1 /* 2 * Copyright (c) 1997, 2018, 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 "jfr/support/jfrThreadId.hpp" 45 #include "jvmtifiles/jvmtiEnv.hpp" 46 #include "logging/log.hpp" 47 #include "logging/logConfiguration.hpp" 48 #include "logging/logStream.hpp" 49 #include "memory/allocation.inline.hpp" 50 #include "memory/metaspaceShared.hpp" 51 #include "memory/oopFactory.hpp" 52 #include "memory/resourceArea.hpp" 53 #include "memory/universe.hpp" 54 #include "oops/access.inline.hpp" 55 #include "oops/instanceKlass.hpp" 56 #include "oops/objArrayOop.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "oops/symbol.hpp" 59 #include "oops/typeArrayOop.inline.hpp" 60 #include "oops/verifyOopClosure.hpp" 61 #include "prims/jvm_misc.hpp" 62 #include "prims/jvmtiExport.hpp" 63 #include "prims/jvmtiThreadState.hpp" 64 #include "prims/privilegedStack.hpp" 65 #include "runtime/arguments.hpp" 66 #include "runtime/atomic.hpp" 67 #include "runtime/biasedLocking.hpp" 68 #include "runtime/fieldDescriptor.inline.hpp" 69 #include "runtime/flags/jvmFlagConstraintList.hpp" 70 #include "runtime/flags/jvmFlagRangeList.hpp" 71 #include "runtime/flags/jvmFlagWriteableList.hpp" 72 #include "runtime/deoptimization.hpp" 73 #include "runtime/frame.inline.hpp" 74 #include "runtime/handshake.hpp" 75 #include "runtime/init.hpp" 76 #include "runtime/interfaceSupport.inline.hpp" 77 #include "runtime/java.hpp" 78 #include "runtime/javaCalls.hpp" 79 #include "runtime/jniHandles.inline.hpp" 80 #include "runtime/jniPeriodicChecker.hpp" 81 #include "runtime/memprofiler.hpp" 82 #include "runtime/mutexLocker.hpp" 83 #include "runtime/objectMonitor.hpp" 84 #include "runtime/orderAccess.hpp" 85 #include "runtime/osThread.hpp" 86 #include "runtime/prefetch.inline.hpp" 87 #include "runtime/safepoint.hpp" 88 #include "runtime/safepointMechanism.inline.hpp" 89 #include "runtime/safepointVerifiers.hpp" 90 #include "runtime/sharedRuntime.hpp" 91 #include "runtime/statSampler.hpp" 92 #include "runtime/stubRoutines.hpp" 93 #include "runtime/sweeper.hpp" 94 #include "runtime/task.hpp" 95 #include "runtime/thread.inline.hpp" 96 #include "runtime/threadCritical.hpp" 97 #include "runtime/threadSMR.inline.hpp" 98 #include "runtime/threadStatisticalInfo.hpp" 99 #include "runtime/timer.hpp" 100 #include "runtime/timerTrace.hpp" 101 #include "runtime/vframe.inline.hpp" 102 #include "runtime/vframeArray.hpp" 103 #include "runtime/vframe_hp.hpp" 104 #include "runtime/vmThread.hpp" 105 #include "runtime/vm_operations.hpp" 106 #include "runtime/vm_version.hpp" 107 #include "services/attachListener.hpp" 108 #include "services/management.hpp" 109 #include "services/memTracker.hpp" 110 #include "services/threadService.hpp" 111 #include "utilities/align.hpp" 112 #include "utilities/copy.hpp" 113 #include "utilities/defaultStream.hpp" 114 #include "utilities/dtrace.hpp" 115 #include "utilities/events.hpp" 116 #include "utilities/macros.hpp" 117 #include "utilities/preserveException.hpp" 118 #include "utilities/singleWriterSynchronizer.hpp" 119 #include "utilities/vmError.hpp" 120 #if INCLUDE_JVMCI 121 #include "jvmci/jvmciCompiler.hpp" 122 #include "jvmci/jvmciRuntime.hpp" 123 #include "logging/logHandle.hpp" 124 #endif 125 #ifdef COMPILER1 126 #include "c1/c1_Compiler.hpp" 127 #endif 128 #ifdef COMPILER2 129 #include "opto/c2compiler.hpp" 130 #include "opto/idealGraphPrinter.hpp" 131 #endif 132 #if INCLUDE_RTM_OPT 133 #include "runtime/rtmLocking.hpp" 134 #endif 135 #if INCLUDE_JFR 136 #include "jfr/jfr.hpp" 137 #endif 138 139 // Initialization after module runtime initialization 140 void universe_post_module_init(); // must happen after call_initPhase2 141 142 #ifdef DTRACE_ENABLED 143 144 // Only bother with this argument setup if dtrace is available 145 146 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 147 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 148 149 #define DTRACE_THREAD_PROBE(probe, javathread) \ 150 { \ 151 ResourceMark rm(this); \ 152 int len = 0; \ 153 const char* name = (javathread)->get_thread_name(); \ 154 len = strlen(name); \ 155 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 156 (char *) name, len, \ 157 java_lang_Thread::thread_id((javathread)->threadObj()), \ 158 (uintptr_t) (javathread)->osthread()->thread_id(), \ 159 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 160 } 161 162 #else // ndef DTRACE_ENABLED 163 164 #define DTRACE_THREAD_PROBE(probe, javathread) 165 166 #endif // ndef DTRACE_ENABLED 167 168 #ifndef USE_LIBRARY_BASED_TLS_ONLY 169 // Current thread is maintained as a thread-local variable 170 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 171 #endif 172 173 // ======= Thread ======== 174 // Support for forcing alignment of thread objects for biased locking 175 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 176 if (UseBiasedLocking) { 177 const int alignment = markOopDesc::biased_lock_alignment; 178 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 179 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 180 : AllocateHeap(aligned_size, flags, CURRENT_PC, 181 AllocFailStrategy::RETURN_NULL); 182 void* aligned_addr = align_up(real_malloc_addr, alignment); 183 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 184 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 185 "JavaThread alignment code overflowed allocated storage"); 186 if (aligned_addr != real_malloc_addr) { 187 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 188 p2i(real_malloc_addr), 189 p2i(aligned_addr)); 190 } 191 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 192 return aligned_addr; 193 } else { 194 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 195 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 196 } 197 } 198 199 void Thread::operator delete(void* p) { 200 if (UseBiasedLocking) { 201 FreeHeap(((Thread*) p)->_real_malloc_address); 202 } else { 203 FreeHeap(p); 204 } 205 } 206 207 void JavaThread::smr_delete() { 208 if (_on_thread_list) { 209 ThreadsSMRSupport::smr_delete(this); 210 } else { 211 delete this; 212 } 213 } 214 215 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 216 // JavaThread 217 218 219 Thread::Thread() { 220 // stack and get_thread 221 set_stack_base(NULL); 222 set_stack_size(0); 223 set_self_raw_id(0); 224 set_lgrp_id(-1); 225 DEBUG_ONLY(clear_suspendible_thread();) 226 227 // allocated data structures 228 set_osthread(NULL); 229 set_resource_area(new (mtThread)ResourceArea()); 230 DEBUG_ONLY(_current_resource_mark = NULL;) 231 set_handle_area(new (mtThread) HandleArea(NULL)); 232 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 233 set_active_handles(NULL); 234 set_free_handle_block(NULL); 235 set_last_handle_mark(NULL); 236 237 // This initial value ==> never claimed. 238 _oops_do_parity = 0; 239 _threads_hazard_ptr = NULL; 240 _threads_list_ptr = NULL; 241 _nested_threads_hazard_ptr_cnt = 0; 242 _rcu_counter = 0; 243 244 // the handle mark links itself to last_handle_mark 245 new HandleMark(this); 246 247 // plain initialization 248 debug_only(_owned_locks = NULL;) 249 debug_only(_allow_allocation_count = 0;) 250 NOT_PRODUCT(_allow_safepoint_count = 0;) 251 NOT_PRODUCT(_skip_gcalot = false;) 252 _jvmti_env_iteration_count = 0; 253 set_allocated_bytes(0); 254 _vm_operation_started_count = 0; 255 _vm_operation_completed_count = 0; 256 _current_pending_monitor = NULL; 257 _current_pending_monitor_is_from_java = true; 258 _current_waiting_monitor = NULL; 259 _num_nested_signal = 0; 260 omFreeList = NULL; 261 omFreeCount = 0; 262 omFreeProvision = 32; 263 omInUseList = NULL; 264 omInUseCount = 0; 265 266 #ifdef ASSERT 267 _visited_for_critical_count = false; 268 #endif 269 270 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 271 Monitor::_safepoint_check_sometimes); 272 _suspend_flags = 0; 273 274 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 275 _hashStateX = os::random(); 276 _hashStateY = 842502087; 277 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 278 _hashStateW = 273326509; 279 280 _OnTrap = 0; 281 _Stalled = 0; 282 _TypeTag = 0x2BAD; 283 284 // Many of the following fields are effectively final - immutable 285 // Note that nascent threads can't use the Native Monitor-Mutex 286 // construct until the _MutexEvent is initialized ... 287 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 288 // we might instead use a stack of ParkEvents that we could provision on-demand. 289 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 290 // and ::Release() 291 _ParkEvent = ParkEvent::Allocate(this); 292 _SleepEvent = ParkEvent::Allocate(this); 293 _MutexEvent = ParkEvent::Allocate(this); 294 _MuxEvent = ParkEvent::Allocate(this); 295 296 #ifdef CHECK_UNHANDLED_OOPS 297 if (CheckUnhandledOops) { 298 _unhandled_oops = new UnhandledOops(this); 299 } 300 #endif // CHECK_UNHANDLED_OOPS 301 #ifdef ASSERT 302 if (UseBiasedLocking) { 303 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 304 assert(this == _real_malloc_address || 305 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 306 "bug in forced alignment of thread objects"); 307 } 308 #endif // ASSERT 309 310 // Notify the barrier set that a thread is being created. Note that some 311 // threads are created before a barrier set is available. The call to 312 // BarrierSet::on_thread_create() for these threads is therefore deferred 313 // to BarrierSet::set_barrier_set(). 314 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 315 if (barrier_set != NULL) { 316 barrier_set->on_thread_create(this); 317 } else { 318 DEBUG_ONLY(Threads::inc_threads_before_barrier_set();) 319 } 320 } 321 322 void Thread::initialize_thread_current() { 323 #ifndef USE_LIBRARY_BASED_TLS_ONLY 324 assert(_thr_current == NULL, "Thread::current already initialized"); 325 _thr_current = this; 326 #endif 327 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 328 ThreadLocalStorage::set_thread(this); 329 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 330 } 331 332 void Thread::clear_thread_current() { 333 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 334 #ifndef USE_LIBRARY_BASED_TLS_ONLY 335 _thr_current = NULL; 336 #endif 337 ThreadLocalStorage::set_thread(NULL); 338 } 339 340 void Thread::record_stack_base_and_size() { 341 set_stack_base(os::current_stack_base()); 342 set_stack_size(os::current_stack_size()); 343 // CR 7190089: on Solaris, primordial thread's stack is adjusted 344 // in initialize_thread(). Without the adjustment, stack size is 345 // incorrect if stack is set to unlimited (ulimit -s unlimited). 346 // So far, only Solaris has real implementation of initialize_thread(). 347 // 348 // set up any platform-specific state. 349 os::initialize_thread(this); 350 351 // Set stack limits after thread is initialized. 352 if (is_Java_thread()) { 353 ((JavaThread*) this)->set_stack_overflow_limit(); 354 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 355 } 356 #if INCLUDE_NMT 357 // record thread's native stack, stack grows downward 358 MemTracker::record_thread_stack(stack_end(), stack_size()); 359 #endif // INCLUDE_NMT 360 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 361 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 362 os::current_thread_id(), p2i(stack_base() - stack_size()), 363 p2i(stack_base()), stack_size()/1024); 364 } 365 366 367 Thread::~Thread() { 368 JFR_ONLY(Jfr::on_thread_destruct(this);) 369 370 // Notify the barrier set that a thread is being destroyed. Note that a barrier 371 // set might not be available if we encountered errors during bootstrapping. 372 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 373 if (barrier_set != NULL) { 374 barrier_set->on_thread_destroy(this); 375 } 376 377 378 // stack_base can be NULL if the thread is never started or exited before 379 // record_stack_base_and_size called. Although, we would like to ensure 380 // that all started threads do call record_stack_base_and_size(), there is 381 // not proper way to enforce that. 382 #if INCLUDE_NMT 383 if (_stack_base != NULL) { 384 MemTracker::release_thread_stack(stack_end(), stack_size()); 385 #ifdef ASSERT 386 set_stack_base(NULL); 387 #endif 388 } 389 #endif // INCLUDE_NMT 390 391 // deallocate data structures 392 delete resource_area(); 393 // since the handle marks are using the handle area, we have to deallocated the root 394 // handle mark before deallocating the thread's handle area, 395 assert(last_handle_mark() != NULL, "check we have an element"); 396 delete last_handle_mark(); 397 assert(last_handle_mark() == NULL, "check we have reached the end"); 398 399 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 400 // We NULL out the fields for good hygiene. 401 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 402 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 403 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 404 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 405 406 delete handle_area(); 407 delete metadata_handles(); 408 409 // SR_handler uses this as a termination indicator - 410 // needs to happen before os::free_thread() 411 delete _SR_lock; 412 _SR_lock = NULL; 413 414 // osthread() can be NULL, if creation of thread failed. 415 if (osthread() != NULL) os::free_thread(osthread()); 416 417 // clear Thread::current if thread is deleting itself. 418 // Needed to ensure JNI correctly detects non-attached threads. 419 if (this == Thread::current()) { 420 clear_thread_current(); 421 } 422 423 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 424 } 425 426 // NOTE: dummy function for assertion purpose. 427 void Thread::run() { 428 ShouldNotReachHere(); 429 } 430 431 #ifdef ASSERT 432 // A JavaThread is considered "dangling" if it is not the current 433 // thread, has been added the Threads list, the system is not at a 434 // safepoint and the Thread is not "protected". 435 // 436 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 437 assert(!thread->is_Java_thread() || Thread::current() == thread || 438 !((JavaThread *) thread)->on_thread_list() || 439 SafepointSynchronize::is_at_safepoint() || 440 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 441 "possibility of dangling Thread pointer"); 442 } 443 #endif 444 445 ThreadPriority Thread::get_priority(const Thread* const thread) { 446 ThreadPriority priority; 447 // Can return an error! 448 (void)os::get_priority(thread, priority); 449 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 450 return priority; 451 } 452 453 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 454 debug_only(check_for_dangling_thread_pointer(thread);) 455 // Can return an error! 456 (void)os::set_priority(thread, priority); 457 } 458 459 460 void Thread::start(Thread* thread) { 461 // Start is different from resume in that its safety is guaranteed by context or 462 // being called from a Java method synchronized on the Thread object. 463 if (!DisableStartThread) { 464 if (thread->is_Java_thread()) { 465 // Initialize the thread state to RUNNABLE before starting this thread. 466 // Can not set it after the thread started because we do not know the 467 // exact thread state at that time. It could be in MONITOR_WAIT or 468 // in SLEEPING or some other state. 469 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 470 java_lang_Thread::RUNNABLE); 471 } 472 os::start_thread(thread); 473 } 474 } 475 476 // Enqueue a VM_Operation to do the job for us - sometime later 477 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 478 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 479 VMThread::execute(vm_stop); 480 } 481 482 483 // Check if an external suspend request has completed (or has been 484 // cancelled). Returns true if the thread is externally suspended and 485 // false otherwise. 486 // 487 // The bits parameter returns information about the code path through 488 // the routine. Useful for debugging: 489 // 490 // set in is_ext_suspend_completed(): 491 // 0x00000001 - routine was entered 492 // 0x00000010 - routine return false at end 493 // 0x00000100 - thread exited (return false) 494 // 0x00000200 - suspend request cancelled (return false) 495 // 0x00000400 - thread suspended (return true) 496 // 0x00001000 - thread is in a suspend equivalent state (return true) 497 // 0x00002000 - thread is native and walkable (return true) 498 // 0x00004000 - thread is native_trans and walkable (needed retry) 499 // 500 // set in wait_for_ext_suspend_completion(): 501 // 0x00010000 - routine was entered 502 // 0x00020000 - suspend request cancelled before loop (return false) 503 // 0x00040000 - thread suspended before loop (return true) 504 // 0x00080000 - suspend request cancelled in loop (return false) 505 // 0x00100000 - thread suspended in loop (return true) 506 // 0x00200000 - suspend not completed during retry loop (return false) 507 508 // Helper class for tracing suspend wait debug bits. 509 // 510 // 0x00000100 indicates that the target thread exited before it could 511 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 512 // 0x00080000 each indicate a cancelled suspend request so they don't 513 // count as wait failures either. 514 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 515 516 class TraceSuspendDebugBits : public StackObj { 517 private: 518 JavaThread * jt; 519 bool is_wait; 520 bool called_by_wait; // meaningful when !is_wait 521 uint32_t * bits; 522 523 public: 524 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 525 uint32_t *_bits) { 526 jt = _jt; 527 is_wait = _is_wait; 528 called_by_wait = _called_by_wait; 529 bits = _bits; 530 } 531 532 ~TraceSuspendDebugBits() { 533 if (!is_wait) { 534 #if 1 535 // By default, don't trace bits for is_ext_suspend_completed() calls. 536 // That trace is very chatty. 537 return; 538 #else 539 if (!called_by_wait) { 540 // If tracing for is_ext_suspend_completed() is enabled, then only 541 // trace calls to it from wait_for_ext_suspend_completion() 542 return; 543 } 544 #endif 545 } 546 547 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 548 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 549 MutexLocker ml(Threads_lock); // needed for get_thread_name() 550 ResourceMark rm; 551 552 tty->print_cr( 553 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 554 jt->get_thread_name(), *bits); 555 556 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 557 } 558 } 559 } 560 }; 561 #undef DEBUG_FALSE_BITS 562 563 564 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 565 uint32_t *bits) { 566 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 567 568 bool did_trans_retry = false; // only do thread_in_native_trans retry once 569 bool do_trans_retry; // flag to force the retry 570 571 *bits |= 0x00000001; 572 573 do { 574 do_trans_retry = false; 575 576 if (is_exiting()) { 577 // Thread is in the process of exiting. This is always checked 578 // first to reduce the risk of dereferencing a freed JavaThread. 579 *bits |= 0x00000100; 580 return false; 581 } 582 583 if (!is_external_suspend()) { 584 // Suspend request is cancelled. This is always checked before 585 // is_ext_suspended() to reduce the risk of a rogue resume 586 // confusing the thread that made the suspend request. 587 *bits |= 0x00000200; 588 return false; 589 } 590 591 if (is_ext_suspended()) { 592 // thread is suspended 593 *bits |= 0x00000400; 594 return true; 595 } 596 597 // Now that we no longer do hard suspends of threads running 598 // native code, the target thread can be changing thread state 599 // while we are in this routine: 600 // 601 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 602 // 603 // We save a copy of the thread state as observed at this moment 604 // and make our decision about suspend completeness based on the 605 // copy. This closes the race where the thread state is seen as 606 // _thread_in_native_trans in the if-thread_blocked check, but is 607 // seen as _thread_blocked in if-thread_in_native_trans check. 608 JavaThreadState save_state = thread_state(); 609 610 if (save_state == _thread_blocked && is_suspend_equivalent()) { 611 // If the thread's state is _thread_blocked and this blocking 612 // condition is known to be equivalent to a suspend, then we can 613 // consider the thread to be externally suspended. This means that 614 // the code that sets _thread_blocked has been modified to do 615 // self-suspension if the blocking condition releases. We also 616 // used to check for CONDVAR_WAIT here, but that is now covered by 617 // the _thread_blocked with self-suspension check. 618 // 619 // Return true since we wouldn't be here unless there was still an 620 // external suspend request. 621 *bits |= 0x00001000; 622 return true; 623 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 624 // Threads running native code will self-suspend on native==>VM/Java 625 // transitions. If its stack is walkable (should always be the case 626 // unless this function is called before the actual java_suspend() 627 // call), then the wait is done. 628 *bits |= 0x00002000; 629 return true; 630 } else if (!called_by_wait && !did_trans_retry && 631 save_state == _thread_in_native_trans && 632 frame_anchor()->walkable()) { 633 // The thread is transitioning from thread_in_native to another 634 // thread state. check_safepoint_and_suspend_for_native_trans() 635 // will force the thread to self-suspend. If it hasn't gotten 636 // there yet we may have caught the thread in-between the native 637 // code check above and the self-suspend. Lucky us. If we were 638 // called by wait_for_ext_suspend_completion(), then it 639 // will be doing the retries so we don't have to. 640 // 641 // Since we use the saved thread state in the if-statement above, 642 // there is a chance that the thread has already transitioned to 643 // _thread_blocked by the time we get here. In that case, we will 644 // make a single unnecessary pass through the logic below. This 645 // doesn't hurt anything since we still do the trans retry. 646 647 *bits |= 0x00004000; 648 649 // Once the thread leaves thread_in_native_trans for another 650 // thread state, we break out of this retry loop. We shouldn't 651 // need this flag to prevent us from getting back here, but 652 // sometimes paranoia is good. 653 did_trans_retry = true; 654 655 // We wait for the thread to transition to a more usable state. 656 for (int i = 1; i <= SuspendRetryCount; i++) { 657 // We used to do an "os::yield_all(i)" call here with the intention 658 // that yielding would increase on each retry. However, the parameter 659 // is ignored on Linux which means the yield didn't scale up. Waiting 660 // on the SR_lock below provides a much more predictable scale up for 661 // the delay. It also provides a simple/direct point to check for any 662 // safepoint requests from the VMThread 663 664 // temporarily drops SR_lock while doing wait with safepoint check 665 // (if we're a JavaThread - the WatcherThread can also call this) 666 // and increase delay with each retry 667 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 668 669 // check the actual thread state instead of what we saved above 670 if (thread_state() != _thread_in_native_trans) { 671 // the thread has transitioned to another thread state so 672 // try all the checks (except this one) one more time. 673 do_trans_retry = true; 674 break; 675 } 676 } // end retry loop 677 678 679 } 680 } while (do_trans_retry); 681 682 *bits |= 0x00000010; 683 return false; 684 } 685 686 // Wait for an external suspend request to complete (or be cancelled). 687 // Returns true if the thread is externally suspended and false otherwise. 688 // 689 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 690 uint32_t *bits) { 691 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 692 false /* !called_by_wait */, bits); 693 694 // local flag copies to minimize SR_lock hold time 695 bool is_suspended; 696 bool pending; 697 uint32_t reset_bits; 698 699 // set a marker so is_ext_suspend_completed() knows we are the caller 700 *bits |= 0x00010000; 701 702 // We use reset_bits to reinitialize the bits value at the top of 703 // each retry loop. This allows the caller to make use of any 704 // unused bits for their own marking purposes. 705 reset_bits = *bits; 706 707 { 708 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 709 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 710 delay, bits); 711 pending = is_external_suspend(); 712 } 713 // must release SR_lock to allow suspension to complete 714 715 if (!pending) { 716 // A cancelled suspend request is the only false return from 717 // is_ext_suspend_completed() that keeps us from entering the 718 // retry loop. 719 *bits |= 0x00020000; 720 return false; 721 } 722 723 if (is_suspended) { 724 *bits |= 0x00040000; 725 return true; 726 } 727 728 for (int i = 1; i <= retries; i++) { 729 *bits = reset_bits; // reinit to only track last retry 730 731 // We used to do an "os::yield_all(i)" call here with the intention 732 // that yielding would increase on each retry. However, the parameter 733 // is ignored on Linux which means the yield didn't scale up. Waiting 734 // on the SR_lock below provides a much more predictable scale up for 735 // the delay. It also provides a simple/direct point to check for any 736 // safepoint requests from the VMThread 737 738 { 739 MutexLocker ml(SR_lock()); 740 // wait with safepoint check (if we're a JavaThread - the WatcherThread 741 // can also call this) and increase delay with each retry 742 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 743 744 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 745 delay, bits); 746 747 // It is possible for the external suspend request to be cancelled 748 // (by a resume) before the actual suspend operation is completed. 749 // Refresh our local copy to see if we still need to wait. 750 pending = is_external_suspend(); 751 } 752 753 if (!pending) { 754 // A cancelled suspend request is the only false return from 755 // is_ext_suspend_completed() that keeps us from staying in the 756 // retry loop. 757 *bits |= 0x00080000; 758 return false; 759 } 760 761 if (is_suspended) { 762 *bits |= 0x00100000; 763 return true; 764 } 765 } // end retry loop 766 767 // thread did not suspend after all our retries 768 *bits |= 0x00200000; 769 return false; 770 } 771 772 // Called from API entry points which perform stack walking. If the 773 // associated JavaThread is the current thread, then wait_for_suspend 774 // is not used. Otherwise, it determines if we should wait for the 775 // "other" thread to complete external suspension. (NOTE: in future 776 // releases the suspension mechanism should be reimplemented so this 777 // is not necessary.) 778 // 779 bool 780 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 781 if (this != JavaThread::current()) { 782 // "other" threads require special handling. 783 if (wait_for_suspend) { 784 // We are allowed to wait for the external suspend to complete 785 // so give the other thread a chance to get suspended. 786 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 787 SuspendRetryDelay, bits)) { 788 // Didn't make it so let the caller know. 789 return false; 790 } 791 } 792 // We aren't allowed to wait for the external suspend to complete 793 // so if the other thread isn't externally suspended we need to 794 // let the caller know. 795 else if (!is_ext_suspend_completed_with_lock(bits)) { 796 return false; 797 } 798 } 799 800 return true; 801 } 802 803 #ifndef PRODUCT 804 void JavaThread::record_jump(address target, address instr, const char* file, 805 int line) { 806 807 // This should not need to be atomic as the only way for simultaneous 808 // updates is via interrupts. Even then this should be rare or non-existent 809 // and we don't care that much anyway. 810 811 int index = _jmp_ring_index; 812 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 813 _jmp_ring[index]._target = (intptr_t) target; 814 _jmp_ring[index]._instruction = (intptr_t) instr; 815 _jmp_ring[index]._file = file; 816 _jmp_ring[index]._line = line; 817 } 818 #endif // PRODUCT 819 820 void Thread::interrupt(Thread* thread) { 821 debug_only(check_for_dangling_thread_pointer(thread);) 822 os::interrupt(thread); 823 } 824 825 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 826 debug_only(check_for_dangling_thread_pointer(thread);) 827 // Note: If clear_interrupted==false, this simply fetches and 828 // returns the value of the field osthread()->interrupted(). 829 return os::is_interrupted(thread, clear_interrupted); 830 } 831 832 833 // GC Support 834 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 835 int thread_parity = _oops_do_parity; 836 if (thread_parity != strong_roots_parity) { 837 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 838 if (res == thread_parity) { 839 return true; 840 } else { 841 guarantee(res == strong_roots_parity, "Or else what?"); 842 return false; 843 } 844 } 845 return false; 846 } 847 848 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 849 active_handles()->oops_do(f); 850 // Do oop for ThreadShadow 851 f->do_oop((oop*)&_pending_exception); 852 handle_area()->oops_do(f); 853 854 // We scan thread local monitor lists here, and the remaining global 855 // monitors in ObjectSynchronizer::oops_do(). 856 ObjectSynchronizer::thread_local_used_oops_do(this, f); 857 } 858 859 void Thread::metadata_handles_do(void f(Metadata*)) { 860 // Only walk the Handles in Thread. 861 if (metadata_handles() != NULL) { 862 for (int i = 0; i< metadata_handles()->length(); i++) { 863 f(metadata_handles()->at(i)); 864 } 865 } 866 } 867 868 void Thread::print_on(outputStream* st, bool print_extended_info) const { 869 // get_priority assumes osthread initialized 870 if (osthread() != NULL) { 871 int os_prio; 872 if (os::get_native_priority(this, &os_prio) == OS_OK) { 873 st->print("os_prio=%d ", os_prio); 874 } 875 876 st->print("cpu=%.2fms ", 877 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 878 ); 879 st->print("elapsed=%.2fs ", 880 _statistical_info.getElapsedTime() / 1000.0 881 ); 882 if (is_Java_thread() && (PrintExtendedThreadInfo || print_extended_info)) { 883 size_t allocated_bytes = (size_t) const_cast<Thread*>(this)->cooked_allocated_bytes(); 884 st->print("allocated=" SIZE_FORMAT "%s ", 885 byte_size_in_proper_unit(allocated_bytes), 886 proper_unit_for_byte_size(allocated_bytes) 887 ); 888 st->print("defined_classes=" INT64_FORMAT " ", _statistical_info.getDefineClassCount()); 889 } 890 891 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 892 osthread()->print_on(st); 893 } 894 ThreadsSMRSupport::print_info_on(this, st); 895 st->print(" "); 896 debug_only(if (WizardMode) print_owned_locks_on(st);) 897 } 898 899 // Thread::print_on_error() is called by fatal error handler. Don't use 900 // any lock or allocate memory. 901 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 902 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 903 904 if (is_VM_thread()) { st->print("VMThread"); } 905 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 906 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 907 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 908 else { st->print("Thread"); } 909 910 if (is_Named_thread()) { 911 st->print(" \"%s\"", name()); 912 } 913 914 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 915 p2i(stack_end()), p2i(stack_base())); 916 917 if (osthread()) { 918 st->print(" [id=%d]", osthread()->thread_id()); 919 } 920 921 ThreadsSMRSupport::print_info_on(this, st); 922 } 923 924 void Thread::print_value_on(outputStream* st) const { 925 if (is_Named_thread()) { 926 st->print(" \"%s\" ", name()); 927 } 928 st->print(INTPTR_FORMAT, p2i(this)); // print address 929 } 930 931 #ifdef ASSERT 932 void Thread::print_owned_locks_on(outputStream* st) const { 933 Monitor *cur = _owned_locks; 934 if (cur == NULL) { 935 st->print(" (no locks) "); 936 } else { 937 st->print_cr(" Locks owned:"); 938 while (cur) { 939 cur->print_on(st); 940 cur = cur->next(); 941 } 942 } 943 } 944 945 static int ref_use_count = 0; 946 947 bool Thread::owns_locks_but_compiled_lock() const { 948 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 949 if (cur != Compile_lock) return true; 950 } 951 return false; 952 } 953 954 955 #endif 956 957 #ifndef PRODUCT 958 959 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 960 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 961 // no locks which allow_vm_block's are held 962 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 963 // Check if current thread is allowed to block at a safepoint 964 if (!(_allow_safepoint_count == 0)) { 965 fatal("Possible safepoint reached by thread that does not allow it"); 966 } 967 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 968 fatal("LEAF method calling lock?"); 969 } 970 971 #ifdef ASSERT 972 if (potential_vm_operation && is_Java_thread() 973 && !Universe::is_bootstrapping()) { 974 // Make sure we do not hold any locks that the VM thread also uses. 975 // This could potentially lead to deadlocks 976 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 977 // Threads_lock is special, since the safepoint synchronization will not start before this is 978 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 979 // since it is used to transfer control between JavaThreads and the VMThread 980 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 981 if ((cur->allow_vm_block() && 982 cur != Threads_lock && 983 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 984 cur != VMOperationRequest_lock && 985 cur != VMOperationQueue_lock) || 986 cur->rank() == Mutex::special) { 987 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 988 } 989 } 990 } 991 992 if (GCALotAtAllSafepoints) { 993 // We could enter a safepoint here and thus have a gc 994 InterfaceSupport::check_gc_alot(); 995 } 996 #endif 997 } 998 #endif 999 1000 bool Thread::is_in_stack(address adr) const { 1001 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1002 address end = os::current_stack_pointer(); 1003 // Allow non Java threads to call this without stack_base 1004 if (_stack_base == NULL) return true; 1005 if (stack_base() >= adr && adr >= end) return true; 1006 1007 return false; 1008 } 1009 1010 bool Thread::is_in_usable_stack(address adr) const { 1011 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1012 size_t usable_stack_size = _stack_size - stack_guard_size; 1013 1014 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1015 } 1016 1017 1018 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1019 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1020 // used for compilation in the future. If that change is made, the need for these methods 1021 // should be revisited, and they should be removed if possible. 1022 1023 bool Thread::is_lock_owned(address adr) const { 1024 return on_local_stack(adr); 1025 } 1026 1027 bool Thread::set_as_starting_thread() { 1028 // NOTE: this must be called inside the main thread. 1029 return os::create_main_thread((JavaThread*)this); 1030 } 1031 1032 static void initialize_class(Symbol* class_name, TRAPS) { 1033 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1034 InstanceKlass::cast(klass)->initialize(CHECK); 1035 } 1036 1037 1038 // Creates the initial ThreadGroup 1039 static Handle create_initial_thread_group(TRAPS) { 1040 Handle system_instance = JavaCalls::construct_new_instance( 1041 SystemDictionary::ThreadGroup_klass(), 1042 vmSymbols::void_method_signature(), 1043 CHECK_NH); 1044 Universe::set_system_thread_group(system_instance()); 1045 1046 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1047 Handle main_instance = JavaCalls::construct_new_instance( 1048 SystemDictionary::ThreadGroup_klass(), 1049 vmSymbols::threadgroup_string_void_signature(), 1050 system_instance, 1051 string, 1052 CHECK_NH); 1053 return main_instance; 1054 } 1055 1056 // Creates the initial Thread 1057 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1058 TRAPS) { 1059 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1060 assert(ik->is_initialized(), "must be"); 1061 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1062 1063 // Cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1064 // constructor calls Thread.current(), which must be set here for the 1065 // initial thread. 1066 java_lang_Thread::set_thread(thread_oop(), thread); 1067 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1068 thread->set_threadObj(thread_oop()); 1069 1070 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1071 1072 JavaValue result(T_VOID); 1073 JavaCalls::call_special(&result, thread_oop, 1074 ik, 1075 vmSymbols::object_initializer_name(), 1076 vmSymbols::threadgroup_string_void_signature(), 1077 thread_group, 1078 string, 1079 CHECK_NULL); 1080 return thread_oop(); 1081 } 1082 1083 char java_runtime_name[128] = ""; 1084 char java_runtime_version[128] = ""; 1085 1086 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1087 static const char* get_java_runtime_name(TRAPS) { 1088 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1089 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1090 fieldDescriptor fd; 1091 bool found = k != NULL && 1092 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1093 vmSymbols::string_signature(), &fd); 1094 if (found) { 1095 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1096 if (name_oop == NULL) { 1097 return NULL; 1098 } 1099 const char* name = java_lang_String::as_utf8_string(name_oop, 1100 java_runtime_name, 1101 sizeof(java_runtime_name)); 1102 return name; 1103 } else { 1104 return NULL; 1105 } 1106 } 1107 1108 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1109 static const char* get_java_runtime_version(TRAPS) { 1110 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1111 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1112 fieldDescriptor fd; 1113 bool found = k != NULL && 1114 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1115 vmSymbols::string_signature(), &fd); 1116 if (found) { 1117 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1118 if (name_oop == NULL) { 1119 return NULL; 1120 } 1121 const char* name = java_lang_String::as_utf8_string(name_oop, 1122 java_runtime_version, 1123 sizeof(java_runtime_version)); 1124 return name; 1125 } else { 1126 return NULL; 1127 } 1128 } 1129 1130 // General purpose hook into Java code, run once when the VM is initialized. 1131 // The Java library method itself may be changed independently from the VM. 1132 static void call_postVMInitHook(TRAPS) { 1133 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1134 if (klass != NULL) { 1135 JavaValue result(T_VOID); 1136 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1137 vmSymbols::void_method_signature(), 1138 CHECK); 1139 } 1140 } 1141 1142 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1143 bool daemon, TRAPS) { 1144 assert(thread_group.not_null(), "thread group should be specified"); 1145 assert(threadObj() == NULL, "should only create Java thread object once"); 1146 1147 InstanceKlass* ik = SystemDictionary::Thread_klass(); 1148 assert(ik->is_initialized(), "must be"); 1149 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1150 1151 // We are called from jni_AttachCurrentThread/jni_AttachCurrentThreadAsDaemon. 1152 // We cannot use JavaCalls::construct_new_instance because the java.lang.Thread 1153 // constructor calls Thread.current(), which must be set here. 1154 java_lang_Thread::set_thread(thread_oop(), this); 1155 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1156 set_threadObj(thread_oop()); 1157 1158 JavaValue result(T_VOID); 1159 if (thread_name != NULL) { 1160 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1161 // Thread gets assigned specified name and null target 1162 JavaCalls::call_special(&result, 1163 thread_oop, 1164 ik, 1165 vmSymbols::object_initializer_name(), 1166 vmSymbols::threadgroup_string_void_signature(), 1167 thread_group, 1168 name, 1169 THREAD); 1170 } else { 1171 // Thread gets assigned name "Thread-nnn" and null target 1172 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1173 JavaCalls::call_special(&result, 1174 thread_oop, 1175 ik, 1176 vmSymbols::object_initializer_name(), 1177 vmSymbols::threadgroup_runnable_void_signature(), 1178 thread_group, 1179 Handle(), 1180 THREAD); 1181 } 1182 1183 1184 if (daemon) { 1185 java_lang_Thread::set_daemon(thread_oop()); 1186 } 1187 1188 if (HAS_PENDING_EXCEPTION) { 1189 return; 1190 } 1191 1192 Klass* group = SystemDictionary::ThreadGroup_klass(); 1193 Handle threadObj(THREAD, this->threadObj()); 1194 1195 JavaCalls::call_special(&result, 1196 thread_group, 1197 group, 1198 vmSymbols::add_method_name(), 1199 vmSymbols::thread_void_signature(), 1200 threadObj, // Arg 1 1201 THREAD); 1202 } 1203 1204 // List of all NonJavaThreads and safe iteration over that list. 1205 1206 class NonJavaThread::List { 1207 public: 1208 NonJavaThread* volatile _head; 1209 SingleWriterSynchronizer _protect; 1210 1211 List() : _head(NULL), _protect() {} 1212 }; 1213 1214 NonJavaThread::List NonJavaThread::_the_list; 1215 1216 NonJavaThread::Iterator::Iterator() : 1217 _protect_enter(_the_list._protect.enter()), 1218 _current(OrderAccess::load_acquire(&_the_list._head)) 1219 {} 1220 1221 NonJavaThread::Iterator::~Iterator() { 1222 _the_list._protect.exit(_protect_enter); 1223 } 1224 1225 void NonJavaThread::Iterator::step() { 1226 assert(!end(), "precondition"); 1227 _current = OrderAccess::load_acquire(&_current->_next); 1228 } 1229 1230 NonJavaThread::NonJavaThread() : Thread(), _next(NULL) { 1231 // Add this thread to _the_list. 1232 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1233 _next = _the_list._head; 1234 OrderAccess::release_store(&_the_list._head, this); 1235 } 1236 1237 NonJavaThread::~NonJavaThread() { 1238 // Remove this thread from _the_list. 1239 MutexLockerEx lock(NonJavaThreadsList_lock, Mutex::_no_safepoint_check_flag); 1240 NonJavaThread* volatile* p = &_the_list._head; 1241 for (NonJavaThread* t = *p; t != NULL; p = &t->_next, t = *p) { 1242 if (t == this) { 1243 *p = this->_next; 1244 // Wait for any in-progress iterators. 1245 _the_list._protect.synchronize(); 1246 break; 1247 } 1248 } 1249 } 1250 1251 // NamedThread -- non-JavaThread subclasses with multiple 1252 // uniquely named instances should derive from this. 1253 NamedThread::NamedThread() : 1254 NonJavaThread(), 1255 _name(NULL), 1256 _processed_thread(NULL), 1257 _gc_id(GCId::undefined()) 1258 {} 1259 1260 NamedThread::~NamedThread() { 1261 if (_name != NULL) { 1262 FREE_C_HEAP_ARRAY(char, _name); 1263 _name = NULL; 1264 } 1265 } 1266 1267 void NamedThread::set_name(const char* format, ...) { 1268 guarantee(_name == NULL, "Only get to set name once."); 1269 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1270 guarantee(_name != NULL, "alloc failure"); 1271 va_list ap; 1272 va_start(ap, format); 1273 jio_vsnprintf(_name, max_name_len, format, ap); 1274 va_end(ap); 1275 } 1276 1277 void NamedThread::initialize_named_thread() { 1278 set_native_thread_name(name()); 1279 } 1280 1281 void NamedThread::print_on(outputStream* st) const { 1282 st->print("\"%s\" ", name()); 1283 Thread::print_on(st); 1284 st->cr(); 1285 } 1286 1287 1288 // ======= WatcherThread ======== 1289 1290 // The watcher thread exists to simulate timer interrupts. It should 1291 // be replaced by an abstraction over whatever native support for 1292 // timer interrupts exists on the platform. 1293 1294 WatcherThread* WatcherThread::_watcher_thread = NULL; 1295 bool WatcherThread::_startable = false; 1296 volatile bool WatcherThread::_should_terminate = false; 1297 1298 WatcherThread::WatcherThread() : NonJavaThread() { 1299 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1300 if (os::create_thread(this, os::watcher_thread)) { 1301 _watcher_thread = this; 1302 1303 // Set the watcher thread to the highest OS priority which should not be 1304 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1305 // is created. The only normal thread using this priority is the reference 1306 // handler thread, which runs for very short intervals only. 1307 // If the VMThread's priority is not lower than the WatcherThread profiling 1308 // will be inaccurate. 1309 os::set_priority(this, MaxPriority); 1310 if (!DisableStartThread) { 1311 os::start_thread(this); 1312 } 1313 } 1314 } 1315 1316 int WatcherThread::sleep() const { 1317 // The WatcherThread does not participate in the safepoint protocol 1318 // for the PeriodicTask_lock because it is not a JavaThread. 1319 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1320 1321 if (_should_terminate) { 1322 // check for termination before we do any housekeeping or wait 1323 return 0; // we did not sleep. 1324 } 1325 1326 // remaining will be zero if there are no tasks, 1327 // causing the WatcherThread to sleep until a task is 1328 // enrolled 1329 int remaining = PeriodicTask::time_to_wait(); 1330 int time_slept = 0; 1331 1332 // we expect this to timeout - we only ever get unparked when 1333 // we should terminate or when a new task has been enrolled 1334 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1335 1336 jlong time_before_loop = os::javaTimeNanos(); 1337 1338 while (true) { 1339 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1340 remaining); 1341 jlong now = os::javaTimeNanos(); 1342 1343 if (remaining == 0) { 1344 // if we didn't have any tasks we could have waited for a long time 1345 // consider the time_slept zero and reset time_before_loop 1346 time_slept = 0; 1347 time_before_loop = now; 1348 } else { 1349 // need to recalculate since we might have new tasks in _tasks 1350 time_slept = (int) ((now - time_before_loop) / 1000000); 1351 } 1352 1353 // Change to task list or spurious wakeup of some kind 1354 if (timedout || _should_terminate) { 1355 break; 1356 } 1357 1358 remaining = PeriodicTask::time_to_wait(); 1359 if (remaining == 0) { 1360 // Last task was just disenrolled so loop around and wait until 1361 // another task gets enrolled 1362 continue; 1363 } 1364 1365 remaining -= time_slept; 1366 if (remaining <= 0) { 1367 break; 1368 } 1369 } 1370 1371 return time_slept; 1372 } 1373 1374 void WatcherThread::run() { 1375 assert(this == watcher_thread(), "just checking"); 1376 1377 this->record_stack_base_and_size(); 1378 this->set_native_thread_name(this->name()); 1379 this->set_active_handles(JNIHandleBlock::allocate_block()); 1380 while (true) { 1381 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1382 assert(watcher_thread() == this, "thread consistency check"); 1383 1384 // Calculate how long it'll be until the next PeriodicTask work 1385 // should be done, and sleep that amount of time. 1386 int time_waited = sleep(); 1387 1388 if (VMError::is_error_reported()) { 1389 // A fatal error has happened, the error handler(VMError::report_and_die) 1390 // should abort JVM after creating an error log file. However in some 1391 // rare cases, the error handler itself might deadlock. Here periodically 1392 // check for error reporting timeouts, and if it happens, just proceed to 1393 // abort the VM. 1394 1395 // This code is in WatcherThread because WatcherThread wakes up 1396 // periodically so the fatal error handler doesn't need to do anything; 1397 // also because the WatcherThread is less likely to crash than other 1398 // threads. 1399 1400 for (;;) { 1401 // Note: we use naked sleep in this loop because we want to avoid using 1402 // any kind of VM infrastructure which may be broken at this point. 1403 if (VMError::check_timeout()) { 1404 // We hit error reporting timeout. Error reporting was interrupted and 1405 // will be wrapping things up now (closing files etc). Give it some more 1406 // time, then quit the VM. 1407 os::naked_short_sleep(200); 1408 // Print a message to stderr. 1409 fdStream err(defaultStream::output_fd()); 1410 err.print_raw_cr("# [ timer expired, abort... ]"); 1411 // skip atexit/vm_exit/vm_abort hooks 1412 os::die(); 1413 } 1414 1415 // Wait a second, then recheck for timeout. 1416 os::naked_short_sleep(999); 1417 } 1418 } 1419 1420 if (_should_terminate) { 1421 // check for termination before posting the next tick 1422 break; 1423 } 1424 1425 PeriodicTask::real_time_tick(time_waited); 1426 } 1427 1428 // Signal that it is terminated 1429 { 1430 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1431 _watcher_thread = NULL; 1432 Terminator_lock->notify(); 1433 } 1434 } 1435 1436 void WatcherThread::start() { 1437 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1438 1439 if (watcher_thread() == NULL && _startable) { 1440 _should_terminate = false; 1441 // Create the single instance of WatcherThread 1442 new WatcherThread(); 1443 } 1444 } 1445 1446 void WatcherThread::make_startable() { 1447 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1448 _startable = true; 1449 } 1450 1451 void WatcherThread::stop() { 1452 { 1453 // Follow normal safepoint aware lock enter protocol since the 1454 // WatcherThread is stopped by another JavaThread. 1455 MutexLocker ml(PeriodicTask_lock); 1456 _should_terminate = true; 1457 1458 WatcherThread* watcher = watcher_thread(); 1459 if (watcher != NULL) { 1460 // unpark the WatcherThread so it can see that it should terminate 1461 watcher->unpark(); 1462 } 1463 } 1464 1465 MutexLocker mu(Terminator_lock); 1466 1467 while (watcher_thread() != NULL) { 1468 // This wait should make safepoint checks, wait without a timeout, 1469 // and wait as a suspend-equivalent condition. 1470 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1471 Mutex::_as_suspend_equivalent_flag); 1472 } 1473 } 1474 1475 void WatcherThread::unpark() { 1476 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1477 PeriodicTask_lock->notify(); 1478 } 1479 1480 void WatcherThread::print_on(outputStream* st) const { 1481 st->print("\"%s\" ", name()); 1482 Thread::print_on(st); 1483 st->cr(); 1484 } 1485 1486 // ======= JavaThread ======== 1487 1488 #if INCLUDE_JVMCI 1489 1490 jlong* JavaThread::_jvmci_old_thread_counters; 1491 1492 bool jvmci_counters_include(JavaThread* thread) { 1493 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1494 } 1495 1496 void JavaThread::collect_counters(typeArrayOop array) { 1497 if (JVMCICounterSize > 0) { 1498 JavaThreadIteratorWithHandle jtiwh; 1499 for (int i = 0; i < array->length(); i++) { 1500 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1501 } 1502 for (; JavaThread *tp = jtiwh.next(); ) { 1503 if (jvmci_counters_include(tp)) { 1504 for (int i = 0; i < array->length(); i++) { 1505 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1506 } 1507 } 1508 } 1509 } 1510 } 1511 1512 #endif // INCLUDE_JVMCI 1513 1514 // A JavaThread is a normal Java thread 1515 1516 void JavaThread::initialize() { 1517 // Initialize fields 1518 1519 set_saved_exception_pc(NULL); 1520 set_threadObj(NULL); 1521 _anchor.clear(); 1522 set_entry_point(NULL); 1523 set_jni_functions(jni_functions()); 1524 set_callee_target(NULL); 1525 set_vm_result(NULL); 1526 set_vm_result_2(NULL); 1527 set_vframe_array_head(NULL); 1528 set_vframe_array_last(NULL); 1529 set_deferred_locals(NULL); 1530 set_deopt_mark(NULL); 1531 set_deopt_compiled_method(NULL); 1532 clear_must_deopt_id(); 1533 set_monitor_chunks(NULL); 1534 set_next(NULL); 1535 _on_thread_list = false; 1536 set_thread_state(_thread_new); 1537 _terminated = _not_terminated; 1538 _privileged_stack_top = NULL; 1539 _array_for_gc = NULL; 1540 _suspend_equivalent = false; 1541 _in_deopt_handler = 0; 1542 _doing_unsafe_access = false; 1543 _stack_guard_state = stack_guard_unused; 1544 #if INCLUDE_JVMCI 1545 _pending_monitorenter = false; 1546 _pending_deoptimization = -1; 1547 _pending_failed_speculation = 0; 1548 _pending_transfer_to_interpreter = false; 1549 _adjusting_comp_level = false; 1550 _in_retryable_allocation = false; 1551 _jvmci._alternate_call_target = NULL; 1552 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1553 if (JVMCICounterSize > 0) { 1554 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1555 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1556 } else { 1557 _jvmci_counters = NULL; 1558 } 1559 #endif // INCLUDE_JVMCI 1560 _reserved_stack_activation = NULL; // stack base not known yet 1561 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1562 _exception_pc = 0; 1563 _exception_handler_pc = 0; 1564 _is_method_handle_return = 0; 1565 _jvmti_thread_state= NULL; 1566 _should_post_on_exceptions_flag = JNI_FALSE; 1567 _interp_only_mode = 0; 1568 _special_runtime_exit_condition = _no_async_condition; 1569 _pending_async_exception = NULL; 1570 _thread_stat = NULL; 1571 _thread_stat = new ThreadStatistics(); 1572 _blocked_on_compilation = false; 1573 _jni_active_critical = 0; 1574 _pending_jni_exception_check_fn = NULL; 1575 _do_not_unlock_if_synchronized = false; 1576 _cached_monitor_info = NULL; 1577 _parker = Parker::Allocate(this); 1578 1579 #ifndef PRODUCT 1580 _jmp_ring_index = 0; 1581 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1582 record_jump(NULL, NULL, NULL, 0); 1583 } 1584 #endif // PRODUCT 1585 1586 // Setup safepoint state info for this thread 1587 ThreadSafepointState::create(this); 1588 1589 debug_only(_java_call_counter = 0); 1590 1591 // JVMTI PopFrame support 1592 _popframe_condition = popframe_inactive; 1593 _popframe_preserved_args = NULL; 1594 _popframe_preserved_args_size = 0; 1595 _frames_to_pop_failed_realloc = 0; 1596 1597 if (SafepointMechanism::uses_thread_local_poll()) { 1598 SafepointMechanism::initialize_header(this); 1599 } 1600 1601 pd_initialize(); 1602 } 1603 1604 JavaThread::JavaThread(bool is_attaching_via_jni) : 1605 Thread() { 1606 initialize(); 1607 if (is_attaching_via_jni) { 1608 _jni_attach_state = _attaching_via_jni; 1609 } else { 1610 _jni_attach_state = _not_attaching_via_jni; 1611 } 1612 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1613 } 1614 1615 bool JavaThread::reguard_stack(address cur_sp) { 1616 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1617 && _stack_guard_state != stack_guard_reserved_disabled) { 1618 return true; // Stack already guarded or guard pages not needed. 1619 } 1620 1621 if (register_stack_overflow()) { 1622 // For those architectures which have separate register and 1623 // memory stacks, we must check the register stack to see if 1624 // it has overflowed. 1625 return false; 1626 } 1627 1628 // Java code never executes within the yellow zone: the latter is only 1629 // there to provoke an exception during stack banging. If java code 1630 // is executing there, either StackShadowPages should be larger, or 1631 // some exception code in c1, c2 or the interpreter isn't unwinding 1632 // when it should. 1633 guarantee(cur_sp > stack_reserved_zone_base(), 1634 "not enough space to reguard - increase StackShadowPages"); 1635 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1636 enable_stack_yellow_reserved_zone(); 1637 if (reserved_stack_activation() != stack_base()) { 1638 set_reserved_stack_activation(stack_base()); 1639 } 1640 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1641 set_reserved_stack_activation(stack_base()); 1642 enable_stack_reserved_zone(); 1643 } 1644 return true; 1645 } 1646 1647 bool JavaThread::reguard_stack(void) { 1648 return reguard_stack(os::current_stack_pointer()); 1649 } 1650 1651 1652 void JavaThread::block_if_vm_exited() { 1653 if (_terminated == _vm_exited) { 1654 // _vm_exited is set at safepoint, and Threads_lock is never released 1655 // we will block here forever 1656 Threads_lock->lock_without_safepoint_check(); 1657 ShouldNotReachHere(); 1658 } 1659 } 1660 1661 1662 // Remove this ifdef when C1 is ported to the compiler interface. 1663 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1664 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1665 1666 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1667 Thread() { 1668 initialize(); 1669 _jni_attach_state = _not_attaching_via_jni; 1670 set_entry_point(entry_point); 1671 // Create the native thread itself. 1672 // %note runtime_23 1673 os::ThreadType thr_type = os::java_thread; 1674 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1675 os::java_thread; 1676 os::create_thread(this, thr_type, stack_sz); 1677 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1678 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1679 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1680 // the exception consists of creating the exception object & initializing it, initialization 1681 // will leave the VM via a JavaCall and then all locks must be unlocked). 1682 // 1683 // The thread is still suspended when we reach here. Thread must be explicit started 1684 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1685 // by calling Threads:add. The reason why this is not done here, is because the thread 1686 // object must be fully initialized (take a look at JVM_Start) 1687 } 1688 1689 JavaThread::~JavaThread() { 1690 1691 // JSR166 -- return the parker to the free list 1692 Parker::Release(_parker); 1693 _parker = NULL; 1694 1695 // Free any remaining previous UnrollBlock 1696 vframeArray* old_array = vframe_array_last(); 1697 1698 if (old_array != NULL) { 1699 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1700 old_array->set_unroll_block(NULL); 1701 delete old_info; 1702 delete old_array; 1703 } 1704 1705 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1706 if (deferred != NULL) { 1707 // This can only happen if thread is destroyed before deoptimization occurs. 1708 assert(deferred->length() != 0, "empty array!"); 1709 do { 1710 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1711 deferred->remove_at(0); 1712 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1713 delete dlv; 1714 } while (deferred->length() != 0); 1715 delete deferred; 1716 } 1717 1718 // All Java related clean up happens in exit 1719 ThreadSafepointState::destroy(this); 1720 if (_thread_stat != NULL) delete _thread_stat; 1721 1722 #if INCLUDE_JVMCI 1723 if (JVMCICounterSize > 0) { 1724 if (jvmci_counters_include(this)) { 1725 for (int i = 0; i < JVMCICounterSize; i++) { 1726 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1727 } 1728 } 1729 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1730 } 1731 #endif // INCLUDE_JVMCI 1732 } 1733 1734 1735 // The first routine called by a new Java thread 1736 void JavaThread::run() { 1737 // initialize thread-local alloc buffer related fields 1738 this->initialize_tlab(); 1739 1740 // used to test validity of stack trace backs 1741 this->record_base_of_stack_pointer(); 1742 1743 // Record real stack base and size. 1744 this->record_stack_base_and_size(); 1745 1746 this->create_stack_guard_pages(); 1747 1748 this->cache_global_variables(); 1749 1750 // Thread is now sufficient initialized to be handled by the safepoint code as being 1751 // in the VM. Change thread state from _thread_new to _thread_in_vm 1752 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1753 1754 assert(JavaThread::current() == this, "sanity check"); 1755 assert(!Thread::current()->owns_locks(), "sanity check"); 1756 1757 DTRACE_THREAD_PROBE(start, this); 1758 1759 // This operation might block. We call that after all safepoint checks for a new thread has 1760 // been completed. 1761 this->set_active_handles(JNIHandleBlock::allocate_block()); 1762 1763 if (JvmtiExport::should_post_thread_life()) { 1764 JvmtiExport::post_thread_start(this); 1765 } 1766 1767 EventThreadStart event; 1768 if (event.should_commit()) { 1769 event.set_thread(JFR_THREAD_ID(this)); 1770 event.commit(); 1771 } 1772 1773 // We call another function to do the rest so we are sure that the stack addresses used 1774 // from there will be lower than the stack base just computed 1775 thread_main_inner(); 1776 1777 // Note, thread is no longer valid at this point! 1778 } 1779 1780 1781 void JavaThread::thread_main_inner() { 1782 assert(JavaThread::current() == this, "sanity check"); 1783 assert(this->threadObj() != NULL, "just checking"); 1784 1785 // Execute thread entry point unless this thread has a pending exception 1786 // or has been stopped before starting. 1787 // Note: Due to JVM_StopThread we can have pending exceptions already! 1788 if (!this->has_pending_exception() && 1789 !java_lang_Thread::is_stillborn(this->threadObj())) { 1790 { 1791 ResourceMark rm(this); 1792 this->set_native_thread_name(this->get_thread_name()); 1793 } 1794 HandleMark hm(this); 1795 this->entry_point()(this, this); 1796 } 1797 1798 DTRACE_THREAD_PROBE(stop, this); 1799 1800 this->exit(false); 1801 this->smr_delete(); 1802 } 1803 1804 1805 static void ensure_join(JavaThread* thread) { 1806 // We do not need to grab the Threads_lock, since we are operating on ourself. 1807 Handle threadObj(thread, thread->threadObj()); 1808 assert(threadObj.not_null(), "java thread object must exist"); 1809 ObjectLocker lock(threadObj, thread); 1810 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1811 thread->clear_pending_exception(); 1812 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1813 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1814 // Clear the native thread instance - this makes isAlive return false and allows the join() 1815 // to complete once we've done the notify_all below 1816 java_lang_Thread::set_thread(threadObj(), NULL); 1817 lock.notify_all(thread); 1818 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1819 thread->clear_pending_exception(); 1820 } 1821 1822 1823 // For any new cleanup additions, please check to see if they need to be applied to 1824 // cleanup_failed_attach_current_thread as well. 1825 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1826 assert(this == JavaThread::current(), "thread consistency check"); 1827 1828 elapsedTimer _timer_exit_phase1; 1829 elapsedTimer _timer_exit_phase2; 1830 elapsedTimer _timer_exit_phase3; 1831 elapsedTimer _timer_exit_phase4; 1832 1833 if (log_is_enabled(Debug, os, thread, timer)) { 1834 _timer_exit_phase1.start(); 1835 } 1836 1837 HandleMark hm(this); 1838 Handle uncaught_exception(this, this->pending_exception()); 1839 this->clear_pending_exception(); 1840 Handle threadObj(this, this->threadObj()); 1841 assert(threadObj.not_null(), "Java thread object should be created"); 1842 1843 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1844 { 1845 EXCEPTION_MARK; 1846 1847 CLEAR_PENDING_EXCEPTION; 1848 } 1849 if (!destroy_vm) { 1850 if (uncaught_exception.not_null()) { 1851 EXCEPTION_MARK; 1852 // Call method Thread.dispatchUncaughtException(). 1853 Klass* thread_klass = SystemDictionary::Thread_klass(); 1854 JavaValue result(T_VOID); 1855 JavaCalls::call_virtual(&result, 1856 threadObj, thread_klass, 1857 vmSymbols::dispatchUncaughtException_name(), 1858 vmSymbols::throwable_void_signature(), 1859 uncaught_exception, 1860 THREAD); 1861 if (HAS_PENDING_EXCEPTION) { 1862 ResourceMark rm(this); 1863 jio_fprintf(defaultStream::error_stream(), 1864 "\nException: %s thrown from the UncaughtExceptionHandler" 1865 " in thread \"%s\"\n", 1866 pending_exception()->klass()->external_name(), 1867 get_thread_name()); 1868 CLEAR_PENDING_EXCEPTION; 1869 } 1870 } 1871 1872 // Called before the java thread exit since we want to read info 1873 // from java_lang_Thread object 1874 EventThreadEnd event; 1875 if (event.should_commit()) { 1876 event.set_thread(JFR_THREAD_ID(this)); 1877 event.commit(); 1878 } 1879 1880 // Call after last event on thread 1881 JFR_ONLY(Jfr::on_thread_exit(this);) 1882 1883 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1884 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1885 // is deprecated anyhow. 1886 if (!is_Compiler_thread()) { 1887 int count = 3; 1888 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1889 EXCEPTION_MARK; 1890 JavaValue result(T_VOID); 1891 Klass* thread_klass = SystemDictionary::Thread_klass(); 1892 JavaCalls::call_virtual(&result, 1893 threadObj, thread_klass, 1894 vmSymbols::exit_method_name(), 1895 vmSymbols::void_method_signature(), 1896 THREAD); 1897 CLEAR_PENDING_EXCEPTION; 1898 } 1899 } 1900 // notify JVMTI 1901 if (JvmtiExport::should_post_thread_life()) { 1902 JvmtiExport::post_thread_end(this); 1903 } 1904 1905 // We have notified the agents that we are exiting, before we go on, 1906 // we must check for a pending external suspend request and honor it 1907 // in order to not surprise the thread that made the suspend request. 1908 while (true) { 1909 { 1910 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1911 if (!is_external_suspend()) { 1912 set_terminated(_thread_exiting); 1913 ThreadService::current_thread_exiting(this); 1914 break; 1915 } 1916 // Implied else: 1917 // Things get a little tricky here. We have a pending external 1918 // suspend request, but we are holding the SR_lock so we 1919 // can't just self-suspend. So we temporarily drop the lock 1920 // and then self-suspend. 1921 } 1922 1923 ThreadBlockInVM tbivm(this); 1924 java_suspend_self(); 1925 1926 // We're done with this suspend request, but we have to loop around 1927 // and check again. Eventually we will get SR_lock without a pending 1928 // external suspend request and will be able to mark ourselves as 1929 // exiting. 1930 } 1931 // no more external suspends are allowed at this point 1932 } else { 1933 // before_exit() has already posted JVMTI THREAD_END events 1934 } 1935 1936 if (log_is_enabled(Debug, os, thread, timer)) { 1937 _timer_exit_phase1.stop(); 1938 _timer_exit_phase2.start(); 1939 } 1940 // Notify waiters on thread object. This has to be done after exit() is called 1941 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1942 // group should have the destroyed bit set before waiters are notified). 1943 ensure_join(this); 1944 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1945 1946 if (log_is_enabled(Debug, os, thread, timer)) { 1947 _timer_exit_phase2.stop(); 1948 _timer_exit_phase3.start(); 1949 } 1950 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1951 // held by this thread must be released. The spec does not distinguish 1952 // between JNI-acquired and regular Java monitors. We can only see 1953 // regular Java monitors here if monitor enter-exit matching is broken. 1954 // 1955 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1956 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1957 if (exit_type == jni_detach) { 1958 // Sanity check even though JNI DetachCurrentThread() would have 1959 // returned JNI_ERR if there was a Java frame. JavaThread exit 1960 // should be done executing Java code by the time we get here. 1961 assert(!this->has_last_Java_frame(), 1962 "should not have a Java frame when detaching or exiting"); 1963 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1964 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1965 } 1966 1967 // These things needs to be done while we are still a Java Thread. Make sure that thread 1968 // is in a consistent state, in case GC happens 1969 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1970 1971 if (active_handles() != NULL) { 1972 JNIHandleBlock* block = active_handles(); 1973 set_active_handles(NULL); 1974 JNIHandleBlock::release_block(block); 1975 } 1976 1977 if (free_handle_block() != NULL) { 1978 JNIHandleBlock* block = free_handle_block(); 1979 set_free_handle_block(NULL); 1980 JNIHandleBlock::release_block(block); 1981 } 1982 1983 // These have to be removed while this is still a valid thread. 1984 remove_stack_guard_pages(); 1985 1986 if (UseTLAB) { 1987 tlab().retire(); 1988 } 1989 1990 if (JvmtiEnv::environments_might_exist()) { 1991 JvmtiExport::cleanup_thread(this); 1992 } 1993 1994 // We must flush any deferred card marks and other various GC barrier 1995 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 1996 // before removing a thread from the list of active threads. 1997 BarrierSet::barrier_set()->on_thread_detach(this); 1998 1999 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2000 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2001 os::current_thread_id()); 2002 2003 if (log_is_enabled(Debug, os, thread, timer)) { 2004 _timer_exit_phase3.stop(); 2005 _timer_exit_phase4.start(); 2006 } 2007 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2008 Threads::remove(this); 2009 2010 if (log_is_enabled(Debug, os, thread, timer)) { 2011 _timer_exit_phase4.stop(); 2012 ResourceMark rm(this); 2013 log_debug(os, thread, timer)("name='%s'" 2014 ", exit-phase1=" JLONG_FORMAT 2015 ", exit-phase2=" JLONG_FORMAT 2016 ", exit-phase3=" JLONG_FORMAT 2017 ", exit-phase4=" JLONG_FORMAT, 2018 get_thread_name(), 2019 _timer_exit_phase1.milliseconds(), 2020 _timer_exit_phase2.milliseconds(), 2021 _timer_exit_phase3.milliseconds(), 2022 _timer_exit_phase4.milliseconds()); 2023 } 2024 } 2025 2026 void JavaThread::cleanup_failed_attach_current_thread() { 2027 if (active_handles() != NULL) { 2028 JNIHandleBlock* block = active_handles(); 2029 set_active_handles(NULL); 2030 JNIHandleBlock::release_block(block); 2031 } 2032 2033 if (free_handle_block() != NULL) { 2034 JNIHandleBlock* block = free_handle_block(); 2035 set_free_handle_block(NULL); 2036 JNIHandleBlock::release_block(block); 2037 } 2038 2039 // These have to be removed while this is still a valid thread. 2040 remove_stack_guard_pages(); 2041 2042 if (UseTLAB) { 2043 tlab().retire(); 2044 } 2045 2046 BarrierSet::barrier_set()->on_thread_detach(this); 2047 2048 Threads::remove(this); 2049 this->smr_delete(); 2050 } 2051 2052 JavaThread* JavaThread::active() { 2053 Thread* thread = Thread::current(); 2054 if (thread->is_Java_thread()) { 2055 return (JavaThread*) thread; 2056 } else { 2057 assert(thread->is_VM_thread(), "this must be a vm thread"); 2058 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2059 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2060 assert(ret->is_Java_thread(), "must be a Java thread"); 2061 return ret; 2062 } 2063 } 2064 2065 bool JavaThread::is_lock_owned(address adr) const { 2066 if (Thread::is_lock_owned(adr)) return true; 2067 2068 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2069 if (chunk->contains(adr)) return true; 2070 } 2071 2072 return false; 2073 } 2074 2075 2076 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2077 chunk->set_next(monitor_chunks()); 2078 set_monitor_chunks(chunk); 2079 } 2080 2081 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2082 guarantee(monitor_chunks() != NULL, "must be non empty"); 2083 if (monitor_chunks() == chunk) { 2084 set_monitor_chunks(chunk->next()); 2085 } else { 2086 MonitorChunk* prev = monitor_chunks(); 2087 while (prev->next() != chunk) prev = prev->next(); 2088 prev->set_next(chunk->next()); 2089 } 2090 } 2091 2092 // JVM support. 2093 2094 // Note: this function shouldn't block if it's called in 2095 // _thread_in_native_trans state (such as from 2096 // check_special_condition_for_native_trans()). 2097 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2098 2099 if (has_last_Java_frame() && has_async_condition()) { 2100 // If we are at a polling page safepoint (not a poll return) 2101 // then we must defer async exception because live registers 2102 // will be clobbered by the exception path. Poll return is 2103 // ok because the call we a returning from already collides 2104 // with exception handling registers and so there is no issue. 2105 // (The exception handling path kills call result registers but 2106 // this is ok since the exception kills the result anyway). 2107 2108 if (is_at_poll_safepoint()) { 2109 // if the code we are returning to has deoptimized we must defer 2110 // the exception otherwise live registers get clobbered on the 2111 // exception path before deoptimization is able to retrieve them. 2112 // 2113 RegisterMap map(this, false); 2114 frame caller_fr = last_frame().sender(&map); 2115 assert(caller_fr.is_compiled_frame(), "what?"); 2116 if (caller_fr.is_deoptimized_frame()) { 2117 log_info(exceptions)("deferred async exception at compiled safepoint"); 2118 return; 2119 } 2120 } 2121 } 2122 2123 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2124 if (condition == _no_async_condition) { 2125 // Conditions have changed since has_special_runtime_exit_condition() 2126 // was called: 2127 // - if we were here only because of an external suspend request, 2128 // then that was taken care of above (or cancelled) so we are done 2129 // - if we were here because of another async request, then it has 2130 // been cleared between the has_special_runtime_exit_condition() 2131 // and now so again we are done 2132 return; 2133 } 2134 2135 // Check for pending async. exception 2136 if (_pending_async_exception != NULL) { 2137 // Only overwrite an already pending exception, if it is not a threadDeath. 2138 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2139 2140 // We cannot call Exceptions::_throw(...) here because we cannot block 2141 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2142 2143 LogTarget(Info, exceptions) lt; 2144 if (lt.is_enabled()) { 2145 ResourceMark rm; 2146 LogStream ls(lt); 2147 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2148 if (has_last_Java_frame()) { 2149 frame f = last_frame(); 2150 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2151 } 2152 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2153 } 2154 _pending_async_exception = NULL; 2155 clear_has_async_exception(); 2156 } 2157 } 2158 2159 if (check_unsafe_error && 2160 condition == _async_unsafe_access_error && !has_pending_exception()) { 2161 condition = _no_async_condition; // done 2162 switch (thread_state()) { 2163 case _thread_in_vm: { 2164 JavaThread* THREAD = this; 2165 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2166 } 2167 case _thread_in_native: { 2168 ThreadInVMfromNative tiv(this); 2169 JavaThread* THREAD = this; 2170 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2171 } 2172 case _thread_in_Java: { 2173 ThreadInVMfromJava tiv(this); 2174 JavaThread* THREAD = this; 2175 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2176 } 2177 default: 2178 ShouldNotReachHere(); 2179 } 2180 } 2181 2182 assert(condition == _no_async_condition || has_pending_exception() || 2183 (!check_unsafe_error && condition == _async_unsafe_access_error), 2184 "must have handled the async condition, if no exception"); 2185 } 2186 2187 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2188 // 2189 // Check for pending external suspend. Internal suspend requests do 2190 // not use handle_special_runtime_exit_condition(). 2191 // If JNIEnv proxies are allowed, don't self-suspend if the target 2192 // thread is not the current thread. In older versions of jdbx, jdbx 2193 // threads could call into the VM with another thread's JNIEnv so we 2194 // can be here operating on behalf of a suspended thread (4432884). 2195 bool do_self_suspend = is_external_suspend_with_lock(); 2196 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2197 // 2198 // Because thread is external suspended the safepoint code will count 2199 // thread as at a safepoint. This can be odd because we can be here 2200 // as _thread_in_Java which would normally transition to _thread_blocked 2201 // at a safepoint. We would like to mark the thread as _thread_blocked 2202 // before calling java_suspend_self like all other callers of it but 2203 // we must then observe proper safepoint protocol. (We can't leave 2204 // _thread_blocked with a safepoint in progress). However we can be 2205 // here as _thread_in_native_trans so we can't use a normal transition 2206 // constructor/destructor pair because they assert on that type of 2207 // transition. We could do something like: 2208 // 2209 // JavaThreadState state = thread_state(); 2210 // set_thread_state(_thread_in_vm); 2211 // { 2212 // ThreadBlockInVM tbivm(this); 2213 // java_suspend_self() 2214 // } 2215 // set_thread_state(_thread_in_vm_trans); 2216 // if (safepoint) block; 2217 // set_thread_state(state); 2218 // 2219 // but that is pretty messy. Instead we just go with the way the 2220 // code has worked before and note that this is the only path to 2221 // java_suspend_self that doesn't put the thread in _thread_blocked 2222 // mode. 2223 2224 frame_anchor()->make_walkable(this); 2225 java_suspend_self(); 2226 2227 // We might be here for reasons in addition to the self-suspend request 2228 // so check for other async requests. 2229 } 2230 2231 if (check_asyncs) { 2232 check_and_handle_async_exceptions(); 2233 } 2234 2235 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2236 } 2237 2238 void JavaThread::send_thread_stop(oop java_throwable) { 2239 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2240 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2241 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2242 2243 // Do not throw asynchronous exceptions against the compiler thread 2244 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2245 if (!can_call_java()) return; 2246 2247 { 2248 // Actually throw the Throwable against the target Thread - however 2249 // only if there is no thread death exception installed already. 2250 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2251 // If the topmost frame is a runtime stub, then we are calling into 2252 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2253 // must deoptimize the caller before continuing, as the compiled exception handler table 2254 // may not be valid 2255 if (has_last_Java_frame()) { 2256 frame f = last_frame(); 2257 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2258 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2259 RegisterMap reg_map(this, UseBiasedLocking); 2260 frame compiled_frame = f.sender(®_map); 2261 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2262 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2263 } 2264 } 2265 } 2266 2267 // Set async. pending exception in thread. 2268 set_pending_async_exception(java_throwable); 2269 2270 if (log_is_enabled(Info, exceptions)) { 2271 ResourceMark rm; 2272 log_info(exceptions)("Pending Async. exception installed of type: %s", 2273 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2274 } 2275 // for AbortVMOnException flag 2276 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2277 } 2278 } 2279 2280 2281 // Interrupt thread so it will wake up from a potential wait() 2282 Thread::interrupt(this); 2283 } 2284 2285 // External suspension mechanism. 2286 // 2287 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2288 // to any VM_locks and it is at a transition 2289 // Self-suspension will happen on the transition out of the vm. 2290 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2291 // 2292 // Guarantees on return: 2293 // + Target thread will not execute any new bytecode (that's why we need to 2294 // force a safepoint) 2295 // + Target thread will not enter any new monitors 2296 // 2297 void JavaThread::java_suspend() { 2298 ThreadsListHandle tlh; 2299 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2300 return; 2301 } 2302 2303 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2304 if (!is_external_suspend()) { 2305 // a racing resume has cancelled us; bail out now 2306 return; 2307 } 2308 2309 // suspend is done 2310 uint32_t debug_bits = 0; 2311 // Warning: is_ext_suspend_completed() may temporarily drop the 2312 // SR_lock to allow the thread to reach a stable thread state if 2313 // it is currently in a transient thread state. 2314 if (is_ext_suspend_completed(false /* !called_by_wait */, 2315 SuspendRetryDelay, &debug_bits)) { 2316 return; 2317 } 2318 } 2319 2320 VM_ThreadSuspend vm_suspend; 2321 VMThread::execute(&vm_suspend); 2322 } 2323 2324 // Part II of external suspension. 2325 // A JavaThread self suspends when it detects a pending external suspend 2326 // request. This is usually on transitions. It is also done in places 2327 // where continuing to the next transition would surprise the caller, 2328 // e.g., monitor entry. 2329 // 2330 // Returns the number of times that the thread self-suspended. 2331 // 2332 // Note: DO NOT call java_suspend_self() when you just want to block current 2333 // thread. java_suspend_self() is the second stage of cooperative 2334 // suspension for external suspend requests and should only be used 2335 // to complete an external suspend request. 2336 // 2337 int JavaThread::java_suspend_self() { 2338 int ret = 0; 2339 2340 // we are in the process of exiting so don't suspend 2341 if (is_exiting()) { 2342 clear_external_suspend(); 2343 return ret; 2344 } 2345 2346 assert(_anchor.walkable() || 2347 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2348 "must have walkable stack"); 2349 2350 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2351 2352 assert(!this->is_ext_suspended(), 2353 "a thread trying to self-suspend should not already be suspended"); 2354 2355 if (this->is_suspend_equivalent()) { 2356 // If we are self-suspending as a result of the lifting of a 2357 // suspend equivalent condition, then the suspend_equivalent 2358 // flag is not cleared until we set the ext_suspended flag so 2359 // that wait_for_ext_suspend_completion() returns consistent 2360 // results. 2361 this->clear_suspend_equivalent(); 2362 } 2363 2364 // A racing resume may have cancelled us before we grabbed SR_lock 2365 // above. Or another external suspend request could be waiting for us 2366 // by the time we return from SR_lock()->wait(). The thread 2367 // that requested the suspension may already be trying to walk our 2368 // stack and if we return now, we can change the stack out from under 2369 // it. This would be a "bad thing (TM)" and cause the stack walker 2370 // to crash. We stay self-suspended until there are no more pending 2371 // external suspend requests. 2372 while (is_external_suspend()) { 2373 ret++; 2374 this->set_ext_suspended(); 2375 2376 // _ext_suspended flag is cleared by java_resume() 2377 while (is_ext_suspended()) { 2378 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2379 } 2380 } 2381 2382 return ret; 2383 } 2384 2385 #ifdef ASSERT 2386 // Verify the JavaThread has not yet been published in the Threads::list, and 2387 // hence doesn't need protection from concurrent access at this stage. 2388 void JavaThread::verify_not_published() { 2389 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2390 // since an unpublished JavaThread doesn't participate in the 2391 // Thread-SMR protocol for keeping a ThreadsList alive. 2392 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2393 } 2394 #endif 2395 2396 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2397 // progress or when _suspend_flags is non-zero. 2398 // Current thread needs to self-suspend if there is a suspend request and/or 2399 // block if a safepoint is in progress. 2400 // Async exception ISN'T checked. 2401 // Note only the ThreadInVMfromNative transition can call this function 2402 // directly and when thread state is _thread_in_native_trans 2403 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2404 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2405 2406 JavaThread *curJT = JavaThread::current(); 2407 bool do_self_suspend = thread->is_external_suspend(); 2408 2409 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2410 2411 // If JNIEnv proxies are allowed, don't self-suspend if the target 2412 // thread is not the current thread. In older versions of jdbx, jdbx 2413 // threads could call into the VM with another thread's JNIEnv so we 2414 // can be here operating on behalf of a suspended thread (4432884). 2415 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2416 JavaThreadState state = thread->thread_state(); 2417 2418 // We mark this thread_blocked state as a suspend-equivalent so 2419 // that a caller to is_ext_suspend_completed() won't be confused. 2420 // The suspend-equivalent state is cleared by java_suspend_self(). 2421 thread->set_suspend_equivalent(); 2422 2423 // If the safepoint code sees the _thread_in_native_trans state, it will 2424 // wait until the thread changes to other thread state. There is no 2425 // guarantee on how soon we can obtain the SR_lock and complete the 2426 // self-suspend request. It would be a bad idea to let safepoint wait for 2427 // too long. Temporarily change the state to _thread_blocked to 2428 // let the VM thread know that this thread is ready for GC. The problem 2429 // of changing thread state is that safepoint could happen just after 2430 // java_suspend_self() returns after being resumed, and VM thread will 2431 // see the _thread_blocked state. We must check for safepoint 2432 // after restoring the state and make sure we won't leave while a safepoint 2433 // is in progress. 2434 thread->set_thread_state(_thread_blocked); 2435 thread->java_suspend_self(); 2436 thread->set_thread_state(state); 2437 2438 InterfaceSupport::serialize_thread_state_with_handler(thread); 2439 } 2440 2441 SafepointMechanism::block_if_requested(curJT); 2442 2443 if (thread->is_deopt_suspend()) { 2444 thread->clear_deopt_suspend(); 2445 RegisterMap map(thread, false); 2446 frame f = thread->last_frame(); 2447 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2448 f = f.sender(&map); 2449 } 2450 if (f.id() == thread->must_deopt_id()) { 2451 thread->clear_must_deopt_id(); 2452 f.deoptimize(thread); 2453 } else { 2454 fatal("missed deoptimization!"); 2455 } 2456 } 2457 2458 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2459 } 2460 2461 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2462 // progress or when _suspend_flags is non-zero. 2463 // Current thread needs to self-suspend if there is a suspend request and/or 2464 // block if a safepoint is in progress. 2465 // Also check for pending async exception (not including unsafe access error). 2466 // Note only the native==>VM/Java barriers can call this function and when 2467 // thread state is _thread_in_native_trans. 2468 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2469 check_safepoint_and_suspend_for_native_trans(thread); 2470 2471 if (thread->has_async_exception()) { 2472 // We are in _thread_in_native_trans state, don't handle unsafe 2473 // access error since that may block. 2474 thread->check_and_handle_async_exceptions(false); 2475 } 2476 } 2477 2478 // This is a variant of the normal 2479 // check_special_condition_for_native_trans with slightly different 2480 // semantics for use by critical native wrappers. It does all the 2481 // normal checks but also performs the transition back into 2482 // thread_in_Java state. This is required so that critical natives 2483 // can potentially block and perform a GC if they are the last thread 2484 // exiting the GCLocker. 2485 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2486 check_special_condition_for_native_trans(thread); 2487 2488 // Finish the transition 2489 thread->set_thread_state(_thread_in_Java); 2490 2491 if (thread->do_critical_native_unlock()) { 2492 ThreadInVMfromJavaNoAsyncException tiv(thread); 2493 GCLocker::unlock_critical(thread); 2494 thread->clear_critical_native_unlock(); 2495 } 2496 } 2497 2498 // We need to guarantee the Threads_lock here, since resumes are not 2499 // allowed during safepoint synchronization 2500 // Can only resume from an external suspension 2501 void JavaThread::java_resume() { 2502 assert_locked_or_safepoint(Threads_lock); 2503 2504 // Sanity check: thread is gone, has started exiting or the thread 2505 // was not externally suspended. 2506 ThreadsListHandle tlh; 2507 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2508 return; 2509 } 2510 2511 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2512 2513 clear_external_suspend(); 2514 2515 if (is_ext_suspended()) { 2516 clear_ext_suspended(); 2517 SR_lock()->notify_all(); 2518 } 2519 } 2520 2521 size_t JavaThread::_stack_red_zone_size = 0; 2522 size_t JavaThread::_stack_yellow_zone_size = 0; 2523 size_t JavaThread::_stack_reserved_zone_size = 0; 2524 size_t JavaThread::_stack_shadow_zone_size = 0; 2525 2526 void JavaThread::create_stack_guard_pages() { 2527 if (!os::uses_stack_guard_pages() || 2528 _stack_guard_state != stack_guard_unused || 2529 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2530 log_info(os, thread)("Stack guard page creation for thread " 2531 UINTX_FORMAT " disabled", os::current_thread_id()); 2532 return; 2533 } 2534 address low_addr = stack_end(); 2535 size_t len = stack_guard_zone_size(); 2536 2537 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2538 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2539 2540 int must_commit = os::must_commit_stack_guard_pages(); 2541 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2542 2543 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2544 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2545 return; 2546 } 2547 2548 if (os::guard_memory((char *) low_addr, len)) { 2549 _stack_guard_state = stack_guard_enabled; 2550 } else { 2551 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2552 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2553 if (os::uncommit_memory((char *) low_addr, len)) { 2554 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2555 } 2556 return; 2557 } 2558 2559 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2560 PTR_FORMAT "-" PTR_FORMAT ".", 2561 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2562 } 2563 2564 void JavaThread::remove_stack_guard_pages() { 2565 assert(Thread::current() == this, "from different thread"); 2566 if (_stack_guard_state == stack_guard_unused) return; 2567 address low_addr = stack_end(); 2568 size_t len = stack_guard_zone_size(); 2569 2570 if (os::must_commit_stack_guard_pages()) { 2571 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2572 _stack_guard_state = stack_guard_unused; 2573 } else { 2574 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2575 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2576 return; 2577 } 2578 } else { 2579 if (_stack_guard_state == stack_guard_unused) return; 2580 if (os::unguard_memory((char *) low_addr, len)) { 2581 _stack_guard_state = stack_guard_unused; 2582 } else { 2583 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2584 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2585 return; 2586 } 2587 } 2588 2589 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2590 PTR_FORMAT "-" PTR_FORMAT ".", 2591 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2592 } 2593 2594 void JavaThread::enable_stack_reserved_zone() { 2595 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2596 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2597 2598 // The base notation is from the stack's point of view, growing downward. 2599 // We need to adjust it to work correctly with guard_memory() 2600 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2601 2602 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2603 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2604 2605 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2606 _stack_guard_state = stack_guard_enabled; 2607 } else { 2608 warning("Attempt to guard stack reserved zone failed."); 2609 } 2610 enable_register_stack_guard(); 2611 } 2612 2613 void JavaThread::disable_stack_reserved_zone() { 2614 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2615 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2616 2617 // Simply return if called for a thread that does not use guard pages. 2618 if (_stack_guard_state == stack_guard_unused) return; 2619 2620 // The base notation is from the stack's point of view, growing downward. 2621 // We need to adjust it to work correctly with guard_memory() 2622 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2623 2624 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2625 _stack_guard_state = stack_guard_reserved_disabled; 2626 } else { 2627 warning("Attempt to unguard stack reserved zone failed."); 2628 } 2629 disable_register_stack_guard(); 2630 } 2631 2632 void JavaThread::enable_stack_yellow_reserved_zone() { 2633 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2634 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2635 2636 // The base notation is from the stacks point of view, growing downward. 2637 // We need to adjust it to work correctly with guard_memory() 2638 address base = stack_red_zone_base(); 2639 2640 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2641 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2642 2643 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2644 _stack_guard_state = stack_guard_enabled; 2645 } else { 2646 warning("Attempt to guard stack yellow zone failed."); 2647 } 2648 enable_register_stack_guard(); 2649 } 2650 2651 void JavaThread::disable_stack_yellow_reserved_zone() { 2652 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2653 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2654 2655 // Simply return if called for a thread that does not use guard pages. 2656 if (_stack_guard_state == stack_guard_unused) return; 2657 2658 // The base notation is from the stacks point of view, growing downward. 2659 // We need to adjust it to work correctly with guard_memory() 2660 address base = stack_red_zone_base(); 2661 2662 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2663 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2664 } else { 2665 warning("Attempt to unguard stack yellow zone failed."); 2666 } 2667 disable_register_stack_guard(); 2668 } 2669 2670 void JavaThread::enable_stack_red_zone() { 2671 // The base notation is from the stacks point of view, growing downward. 2672 // We need to adjust it to work correctly with guard_memory() 2673 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2674 address base = stack_red_zone_base() - stack_red_zone_size(); 2675 2676 guarantee(base < stack_base(), "Error calculating stack red zone"); 2677 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2678 2679 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2680 warning("Attempt to guard stack red zone failed."); 2681 } 2682 } 2683 2684 void JavaThread::disable_stack_red_zone() { 2685 // The base notation is from the stacks point of view, growing downward. 2686 // We need to adjust it to work correctly with guard_memory() 2687 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2688 address base = stack_red_zone_base() - stack_red_zone_size(); 2689 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2690 warning("Attempt to unguard stack red zone failed."); 2691 } 2692 } 2693 2694 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2695 // ignore is there is no stack 2696 if (!has_last_Java_frame()) return; 2697 // traverse the stack frames. Starts from top frame. 2698 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2699 frame* fr = fst.current(); 2700 f(fr, fst.register_map()); 2701 } 2702 } 2703 2704 2705 #ifndef PRODUCT 2706 // Deoptimization 2707 // Function for testing deoptimization 2708 void JavaThread::deoptimize() { 2709 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2710 StackFrameStream fst(this, UseBiasedLocking); 2711 bool deopt = false; // Dump stack only if a deopt actually happens. 2712 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2713 // Iterate over all frames in the thread and deoptimize 2714 for (; !fst.is_done(); fst.next()) { 2715 if (fst.current()->can_be_deoptimized()) { 2716 2717 if (only_at) { 2718 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2719 // consists of comma or carriage return separated numbers so 2720 // search for the current bci in that string. 2721 address pc = fst.current()->pc(); 2722 nmethod* nm = (nmethod*) fst.current()->cb(); 2723 ScopeDesc* sd = nm->scope_desc_at(pc); 2724 char buffer[8]; 2725 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2726 size_t len = strlen(buffer); 2727 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2728 while (found != NULL) { 2729 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2730 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2731 // Check that the bci found is bracketed by terminators. 2732 break; 2733 } 2734 found = strstr(found + 1, buffer); 2735 } 2736 if (!found) { 2737 continue; 2738 } 2739 } 2740 2741 if (DebugDeoptimization && !deopt) { 2742 deopt = true; // One-time only print before deopt 2743 tty->print_cr("[BEFORE Deoptimization]"); 2744 trace_frames(); 2745 trace_stack(); 2746 } 2747 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2748 } 2749 } 2750 2751 if (DebugDeoptimization && deopt) { 2752 tty->print_cr("[AFTER Deoptimization]"); 2753 trace_frames(); 2754 } 2755 } 2756 2757 2758 // Make zombies 2759 void JavaThread::make_zombies() { 2760 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2761 if (fst.current()->can_be_deoptimized()) { 2762 // it is a Java nmethod 2763 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2764 nm->make_not_entrant(); 2765 } 2766 } 2767 } 2768 #endif // PRODUCT 2769 2770 2771 void JavaThread::deoptimized_wrt_marked_nmethods() { 2772 if (!has_last_Java_frame()) return; 2773 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2774 StackFrameStream fst(this, UseBiasedLocking); 2775 for (; !fst.is_done(); fst.next()) { 2776 if (fst.current()->should_be_deoptimized()) { 2777 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2778 } 2779 } 2780 } 2781 2782 2783 // If the caller is a NamedThread, then remember, in the current scope, 2784 // the given JavaThread in its _processed_thread field. 2785 class RememberProcessedThread: public StackObj { 2786 NamedThread* _cur_thr; 2787 public: 2788 RememberProcessedThread(JavaThread* jthr) { 2789 Thread* thread = Thread::current(); 2790 if (thread->is_Named_thread()) { 2791 _cur_thr = (NamedThread *)thread; 2792 _cur_thr->set_processed_thread(jthr); 2793 } else { 2794 _cur_thr = NULL; 2795 } 2796 } 2797 2798 ~RememberProcessedThread() { 2799 if (_cur_thr) { 2800 _cur_thr->set_processed_thread(NULL); 2801 } 2802 } 2803 }; 2804 2805 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2806 // Verify that the deferred card marks have been flushed. 2807 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2808 2809 // Traverse the GCHandles 2810 Thread::oops_do(f, cf); 2811 2812 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2813 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2814 2815 if (has_last_Java_frame()) { 2816 // Record JavaThread to GC thread 2817 RememberProcessedThread rpt(this); 2818 2819 // Traverse the privileged stack 2820 if (_privileged_stack_top != NULL) { 2821 _privileged_stack_top->oops_do(f); 2822 } 2823 2824 // traverse the registered growable array 2825 if (_array_for_gc != NULL) { 2826 for (int index = 0; index < _array_for_gc->length(); index++) { 2827 f->do_oop(_array_for_gc->adr_at(index)); 2828 } 2829 } 2830 2831 // Traverse the monitor chunks 2832 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2833 chunk->oops_do(f); 2834 } 2835 2836 // Traverse the execution stack 2837 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2838 fst.current()->oops_do(f, cf, fst.register_map()); 2839 } 2840 } 2841 2842 // callee_target is never live across a gc point so NULL it here should 2843 // it still contain a methdOop. 2844 2845 set_callee_target(NULL); 2846 2847 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2848 // If we have deferred set_locals there might be oops waiting to be 2849 // written 2850 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2851 if (list != NULL) { 2852 for (int i = 0; i < list->length(); i++) { 2853 list->at(i)->oops_do(f); 2854 } 2855 } 2856 2857 // Traverse instance variables at the end since the GC may be moving things 2858 // around using this function 2859 f->do_oop((oop*) &_threadObj); 2860 f->do_oop((oop*) &_vm_result); 2861 f->do_oop((oop*) &_exception_oop); 2862 f->do_oop((oop*) &_pending_async_exception); 2863 2864 if (jvmti_thread_state() != NULL) { 2865 jvmti_thread_state()->oops_do(f); 2866 } 2867 } 2868 2869 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 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 // Traverse the execution stack 2875 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2876 fst.current()->nmethods_do(cf); 2877 } 2878 } 2879 } 2880 2881 void JavaThread::metadata_do(void f(Metadata*)) { 2882 if (has_last_Java_frame()) { 2883 // Traverse the execution stack to call f() on the methods in the stack 2884 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2885 fst.current()->metadata_do(f); 2886 } 2887 } else if (is_Compiler_thread()) { 2888 // need to walk ciMetadata in current compile tasks to keep alive. 2889 CompilerThread* ct = (CompilerThread*)this; 2890 if (ct->env() != NULL) { 2891 ct->env()->metadata_do(f); 2892 } 2893 CompileTask* task = ct->task(); 2894 if (task != NULL) { 2895 task->metadata_do(f); 2896 } 2897 } 2898 } 2899 2900 // Printing 2901 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2902 switch (_thread_state) { 2903 case _thread_uninitialized: return "_thread_uninitialized"; 2904 case _thread_new: return "_thread_new"; 2905 case _thread_new_trans: return "_thread_new_trans"; 2906 case _thread_in_native: return "_thread_in_native"; 2907 case _thread_in_native_trans: return "_thread_in_native_trans"; 2908 case _thread_in_vm: return "_thread_in_vm"; 2909 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2910 case _thread_in_Java: return "_thread_in_Java"; 2911 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2912 case _thread_blocked: return "_thread_blocked"; 2913 case _thread_blocked_trans: return "_thread_blocked_trans"; 2914 default: return "unknown thread state"; 2915 } 2916 } 2917 2918 #ifndef PRODUCT 2919 void JavaThread::print_thread_state_on(outputStream *st) const { 2920 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2921 }; 2922 void JavaThread::print_thread_state() const { 2923 print_thread_state_on(tty); 2924 } 2925 #endif // PRODUCT 2926 2927 // Called by Threads::print() for VM_PrintThreads operation 2928 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2929 st->print_raw("\""); 2930 st->print_raw(get_thread_name()); 2931 st->print_raw("\" "); 2932 oop thread_oop = threadObj(); 2933 if (thread_oop != NULL) { 2934 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2935 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2936 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2937 } 2938 Thread::print_on(st, print_extended_info); 2939 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2940 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2941 if (thread_oop != NULL) { 2942 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2943 } 2944 #ifndef PRODUCT 2945 print_thread_state_on(st); 2946 _safepoint_state->print_on(st); 2947 #endif // PRODUCT 2948 if (is_Compiler_thread()) { 2949 CompileTask *task = ((CompilerThread*)this)->task(); 2950 if (task != NULL) { 2951 st->print(" Compiling: "); 2952 task->print(st, NULL, true, false); 2953 } else { 2954 st->print(" No compile task"); 2955 } 2956 st->cr(); 2957 } 2958 } 2959 2960 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2961 st->print("%s", get_thread_name_string(buf, buflen)); 2962 } 2963 2964 // Called by fatal error handler. The difference between this and 2965 // JavaThread::print() is that we can't grab lock or allocate memory. 2966 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2967 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2968 oop thread_obj = threadObj(); 2969 if (thread_obj != NULL) { 2970 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2971 } 2972 st->print(" ["); 2973 st->print("%s", _get_thread_state_name(_thread_state)); 2974 if (osthread()) { 2975 st->print(", id=%d", osthread()->thread_id()); 2976 } 2977 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2978 p2i(stack_end()), p2i(stack_base())); 2979 st->print("]"); 2980 2981 ThreadsSMRSupport::print_info_on(this, st); 2982 return; 2983 } 2984 2985 // Verification 2986 2987 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2988 2989 void JavaThread::verify() { 2990 // Verify oops in the thread. 2991 oops_do(&VerifyOopClosure::verify_oop, NULL); 2992 2993 // Verify the stack frames. 2994 frames_do(frame_verify); 2995 } 2996 2997 // CR 6300358 (sub-CR 2137150) 2998 // Most callers of this method assume that it can't return NULL but a 2999 // thread may not have a name whilst it is in the process of attaching to 3000 // the VM - see CR 6412693, and there are places where a JavaThread can be 3001 // seen prior to having it's threadObj set (eg JNI attaching threads and 3002 // if vm exit occurs during initialization). These cases can all be accounted 3003 // for such that this method never returns NULL. 3004 const char* JavaThread::get_thread_name() const { 3005 #ifdef ASSERT 3006 // early safepoints can hit while current thread does not yet have TLS 3007 if (!SafepointSynchronize::is_at_safepoint()) { 3008 Thread *cur = Thread::current(); 3009 if (!(cur->is_Java_thread() && cur == this)) { 3010 // Current JavaThreads are allowed to get their own name without 3011 // the Threads_lock. 3012 assert_locked_or_safepoint(Threads_lock); 3013 } 3014 } 3015 #endif // ASSERT 3016 return get_thread_name_string(); 3017 } 3018 3019 // Returns a non-NULL representation of this thread's name, or a suitable 3020 // descriptive string if there is no set name 3021 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3022 const char* name_str; 3023 oop thread_obj = threadObj(); 3024 if (thread_obj != NULL) { 3025 oop name = java_lang_Thread::name(thread_obj); 3026 if (name != NULL) { 3027 if (buf == NULL) { 3028 name_str = java_lang_String::as_utf8_string(name); 3029 } else { 3030 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3031 } 3032 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3033 name_str = "<no-name - thread is attaching>"; 3034 } else { 3035 name_str = Thread::name(); 3036 } 3037 } else { 3038 name_str = Thread::name(); 3039 } 3040 assert(name_str != NULL, "unexpected NULL thread name"); 3041 return name_str; 3042 } 3043 3044 3045 const char* JavaThread::get_threadgroup_name() const { 3046 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3047 oop thread_obj = threadObj(); 3048 if (thread_obj != NULL) { 3049 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3050 if (thread_group != NULL) { 3051 // ThreadGroup.name can be null 3052 return java_lang_ThreadGroup::name(thread_group); 3053 } 3054 } 3055 return NULL; 3056 } 3057 3058 const char* JavaThread::get_parent_name() const { 3059 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3060 oop thread_obj = threadObj(); 3061 if (thread_obj != NULL) { 3062 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3063 if (thread_group != NULL) { 3064 oop parent = java_lang_ThreadGroup::parent(thread_group); 3065 if (parent != NULL) { 3066 // ThreadGroup.name can be null 3067 return java_lang_ThreadGroup::name(parent); 3068 } 3069 } 3070 } 3071 return NULL; 3072 } 3073 3074 ThreadPriority JavaThread::java_priority() const { 3075 oop thr_oop = threadObj(); 3076 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3077 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3078 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3079 return priority; 3080 } 3081 3082 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3083 3084 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3085 // Link Java Thread object <-> C++ Thread 3086 3087 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3088 // and put it into a new Handle. The Handle "thread_oop" can then 3089 // be used to pass the C++ thread object to other methods. 3090 3091 // Set the Java level thread object (jthread) field of the 3092 // new thread (a JavaThread *) to C++ thread object using the 3093 // "thread_oop" handle. 3094 3095 // Set the thread field (a JavaThread *) of the 3096 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3097 3098 Handle thread_oop(Thread::current(), 3099 JNIHandles::resolve_non_null(jni_thread)); 3100 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3101 "must be initialized"); 3102 set_threadObj(thread_oop()); 3103 java_lang_Thread::set_thread(thread_oop(), this); 3104 3105 if (prio == NoPriority) { 3106 prio = java_lang_Thread::priority(thread_oop()); 3107 assert(prio != NoPriority, "A valid priority should be present"); 3108 } 3109 3110 // Push the Java priority down to the native thread; needs Threads_lock 3111 Thread::set_priority(this, prio); 3112 3113 // Add the new thread to the Threads list and set it in motion. 3114 // We must have threads lock in order to call Threads::add. 3115 // It is crucial that we do not block before the thread is 3116 // added to the Threads list for if a GC happens, then the java_thread oop 3117 // will not be visited by GC. 3118 Threads::add(this); 3119 } 3120 3121 oop JavaThread::current_park_blocker() { 3122 // Support for JSR-166 locks 3123 oop thread_oop = threadObj(); 3124 if (thread_oop != NULL && 3125 JDK_Version::current().supports_thread_park_blocker()) { 3126 return java_lang_Thread::park_blocker(thread_oop); 3127 } 3128 return NULL; 3129 } 3130 3131 3132 void JavaThread::print_stack_on(outputStream* st) { 3133 if (!has_last_Java_frame()) return; 3134 ResourceMark rm; 3135 HandleMark hm; 3136 3137 RegisterMap reg_map(this); 3138 vframe* start_vf = last_java_vframe(®_map); 3139 int count = 0; 3140 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3141 if (f->is_java_frame()) { 3142 javaVFrame* jvf = javaVFrame::cast(f); 3143 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3144 3145 // Print out lock information 3146 if (JavaMonitorsInStackTrace) { 3147 jvf->print_lock_info_on(st, count); 3148 } 3149 } else { 3150 // Ignore non-Java frames 3151 } 3152 3153 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3154 count++; 3155 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3156 } 3157 } 3158 3159 3160 // JVMTI PopFrame support 3161 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3162 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3163 if (in_bytes(size_in_bytes) != 0) { 3164 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3165 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3166 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3167 } 3168 } 3169 3170 void* JavaThread::popframe_preserved_args() { 3171 return _popframe_preserved_args; 3172 } 3173 3174 ByteSize JavaThread::popframe_preserved_args_size() { 3175 return in_ByteSize(_popframe_preserved_args_size); 3176 } 3177 3178 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3179 int sz = in_bytes(popframe_preserved_args_size()); 3180 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3181 return in_WordSize(sz / wordSize); 3182 } 3183 3184 void JavaThread::popframe_free_preserved_args() { 3185 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3186 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3187 _popframe_preserved_args = NULL; 3188 _popframe_preserved_args_size = 0; 3189 } 3190 3191 #ifndef PRODUCT 3192 3193 void JavaThread::trace_frames() { 3194 tty->print_cr("[Describe stack]"); 3195 int frame_no = 1; 3196 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3197 tty->print(" %d. ", frame_no++); 3198 fst.current()->print_value_on(tty, this); 3199 tty->cr(); 3200 } 3201 } 3202 3203 class PrintAndVerifyOopClosure: public OopClosure { 3204 protected: 3205 template <class T> inline void do_oop_work(T* p) { 3206 oop obj = RawAccess<>::oop_load(p); 3207 if (obj == NULL) return; 3208 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3209 if (oopDesc::is_oop_or_null(obj)) { 3210 if (obj->is_objArray()) { 3211 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3212 } else { 3213 obj->print(); 3214 } 3215 } else { 3216 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3217 } 3218 tty->cr(); 3219 } 3220 public: 3221 virtual void do_oop(oop* p) { do_oop_work(p); } 3222 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3223 }; 3224 3225 3226 static void oops_print(frame* f, const RegisterMap *map) { 3227 PrintAndVerifyOopClosure print; 3228 f->print_value(); 3229 f->oops_do(&print, NULL, (RegisterMap*)map); 3230 } 3231 3232 // Print our all the locations that contain oops and whether they are 3233 // valid or not. This useful when trying to find the oldest frame 3234 // where an oop has gone bad since the frame walk is from youngest to 3235 // oldest. 3236 void JavaThread::trace_oops() { 3237 tty->print_cr("[Trace oops]"); 3238 frames_do(oops_print); 3239 } 3240 3241 3242 #ifdef ASSERT 3243 // Print or validate the layout of stack frames 3244 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3245 ResourceMark rm; 3246 PRESERVE_EXCEPTION_MARK; 3247 FrameValues values; 3248 int frame_no = 0; 3249 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3250 fst.current()->describe(values, ++frame_no); 3251 if (depth == frame_no) break; 3252 } 3253 if (validate_only) { 3254 values.validate(); 3255 } else { 3256 tty->print_cr("[Describe stack layout]"); 3257 values.print(this); 3258 } 3259 } 3260 #endif 3261 3262 void JavaThread::trace_stack_from(vframe* start_vf) { 3263 ResourceMark rm; 3264 int vframe_no = 1; 3265 for (vframe* f = start_vf; f; f = f->sender()) { 3266 if (f->is_java_frame()) { 3267 javaVFrame::cast(f)->print_activation(vframe_no++); 3268 } else { 3269 f->print(); 3270 } 3271 if (vframe_no > StackPrintLimit) { 3272 tty->print_cr("...<more frames>..."); 3273 return; 3274 } 3275 } 3276 } 3277 3278 3279 void JavaThread::trace_stack() { 3280 if (!has_last_Java_frame()) return; 3281 ResourceMark rm; 3282 HandleMark hm; 3283 RegisterMap reg_map(this); 3284 trace_stack_from(last_java_vframe(®_map)); 3285 } 3286 3287 3288 #endif // PRODUCT 3289 3290 3291 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3292 assert(reg_map != NULL, "a map must be given"); 3293 frame f = last_frame(); 3294 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3295 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3296 } 3297 return NULL; 3298 } 3299 3300 3301 Klass* JavaThread::security_get_caller_class(int depth) { 3302 vframeStream vfst(this); 3303 vfst.security_get_caller_frame(depth); 3304 if (!vfst.at_end()) { 3305 return vfst.method()->method_holder(); 3306 } 3307 return NULL; 3308 } 3309 3310 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3311 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3312 CompileBroker::compiler_thread_loop(); 3313 } 3314 3315 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3316 NMethodSweeper::sweeper_loop(); 3317 } 3318 3319 // Create a CompilerThread 3320 CompilerThread::CompilerThread(CompileQueue* queue, 3321 CompilerCounters* counters) 3322 : JavaThread(&compiler_thread_entry) { 3323 _env = NULL; 3324 _log = NULL; 3325 _task = NULL; 3326 _queue = queue; 3327 _counters = counters; 3328 _buffer_blob = NULL; 3329 _compiler = NULL; 3330 3331 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3332 resource_area()->bias_to(mtCompiler); 3333 3334 #ifndef PRODUCT 3335 _ideal_graph_printer = NULL; 3336 #endif 3337 } 3338 3339 CompilerThread::~CompilerThread() { 3340 // Delete objects which were allocated on heap. 3341 delete _counters; 3342 } 3343 3344 bool CompilerThread::can_call_java() const { 3345 return _compiler != NULL && _compiler->is_jvmci(); 3346 } 3347 3348 // Create sweeper thread 3349 CodeCacheSweeperThread::CodeCacheSweeperThread() 3350 : JavaThread(&sweeper_thread_entry) { 3351 _scanned_compiled_method = NULL; 3352 } 3353 3354 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3355 JavaThread::oops_do(f, cf); 3356 if (_scanned_compiled_method != NULL && cf != NULL) { 3357 // Safepoints can occur when the sweeper is scanning an nmethod so 3358 // process it here to make sure it isn't unloaded in the middle of 3359 // a scan. 3360 cf->do_code_blob(_scanned_compiled_method); 3361 } 3362 } 3363 3364 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3365 JavaThread::nmethods_do(cf); 3366 if (_scanned_compiled_method != NULL && cf != NULL) { 3367 // Safepoints can occur when the sweeper is scanning an nmethod so 3368 // process it here to make sure it isn't unloaded in the middle of 3369 // a scan. 3370 cf->do_code_blob(_scanned_compiled_method); 3371 } 3372 } 3373 3374 3375 // ======= Threads ======== 3376 3377 // The Threads class links together all active threads, and provides 3378 // operations over all threads. It is protected by the Threads_lock, 3379 // which is also used in other global contexts like safepointing. 3380 // ThreadsListHandles are used to safely perform operations on one 3381 // or more threads without the risk of the thread exiting during the 3382 // operation. 3383 // 3384 // Note: The Threads_lock is currently more widely used than we 3385 // would like. We are actively migrating Threads_lock uses to other 3386 // mechanisms in order to reduce Threads_lock contention. 3387 3388 JavaThread* Threads::_thread_list = NULL; 3389 int Threads::_number_of_threads = 0; 3390 int Threads::_number_of_non_daemon_threads = 0; 3391 int Threads::_return_code = 0; 3392 int Threads::_thread_claim_parity = 0; 3393 size_t JavaThread::_stack_size_at_create = 0; 3394 3395 #ifdef ASSERT 3396 bool Threads::_vm_complete = false; 3397 size_t Threads::_threads_before_barrier_set = 0; 3398 #endif 3399 3400 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3401 Prefetch::read((void*)addr, prefetch_interval); 3402 return *addr; 3403 } 3404 3405 // Possibly the ugliest for loop the world has seen. C++ does not allow 3406 // multiple types in the declaration section of the for loop. In this case 3407 // we are only dealing with pointers and hence can cast them. It looks ugly 3408 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3409 #define DO_JAVA_THREADS(LIST, X) \ 3410 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3411 *MACRO_list = (JavaThread*)(LIST), \ 3412 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3413 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3414 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3415 MACRO_current_p != MACRO_end; \ 3416 MACRO_current_p++, \ 3417 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3418 3419 // All JavaThreads 3420 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3421 3422 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3423 void Threads::non_java_threads_do(ThreadClosure* tc) { 3424 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3425 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3426 tc->do_thread(njti.current()); 3427 } 3428 } 3429 3430 // All JavaThreads 3431 void Threads::java_threads_do(ThreadClosure* tc) { 3432 assert_locked_or_safepoint(Threads_lock); 3433 // ALL_JAVA_THREADS iterates through all JavaThreads. 3434 ALL_JAVA_THREADS(p) { 3435 tc->do_thread(p); 3436 } 3437 } 3438 3439 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3440 assert_locked_or_safepoint(Threads_lock); 3441 java_threads_do(tc); 3442 tc->do_thread(VMThread::vm_thread()); 3443 } 3444 3445 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3446 void Threads::threads_do(ThreadClosure* tc) { 3447 assert_locked_or_safepoint(Threads_lock); 3448 java_threads_do(tc); 3449 non_java_threads_do(tc); 3450 } 3451 3452 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3453 int cp = Threads::thread_claim_parity(); 3454 ALL_JAVA_THREADS(p) { 3455 if (p->claim_oops_do(is_par, cp)) { 3456 tc->do_thread(p); 3457 } 3458 } 3459 VMThread* vmt = VMThread::vm_thread(); 3460 if (vmt->claim_oops_do(is_par, cp)) { 3461 tc->do_thread(vmt); 3462 } 3463 } 3464 3465 // The system initialization in the library has three phases. 3466 // 3467 // Phase 1: java.lang.System class initialization 3468 // java.lang.System is a primordial class loaded and initialized 3469 // by the VM early during startup. java.lang.System.<clinit> 3470 // only does registerNatives and keeps the rest of the class 3471 // initialization work later until thread initialization completes. 3472 // 3473 // System.initPhase1 initializes the system properties, the static 3474 // fields in, out, and err. Set up java signal handlers, OS-specific 3475 // system settings, and thread group of the main thread. 3476 static void call_initPhase1(TRAPS) { 3477 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3478 JavaValue result(T_VOID); 3479 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3480 vmSymbols::void_method_signature(), CHECK); 3481 } 3482 3483 // Phase 2. Module system initialization 3484 // This will initialize the module system. Only java.base classes 3485 // can be loaded until phase 2 completes. 3486 // 3487 // Call System.initPhase2 after the compiler initialization and jsr292 3488 // classes get initialized because module initialization runs a lot of java 3489 // code, that for performance reasons, should be compiled. Also, this will 3490 // enable the startup code to use lambda and other language features in this 3491 // phase and onward. 3492 // 3493 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3494 static void call_initPhase2(TRAPS) { 3495 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3496 3497 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3498 3499 JavaValue result(T_INT); 3500 JavaCallArguments args; 3501 args.push_int(DisplayVMOutputToStderr); 3502 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3503 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3504 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3505 if (result.get_jint() != JNI_OK) { 3506 vm_exit_during_initialization(); // no message or exception 3507 } 3508 3509 universe_post_module_init(); 3510 } 3511 3512 // Phase 3. final setup - set security manager, system class loader and TCCL 3513 // 3514 // This will instantiate and set the security manager, set the system class 3515 // loader as well as the thread context class loader. The security manager 3516 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3517 // other modules or the application's classpath. 3518 static void call_initPhase3(TRAPS) { 3519 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3520 JavaValue result(T_VOID); 3521 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3522 vmSymbols::void_method_signature(), CHECK); 3523 } 3524 3525 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3526 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3527 3528 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3529 create_vm_init_libraries(); 3530 } 3531 3532 initialize_class(vmSymbols::java_lang_String(), CHECK); 3533 3534 // Inject CompactStrings value after the static initializers for String ran. 3535 java_lang_String::set_compact_strings(CompactStrings); 3536 3537 // Initialize java_lang.System (needed before creating the thread) 3538 initialize_class(vmSymbols::java_lang_System(), CHECK); 3539 // The VM creates & returns objects of this class. Make sure it's initialized. 3540 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3541 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3542 Handle thread_group = create_initial_thread_group(CHECK); 3543 Universe::set_main_thread_group(thread_group()); 3544 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3545 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3546 main_thread->set_threadObj(thread_object); 3547 // Set thread status to running since main thread has 3548 // been started and running. 3549 java_lang_Thread::set_thread_status(thread_object, 3550 java_lang_Thread::RUNNABLE); 3551 3552 // The VM creates objects of this class. 3553 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3554 3555 // The VM preresolves methods to these classes. Make sure that they get initialized 3556 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3557 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3558 3559 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3560 call_initPhase1(CHECK); 3561 3562 // get the Java runtime name after java.lang.System is initialized 3563 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3564 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3565 3566 // an instance of OutOfMemory exception has been allocated earlier 3567 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3568 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3569 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3570 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3571 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3572 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3573 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3574 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3575 } 3576 3577 void Threads::initialize_jsr292_core_classes(TRAPS) { 3578 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3579 3580 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3581 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3582 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3583 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3584 } 3585 3586 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3587 extern void JDK_Version_init(); 3588 3589 // Preinitialize version info. 3590 VM_Version::early_initialize(); 3591 3592 // Check version 3593 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3594 3595 // Initialize library-based TLS 3596 ThreadLocalStorage::init(); 3597 3598 // Initialize the output stream module 3599 ostream_init(); 3600 3601 // Process java launcher properties. 3602 Arguments::process_sun_java_launcher_properties(args); 3603 3604 // Initialize the os module 3605 os::init(); 3606 3607 // Record VM creation timing statistics 3608 TraceVmCreationTime create_vm_timer; 3609 create_vm_timer.start(); 3610 3611 // Initialize system properties. 3612 Arguments::init_system_properties(); 3613 3614 // So that JDK version can be used as a discriminator when parsing arguments 3615 JDK_Version_init(); 3616 3617 // Update/Initialize System properties after JDK version number is known 3618 Arguments::init_version_specific_system_properties(); 3619 3620 // Make sure to initialize log configuration *before* parsing arguments 3621 LogConfiguration::initialize(create_vm_timer.begin_time()); 3622 3623 // Parse arguments 3624 // Note: this internally calls os::init_container_support() 3625 jint parse_result = Arguments::parse(args); 3626 if (parse_result != JNI_OK) return parse_result; 3627 3628 os::init_before_ergo(); 3629 3630 jint ergo_result = Arguments::apply_ergo(); 3631 if (ergo_result != JNI_OK) return ergo_result; 3632 3633 // Final check of all ranges after ergonomics which may change values. 3634 if (!JVMFlagRangeList::check_ranges()) { 3635 return JNI_EINVAL; 3636 } 3637 3638 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3639 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3640 if (!constraint_result) { 3641 return JNI_EINVAL; 3642 } 3643 3644 JVMFlagWriteableList::mark_startup(); 3645 3646 if (PauseAtStartup) { 3647 os::pause(); 3648 } 3649 3650 HOTSPOT_VM_INIT_BEGIN(); 3651 3652 // Timing (must come after argument parsing) 3653 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3654 3655 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3656 // Initialize assert poison page mechanism. 3657 if (ShowRegistersOnAssert) { 3658 initialize_assert_poison(); 3659 } 3660 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3661 3662 // Initialize the os module after parsing the args 3663 jint os_init_2_result = os::init_2(); 3664 if (os_init_2_result != JNI_OK) return os_init_2_result; 3665 3666 SafepointMechanism::initialize(); 3667 3668 jint adjust_after_os_result = Arguments::adjust_after_os(); 3669 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3670 3671 // Initialize output stream logging 3672 ostream_init_log(); 3673 3674 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3675 // Must be before create_vm_init_agents() 3676 if (Arguments::init_libraries_at_startup()) { 3677 convert_vm_init_libraries_to_agents(); 3678 } 3679 3680 // Launch -agentlib/-agentpath and converted -Xrun agents 3681 if (Arguments::init_agents_at_startup()) { 3682 create_vm_init_agents(); 3683 } 3684 3685 // Initialize Threads state 3686 _thread_list = NULL; 3687 _number_of_threads = 0; 3688 _number_of_non_daemon_threads = 0; 3689 3690 // Initialize global data structures and create system classes in heap 3691 vm_init_globals(); 3692 3693 #if INCLUDE_JVMCI 3694 if (JVMCICounterSize > 0) { 3695 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3696 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3697 } else { 3698 JavaThread::_jvmci_old_thread_counters = NULL; 3699 } 3700 #endif // INCLUDE_JVMCI 3701 3702 // Attach the main thread to this os thread 3703 JavaThread* main_thread = new JavaThread(); 3704 main_thread->set_thread_state(_thread_in_vm); 3705 main_thread->initialize_thread_current(); 3706 // must do this before set_active_handles 3707 main_thread->record_stack_base_and_size(); 3708 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3709 3710 if (!main_thread->set_as_starting_thread()) { 3711 vm_shutdown_during_initialization( 3712 "Failed necessary internal allocation. Out of swap space"); 3713 main_thread->smr_delete(); 3714 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3715 return JNI_ENOMEM; 3716 } 3717 3718 // Enable guard page *after* os::create_main_thread(), otherwise it would 3719 // crash Linux VM, see notes in os_linux.cpp. 3720 main_thread->create_stack_guard_pages(); 3721 3722 // Initialize Java-Level synchronization subsystem 3723 ObjectMonitor::Initialize(); 3724 3725 // Initialize global modules 3726 jint status = init_globals(); 3727 if (status != JNI_OK) { 3728 main_thread->smr_delete(); 3729 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3730 return status; 3731 } 3732 3733 JFR_ONLY(Jfr::on_vm_init();) 3734 3735 // Should be done after the heap is fully created 3736 main_thread->cache_global_variables(); 3737 3738 HandleMark hm; 3739 3740 { MutexLocker mu(Threads_lock); 3741 Threads::add(main_thread); 3742 } 3743 3744 // Any JVMTI raw monitors entered in onload will transition into 3745 // real raw monitor. VM is setup enough here for raw monitor enter. 3746 JvmtiExport::transition_pending_onload_raw_monitors(); 3747 3748 // Create the VMThread 3749 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3750 3751 VMThread::create(); 3752 Thread* vmthread = VMThread::vm_thread(); 3753 3754 if (!os::create_thread(vmthread, os::vm_thread)) { 3755 vm_exit_during_initialization("Cannot create VM thread. " 3756 "Out of system resources."); 3757 } 3758 3759 // Wait for the VM thread to become ready, and VMThread::run to initialize 3760 // Monitors can have spurious returns, must always check another state flag 3761 { 3762 MutexLocker ml(Notify_lock); 3763 os::start_thread(vmthread); 3764 while (vmthread->active_handles() == NULL) { 3765 Notify_lock->wait(); 3766 } 3767 } 3768 } 3769 3770 assert(Universe::is_fully_initialized(), "not initialized"); 3771 if (VerifyDuringStartup) { 3772 // Make sure we're starting with a clean slate. 3773 VM_Verify verify_op; 3774 VMThread::execute(&verify_op); 3775 } 3776 3777 // We need this to update the java.vm.info property in case any flags used 3778 // to initially define it have been changed. This is needed for both CDS and 3779 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3780 // is initially computed. See VM_Version::vm_info_string(). 3781 // This update must happen before we initialize the java classes, but 3782 // after any initialization logic that might modify the flags. 3783 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3784 3785 Thread* THREAD = Thread::current(); 3786 3787 // Always call even when there are not JVMTI environments yet, since environments 3788 // may be attached late and JVMTI must track phases of VM execution 3789 JvmtiExport::enter_early_start_phase(); 3790 3791 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3792 JvmtiExport::post_early_vm_start(); 3793 3794 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3795 3796 quicken_jni_functions(); 3797 3798 // No more stub generation allowed after that point. 3799 StubCodeDesc::freeze(); 3800 3801 // Set flag that basic initialization has completed. Used by exceptions and various 3802 // debug stuff, that does not work until all basic classes have been initialized. 3803 set_init_completed(); 3804 3805 LogConfiguration::post_initialize(); 3806 Metaspace::post_initialize(); 3807 3808 HOTSPOT_VM_INIT_END(); 3809 3810 // record VM initialization completion time 3811 #if INCLUDE_MANAGEMENT 3812 Management::record_vm_init_completed(); 3813 #endif // INCLUDE_MANAGEMENT 3814 3815 // Signal Dispatcher needs to be started before VMInit event is posted 3816 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3817 3818 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3819 if (!DisableAttachMechanism) { 3820 AttachListener::vm_start(); 3821 if (StartAttachListener || AttachListener::init_at_startup()) { 3822 AttachListener::init(); 3823 } 3824 } 3825 3826 // Launch -Xrun agents 3827 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3828 // back-end can launch with -Xdebug -Xrunjdwp. 3829 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3830 create_vm_init_libraries(); 3831 } 3832 3833 if (CleanChunkPoolAsync) { 3834 Chunk::start_chunk_pool_cleaner_task(); 3835 } 3836 3837 // initialize compiler(s) 3838 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3839 #if INCLUDE_JVMCI 3840 bool force_JVMCI_intialization = false; 3841 if (EnableJVMCI) { 3842 // Initialize JVMCI eagerly when it is explicitly requested. 3843 // Or when JVMCIPrintProperties is enabled. 3844 // The JVMCI Java initialization code will read this flag and 3845 // do the printing if it's set. 3846 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3847 3848 if (!force_JVMCI_intialization) { 3849 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3850 // compilations via JVMCI will not actually block until JVMCI is initialized. 3851 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3852 } 3853 } 3854 #endif 3855 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3856 // Postpone completion of compiler initialization to after JVMCI 3857 // is initialized to avoid timeouts of blocking compilations. 3858 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3859 CompileBroker::compilation_init_phase2(); 3860 } 3861 #endif 3862 3863 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3864 // It is done after compilers are initialized, because otherwise compilations of 3865 // signature polymorphic MH intrinsics can be missed 3866 // (see SystemDictionary::find_method_handle_intrinsic). 3867 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3868 3869 // This will initialize the module system. Only java.base classes can be 3870 // loaded until phase 2 completes 3871 call_initPhase2(CHECK_JNI_ERR); 3872 3873 // Always call even when there are not JVMTI environments yet, since environments 3874 // may be attached late and JVMTI must track phases of VM execution 3875 JvmtiExport::enter_start_phase(); 3876 3877 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3878 JvmtiExport::post_vm_start(); 3879 3880 // Final system initialization including security manager and system class loader 3881 call_initPhase3(CHECK_JNI_ERR); 3882 3883 // cache the system and platform class loaders 3884 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3885 3886 #if INCLUDE_CDS 3887 if (DumpSharedSpaces) { 3888 // capture the module path info from the ModuleEntryTable 3889 ClassLoader::initialize_module_path(THREAD); 3890 } 3891 #endif 3892 3893 #if INCLUDE_JVMCI 3894 if (force_JVMCI_intialization) { 3895 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3896 CompileBroker::compilation_init_phase2(); 3897 } 3898 #endif 3899 3900 // Always call even when there are not JVMTI environments yet, since environments 3901 // may be attached late and JVMTI must track phases of VM execution 3902 JvmtiExport::enter_live_phase(); 3903 3904 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3905 JvmtiExport::post_vm_initialized(); 3906 3907 JFR_ONLY(Jfr::on_vm_start();) 3908 3909 #if INCLUDE_MANAGEMENT 3910 Management::initialize(THREAD); 3911 3912 if (HAS_PENDING_EXCEPTION) { 3913 // management agent fails to start possibly due to 3914 // configuration problem and is responsible for printing 3915 // stack trace if appropriate. Simply exit VM. 3916 vm_exit(1); 3917 } 3918 #endif // INCLUDE_MANAGEMENT 3919 3920 if (MemProfiling) MemProfiler::engage(); 3921 StatSampler::engage(); 3922 if (CheckJNICalls) JniPeriodicChecker::engage(); 3923 3924 BiasedLocking::init(); 3925 3926 #if INCLUDE_RTM_OPT 3927 RTMLockingCounters::init(); 3928 #endif 3929 3930 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3931 call_postVMInitHook(THREAD); 3932 // The Java side of PostVMInitHook.run must deal with all 3933 // exceptions and provide means of diagnosis. 3934 if (HAS_PENDING_EXCEPTION) { 3935 CLEAR_PENDING_EXCEPTION; 3936 } 3937 } 3938 3939 { 3940 MutexLocker ml(PeriodicTask_lock); 3941 // Make sure the WatcherThread can be started by WatcherThread::start() 3942 // or by dynamic enrollment. 3943 WatcherThread::make_startable(); 3944 // Start up the WatcherThread if there are any periodic tasks 3945 // NOTE: All PeriodicTasks should be registered by now. If they 3946 // aren't, late joiners might appear to start slowly (we might 3947 // take a while to process their first tick). 3948 if (PeriodicTask::num_tasks() > 0) { 3949 WatcherThread::start(); 3950 } 3951 } 3952 3953 create_vm_timer.end(); 3954 #ifdef ASSERT 3955 _vm_complete = true; 3956 #endif 3957 3958 if (DumpSharedSpaces) { 3959 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3960 ShouldNotReachHere(); 3961 } 3962 3963 return JNI_OK; 3964 } 3965 3966 // type for the Agent_OnLoad and JVM_OnLoad entry points 3967 extern "C" { 3968 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3969 } 3970 // Find a command line agent library and return its entry point for 3971 // -agentlib: -agentpath: -Xrun 3972 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3973 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3974 const char *on_load_symbols[], 3975 size_t num_symbol_entries) { 3976 OnLoadEntry_t on_load_entry = NULL; 3977 void *library = NULL; 3978 3979 if (!agent->valid()) { 3980 char buffer[JVM_MAXPATHLEN]; 3981 char ebuf[1024] = ""; 3982 const char *name = agent->name(); 3983 const char *msg = "Could not find agent library "; 3984 3985 // First check to see if agent is statically linked into executable 3986 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3987 library = agent->os_lib(); 3988 } else if (agent->is_absolute_path()) { 3989 library = os::dll_load(name, ebuf, sizeof ebuf); 3990 if (library == NULL) { 3991 const char *sub_msg = " in absolute path, with error: "; 3992 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3993 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3994 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3995 // If we can't find the agent, exit. 3996 vm_exit_during_initialization(buf, NULL); 3997 FREE_C_HEAP_ARRAY(char, buf); 3998 } 3999 } else { 4000 // Try to load the agent from the standard dll directory 4001 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4002 name)) { 4003 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4004 } 4005 if (library == NULL) { // Try the library path directory. 4006 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4007 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4008 } 4009 if (library == NULL) { 4010 const char *sub_msg = " on the library path, with error: "; 4011 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4012 4013 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4014 strlen(ebuf) + strlen(sub_msg2) + 1; 4015 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4016 if (!agent->is_instrument_lib()) { 4017 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4018 } else { 4019 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4020 } 4021 // If we can't find the agent, exit. 4022 vm_exit_during_initialization(buf, NULL); 4023 FREE_C_HEAP_ARRAY(char, buf); 4024 } 4025 } 4026 } 4027 agent->set_os_lib(library); 4028 agent->set_valid(); 4029 } 4030 4031 // Find the OnLoad function. 4032 on_load_entry = 4033 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4034 false, 4035 on_load_symbols, 4036 num_symbol_entries)); 4037 return on_load_entry; 4038 } 4039 4040 // Find the JVM_OnLoad entry point 4041 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4042 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4043 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4044 } 4045 4046 // Find the Agent_OnLoad entry point 4047 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4048 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4049 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4050 } 4051 4052 // For backwards compatibility with -Xrun 4053 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4054 // treated like -agentpath: 4055 // Must be called before agent libraries are created 4056 void Threads::convert_vm_init_libraries_to_agents() { 4057 AgentLibrary* agent; 4058 AgentLibrary* next; 4059 4060 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4061 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4062 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4063 4064 // If there is an JVM_OnLoad function it will get called later, 4065 // otherwise see if there is an Agent_OnLoad 4066 if (on_load_entry == NULL) { 4067 on_load_entry = lookup_agent_on_load(agent); 4068 if (on_load_entry != NULL) { 4069 // switch it to the agent list -- so that Agent_OnLoad will be called, 4070 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4071 Arguments::convert_library_to_agent(agent); 4072 } else { 4073 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4074 } 4075 } 4076 } 4077 } 4078 4079 // Create agents for -agentlib: -agentpath: and converted -Xrun 4080 // Invokes Agent_OnLoad 4081 // Called very early -- before JavaThreads exist 4082 void Threads::create_vm_init_agents() { 4083 extern struct JavaVM_ main_vm; 4084 AgentLibrary* agent; 4085 4086 JvmtiExport::enter_onload_phase(); 4087 4088 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4089 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4090 4091 if (on_load_entry != NULL) { 4092 // Invoke the Agent_OnLoad function 4093 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4094 if (err != JNI_OK) { 4095 vm_exit_during_initialization("agent library failed to init", agent->name()); 4096 } 4097 } else { 4098 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4099 } 4100 } 4101 JvmtiExport::enter_primordial_phase(); 4102 } 4103 4104 extern "C" { 4105 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4106 } 4107 4108 void Threads::shutdown_vm_agents() { 4109 // Send any Agent_OnUnload notifications 4110 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4111 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4112 extern struct JavaVM_ main_vm; 4113 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4114 4115 // Find the Agent_OnUnload function. 4116 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4117 os::find_agent_function(agent, 4118 false, 4119 on_unload_symbols, 4120 num_symbol_entries)); 4121 4122 // Invoke the Agent_OnUnload function 4123 if (unload_entry != NULL) { 4124 JavaThread* thread = JavaThread::current(); 4125 ThreadToNativeFromVM ttn(thread); 4126 HandleMark hm(thread); 4127 (*unload_entry)(&main_vm); 4128 } 4129 } 4130 } 4131 4132 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4133 // Invokes JVM_OnLoad 4134 void Threads::create_vm_init_libraries() { 4135 extern struct JavaVM_ main_vm; 4136 AgentLibrary* agent; 4137 4138 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4139 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4140 4141 if (on_load_entry != NULL) { 4142 // Invoke the JVM_OnLoad function 4143 JavaThread* thread = JavaThread::current(); 4144 ThreadToNativeFromVM ttn(thread); 4145 HandleMark hm(thread); 4146 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4147 if (err != JNI_OK) { 4148 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4149 } 4150 } else { 4151 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4152 } 4153 } 4154 } 4155 4156 4157 // Last thread running calls java.lang.Shutdown.shutdown() 4158 void JavaThread::invoke_shutdown_hooks() { 4159 HandleMark hm(this); 4160 4161 // We could get here with a pending exception, if so clear it now. 4162 if (this->has_pending_exception()) { 4163 this->clear_pending_exception(); 4164 } 4165 4166 EXCEPTION_MARK; 4167 Klass* shutdown_klass = 4168 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4169 THREAD); 4170 if (shutdown_klass != NULL) { 4171 // SystemDictionary::resolve_or_null will return null if there was 4172 // an exception. If we cannot load the Shutdown class, just don't 4173 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4174 // won't be run. Note that if a shutdown hook was registered, 4175 // the Shutdown class would have already been loaded 4176 // (Runtime.addShutdownHook will load it). 4177 JavaValue result(T_VOID); 4178 JavaCalls::call_static(&result, 4179 shutdown_klass, 4180 vmSymbols::shutdown_method_name(), 4181 vmSymbols::void_method_signature(), 4182 THREAD); 4183 } 4184 CLEAR_PENDING_EXCEPTION; 4185 } 4186 4187 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4188 // the program falls off the end of main(). Another VM exit path is through 4189 // vm_exit() when the program calls System.exit() to return a value or when 4190 // there is a serious error in VM. The two shutdown paths are not exactly 4191 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4192 // and VM_Exit op at VM level. 4193 // 4194 // Shutdown sequence: 4195 // + Shutdown native memory tracking if it is on 4196 // + Wait until we are the last non-daemon thread to execute 4197 // <-- every thing is still working at this moment --> 4198 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4199 // shutdown hooks 4200 // + Call before_exit(), prepare for VM exit 4201 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4202 // currently the only user of this mechanism is File.deleteOnExit()) 4203 // > stop StatSampler, watcher thread, CMS threads, 4204 // post thread end and vm death events to JVMTI, 4205 // stop signal thread 4206 // + Call JavaThread::exit(), it will: 4207 // > release JNI handle blocks, remove stack guard pages 4208 // > remove this thread from Threads list 4209 // <-- no more Java code from this thread after this point --> 4210 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4211 // the compiler threads at safepoint 4212 // <-- do not use anything that could get blocked by Safepoint --> 4213 // + Disable tracing at JNI/JVM barriers 4214 // + Set _vm_exited flag for threads that are still running native code 4215 // + Call exit_globals() 4216 // > deletes tty 4217 // > deletes PerfMemory resources 4218 // + Delete this thread 4219 // + Return to caller 4220 4221 bool Threads::destroy_vm() { 4222 JavaThread* thread = JavaThread::current(); 4223 4224 #ifdef ASSERT 4225 _vm_complete = false; 4226 #endif 4227 // Wait until we are the last non-daemon thread to execute 4228 { MutexLocker nu(Threads_lock); 4229 while (Threads::number_of_non_daemon_threads() > 1) 4230 // This wait should make safepoint checks, wait without a timeout, 4231 // and wait as a suspend-equivalent condition. 4232 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4233 Mutex::_as_suspend_equivalent_flag); 4234 } 4235 4236 EventShutdown e; 4237 if (e.should_commit()) { 4238 e.set_reason("No remaining non-daemon Java threads"); 4239 e.commit(); 4240 } 4241 4242 // Hang forever on exit if we are reporting an error. 4243 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4244 os::infinite_sleep(); 4245 } 4246 os::wait_for_keypress_at_exit(); 4247 4248 // run Java level shutdown hooks 4249 thread->invoke_shutdown_hooks(); 4250 4251 before_exit(thread); 4252 4253 thread->exit(true); 4254 // thread will never call smr_delete, instead of implicit cancel 4255 // in wait_for_vm_thread_exit we do it explicit. 4256 thread->cancel_handshake(); 4257 4258 // Stop VM thread. 4259 { 4260 // 4945125 The vm thread comes to a safepoint during exit. 4261 // GC vm_operations can get caught at the safepoint, and the 4262 // heap is unparseable if they are caught. Grab the Heap_lock 4263 // to prevent this. The GC vm_operations will not be able to 4264 // queue until after the vm thread is dead. After this point, 4265 // we'll never emerge out of the safepoint before the VM exits. 4266 4267 MutexLocker ml(Heap_lock); 4268 4269 VMThread::wait_for_vm_thread_exit(); 4270 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4271 VMThread::destroy(); 4272 } 4273 4274 // Now, all Java threads are gone except daemon threads. Daemon threads 4275 // running Java code or in VM are stopped by the Safepoint. However, 4276 // daemon threads executing native code are still running. But they 4277 // will be stopped at native=>Java/VM barriers. Note that we can't 4278 // simply kill or suspend them, as it is inherently deadlock-prone. 4279 4280 VM_Exit::set_vm_exited(); 4281 4282 // Clean up ideal graph printers after the VMThread has started 4283 // the final safepoint which will block all the Compiler threads. 4284 // Note that this Thread has already logically exited so the 4285 // clean_up() function's use of a JavaThreadIteratorWithHandle 4286 // would be a problem except set_vm_exited() has remembered the 4287 // shutdown thread which is granted a policy exception. 4288 #if defined(COMPILER2) && !defined(PRODUCT) 4289 IdealGraphPrinter::clean_up(); 4290 #endif 4291 4292 notify_vm_shutdown(); 4293 4294 // exit_globals() will delete tty 4295 exit_globals(); 4296 4297 // We are after VM_Exit::set_vm_exited() so we can't call 4298 // thread->smr_delete() or we will block on the Threads_lock. 4299 // Deleting the shutdown thread here is safe because another 4300 // JavaThread cannot have an active ThreadsListHandle for 4301 // this JavaThread. 4302 delete thread; 4303 4304 #if INCLUDE_JVMCI 4305 if (JVMCICounterSize > 0) { 4306 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4307 } 4308 #endif 4309 4310 LogConfiguration::finalize(); 4311 4312 return true; 4313 } 4314 4315 4316 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4317 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4318 return is_supported_jni_version(version); 4319 } 4320 4321 4322 jboolean Threads::is_supported_jni_version(jint version) { 4323 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4324 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4325 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4326 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4327 if (version == JNI_VERSION_9) return JNI_TRUE; 4328 if (version == JNI_VERSION_10) return JNI_TRUE; 4329 return JNI_FALSE; 4330 } 4331 4332 4333 void Threads::add(JavaThread* p, bool force_daemon) { 4334 // The threads lock must be owned at this point 4335 assert_locked_or_safepoint(Threads_lock); 4336 4337 BarrierSet::barrier_set()->on_thread_attach(p); 4338 4339 p->set_next(_thread_list); 4340 _thread_list = p; 4341 4342 // Once a JavaThread is added to the Threads list, smr_delete() has 4343 // to be used to delete it. Otherwise we can just delete it directly. 4344 p->set_on_thread_list(); 4345 4346 _number_of_threads++; 4347 oop threadObj = p->threadObj(); 4348 bool daemon = true; 4349 // Bootstrapping problem: threadObj can be null for initial 4350 // JavaThread (or for threads attached via JNI) 4351 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4352 _number_of_non_daemon_threads++; 4353 daemon = false; 4354 } 4355 4356 ThreadService::add_thread(p, daemon); 4357 4358 // Maintain fast thread list 4359 ThreadsSMRSupport::add_thread(p); 4360 4361 // Possible GC point. 4362 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4363 } 4364 4365 void Threads::remove(JavaThread* p) { 4366 4367 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4368 ObjectSynchronizer::omFlush(p); 4369 4370 // Extra scope needed for Thread_lock, so we can check 4371 // that we do not remove thread without safepoint code notice 4372 { MutexLocker ml(Threads_lock); 4373 4374 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4375 4376 // Maintain fast thread list 4377 ThreadsSMRSupport::remove_thread(p); 4378 4379 JavaThread* current = _thread_list; 4380 JavaThread* prev = NULL; 4381 4382 while (current != p) { 4383 prev = current; 4384 current = current->next(); 4385 } 4386 4387 if (prev) { 4388 prev->set_next(current->next()); 4389 } else { 4390 _thread_list = p->next(); 4391 } 4392 4393 _number_of_threads--; 4394 oop threadObj = p->threadObj(); 4395 bool daemon = true; 4396 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4397 _number_of_non_daemon_threads--; 4398 daemon = false; 4399 4400 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4401 // on destroy_vm will wake up. 4402 if (number_of_non_daemon_threads() == 1) { 4403 Threads_lock->notify_all(); 4404 } 4405 } 4406 ThreadService::remove_thread(p, daemon); 4407 4408 // Make sure that safepoint code disregard this thread. This is needed since 4409 // the thread might mess around with locks after this point. This can cause it 4410 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4411 // of this thread since it is removed from the queue. 4412 p->set_terminated_value(); 4413 } // unlock Threads_lock 4414 4415 // Since Events::log uses a lock, we grab it outside the Threads_lock 4416 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4417 } 4418 4419 // Operations on the Threads list for GC. These are not explicitly locked, 4420 // but the garbage collector must provide a safe context for them to run. 4421 // In particular, these things should never be called when the Threads_lock 4422 // is held by some other thread. (Note: the Safepoint abstraction also 4423 // uses the Threads_lock to guarantee this property. It also makes sure that 4424 // all threads gets blocked when exiting or starting). 4425 4426 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4427 ALL_JAVA_THREADS(p) { 4428 p->oops_do(f, cf); 4429 } 4430 VMThread::vm_thread()->oops_do(f, cf); 4431 } 4432 4433 void Threads::change_thread_claim_parity() { 4434 // Set the new claim parity. 4435 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4436 "Not in range."); 4437 _thread_claim_parity++; 4438 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4439 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4440 "Not in range."); 4441 } 4442 4443 #ifdef ASSERT 4444 void Threads::assert_all_threads_claimed() { 4445 ALL_JAVA_THREADS(p) { 4446 const int thread_parity = p->oops_do_parity(); 4447 assert((thread_parity == _thread_claim_parity), 4448 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4449 } 4450 VMThread* vmt = VMThread::vm_thread(); 4451 const int thread_parity = vmt->oops_do_parity(); 4452 assert((thread_parity == _thread_claim_parity), 4453 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4454 } 4455 #endif // ASSERT 4456 4457 class ParallelOopsDoThreadClosure : public ThreadClosure { 4458 private: 4459 OopClosure* _f; 4460 CodeBlobClosure* _cf; 4461 public: 4462 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4463 void do_thread(Thread* t) { 4464 t->oops_do(_f, _cf); 4465 } 4466 }; 4467 4468 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4469 ParallelOopsDoThreadClosure tc(f, cf); 4470 possibly_parallel_threads_do(is_par, &tc); 4471 } 4472 4473 void Threads::nmethods_do(CodeBlobClosure* cf) { 4474 ALL_JAVA_THREADS(p) { 4475 // This is used by the code cache sweeper to mark nmethods that are active 4476 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4477 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4478 if(!p->is_Code_cache_sweeper_thread()) { 4479 p->nmethods_do(cf); 4480 } 4481 } 4482 } 4483 4484 void Threads::metadata_do(void f(Metadata*)) { 4485 ALL_JAVA_THREADS(p) { 4486 p->metadata_do(f); 4487 } 4488 } 4489 4490 class ThreadHandlesClosure : public ThreadClosure { 4491 void (*_f)(Metadata*); 4492 public: 4493 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4494 virtual void do_thread(Thread* thread) { 4495 thread->metadata_handles_do(_f); 4496 } 4497 }; 4498 4499 void Threads::metadata_handles_do(void f(Metadata*)) { 4500 // Only walk the Handles in Thread. 4501 ThreadHandlesClosure handles_closure(f); 4502 threads_do(&handles_closure); 4503 } 4504 4505 void Threads::deoptimized_wrt_marked_nmethods() { 4506 ALL_JAVA_THREADS(p) { 4507 p->deoptimized_wrt_marked_nmethods(); 4508 } 4509 } 4510 4511 4512 // Get count Java threads that are waiting to enter the specified monitor. 4513 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4514 int count, 4515 address monitor) { 4516 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4517 4518 int i = 0; 4519 DO_JAVA_THREADS(t_list, p) { 4520 if (!p->can_call_java()) continue; 4521 4522 address pending = (address)p->current_pending_monitor(); 4523 if (pending == monitor) { // found a match 4524 if (i < count) result->append(p); // save the first count matches 4525 i++; 4526 } 4527 } 4528 4529 return result; 4530 } 4531 4532 4533 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4534 address owner) { 4535 // NULL owner means not locked so we can skip the search 4536 if (owner == NULL) return NULL; 4537 4538 DO_JAVA_THREADS(t_list, p) { 4539 // first, see if owner is the address of a Java thread 4540 if (owner == (address)p) return p; 4541 } 4542 4543 // Cannot assert on lack of success here since this function may be 4544 // used by code that is trying to report useful problem information 4545 // like deadlock detection. 4546 if (UseHeavyMonitors) return NULL; 4547 4548 // If we didn't find a matching Java thread and we didn't force use of 4549 // heavyweight monitors, then the owner is the stack address of the 4550 // Lock Word in the owning Java thread's stack. 4551 // 4552 JavaThread* the_owner = NULL; 4553 DO_JAVA_THREADS(t_list, q) { 4554 if (q->is_lock_owned(owner)) { 4555 the_owner = q; 4556 break; 4557 } 4558 } 4559 4560 // cannot assert on lack of success here; see above comment 4561 return the_owner; 4562 } 4563 4564 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4565 void Threads::print_on(outputStream* st, bool print_stacks, 4566 bool internal_format, bool print_concurrent_locks, 4567 bool print_extended_info) { 4568 char buf[32]; 4569 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4570 4571 st->print_cr("Full thread dump %s (%s %s):", 4572 VM_Version::vm_name(), 4573 VM_Version::vm_release(), 4574 VM_Version::vm_info_string()); 4575 st->cr(); 4576 4577 #if INCLUDE_SERVICES 4578 // Dump concurrent locks 4579 ConcurrentLocksDump concurrent_locks; 4580 if (print_concurrent_locks) { 4581 concurrent_locks.dump_at_safepoint(); 4582 } 4583 #endif // INCLUDE_SERVICES 4584 4585 ThreadsSMRSupport::print_info_on(st); 4586 st->cr(); 4587 4588 ALL_JAVA_THREADS(p) { 4589 ResourceMark rm; 4590 p->print_on(st, print_extended_info); 4591 if (print_stacks) { 4592 if (internal_format) { 4593 p->trace_stack(); 4594 } else { 4595 p->print_stack_on(st); 4596 } 4597 } 4598 st->cr(); 4599 #if INCLUDE_SERVICES 4600 if (print_concurrent_locks) { 4601 concurrent_locks.print_locks_on(p, st); 4602 } 4603 #endif // INCLUDE_SERVICES 4604 } 4605 4606 VMThread::vm_thread()->print_on(st); 4607 st->cr(); 4608 Universe::heap()->print_gc_threads_on(st); 4609 WatcherThread* wt = WatcherThread::watcher_thread(); 4610 if (wt != NULL) { 4611 wt->print_on(st); 4612 st->cr(); 4613 } 4614 4615 st->flush(); 4616 } 4617 4618 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4619 int buflen, bool* found_current) { 4620 if (this_thread != NULL) { 4621 bool is_current = (current == this_thread); 4622 *found_current = *found_current || is_current; 4623 st->print("%s", is_current ? "=>" : " "); 4624 4625 st->print(PTR_FORMAT, p2i(this_thread)); 4626 st->print(" "); 4627 this_thread->print_on_error(st, buf, buflen); 4628 st->cr(); 4629 } 4630 } 4631 4632 class PrintOnErrorClosure : public ThreadClosure { 4633 outputStream* _st; 4634 Thread* _current; 4635 char* _buf; 4636 int _buflen; 4637 bool* _found_current; 4638 public: 4639 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4640 int buflen, bool* found_current) : 4641 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4642 4643 virtual void do_thread(Thread* thread) { 4644 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4645 } 4646 }; 4647 4648 // Threads::print_on_error() is called by fatal error handler. It's possible 4649 // that VM is not at safepoint and/or current thread is inside signal handler. 4650 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4651 // memory (even in resource area), it might deadlock the error handler. 4652 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4653 int buflen) { 4654 ThreadsSMRSupport::print_info_on(st); 4655 st->cr(); 4656 4657 bool found_current = false; 4658 st->print_cr("Java Threads: ( => current thread )"); 4659 ALL_JAVA_THREADS(thread) { 4660 print_on_error(thread, st, current, buf, buflen, &found_current); 4661 } 4662 st->cr(); 4663 4664 st->print_cr("Other Threads:"); 4665 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4666 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4667 4668 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4669 Universe::heap()->gc_threads_do(&print_closure); 4670 4671 if (!found_current) { 4672 st->cr(); 4673 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4674 current->print_on_error(st, buf, buflen); 4675 st->cr(); 4676 } 4677 st->cr(); 4678 4679 st->print_cr("Threads with active compile tasks:"); 4680 print_threads_compiling(st, buf, buflen); 4681 } 4682 4683 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4684 ALL_JAVA_THREADS(thread) { 4685 if (thread->is_Compiler_thread()) { 4686 CompilerThread* ct = (CompilerThread*) thread; 4687 4688 // Keep task in local variable for NULL check. 4689 // ct->_task might be set to NULL by concurring compiler thread 4690 // because it completed the compilation. The task is never freed, 4691 // though, just returned to a free list. 4692 CompileTask* task = ct->task(); 4693 if (task != NULL) { 4694 thread->print_name_on_error(st, buf, buflen); 4695 task->print(st, NULL, true, true); 4696 } 4697 } 4698 } 4699 } 4700 4701 4702 // Internal SpinLock and Mutex 4703 // Based on ParkEvent 4704 4705 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4706 // 4707 // We employ SpinLocks _only for low-contention, fixed-length 4708 // short-duration critical sections where we're concerned 4709 // about native mutex_t or HotSpot Mutex:: latency. 4710 // The mux construct provides a spin-then-block mutual exclusion 4711 // mechanism. 4712 // 4713 // Testing has shown that contention on the ListLock guarding gFreeList 4714 // is common. If we implement ListLock as a simple SpinLock it's common 4715 // for the JVM to devolve to yielding with little progress. This is true 4716 // despite the fact that the critical sections protected by ListLock are 4717 // extremely short. 4718 // 4719 // TODO-FIXME: ListLock should be of type SpinLock. 4720 // We should make this a 1st-class type, integrated into the lock 4721 // hierarchy as leaf-locks. Critically, the SpinLock structure 4722 // should have sufficient padding to avoid false-sharing and excessive 4723 // cache-coherency traffic. 4724 4725 4726 typedef volatile int SpinLockT; 4727 4728 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4729 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4730 return; // normal fast-path return 4731 } 4732 4733 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4734 int ctr = 0; 4735 int Yields = 0; 4736 for (;;) { 4737 while (*adr != 0) { 4738 ++ctr; 4739 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4740 if (Yields > 5) { 4741 os::naked_short_sleep(1); 4742 } else { 4743 os::naked_yield(); 4744 ++Yields; 4745 } 4746 } else { 4747 SpinPause(); 4748 } 4749 } 4750 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4751 } 4752 } 4753 4754 void Thread::SpinRelease(volatile int * adr) { 4755 assert(*adr != 0, "invariant"); 4756 OrderAccess::fence(); // guarantee at least release consistency. 4757 // Roach-motel semantics. 4758 // It's safe if subsequent LDs and STs float "up" into the critical section, 4759 // but prior LDs and STs within the critical section can't be allowed 4760 // to reorder or float past the ST that releases the lock. 4761 // Loads and stores in the critical section - which appear in program 4762 // order before the store that releases the lock - must also appear 4763 // before the store that releases the lock in memory visibility order. 4764 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4765 // the ST of 0 into the lock-word which releases the lock, so fence 4766 // more than covers this on all platforms. 4767 *adr = 0; 4768 } 4769 4770 // muxAcquire and muxRelease: 4771 // 4772 // * muxAcquire and muxRelease support a single-word lock-word construct. 4773 // The LSB of the word is set IFF the lock is held. 4774 // The remainder of the word points to the head of a singly-linked list 4775 // of threads blocked on the lock. 4776 // 4777 // * The current implementation of muxAcquire-muxRelease uses its own 4778 // dedicated Thread._MuxEvent instance. If we're interested in 4779 // minimizing the peak number of extant ParkEvent instances then 4780 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4781 // as certain invariants were satisfied. Specifically, care would need 4782 // to be taken with regards to consuming unpark() "permits". 4783 // A safe rule of thumb is that a thread would never call muxAcquire() 4784 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4785 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4786 // consume an unpark() permit intended for monitorenter, for instance. 4787 // One way around this would be to widen the restricted-range semaphore 4788 // implemented in park(). Another alternative would be to provide 4789 // multiple instances of the PlatformEvent() for each thread. One 4790 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4791 // 4792 // * Usage: 4793 // -- Only as leaf locks 4794 // -- for short-term locking only as muxAcquire does not perform 4795 // thread state transitions. 4796 // 4797 // Alternatives: 4798 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4799 // but with parking or spin-then-park instead of pure spinning. 4800 // * Use Taura-Oyama-Yonenzawa locks. 4801 // * It's possible to construct a 1-0 lock if we encode the lockword as 4802 // (List,LockByte). Acquire will CAS the full lockword while Release 4803 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4804 // acquiring threads use timers (ParkTimed) to detect and recover from 4805 // the stranding window. Thread/Node structures must be aligned on 256-byte 4806 // boundaries by using placement-new. 4807 // * Augment MCS with advisory back-link fields maintained with CAS(). 4808 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4809 // The validity of the backlinks must be ratified before we trust the value. 4810 // If the backlinks are invalid the exiting thread must back-track through the 4811 // the forward links, which are always trustworthy. 4812 // * Add a successor indication. The LockWord is currently encoded as 4813 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4814 // to provide the usual futile-wakeup optimization. 4815 // See RTStt for details. 4816 // 4817 4818 4819 const intptr_t LOCKBIT = 1; 4820 4821 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4822 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4823 if (w == 0) return; 4824 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4825 return; 4826 } 4827 4828 ParkEvent * const Self = Thread::current()->_MuxEvent; 4829 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4830 for (;;) { 4831 int its = (os::is_MP() ? 100 : 0) + 1; 4832 4833 // Optional spin phase: spin-then-park strategy 4834 while (--its >= 0) { 4835 w = *Lock; 4836 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4837 return; 4838 } 4839 } 4840 4841 Self->reset(); 4842 Self->OnList = intptr_t(Lock); 4843 // The following fence() isn't _strictly necessary as the subsequent 4844 // CAS() both serializes execution and ratifies the fetched *Lock value. 4845 OrderAccess::fence(); 4846 for (;;) { 4847 w = *Lock; 4848 if ((w & LOCKBIT) == 0) { 4849 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4850 Self->OnList = 0; // hygiene - allows stronger asserts 4851 return; 4852 } 4853 continue; // Interference -- *Lock changed -- Just retry 4854 } 4855 assert(w & LOCKBIT, "invariant"); 4856 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4857 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4858 } 4859 4860 while (Self->OnList != 0) { 4861 Self->park(); 4862 } 4863 } 4864 } 4865 4866 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4867 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4868 if (w == 0) return; 4869 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4870 return; 4871 } 4872 4873 ParkEvent * ReleaseAfter = NULL; 4874 if (ev == NULL) { 4875 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4876 } 4877 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4878 for (;;) { 4879 guarantee(ev->OnList == 0, "invariant"); 4880 int its = (os::is_MP() ? 100 : 0) + 1; 4881 4882 // Optional spin phase: spin-then-park strategy 4883 while (--its >= 0) { 4884 w = *Lock; 4885 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4886 if (ReleaseAfter != NULL) { 4887 ParkEvent::Release(ReleaseAfter); 4888 } 4889 return; 4890 } 4891 } 4892 4893 ev->reset(); 4894 ev->OnList = intptr_t(Lock); 4895 // The following fence() isn't _strictly necessary as the subsequent 4896 // CAS() both serializes execution and ratifies the fetched *Lock value. 4897 OrderAccess::fence(); 4898 for (;;) { 4899 w = *Lock; 4900 if ((w & LOCKBIT) == 0) { 4901 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4902 ev->OnList = 0; 4903 // We call ::Release while holding the outer lock, thus 4904 // artificially lengthening the critical section. 4905 // Consider deferring the ::Release() until the subsequent unlock(), 4906 // after we've dropped the outer lock. 4907 if (ReleaseAfter != NULL) { 4908 ParkEvent::Release(ReleaseAfter); 4909 } 4910 return; 4911 } 4912 continue; // Interference -- *Lock changed -- Just retry 4913 } 4914 assert(w & LOCKBIT, "invariant"); 4915 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4916 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4917 } 4918 4919 while (ev->OnList != 0) { 4920 ev->park(); 4921 } 4922 } 4923 } 4924 4925 // Release() must extract a successor from the list and then wake that thread. 4926 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4927 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4928 // Release() would : 4929 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4930 // (B) Extract a successor from the private list "in-hand" 4931 // (C) attempt to CAS() the residual back into *Lock over null. 4932 // If there were any newly arrived threads and the CAS() would fail. 4933 // In that case Release() would detach the RATs, re-merge the list in-hand 4934 // with the RATs and repeat as needed. Alternately, Release() might 4935 // detach and extract a successor, but then pass the residual list to the wakee. 4936 // The wakee would be responsible for reattaching and remerging before it 4937 // competed for the lock. 4938 // 4939 // Both "pop" and DMR are immune from ABA corruption -- there can be 4940 // multiple concurrent pushers, but only one popper or detacher. 4941 // This implementation pops from the head of the list. This is unfair, 4942 // but tends to provide excellent throughput as hot threads remain hot. 4943 // (We wake recently run threads first). 4944 // 4945 // All paths through muxRelease() will execute a CAS. 4946 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4947 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4948 // executed within the critical section are complete and globally visible before the 4949 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4950 void Thread::muxRelease(volatile intptr_t * Lock) { 4951 for (;;) { 4952 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4953 assert(w & LOCKBIT, "invariant"); 4954 if (w == LOCKBIT) return; 4955 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4956 assert(List != NULL, "invariant"); 4957 assert(List->OnList == intptr_t(Lock), "invariant"); 4958 ParkEvent * const nxt = List->ListNext; 4959 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4960 4961 // The following CAS() releases the lock and pops the head element. 4962 // The CAS() also ratifies the previously fetched lock-word value. 4963 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4964 continue; 4965 } 4966 List->OnList = 0; 4967 OrderAccess::fence(); 4968 List->unpark(); 4969 return; 4970 } 4971 } 4972 4973 4974 void Threads::verify() { 4975 ALL_JAVA_THREADS(p) { 4976 p->verify(); 4977 } 4978 VMThread* thread = VMThread::vm_thread(); 4979 if (thread != NULL) thread->verify(); 4980 }