1 /* 2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "jvm.h" 27 #include "classfile/classLoader.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/barrierSet.hpp" 37 #include "gc/shared/gcId.hpp" 38 #include "gc/shared/gcLocker.inline.hpp" 39 #include "gc/shared/workgroup.hpp" 40 #include "interpreter/interpreter.hpp" 41 #include "interpreter/linkResolver.hpp" 42 #include "interpreter/oopMapCache.hpp" 43 #include "jfr/jfrEvents.hpp" 44 #include "jvmtifiles/jvmtiEnv.hpp" 45 #include "logging/log.hpp" 46 #include "logging/logConfiguration.hpp" 47 #include "logging/logStream.hpp" 48 #include "memory/allocation.inline.hpp" 49 #include "memory/metaspaceShared.hpp" 50 #include "memory/oopFactory.hpp" 51 #include "memory/resourceArea.hpp" 52 #include "memory/universe.hpp" 53 #include "oops/access.inline.hpp" 54 #include "oops/instanceKlass.hpp" 55 #include "oops/objArrayOop.hpp" 56 #include "oops/oop.inline.hpp" 57 #include "oops/symbol.hpp" 58 #include "oops/typeArrayOop.inline.hpp" 59 #include "oops/verifyOopClosure.hpp" 60 #include "prims/jvm_misc.hpp" 61 #include "prims/jvmtiExport.hpp" 62 #include "prims/jvmtiThreadState.hpp" 63 #include "runtime/arguments.hpp" 64 #include "runtime/atomic.hpp" 65 #include "runtime/biasedLocking.hpp" 66 #include "runtime/fieldDescriptor.inline.hpp" 67 #include "runtime/flags/jvmFlagConstraintList.hpp" 68 #include "runtime/flags/jvmFlagRangeList.hpp" 69 #include "runtime/flags/jvmFlagWriteableList.hpp" 70 #include "runtime/deoptimization.hpp" 71 #include "runtime/frame.inline.hpp" 72 #include "runtime/handles.inline.hpp" 73 #include "runtime/handshake.hpp" 74 #include "runtime/init.hpp" 75 #include "runtime/interfaceSupport.inline.hpp" 76 #include "runtime/java.hpp" 77 #include "runtime/javaCalls.hpp" 78 #include "runtime/jniHandles.inline.hpp" 79 #include "runtime/jniPeriodicChecker.hpp" 80 #include "runtime/memprofiler.hpp" 81 #include "runtime/mutexLocker.hpp" 82 #include "runtime/objectMonitor.hpp" 83 #include "runtime/orderAccess.hpp" 84 #include "runtime/osThread.hpp" 85 #include "runtime/prefetch.inline.hpp" 86 #include "runtime/safepoint.hpp" 87 #include "runtime/safepointMechanism.inline.hpp" 88 #include "runtime/safepointVerifiers.hpp" 89 #include "runtime/sharedRuntime.hpp" 90 #include "runtime/statSampler.hpp" 91 #include "runtime/stubRoutines.hpp" 92 #include "runtime/sweeper.hpp" 93 #include "runtime/task.hpp" 94 #include "runtime/thread.inline.hpp" 95 #include "runtime/threadCritical.hpp" 96 #include "runtime/threadSMR.inline.hpp" 97 #include "runtime/threadStatisticalInfo.hpp" 98 #include "runtime/timer.hpp" 99 #include "runtime/timerTrace.hpp" 100 #include "runtime/vframe.inline.hpp" 101 #include "runtime/vframeArray.hpp" 102 #include "runtime/vframe_hp.hpp" 103 #include "runtime/vmThread.hpp" 104 #include "runtime/vmOperations.hpp" 105 #include "runtime/vm_version.hpp" 106 #include "services/attachListener.hpp" 107 #include "services/management.hpp" 108 #include "services/memTracker.hpp" 109 #include "services/threadService.hpp" 110 #include "utilities/align.hpp" 111 #include "utilities/copy.hpp" 112 #include "utilities/defaultStream.hpp" 113 #include "utilities/dtrace.hpp" 114 #include "utilities/events.hpp" 115 #include "utilities/macros.hpp" 116 #include "utilities/preserveException.hpp" 117 #include "utilities/singleWriterSynchronizer.hpp" 118 #include "utilities/vmError.hpp" 119 #if INCLUDE_JVMCI 120 #include "jvmci/jvmciCompiler.hpp" 121 #include "jvmci/jvmciRuntime.hpp" 122 #include "logging/logHandle.hpp" 123 #endif 124 #ifdef COMPILER1 125 #include "c1/c1_Compiler.hpp" 126 #endif 127 #ifdef COMPILER2 128 #include "opto/c2compiler.hpp" 129 #include "opto/idealGraphPrinter.hpp" 130 #endif 131 #if INCLUDE_RTM_OPT 132 #include "runtime/rtmLocking.hpp" 133 #endif 134 #if INCLUDE_JFR 135 #include "jfr/jfr.hpp" 136 #endif 137 138 // Initialization after module runtime initialization 139 void universe_post_module_init(); // must happen after call_initPhase2 140 141 #ifdef DTRACE_ENABLED 142 143 // Only bother with this argument setup if dtrace is available 144 145 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 146 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) \ 149 { \ 150 ResourceMark rm(this); \ 151 int len = 0; \ 152 const char* name = (javathread)->get_thread_name(); \ 153 len = strlen(name); \ 154 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 155 (char *) name, len, \ 156 java_lang_Thread::thread_id((javathread)->threadObj()), \ 157 (uintptr_t) (javathread)->osthread()->thread_id(), \ 158 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 159 } 160 161 #else // ndef DTRACE_ENABLED 162 163 #define DTRACE_THREAD_PROBE(probe, javathread) 164 165 #endif // ndef DTRACE_ENABLED 166 167 #ifndef USE_LIBRARY_BASED_TLS_ONLY 168 // Current thread is maintained as a thread-local variable 169 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 170 #endif 171 172 // ======= Thread ======== 173 // Support for forcing alignment of thread objects for biased locking 174 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 175 if (UseBiasedLocking) { 176 const int alignment = markOopDesc::biased_lock_alignment; 177 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 178 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 179 : AllocateHeap(aligned_size, flags, CURRENT_PC, 180 AllocFailStrategy::RETURN_NULL); 181 void* aligned_addr = align_up(real_malloc_addr, alignment); 182 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 183 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 184 "JavaThread alignment code overflowed allocated storage"); 185 if (aligned_addr != real_malloc_addr) { 186 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 187 p2i(real_malloc_addr), 188 p2i(aligned_addr)); 189 } 190 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 191 return aligned_addr; 192 } else { 193 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 194 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 195 } 196 } 197 198 void Thread::operator delete(void* p) { 199 if (UseBiasedLocking) { 200 FreeHeap(((Thread*) p)->_real_malloc_address); 201 } else { 202 FreeHeap(p); 203 } 204 } 205 206 void JavaThread::smr_delete() { 207 if (_on_thread_list) { 208 ThreadsSMRSupport::smr_delete(this); 209 } else { 210 delete this; 211 } 212 } 213 214 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 215 // JavaThread 216 217 DEBUG_ONLY(Thread* Thread::_starting_thread = NULL;) 218 219 Thread::Thread() { 220 221 DEBUG_ONLY(_run_state = PRE_CALL_RUN;) 222 223 // stack and get_thread 224 set_stack_base(NULL); 225 set_stack_size(0); 226 set_self_raw_id(0); 227 set_lgrp_id(-1); 228 DEBUG_ONLY(clear_suspendible_thread();) 229 230 // allocated data structures 231 set_osthread(NULL); 232 set_resource_area(new (mtThread)ResourceArea()); 233 DEBUG_ONLY(_current_resource_mark = NULL;) 234 set_handle_area(new (mtThread) HandleArea(NULL)); 235 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 236 set_active_handles(NULL); 237 set_free_handle_block(NULL); 238 set_last_handle_mark(NULL); 239 DEBUG_ONLY(_missed_ic_stub_refill_verifier = NULL); 240 241 // This initial value ==> never claimed. 242 _oops_do_parity = 0; 243 _threads_hazard_ptr = NULL; 244 _threads_list_ptr = NULL; 245 _nested_threads_hazard_ptr_cnt = 0; 246 _rcu_counter = 0; 247 248 // the handle mark links itself to last_handle_mark 249 new HandleMark(this); 250 251 // plain initialization 252 debug_only(_owned_locks = NULL;) 253 debug_only(_allow_allocation_count = 0;) 254 NOT_PRODUCT(_allow_safepoint_count = 0;) 255 NOT_PRODUCT(_skip_gcalot = false;) 256 _jvmti_env_iteration_count = 0; 257 set_allocated_bytes(0); 258 _vm_operation_started_count = 0; 259 _vm_operation_completed_count = 0; 260 _current_pending_monitor = NULL; 261 _current_pending_monitor_is_from_java = true; 262 _current_waiting_monitor = NULL; 263 _num_nested_signal = 0; 264 omFreeList = NULL; 265 omFreeCount = 0; 266 omFreeProvision = 32; 267 omInUseList = NULL; 268 omInUseCount = 0; 269 270 #ifdef ASSERT 271 _visited_for_critical_count = false; 272 #endif 273 274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 275 Monitor::_safepoint_check_sometimes); 276 _suspend_flags = 0; 277 278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 279 _hashStateX = os::random(); 280 _hashStateY = 842502087; 281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 282 _hashStateW = 273326509; 283 284 _OnTrap = 0; 285 _Stalled = 0; 286 _TypeTag = 0x2BAD; 287 288 // Many of the following fields are effectively final - immutable 289 // Note that nascent threads can't use the Native Monitor-Mutex 290 // construct until the _MutexEvent is initialized ... 291 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 292 // we might instead use a stack of ParkEvents that we could provision on-demand. 293 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 294 // and ::Release() 295 _ParkEvent = ParkEvent::Allocate(this); 296 _SleepEvent = ParkEvent::Allocate(this); 297 _MuxEvent = ParkEvent::Allocate(this); 298 299 #ifdef CHECK_UNHANDLED_OOPS 300 if (CheckUnhandledOops) { 301 _unhandled_oops = new UnhandledOops(this); 302 } 303 #endif // CHECK_UNHANDLED_OOPS 304 #ifdef ASSERT 305 if (UseBiasedLocking) { 306 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 307 assert(this == _real_malloc_address || 308 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 309 "bug in forced alignment of thread objects"); 310 } 311 #endif // ASSERT 312 313 // Notify the barrier set that a thread is being created. The initial 314 // thread is created before the barrier set is available. The call to 315 // BarrierSet::on_thread_create() for this thread is therefore deferred 316 // to BarrierSet::set_barrier_set(). 317 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 318 if (barrier_set != NULL) { 319 barrier_set->on_thread_create(this); 320 } else { 321 // Only the main thread should be created before the barrier set 322 // and that happens just before Thread::current is set. No other thread 323 // can attach as the VM is not created yet, so they can't execute this code. 324 // If the main thread creates other threads before the barrier set that is an error. 325 assert(Thread::current_or_null() == NULL, "creating thread before barrier set"); 326 } 327 } 328 329 void Thread::initialize_thread_current() { 330 #ifndef USE_LIBRARY_BASED_TLS_ONLY 331 assert(_thr_current == NULL, "Thread::current already initialized"); 332 _thr_current = this; 333 #endif 334 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 335 ThreadLocalStorage::set_thread(this); 336 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 337 } 338 339 void Thread::clear_thread_current() { 340 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 341 #ifndef USE_LIBRARY_BASED_TLS_ONLY 342 _thr_current = NULL; 343 #endif 344 ThreadLocalStorage::set_thread(NULL); 345 } 346 347 void Thread::record_stack_base_and_size() { 348 // Note: at this point, Thread object is not yet initialized. Do not rely on 349 // any members being initialized. Do not rely on Thread::current() being set. 350 // If possible, refrain from doing anything which may crash or assert since 351 // quite probably those crash dumps will be useless. 352 set_stack_base(os::current_stack_base()); 353 set_stack_size(os::current_stack_size()); 354 355 #ifdef SOLARIS 356 if (os::is_primordial_thread()) { 357 os::Solaris::correct_stack_boundaries_for_primordial_thread(this); 358 } 359 #endif 360 361 // Set stack limits after thread is initialized. 362 if (is_Java_thread()) { 363 ((JavaThread*) this)->set_stack_overflow_limit(); 364 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 365 } 366 } 367 368 #if INCLUDE_NMT 369 void Thread::register_thread_stack_with_NMT() { 370 MemTracker::record_thread_stack(stack_end(), stack_size()); 371 } 372 #endif // INCLUDE_NMT 373 374 void Thread::call_run() { 375 DEBUG_ONLY(_run_state = CALL_RUN;) 376 377 // At this point, Thread object should be fully initialized and 378 // Thread::current() should be set. 379 380 assert(Thread::current_or_null() != NULL, "current thread is unset"); 381 assert(Thread::current_or_null() == this, "current thread is wrong"); 382 383 // Perform common initialization actions 384 385 register_thread_stack_with_NMT(); 386 387 JFR_ONLY(Jfr::on_thread_start(this);) 388 389 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 390 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 391 os::current_thread_id(), p2i(stack_base() - stack_size()), 392 p2i(stack_base()), stack_size()/1024); 393 394 // Perform <ChildClass> initialization actions 395 DEBUG_ONLY(_run_state = PRE_RUN;) 396 this->pre_run(); 397 398 // Invoke <ChildClass>::run() 399 DEBUG_ONLY(_run_state = RUN;) 400 this->run(); 401 // Returned from <ChildClass>::run(). Thread finished. 402 403 // Perform common tear-down actions 404 405 assert(Thread::current_or_null() != NULL, "current thread is unset"); 406 assert(Thread::current_or_null() == this, "current thread is wrong"); 407 408 // Perform <ChildClass> tear-down actions 409 DEBUG_ONLY(_run_state = POST_RUN;) 410 this->post_run(); 411 412 // Note: at this point the thread object may already have deleted itself, 413 // so from here on do not dereference *this*. Not all thread types currently 414 // delete themselves when they terminate. But no thread should ever be deleted 415 // asynchronously with respect to its termination - that is what _run_state can 416 // be used to check. 417 418 assert(Thread::current_or_null() == NULL, "current thread still present"); 419 } 420 421 Thread::~Thread() { 422 423 // Attached threads will remain in PRE_CALL_RUN, as will threads that don't actually 424 // get started due to errors etc. Any active thread should at least reach post_run 425 // before it is deleted (usually in post_run()). 426 assert(_run_state == PRE_CALL_RUN || 427 _run_state == POST_RUN, "Active Thread deleted before post_run(): " 428 "_run_state=%d", (int)_run_state); 429 430 // Notify the barrier set that a thread is being destroyed. Note that a barrier 431 // set might not be available if we encountered errors during bootstrapping. 432 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 433 if (barrier_set != NULL) { 434 barrier_set->on_thread_destroy(this); 435 } 436 437 // stack_base can be NULL if the thread is never started or exited before 438 // record_stack_base_and_size called. Although, we would like to ensure 439 // that all started threads do call record_stack_base_and_size(), there is 440 // not proper way to enforce that. 441 #if INCLUDE_NMT 442 if (_stack_base != NULL) { 443 MemTracker::release_thread_stack(stack_end(), stack_size()); 444 #ifdef ASSERT 445 set_stack_base(NULL); 446 #endif 447 } 448 #endif // INCLUDE_NMT 449 450 // deallocate data structures 451 delete resource_area(); 452 // since the handle marks are using the handle area, we have to deallocated the root 453 // handle mark before deallocating the thread's handle area, 454 assert(last_handle_mark() != NULL, "check we have an element"); 455 delete last_handle_mark(); 456 assert(last_handle_mark() == NULL, "check we have reached the end"); 457 458 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 459 // We NULL out the fields for good hygiene. 460 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 461 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 462 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 463 464 delete handle_area(); 465 delete metadata_handles(); 466 467 // SR_handler uses this as a termination indicator - 468 // needs to happen before os::free_thread() 469 delete _SR_lock; 470 _SR_lock = NULL; 471 472 // osthread() can be NULL, if creation of thread failed. 473 if (osthread() != NULL) os::free_thread(osthread()); 474 475 // Clear Thread::current if thread is deleting itself and it has not 476 // already been done. This must be done before the memory is deallocated. 477 // Needed to ensure JNI correctly detects non-attached threads. 478 if (this == Thread::current_or_null()) { 479 Thread::clear_thread_current(); 480 } 481 482 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 483 } 484 485 #ifdef ASSERT 486 // A JavaThread is considered "dangling" if it is not the current 487 // thread, has been added the Threads list, the system is not at a 488 // safepoint and the Thread is not "protected". 489 // 490 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 491 assert(!thread->is_Java_thread() || Thread::current() == thread || 492 !((JavaThread *) thread)->on_thread_list() || 493 SafepointSynchronize::is_at_safepoint() || 494 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 495 "possibility of dangling Thread pointer"); 496 } 497 #endif 498 499 ThreadPriority Thread::get_priority(const Thread* const thread) { 500 ThreadPriority priority; 501 // Can return an error! 502 (void)os::get_priority(thread, priority); 503 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 504 return priority; 505 } 506 507 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 508 debug_only(check_for_dangling_thread_pointer(thread);) 509 // Can return an error! 510 (void)os::set_priority(thread, priority); 511 } 512 513 514 void Thread::start(Thread* thread) { 515 // Start is different from resume in that its safety is guaranteed by context or 516 // being called from a Java method synchronized on the Thread object. 517 if (!DisableStartThread) { 518 if (thread->is_Java_thread()) { 519 // Initialize the thread state to RUNNABLE before starting this thread. 520 // Can not set it after the thread started because we do not know the 521 // exact thread state at that time. It could be in MONITOR_WAIT or 522 // in SLEEPING or some other state. 523 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 524 java_lang_Thread::RUNNABLE); 525 } 526 os::start_thread(thread); 527 } 528 } 529 530 // Enqueue a VM_Operation to do the job for us - sometime later 531 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 532 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 533 VMThread::execute(vm_stop); 534 } 535 536 537 // Check if an external suspend request has completed (or has been 538 // cancelled). Returns true if the thread is externally suspended and 539 // false otherwise. 540 // 541 // The bits parameter returns information about the code path through 542 // the routine. Useful for debugging: 543 // 544 // set in is_ext_suspend_completed(): 545 // 0x00000001 - routine was entered 546 // 0x00000010 - routine return false at end 547 // 0x00000100 - thread exited (return false) 548 // 0x00000200 - suspend request cancelled (return false) 549 // 0x00000400 - thread suspended (return true) 550 // 0x00001000 - thread is in a suspend equivalent state (return true) 551 // 0x00002000 - thread is native and walkable (return true) 552 // 0x00004000 - thread is native_trans and walkable (needed retry) 553 // 554 // set in wait_for_ext_suspend_completion(): 555 // 0x00010000 - routine was entered 556 // 0x00020000 - suspend request cancelled before loop (return false) 557 // 0x00040000 - thread suspended before loop (return true) 558 // 0x00080000 - suspend request cancelled in loop (return false) 559 // 0x00100000 - thread suspended in loop (return true) 560 // 0x00200000 - suspend not completed during retry loop (return false) 561 562 // Helper class for tracing suspend wait debug bits. 563 // 564 // 0x00000100 indicates that the target thread exited before it could 565 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 566 // 0x00080000 each indicate a cancelled suspend request so they don't 567 // count as wait failures either. 568 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 569 570 class TraceSuspendDebugBits : public StackObj { 571 private: 572 JavaThread * jt; 573 bool is_wait; 574 bool called_by_wait; // meaningful when !is_wait 575 uint32_t * bits; 576 577 public: 578 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 579 uint32_t *_bits) { 580 jt = _jt; 581 is_wait = _is_wait; 582 called_by_wait = _called_by_wait; 583 bits = _bits; 584 } 585 586 ~TraceSuspendDebugBits() { 587 if (!is_wait) { 588 #if 1 589 // By default, don't trace bits for is_ext_suspend_completed() calls. 590 // That trace is very chatty. 591 return; 592 #else 593 if (!called_by_wait) { 594 // If tracing for is_ext_suspend_completed() is enabled, then only 595 // trace calls to it from wait_for_ext_suspend_completion() 596 return; 597 } 598 #endif 599 } 600 601 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 602 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 603 MutexLocker ml(Threads_lock); // needed for get_thread_name() 604 ResourceMark rm; 605 606 tty->print_cr( 607 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 608 jt->get_thread_name(), *bits); 609 610 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 611 } 612 } 613 } 614 }; 615 #undef DEBUG_FALSE_BITS 616 617 618 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 619 uint32_t *bits) { 620 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 621 622 bool did_trans_retry = false; // only do thread_in_native_trans retry once 623 bool do_trans_retry; // flag to force the retry 624 625 *bits |= 0x00000001; 626 627 do { 628 do_trans_retry = false; 629 630 if (is_exiting()) { 631 // Thread is in the process of exiting. This is always checked 632 // first to reduce the risk of dereferencing a freed JavaThread. 633 *bits |= 0x00000100; 634 return false; 635 } 636 637 if (!is_external_suspend()) { 638 // Suspend request is cancelled. This is always checked before 639 // is_ext_suspended() to reduce the risk of a rogue resume 640 // confusing the thread that made the suspend request. 641 *bits |= 0x00000200; 642 return false; 643 } 644 645 if (is_ext_suspended()) { 646 // thread is suspended 647 *bits |= 0x00000400; 648 return true; 649 } 650 651 // Now that we no longer do hard suspends of threads running 652 // native code, the target thread can be changing thread state 653 // while we are in this routine: 654 // 655 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 656 // 657 // We save a copy of the thread state as observed at this moment 658 // and make our decision about suspend completeness based on the 659 // copy. This closes the race where the thread state is seen as 660 // _thread_in_native_trans in the if-thread_blocked check, but is 661 // seen as _thread_blocked in if-thread_in_native_trans check. 662 JavaThreadState save_state = thread_state(); 663 664 if (save_state == _thread_blocked && is_suspend_equivalent()) { 665 // If the thread's state is _thread_blocked and this blocking 666 // condition is known to be equivalent to a suspend, then we can 667 // consider the thread to be externally suspended. This means that 668 // the code that sets _thread_blocked has been modified to do 669 // self-suspension if the blocking condition releases. We also 670 // used to check for CONDVAR_WAIT here, but that is now covered by 671 // the _thread_blocked with self-suspension check. 672 // 673 // Return true since we wouldn't be here unless there was still an 674 // external suspend request. 675 *bits |= 0x00001000; 676 return true; 677 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 678 // Threads running native code will self-suspend on native==>VM/Java 679 // transitions. If its stack is walkable (should always be the case 680 // unless this function is called before the actual java_suspend() 681 // call), then the wait is done. 682 *bits |= 0x00002000; 683 return true; 684 } else if (!called_by_wait && !did_trans_retry && 685 save_state == _thread_in_native_trans && 686 frame_anchor()->walkable()) { 687 // The thread is transitioning from thread_in_native to another 688 // thread state. check_safepoint_and_suspend_for_native_trans() 689 // will force the thread to self-suspend. If it hasn't gotten 690 // there yet we may have caught the thread in-between the native 691 // code check above and the self-suspend. Lucky us. If we were 692 // called by wait_for_ext_suspend_completion(), then it 693 // will be doing the retries so we don't have to. 694 // 695 // Since we use the saved thread state in the if-statement above, 696 // there is a chance that the thread has already transitioned to 697 // _thread_blocked by the time we get here. In that case, we will 698 // make a single unnecessary pass through the logic below. This 699 // doesn't hurt anything since we still do the trans retry. 700 701 *bits |= 0x00004000; 702 703 // Once the thread leaves thread_in_native_trans for another 704 // thread state, we break out of this retry loop. We shouldn't 705 // need this flag to prevent us from getting back here, but 706 // sometimes paranoia is good. 707 did_trans_retry = true; 708 709 // We wait for the thread to transition to a more usable state. 710 for (int i = 1; i <= SuspendRetryCount; i++) { 711 // We used to do an "os::yield_all(i)" call here with the intention 712 // that yielding would increase on each retry. However, the parameter 713 // is ignored on Linux which means the yield didn't scale up. Waiting 714 // on the SR_lock below provides a much more predictable scale up for 715 // the delay. It also provides a simple/direct point to check for any 716 // safepoint requests from the VMThread 717 718 // temporarily drops SR_lock while doing wait with safepoint check 719 // (if we're a JavaThread - the WatcherThread can also call this) 720 // and increase delay with each retry 721 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 722 723 // check the actual thread state instead of what we saved above 724 if (thread_state() != _thread_in_native_trans) { 725 // the thread has transitioned to another thread state so 726 // try all the checks (except this one) one more time. 727 do_trans_retry = true; 728 break; 729 } 730 } // end retry loop 731 732 733 } 734 } while (do_trans_retry); 735 736 *bits |= 0x00000010; 737 return false; 738 } 739 740 // Wait for an external suspend request to complete (or be cancelled). 741 // Returns true if the thread is externally suspended and false otherwise. 742 // 743 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 744 uint32_t *bits) { 745 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 746 false /* !called_by_wait */, bits); 747 748 // local flag copies to minimize SR_lock hold time 749 bool is_suspended; 750 bool pending; 751 uint32_t reset_bits; 752 753 // set a marker so is_ext_suspend_completed() knows we are the caller 754 *bits |= 0x00010000; 755 756 // We use reset_bits to reinitialize the bits value at the top of 757 // each retry loop. This allows the caller to make use of any 758 // unused bits for their own marking purposes. 759 reset_bits = *bits; 760 761 { 762 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 763 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 764 delay, bits); 765 pending = is_external_suspend(); 766 } 767 // must release SR_lock to allow suspension to complete 768 769 if (!pending) { 770 // A cancelled suspend request is the only false return from 771 // is_ext_suspend_completed() that keeps us from entering the 772 // retry loop. 773 *bits |= 0x00020000; 774 return false; 775 } 776 777 if (is_suspended) { 778 *bits |= 0x00040000; 779 return true; 780 } 781 782 for (int i = 1; i <= retries; i++) { 783 *bits = reset_bits; // reinit to only track last retry 784 785 // We used to do an "os::yield_all(i)" call here with the intention 786 // that yielding would increase on each retry. However, the parameter 787 // is ignored on Linux which means the yield didn't scale up. Waiting 788 // on the SR_lock below provides a much more predictable scale up for 789 // the delay. It also provides a simple/direct point to check for any 790 // safepoint requests from the VMThread 791 792 { 793 MutexLocker ml(SR_lock()); 794 // wait with safepoint check (if we're a JavaThread - the WatcherThread 795 // can also call this) and increase delay with each retry 796 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 797 798 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 799 delay, bits); 800 801 // It is possible for the external suspend request to be cancelled 802 // (by a resume) before the actual suspend operation is completed. 803 // Refresh our local copy to see if we still need to wait. 804 pending = is_external_suspend(); 805 } 806 807 if (!pending) { 808 // A cancelled suspend request is the only false return from 809 // is_ext_suspend_completed() that keeps us from staying in the 810 // retry loop. 811 *bits |= 0x00080000; 812 return false; 813 } 814 815 if (is_suspended) { 816 *bits |= 0x00100000; 817 return true; 818 } 819 } // end retry loop 820 821 // thread did not suspend after all our retries 822 *bits |= 0x00200000; 823 return false; 824 } 825 826 // Called from API entry points which perform stack walking. If the 827 // associated JavaThread is the current thread, then wait_for_suspend 828 // is not used. Otherwise, it determines if we should wait for the 829 // "other" thread to complete external suspension. (NOTE: in future 830 // releases the suspension mechanism should be reimplemented so this 831 // is not necessary.) 832 // 833 bool 834 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 835 if (this != JavaThread::current()) { 836 // "other" threads require special handling. 837 if (wait_for_suspend) { 838 // We are allowed to wait for the external suspend to complete 839 // so give the other thread a chance to get suspended. 840 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 841 SuspendRetryDelay, bits)) { 842 // Didn't make it so let the caller know. 843 return false; 844 } 845 } 846 // We aren't allowed to wait for the external suspend to complete 847 // so if the other thread isn't externally suspended we need to 848 // let the caller know. 849 else if (!is_ext_suspend_completed_with_lock(bits)) { 850 return false; 851 } 852 } 853 854 return true; 855 } 856 857 #ifndef PRODUCT 858 void JavaThread::record_jump(address target, address instr, const char* file, 859 int line) { 860 861 // This should not need to be atomic as the only way for simultaneous 862 // updates is via interrupts. Even then this should be rare or non-existent 863 // and we don't care that much anyway. 864 865 int index = _jmp_ring_index; 866 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 867 _jmp_ring[index]._target = (intptr_t) target; 868 _jmp_ring[index]._instruction = (intptr_t) instr; 869 _jmp_ring[index]._file = file; 870 _jmp_ring[index]._line = line; 871 } 872 #endif // PRODUCT 873 874 void Thread::interrupt(Thread* thread) { 875 debug_only(check_for_dangling_thread_pointer(thread);) 876 os::interrupt(thread); 877 } 878 879 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 880 debug_only(check_for_dangling_thread_pointer(thread);) 881 // Note: If clear_interrupted==false, this simply fetches and 882 // returns the value of the field osthread()->interrupted(). 883 return os::is_interrupted(thread, clear_interrupted); 884 } 885 886 887 // GC Support 888 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 889 int thread_parity = _oops_do_parity; 890 if (thread_parity != strong_roots_parity) { 891 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 892 if (res == thread_parity) { 893 return true; 894 } else { 895 guarantee(res == strong_roots_parity, "Or else what?"); 896 return false; 897 } 898 } 899 return false; 900 } 901 902 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 903 active_handles()->oops_do(f); 904 // Do oop for ThreadShadow 905 f->do_oop((oop*)&_pending_exception); 906 handle_area()->oops_do(f); 907 908 // We scan thread local monitor lists here, and the remaining global 909 // monitors in ObjectSynchronizer::oops_do(). 910 ObjectSynchronizer::thread_local_used_oops_do(this, f); 911 } 912 913 void Thread::metadata_handles_do(void f(Metadata*)) { 914 // Only walk the Handles in Thread. 915 if (metadata_handles() != NULL) { 916 for (int i = 0; i< metadata_handles()->length(); i++) { 917 f(metadata_handles()->at(i)); 918 } 919 } 920 } 921 922 void Thread::print_on(outputStream* st, bool print_extended_info) const { 923 // get_priority assumes osthread initialized 924 if (osthread() != NULL) { 925 int os_prio; 926 if (os::get_native_priority(this, &os_prio) == OS_OK) { 927 st->print("os_prio=%d ", os_prio); 928 } 929 930 st->print("cpu=%.2fms ", 931 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 932 ); 933 st->print("elapsed=%.2fs ", 934 _statistical_info.getElapsedTime() / 1000.0 935 ); 936 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 937 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 938 st->print("allocated=" SIZE_FORMAT "%s ", 939 byte_size_in_proper_unit(allocated_bytes), 940 proper_unit_for_byte_size(allocated_bytes) 941 ); 942 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 943 } 944 945 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 946 osthread()->print_on(st); 947 } 948 ThreadsSMRSupport::print_info_on(this, st); 949 st->print(" "); 950 debug_only(if (WizardMode) print_owned_locks_on(st);) 951 } 952 953 // Thread::print_on_error() is called by fatal error handler. Don't use 954 // any lock or allocate memory. 955 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 956 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 957 958 if (is_VM_thread()) { st->print("VMThread"); } 959 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 960 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 961 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 962 else { st->print("Thread"); } 963 964 if (is_Named_thread()) { 965 st->print(" \"%s\"", name()); 966 } 967 968 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 969 p2i(stack_end()), p2i(stack_base())); 970 971 if (osthread()) { 972 st->print(" [id=%d]", osthread()->thread_id()); 973 } 974 975 ThreadsSMRSupport::print_info_on(this, st); 976 } 977 978 void Thread::print_value_on(outputStream* st) const { 979 if (is_Named_thread()) { 980 st->print(" \"%s\" ", name()); 981 } 982 st->print(INTPTR_FORMAT, p2i(this)); // print address 983 } 984 985 #ifdef ASSERT 986 void Thread::print_owned_locks_on(outputStream* st) const { 987 Monitor *cur = _owned_locks; 988 if (cur == NULL) { 989 st->print(" (no locks) "); 990 } else { 991 st->print_cr(" Locks owned:"); 992 while (cur) { 993 cur->print_on(st); 994 cur = cur->next(); 995 } 996 } 997 } 998 999 static int ref_use_count = 0; 1000 1001 bool Thread::owns_locks_but_compiled_lock() const { 1002 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1003 if (cur != Compile_lock) return true; 1004 } 1005 return false; 1006 } 1007 1008 1009 #endif 1010 1011 #ifndef PRODUCT 1012 1013 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 1014 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 1015 // no locks which allow_vm_block's are held 1016 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 1017 // Check if current thread is allowed to block at a safepoint 1018 if (!(_allow_safepoint_count == 0)) { 1019 fatal("Possible safepoint reached by thread that does not allow it"); 1020 } 1021 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 1022 fatal("LEAF method calling lock?"); 1023 } 1024 1025 #ifdef ASSERT 1026 if (potential_vm_operation && is_Java_thread() 1027 && !Universe::is_bootstrapping()) { 1028 // Make sure we do not hold any locks that the VM thread also uses. 1029 // This could potentially lead to deadlocks 1030 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1031 // Threads_lock is special, since the safepoint synchronization will not start before this is 1032 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1033 // since it is used to transfer control between JavaThreads and the VMThread 1034 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1035 if ((cur->allow_vm_block() && 1036 cur != Threads_lock && 1037 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1038 cur != VMOperationRequest_lock && 1039 cur != VMOperationQueue_lock) || 1040 cur->rank() == Mutex::special) { 1041 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1042 } 1043 } 1044 } 1045 1046 if (GCALotAtAllSafepoints) { 1047 // We could enter a safepoint here and thus have a gc 1048 InterfaceSupport::check_gc_alot(); 1049 } 1050 #endif 1051 } 1052 #endif 1053 1054 bool Thread::is_in_stack(address adr) const { 1055 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1056 address end = os::current_stack_pointer(); 1057 // Allow non Java threads to call this without stack_base 1058 if (_stack_base == NULL) return true; 1059 if (stack_base() >= adr && adr >= end) return true; 1060 1061 return false; 1062 } 1063 1064 bool Thread::is_in_usable_stack(address adr) const { 1065 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1066 size_t usable_stack_size = _stack_size - stack_guard_size; 1067 1068 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1069 } 1070 1071 1072 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1073 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1074 // used for compilation in the future. If that change is made, the need for these methods 1075 // should be revisited, and they should be removed if possible. 1076 1077 bool Thread::is_lock_owned(address adr) const { 1078 return on_local_stack(adr); 1079 } 1080 1081 bool Thread::set_as_starting_thread() { 1082 assert(_starting_thread == NULL, "already initialized: " 1083 "_starting_thread=" INTPTR_FORMAT, p2i(_starting_thread)); 1084 // NOTE: this must be called inside the main thread. 1085 DEBUG_ONLY(_starting_thread = this;) 1086 return os::create_main_thread((JavaThread*)this); 1087 } 1088 1089 static void initialize_class(Symbol* class_name, TRAPS) { 1090 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1091 InstanceKlass::cast(klass)->initialize(CHECK); 1092 } 1093 1094 1095 // Creates the initial ThreadGroup 1096 static Handle create_initial_thread_group(TRAPS) { 1097 Handle system_instance = JavaCalls::construct_new_instance( 1098 SystemDictionary::ThreadGroup_klass(), 1099 vmSymbols::void_method_signature(), 1100 CHECK_NH); 1101 Universe::set_system_thread_group(system_instance()); 1102 1103 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1104 Handle main_instance = JavaCalls::construct_new_instance( 1105 SystemDictionary::ThreadGroup_klass(), 1106 vmSymbols::threadgroup_string_void_signature(), 1107 system_instance, 1108 string, 1109 CHECK_NH); 1110 return main_instance; 1111 } 1112 1113 // Creates the initial Thread 1114 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1115 TRAPS) { 1116 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1117 assert(ik->is_initialized(), "must be"); 1118 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1119 1120 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1121 // constructor calls Thread.current(), which must be set here for the 1122 // initial thread. 1123 java_lang_Thread::set_thread(thread_oop(), thread); 1124 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1125 thread->set_threadObj(thread_oop()); 1126 1127 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1128 1129 JavaValue result(T_VOID); 1130 JavaCalls::call_special(&result, thread_oop, 1131 ik, 1132 vmSymbols::object_initializer_name(), 1133 vmSymbols::threadgroup_string_void_signature(), 1134 thread_group, 1135 string, 1136 CHECK_NULL); 1137 return thread_oop(); 1138 } 1139 1140 char java_runtime_name[128] = ""; 1141 char java_runtime_version[128] = ""; 1142 1143 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1144 static const char* get_java_runtime_name(TRAPS) { 1145 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1146 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1147 fieldDescriptor fd; 1148 bool found = k != NULL && 1149 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1150 vmSymbols::string_signature(), &fd); 1151 if (found) { 1152 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1153 if (name_oop == NULL) { 1154 return NULL; 1155 } 1156 const char* name = java_lang_String::as_utf8_string(name_oop, 1157 java_runtime_name, 1158 sizeof(java_runtime_name)); 1159 return name; 1160 } else { 1161 return NULL; 1162 } 1163 } 1164 1165 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1166 static const char* get_java_runtime_version(TRAPS) { 1167 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1168 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1169 fieldDescriptor fd; 1170 bool found = k != NULL && 1171 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1172 vmSymbols::string_signature(), &fd); 1173 if (found) { 1174 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1175 if (name_oop == NULL) { 1176 return NULL; 1177 } 1178 const char* name = java_lang_String::as_utf8_string(name_oop, 1179 java_runtime_version, 1180 sizeof(java_runtime_version)); 1181 return name; 1182 } else { 1183 return NULL; 1184 } 1185 } 1186 1187 // General purpose hook into Java code, run once when the VM is initialized. 1188 // The Java library method itself may be changed independently from the VM. 1189 static void call_postVMInitHook(TRAPS) { 1190 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1191 if (klass != NULL) { 1192 JavaValue result(T_VOID); 1193 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1194 vmSymbols::void_method_signature(), 1195 CHECK); 1196 } 1197 } 1198 1199 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1200 bool daemon, TRAPS) { 1201 assert(thread_group.not_null(), "thread group should be specified"); 1202 assert(threadObj() == NULL, "should only create Java thread object once"); 1203 1204 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1205 assert(ik->is_initialized(), "must be"); 1206 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1207 1208 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1209 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1210 // constructor calls Thread.current(), which must be set here. 1211 java_lang_Thread::set_thread(thread_oop(), this); 1212 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1213 set_threadObj(thread_oop()); 1214 1215 JavaValue result(T_VOID); 1216 if (thread_name != NULL) { 1217 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1218 // Thread gets assigned specified name and null target 1219 JavaCalls::call_special(&result, 1220 thread_oop, 1221 ik, 1222 vmSymbols::object_initializer_name(), 1223 vmSymbols::threadgroup_string_void_signature(), 1224 thread_group, 1225 name, 1226 THREAD); 1227 } else { 1228 // Thread gets assigned name "Thread-nnn" and null target 1229 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1230 JavaCalls::call_special(&result, 1231 thread_oop, 1232 ik, 1233 vmSymbols::object_initializer_name(), 1234 vmSymbols::threadgroup_runnable_void_signature(), 1235 thread_group, 1236 Handle(), 1237 THREAD); 1238 } 1239 1240 1241 if (daemon) { 1242 java_lang_Thread::set_daemon(thread_oop()); 1243 } 1244 1245 if (HAS_PENDING_EXCEPTION) { 1246 return; 1247 } 1248 1249 Klass* group = SystemDictionary::ThreadGroup_klass(); 1250 Handle threadObj(THREAD, this->threadObj()); 1251 1252 JavaCalls::call_special(&result, 1253 thread_group, 1254 group, 1255 vmSymbols::add_method_name(), 1256 vmSymbols::thread_void_signature(), 1257 threadObj, // Arg 1 1258 THREAD); 1259 } 1260 1261 // List of all NonJavaThreads and safe iteration over that list. 1262 1263 class NonJavaThread::List { 1264 public: 1265 NonJavaThread* volatile _head; 1266 SingleWriterSynchronizer _protect; 1267 1268 List() : _head(NULL), _protect() {} 1269 }; 1270 1271 NonJavaThread::List NonJavaThread::_the_list; 1272 1273 NonJavaThread::Iterator::Iterator() : 1274 _protect_enter(_the_list._protect.enter()), 1275 _current(OrderAccess::load_acquire(&_the_list._head)) 1276 {} 1277 1278 NonJavaThread::Iterator::~Iterator() { 1279 _the_list._protect.exit(_protect_enter); 1280 } 1281 1282 void NonJavaThread::Iterator::step() { 1283 assert(!end(), "precondition"); 1284 _current = OrderAccess::load_acquire(&_current->_next); 1285 } 1286 1287 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1288 assert(BarrierSet::barrier_set() != NULL, "NonJavaThread created too soon!"); 1289 } 1290 1291 NonJavaThread::~NonJavaThread() { } 1292 1293 void NonJavaThread::add_to_the_list() { 1294 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1295 _next = _the_list._head; 1296 OrderAccess::release_store(&_the_list._head, this); 1297 } 1298 1299 void NonJavaThread::remove_from_the_list() { 1300 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1301 NonJavaThread* volatile* p = &_the_list._head; 1302 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1303 if (t == this) { 1304 *p = this->_next; 1305 // Wait for any in-progress iterators. Concurrent synchronize is 1306 // not allowed, so do it while holding the list lock. 1307 _the_list._protect.synchronize(); 1308 break; 1309 } 1310 } 1311 } 1312 1313 void NonJavaThread::pre_run() { 1314 // Initialize BarrierSet-related data before adding to list. 1315 assert(BarrierSet::barrier_set() != NULL, "invariant"); 1316 BarrierSet::barrier_set()->on_thread_attach(this); 1317 add_to_the_list(); 1318 1319 // This is slightly odd in that NamedThread is a subclass, but 1320 // in fact name() is defined in Thread 1321 assert(this->name() != NULL, "thread name was not set before it was started"); 1322 this->set_native_thread_name(this->name()); 1323 } 1324 1325 void NonJavaThread::post_run() { 1326 JFR_ONLY(Jfr::on_thread_exit(this);) 1327 // Clean up BarrierSet data before removing from list. 1328 BarrierSet::barrier_set()->on_thread_detach(this); 1329 remove_from_the_list(); 1330 // Ensure thread-local-storage is cleared before termination. 1331 Thread::clear_thread_current(); 1332 } 1333 1334 // NamedThread -- non-JavaThread subclasses with multiple 1335 // uniquely named instances should derive from this. 1336 NamedThread::NamedThread() : 1337 NonJavaThread(), 1338 _name(NULL), 1339 _processed_thread(NULL), 1340 _gc_id(GCId::undefined()) 1341 {} 1342 1343 NamedThread::~NamedThread() { 1344 if (_name != NULL) { 1345 FREE_C_HEAP_ARRAY(char, _name); 1346 _name = NULL; 1347 } 1348 } 1349 1350 void NamedThread::set_name(const char* format, ...) { 1351 guarantee(_name == NULL, "Only get to set name once."); 1352 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1353 guarantee(_name != NULL, "alloc failure"); 1354 va_list ap; 1355 va_start(ap, format); 1356 jio_vsnprintf(_name, max_name_len, format, ap); 1357 va_end(ap); 1358 } 1359 1360 void NamedThread::print_on(outputStream* st) const { 1361 st->print("\"%s\" ", name()); 1362 Thread::print_on(st); 1363 st->cr(); 1364 } 1365 1366 1367 // ======= WatcherThread ======== 1368 1369 // The watcher thread exists to simulate timer interrupts. It should 1370 // be replaced by an abstraction over whatever native support for 1371 // timer interrupts exists on the platform. 1372 1373 WatcherThread* WatcherThread::_watcher_thread = NULL; 1374 bool WatcherThread::_startable = false; 1375 volatile bool WatcherThread::_should_terminate = false; 1376 1377 WatcherThread::WatcherThread() : NonJavaThread() { 1378 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1379 if (os::create_thread(this, os::watcher_thread)) { 1380 _watcher_thread = this; 1381 1382 // Set the watcher thread to the highest OS priority which should not be 1383 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1384 // is created. The only normal thread using this priority is the reference 1385 // handler thread, which runs for very short intervals only. 1386 // If the VMThread's priority is not lower than the WatcherThread profiling 1387 // will be inaccurate. 1388 os::set_priority(this, MaxPriority); 1389 if (!DisableStartThread) { 1390 os::start_thread(this); 1391 } 1392 } 1393 } 1394 1395 int WatcherThread::sleep() const { 1396 // The WatcherThread does not participate in the safepoint protocol 1397 // for the PeriodicTask_lock because it is not a JavaThread. 1398 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1399 1400 if (_should_terminate) { 1401 // check for termination before we do any housekeeping or wait 1402 return 0; // we did not sleep. 1403 } 1404 1405 // remaining will be zero if there are no tasks, 1406 // causing the WatcherThread to sleep until a task is 1407 // enrolled 1408 int remaining = PeriodicTask::time_to_wait(); 1409 int time_slept = 0; 1410 1411 // we expect this to timeout - we only ever get unparked when 1412 // we should terminate or when a new task has been enrolled 1413 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1414 1415 jlong time_before_loop = os::javaTimeNanos(); 1416 1417 while (true) { 1418 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1419 remaining); 1420 jlong now = os::javaTimeNanos(); 1421 1422 if (remaining == 0) { 1423 // if we didn't have any tasks we could have waited for a long time 1424 // consider the time_slept zero and reset time_before_loop 1425 time_slept = 0; 1426 time_before_loop = now; 1427 } else { 1428 // need to recalculate since we might have new tasks in _tasks 1429 time_slept = (int) ((now - time_before_loop) / 1000000); 1430 } 1431 1432 // Change to task list or spurious wakeup of some kind 1433 if (timedout || _should_terminate) { 1434 break; 1435 } 1436 1437 remaining = PeriodicTask::time_to_wait(); 1438 if (remaining == 0) { 1439 // Last task was just disenrolled so loop around and wait until 1440 // another task gets enrolled 1441 continue; 1442 } 1443 1444 remaining -= time_slept; 1445 if (remaining <= 0) { 1446 break; 1447 } 1448 } 1449 1450 return time_slept; 1451 } 1452 1453 void WatcherThread::run() { 1454 assert(this == watcher_thread(), "just checking"); 1455 1456 this->set_active_handles(JNIHandleBlock::allocate_block()); 1457 while (true) { 1458 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1459 assert(watcher_thread() == this, "thread consistency check"); 1460 1461 // Calculate how long it'll be until the next PeriodicTask work 1462 // should be done, and sleep that amount of time. 1463 int time_waited = sleep(); 1464 1465 if (VMError::is_error_reported()) { 1466 // A fatal error has happened, the error handler(VMError::report_and_die) 1467 // should abort JVM after creating an error log file. However in some 1468 // rare cases, the error handler itself might deadlock. Here periodically 1469 // check for error reporting timeouts, and if it happens, just proceed to 1470 // abort the VM. 1471 1472 // This code is in WatcherThread because WatcherThread wakes up 1473 // periodically so the fatal error handler doesn't need to do anything; 1474 // also because the WatcherThread is less likely to crash than other 1475 // threads. 1476 1477 for (;;) { 1478 // Note: we use naked sleep in this loop because we want to avoid using 1479 // any kind of VM infrastructure which may be broken at this point. 1480 if (VMError::check_timeout()) { 1481 // We hit error reporting timeout. Error reporting was interrupted and 1482 // will be wrapping things up now (closing files etc). Give it some more 1483 // time, then quit the VM. 1484 os::naked_short_sleep(200); 1485 // Print a message to stderr. 1486 fdStream err(defaultStream::output_fd()); 1487 err.print_raw_cr("# [ timer expired, abort... ]"); 1488 // skip atexit/vm_exit/vm_abort hooks 1489 os::die(); 1490 } 1491 1492 // Wait a second, then recheck for timeout. 1493 os::naked_short_sleep(999); 1494 } 1495 } 1496 1497 if (_should_terminate) { 1498 // check for termination before posting the next tick 1499 break; 1500 } 1501 1502 PeriodicTask::real_time_tick(time_waited); 1503 } 1504 1505 // Signal that it is terminated 1506 { 1507 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1508 _watcher_thread = NULL; 1509 Terminator_lock->notify(); 1510 } 1511 } 1512 1513 void WatcherThread::start() { 1514 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1515 1516 if (watcher_thread() == NULL && _startable) { 1517 _should_terminate = false; 1518 // Create the single instance of WatcherThread 1519 new WatcherThread(); 1520 } 1521 } 1522 1523 void WatcherThread::make_startable() { 1524 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1525 _startable = true; 1526 } 1527 1528 void WatcherThread::stop() { 1529 { 1530 // Follow normal safepoint aware lock enter protocol since the 1531 // WatcherThread is stopped by another JavaThread. 1532 MutexLocker ml(PeriodicTask_lock); 1533 _should_terminate = true; 1534 1535 WatcherThread* watcher = watcher_thread(); 1536 if (watcher != NULL) { 1537 // unpark the WatcherThread so it can see that it should terminate 1538 watcher->unpark(); 1539 } 1540 } 1541 1542 MutexLocker mu(Terminator_lock); 1543 1544 while (watcher_thread() != NULL) { 1545 // This wait should make safepoint checks, wait without a timeout, 1546 // and wait as a suspend-equivalent condition. 1547 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1548 Mutex::_as_suspend_equivalent_flag); 1549 } 1550 } 1551 1552 void WatcherThread::unpark() { 1553 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1554 PeriodicTask_lock->notify(); 1555 } 1556 1557 void WatcherThread::print_on(outputStream* st) const { 1558 st->print("\"%s\" ", name()); 1559 Thread::print_on(st); 1560 st->cr(); 1561 } 1562 1563 // ======= JavaThread ======== 1564 1565 #if INCLUDE_JVMCI 1566 1567 jlong* JavaThread::_jvmci_old_thread_counters; 1568 1569 bool jvmci_counters_include(JavaThread* thread) { 1570 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1571 } 1572 1573 void JavaThread::collect_counters(typeArrayOop array) { 1574 if (JVMCICounterSize > 0) { 1575 JavaThreadIteratorWithHandle jtiwh; 1576 for (int i = 0; i < array->length(); i++) { 1577 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1578 } 1579 for (; JavaThread *tp = jtiwh.next(); ) { 1580 if (jvmci_counters_include(tp)) { 1581 for (int i = 0; i < array->length(); i++) { 1582 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1583 } 1584 } 1585 } 1586 } 1587 } 1588 1589 #endif // INCLUDE_JVMCI 1590 1591 // A JavaThread is a normal Java thread 1592 1593 void JavaThread::initialize() { 1594 // Initialize fields 1595 1596 set_saved_exception_pc(NULL); 1597 set_threadObj(NULL); 1598 _anchor.clear(); 1599 set_entry_point(NULL); 1600 set_jni_functions(jni_functions()); 1601 set_callee_target(NULL); 1602 set_vm_result(NULL); 1603 set_vm_result_2(NULL); 1604 set_vframe_array_head(NULL); 1605 set_vframe_array_last(NULL); 1606 set_deferred_locals(NULL); 1607 set_deopt_mark(NULL); 1608 set_deopt_compiled_method(NULL); 1609 clear_must_deopt_id(); 1610 set_monitor_chunks(NULL); 1611 set_next(NULL); 1612 _on_thread_list = false; 1613 set_thread_state(_thread_new); 1614 _terminated = _not_terminated; 1615 _array_for_gc = NULL; 1616 _suspend_equivalent = false; 1617 _in_deopt_handler = 0; 1618 _doing_unsafe_access = false; 1619 _stack_guard_state = stack_guard_unused; 1620 #if INCLUDE_JVMCI 1621 _pending_monitorenter = false; 1622 _pending_deoptimization = -1; 1623 _pending_failed_speculation = 0; 1624 _pending_transfer_to_interpreter = false; 1625 _adjusting_comp_level = false; 1626 _in_retryable_allocation = false; 1627 _jvmci._alternate_call_target = NULL; 1628 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1629 if (JVMCICounterSize > 0) { 1630 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1631 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1632 } else { 1633 _jvmci_counters = NULL; 1634 } 1635 #endif // INCLUDE_JVMCI 1636 _reserved_stack_activation = NULL; // stack base not known yet 1637 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1638 _exception_pc = 0; 1639 _exception_handler_pc = 0; 1640 _is_method_handle_return = 0; 1641 _jvmti_thread_state= NULL; 1642 _should_post_on_exceptions_flag = JNI_FALSE; 1643 _interp_only_mode = 0; 1644 _special_runtime_exit_condition = _no_async_condition; 1645 _pending_async_exception = NULL; 1646 _thread_stat = NULL; 1647 _thread_stat = new ThreadStatistics(); 1648 _blocked_on_compilation = false; 1649 _jni_active_critical = 0; 1650 _pending_jni_exception_check_fn = NULL; 1651 _do_not_unlock_if_synchronized = false; 1652 _cached_monitor_info = NULL; 1653 _parker = Parker::Allocate(this); 1654 1655 #ifndef PRODUCT 1656 _jmp_ring_index = 0; 1657 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1658 record_jump(NULL, NULL, NULL, 0); 1659 } 1660 #endif // PRODUCT 1661 1662 // Setup safepoint state info for this thread 1663 ThreadSafepointState::create(this); 1664 1665 debug_only(_java_call_counter = 0); 1666 1667 // JVMTI PopFrame support 1668 _popframe_condition = popframe_inactive; 1669 _popframe_preserved_args = NULL; 1670 _popframe_preserved_args_size = 0; 1671 _frames_to_pop_failed_realloc = 0; 1672 1673 if (SafepointMechanism::uses_thread_local_poll()) { 1674 SafepointMechanism::initialize_header(this); 1675 } 1676 1677 _class_to_be_initialized = NULL; 1678 1679 pd_initialize(); 1680 } 1681 1682 JavaThread::JavaThread(bool is_attaching_via_jni) : 1683 Thread() { 1684 initialize(); 1685 if (is_attaching_via_jni) { 1686 _jni_attach_state = _attaching_via_jni; 1687 } else { 1688 _jni_attach_state = _not_attaching_via_jni; 1689 } 1690 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1691 } 1692 1693 bool JavaThread::reguard_stack(address cur_sp) { 1694 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1695 && _stack_guard_state != stack_guard_reserved_disabled) { 1696 return true; // Stack already guarded or guard pages not needed. 1697 } 1698 1699 if (register_stack_overflow()) { 1700 // For those architectures which have separate register and 1701 // memory stacks, we must check the register stack to see if 1702 // it has overflowed. 1703 return false; 1704 } 1705 1706 // Java code never executes within the yellow zone: the latter is only 1707 // there to provoke an exception during stack banging. If java code 1708 // is executing there, either StackShadowPages should be larger, or 1709 // some exception code in c1, c2 or the interpreter isn't unwinding 1710 // when it should. 1711 guarantee(cur_sp > stack_reserved_zone_base(), 1712 "not enough space to reguard - increase StackShadowPages"); 1713 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1714 enable_stack_yellow_reserved_zone(); 1715 if (reserved_stack_activation() != stack_base()) { 1716 set_reserved_stack_activation(stack_base()); 1717 } 1718 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1719 set_reserved_stack_activation(stack_base()); 1720 enable_stack_reserved_zone(); 1721 } 1722 return true; 1723 } 1724 1725 bool JavaThread::reguard_stack(void) { 1726 return reguard_stack(os::current_stack_pointer()); 1727 } 1728 1729 1730 void JavaThread::block_if_vm_exited() { 1731 if (_terminated == _vm_exited) { 1732 // _vm_exited is set at safepoint, and Threads_lock is never released 1733 // we will block here forever 1734 Threads_lock->lock_without_safepoint_check(); 1735 ShouldNotReachHere(); 1736 } 1737 } 1738 1739 1740 // Remove this ifdef when C1 is ported to the compiler interface. 1741 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1742 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1743 1744 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1745 Thread() { 1746 initialize(); 1747 _jni_attach_state = _not_attaching_via_jni; 1748 set_entry_point(entry_point); 1749 // Create the native thread itself. 1750 // %note runtime_23 1751 os::ThreadType thr_type = os::java_thread; 1752 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1753 os::java_thread; 1754 os::create_thread(this, thr_type, stack_sz); 1755 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1756 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1757 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1758 // the exception consists of creating the exception object & initializing it, initialization 1759 // will leave the VM via a JavaCall and then all locks must be unlocked). 1760 // 1761 // The thread is still suspended when we reach here. Thread must be explicit started 1762 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1763 // by calling Threads:add. The reason why this is not done here, is because the thread 1764 // object must be fully initialized (take a look at JVM_Start) 1765 } 1766 1767 JavaThread::~JavaThread() { 1768 1769 // JSR166 -- return the parker to the free list 1770 Parker::Release(_parker); 1771 _parker = NULL; 1772 1773 // Free any remaining previous UnrollBlock 1774 vframeArray* old_array = vframe_array_last(); 1775 1776 if (old_array != NULL) { 1777 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1778 old_array->set_unroll_block(NULL); 1779 delete old_info; 1780 delete old_array; 1781 } 1782 1783 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1784 if (deferred != NULL) { 1785 // This can only happen if thread is destroyed before deoptimization occurs. 1786 assert(deferred->length() != 0, "empty array!"); 1787 do { 1788 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1789 deferred->remove_at(0); 1790 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1791 delete dlv; 1792 } while (deferred->length() != 0); 1793 delete deferred; 1794 } 1795 1796 // All Java related clean up happens in exit 1797 ThreadSafepointState::destroy(this); 1798 if (_thread_stat != NULL) delete _thread_stat; 1799 1800 #if INCLUDE_JVMCI 1801 if (JVMCICounterSize > 0) { 1802 if (jvmci_counters_include(this)) { 1803 for (int i = 0; i < JVMCICounterSize; i++) { 1804 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1805 } 1806 } 1807 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1808 } 1809 #endif // INCLUDE_JVMCI 1810 } 1811 1812 1813 // First JavaThread specific code executed by a new Java thread. 1814 void JavaThread::pre_run() { 1815 // empty - see comments in run() 1816 } 1817 1818 // The main routine called by a new Java thread. This isn't overridden 1819 // by subclasses, instead different subclasses define a different "entry_point" 1820 // which defines the actual logic for that kind of thread. 1821 void JavaThread::run() { 1822 // initialize thread-local alloc buffer related fields 1823 this->initialize_tlab(); 1824 1825 // Used to test validity of stack trace backs. 1826 // This can't be moved into pre_run() else we invalidate 1827 // the requirement that thread_main_inner is lower on 1828 // the stack. Consequently all the initialization logic 1829 // stays here in run() rather than pre_run(). 1830 this->record_base_of_stack_pointer(); 1831 1832 this->create_stack_guard_pages(); 1833 1834 this->cache_global_variables(); 1835 1836 // Thread is now sufficiently initialized to be handled by the safepoint code as being 1837 // in the VM. Change thread state from _thread_new to _thread_in_vm 1838 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1839 1840 assert(JavaThread::current() == this, "sanity check"); 1841 assert(!Thread::current()->owns_locks(), "sanity check"); 1842 1843 DTRACE_THREAD_PROBE(start, this); 1844 1845 // This operation might block. We call that after all safepoint checks for a new thread has 1846 // been completed. 1847 this->set_active_handles(JNIHandleBlock::allocate_block()); 1848 1849 if (JvmtiExport::should_post_thread_life()) { 1850 JvmtiExport::post_thread_start(this); 1851 1852 } 1853 1854 // We call another function to do the rest so we are sure that the stack addresses used 1855 // from there will be lower than the stack base just computed. 1856 thread_main_inner(); 1857 } 1858 1859 void JavaThread::thread_main_inner() { 1860 assert(JavaThread::current() == this, "sanity check"); 1861 assert(this->threadObj() != NULL, "just checking"); 1862 1863 // Execute thread entry point unless this thread has a pending exception 1864 // or has been stopped before starting. 1865 // Note: Due to JVM_StopThread we can have pending exceptions already! 1866 if (!this->has_pending_exception() && 1867 !java_lang_Thread::is_stillborn(this->threadObj())) { 1868 { 1869 ResourceMark rm(this); 1870 this->set_native_thread_name(this->get_thread_name()); 1871 } 1872 HandleMark hm(this); 1873 this->entry_point()(this, this); 1874 } 1875 1876 DTRACE_THREAD_PROBE(stop, this); 1877 1878 // Cleanup is handled in post_run() 1879 } 1880 1881 // Shared teardown for all JavaThreads 1882 void JavaThread::post_run() { 1883 this->exit(false); 1884 // Defer deletion to here to ensure 'this' is still referenceable in call_run 1885 // for any shared tear-down. 1886 this->smr_delete(); 1887 } 1888 1889 static void ensure_join(JavaThread* thread) { 1890 // We do not need to grab the Threads_lock, since we are operating on ourself. 1891 Handle threadObj(thread, thread->threadObj()); 1892 assert(threadObj.not_null(), "java thread object must exist"); 1893 ObjectLocker lock(threadObj, thread); 1894 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1895 thread->clear_pending_exception(); 1896 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1897 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1898 // Clear the native thread instance - this makes isAlive return false and allows the join() 1899 // to complete once we've done the notify_all below 1900 java_lang_Thread::set_thread(threadObj(), NULL); 1901 lock.notify_all(thread); 1902 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1903 thread->clear_pending_exception(); 1904 } 1905 1906 static bool is_daemon(oop threadObj) { 1907 return (threadObj != NULL && java_lang_Thread::is_daemon(threadObj)); 1908 } 1909 1910 // For any new cleanup additions, please check to see if they need to be applied to 1911 // cleanup_failed_attach_current_thread as well. 1912 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1913 assert(this == JavaThread::current(), "thread consistency check"); 1914 1915 elapsedTimer _timer_exit_phase1; 1916 elapsedTimer _timer_exit_phase2; 1917 elapsedTimer _timer_exit_phase3; 1918 elapsedTimer _timer_exit_phase4; 1919 1920 if (log_is_enabled(Debug, os, thread, timer)) { 1921 _timer_exit_phase1.start(); 1922 } 1923 1924 HandleMark hm(this); 1925 Handle uncaught_exception(this, this->pending_exception()); 1926 this->clear_pending_exception(); 1927 Handle threadObj(this, this->threadObj()); 1928 assert(threadObj.not_null(), "Java thread object should be created"); 1929 1930 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1931 { 1932 EXCEPTION_MARK; 1933 1934 CLEAR_PENDING_EXCEPTION; 1935 } 1936 if (!destroy_vm) { 1937 if (uncaught_exception.not_null()) { 1938 EXCEPTION_MARK; 1939 // Call method Thread.dispatchUncaughtException(). 1940 Klass* thread_klass = SystemDictionary::Thread_klass(); 1941 JavaValue result(T_VOID); 1942 JavaCalls::call_virtual(&result, 1943 threadObj, thread_klass, 1944 vmSymbols::dispatchUncaughtException_name(), 1945 vmSymbols::throwable_void_signature(), 1946 uncaught_exception, 1947 THREAD); 1948 if (HAS_PENDING_EXCEPTION) { 1949 ResourceMark rm(this); 1950 jio_fprintf(defaultStream::error_stream(), 1951 "\nException: %s thrown from the UncaughtExceptionHandler" 1952 " in thread \"%s\"\n", 1953 pending_exception()->klass()->external_name(), 1954 get_thread_name()); 1955 CLEAR_PENDING_EXCEPTION; 1956 } 1957 } 1958 JFR_ONLY(Jfr::on_java_thread_dismantle(this);) 1959 1960 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1961 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1962 // is deprecated anyhow. 1963 if (!is_Compiler_thread()) { 1964 int count = 3; 1965 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1966 EXCEPTION_MARK; 1967 JavaValue result(T_VOID); 1968 Klass* thread_klass = SystemDictionary::Thread_klass(); 1969 JavaCalls::call_virtual(&result, 1970 threadObj, thread_klass, 1971 vmSymbols::exit_method_name(), 1972 vmSymbols::void_method_signature(), 1973 THREAD); 1974 CLEAR_PENDING_EXCEPTION; 1975 } 1976 } 1977 // notify JVMTI 1978 if (JvmtiExport::should_post_thread_life()) { 1979 JvmtiExport::post_thread_end(this); 1980 } 1981 1982 // We have notified the agents that we are exiting, before we go on, 1983 // we must check for a pending external suspend request and honor it 1984 // in order to not surprise the thread that made the suspend request. 1985 while (true) { 1986 { 1987 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1988 if (!is_external_suspend()) { 1989 set_terminated(_thread_exiting); 1990 ThreadService::current_thread_exiting(this, is_daemon(threadObj())); 1991 break; 1992 } 1993 // Implied else: 1994 // Things get a little tricky here. We have a pending external 1995 // suspend request, but we are holding the SR_lock so we 1996 // can't just self-suspend. So we temporarily drop the lock 1997 // and then self-suspend. 1998 } 1999 2000 ThreadBlockInVM tbivm(this); 2001 java_suspend_self(); 2002 2003 // We're done with this suspend request, but we have to loop around 2004 // and check again. Eventually we will get SR_lock without a pending 2005 // external suspend request and will be able to mark ourselves as 2006 // exiting. 2007 } 2008 // no more external suspends are allowed at this point 2009 } else { 2010 assert(!is_terminated() && !is_exiting(), "must not be exiting"); 2011 // before_exit() has already posted JVMTI THREAD_END events 2012 } 2013 2014 if (log_is_enabled(Debug, os, thread, timer)) { 2015 _timer_exit_phase1.stop(); 2016 _timer_exit_phase2.start(); 2017 } 2018 // Notify waiters on thread object. This has to be done after exit() is called 2019 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 2020 // group should have the destroyed bit set before waiters are notified). 2021 ensure_join(this); 2022 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 2023 2024 if (log_is_enabled(Debug, os, thread, timer)) { 2025 _timer_exit_phase2.stop(); 2026 _timer_exit_phase3.start(); 2027 } 2028 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 2029 // held by this thread must be released. The spec does not distinguish 2030 // between JNI-acquired and regular Java monitors. We can only see 2031 // regular Java monitors here if monitor enter-exit matching is broken. 2032 // 2033 // ensure_join() ignores IllegalThreadStateExceptions, and so does 2034 // ObjectSynchronizer::release_monitors_owned_by_thread(). 2035 if (exit_type == jni_detach) { 2036 // Sanity check even though JNI DetachCurrentThread() would have 2037 // returned JNI_ERR if there was a Java frame. JavaThread exit 2038 // should be done executing Java code by the time we get here. 2039 assert(!this->has_last_Java_frame(), 2040 "should not have a Java frame when detaching or exiting"); 2041 ObjectSynchronizer::release_monitors_owned_by_thread(this); 2042 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 2043 } 2044 2045 // These things needs to be done while we are still a Java Thread. Make sure that thread 2046 // is in a consistent state, in case GC happens 2047 JFR_ONLY(Jfr::on_thread_exit(this);) 2048 2049 if (active_handles() != NULL) { 2050 JNIHandleBlock* block = active_handles(); 2051 set_active_handles(NULL); 2052 JNIHandleBlock::release_block(block); 2053 } 2054 2055 if (free_handle_block() != NULL) { 2056 JNIHandleBlock* block = free_handle_block(); 2057 set_free_handle_block(NULL); 2058 JNIHandleBlock::release_block(block); 2059 } 2060 2061 // These have to be removed while this is still a valid thread. 2062 remove_stack_guard_pages(); 2063 2064 if (UseTLAB) { 2065 tlab().retire(); 2066 } 2067 2068 if (JvmtiEnv::environments_might_exist()) { 2069 JvmtiExport::cleanup_thread(this); 2070 } 2071 2072 // We must flush any deferred card marks and other various GC barrier 2073 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2074 // before removing a thread from the list of active threads. 2075 BarrierSet::barrier_set()->on_thread_detach(this); 2076 2077 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2078 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2079 os::current_thread_id()); 2080 2081 if (log_is_enabled(Debug, os, thread, timer)) { 2082 _timer_exit_phase3.stop(); 2083 _timer_exit_phase4.start(); 2084 } 2085 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2086 Threads::remove(this); 2087 2088 if (log_is_enabled(Debug, os, thread, timer)) { 2089 _timer_exit_phase4.stop(); 2090 ResourceMark rm(this); 2091 log_debug(os, thread, timer)("name='%s'" 2092 ", exit-phase1=" JLONG_FORMAT 2093 ", exit-phase2=" JLONG_FORMAT 2094 ", exit-phase3=" JLONG_FORMAT 2095 ", exit-phase4=" JLONG_FORMAT, 2096 get_thread_name(), 2097 _timer_exit_phase1.milliseconds(), 2098 _timer_exit_phase2.milliseconds(), 2099 _timer_exit_phase3.milliseconds(), 2100 _timer_exit_phase4.milliseconds()); 2101 } 2102 } 2103 2104 void JavaThread::cleanup_failed_attach_current_thread() { 2105 if (active_handles() != NULL) { 2106 JNIHandleBlock* block = active_handles(); 2107 set_active_handles(NULL); 2108 JNIHandleBlock::release_block(block); 2109 } 2110 2111 if (free_handle_block() != NULL) { 2112 JNIHandleBlock* block = free_handle_block(); 2113 set_free_handle_block(NULL); 2114 JNIHandleBlock::release_block(block); 2115 } 2116 2117 // These have to be removed while this is still a valid thread. 2118 remove_stack_guard_pages(); 2119 2120 if (UseTLAB) { 2121 tlab().retire(); 2122 } 2123 2124 BarrierSet::barrier_set()->on_thread_detach(this); 2125 2126 Threads::remove(this); 2127 this->smr_delete(); 2128 } 2129 2130 JavaThread* JavaThread::active() { 2131 Thread* thread = Thread::current(); 2132 if (thread->is_Java_thread()) { 2133 return (JavaThread*) thread; 2134 } else { 2135 assert(thread->is_VM_thread(), "this must be a vm thread"); 2136 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2137 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2138 assert(ret->is_Java_thread(), "must be a Java thread"); 2139 return ret; 2140 } 2141 } 2142 2143 bool JavaThread::is_lock_owned(address adr) const { 2144 if (Thread::is_lock_owned(adr)) return true; 2145 2146 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2147 if (chunk->contains(adr)) return true; 2148 } 2149 2150 return false; 2151 } 2152 2153 2154 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2155 chunk->set_next(monitor_chunks()); 2156 set_monitor_chunks(chunk); 2157 } 2158 2159 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2160 guarantee(monitor_chunks() != NULL, "must be non empty"); 2161 if (monitor_chunks() == chunk) { 2162 set_monitor_chunks(chunk->next()); 2163 } else { 2164 MonitorChunk* prev = monitor_chunks(); 2165 while (prev->next() != chunk) prev = prev->next(); 2166 prev->set_next(chunk->next()); 2167 } 2168 } 2169 2170 // JVM support. 2171 2172 // Note: this function shouldn't block if it's called in 2173 // _thread_in_native_trans state (such as from 2174 // check_special_condition_for_native_trans()). 2175 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2176 2177 if (has_last_Java_frame() && has_async_condition()) { 2178 // If we are at a polling page safepoint (not a poll return) 2179 // then we must defer async exception because live registers 2180 // will be clobbered by the exception path. Poll return is 2181 // ok because the call we a returning from already collides 2182 // with exception handling registers and so there is no issue. 2183 // (The exception handling path kills call result registers but 2184 // this is ok since the exception kills the result anyway). 2185 2186 if (is_at_poll_safepoint()) { 2187 // if the code we are returning to has deoptimized we must defer 2188 // the exception otherwise live registers get clobbered on the 2189 // exception path before deoptimization is able to retrieve them. 2190 // 2191 RegisterMap map(this, false); 2192 frame caller_fr = last_frame().sender(&map); 2193 assert(caller_fr.is_compiled_frame(), "what?"); 2194 if (caller_fr.is_deoptimized_frame()) { 2195 log_info(exceptions)("deferred async exception at compiled safepoint"); 2196 return; 2197 } 2198 } 2199 } 2200 2201 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2202 if (condition == _no_async_condition) { 2203 // Conditions have changed since has_special_runtime_exit_condition() 2204 // was called: 2205 // - if we were here only because of an external suspend request, 2206 // then that was taken care of above (or cancelled) so we are done 2207 // - if we were here because of another async request, then it has 2208 // been cleared between the has_special_runtime_exit_condition() 2209 // and now so again we are done 2210 return; 2211 } 2212 2213 // Check for pending async. exception 2214 if (_pending_async_exception != NULL) { 2215 // Only overwrite an already pending exception, if it is not a threadDeath. 2216 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2217 2218 // We cannot call Exceptions::_throw(...) here because we cannot block 2219 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2220 2221 LogTarget(Info, exceptions) lt; 2222 if (lt.is_enabled()) { 2223 ResourceMark rm; 2224 LogStream ls(lt); 2225 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2226 if (has_last_Java_frame()) { 2227 frame f = last_frame(); 2228 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2229 } 2230 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2231 } 2232 _pending_async_exception = NULL; 2233 clear_has_async_exception(); 2234 } 2235 } 2236 2237 if (check_unsafe_error && 2238 condition == _async_unsafe_access_error && !has_pending_exception()) { 2239 condition = _no_async_condition; // done 2240 switch (thread_state()) { 2241 case _thread_in_vm: { 2242 JavaThread* THREAD = this; 2243 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2244 } 2245 case _thread_in_native: { 2246 ThreadInVMfromNative tiv(this); 2247 JavaThread* THREAD = this; 2248 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2249 } 2250 case _thread_in_Java: { 2251 ThreadInVMfromJava tiv(this); 2252 JavaThread* THREAD = this; 2253 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2254 } 2255 default: 2256 ShouldNotReachHere(); 2257 } 2258 } 2259 2260 assert(condition == _no_async_condition || has_pending_exception() || 2261 (!check_unsafe_error && condition == _async_unsafe_access_error), 2262 "must have handled the async condition, if no exception"); 2263 } 2264 2265 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2266 // 2267 // Check for pending external suspend. 2268 // If JNIEnv proxies are allowed, don't self-suspend if the target 2269 // thread is not the current thread. In older versions of jdbx, jdbx 2270 // threads could call into the VM with another thread's JNIEnv so we 2271 // can be here operating on behalf of a suspended thread (4432884). 2272 bool do_self_suspend = is_external_suspend_with_lock(); 2273 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2274 frame_anchor()->make_walkable(this); 2275 java_suspend_self_with_safepoint_check(); 2276 } 2277 2278 // We might be here for reasons in addition to the self-suspend request 2279 // so check for other async requests. 2280 if (check_asyncs) { 2281 check_and_handle_async_exceptions(); 2282 } 2283 2284 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2285 } 2286 2287 void JavaThread::send_thread_stop(oop java_throwable) { 2288 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2289 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2290 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2291 2292 // Do not throw asynchronous exceptions against the compiler thread 2293 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2294 if (!can_call_java()) return; 2295 2296 { 2297 // Actually throw the Throwable against the target Thread - however 2298 // only if there is no thread death exception installed already. 2299 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2300 // If the topmost frame is a runtime stub, then we are calling into 2301 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2302 // must deoptimize the caller before continuing, as the compiled exception handler table 2303 // may not be valid 2304 if (has_last_Java_frame()) { 2305 frame f = last_frame(); 2306 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2307 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2308 RegisterMap reg_map(this, UseBiasedLocking); 2309 frame compiled_frame = f.sender(®_map); 2310 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2311 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2312 } 2313 } 2314 } 2315 2316 // Set async. pending exception in thread. 2317 set_pending_async_exception(java_throwable); 2318 2319 if (log_is_enabled(Info, exceptions)) { 2320 ResourceMark rm; 2321 log_info(exceptions)("Pending Async. exception installed of type: %s", 2322 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2323 } 2324 // for AbortVMOnException flag 2325 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2326 } 2327 } 2328 2329 2330 // Interrupt thread so it will wake up from a potential wait() 2331 Thread::interrupt(this); 2332 } 2333 2334 // External suspension mechanism. 2335 // 2336 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2337 // to any VM_locks and it is at a transition 2338 // Self-suspension will happen on the transition out of the vm. 2339 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2340 // 2341 // Guarantees on return: 2342 // + Target thread will not execute any new bytecode (that's why we need to 2343 // force a safepoint) 2344 // + Target thread will not enter any new monitors 2345 // 2346 void JavaThread::java_suspend() { 2347 ThreadsListHandle tlh; 2348 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2349 return; 2350 } 2351 2352 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2353 if (!is_external_suspend()) { 2354 // a racing resume has cancelled us; bail out now 2355 return; 2356 } 2357 2358 // suspend is done 2359 uint32_t debug_bits = 0; 2360 // Warning: is_ext_suspend_completed() may temporarily drop the 2361 // SR_lock to allow the thread to reach a stable thread state if 2362 // it is currently in a transient thread state. 2363 if (is_ext_suspend_completed(false /* !called_by_wait */, 2364 SuspendRetryDelay, &debug_bits)) { 2365 return; 2366 } 2367 } 2368 2369 if (Thread::current() == this) { 2370 // Safely self-suspend. 2371 // If we don't do this explicitly it will implicitly happen 2372 // before we transition back to Java, and on some other thread-state 2373 // transition paths, but not as we exit a JVM TI SuspendThread call. 2374 // As SuspendThread(current) must not return (until resumed) we must 2375 // self-suspend here. 2376 ThreadBlockInVM tbivm(this); 2377 java_suspend_self(); 2378 } else { 2379 VM_ThreadSuspend vm_suspend; 2380 VMThread::execute(&vm_suspend); 2381 } 2382 } 2383 2384 // Part II of external suspension. 2385 // A JavaThread self suspends when it detects a pending external suspend 2386 // request. This is usually on transitions. It is also done in places 2387 // where continuing to the next transition would surprise the caller, 2388 // e.g., monitor entry. 2389 // 2390 // Returns the number of times that the thread self-suspended. 2391 // 2392 // Note: DO NOT call java_suspend_self() when you just want to block current 2393 // thread. java_suspend_self() is the second stage of cooperative 2394 // suspension for external suspend requests and should only be used 2395 // to complete an external suspend request. 2396 // 2397 int JavaThread::java_suspend_self() { 2398 assert(thread_state() == _thread_blocked, "wrong state for java_suspend_self()"); 2399 int ret = 0; 2400 2401 // we are in the process of exiting so don't suspend 2402 if (is_exiting()) { 2403 clear_external_suspend(); 2404 return ret; 2405 } 2406 2407 assert(_anchor.walkable() || 2408 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2409 "must have walkable stack"); 2410 2411 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2412 2413 assert(!this->is_ext_suspended(), 2414 "a thread trying to self-suspend should not already be suspended"); 2415 2416 if (this->is_suspend_equivalent()) { 2417 // If we are self-suspending as a result of the lifting of a 2418 // suspend equivalent condition, then the suspend_equivalent 2419 // flag is not cleared until we set the ext_suspended flag so 2420 // that wait_for_ext_suspend_completion() returns consistent 2421 // results. 2422 this->clear_suspend_equivalent(); 2423 } 2424 2425 // A racing resume may have cancelled us before we grabbed SR_lock 2426 // above. Or another external suspend request could be waiting for us 2427 // by the time we return from SR_lock()->wait(). The thread 2428 // that requested the suspension may already be trying to walk our 2429 // stack and if we return now, we can change the stack out from under 2430 // it. This would be a "bad thing (TM)" and cause the stack walker 2431 // to crash. We stay self-suspended until there are no more pending 2432 // external suspend requests. 2433 while (is_external_suspend()) { 2434 ret++; 2435 this->set_ext_suspended(); 2436 2437 // _ext_suspended flag is cleared by java_resume() 2438 while (is_ext_suspended()) { 2439 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2440 } 2441 } 2442 2443 return ret; 2444 } 2445 2446 // Helper routine to set up the correct thread state before calling java_suspend_self. 2447 // This is called when regular thread-state transition helpers can't be used because 2448 // we can be in various states, in particular _thread_in_native_trans. 2449 // Because this thread is external suspended the safepoint code will count it as at 2450 // a safepoint, regardless of what it's actual current thread-state is. But 2451 // is_ext_suspend_completed() may be waiting to see a thread transition from 2452 // _thread_in_native_trans to _thread_blocked. So we set the thread state directly 2453 // to _thread_blocked. The problem with setting thread state directly is that a 2454 // safepoint could happen just after java_suspend_self() returns after being resumed, 2455 // and the VM thread will see the _thread_blocked state. So we must check for a safepoint 2456 // after restoring the state to make sure we won't leave while a safepoint is in progress. 2457 void JavaThread::java_suspend_self_with_safepoint_check() { 2458 assert(this == Thread::current(), "invariant"); 2459 JavaThreadState state = thread_state(); 2460 set_thread_state(_thread_blocked); 2461 java_suspend_self(); 2462 set_thread_state(state); 2463 InterfaceSupport::serialize_thread_state_with_handler(this); 2464 SafepointMechanism::block_if_requested(this); 2465 } 2466 2467 #ifdef ASSERT 2468 // Verify the JavaThread has not yet been published in the Threads::list, and 2469 // hence doesn't need protection from concurrent access at this stage. 2470 void JavaThread::verify_not_published() { 2471 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2472 // since an unpublished JavaThread doesn't participate in the 2473 // Thread-SMR protocol for keeping a ThreadsList alive. 2474 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2475 } 2476 #endif 2477 2478 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2479 // progress or when _suspend_flags is non-zero. 2480 // Current thread needs to self-suspend if there is a suspend request and/or 2481 // block if a safepoint is in progress. 2482 // Async exception ISN'T checked. 2483 // Note only the ThreadInVMfromNative transition can call this function 2484 // directly and when thread state is _thread_in_native_trans 2485 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2486 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2487 2488 JavaThread *curJT = JavaThread::current(); 2489 bool do_self_suspend = thread->is_external_suspend(); 2490 2491 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2492 2493 // If JNIEnv proxies are allowed, don't self-suspend if the target 2494 // thread is not the current thread. In older versions of jdbx, jdbx 2495 // threads could call into the VM with another thread's JNIEnv so we 2496 // can be here operating on behalf of a suspended thread (4432884). 2497 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2498 thread->java_suspend_self_with_safepoint_check(); 2499 } else { 2500 SafepointMechanism::block_if_requested(curJT); 2501 } 2502 2503 if (thread->is_deopt_suspend()) { 2504 thread->clear_deopt_suspend(); 2505 RegisterMap map(thread, false); 2506 frame f = thread->last_frame(); 2507 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2508 f = f.sender(&map); 2509 } 2510 if (f.id() == thread->must_deopt_id()) { 2511 thread->clear_must_deopt_id(); 2512 f.deoptimize(thread); 2513 } else { 2514 fatal("missed deoptimization!"); 2515 } 2516 } 2517 2518 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2519 } 2520 2521 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2522 // progress or when _suspend_flags is non-zero. 2523 // Current thread needs to self-suspend if there is a suspend request and/or 2524 // block if a safepoint is in progress. 2525 // Also check for pending async exception (not including unsafe access error). 2526 // Note only the native==>VM/Java barriers can call this function and when 2527 // thread state is _thread_in_native_trans. 2528 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2529 check_safepoint_and_suspend_for_native_trans(thread); 2530 2531 if (thread->has_async_exception()) { 2532 // We are in _thread_in_native_trans state, don't handle unsafe 2533 // access error since that may block. 2534 thread->check_and_handle_async_exceptions(false); 2535 } 2536 } 2537 2538 // This is a variant of the normal 2539 // check_special_condition_for_native_trans with slightly different 2540 // semantics for use by critical native wrappers. It does all the 2541 // normal checks but also performs the transition back into 2542 // thread_in_Java state. This is required so that critical natives 2543 // can potentially block and perform a GC if they are the last thread 2544 // exiting the GCLocker. 2545 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2546 check_special_condition_for_native_trans(thread); 2547 2548 // Finish the transition 2549 thread->set_thread_state(_thread_in_Java); 2550 2551 if (thread->do_critical_native_unlock()) { 2552 ThreadInVMfromJavaNoAsyncException tiv(thread); 2553 GCLocker::unlock_critical(thread); 2554 thread->clear_critical_native_unlock(); 2555 } 2556 } 2557 2558 // We need to guarantee the Threads_lock here, since resumes are not 2559 // allowed during safepoint synchronization 2560 // Can only resume from an external suspension 2561 void JavaThread::java_resume() { 2562 assert_locked_or_safepoint(Threads_lock); 2563 2564 // Sanity check: thread is gone, has started exiting or the thread 2565 // was not externally suspended. 2566 ThreadsListHandle tlh; 2567 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2568 return; 2569 } 2570 2571 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2572 2573 clear_external_suspend(); 2574 2575 if (is_ext_suspended()) { 2576 clear_ext_suspended(); 2577 SR_lock()->notify_all(); 2578 } 2579 } 2580 2581 size_t JavaThread::_stack_red_zone_size = 0; 2582 size_t JavaThread::_stack_yellow_zone_size = 0; 2583 size_t JavaThread::_stack_reserved_zone_size = 0; 2584 size_t JavaThread::_stack_shadow_zone_size = 0; 2585 2586 void JavaThread::create_stack_guard_pages() { 2587 if (!os::uses_stack_guard_pages() || 2588 _stack_guard_state != stack_guard_unused || 2589 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2590 log_info(os, thread)("Stack guard page creation for thread " 2591 UINTX_FORMAT " disabled", os::current_thread_id()); 2592 return; 2593 } 2594 address low_addr = stack_end(); 2595 size_t len = stack_guard_zone_size(); 2596 2597 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2598 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2599 2600 int must_commit = os::must_commit_stack_guard_pages(); 2601 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2602 2603 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2604 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2605 return; 2606 } 2607 2608 if (os::guard_memory((char *) low_addr, len)) { 2609 _stack_guard_state = stack_guard_enabled; 2610 } else { 2611 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2612 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2613 if (os::uncommit_memory((char *) low_addr, len)) { 2614 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2615 } 2616 return; 2617 } 2618 2619 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2620 PTR_FORMAT "-" PTR_FORMAT ".", 2621 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2622 } 2623 2624 void JavaThread::remove_stack_guard_pages() { 2625 assert(Thread::current() == this, "from different thread"); 2626 if (_stack_guard_state == stack_guard_unused) return; 2627 address low_addr = stack_end(); 2628 size_t len = stack_guard_zone_size(); 2629 2630 if (os::must_commit_stack_guard_pages()) { 2631 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2632 _stack_guard_state = stack_guard_unused; 2633 } else { 2634 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2635 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2636 return; 2637 } 2638 } else { 2639 if (_stack_guard_state == stack_guard_unused) return; 2640 if (os::unguard_memory((char *) low_addr, len)) { 2641 _stack_guard_state = stack_guard_unused; 2642 } else { 2643 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2644 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2645 return; 2646 } 2647 } 2648 2649 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2650 PTR_FORMAT "-" PTR_FORMAT ".", 2651 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2652 } 2653 2654 void JavaThread::enable_stack_reserved_zone() { 2655 assert(_stack_guard_state == stack_guard_reserved_disabled, "inconsistent state"); 2656 2657 // The base notation is from the stack's point of view, growing downward. 2658 // We need to adjust it to work correctly with guard_memory() 2659 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2660 2661 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2662 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2663 2664 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2665 _stack_guard_state = stack_guard_enabled; 2666 } else { 2667 warning("Attempt to guard stack reserved zone failed."); 2668 } 2669 enable_register_stack_guard(); 2670 } 2671 2672 void JavaThread::disable_stack_reserved_zone() { 2673 assert(_stack_guard_state == stack_guard_enabled, "inconsistent state"); 2674 2675 // Simply return if called for a thread that does not use guard pages. 2676 if (_stack_guard_state != stack_guard_enabled) return; 2677 2678 // The base notation is from the stack's point of view, growing downward. 2679 // We need to adjust it to work correctly with guard_memory() 2680 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2681 2682 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2683 _stack_guard_state = stack_guard_reserved_disabled; 2684 } else { 2685 warning("Attempt to unguard stack reserved zone failed."); 2686 } 2687 disable_register_stack_guard(); 2688 } 2689 2690 void JavaThread::enable_stack_yellow_reserved_zone() { 2691 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2692 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2693 2694 // The base notation is from the stacks point of view, growing downward. 2695 // We need to adjust it to work correctly with guard_memory() 2696 address base = stack_red_zone_base(); 2697 2698 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2699 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2700 2701 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2702 _stack_guard_state = stack_guard_enabled; 2703 } else { 2704 warning("Attempt to guard stack yellow zone failed."); 2705 } 2706 enable_register_stack_guard(); 2707 } 2708 2709 void JavaThread::disable_stack_yellow_reserved_zone() { 2710 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2711 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2712 2713 // Simply return if called for a thread that does not use guard pages. 2714 if (_stack_guard_state == stack_guard_unused) return; 2715 2716 // The base notation is from the stacks point of view, growing downward. 2717 // We need to adjust it to work correctly with guard_memory() 2718 address base = stack_red_zone_base(); 2719 2720 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2721 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2722 } else { 2723 warning("Attempt to unguard stack yellow zone failed."); 2724 } 2725 disable_register_stack_guard(); 2726 } 2727 2728 void JavaThread::enable_stack_red_zone() { 2729 // The base notation is from the stacks point of view, growing downward. 2730 // We need to adjust it to work correctly with guard_memory() 2731 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2732 address base = stack_red_zone_base() - stack_red_zone_size(); 2733 2734 guarantee(base < stack_base(), "Error calculating stack red zone"); 2735 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2736 2737 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2738 warning("Attempt to guard stack red zone failed."); 2739 } 2740 } 2741 2742 void JavaThread::disable_stack_red_zone() { 2743 // The base notation is from the stacks point of view, growing downward. 2744 // We need to adjust it to work correctly with guard_memory() 2745 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2746 address base = stack_red_zone_base() - stack_red_zone_size(); 2747 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2748 warning("Attempt to unguard stack red zone failed."); 2749 } 2750 } 2751 2752 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2753 // ignore is there is no stack 2754 if (!has_last_Java_frame()) return; 2755 // traverse the stack frames. Starts from top frame. 2756 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2757 frame* fr = fst.current(); 2758 f(fr, fst.register_map()); 2759 } 2760 } 2761 2762 2763 #ifndef PRODUCT 2764 // Deoptimization 2765 // Function for testing deoptimization 2766 void JavaThread::deoptimize() { 2767 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2768 StackFrameStream fst(this, UseBiasedLocking); 2769 bool deopt = false; // Dump stack only if a deopt actually happens. 2770 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2771 // Iterate over all frames in the thread and deoptimize 2772 for (; !fst.is_done(); fst.next()) { 2773 if (fst.current()->can_be_deoptimized()) { 2774 2775 if (only_at) { 2776 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2777 // consists of comma or carriage return separated numbers so 2778 // search for the current bci in that string. 2779 address pc = fst.current()->pc(); 2780 nmethod* nm = (nmethod*) fst.current()->cb(); 2781 ScopeDesc* sd = nm->scope_desc_at(pc); 2782 char buffer[8]; 2783 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2784 size_t len = strlen(buffer); 2785 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2786 while (found != NULL) { 2787 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2788 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2789 // Check that the bci found is bracketed by terminators. 2790 break; 2791 } 2792 found = strstr(found + 1, buffer); 2793 } 2794 if (!found) { 2795 continue; 2796 } 2797 } 2798 2799 if (DebugDeoptimization && !deopt) { 2800 deopt = true; // One-time only print before deopt 2801 tty->print_cr("[BEFORE Deoptimization]"); 2802 trace_frames(); 2803 trace_stack(); 2804 } 2805 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2806 } 2807 } 2808 2809 if (DebugDeoptimization && deopt) { 2810 tty->print_cr("[AFTER Deoptimization]"); 2811 trace_frames(); 2812 } 2813 } 2814 2815 2816 // Make zombies 2817 void JavaThread::make_zombies() { 2818 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2819 if (fst.current()->can_be_deoptimized()) { 2820 // it is a Java nmethod 2821 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2822 nm->make_not_entrant(); 2823 } 2824 } 2825 } 2826 #endif // PRODUCT 2827 2828 2829 void JavaThread::deoptimized_wrt_marked_nmethods() { 2830 if (!has_last_Java_frame()) return; 2831 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2832 StackFrameStream fst(this, UseBiasedLocking); 2833 for (; !fst.is_done(); fst.next()) { 2834 if (fst.current()->should_be_deoptimized()) { 2835 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2836 } 2837 } 2838 } 2839 2840 2841 // If the caller is a NamedThread, then remember, in the current scope, 2842 // the given JavaThread in its _processed_thread field. 2843 class RememberProcessedThread: public StackObj { 2844 NamedThread* _cur_thr; 2845 public: 2846 RememberProcessedThread(JavaThread* jthr) { 2847 Thread* thread = Thread::current(); 2848 if (thread->is_Named_thread()) { 2849 _cur_thr = (NamedThread *)thread; 2850 _cur_thr->set_processed_thread(jthr); 2851 } else { 2852 _cur_thr = NULL; 2853 } 2854 } 2855 2856 ~RememberProcessedThread() { 2857 if (_cur_thr) { 2858 _cur_thr->set_processed_thread(NULL); 2859 } 2860 } 2861 }; 2862 2863 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2864 // Verify that the deferred card marks have been flushed. 2865 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2866 2867 // Traverse the GCHandles 2868 Thread::oops_do(f, cf); 2869 2870 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2871 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2872 2873 if (has_last_Java_frame()) { 2874 // Record JavaThread to GC thread 2875 RememberProcessedThread rpt(this); 2876 2877 // traverse the registered growable array 2878 if (_array_for_gc != NULL) { 2879 for (int index = 0; index < _array_for_gc->length(); index++) { 2880 f->do_oop(_array_for_gc->adr_at(index)); 2881 } 2882 } 2883 2884 // Traverse the monitor chunks 2885 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2886 chunk->oops_do(f); 2887 } 2888 2889 // Traverse the execution stack 2890 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2891 fst.current()->oops_do(f, cf, fst.register_map()); 2892 } 2893 } 2894 2895 // callee_target is never live across a gc point so NULL it here should 2896 // it still contain a methdOop. 2897 2898 set_callee_target(NULL); 2899 2900 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2901 // If we have deferred set_locals there might be oops waiting to be 2902 // written 2903 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2904 if (list != NULL) { 2905 for (int i = 0; i < list->length(); i++) { 2906 list->at(i)->oops_do(f); 2907 } 2908 } 2909 2910 // Traverse instance variables at the end since the GC may be moving things 2911 // around using this function 2912 f->do_oop((oop*) &_threadObj); 2913 f->do_oop((oop*) &_vm_result); 2914 f->do_oop((oop*) &_exception_oop); 2915 f->do_oop((oop*) &_pending_async_exception); 2916 2917 if (jvmti_thread_state() != NULL) { 2918 jvmti_thread_state()->oops_do(f); 2919 } 2920 } 2921 2922 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2923 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2924 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2925 2926 if (has_last_Java_frame()) { 2927 // Traverse the execution stack 2928 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2929 fst.current()->nmethods_do(cf); 2930 } 2931 } 2932 } 2933 2934 void JavaThread::metadata_do(MetadataClosure* f) { 2935 if (has_last_Java_frame()) { 2936 // Traverse the execution stack to call f() on the methods in the stack 2937 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2938 fst.current()->metadata_do(f); 2939 } 2940 } else if (is_Compiler_thread()) { 2941 // need to walk ciMetadata in current compile tasks to keep alive. 2942 CompilerThread* ct = (CompilerThread*)this; 2943 if (ct->env() != NULL) { 2944 ct->env()->metadata_do(f); 2945 } 2946 CompileTask* task = ct->task(); 2947 if (task != NULL) { 2948 task->metadata_do(f); 2949 } 2950 } 2951 } 2952 2953 // Printing 2954 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2955 switch (_thread_state) { 2956 case _thread_uninitialized: return "_thread_uninitialized"; 2957 case _thread_new: return "_thread_new"; 2958 case _thread_new_trans: return "_thread_new_trans"; 2959 case _thread_in_native: return "_thread_in_native"; 2960 case _thread_in_native_trans: return "_thread_in_native_trans"; 2961 case _thread_in_vm: return "_thread_in_vm"; 2962 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2963 case _thread_in_Java: return "_thread_in_Java"; 2964 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2965 case _thread_blocked: return "_thread_blocked"; 2966 case _thread_blocked_trans: return "_thread_blocked_trans"; 2967 default: return "unknown thread state"; 2968 } 2969 } 2970 2971 #ifndef PRODUCT 2972 void JavaThread::print_thread_state_on(outputStream *st) const { 2973 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2974 }; 2975 void JavaThread::print_thread_state() const { 2976 print_thread_state_on(tty); 2977 } 2978 #endif // PRODUCT 2979 2980 // Called by Threads::print() for VM_PrintThreads operation 2981 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2982 st->print_raw("\""); 2983 st->print_raw(get_thread_name()); 2984 st->print_raw("\" "); 2985 oop thread_oop = threadObj(); 2986 if (thread_oop != NULL) { 2987 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2988 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2989 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2990 } 2991 Thread::print_on(st, print_extended_info); 2992 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2993 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2994 if (thread_oop != NULL) { 2995 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2996 } 2997 #ifndef PRODUCT 2998 _safepoint_state->print_on(st); 2999 #endif // PRODUCT 3000 if (is_Compiler_thread()) { 3001 CompileTask *task = ((CompilerThread*)this)->task(); 3002 if (task != NULL) { 3003 st->print(" Compiling: "); 3004 task->print(st, NULL, true, false); 3005 } else { 3006 st->print(" No compile task"); 3007 } 3008 st->cr(); 3009 } 3010 } 3011 3012 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 3013 st->print("%s", get_thread_name_string(buf, buflen)); 3014 } 3015 3016 // Called by fatal error handler. The difference between this and 3017 // JavaThread::print() is that we can't grab lock or allocate memory. 3018 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3019 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3020 oop thread_obj = threadObj(); 3021 if (thread_obj != NULL) { 3022 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3023 } 3024 st->print(" ["); 3025 st->print("%s", _get_thread_state_name(_thread_state)); 3026 if (osthread()) { 3027 st->print(", id=%d", osthread()->thread_id()); 3028 } 3029 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3030 p2i(stack_end()), p2i(stack_base())); 3031 st->print("]"); 3032 3033 ThreadsSMRSupport::print_info_on(this, st); 3034 return; 3035 } 3036 3037 // Verification 3038 3039 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3040 3041 void JavaThread::verify() { 3042 // Verify oops in the thread. 3043 oops_do(&VerifyOopClosure::verify_oop, NULL); 3044 3045 // Verify the stack frames. 3046 frames_do(frame_verify); 3047 } 3048 3049 // CR 6300358 (sub-CR 2137150) 3050 // Most callers of this method assume that it can't return NULL but a 3051 // thread may not have a name whilst it is in the process of attaching to 3052 // the VM - see CR 6412693, and there are places where a JavaThread can be 3053 // seen prior to having it's threadObj set (eg JNI attaching threads and 3054 // if vm exit occurs during initialization). These cases can all be accounted 3055 // for such that this method never returns NULL. 3056 const char* JavaThread::get_thread_name() const { 3057 #ifdef ASSERT 3058 // early safepoints can hit while current thread does not yet have TLS 3059 if (!SafepointSynchronize::is_at_safepoint()) { 3060 Thread *cur = Thread::current(); 3061 if (!(cur->is_Java_thread() && cur == this)) { 3062 // Current JavaThreads are allowed to get their own name without 3063 // the Threads_lock. 3064 assert_locked_or_safepoint(Threads_lock); 3065 } 3066 } 3067 #endif // ASSERT 3068 return get_thread_name_string(); 3069 } 3070 3071 // Returns a non-NULL representation of this thread's name, or a suitable 3072 // descriptive string if there is no set name 3073 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3074 const char* name_str; 3075 oop thread_obj = threadObj(); 3076 if (thread_obj != NULL) { 3077 oop name = java_lang_Thread::name(thread_obj); 3078 if (name != NULL) { 3079 if (buf == NULL) { 3080 name_str = java_lang_String::as_utf8_string(name); 3081 } else { 3082 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3083 } 3084 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3085 name_str = "<no-name - thread is attaching>"; 3086 } else { 3087 name_str = Thread::name(); 3088 } 3089 } else { 3090 name_str = Thread::name(); 3091 } 3092 assert(name_str != NULL, "unexpected NULL thread name"); 3093 return name_str; 3094 } 3095 3096 3097 const char* JavaThread::get_threadgroup_name() const { 3098 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3099 oop thread_obj = threadObj(); 3100 if (thread_obj != NULL) { 3101 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3102 if (thread_group != NULL) { 3103 // ThreadGroup.name can be null 3104 return java_lang_ThreadGroup::name(thread_group); 3105 } 3106 } 3107 return NULL; 3108 } 3109 3110 const char* JavaThread::get_parent_name() const { 3111 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3112 oop thread_obj = threadObj(); 3113 if (thread_obj != NULL) { 3114 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3115 if (thread_group != NULL) { 3116 oop parent = java_lang_ThreadGroup::parent(thread_group); 3117 if (parent != NULL) { 3118 // ThreadGroup.name can be null 3119 return java_lang_ThreadGroup::name(parent); 3120 } 3121 } 3122 } 3123 return NULL; 3124 } 3125 3126 ThreadPriority JavaThread::java_priority() const { 3127 oop thr_oop = threadObj(); 3128 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3129 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3130 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3131 return priority; 3132 } 3133 3134 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3135 3136 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3137 // Link Java Thread object <-> C++ Thread 3138 3139 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3140 // and put it into a new Handle. The Handle "thread_oop" can then 3141 // be used to pass the C++ thread object to other methods. 3142 3143 // Set the Java level thread object (jthread) field of the 3144 // new thread (a JavaThread *) to C++ thread object using the 3145 // "thread_oop" handle. 3146 3147 // Set the thread field (a JavaThread *) of the 3148 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3149 3150 Handle thread_oop(Thread::current(), 3151 JNIHandles::resolve_non_null(jni_thread)); 3152 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3153 "must be initialized"); 3154 set_threadObj(thread_oop()); 3155 java_lang_Thread::set_thread(thread_oop(), this); 3156 3157 if (prio == NoPriority) { 3158 prio = java_lang_Thread::priority(thread_oop()); 3159 assert(prio != NoPriority, "A valid priority should be present"); 3160 } 3161 3162 // Push the Java priority down to the native thread; needs Threads_lock 3163 Thread::set_priority(this, prio); 3164 3165 // Add the new thread to the Threads list and set it in motion. 3166 // We must have threads lock in order to call Threads::add. 3167 // It is crucial that we do not block before the thread is 3168 // added to the Threads list for if a GC happens, then the java_thread oop 3169 // will not be visited by GC. 3170 Threads::add(this); 3171 } 3172 3173 oop JavaThread::current_park_blocker() { 3174 // Support for JSR-166 locks 3175 oop thread_oop = threadObj(); 3176 if (thread_oop != NULL && 3177 JDK_Version::current().supports_thread_park_blocker()) { 3178 return java_lang_Thread::park_blocker(thread_oop); 3179 } 3180 return NULL; 3181 } 3182 3183 3184 void JavaThread::print_stack_on(outputStream* st) { 3185 if (!has_last_Java_frame()) return; 3186 ResourceMark rm; 3187 HandleMark hm; 3188 3189 RegisterMap reg_map(this); 3190 vframe* start_vf = last_java_vframe(®_map); 3191 int count = 0; 3192 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3193 if (f->is_java_frame()) { 3194 javaVFrame* jvf = javaVFrame::cast(f); 3195 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3196 3197 // Print out lock information 3198 if (JavaMonitorsInStackTrace) { 3199 jvf->print_lock_info_on(st, count); 3200 } 3201 } else { 3202 // Ignore non-Java frames 3203 } 3204 3205 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3206 count++; 3207 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3208 } 3209 } 3210 3211 3212 // JVMTI PopFrame support 3213 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3214 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3215 if (in_bytes(size_in_bytes) != 0) { 3216 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3217 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3218 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3219 } 3220 } 3221 3222 void* JavaThread::popframe_preserved_args() { 3223 return _popframe_preserved_args; 3224 } 3225 3226 ByteSize JavaThread::popframe_preserved_args_size() { 3227 return in_ByteSize(_popframe_preserved_args_size); 3228 } 3229 3230 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3231 int sz = in_bytes(popframe_preserved_args_size()); 3232 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3233 return in_WordSize(sz / wordSize); 3234 } 3235 3236 void JavaThread::popframe_free_preserved_args() { 3237 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3238 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3239 _popframe_preserved_args = NULL; 3240 _popframe_preserved_args_size = 0; 3241 } 3242 3243 #ifndef PRODUCT 3244 3245 void JavaThread::trace_frames() { 3246 tty->print_cr("[Describe stack]"); 3247 int frame_no = 1; 3248 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3249 tty->print(" %d. ", frame_no++); 3250 fst.current()->print_value_on(tty, this); 3251 tty->cr(); 3252 } 3253 } 3254 3255 class PrintAndVerifyOopClosure: public OopClosure { 3256 protected: 3257 template <class T> inline void do_oop_work(T* p) { 3258 oop obj = RawAccess<>::oop_load(p); 3259 if (obj == NULL) return; 3260 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3261 if (oopDesc::is_oop_or_null(obj)) { 3262 if (obj->is_objArray()) { 3263 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3264 } else { 3265 obj->print(); 3266 } 3267 } else { 3268 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3269 } 3270 tty->cr(); 3271 } 3272 public: 3273 virtual void do_oop(oop* p) { do_oop_work(p); } 3274 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3275 }; 3276 3277 3278 static void oops_print(frame* f, const RegisterMap *map) { 3279 PrintAndVerifyOopClosure print; 3280 f->print_value(); 3281 f->oops_do(&print, NULL, (RegisterMap*)map); 3282 } 3283 3284 // Print our all the locations that contain oops and whether they are 3285 // valid or not. This useful when trying to find the oldest frame 3286 // where an oop has gone bad since the frame walk is from youngest to 3287 // oldest. 3288 void JavaThread::trace_oops() { 3289 tty->print_cr("[Trace oops]"); 3290 frames_do(oops_print); 3291 } 3292 3293 3294 #ifdef ASSERT 3295 // Print or validate the layout of stack frames 3296 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3297 ResourceMark rm; 3298 PRESERVE_EXCEPTION_MARK; 3299 FrameValues values; 3300 int frame_no = 0; 3301 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3302 fst.current()->describe(values, ++frame_no); 3303 if (depth == frame_no) break; 3304 } 3305 if (validate_only) { 3306 values.validate(); 3307 } else { 3308 tty->print_cr("[Describe stack layout]"); 3309 values.print(this); 3310 } 3311 } 3312 #endif 3313 3314 void JavaThread::trace_stack_from(vframe* start_vf) { 3315 ResourceMark rm; 3316 int vframe_no = 1; 3317 for (vframe* f = start_vf; f; f = f->sender()) { 3318 if (f->is_java_frame()) { 3319 javaVFrame::cast(f)->print_activation(vframe_no++); 3320 } else { 3321 f->print(); 3322 } 3323 if (vframe_no > StackPrintLimit) { 3324 tty->print_cr("...<more frames>..."); 3325 return; 3326 } 3327 } 3328 } 3329 3330 3331 void JavaThread::trace_stack() { 3332 if (!has_last_Java_frame()) return; 3333 ResourceMark rm; 3334 HandleMark hm; 3335 RegisterMap reg_map(this); 3336 trace_stack_from(last_java_vframe(®_map)); 3337 } 3338 3339 3340 #endif // PRODUCT 3341 3342 3343 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3344 assert(reg_map != NULL, "a map must be given"); 3345 frame f = last_frame(); 3346 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3347 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3348 } 3349 return NULL; 3350 } 3351 3352 3353 Klass* JavaThread::security_get_caller_class(int depth) { 3354 vframeStream vfst(this); 3355 vfst.security_get_caller_frame(depth); 3356 if (!vfst.at_end()) { 3357 return vfst.method()->method_holder(); 3358 } 3359 return NULL; 3360 } 3361 3362 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3363 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3364 CompileBroker::compiler_thread_loop(); 3365 } 3366 3367 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3368 NMethodSweeper::sweeper_loop(); 3369 } 3370 3371 // Create a CompilerThread 3372 CompilerThread::CompilerThread(CompileQueue* queue, 3373 CompilerCounters* counters) 3374 : JavaThread(&compiler_thread_entry) { 3375 _env = NULL; 3376 _log = NULL; 3377 _task = NULL; 3378 _queue = queue; 3379 _counters = counters; 3380 _buffer_blob = NULL; 3381 _compiler = NULL; 3382 3383 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3384 resource_area()->bias_to(mtCompiler); 3385 3386 #ifndef PRODUCT 3387 _ideal_graph_printer = NULL; 3388 #endif 3389 } 3390 3391 CompilerThread::~CompilerThread() { 3392 // Delete objects which were allocated on heap. 3393 delete _counters; 3394 } 3395 3396 bool CompilerThread::can_call_java() const { 3397 return _compiler != NULL && _compiler->is_jvmci(); 3398 } 3399 3400 // Create sweeper thread 3401 CodeCacheSweeperThread::CodeCacheSweeperThread() 3402 : JavaThread(&sweeper_thread_entry) { 3403 _scanned_compiled_method = NULL; 3404 } 3405 3406 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3407 JavaThread::oops_do(f, cf); 3408 if (_scanned_compiled_method != NULL && cf != NULL) { 3409 // Safepoints can occur when the sweeper is scanning an nmethod so 3410 // process it here to make sure it isn't unloaded in the middle of 3411 // a scan. 3412 cf->do_code_blob(_scanned_compiled_method); 3413 } 3414 } 3415 3416 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3417 JavaThread::nmethods_do(cf); 3418 if (_scanned_compiled_method != NULL && cf != NULL) { 3419 // Safepoints can occur when the sweeper is scanning an nmethod so 3420 // process it here to make sure it isn't unloaded in the middle of 3421 // a scan. 3422 cf->do_code_blob(_scanned_compiled_method); 3423 } 3424 } 3425 3426 3427 // ======= Threads ======== 3428 3429 // The Threads class links together all active threads, and provides 3430 // operations over all threads. It is protected by the Threads_lock, 3431 // which is also used in other global contexts like safepointing. 3432 // ThreadsListHandles are used to safely perform operations on one 3433 // or more threads without the risk of the thread exiting during the 3434 // operation. 3435 // 3436 // Note: The Threads_lock is currently more widely used than we 3437 // would like. We are actively migrating Threads_lock uses to other 3438 // mechanisms in order to reduce Threads_lock contention. 3439 3440 JavaThread* Threads::_thread_list = NULL; 3441 int Threads::_number_of_threads = 0; 3442 int Threads::_number_of_non_daemon_threads = 0; 3443 int Threads::_return_code = 0; 3444 int Threads::_thread_claim_parity = 0; 3445 size_t JavaThread::_stack_size_at_create = 0; 3446 3447 #ifdef ASSERT 3448 bool Threads::_vm_complete = false; 3449 #endif 3450 3451 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3452 Prefetch::read((void*)addr, prefetch_interval); 3453 return *addr; 3454 } 3455 3456 // Possibly the ugliest for loop the world has seen. C++ does not allow 3457 // multiple types in the declaration section of the for loop. In this case 3458 // we are only dealing with pointers and hence can cast them. It looks ugly 3459 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3460 #define DO_JAVA_THREADS(LIST, X) \ 3461 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3462 *MACRO_list = (JavaThread*)(LIST), \ 3463 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3464 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3465 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3466 MACRO_current_p != MACRO_end; \ 3467 MACRO_current_p++, \ 3468 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3469 3470 // All JavaThreads 3471 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3472 3473 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3474 void Threads::non_java_threads_do(ThreadClosure* tc) { 3475 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3476 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3477 tc->do_thread(njti.current()); 3478 } 3479 } 3480 3481 // All JavaThreads 3482 void Threads::java_threads_do(ThreadClosure* tc) { 3483 assert_locked_or_safepoint(Threads_lock); 3484 // ALL_JAVA_THREADS iterates through all JavaThreads. 3485 ALL_JAVA_THREADS(p) { 3486 tc->do_thread(p); 3487 } 3488 } 3489 3490 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3491 assert_locked_or_safepoint(Threads_lock); 3492 java_threads_do(tc); 3493 tc->do_thread(VMThread::vm_thread()); 3494 } 3495 3496 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3497 void Threads::threads_do(ThreadClosure* tc) { 3498 assert_locked_or_safepoint(Threads_lock); 3499 java_threads_do(tc); 3500 non_java_threads_do(tc); 3501 } 3502 3503 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3504 int cp = Threads::thread_claim_parity(); 3505 ALL_JAVA_THREADS(p) { 3506 if (p->claim_oops_do(is_par, cp)) { 3507 tc->do_thread(p); 3508 } 3509 } 3510 VMThread* vmt = VMThread::vm_thread(); 3511 if (vmt->claim_oops_do(is_par, cp)) { 3512 tc->do_thread(vmt); 3513 } 3514 } 3515 3516 // The system initialization in the library has three phases. 3517 // 3518 // Phase 1: java.lang.System class initialization 3519 // java.lang.System is a primordial class loaded and initialized 3520 // by the VM early during startup. java.lang.System.<clinit> 3521 // only does registerNatives and keeps the rest of the class 3522 // initialization work later until thread initialization completes. 3523 // 3524 // System.initPhase1 initializes the system properties, the static 3525 // fields in, out, and err. Set up java signal handlers, OS-specific 3526 // system settings, and thread group of the main thread. 3527 static void call_initPhase1(TRAPS) { 3528 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3529 JavaValue result(T_VOID); 3530 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3531 vmSymbols::void_method_signature(), CHECK); 3532 } 3533 3534 // Phase 2. Module system initialization 3535 // This will initialize the module system. Only java.base classes 3536 // can be loaded until phase 2 completes. 3537 // 3538 // Call System.initPhase2 after the compiler initialization and jsr292 3539 // classes get initialized because module initialization runs a lot of java 3540 // code, that for performance reasons, should be compiled. Also, this will 3541 // enable the startup code to use lambda and other language features in this 3542 // phase and onward. 3543 // 3544 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3545 static void call_initPhase2(TRAPS) { 3546 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3547 3548 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3549 3550 JavaValue result(T_INT); 3551 JavaCallArguments args; 3552 args.push_int(DisplayVMOutputToStderr); 3553 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3554 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3555 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3556 if (result.get_jint() != JNI_OK) { 3557 vm_exit_during_initialization(); // no message or exception 3558 } 3559 3560 universe_post_module_init(); 3561 } 3562 3563 // Phase 3. final setup - set security manager, system class loader and TCCL 3564 // 3565 // This will instantiate and set the security manager, set the system class 3566 // loader as well as the thread context class loader. The security manager 3567 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3568 // other modules or the application's classpath. 3569 static void call_initPhase3(TRAPS) { 3570 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3571 JavaValue result(T_VOID); 3572 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3573 vmSymbols::void_method_signature(), CHECK); 3574 } 3575 3576 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3577 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3578 3579 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3580 create_vm_init_libraries(); 3581 } 3582 3583 initialize_class(vmSymbols::java_lang_String(), CHECK); 3584 3585 // Inject CompactStrings value after the static initializers for String ran. 3586 java_lang_String::set_compact_strings(CompactStrings); 3587 3588 // Initialize java_lang.System (needed before creating the thread) 3589 initialize_class(vmSymbols::java_lang_System(), CHECK); 3590 // The VM creates & returns objects of this class. Make sure it's initialized. 3591 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3592 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3593 Handle thread_group = create_initial_thread_group(CHECK); 3594 Universe::set_main_thread_group(thread_group()); 3595 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3596 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3597 main_thread->set_threadObj(thread_object); 3598 // Set thread status to running since main thread has 3599 // been started and running. 3600 java_lang_Thread::set_thread_status(thread_object, 3601 java_lang_Thread::RUNNABLE); 3602 3603 // The VM creates objects of this class. 3604 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3605 3606 // The VM preresolves methods to these classes. Make sure that they get initialized 3607 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3608 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3609 3610 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3611 call_initPhase1(CHECK); 3612 3613 // get the Java runtime name after java.lang.System is initialized 3614 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3615 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3616 3617 // an instance of OutOfMemory exception has been allocated earlier 3618 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3619 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3620 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3621 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3622 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3623 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3624 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3625 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3626 } 3627 3628 void Threads::initialize_jsr292_core_classes(TRAPS) { 3629 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3630 3631 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3632 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3633 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3634 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3635 } 3636 3637 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3638 extern void JDK_Version_init(); 3639 3640 // Preinitialize version info. 3641 VM_Version::early_initialize(); 3642 3643 // Check version 3644 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3645 3646 // Initialize library-based TLS 3647 ThreadLocalStorage::init(); 3648 3649 // Initialize the output stream module 3650 ostream_init(); 3651 3652 // Process java launcher properties. 3653 Arguments::process_sun_java_launcher_properties(args); 3654 3655 // Initialize the os module 3656 os::init(); 3657 3658 // Record VM creation timing statistics 3659 TraceVmCreationTime create_vm_timer; 3660 create_vm_timer.start(); 3661 3662 // Initialize system properties. 3663 Arguments::init_system_properties(); 3664 3665 // So that JDK version can be used as a discriminator when parsing arguments 3666 JDK_Version_init(); 3667 3668 // Update/Initialize System properties after JDK version number is known 3669 Arguments::init_version_specific_system_properties(); 3670 3671 // Make sure to initialize log configuration *before* parsing arguments 3672 LogConfiguration::initialize(create_vm_timer.begin_time()); 3673 3674 // Parse arguments 3675 // Note: this internally calls os::init_container_support() 3676 jint parse_result = Arguments::parse(args); 3677 if (parse_result != JNI_OK) return parse_result; 3678 3679 os::init_before_ergo(); 3680 3681 jint ergo_result = Arguments::apply_ergo(); 3682 if (ergo_result != JNI_OK) return ergo_result; 3683 3684 // Final check of all ranges after ergonomics which may change values. 3685 if (!JVMFlagRangeList::check_ranges()) { 3686 return JNI_EINVAL; 3687 } 3688 3689 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3690 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3691 if (!constraint_result) { 3692 return JNI_EINVAL; 3693 } 3694 3695 JVMFlagWriteableList::mark_startup(); 3696 3697 if (PauseAtStartup) { 3698 os::pause(); 3699 } 3700 3701 HOTSPOT_VM_INIT_BEGIN(); 3702 3703 // Timing (must come after argument parsing) 3704 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3705 3706 // Initialize the os module after parsing the args 3707 jint os_init_2_result = os::init_2(); 3708 if (os_init_2_result != JNI_OK) return os_init_2_result; 3709 3710 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3711 // Initialize assert poison page mechanism. 3712 if (ShowRegistersOnAssert) { 3713 initialize_assert_poison(); 3714 } 3715 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3716 3717 SafepointMechanism::initialize(); 3718 3719 jint adjust_after_os_result = Arguments::adjust_after_os(); 3720 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3721 3722 // Initialize output stream logging 3723 ostream_init_log(); 3724 3725 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3726 // Must be before create_vm_init_agents() 3727 if (Arguments::init_libraries_at_startup()) { 3728 convert_vm_init_libraries_to_agents(); 3729 } 3730 3731 // Launch -agentlib/-agentpath and converted -Xrun agents 3732 if (Arguments::init_agents_at_startup()) { 3733 create_vm_init_agents(); 3734 } 3735 3736 // Initialize Threads state 3737 _thread_list = NULL; 3738 _number_of_threads = 0; 3739 _number_of_non_daemon_threads = 0; 3740 3741 // Initialize global data structures and create system classes in heap 3742 vm_init_globals(); 3743 3744 #if INCLUDE_JVMCI 3745 if (JVMCICounterSize > 0) { 3746 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3747 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3748 } else { 3749 JavaThread::_jvmci_old_thread_counters = NULL; 3750 } 3751 #endif // INCLUDE_JVMCI 3752 3753 // Attach the main thread to this os thread 3754 JavaThread* main_thread = new JavaThread(); 3755 main_thread->set_thread_state(_thread_in_vm); 3756 main_thread->initialize_thread_current(); 3757 // must do this before set_active_handles 3758 main_thread->record_stack_base_and_size(); 3759 main_thread->register_thread_stack_with_NMT(); 3760 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3761 3762 if (!main_thread->set_as_starting_thread()) { 3763 vm_shutdown_during_initialization( 3764 "Failed necessary internal allocation. Out of swap space"); 3765 main_thread->smr_delete(); 3766 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3767 return JNI_ENOMEM; 3768 } 3769 3770 // Enable guard page *after* os::create_main_thread(), otherwise it would 3771 // crash Linux VM, see notes in os_linux.cpp. 3772 main_thread->create_stack_guard_pages(); 3773 3774 // Initialize Java-Level synchronization subsystem 3775 ObjectMonitor::Initialize(); 3776 3777 // Initialize global modules 3778 jint status = init_globals(); 3779 if (status != JNI_OK) { 3780 main_thread->smr_delete(); 3781 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3782 return status; 3783 } 3784 3785 JFR_ONLY(Jfr::on_vm_init();) 3786 3787 // Should be done after the heap is fully created 3788 main_thread->cache_global_variables(); 3789 3790 HandleMark hm; 3791 3792 { MutexLocker mu(Threads_lock); 3793 Threads::add(main_thread); 3794 } 3795 3796 // Any JVMTI raw monitors entered in onload will transition into 3797 // real raw monitor. VM is setup enough here for raw monitor enter. 3798 JvmtiExport::transition_pending_onload_raw_monitors(); 3799 3800 // Create the VMThread 3801 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3802 3803 VMThread::create(); 3804 Thread* vmthread = VMThread::vm_thread(); 3805 3806 if (!os::create_thread(vmthread, os::vm_thread)) { 3807 vm_exit_during_initialization("Cannot create VM thread. " 3808 "Out of system resources."); 3809 } 3810 3811 // Wait for the VM thread to become ready, and VMThread::run to initialize 3812 // Monitors can have spurious returns, must always check another state flag 3813 { 3814 MutexLocker ml(Notify_lock); 3815 os::start_thread(vmthread); 3816 while (vmthread->active_handles() == NULL) { 3817 Notify_lock->wait(); 3818 } 3819 } 3820 } 3821 3822 assert(Universe::is_fully_initialized(), "not initialized"); 3823 if (VerifyDuringStartup) { 3824 // Make sure we're starting with a clean slate. 3825 VM_Verify verify_op; 3826 VMThread::execute(&verify_op); 3827 } 3828 3829 // We need this to update the java.vm.info property in case any flags used 3830 // to initially define it have been changed. This is needed for both CDS and 3831 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3832 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3833 // This update must happen before we initialize the java classes, but 3834 // after any initialization logic that might modify the flags. 3835 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3836 3837 Thread* THREAD = Thread::current(); 3838 3839 // Always call even when there are not JVMTI environments yet, since environments 3840 // may be attached late and JVMTI must track phases of VM execution 3841 JvmtiExport::enter_early_start_phase(); 3842 3843 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3844 JvmtiExport::post_early_vm_start(); 3845 3846 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3847 3848 quicken_jni_functions(); 3849 3850 // No more stub generation allowed after that point. 3851 StubCodeDesc::freeze(); 3852 3853 // Set flag that basic initialization has completed. Used by exceptions and various 3854 // debug stuff, that does not work until all basic classes have been initialized. 3855 set_init_completed(); 3856 3857 LogConfiguration::post_initialize(); 3858 Metaspace::post_initialize(); 3859 3860 HOTSPOT_VM_INIT_END(); 3861 3862 // record VM initialization completion time 3863 #if INCLUDE_MANAGEMENT 3864 Management::record_vm_init_completed(); 3865 #endif // INCLUDE_MANAGEMENT 3866 3867 // Signal Dispatcher needs to be started before VMInit event is posted 3868 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3869 3870 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3871 if (!DisableAttachMechanism) { 3872 AttachListener::vm_start(); 3873 if (StartAttachListener || AttachListener::init_at_startup()) { 3874 AttachListener::init(); 3875 } 3876 } 3877 3878 // Launch -Xrun agents 3879 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3880 // back-end can launch with -Xdebug -Xrunjdwp. 3881 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3882 create_vm_init_libraries(); 3883 } 3884 3885 if (CleanChunkPoolAsync) { 3886 Chunk::start_chunk_pool_cleaner_task(); 3887 } 3888 3889 // initialize compiler(s) 3890 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3891 #if INCLUDE_JVMCI 3892 bool force_JVMCI_intialization = false; 3893 if (EnableJVMCI) { 3894 // Initialize JVMCI eagerly when it is explicitly requested. 3895 // Or when JVMCIPrintProperties is enabled. 3896 // The JVMCI Java initialization code will read this flag and 3897 // do the printing if it's set. 3898 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3899 3900 if (!force_JVMCI_intialization) { 3901 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3902 // compilations via JVMCI will not actually block until JVMCI is initialized. 3903 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3904 } 3905 } 3906 #endif 3907 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3908 // Postpone completion of compiler initialization to after JVMCI 3909 // is initialized to avoid timeouts of blocking compilations. 3910 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3911 CompileBroker::compilation_init_phase2(); 3912 } 3913 #endif 3914 3915 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3916 // It is done after compilers are initialized, because otherwise compilations of 3917 // signature polymorphic MH intrinsics can be missed 3918 // (see SystemDictionary::find_method_handle_intrinsic). 3919 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3920 3921 // This will initialize the module system. Only java.base classes can be 3922 // loaded until phase 2 completes 3923 call_initPhase2(CHECK_JNI_ERR); 3924 3925 // Always call even when there are not JVMTI environments yet, since environments 3926 // may be attached late and JVMTI must track phases of VM execution 3927 JvmtiExport::enter_start_phase(); 3928 3929 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3930 JvmtiExport::post_vm_start(); 3931 3932 // Final system initialization including security manager and system class loader 3933 call_initPhase3(CHECK_JNI_ERR); 3934 3935 // cache the system and platform class loaders 3936 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3937 3938 #if INCLUDE_CDS 3939 if (DumpSharedSpaces) { 3940 // capture the module path info from the ModuleEntryTable 3941 ClassLoader::initialize_module_path(THREAD); 3942 } 3943 #endif 3944 3945 #if INCLUDE_JVMCI 3946 if (force_JVMCI_intialization) { 3947 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3948 CompileBroker::compilation_init_phase2(); 3949 } 3950 #endif 3951 3952 // Always call even when there are not JVMTI environments yet, since environments 3953 // may be attached late and JVMTI must track phases of VM execution 3954 JvmtiExport::enter_live_phase(); 3955 3956 // Make perfmemory accessible 3957 PerfMemory::set_accessible(true); 3958 3959 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3960 JvmtiExport::post_vm_initialized(); 3961 3962 JFR_ONLY(Jfr::on_vm_start();) 3963 3964 #if INCLUDE_MANAGEMENT 3965 Management::initialize(THREAD); 3966 3967 if (HAS_PENDING_EXCEPTION) { 3968 // management agent fails to start possibly due to 3969 // configuration problem and is responsible for printing 3970 // stack trace if appropriate. Simply exit VM. 3971 vm_exit(1); 3972 } 3973 #endif // INCLUDE_MANAGEMENT 3974 3975 if (MemProfiling) MemProfiler::engage(); 3976 StatSampler::engage(); 3977 if (CheckJNICalls) JniPeriodicChecker::engage(); 3978 3979 BiasedLocking::init(); 3980 3981 #if INCLUDE_RTM_OPT 3982 RTMLockingCounters::init(); 3983 #endif 3984 3985 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3986 call_postVMInitHook(THREAD); 3987 // The Java side of PostVMInitHook.run must deal with all 3988 // exceptions and provide means of diagnosis. 3989 if (HAS_PENDING_EXCEPTION) { 3990 CLEAR_PENDING_EXCEPTION; 3991 } 3992 } 3993 3994 { 3995 MutexLocker ml(PeriodicTask_lock); 3996 // Make sure the WatcherThread can be started by WatcherThread::start() 3997 // or by dynamic enrollment. 3998 WatcherThread::make_startable(); 3999 // Start up the WatcherThread if there are any periodic tasks 4000 // NOTE: All PeriodicTasks should be registered by now. If they 4001 // aren't, late joiners might appear to start slowly (we might 4002 // take a while to process their first tick). 4003 if (PeriodicTask::num_tasks() > 0) { 4004 WatcherThread::start(); 4005 } 4006 } 4007 4008 create_vm_timer.end(); 4009 #ifdef ASSERT 4010 _vm_complete = true; 4011 #endif 4012 4013 if (DumpSharedSpaces) { 4014 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4015 ShouldNotReachHere(); 4016 } 4017 4018 return JNI_OK; 4019 } 4020 4021 // type for the Agent_OnLoad and JVM_OnLoad entry points 4022 extern "C" { 4023 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4024 } 4025 // Find a command line agent library and return its entry point for 4026 // -agentlib: -agentpath: -Xrun 4027 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4028 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4029 const char *on_load_symbols[], 4030 size_t num_symbol_entries) { 4031 OnLoadEntry_t on_load_entry = NULL; 4032 void *library = NULL; 4033 4034 if (!agent->valid()) { 4035 char buffer[JVM_MAXPATHLEN]; 4036 char ebuf[1024] = ""; 4037 const char *name = agent->name(); 4038 const char *msg = "Could not find agent library "; 4039 4040 // First check to see if agent is statically linked into executable 4041 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4042 library = agent->os_lib(); 4043 } else if (agent->is_absolute_path()) { 4044 library = os::dll_load(name, ebuf, sizeof ebuf); 4045 if (library == NULL) { 4046 const char *sub_msg = " in absolute path, with error: "; 4047 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4048 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4049 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4050 // If we can't find the agent, exit. 4051 vm_exit_during_initialization(buf, NULL); 4052 FREE_C_HEAP_ARRAY(char, buf); 4053 } 4054 } else { 4055 // Try to load the agent from the standard dll directory 4056 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4057 name)) { 4058 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4059 } 4060 if (library == NULL) { // Try the library path directory. 4061 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4062 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4063 } 4064 if (library == NULL) { 4065 const char *sub_msg = " on the library path, with error: "; 4066 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4067 4068 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4069 strlen(ebuf) + strlen(sub_msg2) + 1; 4070 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4071 if (!agent->is_instrument_lib()) { 4072 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4073 } else { 4074 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4075 } 4076 // If we can't find the agent, exit. 4077 vm_exit_during_initialization(buf, NULL); 4078 FREE_C_HEAP_ARRAY(char, buf); 4079 } 4080 } 4081 } 4082 agent->set_os_lib(library); 4083 agent->set_valid(); 4084 } 4085 4086 // Find the OnLoad function. 4087 on_load_entry = 4088 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4089 false, 4090 on_load_symbols, 4091 num_symbol_entries)); 4092 return on_load_entry; 4093 } 4094 4095 // Find the JVM_OnLoad entry point 4096 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4097 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4098 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4099 } 4100 4101 // Find the Agent_OnLoad entry point 4102 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4103 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4104 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4105 } 4106 4107 // For backwards compatibility with -Xrun 4108 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4109 // treated like -agentpath: 4110 // Must be called before agent libraries are created 4111 void Threads::convert_vm_init_libraries_to_agents() { 4112 AgentLibrary* agent; 4113 AgentLibrary* next; 4114 4115 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4116 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4117 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4118 4119 // If there is an JVM_OnLoad function it will get called later, 4120 // otherwise see if there is an Agent_OnLoad 4121 if (on_load_entry == NULL) { 4122 on_load_entry = lookup_agent_on_load(agent); 4123 if (on_load_entry != NULL) { 4124 // switch it to the agent list -- so that Agent_OnLoad will be called, 4125 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4126 Arguments::convert_library_to_agent(agent); 4127 } else { 4128 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4129 } 4130 } 4131 } 4132 } 4133 4134 // Create agents for -agentlib: -agentpath: and converted -Xrun 4135 // Invokes Agent_OnLoad 4136 // Called very early -- before JavaThreads exist 4137 void Threads::create_vm_init_agents() { 4138 extern struct JavaVM_ main_vm; 4139 AgentLibrary* agent; 4140 4141 JvmtiExport::enter_onload_phase(); 4142 4143 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4144 // CDS dumping does not support native JVMTI agent. 4145 // CDS dumping supports Java agent if the AllowArchivingWithJavaAgent diagnostic option is specified. 4146 if (DumpSharedSpaces) { 4147 if(!agent->is_instrument_lib()) { 4148 vm_exit_during_cds_dumping("CDS dumping does not support native JVMTI agent, name", agent->name()); 4149 } else if (!AllowArchivingWithJavaAgent) { 4150 vm_exit_during_cds_dumping( 4151 "Must enable AllowArchivingWithJavaAgent in order to run Java agent during CDS dumping"); 4152 } 4153 } 4154 4155 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4156 4157 if (on_load_entry != NULL) { 4158 // Invoke the Agent_OnLoad function 4159 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4160 if (err != JNI_OK) { 4161 vm_exit_during_initialization("agent library failed to init", agent->name()); 4162 } 4163 } else { 4164 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4165 } 4166 } 4167 4168 JvmtiExport::enter_primordial_phase(); 4169 } 4170 4171 extern "C" { 4172 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4173 } 4174 4175 void Threads::shutdown_vm_agents() { 4176 // Send any Agent_OnUnload notifications 4177 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4178 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4179 extern struct JavaVM_ main_vm; 4180 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4181 4182 // Find the Agent_OnUnload function. 4183 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4184 os::find_agent_function(agent, 4185 false, 4186 on_unload_symbols, 4187 num_symbol_entries)); 4188 4189 // Invoke the Agent_OnUnload function 4190 if (unload_entry != NULL) { 4191 JavaThread* thread = JavaThread::current(); 4192 ThreadToNativeFromVM ttn(thread); 4193 HandleMark hm(thread); 4194 (*unload_entry)(&main_vm); 4195 } 4196 } 4197 } 4198 4199 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4200 // Invokes JVM_OnLoad 4201 void Threads::create_vm_init_libraries() { 4202 extern struct JavaVM_ main_vm; 4203 AgentLibrary* agent; 4204 4205 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4206 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4207 4208 if (on_load_entry != NULL) { 4209 // Invoke the JVM_OnLoad function 4210 JavaThread* thread = JavaThread::current(); 4211 ThreadToNativeFromVM ttn(thread); 4212 HandleMark hm(thread); 4213 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4214 if (err != JNI_OK) { 4215 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4216 } 4217 } else { 4218 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4219 } 4220 } 4221 } 4222 4223 4224 // Last thread running calls java.lang.Shutdown.shutdown() 4225 void JavaThread::invoke_shutdown_hooks() { 4226 HandleMark hm(this); 4227 4228 // We could get here with a pending exception, if so clear it now. 4229 if (this->has_pending_exception()) { 4230 this->clear_pending_exception(); 4231 } 4232 4233 EXCEPTION_MARK; 4234 Klass* shutdown_klass = 4235 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4236 THREAD); 4237 if (shutdown_klass != NULL) { 4238 // SystemDictionary::resolve_or_null will return null if there was 4239 // an exception. If we cannot load the Shutdown class, just don't 4240 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4241 // won't be run. Note that if a shutdown hook was registered, 4242 // the Shutdown class would have already been loaded 4243 // (Runtime.addShutdownHook will load it). 4244 JavaValue result(T_VOID); 4245 JavaCalls::call_static(&result, 4246 shutdown_klass, 4247 vmSymbols::shutdown_method_name(), 4248 vmSymbols::void_method_signature(), 4249 THREAD); 4250 } 4251 CLEAR_PENDING_EXCEPTION; 4252 } 4253 4254 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4255 // the program falls off the end of main(). Another VM exit path is through 4256 // vm_exit() when the program calls System.exit() to return a value or when 4257 // there is a serious error in VM. The two shutdown paths are not exactly 4258 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4259 // and VM_Exit op at VM level. 4260 // 4261 // Shutdown sequence: 4262 // + Shutdown native memory tracking if it is on 4263 // + Wait until we are the last non-daemon thread to execute 4264 // <-- every thing is still working at this moment --> 4265 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4266 // shutdown hooks 4267 // + Call before_exit(), prepare for VM exit 4268 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4269 // currently the only user of this mechanism is File.deleteOnExit()) 4270 // > stop StatSampler, watcher thread, CMS threads, 4271 // post thread end and vm death events to JVMTI, 4272 // stop signal thread 4273 // + Call JavaThread::exit(), it will: 4274 // > release JNI handle blocks, remove stack guard pages 4275 // > remove this thread from Threads list 4276 // <-- no more Java code from this thread after this point --> 4277 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4278 // the compiler threads at safepoint 4279 // <-- do not use anything that could get blocked by Safepoint --> 4280 // + Disable tracing at JNI/JVM barriers 4281 // + Set _vm_exited flag for threads that are still running native code 4282 // + Call exit_globals() 4283 // > deletes tty 4284 // > deletes PerfMemory resources 4285 // + Delete this thread 4286 // + Return to caller 4287 4288 bool Threads::destroy_vm() { 4289 JavaThread* thread = JavaThread::current(); 4290 4291 #ifdef ASSERT 4292 _vm_complete = false; 4293 #endif 4294 // Wait until we are the last non-daemon thread to execute 4295 { MutexLocker nu(Threads_lock); 4296 while (Threads::number_of_non_daemon_threads() > 1) 4297 // This wait should make safepoint checks, wait without a timeout, 4298 // and wait as a suspend-equivalent condition. 4299 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4300 Mutex::_as_suspend_equivalent_flag); 4301 } 4302 4303 EventShutdown e; 4304 if (e.should_commit()) { 4305 e.set_reason("No remaining non-daemon Java threads"); 4306 e.commit(); 4307 } 4308 4309 // Hang forever on exit if we are reporting an error. 4310 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4311 os::infinite_sleep(); 4312 } 4313 os::wait_for_keypress_at_exit(); 4314 4315 // run Java level shutdown hooks 4316 thread->invoke_shutdown_hooks(); 4317 4318 before_exit(thread); 4319 4320 thread->exit(true); 4321 4322 // Stop VM thread. 4323 { 4324 // 4945125 The vm thread comes to a safepoint during exit. 4325 // GC vm_operations can get caught at the safepoint, and the 4326 // heap is unparseable if they are caught. Grab the Heap_lock 4327 // to prevent this. The GC vm_operations will not be able to 4328 // queue until after the vm thread is dead. After this point, 4329 // we'll never emerge out of the safepoint before the VM exits. 4330 4331 MutexLockerEx ml(Heap_lock, Mutex::_no_safepoint_check_flag); 4332 4333 VMThread::wait_for_vm_thread_exit(); 4334 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4335 VMThread::destroy(); 4336 } 4337 4338 // Now, all Java threads are gone except daemon threads. Daemon threads 4339 // running Java code or in VM are stopped by the Safepoint. However, 4340 // daemon threads executing native code are still running. But they 4341 // will be stopped at native=>Java/VM barriers. Note that we can't 4342 // simply kill or suspend them, as it is inherently deadlock-prone. 4343 4344 VM_Exit::set_vm_exited(); 4345 4346 // Clean up ideal graph printers after the VMThread has started 4347 // the final safepoint which will block all the Compiler threads. 4348 // Note that this Thread has already logically exited so the 4349 // clean_up() function's use of a JavaThreadIteratorWithHandle 4350 // would be a problem except set_vm_exited() has remembered the 4351 // shutdown thread which is granted a policy exception. 4352 #if defined(COMPILER2) && !defined(PRODUCT) 4353 IdealGraphPrinter::clean_up(); 4354 #endif 4355 4356 notify_vm_shutdown(); 4357 4358 // exit_globals() will delete tty 4359 exit_globals(); 4360 4361 // We are after VM_Exit::set_vm_exited() so we can't call 4362 // thread->smr_delete() or we will block on the Threads_lock. 4363 // Deleting the shutdown thread here is safe because another 4364 // JavaThread cannot have an active ThreadsListHandle for 4365 // this JavaThread. 4366 delete thread; 4367 4368 #if INCLUDE_JVMCI 4369 if (JVMCICounterSize > 0) { 4370 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4371 } 4372 #endif 4373 4374 LogConfiguration::finalize(); 4375 4376 return true; 4377 } 4378 4379 4380 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4381 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4382 return is_supported_jni_version(version); 4383 } 4384 4385 4386 jboolean Threads::is_supported_jni_version(jint version) { 4387 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4388 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4389 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4390 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4391 if (version == JNI_VERSION_9) return JNI_TRUE; 4392 if (version == JNI_VERSION_10) return JNI_TRUE; 4393 return JNI_FALSE; 4394 } 4395 4396 4397 void Threads::add(JavaThread* p, bool force_daemon) { 4398 // The threads lock must be owned at this point 4399 assert(Threads_lock->owned_by_self(), "must have threads lock"); 4400 4401 BarrierSet::barrier_set()->on_thread_attach(p); 4402 4403 p->set_next(_thread_list); 4404 _thread_list = p; 4405 4406 // Once a JavaThread is added to the Threads list, smr_delete() has 4407 // to be used to delete it. Otherwise we can just delete it directly. 4408 p->set_on_thread_list(); 4409 4410 _number_of_threads++; 4411 oop threadObj = p->threadObj(); 4412 bool daemon = true; 4413 // Bootstrapping problem: threadObj can be null for initial 4414 // JavaThread (or for threads attached via JNI) 4415 if ((!force_daemon) && !is_daemon((threadObj))) { 4416 _number_of_non_daemon_threads++; 4417 daemon = false; 4418 } 4419 4420 ThreadService::add_thread(p, daemon); 4421 4422 // Maintain fast thread list 4423 ThreadsSMRSupport::add_thread(p); 4424 4425 // Possible GC point. 4426 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4427 } 4428 4429 void Threads::remove(JavaThread* p) { 4430 4431 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4432 ObjectSynchronizer::omFlush(p); 4433 4434 // Extra scope needed for Thread_lock, so we can check 4435 // that we do not remove thread without safepoint code notice 4436 { MutexLocker ml(Threads_lock); 4437 4438 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4439 4440 // Maintain fast thread list 4441 ThreadsSMRSupport::remove_thread(p); 4442 4443 JavaThread* current = _thread_list; 4444 JavaThread* prev = NULL; 4445 4446 while (current != p) { 4447 prev = current; 4448 current = current->next(); 4449 } 4450 4451 if (prev) { 4452 prev->set_next(current->next()); 4453 } else { 4454 _thread_list = p->next(); 4455 } 4456 4457 _number_of_threads--; 4458 oop threadObj = p->threadObj(); 4459 bool daemon = true; 4460 if (!is_daemon(threadObj)) { 4461 _number_of_non_daemon_threads--; 4462 daemon = false; 4463 4464 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4465 // on destroy_vm will wake up. 4466 if (number_of_non_daemon_threads() == 1) { 4467 Threads_lock->notify_all(); 4468 } 4469 } 4470 ThreadService::remove_thread(p, daemon); 4471 4472 // Make sure that safepoint code disregard this thread. This is needed since 4473 // the thread might mess around with locks after this point. This can cause it 4474 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4475 // of this thread since it is removed from the queue. 4476 p->set_terminated_value(); 4477 } // unlock Threads_lock 4478 4479 // Since Events::log uses a lock, we grab it outside the Threads_lock 4480 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4481 } 4482 4483 // Operations on the Threads list for GC. These are not explicitly locked, 4484 // but the garbage collector must provide a safe context for them to run. 4485 // In particular, these things should never be called when the Threads_lock 4486 // is held by some other thread. (Note: the Safepoint abstraction also 4487 // uses the Threads_lock to guarantee this property. It also makes sure that 4488 // all threads gets blocked when exiting or starting). 4489 4490 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4491 ALL_JAVA_THREADS(p) { 4492 p->oops_do(f, cf); 4493 } 4494 VMThread::vm_thread()->oops_do(f, cf); 4495 } 4496 4497 void Threads::change_thread_claim_parity() { 4498 // Set the new claim parity. 4499 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4500 "Not in range."); 4501 _thread_claim_parity++; 4502 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4503 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4504 "Not in range."); 4505 } 4506 4507 #ifdef ASSERT 4508 void Threads::assert_all_threads_claimed() { 4509 ALL_JAVA_THREADS(p) { 4510 const int thread_parity = p->oops_do_parity(); 4511 assert((thread_parity == _thread_claim_parity), 4512 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4513 } 4514 VMThread* vmt = VMThread::vm_thread(); 4515 const int thread_parity = vmt->oops_do_parity(); 4516 assert((thread_parity == _thread_claim_parity), 4517 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4518 } 4519 #endif // ASSERT 4520 4521 class ParallelOopsDoThreadClosure : public ThreadClosure { 4522 private: 4523 OopClosure* _f; 4524 CodeBlobClosure* _cf; 4525 public: 4526 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4527 void do_thread(Thread* t) { 4528 t->oops_do(_f, _cf); 4529 } 4530 }; 4531 4532 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4533 ParallelOopsDoThreadClosure tc(f, cf); 4534 possibly_parallel_threads_do(is_par, &tc); 4535 } 4536 4537 void Threads::nmethods_do(CodeBlobClosure* cf) { 4538 ALL_JAVA_THREADS(p) { 4539 // This is used by the code cache sweeper to mark nmethods that are active 4540 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4541 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4542 if(!p->is_Code_cache_sweeper_thread()) { 4543 p->nmethods_do(cf); 4544 } 4545 } 4546 } 4547 4548 void Threads::metadata_do(MetadataClosure* f) { 4549 ALL_JAVA_THREADS(p) { 4550 p->metadata_do(f); 4551 } 4552 } 4553 4554 class ThreadHandlesClosure : public ThreadClosure { 4555 void (*_f)(Metadata*); 4556 public: 4557 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4558 virtual void do_thread(Thread* thread) { 4559 thread->metadata_handles_do(_f); 4560 } 4561 }; 4562 4563 void Threads::metadata_handles_do(void f(Metadata*)) { 4564 // Only walk the Handles in Thread. 4565 ThreadHandlesClosure handles_closure(f); 4566 threads_do(&handles_closure); 4567 } 4568 4569 void Threads::deoptimized_wrt_marked_nmethods() { 4570 ALL_JAVA_THREADS(p) { 4571 p->deoptimized_wrt_marked_nmethods(); 4572 } 4573 } 4574 4575 4576 // Get count Java threads that are waiting to enter the specified monitor. 4577 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4578 int count, 4579 address monitor) { 4580 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4581 4582 int i = 0; 4583 DO_JAVA_THREADS(t_list, p) { 4584 if (!p->can_call_java()) continue; 4585 4586 address pending = (address)p->current_pending_monitor(); 4587 if (pending == monitor) { // found a match 4588 if (i < count) result->append(p); // save the first count matches 4589 i++; 4590 } 4591 } 4592 4593 return result; 4594 } 4595 4596 4597 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4598 address owner) { 4599 // NULL owner means not locked so we can skip the search 4600 if (owner == NULL) return NULL; 4601 4602 DO_JAVA_THREADS(t_list, p) { 4603 // first, see if owner is the address of a Java thread 4604 if (owner == (address)p) return p; 4605 } 4606 4607 // Cannot assert on lack of success here since this function may be 4608 // used by code that is trying to report useful problem information 4609 // like deadlock detection. 4610 if (UseHeavyMonitors) return NULL; 4611 4612 // If we didn't find a matching Java thread and we didn't force use of 4613 // heavyweight monitors, then the owner is the stack address of the 4614 // Lock Word in the owning Java thread's stack. 4615 // 4616 JavaThread* the_owner = NULL; 4617 DO_JAVA_THREADS(t_list, q) { 4618 if (q->is_lock_owned(owner)) { 4619 the_owner = q; 4620 break; 4621 } 4622 } 4623 4624 // cannot assert on lack of success here; see above comment 4625 return the_owner; 4626 } 4627 4628 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4629 void Threads::print_on(outputStream* st, bool print_stacks, 4630 bool internal_format, bool print_concurrent_locks, 4631 bool print_extended_info) { 4632 char buf[32]; 4633 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4634 4635 st->print_cr("Full thread dump %s (%s %s):", 4636 VM_Version::vm_name(), 4637 VM_Version::vm_release(), 4638 VM_Version::vm_info_string()); 4639 st->cr(); 4640 4641 #if INCLUDE_SERVICES 4642 // Dump concurrent locks 4643 ConcurrentLocksDump concurrent_locks; 4644 if (print_concurrent_locks) { 4645 concurrent_locks.dump_at_safepoint(); 4646 } 4647 #endif // INCLUDE_SERVICES 4648 4649 ThreadsSMRSupport::print_info_on(st); 4650 st->cr(); 4651 4652 ALL_JAVA_THREADS(p) { 4653 ResourceMark rm; 4654 p->print_on(st, print_extended_info); 4655 if (print_stacks) { 4656 if (internal_format) { 4657 p->trace_stack(); 4658 } else { 4659 p->print_stack_on(st); 4660 } 4661 } 4662 st->cr(); 4663 #if INCLUDE_SERVICES 4664 if (print_concurrent_locks) { 4665 concurrent_locks.print_locks_on(p, st); 4666 } 4667 #endif // INCLUDE_SERVICES 4668 } 4669 4670 VMThread::vm_thread()->print_on(st); 4671 st->cr(); 4672 Universe::heap()->print_gc_threads_on(st); 4673 WatcherThread* wt = WatcherThread::watcher_thread(); 4674 if (wt != NULL) { 4675 wt->print_on(st); 4676 st->cr(); 4677 } 4678 4679 st->flush(); 4680 } 4681 4682 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4683 int buflen, bool* found_current) { 4684 if (this_thread != NULL) { 4685 bool is_current = (current == this_thread); 4686 *found_current = *found_current || is_current; 4687 st->print("%s", is_current ? "=>" : " "); 4688 4689 st->print(PTR_FORMAT, p2i(this_thread)); 4690 st->print(" "); 4691 this_thread->print_on_error(st, buf, buflen); 4692 st->cr(); 4693 } 4694 } 4695 4696 class PrintOnErrorClosure : public ThreadClosure { 4697 outputStream* _st; 4698 Thread* _current; 4699 char* _buf; 4700 int _buflen; 4701 bool* _found_current; 4702 public: 4703 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4704 int buflen, bool* found_current) : 4705 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4706 4707 virtual void do_thread(Thread* thread) { 4708 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4709 } 4710 }; 4711 4712 // Threads::print_on_error() is called by fatal error handler. It's possible 4713 // that VM is not at safepoint and/or current thread is inside signal handler. 4714 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4715 // memory (even in resource area), it might deadlock the error handler. 4716 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4717 int buflen) { 4718 ThreadsSMRSupport::print_info_on(st); 4719 st->cr(); 4720 4721 bool found_current = false; 4722 st->print_cr("Java Threads: ( => current thread )"); 4723 ALL_JAVA_THREADS(thread) { 4724 print_on_error(thread, st, current, buf, buflen, &found_current); 4725 } 4726 st->cr(); 4727 4728 st->print_cr("Other Threads:"); 4729 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4730 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4731 4732 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4733 Universe::heap()->gc_threads_do(&print_closure); 4734 4735 if (!found_current) { 4736 st->cr(); 4737 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4738 current->print_on_error(st, buf, buflen); 4739 st->cr(); 4740 } 4741 st->cr(); 4742 4743 st->print_cr("Threads with active compile tasks:"); 4744 print_threads_compiling(st, buf, buflen); 4745 } 4746 4747 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen, bool short_form) { 4748 ALL_JAVA_THREADS(thread) { 4749 if (thread->is_Compiler_thread()) { 4750 CompilerThread* ct = (CompilerThread*) thread; 4751 4752 // Keep task in local variable for NULL check. 4753 // ct->_task might be set to NULL by concurring compiler thread 4754 // because it completed the compilation. The task is never freed, 4755 // though, just returned to a free list. 4756 CompileTask* task = ct->task(); 4757 if (task != NULL) { 4758 thread->print_name_on_error(st, buf, buflen); 4759 st->print(" "); 4760 task->print(st, NULL, short_form, true); 4761 } 4762 } 4763 } 4764 } 4765 4766 4767 // Internal SpinLock and Mutex 4768 // Based on ParkEvent 4769 4770 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4771 // 4772 // We employ SpinLocks _only for low-contention, fixed-length 4773 // short-duration critical sections where we're concerned 4774 // about native mutex_t or HotSpot Mutex:: latency. 4775 // The mux construct provides a spin-then-block mutual exclusion 4776 // mechanism. 4777 // 4778 // Testing has shown that contention on the ListLock guarding gFreeList 4779 // is common. If we implement ListLock as a simple SpinLock it's common 4780 // for the JVM to devolve to yielding with little progress. This is true 4781 // despite the fact that the critical sections protected by ListLock are 4782 // extremely short. 4783 // 4784 // TODO-FIXME: ListLock should be of type SpinLock. 4785 // We should make this a 1st-class type, integrated into the lock 4786 // hierarchy as leaf-locks. Critically, the SpinLock structure 4787 // should have sufficient padding to avoid false-sharing and excessive 4788 // cache-coherency traffic. 4789 4790 4791 typedef volatile int SpinLockT; 4792 4793 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4794 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4795 return; // normal fast-path return 4796 } 4797 4798 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4799 int ctr = 0; 4800 int Yields = 0; 4801 for (;;) { 4802 while (*adr != 0) { 4803 ++ctr; 4804 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4805 if (Yields > 5) { 4806 os::naked_short_sleep(1); 4807 } else { 4808 os::naked_yield(); 4809 ++Yields; 4810 } 4811 } else { 4812 SpinPause(); 4813 } 4814 } 4815 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4816 } 4817 } 4818 4819 void Thread::SpinRelease(volatile int * adr) { 4820 assert(*adr != 0, "invariant"); 4821 OrderAccess::fence(); // guarantee at least release consistency. 4822 // Roach-motel semantics. 4823 // It's safe if subsequent LDs and STs float "up" into the critical section, 4824 // but prior LDs and STs within the critical section can't be allowed 4825 // to reorder or float past the ST that releases the lock. 4826 // Loads and stores in the critical section - which appear in program 4827 // order before the store that releases the lock - must also appear 4828 // before the store that releases the lock in memory visibility order. 4829 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4830 // the ST of 0 into the lock-word which releases the lock, so fence 4831 // more than covers this on all platforms. 4832 *adr = 0; 4833 } 4834 4835 // muxAcquire and muxRelease: 4836 // 4837 // * muxAcquire and muxRelease support a single-word lock-word construct. 4838 // The LSB of the word is set IFF the lock is held. 4839 // The remainder of the word points to the head of a singly-linked list 4840 // of threads blocked on the lock. 4841 // 4842 // * The current implementation of muxAcquire-muxRelease uses its own 4843 // dedicated Thread._MuxEvent instance. If we're interested in 4844 // minimizing the peak number of extant ParkEvent instances then 4845 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4846 // as certain invariants were satisfied. Specifically, care would need 4847 // to be taken with regards to consuming unpark() "permits". 4848 // A safe rule of thumb is that a thread would never call muxAcquire() 4849 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4850 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4851 // consume an unpark() permit intended for monitorenter, for instance. 4852 // One way around this would be to widen the restricted-range semaphore 4853 // implemented in park(). Another alternative would be to provide 4854 // multiple instances of the PlatformEvent() for each thread. One 4855 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4856 // 4857 // * Usage: 4858 // -- Only as leaf locks 4859 // -- for short-term locking only as muxAcquire does not perform 4860 // thread state transitions. 4861 // 4862 // Alternatives: 4863 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4864 // but with parking or spin-then-park instead of pure spinning. 4865 // * Use Taura-Oyama-Yonenzawa locks. 4866 // * It's possible to construct a 1-0 lock if we encode the lockword as 4867 // (List,LockByte). Acquire will CAS the full lockword while Release 4868 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4869 // acquiring threads use timers (ParkTimed) to detect and recover from 4870 // the stranding window. Thread/Node structures must be aligned on 256-byte 4871 // boundaries by using placement-new. 4872 // * Augment MCS with advisory back-link fields maintained with CAS(). 4873 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4874 // The validity of the backlinks must be ratified before we trust the value. 4875 // If the backlinks are invalid the exiting thread must back-track through the 4876 // the forward links, which are always trustworthy. 4877 // * Add a successor indication. The LockWord is currently encoded as 4878 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4879 // to provide the usual futile-wakeup optimization. 4880 // See RTStt for details. 4881 // 4882 4883 4884 const intptr_t LOCKBIT = 1; 4885 4886 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4887 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4888 if (w == 0) return; 4889 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4890 return; 4891 } 4892 4893 ParkEvent * const Self = Thread::current()->_MuxEvent; 4894 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4895 for (;;) { 4896 int its = (os::is_MP() ? 100 : 0) + 1; 4897 4898 // Optional spin phase: spin-then-park strategy 4899 while (--its >= 0) { 4900 w = *Lock; 4901 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4902 return; 4903 } 4904 } 4905 4906 Self->reset(); 4907 Self->OnList = intptr_t(Lock); 4908 // The following fence() isn't _strictly necessary as the subsequent 4909 // CAS() both serializes execution and ratifies the fetched *Lock value. 4910 OrderAccess::fence(); 4911 for (;;) { 4912 w = *Lock; 4913 if ((w & LOCKBIT) == 0) { 4914 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4915 Self->OnList = 0; // hygiene - allows stronger asserts 4916 return; 4917 } 4918 continue; // Interference -- *Lock changed -- Just retry 4919 } 4920 assert(w & LOCKBIT, "invariant"); 4921 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4922 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4923 } 4924 4925 while (Self->OnList != 0) { 4926 Self->park(); 4927 } 4928 } 4929 } 4930 4931 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4932 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4933 if (w == 0) return; 4934 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4935 return; 4936 } 4937 4938 ParkEvent * ReleaseAfter = NULL; 4939 if (ev == NULL) { 4940 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4941 } 4942 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4943 for (;;) { 4944 guarantee(ev->OnList == 0, "invariant"); 4945 int its = (os::is_MP() ? 100 : 0) + 1; 4946 4947 // Optional spin phase: spin-then-park strategy 4948 while (--its >= 0) { 4949 w = *Lock; 4950 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4951 if (ReleaseAfter != NULL) { 4952 ParkEvent::Release(ReleaseAfter); 4953 } 4954 return; 4955 } 4956 } 4957 4958 ev->reset(); 4959 ev->OnList = intptr_t(Lock); 4960 // The following fence() isn't _strictly necessary as the subsequent 4961 // CAS() both serializes execution and ratifies the fetched *Lock value. 4962 OrderAccess::fence(); 4963 for (;;) { 4964 w = *Lock; 4965 if ((w & LOCKBIT) == 0) { 4966 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4967 ev->OnList = 0; 4968 // We call ::Release while holding the outer lock, thus 4969 // artificially lengthening the critical section. 4970 // Consider deferring the ::Release() until the subsequent unlock(), 4971 // after we've dropped the outer lock. 4972 if (ReleaseAfter != NULL) { 4973 ParkEvent::Release(ReleaseAfter); 4974 } 4975 return; 4976 } 4977 continue; // Interference -- *Lock changed -- Just retry 4978 } 4979 assert(w & LOCKBIT, "invariant"); 4980 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4981 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4982 } 4983 4984 while (ev->OnList != 0) { 4985 ev->park(); 4986 } 4987 } 4988 } 4989 4990 // Release() must extract a successor from the list and then wake that thread. 4991 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4992 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4993 // Release() would : 4994 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4995 // (B) Extract a successor from the private list "in-hand" 4996 // (C) attempt to CAS() the residual back into *Lock over null. 4997 // If there were any newly arrived threads and the CAS() would fail. 4998 // In that case Release() would detach the RATs, re-merge the list in-hand 4999 // with the RATs and repeat as needed. Alternately, Release() might 5000 // detach and extract a successor, but then pass the residual list to the wakee. 5001 // The wakee would be responsible for reattaching and remerging before it 5002 // competed for the lock. 5003 // 5004 // Both "pop" and DMR are immune from ABA corruption -- there can be 5005 // multiple concurrent pushers, but only one popper or detacher. 5006 // This implementation pops from the head of the list. This is unfair, 5007 // but tends to provide excellent throughput as hot threads remain hot. 5008 // (We wake recently run threads first). 5009 // 5010 // All paths through muxRelease() will execute a CAS. 5011 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5012 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5013 // executed within the critical section are complete and globally visible before the 5014 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5015 void Thread::muxRelease(volatile intptr_t * Lock) { 5016 for (;;) { 5017 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 5018 assert(w & LOCKBIT, "invariant"); 5019 if (w == LOCKBIT) return; 5020 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5021 assert(List != NULL, "invariant"); 5022 assert(List->OnList == intptr_t(Lock), "invariant"); 5023 ParkEvent * const nxt = List->ListNext; 5024 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5025 5026 // The following CAS() releases the lock and pops the head element. 5027 // The CAS() also ratifies the previously fetched lock-word value. 5028 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 5029 continue; 5030 } 5031 List->OnList = 0; 5032 OrderAccess::fence(); 5033 List->unpark(); 5034 return; 5035 } 5036 } 5037 5038 5039 void Threads::verify() { 5040 ALL_JAVA_THREADS(p) { 5041 p->verify(); 5042 } 5043 VMThread* thread = VMThread::vm_thread(); 5044 if (thread != NULL) thread->verify(); 5045 }