_threads_do(ThreadClosure* tc) { 3574 assert_locked_or_safepoint(Threads_lock); 3575 // ALL_JAVA_THREADS iterates through all JavaThreads. 3576 ALL_JAVA_THREADS(p) { 3577 tc->do_thread(p); 3578 } 3579 } 3580 3581 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3582 assert_locked_or_safepoint(Threads_lock); 3583 java_threads_do(tc); 3584 tc->do_thread(VMThread::vm_thread()); 3585 } 3586 3587 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3588 void Threads::threads_do(ThreadClosure* tc) { 3589 assert_locked_or_safepoint(Threads_lock); 3590 java_threads_do(tc); 3591 non_java_threads_do(tc); 3592 } 3593 3594 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3595 uintx claim_token = Threads::thread_claim_token(); 3596 ALL_JAVA_THREADS(p) { 3597 if (p->claim_threads_do(is_par, claim_token)) { 3598 tc->do_thread(p); 3599 } 3600 } 3601 VMThread* vmt = VMThread::vm_thread(); 3602 if (vmt->claim_threads_do(is_par, claim_token)) { 3603 tc->do_thread(vmt); 3604 } 3605 } 3606 3607 // The system initialization in the library has three phases. 3608 // 3609 // Phase 1: java.lang.System class initialization 3610 // java.lang.System is a primordial class loaded and initialized 3611 // by the VM early during startup. java.lang.System.<clinit> 3612 // only does registerNatives and keeps the rest of the class 3613 // initialization work later until thread initialization completes. 3614 // 3615 // System.initPhase1 initializes the system properties, the static 3616 // fields in, out, and err. Set up java signal handlers, OS-specific 3617 // system settings, and thread group of the main thread. 3618 static void call_initPhase1(TRAPS) { 3619 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3620 JavaValue result(T_VOID); 3621 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3622 vmSymbols::void_method_signature(), CHECK); 3623 } 3624 3625 // Phase 2. Module system initialization 3626 // This will initialize the module system. Only java.base classes 3627 // can be loaded until phase 2 completes. 3628 // 3629 // Call System.initPhase2 after the compiler initialization and jsr292 3630 // classes get initialized because module initialization runs a lot of java 3631 // code, that for performance reasons, should be compiled. Also, this will 3632 // enable the startup code to use lambda and other language features in this 3633 // phase and onward. 3634 // 3635 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3636 static void call_initPhase2(TRAPS) { 3637 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3638 3639 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3640 3641 JavaValue result(T_INT); 3642 JavaCallArguments args; 3643 args.push_int(DisplayVMOutputToStderr); 3644 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3645 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3646 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3647 if (result.get_jint() != JNI_OK) { 3648 vm_exit_during_initialization(); // no message or exception 3649 } 3650 3651 universe_post_module_init(); 3652 } 3653 3654 // Phase 3. final setup - set security manager, system class loader and TCCL 3655 // 3656 // This will instantiate and set the security manager, set the system class 3657 // loader as well as the thread context class loader. The security manager 3658 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3659 // other modules or the application's classpath. 3660 static void call_initPhase3(TRAPS) { 3661 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3662 JavaValue result(T_VOID); 3663 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3664 vmSymbols::void_method_signature(), CHECK); 3665 } 3666 3667 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3668 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3669 3670 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3671 create_vm_init_libraries(); 3672 } 3673 3674 initialize_class(vmSymbols::java_lang_String(), CHECK); 3675 3676 // Inject CompactStrings value after the static initializers for String ran. 3677 java_lang_String::set_compact_strings(CompactStrings); 3678 3679 // Initialize java_lang.System (needed before creating the thread) 3680 initialize_class(vmSymbols::java_lang_System(), CHECK); 3681 // The VM creates & returns objects of this class. Make sure it's initialized. 3682 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3683 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3684 Handle thread_group = create_initial_thread_group(CHECK); 3685 Universe::set_main_thread_group(thread_group()); 3686 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3687 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3688 main_thread->set_threadObj(thread_object); 3689 3690 // Set thread status to running since main thread has 3691 // been started and running. 3692 java_lang_Thread::set_thread_status(thread_object, 3693 java_lang_Thread::RUNNABLE); 3694 3695 // The VM creates objects of this class. 3696 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3697 3698 #ifdef ASSERT 3699 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3700 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3701 #endif 3702 3703 // initialize the hardware-specific constants needed by Unsafe 3704 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3705 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3706 3707 // The VM preresolves methods to these classes. Make sure that they get initialized 3708 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3709 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3710 3711 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3712 call_initPhase1(CHECK); 3713 3714 // get the Java runtime name, version, and vendor info after java.lang.System is initialized 3715 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3716 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3717 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD)); 3718 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD)); 3719 3720 // an instance of OutOfMemory exception has been allocated earlier 3721 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3722 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3723 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3724 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3725 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3726 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3727 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3728 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3729 3730 // Eager box cache initialization only if AOT is on and any library is loaded. 3731 AOTLoader::initialize_box_caches(CHECK); 3732 } 3733 3734 void Threads::initialize_jsr292_core_classes(TRAPS) { 3735 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3736 3737 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3738 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3739 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3740 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3741 } 3742 3743 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3744 extern void JDK_Version_init(); 3745 3746 // Preinitialize version info. 3747 VM_Version::early_initialize(); 3748 3749 // Check version 3750 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3751 3752 // Initialize library-based TLS 3753 ThreadLocalStorage::init(); 3754 3755 // Initialize the output stream module 3756 ostream_init(); 3757 3758 // Process java launcher properties. 3759 Arguments::process_sun_java_launcher_properties(args); 3760 3761 // Initialize the os module 3762 os::init(); 3763 3764 // Record VM creation timing statistics 3765 TraceVmCreationTime create_vm_timer; 3766 create_vm_timer.start(); 3767 3768 // Initialize system properties. 3769 Arguments::init_system_properties(); 3770 3771 // So that JDK version can be used as a discriminator when parsing arguments 3772 JDK_Version_init(); 3773 3774 // Update/Initialize System properties after JDK version number is known 3775 Arguments::init_version_specific_system_properties(); 3776 3777 // Make sure to initialize log configuration *before* parsing arguments 3778 LogConfiguration::initialize(create_vm_timer.begin_time()); 3779 3780 // Parse arguments 3781 // Note: this internally calls os::init_container_support() 3782 jint parse_result = Arguments::parse(args); 3783 if (parse_result != JNI_OK) return parse_result; 3784 3785 os::init_before_ergo(); 3786 3787 jint ergo_result = Arguments::apply_ergo(); 3788 if (ergo_result != JNI_OK) return ergo_result; 3789 3790 // Final check of all ranges after ergonomics which may change values. 3791 if (!JVMFlagRangeList::check_ranges()) { 3792 return JNI_EINVAL; 3793 } 3794 3795 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3796 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3797 if (!constraint_result) { 3798 return JNI_EINVAL; 3799 } 3800 3801 JVMFlagWriteableList::mark_startup(); 3802 3803 if (PauseAtStartup) { 3804 os::pause(); 3805 } 3806 3807 HOTSPOT_VM_INIT_BEGIN(); 3808 3809 // Timing (must come after argument parsing) 3810 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3811 3812 // Initialize the os module after parsing the args 3813 jint os_init_2_result = os::init_2(); 3814 if (os_init_2_result != JNI_OK) return os_init_2_result; 3815 3816 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3817 // Initialize assert poison page mechanism. 3818 if (ShowRegistersOnAssert) { 3819 initialize_assert_poison(); 3820 } 3821 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3822 3823 SafepointMechanism::initialize(); 3824 3825 jint adjust_after_os_result = Arguments::adjust_after_os(); 3826 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3827 3828 // Initialize output stream logging 3829 ostream_init_log(); 3830 3831 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3832 // Must be before create_vm_init_agents() 3833 if (Arguments::init_libraries_at_startup()) { 3834 convert_vm_init_libraries_to_agents(); 3835 } 3836 3837 // Launch -agentlib/-agentpath and converted -Xrun agents 3838 if (Arguments::init_agents_at_startup()) { 3839 create_vm_init_agents(); 3840 } 3841 3842 // Initialize Threads state 3843 _number_of_threads = 0; 3844 _number_of_non_daemon_threads = 0; 3845 3846 // Initialize global data structures and create system classes in heap 3847 vm_init_globals(); 3848 3849 #if INCLUDE_JVMCI 3850 if (JVMCICounterSize > 0) { 3851 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3852 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3853 } else { 3854 JavaThread::_jvmci_old_thread_counters = NULL; 3855 } 3856 #endif // INCLUDE_JVMCI 3857 3858 // Attach the main thread to this os thread 3859 JavaThread* main_thread = new JavaThread(); 3860 main_thread->set_thread_state(_thread_in_vm); 3861 main_thread->initialize_thread_current(); 3862 // must do this before set_active_handles 3863 main_thread->record_stack_base_and_size(); 3864 main_thread->register_thread_stack_with_NMT(); 3865 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3866 3867 if (!main_thread->set_as_starting_thread()) { 3868 vm_shutdown_during_initialization( 3869 "Failed necessary internal allocation. Out of swap space"); 3870 main_thread->smr_delete(); 3871 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3872 return JNI_ENOMEM; 3873 } 3874 3875 // Enable guard page *after* os::create_main_thread(), otherwise it would 3876 // crash Linux VM, see notes in os_linux.cpp. 3877 main_thread->create_stack_guard_pages(); 3878 3879 // Initialize Java-Level synchronization subsystem 3880 ObjectMonitor::Initialize(); 3881 3882 // Initialize global modules 3883 jint status = init_globals(); 3884 if (status != JNI_OK) { 3885 main_thread->smr_delete(); 3886 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3887 return status; 3888 } 3889 3890 JFR_ONLY(Jfr::on_create_vm_1();) 3891 3892 // Should be done after the heap is fully created 3893 main_thread->cache_global_variables(); 3894 3895 HandleMark hm; 3896 3897 { MutexLocker mu(Threads_lock); 3898 Threads::add(main_thread); 3899 } 3900 3901 // Any JVMTI raw monitors entered in onload will transition into 3902 // real raw monitor. VM is setup enough here for raw monitor enter. 3903 JvmtiExport::transition_pending_onload_raw_monitors(); 3904 3905 // Create the VMThread 3906 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3907 3908 VMThread::create(); 3909 Thread* vmthread = VMThread::vm_thread(); 3910 3911 if (!os::create_thread(vmthread, os::vm_thread)) { 3912 vm_exit_during_initialization("Cannot create VM thread. " 3913 "Out of system resources."); 3914 } 3915 3916 // Wait for the VM thread to become ready, and VMThread::run to initialize 3917 // Monitors can have spurious returns, must always check another state flag 3918 { 3919 MonitorLocker ml(Notify_lock); 3920 os::start_thread(vmthread); 3921 while (vmthread->active_handles() == NULL) { 3922 ml.wait(); 3923 } 3924 } 3925 } 3926 3927 assert(Universe::is_fully_initialized(), "not initialized"); 3928 if (VerifyDuringStartup) { 3929 // Make sure we're starting with a clean slate. 3930 VM_Verify verify_op; 3931 VMThread::execute(&verify_op); 3932 } 3933 3934 // We need this to update the java.vm.info property in case any flags used 3935 // to initially define it have been changed. This is needed for both CDS and 3936 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3937 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3938 // This update must happen before we initialize the java classes, but 3939 // after any initialization logic that might modify the flags. 3940 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3941 3942 Thread* THREAD = Thread::current(); 3943 3944 // Always call even when there are not JVMTI environments yet, since environments 3945 // may be attached late and JVMTI must track phases of VM execution 3946 JvmtiExport::enter_early_start_phase(); 3947 3948 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3949 JvmtiExport::post_early_vm_start(); 3950 3951 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3952 3953 quicken_jni_functions(); 3954 3955 // No more stub generation allowed after that point. 3956 StubCodeDesc::freeze(); 3957 3958 // Set flag that basic initialization has completed. Used by exceptions and various 3959 // debug stuff, that does not work until all basic classes have been initialized. 3960 set_init_completed(); 3961 3962 LogConfiguration::post_initialize(); 3963 Metaspace::post_initialize(); 3964 3965 HOTSPOT_VM_INIT_END(); 3966 3967 // record VM initialization completion time 3968 #if INCLUDE_MANAGEMENT 3969 Management::record_vm_init_completed(); 3970 #endif // INCLUDE_MANAGEMENT 3971 3972 // Signal Dispatcher needs to be started before VMInit event is posted 3973 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3974 3975 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3976 if (!DisableAttachMechanism) { 3977 AttachListener::vm_start(); 3978 if (StartAttachListener || AttachListener::init_at_startup()) { 3979 AttachListener::init(); 3980 } 3981 } 3982 3983 // Launch -Xrun agents 3984 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3985 // back-end can launch with -Xdebug -Xrunjdwp. 3986 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3987 create_vm_init_libraries(); 3988 } 3989 3990 if (CleanChunkPoolAsync) { 3991 Chunk::start_chunk_pool_cleaner_task(); 3992 } 3993 3994 3995 // initialize compiler(s) 3996 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3997 #if INCLUDE_JVMCI 3998 bool force_JVMCI_intialization = false; 3999 if (EnableJVMCI) { 4000 // Initialize JVMCI eagerly when it is explicitly requested. 4001 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 4002 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 4003 4004 if (!force_JVMCI_intialization) { 4005 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4006 // compilations via JVMCI will not actually block until JVMCI is initialized. 4007 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4008 } 4009 } 4010 #endif 4011 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 4012 // Postpone completion of compiler initialization to after JVMCI 4013 // is initialized to avoid timeouts of blocking compilations. 4014 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 4015 CompileBroker::compilation_init_phase2(); 4016 } 4017 #endif 4018 4019 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4020 // It is done after compilers are initialized, because otherwise compilations of 4021 // signature polymorphic MH intrinsics can be missed 4022 // (see SystemDictionary::find_method_handle_intrinsic). 4023 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4024 4025 // This will initialize the module system. Only java.base classes can be 4026 // loaded until phase 2 completes 4027 call_initPhase2(CHECK_JNI_ERR); 4028 4029 JFR_ONLY(Jfr::on_create_vm_2();) 4030 4031 // Always call even when there are not JVMTI environments yet, since environments 4032 // may be attached late and JVMTI must track phases of VM execution 4033 JvmtiExport::enter_start_phase(); 4034 4035 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4036 JvmtiExport::post_vm_start(); 4037 4038 // Final system initialization including security manager and system class loader 4039 call_initPhase3(CHECK_JNI_ERR); 4040 4041 // cache the system and platform class loaders 4042 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4043 4044 #if INCLUDE_CDS 4045 // capture the module path info from the ModuleEntryTable 4046 ClassLoader::initialize_module_path(THREAD); 4047 #endif 4048 4049 #if INCLUDE_JVMCI 4050 if (force_JVMCI_intialization) { 4051 JVMCI::initialize_compiler(CHECK_JNI_ERR); 4052 CompileBroker::compilation_init_phase2(); 4053 } 4054 #endif 4055 4056 // Always call even when there are not JVMTI environments yet, since environments 4057 // may be attached late and JVMTI must track phases of VM execution 4058 JvmtiExport::enter_live_phase(); 4059 4060 // Make perfmemory accessible 4061 PerfMemory::set_accessible(true); 4062 4063 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4064 JvmtiExport::post_vm_initialized(); 4065 4066 JFR_ONLY(Jfr::on_create_vm_3();) 4067 4068 #if INCLUDE_MANAGEMENT 4069 Management::initialize(THREAD); 4070 4071 if (HAS_PENDING_EXCEPTION) { 4072 // management agent fails to start possibly due to 4073 // configuration problem and is responsible for printing 4074 // stack trace if appropriate. Simply exit VM. 4075 vm_exit(1); 4076 } 4077 #endif // INCLUDE_MANAGEMENT 4078 4079 if (MemProfiling) MemProfiler::engage(); 4080 StatSampler::engage(); 4081 if (CheckJNICalls) JniPeriodicChecker::engage(); 4082 4083 BiasedLocking::init(); 4084 4085 #if INCLUDE_RTM_OPT 4086 RTMLockingCounters::init(); 4087 #endif 4088 4089 call_postVMInitHook(THREAD); 4090 // The Java side of PostVMInitHook.run must deal with all 4091 // exceptions and provide means of diagnosis. 4092 if (HAS_PENDING_EXCEPTION) { 4093 CLEAR_PENDING_EXCEPTION; 4094 } 4095 4096 { 4097 MutexLocker ml(PeriodicTask_lock); 4098 // Make sure the WatcherThread can be started by WatcherThread::start() 4099 // or by dynamic enrollment. 4100 WatcherThread::make_startable(); 4101 // Start up the WatcherThread if there are any periodic tasks 4102 // NOTE: All PeriodicTasks should be registered by now. If they 4103 // aren't, late joiners might appear to start slowly (we might 4104 // take a while to process their first tick). 4105 if (PeriodicTask::num_tasks() > 0) { 4106 WatcherThread::start(); 4107 } 4108 } 4109 4110 create_vm_timer.end(); 4111 #ifdef ASSERT 4112 _vm_complete = true; 4113 #endif 4114 4115 if (DumpSharedSpaces) { 4116 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4117 ShouldNotReachHere(); 4118 } 4119 4120 return JNI_OK; 4121 } 4122 4123 // type for the Agent_OnLoad and JVM_OnLoad entry points 4124 extern "C" { 4125 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4126 } 4127 // Find a command line agent library and return its entry point for 4128 // -agentlib: -agentpath: -Xrun 4129 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4130 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4131 const char *on_load_symbols[], 4132 size_t num_symbol_entries) { 4133 OnLoadEntry_t on_load_entry = NULL; 4134 void *library = NULL; 4135 4136 if (!agent->valid()) { 4137 char buffer[JVM_MAXPATHLEN]; 4138 char ebuf[1024] = ""; 4139 const char *name = agent->name(); 4140 const char *msg = "Could not find agent library "; 4141 4142 // First check to see if agent is statically linked into executable 4143 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4144 library = agent->os_lib(); 4145 } else if (agent->is_absolute_path()) { 4146 library = os::dll_load(name, ebuf, sizeof ebuf); 4147 if (library == NULL) { 4148 const char *sub_msg = " in absolute path, with error: "; 4149 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4150 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4151 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4152 // If we can't find the agent, exit. 4153 vm_exit_during_initialization(buf, NULL); 4154 FREE_C_HEAP_ARRAY(char, buf); 4155 } 4156 } else { 4157 // Try to load the agent from the standard dll directory 4158 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4159 name)) { 4160 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4161 } 4162 if (library == NULL) { // Try the library path directory. 4163 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4164 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4165 } 4166 if (library == NULL) { 4167 const char *sub_msg = " on the library path, with error: "; 4168 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4169 4170 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4171 strlen(ebuf) + strlen(sub_msg2) + 1; 4172 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4173 if (!agent->is_instrument_lib()) { 4174 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4175 } else { 4176 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4177 } 4178 // If we can't find the agent, exit. 4179 vm_exit_during_initialization(buf, NULL); 4180 FREE_C_HEAP_ARRAY(char, buf); 4181 } 4182 } 4183 } 4184 agent->set_os_lib(library); 4185 agent->set_valid(); 4186 } 4187 4188 // Find the OnLoad function. 4189 on_load_entry = 4190 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4191 false, 4192 on_load_symbols, 4193 num_symbol_entries)); 4194 return on_load_entry; 4195 } 4196 4197 // Find the JVM_OnLoad entry point 4198 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4199 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4200 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4201 } 4202 4203 // Find the Agent_OnLoad entry point 4204 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4205 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4206 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4207 } 4208 4209 // For backwards compatibility with -Xrun 4210 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4211 // treated like -agentpath: 4212 // Must be called before agent libraries are created 4213 void Threads::convert_vm_init_libraries_to_agents() { 4214 AgentLibrary* agent; 4215 AgentLibrary* next; 4216 4217 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4218 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4219 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4220 4221 // If there is an JVM_OnLoad function it will get called later, 4222 // otherwise see if there is an Agent_OnLoad 4223 if (on_load_entry == NULL) { 4224 on_load_entry = lookup_agent_on_load(agent); 4225 if (on_load_entry != NULL) { 4226 // switch it to the agent list -- so that Agent_OnLoad will be called, 4227 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4228 Arguments::convert_library_to_agent(agent); 4229 } else { 4230 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4231 } 4232 } 4233 } 4234 } 4235 4236 // Create agents for -agentlib: -agentpath: and converted -Xrun 4237 // Invokes Agent_OnLoad 4238 // Called very early -- before JavaThreads exist 4239 void Threads::create_vm_init_agents() { 4240 extern struct JavaVM_ main_vm; 4241 AgentLibrary* agent; 4242 4243 JvmtiExport::enter_onload_phase(); 4244 4245 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4246 // CDS dumping does not support native JVMTI agent. 4247 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4248 if (Arguments::is_dumping_archive()) { 4249 if(!agent->is_instrument_lib()) { 4250 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4251 } else if (!AllowArchivingWithJavaAgent) { 4252 vm_exit_during_cds_dumping( 4253 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4254 } 4255 } 4256 4257 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4258 4259 if (on_load_entry != NULL) { 4260 // Invoke the Agent_OnLoad function 4261 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4262 if (err != JNI_OK) { 4263 vm_exit_during_initialization("agent library failed to init", agent->name()); 4264 } 4265 } else { 4266 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4267 } 4268 } 4269 4270 JvmtiExport::enter_primordial_phase(); 4271 } 4272 4273 extern "C" { 4274 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4275 } 4276 4277 void Threads::shutdown_vm_agents() { 4278 // Send any Agent_OnUnload notifications 4279 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4280 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4281 extern struct JavaVM_ main_vm; 4282 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4283 4284 // Find the Agent_OnUnload function. 4285 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4286 os::find_agent_function(agent, 4287 false, 4288 on_unload_symbols, 4289 num_symbol_entries)); 4290 4291 // Invoke the Agent_OnUnload function 4292 if (unload_entry != NULL) { 4293 JavaThread* thread = JavaThread::current(); 4294 ThreadToNativeFromVM ttn(thread); 4295 HandleMark hm(thread); 4296 (*unload_entry)(&main_vm); 4297 } 4298 } 4299 } 4300 4301 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4302 // Invokes JVM_OnLoad 4303 void Threads::create_vm_init_libraries() { 4304 extern struct JavaVM_ main_vm; 4305 AgentLibrary* agent; 4306 4307 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4308 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4309 4310 if (on_load_entry != NULL) { 4311 // Invoke the JVM_OnLoad function 4312 JavaThread* thread = JavaThread::current(); 4313 ThreadToNativeFromVM ttn(thread); 4314 HandleMark hm(thread); 4315 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4316 if (err != JNI_OK) { 4317 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4318 } 4319 } else { 4320 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4321 } 4322 } 4323 } 4324 4325 4326 // Last thread running calls java.lang.Shutdown.shutdown() 4327 void JavaThread::invoke_shutdown_hooks() { 4328 HandleMark hm(this); 4329 4330 // We could get here with a pending exception, if so clear it now. 4331 if (this->has_pending_exception()) { 4332 this->clear_pending_exception(); 4333 } 4334 4335 EXCEPTION_MARK; 4336 Klass* shutdown_klass = 4337 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4338 THREAD); 4339 if (shutdown_klass != NULL) { 4340 // SystemDictionary::resolve_or_null will return null if there was 4341 // an exception. If we cannot load the Shutdown class, just don't 4342 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4343 // won't be run. Note that if a shutdown hook was registered, 4344 // the Shutdown class would have already been loaded 4345 // (Runtime.addShutdownHook will load it). 4346 JavaValue result(T_VOID); 4347 JavaCalls::call_static(&result, 4348 shutdown_klass, 4349 vmSymbols::shutdown_name(), 4350 vmSymbols::void_method_signature(), 4351 THREAD); 4352 } 4353 CLEAR_PENDING_EXCEPTION; 4354 } 4355 4356 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4357 // the program falls off the end of main(). Another VM exit path is through 4358 // vm_exit() when the program calls System.exit() to return a value or when 4359 // there is a serious error in VM. The two shutdown paths are not exactly 4360 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4361 // and VM_Exit op at VM level. 4362 // 4363 // Shutdown sequence: 4364 // + Shutdown native memory tracking if it is on 4365 // + Wait until we are the last non-daemon thread to execute 4366 // <-- every thing is still working at this moment --> 4367 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4368 // shutdown hooks 4369 // + Call before_exit(), prepare for VM exit 4370 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4371 // currently the only user of this mechanism is File.deleteOnExit()) 4372 // > stop StatSampler, watcher thread, 4373 // post thread end and vm death events to JVMTI, 4374 // stop signal thread 4375 // + Call JavaThread::exit(), it will: 4376 // > release JNI handle blocks, remove stack guard pages 4377 // > remove this thread from Threads list 4378 // <-- no more Java code from this thread after this point --> 4379 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4380 // the compiler threads at safepoint 4381 // <-- do not use anything that could get blocked by Safepoint --> 4382 // + Disable tracing at JNI/JVM barriers 4383 // + Set _vm_exited flag for threads that are still running native code 4384 // + Call exit_globals() 4385 // > deletes tty 4386 // > deletes PerfMemory resources 4387 // + Delete this thread 4388 // + Return to caller 4389 4390 bool Threads::destroy_vm() { 4391 JavaThread* thread = JavaThread::current(); 4392 4393 #ifdef ASSERT 4394 _vm_complete = false; 4395 #endif 4396 // Wait until we are the last non-daemon thread to execute 4397 { MonitorLocker nu(Threads_lock); 4398 while (Threads::number_of_non_daemon_threads() > 1) 4399 // This wait should make safepoint checks, wait without a timeout, 4400 // and wait as a suspend-equivalent condition. 4401 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4402 } 4403 4404 EventShutdown e; 4405 if (e.should_commit()) { 4406 e.set_reason("No remaining non-daemon Java threads"); 4407 e.commit(); 4408 } 4409 4410 // Hang forever on exit if we are reporting an error. 4411 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4412 os::infinite_sleep(); 4413 } 4414 os::wait_for_keypress_at_exit(); 4415 4416 // run Java level shutdown hooks 4417 thread->invoke_shutdown_hooks(); 4418 4419 before_exit(thread); 4420 4421 thread->exit(true); 4422 4423 // Stop VM thread. 4424 { 4425 // 4945125 The vm thread comes to a safepoint during exit. 4426 // GC vm_operations can get caught at the safepoint, and the 4427 // heap is unparseable if they are caught. Grab the Heap_lock 4428 // to prevent this. The GC vm_operations will not be able to 4429 // queue until after the vm thread is dead. After this point, 4430 // we'll never emerge out of the safepoint before the VM exits. 4431 4432 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4433 4434 VMThread::wait_for_vm_thread_exit(); 4435 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4436 VMThread::destroy(); 4437 } 4438 4439 // Now, all Java threads are gone except daemon threads. Daemon threads 4440 // running Java code or in VM are stopped by the Safepoint. However, 4441 // daemon threads executing native code are still running. But they 4442 // will be stopped at native=>Java/VM barriers. Note that we can't 4443 // simply kill or suspend them, as it is inherently deadlock-prone. 4444 4445 VM_Exit::set_vm_exited(); 4446 4447 // Clean up ideal graph printers after the VMThread has started 4448 // the final safepoint which will block all the Compiler threads. 4449 // Note that this Thread has already logically exited so the 4450 // clean_up() function's use of a JavaThreadIteratorWithHandle 4451 // would be a problem except set_vm_exited() has remembered the 4452 // shutdown thread which is granted a policy exception. 4453 #if defined(COMPILER2) && !defined(PRODUCT) 4454 IdealGraphPrinter::clean_up(); 4455 #endif 4456 4457 notify_vm_shutdown(); 4458 4459 // exit_globals() will delete tty 4460 exit_globals(); 4461 4462 // We are after VM_Exit::set_vm_exited() so we can't call 4463 // thread->smr_delete() or we will block on the Threads_lock. 4464 // Deleting the shutdown thread here is safe because another 4465 // JavaThread cannot have an active ThreadsListHandle for 4466 // this JavaThread. 4467 delete thread; 4468 4469 #if INCLUDE_JVMCI 4470 if (JVMCICounterSize > 0) { 4471 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4472 } 4473 #endif 4474 4475 LogConfiguration::finalize(); 4476 4477 return true; 4478 } 4479 4480 4481 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4482 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4483 return is_supported_jni_version(version); 4484 } 4485 4486 4487 jboolean Threads::is_supported_jni_version(jint version) { 4488 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4489 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4490 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4491 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4492 if (version == JNI_VERSION_9) return JNI_TRUE; 4493 if (version == JNI_VERSION_10) return JNI_TRUE; 4494 return JNI_FALSE; 4495 } 4496 4497 4498 void Threads::add(JavaThread* p, bool force_daemon) { 4499 // The threads lock must be owned at this point 4500 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4501 4502 BarrierSet::barrier_set()->on_thread_attach(p); 4503 4504 // Once a JavaThread is added to the Threads list, smr_delete() has 4505 // to be used to delete it. Otherwise we can just delete it directly. 4506 p->set_on_thread_list(); 4507 4508 _number_of_threads++; 4509 oop threadObj = p->threadObj(); 4510 bool daemon = true; 4511 // Bootstrapping problem: threadObj can be null for initial 4512 // JavaThread (or for threads attached via JNI) 4513 if ((!force_daemon) && !is_daemon((threadObj))) { 4514 _number_of_non_daemon_threads++; 4515 daemon = false; 4516 } 4517 4518 ThreadService::add_thread(p, daemon); 4519 4520 // Maintain fast thread list 4521 ThreadsSMRSupport::add_thread(p); 4522 4523 // Possible GC point. 4524 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4525 } 4526 4527 void Threads::remove(JavaThread* p, bool is_daemon) { 4528 4529 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4530 ObjectSynchronizer::om_flush(p); 4531 4532 // Extra scope needed for Thread_lock, so we can check 4533 // that we do not remove thread without safepoint code notice 4534 { MonitorLocker ml(Threads_lock); 4535 4536 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4537 4538 // Maintain fast thread list 4539 ThreadsSMRSupport::remove_thread(p); 4540 4541 _number_of_threads--; 4542 if (!is_daemon) { 4543 _number_of_non_daemon_threads--; 4544 4545 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4546 // on destroy_vm will wake up. 4547 if (number_of_non_daemon_threads() == 1) { 4548 ml.notify_all(); 4549 } 4550 } 4551 ThreadService::remove_thread(p, is_daemon); 4552 4553 // Make sure that safepoint code disregard this thread. This is needed since 4554 // the thread might mess around with locks after this point. This can cause it 4555 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4556 // of this thread since it is removed from the queue. 4557 p->set_terminated_value(); 4558 } // unlock Threads_lock 4559 4560 // Since Events::log uses a lock, we grab it outside the Threads_lock 4561 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4562 } 4563 4564 // Operations on the Threads list for GC. These are not explicitly locked, 4565 // but the garbage collector must provide a safe context for them to run. 4566 // In particular, these things should never be called when the Threads_lock 4567 // is held by some other thread. (Note: the Safepoint abstraction also 4568 // uses the Threads_lock to guarantee this property. It also makes sure that 4569 // all threads gets blocked when exiting or starting). 4570 4571 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4572 ALL_JAVA_THREADS(p) { 4573 p->oops_do(f, cf); 4574 } 4575 VMThread::vm_thread()->oops_do(f, cf); 4576 } 4577 4578 void Threads::change_thread_claim_token() { 4579 if (++_thread_claim_token == 0) { 4580 // On overflow of the token counter, there is a risk of future 4581 // collisions between a new global token value and a stale token 4582 // for a thread, because not all iterations visit all threads. 4583 // (Though it's pretty much a theoretical concern for non-trivial 4584 // token counter sizes.) To deal with the possibility, reset all 4585 // the thread tokens to zero on global token overflow. 4586 struct ResetClaims : public ThreadClosure { 4587 virtual void do_thread(Thread* t) { 4588 t->claim_threads_do(false, 0); 4589 } 4590 } reset_claims; 4591 Threads::threads_do(&reset_claims); 4592 // On overflow, update the global token to non-zero, to 4593 // avoid the special "never claimed" initial thread value. 4594 _thread_claim_token = 1; 4595 } 4596 } 4597 4598 #ifdef ASSERT 4599 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4600 const uintx token = t->threads_do_token(); 4601 assert(token == expected, 4602 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4603 UINTX_FORMAT, kind, p2i(t), token, expected); 4604 } 4605 4606 void Threads::assert_all_threads_claimed() { 4607 ALL_JAVA_THREADS(p) { 4608 assert_thread_claimed("Thread", p, _thread_claim_token); 4609 } 4610 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4611 } 4612 #endif // ASSERT 4613 4614 class ParallelOopsDoThreadClosure : public ThreadClosure { 4615 private: 4616 OopClosure* _f; 4617 CodeBlobClosure* _cf; 4618 public: 4619 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4620 void do_thread(Thread* t) { 4621 t->oops_do(_f, _cf); 4622 } 4623 }; 4624 4625 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4626 ParallelOopsDoThreadClosure tc(f, cf); 4627 possibly_parallel_threads_do(is_par, &tc); 4628 } 4629 4630 void Threads::nmethods_do(CodeBlobClosure* cf) { 4631 ALL_JAVA_THREADS(p) { 4632 // This is used by the code cache sweeper to mark nmethods that are active 4633 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4634 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4635 if(!p->is_Code_cache_sweeper_thread()) { 4636 p->nmethods_do(cf); 4637 } 4638 } 4639 } 4640 4641 void Threads::metadata_do(MetadataClosure* f) { 4642 ALL_JAVA_THREADS(p) { 4643 p->metadata_do(f); 4644 } 4645 } 4646 4647 class ThreadHandlesClosure : public ThreadClosure { 4648 void (*_f)(Metadata*); 4649 public: 4650 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4651 virtual void do_thread(Thread* thread) { 4652 thread->metadata_handles_do(_f); 4653 } 4654 }; 4655 4656 void Threads::metadata_handles_do(void f(Metadata*)) { 4657 // Only walk the Handles in Thread. 4658 ThreadHandlesClosure handles_closure(f); 4659 threads_do(&handles_closure); 4660 } 4661 4662 // Get count Java threads that are waiting to enter the specified monitor. 4663 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4664 int count, 4665 address monitor) { 4666 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4667 4668 int i = 0; 4669 DO_JAVA_THREADS(t_list, p) { 4670 if (!p->can_call_java()) continue; 4671 4672 address pending = (address)p->current_pending_monitor(); 4673 if (pending == monitor) { // found a match 4674 if (i < count) result->append(p); // save the first count matches 4675 i++; 4676 } 4677 } 4678 4679 return result; 4680 } 4681 4682 4683 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4684 address owner) { 4685 // NULL owner means not locked so we can skip the search 4686 if (owner == NULL) return NULL; 4687 4688 DO_JAVA_THREADS(t_list, p) { 4689 // first, see if owner is the address of a Java thread 4690 if (owner == (address)p) return p; 4691 } 4692 4693 // Cannot assert on lack of success here since this function may be 4694 // used by code that is trying to report useful problem information 4695 // like deadlock detection. 4696 if (UseHeavyMonitors) return NULL; 4697 4698 // If we didn't find a matching Java thread and we didn't force use of 4699 // heavyweight monitors, then the owner is the stack address of the 4700 // Lock Word in the owning Java thread's stack. 4701 // 4702 JavaThread* the_owner = NULL; 4703 DO_JAVA_THREADS(t_list, q) { 4704 if (q->is_lock_owned(owner)) { 4705 the_owner = q; 4706 break; 4707 } 4708 } 4709 4710 // cannot assert on lack of success here; see above comment 4711 return the_owner; 4712 } 4713 4714 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4715 void Threads::print_on(outputStream* st, bool print_stacks, 4716 bool internal_format, bool print_concurrent_locks, 4717 bool print_extended_info) { 4718 char buf[32]; 4719 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4720 4721 st->print_cr("Full thread dump %s (%s %s):", 4722 VM_Version::vm_name(), 4723 VM_Version::vm_release(), 4724 VM_Version::vm_info_string()); 4725 st->cr(); 4726 4727 #if INCLUDE_SERVICES 4728 // Dump concurrent locks 4729 ConcurrentLocksDump concurrent_locks; 4730 if (print_concurrent_locks) { 4731 concurrent_locks.dump_at_safepoint(); 4732 } 4733 #endif // INCLUDE_SERVICES 4734 4735 ThreadsSMRSupport::print_info_on(st); 4736 st->cr(); 4737 4738 ALL_JAVA_THREADS(p) { 4739 ResourceMark rm; 4740 p->print_on(st, print_extended_info); 4741 if (print_stacks) { 4742 if (internal_format) { 4743 p->trace_stack(); 4744 } else { 4745 p->print_stack_on(st); 4746 } 4747 } 4748 st->cr(); 4749 #if INCLUDE_SERVICES 4750 if (print_concurrent_locks) { 4751 concurrent_locks.print_locks_on(p, st); 4752 } 4753 #endif // INCLUDE_SERVICES 4754 } 4755 4756 VMThread::vm_thread()->print_on(st); 4757 st->cr(); 4758 Universe::heap()->print_gc_threads_on(st); 4759 WatcherThread* wt = WatcherThread::watcher_thread(); 4760 if (wt != NULL) { 4761 wt->print_on(st); 4762 st->cr(); 4763 } 4764 4765 st->flush(); 4766 } 4767 4768 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4769 int buflen, bool* found_current) { 4770 if (this_thread != NULL) { 4771 bool is_current = (current == this_thread); 4772 *found_current = *found_current || is_current; 4773 st->print("%s", is_current ? "=>" : " "); 4774 4775 st->print(PTR_FORMAT, p2i(this_thread)); 4776 st->print(" "); 4777 this_thread->print_on_error(st, buf, buflen); 4778 st->cr(); 4779 } 4780 } 4781 4782 class PrintOnErrorClosure : public ThreadClosure { 4783 outputStream* _st; 4784 Thread* _current; 4785 char* _buf; 4786 int _buflen; 4787 bool* _found_current; 4788 public: 4789 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4790 int buflen, bool* found_current) : 4791 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4792 4793 virtual void do_thread(Thread* thread) { 4794 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4795 } 4796 }; 4797 4798 // Threads::print_on_error() is called by fatal error handler. It's possible 4799 // that VM is not at safepoint and/or current thread is inside signal handler. 4800 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4801 // memory (even in resource area), it might deadlock the error handler. 4802 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4803 int buflen) { 4804 ThreadsSMRSupport::print_info_on(st); 4805 st->cr(); 4806 4807 bool found_current = false; 4808 st->print_cr("Java Threads: ( => current thread )"); 4809 ALL_JAVA_THREADS(thread) { 4810 print_on_error(thread, st, current, buf, buflen, &found_current); 4811 } 4812 st->cr(); 4813 4814 st->print_cr("Other Threads:"); 4815 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4816 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4817 4818 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4819 Universe::heap()->gc_threads_do(&print_closure); 4820 4821 if (!found_current) { 4822 st->cr(); 4823 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4824 current->print_on_error(st, buf, buflen); 4825 st->cr(); 4826 } 4827 st->cr(); 4828 4829 st->print_cr("Threads with active compile tasks:"); 4830 print_threads_compiling(st, buf, buflen); 4831 } 4832 4833 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4834 ALL_JAVA_THREADS(thread) { 4835 if (thread->is_Compiler_thread()) { 4836 CompilerThread* ct = (CompilerThread*) thread; 4837 4838 // Keep task in local variable for NULL check. 4839 // ct->_task might be set to NULL by concurring compiler thread 4840 // because it completed the compilation. The task is never freed, 4841 // though, just returned to a free list. 4842 CompileTask* task = ct->task(); 4843 if (task != NULL) { 4844 thread->print_name_on_error(st, buf, buflen); 4845 st->print(" "); 4846 task->print(st, NULL, short_form, true); 4847 } 4848 } 4849 } 4850 } 4851 4852 4853 // Internal SpinLock and Mutex 4854 // Based on ParkEvent 4855 4856 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4857 // 4858 // We employ SpinLocks _only for low-contention, fixed-length 4859 // short-duration critical sections where we're concerned 4860 // about native mutex_t or HotSpot Mutex:: latency. 4861 // The mux construct provides a spin-then-block mutual exclusion 4862 // mechanism. 4863 // 4864 // Testing has shown that contention on the ListLock guarding gFreeList 4865 // is common. If we implement ListLock as a simple SpinLock it's common 4866 // for the JVM to devolve to yielding with little progress. This is true 4867 // despite the fact that the critical sections protected by ListLock are 4868 // extremely short. 4869 // 4870 // TODO-FIXME: ListLock should be of type SpinLock. 4871 // We should make this a 1st-class type, integrated into the lock 4872 // hierarchy as leaf-locks. Critically, the SpinLock structure 4873 // should have sufficient padding to avoid false-sharing and excessive 4874 // cache-coherency traffic. 4875 4876 4877 typedef volatile int SpinLockT; 4878 4879 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4880 if (Atomic::cmpxchg(adr, 0, 1) == 0) { 4881 return; // normal fast-path return 4882 } 4883 4884 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4885 int ctr = 0; 4886 int Yields = 0; 4887 for (;;) { 4888 while (*adr != 0) { 4889 ++ctr; 4890 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4891 if (Yields > 5) { 4892 os::naked_short_sleep(1); 4893 } else { 4894 os::naked_yield(); 4895 ++Yields; 4896 } 4897 } else { 4898 SpinPause(); 4899 } 4900 } 4901 if (Atomic::cmpxchg(adr, 0, 1) == 0) return; 4902 } 4903 } 4904 4905 void Thread::SpinRelease(volatile int * adr) { 4906 assert(*adr != 0, "invariant"); 4907 OrderAccess::fence(); // guarantee at least release consistency. 4908 // Roach-motel semantics. 4909 // It's safe if subsequent LDs and STs float "up" into the critical section, 4910 // but prior LDs and STs within the critical section can't be allowed 4911 // to reorder or float past the ST that releases the lock. 4912 // Loads and stores in the critical section - which appear in program 4913 // order before the store that releases the lock - must also appear 4914 // before the store that releases the lock in memory visibility order. 4915 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4916 // the ST of 0 into the lock-word which releases the lock, so fence 4917 // more than covers this on all platforms. 4918 *adr = 0; 4919 } 4920 4921 // muxAcquire and muxRelease: 4922 // 4923 // * muxAcquire and muxRelease support a single-word lock-word construct. 4924 // The LSB of the word is set IFF the lock is held. 4925 // The remainder of the word points to the head of a singly-linked list 4926 // of threads blocked on the lock. 4927 // 4928 // * The current implementation of muxAcquire-muxRelease uses its own 4929 // dedicated Thread._MuxEvent instance. If we're interested in 4930 // minimizing the peak number of extant ParkEvent instances then 4931 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4932 // as certain invariants were satisfied. Specifically, care would need 4933 // to be taken with regards to consuming unpark() "permits". 4934 // A safe rule of thumb is that a thread would never call muxAcquire() 4935 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4936 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4937 // consume an unpark() permit intended for monitorenter, for instance. 4938 // One way around this would be to widen the restricted-range semaphore 4939 // implemented in park(). Another alternative would be to provide 4940 // multiple instances of the PlatformEvent() for each thread. One 4941 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4942 // 4943 // * Usage: 4944 // -- Only as leaf locks 4945 // -- for short-term locking only as muxAcquire does not perform 4946 // thread state transitions. 4947 // 4948 // Alternatives: 4949 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4950 // but with parking or spin-then-park instead of pure spinning. 4951 // * Use Taura-Oyama-Yonenzawa locks. 4952 // * It's possible to construct a 1-0 lock if we encode the lockword as 4953 // (List,LockByte). Acquire will CAS the full lockword while Release 4954 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4955 // acquiring threads use timers (ParkTimed) to detect and recover from 4956 // the stranding window. Thread/Node structures must be aligned on 256-byte 4957 // boundaries by using placement-new. 4958 // * Augment MCS with advisory back-link fields maintained with CAS(). 4959 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4960 // The validity of the backlinks must be ratified before we trust the value. 4961 // If the backlinks are invalid the exiting thread must back-track through the 4962 // the forward links, which are always trustworthy. 4963 // * Add a successor indication. The LockWord is currently encoded as 4964 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4965 // to provide the usual futile-wakeup optimization. 4966 // See RTStt for details. 4967 // 4968 4969 4970 const intptr_t LOCKBIT = 1; 4971 4972 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4973 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT); 4974 if (w == 0) return; 4975 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4976 return; 4977 } 4978 4979 ParkEvent * const Self = Thread::current()->_MuxEvent; 4980 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4981 for (;;) { 4982 int its = (os::is_MP() ? 100 : 0) + 1; 4983 4984 // Optional spin phase: spin-then-park strategy 4985 while (--its >= 0) { 4986 w = *Lock; 4987 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4988 return; 4989 } 4990 } 4991 4992 Self->reset(); 4993 Self->OnList = intptr_t(Lock); 4994 // The following fence() isn't _strictly necessary as the subsequent 4995 // CAS() both serializes execution and ratifies the fetched *Lock value. 4996 OrderAccess::fence(); 4997 for (;;) { 4998 w = *Lock; 4999 if ((w & LOCKBIT) == 0) { 5000 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5001 Self->OnList = 0; // hygiene - allows stronger asserts 5002 return; 5003 } 5004 continue; // Interference -- *Lock changed -- Just retry 5005 } 5006 assert(w & LOCKBIT, "invariant"); 5007 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5008 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break; 5009 } 5010 5011 while (Self->OnList != 0) { 5012 Self->park(); 5013 } 5014 } 5015 } 5016 5017 // Release() must extract a successor from the list and then wake that thread. 5018 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5019 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5020 // Release() would : 5021 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5022 // (B) Extract a successor from the private list "in-hand" 5023 // (C) attempt to CAS() the residual back into *Lock over null. 5024 // If there were any newly arrived threads and the CAS() would fail. 5025 // In that case Release() would detach the RATs, re-merge the list in-hand 5026 // with the RATs and repeat as needed. Alternately, Release() might 5027 // detach and extract a successor, but then pass the residual list to the wakee. 5028 // The wakee would be responsible for reattaching and remerging before it 5029 // competed for the lock. 5030 // 5031 // Both "pop" and DMR are immune from ABA corruption -- there can be 5032 // multiple concurrent pushers, but only one popper or detacher. 5033 // This implementation pops from the head of the list. This is unfair, 5034 // but tends to provide excellent throughput as hot threads remain hot. 5035 // (We wake recently run threads first). 5036 // 5037 // All paths through muxRelease() will execute a CAS. 5038 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5039 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5040 // executed within the critical section are complete and globally visible before the 5041 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5042 void Thread::muxRelease(volatile intptr_t * Lock) { 5043 for (;;) { 5044 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0); 5045 assert(w & LOCKBIT, "invariant"); 5046 if (w == LOCKBIT) return; 5047 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5048 assert(List != NULL, "invariant"); 5049 assert(List->OnList == intptr_t(Lock), "invariant"); 5050 ParkEvent * const nxt = List->ListNext; 5051 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5052 5053 // The following CAS() releases the lock and pops the head element. 5054 // The CAS() also ratifies the previously fetched lock-word value. 5055 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) { 5056 continue; 5057 } 5058 List->OnList = 0; 5059 OrderAccess::fence(); 5060 List->unpark(); 5061 return; 5062 } 5063 } 5064 5065 5066 void Threads::verify() { 5067 ALL_JAVA_THREADS(p) { 5068 p->verify(); 5069 } 5070 VMThread* thread = VMThread::vm_thread(); 5071 if (thread != NULL) thread->verify(); 5072 }