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 MutexLocker ml(PeriodicTask_lock); 1318 1319 if (_should_terminate) { 1320 // check for termination before we do any housekeeping or wait 1321 return 0; // we did not sleep. 1322 } 1323 1324 // remaining will be zero if there are no tasks, 1325 // causing the WatcherThread to sleep until a task is 1326 // enrolled 1327 int remaining = PeriodicTask::time_to_wait(); 1328 int time_slept = 0; 1329 1330 // we expect this to timeout - we only ever get unparked when 1331 // we should terminate or when a new task has been enrolled 1332 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1333 1334 jlong time_before_loop = os::javaTimeNanos(); 1335 1336 while (true) { 1337 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1338 remaining); 1339 jlong now = os::javaTimeNanos(); 1340 1341 if (remaining == 0) { 1342 // if we didn't have any tasks we could have waited for a long time 1343 // consider the time_slept zero and reset time_before_loop 1344 time_slept = 0; 1345 time_before_loop = now; 1346 } else { 1347 // need to recalculate since we might have new tasks in _tasks 1348 time_slept = (int) ((now - time_before_loop) / 1000000); 1349 } 1350 1351 // Change to task list or spurious wakeup of some kind 1352 if (timedout || _should_terminate) { 1353 break; 1354 } 1355 1356 remaining = PeriodicTask::time_to_wait(); 1357 if (remaining == 0) { 1358 // Last task was just disenrolled so loop around and wait until 1359 // another task gets enrolled 1360 continue; 1361 } 1362 1363 remaining -= time_slept; 1364 if (remaining <= 0) { 1365 break; 1366 } 1367 } 1368 1369 return time_slept; 1370 } 1371 1372 void WatcherThread::run() { 1373 assert(this == watcher_thread(), "just checking"); 1374 1375 this->record_stack_base_and_size(); 1376 this->set_native_thread_name(this->name()); 1377 this->set_active_handles(JNIHandleBlock::allocate_block()); 1378 while (true) { 1379 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1380 assert(watcher_thread() == this, "thread consistency check"); 1381 1382 // Calculate how long it'll be until the next PeriodicTask work 1383 // should be done, and sleep that amount of time. 1384 int time_waited = sleep(); 1385 1386 if (VMError::is_error_reported()) { 1387 // A fatal error has happened, the error handler(VMError::report_and_die) 1388 // should abort JVM after creating an error log file. However in some 1389 // rare cases, the error handler itself might deadlock. Here periodically 1390 // check for error reporting timeouts, and if it happens, just proceed to 1391 // abort the VM. 1392 1393 // This code is in WatcherThread because WatcherThread wakes up 1394 // periodically so the fatal error handler doesn't need to do anything; 1395 // also because the WatcherThread is less likely to crash than other 1396 // threads. 1397 1398 for (;;) { 1399 // Note: we use naked sleep in this loop because we want to avoid using 1400 // any kind of VM infrastructure which may be broken at this point. 1401 if (VMError::check_timeout()) { 1402 // We hit error reporting timeout. Error reporting was interrupted and 1403 // will be wrapping things up now (closing files etc). Give it some more 1404 // time, then quit the VM. 1405 os::naked_short_sleep(200); 1406 // Print a message to stderr. 1407 fdStream err(defaultStream::output_fd()); 1408 err.print_raw_cr("# [ timer expired, abort... ]"); 1409 // skip atexit/vm_exit/vm_abort hooks 1410 os::die(); 1411 } 1412 1413 // Wait a second, then recheck for timeout. 1414 os::naked_short_sleep(999); 1415 } 1416 } 1417 1418 if (_should_terminate) { 1419 // check for termination before posting the next tick 1420 break; 1421 } 1422 1423 PeriodicTask::real_time_tick(time_waited); 1424 } 1425 1426 // Signal that it is terminated 1427 { 1428 MutexLocker mu(Terminator_lock); 1429 _watcher_thread = NULL; 1430 Terminator_lock->notify(); 1431 } 1432 } 1433 1434 void WatcherThread::start() { 1435 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1436 1437 if (watcher_thread() == NULL && _startable) { 1438 _should_terminate = false; 1439 // Create the single instance of WatcherThread 1440 new WatcherThread(); 1441 } 1442 } 1443 1444 void WatcherThread::make_startable() { 1445 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1446 _startable = true; 1447 } 1448 1449 void WatcherThread::stop() { 1450 { 1451 // Follow normal safepoint aware lock enter protocol since the 1452 // WatcherThread is stopped by another JavaThread. 1453 MutexLocker ml(PeriodicTask_lock); 1454 _should_terminate = true; 1455 1456 WatcherThread* watcher = watcher_thread(); 1457 if (watcher != NULL) { 1458 // unpark the WatcherThread so it can see that it should terminate 1459 watcher->unpark(); 1460 } 1461 } 1462 1463 MutexLocker mu(Terminator_lock); 1464 1465 while (watcher_thread() != NULL) { 1466 // This wait should make safepoint checks, wait without a timeout, 1467 // and wait as a suspend-equivalent condition. 1468 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1469 Mutex::_as_suspend_equivalent_flag); 1470 } 1471 } 1472 1473 void WatcherThread::unpark() { 1474 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1475 PeriodicTask_lock->notify(); 1476 } 1477 1478 void WatcherThread::print_on(outputStream* st) const { 1479 st->print("\"%s\" ", name()); 1480 Thread::print_on(st); 1481 st->cr(); 1482 } 1483 1484 // ======= JavaThread ======== 1485 1486 #if INCLUDE_JVMCI 1487 1488 jlong* JavaThread::_jvmci_old_thread_counters; 1489 1490 bool jvmci_counters_include(JavaThread* thread) { 1491 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1492 } 1493 1494 void JavaThread::collect_counters(typeArrayOop array) { 1495 if (JVMCICounterSize > 0) { 1496 JavaThreadIteratorWithHandle jtiwh; 1497 for (int i = 0; i < array->length(); i++) { 1498 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1499 } 1500 for (; JavaThread *tp = jtiwh.next(); ) { 1501 if (jvmci_counters_include(tp)) { 1502 for (int i = 0; i < array->length(); i++) { 1503 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1504 } 1505 } 1506 } 1507 } 1508 } 1509 1510 #endif // INCLUDE_JVMCI 1511 1512 // A JavaThread is a normal Java thread 1513 1514 void JavaThread::initialize() { 1515 // Initialize fields 1516 1517 set_saved_exception_pc(NULL); 1518 set_threadObj(NULL); 1519 _anchor.clear(); 1520 set_entry_point(NULL); 1521 set_jni_functions(jni_functions()); 1522 set_callee_target(NULL); 1523 set_vm_result(NULL); 1524 set_vm_result_2(NULL); 1525 set_vframe_array_head(NULL); 1526 set_vframe_array_last(NULL); 1527 set_deferred_locals(NULL); 1528 set_deopt_mark(NULL); 1529 set_deopt_compiled_method(NULL); 1530 clear_must_deopt_id(); 1531 set_monitor_chunks(NULL); 1532 set_next(NULL); 1533 _on_thread_list = false; 1534 set_thread_state(_thread_new); 1535 _terminated = _not_terminated; 1536 _privileged_stack_top = NULL; 1537 _array_for_gc = NULL; 1538 _suspend_equivalent = false; 1539 _in_deopt_handler = 0; 1540 _doing_unsafe_access = false; 1541 _stack_guard_state = stack_guard_unused; 1542 #if INCLUDE_JVMCI 1543 _pending_monitorenter = false; 1544 _pending_deoptimization = -1; 1545 _pending_failed_speculation = 0; 1546 _pending_transfer_to_interpreter = false; 1547 _adjusting_comp_level = false; 1548 _in_retryable_allocation = false; 1549 _jvmci._alternate_call_target = NULL; 1550 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1551 if (JVMCICounterSize > 0) { 1552 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1553 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1554 } else { 1555 _jvmci_counters = NULL; 1556 } 1557 #endif // INCLUDE_JVMCI 1558 _reserved_stack_activation = NULL; // stack base not known yet 1559 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1560 _exception_pc = 0; 1561 _exception_handler_pc = 0; 1562 _is_method_handle_return = 0; 1563 _jvmti_thread_state= NULL; 1564 _should_post_on_exceptions_flag = JNI_FALSE; 1565 _interp_only_mode = 0; 1566 _special_runtime_exit_condition = _no_async_condition; 1567 _pending_async_exception = NULL; 1568 _thread_stat = NULL; 1569 _thread_stat = new ThreadStatistics(); 1570 _blocked_on_compilation = false; 1571 _jni_active_critical = 0; 1572 _pending_jni_exception_check_fn = NULL; 1573 _do_not_unlock_if_synchronized = false; 1574 _cached_monitor_info = NULL; 1575 _parker = Parker::Allocate(this); 1576 1577 #ifndef PRODUCT 1578 _jmp_ring_index = 0; 1579 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1580 record_jump(NULL, NULL, NULL, 0); 1581 } 1582 #endif // PRODUCT 1583 1584 // Setup safepoint state info for this thread 1585 ThreadSafepointState::create(this); 1586 1587 debug_only(_java_call_counter = 0); 1588 1589 // JVMTI PopFrame support 1590 _popframe_condition = popframe_inactive; 1591 _popframe_preserved_args = NULL; 1592 _popframe_preserved_args_size = 0; 1593 _frames_to_pop_failed_realloc = 0; 1594 1595 if (SafepointMechanism::uses_thread_local_poll()) { 1596 SafepointMechanism::initialize_header(this); 1597 } 1598 1599 pd_initialize(); 1600 } 1601 1602 JavaThread::JavaThread(bool is_attaching_via_jni) : 1603 Thread() { 1604 initialize(); 1605 if (is_attaching_via_jni) { 1606 _jni_attach_state = _attaching_via_jni; 1607 } else { 1608 _jni_attach_state = _not_attaching_via_jni; 1609 } 1610 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1611 } 1612 1613 bool JavaThread::reguard_stack(address cur_sp) { 1614 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1615 && _stack_guard_state != stack_guard_reserved_disabled) { 1616 return true; // Stack already guarded or guard pages not needed. 1617 } 1618 1619 if (register_stack_overflow()) { 1620 // For those architectures which have separate register and 1621 // memory stacks, we must check the register stack to see if 1622 // it has overflowed. 1623 return false; 1624 } 1625 1626 // Java code never executes within the yellow zone: the latter is only 1627 // there to provoke an exception during stack banging. If java code 1628 // is executing there, either StackShadowPages should be larger, or 1629 // some exception code in c1, c2 or the interpreter isn't unwinding 1630 // when it should. 1631 guarantee(cur_sp > stack_reserved_zone_base(), 1632 "not enough space to reguard - increase StackShadowPages"); 1633 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1634 enable_stack_yellow_reserved_zone(); 1635 if (reserved_stack_activation() != stack_base()) { 1636 set_reserved_stack_activation(stack_base()); 1637 } 1638 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1639 set_reserved_stack_activation(stack_base()); 1640 enable_stack_reserved_zone(); 1641 } 1642 return true; 1643 } 1644 1645 bool JavaThread::reguard_stack(void) { 1646 return reguard_stack(os::current_stack_pointer()); 1647 } 1648 1649 1650 void JavaThread::block_if_vm_exited() { 1651 if (_terminated == _vm_exited) { 1652 // _vm_exited is set at safepoint, and Threads_lock is never released 1653 // we will block here forever 1654 Threads_lock->lock_without_safepoint_check(); 1655 ShouldNotReachHere(); 1656 } 1657 } 1658 1659 1660 // Remove this ifdef when C1 is ported to the compiler interface. 1661 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1662 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1663 1664 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1665 Thread() { 1666 initialize(); 1667 _jni_attach_state = _not_attaching_via_jni; 1668 set_entry_point(entry_point); 1669 // Create the native thread itself. 1670 // %note runtime_23 1671 os::ThreadType thr_type = os::java_thread; 1672 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1673 os::java_thread; 1674 os::create_thread(this, thr_type, stack_sz); 1675 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1676 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1677 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1678 // the exception consists of creating the exception object & initializing it, initialization 1679 // will leave the VM via a JavaCall and then all locks must be unlocked). 1680 // 1681 // The thread is still suspended when we reach here. Thread must be explicit started 1682 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1683 // by calling Threads:add. The reason why this is not done here, is because the thread 1684 // object must be fully initialized (take a look at JVM_Start) 1685 } 1686 1687 JavaThread::~JavaThread() { 1688 1689 // JSR166 -- return the parker to the free list 1690 Parker::Release(_parker); 1691 _parker = NULL; 1692 1693 // Free any remaining previous UnrollBlock 1694 vframeArray* old_array = vframe_array_last(); 1695 1696 if (old_array != NULL) { 1697 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1698 old_array->set_unroll_block(NULL); 1699 delete old_info; 1700 delete old_array; 1701 } 1702 1703 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1704 if (deferred != NULL) { 1705 // This can only happen if thread is destroyed before deoptimization occurs. 1706 assert(deferred->length() != 0, "empty array!"); 1707 do { 1708 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1709 deferred->remove_at(0); 1710 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1711 delete dlv; 1712 } while (deferred->length() != 0); 1713 delete deferred; 1714 } 1715 1716 // All Java related clean up happens in exit 1717 ThreadSafepointState::destroy(this); 1718 if (_thread_stat != NULL) delete _thread_stat; 1719 1720 #if INCLUDE_JVMCI 1721 if (JVMCICounterSize > 0) { 1722 if (jvmci_counters_include(this)) { 1723 for (int i = 0; i < JVMCICounterSize; i++) { 1724 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1725 } 1726 } 1727 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1728 } 1729 #endif // INCLUDE_JVMCI 1730 } 1731 1732 1733 // The first routine called by a new Java thread 1734 void JavaThread::run() { 1735 // initialize thread-local alloc buffer related fields 1736 this->initialize_tlab(); 1737 1738 // used to test validity of stack trace backs 1739 this->record_base_of_stack_pointer(); 1740 1741 // Record real stack base and size. 1742 this->record_stack_base_and_size(); 1743 1744 this->create_stack_guard_pages(); 1745 1746 this->cache_global_variables(); 1747 1748 // Thread is now sufficient initialized to be handled by the safepoint code as being 1749 // in the VM. Change thread state from _thread_new to _thread_in_vm 1750 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1751 1752 assert(JavaThread::current() == this, "sanity check"); 1753 assert(!Thread::current()->owns_locks(), "sanity check"); 1754 1755 DTRACE_THREAD_PROBE(start, this); 1756 1757 // This operation might block. We call that after all safepoint checks for a new thread has 1758 // been completed. 1759 this->set_active_handles(JNIHandleBlock::allocate_block()); 1760 1761 if (JvmtiExport::should_post_thread_life()) { 1762 JvmtiExport::post_thread_start(this); 1763 } 1764 1765 EventThreadStart event; 1766 if (event.should_commit()) { 1767 event.set_thread(JFR_THREAD_ID(this)); 1768 event.commit(); 1769 } 1770 1771 // We call another function to do the rest so we are sure that the stack addresses used 1772 // from there will be lower than the stack base just computed 1773 thread_main_inner(); 1774 1775 // Note, thread is no longer valid at this point! 1776 } 1777 1778 1779 void JavaThread::thread_main_inner() { 1780 assert(JavaThread::current() == this, "sanity check"); 1781 assert(this->threadObj() != NULL, "just checking"); 1782 1783 // Execute thread entry point unless this thread has a pending exception 1784 // or has been stopped before starting. 1785 // Note: Due to JVM_StopThread we can have pending exceptions already! 1786 if (!this->has_pending_exception() && 1787 !java_lang_Thread::is_stillborn(this->threadObj())) { 1788 { 1789 ResourceMark rm(this); 1790 this->set_native_thread_name(this->get_thread_name()); 1791 } 1792 HandleMark hm(this); 1793 this->entry_point()(this, this); 1794 } 1795 1796 DTRACE_THREAD_PROBE(stop, this); 1797 1798 this->exit(false); 1799 this->smr_delete(); 1800 } 1801 1802 1803 static void ensure_join(JavaThread* thread) { 1804 // We do not need to grab the Threads_lock, since we are operating on ourself. 1805 Handle threadObj(thread, thread->threadObj()); 1806 assert(threadObj.not_null(), "java thread object must exist"); 1807 ObjectLocker lock(threadObj, thread); 1808 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1809 thread->clear_pending_exception(); 1810 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1811 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1812 // Clear the native thread instance - this makes isAlive return false and allows the join() 1813 // to complete once we've done the notify_all below 1814 java_lang_Thread::set_thread(threadObj(), NULL); 1815 lock.notify_all(thread); 1816 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1817 thread->clear_pending_exception(); 1818 } 1819 1820 1821 // For any new cleanup additions, please check to see if they need to be applied to 1822 // cleanup_failed_attach_current_thread as well. 1823 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1824 assert(this == JavaThread::current(), "thread consistency check"); 1825 1826 elapsedTimer _timer_exit_phase1; 1827 elapsedTimer _timer_exit_phase2; 1828 elapsedTimer _timer_exit_phase3; 1829 elapsedTimer _timer_exit_phase4; 1830 1831 if (log_is_enabled(Debug, os, thread, timer)) { 1832 _timer_exit_phase1.start(); 1833 } 1834 1835 HandleMark hm(this); 1836 Handle uncaught_exception(this, this->pending_exception()); 1837 this->clear_pending_exception(); 1838 Handle threadObj(this, this->threadObj()); 1839 assert(threadObj.not_null(), "Java thread object should be created"); 1840 1841 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1842 { 1843 EXCEPTION_MARK; 1844 1845 CLEAR_PENDING_EXCEPTION; 1846 } 1847 if (!destroy_vm) { 1848 if (uncaught_exception.not_null()) { 1849 EXCEPTION_MARK; 1850 // Call method Thread.dispatchUncaughtException(). 1851 Klass* thread_klass = SystemDictionary::Thread_klass(); 1852 JavaValue result(T_VOID); 1853 JavaCalls::call_virtual(&result, 1854 threadObj, thread_klass, 1855 vmSymbols::dispatchUncaughtException_name(), 1856 vmSymbols::throwable_void_signature(), 1857 uncaught_exception, 1858 THREAD); 1859 if (HAS_PENDING_EXCEPTION) { 1860 ResourceMark rm(this); 1861 jio_fprintf(defaultStream::error_stream(), 1862 "\nException: %s thrown from the UncaughtExceptionHandler" 1863 " in thread \"%s\"\n", 1864 pending_exception()->klass()->external_name(), 1865 get_thread_name()); 1866 CLEAR_PENDING_EXCEPTION; 1867 } 1868 } 1869 1870 // Called before the java thread exit since we want to read info 1871 // from java_lang_Thread object 1872 EventThreadEnd event; 1873 if (event.should_commit()) { 1874 event.set_thread(JFR_THREAD_ID(this)); 1875 event.commit(); 1876 } 1877 1878 // Call after last event on thread 1879 JFR_ONLY(Jfr::on_thread_exit(this);) 1880 1881 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1882 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1883 // is deprecated anyhow. 1884 if (!is_Compiler_thread()) { 1885 int count = 3; 1886 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1887 EXCEPTION_MARK; 1888 JavaValue result(T_VOID); 1889 Klass* thread_klass = SystemDictionary::Thread_klass(); 1890 JavaCalls::call_virtual(&result, 1891 threadObj, thread_klass, 1892 vmSymbols::exit_method_name(), 1893 vmSymbols::void_method_signature(), 1894 THREAD); 1895 CLEAR_PENDING_EXCEPTION; 1896 } 1897 } 1898 // notify JVMTI 1899 if (JvmtiExport::should_post_thread_life()) { 1900 JvmtiExport::post_thread_end(this); 1901 } 1902 1903 // We have notified the agents that we are exiting, before we go on, 1904 // we must check for a pending external suspend request and honor it 1905 // in order to not surprise the thread that made the suspend request. 1906 while (true) { 1907 { 1908 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1909 if (!is_external_suspend()) { 1910 set_terminated(_thread_exiting); 1911 ThreadService::current_thread_exiting(this); 1912 break; 1913 } 1914 // Implied else: 1915 // Things get a little tricky here. We have a pending external 1916 // suspend request, but we are holding the SR_lock so we 1917 // can't just self-suspend. So we temporarily drop the lock 1918 // and then self-suspend. 1919 } 1920 1921 ThreadBlockInVM tbivm(this); 1922 java_suspend_self(); 1923 1924 // We're done with this suspend request, but we have to loop around 1925 // and check again. Eventually we will get SR_lock without a pending 1926 // external suspend request and will be able to mark ourselves as 1927 // exiting. 1928 } 1929 // no more external suspends are allowed at this point 1930 } else { 1931 // before_exit() has already posted JVMTI THREAD_END events 1932 } 1933 1934 if (log_is_enabled(Debug, os, thread, timer)) { 1935 _timer_exit_phase1.stop(); 1936 _timer_exit_phase2.start(); 1937 } 1938 // Notify waiters on thread object. This has to be done after exit() is called 1939 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1940 // group should have the destroyed bit set before waiters are notified). 1941 ensure_join(this); 1942 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1943 1944 if (log_is_enabled(Debug, os, thread, timer)) { 1945 _timer_exit_phase2.stop(); 1946 _timer_exit_phase3.start(); 1947 } 1948 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1949 // held by this thread must be released. The spec does not distinguish 1950 // between JNI-acquired and regular Java monitors. We can only see 1951 // regular Java monitors here if monitor enter-exit matching is broken. 1952 // 1953 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1954 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1955 if (exit_type == jni_detach) { 1956 // Sanity check even though JNI DetachCurrentThread() would have 1957 // returned JNI_ERR if there was a Java frame. JavaThread exit 1958 // should be done executing Java code by the time we get here. 1959 assert(!this->has_last_Java_frame(), 1960 "should not have a Java frame when detaching or exiting"); 1961 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1962 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1963 } 1964 1965 // These things needs to be done while we are still a Java Thread. Make sure that thread 1966 // is in a consistent state, in case GC happens 1967 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1968 1969 if (active_handles() != NULL) { 1970 JNIHandleBlock* block = active_handles(); 1971 set_active_handles(NULL); 1972 JNIHandleBlock::release_block(block); 1973 } 1974 1975 if (free_handle_block() != NULL) { 1976 JNIHandleBlock* block = free_handle_block(); 1977 set_free_handle_block(NULL); 1978 JNIHandleBlock::release_block(block); 1979 } 1980 1981 // These have to be removed while this is still a valid thread. 1982 remove_stack_guard_pages(); 1983 1984 if (UseTLAB) { 1985 tlab().retire(); 1986 } 1987 1988 if (JvmtiEnv::environments_might_exist()) { 1989 JvmtiExport::cleanup_thread(this); 1990 } 1991 1992 // We must flush any deferred card marks and other various GC barrier 1993 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 1994 // before removing a thread from the list of active threads. 1995 BarrierSet::barrier_set()->on_thread_detach(this); 1996 1997 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1998 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1999 os::current_thread_id()); 2000 2001 if (log_is_enabled(Debug, os, thread, timer)) { 2002 _timer_exit_phase3.stop(); 2003 _timer_exit_phase4.start(); 2004 } 2005 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2006 Threads::remove(this); 2007 2008 if (log_is_enabled(Debug, os, thread, timer)) { 2009 _timer_exit_phase4.stop(); 2010 ResourceMark rm(this); 2011 log_debug(os, thread, timer)("name='%s'" 2012 ", exit-phase1=" JLONG_FORMAT 2013 ", exit-phase2=" JLONG_FORMAT 2014 ", exit-phase3=" JLONG_FORMAT 2015 ", exit-phase4=" JLONG_FORMAT, 2016 get_thread_name(), 2017 _timer_exit_phase1.milliseconds(), 2018 _timer_exit_phase2.milliseconds(), 2019 _timer_exit_phase3.milliseconds(), 2020 _timer_exit_phase4.milliseconds()); 2021 } 2022 } 2023 2024 void JavaThread::cleanup_failed_attach_current_thread() { 2025 if (active_handles() != NULL) { 2026 JNIHandleBlock* block = active_handles(); 2027 set_active_handles(NULL); 2028 JNIHandleBlock::release_block(block); 2029 } 2030 2031 if (free_handle_block() != NULL) { 2032 JNIHandleBlock* block = free_handle_block(); 2033 set_free_handle_block(NULL); 2034 JNIHandleBlock::release_block(block); 2035 } 2036 2037 // These have to be removed while this is still a valid thread. 2038 remove_stack_guard_pages(); 2039 2040 if (UseTLAB) { 2041 tlab().retire(); 2042 } 2043 2044 BarrierSet::barrier_set()->on_thread_detach(this); 2045 2046 Threads::remove(this); 2047 this->smr_delete(); 2048 } 2049 2050 JavaThread* JavaThread::active() { 2051 Thread* thread = Thread::current(); 2052 if (thread->is_Java_thread()) { 2053 return (JavaThread*) thread; 2054 } else { 2055 assert(thread->is_VM_thread(), "this must be a vm thread"); 2056 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2057 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2058 assert(ret->is_Java_thread(), "must be a Java thread"); 2059 return ret; 2060 } 2061 } 2062 2063 bool JavaThread::is_lock_owned(address adr) const { 2064 if (Thread::is_lock_owned(adr)) return true; 2065 2066 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2067 if (chunk->contains(adr)) return true; 2068 } 2069 2070 return false; 2071 } 2072 2073 2074 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2075 chunk->set_next(monitor_chunks()); 2076 set_monitor_chunks(chunk); 2077 } 2078 2079 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2080 guarantee(monitor_chunks() != NULL, "must be non empty"); 2081 if (monitor_chunks() == chunk) { 2082 set_monitor_chunks(chunk->next()); 2083 } else { 2084 MonitorChunk* prev = monitor_chunks(); 2085 while (prev->next() != chunk) prev = prev->next(); 2086 prev->set_next(chunk->next()); 2087 } 2088 } 2089 2090 // JVM support. 2091 2092 // Note: this function shouldn't block if it's called in 2093 // _thread_in_native_trans state (such as from 2094 // check_special_condition_for_native_trans()). 2095 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2096 2097 if (has_last_Java_frame() && has_async_condition()) { 2098 // If we are at a polling page safepoint (not a poll return) 2099 // then we must defer async exception because live registers 2100 // will be clobbered by the exception path. Poll return is 2101 // ok because the call we a returning from already collides 2102 // with exception handling registers and so there is no issue. 2103 // (The exception handling path kills call result registers but 2104 // this is ok since the exception kills the result anyway). 2105 2106 if (is_at_poll_safepoint()) { 2107 // if the code we are returning to has deoptimized we must defer 2108 // the exception otherwise live registers get clobbered on the 2109 // exception path before deoptimization is able to retrieve them. 2110 // 2111 RegisterMap map(this, false); 2112 frame caller_fr = last_frame().sender(&map); 2113 assert(caller_fr.is_compiled_frame(), "what?"); 2114 if (caller_fr.is_deoptimized_frame()) { 2115 log_info(exceptions)("deferred async exception at compiled safepoint"); 2116 return; 2117 } 2118 } 2119 } 2120 2121 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2122 if (condition == _no_async_condition) { 2123 // Conditions have changed since has_special_runtime_exit_condition() 2124 // was called: 2125 // - if we were here only because of an external suspend request, 2126 // then that was taken care of above (or cancelled) so we are done 2127 // - if we were here because of another async request, then it has 2128 // been cleared between the has_special_runtime_exit_condition() 2129 // and now so again we are done 2130 return; 2131 } 2132 2133 // Check for pending async. exception 2134 if (_pending_async_exception != NULL) { 2135 // Only overwrite an already pending exception, if it is not a threadDeath. 2136 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2137 2138 // We cannot call Exceptions::_throw(...) here because we cannot block 2139 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2140 2141 LogTarget(Info, exceptions) lt; 2142 if (lt.is_enabled()) { 2143 ResourceMark rm; 2144 LogStream ls(lt); 2145 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2146 if (has_last_Java_frame()) { 2147 frame f = last_frame(); 2148 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2149 } 2150 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2151 } 2152 _pending_async_exception = NULL; 2153 clear_has_async_exception(); 2154 } 2155 } 2156 2157 if (check_unsafe_error && 2158 condition == _async_unsafe_access_error && !has_pending_exception()) { 2159 condition = _no_async_condition; // done 2160 switch (thread_state()) { 2161 case _thread_in_vm: { 2162 JavaThread* THREAD = this; 2163 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2164 } 2165 case _thread_in_native: { 2166 ThreadInVMfromNative tiv(this); 2167 JavaThread* THREAD = this; 2168 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2169 } 2170 case _thread_in_Java: { 2171 ThreadInVMfromJava tiv(this); 2172 JavaThread* THREAD = this; 2173 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2174 } 2175 default: 2176 ShouldNotReachHere(); 2177 } 2178 } 2179 2180 assert(condition == _no_async_condition || has_pending_exception() || 2181 (!check_unsafe_error && condition == _async_unsafe_access_error), 2182 "must have handled the async condition, if no exception"); 2183 } 2184 2185 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2186 // 2187 // Check for pending external suspend. Internal suspend requests do 2188 // not use handle_special_runtime_exit_condition(). 2189 // If JNIEnv proxies are allowed, don't self-suspend if the target 2190 // thread is not the current thread. In older versions of jdbx, jdbx 2191 // threads could call into the VM with another thread's JNIEnv so we 2192 // can be here operating on behalf of a suspended thread (4432884). 2193 bool do_self_suspend = is_external_suspend_with_lock(); 2194 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2195 // 2196 // Because thread is external suspended the safepoint code will count 2197 // thread as at a safepoint. This can be odd because we can be here 2198 // as _thread_in_Java which would normally transition to _thread_blocked 2199 // at a safepoint. We would like to mark the thread as _thread_blocked 2200 // before calling java_suspend_self like all other callers of it but 2201 // we must then observe proper safepoint protocol. (We can't leave 2202 // _thread_blocked with a safepoint in progress). However we can be 2203 // here as _thread_in_native_trans so we can't use a normal transition 2204 // constructor/destructor pair because they assert on that type of 2205 // transition. We could do something like: 2206 // 2207 // JavaThreadState state = thread_state(); 2208 // set_thread_state(_thread_in_vm); 2209 // { 2210 // ThreadBlockInVM tbivm(this); 2211 // java_suspend_self() 2212 // } 2213 // set_thread_state(_thread_in_vm_trans); 2214 // if (safepoint) block; 2215 // set_thread_state(state); 2216 // 2217 // but that is pretty messy. Instead we just go with the way the 2218 // code has worked before and note that this is the only path to 2219 // java_suspend_self that doesn't put the thread in _thread_blocked 2220 // mode. 2221 2222 frame_anchor()->make_walkable(this); 2223 java_suspend_self(); 2224 2225 // We might be here for reasons in addition to the self-suspend request 2226 // so check for other async requests. 2227 } 2228 2229 if (check_asyncs) { 2230 check_and_handle_async_exceptions(); 2231 } 2232 2233 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(this);) 2234 } 2235 2236 void JavaThread::send_thread_stop(oop java_throwable) { 2237 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2238 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2239 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2240 2241 // Do not throw asynchronous exceptions against the compiler thread 2242 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2243 if (!can_call_java()) return; 2244 2245 { 2246 // Actually throw the Throwable against the target Thread - however 2247 // only if there is no thread death exception installed already. 2248 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2249 // If the topmost frame is a runtime stub, then we are calling into 2250 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2251 // must deoptimize the caller before continuing, as the compiled exception handler table 2252 // may not be valid 2253 if (has_last_Java_frame()) { 2254 frame f = last_frame(); 2255 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2256 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2257 RegisterMap reg_map(this, UseBiasedLocking); 2258 frame compiled_frame = f.sender(®_map); 2259 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2260 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2261 } 2262 } 2263 } 2264 2265 // Set async. pending exception in thread. 2266 set_pending_async_exception(java_throwable); 2267 2268 if (log_is_enabled(Info, exceptions)) { 2269 ResourceMark rm; 2270 log_info(exceptions)("Pending Async. exception installed of type: %s", 2271 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2272 } 2273 // for AbortVMOnException flag 2274 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2275 } 2276 } 2277 2278 2279 // Interrupt thread so it will wake up from a potential wait() 2280 Thread::interrupt(this); 2281 } 2282 2283 // External suspension mechanism. 2284 // 2285 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2286 // to any VM_locks and it is at a transition 2287 // Self-suspension will happen on the transition out of the vm. 2288 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2289 // 2290 // Guarantees on return: 2291 // + Target thread will not execute any new bytecode (that's why we need to 2292 // force a safepoint) 2293 // + Target thread will not enter any new monitors 2294 // 2295 void JavaThread::java_suspend() { 2296 ThreadsListHandle tlh; 2297 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2298 return; 2299 } 2300 2301 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2302 if (!is_external_suspend()) { 2303 // a racing resume has cancelled us; bail out now 2304 return; 2305 } 2306 2307 // suspend is done 2308 uint32_t debug_bits = 0; 2309 // Warning: is_ext_suspend_completed() may temporarily drop the 2310 // SR_lock to allow the thread to reach a stable thread state if 2311 // it is currently in a transient thread state. 2312 if (is_ext_suspend_completed(false /* !called_by_wait */, 2313 SuspendRetryDelay, &debug_bits)) { 2314 return; 2315 } 2316 } 2317 2318 VM_ThreadSuspend vm_suspend; 2319 VMThread::execute(&vm_suspend); 2320 } 2321 2322 // Part II of external suspension. 2323 // A JavaThread self suspends when it detects a pending external suspend 2324 // request. This is usually on transitions. It is also done in places 2325 // where continuing to the next transition would surprise the caller, 2326 // e.g., monitor entry. 2327 // 2328 // Returns the number of times that the thread self-suspended. 2329 // 2330 // Note: DO NOT call java_suspend_self() when you just want to block current 2331 // thread. java_suspend_self() is the second stage of cooperative 2332 // suspension for external suspend requests and should only be used 2333 // to complete an external suspend request. 2334 // 2335 int JavaThread::java_suspend_self() { 2336 int ret = 0; 2337 2338 // we are in the process of exiting so don't suspend 2339 if (is_exiting()) { 2340 clear_external_suspend(); 2341 return ret; 2342 } 2343 2344 assert(_anchor.walkable() || 2345 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2346 "must have walkable stack"); 2347 2348 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2349 2350 assert(!this->is_ext_suspended(), 2351 "a thread trying to self-suspend should not already be suspended"); 2352 2353 if (this->is_suspend_equivalent()) { 2354 // If we are self-suspending as a result of the lifting of a 2355 // suspend equivalent condition, then the suspend_equivalent 2356 // flag is not cleared until we set the ext_suspended flag so 2357 // that wait_for_ext_suspend_completion() returns consistent 2358 // results. 2359 this->clear_suspend_equivalent(); 2360 } 2361 2362 // A racing resume may have cancelled us before we grabbed SR_lock 2363 // above. Or another external suspend request could be waiting for us 2364 // by the time we return from SR_lock()->wait(). The thread 2365 // that requested the suspension may already be trying to walk our 2366 // stack and if we return now, we can change the stack out from under 2367 // it. This would be a "bad thing (TM)" and cause the stack walker 2368 // to crash. We stay self-suspended until there are no more pending 2369 // external suspend requests. 2370 while (is_external_suspend()) { 2371 ret++; 2372 this->set_ext_suspended(); 2373 2374 // _ext_suspended flag is cleared by java_resume() 2375 while (is_ext_suspended()) { 2376 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2377 } 2378 } 2379 2380 return ret; 2381 } 2382 2383 #ifdef ASSERT 2384 // Verify the JavaThread has not yet been published in the Threads::list, and 2385 // hence doesn't need protection from concurrent access at this stage. 2386 void JavaThread::verify_not_published() { 2387 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2388 // since an unpublished JavaThread doesn't participate in the 2389 // Thread-SMR protocol for keeping a ThreadsList alive. 2390 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2391 } 2392 #endif 2393 2394 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2395 // progress or when _suspend_flags is non-zero. 2396 // Current thread needs to self-suspend if there is a suspend request and/or 2397 // block if a safepoint is in progress. 2398 // Async exception ISN'T checked. 2399 // Note only the ThreadInVMfromNative transition can call this function 2400 // directly and when thread state is _thread_in_native_trans 2401 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2402 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2403 2404 JavaThread *curJT = JavaThread::current(); 2405 bool do_self_suspend = thread->is_external_suspend(); 2406 2407 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2408 2409 // If JNIEnv proxies are allowed, don't self-suspend if the target 2410 // thread is not the current thread. In older versions of jdbx, jdbx 2411 // threads could call into the VM with another thread's JNIEnv so we 2412 // can be here operating on behalf of a suspended thread (4432884). 2413 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2414 JavaThreadState state = thread->thread_state(); 2415 2416 // We mark this thread_blocked state as a suspend-equivalent so 2417 // that a caller to is_ext_suspend_completed() won't be confused. 2418 // The suspend-equivalent state is cleared by java_suspend_self(). 2419 thread->set_suspend_equivalent(); 2420 2421 // If the safepoint code sees the _thread_in_native_trans state, it will 2422 // wait until the thread changes to other thread state. There is no 2423 // guarantee on how soon we can obtain the SR_lock and complete the 2424 // self-suspend request. It would be a bad idea to let safepoint wait for 2425 // too long. Temporarily change the state to _thread_blocked to 2426 // let the VM thread know that this thread is ready for GC. The problem 2427 // of changing thread state is that safepoint could happen just after 2428 // java_suspend_self() returns after being resumed, and VM thread will 2429 // see the _thread_blocked state. We must check for safepoint 2430 // after restoring the state and make sure we won't leave while a safepoint 2431 // is in progress. 2432 thread->set_thread_state(_thread_blocked); 2433 thread->java_suspend_self(); 2434 thread->set_thread_state(state); 2435 2436 InterfaceSupport::serialize_thread_state_with_handler(thread); 2437 } 2438 2439 SafepointMechanism::block_if_requested(curJT); 2440 2441 if (thread->is_deopt_suspend()) { 2442 thread->clear_deopt_suspend(); 2443 RegisterMap map(thread, false); 2444 frame f = thread->last_frame(); 2445 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2446 f = f.sender(&map); 2447 } 2448 if (f.id() == thread->must_deopt_id()) { 2449 thread->clear_must_deopt_id(); 2450 f.deoptimize(thread); 2451 } else { 2452 fatal("missed deoptimization!"); 2453 } 2454 } 2455 2456 JFR_ONLY(SUSPEND_THREAD_CONDITIONAL(thread);) 2457 } 2458 2459 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2460 // progress or when _suspend_flags is non-zero. 2461 // Current thread needs to self-suspend if there is a suspend request and/or 2462 // block if a safepoint is in progress. 2463 // Also check for pending async exception (not including unsafe access error). 2464 // Note only the native==>VM/Java barriers can call this function and when 2465 // thread state is _thread_in_native_trans. 2466 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2467 check_safepoint_and_suspend_for_native_trans(thread); 2468 2469 if (thread->has_async_exception()) { 2470 // We are in _thread_in_native_trans state, don't handle unsafe 2471 // access error since that may block. 2472 thread->check_and_handle_async_exceptions(false); 2473 } 2474 } 2475 2476 // This is a variant of the normal 2477 // check_special_condition_for_native_trans with slightly different 2478 // semantics for use by critical native wrappers. It does all the 2479 // normal checks but also performs the transition back into 2480 // thread_in_Java state. This is required so that critical natives 2481 // can potentially block and perform a GC if they are the last thread 2482 // exiting the GCLocker. 2483 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2484 check_special_condition_for_native_trans(thread); 2485 2486 // Finish the transition 2487 thread->set_thread_state(_thread_in_Java); 2488 2489 if (thread->do_critical_native_unlock()) { 2490 ThreadInVMfromJavaNoAsyncException tiv(thread); 2491 GCLocker::unlock_critical(thread); 2492 thread->clear_critical_native_unlock(); 2493 } 2494 } 2495 2496 // We need to guarantee the Threads_lock here, since resumes are not 2497 // allowed during safepoint synchronization 2498 // Can only resume from an external suspension 2499 void JavaThread::java_resume() { 2500 assert_locked_or_safepoint(Threads_lock); 2501 2502 // Sanity check: thread is gone, has started exiting or the thread 2503 // was not externally suspended. 2504 ThreadsListHandle tlh; 2505 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2506 return; 2507 } 2508 2509 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2510 2511 clear_external_suspend(); 2512 2513 if (is_ext_suspended()) { 2514 clear_ext_suspended(); 2515 SR_lock()->notify_all(); 2516 } 2517 } 2518 2519 size_t JavaThread::_stack_red_zone_size = 0; 2520 size_t JavaThread::_stack_yellow_zone_size = 0; 2521 size_t JavaThread::_stack_reserved_zone_size = 0; 2522 size_t JavaThread::_stack_shadow_zone_size = 0; 2523 2524 void JavaThread::create_stack_guard_pages() { 2525 if (!os::uses_stack_guard_pages() || 2526 _stack_guard_state != stack_guard_unused || 2527 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2528 log_info(os, thread)("Stack guard page creation for thread " 2529 UINTX_FORMAT " disabled", os::current_thread_id()); 2530 return; 2531 } 2532 address low_addr = stack_end(); 2533 size_t len = stack_guard_zone_size(); 2534 2535 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2536 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2537 2538 int must_commit = os::must_commit_stack_guard_pages(); 2539 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2540 2541 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2542 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2543 return; 2544 } 2545 2546 if (os::guard_memory((char *) low_addr, len)) { 2547 _stack_guard_state = stack_guard_enabled; 2548 } else { 2549 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2550 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2551 if (os::uncommit_memory((char *) low_addr, len)) { 2552 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2553 } 2554 return; 2555 } 2556 2557 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2558 PTR_FORMAT "-" PTR_FORMAT ".", 2559 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2560 } 2561 2562 void JavaThread::remove_stack_guard_pages() { 2563 assert(Thread::current() == this, "from different thread"); 2564 if (_stack_guard_state == stack_guard_unused) return; 2565 address low_addr = stack_end(); 2566 size_t len = stack_guard_zone_size(); 2567 2568 if (os::must_commit_stack_guard_pages()) { 2569 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2570 _stack_guard_state = stack_guard_unused; 2571 } else { 2572 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2573 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2574 return; 2575 } 2576 } else { 2577 if (_stack_guard_state == stack_guard_unused) return; 2578 if (os::unguard_memory((char *) low_addr, len)) { 2579 _stack_guard_state = stack_guard_unused; 2580 } else { 2581 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2582 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2583 return; 2584 } 2585 } 2586 2587 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2588 PTR_FORMAT "-" PTR_FORMAT ".", 2589 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2590 } 2591 2592 void JavaThread::enable_stack_reserved_zone() { 2593 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2594 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2595 2596 // The base notation is from the stack's point of view, growing downward. 2597 // We need to adjust it to work correctly with guard_memory() 2598 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2599 2600 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2601 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2602 2603 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2604 _stack_guard_state = stack_guard_enabled; 2605 } else { 2606 warning("Attempt to guard stack reserved zone failed."); 2607 } 2608 enable_register_stack_guard(); 2609 } 2610 2611 void JavaThread::disable_stack_reserved_zone() { 2612 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2613 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2614 2615 // Simply return if called for a thread that does not use guard pages. 2616 if (_stack_guard_state == stack_guard_unused) return; 2617 2618 // The base notation is from the stack's point of view, growing downward. 2619 // We need to adjust it to work correctly with guard_memory() 2620 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2621 2622 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2623 _stack_guard_state = stack_guard_reserved_disabled; 2624 } else { 2625 warning("Attempt to unguard stack reserved zone failed."); 2626 } 2627 disable_register_stack_guard(); 2628 } 2629 2630 void JavaThread::enable_stack_yellow_reserved_zone() { 2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2632 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2633 2634 // The base notation is from the stacks point of view, growing downward. 2635 // We need to adjust it to work correctly with guard_memory() 2636 address base = stack_red_zone_base(); 2637 2638 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2639 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2640 2641 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2642 _stack_guard_state = stack_guard_enabled; 2643 } else { 2644 warning("Attempt to guard stack yellow zone failed."); 2645 } 2646 enable_register_stack_guard(); 2647 } 2648 2649 void JavaThread::disable_stack_yellow_reserved_zone() { 2650 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2651 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2652 2653 // Simply return if called for a thread that does not use guard pages. 2654 if (_stack_guard_state == stack_guard_unused) return; 2655 2656 // The base notation is from the stacks point of view, growing downward. 2657 // We need to adjust it to work correctly with guard_memory() 2658 address base = stack_red_zone_base(); 2659 2660 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2661 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2662 } else { 2663 warning("Attempt to unguard stack yellow zone failed."); 2664 } 2665 disable_register_stack_guard(); 2666 } 2667 2668 void JavaThread::enable_stack_red_zone() { 2669 // The base notation is from the stacks point of view, growing downward. 2670 // We need to adjust it to work correctly with guard_memory() 2671 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2672 address base = stack_red_zone_base() - stack_red_zone_size(); 2673 2674 guarantee(base < stack_base(), "Error calculating stack red zone"); 2675 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2676 2677 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2678 warning("Attempt to guard stack red zone failed."); 2679 } 2680 } 2681 2682 void JavaThread::disable_stack_red_zone() { 2683 // The base notation is from the stacks point of view, growing downward. 2684 // We need to adjust it to work correctly with guard_memory() 2685 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2686 address base = stack_red_zone_base() - stack_red_zone_size(); 2687 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2688 warning("Attempt to unguard stack red zone failed."); 2689 } 2690 } 2691 2692 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2693 // ignore is there is no stack 2694 if (!has_last_Java_frame()) return; 2695 // traverse the stack frames. Starts from top frame. 2696 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2697 frame* fr = fst.current(); 2698 f(fr, fst.register_map()); 2699 } 2700 } 2701 2702 2703 #ifndef PRODUCT 2704 // Deoptimization 2705 // Function for testing deoptimization 2706 void JavaThread::deoptimize() { 2707 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2708 StackFrameStream fst(this, UseBiasedLocking); 2709 bool deopt = false; // Dump stack only if a deopt actually happens. 2710 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2711 // Iterate over all frames in the thread and deoptimize 2712 for (; !fst.is_done(); fst.next()) { 2713 if (fst.current()->can_be_deoptimized()) { 2714 2715 if (only_at) { 2716 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2717 // consists of comma or carriage return separated numbers so 2718 // search for the current bci in that string. 2719 address pc = fst.current()->pc(); 2720 nmethod* nm = (nmethod*) fst.current()->cb(); 2721 ScopeDesc* sd = nm->scope_desc_at(pc); 2722 char buffer[8]; 2723 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2724 size_t len = strlen(buffer); 2725 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2726 while (found != NULL) { 2727 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2728 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2729 // Check that the bci found is bracketed by terminators. 2730 break; 2731 } 2732 found = strstr(found + 1, buffer); 2733 } 2734 if (!found) { 2735 continue; 2736 } 2737 } 2738 2739 if (DebugDeoptimization && !deopt) { 2740 deopt = true; // One-time only print before deopt 2741 tty->print_cr("[BEFORE Deoptimization]"); 2742 trace_frames(); 2743 trace_stack(); 2744 } 2745 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2746 } 2747 } 2748 2749 if (DebugDeoptimization && deopt) { 2750 tty->print_cr("[AFTER Deoptimization]"); 2751 trace_frames(); 2752 } 2753 } 2754 2755 2756 // Make zombies 2757 void JavaThread::make_zombies() { 2758 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2759 if (fst.current()->can_be_deoptimized()) { 2760 // it is a Java nmethod 2761 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2762 nm->make_not_entrant(); 2763 } 2764 } 2765 } 2766 #endif // PRODUCT 2767 2768 2769 void JavaThread::deoptimized_wrt_marked_nmethods() { 2770 if (!has_last_Java_frame()) return; 2771 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2772 StackFrameStream fst(this, UseBiasedLocking); 2773 for (; !fst.is_done(); fst.next()) { 2774 if (fst.current()->should_be_deoptimized()) { 2775 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2776 } 2777 } 2778 } 2779 2780 2781 // If the caller is a NamedThread, then remember, in the current scope, 2782 // the given JavaThread in its _processed_thread field. 2783 class RememberProcessedThread: public StackObj { 2784 NamedThread* _cur_thr; 2785 public: 2786 RememberProcessedThread(JavaThread* jthr) { 2787 Thread* thread = Thread::current(); 2788 if (thread->is_Named_thread()) { 2789 _cur_thr = (NamedThread *)thread; 2790 _cur_thr->set_processed_thread(jthr); 2791 } else { 2792 _cur_thr = NULL; 2793 } 2794 } 2795 2796 ~RememberProcessedThread() { 2797 if (_cur_thr) { 2798 _cur_thr->set_processed_thread(NULL); 2799 } 2800 } 2801 }; 2802 2803 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2804 // Verify that the deferred card marks have been flushed. 2805 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2806 2807 // Traverse the GCHandles 2808 Thread::oops_do(f, cf); 2809 2810 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2811 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2812 2813 if (has_last_Java_frame()) { 2814 // Record JavaThread to GC thread 2815 RememberProcessedThread rpt(this); 2816 2817 // Traverse the privileged stack 2818 if (_privileged_stack_top != NULL) { 2819 _privileged_stack_top->oops_do(f); 2820 } 2821 2822 // traverse the registered growable array 2823 if (_array_for_gc != NULL) { 2824 for (int index = 0; index < _array_for_gc->length(); index++) { 2825 f->do_oop(_array_for_gc->adr_at(index)); 2826 } 2827 } 2828 2829 // Traverse the monitor chunks 2830 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2831 chunk->oops_do(f); 2832 } 2833 2834 // Traverse the execution stack 2835 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2836 fst.current()->oops_do(f, cf, fst.register_map()); 2837 } 2838 } 2839 2840 // callee_target is never live across a gc point so NULL it here should 2841 // it still contain a methdOop. 2842 2843 set_callee_target(NULL); 2844 2845 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2846 // If we have deferred set_locals there might be oops waiting to be 2847 // written 2848 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2849 if (list != NULL) { 2850 for (int i = 0; i < list->length(); i++) { 2851 list->at(i)->oops_do(f); 2852 } 2853 } 2854 2855 // Traverse instance variables at the end since the GC may be moving things 2856 // around using this function 2857 f->do_oop((oop*) &_threadObj); 2858 f->do_oop((oop*) &_vm_result); 2859 f->do_oop((oop*) &_exception_oop); 2860 f->do_oop((oop*) &_pending_async_exception); 2861 2862 if (jvmti_thread_state() != NULL) { 2863 jvmti_thread_state()->oops_do(f); 2864 } 2865 } 2866 2867 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2868 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2869 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2870 2871 if (has_last_Java_frame()) { 2872 // Traverse the execution stack 2873 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2874 fst.current()->nmethods_do(cf); 2875 } 2876 } 2877 } 2878 2879 void JavaThread::metadata_do(void f(Metadata*)) { 2880 if (has_last_Java_frame()) { 2881 // Traverse the execution stack to call f() on the methods in the stack 2882 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2883 fst.current()->metadata_do(f); 2884 } 2885 } else if (is_Compiler_thread()) { 2886 // need to walk ciMetadata in current compile tasks to keep alive. 2887 CompilerThread* ct = (CompilerThread*)this; 2888 if (ct->env() != NULL) { 2889 ct->env()->metadata_do(f); 2890 } 2891 CompileTask* task = ct->task(); 2892 if (task != NULL) { 2893 task->metadata_do(f); 2894 } 2895 } 2896 } 2897 2898 // Printing 2899 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2900 switch (_thread_state) { 2901 case _thread_uninitialized: return "_thread_uninitialized"; 2902 case _thread_new: return "_thread_new"; 2903 case _thread_new_trans: return "_thread_new_trans"; 2904 case _thread_in_native: return "_thread_in_native"; 2905 case _thread_in_native_trans: return "_thread_in_native_trans"; 2906 case _thread_in_vm: return "_thread_in_vm"; 2907 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2908 case _thread_in_Java: return "_thread_in_Java"; 2909 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2910 case _thread_blocked: return "_thread_blocked"; 2911 case _thread_blocked_trans: return "_thread_blocked_trans"; 2912 default: return "unknown thread state"; 2913 } 2914 } 2915 2916 #ifndef PRODUCT 2917 void JavaThread::print_thread_state_on(outputStream *st) const { 2918 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2919 }; 2920 void JavaThread::print_thread_state() const { 2921 print_thread_state_on(tty); 2922 } 2923 #endif // PRODUCT 2924 2925 // Called by Threads::print() for VM_PrintThreads operation 2926 void JavaThread::print_on(outputStream *st, bool print_extended_info) const { 2927 st->print_raw("\""); 2928 st->print_raw(get_thread_name()); 2929 st->print_raw("\" "); 2930 oop thread_oop = threadObj(); 2931 if (thread_oop != NULL) { 2932 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2933 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2934 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2935 } 2936 Thread::print_on(st, print_extended_info); 2937 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2938 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2939 if (thread_oop != NULL) { 2940 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2941 } 2942 #ifndef PRODUCT 2943 print_thread_state_on(st); 2944 _safepoint_state->print_on(st); 2945 #endif // PRODUCT 2946 if (is_Compiler_thread()) { 2947 CompileTask *task = ((CompilerThread*)this)->task(); 2948 if (task != NULL) { 2949 st->print(" Compiling: "); 2950 task->print(st, NULL, true, false); 2951 } else { 2952 st->print(" No compile task"); 2953 } 2954 st->cr(); 2955 } 2956 } 2957 2958 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2959 st->print("%s", get_thread_name_string(buf, buflen)); 2960 } 2961 2962 // Called by fatal error handler. The difference between this and 2963 // JavaThread::print() is that we can't grab lock or allocate memory. 2964 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2965 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2966 oop thread_obj = threadObj(); 2967 if (thread_obj != NULL) { 2968 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2969 } 2970 st->print(" ["); 2971 st->print("%s", _get_thread_state_name(_thread_state)); 2972 if (osthread()) { 2973 st->print(", id=%d", osthread()->thread_id()); 2974 } 2975 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2976 p2i(stack_end()), p2i(stack_base())); 2977 st->print("]"); 2978 2979 ThreadsSMRSupport::print_info_on(this, st); 2980 return; 2981 } 2982 2983 // Verification 2984 2985 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2986 2987 void JavaThread::verify() { 2988 // Verify oops in the thread. 2989 oops_do(&VerifyOopClosure::verify_oop, NULL); 2990 2991 // Verify the stack frames. 2992 frames_do(frame_verify); 2993 } 2994 2995 // CR 6300358 (sub-CR 2137150) 2996 // Most callers of this method assume that it can't return NULL but a 2997 // thread may not have a name whilst it is in the process of attaching to 2998 // the VM - see CR 6412693, and there are places where a JavaThread can be 2999 // seen prior to having it's threadObj set (eg JNI attaching threads and 3000 // if vm exit occurs during initialization). These cases can all be accounted 3001 // for such that this method never returns NULL. 3002 const char* JavaThread::get_thread_name() const { 3003 #ifdef ASSERT 3004 // early safepoints can hit while current thread does not yet have TLS 3005 if (!SafepointSynchronize::is_at_safepoint()) { 3006 Thread *cur = Thread::current(); 3007 if (!(cur->is_Java_thread() && cur == this)) { 3008 // Current JavaThreads are allowed to get their own name without 3009 // the Threads_lock. 3010 assert_locked_or_safepoint(Threads_lock); 3011 } 3012 } 3013 #endif // ASSERT 3014 return get_thread_name_string(); 3015 } 3016 3017 // Returns a non-NULL representation of this thread's name, or a suitable 3018 // descriptive string if there is no set name 3019 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3020 const char* name_str; 3021 oop thread_obj = threadObj(); 3022 if (thread_obj != NULL) { 3023 oop name = java_lang_Thread::name(thread_obj); 3024 if (name != NULL) { 3025 if (buf == NULL) { 3026 name_str = java_lang_String::as_utf8_string(name); 3027 } else { 3028 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3029 } 3030 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3031 name_str = "<no-name - thread is attaching>"; 3032 } else { 3033 name_str = Thread::name(); 3034 } 3035 } else { 3036 name_str = Thread::name(); 3037 } 3038 assert(name_str != NULL, "unexpected NULL thread name"); 3039 return name_str; 3040 } 3041 3042 3043 const char* JavaThread::get_threadgroup_name() const { 3044 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3045 oop thread_obj = threadObj(); 3046 if (thread_obj != NULL) { 3047 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3048 if (thread_group != NULL) { 3049 // ThreadGroup.name can be null 3050 return java_lang_ThreadGroup::name(thread_group); 3051 } 3052 } 3053 return NULL; 3054 } 3055 3056 const char* JavaThread::get_parent_name() const { 3057 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3058 oop thread_obj = threadObj(); 3059 if (thread_obj != NULL) { 3060 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3061 if (thread_group != NULL) { 3062 oop parent = java_lang_ThreadGroup::parent(thread_group); 3063 if (parent != NULL) { 3064 // ThreadGroup.name can be null 3065 return java_lang_ThreadGroup::name(parent); 3066 } 3067 } 3068 } 3069 return NULL; 3070 } 3071 3072 ThreadPriority JavaThread::java_priority() const { 3073 oop thr_oop = threadObj(); 3074 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3075 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3076 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3077 return priority; 3078 } 3079 3080 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3081 3082 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3083 // Link Java Thread object <-> C++ Thread 3084 3085 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3086 // and put it into a new Handle. The Handle "thread_oop" can then 3087 // be used to pass the C++ thread object to other methods. 3088 3089 // Set the Java level thread object (jthread) field of the 3090 // new thread (a JavaThread *) to C++ thread object using the 3091 // "thread_oop" handle. 3092 3093 // Set the thread field (a JavaThread *) of the 3094 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3095 3096 Handle thread_oop(Thread::current(), 3097 JNIHandles::resolve_non_null(jni_thread)); 3098 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3099 "must be initialized"); 3100 set_threadObj(thread_oop()); 3101 java_lang_Thread::set_thread(thread_oop(), this); 3102 3103 if (prio == NoPriority) { 3104 prio = java_lang_Thread::priority(thread_oop()); 3105 assert(prio != NoPriority, "A valid priority should be present"); 3106 } 3107 3108 // Push the Java priority down to the native thread; needs Threads_lock 3109 Thread::set_priority(this, prio); 3110 3111 // Add the new thread to the Threads list and set it in motion. 3112 // We must have threads lock in order to call Threads::add. 3113 // It is crucial that we do not block before the thread is 3114 // added to the Threads list for if a GC happens, then the java_thread oop 3115 // will not be visited by GC. 3116 Threads::add(this); 3117 } 3118 3119 oop JavaThread::current_park_blocker() { 3120 // Support for JSR-166 locks 3121 oop thread_oop = threadObj(); 3122 if (thread_oop != NULL && 3123 JDK_Version::current().supports_thread_park_blocker()) { 3124 return java_lang_Thread::park_blocker(thread_oop); 3125 } 3126 return NULL; 3127 } 3128 3129 3130 void JavaThread::print_stack_on(outputStream* st) { 3131 if (!has_last_Java_frame()) return; 3132 ResourceMark rm; 3133 HandleMark hm; 3134 3135 RegisterMap reg_map(this); 3136 vframe* start_vf = last_java_vframe(®_map); 3137 int count = 0; 3138 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3139 if (f->is_java_frame()) { 3140 javaVFrame* jvf = javaVFrame::cast(f); 3141 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3142 3143 // Print out lock information 3144 if (JavaMonitorsInStackTrace) { 3145 jvf->print_lock_info_on(st, count); 3146 } 3147 } else { 3148 // Ignore non-Java frames 3149 } 3150 3151 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3152 count++; 3153 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3154 } 3155 } 3156 3157 3158 // JVMTI PopFrame support 3159 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3160 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3161 if (in_bytes(size_in_bytes) != 0) { 3162 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3163 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3164 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3165 } 3166 } 3167 3168 void* JavaThread::popframe_preserved_args() { 3169 return _popframe_preserved_args; 3170 } 3171 3172 ByteSize JavaThread::popframe_preserved_args_size() { 3173 return in_ByteSize(_popframe_preserved_args_size); 3174 } 3175 3176 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3177 int sz = in_bytes(popframe_preserved_args_size()); 3178 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3179 return in_WordSize(sz / wordSize); 3180 } 3181 3182 void JavaThread::popframe_free_preserved_args() { 3183 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3184 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3185 _popframe_preserved_args = NULL; 3186 _popframe_preserved_args_size = 0; 3187 } 3188 3189 #ifndef PRODUCT 3190 3191 void JavaThread::trace_frames() { 3192 tty->print_cr("[Describe stack]"); 3193 int frame_no = 1; 3194 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3195 tty->print(" %d. ", frame_no++); 3196 fst.current()->print_value_on(tty, this); 3197 tty->cr(); 3198 } 3199 } 3200 3201 class PrintAndVerifyOopClosure: public OopClosure { 3202 protected: 3203 template <class T> inline void do_oop_work(T* p) { 3204 oop obj = RawAccess<>::oop_load(p); 3205 if (obj == NULL) return; 3206 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3207 if (oopDesc::is_oop_or_null(obj)) { 3208 if (obj->is_objArray()) { 3209 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3210 } else { 3211 obj->print(); 3212 } 3213 } else { 3214 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3215 } 3216 tty->cr(); 3217 } 3218 public: 3219 virtual void do_oop(oop* p) { do_oop_work(p); } 3220 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3221 }; 3222 3223 3224 static void oops_print(frame* f, const RegisterMap *map) { 3225 PrintAndVerifyOopClosure print; 3226 f->print_value(); 3227 f->oops_do(&print, NULL, (RegisterMap*)map); 3228 } 3229 3230 // Print our all the locations that contain oops and whether they are 3231 // valid or not. This useful when trying to find the oldest frame 3232 // where an oop has gone bad since the frame walk is from youngest to 3233 // oldest. 3234 void JavaThread::trace_oops() { 3235 tty->print_cr("[Trace oops]"); 3236 frames_do(oops_print); 3237 } 3238 3239 3240 #ifdef ASSERT 3241 // Print or validate the layout of stack frames 3242 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3243 ResourceMark rm; 3244 PRESERVE_EXCEPTION_MARK; 3245 FrameValues values; 3246 int frame_no = 0; 3247 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3248 fst.current()->describe(values, ++frame_no); 3249 if (depth == frame_no) break; 3250 } 3251 if (validate_only) { 3252 values.validate(); 3253 } else { 3254 tty->print_cr("[Describe stack layout]"); 3255 values.print(this); 3256 } 3257 } 3258 #endif 3259 3260 void JavaThread::trace_stack_from(vframe* start_vf) { 3261 ResourceMark rm; 3262 int vframe_no = 1; 3263 for (vframe* f = start_vf; f; f = f->sender()) { 3264 if (f->is_java_frame()) { 3265 javaVFrame::cast(f)->print_activation(vframe_no++); 3266 } else { 3267 f->print(); 3268 } 3269 if (vframe_no > StackPrintLimit) { 3270 tty->print_cr("...<more frames>..."); 3271 return; 3272 } 3273 } 3274 } 3275 3276 3277 void JavaThread::trace_stack() { 3278 if (!has_last_Java_frame()) return; 3279 ResourceMark rm; 3280 HandleMark hm; 3281 RegisterMap reg_map(this); 3282 trace_stack_from(last_java_vframe(®_map)); 3283 } 3284 3285 3286 #endif // PRODUCT 3287 3288 3289 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3290 assert(reg_map != NULL, "a map must be given"); 3291 frame f = last_frame(); 3292 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3293 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3294 } 3295 return NULL; 3296 } 3297 3298 3299 Klass* JavaThread::security_get_caller_class(int depth) { 3300 vframeStream vfst(this); 3301 vfst.security_get_caller_frame(depth); 3302 if (!vfst.at_end()) { 3303 return vfst.method()->method_holder(); 3304 } 3305 return NULL; 3306 } 3307 3308 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3309 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3310 CompileBroker::compiler_thread_loop(); 3311 } 3312 3313 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3314 NMethodSweeper::sweeper_loop(); 3315 } 3316 3317 // Create a CompilerThread 3318 CompilerThread::CompilerThread(CompileQueue* queue, 3319 CompilerCounters* counters) 3320 : JavaThread(&compiler_thread_entry) { 3321 _env = NULL; 3322 _log = NULL; 3323 _task = NULL; 3324 _queue = queue; 3325 _counters = counters; 3326 _buffer_blob = NULL; 3327 _compiler = NULL; 3328 3329 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3330 resource_area()->bias_to(mtCompiler); 3331 3332 #ifndef PRODUCT 3333 _ideal_graph_printer = NULL; 3334 #endif 3335 } 3336 3337 CompilerThread::~CompilerThread() { 3338 // Delete objects which were allocated on heap. 3339 delete _counters; 3340 } 3341 3342 bool CompilerThread::can_call_java() const { 3343 return _compiler != NULL && _compiler->is_jvmci(); 3344 } 3345 3346 // Create sweeper thread 3347 CodeCacheSweeperThread::CodeCacheSweeperThread() 3348 : JavaThread(&sweeper_thread_entry) { 3349 _scanned_compiled_method = NULL; 3350 } 3351 3352 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3353 JavaThread::oops_do(f, cf); 3354 if (_scanned_compiled_method != NULL && cf != NULL) { 3355 // Safepoints can occur when the sweeper is scanning an nmethod so 3356 // process it here to make sure it isn't unloaded in the middle of 3357 // a scan. 3358 cf->do_code_blob(_scanned_compiled_method); 3359 } 3360 } 3361 3362 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3363 JavaThread::nmethods_do(cf); 3364 if (_scanned_compiled_method != NULL && cf != NULL) { 3365 // Safepoints can occur when the sweeper is scanning an nmethod so 3366 // process it here to make sure it isn't unloaded in the middle of 3367 // a scan. 3368 cf->do_code_blob(_scanned_compiled_method); 3369 } 3370 } 3371 3372 3373 // ======= Threads ======== 3374 3375 // The Threads class links together all active threads, and provides 3376 // operations over all threads. It is protected by the Threads_lock, 3377 // which is also used in other global contexts like safepointing. 3378 // ThreadsListHandles are used to safely perform operations on one 3379 // or more threads without the risk of the thread exiting during the 3380 // operation. 3381 // 3382 // Note: The Threads_lock is currently more widely used than we 3383 // would like. We are actively migrating Threads_lock uses to other 3384 // mechanisms in order to reduce Threads_lock contention. 3385 3386 JavaThread* Threads::_thread_list = NULL; 3387 int Threads::_number_of_threads = 0; 3388 int Threads::_number_of_non_daemon_threads = 0; 3389 int Threads::_return_code = 0; 3390 int Threads::_thread_claim_parity = 0; 3391 size_t JavaThread::_stack_size_at_create = 0; 3392 3393 #ifdef ASSERT 3394 bool Threads::_vm_complete = false; 3395 size_t Threads::_threads_before_barrier_set = 0; 3396 #endif 3397 3398 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3399 Prefetch::read((void*)addr, prefetch_interval); 3400 return *addr; 3401 } 3402 3403 // Possibly the ugliest for loop the world has seen. C++ does not allow 3404 // multiple types in the declaration section of the for loop. In this case 3405 // we are only dealing with pointers and hence can cast them. It looks ugly 3406 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3407 #define DO_JAVA_THREADS(LIST, X) \ 3408 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3409 *MACRO_list = (JavaThread*)(LIST), \ 3410 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3411 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3412 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3413 MACRO_current_p != MACRO_end; \ 3414 MACRO_current_p++, \ 3415 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3416 3417 // All JavaThreads 3418 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3419 3420 // All NonJavaThreads (i.e., every non-JavaThread in the system). 3421 void Threads::non_java_threads_do(ThreadClosure* tc) { 3422 NoSafepointVerifier nsv(!SafepointSynchronize::is_at_safepoint(), false); 3423 for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) { 3424 tc->do_thread(njti.current()); 3425 } 3426 } 3427 3428 // All JavaThreads 3429 void Threads::java_threads_do(ThreadClosure* tc) { 3430 assert_locked_or_safepoint(Threads_lock); 3431 // ALL_JAVA_THREADS iterates through all JavaThreads. 3432 ALL_JAVA_THREADS(p) { 3433 tc->do_thread(p); 3434 } 3435 } 3436 3437 void Threads::java_threads_and_vm_thread_do(ThreadClosure* tc) { 3438 assert_locked_or_safepoint(Threads_lock); 3439 java_threads_do(tc); 3440 tc->do_thread(VMThread::vm_thread()); 3441 } 3442 3443 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3444 void Threads::threads_do(ThreadClosure* tc) { 3445 assert_locked_or_safepoint(Threads_lock); 3446 java_threads_do(tc); 3447 non_java_threads_do(tc); 3448 } 3449 3450 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3451 int cp = Threads::thread_claim_parity(); 3452 ALL_JAVA_THREADS(p) { 3453 if (p->claim_oops_do(is_par, cp)) { 3454 tc->do_thread(p); 3455 } 3456 } 3457 VMThread* vmt = VMThread::vm_thread(); 3458 if (vmt->claim_oops_do(is_par, cp)) { 3459 tc->do_thread(vmt); 3460 } 3461 } 3462 3463 // The system initialization in the library has three phases. 3464 // 3465 // Phase 1: java.lang.System class initialization 3466 // java.lang.System is a primordial class loaded and initialized 3467 // by the VM early during startup. java.lang.System.<clinit> 3468 // only does registerNatives and keeps the rest of the class 3469 // initialization work later until thread initialization completes. 3470 // 3471 // System.initPhase1 initializes the system properties, the static 3472 // fields in, out, and err. Set up java signal handlers, OS-specific 3473 // system settings, and thread group of the main thread. 3474 static void call_initPhase1(TRAPS) { 3475 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3476 JavaValue result(T_VOID); 3477 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3478 vmSymbols::void_method_signature(), CHECK); 3479 } 3480 3481 // Phase 2. Module system initialization 3482 // This will initialize the module system. Only java.base classes 3483 // can be loaded until phase 2 completes. 3484 // 3485 // Call System.initPhase2 after the compiler initialization and jsr292 3486 // classes get initialized because module initialization runs a lot of java 3487 // code, that for performance reasons, should be compiled. Also, this will 3488 // enable the startup code to use lambda and other language features in this 3489 // phase and onward. 3490 // 3491 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3492 static void call_initPhase2(TRAPS) { 3493 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3494 3495 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3496 3497 JavaValue result(T_INT); 3498 JavaCallArguments args; 3499 args.push_int(DisplayVMOutputToStderr); 3500 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3501 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3502 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3503 if (result.get_jint() != JNI_OK) { 3504 vm_exit_during_initialization(); // no message or exception 3505 } 3506 3507 universe_post_module_init(); 3508 } 3509 3510 // Phase 3. final setup - set security manager, system class loader and TCCL 3511 // 3512 // This will instantiate and set the security manager, set the system class 3513 // loader as well as the thread context class loader. The security manager 3514 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3515 // other modules or the application's classpath. 3516 static void call_initPhase3(TRAPS) { 3517 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3518 JavaValue result(T_VOID); 3519 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3520 vmSymbols::void_method_signature(), CHECK); 3521 } 3522 3523 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3524 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3525 3526 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3527 create_vm_init_libraries(); 3528 } 3529 3530 initialize_class(vmSymbols::java_lang_String(), CHECK); 3531 3532 // Inject CompactStrings value after the static initializers for String ran. 3533 java_lang_String::set_compact_strings(CompactStrings); 3534 3535 // Initialize java_lang.System (needed before creating the thread) 3536 initialize_class(vmSymbols::java_lang_System(), CHECK); 3537 // The VM creates & returns objects of this class. Make sure it's initialized. 3538 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3539 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3540 Handle thread_group = create_initial_thread_group(CHECK); 3541 Universe::set_main_thread_group(thread_group()); 3542 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3543 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3544 main_thread->set_threadObj(thread_object); 3545 // Set thread status to running since main thread has 3546 // been started and running. 3547 java_lang_Thread::set_thread_status(thread_object, 3548 java_lang_Thread::RUNNABLE); 3549 3550 // The VM creates objects of this class. 3551 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3552 3553 // The VM preresolves methods to these classes. Make sure that they get initialized 3554 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3555 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3556 3557 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3558 call_initPhase1(CHECK); 3559 3560 // get the Java runtime name after java.lang.System is initialized 3561 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3562 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3563 3564 // an instance of OutOfMemory exception has been allocated earlier 3565 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3566 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3567 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3568 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3569 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3570 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3571 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3572 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3573 } 3574 3575 void Threads::initialize_jsr292_core_classes(TRAPS) { 3576 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3577 3578 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3579 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3580 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3581 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3582 } 3583 3584 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3585 extern void JDK_Version_init(); 3586 3587 // Preinitialize version info. 3588 VM_Version::early_initialize(); 3589 3590 // Check version 3591 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3592 3593 // Initialize library-based TLS 3594 ThreadLocalStorage::init(); 3595 3596 // Initialize the output stream module 3597 ostream_init(); 3598 3599 // Process java launcher properties. 3600 Arguments::process_sun_java_launcher_properties(args); 3601 3602 // Initialize the os module 3603 os::init(); 3604 3605 // Record VM creation timing statistics 3606 TraceVmCreationTime create_vm_timer; 3607 create_vm_timer.start(); 3608 3609 // Initialize system properties. 3610 Arguments::init_system_properties(); 3611 3612 // So that JDK version can be used as a discriminator when parsing arguments 3613 JDK_Version_init(); 3614 3615 // Update/Initialize System properties after JDK version number is known 3616 Arguments::init_version_specific_system_properties(); 3617 3618 // Make sure to initialize log configuration *before* parsing arguments 3619 LogConfiguration::initialize(create_vm_timer.begin_time()); 3620 3621 // Parse arguments 3622 // Note: this internally calls os::init_container_support() 3623 jint parse_result = Arguments::parse(args); 3624 if (parse_result != JNI_OK) return parse_result; 3625 3626 os::init_before_ergo(); 3627 3628 jint ergo_result = Arguments::apply_ergo(); 3629 if (ergo_result != JNI_OK) return ergo_result; 3630 3631 // Final check of all ranges after ergonomics which may change values. 3632 if (!JVMFlagRangeList::check_ranges()) { 3633 return JNI_EINVAL; 3634 } 3635 3636 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3637 bool constraint_result = JVMFlagConstraintList::check_constraints(JVMFlagConstraint::AfterErgo); 3638 if (!constraint_result) { 3639 return JNI_EINVAL; 3640 } 3641 3642 JVMFlagWriteableList::mark_startup(); 3643 3644 if (PauseAtStartup) { 3645 os::pause(); 3646 } 3647 3648 HOTSPOT_VM_INIT_BEGIN(); 3649 3650 // Timing (must come after argument parsing) 3651 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3652 3653 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3654 // Initialize assert poison page mechanism. 3655 if (ShowRegistersOnAssert) { 3656 initialize_assert_poison(); 3657 } 3658 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3659 3660 // Initialize the os module after parsing the args 3661 jint os_init_2_result = os::init_2(); 3662 if (os_init_2_result != JNI_OK) return os_init_2_result; 3663 3664 SafepointMechanism::initialize(); 3665 3666 jint adjust_after_os_result = Arguments::adjust_after_os(); 3667 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3668 3669 // Initialize output stream logging 3670 ostream_init_log(); 3671 3672 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3673 // Must be before create_vm_init_agents() 3674 if (Arguments::init_libraries_at_startup()) { 3675 convert_vm_init_libraries_to_agents(); 3676 } 3677 3678 // Launch -agentlib/-agentpath and converted -Xrun agents 3679 if (Arguments::init_agents_at_startup()) { 3680 create_vm_init_agents(); 3681 } 3682 3683 // Initialize Threads state 3684 _thread_list = NULL; 3685 _number_of_threads = 0; 3686 _number_of_non_daemon_threads = 0; 3687 3688 // Initialize global data structures and create system classes in heap 3689 vm_init_globals(); 3690 3691 #if INCLUDE_JVMCI 3692 if (JVMCICounterSize > 0) { 3693 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3694 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3695 } else { 3696 JavaThread::_jvmci_old_thread_counters = NULL; 3697 } 3698 #endif // INCLUDE_JVMCI 3699 3700 // Attach the main thread to this os thread 3701 JavaThread* main_thread = new JavaThread(); 3702 main_thread->set_thread_state(_thread_in_vm); 3703 main_thread->initialize_thread_current(); 3704 // must do this before set_active_handles 3705 main_thread->record_stack_base_and_size(); 3706 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3707 3708 if (!main_thread->set_as_starting_thread()) { 3709 vm_shutdown_during_initialization( 3710 "Failed necessary internal allocation. Out of swap space"); 3711 main_thread->smr_delete(); 3712 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3713 return JNI_ENOMEM; 3714 } 3715 3716 // Enable guard page *after* os::create_main_thread(), otherwise it would 3717 // crash Linux VM, see notes in os_linux.cpp. 3718 main_thread->create_stack_guard_pages(); 3719 3720 // Initialize Java-Level synchronization subsystem 3721 ObjectMonitor::Initialize(); 3722 3723 // Initialize global modules 3724 jint status = init_globals(); 3725 if (status != JNI_OK) { 3726 main_thread->smr_delete(); 3727 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3728 return status; 3729 } 3730 3731 JFR_ONLY(Jfr::on_vm_init();) 3732 3733 // Should be done after the heap is fully created 3734 main_thread->cache_global_variables(); 3735 3736 HandleMark hm; 3737 3738 { MutexLocker mu(Threads_lock); 3739 Threads::add(main_thread); 3740 } 3741 3742 // Any JVMTI raw monitors entered in onload will transition into 3743 // real raw monitor. VM is setup enough here for raw monitor enter. 3744 JvmtiExport::transition_pending_onload_raw_monitors(); 3745 3746 // Create the VMThread 3747 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3748 3749 VMThread::create(); 3750 Thread* vmthread = VMThread::vm_thread(); 3751 3752 if (!os::create_thread(vmthread, os::vm_thread)) { 3753 vm_exit_during_initialization("Cannot create VM thread. " 3754 "Out of system resources."); 3755 } 3756 3757 // Wait for the VM thread to become ready, and VMThread::run to initialize 3758 // Monitors can have spurious returns, must always check another state flag 3759 { 3760 MutexLocker ml(Notify_lock); 3761 os::start_thread(vmthread); 3762 while (vmthread->active_handles() == NULL) { 3763 Notify_lock->wait(); 3764 } 3765 } 3766 } 3767 3768 assert(Universe::is_fully_initialized(), "not initialized"); 3769 if (VerifyDuringStartup) { 3770 // Make sure we're starting with a clean slate. 3771 VM_Verify verify_op; 3772 VMThread::execute(&verify_op); 3773 } 3774 3775 // We need this to update the java.vm.info property in case any flags used 3776 // to initially define it have been changed. This is needed for both CDS and 3777 // AOT, since UseSharedSpaces and UseAOT may be changed after java.vm.info 3778 // is initially computed. See Abstract_VM_Version::vm_info_string(). 3779 // This update must happen before we initialize the java classes, but 3780 // after any initialization logic that might modify the flags. 3781 Arguments::update_vm_info_property(VM_Version::vm_info_string()); 3782 3783 Thread* THREAD = Thread::current(); 3784 3785 // Always call even when there are not JVMTI environments yet, since environments 3786 // may be attached late and JVMTI must track phases of VM execution 3787 JvmtiExport::enter_early_start_phase(); 3788 3789 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3790 JvmtiExport::post_early_vm_start(); 3791 3792 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3793 3794 quicken_jni_functions(); 3795 3796 // No more stub generation allowed after that point. 3797 StubCodeDesc::freeze(); 3798 3799 // Set flag that basic initialization has completed. Used by exceptions and various 3800 // debug stuff, that does not work until all basic classes have been initialized. 3801 set_init_completed(); 3802 3803 LogConfiguration::post_initialize(); 3804 Metaspace::post_initialize(); 3805 3806 HOTSPOT_VM_INIT_END(); 3807 3808 // record VM initialization completion time 3809 #if INCLUDE_MANAGEMENT 3810 Management::record_vm_init_completed(); 3811 #endif // INCLUDE_MANAGEMENT 3812 3813 // Signal Dispatcher needs to be started before VMInit event is posted 3814 os::initialize_jdk_signal_support(CHECK_JNI_ERR); 3815 3816 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3817 if (!DisableAttachMechanism) { 3818 AttachListener::vm_start(); 3819 if (StartAttachListener || AttachListener::init_at_startup()) { 3820 AttachListener::init(); 3821 } 3822 } 3823 3824 // Launch -Xrun agents 3825 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3826 // back-end can launch with -Xdebug -Xrunjdwp. 3827 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3828 create_vm_init_libraries(); 3829 } 3830 3831 if (CleanChunkPoolAsync) { 3832 Chunk::start_chunk_pool_cleaner_task(); 3833 } 3834 3835 // initialize compiler(s) 3836 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3837 #if INCLUDE_JVMCI 3838 bool force_JVMCI_intialization = false; 3839 if (EnableJVMCI) { 3840 // Initialize JVMCI eagerly when it is explicitly requested. 3841 // Or when JVMCIPrintProperties is enabled. 3842 // The JVMCI Java initialization code will read this flag and 3843 // do the printing if it's set. 3844 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3845 3846 if (!force_JVMCI_intialization) { 3847 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3848 // compilations via JVMCI will not actually block until JVMCI is initialized. 3849 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3850 } 3851 } 3852 #endif 3853 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3854 // Postpone completion of compiler initialization to after JVMCI 3855 // is initialized to avoid timeouts of blocking compilations. 3856 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3857 CompileBroker::compilation_init_phase2(); 3858 } 3859 #endif 3860 3861 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3862 // It is done after compilers are initialized, because otherwise compilations of 3863 // signature polymorphic MH intrinsics can be missed 3864 // (see SystemDictionary::find_method_handle_intrinsic). 3865 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3866 3867 // This will initialize the module system. Only java.base classes can be 3868 // loaded until phase 2 completes 3869 call_initPhase2(CHECK_JNI_ERR); 3870 3871 // Always call even when there are not JVMTI environments yet, since environments 3872 // may be attached late and JVMTI must track phases of VM execution 3873 JvmtiExport::enter_start_phase(); 3874 3875 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3876 JvmtiExport::post_vm_start(); 3877 3878 // Final system initialization including security manager and system class loader 3879 call_initPhase3(CHECK_JNI_ERR); 3880 3881 // cache the system and platform class loaders 3882 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3883 3884 #if INCLUDE_CDS 3885 if (DumpSharedSpaces) { 3886 // capture the module path info from the ModuleEntryTable 3887 ClassLoader::initialize_module_path(THREAD); 3888 } 3889 #endif 3890 3891 #if INCLUDE_JVMCI 3892 if (force_JVMCI_intialization) { 3893 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3894 CompileBroker::compilation_init_phase2(); 3895 } 3896 #endif 3897 3898 // Always call even when there are not JVMTI environments yet, since environments 3899 // may be attached late and JVMTI must track phases of VM execution 3900 JvmtiExport::enter_live_phase(); 3901 3902 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3903 JvmtiExport::post_vm_initialized(); 3904 3905 JFR_ONLY(Jfr::on_vm_start();) 3906 3907 #if INCLUDE_MANAGEMENT 3908 Management::initialize(THREAD); 3909 3910 if (HAS_PENDING_EXCEPTION) { 3911 // management agent fails to start possibly due to 3912 // configuration problem and is responsible for printing 3913 // stack trace if appropriate. Simply exit VM. 3914 vm_exit(1); 3915 } 3916 #endif // INCLUDE_MANAGEMENT 3917 3918 if (MemProfiling) MemProfiler::engage(); 3919 StatSampler::engage(); 3920 if (CheckJNICalls) JniPeriodicChecker::engage(); 3921 3922 BiasedLocking::init(); 3923 3924 #if INCLUDE_RTM_OPT 3925 RTMLockingCounters::init(); 3926 #endif 3927 3928 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3929 call_postVMInitHook(THREAD); 3930 // The Java side of PostVMInitHook.run must deal with all 3931 // exceptions and provide means of diagnosis. 3932 if (HAS_PENDING_EXCEPTION) { 3933 CLEAR_PENDING_EXCEPTION; 3934 } 3935 } 3936 3937 { 3938 MutexLocker ml(PeriodicTask_lock); 3939 // Make sure the WatcherThread can be started by WatcherThread::start() 3940 // or by dynamic enrollment. 3941 WatcherThread::make_startable(); 3942 // Start up the WatcherThread if there are any periodic tasks 3943 // NOTE: All PeriodicTasks should be registered by now. If they 3944 // aren't, late joiners might appear to start slowly (we might 3945 // take a while to process their first tick). 3946 if (PeriodicTask::num_tasks() > 0) { 3947 WatcherThread::start(); 3948 } 3949 } 3950 3951 create_vm_timer.end(); 3952 #ifdef ASSERT 3953 _vm_complete = true; 3954 #endif 3955 3956 if (DumpSharedSpaces) { 3957 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3958 ShouldNotReachHere(); 3959 } 3960 3961 return JNI_OK; 3962 } 3963 3964 // type for the Agent_OnLoad and JVM_OnLoad entry points 3965 extern "C" { 3966 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3967 } 3968 // Find a command line agent library and return its entry point for 3969 // -agentlib: -agentpath: -Xrun 3970 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3971 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3972 const char *on_load_symbols[], 3973 size_t num_symbol_entries) { 3974 OnLoadEntry_t on_load_entry = NULL; 3975 void *library = NULL; 3976 3977 if (!agent->valid()) { 3978 char buffer[JVM_MAXPATHLEN]; 3979 char ebuf[1024] = ""; 3980 const char *name = agent->name(); 3981 const char *msg = "Could not find agent library "; 3982 3983 // First check to see if agent is statically linked into executable 3984 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3985 library = agent->os_lib(); 3986 } else if (agent->is_absolute_path()) { 3987 library = os::dll_load(name, ebuf, sizeof ebuf); 3988 if (library == NULL) { 3989 const char *sub_msg = " in absolute path, with error: "; 3990 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3991 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3992 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3993 // If we can't find the agent, exit. 3994 vm_exit_during_initialization(buf, NULL); 3995 FREE_C_HEAP_ARRAY(char, buf); 3996 } 3997 } else { 3998 // Try to load the agent from the standard dll directory 3999 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4000 name)) { 4001 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4002 } 4003 if (library == NULL) { // Try the library path directory. 4004 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4005 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4006 } 4007 if (library == NULL) { 4008 const char *sub_msg = " on the library path, with error: "; 4009 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4010 4011 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4012 strlen(ebuf) + strlen(sub_msg2) + 1; 4013 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4014 if (!agent->is_instrument_lib()) { 4015 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4016 } else { 4017 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4018 } 4019 // If we can't find the agent, exit. 4020 vm_exit_during_initialization(buf, NULL); 4021 FREE_C_HEAP_ARRAY(char, buf); 4022 } 4023 } 4024 } 4025 agent->set_os_lib(library); 4026 agent->set_valid(); 4027 } 4028 4029 // Find the OnLoad function. 4030 on_load_entry = 4031 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4032 false, 4033 on_load_symbols, 4034 num_symbol_entries)); 4035 return on_load_entry; 4036 } 4037 4038 // Find the JVM_OnLoad entry point 4039 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4040 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4041 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4042 } 4043 4044 // Find the Agent_OnLoad entry point 4045 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4046 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4047 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4048 } 4049 4050 // For backwards compatibility with -Xrun 4051 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4052 // treated like -agentpath: 4053 // Must be called before agent libraries are created 4054 void Threads::convert_vm_init_libraries_to_agents() { 4055 AgentLibrary* agent; 4056 AgentLibrary* next; 4057 4058 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4059 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4060 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4061 4062 // If there is an JVM_OnLoad function it will get called later, 4063 // otherwise see if there is an Agent_OnLoad 4064 if (on_load_entry == NULL) { 4065 on_load_entry = lookup_agent_on_load(agent); 4066 if (on_load_entry != NULL) { 4067 // switch it to the agent list -- so that Agent_OnLoad will be called, 4068 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4069 Arguments::convert_library_to_agent(agent); 4070 } else { 4071 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4072 } 4073 } 4074 } 4075 } 4076 4077 // Create agents for -agentlib: -agentpath: and converted -Xrun 4078 // Invokes Agent_OnLoad 4079 // Called very early -- before JavaThreads exist 4080 void Threads::create_vm_init_agents() { 4081 extern struct JavaVM_ main_vm; 4082 AgentLibrary* agent; 4083 4084 JvmtiExport::enter_onload_phase(); 4085 4086 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4087 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4088 4089 if (on_load_entry != NULL) { 4090 // Invoke the Agent_OnLoad function 4091 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4092 if (err != JNI_OK) { 4093 vm_exit_during_initialization("agent library failed to init", agent->name()); 4094 } 4095 } else { 4096 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4097 } 4098 } 4099 JvmtiExport::enter_primordial_phase(); 4100 } 4101 4102 extern "C" { 4103 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4104 } 4105 4106 void Threads::shutdown_vm_agents() { 4107 // Send any Agent_OnUnload notifications 4108 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4109 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4110 extern struct JavaVM_ main_vm; 4111 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4112 4113 // Find the Agent_OnUnload function. 4114 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4115 os::find_agent_function(agent, 4116 false, 4117 on_unload_symbols, 4118 num_symbol_entries)); 4119 4120 // Invoke the Agent_OnUnload function 4121 if (unload_entry != NULL) { 4122 JavaThread* thread = JavaThread::current(); 4123 ThreadToNativeFromVM ttn(thread); 4124 HandleMark hm(thread); 4125 (*unload_entry)(&main_vm); 4126 } 4127 } 4128 } 4129 4130 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4131 // Invokes JVM_OnLoad 4132 void Threads::create_vm_init_libraries() { 4133 extern struct JavaVM_ main_vm; 4134 AgentLibrary* agent; 4135 4136 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4137 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4138 4139 if (on_load_entry != NULL) { 4140 // Invoke the JVM_OnLoad function 4141 JavaThread* thread = JavaThread::current(); 4142 ThreadToNativeFromVM ttn(thread); 4143 HandleMark hm(thread); 4144 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4145 if (err != JNI_OK) { 4146 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4147 } 4148 } else { 4149 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4150 } 4151 } 4152 } 4153 4154 4155 // Last thread running calls java.lang.Shutdown.shutdown() 4156 void JavaThread::invoke_shutdown_hooks() { 4157 HandleMark hm(this); 4158 4159 // We could get here with a pending exception, if so clear it now. 4160 if (this->has_pending_exception()) { 4161 this->clear_pending_exception(); 4162 } 4163 4164 EXCEPTION_MARK; 4165 Klass* shutdown_klass = 4166 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4167 THREAD); 4168 if (shutdown_klass != NULL) { 4169 // SystemDictionary::resolve_or_null will return null if there was 4170 // an exception. If we cannot load the Shutdown class, just don't 4171 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4172 // won't be run. Note that if a shutdown hook was registered, 4173 // the Shutdown class would have already been loaded 4174 // (Runtime.addShutdownHook will load it). 4175 JavaValue result(T_VOID); 4176 JavaCalls::call_static(&result, 4177 shutdown_klass, 4178 vmSymbols::shutdown_method_name(), 4179 vmSymbols::void_method_signature(), 4180 THREAD); 4181 } 4182 CLEAR_PENDING_EXCEPTION; 4183 } 4184 4185 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4186 // the program falls off the end of main(). Another VM exit path is through 4187 // vm_exit() when the program calls System.exit() to return a value or when 4188 // there is a serious error in VM. The two shutdown paths are not exactly 4189 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4190 // and VM_Exit op at VM level. 4191 // 4192 // Shutdown sequence: 4193 // + Shutdown native memory tracking if it is on 4194 // + Wait until we are the last non-daemon thread to execute 4195 // <-- every thing is still working at this moment --> 4196 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4197 // shutdown hooks 4198 // + Call before_exit(), prepare for VM exit 4199 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4200 // currently the only user of this mechanism is File.deleteOnExit()) 4201 // > stop StatSampler, watcher thread, CMS threads, 4202 // post thread end and vm death events to JVMTI, 4203 // stop signal thread 4204 // + Call JavaThread::exit(), it will: 4205 // > release JNI handle blocks, remove stack guard pages 4206 // > remove this thread from Threads list 4207 // <-- no more Java code from this thread after this point --> 4208 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4209 // the compiler threads at safepoint 4210 // <-- do not use anything that could get blocked by Safepoint --> 4211 // + Disable tracing at JNI/JVM barriers 4212 // + Set _vm_exited flag for threads that are still running native code 4213 // + Call exit_globals() 4214 // > deletes tty 4215 // > deletes PerfMemory resources 4216 // + Delete this thread 4217 // + Return to caller 4218 4219 bool Threads::destroy_vm() { 4220 JavaThread* thread = JavaThread::current(); 4221 4222 #ifdef ASSERT 4223 _vm_complete = false; 4224 #endif 4225 // Wait until we are the last non-daemon thread to execute 4226 { MutexLocker nu(Threads_lock); 4227 while (Threads::number_of_non_daemon_threads() > 1) 4228 // This wait should make safepoint checks, wait without a timeout, 4229 // and wait as a suspend-equivalent condition. 4230 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4231 Mutex::_as_suspend_equivalent_flag); 4232 } 4233 4234 EventShutdown e; 4235 if (e.should_commit()) { 4236 e.set_reason("No remaining non-daemon Java threads"); 4237 e.commit(); 4238 } 4239 4240 // Hang forever on exit if we are reporting an error. 4241 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4242 os::infinite_sleep(); 4243 } 4244 os::wait_for_keypress_at_exit(); 4245 4246 // run Java level shutdown hooks 4247 thread->invoke_shutdown_hooks(); 4248 4249 before_exit(thread); 4250 4251 thread->exit(true); 4252 // thread will never call smr_delete, instead of implicit cancel 4253 // in wait_for_vm_thread_exit we do it explicit. 4254 thread->cancel_handshake(); 4255 4256 // Stop VM thread. 4257 { 4258 // 4945125 The vm thread comes to a safepoint during exit. 4259 // GC vm_operations can get caught at the safepoint, and the 4260 // heap is unparseable if they are caught. Grab the Heap_lock 4261 // to prevent this. The GC vm_operations will not be able to 4262 // queue until after the vm thread is dead. After this point, 4263 // we'll never emerge out of the safepoint before the VM exits. 4264 4265 MutexLocker ml(Heap_lock); 4266 4267 VMThread::wait_for_vm_thread_exit(); 4268 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4269 VMThread::destroy(); 4270 } 4271 4272 // Now, all Java threads are gone except daemon threads. Daemon threads 4273 // running Java code or in VM are stopped by the Safepoint. However, 4274 // daemon threads executing native code are still running. But they 4275 // will be stopped at native=>Java/VM barriers. Note that we can't 4276 // simply kill or suspend them, as it is inherently deadlock-prone. 4277 4278 VM_Exit::set_vm_exited(); 4279 4280 // Clean up ideal graph printers after the VMThread has started 4281 // the final safepoint which will block all the Compiler threads. 4282 // Note that this Thread has already logically exited so the 4283 // clean_up() function's use of a JavaThreadIteratorWithHandle 4284 // would be a problem except set_vm_exited() has remembered the 4285 // shutdown thread which is granted a policy exception. 4286 #if defined(COMPILER2) && !defined(PRODUCT) 4287 IdealGraphPrinter::clean_up(); 4288 #endif 4289 4290 notify_vm_shutdown(); 4291 4292 // exit_globals() will delete tty 4293 exit_globals(); 4294 4295 // We are after VM_Exit::set_vm_exited() so we can't call 4296 // thread->smr_delete() or we will block on the Threads_lock. 4297 // Deleting the shutdown thread here is safe because another 4298 // JavaThread cannot have an active ThreadsListHandle for 4299 // this JavaThread. 4300 delete thread; 4301 4302 #if INCLUDE_JVMCI 4303 if (JVMCICounterSize > 0) { 4304 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4305 } 4306 #endif 4307 4308 LogConfiguration::finalize(); 4309 4310 return true; 4311 } 4312 4313 4314 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4315 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4316 return is_supported_jni_version(version); 4317 } 4318 4319 4320 jboolean Threads::is_supported_jni_version(jint version) { 4321 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4322 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4323 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4324 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4325 if (version == JNI_VERSION_9) return JNI_TRUE; 4326 if (version == JNI_VERSION_10) return JNI_TRUE; 4327 return JNI_FALSE; 4328 } 4329 4330 4331 void Threads::add(JavaThread* p, bool force_daemon) { 4332 // The threads lock must be owned at this point 4333 assert_locked_or_safepoint(Threads_lock); 4334 4335 BarrierSet::barrier_set()->on_thread_attach(p); 4336 4337 p->set_next(_thread_list); 4338 _thread_list = p; 4339 4340 // Once a JavaThread is added to the Threads list, smr_delete() has 4341 // to be used to delete it. Otherwise we can just delete it directly. 4342 p->set_on_thread_list(); 4343 4344 _number_of_threads++; 4345 oop threadObj = p->threadObj(); 4346 bool daemon = true; 4347 // Bootstrapping problem: threadObj can be null for initial 4348 // JavaThread (or for threads attached via JNI) 4349 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4350 _number_of_non_daemon_threads++; 4351 daemon = false; 4352 } 4353 4354 ThreadService::add_thread(p, daemon); 4355 4356 // Maintain fast thread list 4357 ThreadsSMRSupport::add_thread(p); 4358 4359 // Possible GC point. 4360 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4361 } 4362 4363 void Threads::remove(JavaThread* p) { 4364 4365 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4366 ObjectSynchronizer::omFlush(p); 4367 4368 // Extra scope needed for Thread_lock, so we can check 4369 // that we do not remove thread without safepoint code notice 4370 { MutexLocker ml(Threads_lock); 4371 4372 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4373 4374 // Maintain fast thread list 4375 ThreadsSMRSupport::remove_thread(p); 4376 4377 JavaThread* current = _thread_list; 4378 JavaThread* prev = NULL; 4379 4380 while (current != p) { 4381 prev = current; 4382 current = current->next(); 4383 } 4384 4385 if (prev) { 4386 prev->set_next(current->next()); 4387 } else { 4388 _thread_list = p->next(); 4389 } 4390 4391 _number_of_threads--; 4392 oop threadObj = p->threadObj(); 4393 bool daemon = true; 4394 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4395 _number_of_non_daemon_threads--; 4396 daemon = false; 4397 4398 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4399 // on destroy_vm will wake up. 4400 if (number_of_non_daemon_threads() == 1) { 4401 Threads_lock->notify_all(); 4402 } 4403 } 4404 ThreadService::remove_thread(p, daemon); 4405 4406 // Make sure that safepoint code disregard this thread. This is needed since 4407 // the thread might mess around with locks after this point. This can cause it 4408 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4409 // of this thread since it is removed from the queue. 4410 p->set_terminated_value(); 4411 } // unlock Threads_lock 4412 4413 // Since Events::log uses a lock, we grab it outside the Threads_lock 4414 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4415 } 4416 4417 // Operations on the Threads list for GC. These are not explicitly locked, 4418 // but the garbage collector must provide a safe context for them to run. 4419 // In particular, these things should never be called when the Threads_lock 4420 // is held by some other thread. (Note: the Safepoint abstraction also 4421 // uses the Threads_lock to guarantee this property. It also makes sure that 4422 // all threads gets blocked when exiting or starting). 4423 4424 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4425 ALL_JAVA_THREADS(p) { 4426 p->oops_do(f, cf); 4427 } 4428 VMThread::vm_thread()->oops_do(f, cf); 4429 } 4430 4431 void Threads::change_thread_claim_parity() { 4432 // Set the new claim parity. 4433 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4434 "Not in range."); 4435 _thread_claim_parity++; 4436 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4437 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4438 "Not in range."); 4439 } 4440 4441 #ifdef ASSERT 4442 void Threads::assert_all_threads_claimed() { 4443 ALL_JAVA_THREADS(p) { 4444 const int thread_parity = p->oops_do_parity(); 4445 assert((thread_parity == _thread_claim_parity), 4446 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4447 } 4448 VMThread* vmt = VMThread::vm_thread(); 4449 const int thread_parity = vmt->oops_do_parity(); 4450 assert((thread_parity == _thread_claim_parity), 4451 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4452 } 4453 #endif // ASSERT 4454 4455 class ParallelOopsDoThreadClosure : public ThreadClosure { 4456 private: 4457 OopClosure* _f; 4458 CodeBlobClosure* _cf; 4459 public: 4460 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4461 void do_thread(Thread* t) { 4462 t->oops_do(_f, _cf); 4463 } 4464 }; 4465 4466 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4467 ParallelOopsDoThreadClosure tc(f, cf); 4468 possibly_parallel_threads_do(is_par, &tc); 4469 } 4470 4471 void Threads::nmethods_do(CodeBlobClosure* cf) { 4472 ALL_JAVA_THREADS(p) { 4473 // This is used by the code cache sweeper to mark nmethods that are active 4474 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4475 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4476 if(!p->is_Code_cache_sweeper_thread()) { 4477 p->nmethods_do(cf); 4478 } 4479 } 4480 } 4481 4482 void Threads::metadata_do(void f(Metadata*)) { 4483 ALL_JAVA_THREADS(p) { 4484 p->metadata_do(f); 4485 } 4486 } 4487 4488 class ThreadHandlesClosure : public ThreadClosure { 4489 void (*_f)(Metadata*); 4490 public: 4491 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4492 virtual void do_thread(Thread* thread) { 4493 thread->metadata_handles_do(_f); 4494 } 4495 }; 4496 4497 void Threads::metadata_handles_do(void f(Metadata*)) { 4498 // Only walk the Handles in Thread. 4499 ThreadHandlesClosure handles_closure(f); 4500 threads_do(&handles_closure); 4501 } 4502 4503 void Threads::deoptimized_wrt_marked_nmethods() { 4504 ALL_JAVA_THREADS(p) { 4505 p->deoptimized_wrt_marked_nmethods(); 4506 } 4507 } 4508 4509 4510 // Get count Java threads that are waiting to enter the specified monitor. 4511 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4512 int count, 4513 address monitor) { 4514 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4515 4516 int i = 0; 4517 DO_JAVA_THREADS(t_list, p) { 4518 if (!p->can_call_java()) continue; 4519 4520 address pending = (address)p->current_pending_monitor(); 4521 if (pending == monitor) { // found a match 4522 if (i < count) result->append(p); // save the first count matches 4523 i++; 4524 } 4525 } 4526 4527 return result; 4528 } 4529 4530 4531 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4532 address owner) { 4533 // NULL owner means not locked so we can skip the search 4534 if (owner == NULL) return NULL; 4535 4536 DO_JAVA_THREADS(t_list, p) { 4537 // first, see if owner is the address of a Java thread 4538 if (owner == (address)p) return p; 4539 } 4540 4541 // Cannot assert on lack of success here since this function may be 4542 // used by code that is trying to report useful problem information 4543 // like deadlock detection. 4544 if (UseHeavyMonitors) return NULL; 4545 4546 // If we didn't find a matching Java thread and we didn't force use of 4547 // heavyweight monitors, then the owner is the stack address of the 4548 // Lock Word in the owning Java thread's stack. 4549 // 4550 JavaThread* the_owner = NULL; 4551 DO_JAVA_THREADS(t_list, q) { 4552 if (q->is_lock_owned(owner)) { 4553 the_owner = q; 4554 break; 4555 } 4556 } 4557 4558 // cannot assert on lack of success here; see above comment 4559 return the_owner; 4560 } 4561 4562 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4563 void Threads::print_on(outputStream* st, bool print_stacks, 4564 bool internal_format, bool print_concurrent_locks, 4565 bool print_extended_info) { 4566 char buf[32]; 4567 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4568 4569 st->print_cr("Full thread dump %s (%s %s):", 4570 Abstract_VM_Version::vm_name(), 4571 Abstract_VM_Version::vm_release(), 4572 Abstract_VM_Version::vm_info_string()); 4573 st->cr(); 4574 4575 #if INCLUDE_SERVICES 4576 // Dump concurrent locks 4577 ConcurrentLocksDump concurrent_locks; 4578 if (print_concurrent_locks) { 4579 concurrent_locks.dump_at_safepoint(); 4580 } 4581 #endif // INCLUDE_SERVICES 4582 4583 ThreadsSMRSupport::print_info_on(st); 4584 st->cr(); 4585 4586 ALL_JAVA_THREADS(p) { 4587 ResourceMark rm; 4588 p->print_on(st, print_extended_info); 4589 if (print_stacks) { 4590 if (internal_format) { 4591 p->trace_stack(); 4592 } else { 4593 p->print_stack_on(st); 4594 } 4595 } 4596 st->cr(); 4597 #if INCLUDE_SERVICES 4598 if (print_concurrent_locks) { 4599 concurrent_locks.print_locks_on(p, st); 4600 } 4601 #endif // INCLUDE_SERVICES 4602 } 4603 4604 VMThread::vm_thread()->print_on(st); 4605 st->cr(); 4606 Universe::heap()->print_gc_threads_on(st); 4607 WatcherThread* wt = WatcherThread::watcher_thread(); 4608 if (wt != NULL) { 4609 wt->print_on(st); 4610 st->cr(); 4611 } 4612 4613 st->flush(); 4614 } 4615 4616 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4617 int buflen, bool* found_current) { 4618 if (this_thread != NULL) { 4619 bool is_current = (current == this_thread); 4620 *found_current = *found_current || is_current; 4621 st->print("%s", is_current ? "=>" : " "); 4622 4623 st->print(PTR_FORMAT, p2i(this_thread)); 4624 st->print(" "); 4625 this_thread->print_on_error(st, buf, buflen); 4626 st->cr(); 4627 } 4628 } 4629 4630 class PrintOnErrorClosure : public ThreadClosure { 4631 outputStream* _st; 4632 Thread* _current; 4633 char* _buf; 4634 int _buflen; 4635 bool* _found_current; 4636 public: 4637 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4638 int buflen, bool* found_current) : 4639 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4640 4641 virtual void do_thread(Thread* thread) { 4642 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4643 } 4644 }; 4645 4646 // Threads::print_on_error() is called by fatal error handler. It's possible 4647 // that VM is not at safepoint and/or current thread is inside signal handler. 4648 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4649 // memory (even in resource area), it might deadlock the error handler. 4650 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4651 int buflen) { 4652 ThreadsSMRSupport::print_info_on(st); 4653 st->cr(); 4654 4655 bool found_current = false; 4656 st->print_cr("Java Threads: ( => current thread )"); 4657 ALL_JAVA_THREADS(thread) { 4658 print_on_error(thread, st, current, buf, buflen, &found_current); 4659 } 4660 st->cr(); 4661 4662 st->print_cr("Other Threads:"); 4663 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4664 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4665 4666 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4667 Universe::heap()->gc_threads_do(&print_closure); 4668 4669 if (!found_current) { 4670 st->cr(); 4671 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4672 current->print_on_error(st, buf, buflen); 4673 st->cr(); 4674 } 4675 st->cr(); 4676 4677 st->print_cr("Threads with active compile tasks:"); 4678 print_threads_compiling(st, buf, buflen); 4679 } 4680 4681 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4682 ALL_JAVA_THREADS(thread) { 4683 if (thread->is_Compiler_thread()) { 4684 CompilerThread* ct = (CompilerThread*) thread; 4685 4686 // Keep task in local variable for NULL check. 4687 // ct->_task might be set to NULL by concurring compiler thread 4688 // because it completed the compilation. The task is never freed, 4689 // though, just returned to a free list. 4690 CompileTask* task = ct->task(); 4691 if (task != NULL) { 4692 thread->print_name_on_error(st, buf, buflen); 4693 task->print(st, NULL, true, true); 4694 } 4695 } 4696 } 4697 } 4698 4699 4700 // Internal SpinLock and Mutex 4701 // Based on ParkEvent 4702 4703 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4704 // 4705 // We employ SpinLocks _only for low-contention, fixed-length 4706 // short-duration critical sections where we're concerned 4707 // about native mutex_t or HotSpot Mutex:: latency. 4708 // The mux construct provides a spin-then-block mutual exclusion 4709 // mechanism. 4710 // 4711 // Testing has shown that contention on the ListLock guarding gFreeList 4712 // is common. If we implement ListLock as a simple SpinLock it's common 4713 // for the JVM to devolve to yielding with little progress. This is true 4714 // despite the fact that the critical sections protected by ListLock are 4715 // extremely short. 4716 // 4717 // TODO-FIXME: ListLock should be of type SpinLock. 4718 // We should make this a 1st-class type, integrated into the lock 4719 // hierarchy as leaf-locks. Critically, the SpinLock structure 4720 // should have sufficient padding to avoid false-sharing and excessive 4721 // cache-coherency traffic. 4722 4723 4724 typedef volatile int SpinLockT; 4725 4726 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4727 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4728 return; // normal fast-path return 4729 } 4730 4731 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4732 int ctr = 0; 4733 int Yields = 0; 4734 for (;;) { 4735 while (*adr != 0) { 4736 ++ctr; 4737 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4738 if (Yields > 5) { 4739 os::naked_short_sleep(1); 4740 } else { 4741 os::naked_yield(); 4742 ++Yields; 4743 } 4744 } else { 4745 SpinPause(); 4746 } 4747 } 4748 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4749 } 4750 } 4751 4752 void Thread::SpinRelease(volatile int * adr) { 4753 assert(*adr != 0, "invariant"); 4754 OrderAccess::fence(); // guarantee at least release consistency. 4755 // Roach-motel semantics. 4756 // It's safe if subsequent LDs and STs float "up" into the critical section, 4757 // but prior LDs and STs within the critical section can't be allowed 4758 // to reorder or float past the ST that releases the lock. 4759 // Loads and stores in the critical section - which appear in program 4760 // order before the store that releases the lock - must also appear 4761 // before the store that releases the lock in memory visibility order. 4762 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4763 // the ST of 0 into the lock-word which releases the lock, so fence 4764 // more than covers this on all platforms. 4765 *adr = 0; 4766 } 4767 4768 // muxAcquire and muxRelease: 4769 // 4770 // * muxAcquire and muxRelease support a single-word lock-word construct. 4771 // The LSB of the word is set IFF the lock is held. 4772 // The remainder of the word points to the head of a singly-linked list 4773 // of threads blocked on the lock. 4774 // 4775 // * The current implementation of muxAcquire-muxRelease uses its own 4776 // dedicated Thread._MuxEvent instance. If we're interested in 4777 // minimizing the peak number of extant ParkEvent instances then 4778 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4779 // as certain invariants were satisfied. Specifically, care would need 4780 // to be taken with regards to consuming unpark() "permits". 4781 // A safe rule of thumb is that a thread would never call muxAcquire() 4782 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4783 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4784 // consume an unpark() permit intended for monitorenter, for instance. 4785 // One way around this would be to widen the restricted-range semaphore 4786 // implemented in park(). Another alternative would be to provide 4787 // multiple instances of the PlatformEvent() for each thread. One 4788 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4789 // 4790 // * Usage: 4791 // -- Only as leaf locks 4792 // -- for short-term locking only as muxAcquire does not perform 4793 // thread state transitions. 4794 // 4795 // Alternatives: 4796 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4797 // but with parking or spin-then-park instead of pure spinning. 4798 // * Use Taura-Oyama-Yonenzawa locks. 4799 // * It's possible to construct a 1-0 lock if we encode the lockword as 4800 // (List,LockByte). Acquire will CAS the full lockword while Release 4801 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4802 // acquiring threads use timers (ParkTimed) to detect and recover from 4803 // the stranding window. Thread/Node structures must be aligned on 256-byte 4804 // boundaries by using placement-new. 4805 // * Augment MCS with advisory back-link fields maintained with CAS(). 4806 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4807 // The validity of the backlinks must be ratified before we trust the value. 4808 // If the backlinks are invalid the exiting thread must back-track through the 4809 // the forward links, which are always trustworthy. 4810 // * Add a successor indication. The LockWord is currently encoded as 4811 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4812 // to provide the usual futile-wakeup optimization. 4813 // See RTStt for details. 4814 // 4815 4816 4817 const intptr_t LOCKBIT = 1; 4818 4819 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4820 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4821 if (w == 0) return; 4822 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4823 return; 4824 } 4825 4826 ParkEvent * const Self = Thread::current()->_MuxEvent; 4827 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4828 for (;;) { 4829 int its = (os::is_MP() ? 100 : 0) + 1; 4830 4831 // Optional spin phase: spin-then-park strategy 4832 while (--its >= 0) { 4833 w = *Lock; 4834 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4835 return; 4836 } 4837 } 4838 4839 Self->reset(); 4840 Self->OnList = intptr_t(Lock); 4841 // The following fence() isn't _strictly necessary as the subsequent 4842 // CAS() both serializes execution and ratifies the fetched *Lock value. 4843 OrderAccess::fence(); 4844 for (;;) { 4845 w = *Lock; 4846 if ((w & LOCKBIT) == 0) { 4847 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4848 Self->OnList = 0; // hygiene - allows stronger asserts 4849 return; 4850 } 4851 continue; // Interference -- *Lock changed -- Just retry 4852 } 4853 assert(w & LOCKBIT, "invariant"); 4854 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4855 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4856 } 4857 4858 while (Self->OnList != 0) { 4859 Self->park(); 4860 } 4861 } 4862 } 4863 4864 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4865 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4866 if (w == 0) return; 4867 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4868 return; 4869 } 4870 4871 ParkEvent * ReleaseAfter = NULL; 4872 if (ev == NULL) { 4873 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4874 } 4875 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4876 for (;;) { 4877 guarantee(ev->OnList == 0, "invariant"); 4878 int its = (os::is_MP() ? 100 : 0) + 1; 4879 4880 // Optional spin phase: spin-then-park strategy 4881 while (--its >= 0) { 4882 w = *Lock; 4883 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4884 if (ReleaseAfter != NULL) { 4885 ParkEvent::Release(ReleaseAfter); 4886 } 4887 return; 4888 } 4889 } 4890 4891 ev->reset(); 4892 ev->OnList = intptr_t(Lock); 4893 // The following fence() isn't _strictly necessary as the subsequent 4894 // CAS() both serializes execution and ratifies the fetched *Lock value. 4895 OrderAccess::fence(); 4896 for (;;) { 4897 w = *Lock; 4898 if ((w & LOCKBIT) == 0) { 4899 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4900 ev->OnList = 0; 4901 // We call ::Release while holding the outer lock, thus 4902 // artificially lengthening the critical section. 4903 // Consider deferring the ::Release() until the subsequent unlock(), 4904 // after we've dropped the outer lock. 4905 if (ReleaseAfter != NULL) { 4906 ParkEvent::Release(ReleaseAfter); 4907 } 4908 return; 4909 } 4910 continue; // Interference -- *Lock changed -- Just retry 4911 } 4912 assert(w & LOCKBIT, "invariant"); 4913 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4914 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4915 } 4916 4917 while (ev->OnList != 0) { 4918 ev->park(); 4919 } 4920 } 4921 } 4922 4923 // Release() must extract a successor from the list and then wake that thread. 4924 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4925 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4926 // Release() would : 4927 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4928 // (B) Extract a successor from the private list "in-hand" 4929 // (C) attempt to CAS() the residual back into *Lock over null. 4930 // If there were any newly arrived threads and the CAS() would fail. 4931 // In that case Release() would detach the RATs, re-merge the list in-hand 4932 // with the RATs and repeat as needed. Alternately, Release() might 4933 // detach and extract a successor, but then pass the residual list to the wakee. 4934 // The wakee would be responsible for reattaching and remerging before it 4935 // competed for the lock. 4936 // 4937 // Both "pop" and DMR are immune from ABA corruption -- there can be 4938 // multiple concurrent pushers, but only one popper or detacher. 4939 // This implementation pops from the head of the list. This is unfair, 4940 // but tends to provide excellent throughput as hot threads remain hot. 4941 // (We wake recently run threads first). 4942 // 4943 // All paths through muxRelease() will execute a CAS. 4944 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4945 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4946 // executed within the critical section are complete and globally visible before the 4947 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4948 void Thread::muxRelease(volatile intptr_t * Lock) { 4949 for (;;) { 4950 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4951 assert(w & LOCKBIT, "invariant"); 4952 if (w == LOCKBIT) return; 4953 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4954 assert(List != NULL, "invariant"); 4955 assert(List->OnList == intptr_t(Lock), "invariant"); 4956 ParkEvent * const nxt = List->ListNext; 4957 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4958 4959 // The following CAS() releases the lock and pops the head element. 4960 // The CAS() also ratifies the previously fetched lock-word value. 4961 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4962 continue; 4963 } 4964 List->OnList = 0; 4965 OrderAccess::fence(); 4966 List->unpark(); 4967 return; 4968 } 4969 } 4970 4971 4972 void Threads::verify() { 4973 ALL_JAVA_THREADS(p) { 4974 p->verify(); 4975 } 4976 VMThread* thread = VMThread::vm_thread(); 4977 if (thread != NULL) thread->verify(); 4978 } --- EOF ---