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 // Enqueue a VM_Operation to do the job for us - sometime later 529 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 530 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 531 VMThread::execute(vm_stop); 532 } 533 534 535 // Check if an external suspend request has completed (or has been 536 // cancelled). Returns true if the thread is externally suspended and 537 // false otherwise. 538 // 539 // The bits parameter returns information about the code path through 540 // the routine. Useful for debugging: 541 // 542 // set in is_ext_suspend_completed(): 543 // 0x00000001 - routine was entered 544 // 0x00000010 - routine return false at end 545 // 0x00000100 - thread exited (return false) 546 // 0x00000200 - suspend request cancelled (return false) 547 // 0x00000400 - thread suspended (return true) 548 // 0x00001000 - thread is in a suspend equivalent state (return true) 549 // 0x00002000 - thread is native and walkable (return true) 550 // 0x00004000 - thread is native_trans and walkable (needed retry) 551 // 552 // set in wait_for_ext_suspend_completion(): 553 // 0x00010000 - routine was entered 554 // 0x00020000 - suspend request cancelled before loop (return false) 555 // 0x00040000 - thread suspended before loop (return true) 556 // 0x00080000 - suspend request cancelled in loop (return false) 557 // 0x00100000 - thread suspended in loop (return true) 558 // 0x00200000 - suspend not completed during retry loop (return false) 559 560 // Helper class for tracing suspend wait debug bits. 561 // 562 // 0x00000100 indicates that the target thread exited before it could 563 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 564 // 0x00080000 each indicate a cancelled suspend request so they don't 565 // count as wait failures either. 566 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 567 568 class TraceSuspendDebugBits : public StackObj { 569 private: 570 JavaThread * jt; 571 bool is_wait; 572 bool called_by_wait; // meaningful when !is_wait 573 uint32_t * bits; 574 575 public: 576 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 577 uint32_t *_bits) { 578 jt = _jt; 579 is_wait = _is_wait; 580 called_by_wait = _called_by_wait; 581 bits = _bits; 582 } 583 584 ~TraceSuspendDebugBits() { 585 if (!is_wait) { 586 #if 1 587 // By default, don't trace bits for is_ext_suspend_completed() calls. 588 // That trace is very chatty. 589 return; 590 #else 591 if (!called_by_wait) { 592 // If tracing for is_ext_suspend_completed() is enabled, then only 593 // trace calls to it from wait_for_ext_suspend_completion() 594 return; 595 } 596 #endif 597 } 598 599 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 600 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 601 MutexLocker ml(Threads_lock); // needed for get_thread_name() 602 ResourceMark rm; 603 604 tty->print_cr( 605 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 606 jt->get_thread_name(), *bits); 607 608 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 609 } 610 } 611 } 612 }; 613 #undef DEBUG_FALSE_BITS 614 615 616 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 617 uint32_t *bits) { 618 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 619 620 bool did_trans_retry = false; // only do thread_in_native_trans retry once 621 bool do_trans_retry; // flag to force the retry 622 623 *bits |= 0x00000001; 624 625 do { 626 do_trans_retry = false; 627 628 if (is_exiting()) { 629 // Thread is in the process of exiting. This is always checked 630 // first to reduce the risk of dereferencing a freed JavaThread. 631 *bits |= 0x00000100; 632 return false; 633 } 634 635 if (!is_external_suspend()) { 636 // Suspend request is cancelled. This is always checked before 637 // is_ext_suspended() to reduce the risk of a rogue resume 638 // confusing the thread that made the suspend request. 639 *bits |= 0x00000200; 640 return false; 641 } 642 643 if (is_ext_suspended()) { 644 // thread is suspended 645 *bits |= 0x00000400; 646 return true; 647 } 648 649 // Now that we no longer do hard suspends of threads running 650 // native code, the target thread can be changing thread state 651 // while we are in this routine: 652 // 653 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 654 // 655 // We save a copy of the thread state as observed at this moment 656 // and make our decision about suspend completeness based on the 657 // copy. This closes the race where the thread state is seen as 658 // _thread_in_native_trans in the if-thread_blocked check, but is 659 // seen as _thread_blocked in if-thread_in_native_trans check. 660 JavaThreadState save_state = thread_state(); 661 662 if (save_state == _thread_blocked && is_suspend_equivalent()) { 663 // If the thread's state is _thread_blocked and this blocking 664 // condition is known to be equivalent to a suspend, then we can 665 // consider the thread to be externally suspended. This means that 666 // the code that sets _thread_blocked has been modified to do 667 // self-suspension if the blocking condition releases. We also 668 // used to check for CONDVAR_WAIT here, but that is now covered by 669 // the _thread_blocked with self-suspension check. 670 // 671 // Return true since we wouldn't be here unless there was still an 672 // external suspend request. 673 *bits |= 0x00001000; 674 return true; 675 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 676 // Threads running native code will self-suspend on native==>VM/Java 677 // transitions. If its stack is walkable (should always be the case 678 // unless this function is called before the actual java_suspend() 679 // call), then the wait is done. 680 *bits |= 0x00002000; 681 return true; 682 } else if (!called_by_wait && !did_trans_retry && 683 save_state == _thread_in_native_trans && 684 frame_anchor()->walkable()) { 685 // The thread is transitioning from thread_in_native to another 686 // thread state. check_safepoint_and_suspend_for_native_trans() 687 // will force the thread to self-suspend. If it hasn't gotten 688 // there yet we may have caught the thread in-between the native 689 // code check above and the self-suspend. Lucky us. If we were 690 // called by wait_for_ext_suspend_completion(), then it 691 // will be doing the retries so we don't have to. 692 // 693 // Since we use the saved thread state in the if-statement above, 694 // there is a chance that the thread has already transitioned to 695 // _thread_blocked by the time we get here. In that case, we will 696 // make a single unnecessary pass through the logic below. This 697 // doesn't hurt anything since we still do the trans retry. 698 699 *bits |= 0x00004000; 700 701 // Once the thread leaves thread_in_native_trans for another 702 // thread state, we break out of this retry loop. We shouldn't 703 // need this flag to prevent us from getting back here, but 704 // sometimes paranoia is good. 705 did_trans_retry = true; 706 707 // We wait for the thread to transition to a more usable state. 708 for (int i = 1; i <= SuspendRetryCount; i++) { 709 // We used to do an "os::yield_all(i)" call here with the intention 710 // that yielding would increase on each retry. However, the parameter 711 // is ignored on Linux which means the yield didn't scale up. Waiting 712 // on the SR_lock below provides a much more predictable scale up for 713 // the delay. It also provides a simple/direct point to check for any 714 // safepoint requests from the VMThread 715 716 // temporarily drops SR_lock while doing wait with safepoint check 717 // (if we're a JavaThread - the WatcherThread can also call this) 718 // and increase delay with each retry 719 if (Thread::current()->is_Java_thread()) { 720 SR_lock()->wait(i * delay); 721 } else { 722 SR_lock()->wait_without_safepoint_check(i * delay); 723 } 724 725 // check the actual thread state instead of what we saved above 726 if (thread_state() != _thread_in_native_trans) { 727 // the thread has transitioned to another thread state so 728 // try all the checks (except this one) one more time. 729 do_trans_retry = true; 730 break; 731 } 732 } // end retry loop 733 734 735 } 736 } while (do_trans_retry); 737 738 *bits |= 0x00000010; 739 return false; 740 } 741 742 // Wait for an external suspend request to complete (or be cancelled). 743 // Returns true if the thread is externally suspended and false otherwise. 744 // 745 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 746 uint32_t *bits) { 747 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 748 false /* !called_by_wait */, bits); 749 750 // local flag copies to minimize SR_lock hold time 751 bool is_suspended; 752 bool pending; 753 uint32_t reset_bits; 754 755 // set a marker so is_ext_suspend_completed() knows we are the caller 756 *bits |= 0x00010000; 757 758 // We use reset_bits to reinitialize the bits value at the top of 759 // each retry loop. This allows the caller to make use of any 760 // unused bits for their own marking purposes. 761 reset_bits = *bits; 762 763 { 764 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 765 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 766 delay, bits); 767 pending = is_external_suspend(); 768 } 769 // must release SR_lock to allow suspension to complete 770 771 if (!pending) { 772 // A cancelled suspend request is the only false return from 773 // is_ext_suspend_completed() that keeps us from entering the 774 // retry loop. 775 *bits |= 0x00020000; 776 return false; 777 } 778 779 if (is_suspended) { 780 *bits |= 0x00040000; 781 return true; 782 } 783 784 for (int i = 1; i <= retries; i++) { 785 *bits = reset_bits; // reinit to only track last retry 786 787 // We used to do an "os::yield_all(i)" call here with the intention 788 // that yielding would increase on each retry. However, the parameter 789 // is ignored on Linux which means the yield didn't scale up. Waiting 790 // on the SR_lock below provides a much more predictable scale up for 791 // the delay. It also provides a simple/direct point to check for any 792 // safepoint requests from the VMThread 793 794 { 795 Thread* t = Thread::current(); 796 MonitorLocker ml(SR_lock(), 797 t->is_Java_thread() ? Mutex::_safepoint_check_flag : Mutex::_no_safepoint_check_flag); 798 // wait with safepoint check (if we're a JavaThread - the WatcherThread 799 // can also call this) and increase delay with each retry 800 ml.wait(i * delay); 801 802 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 803 delay, bits); 804 805 // It is possible for the external suspend request to be cancelled 806 // (by a resume) before the actual suspend operation is completed. 807 // Refresh our local copy to see if we still need to wait. 808 pending = is_external_suspend(); 809 } 810 811 if (!pending) { 812 // A cancelled suspend request is the only false return from 813 // is_ext_suspend_completed() that keeps us from staying in the 814 // retry loop. 815 *bits |= 0x00080000; 816 return false; 817 } 818 819 if (is_suspended) { 820 *bits |= 0x00100000; 821 return true; 822 } 823 } // end retry loop 824 825 // thread did not suspend after all our retries 826 *bits |= 0x00200000; 827 return false; 828 } 829 830 // Called from API entry points which perform stack walking. If the 831 // associated JavaThread is the current thread, then wait_for_suspend 832 // is not used. Otherwise, it determines if we should wait for the 833 // "other" thread to complete external suspension. (NOTE: in future 834 // releases the suspension mechanism should be reimplemented so this 835 // is not necessary.) 836 // 837 bool 838 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 839 if (this != JavaThread::current()) { 840 // "other" threads require special handling. 841 if (wait_for_suspend) { 842 // We are allowed to wait for the external suspend to complete 843 // so give the other thread a chance to get suspended. 844 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 845 SuspendRetryDelay, bits)) { 846 // Didn't make it so let the caller know. 847 return false; 848 } 849 } 850 // We aren't allowed to wait for the external suspend to complete 851 // so if the other thread isn't externally suspended we need to 852 // let the caller know. 853 else if (!is_ext_suspend_completed_with_lock(bits)) { 854 return false; 855 } 856 } 857 858 return true; 859 } 860 861 // GC Support 862 bool Thread::claim_par_threads_do(uintx claim_token) { 863 uintx token = _threads_do_token; 864 if (token != claim_token) { 865 uintx res = Atomic::cmpxchg(&_threads_do_token, token, claim_token); 866 if (res == token) { 867 return true; 868 } 869 guarantee(res == claim_token, "invariant"); 870 } 871 return false; 872 } 873 874 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 875 active_handles()->oops_do(f); 876 // Do oop for ThreadShadow 877 f->do_oop((oop*)&_pending_exception); 878 handle_area()->oops_do(f); 879 880 // We scan thread local monitor lists here, and the remaining global 881 // monitors in ObjectSynchronizer::oops_do(). 882 ObjectSynchronizer::thread_local_used_oops_do(this, f); 883 } 884 885 void Thread::metadata_handles_do(void f(Metadata*)) { 886 // Only walk the Handles in Thread. 887 if (metadata_handles() != NULL) { 888 for (int i = 0; i< metadata_handles()->length(); i++) { 889 f(metadata_handles()->at(i)); 890 } 891 } 892 } 893 894 void Thread::print_on(outputStream* st, bool print_extended_info) const { 895 // get_priority assumes osthread initialized 896 if (osthread() != NULL) { 897 int os_prio; 898 if (os::get_native_priority(this, &os_prio) == OS_OK) { 899 st->print("os_prio=%d ", os_prio); 900 } 901 902 st->print("cpu=%.2fms ", 903 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 904 ); 905 st->print("elapsed=%.2fs ", 906 _statistical_info.getElapsedTime() / 1000.0 907 ); 908 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 909 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 910 st->print("allocated=" SIZE_FORMAT "%s ", 911 byte_size_in_proper_unit(allocated_bytes), 912 proper_unit_for_byte_size(allocated_bytes) 913 ); 914 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 915 } 916 917 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 918 osthread()->print_on(st); 919 } 920 ThreadsSMRSupport::print_info_on(this, st); 921 st->print(" "); 922 debug_only(if (WizardMode) print_owned_locks_on(st);) 923 } 924 925 void Thread::print() const { print_on(tty); } 926 927 // Thread::print_on_error() is called by fatal error handler. Don't use 928 // any lock or allocate memory. 929 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 930 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 931 932 if (is_VM_thread()) { st->print("VMThread"); } 933 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 934 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 935 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 936 else { st->print("Thread"); } 937 938 if (is_Named_thread()) { 939 st->print(" \"%s\"", name()); 940 } 941 942 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 943 p2i(stack_end()), p2i(stack_base())); 944 945 if (osthread()) { 946 st->print(" [id=%d]", osthread()->thread_id()); 947 } 948 949 ThreadsSMRSupport::print_info_on(this, st); 950 } 951 952 void Thread::print_value_on(outputStream* st) const { 953 if (is_Named_thread()) { 954 st->print(" \"%s\" ", name()); 955 } 956 st->print(INTPTR_FORMAT, p2i(this)); // print address 957 } 958 959 #ifdef ASSERT 960 void Thread::print_owned_locks_on(outputStream* st) const { 961 Mutex* cur = _owned_locks; 962 if (cur == NULL) { 963 st->print(" (no locks) "); 964 } else { 965 st->print_cr(" Locks owned:"); 966 while (cur) { 967 cur->print_on(st); 968 cur = cur->next(); 969 } 970 } 971 } 972 973 // Checks safepoint allowed and clears unhandled oops at potential safepoints. 974 void Thread::check_possible_safepoint() { 975 if (!is_Java_thread()) return; 976 977 if (_no_safepoint_count > 0) { 978 print_owned_locks(); 979 fatal("Possible safepoint reached by thread that does not allow it"); 980 } 981 #ifdef CHECK_UNHANDLED_OOPS 982 // Clear unhandled oops in JavaThreads so we get a crash right away. 983 clear_unhandled_oops(); 984 #endif // CHECK_UNHANDLED_OOPS 985 } 986 987 void Thread::check_for_valid_safepoint_state() { 988 if (!is_Java_thread()) return; 989 990 // Check NoSafepointVerifier, which is implied by locks taken that can be 991 // shared with the VM thread. This makes sure that no locks with allow_vm_block 992 // are held. 993 check_possible_safepoint(); 994 995 if (((JavaThread*)this)->thread_state() != _thread_in_vm) { 996 fatal("LEAF method calling lock?"); 997 } 998 999 if (GCALotAtAllSafepoints) { 1000 // We could enter a safepoint here and thus have a gc 1001 InterfaceSupport::check_gc_alot(); 1002 } 1003 } 1004 #endif // ASSERT 1005 1006 bool Thread::is_in_stack(address adr) const { 1007 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1008 address end = os::current_stack_pointer(); 1009 // Allow non Java threads to call this without stack_base 1010 if (_stack_base == NULL) return true; 1011 if (stack_base() > adr && adr >= end) return true; 1012 1013 return false; 1014 } 1015 1016 bool Thread::is_in_usable_stack(address adr) const { 1017 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1018 size_t usable_stack_size = _stack_size - stack_guard_size; 1019 1020 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1021 } 1022 1023 1024 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1025 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1026 // used for compilation in the future. If that change is made, the need for these methods 1027 // should be revisited, and they should be removed if possible. 1028 1029 bool Thread::is_lock_owned(address adr) const { 1030 return on_local_stack(adr); 1031 } 1032 1033 bool Thread::set_as_starting_thread() { 1034 assert(_starting_thread == NULL, "already initialized: " 1035 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1036 // NOTE: this must be called inside the main thread. 1037 DEBUG_ONLY(_starting_thread = this;) 1038 return os::create_main_thread((JavaThread*)this); 1039 } 1040 1041 static void initialize_class(Symbol* class_name, TRAPS) { 1042 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1043 InstanceKlass::cast(klass)->initialize(CHECK); 1044 } 1045 1046 1047 // Creates the initial ThreadGroup 1048 static Handle create_initial_thread_group(TRAPS) { 1049 Handle system_instance = JavaCalls::construct_new_instance( 1050 SystemDictionary::ThreadGroup_klass(), 1051 vmSymbols::void_method_signature(), 1052 CHECK_NH); 1053 Universe::set_system_thread_group(system_instance()); 1054 1055 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1056 Handle main_instance = JavaCalls::construct_new_instance( 1057 SystemDictionary::ThreadGroup_klass(), 1058 vmSymbols::threadgroup_string_void_signature(), 1059 system_instance, 1060 string, 1061 CHECK_NH); 1062 return main_instance; 1063 } 1064 1065 // Creates the initial Thread 1066 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1067 TRAPS) { 1068 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1069 assert(ik->is_initialized(), "must be"); 1070 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1071 1072 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1073 // constructor calls Thread.current(), which must be set here for the 1074 // initial thread. 1075 java_lang_Thread::set_thread(thread_oop(), thread); 1076 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1077 thread->set_threadObj(thread_oop()); 1078 1079 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1080 1081 JavaValue result(T_VOID); 1082 JavaCalls::call_special(&result, thread_oop, 1083 ik, 1084 vmSymbols::object_initializer_name(), 1085 vmSymbols::threadgroup_string_void_signature(), 1086 thread_group, 1087 string, 1088 CHECK_NULL); 1089 return thread_oop(); 1090 } 1091 1092 char java_runtime_name[128] = ""; 1093 char java_runtime_version[128] = ""; 1094 char java_runtime_vendor_version[128] = ""; 1095 char java_runtime_vendor_vm_bug_url[128] = ""; 1096 1097 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1098 static const char* get_java_runtime_name(TRAPS) { 1099 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1100 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1101 fieldDescriptor fd; 1102 bool found = k != NULL && 1103 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1104 vmSymbols::string_signature(), &fd); 1105 if (found) { 1106 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1107 if (name_oop == NULL) { 1108 return NULL; 1109 } 1110 const char* name = java_lang_String::as_utf8_string(name_oop, 1111 java_runtime_name, 1112 sizeof(java_runtime_name)); 1113 return name; 1114 } else { 1115 return NULL; 1116 } 1117 } 1118 1119 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1120 static const char* get_java_runtime_version(TRAPS) { 1121 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1122 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1123 fieldDescriptor fd; 1124 bool found = k != NULL && 1125 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1126 vmSymbols::string_signature(), &fd); 1127 if (found) { 1128 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1129 if (name_oop == NULL) { 1130 return NULL; 1131 } 1132 const char* name = java_lang_String::as_utf8_string(name_oop, 1133 java_runtime_version, 1134 sizeof(java_runtime_version)); 1135 return name; 1136 } else { 1137 return NULL; 1138 } 1139 } 1140 1141 // extract the JRE vendor version from java.lang.VersionProps.VENDOR_VERSION 1142 static const char* get_java_runtime_vendor_version(TRAPS) { 1143 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1144 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1145 fieldDescriptor fd; 1146 bool found = k != NULL && 1147 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_version_name(), 1148 vmSymbols::string_signature(), &fd); 1149 if (found) { 1150 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1151 if (name_oop == NULL) { 1152 return NULL; 1153 } 1154 const char* name = java_lang_String::as_utf8_string(name_oop, 1155 java_runtime_vendor_version, 1156 sizeof(java_runtime_vendor_version)); 1157 return name; 1158 } else { 1159 return NULL; 1160 } 1161 } 1162 1163 // extract the JRE vendor VM bug URL from java.lang.VersionProps.VENDOR_URL_VM_BUG 1164 static const char* get_java_runtime_vendor_vm_bug_url(TRAPS) { 1165 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1166 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1167 fieldDescriptor fd; 1168 bool found = k != NULL && 1169 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_vendor_vm_bug_url_name(), 1170 vmSymbols::string_signature(), &fd); 1171 if (found) { 1172 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1173 if (name_oop == NULL) { 1174 return NULL; 1175 } 1176 const char* name = java_lang_String::as_utf8_string(name_oop, 1177 java_runtime_vendor_vm_bug_url, 1178 sizeof(java_runtime_vendor_vm_bug_url)); 1179 return name; 1180 } else { 1181 return NULL; 1182 } 1183 } 1184 1185 // General purpose hook into Java code, run once when the VM is initialized. 1186 // The Java library method itself may be changed independently from the VM. 1187 static void call_postVMInitHook(TRAPS) { 1188 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1189 if (klass != NULL) { 1190 JavaValue result(T_VOID); 1191 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1192 vmSymbols::void_method_signature(), 1193 CHECK); 1194 } 1195 } 1196 1197 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1198 bool daemon, TRAPS) { 1199 assert(thread_group.not_null(), "thread group should be specified"); 1200 assert(threadObj() == NULL, "should only create Java thread object once"); 1201 1202 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1203 assert(ik->is_initialized(), "must be"); 1204 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1205 1206 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1207 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1208 // constructor calls Thread.current(), which must be set here. 1209 java_lang_Thread::set_thread(thread_oop(), this); 1210 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1211 set_threadObj(thread_oop()); 1212 1213 JavaValue result(T_VOID); 1214 if (thread_name != NULL) { 1215 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1216 // Thread gets assigned specified name and null target 1217 JavaCalls::call_special(&result, 1218 thread_oop, 1219 ik, 1220 vmSymbols::object_initializer_name(), 1221 vmSymbols::threadgroup_string_void_signature(), 1222 thread_group, 1223 name, 1224 THREAD); 1225 } else { 1226 // Thread gets assigned name "Thread-nnn" and null target 1227 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1228 JavaCalls::call_special(&result, 1229 thread_oop, 1230 ik, 1231 vmSymbols::object_initializer_name(), 1232 vmSymbols::threadgroup_runnable_void_signature(), 1233 thread_group, 1234 Handle(), 1235 THREAD); 1236 } 1237 1238 1239 if (daemon) { 1240 java_lang_Thread::set_daemon(thread_oop()); 1241 } 1242 1243 if (HAS_PENDING_EXCEPTION) { 1244 return; 1245 } 1246 1247 Klass* group = SystemDictionary::ThreadGroup_klass(); 1248 Handle threadObj(THREAD, this->threadObj()); 1249 1250 JavaCalls::call_special(&result, 1251 thread_group, 1252 group, 1253 vmSymbols::add_method_name(), 1254 vmSymbols::thread_void_signature(), 1255 threadObj, // Arg 1 1256 THREAD); 1257 } 1258 1259 // List of all NonJavaThreads and safe iteration over that list. 1260 1261 class NonJavaThread::List { 1262 public: 1263 NonJavaThread* volatile _head; 1264 SingleWriterSynchronizer _protect; 1265 1266 List() : _head(NULL), _protect() {} 1267 }; 1268 1269 NonJavaThread::List NonJavaThread::_the_list; 1270 1271 NonJavaThread::Iterator::Iterator() : 1272 _protect_enter(_the_list._protect.enter()), 1273 _current(Atomic::load_acquire(&_the_list._head)) 1274 {} 1275 1276 NonJavaThread::Iterator::~Iterator() { 1277 _the_list._protect.exit(_protect_enter); 1278 } 1279 1280 void NonJavaThread::Iterator::step() { 1281 assert(!end(), "precondition"); 1282 _current = Atomic::load_acquire(&_current->_next); 1283 } 1284 1285 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1286 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1287 } 1288 1289 NonJavaThread::~NonJavaThread() { } 1290 1291 void NonJavaThread::add_to_the_list() { 1292 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1293 // Initialize BarrierSet-related data before adding to list. 1294 BarrierSet::barrier_set()->on_thread_attach(this); 1295 Atomic::release_store(&_next, _the_list._head); 1296 Atomic::release_store(&_the_list._head, this); 1297 } 1298 1299 void NonJavaThread::remove_from_the_list() { 1300 { 1301 MutexLocker ml(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1302 // Cleanup BarrierSet-related data before removing from list. 1303 BarrierSet::barrier_set()->on_thread_detach(this); 1304 NonJavaThread* volatile* p = &_the_list._head; 1305 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1306 if (t == this) { 1307 *p = _next; 1308 break; 1309 } 1310 } 1311 } 1312 // Wait for any in-progress iterators. Concurrent synchronize is not 1313 // allowed, so do it while holding a dedicated lock. Outside and distinct 1314 // from NJTList_lock in case an iteration attempts to lock it. 1315 MutexLocker ml(NonJavaThreadsListSync_lock, Mutex::_no_safepoint_check_flag); 1316 _the_list._protect.synchronize(); 1317 _next = NULL; // Safe to drop the link now. 1318 } 1319 1320 void NonJavaThread::pre_run() { 1321 add_to_the_list(); 1322 1323 // This is slightly odd in that NamedThread is a subclass, but 1324 // in fact name() is defined in Thread 1325 assert(this->name() != NULL, "thread name was not set before it was started"); 1326 this->set_native_thread_name(this->name()); 1327 } 1328 1329 void NonJavaThread::post_run() { 1330 JFR_ONLY(Jfr::on_thread_exit(this);) 1331 remove_from_the_list(); 1332 // Ensure thread-local-storage is cleared before termination. 1333 Thread::clear_thread_current(); 1334 } 1335 1336 // NamedThread -- non-JavaThread subclasses with multiple 1337 // uniquely named instances should derive from this. 1338 NamedThread::NamedThread() : 1339 NonJavaThread(), 1340 _name(NULL), 1341 _processed_thread(NULL), 1342 _gc_id(GCId::undefined()) 1343 {} 1344 1345 NamedThread::~NamedThread() { 1346 FREE_C_HEAP_ARRAY(char, _name); 1347 } 1348 1349 void NamedThread::set_name(const char* format, ...) { 1350 guarantee(_name == NULL, "Only get to set name once."); 1351 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1352 va_list ap; 1353 va_start(ap, format); 1354 jio_vsnprintf(_name, max_name_len, format, ap); 1355 va_end(ap); 1356 } 1357 1358 void NamedThread::print_on(outputStream* st) const { 1359 st->print("\"%s\" ", name()); 1360 Thread::print_on(st); 1361 st->cr(); 1362 } 1363 1364 1365 // ======= WatcherThread ======== 1366 1367 // The watcher thread exists to simulate timer interrupts. It should 1368 // be replaced by an abstraction over whatever native support for 1369 // timer interrupts exists on the platform. 1370 1371 WatcherThread* WatcherThread::_watcher_thread = NULL; 1372 bool WatcherThread::_startable = false; 1373 volatile bool WatcherThread::_should_terminate = false; 1374 1375 WatcherThread::WatcherThread() : NonJavaThread() { 1376 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1377 if (os::create_thread(this, os::watcher_thread)) { 1378 _watcher_thread = this; 1379 1380 // Set the watcher thread to the highest OS priority which should not be 1381 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1382 // is created. The only normal thread using this priority is the reference 1383 // handler thread, which runs for very short intervals only. 1384 // If the VMThread's priority is not lower than the WatcherThread profiling 1385 // will be inaccurate. 1386 os::set_priority(this, MaxPriority); 1387 if (!DisableStartThread) { 1388 os::start_thread(this); 1389 } 1390 } 1391 } 1392 1393 int WatcherThread::sleep() const { 1394 // The WatcherThread does not participate in the safepoint protocol 1395 // for the PeriodicTask_lock because it is not a JavaThread. 1396 MonitorLocker ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1397 1398 if (_should_terminate) { 1399 // check for termination before we do any housekeeping or wait 1400 return 0; // we did not sleep. 1401 } 1402 1403 // remaining will be zero if there are no tasks, 1404 // causing the WatcherThread to sleep until a task is 1405 // enrolled 1406 int remaining = PeriodicTask::time_to_wait(); 1407 int time_slept = 0; 1408 1409 // we expect this to timeout - we only ever get unparked when 1410 // we should terminate or when a new task has been enrolled 1411 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1412 1413 jlong time_before_loop = os::javaTimeNanos(); 1414 1415 while (true) { 1416 bool timedout = ml.wait(remaining); 1417 jlong now = os::javaTimeNanos(); 1418 1419 if (remaining == 0) { 1420 // if we didn't have any tasks we could have waited for a long time 1421 // consider the time_slept zero and reset time_before_loop 1422 time_slept = 0; 1423 time_before_loop = now; 1424 } else { 1425 // need to recalculate since we might have new tasks in _tasks 1426 time_slept = (int) ((now - time_before_loop) / 1000000); 1427 } 1428 1429 // Change to task list or spurious wakeup of some kind 1430 if (timedout || _should_terminate) { 1431 break; 1432 } 1433 1434 remaining = PeriodicTask::time_to_wait(); 1435 if (remaining == 0) { 1436 // Last task was just disenrolled so loop around and wait until 1437 // another task gets enrolled 1438 continue; 1439 } 1440 1441 remaining -= time_slept; 1442 if (remaining <= 0) { 1443 break; 1444 } 1445 } 1446 1447 return time_slept; 1448 } 1449 1450 void WatcherThread::run() { 1451 assert(this == watcher_thread(), "just checking"); 1452 1453 this->set_active_handles(JNIHandleBlock::allocate_block()); 1454 while (true) { 1455 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1456 assert(watcher_thread() == this, "thread consistency check"); 1457 1458 // Calculate how long it'll be until the next PeriodicTask work 1459 // should be done, and sleep that amount of time. 1460 int time_waited = sleep(); 1461 1462 if (VMError::is_error_reported()) { 1463 // A fatal error has happened, the error handler(VMError::report_and_die) 1464 // should abort JVM after creating an error log file. However in some 1465 // rare cases, the error handler itself might deadlock. Here periodically 1466 // check for error reporting timeouts, and if it happens, just proceed to 1467 // abort the VM. 1468 1469 // This code is in WatcherThread because WatcherThread wakes up 1470 // periodically so the fatal error handler doesn't need to do anything; 1471 // also because the WatcherThread is less likely to crash than other 1472 // threads. 1473 1474 for (;;) { 1475 // Note: we use naked sleep in this loop because we want to avoid using 1476 // any kind of VM infrastructure which may be broken at this point. 1477 if (VMError::check_timeout()) { 1478 // We hit error reporting timeout. Error reporting was interrupted and 1479 // will be wrapping things up now (closing files etc). Give it some more 1480 // time, then quit the VM. 1481 os::naked_short_sleep(200); 1482 // Print a message to stderr. 1483 fdStream err(defaultStream::output_fd()); 1484 err.print_raw_cr("# [ timer expired, abort... ]"); 1485 // skip atexit/vm_exit/vm_abort hooks 1486 os::die(); 1487 } 1488 1489 // Wait a second, then recheck for timeout. 1490 os::naked_short_sleep(999); 1491 } 1492 } 1493 1494 if (_should_terminate) { 1495 // check for termination before posting the next tick 1496 break; 1497 } 1498 1499 PeriodicTask::real_time_tick(time_waited); 1500 } 1501 1502 // Signal that it is terminated 1503 { 1504 MutexLocker mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1505 _watcher_thread = NULL; 1506 Terminator_lock->notify_all(); 1507 } 1508 } 1509 1510 void WatcherThread::start() { 1511 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1512 1513 if (watcher_thread() == NULL && _startable) { 1514 _should_terminate = false; 1515 // Create the single instance of WatcherThread 1516 new WatcherThread(); 1517 } 1518 } 1519 1520 void WatcherThread::make_startable() { 1521 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1522 _startable = true; 1523 } 1524 1525 void WatcherThread::stop() { 1526 { 1527 // Follow normal safepoint aware lock enter protocol since the 1528 // WatcherThread is stopped by another JavaThread. 1529 MutexLocker ml(PeriodicTask_lock); 1530 _should_terminate = true; 1531 1532 WatcherThread* watcher = watcher_thread(); 1533 if (watcher != NULL) { 1534 // unpark the WatcherThread so it can see that it should terminate 1535 watcher->unpark(); 1536 } 1537 } 1538 1539 MonitorLocker mu(Terminator_lock); 1540 1541 while (watcher_thread() != NULL) { 1542 // This wait should make safepoint checks, wait without a timeout, 1543 // and wait as a suspend-equivalent condition. 1544 mu.wait(0, Mutex::_as_suspend_equivalent_flag); 1545 } 1546 } 1547 1548 void WatcherThread::unpark() { 1549 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1550 PeriodicTask_lock->notify(); 1551 } 1552 1553 void WatcherThread::print_on(outputStream* st) const { 1554 st->print("\"%s\" ", name()); 1555 Thread::print_on(st); 1556 st->cr(); 1557 } 1558 1559 // ======= JavaThread ======== 1560 1561 #if INCLUDE_JVMCI 1562 1563 jlong* JavaThread::_jvmci_old_thread_counters; 1564 1565 bool jvmci_counters_include(JavaThread* thread) { 1566 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1567 } 1568 1569 void JavaThread::collect_counters(jlong* array, int length) { 1570 assert(length == JVMCICounterSize, "wrong value"); 1571 for (int i = 0; i < length; i++) { 1572 array[i] = _jvmci_old_thread_counters[i]; 1573 } 1574 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1575 if (jvmci_counters_include(tp)) { 1576 for (int i = 0; i < length; i++) { 1577 array[i] += tp->_jvmci_counters[i]; 1578 } 1579 } 1580 } 1581 } 1582 1583 // Attempt to enlarge the array for per thread counters. 1584 jlong* resize_counters_array(jlong* old_counters, int current_size, int new_size) { 1585 jlong* new_counters = NEW_C_HEAP_ARRAY(jlong, new_size, mtJVMCI); 1586 if (old_counters == NULL) { 1587 old_counters = new_counters; 1588 memset(old_counters, 0, sizeof(jlong) * new_size); 1589 } else { 1590 for (int i = 0; i < MIN2((int) current_size, new_size); i++) { 1591 new_counters[i] = old_counters[i]; 1592 } 1593 if (new_size > current_size) { 1594 memset(new_counters + current_size, 0, sizeof(jlong) * (new_size - current_size)); 1595 } 1596 FREE_C_HEAP_ARRAY(jlong, old_counters); 1597 } 1598 return new_counters; 1599 } 1600 1601 // Attempt to enlarge the array for per thread counters. 1602 void JavaThread::resize_counters(int current_size, int new_size) { 1603 _jvmci_counters = resize_counters_array(_jvmci_counters, current_size, new_size); 1604 } 1605 1606 class VM_JVMCIResizeCounters : public VM_Operation { 1607 private: 1608 int _new_size; 1609 1610 public: 1611 VM_JVMCIResizeCounters(int new_size) : _new_size(new_size) { } 1612 VMOp_Type type() const { return VMOp_JVMCIResizeCounters; } 1613 bool allow_nested_vm_operations() const { return true; } 1614 void doit() { 1615 // Resize the old thread counters array 1616 jlong* new_counters = resize_counters_array(JavaThread::_jvmci_old_thread_counters, JVMCICounterSize, _new_size); 1617 JavaThread::_jvmci_old_thread_counters = new_counters; 1618 1619 // Now resize each threads array 1620 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *tp = jtiwh.next(); ) { 1621 tp->resize_counters(JVMCICounterSize, _new_size); 1622 } 1623 JVMCICounterSize = _new_size; 1624 } 1625 }; 1626 1627 void JavaThread::resize_all_jvmci_counters(int new_size) { 1628 VM_JVMCIResizeCounters op(new_size); 1629 VMThread::execute(&op); 1630 } 1631 1632 #endif // INCLUDE_JVMCI 1633 1634 // A JavaThread is a normal Java thread 1635 1636 void JavaThread::initialize() { 1637 // Initialize fields 1638 1639 set_saved_exception_pc(NULL); 1640 set_threadObj(NULL); 1641 _anchor.clear(); 1642 set_entry_point(NULL); 1643 set_jni_functions(jni_functions()); 1644 set_callee_target(NULL); 1645 set_vm_result(NULL); 1646 set_vm_result_2(NULL); 1647 set_vframe_array_head(NULL); 1648 set_vframe_array_last(NULL); 1649 set_deferred_locals(NULL); 1650 set_deopt_mark(NULL); 1651 set_deopt_compiled_method(NULL); 1652 set_monitor_chunks(NULL); 1653 _on_thread_list = false; 1654 set_thread_state(_thread_new); 1655 _terminated = _not_terminated; 1656 _array_for_gc = NULL; 1657 _suspend_equivalent = false; 1658 _in_deopt_handler = 0; 1659 _doing_unsafe_access = false; 1660 _stack_guard_state = stack_guard_unused; 1661 #if INCLUDE_JVMCI 1662 _pending_monitorenter = false; 1663 _pending_deoptimization = -1; 1664 _pending_failed_speculation = 0; 1665 _pending_transfer_to_interpreter = false; 1666 _in_retryable_allocation = false; 1667 _jvmci._alternate_call_target = NULL; 1668 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1669 _jvmci_counters = NULL; 1670 if (JVMCICounterSize > 0) { 1671 resize_counters(0, (int) JVMCICounterSize); 1672 } 1673 #endif // INCLUDE_JVMCI 1674 _reserved_stack_activation = NULL; // stack base not known yet 1675 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1676 _exception_pc = 0; 1677 _exception_handler_pc = 0; 1678 _is_method_handle_return = 0; 1679 _jvmti_thread_state= NULL; 1680 _should_post_on_exceptions_flag = JNI_FALSE; 1681 _interp_only_mode = 0; 1682 _special_runtime_exit_condition = _no_async_condition; 1683 _pending_async_exception = NULL; 1684 _thread_stat = NULL; 1685 _thread_stat = new ThreadStatistics(); 1686 _jni_active_critical = 0; 1687 _pending_jni_exception_check_fn = NULL; 1688 _do_not_unlock_if_synchronized = false; 1689 _cached_monitor_info = NULL; 1690 _parker = Parker::Allocate(this); 1691 _SleepEvent = ParkEvent::Allocate(this); 1692 // Setup safepoint state info for this thread 1693 ThreadSafepointState::create(this); 1694 1695 debug_only(_java_call_counter = 0); 1696 1697 // JVMTI PopFrame support 1698 _popframe_condition = popframe_inactive; 1699 _popframe_preserved_args = NULL; 1700 _popframe_preserved_args_size = 0; 1701 _frames_to_pop_failed_realloc = 0; 1702 1703 if (SafepointMechanism::uses_thread_local_poll()) { 1704 SafepointMechanism::initialize_header(this); 1705 } 1706 1707 _class_to_be_initialized = NULL; 1708 1709 pd_initialize(); 1710 } 1711 1712 JavaThread::JavaThread(bool is_attaching_via_jni) : 1713 Thread() { 1714 initialize(); 1715 if (is_attaching_via_jni) { 1716 _jni_attach_state = _attaching_via_jni; 1717 } else { 1718 _jni_attach_state = _not_attaching_via_jni; 1719 } 1720 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1721 } 1722 1723 1724 // interrupt support 1725 1726 void JavaThread::interrupt() { 1727 debug_only(check_for_dangling_thread_pointer(this);) 1728 1729 // For Windows _interrupt_event 1730 osthread()->set_interrupted(true); 1731 1732 // For Thread.sleep 1733 _SleepEvent->unpark(); 1734 1735 // For JSR166 LockSupport.park 1736 parker()->unpark(); 1737 1738 // For ObjectMonitor and JvmtiRawMonitor 1739 _ParkEvent->unpark(); 1740 } 1741 1742 1743 bool JavaThread::is_interrupted(bool clear_interrupted) { 1744 debug_only(check_for_dangling_thread_pointer(this);) 1745 1746 if (threadObj() == NULL) { 1747 // If there is no j.l.Thread then it is impossible to have 1748 // been interrupted. We can find NULL during VM initialization 1749 // or when a JNI thread is still in the process of attaching. 1750 // In such cases this must be the current thread. 1751 assert(this == Thread::current(), "invariant"); 1752 return false; 1753 } 1754 1755 bool interrupted = java_lang_Thread::interrupted(threadObj()); 1756 1757 // NOTE that since there is no "lock" around the interrupt and 1758 // is_interrupted operations, there is the possibility that the 1759 // interrupted flag will be "false" but that the 1760 // low-level events will be in the signaled state. This is 1761 // intentional. The effect of this is that Object.wait() and 1762 // LockSupport.park() will appear to have a spurious wakeup, which 1763 // is allowed and not harmful, and the possibility is so rare that 1764 // it is not worth the added complexity to add yet another lock. 1765 // For the sleep event an explicit reset is performed on entry 1766 // to JavaThread::sleep, so there is no early return. It has also been 1767 // recommended not to put the interrupted flag into the "event" 1768 // structure because it hides the issue. 1769 // Also, because there is no lock, we must only clear the interrupt 1770 // state if we are going to report that we were interrupted; otherwise 1771 // an interrupt that happens just after we read the field would be lost. 1772 if (interrupted && clear_interrupted) { 1773 assert(this == Thread::current(), "only the current thread can clear"); 1774 java_lang_Thread::set_interrupted(threadObj(), false); 1775 osthread()->set_interrupted(false); 1776 } 1777 1778 return interrupted; 1779 } 1780 1781 bool JavaThread::reguard_stack(address cur_sp) { 1782 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1783 && _stack_guard_state != stack_guard_reserved_disabled) { 1784 return true; // Stack already guarded or guard pages not needed. 1785 } 1786 1787 if (register_stack_overflow()) { 1788 // For those architectures which have separate register and 1789 // memory stacks, we must check the register stack to see if 1790 // it has overflowed. 1791 return false; 1792 } 1793 1794 // Java code never executes within the yellow zone: the latter is only 1795 // there to provoke an exception during stack banging. If java code 1796 // is executing there, either StackShadowPages should be larger, or 1797 // some exception code in c1, c2 or the interpreter isn't unwinding 1798 // when it should. 1799 guarantee(cur_sp > stack_reserved_zone_base(), 1800 "not enough space to reguard - increase StackShadowPages"); 1801 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1802 enable_stack_yellow_reserved_zone(); 1803 if (reserved_stack_activation() != stack_base()) { 1804 set_reserved_stack_activation(stack_base()); 1805 } 1806 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1807 set_reserved_stack_activation(stack_base()); 1808 enable_stack_reserved_zone(); 1809 } 1810 return true; 1811 } 1812 1813 bool JavaThread::reguard_stack(void) { 1814 return reguard_stack(os::current_stack_pointer()); 1815 } 1816 1817 1818 void JavaThread::block_if_vm_exited() { 1819 if (_terminated == _vm_exited) { 1820 // _vm_exited is set at safepoint, and Threads_lock is never released 1821 // we will block here forever. 1822 // Here we can be doing a jump from a safe state to an unsafe state without 1823 // proper transition, but it happens after the final safepoint has begun. 1824 set_thread_state(_thread_in_vm); 1825 Threads_lock->lock(); 1826 ShouldNotReachHere(); 1827 } 1828 } 1829 1830 1831 // Remove this ifdef when C1 is ported to the compiler interface. 1832 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1833 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1834 1835 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1836 Thread() { 1837 initialize(); 1838 _jni_attach_state = _not_attaching_via_jni; 1839 set_entry_point(entry_point); 1840 // Create the native thread itself. 1841 // %note runtime_23 1842 os::ThreadType thr_type = os::java_thread; 1843 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1844 os::java_thread; 1845 os::create_thread(this, thr_type, stack_sz); 1846 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1847 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1848 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1849 // the exception consists of creating the exception object & initializing it, initialization 1850 // will leave the VM via a JavaCall and then all locks must be unlocked). 1851 // 1852 // The thread is still suspended when we reach here. Thread must be explicit started 1853 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1854 // by calling Threads:add. The reason why this is not done here, is because the thread 1855 // object must be fully initialized (take a look at JVM_Start) 1856 } 1857 1858 JavaThread::~JavaThread() { 1859 1860 // JSR166 -- return the parker to the free list 1861 Parker::Release(_parker); 1862 _parker = NULL; 1863 1864 // Return the sleep event to the free list 1865 ParkEvent::Release(_SleepEvent); 1866 _SleepEvent = NULL; 1867 1868 // Free any remaining previous UnrollBlock 1869 vframeArray* old_array = vframe_array_last(); 1870 1871 if (old_array != NULL) { 1872 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1873 old_array->set_unroll_block(NULL); 1874 delete old_info; 1875 delete old_array; 1876 } 1877 1878 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1879 if (deferred != NULL) { 1880 // This can only happen if thread is destroyed before deoptimization occurs. 1881 assert(deferred->length() != 0, "empty array!"); 1882 do { 1883 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1884 deferred->remove_at(0); 1885 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1886 delete dlv; 1887 } while (deferred->length() != 0); 1888 delete deferred; 1889 } 1890 1891 // All Java related clean up happens in exit 1892 ThreadSafepointState::destroy(this); 1893 if (_thread_stat != NULL) delete _thread_stat; 1894 1895 #if INCLUDE_JVMCI 1896 if (JVMCICounterSize > 0) { 1897 if (jvmci_counters_include(this)) { 1898 for (int i = 0; i < JVMCICounterSize; i++) { 1899 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1900 } 1901 } 1902 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1903 } 1904 #endif // INCLUDE_JVMCI 1905 } 1906 1907 1908 // First JavaThread specific code executed by a new Java thread. 1909 void JavaThread::pre_run() { 1910 // empty - see comments in run() 1911 } 1912 1913 // The main routine called by a new Java thread. This isn't overridden 1914 // by subclasses, instead different subclasses define a different "entry_point" 1915 // which defines the actual logic for that kind of thread. 1916 void JavaThread::run() { 1917 // initialize thread-local alloc buffer related fields 1918 this->initialize_tlab(); 1919 1920 // Used to test validity of stack trace backs. 1921 // This can't be moved into pre_run() else we invalidate 1922 // the requirement that thread_main_inner is lower on 1923 // the stack. Consequently all the initialization logic 1924 // stays here in run() rather than pre_run(). 1925 this->record_base_of_stack_pointer(); 1926 1927 this->create_stack_guard_pages(); 1928 1929 this->cache_global_variables(); 1930 1931 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1932 // in the VM. Change thread state from _thread_new to _thread_in_vm 1933 ThreadStateTransition::transition(this, _thread_new, _thread_in_vm); 1934 // Before a thread is on the threads list it is always safe, so after leaving the 1935 // _thread_new we should emit a instruction barrier. The distance to modified code 1936 // from here is probably far enough, but this is consistent and safe. 1937 OrderAccess::cross_modify_fence(); 1938 1939 assert(JavaThread::current() == this, "sanity check"); 1940 assert(!Thread::current()->owns_locks(), "sanity check"); 1941 1942 DTRACE_THREAD_PROBE(start, this); 1943 1944 // This operation might block. We call that after all safepoint checks for a new thread has 1945 // been completed. 1946 this->set_active_handles(JNIHandleBlock::allocate_block()); 1947 1948 if (JvmtiExport::should_post_thread_life()) { 1949 JvmtiExport::post_thread_start(this); 1950 1951 } 1952 1953 // We call another function to do the rest so we are sure that the stack addresses used 1954 // from there will be lower than the stack base just computed. 1955 thread_main_inner(); 1956 } 1957 1958 void JavaThread::thread_main_inner() { 1959 assert(JavaThread::current() == this, "sanity check"); 1960 assert(this->threadObj() != NULL, "just checking"); 1961 1962 // Execute thread entry point unless this thread has a pending exception 1963 // or has been stopped before starting. 1964 // Note: Due to JVM_StopThread we can have pending exceptions already! 1965 if (!this->has_pending_exception() && 1966 !java_lang_Thread::is_stillborn(this->threadObj())) { 1967 { 1968 ResourceMark rm(this); 1969 this->set_native_thread_name(this->get_thread_name()); 1970 } 1971 HandleMark hm(this); 1972 this->entry_point()(this, this); 1973 } 1974 1975 DTRACE_THREAD_PROBE(stop, this); 1976 1977 // Cleanup is handled in post_run() 1978 } 1979 1980 // Shared teardown for all JavaThreads 1981 void JavaThread::post_run() { 1982 this->exit(false); 1983 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1984 // for any shared tear-down. 1985 this->smr_delete(); 1986 } 1987 1988 static void ensure_join(JavaThread* thread) { 1989 // We do not need to grab the Threads_lock, since we are operating on ourself. 1990 Handle threadObj(thread, thread->threadObj()); 1991 assert(threadObj.not_null(), "java thread object must exist"); 1992 ObjectLocker lock(threadObj, thread); 1993 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1994 thread->clear_pending_exception(); 1995 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1996 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1997 // Clear the native thread instance - this makes isAlive return false and allows the join() 1998 // to complete once we've done the notify_all below 1999 java_lang_Thread::set_thread(threadObj(), NULL); 2000 lock.notify_all(thread); 2001 // Ignore pending exception (ThreadDeath), since we are exiting anyway 2002 thread->clear_pending_exception(); 2003 } 2004 2005 static bool is_daemon(oop threadObj) { 2006 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 2007 } 2008 2009 // For any new cleanup additions, please check to see if they need to be applied to 2010 // cleanup_failed_attach_current_thread as well. 2011 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 2012 assert(this == JavaThread::current(), "thread consistency check"); 2013 2014 elapsedTimer _timer_exit_phase1; 2015 elapsedTimer _timer_exit_phase2; 2016 elapsedTimer _timer_exit_phase3; 2017 elapsedTimer _timer_exit_phase4; 2018 2019 if (log_is_enabled(Debug, os, thread, timer)) { 2020 _timer_exit_phase1.start(); 2021 } 2022 2023 HandleMark hm(this); 2024 Handle uncaught_exception(this, this->pending_exception()); 2025 this->clear_pending_exception(); 2026 Handle threadObj(this, this->threadObj()); 2027 assert(threadObj.not_null(), "Java thread object should be created"); 2028 2029 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 2030 { 2031 EXCEPTION_MARK; 2032 2033 CLEAR_PENDING_EXCEPTION; 2034 } 2035 if (!destroy_vm) { 2036 if (uncaught_exception.not_null()) { 2037 EXCEPTION_MARK; 2038 // Call method Thread.dispatchUncaughtException(). 2039 Klass* thread_klass = SystemDictionary::Thread_klass(); 2040 JavaValue result(T_VOID); 2041 JavaCalls::call_virtual(&result, 2042 threadObj, thread_klass, 2043 vmSymbols::dispatchUncaughtException_name(), 2044 vmSymbols::throwable_void_signature(), 2045 uncaught_exception, 2046 THREAD); 2047 if (HAS_PENDING_EXCEPTION) { 2048 ResourceMark rm(this); 2049 jio_fprintf(defaultStream::error_stream(), 2050 "\nException: %s thrown from the UncaughtExceptionHandler" 2051 " in thread \"%s\"\n", 2052 pending_exception()->klass()->external_name(), 2053 get_thread_name()); 2054 CLEAR_PENDING_EXCEPTION; 2055 } 2056 } 2057 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 2058 2059 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 2060 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 2061 // is deprecated anyhow. 2062 if (!is_Compiler_thread()) { 2063 int count = 3; 2064 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 2065 EXCEPTION_MARK; 2066 JavaValue result(T_VOID); 2067 Klass* thread_klass = SystemDictionary::Thread_klass(); 2068 JavaCalls::call_virtual(&result, 2069 threadObj, thread_klass, 2070 vmSymbols::exit_method_name(), 2071 vmSymbols::void_method_signature(), 2072 THREAD); 2073 CLEAR_PENDING_EXCEPTION; 2074 } 2075 } 2076 // notify JVMTI 2077 if (JvmtiExport::should_post_thread_life()) { 2078 JvmtiExport::post_thread_end(this); 2079 } 2080 2081 // We have notified the agents that we are exiting, before we go on, 2082 // we must check for a pending external suspend request and honor it 2083 // in order to not surprise the thread that made the suspend request. 2084 while (true) { 2085 { 2086 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2087 if (!is_external_suspend()) { 2088 set_terminated(_thread_exiting); 2089 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 2090 break; 2091 } 2092 // Implied else: 2093 // Things get a little tricky here. We have a pending external 2094 // suspend request, but we are holding the SR_lock so we 2095 // can't just self-suspend. So we temporarily drop the lock 2096 // and then self-suspend. 2097 } 2098 2099 ThreadBlockInVM tbivm(this); 2100 java_suspend_self(); 2101 2102 // We're done with this suspend request, but we have to loop around 2103 // and check again. Eventually we will get SR_lock without a pending 2104 // external suspend request and will be able to mark ourselves as 2105 // exiting. 2106 } 2107 // no more external suspends are allowed at this point 2108 } else { 2109 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2110 // before_exit() has already posted JVMTI THREAD_END events 2111 } 2112 2113 if (log_is_enabled(Debug, os, thread, timer)) { 2114 _timer_exit_phase1.stop(); 2115 _timer_exit_phase2.start(); 2116 } 2117 2118 // Capture daemon status before the thread is marked as terminated. 2119 bool daemon = is_daemon(threadObj()); 2120 2121 // Notify waiters on thread object. This has to be done after exit() is called 2122 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2123 // group should have the destroyed bit set before waiters are notified). 2124 ensure_join(this); 2125 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2126 2127 if (log_is_enabled(Debug, os, thread, timer)) { 2128 _timer_exit_phase2.stop(); 2129 _timer_exit_phase3.start(); 2130 } 2131 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2132 // held by this thread must be released. The spec does not distinguish 2133 // between JNI-acquired and regular Java monitors. We can only see 2134 // regular Java monitors here if monitor enter-exit matching is broken. 2135 // 2136 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2137 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2138 if (exit_type == jni_detach) { 2139 // Sanity check even though JNI DetachCurrentThread() would have 2140 // returned JNI_ERR if there was a Java frame. JavaThread exit 2141 // should be done executing Java code by the time we get here. 2142 assert(!this->has_last_Java_frame(), 2143 "should not have a Java frame when detaching or exiting"); 2144 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2145 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2146 } 2147 2148 // These things needs to be done while we are still a Java Thread. Make sure that thread 2149 // is in a consistent state, in case GC happens 2150 JFR_ONLY(Jfr::on_thread_exit(this);) 2151 2152 if (active_handles() != NULL) { 2153 JNIHandleBlock* block = active_handles(); 2154 set_active_handles(NULL); 2155 JNIHandleBlock::release_block(block); 2156 } 2157 2158 if (free_handle_block() != NULL) { 2159 JNIHandleBlock* block = free_handle_block(); 2160 set_free_handle_block(NULL); 2161 JNIHandleBlock::release_block(block); 2162 } 2163 2164 // These have to be removed while this is still a valid thread. 2165 remove_stack_guard_pages(); 2166 2167 if (UseTLAB) { 2168 tlab().retire(); 2169 } 2170 2171 if (JvmtiEnv::environments_might_exist()) { 2172 JvmtiExport::cleanup_thread(this); 2173 } 2174 2175 // We must flush any deferred card marks and other various GC barrier 2176 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2177 // before removing a thread from the list of active threads. 2178 BarrierSet::barrier_set()->on_thread_detach(this); 2179 2180 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2181 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2182 os::current_thread_id()); 2183 2184 if (log_is_enabled(Debug, os, thread, timer)) { 2185 _timer_exit_phase3.stop(); 2186 _timer_exit_phase4.start(); 2187 } 2188 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2189 Threads::remove(this, daemon); 2190 2191 if (log_is_enabled(Debug, os, thread, timer)) { 2192 _timer_exit_phase4.stop(); 2193 ResourceMark rm(this); 2194 log_debug(os, thread, timer)("name='%s'" 2195 ", exit-phase1=" JLONG_FORMAT 2196 ", exit-phase2=" JLONG_FORMAT 2197 ", exit-phase3=" JLONG_FORMAT 2198 ", exit-phase4=" JLONG_FORMAT, 2199 get_thread_name(), 2200 _timer_exit_phase1.milliseconds(), 2201 _timer_exit_phase2.milliseconds(), 2202 _timer_exit_phase3.milliseconds(), 2203 _timer_exit_phase4.milliseconds()); 2204 } 2205 } 2206 2207 void JavaThread::cleanup_failed_attach_current_thread(bool is_daemon) { 2208 if (active_handles() != NULL) { 2209 JNIHandleBlock* block = active_handles(); 2210 set_active_handles(NULL); 2211 JNIHandleBlock::release_block(block); 2212 } 2213 2214 if (free_handle_block() != NULL) { 2215 JNIHandleBlock* block = free_handle_block(); 2216 set_free_handle_block(NULL); 2217 JNIHandleBlock::release_block(block); 2218 } 2219 2220 // These have to be removed while this is still a valid thread. 2221 remove_stack_guard_pages(); 2222 2223 if (UseTLAB) { 2224 tlab().retire(); 2225 } 2226 2227 BarrierSet::barrier_set()->on_thread_detach(this); 2228 2229 Threads::remove(this, is_daemon); 2230 this->smr_delete(); 2231 } 2232 2233 JavaThread* JavaThread::active() { 2234 Thread* thread = Thread::current(); 2235 if (thread->is_Java_thread()) { 2236 return (JavaThread*) thread; 2237 } else { 2238 assert(thread->is_VM_thread(), "this must be a vm thread"); 2239 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2240 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2241 assert(ret->is_Java_thread(), "must be a Java thread"); 2242 return ret; 2243 } 2244 } 2245 2246 bool JavaThread::is_lock_owned(address adr) const { 2247 if (Thread::is_lock_owned(adr)) return true; 2248 2249 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2250 if (chunk->contains(adr)) return true; 2251 } 2252 2253 return false; 2254 } 2255 2256 2257 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2258 chunk->set_next(monitor_chunks()); 2259 set_monitor_chunks(chunk); 2260 } 2261 2262 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2263 guarantee(monitor_chunks() != NULL, "must be non empty"); 2264 if (monitor_chunks() == chunk) { 2265 set_monitor_chunks(chunk->next()); 2266 } else { 2267 MonitorChunk* prev = monitor_chunks(); 2268 while (prev->next() != chunk) prev = prev->next(); 2269 prev->set_next(chunk->next()); 2270 } 2271 } 2272 2273 // JVM support. 2274 2275 // Note: this function shouldn't block if it's called in 2276 // _thread_in_native_trans state (such as from 2277 // check_special_condition_for_native_trans()). 2278 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2279 2280 if (has_last_Java_frame() && has_async_condition()) { 2281 // If we are at a polling page safepoint (not a poll return) 2282 // then we must defer async exception because live registers 2283 // will be clobbered by the exception path. Poll return is 2284 // ok because the call we a returning from already collides 2285 // with exception handling registers and so there is no issue. 2286 // (The exception handling path kills call result registers but 2287 // this is ok since the exception kills the result anyway). 2288 2289 if (is_at_poll_safepoint()) { 2290 // if the code we are returning to has deoptimized we must defer 2291 // the exception otherwise live registers get clobbered on the 2292 // exception path before deoptimization is able to retrieve them. 2293 // 2294 RegisterMap map(this, false); 2295 frame caller_fr = last_frame().sender(&map); 2296 assert(caller_fr.is_compiled_frame(), "what?"); 2297 if (caller_fr.is_deoptimized_frame()) { 2298 log_info(exceptions)("deferred async exception at compiled safepoint"); 2299 return; 2300 } 2301 } 2302 } 2303 2304 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2305 if (condition == _no_async_condition) { 2306 // Conditions have changed since has_special_runtime_exit_condition() 2307 // was called: 2308 // - if we were here only because of an external suspend request, 2309 // then that was taken care of above (or cancelled) so we are done 2310 // - if we were here because of another async request, then it has 2311 // been cleared between the has_special_runtime_exit_condition() 2312 // and now so again we are done 2313 return; 2314 } 2315 2316 // Check for pending async. exception 2317 if (_pending_async_exception != NULL) { 2318 // Only overwrite an already pending exception, if it is not a threadDeath. 2319 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2320 2321 // We cannot call Exceptions::_throw(...) here because we cannot block 2322 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2323 2324 LogTarget(Info, exceptions) lt; 2325 if (lt.is_enabled()) { 2326 ResourceMark rm; 2327 LogStream ls(lt); 2328 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2329 if (has_last_Java_frame()) { 2330 frame f = last_frame(); 2331 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2332 } 2333 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2334 } 2335 _pending_async_exception = NULL; 2336 clear_has_async_exception(); 2337 } 2338 } 2339 2340 if (check_unsafe_error && 2341 condition == _async_unsafe_access_error && !has_pending_exception()) { 2342 condition = _no_async_condition; // done 2343 switch (thread_state()) { 2344 case _thread_in_vm: { 2345 JavaThread* THREAD = this; 2346 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2347 } 2348 case _thread_in_native: { 2349 ThreadInVMfromNative tiv(this); 2350 JavaThread* THREAD = this; 2351 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2352 } 2353 case _thread_in_Java: { 2354 ThreadInVMfromJava tiv(this); 2355 JavaThread* THREAD = this; 2356 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2357 } 2358 default: 2359 ShouldNotReachHere(); 2360 } 2361 } 2362 2363 assert(condition == _no_async_condition || has_pending_exception() || 2364 (!check_unsafe_error && condition == _async_unsafe_access_error), 2365 "must have handled the async condition, if no exception"); 2366 } 2367 2368 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2369 2370 // Check for pending external suspend. 2371 if (is_external_suspend_with_lock()) { 2372 frame_anchor()->make_walkable(this); 2373 java_suspend_self_with_safepoint_check(); 2374 } 2375 2376 // We might be here for reasons in addition to the self-suspend request 2377 // so check for other async requests. 2378 if (check_asyncs) { 2379 check_and_handle_async_exceptions(); 2380 } 2381 2382 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2383 } 2384 2385 void JavaThread::send_thread_stop(oop java_throwable) { 2386 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2387 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2388 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2389 2390 // Do not throw asynchronous exceptions against the compiler thread 2391 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2392 if (!can_call_java()) return; 2393 2394 { 2395 // Actually throw the Throwable against the target Thread - however 2396 // only if there is no thread death exception installed already. 2397 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2398 // If the topmost frame is a runtime stub, then we are calling into 2399 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2400 // must deoptimize the caller before continuing, as the compiled exception handler table 2401 // may not be valid 2402 if (has_last_Java_frame()) { 2403 frame f = last_frame(); 2404 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2405 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2406 RegisterMap reg_map(this, UseBiasedLocking); 2407 frame compiled_frame = f.sender(®_map); 2408 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2409 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2410 } 2411 } 2412 } 2413 2414 // Set async. pending exception in thread. 2415 set_pending_async_exception(java_throwable); 2416 2417 if (log_is_enabled(Info, exceptions)) { 2418 ResourceMark rm; 2419 log_info(exceptions)("Pending Async. exception installed of type: %s", 2420 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2421 } 2422 // for AbortVMOnException flag 2423 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2424 } 2425 } 2426 2427 2428 // Interrupt thread so it will wake up from a potential wait()/sleep()/park() 2429 java_lang_Thread::set_interrupted(threadObj(), true); 2430 this->interrupt(); 2431 } 2432 2433 // External suspension mechanism. 2434 // 2435 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2436 // to any VM_locks and it is at a transition 2437 // Self-suspension will happen on the transition out of the vm. 2438 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2439 // 2440 // Guarantees on return: 2441 // + Target thread will not execute any new bytecode (that's why we need to 2442 // force a safepoint) 2443 // + Target thread will not enter any new monitors 2444 // 2445 void JavaThread::java_suspend() { 2446 ThreadsListHandle tlh; 2447 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2448 return; 2449 } 2450 2451 { MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2452 if (!is_external_suspend()) { 2453 // a racing resume has cancelled us; bail out now 2454 return; 2455 } 2456 2457 // suspend is done 2458 uint32_t debug_bits = 0; 2459 // Warning: is_ext_suspend_completed() may temporarily drop the 2460 // SR_lock to allow the thread to reach a stable thread state if 2461 // it is currently in a transient thread state. 2462 if (is_ext_suspend_completed(false /* !called_by_wait */, 2463 SuspendRetryDelay, &debug_bits)) { 2464 return; 2465 } 2466 } 2467 2468 if (Thread::current() == this) { 2469 // Safely self-suspend. 2470 // If we don't do this explicitly it will implicitly happen 2471 // before we transition back to Java, and on some other thread-state 2472 // transition paths, but not as we exit a JVM TI SuspendThread call. 2473 // As SuspendThread(current) must not return (until resumed) we must 2474 // self-suspend here. 2475 ThreadBlockInVM tbivm(this); 2476 java_suspend_self(); 2477 } else { 2478 VM_ThreadSuspend vm_suspend; 2479 VMThread::execute(&vm_suspend); 2480 } 2481 } 2482 2483 // Part II of external suspension. 2484 // A JavaThread self suspends when it detects a pending external suspend 2485 // request. This is usually on transitions. It is also done in places 2486 // where continuing to the next transition would surprise the caller, 2487 // e.g., monitor entry. 2488 // 2489 // Returns the number of times that the thread self-suspended. 2490 // 2491 // Note: DO NOT call java_suspend_self() when you just want to block current 2492 // thread. java_suspend_self() is the second stage of cooperative 2493 // suspension for external suspend requests and should only be used 2494 // to complete an external suspend request. 2495 // 2496 int JavaThread::java_suspend_self() { 2497 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2498 int ret = 0; 2499 2500 // we are in the process of exiting so don't suspend 2501 if (is_exiting()) { 2502 clear_external_suspend(); 2503 return ret; 2504 } 2505 2506 assert(_anchor.walkable() || 2507 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2508 "must have walkable stack"); 2509 2510 MonitorLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2511 2512 assert(!this->is_ext_suspended(), 2513 "a thread trying to self-suspend should not already be suspended"); 2514 2515 if (this->is_suspend_equivalent()) { 2516 // If we are self-suspending as a result of the lifting of a 2517 // suspend equivalent condition, then the suspend_equivalent 2518 // flag is not cleared until we set the ext_suspended flag so 2519 // that wait_for_ext_suspend_completion() returns consistent 2520 // results. 2521 this->clear_suspend_equivalent(); 2522 } 2523 2524 // A racing resume may have cancelled us before we grabbed SR_lock 2525 // above. Or another external suspend request could be waiting for us 2526 // by the time we return from SR_lock()->wait(). The thread 2527 // that requested the suspension may already be trying to walk our 2528 // stack and if we return now, we can change the stack out from under 2529 // it. This would be a "bad thing (TM)" and cause the stack walker 2530 // to crash. We stay self-suspended until there are no more pending 2531 // external suspend requests. 2532 while (is_external_suspend()) { 2533 ret++; 2534 this->set_ext_suspended(); 2535 2536 // _ext_suspended flag is cleared by java_resume() 2537 while (is_ext_suspended()) { 2538 ml.wait(); 2539 } 2540 } 2541 return ret; 2542 } 2543 2544 // Helper routine to set up the correct thread state before calling java_suspend_self. 2545 // This is called when regular thread-state transition helpers can't be used because 2546 // we can be in various states, in particular _thread_in_native_trans. 2547 // Because this thread is external suspended the safepoint code will count it as at 2548 // a safepoint, regardless of what its actual current thread-state is. But 2549 // is_ext_suspend_completed() may be waiting to see a thread transition from 2550 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2551 // to _thread_blocked. The problem with setting thread state directly is that a 2552 // safepoint could happen just after java_suspend_self() returns after being resumed, 2553 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2554 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2555 // However, not all initial-states are allowed when performing a safepoint check, as we 2556 // should never be blocking at a safepoint whilst in those states. Of these 'bad' states 2557 // only _thread_in_native is possible when executing this code (based on our two callers). 2558 // A thread that is _thread_in_native is already safepoint-safe and so it doesn't matter 2559 // whether the VMThread sees the _thread_blocked state, or the _thread_in_native state, 2560 // and so we don't need the explicit safepoint check. 2561 2562 void JavaThread::java_suspend_self_with_safepoint_check() { 2563 assert(this == Thread::current(), "invariant"); 2564 JavaThreadState state = thread_state(); 2565 set_thread_state(_thread_blocked); 2566 java_suspend_self(); 2567 set_thread_state_fence(state); 2568 // Since we are not using a regular thread-state transition helper here, 2569 // we must manually emit the instruction barrier after leaving a safe state. 2570 OrderAccess::cross_modify_fence(); 2571 if (state != _thread_in_native) { 2572 SafepointMechanism::block_if_requested(this); 2573 } 2574 } 2575 2576 #ifdef ASSERT 2577 // Verify the JavaThread has not yet been published in the Threads::list, and 2578 // hence doesn't need protection from concurrent access at this stage. 2579 void JavaThread::verify_not_published() { 2580 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2581 // since an unpublished JavaThread doesn't participate in the 2582 // Thread-SMR protocol for keeping a ThreadsList alive. 2583 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2584 } 2585 #endif 2586 2587 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2588 // progress or when _suspend_flags is non-zero. 2589 // Current thread needs to self-suspend if there is a suspend request and/or 2590 // block if a safepoint is in progress. 2591 // Async exception ISN'T checked. 2592 // Note only the ThreadInVMfromNative transition can call this function 2593 // directly and when thread state is _thread_in_native_trans 2594 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2595 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2596 2597 assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2598 2599 if (thread->is_external_suspend()) { 2600 thread->java_suspend_self_with_safepoint_check(); 2601 } else { 2602 SafepointMechanism::block_if_requested(thread); 2603 } 2604 2605 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2606 } 2607 2608 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2609 // progress or when _suspend_flags is non-zero. 2610 // Current thread needs to self-suspend if there is a suspend request and/or 2611 // block if a safepoint is in progress. 2612 // Also check for pending async exception (not including unsafe access error). 2613 // Note only the native==>VM/Java barriers can call this function and when 2614 // thread state is _thread_in_native_trans. 2615 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2616 check_safepoint_and_suspend_for_native_trans(thread); 2617 2618 if (thread->has_async_exception()) { 2619 // We are in _thread_in_native_trans state, don't handle unsafe 2620 // access error since that may block. 2621 thread->check_and_handle_async_exceptions(false); 2622 } 2623 } 2624 2625 // This is a variant of the normal 2626 // check_special_condition_for_native_trans with slightly different 2627 // semantics for use by critical native wrappers. It does all the 2628 // normal checks but also performs the transition back into 2629 // thread_in_Java state. This is required so that critical natives 2630 // can potentially block and perform a GC if they are the last thread 2631 // exiting the GCLocker. 2632 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2633 check_special_condition_for_native_trans(thread); 2634 2635 // Finish the transition 2636 thread->set_thread_state(_thread_in_Java); 2637 2638 if (thread->do_critical_native_unlock()) { 2639 ThreadInVMfromJavaNoAsyncException tiv(thread); 2640 GCLocker::unlock_critical(thread); 2641 thread->clear_critical_native_unlock(); 2642 } 2643 } 2644 2645 // We need to guarantee the Threads_lock here, since resumes are not 2646 // allowed during safepoint synchronization 2647 // Can only resume from an external suspension 2648 void JavaThread::java_resume() { 2649 assert_locked_or_safepoint(Threads_lock); 2650 2651 // Sanity check: thread is gone, has started exiting or the thread 2652 // was not externally suspended. 2653 ThreadsListHandle tlh; 2654 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2655 return; 2656 } 2657 2658 MutexLocker ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2659 2660 clear_external_suspend(); 2661 2662 if (is_ext_suspended()) { 2663 clear_ext_suspended(); 2664 SR_lock()->notify_all(); 2665 } 2666 } 2667 2668 size_t JavaThread::_stack_red_zone_size = 0; 2669 size_t JavaThread::_stack_yellow_zone_size = 0; 2670 size_t JavaThread::_stack_reserved_zone_size = 0; 2671 size_t JavaThread::_stack_shadow_zone_size = 0; 2672 2673 void JavaThread::create_stack_guard_pages() { 2674 if (!os::uses_stack_guard_pages() || 2675 _stack_guard_state != stack_guard_unused || 2676 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2677 log_info(os, thread)("Stack guard page creation for thread " 2678 UINTX_FORMAT " disabled", os::current_thread_id()); 2679 return; 2680 } 2681 address low_addr = stack_end(); 2682 size_t len = stack_guard_zone_size(); 2683 2684 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2685 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2686 2687 int must_commit = os::must_commit_stack_guard_pages(); 2688 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2689 2690 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2691 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2692 return; 2693 } 2694 2695 if (os::guard_memory((char *) low_addr, len)) { 2696 _stack_guard_state = stack_guard_enabled; 2697 } else { 2698 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2699 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2700 if (os::uncommit_memory((char *) low_addr, len)) { 2701 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2702 } 2703 return; 2704 } 2705 2706 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2707 PTR_FORMAT "-" PTR_FORMAT ".", 2708 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2709 } 2710 2711 void JavaThread::remove_stack_guard_pages() { 2712 assert(Thread::current() == this, "from different thread"); 2713 if (_stack_guard_state == stack_guard_unused) return; 2714 address low_addr = stack_end(); 2715 size_t len = stack_guard_zone_size(); 2716 2717 if (os::must_commit_stack_guard_pages()) { 2718 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2719 _stack_guard_state = stack_guard_unused; 2720 } else { 2721 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2722 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2723 return; 2724 } 2725 } else { 2726 if (_stack_guard_state == stack_guard_unused) return; 2727 if (os::unguard_memory((char *) low_addr, len)) { 2728 _stack_guard_state = stack_guard_unused; 2729 } else { 2730 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2731 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2732 return; 2733 } 2734 } 2735 2736 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2737 PTR_FORMAT "-" PTR_FORMAT ".", 2738 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2739 } 2740 2741 void JavaThread::enable_stack_reserved_zone() { 2742 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2743 2744 // The base notation is from the stack's point of view, growing downward. 2745 // We need to adjust it to work correctly with guard_memory() 2746 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2747 2748 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2749 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2750 2751 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2752 _stack_guard_state = stack_guard_enabled; 2753 } else { 2754 warning("Attempt to guard stack reserved zone failed."); 2755 } 2756 enable_register_stack_guard(); 2757 } 2758 2759 void JavaThread::disable_stack_reserved_zone() { 2760 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2761 2762 // Simply return if called for a thread that does not use guard pages. 2763 if (_stack_guard_state != stack_guard_enabled) return; 2764 2765 // The base notation is from the stack's point of view, growing downward. 2766 // We need to adjust it to work correctly with guard_memory() 2767 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2768 2769 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2770 _stack_guard_state = stack_guard_reserved_disabled; 2771 } else { 2772 warning("Attempt to unguard stack reserved zone failed."); 2773 } 2774 disable_register_stack_guard(); 2775 } 2776 2777 void JavaThread::enable_stack_yellow_reserved_zone() { 2778 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2779 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2780 2781 // The base notation is from the stacks point of view, growing downward. 2782 // We need to adjust it to work correctly with guard_memory() 2783 address base = stack_red_zone_base(); 2784 2785 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2786 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2787 2788 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2789 _stack_guard_state = stack_guard_enabled; 2790 } else { 2791 warning("Attempt to guard stack yellow zone failed."); 2792 } 2793 enable_register_stack_guard(); 2794 } 2795 2796 void JavaThread::disable_stack_yellow_reserved_zone() { 2797 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2798 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2799 2800 // Simply return if called for a thread that does not use guard pages. 2801 if (_stack_guard_state == stack_guard_unused) return; 2802 2803 // The base notation is from the stacks point of view, growing downward. 2804 // We need to adjust it to work correctly with guard_memory() 2805 address base = stack_red_zone_base(); 2806 2807 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2808 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2809 } else { 2810 warning("Attempt to unguard stack yellow zone failed."); 2811 } 2812 disable_register_stack_guard(); 2813 } 2814 2815 void JavaThread::enable_stack_red_zone() { 2816 // The base notation is from the stacks point of view, growing downward. 2817 // We need to adjust it to work correctly with guard_memory() 2818 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2819 address base = stack_red_zone_base() - stack_red_zone_size(); 2820 2821 guarantee(base < stack_base(), "Error calculating stack red zone"); 2822 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2823 2824 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2825 warning("Attempt to guard stack red zone failed."); 2826 } 2827 } 2828 2829 void JavaThread::disable_stack_red_zone() { 2830 // The base notation is from the stacks point of view, growing downward. 2831 // We need to adjust it to work correctly with guard_memory() 2832 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2833 address base = stack_red_zone_base() - stack_red_zone_size(); 2834 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2835 warning("Attempt to unguard stack red zone failed."); 2836 } 2837 } 2838 2839 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2840 // ignore is there is no stack 2841 if (!has_last_Java_frame()) return; 2842 // traverse the stack frames. Starts from top frame. 2843 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2844 frame* fr = fst.current(); 2845 f(fr, fst.register_map()); 2846 } 2847 } 2848 2849 2850 #ifndef PRODUCT 2851 // Deoptimization 2852 // Function for testing deoptimization 2853 void JavaThread::deoptimize() { 2854 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2855 StackFrameStream fst(this, UseBiasedLocking); 2856 bool deopt = false; // Dump stack only if a deopt actually happens. 2857 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2858 // Iterate over all frames in the thread and deoptimize 2859 for (; !fst.is_done(); fst.next()) { 2860 if (fst.current()->can_be_deoptimized()) { 2861 2862 if (only_at) { 2863 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2864 // consists of comma or carriage return separated numbers so 2865 // search for the current bci in that string. 2866 address pc = fst.current()->pc(); 2867 nmethod* nm = (nmethod*) fst.current()->cb(); 2868 ScopeDesc* sd = nm->scope_desc_at(pc); 2869 char buffer[8]; 2870 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2871 size_t len = strlen(buffer); 2872 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2873 while (found != NULL) { 2874 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2875 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2876 // Check that the bci found is bracketed by terminators. 2877 break; 2878 } 2879 found = strstr(found + 1, buffer); 2880 } 2881 if (!found) { 2882 continue; 2883 } 2884 } 2885 2886 if (DebugDeoptimization && !deopt) { 2887 deopt = true; // One-time only print before deopt 2888 tty->print_cr("[BEFORE Deoptimization]"); 2889 trace_frames(); 2890 trace_stack(); 2891 } 2892 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2893 } 2894 } 2895 2896 if (DebugDeoptimization && deopt) { 2897 tty->print_cr("[AFTER Deoptimization]"); 2898 trace_frames(); 2899 } 2900 } 2901 2902 2903 // Make zombies 2904 void JavaThread::make_zombies() { 2905 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2906 if (fst.current()->can_be_deoptimized()) { 2907 // it is a Java nmethod 2908 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2909 nm->make_not_entrant(); 2910 } 2911 } 2912 } 2913 #endif // PRODUCT 2914 2915 2916 void JavaThread::deoptimize_marked_methods() { 2917 if (!has_last_Java_frame()) return; 2918 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2919 StackFrameStream fst(this, UseBiasedLocking); 2920 for (; !fst.is_done(); fst.next()) { 2921 if (fst.current()->should_be_deoptimized()) { 2922 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2923 } 2924 } 2925 } 2926 2927 // If the caller is a NamedThread, then remember, in the current scope, 2928 // the given JavaThread in its _processed_thread field. 2929 class RememberProcessedThread: public StackObj { 2930 NamedThread* _cur_thr; 2931 public: 2932 RememberProcessedThread(JavaThread* jthr) { 2933 Thread* thread = Thread::current(); 2934 if (thread->is_Named_thread()) { 2935 _cur_thr = (NamedThread *)thread; 2936 _cur_thr->set_processed_thread(jthr); 2937 } else { 2938 _cur_thr = NULL; 2939 } 2940 } 2941 2942 ~RememberProcessedThread() { 2943 if (_cur_thr) { 2944 _cur_thr->set_processed_thread(NULL); 2945 } 2946 } 2947 }; 2948 2949 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2950 // Verify that the deferred card marks have been flushed. 2951 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2952 2953 // Traverse the GCHandles 2954 Thread::oops_do(f, cf); 2955 2956 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2957 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2958 2959 if (has_last_Java_frame()) { 2960 // Record JavaThread to GC thread 2961 RememberProcessedThread rpt(this); 2962 2963 // traverse the registered growable array 2964 if (_array_for_gc != NULL) { 2965 for (int index = 0; index < _array_for_gc->length(); index++) { 2966 f->do_oop(_array_for_gc->adr_at(index)); 2967 } 2968 } 2969 2970 // Traverse the monitor chunks 2971 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2972 chunk->oops_do(f); 2973 } 2974 2975 // Traverse the execution stack 2976 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2977 fst.current()->oops_do(f, cf, fst.register_map()); 2978 } 2979 } 2980 2981 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2982 // If we have deferred set_locals there might be oops waiting to be 2983 // written 2984 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2985 if (list != NULL) { 2986 for (int i = 0; i < list->length(); i++) { 2987 list->at(i)->oops_do(f); 2988 } 2989 } 2990 2991 // Traverse instance variables at the end since the GC may be moving things 2992 // around using this function 2993 f->do_oop((oop*) &_threadObj); 2994 f->do_oop((oop*) &_vm_result); 2995 f->do_oop((oop*) &_exception_oop); 2996 f->do_oop((oop*) &_pending_async_exception); 2997 2998 if (jvmti_thread_state() != NULL) { 2999 jvmti_thread_state()->oops_do(f); 3000 } 3001 } 3002 3003 #ifdef ASSERT 3004 void JavaThread::verify_states_for_handshake() { 3005 // This checks that the thread has a correct frame state during a handshake. 3006 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3007 (has_last_Java_frame() && java_call_counter() > 0), 3008 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3009 has_last_Java_frame(), java_call_counter()); 3010 } 3011 #endif 3012 3013 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 3014 assert((!has_last_Java_frame() && java_call_counter() == 0) || 3015 (has_last_Java_frame() && java_call_counter() > 0), 3016 "unexpected frame info: has_last_frame=%d, java_call_counter=%d", 3017 has_last_Java_frame(), java_call_counter()); 3018 3019 if (has_last_Java_frame()) { 3020 // Traverse the execution stack 3021 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3022 fst.current()->nmethods_do(cf); 3023 } 3024 } 3025 } 3026 3027 void JavaThread::metadata_do(MetadataClosure* f) { 3028 if (has_last_Java_frame()) { 3029 // Traverse the execution stack to call f() on the methods in the stack 3030 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3031 fst.current()->metadata_do(f); 3032 } 3033 } else if (is_Compiler_thread()) { 3034 // need to walk ciMetadata in current compile tasks to keep alive. 3035 CompilerThread* ct = (CompilerThread*)this; 3036 if (ct->env() != NULL) { 3037 ct->env()->metadata_do(f); 3038 } 3039 CompileTask* task = ct->task(); 3040 if (task != NULL) { 3041 task->metadata_do(f); 3042 } 3043 } 3044 } 3045 3046 // Printing 3047 const char* _get_thread_state_name(JavaThreadState _thread_state) { 3048 switch (_thread_state) { 3049 case _thread_uninitialized: return "_thread_uninitialized"; 3050 case _thread_new: return "_thread_new"; 3051 case _thread_new_trans: return "_thread_new_trans"; 3052 case _thread_in_native: return "_thread_in_native"; 3053 case _thread_in_native_trans: return "_thread_in_native_trans"; 3054 case _thread_in_vm: return "_thread_in_vm"; 3055 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 3056 case _thread_in_Java: return "_thread_in_Java"; 3057 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 3058 case _thread_blocked: return "_thread_blocked"; 3059 case _thread_blocked_trans: return "_thread_blocked_trans"; 3060 default: return "unknown thread state"; 3061 } 3062 } 3063 3064 #ifndef PRODUCT 3065 void JavaThread::print_thread_state_on(outputStream *st) const { 3066 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 3067 }; 3068 #endif // PRODUCT 3069 3070 // Called by Threads::print() for VM_PrintThreads operation 3071 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 3072 st->print_raw("\""); 3073 st->print_raw(get_thread_name()); 3074 st->print_raw("\" "); 3075 oop thread_oop = threadObj(); 3076 if (thread_oop != NULL) { 3077 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 3078 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 3079 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 3080 } 3081 Thread::print_on(st, print_extended_info); 3082 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 3083 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 3084 if (thread_oop != NULL) { 3085 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 3086 } 3087 #ifndef PRODUCT 3088 _safepoint_state->print_on(st); 3089 #endif // PRODUCT 3090 if (is_Compiler_thread()) { 3091 CompileTask *task = ((CompilerThread*)this)->task(); 3092 if (task != NULL) { 3093 st->print(" Compiling: "); 3094 task->print(st, NULL, true, false); 3095 } else { 3096 st->print(" No compile task"); 3097 } 3098 st->cr(); 3099 } 3100 } 3101 3102 void JavaThread::print() const { print_on(tty); } 3103 3104 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3105 st->print("%s", get_thread_name_string(buf, buflen)); 3106 } 3107 3108 // Called by fatal error handler. The difference between this and 3109 // JavaThread::print() is that we can't grab lock or allocate memory. 3110 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3111 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3112 oop thread_obj = threadObj(); 3113 if (thread_obj != NULL) { 3114 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3115 } 3116 st->print(" ["); 3117 st->print("%s", _get_thread_state_name(_thread_state)); 3118 if (osthread()) { 3119 st->print(", id=%d", osthread()->thread_id()); 3120 } 3121 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3122 p2i(stack_end()), p2i(stack_base())); 3123 st->print("]"); 3124 3125 ThreadsSMRSupport::print_info_on(this, st); 3126 return; 3127 } 3128 3129 // Verification 3130 3131 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3132 3133 void JavaThread::verify() { 3134 // Verify oops in the thread. 3135 oops_do(&VerifyOopClosure::verify_oop, NULL); 3136 3137 // Verify the stack frames. 3138 frames_do(frame_verify); 3139 } 3140 3141 // CR 6300358 (sub-CR 2137150) 3142 // Most callers of this method assume that it can't return NULL but a 3143 // thread may not have a name whilst it is in the process of attaching to 3144 // the VM - see CR 6412693, and there are places where a JavaThread can be 3145 // seen prior to having it's threadObj set (eg JNI attaching threads and 3146 // if vm exit occurs during initialization). These cases can all be accounted 3147 // for such that this method never returns NULL. 3148 const char* JavaThread::get_thread_name() const { 3149 #ifdef ASSERT 3150 // early safepoints can hit while current thread does not yet have TLS 3151 if (!SafepointSynchronize::is_at_safepoint()) { 3152 Thread *cur = Thread::current(); 3153 if (!(cur->is_Java_thread() && cur == this)) { 3154 // Current JavaThreads are allowed to get their own name without 3155 // the Threads_lock. 3156 assert_locked_or_safepoint(Threads_lock); 3157 } 3158 } 3159 #endif // ASSERT 3160 return get_thread_name_string(); 3161 } 3162 3163 // Returns a non-NULL representation of this thread's name, or a suitable 3164 // descriptive string if there is no set name 3165 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3166 const char* name_str; 3167 oop thread_obj = threadObj(); 3168 if (thread_obj != NULL) { 3169 oop name = java_lang_Thread::name(thread_obj); 3170 if (name != NULL) { 3171 if (buf == NULL) { 3172 name_str = java_lang_String::as_utf8_string(name); 3173 } else { 3174 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3175 } 3176 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3177 name_str = "<no-name - thread is attaching>"; 3178 } else { 3179 name_str = Thread::name(); 3180 } 3181 } else { 3182 name_str = Thread::name(); 3183 } 3184 assert(name_str != NULL, "unexpected NULL thread name"); 3185 return name_str; 3186 } 3187 3188 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3189 3190 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3191 assert(NoPriority <= prio && prio <= MaxPriority, "sanity check"); 3192 // Link Java Thread object <-> C++ Thread 3193 3194 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3195 // and put it into a new Handle. The Handle "thread_oop" can then 3196 // be used to pass the C++ thread object to other methods. 3197 3198 // Set the Java level thread object (jthread) field of the 3199 // new thread (a JavaThread *) to C++ thread object using the 3200 // "thread_oop" handle. 3201 3202 // Set the thread field (a JavaThread *) of the 3203 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3204 3205 Handle thread_oop(Thread::current(), 3206 JNIHandles::resolve_non_null(jni_thread)); 3207 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3208 "must be initialized"); 3209 set_threadObj(thread_oop()); 3210 java_lang_Thread::set_thread(thread_oop(), this); 3211 3212 if (prio == NoPriority) { 3213 prio = java_lang_Thread::priority(thread_oop()); 3214 assert(prio != NoPriority, "A valid priority should be present"); 3215 } 3216 3217 // Push the Java priority down to the native thread; needs Threads_lock 3218 Thread::set_priority(this, prio); 3219 3220 // Add the new thread to the Threads list and set it in motion. 3221 // We must have threads lock in order to call Threads::add. 3222 // It is crucial that we do not block before the thread is 3223 // added to the Threads list for if a GC happens, then the java_thread oop 3224 // will not be visited by GC. 3225 Threads::add(this); 3226 } 3227 3228 oop JavaThread::current_park_blocker() { 3229 // Support for JSR-166 locks 3230 oop thread_oop = threadObj(); 3231 if (thread_oop != NULL) { 3232 return java_lang_Thread::park_blocker(thread_oop); 3233 } 3234 return NULL; 3235 } 3236 3237 3238 void JavaThread::print_stack_on(outputStream* st) { 3239 if (!has_last_Java_frame()) return; 3240 ResourceMark rm; 3241 HandleMark hm; 3242 3243 RegisterMap reg_map(this); 3244 vframe* start_vf = last_java_vframe(®_map); 3245 int count = 0; 3246 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3247 if (f->is_java_frame()) { 3248 javaVFrame* jvf = javaVFrame::cast(f); 3249 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3250 3251 // Print out lock information 3252 if (JavaMonitorsInStackTrace) { 3253 jvf->print_lock_info_on(st, count); 3254 } 3255 } else { 3256 // Ignore non-Java frames 3257 } 3258 3259 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3260 count++; 3261 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3262 } 3263 } 3264 3265 3266 // JVMTI PopFrame support 3267 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3268 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3269 if (in_bytes(size_in_bytes) != 0) { 3270 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3271 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3272 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3273 } 3274 } 3275 3276 void* JavaThread::popframe_preserved_args() { 3277 return _popframe_preserved_args; 3278 } 3279 3280 ByteSize JavaThread::popframe_preserved_args_size() { 3281 return in_ByteSize(_popframe_preserved_args_size); 3282 } 3283 3284 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3285 int sz = in_bytes(popframe_preserved_args_size()); 3286 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3287 return in_WordSize(sz / wordSize); 3288 } 3289 3290 void JavaThread::popframe_free_preserved_args() { 3291 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3292 FREE_C_HEAP_ARRAY(char, (char*)_popframe_preserved_args); 3293 _popframe_preserved_args = NULL; 3294 _popframe_preserved_args_size = 0; 3295 } 3296 3297 #ifndef PRODUCT 3298 3299 void JavaThread::trace_frames() { 3300 tty->print_cr("[Describe stack]"); 3301 int frame_no = 1; 3302 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3303 tty->print(" %d. ", frame_no++); 3304 fst.current()->print_value_on(tty, this); 3305 tty->cr(); 3306 } 3307 } 3308 3309 class PrintAndVerifyOopClosure: public OopClosure { 3310 protected: 3311 template <class T> inline void do_oop_work(T* p) { 3312 oop obj = RawAccess<>::oop_load(p); 3313 if (obj == NULL) return; 3314 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3315 if (oopDesc::is_oop_or_null(obj)) { 3316 if (obj->is_objArray()) { 3317 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3318 } else { 3319 obj->print(); 3320 } 3321 } else { 3322 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3323 } 3324 tty->cr(); 3325 } 3326 public: 3327 virtual void do_oop(oop* p) { do_oop_work(p); } 3328 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3329 }; 3330 3331 #ifdef ASSERT 3332 // Print or validate the layout of stack frames 3333 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3334 ResourceMark rm; 3335 PRESERVE_EXCEPTION_MARK; 3336 FrameValues values; 3337 int frame_no = 0; 3338 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3339 fst.current()->describe(values, ++frame_no); 3340 if (depth == frame_no) break; 3341 } 3342 if (validate_only) { 3343 values.validate(); 3344 } else { 3345 tty->print_cr("[Describe stack layout]"); 3346 values.print(this); 3347 } 3348 } 3349 #endif 3350 3351 void JavaThread::trace_stack_from(vframe* start_vf) { 3352 ResourceMark rm; 3353 int vframe_no = 1; 3354 for (vframe* f = start_vf; f; f = f->sender()) { 3355 if (f->is_java_frame()) { 3356 javaVFrame::cast(f)->print_activation(vframe_no++); 3357 } else { 3358 f->print(); 3359 } 3360 if (vframe_no > StackPrintLimit) { 3361 tty->print_cr("...<more frames>..."); 3362 return; 3363 } 3364 } 3365 } 3366 3367 3368 void JavaThread::trace_stack() { 3369 if (!has_last_Java_frame()) return; 3370 ResourceMark rm; 3371 HandleMark hm; 3372 RegisterMap reg_map(this); 3373 trace_stack_from(last_java_vframe(®_map)); 3374 } 3375 3376 3377 #endif // PRODUCT 3378 3379 3380 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3381 assert(reg_map != NULL, "a map must be given"); 3382 frame f = last_frame(); 3383 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3384 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3385 } 3386 return NULL; 3387 } 3388 3389 3390 Klass* JavaThread::security_get_caller_class(int depth) { 3391 vframeStream vfst(this); 3392 vfst.security_get_caller_frame(depth); 3393 if (!vfst.at_end()) { 3394 return vfst.method()->method_holder(); 3395 } 3396 return NULL; 3397 } 3398 3399 // java.lang.Thread.sleep support 3400 // Returns true if sleep time elapsed as expected, and false 3401 // if the thread was interrupted. 3402 bool JavaThread::sleep(jlong millis) { 3403 assert(this == Thread::current(), "thread consistency check"); 3404 3405 ParkEvent * const slp = this->_SleepEvent; 3406 // Because there can be races with thread interruption sending an unpark() 3407 // to the event, we explicitly reset it here to avoid an immediate return. 3408 // The actual interrupt state will be checked before we park(). 3409 slp->reset(); 3410 // Thread interruption establishes a happens-before ordering in the 3411 // Java Memory Model, so we need to ensure we synchronize with the 3412 // interrupt state. 3413 OrderAccess::fence(); 3414 3415 jlong prevtime = os::javaTimeNanos(); 3416 3417 for (;;) { 3418 // interruption has precedence over timing out 3419 if (this->is_interrupted(true)) { 3420 return false; 3421 } 3422 3423 if (millis <= 0) { 3424 return true; 3425 } 3426 3427 { 3428 ThreadBlockInVM tbivm(this); 3429 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 3430 3431 this->set_suspend_equivalent(); 3432 // cleared by handle_special_suspend_equivalent_condition() or 3433 // java_suspend_self() via check_and_wait_while_suspended() 3434 3435 slp->park(millis); 3436 3437 // were we externally suspended while we were waiting? 3438 this->check_and_wait_while_suspended(); 3439 } 3440 3441 // Update elapsed time tracking 3442 jlong newtime = os::javaTimeNanos(); 3443 if (newtime - prevtime < 0) { 3444 // time moving backwards, should only happen if no monotonic clock 3445 // not a guarantee() because JVM should not abort on kernel/glibc bugs 3446 assert(!os::supports_monotonic_clock(), 3447 "unexpected time moving backwards detected in JavaThread::sleep()"); 3448 } else { 3449 millis -= (newtime - prevtime) / NANOSECS_PER_MILLISEC; 3450 } 3451 prevtime = newtime; 3452 } 3453 } 3454 3455 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3456 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3457 CompileBroker::compiler_thread_loop(); 3458 } 3459 3460 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3461 NMethodSweeper::sweeper_loop(); 3462 } 3463 3464 // Create a CompilerThread 3465 CompilerThread::CompilerThread(CompileQueue* queue, 3466 CompilerCounters* counters) 3467 : JavaThread(&compiler_thread_entry) { 3468 _env = NULL; 3469 _log = NULL; 3470 _task = NULL; 3471 _queue = queue; 3472 _counters = counters; 3473 _buffer_blob = NULL; 3474 _compiler = NULL; 3475 3476 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3477 resource_area()->bias_to(mtCompiler); 3478 3479 #ifndef PRODUCT 3480 _ideal_graph_printer = NULL; 3481 #endif 3482 } 3483 3484 CompilerThread::~CompilerThread() { 3485 // Delete objects which were allocated on heap. 3486 delete _counters; 3487 } 3488 3489 bool CompilerThread::can_call_java() const { 3490 return _compiler != NULL && _compiler->is_jvmci(); 3491 } 3492 3493 // Create sweeper thread 3494 CodeCacheSweeperThread::CodeCacheSweeperThread() 3495 : JavaThread(&sweeper_thread_entry) { 3496 _scanned_compiled_method = NULL; 3497 } 3498 3499 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3500 JavaThread::oops_do(f, cf); 3501 if (_scanned_compiled_method != NULL && cf != NULL) { 3502 // Safepoints can occur when the sweeper is scanning an nmethod so 3503 // process it here to make sure it isn't unloaded in the middle of 3504 // a scan. 3505 cf->do_code_blob(_scanned_compiled_method); 3506 } 3507 } 3508 3509 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3510 JavaThread::nmethods_do(cf); 3511 if (_scanned_compiled_method != NULL && cf != NULL) { 3512 // Safepoints can occur when the sweeper is scanning an nmethod so 3513 // process it here to make sure it isn't unloaded in the middle of 3514 // a scan. 3515 cf->do_code_blob(_scanned_compiled_method); 3516 } 3517 } 3518 3519 3520 // ======= Threads ======== 3521 3522 // The Threads class links together all active threads, and provides 3523 // operations over all threads. It is protected by the Threads_lock, 3524 // which is also used in other global contexts like safepointing. 3525 // ThreadsListHandles are used to safely perform operations on one 3526 // or more threads without the risk of the thread exiting during the 3527 // operation. 3528 // 3529 // Note: The Threads_lock is currently more widely used than we 3530 // would like. We are actively migrating Threads_lock uses to other 3531 // mechanisms in order to reduce Threads_lock contention. 3532 3533 int Threads::_number_of_threads = 0; 3534 int Threads::_number_of_non_daemon_threads = 0; 3535 int Threads::_return_code = 0; 3536 uintx Threads::_thread_claim_token = 1; // Never zero. 3537 size_t JavaThread::_stack_size_at_create = 0; 3538 3539 #ifdef ASSERT 3540 bool Threads::_vm_complete = false; 3541 #endif 3542 3543 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3544 Prefetch::read((void*)addr, prefetch_interval); 3545 return *addr; 3546 } 3547 3548 // Possibly the ugliest for loop the world has seen. C++ does not allow 3549 // multiple types in the declaration section of the for loop. In this case 3550 // we are only dealing with pointers and hence can cast them. It looks ugly 3551 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3552 #define DO_JAVA_THREADS(LIST, X) \ 3553 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3554 *MACRO_list = (JavaThread*)(LIST), \ 3555 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3556 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3557 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3558 MACRO_current_p != MACRO_end; \ 3559 MACRO_current_p++, \ 3560 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3561 3562 // All JavaThreads 3563 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3564 3565 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3566 void Threads::non_java_threads_do(ThreadClosure* tc) { 3567 NoSafepointVerifier nsv; 3568 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3569 tc->do_thread(njti.current()); 3570 } 3571 } 3572 3573 // All JavaThreads 3574 void Threads::java_threads_do(ThreadClosure* tc) { 3575 assert_locked_or_safepoint(Threads_lock); 3576 // ALL_JAVA_THREADS iterates through all JavaThreads. 3577 ALL_JAVA_THREADS(p) { 3578 tc->do_thread(p); 3579 } 3580 } 3581 3582 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3583 assert_locked_or_safepoint(Threads_lock); 3584 java_threads_do(tc); 3585 tc->do_thread(VMThread::vm_thread()); 3586 } 3587 3588 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3589 void Threads::threads_do(ThreadClosure* tc) { 3590 assert_locked_or_safepoint(Threads_lock); 3591 java_threads_do(tc); 3592 non_java_threads_do(tc); 3593 } 3594 3595 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3596 uintx claim_token = Threads::thread_claim_token(); 3597 ALL_JAVA_THREADS(p) { 3598 if (p->claim_threads_do(is_par, claim_token)) { 3599 tc->do_thread(p); 3600 } 3601 } 3602 VMThread* vmt = VMThread::vm_thread(); 3603 if (vmt->claim_threads_do(is_par, claim_token)) { 3604 tc->do_thread(vmt); 3605 } 3606 } 3607 3608 // The system initialization in the library has three phases. 3609 // 3610 // Phase 1: java.lang.System class initialization 3611 // java.lang.System is a primordial class loaded and initialized 3612 // by the VM early during startup. java.lang.System.<clinit> 3613 // only does registerNatives and keeps the rest of the class 3614 // initialization work later until thread initialization completes. 3615 // 3616 // System.initPhase1 initializes the system properties, the static 3617 // fields in, out, and err. Set up java signal handlers, OS-specific 3618 // system settings, and thread group of the main thread. 3619 static void call_initPhase1(TRAPS) { 3620 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3621 JavaValue result(T_VOID); 3622 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3623 vmSymbols::void_method_signature(), CHECK); 3624 } 3625 3626 // Phase 2. Module system initialization 3627 // This will initialize the module system. Only java.base classes 3628 // can be loaded until phase 2 completes. 3629 // 3630 // Call System.initPhase2 after the compiler initialization and jsr292 3631 // classes get initialized because module initialization runs a lot of java 3632 // code, that for performance reasons, should be compiled. Also, this will 3633 // enable the startup code to use lambda and other language features in this 3634 // phase and onward. 3635 // 3636 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3637 static void call_initPhase2(TRAPS) { 3638 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3639 3640 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3641 3642 JavaValue result(T_INT); 3643 JavaCallArguments args; 3644 args.push_int(DisplayVMOutputToStderr); 3645 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3646 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3647 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3648 if (result.get_jint() != JNI_OK) { 3649 vm_exit_during_initialization(); // no message or exception 3650 } 3651 3652 universe_post_module_init(); 3653 } 3654 3655 // Phase 3. final setup - set security manager, system class loader and TCCL 3656 // 3657 // This will instantiate and set the security manager, set the system class 3658 // loader as well as the thread context class loader. The security manager 3659 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3660 // other modules or the application's classpath. 3661 static void call_initPhase3(TRAPS) { 3662 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3663 JavaValue result(T_VOID); 3664 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3665 vmSymbols::void_method_signature(), CHECK); 3666 } 3667 3668 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3669 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3670 3671 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3672 create_vm_init_libraries(); 3673 } 3674 3675 initialize_class(vmSymbols::java_lang_String(), CHECK); 3676 3677 // Inject CompactStrings value after the static initializers for String ran. 3678 java_lang_String::set_compact_strings(CompactStrings); 3679 3680 // Initialize java_lang.System (needed before creating the thread) 3681 initialize_class(vmSymbols::java_lang_System(), CHECK); 3682 // The VM creates & returns objects of this class. Make sure it's initialized. 3683 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3684 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3685 Handle thread_group = create_initial_thread_group(CHECK); 3686 Universe::set_main_thread_group(thread_group()); 3687 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3688 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3689 main_thread->set_threadObj(thread_object); 3690 3691 // Set thread status to running since main thread has 3692 // been started and running. 3693 java_lang_Thread::set_thread_status(thread_object, 3694 java_lang_Thread::RUNNABLE); 3695 3696 // The VM creates objects of this class. 3697 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3698 3699 #ifdef ASSERT 3700 InstanceKlass *k = SystemDictionary::UnsafeConstants_klass(); 3701 assert(k->is_not_initialized(), "UnsafeConstants should not already be initialized"); 3702 #endif 3703 3704 // initialize the hardware-specific constants needed by Unsafe 3705 initialize_class(vmSymbols::jdk_internal_misc_UnsafeConstants(), CHECK); 3706 jdk_internal_misc_UnsafeConstants::set_unsafe_constants(); 3707 3708 // The VM preresolves methods to these classes. Make sure that they get initialized 3709 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3710 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3711 3712 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3713 call_initPhase1(CHECK); 3714 3715 // get the Java runtime name, version, and vendor info after java.lang.System is initialized 3716 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3717 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3718 JDK_Version::set_runtime_vendor_version(get_java_runtime_vendor_version(THREAD)); 3719 JDK_Version::set_runtime_vendor_vm_bug_url(get_java_runtime_vendor_vm_bug_url(THREAD)); 3720 3721 // an instance of OutOfMemory exception has been allocated earlier 3722 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3723 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3724 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3725 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3726 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3727 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3728 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3729 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3730 3731 // Eager box cache initialization only if AOT is on and any library is loaded. 3732 AOTLoader::initialize_box_caches(CHECK); 3733 } 3734 3735 void Threads::initialize_jsr292_core_classes(TRAPS) { 3736 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3737 3738 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3739 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3740 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3741 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3742 } 3743 3744 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3745 extern void JDK_Version_init(); 3746 3747 // Preinitialize version info. 3748 VM_Version::early_initialize(); 3749 3750 // Check version 3751 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3752 3753 // Initialize library-based TLS 3754 ThreadLocalStorage::init(); 3755 3756 // Initialize the output stream module 3757 ostream_init(); 3758 3759 // Process java launcher properties. 3760 Arguments::process_sun_java_launcher_properties(args); 3761 3762 // Initialize the os module 3763 os::init(); 3764 3765 // Record VM creation timing statistics 3766 TraceVmCreationTime create_vm_timer; 3767 create_vm_timer.start(); 3768 3769 // Initialize system properties. 3770 Arguments::init_system_properties(); 3771 3772 // So that JDK version can be used as a discriminator when parsing arguments 3773 JDK_Version_init(); 3774 3775 // Update/Initialize System properties after JDK version number is known 3776 Arguments::init_version_specific_system_properties(); 3777 3778 // Make sure to initialize log configuration *before* parsing arguments 3779 LogConfiguration::initialize(create_vm_timer.begin_time()); 3780 3781 // Parse arguments 3782 // Note: this internally calls os::init_container_support() 3783 jint parse_result = Arguments::parse(args); 3784 if (parse_result != JNI_OK) return parse_result; 3785 3786 os::init_before_ergo(); 3787 3788 jint ergo_result = Arguments::apply_ergo(); 3789 if (ergo_result != JNI_OK) return ergo_result; 3790 3791 // Final check of all ranges after ergonomics which may change values. 3792 if (!JVMFlagRangeList::check_ranges()) { 3793 return JNI_EINVAL; 3794 } 3795 3796 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3797 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3798 if (!constraint_result) { 3799 return JNI_EINVAL; 3800 } 3801 3802 JVMFlagWriteableList::mark_startup(); 3803 3804 if (PauseAtStartup) { 3805 os::pause(); 3806 } 3807 3808 HOTSPOT_VM_INIT_BEGIN(); 3809 3810 // Timing (must come after argument parsing) 3811 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3812 3813 // Initialize the os module after parsing the args 3814 jint os_init_2_result = os::init_2(); 3815 if (os_init_2_result != JNI_OK) return os_init_2_result; 3816 3817 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3818 // Initialize assert poison page mechanism. 3819 if (ShowRegistersOnAssert) { 3820 initialize_assert_poison(); 3821 } 3822 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3823 3824 SafepointMechanism::initialize(); 3825 3826 jint adjust_after_os_result = Arguments::adjust_after_os(); 3827 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3828 3829 // Initialize output stream logging 3830 ostream_init_log(); 3831 3832 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3833 // Must be before create_vm_init_agents() 3834 if (Arguments::init_libraries_at_startup()) { 3835 convert_vm_init_libraries_to_agents(); 3836 } 3837 3838 // Launch -agentlib/-agentpath and converted -Xrun agents 3839 if (Arguments::init_agents_at_startup()) { 3840 create_vm_init_agents(); 3841 } 3842 3843 // Initialize Threads state 3844 _number_of_threads = 0; 3845 _number_of_non_daemon_threads = 0; 3846 3847 // Initialize global data structures and create system classes in heap 3848 vm_init_globals(); 3849 3850 #if INCLUDE_JVMCI 3851 if (JVMCICounterSize > 0) { 3852 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtJVMCI); 3853 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3854 } else { 3855 JavaThread::_jvmci_old_thread_counters = NULL; 3856 } 3857 #endif // INCLUDE_JVMCI 3858 3859 // Attach the main thread to this os thread 3860 JavaThread* main_thread = new JavaThread(); 3861 main_thread->set_thread_state(_thread_in_vm); 3862 main_thread->initialize_thread_current(); 3863 // must do this before set_active_handles 3864 main_thread->record_stack_base_and_size(); 3865 main_thread->register_thread_stack_with_NMT(); 3866 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3867 3868 if (!main_thread->set_as_starting_thread()) { 3869 vm_shutdown_during_initialization( 3870 "Failed necessary internal allocation. Out of swap space"); 3871 main_thread->smr_delete(); 3872 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3873 return JNI_ENOMEM; 3874 } 3875 3876 // Enable guard page *after* os::create_main_thread(), otherwise it would 3877 // crash Linux VM, see notes in os_linux.cpp. 3878 main_thread->create_stack_guard_pages(); 3879 3880 // Initialize Java-Level synchronization subsystem 3881 ObjectMonitor::Initialize(); 3882 3883 // Initialize global modules 3884 jint status = init_globals(); 3885 if (status != JNI_OK) { 3886 main_thread->smr_delete(); 3887 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3888 return status; 3889 } 3890 3891 JFR_ONLY(Jfr::on_create_vm_1();) 3892 3893 // Should be done after the heap is fully created 3894 main_thread->cache_global_variables(); 3895 3896 HandleMark hm; 3897 3898 { MutexLocker mu(Threads_lock); 3899 Threads::add(main_thread); 3900 } 3901 3902 // Any JVMTI raw monitors entered in onload will transition into 3903 // real raw monitor. VM is setup enough here for raw monitor enter. 3904 JvmtiExport::transition_pending_onload_raw_monitors(); 3905 3906 // Create the VMThread 3907 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3908 3909 VMThread::create(); 3910 Thread* vmthread = VMThread::vm_thread(); 3911 3912 if (!os::create_thread(vmthread, os::vm_thread)) { 3913 vm_exit_during_initialization("Cannot create VM thread. " 3914 "Out of system resources."); 3915 } 3916 3917 // Wait for the VM thread to become ready, and VMThread::run to initialize 3918 // Monitors can have spurious returns, must always check another state flag 3919 { 3920 MonitorLocker ml(Notify_lock); 3921 os::start_thread(vmthread); 3922 while (vmthread->active_handles() == NULL) { 3923 ml.wait(); 3924 } 3925 } 3926 } 3927 3928 assert(Universe::is_fully_initialized(), "not initialized"); 3929 if (VerifyDuringStartup) { 3930 // Make sure we're starting with a clean slate. 3931 VM_Verify verify_op; 3932 VMThread::execute(&verify_op); 3933 } 3934 3935 // We need this to update the java.vm.info property in case any flags used 3936 // to initially define it have been changed. This is needed for both CDS and 3937 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3938 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3939 // This update must happen before we initialize the java classes, but 3940 // after any initialization logic that might modify the flags. 3941 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3942 3943 Thread* THREAD = Thread::current(); 3944 3945 // Always call even when there are not JVMTI environments yet, since environments 3946 // may be attached late and JVMTI must track phases of VM execution 3947 JvmtiExport::enter_early_start_phase(); 3948 3949 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3950 JvmtiExport::post_early_vm_start(); 3951 3952 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3953 3954 quicken_jni_functions(); 3955 3956 // No more stub generation allowed after that point. 3957 StubCodeDesc::freeze(); 3958 3959 // Set flag that basic initialization has completed. Used by exceptions and various 3960 // debug stuff, that does not work until all basic classes have been initialized. 3961 set_init_completed(); 3962 3963 LogConfiguration::post_initialize(); 3964 Metaspace::post_initialize(); 3965 3966 HOTSPOT_VM_INIT_END(); 3967 3968 // record VM initialization completion time 3969 #if INCLUDE_MANAGEMENT 3970 Management::record_vm_init_completed(); 3971 #endif // INCLUDE_MANAGEMENT 3972 3973 // Signal Dispatcher needs to be started before VMInit event is posted 3974 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3975 3976 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3977 if (!DisableAttachMechanism) { 3978 AttachListener::vm_start(); 3979 if (StartAttachListener || AttachListener::init_at_startup()) { 3980 AttachListener::init(); 3981 } 3982 } 3983 3984 // Launch -Xrun agents 3985 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3986 // back-end can launch with -Xdebug -Xrunjdwp. 3987 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3988 create_vm_init_libraries(); 3989 } 3990 3991 if (CleanChunkPoolAsync) { 3992 Chunk::start_chunk_pool_cleaner_task(); 3993 } 3994 3995 3996 // initialize compiler(s) 3997 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3998 #if INCLUDE_JVMCI 3999 bool force_JVMCI_intialization = false; 4000 if (EnableJVMCI) { 4001 // Initialize JVMCI eagerly when it is explicitly requested. 4002 // Or when JVMCILibDumpJNIConfig or JVMCIPrintProperties is enabled. 4003 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties || JVMCILibDumpJNIConfig; 4004 4005 if (!force_JVMCI_intialization) { 4006 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 4007 // compilations via JVMCI will not actually block until JVMCI is initialized. 4008 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 4009 } 4010 } 4011 #endif 4012 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 4013 // Postpone completion of compiler initialization to after JVMCI 4014 // is initialized to avoid timeouts of blocking compilations. 4015 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 4016 CompileBroker::compilation_init_phase2(); 4017 } 4018 #endif 4019 4020 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 4021 // It is done after compilers are initialized, because otherwise compilations of 4022 // signature polymorphic MH intrinsics can be missed 4023 // (see SystemDictionary::find_method_handle_intrinsic). 4024 initialize_jsr292_core_classes(CHECK_JNI_ERR); 4025 4026 // This will initialize the module system. Only java.base classes can be 4027 // loaded until phase 2 completes 4028 call_initPhase2(CHECK_JNI_ERR); 4029 4030 JFR_ONLY(Jfr::on_create_vm_2();) 4031 4032 // Always call even when there are not JVMTI environments yet, since environments 4033 // may be attached late and JVMTI must track phases of VM execution 4034 JvmtiExport::enter_start_phase(); 4035 4036 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 4037 JvmtiExport::post_vm_start(); 4038 4039 // Final system initialization including security manager and system class loader 4040 call_initPhase3(CHECK_JNI_ERR); 4041 4042 // cache the system and platform class loaders 4043 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 4044 4045 #if INCLUDE_CDS 4046 // capture the module path info from the ModuleEntryTable 4047 ClassLoader::initialize_module_path(THREAD); 4048 #endif 4049 4050 #if INCLUDE_JVMCI 4051 if (force_JVMCI_intialization) { 4052 JVMCI::initialize_compiler(CHECK_JNI_ERR); 4053 CompileBroker::compilation_init_phase2(); 4054 } 4055 #endif 4056 4057 // Always call even when there are not JVMTI environments yet, since environments 4058 // may be attached late and JVMTI must track phases of VM execution 4059 JvmtiExport::enter_live_phase(); 4060 4061 // Make perfmemory accessible 4062 PerfMemory::set_accessible(true); 4063 4064 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 4065 JvmtiExport::post_vm_initialized(); 4066 4067 JFR_ONLY(Jfr::on_create_vm_3();) 4068 4069 #if INCLUDE_MANAGEMENT 4070 Management::initialize(THREAD); 4071 4072 if (HAS_PENDING_EXCEPTION) { 4073 // management agent fails to start possibly due to 4074 // configuration problem and is responsible for printing 4075 // stack trace if appropriate. Simply exit VM. 4076 vm_exit(1); 4077 } 4078 #endif // INCLUDE_MANAGEMENT 4079 4080 if (MemProfiling) MemProfiler::engage(); 4081 StatSampler::engage(); 4082 if (CheckJNICalls) JniPeriodicChecker::engage(); 4083 4084 BiasedLocking::init(); 4085 4086 #if INCLUDE_RTM_OPT 4087 RTMLockingCounters::init(); 4088 #endif 4089 4090 call_postVMInitHook(THREAD); 4091 // The Java side of PostVMInitHook.run must deal with all 4092 // exceptions and provide means of diagnosis. 4093 if (HAS_PENDING_EXCEPTION) { 4094 CLEAR_PENDING_EXCEPTION; 4095 } 4096 4097 { 4098 MutexLocker ml(PeriodicTask_lock); 4099 // Make sure the WatcherThread can be started by WatcherThread::start() 4100 // or by dynamic enrollment. 4101 WatcherThread::make_startable(); 4102 // Start up the WatcherThread if there are any periodic tasks 4103 // NOTE: All PeriodicTasks should be registered by now. If they 4104 // aren't, late joiners might appear to start slowly (we might 4105 // take a while to process their first tick). 4106 if (PeriodicTask::num_tasks() > 0) { 4107 WatcherThread::start(); 4108 } 4109 } 4110 4111 create_vm_timer.end(); 4112 #ifdef ASSERT 4113 _vm_complete = true; 4114 #endif 4115 4116 if (DumpSharedSpaces) { 4117 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4118 ShouldNotReachHere(); 4119 } 4120 4121 return JNI_OK; 4122 } 4123 4124 // type for the Agent_OnLoad and JVM_OnLoad entry points 4125 extern "C" { 4126 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4127 } 4128 // Find a command line agent library and return its entry point for 4129 // -agentlib: -agentpath: -Xrun 4130 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4131 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4132 const char *on_load_symbols[], 4133 size_t num_symbol_entries) { 4134 OnLoadEntry_t on_load_entry = NULL; 4135 void *library = NULL; 4136 4137 if (!agent->valid()) { 4138 char buffer[JVM_MAXPATHLEN]; 4139 char ebuf[1024] = ""; 4140 const char *name = agent->name(); 4141 const char *msg = "Could not find agent library "; 4142 4143 // First check to see if agent is statically linked into executable 4144 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4145 library = agent->os_lib(); 4146 } else if (agent->is_absolute_path()) { 4147 library = os::dll_load(name, ebuf, sizeof ebuf); 4148 if (library == NULL) { 4149 const char *sub_msg = " in absolute path, with error: "; 4150 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4151 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4152 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4153 // If we can't find the agent, exit. 4154 vm_exit_during_initialization(buf, NULL); 4155 FREE_C_HEAP_ARRAY(char, buf); 4156 } 4157 } else { 4158 // Try to load the agent from the standard dll directory 4159 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4160 name)) { 4161 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4162 } 4163 if (library == NULL) { // Try the library path directory. 4164 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4165 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4166 } 4167 if (library == NULL) { 4168 const char *sub_msg = " on the library path, with error: "; 4169 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4170 4171 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4172 strlen(ebuf) + strlen(sub_msg2) + 1; 4173 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4174 if (!agent->is_instrument_lib()) { 4175 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4176 } else { 4177 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4178 } 4179 // If we can't find the agent, exit. 4180 vm_exit_during_initialization(buf, NULL); 4181 FREE_C_HEAP_ARRAY(char, buf); 4182 } 4183 } 4184 } 4185 agent->set_os_lib(library); 4186 agent->set_valid(); 4187 } 4188 4189 // Find the OnLoad function. 4190 on_load_entry = 4191 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4192 false, 4193 on_load_symbols, 4194 num_symbol_entries)); 4195 return on_load_entry; 4196 } 4197 4198 // Find the JVM_OnLoad entry point 4199 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4200 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4201 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4202 } 4203 4204 // Find the Agent_OnLoad entry point 4205 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4206 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4207 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4208 } 4209 4210 // For backwards compatibility with -Xrun 4211 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4212 // treated like -agentpath: 4213 // Must be called before agent libraries are created 4214 void Threads::convert_vm_init_libraries_to_agents() { 4215 AgentLibrary* agent; 4216 AgentLibrary* next; 4217 4218 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4219 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4220 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4221 4222 // If there is an JVM_OnLoad function it will get called later, 4223 // otherwise see if there is an Agent_OnLoad 4224 if (on_load_entry == NULL) { 4225 on_load_entry = lookup_agent_on_load(agent); 4226 if (on_load_entry != NULL) { 4227 // switch it to the agent list -- so that Agent_OnLoad will be called, 4228 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4229 Arguments::convert_library_to_agent(agent); 4230 } else { 4231 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4232 } 4233 } 4234 } 4235 } 4236 4237 // Create agents for -agentlib: -agentpath: and converted -Xrun 4238 // Invokes Agent_OnLoad 4239 // Called very early -- before JavaThreads exist 4240 void Threads::create_vm_init_agents() { 4241 extern struct JavaVM_ main_vm; 4242 AgentLibrary* agent; 4243 4244 JvmtiExport::enter_onload_phase(); 4245 4246 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4247 // CDS dumping does not support native JVMTI agent. 4248 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4249 if (Arguments::is_dumping_archive()) { 4250 if(!agent->is_instrument_lib()) { 4251 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4252 } else if (!AllowArchivingWithJavaAgent) { 4253 vm_exit_during_cds_dumping( 4254 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4255 } 4256 } 4257 4258 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4259 4260 if (on_load_entry != NULL) { 4261 // Invoke the Agent_OnLoad function 4262 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4263 if (err != JNI_OK) { 4264 vm_exit_during_initialization("agent library failed to init", agent->name()); 4265 } 4266 } else { 4267 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4268 } 4269 } 4270 4271 JvmtiExport::enter_primordial_phase(); 4272 } 4273 4274 extern "C" { 4275 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4276 } 4277 4278 void Threads::shutdown_vm_agents() { 4279 // Send any Agent_OnUnload notifications 4280 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4281 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4282 extern struct JavaVM_ main_vm; 4283 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4284 4285 // Find the Agent_OnUnload function. 4286 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4287 os::find_agent_function(agent, 4288 false, 4289 on_unload_symbols, 4290 num_symbol_entries)); 4291 4292 // Invoke the Agent_OnUnload function 4293 if (unload_entry != NULL) { 4294 JavaThread* thread = JavaThread::current(); 4295 ThreadToNativeFromVM ttn(thread); 4296 HandleMark hm(thread); 4297 (*unload_entry)(&main_vm); 4298 } 4299 } 4300 } 4301 4302 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4303 // Invokes JVM_OnLoad 4304 void Threads::create_vm_init_libraries() { 4305 extern struct JavaVM_ main_vm; 4306 AgentLibrary* agent; 4307 4308 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4309 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4310 4311 if (on_load_entry != NULL) { 4312 // Invoke the JVM_OnLoad function 4313 JavaThread* thread = JavaThread::current(); 4314 ThreadToNativeFromVM ttn(thread); 4315 HandleMark hm(thread); 4316 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4317 if (err != JNI_OK) { 4318 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4319 } 4320 } else { 4321 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4322 } 4323 } 4324 } 4325 4326 4327 // Last thread running calls java.lang.Shutdown.shutdown() 4328 void JavaThread::invoke_shutdown_hooks() { 4329 HandleMark hm(this); 4330 4331 // We could get here with a pending exception, if so clear it now. 4332 if (this->has_pending_exception()) { 4333 this->clear_pending_exception(); 4334 } 4335 4336 EXCEPTION_MARK; 4337 Klass* shutdown_klass = 4338 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4339 THREAD); 4340 if (shutdown_klass != NULL) { 4341 // SystemDictionary::resolve_or_null will return null if there was 4342 // an exception. If we cannot load the Shutdown class, just don't 4343 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4344 // won't be run. Note that if a shutdown hook was registered, 4345 // the Shutdown class would have already been loaded 4346 // (Runtime.addShutdownHook will load it). 4347 JavaValue result(T_VOID); 4348 JavaCalls::call_static(&result, 4349 shutdown_klass, 4350 vmSymbols::shutdown_name(), 4351 vmSymbols::void_method_signature(), 4352 THREAD); 4353 } 4354 CLEAR_PENDING_EXCEPTION; 4355 } 4356 4357 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4358 // the program falls off the end of main(). Another VM exit path is through 4359 // vm_exit() when the program calls System.exit() to return a value or when 4360 // there is a serious error in VM. The two shutdown paths are not exactly 4361 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4362 // and VM_Exit op at VM level. 4363 // 4364 // Shutdown sequence: 4365 // + Shutdown native memory tracking if it is on 4366 // + Wait until we are the last non-daemon thread to execute 4367 // <-- every thing is still working at this moment --> 4368 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4369 // shutdown hooks 4370 // + Call before_exit(), prepare for VM exit 4371 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4372 // currently the only user of this mechanism is File.deleteOnExit()) 4373 // > stop StatSampler, watcher thread, 4374 // post thread end and vm death events to JVMTI, 4375 // stop signal thread 4376 // + Call JavaThread::exit(), it will: 4377 // > release JNI handle blocks, remove stack guard pages 4378 // > remove this thread from Threads list 4379 // <-- no more Java code from this thread after this point --> 4380 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4381 // the compiler threads at safepoint 4382 // <-- do not use anything that could get blocked by Safepoint --> 4383 // + Disable tracing at JNI/JVM barriers 4384 // + Set _vm_exited flag for threads that are still running native code 4385 // + Call exit_globals() 4386 // > deletes tty 4387 // > deletes PerfMemory resources 4388 // + Delete this thread 4389 // + Return to caller 4390 4391 bool Threads::destroy_vm() { 4392 JavaThread* thread = JavaThread::current(); 4393 4394 #ifdef ASSERT 4395 _vm_complete = false; 4396 #endif 4397 // Wait until we are the last non-daemon thread to execute 4398 { MonitorLocker nu(Threads_lock); 4399 while (Threads::number_of_non_daemon_threads() > 1) 4400 // This wait should make safepoint checks, wait without a timeout, 4401 // and wait as a suspend-equivalent condition. 4402 nu.wait(0, Mutex::_as_suspend_equivalent_flag); 4403 } 4404 4405 EventShutdown e; 4406 if (e.should_commit()) { 4407 e.set_reason("No remaining non-daemon Java threads"); 4408 e.commit(); 4409 } 4410 4411 // Hang forever on exit if we are reporting an error. 4412 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4413 os::infinite_sleep(); 4414 } 4415 os::wait_for_keypress_at_exit(); 4416 4417 // run Java level shutdown hooks 4418 thread->invoke_shutdown_hooks(); 4419 4420 before_exit(thread); 4421 4422 thread->exit(true); 4423 4424 // Stop VM thread. 4425 { 4426 // 4945125 The vm thread comes to a safepoint during exit. 4427 // GC vm_operations can get caught at the safepoint, and the 4428 // heap is unparseable if they are caught. Grab the Heap_lock 4429 // to prevent this. The GC vm_operations will not be able to 4430 // queue until after the vm thread is dead. After this point, 4431 // we'll never emerge out of the safepoint before the VM exits. 4432 4433 MutexLocker ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4434 4435 VMThread::wait_for_vm_thread_exit(); 4436 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4437 VMThread::destroy(); 4438 } 4439 4440 // Now, all Java threads are gone except daemon threads. Daemon threads 4441 // running Java code or in VM are stopped by the Safepoint. However, 4442 // daemon threads executing native code are still running. But they 4443 // will be stopped at native=>Java/VM barriers. Note that we can't 4444 // simply kill or suspend them, as it is inherently deadlock-prone. 4445 4446 VM_Exit::set_vm_exited(); 4447 4448 // Clean up ideal graph printers after the VMThread has started 4449 // the final safepoint which will block all the Compiler threads. 4450 // Note that this Thread has already logically exited so the 4451 // clean_up() function's use of a JavaThreadIteratorWithHandle 4452 // would be a problem except set_vm_exited() has remembered the 4453 // shutdown thread which is granted a policy exception. 4454 #if defined(COMPILER2) && !defined(PRODUCT) 4455 IdealGraphPrinter::clean_up(); 4456 #endif 4457 4458 notify_vm_shutdown(); 4459 4460 // exit_globals() will delete tty 4461 exit_globals(); 4462 4463 // We are after VM_Exit::set_vm_exited() so we can't call 4464 // thread->smr_delete() or we will block on the Threads_lock. 4465 // Deleting the shutdown thread here is safe because another 4466 // JavaThread cannot have an active ThreadsListHandle for 4467 // this JavaThread. 4468 delete thread; 4469 4470 #if INCLUDE_JVMCI 4471 if (JVMCICounterSize > 0) { 4472 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4473 } 4474 #endif 4475 4476 LogConfiguration::finalize(); 4477 4478 return true; 4479 } 4480 4481 4482 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4483 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4484 return is_supported_jni_version(version); 4485 } 4486 4487 4488 jboolean Threads::is_supported_jni_version(jint version) { 4489 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4490 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4491 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4492 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4493 if (version == JNI_VERSION_9) return JNI_TRUE; 4494 if (version == JNI_VERSION_10) return JNI_TRUE; 4495 return JNI_FALSE; 4496 } 4497 4498 4499 void Threads::add(JavaThread* p, bool force_daemon) { 4500 // The threads lock must be owned at this point 4501 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4502 4503 BarrierSet::barrier_set()->on_thread_attach(p); 4504 4505 // Once a JavaThread is added to the Threads list, smr_delete() has 4506 // to be used to delete it. Otherwise we can just delete it directly. 4507 p->set_on_thread_list(); 4508 4509 _number_of_threads++; 4510 oop threadObj = p->threadObj(); 4511 bool daemon = true; 4512 // Bootstrapping problem: threadObj can be null for initial 4513 // JavaThread (or for threads attached via JNI) 4514 if ((!force_daemon) && !is_daemon((threadObj))) { 4515 _number_of_non_daemon_threads++; 4516 daemon = false; 4517 } 4518 4519 ThreadService::add_thread(p, daemon); 4520 4521 // Maintain fast thread list 4522 ThreadsSMRSupport::add_thread(p); 4523 4524 // Possible GC point. 4525 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4526 } 4527 4528 void Threads::remove(JavaThread* p, bool is_daemon) { 4529 4530 // Reclaim the ObjectMonitors from the om_in_use_list and om_free_list of the moribund thread. 4531 ObjectSynchronizer::om_flush(p); 4532 4533 // Extra scope needed for Thread_lock, so we can check 4534 // that we do not remove thread without safepoint code notice 4535 { MonitorLocker ml(Threads_lock); 4536 4537 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4538 4539 // Maintain fast thread list 4540 ThreadsSMRSupport::remove_thread(p); 4541 4542 _number_of_threads--; 4543 if (!is_daemon) { 4544 _number_of_non_daemon_threads--; 4545 4546 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4547 // on destroy_vm will wake up. 4548 if (number_of_non_daemon_threads() == 1) { 4549 ml.notify_all(); 4550 } 4551 } 4552 ThreadService::remove_thread(p, is_daemon); 4553 4554 // Make sure that safepoint code disregard this thread. This is needed since 4555 // the thread might mess around with locks after this point. This can cause it 4556 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4557 // of this thread since it is removed from the queue. 4558 p->set_terminated_value(); 4559 } // unlock Threads_lock 4560 4561 // Since Events::log uses a lock, we grab it outside the Threads_lock 4562 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4563 } 4564 4565 // Operations on the Threads list for GC. These are not explicitly locked, 4566 // but the garbage collector must provide a safe context for them to run. 4567 // In particular, these things should never be called when the Threads_lock 4568 // is held by some other thread. (Note: the Safepoint abstraction also 4569 // uses the Threads_lock to guarantee this property. It also makes sure that 4570 // all threads gets blocked when exiting or starting). 4571 4572 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4573 ALL_JAVA_THREADS(p) { 4574 p->oops_do(f, cf); 4575 } 4576 VMThread::vm_thread()->oops_do(f, cf); 4577 } 4578 4579 void Threads::change_thread_claim_token() { 4580 if (++_thread_claim_token == 0) { 4581 // On overflow of the token counter, there is a risk of future 4582 // collisions between a new global token value and a stale token 4583 // for a thread, because not all iterations visit all threads. 4584 // (Though it's pretty much a theoretical concern for non-trivial 4585 // token counter sizes.) To deal with the possibility, reset all 4586 // the thread tokens to zero on global token overflow. 4587 struct ResetClaims : public ThreadClosure { 4588 virtual void do_thread(Thread* t) { 4589 t->claim_threads_do(false, 0); 4590 } 4591 } reset_claims; 4592 Threads::threads_do(&reset_claims); 4593 // On overflow, update the global token to non-zero, to 4594 // avoid the special "never claimed" initial thread value. 4595 _thread_claim_token = 1; 4596 } 4597 } 4598 4599 #ifdef ASSERT 4600 void assert_thread_claimed(const char* kind, Thread* t, uintx expected) { 4601 const uintx token = t->threads_do_token(); 4602 assert(token == expected, 4603 "%s " PTR_FORMAT " has incorrect value " UINTX_FORMAT " != " 4604 UINTX_FORMAT, kind, p2i(t), token, expected); 4605 } 4606 4607 void Threads::assert_all_threads_claimed() { 4608 ALL_JAVA_THREADS(p) { 4609 assert_thread_claimed("Thread", p, _thread_claim_token); 4610 } 4611 assert_thread_claimed("VMThread", VMThread::vm_thread(), _thread_claim_token); 4612 } 4613 #endif // ASSERT 4614 4615 class ParallelOopsDoThreadClosure : public ThreadClosure { 4616 private: 4617 OopClosure* _f; 4618 CodeBlobClosure* _cf; 4619 public: 4620 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4621 void do_thread(Thread* t) { 4622 t->oops_do(_f, _cf); 4623 } 4624 }; 4625 4626 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4627 ParallelOopsDoThreadClosure tc(f, cf); 4628 possibly_parallel_threads_do(is_par, &tc); 4629 } 4630 4631 void Threads::nmethods_do(CodeBlobClosure* cf) { 4632 ALL_JAVA_THREADS(p) { 4633 // This is used by the code cache sweeper to mark nmethods that are active 4634 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4635 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4636 if(!p->is_Code_cache_sweeper_thread()) { 4637 p->nmethods_do(cf); 4638 } 4639 } 4640 } 4641 4642 void Threads::metadata_do(MetadataClosure* f) { 4643 ALL_JAVA_THREADS(p) { 4644 p->metadata_do(f); 4645 } 4646 } 4647 4648 class ThreadHandlesClosure : public ThreadClosure { 4649 void (*_f)(Metadata*); 4650 public: 4651 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4652 virtual void do_thread(Thread* thread) { 4653 thread->metadata_handles_do(_f); 4654 } 4655 }; 4656 4657 void Threads::metadata_handles_do(void f(Metadata*)) { 4658 // Only walk the Handles in Thread. 4659 ThreadHandlesClosure handles_closure(f); 4660 threads_do(&handles_closure); 4661 } 4662 4663 // Get count Java threads that are waiting to enter the specified monitor. 4664 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4665 int count, 4666 address monitor) { 4667 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4668 4669 int i = 0; 4670 DO_JAVA_THREADS(t_list, p) { 4671 if (!p->can_call_java()) continue; 4672 4673 address pending = (address)p->current_pending_monitor(); 4674 if (pending == monitor) { // found a match 4675 if (i < count) result->append(p); // save the first count matches 4676 i++; 4677 } 4678 } 4679 4680 return result; 4681 } 4682 4683 4684 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4685 address owner) { 4686 // NULL owner means not locked so we can skip the search 4687 if (owner == NULL) return NULL; 4688 4689 DO_JAVA_THREADS(t_list, p) { 4690 // first, see if owner is the address of a Java thread 4691 if (owner == (address)p) return p; 4692 } 4693 4694 // Cannot assert on lack of success here since this function may be 4695 // used by code that is trying to report useful problem information 4696 // like deadlock detection. 4697 if (UseHeavyMonitors) return NULL; 4698 4699 // If we didn't find a matching Java thread and we didn't force use of 4700 // heavyweight monitors, then the owner is the stack address of the 4701 // Lock Word in the owning Java thread's stack. 4702 // 4703 JavaThread* the_owner = NULL; 4704 DO_JAVA_THREADS(t_list, q) { 4705 if (q->is_lock_owned(owner)) { 4706 the_owner = q; 4707 break; 4708 } 4709 } 4710 4711 // cannot assert on lack of success here; see above comment 4712 return the_owner; 4713 } 4714 4715 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4716 void Threads::print_on(outputStream* st, bool print_stacks, 4717 bool internal_format, bool print_concurrent_locks, 4718 bool print_extended_info) { 4719 char buf[32]; 4720 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4721 4722 st->print_cr("Full thread dump %s (%s %s):", 4723 VM_Version::vm_name(), 4724 VM_Version::vm_release(), 4725 VM_Version::vm_info_string()); 4726 st->cr(); 4727 4728 #if INCLUDE_SERVICES 4729 // Dump concurrent locks 4730 ConcurrentLocksDump concurrent_locks; 4731 if (print_concurrent_locks) { 4732 concurrent_locks.dump_at_safepoint(); 4733 } 4734 #endif // INCLUDE_SERVICES 4735 4736 ThreadsSMRSupport::print_info_on(st); 4737 st->cr(); 4738 4739 ALL_JAVA_THREADS(p) { 4740 ResourceMark rm; 4741 p->print_on(st, print_extended_info); 4742 if (print_stacks) { 4743 if (internal_format) { 4744 p->trace_stack(); 4745 } else { 4746 p->print_stack_on(st); 4747 } 4748 } 4749 st->cr(); 4750 #if INCLUDE_SERVICES 4751 if (print_concurrent_locks) { 4752 concurrent_locks.print_locks_on(p, st); 4753 } 4754 #endif // INCLUDE_SERVICES 4755 } 4756 4757 VMThread::vm_thread()->print_on(st); 4758 st->cr(); 4759 Universe::heap()->print_gc_threads_on(st); 4760 WatcherThread* wt = WatcherThread::watcher_thread(); 4761 if (wt != NULL) { 4762 wt->print_on(st); 4763 st->cr(); 4764 } 4765 4766 st->flush(); 4767 } 4768 4769 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4770 int buflen, bool* found_current) { 4771 if (this_thread != NULL) { 4772 bool is_current = (current == this_thread); 4773 *found_current = *found_current || is_current; 4774 st->print("%s", is_current ? "=>" : " "); 4775 4776 st->print(PTR_FORMAT, p2i(this_thread)); 4777 st->print(" "); 4778 this_thread->print_on_error(st, buf, buflen); 4779 st->cr(); 4780 } 4781 } 4782 4783 class PrintOnErrorClosure : public ThreadClosure { 4784 outputStream* _st; 4785 Thread* _current; 4786 char* _buf; 4787 int _buflen; 4788 bool* _found_current; 4789 public: 4790 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4791 int buflen, bool* found_current) : 4792 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4793 4794 virtual void do_thread(Thread* thread) { 4795 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4796 } 4797 }; 4798 4799 // Threads::print_on_error() is called by fatal error handler. It's possible 4800 // that VM is not at safepoint and/or current thread is inside signal handler. 4801 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4802 // memory (even in resource area), it might deadlock the error handler. 4803 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4804 int buflen) { 4805 ThreadsSMRSupport::print_info_on(st); 4806 st->cr(); 4807 4808 bool found_current = false; 4809 st->print_cr("Java Threads: ( => current thread )"); 4810 ALL_JAVA_THREADS(thread) { 4811 print_on_error(thread, st, current, buf, buflen, &found_current); 4812 } 4813 st->cr(); 4814 4815 st->print_cr("Other Threads:"); 4816 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4817 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4818 4819 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4820 Universe::heap()->gc_threads_do(&print_closure); 4821 4822 if (!found_current) { 4823 st->cr(); 4824 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4825 current->print_on_error(st, buf, buflen); 4826 st->cr(); 4827 } 4828 st->cr(); 4829 4830 st->print_cr("Threads with active compile tasks:"); 4831 print_threads_compiling(st, buf, buflen); 4832 } 4833 4834 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4835 ALL_JAVA_THREADS(thread) { 4836 if (thread->is_Compiler_thread()) { 4837 CompilerThread* ct = (CompilerThread*) thread; 4838 4839 // Keep task in local variable for NULL check. 4840 // ct->_task might be set to NULL by concurring compiler thread 4841 // because it completed the compilation. The task is never freed, 4842 // though, just returned to a free list. 4843 CompileTask* task = ct->task(); 4844 if (task != NULL) { 4845 thread->print_name_on_error(st, buf, buflen); 4846 st->print(" "); 4847 task->print(st, NULL, short_form, true); 4848 } 4849 } 4850 } 4851 } 4852 4853 4854 // Internal SpinLock and Mutex 4855 // Based on ParkEvent 4856 4857 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4858 // 4859 // We employ SpinLocks _only for low-contention, fixed-length 4860 // short-duration critical sections where we're concerned 4861 // about native mutex_t or HotSpot Mutex:: latency. 4862 // The mux construct provides a spin-then-block mutual exclusion 4863 // mechanism. 4864 // 4865 // Testing has shown that contention on the ListLock guarding gFreeList 4866 // is common. If we implement ListLock as a simple SpinLock it's common 4867 // for the JVM to devolve to yielding with little progress. This is true 4868 // despite the fact that the critical sections protected by ListLock are 4869 // extremely short. 4870 // 4871 // TODO-FIXME: ListLock should be of type SpinLock. 4872 // We should make this a 1st-class type, integrated into the lock 4873 // hierarchy as leaf-locks. Critically, the SpinLock structure 4874 // should have sufficient padding to avoid false-sharing and excessive 4875 // cache-coherency traffic. 4876 4877 4878 typedef volatile int SpinLockT; 4879 4880 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4881 if (Atomic::cmpxchg(adr, 0, 1) == 0) { 4882 return; // normal fast-path return 4883 } 4884 4885 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4886 int ctr = 0; 4887 int Yields = 0; 4888 for (;;) { 4889 while (*adr != 0) { 4890 ++ctr; 4891 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4892 if (Yields > 5) { 4893 os::naked_short_sleep(1); 4894 } else { 4895 os::naked_yield(); 4896 ++Yields; 4897 } 4898 } else { 4899 SpinPause(); 4900 } 4901 } 4902 if (Atomic::cmpxchg(adr, 0, 1) == 0) return; 4903 } 4904 } 4905 4906 void Thread::SpinRelease(volatile int * adr) { 4907 assert(*adr != 0, "invariant"); 4908 OrderAccess::fence(); // guarantee at least release consistency. 4909 // Roach-motel semantics. 4910 // It's safe if subsequent LDs and STs float "up" into the critical section, 4911 // but prior LDs and STs within the critical section can't be allowed 4912 // to reorder or float past the ST that releases the lock. 4913 // Loads and stores in the critical section - which appear in program 4914 // order before the store that releases the lock - must also appear 4915 // before the store that releases the lock in memory visibility order. 4916 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4917 // the ST of 0 into the lock-word which releases the lock, so fence 4918 // more than covers this on all platforms. 4919 *adr = 0; 4920 } 4921 4922 // muxAcquire and muxRelease: 4923 // 4924 // * muxAcquire and muxRelease support a single-word lock-word construct. 4925 // The LSB of the word is set IFF the lock is held. 4926 // The remainder of the word points to the head of a singly-linked list 4927 // of threads blocked on the lock. 4928 // 4929 // * The current implementation of muxAcquire-muxRelease uses its own 4930 // dedicated Thread._MuxEvent instance. If we're interested in 4931 // minimizing the peak number of extant ParkEvent instances then 4932 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4933 // as certain invariants were satisfied. Specifically, care would need 4934 // to be taken with regards to consuming unpark() "permits". 4935 // A safe rule of thumb is that a thread would never call muxAcquire() 4936 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4937 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4938 // consume an unpark() permit intended for monitorenter, for instance. 4939 // One way around this would be to widen the restricted-range semaphore 4940 // implemented in park(). Another alternative would be to provide 4941 // multiple instances of the PlatformEvent() for each thread. One 4942 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4943 // 4944 // * Usage: 4945 // -- Only as leaf locks 4946 // -- for short-term locking only as muxAcquire does not perform 4947 // thread state transitions. 4948 // 4949 // Alternatives: 4950 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4951 // but with parking or spin-then-park instead of pure spinning. 4952 // * Use Taura-Oyama-Yonenzawa locks. 4953 // * It's possible to construct a 1-0 lock if we encode the lockword as 4954 // (List,LockByte). Acquire will CAS the full lockword while Release 4955 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4956 // acquiring threads use timers (ParkTimed) to detect and recover from 4957 // the stranding window. Thread/Node structures must be aligned on 256-byte 4958 // boundaries by using placement-new. 4959 // * Augment MCS with advisory back-link fields maintained with CAS(). 4960 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4961 // The validity of the backlinks must be ratified before we trust the value. 4962 // If the backlinks are invalid the exiting thread must back-track through the 4963 // the forward links, which are always trustworthy. 4964 // * Add a successor indication. The LockWord is currently encoded as 4965 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4966 // to provide the usual futile-wakeup optimization. 4967 // See RTStt for details. 4968 // 4969 4970 4971 const intptr_t LOCKBIT = 1; 4972 4973 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4974 intptr_t w = Atomic::cmpxchg(Lock, (intptr_t)0, LOCKBIT); 4975 if (w == 0) return; 4976 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4977 return; 4978 } 4979 4980 ParkEvent * const Self = Thread::current()->_MuxEvent; 4981 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4982 for (;;) { 4983 int its = (os::is_MP() ? 100 : 0) + 1; 4984 4985 // Optional spin phase: spin-then-park strategy 4986 while (--its >= 0) { 4987 w = *Lock; 4988 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 4989 return; 4990 } 4991 } 4992 4993 Self->reset(); 4994 Self->OnList = intptr_t(Lock); 4995 // The following fence() isn't _strictly necessary as the subsequent 4996 // CAS() both serializes execution and ratifies the fetched *Lock value. 4997 OrderAccess::fence(); 4998 for (;;) { 4999 w = *Lock; 5000 if ((w & LOCKBIT) == 0) { 5001 if (Atomic::cmpxchg(Lock, w, w|LOCKBIT) == w) { 5002 Self->OnList = 0; // hygiene - allows stronger asserts 5003 return; 5004 } 5005 continue; // Interference -- *Lock changed -- Just retry 5006 } 5007 assert(w & LOCKBIT, "invariant"); 5008 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 5009 if (Atomic::cmpxchg(Lock, w, intptr_t(Self)|LOCKBIT) == w) break; 5010 } 5011 5012 while (Self->OnList != 0) { 5013 Self->park(); 5014 } 5015 } 5016 } 5017 5018 // Release() must extract a successor from the list and then wake that thread. 5019 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 5020 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 5021 // Release() would : 5022 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 5023 // (B) Extract a successor from the private list "in-hand" 5024 // (C) attempt to CAS() the residual back into *Lock over null. 5025 // If there were any newly arrived threads and the CAS() would fail. 5026 // In that case Release() would detach the RATs, re-merge the list in-hand 5027 // with the RATs and repeat as needed. Alternately, Release() might 5028 // detach and extract a successor, but then pass the residual list to the wakee. 5029 // The wakee would be responsible for reattaching and remerging before it 5030 // competed for the lock. 5031 // 5032 // Both "pop" and DMR are immune from ABA corruption -- there can be 5033 // multiple concurrent pushers, but only one popper or detacher. 5034 // This implementation pops from the head of the list. This is unfair, 5035 // but tends to provide excellent throughput as hot threads remain hot. 5036 // (We wake recently run threads first). 5037 // 5038 // All paths through muxRelease() will execute a CAS. 5039 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5040 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5041 // executed within the critical section are complete and globally visible before the 5042 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5043 void Thread::muxRelease(volatile intptr_t * Lock) { 5044 for (;;) { 5045 const intptr_t w = Atomic::cmpxchg(Lock, LOCKBIT, (intptr_t)0); 5046 assert(w & LOCKBIT, "invariant"); 5047 if (w == LOCKBIT) return; 5048 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5049 assert(List != NULL, "invariant"); 5050 assert(List->OnList == intptr_t(Lock), "invariant"); 5051 ParkEvent * const nxt = List->ListNext; 5052 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5053 5054 // The following CAS() releases the lock and pops the head element. 5055 // The CAS() also ratifies the previously fetched lock-word value. 5056 if (Atomic::cmpxchg(Lock, w, intptr_t(nxt)) != w) { 5057 continue; 5058 } 5059 List->OnList = 0; 5060 OrderAccess::fence(); 5061 List->unpark(); 5062 return; 5063 } 5064 } 5065 5066 5067 void Threads::verify() { 5068 ALL_JAVA_THREADS(p) { 5069 p->verify(); 5070 } 5071 VMThread* thread = VMThread::vm_thread(); 5072 if (thread != NULL) thread->verify(); 5073 }