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 "jvmtifiles/jvmtiEnv.hpp" 44 #include "logging/log.hpp" 45 #include "logging/logConfiguration.hpp" 46 #include "logging/logStream.hpp" 47 #include "memory/allocation.inline.hpp" 48 #include "memory/metaspaceShared.hpp" 49 #include "memory/oopFactory.hpp" 50 #include "memory/resourceArea.hpp" 51 #include "memory/universe.hpp" 52 #include "oops/access.inline.hpp" 53 #include "oops/instanceKlass.hpp" 54 #include "oops/objArrayOop.hpp" 55 #include "oops/oop.inline.hpp" 56 #include "oops/symbol.hpp" 57 #include "oops/typeArrayOop.inline.hpp" 58 #include "oops/verifyOopClosure.hpp" 59 #include "prims/jvm_misc.hpp" 60 #include "prims/jvmtiExport.hpp" 61 #include "prims/jvmtiThreadState.hpp" 62 #include "prims/privilegedStack.hpp" 63 #include "runtime/arguments.hpp" 64 #include "runtime/atomic.hpp" 65 #include "runtime/biasedLocking.hpp" 66 #include "runtime/commandLineFlagConstraintList.hpp" 67 #include "runtime/commandLineFlagWriteableList.hpp" 68 #include "runtime/commandLineFlagRangeList.hpp" 69 #include "runtime/deoptimization.hpp" 70 #include "runtime/frame.inline.hpp" 71 #include "runtime/globals.hpp" 72 #include "runtime/handshake.hpp" 73 #include "runtime/init.hpp" 74 #include "runtime/interfaceSupport.inline.hpp" 75 #include "runtime/java.hpp" 76 #include "runtime/javaCalls.hpp" 77 #include "runtime/jniHandles.inline.hpp" 78 #include "runtime/jniPeriodicChecker.hpp" 79 #include "runtime/memprofiler.hpp" 80 #include "runtime/mutexLocker.hpp" 81 #include "runtime/objectMonitor.hpp" 82 #include "runtime/orderAccess.inline.hpp" 83 #include "runtime/osThread.hpp" 84 #include "runtime/prefetch.inline.hpp" 85 #include "runtime/safepoint.hpp" 86 #include "runtime/safepointMechanism.inline.hpp" 87 #include "runtime/sharedRuntime.hpp" 88 #include "runtime/statSampler.hpp" 89 #include "runtime/stubRoutines.hpp" 90 #include "runtime/sweeper.hpp" 91 #include "runtime/task.hpp" 92 #include "runtime/thread.inline.hpp" 93 #include "runtime/threadCritical.hpp" 94 #include "runtime/threadSMR.inline.hpp" 95 #include "runtime/timer.hpp" 96 #include "runtime/timerTrace.hpp" 97 #include "runtime/vframe.inline.hpp" 98 #include "runtime/vframeArray.hpp" 99 #include "runtime/vframe_hp.hpp" 100 #include "runtime/vmThread.hpp" 101 #include "runtime/vm_operations.hpp" 102 #include "runtime/vm_version.hpp" 103 #include "services/attachListener.hpp" 104 #include "services/management.hpp" 105 #include "services/memTracker.hpp" 106 #include "services/threadService.hpp" 107 #include "trace/traceMacros.hpp" 108 #include "trace/tracing.hpp" 109 #include "trace/tracingExport.hpp" 110 #include "utilities/align.hpp" 111 #include "utilities/copy.hpp" 112 #include "utilities/defaultStream.hpp" 113 #include "utilities/dtrace.hpp" 114 #include "utilities/events.hpp" 115 #include "utilities/macros.hpp" 116 #include "utilities/preserveException.hpp" 117 #include "utilities/vmError.hpp" 118 #if INCLUDE_ALL_GCS 119 #include "gc/cms/concurrentMarkSweepThread.hpp" 120 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" 121 #include "gc/parallel/pcTasks.hpp" 122 #endif // INCLUDE_ALL_GCS 123 #if INCLUDE_JVMCI 124 #include "jvmci/jvmciCompiler.hpp" 125 #include "jvmci/jvmciRuntime.hpp" 126 #include "logging/logHandle.hpp" 127 #endif 128 #ifdef COMPILER1 129 #include "c1/c1_Compiler.hpp" 130 #endif 131 #ifdef COMPILER2 132 #include "opto/c2compiler.hpp" 133 #include "opto/idealGraphPrinter.hpp" 134 #endif 135 #if INCLUDE_RTM_OPT 136 #include "runtime/rtmLocking.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 // Class hierarchy 173 // - Thread 174 // - VMThread 175 // - WatcherThread 176 // - ConcurrentMarkSweepThread 177 // - JavaThread 178 // - CompilerThread 179 180 // ======= Thread ======== 181 // Support for forcing alignment of thread objects for biased locking 182 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 183 if (UseBiasedLocking) { 184 const int alignment = markOopDesc::biased_lock_alignment; 185 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 186 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 187 : AllocateHeap(aligned_size, flags, CURRENT_PC, 188 AllocFailStrategy::RETURN_NULL); 189 void* aligned_addr = align_up(real_malloc_addr, alignment); 190 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 191 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 192 "JavaThread alignment code overflowed allocated storage"); 193 if (aligned_addr != real_malloc_addr) { 194 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 195 p2i(real_malloc_addr), 196 p2i(aligned_addr)); 197 } 198 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 199 return aligned_addr; 200 } else { 201 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 202 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 203 } 204 } 205 206 void Thread::operator delete(void* p) { 207 if (UseBiasedLocking) { 208 FreeHeap(((Thread*) p)->_real_malloc_address); 209 } else { 210 FreeHeap(p); 211 } 212 } 213 214 void JavaThread::smr_delete() { 215 if (_on_thread_list) { 216 ThreadsSMRSupport::smr_delete(this); 217 } else { 218 delete this; 219 } 220 } 221 222 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 223 // JavaThread 224 225 226 Thread::Thread() { 227 // stack and get_thread 228 set_stack_base(NULL); 229 set_stack_size(0); 230 set_self_raw_id(0); 231 set_lgrp_id(-1); 232 DEBUG_ONLY(clear_suspendible_thread();) 233 234 // allocated data structures 235 set_osthread(NULL); 236 set_resource_area(new (mtThread)ResourceArea()); 237 DEBUG_ONLY(_current_resource_mark = NULL;) 238 set_handle_area(new (mtThread) HandleArea(NULL)); 239 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 240 set_active_handles(NULL); 241 set_free_handle_block(NULL); 242 set_last_handle_mark(NULL); 243 244 _statistic_info.setStartTime(os::javaTimeMillis()); 245 _statistic_info.setDefineClassCount(0); 246 247 // This initial value ==> never claimed. 248 _oops_do_parity = 0; 249 _threads_hazard_ptr = NULL; 250 _nested_threads_hazard_ptr = NULL; 251 _nested_threads_hazard_ptr_cnt = 0; 252 _rcu_counter = 0; 253 254 // the handle mark links itself to last_handle_mark 255 new HandleMark(this); 256 257 // plain initialization 258 debug_only(_owned_locks = NULL;) 259 debug_only(_allow_allocation_count = 0;) 260 NOT_PRODUCT(_allow_safepoint_count = 0;) 261 NOT_PRODUCT(_skip_gcalot = false;) 262 _jvmti_env_iteration_count = 0; 263 set_allocated_bytes(0); 264 _vm_operation_started_count = 0; 265 _vm_operation_completed_count = 0; 266 _current_pending_monitor = NULL; 267 _current_pending_monitor_is_from_java = true; 268 _current_waiting_monitor = NULL; 269 _num_nested_signal = 0; 270 omFreeList = NULL; 271 omFreeCount = 0; 272 omFreeProvision = 32; 273 omInUseList = NULL; 274 omInUseCount = 0; 275 276 #ifdef ASSERT 277 _visited_for_critical_count = false; 278 #endif 279 280 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 281 Monitor::_safepoint_check_sometimes); 282 _suspend_flags = 0; 283 284 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 285 _hashStateX = os::random(); 286 _hashStateY = 842502087; 287 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 288 _hashStateW = 273326509; 289 290 _OnTrap = 0; 291 _schedctl = NULL; 292 _Stalled = 0; 293 _TypeTag = 0x2BAD; 294 295 // Many of the following fields are effectively final - immutable 296 // Note that nascent threads can't use the Native Monitor-Mutex 297 // construct until the _MutexEvent is initialized ... 298 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 299 // we might instead use a stack of ParkEvents that we could provision on-demand. 300 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 301 // and ::Release() 302 _ParkEvent = ParkEvent::Allocate(this); 303 _SleepEvent = ParkEvent::Allocate(this); 304 _MutexEvent = ParkEvent::Allocate(this); 305 _MuxEvent = ParkEvent::Allocate(this); 306 307 #ifdef CHECK_UNHANDLED_OOPS 308 if (CheckUnhandledOops) { 309 _unhandled_oops = new UnhandledOops(this); 310 } 311 #endif // CHECK_UNHANDLED_OOPS 312 #ifdef ASSERT 313 if (UseBiasedLocking) { 314 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 315 assert(this == _real_malloc_address || 316 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 317 "bug in forced alignment of thread objects"); 318 } 319 #endif // ASSERT 320 321 // Notify the barrier set that a thread is being created. Note that the 322 // main thread is created before a barrier set is available. The call to 323 // BarrierSet::on_thread_create() for the main thread is therefore deferred 324 // until it calls BarrierSet::set_barrier_set(). 325 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 326 if (barrier_set != NULL) { 327 barrier_set->on_thread_create(this); 328 } 329 } 330 331 void Thread::initialize_thread_current() { 332 #ifndef USE_LIBRARY_BASED_TLS_ONLY 333 assert(_thr_current == NULL, "Thread::current already initialized"); 334 _thr_current = this; 335 #endif 336 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 337 ThreadLocalStorage::set_thread(this); 338 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 339 } 340 341 void Thread::clear_thread_current() { 342 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 343 #ifndef USE_LIBRARY_BASED_TLS_ONLY 344 _thr_current = NULL; 345 #endif 346 ThreadLocalStorage::set_thread(NULL); 347 } 348 349 void Thread::record_stack_base_and_size() { 350 set_stack_base(os::current_stack_base()); 351 set_stack_size(os::current_stack_size()); 352 // CR 7190089: on Solaris, primordial thread's stack is adjusted 353 // in initialize_thread(). Without the adjustment, stack size is 354 // incorrect if stack is set to unlimited (ulimit -s unlimited). 355 // So far, only Solaris has real implementation of initialize_thread(). 356 // 357 // set up any platform-specific state. 358 os::initialize_thread(this); 359 360 // Set stack limits after thread is initialized. 361 if (is_Java_thread()) { 362 ((JavaThread*) this)->set_stack_overflow_limit(); 363 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 364 } 365 #if INCLUDE_NMT 366 // record thread's native stack, stack grows downward 367 MemTracker::record_thread_stack(stack_end(), stack_size()); 368 #endif // INCLUDE_NMT 369 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 370 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 371 os::current_thread_id(), p2i(stack_base() - stack_size()), 372 p2i(stack_base()), stack_size()/1024); 373 } 374 375 376 Thread::~Thread() { 377 EVENT_THREAD_DESTRUCT(this); 378 379 // Notify the barrier set that a thread is being destroyed. Note that a barrier 380 // set might not be available if we encountered errors during bootstrapping. 381 BarrierSet* const barrier_set = BarrierSet::barrier_set(); 382 if (barrier_set != NULL) { 383 barrier_set->on_thread_destroy(this); 384 } 385 386 // stack_base can be NULL if the thread is never started or exited before 387 // record_stack_base_and_size called. Although, we would like to ensure 388 // that all started threads do call record_stack_base_and_size(), there is 389 // not proper way to enforce that. 390 #if INCLUDE_NMT 391 if (_stack_base != NULL) { 392 MemTracker::release_thread_stack(stack_end(), stack_size()); 393 #ifdef ASSERT 394 set_stack_base(NULL); 395 #endif 396 } 397 #endif // INCLUDE_NMT 398 399 // deallocate data structures 400 delete resource_area(); 401 // since the handle marks are using the handle area, we have to deallocated the root 402 // handle mark before deallocating the thread's handle area, 403 assert(last_handle_mark() != NULL, "check we have an element"); 404 delete last_handle_mark(); 405 assert(last_handle_mark() == NULL, "check we have reached the end"); 406 407 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 408 // We NULL out the fields for good hygiene. 409 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 410 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 411 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 412 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 413 414 delete handle_area(); 415 delete metadata_handles(); 416 417 // SR_handler uses this as a termination indicator - 418 // needs to happen before os::free_thread() 419 delete _SR_lock; 420 _SR_lock = NULL; 421 422 // osthread() can be NULL, if creation of thread failed. 423 if (osthread() != NULL) os::free_thread(osthread()); 424 425 // clear Thread::current if thread is deleting itself. 426 // Needed to ensure JNI correctly detects non-attached threads. 427 if (this == Thread::current()) { 428 clear_thread_current(); 429 } 430 431 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 432 } 433 434 // NOTE: dummy function for assertion purpose. 435 void Thread::run() { 436 ShouldNotReachHere(); 437 } 438 439 #ifdef ASSERT 440 // A JavaThread is considered "dangling" if it is not the current 441 // thread, has been added the Threads list, the system is not at a 442 // safepoint and the Thread is not "protected". 443 // 444 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 445 assert(!thread->is_Java_thread() || Thread::current() == thread || 446 !((JavaThread *) thread)->on_thread_list() || 447 SafepointSynchronize::is_at_safepoint() || 448 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 449 "possibility of dangling Thread pointer"); 450 } 451 #endif 452 453 ThreadPriority Thread::get_priority(const Thread* const thread) { 454 ThreadPriority priority; 455 // Can return an error! 456 (void)os::get_priority(thread, priority); 457 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 458 return priority; 459 } 460 461 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 462 debug_only(check_for_dangling_thread_pointer(thread);) 463 // Can return an error! 464 (void)os::set_priority(thread, priority); 465 } 466 467 468 void Thread::start(Thread* thread) { 469 // Start is different from resume in that its safety is guaranteed by context or 470 // being called from a Java method synchronized on the Thread object. 471 if (!DisableStartThread) { 472 if (thread->is_Java_thread()) { 473 // Initialize the thread state to RUNNABLE before starting this thread. 474 // Can not set it after the thread started because we do not know the 475 // exact thread state at that time. It could be in MONITOR_WAIT or 476 // in SLEEPING or some other state. 477 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 478 java_lang_Thread::RUNNABLE); 479 } 480 os::start_thread(thread); 481 } 482 } 483 484 // Enqueue a VM_Operation to do the job for us - sometime later 485 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 486 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 487 VMThread::execute(vm_stop); 488 } 489 490 491 // Check if an external suspend request has completed (or has been 492 // cancelled). Returns true if the thread is externally suspended and 493 // false otherwise. 494 // 495 // The bits parameter returns information about the code path through 496 // the routine. Useful for debugging: 497 // 498 // set in is_ext_suspend_completed(): 499 // 0x00000001 - routine was entered 500 // 0x00000010 - routine return false at end 501 // 0x00000100 - thread exited (return false) 502 // 0x00000200 - suspend request cancelled (return false) 503 // 0x00000400 - thread suspended (return true) 504 // 0x00001000 - thread is in a suspend equivalent state (return true) 505 // 0x00002000 - thread is native and walkable (return true) 506 // 0x00004000 - thread is native_trans and walkable (needed retry) 507 // 508 // set in wait_for_ext_suspend_completion(): 509 // 0x00010000 - routine was entered 510 // 0x00020000 - suspend request cancelled before loop (return false) 511 // 0x00040000 - thread suspended before loop (return true) 512 // 0x00080000 - suspend request cancelled in loop (return false) 513 // 0x00100000 - thread suspended in loop (return true) 514 // 0x00200000 - suspend not completed during retry loop (return false) 515 516 // Helper class for tracing suspend wait debug bits. 517 // 518 // 0x00000100 indicates that the target thread exited before it could 519 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 520 // 0x00080000 each indicate a cancelled suspend request so they don't 521 // count as wait failures either. 522 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 523 524 class TraceSuspendDebugBits : public StackObj { 525 private: 526 JavaThread * jt; 527 bool is_wait; 528 bool called_by_wait; // meaningful when !is_wait 529 uint32_t * bits; 530 531 public: 532 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 533 uint32_t *_bits) { 534 jt = _jt; 535 is_wait = _is_wait; 536 called_by_wait = _called_by_wait; 537 bits = _bits; 538 } 539 540 ~TraceSuspendDebugBits() { 541 if (!is_wait) { 542 #if 1 543 // By default, don't trace bits for is_ext_suspend_completed() calls. 544 // That trace is very chatty. 545 return; 546 #else 547 if (!called_by_wait) { 548 // If tracing for is_ext_suspend_completed() is enabled, then only 549 // trace calls to it from wait_for_ext_suspend_completion() 550 return; 551 } 552 #endif 553 } 554 555 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 556 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 557 MutexLocker ml(Threads_lock); // needed for get_thread_name() 558 ResourceMark rm; 559 560 tty->print_cr( 561 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 562 jt->get_thread_name(), *bits); 563 564 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 565 } 566 } 567 } 568 }; 569 #undef DEBUG_FALSE_BITS 570 571 572 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 573 uint32_t *bits) { 574 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 575 576 bool did_trans_retry = false; // only do thread_in_native_trans retry once 577 bool do_trans_retry; // flag to force the retry 578 579 *bits |= 0x00000001; 580 581 do { 582 do_trans_retry = false; 583 584 if (is_exiting()) { 585 // Thread is in the process of exiting. This is always checked 586 // first to reduce the risk of dereferencing a freed JavaThread. 587 *bits |= 0x00000100; 588 return false; 589 } 590 591 if (!is_external_suspend()) { 592 // Suspend request is cancelled. This is always checked before 593 // is_ext_suspended() to reduce the risk of a rogue resume 594 // confusing the thread that made the suspend request. 595 *bits |= 0x00000200; 596 return false; 597 } 598 599 if (is_ext_suspended()) { 600 // thread is suspended 601 *bits |= 0x00000400; 602 return true; 603 } 604 605 // Now that we no longer do hard suspends of threads running 606 // native code, the target thread can be changing thread state 607 // while we are in this routine: 608 // 609 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 610 // 611 // We save a copy of the thread state as observed at this moment 612 // and make our decision about suspend completeness based on the 613 // copy. This closes the race where the thread state is seen as 614 // _thread_in_native_trans in the if-thread_blocked check, but is 615 // seen as _thread_blocked in if-thread_in_native_trans check. 616 JavaThreadState save_state = thread_state(); 617 618 if (save_state == _thread_blocked && is_suspend_equivalent()) { 619 // If the thread's state is _thread_blocked and this blocking 620 // condition is known to be equivalent to a suspend, then we can 621 // consider the thread to be externally suspended. This means that 622 // the code that sets _thread_blocked has been modified to do 623 // self-suspension if the blocking condition releases. We also 624 // used to check for CONDVAR_WAIT here, but that is now covered by 625 // the _thread_blocked with self-suspension check. 626 // 627 // Return true since we wouldn't be here unless there was still an 628 // external suspend request. 629 *bits |= 0x00001000; 630 return true; 631 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 632 // Threads running native code will self-suspend on native==>VM/Java 633 // transitions. If its stack is walkable (should always be the case 634 // unless this function is called before the actual java_suspend() 635 // call), then the wait is done. 636 *bits |= 0x00002000; 637 return true; 638 } else if (!called_by_wait && !did_trans_retry && 639 save_state == _thread_in_native_trans && 640 frame_anchor()->walkable()) { 641 // The thread is transitioning from thread_in_native to another 642 // thread state. check_safepoint_and_suspend_for_native_trans() 643 // will force the thread to self-suspend. If it hasn't gotten 644 // there yet we may have caught the thread in-between the native 645 // code check above and the self-suspend. Lucky us. If we were 646 // called by wait_for_ext_suspend_completion(), then it 647 // will be doing the retries so we don't have to. 648 // 649 // Since we use the saved thread state in the if-statement above, 650 // there is a chance that the thread has already transitioned to 651 // _thread_blocked by the time we get here. In that case, we will 652 // make a single unnecessary pass through the logic below. This 653 // doesn't hurt anything since we still do the trans retry. 654 655 *bits |= 0x00004000; 656 657 // Once the thread leaves thread_in_native_trans for another 658 // thread state, we break out of this retry loop. We shouldn't 659 // need this flag to prevent us from getting back here, but 660 // sometimes paranoia is good. 661 did_trans_retry = true; 662 663 // We wait for the thread to transition to a more usable state. 664 for (int i = 1; i <= SuspendRetryCount; i++) { 665 // We used to do an "os::yield_all(i)" call here with the intention 666 // that yielding would increase on each retry. However, the parameter 667 // is ignored on Linux which means the yield didn't scale up. Waiting 668 // on the SR_lock below provides a much more predictable scale up for 669 // the delay. It also provides a simple/direct point to check for any 670 // safepoint requests from the VMThread 671 672 // temporarily drops SR_lock while doing wait with safepoint check 673 // (if we're a JavaThread - the WatcherThread can also call this) 674 // and increase delay with each retry 675 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 676 677 // check the actual thread state instead of what we saved above 678 if (thread_state() != _thread_in_native_trans) { 679 // the thread has transitioned to another thread state so 680 // try all the checks (except this one) one more time. 681 do_trans_retry = true; 682 break; 683 } 684 } // end retry loop 685 686 687 } 688 } while (do_trans_retry); 689 690 *bits |= 0x00000010; 691 return false; 692 } 693 694 // Wait for an external suspend request to complete (or be cancelled). 695 // Returns true if the thread is externally suspended and false otherwise. 696 // 697 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 698 uint32_t *bits) { 699 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 700 false /* !called_by_wait */, bits); 701 702 // local flag copies to minimize SR_lock hold time 703 bool is_suspended; 704 bool pending; 705 uint32_t reset_bits; 706 707 // set a marker so is_ext_suspend_completed() knows we are the caller 708 *bits |= 0x00010000; 709 710 // We use reset_bits to reinitialize the bits value at the top of 711 // each retry loop. This allows the caller to make use of any 712 // unused bits for their own marking purposes. 713 reset_bits = *bits; 714 715 { 716 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 717 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 718 delay, bits); 719 pending = is_external_suspend(); 720 } 721 // must release SR_lock to allow suspension to complete 722 723 if (!pending) { 724 // A cancelled suspend request is the only false return from 725 // is_ext_suspend_completed() that keeps us from entering the 726 // retry loop. 727 *bits |= 0x00020000; 728 return false; 729 } 730 731 if (is_suspended) { 732 *bits |= 0x00040000; 733 return true; 734 } 735 736 for (int i = 1; i <= retries; i++) { 737 *bits = reset_bits; // reinit to only track last retry 738 739 // We used to do an "os::yield_all(i)" call here with the intention 740 // that yielding would increase on each retry. However, the parameter 741 // is ignored on Linux which means the yield didn't scale up. Waiting 742 // on the SR_lock below provides a much more predictable scale up for 743 // the delay. It also provides a simple/direct point to check for any 744 // safepoint requests from the VMThread 745 746 { 747 MutexLocker ml(SR_lock()); 748 // wait with safepoint check (if we're a JavaThread - the WatcherThread 749 // can also call this) and increase delay with each retry 750 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 751 752 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 753 delay, bits); 754 755 // It is possible for the external suspend request to be cancelled 756 // (by a resume) before the actual suspend operation is completed. 757 // Refresh our local copy to see if we still need to wait. 758 pending = is_external_suspend(); 759 } 760 761 if (!pending) { 762 // A cancelled suspend request is the only false return from 763 // is_ext_suspend_completed() that keeps us from staying in the 764 // retry loop. 765 *bits |= 0x00080000; 766 return false; 767 } 768 769 if (is_suspended) { 770 *bits |= 0x00100000; 771 return true; 772 } 773 } // end retry loop 774 775 // thread did not suspend after all our retries 776 *bits |= 0x00200000; 777 return false; 778 } 779 780 // Called from API entry points which perform stack walking. If the 781 // associated JavaThread is the current thread, then wait_for_suspend 782 // is not used. Otherwise, it determines if we should wait for the 783 // "other" thread to complete external suspension. (NOTE: in future 784 // releases the suspension mechanism should be reimplemented so this 785 // is not necessary.) 786 // 787 bool 788 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 789 if (this != JavaThread::current()) { 790 // "other" threads require special handling. 791 if (wait_for_suspend) { 792 // We are allowed to wait for the external suspend to complete 793 // so give the other thread a chance to get suspended. 794 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 795 SuspendRetryDelay, bits)) { 796 // Didn't make it so let the caller know. 797 return false; 798 } 799 } 800 // We aren't allowed to wait for the external suspend to complete 801 // so if the other thread isn't externally suspended we need to 802 // let the caller know. 803 else if (!is_ext_suspend_completed_with_lock(bits)) { 804 return false; 805 } 806 } 807 808 return true; 809 } 810 811 #ifndef PRODUCT 812 void JavaThread::record_jump(address target, address instr, const char* file, 813 int line) { 814 815 // This should not need to be atomic as the only way for simultaneous 816 // updates is via interrupts. Even then this should be rare or non-existent 817 // and we don't care that much anyway. 818 819 int index = _jmp_ring_index; 820 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 821 _jmp_ring[index]._target = (intptr_t) target; 822 _jmp_ring[index]._instruction = (intptr_t) instr; 823 _jmp_ring[index]._file = file; 824 _jmp_ring[index]._line = line; 825 } 826 #endif // PRODUCT 827 828 void Thread::interrupt(Thread* thread) { 829 debug_only(check_for_dangling_thread_pointer(thread);) 830 os::interrupt(thread); 831 } 832 833 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 834 debug_only(check_for_dangling_thread_pointer(thread);) 835 // Note: If clear_interrupted==false, this simply fetches and 836 // returns the value of the field osthread()->interrupted(). 837 return os::is_interrupted(thread, clear_interrupted); 838 } 839 840 841 // GC Support 842 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 843 int thread_parity = _oops_do_parity; 844 if (thread_parity != strong_roots_parity) { 845 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 846 if (res == thread_parity) { 847 return true; 848 } else { 849 guarantee(res == strong_roots_parity, "Or else what?"); 850 return false; 851 } 852 } 853 return false; 854 } 855 856 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 857 active_handles()->oops_do(f); 858 // Do oop for ThreadShadow 859 f->do_oop((oop*)&_pending_exception); 860 handle_area()->oops_do(f); 861 862 if (MonitorInUseLists) { 863 // When using thread local monitor lists, we scan them here, 864 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 865 ObjectSynchronizer::thread_local_used_oops_do(this, f); 866 } 867 } 868 869 void Thread::metadata_handles_do(void f(Metadata*)) { 870 // Only walk the Handles in Thread. 871 if (metadata_handles() != NULL) { 872 for (int i = 0; i< metadata_handles()->length(); i++) { 873 f(metadata_handles()->at(i)); 874 } 875 } 876 } 877 878 void Thread::print_on(outputStream* st) const { 879 // get_priority assumes osthread initialized 880 if (osthread() != NULL) { 881 int os_prio; 882 if (os::get_native_priority(this, &os_prio) == OS_OK) { 883 st->print("os_prio=%d ", os_prio); 884 } 885 886 if (os::is_thread_cpu_time_supported()) { 887 st->print("cpu=%.2fms ", 888 os::thread_cpu_time(const_cast<Thread*>(this), true) / 1000000.0 889 ); 890 st->print("elapsed=%.2fs ", 891 _statistic_info.getElepsedTime() / 1000.0); 892 } 893 894 if (is_Java_thread()) { 895 jlong allocated_bytes = const_cast<Thread*>(this)->cooked_allocated_bytes(); 896 st->print("allocated=" JLONG_FORMAT "B ", allocated_bytes); 897 st->print("defined_classes=" INT64_FORMAT " ", _statistic_info.getDefineClassCount()); 898 } 899 900 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 901 osthread()->print_on(st); 902 } 903 if (_threads_hazard_ptr != NULL) { 904 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 905 } 906 if (_nested_threads_hazard_ptr != NULL) { 907 print_nested_threads_hazard_ptrs_on(st); 908 } 909 st->print(" "); 910 debug_only(if (WizardMode) print_owned_locks_on(st);) 911 } 912 913 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const { 914 assert(_nested_threads_hazard_ptr != NULL, "must be set to print"); 915 916 if (EnableThreadSMRStatistics) { 917 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt); 918 } 919 st->print(", _nested_threads_hazard_ptrs="); 920 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL; 921 node = node->next()) { 922 if (node != _nested_threads_hazard_ptr) { 923 // First node does not need a comma-space separator. 924 st->print(", "); 925 } 926 st->print(INTPTR_FORMAT, p2i(node->t_list())); 927 } 928 } 929 930 // Thread::print_on_error() is called by fatal error handler. Don't use 931 // any lock or allocate memory. 932 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 933 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 934 935 if (is_VM_thread()) { st->print("VMThread"); } 936 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 937 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 938 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 939 else { st->print("Thread"); } 940 941 if (is_Named_thread()) { 942 st->print(" \"%s\"", name()); 943 } 944 945 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 946 p2i(stack_end()), p2i(stack_base())); 947 948 if (osthread()) { 949 st->print(" [id=%d]", osthread()->thread_id()); 950 } 951 952 if (_threads_hazard_ptr != NULL) { 953 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 954 } 955 if (_nested_threads_hazard_ptr != NULL) { 956 print_nested_threads_hazard_ptrs_on(st); 957 } 958 } 959 960 void Thread::print_value_on(outputStream* st) const { 961 if (is_Named_thread()) { 962 st->print(" \"%s\" ", name()); 963 } 964 st->print(INTPTR_FORMAT, p2i(this)); // print address 965 } 966 967 #ifdef ASSERT 968 void Thread::print_owned_locks_on(outputStream* st) const { 969 Monitor *cur = _owned_locks; 970 if (cur == NULL) { 971 st->print(" (no locks) "); 972 } else { 973 st->print_cr(" Locks owned:"); 974 while (cur) { 975 cur->print_on(st); 976 cur = cur->next(); 977 } 978 } 979 } 980 981 static int ref_use_count = 0; 982 983 bool Thread::owns_locks_but_compiled_lock() const { 984 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 985 if (cur != Compile_lock) return true; 986 } 987 return false; 988 } 989 990 991 #endif 992 993 #ifndef PRODUCT 994 995 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 996 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 997 // no threads which allow_vm_block's are held 998 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 999 // Check if current thread is allowed to block at a safepoint 1000 if (!(_allow_safepoint_count == 0)) { 1001 fatal("Possible safepoint reached by thread that does not allow it"); 1002 } 1003 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 1004 fatal("LEAF method calling lock?"); 1005 } 1006 1007 #ifdef ASSERT 1008 if (potential_vm_operation && is_Java_thread() 1009 && !Universe::is_bootstrapping()) { 1010 // Make sure we do not hold any locks that the VM thread also uses. 1011 // This could potentially lead to deadlocks 1012 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 1013 // Threads_lock is special, since the safepoint synchronization will not start before this is 1014 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 1015 // since it is used to transfer control between JavaThreads and the VMThread 1016 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 1017 if ((cur->allow_vm_block() && 1018 cur != Threads_lock && 1019 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 1020 cur != VMOperationRequest_lock && 1021 cur != VMOperationQueue_lock) || 1022 cur->rank() == Mutex::special) { 1023 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 1024 } 1025 } 1026 } 1027 1028 if (GCALotAtAllSafepoints) { 1029 // We could enter a safepoint here and thus have a gc 1030 InterfaceSupport::check_gc_alot(); 1031 } 1032 #endif 1033 } 1034 #endif 1035 1036 bool Thread::is_in_stack(address adr) const { 1037 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1038 address end = os::current_stack_pointer(); 1039 // Allow non Java threads to call this without stack_base 1040 if (_stack_base == NULL) return true; 1041 if (stack_base() >= adr && adr >= end) return true; 1042 1043 return false; 1044 } 1045 1046 bool Thread::is_in_usable_stack(address adr) const { 1047 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1048 size_t usable_stack_size = _stack_size - stack_guard_size; 1049 1050 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1051 } 1052 1053 1054 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1055 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1056 // used for compilation in the future. If that change is made, the need for these methods 1057 // should be revisited, and they should be removed if possible. 1058 1059 bool Thread::is_lock_owned(address adr) const { 1060 return on_local_stack(adr); 1061 } 1062 1063 bool Thread::set_as_starting_thread() { 1064 // NOTE: this must be called inside the main thread. 1065 return os::create_main_thread((JavaThread*)this); 1066 } 1067 1068 static void initialize_class(Symbol* class_name, TRAPS) { 1069 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1070 InstanceKlass::cast(klass)->initialize(CHECK); 1071 } 1072 1073 1074 // Creates the initial ThreadGroup 1075 static Handle create_initial_thread_group(TRAPS) { 1076 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 1077 InstanceKlass* ik = InstanceKlass::cast(k); 1078 1079 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 1080 { 1081 JavaValue result(T_VOID); 1082 JavaCalls::call_special(&result, 1083 system_instance, 1084 ik, 1085 vmSymbols::object_initializer_name(), 1086 vmSymbols::void_method_signature(), 1087 CHECK_NH); 1088 } 1089 Universe::set_system_thread_group(system_instance()); 1090 1091 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 1092 { 1093 JavaValue result(T_VOID); 1094 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1095 JavaCalls::call_special(&result, 1096 main_instance, 1097 ik, 1098 vmSymbols::object_initializer_name(), 1099 vmSymbols::threadgroup_string_void_signature(), 1100 system_instance, 1101 string, 1102 CHECK_NH); 1103 } 1104 return main_instance; 1105 } 1106 1107 // Creates the initial Thread 1108 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1109 TRAPS) { 1110 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1111 InstanceKlass* ik = InstanceKlass::cast(k); 1112 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1113 1114 java_lang_Thread::set_thread(thread_oop(), thread); 1115 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1116 thread->set_threadObj(thread_oop()); 1117 1118 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1119 1120 JavaValue result(T_VOID); 1121 JavaCalls::call_special(&result, thread_oop, 1122 ik, 1123 vmSymbols::object_initializer_name(), 1124 vmSymbols::threadgroup_string_void_signature(), 1125 thread_group, 1126 string, 1127 CHECK_NULL); 1128 return thread_oop(); 1129 } 1130 1131 char java_runtime_name[128] = ""; 1132 char java_runtime_version[128] = ""; 1133 1134 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1135 static const char* get_java_runtime_name(TRAPS) { 1136 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1137 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1138 fieldDescriptor fd; 1139 bool found = k != NULL && 1140 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1141 vmSymbols::string_signature(), &fd); 1142 if (found) { 1143 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1144 if (name_oop == NULL) { 1145 return NULL; 1146 } 1147 const char* name = java_lang_String::as_utf8_string(name_oop, 1148 java_runtime_name, 1149 sizeof(java_runtime_name)); 1150 return name; 1151 } else { 1152 return NULL; 1153 } 1154 } 1155 1156 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1157 static const char* get_java_runtime_version(TRAPS) { 1158 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1159 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1160 fieldDescriptor fd; 1161 bool found = k != NULL && 1162 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1163 vmSymbols::string_signature(), &fd); 1164 if (found) { 1165 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1166 if (name_oop == NULL) { 1167 return NULL; 1168 } 1169 const char* name = java_lang_String::as_utf8_string(name_oop, 1170 java_runtime_version, 1171 sizeof(java_runtime_version)); 1172 return name; 1173 } else { 1174 return NULL; 1175 } 1176 } 1177 1178 // General purpose hook into Java code, run once when the VM is initialized. 1179 // The Java library method itself may be changed independently from the VM. 1180 static void call_postVMInitHook(TRAPS) { 1181 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1182 if (klass != NULL) { 1183 JavaValue result(T_VOID); 1184 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1185 vmSymbols::void_method_signature(), 1186 CHECK); 1187 } 1188 } 1189 1190 static void reset_vm_info_property(TRAPS) { 1191 // the vm info string 1192 ResourceMark rm(THREAD); 1193 const char *vm_info = VM_Version::vm_info_string(); 1194 1195 // java.lang.System class 1196 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1197 1198 // setProperty arguments 1199 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1200 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1201 1202 // return value 1203 JavaValue r(T_OBJECT); 1204 1205 // public static String setProperty(String key, String value); 1206 JavaCalls::call_static(&r, 1207 klass, 1208 vmSymbols::setProperty_name(), 1209 vmSymbols::string_string_string_signature(), 1210 key_str, 1211 value_str, 1212 CHECK); 1213 } 1214 1215 1216 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1217 bool daemon, TRAPS) { 1218 assert(thread_group.not_null(), "thread group should be specified"); 1219 assert(threadObj() == NULL, "should only create Java thread object once"); 1220 1221 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1222 InstanceKlass* ik = InstanceKlass::cast(k); 1223 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1224 1225 java_lang_Thread::set_thread(thread_oop(), this); 1226 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1227 set_threadObj(thread_oop()); 1228 1229 JavaValue result(T_VOID); 1230 if (thread_name != NULL) { 1231 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1232 // Thread gets assigned specified name and null target 1233 JavaCalls::call_special(&result, 1234 thread_oop, 1235 ik, 1236 vmSymbols::object_initializer_name(), 1237 vmSymbols::threadgroup_string_void_signature(), 1238 thread_group, // Argument 1 1239 name, // Argument 2 1240 THREAD); 1241 } else { 1242 // Thread gets assigned name "Thread-nnn" and null target 1243 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1244 JavaCalls::call_special(&result, 1245 thread_oop, 1246 ik, 1247 vmSymbols::object_initializer_name(), 1248 vmSymbols::threadgroup_runnable_void_signature(), 1249 thread_group, // Argument 1 1250 Handle(), // Argument 2 1251 THREAD); 1252 } 1253 1254 1255 if (daemon) { 1256 java_lang_Thread::set_daemon(thread_oop()); 1257 } 1258 1259 if (HAS_PENDING_EXCEPTION) { 1260 return; 1261 } 1262 1263 Klass* group = SystemDictionary::ThreadGroup_klass(); 1264 Handle threadObj(THREAD, this->threadObj()); 1265 1266 JavaCalls::call_special(&result, 1267 thread_group, 1268 group, 1269 vmSymbols::add_method_name(), 1270 vmSymbols::thread_void_signature(), 1271 threadObj, // Arg 1 1272 THREAD); 1273 } 1274 1275 // NamedThread -- non-JavaThread subclasses with multiple 1276 // uniquely named instances should derive from this. 1277 NamedThread::NamedThread() : Thread() { 1278 _name = NULL; 1279 _processed_thread = NULL; 1280 _gc_id = GCId::undefined(); 1281 } 1282 1283 NamedThread::~NamedThread() { 1284 if (_name != NULL) { 1285 FREE_C_HEAP_ARRAY(char, _name); 1286 _name = NULL; 1287 } 1288 } 1289 1290 void NamedThread::set_name(const char* format, ...) { 1291 guarantee(_name == NULL, "Only get to set name once."); 1292 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1293 guarantee(_name != NULL, "alloc failure"); 1294 va_list ap; 1295 va_start(ap, format); 1296 jio_vsnprintf(_name, max_name_len, format, ap); 1297 va_end(ap); 1298 } 1299 1300 void NamedThread::initialize_named_thread() { 1301 set_native_thread_name(name()); 1302 } 1303 1304 void NamedThread::print_on(outputStream* st) const { 1305 st->print("\"%s\" ", name()); 1306 Thread::print_on(st); 1307 st->cr(); 1308 } 1309 1310 1311 // ======= WatcherThread ======== 1312 1313 // The watcher thread exists to simulate timer interrupts. It should 1314 // be replaced by an abstraction over whatever native support for 1315 // timer interrupts exists on the platform. 1316 1317 WatcherThread* WatcherThread::_watcher_thread = NULL; 1318 bool WatcherThread::_startable = false; 1319 volatile bool WatcherThread::_should_terminate = false; 1320 1321 WatcherThread::WatcherThread() : Thread() { 1322 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1323 if (os::create_thread(this, os::watcher_thread)) { 1324 _watcher_thread = this; 1325 1326 // Set the watcher thread to the highest OS priority which should not be 1327 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1328 // is created. The only normal thread using this priority is the reference 1329 // handler thread, which runs for very short intervals only. 1330 // If the VMThread's priority is not lower than the WatcherThread profiling 1331 // will be inaccurate. 1332 os::set_priority(this, MaxPriority); 1333 if (!DisableStartThread) { 1334 os::start_thread(this); 1335 } 1336 } 1337 } 1338 1339 int WatcherThread::sleep() const { 1340 // The WatcherThread does not participate in the safepoint protocol 1341 // for the PeriodicTask_lock because it is not a JavaThread. 1342 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1343 1344 if (_should_terminate) { 1345 // check for termination before we do any housekeeping or wait 1346 return 0; // we did not sleep. 1347 } 1348 1349 // remaining will be zero if there are no tasks, 1350 // causing the WatcherThread to sleep until a task is 1351 // enrolled 1352 int remaining = PeriodicTask::time_to_wait(); 1353 int time_slept = 0; 1354 1355 // we expect this to timeout - we only ever get unparked when 1356 // we should terminate or when a new task has been enrolled 1357 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1358 1359 jlong time_before_loop = os::javaTimeNanos(); 1360 1361 while (true) { 1362 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1363 remaining); 1364 jlong now = os::javaTimeNanos(); 1365 1366 if (remaining == 0) { 1367 // if we didn't have any tasks we could have waited for a long time 1368 // consider the time_slept zero and reset time_before_loop 1369 time_slept = 0; 1370 time_before_loop = now; 1371 } else { 1372 // need to recalculate since we might have new tasks in _tasks 1373 time_slept = (int) ((now - time_before_loop) / 1000000); 1374 } 1375 1376 // Change to task list or spurious wakeup of some kind 1377 if (timedout || _should_terminate) { 1378 break; 1379 } 1380 1381 remaining = PeriodicTask::time_to_wait(); 1382 if (remaining == 0) { 1383 // Last task was just disenrolled so loop around and wait until 1384 // another task gets enrolled 1385 continue; 1386 } 1387 1388 remaining -= time_slept; 1389 if (remaining <= 0) { 1390 break; 1391 } 1392 } 1393 1394 return time_slept; 1395 } 1396 1397 void WatcherThread::run() { 1398 assert(this == watcher_thread(), "just checking"); 1399 1400 this->record_stack_base_and_size(); 1401 this->set_native_thread_name(this->name()); 1402 this->set_active_handles(JNIHandleBlock::allocate_block()); 1403 while (true) { 1404 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1405 assert(watcher_thread() == this, "thread consistency check"); 1406 1407 // Calculate how long it'll be until the next PeriodicTask work 1408 // should be done, and sleep that amount of time. 1409 int time_waited = sleep(); 1410 1411 if (VMError::is_error_reported()) { 1412 // A fatal error has happened, the error handler(VMError::report_and_die) 1413 // should abort JVM after creating an error log file. However in some 1414 // rare cases, the error handler itself might deadlock. Here periodically 1415 // check for error reporting timeouts, and if it happens, just proceed to 1416 // abort the VM. 1417 1418 // This code is in WatcherThread because WatcherThread wakes up 1419 // periodically so the fatal error handler doesn't need to do anything; 1420 // also because the WatcherThread is less likely to crash than other 1421 // threads. 1422 1423 for (;;) { 1424 // Note: we use naked sleep in this loop because we want to avoid using 1425 // any kind of VM infrastructure which may be broken at this point. 1426 if (VMError::check_timeout()) { 1427 // We hit error reporting timeout. Error reporting was interrupted and 1428 // will be wrapping things up now (closing files etc). Give it some more 1429 // time, then quit the VM. 1430 os::naked_short_sleep(200); 1431 // Print a message to stderr. 1432 fdStream err(defaultStream::output_fd()); 1433 err.print_raw_cr("# [ timer expired, abort... ]"); 1434 // skip atexit/vm_exit/vm_abort hooks 1435 os::die(); 1436 } 1437 1438 // Wait a second, then recheck for timeout. 1439 os::naked_short_sleep(999); 1440 } 1441 } 1442 1443 if (_should_terminate) { 1444 // check for termination before posting the next tick 1445 break; 1446 } 1447 1448 PeriodicTask::real_time_tick(time_waited); 1449 } 1450 1451 // Signal that it is terminated 1452 { 1453 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1454 _watcher_thread = NULL; 1455 Terminator_lock->notify(); 1456 } 1457 } 1458 1459 void WatcherThread::start() { 1460 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1461 1462 if (watcher_thread() == NULL && _startable) { 1463 _should_terminate = false; 1464 // Create the single instance of WatcherThread 1465 new WatcherThread(); 1466 } 1467 } 1468 1469 void WatcherThread::make_startable() { 1470 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1471 _startable = true; 1472 } 1473 1474 void WatcherThread::stop() { 1475 { 1476 // Follow normal safepoint aware lock enter protocol since the 1477 // WatcherThread is stopped by another JavaThread. 1478 MutexLocker ml(PeriodicTask_lock); 1479 _should_terminate = true; 1480 1481 WatcherThread* watcher = watcher_thread(); 1482 if (watcher != NULL) { 1483 // unpark the WatcherThread so it can see that it should terminate 1484 watcher->unpark(); 1485 } 1486 } 1487 1488 MutexLocker mu(Terminator_lock); 1489 1490 while (watcher_thread() != NULL) { 1491 // This wait should make safepoint checks, wait without a timeout, 1492 // and wait as a suspend-equivalent condition. 1493 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1494 Mutex::_as_suspend_equivalent_flag); 1495 } 1496 } 1497 1498 void WatcherThread::unpark() { 1499 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1500 PeriodicTask_lock->notify(); 1501 } 1502 1503 void WatcherThread::print_on(outputStream* st) const { 1504 st->print("\"%s\" ", name()); 1505 Thread::print_on(st); 1506 st->cr(); 1507 } 1508 1509 // ======= JavaThread ======== 1510 1511 #if INCLUDE_JVMCI 1512 1513 jlong* JavaThread::_jvmci_old_thread_counters; 1514 1515 bool jvmci_counters_include(JavaThread* thread) { 1516 oop threadObj = thread->threadObj(); 1517 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1518 } 1519 1520 void JavaThread::collect_counters(typeArrayOop array) { 1521 if (JVMCICounterSize > 0) { 1522 MutexLocker tl(Threads_lock); 1523 JavaThreadIteratorWithHandle jtiwh; 1524 for (int i = 0; i < array->length(); i++) { 1525 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1526 } 1527 for (; JavaThread *tp = jtiwh.next(); ) { 1528 if (jvmci_counters_include(tp)) { 1529 for (int i = 0; i < array->length(); i++) { 1530 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1531 } 1532 } 1533 } 1534 } 1535 } 1536 1537 #endif // INCLUDE_JVMCI 1538 1539 // A JavaThread is a normal Java thread 1540 1541 void JavaThread::initialize() { 1542 // Initialize fields 1543 1544 set_saved_exception_pc(NULL); 1545 set_threadObj(NULL); 1546 _anchor.clear(); 1547 set_entry_point(NULL); 1548 set_jni_functions(jni_functions()); 1549 set_callee_target(NULL); 1550 set_vm_result(NULL); 1551 set_vm_result_2(NULL); 1552 set_vframe_array_head(NULL); 1553 set_vframe_array_last(NULL); 1554 set_deferred_locals(NULL); 1555 set_deopt_mark(NULL); 1556 set_deopt_compiled_method(NULL); 1557 clear_must_deopt_id(); 1558 set_monitor_chunks(NULL); 1559 set_next(NULL); 1560 _on_thread_list = false; 1561 set_thread_state(_thread_new); 1562 _terminated = _not_terminated; 1563 _privileged_stack_top = NULL; 1564 _array_for_gc = NULL; 1565 _suspend_equivalent = false; 1566 _in_deopt_handler = 0; 1567 _doing_unsafe_access = false; 1568 _stack_guard_state = stack_guard_unused; 1569 #if INCLUDE_JVMCI 1570 _pending_monitorenter = false; 1571 _pending_deoptimization = -1; 1572 _pending_failed_speculation = NULL; 1573 _pending_transfer_to_interpreter = false; 1574 _adjusting_comp_level = false; 1575 _jvmci._alternate_call_target = NULL; 1576 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1577 if (JVMCICounterSize > 0) { 1578 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1579 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1580 } else { 1581 _jvmci_counters = NULL; 1582 } 1583 #endif // INCLUDE_JVMCI 1584 _reserved_stack_activation = NULL; // stack base not known yet 1585 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1586 _exception_pc = 0; 1587 _exception_handler_pc = 0; 1588 _is_method_handle_return = 0; 1589 _jvmti_thread_state= NULL; 1590 _should_post_on_exceptions_flag = JNI_FALSE; 1591 _jvmti_get_loaded_classes_closure = NULL; 1592 _interp_only_mode = 0; 1593 _special_runtime_exit_condition = _no_async_condition; 1594 _pending_async_exception = NULL; 1595 _thread_stat = NULL; 1596 _thread_stat = new ThreadStatistics(); 1597 _blocked_on_compilation = false; 1598 _jni_active_critical = 0; 1599 _pending_jni_exception_check_fn = NULL; 1600 _do_not_unlock_if_synchronized = false; 1601 _cached_monitor_info = NULL; 1602 _parker = Parker::Allocate(this); 1603 1604 #ifndef PRODUCT 1605 _jmp_ring_index = 0; 1606 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1607 record_jump(NULL, NULL, NULL, 0); 1608 } 1609 #endif // PRODUCT 1610 1611 // Setup safepoint state info for this thread 1612 ThreadSafepointState::create(this); 1613 1614 debug_only(_java_call_counter = 0); 1615 1616 // JVMTI PopFrame support 1617 _popframe_condition = popframe_inactive; 1618 _popframe_preserved_args = NULL; 1619 _popframe_preserved_args_size = 0; 1620 _frames_to_pop_failed_realloc = 0; 1621 1622 if (SafepointMechanism::uses_thread_local_poll()) { 1623 SafepointMechanism::initialize_header(this); 1624 } 1625 1626 pd_initialize(); 1627 } 1628 1629 JavaThread::JavaThread(bool is_attaching_via_jni) : 1630 Thread() { 1631 initialize(); 1632 if (is_attaching_via_jni) { 1633 _jni_attach_state = _attaching_via_jni; 1634 } else { 1635 _jni_attach_state = _not_attaching_via_jni; 1636 } 1637 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1638 } 1639 1640 bool JavaThread::reguard_stack(address cur_sp) { 1641 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1642 && _stack_guard_state != stack_guard_reserved_disabled) { 1643 return true; // Stack already guarded or guard pages not needed. 1644 } 1645 1646 if (register_stack_overflow()) { 1647 // For those architectures which have separate register and 1648 // memory stacks, we must check the register stack to see if 1649 // it has overflowed. 1650 return false; 1651 } 1652 1653 // Java code never executes within the yellow zone: the latter is only 1654 // there to provoke an exception during stack banging. If java code 1655 // is executing there, either StackShadowPages should be larger, or 1656 // some exception code in c1, c2 or the interpreter isn't unwinding 1657 // when it should. 1658 guarantee(cur_sp > stack_reserved_zone_base(), 1659 "not enough space to reguard - increase StackShadowPages"); 1660 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1661 enable_stack_yellow_reserved_zone(); 1662 if (reserved_stack_activation() != stack_base()) { 1663 set_reserved_stack_activation(stack_base()); 1664 } 1665 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1666 set_reserved_stack_activation(stack_base()); 1667 enable_stack_reserved_zone(); 1668 } 1669 return true; 1670 } 1671 1672 bool JavaThread::reguard_stack(void) { 1673 return reguard_stack(os::current_stack_pointer()); 1674 } 1675 1676 1677 void JavaThread::block_if_vm_exited() { 1678 if (_terminated == _vm_exited) { 1679 // _vm_exited is set at safepoint, and Threads_lock is never released 1680 // we will block here forever 1681 Threads_lock->lock_without_safepoint_check(); 1682 ShouldNotReachHere(); 1683 } 1684 } 1685 1686 1687 // Remove this ifdef when C1 is ported to the compiler interface. 1688 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1689 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1690 1691 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1692 Thread() { 1693 initialize(); 1694 _jni_attach_state = _not_attaching_via_jni; 1695 set_entry_point(entry_point); 1696 // Create the native thread itself. 1697 // %note runtime_23 1698 os::ThreadType thr_type = os::java_thread; 1699 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1700 os::java_thread; 1701 os::create_thread(this, thr_type, stack_sz); 1702 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1703 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1704 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1705 // the exception consists of creating the exception object & initializing it, initialization 1706 // will leave the VM via a JavaCall and then all locks must be unlocked). 1707 // 1708 // The thread is still suspended when we reach here. Thread must be explicit started 1709 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1710 // by calling Threads:add. The reason why this is not done here, is because the thread 1711 // object must be fully initialized (take a look at JVM_Start) 1712 } 1713 1714 JavaThread::~JavaThread() { 1715 1716 // JSR166 -- return the parker to the free list 1717 Parker::Release(_parker); 1718 _parker = NULL; 1719 1720 // Free any remaining previous UnrollBlock 1721 vframeArray* old_array = vframe_array_last(); 1722 1723 if (old_array != NULL) { 1724 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1725 old_array->set_unroll_block(NULL); 1726 delete old_info; 1727 delete old_array; 1728 } 1729 1730 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1731 if (deferred != NULL) { 1732 // This can only happen if thread is destroyed before deoptimization occurs. 1733 assert(deferred->length() != 0, "empty array!"); 1734 do { 1735 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1736 deferred->remove_at(0); 1737 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1738 delete dlv; 1739 } while (deferred->length() != 0); 1740 delete deferred; 1741 } 1742 1743 // All Java related clean up happens in exit 1744 ThreadSafepointState::destroy(this); 1745 if (_thread_stat != NULL) delete _thread_stat; 1746 1747 #if INCLUDE_JVMCI 1748 if (JVMCICounterSize > 0) { 1749 if (jvmci_counters_include(this)) { 1750 for (int i = 0; i < JVMCICounterSize; i++) { 1751 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1752 } 1753 } 1754 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1755 } 1756 #endif // INCLUDE_JVMCI 1757 } 1758 1759 1760 // The first routine called by a new Java thread 1761 void JavaThread::run() { 1762 // initialize thread-local alloc buffer related fields 1763 this->initialize_tlab(); 1764 1765 // used to test validity of stack trace backs 1766 this->record_base_of_stack_pointer(); 1767 1768 // Record real stack base and size. 1769 this->record_stack_base_and_size(); 1770 1771 this->create_stack_guard_pages(); 1772 1773 this->cache_global_variables(); 1774 1775 // Thread is now sufficient initialized to be handled by the safepoint code as being 1776 // in the VM. Change thread state from _thread_new to _thread_in_vm 1777 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1778 1779 assert(JavaThread::current() == this, "sanity check"); 1780 assert(!Thread::current()->owns_locks(), "sanity check"); 1781 1782 DTRACE_THREAD_PROBE(start, this); 1783 1784 // This operation might block. We call that after all safepoint checks for a new thread has 1785 // been completed. 1786 this->set_active_handles(JNIHandleBlock::allocate_block()); 1787 1788 if (JvmtiExport::should_post_thread_life()) { 1789 JvmtiExport::post_thread_start(this); 1790 } 1791 1792 EventThreadStart event; 1793 if (event.should_commit()) { 1794 event.set_thread(THREAD_TRACE_ID(this)); 1795 event.commit(); 1796 } 1797 1798 // We call another function to do the rest so we are sure that the stack addresses used 1799 // from there will be lower than the stack base just computed 1800 thread_main_inner(); 1801 1802 // Note, thread is no longer valid at this point! 1803 } 1804 1805 1806 void JavaThread::thread_main_inner() { 1807 assert(JavaThread::current() == this, "sanity check"); 1808 assert(this->threadObj() != NULL, "just checking"); 1809 1810 // Execute thread entry point unless this thread has a pending exception 1811 // or has been stopped before starting. 1812 // Note: Due to JVM_StopThread we can have pending exceptions already! 1813 if (!this->has_pending_exception() && 1814 !java_lang_Thread::is_stillborn(this->threadObj())) { 1815 { 1816 ResourceMark rm(this); 1817 this->set_native_thread_name(this->get_thread_name()); 1818 } 1819 HandleMark hm(this); 1820 this->entry_point()(this, this); 1821 } 1822 1823 DTRACE_THREAD_PROBE(stop, this); 1824 1825 this->exit(false); 1826 this->smr_delete(); 1827 } 1828 1829 1830 static void ensure_join(JavaThread* thread) { 1831 // We do not need to grab the Threads_lock, since we are operating on ourself. 1832 Handle threadObj(thread, thread->threadObj()); 1833 assert(threadObj.not_null(), "java thread object must exist"); 1834 ObjectLocker lock(threadObj, thread); 1835 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1836 thread->clear_pending_exception(); 1837 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1838 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1839 // Clear the native thread instance - this makes isAlive return false and allows the join() 1840 // to complete once we've done the notify_all below 1841 java_lang_Thread::set_thread(threadObj(), NULL); 1842 lock.notify_all(thread); 1843 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1844 thread->clear_pending_exception(); 1845 } 1846 1847 1848 // For any new cleanup additions, please check to see if they need to be applied to 1849 // cleanup_failed_attach_current_thread as well. 1850 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1851 assert(this == JavaThread::current(), "thread consistency check"); 1852 1853 elapsedTimer _timer_exit_phase1; 1854 elapsedTimer _timer_exit_phase2; 1855 elapsedTimer _timer_exit_phase3; 1856 elapsedTimer _timer_exit_phase4; 1857 1858 if (log_is_enabled(Debug, os, thread, timer)) { 1859 _timer_exit_phase1.start(); 1860 } 1861 1862 HandleMark hm(this); 1863 Handle uncaught_exception(this, this->pending_exception()); 1864 this->clear_pending_exception(); 1865 Handle threadObj(this, this->threadObj()); 1866 assert(threadObj.not_null(), "Java thread object should be created"); 1867 1868 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1869 { 1870 EXCEPTION_MARK; 1871 1872 CLEAR_PENDING_EXCEPTION; 1873 } 1874 if (!destroy_vm) { 1875 if (uncaught_exception.not_null()) { 1876 EXCEPTION_MARK; 1877 // Call method Thread.dispatchUncaughtException(). 1878 Klass* thread_klass = SystemDictionary::Thread_klass(); 1879 JavaValue result(T_VOID); 1880 JavaCalls::call_virtual(&result, 1881 threadObj, thread_klass, 1882 vmSymbols::dispatchUncaughtException_name(), 1883 vmSymbols::throwable_void_signature(), 1884 uncaught_exception, 1885 THREAD); 1886 if (HAS_PENDING_EXCEPTION) { 1887 ResourceMark rm(this); 1888 jio_fprintf(defaultStream::error_stream(), 1889 "\nException: %s thrown from the UncaughtExceptionHandler" 1890 " in thread \"%s\"\n", 1891 pending_exception()->klass()->external_name(), 1892 get_thread_name()); 1893 CLEAR_PENDING_EXCEPTION; 1894 } 1895 } 1896 1897 // Called before the java thread exit since we want to read info 1898 // from java_lang_Thread object 1899 EventThreadEnd event; 1900 if (event.should_commit()) { 1901 event.set_thread(THREAD_TRACE_ID(this)); 1902 event.commit(); 1903 } 1904 1905 // Call after last event on thread 1906 EVENT_THREAD_EXIT(this); 1907 1908 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1909 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1910 // is deprecated anyhow. 1911 if (!is_Compiler_thread()) { 1912 int count = 3; 1913 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1914 EXCEPTION_MARK; 1915 JavaValue result(T_VOID); 1916 Klass* thread_klass = SystemDictionary::Thread_klass(); 1917 JavaCalls::call_virtual(&result, 1918 threadObj, thread_klass, 1919 vmSymbols::exit_method_name(), 1920 vmSymbols::void_method_signature(), 1921 THREAD); 1922 CLEAR_PENDING_EXCEPTION; 1923 } 1924 } 1925 // notify JVMTI 1926 if (JvmtiExport::should_post_thread_life()) { 1927 JvmtiExport::post_thread_end(this); 1928 } 1929 1930 // We have notified the agents that we are exiting, before we go on, 1931 // we must check for a pending external suspend request and honor it 1932 // in order to not surprise the thread that made the suspend request. 1933 while (true) { 1934 { 1935 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1936 if (!is_external_suspend()) { 1937 set_terminated(_thread_exiting); 1938 ThreadService::current_thread_exiting(this); 1939 break; 1940 } 1941 // Implied else: 1942 // Things get a little tricky here. We have a pending external 1943 // suspend request, but we are holding the SR_lock so we 1944 // can't just self-suspend. So we temporarily drop the lock 1945 // and then self-suspend. 1946 } 1947 1948 ThreadBlockInVM tbivm(this); 1949 java_suspend_self(); 1950 1951 // We're done with this suspend request, but we have to loop around 1952 // and check again. Eventually we will get SR_lock without a pending 1953 // external suspend request and will be able to mark ourselves as 1954 // exiting. 1955 } 1956 // no more external suspends are allowed at this point 1957 } else { 1958 // before_exit() has already posted JVMTI THREAD_END events 1959 } 1960 1961 if (log_is_enabled(Debug, os, thread, timer)) { 1962 _timer_exit_phase1.stop(); 1963 _timer_exit_phase2.start(); 1964 } 1965 // Notify waiters on thread object. This has to be done after exit() is called 1966 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1967 // group should have the destroyed bit set before waiters are notified). 1968 ensure_join(this); 1969 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1970 1971 if (log_is_enabled(Debug, os, thread, timer)) { 1972 _timer_exit_phase2.stop(); 1973 _timer_exit_phase3.start(); 1974 } 1975 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1976 // held by this thread must be released. The spec does not distinguish 1977 // between JNI-acquired and regular Java monitors. We can only see 1978 // regular Java monitors here if monitor enter-exit matching is broken. 1979 // 1980 // Optionally release any monitors for regular JavaThread exits. This 1981 // is provided as a work around for any bugs in monitor enter-exit 1982 // matching. This can be expensive so it is not enabled by default. 1983 // 1984 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1985 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1986 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1987 // Sanity check even though JNI DetachCurrentThread() would have 1988 // returned JNI_ERR if there was a Java frame. JavaThread exit 1989 // should be done executing Java code by the time we get here. 1990 assert(!this->has_last_Java_frame(), 1991 "should not have a Java frame when detaching or exiting"); 1992 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1993 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1994 } 1995 1996 // These things needs to be done while we are still a Java Thread. Make sure that thread 1997 // is in a consistent state, in case GC happens 1998 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1999 2000 if (active_handles() != NULL) { 2001 JNIHandleBlock* block = active_handles(); 2002 set_active_handles(NULL); 2003 JNIHandleBlock::release_block(block); 2004 } 2005 2006 if (free_handle_block() != NULL) { 2007 JNIHandleBlock* block = free_handle_block(); 2008 set_free_handle_block(NULL); 2009 JNIHandleBlock::release_block(block); 2010 } 2011 2012 // These have to be removed while this is still a valid thread. 2013 remove_stack_guard_pages(); 2014 2015 if (UseTLAB) { 2016 tlab().make_parsable(true); // retire TLAB 2017 } 2018 2019 if (JvmtiEnv::environments_might_exist()) { 2020 JvmtiExport::cleanup_thread(this); 2021 } 2022 2023 // We must flush any deferred card marks and other various GC barrier 2024 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2025 // before removing a thread from the list of active threads. 2026 BarrierSet::barrier_set()->on_thread_detach(this); 2027 2028 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2029 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2030 os::current_thread_id()); 2031 2032 if (log_is_enabled(Debug, os, thread, timer)) { 2033 _timer_exit_phase3.stop(); 2034 _timer_exit_phase4.start(); 2035 } 2036 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2037 Threads::remove(this); 2038 2039 if (log_is_enabled(Debug, os, thread, timer)) { 2040 _timer_exit_phase4.stop(); 2041 ResourceMark rm(this); 2042 log_debug(os, thread, timer)("name='%s'" 2043 ", exit-phase1=" JLONG_FORMAT 2044 ", exit-phase2=" JLONG_FORMAT 2045 ", exit-phase3=" JLONG_FORMAT 2046 ", exit-phase4=" JLONG_FORMAT, 2047 get_thread_name(), 2048 _timer_exit_phase1.milliseconds(), 2049 _timer_exit_phase2.milliseconds(), 2050 _timer_exit_phase3.milliseconds(), 2051 _timer_exit_phase4.milliseconds()); 2052 } 2053 } 2054 2055 void JavaThread::cleanup_failed_attach_current_thread() { 2056 if (active_handles() != NULL) { 2057 JNIHandleBlock* block = active_handles(); 2058 set_active_handles(NULL); 2059 JNIHandleBlock::release_block(block); 2060 } 2061 2062 if (free_handle_block() != NULL) { 2063 JNIHandleBlock* block = free_handle_block(); 2064 set_free_handle_block(NULL); 2065 JNIHandleBlock::release_block(block); 2066 } 2067 2068 // These have to be removed while this is still a valid thread. 2069 remove_stack_guard_pages(); 2070 2071 if (UseTLAB) { 2072 tlab().make_parsable(true); // retire TLAB, if any 2073 } 2074 2075 BarrierSet::barrier_set()->on_thread_detach(this); 2076 2077 Threads::remove(this); 2078 this->smr_delete(); 2079 } 2080 2081 JavaThread* JavaThread::active() { 2082 Thread* thread = Thread::current(); 2083 if (thread->is_Java_thread()) { 2084 return (JavaThread*) thread; 2085 } else { 2086 assert(thread->is_VM_thread(), "this must be a vm thread"); 2087 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2088 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2089 assert(ret->is_Java_thread(), "must be a Java thread"); 2090 return ret; 2091 } 2092 } 2093 2094 bool JavaThread::is_lock_owned(address adr) const { 2095 if (Thread::is_lock_owned(adr)) return true; 2096 2097 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2098 if (chunk->contains(adr)) return true; 2099 } 2100 2101 return false; 2102 } 2103 2104 2105 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2106 chunk->set_next(monitor_chunks()); 2107 set_monitor_chunks(chunk); 2108 } 2109 2110 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2111 guarantee(monitor_chunks() != NULL, "must be non empty"); 2112 if (monitor_chunks() == chunk) { 2113 set_monitor_chunks(chunk->next()); 2114 } else { 2115 MonitorChunk* prev = monitor_chunks(); 2116 while (prev->next() != chunk) prev = prev->next(); 2117 prev->set_next(chunk->next()); 2118 } 2119 } 2120 2121 // JVM support. 2122 2123 // Note: this function shouldn't block if it's called in 2124 // _thread_in_native_trans state (such as from 2125 // check_special_condition_for_native_trans()). 2126 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2127 2128 if (has_last_Java_frame() && has_async_condition()) { 2129 // If we are at a polling page safepoint (not a poll return) 2130 // then we must defer async exception because live registers 2131 // will be clobbered by the exception path. Poll return is 2132 // ok because the call we a returning from already collides 2133 // with exception handling registers and so there is no issue. 2134 // (The exception handling path kills call result registers but 2135 // this is ok since the exception kills the result anyway). 2136 2137 if (is_at_poll_safepoint()) { 2138 // if the code we are returning to has deoptimized we must defer 2139 // the exception otherwise live registers get clobbered on the 2140 // exception path before deoptimization is able to retrieve them. 2141 // 2142 RegisterMap map(this, false); 2143 frame caller_fr = last_frame().sender(&map); 2144 assert(caller_fr.is_compiled_frame(), "what?"); 2145 if (caller_fr.is_deoptimized_frame()) { 2146 log_info(exceptions)("deferred async exception at compiled safepoint"); 2147 return; 2148 } 2149 } 2150 } 2151 2152 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2153 if (condition == _no_async_condition) { 2154 // Conditions have changed since has_special_runtime_exit_condition() 2155 // was called: 2156 // - if we were here only because of an external suspend request, 2157 // then that was taken care of above (or cancelled) so we are done 2158 // - if we were here because of another async request, then it has 2159 // been cleared between the has_special_runtime_exit_condition() 2160 // and now so again we are done 2161 return; 2162 } 2163 2164 // Check for pending async. exception 2165 if (_pending_async_exception != NULL) { 2166 // Only overwrite an already pending exception, if it is not a threadDeath. 2167 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2168 2169 // We cannot call Exceptions::_throw(...) here because we cannot block 2170 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2171 2172 LogTarget(Info, exceptions) lt; 2173 if (lt.is_enabled()) { 2174 ResourceMark rm; 2175 LogStream ls(lt); 2176 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2177 if (has_last_Java_frame()) { 2178 frame f = last_frame(); 2179 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2180 } 2181 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2182 } 2183 _pending_async_exception = NULL; 2184 clear_has_async_exception(); 2185 } 2186 } 2187 2188 if (check_unsafe_error && 2189 condition == _async_unsafe_access_error && !has_pending_exception()) { 2190 condition = _no_async_condition; // done 2191 switch (thread_state()) { 2192 case _thread_in_vm: { 2193 JavaThread* THREAD = this; 2194 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2195 } 2196 case _thread_in_native: { 2197 ThreadInVMfromNative tiv(this); 2198 JavaThread* THREAD = this; 2199 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2200 } 2201 case _thread_in_Java: { 2202 ThreadInVMfromJava tiv(this); 2203 JavaThread* THREAD = this; 2204 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2205 } 2206 default: 2207 ShouldNotReachHere(); 2208 } 2209 } 2210 2211 assert(condition == _no_async_condition || has_pending_exception() || 2212 (!check_unsafe_error && condition == _async_unsafe_access_error), 2213 "must have handled the async condition, if no exception"); 2214 } 2215 2216 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2217 // 2218 // Check for pending external suspend. Internal suspend requests do 2219 // not use handle_special_runtime_exit_condition(). 2220 // If JNIEnv proxies are allowed, don't self-suspend if the target 2221 // thread is not the current thread. In older versions of jdbx, jdbx 2222 // threads could call into the VM with another thread's JNIEnv so we 2223 // can be here operating on behalf of a suspended thread (4432884). 2224 bool do_self_suspend = is_external_suspend_with_lock(); 2225 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2226 // 2227 // Because thread is external suspended the safepoint code will count 2228 // thread as at a safepoint. This can be odd because we can be here 2229 // as _thread_in_Java which would normally transition to _thread_blocked 2230 // at a safepoint. We would like to mark the thread as _thread_blocked 2231 // before calling java_suspend_self like all other callers of it but 2232 // we must then observe proper safepoint protocol. (We can't leave 2233 // _thread_blocked with a safepoint in progress). However we can be 2234 // here as _thread_in_native_trans so we can't use a normal transition 2235 // constructor/destructor pair because they assert on that type of 2236 // transition. We could do something like: 2237 // 2238 // JavaThreadState state = thread_state(); 2239 // set_thread_state(_thread_in_vm); 2240 // { 2241 // ThreadBlockInVM tbivm(this); 2242 // java_suspend_self() 2243 // } 2244 // set_thread_state(_thread_in_vm_trans); 2245 // if (safepoint) block; 2246 // set_thread_state(state); 2247 // 2248 // but that is pretty messy. Instead we just go with the way the 2249 // code has worked before and note that this is the only path to 2250 // java_suspend_self that doesn't put the thread in _thread_blocked 2251 // mode. 2252 2253 frame_anchor()->make_walkable(this); 2254 java_suspend_self(); 2255 2256 // We might be here for reasons in addition to the self-suspend request 2257 // so check for other async requests. 2258 } 2259 2260 if (check_asyncs) { 2261 check_and_handle_async_exceptions(); 2262 } 2263 #if INCLUDE_TRACE 2264 if (is_trace_suspend()) { 2265 TRACE_SUSPEND_THREAD(this); 2266 } 2267 #endif 2268 } 2269 2270 void JavaThread::send_thread_stop(oop java_throwable) { 2271 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2272 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2273 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2274 2275 // Do not throw asynchronous exceptions against the compiler thread 2276 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2277 if (!can_call_java()) return; 2278 2279 { 2280 // Actually throw the Throwable against the target Thread - however 2281 // only if there is no thread death exception installed already. 2282 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2283 // If the topmost frame is a runtime stub, then we are calling into 2284 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2285 // must deoptimize the caller before continuing, as the compiled exception handler table 2286 // may not be valid 2287 if (has_last_Java_frame()) { 2288 frame f = last_frame(); 2289 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2290 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2291 RegisterMap reg_map(this, UseBiasedLocking); 2292 frame compiled_frame = f.sender(®_map); 2293 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2294 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2295 } 2296 } 2297 } 2298 2299 // Set async. pending exception in thread. 2300 set_pending_async_exception(java_throwable); 2301 2302 if (log_is_enabled(Info, exceptions)) { 2303 ResourceMark rm; 2304 log_info(exceptions)("Pending Async. exception installed of type: %s", 2305 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2306 } 2307 // for AbortVMOnException flag 2308 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2309 } 2310 } 2311 2312 2313 // Interrupt thread so it will wake up from a potential wait() 2314 Thread::interrupt(this); 2315 } 2316 2317 // External suspension mechanism. 2318 // 2319 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2320 // to any VM_locks and it is at a transition 2321 // Self-suspension will happen on the transition out of the vm. 2322 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2323 // 2324 // Guarantees on return: 2325 // + Target thread will not execute any new bytecode (that's why we need to 2326 // force a safepoint) 2327 // + Target thread will not enter any new monitors 2328 // 2329 void JavaThread::java_suspend() { 2330 ThreadsListHandle tlh; 2331 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2332 return; 2333 } 2334 2335 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2336 if (!is_external_suspend()) { 2337 // a racing resume has cancelled us; bail out now 2338 return; 2339 } 2340 2341 // suspend is done 2342 uint32_t debug_bits = 0; 2343 // Warning: is_ext_suspend_completed() may temporarily drop the 2344 // SR_lock to allow the thread to reach a stable thread state if 2345 // it is currently in a transient thread state. 2346 if (is_ext_suspend_completed(false /* !called_by_wait */, 2347 SuspendRetryDelay, &debug_bits)) { 2348 return; 2349 } 2350 } 2351 2352 VM_ThreadSuspend vm_suspend; 2353 VMThread::execute(&vm_suspend); 2354 } 2355 2356 // Part II of external suspension. 2357 // A JavaThread self suspends when it detects a pending external suspend 2358 // request. This is usually on transitions. It is also done in places 2359 // where continuing to the next transition would surprise the caller, 2360 // e.g., monitor entry. 2361 // 2362 // Returns the number of times that the thread self-suspended. 2363 // 2364 // Note: DO NOT call java_suspend_self() when you just want to block current 2365 // thread. java_suspend_self() is the second stage of cooperative 2366 // suspension for external suspend requests and should only be used 2367 // to complete an external suspend request. 2368 // 2369 int JavaThread::java_suspend_self() { 2370 int ret = 0; 2371 2372 // we are in the process of exiting so don't suspend 2373 if (is_exiting()) { 2374 clear_external_suspend(); 2375 return ret; 2376 } 2377 2378 assert(_anchor.walkable() || 2379 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2380 "must have walkable stack"); 2381 2382 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2383 2384 assert(!this->is_ext_suspended(), 2385 "a thread trying to self-suspend should not already be suspended"); 2386 2387 if (this->is_suspend_equivalent()) { 2388 // If we are self-suspending as a result of the lifting of a 2389 // suspend equivalent condition, then the suspend_equivalent 2390 // flag is not cleared until we set the ext_suspended flag so 2391 // that wait_for_ext_suspend_completion() returns consistent 2392 // results. 2393 this->clear_suspend_equivalent(); 2394 } 2395 2396 // A racing resume may have cancelled us before we grabbed SR_lock 2397 // above. Or another external suspend request could be waiting for us 2398 // by the time we return from SR_lock()->wait(). The thread 2399 // that requested the suspension may already be trying to walk our 2400 // stack and if we return now, we can change the stack out from under 2401 // it. This would be a "bad thing (TM)" and cause the stack walker 2402 // to crash. We stay self-suspended until there are no more pending 2403 // external suspend requests. 2404 while (is_external_suspend()) { 2405 ret++; 2406 this->set_ext_suspended(); 2407 2408 // _ext_suspended flag is cleared by java_resume() 2409 while (is_ext_suspended()) { 2410 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2411 } 2412 } 2413 2414 return ret; 2415 } 2416 2417 #ifdef ASSERT 2418 // Verify the JavaThread has not yet been published in the Threads::list, and 2419 // hence doesn't need protection from concurrent access at this stage. 2420 void JavaThread::verify_not_published() { 2421 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2422 // since an unpublished JavaThread doesn't participate in the 2423 // Thread-SMR protocol for keeping a ThreadsList alive. 2424 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2425 } 2426 #endif 2427 2428 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2429 // progress or when _suspend_flags is non-zero. 2430 // Current thread needs to self-suspend if there is a suspend request and/or 2431 // block if a safepoint is in progress. 2432 // Async exception ISN'T checked. 2433 // Note only the ThreadInVMfromNative transition can call this function 2434 // directly and when thread state is _thread_in_native_trans 2435 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2436 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2437 2438 JavaThread *curJT = JavaThread::current(); 2439 bool do_self_suspend = thread->is_external_suspend(); 2440 2441 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2442 2443 // If JNIEnv proxies are allowed, don't self-suspend if the target 2444 // thread is not the current thread. In older versions of jdbx, jdbx 2445 // threads could call into the VM with another thread's JNIEnv so we 2446 // can be here operating on behalf of a suspended thread (4432884). 2447 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2448 JavaThreadState state = thread->thread_state(); 2449 2450 // We mark this thread_blocked state as a suspend-equivalent so 2451 // that a caller to is_ext_suspend_completed() won't be confused. 2452 // The suspend-equivalent state is cleared by java_suspend_self(). 2453 thread->set_suspend_equivalent(); 2454 2455 // If the safepoint code sees the _thread_in_native_trans state, it will 2456 // wait until the thread changes to other thread state. There is no 2457 // guarantee on how soon we can obtain the SR_lock and complete the 2458 // self-suspend request. It would be a bad idea to let safepoint wait for 2459 // too long. Temporarily change the state to _thread_blocked to 2460 // let the VM thread know that this thread is ready for GC. The problem 2461 // of changing thread state is that safepoint could happen just after 2462 // java_suspend_self() returns after being resumed, and VM thread will 2463 // see the _thread_blocked state. We must check for safepoint 2464 // after restoring the state and make sure we won't leave while a safepoint 2465 // is in progress. 2466 thread->set_thread_state(_thread_blocked); 2467 thread->java_suspend_self(); 2468 thread->set_thread_state(state); 2469 2470 InterfaceSupport::serialize_thread_state_with_handler(thread); 2471 } 2472 2473 SafepointMechanism::block_if_requested(curJT); 2474 2475 if (thread->is_deopt_suspend()) { 2476 thread->clear_deopt_suspend(); 2477 RegisterMap map(thread, false); 2478 frame f = thread->last_frame(); 2479 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2480 f = f.sender(&map); 2481 } 2482 if (f.id() == thread->must_deopt_id()) { 2483 thread->clear_must_deopt_id(); 2484 f.deoptimize(thread); 2485 } else { 2486 fatal("missed deoptimization!"); 2487 } 2488 } 2489 #if INCLUDE_TRACE 2490 if (thread->is_trace_suspend()) { 2491 TRACE_SUSPEND_THREAD(thread); 2492 } 2493 #endif 2494 } 2495 2496 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2497 // progress or when _suspend_flags is non-zero. 2498 // Current thread needs to self-suspend if there is a suspend request and/or 2499 // block if a safepoint is in progress. 2500 // Also check for pending async exception (not including unsafe access error). 2501 // Note only the native==>VM/Java barriers can call this function and when 2502 // thread state is _thread_in_native_trans. 2503 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2504 check_safepoint_and_suspend_for_native_trans(thread); 2505 2506 if (thread->has_async_exception()) { 2507 // We are in _thread_in_native_trans state, don't handle unsafe 2508 // access error since that may block. 2509 thread->check_and_handle_async_exceptions(false); 2510 } 2511 } 2512 2513 // This is a variant of the normal 2514 // check_special_condition_for_native_trans with slightly different 2515 // semantics for use by critical native wrappers. It does all the 2516 // normal checks but also performs the transition back into 2517 // thread_in_Java state. This is required so that critical natives 2518 // can potentially block and perform a GC if they are the last thread 2519 // exiting the GCLocker. 2520 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2521 check_special_condition_for_native_trans(thread); 2522 2523 // Finish the transition 2524 thread->set_thread_state(_thread_in_Java); 2525 2526 if (thread->do_critical_native_unlock()) { 2527 ThreadInVMfromJavaNoAsyncException tiv(thread); 2528 GCLocker::unlock_critical(thread); 2529 thread->clear_critical_native_unlock(); 2530 } 2531 } 2532 2533 // We need to guarantee the Threads_lock here, since resumes are not 2534 // allowed during safepoint synchronization 2535 // Can only resume from an external suspension 2536 void JavaThread::java_resume() { 2537 assert_locked_or_safepoint(Threads_lock); 2538 2539 // Sanity check: thread is gone, has started exiting or the thread 2540 // was not externally suspended. 2541 ThreadsListHandle tlh; 2542 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2543 return; 2544 } 2545 2546 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2547 2548 clear_external_suspend(); 2549 2550 if (is_ext_suspended()) { 2551 clear_ext_suspended(); 2552 SR_lock()->notify_all(); 2553 } 2554 } 2555 2556 size_t JavaThread::_stack_red_zone_size = 0; 2557 size_t JavaThread::_stack_yellow_zone_size = 0; 2558 size_t JavaThread::_stack_reserved_zone_size = 0; 2559 size_t JavaThread::_stack_shadow_zone_size = 0; 2560 2561 void JavaThread::create_stack_guard_pages() { 2562 if (!os::uses_stack_guard_pages() || 2563 _stack_guard_state != stack_guard_unused || 2564 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2565 log_info(os, thread)("Stack guard page creation for thread " 2566 UINTX_FORMAT " disabled", os::current_thread_id()); 2567 return; 2568 } 2569 address low_addr = stack_end(); 2570 size_t len = stack_guard_zone_size(); 2571 2572 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2573 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2574 2575 int must_commit = os::must_commit_stack_guard_pages(); 2576 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2577 2578 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2579 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2580 return; 2581 } 2582 2583 if (os::guard_memory((char *) low_addr, len)) { 2584 _stack_guard_state = stack_guard_enabled; 2585 } else { 2586 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2587 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2588 if (os::uncommit_memory((char *) low_addr, len)) { 2589 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2590 } 2591 return; 2592 } 2593 2594 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2595 PTR_FORMAT "-" PTR_FORMAT ".", 2596 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2597 } 2598 2599 void JavaThread::remove_stack_guard_pages() { 2600 assert(Thread::current() == this, "from different thread"); 2601 if (_stack_guard_state == stack_guard_unused) return; 2602 address low_addr = stack_end(); 2603 size_t len = stack_guard_zone_size(); 2604 2605 if (os::must_commit_stack_guard_pages()) { 2606 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2607 _stack_guard_state = stack_guard_unused; 2608 } else { 2609 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2610 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2611 return; 2612 } 2613 } else { 2614 if (_stack_guard_state == stack_guard_unused) return; 2615 if (os::unguard_memory((char *) low_addr, len)) { 2616 _stack_guard_state = stack_guard_unused; 2617 } else { 2618 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2619 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2620 return; 2621 } 2622 } 2623 2624 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2625 PTR_FORMAT "-" PTR_FORMAT ".", 2626 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2627 } 2628 2629 void JavaThread::enable_stack_reserved_zone() { 2630 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2631 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2632 2633 // The base notation is from the stack's point of view, growing downward. 2634 // We need to adjust it to work correctly with guard_memory() 2635 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2636 2637 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2638 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2639 2640 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2641 _stack_guard_state = stack_guard_enabled; 2642 } else { 2643 warning("Attempt to guard stack reserved zone failed."); 2644 } 2645 enable_register_stack_guard(); 2646 } 2647 2648 void JavaThread::disable_stack_reserved_zone() { 2649 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2650 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2651 2652 // Simply return if called for a thread that does not use guard pages. 2653 if (_stack_guard_state == stack_guard_unused) return; 2654 2655 // The base notation is from the stack's point of view, growing downward. 2656 // We need to adjust it to work correctly with guard_memory() 2657 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2658 2659 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2660 _stack_guard_state = stack_guard_reserved_disabled; 2661 } else { 2662 warning("Attempt to unguard stack reserved zone failed."); 2663 } 2664 disable_register_stack_guard(); 2665 } 2666 2667 void JavaThread::enable_stack_yellow_reserved_zone() { 2668 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2669 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2670 2671 // The base notation is from the stacks point of view, growing downward. 2672 // We need to adjust it to work correctly with guard_memory() 2673 address base = stack_red_zone_base(); 2674 2675 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2676 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2677 2678 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2679 _stack_guard_state = stack_guard_enabled; 2680 } else { 2681 warning("Attempt to guard stack yellow zone failed."); 2682 } 2683 enable_register_stack_guard(); 2684 } 2685 2686 void JavaThread::disable_stack_yellow_reserved_zone() { 2687 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2688 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2689 2690 // Simply return if called for a thread that does not use guard pages. 2691 if (_stack_guard_state == stack_guard_unused) return; 2692 2693 // The base notation is from the stacks point of view, growing downward. 2694 // We need to adjust it to work correctly with guard_memory() 2695 address base = stack_red_zone_base(); 2696 2697 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2698 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2699 } else { 2700 warning("Attempt to unguard stack yellow zone failed."); 2701 } 2702 disable_register_stack_guard(); 2703 } 2704 2705 void JavaThread::enable_stack_red_zone() { 2706 // The base notation is from the stacks point of view, growing downward. 2707 // We need to adjust it to work correctly with guard_memory() 2708 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2709 address base = stack_red_zone_base() - stack_red_zone_size(); 2710 2711 guarantee(base < stack_base(), "Error calculating stack red zone"); 2712 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2713 2714 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2715 warning("Attempt to guard stack red zone failed."); 2716 } 2717 } 2718 2719 void JavaThread::disable_stack_red_zone() { 2720 // The base notation is from the stacks point of view, growing downward. 2721 // We need to adjust it to work correctly with guard_memory() 2722 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2723 address base = stack_red_zone_base() - stack_red_zone_size(); 2724 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2725 warning("Attempt to unguard stack red zone failed."); 2726 } 2727 } 2728 2729 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2730 // ignore is there is no stack 2731 if (!has_last_Java_frame()) return; 2732 // traverse the stack frames. Starts from top frame. 2733 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2734 frame* fr = fst.current(); 2735 f(fr, fst.register_map()); 2736 } 2737 } 2738 2739 2740 #ifndef PRODUCT 2741 // Deoptimization 2742 // Function for testing deoptimization 2743 void JavaThread::deoptimize() { 2744 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2745 StackFrameStream fst(this, UseBiasedLocking); 2746 bool deopt = false; // Dump stack only if a deopt actually happens. 2747 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2748 // Iterate over all frames in the thread and deoptimize 2749 for (; !fst.is_done(); fst.next()) { 2750 if (fst.current()->can_be_deoptimized()) { 2751 2752 if (only_at) { 2753 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2754 // consists of comma or carriage return separated numbers so 2755 // search for the current bci in that string. 2756 address pc = fst.current()->pc(); 2757 nmethod* nm = (nmethod*) fst.current()->cb(); 2758 ScopeDesc* sd = nm->scope_desc_at(pc); 2759 char buffer[8]; 2760 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2761 size_t len = strlen(buffer); 2762 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2763 while (found != NULL) { 2764 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2765 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2766 // Check that the bci found is bracketed by terminators. 2767 break; 2768 } 2769 found = strstr(found + 1, buffer); 2770 } 2771 if (!found) { 2772 continue; 2773 } 2774 } 2775 2776 if (DebugDeoptimization && !deopt) { 2777 deopt = true; // One-time only print before deopt 2778 tty->print_cr("[BEFORE Deoptimization]"); 2779 trace_frames(); 2780 trace_stack(); 2781 } 2782 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2783 } 2784 } 2785 2786 if (DebugDeoptimization && deopt) { 2787 tty->print_cr("[AFTER Deoptimization]"); 2788 trace_frames(); 2789 } 2790 } 2791 2792 2793 // Make zombies 2794 void JavaThread::make_zombies() { 2795 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2796 if (fst.current()->can_be_deoptimized()) { 2797 // it is a Java nmethod 2798 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2799 nm->make_not_entrant(); 2800 } 2801 } 2802 } 2803 #endif // PRODUCT 2804 2805 2806 void JavaThread::deoptimized_wrt_marked_nmethods() { 2807 if (!has_last_Java_frame()) return; 2808 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2809 StackFrameStream fst(this, UseBiasedLocking); 2810 for (; !fst.is_done(); fst.next()) { 2811 if (fst.current()->should_be_deoptimized()) { 2812 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2813 } 2814 } 2815 } 2816 2817 2818 // If the caller is a NamedThread, then remember, in the current scope, 2819 // the given JavaThread in its _processed_thread field. 2820 class RememberProcessedThread: public StackObj { 2821 NamedThread* _cur_thr; 2822 public: 2823 RememberProcessedThread(JavaThread* jthr) { 2824 Thread* thread = Thread::current(); 2825 if (thread->is_Named_thread()) { 2826 _cur_thr = (NamedThread *)thread; 2827 _cur_thr->set_processed_thread(jthr); 2828 } else { 2829 _cur_thr = NULL; 2830 } 2831 } 2832 2833 ~RememberProcessedThread() { 2834 if (_cur_thr) { 2835 _cur_thr->set_processed_thread(NULL); 2836 } 2837 } 2838 }; 2839 2840 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2841 // Verify that the deferred card marks have been flushed. 2842 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2843 2844 // Traverse the GCHandles 2845 Thread::oops_do(f, cf); 2846 2847 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2848 2849 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2850 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2851 2852 if (has_last_Java_frame()) { 2853 // Record JavaThread to GC thread 2854 RememberProcessedThread rpt(this); 2855 2856 // Traverse the privileged stack 2857 if (_privileged_stack_top != NULL) { 2858 _privileged_stack_top->oops_do(f); 2859 } 2860 2861 // traverse the registered growable array 2862 if (_array_for_gc != NULL) { 2863 for (int index = 0; index < _array_for_gc->length(); index++) { 2864 f->do_oop(_array_for_gc->adr_at(index)); 2865 } 2866 } 2867 2868 // Traverse the monitor chunks 2869 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2870 chunk->oops_do(f); 2871 } 2872 2873 // Traverse the execution stack 2874 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2875 fst.current()->oops_do(f, cf, fst.register_map()); 2876 } 2877 } 2878 2879 // callee_target is never live across a gc point so NULL it here should 2880 // it still contain a methdOop. 2881 2882 set_callee_target(NULL); 2883 2884 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2885 // If we have deferred set_locals there might be oops waiting to be 2886 // written 2887 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2888 if (list != NULL) { 2889 for (int i = 0; i < list->length(); i++) { 2890 list->at(i)->oops_do(f); 2891 } 2892 } 2893 2894 // Traverse instance variables at the end since the GC may be moving things 2895 // around using this function 2896 f->do_oop((oop*) &_threadObj); 2897 f->do_oop((oop*) &_vm_result); 2898 f->do_oop((oop*) &_exception_oop); 2899 f->do_oop((oop*) &_pending_async_exception); 2900 2901 if (jvmti_thread_state() != NULL) { 2902 jvmti_thread_state()->oops_do(f); 2903 } 2904 } 2905 2906 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2907 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2908 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2909 2910 if (has_last_Java_frame()) { 2911 // Traverse the execution stack 2912 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2913 fst.current()->nmethods_do(cf); 2914 } 2915 } 2916 } 2917 2918 void JavaThread::metadata_do(void f(Metadata*)) { 2919 if (has_last_Java_frame()) { 2920 // Traverse the execution stack to call f() on the methods in the stack 2921 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2922 fst.current()->metadata_do(f); 2923 } 2924 } else if (is_Compiler_thread()) { 2925 // need to walk ciMetadata in current compile tasks to keep alive. 2926 CompilerThread* ct = (CompilerThread*)this; 2927 if (ct->env() != NULL) { 2928 ct->env()->metadata_do(f); 2929 } 2930 CompileTask* task = ct->task(); 2931 if (task != NULL) { 2932 task->metadata_do(f); 2933 } 2934 } 2935 } 2936 2937 // Printing 2938 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2939 switch (_thread_state) { 2940 case _thread_uninitialized: return "_thread_uninitialized"; 2941 case _thread_new: return "_thread_new"; 2942 case _thread_new_trans: return "_thread_new_trans"; 2943 case _thread_in_native: return "_thread_in_native"; 2944 case _thread_in_native_trans: return "_thread_in_native_trans"; 2945 case _thread_in_vm: return "_thread_in_vm"; 2946 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2947 case _thread_in_Java: return "_thread_in_Java"; 2948 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2949 case _thread_blocked: return "_thread_blocked"; 2950 case _thread_blocked_trans: return "_thread_blocked_trans"; 2951 default: return "unknown thread state"; 2952 } 2953 } 2954 2955 #ifndef PRODUCT 2956 void JavaThread::print_thread_state_on(outputStream *st) const { 2957 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2958 }; 2959 void JavaThread::print_thread_state() const { 2960 print_thread_state_on(tty); 2961 } 2962 #endif // PRODUCT 2963 2964 // Called by Threads::print() for VM_PrintThreads operation 2965 void JavaThread::print_on(outputStream *st) const { 2966 st->print_raw("\""); 2967 st->print_raw(get_thread_name()); 2968 st->print_raw("\" "); 2969 oop thread_oop = threadObj(); 2970 if (thread_oop != NULL) { 2971 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2972 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2973 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2974 } 2975 Thread::print_on(st); 2976 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2977 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2978 if (thread_oop != NULL) { 2979 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2980 } 2981 #ifndef PRODUCT 2982 print_thread_state_on(st); 2983 _safepoint_state->print_on(st); 2984 #endif // PRODUCT 2985 if (is_Compiler_thread()) { 2986 CompileTask *task = ((CompilerThread*)this)->task(); 2987 if (task != NULL) { 2988 st->print(" Compiling: "); 2989 task->print(st, NULL, true, false); 2990 } else { 2991 st->print(" No compile task"); 2992 } 2993 st->cr(); 2994 } 2995 } 2996 2997 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2998 st->print("%s", get_thread_name_string(buf, buflen)); 2999 } 3000 3001 // Called by fatal error handler. The difference between this and 3002 // JavaThread::print() is that we can't grab lock or allocate memory. 3003 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 3004 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 3005 oop thread_obj = threadObj(); 3006 if (thread_obj != NULL) { 3007 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 3008 } 3009 st->print(" ["); 3010 st->print("%s", _get_thread_state_name(_thread_state)); 3011 if (osthread()) { 3012 st->print(", id=%d", osthread()->thread_id()); 3013 } 3014 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 3015 p2i(stack_end()), p2i(stack_base())); 3016 st->print("]"); 3017 3018 if (_threads_hazard_ptr != NULL) { 3019 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 3020 } 3021 if (_nested_threads_hazard_ptr != NULL) { 3022 print_nested_threads_hazard_ptrs_on(st); 3023 } 3024 return; 3025 } 3026 3027 // Verification 3028 3029 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3030 3031 void JavaThread::verify() { 3032 // Verify oops in the thread. 3033 oops_do(&VerifyOopClosure::verify_oop, NULL); 3034 3035 // Verify the stack frames. 3036 frames_do(frame_verify); 3037 } 3038 3039 // CR 6300358 (sub-CR 2137150) 3040 // Most callers of this method assume that it can't return NULL but a 3041 // thread may not have a name whilst it is in the process of attaching to 3042 // the VM - see CR 6412693, and there are places where a JavaThread can be 3043 // seen prior to having it's threadObj set (eg JNI attaching threads and 3044 // if vm exit occurs during initialization). These cases can all be accounted 3045 // for such that this method never returns NULL. 3046 const char* JavaThread::get_thread_name() const { 3047 #ifdef ASSERT 3048 // early safepoints can hit while current thread does not yet have TLS 3049 if (!SafepointSynchronize::is_at_safepoint()) { 3050 Thread *cur = Thread::current(); 3051 if (!(cur->is_Java_thread() && cur == this)) { 3052 // Current JavaThreads are allowed to get their own name without 3053 // the Threads_lock. 3054 assert_locked_or_safepoint(Threads_lock); 3055 } 3056 } 3057 #endif // ASSERT 3058 return get_thread_name_string(); 3059 } 3060 3061 // Returns a non-NULL representation of this thread's name, or a suitable 3062 // descriptive string if there is no set name 3063 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3064 const char* name_str; 3065 oop thread_obj = threadObj(); 3066 if (thread_obj != NULL) { 3067 oop name = java_lang_Thread::name(thread_obj); 3068 if (name != NULL) { 3069 if (buf == NULL) { 3070 name_str = java_lang_String::as_utf8_string(name); 3071 } else { 3072 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3073 } 3074 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3075 name_str = "<no-name - thread is attaching>"; 3076 } else { 3077 name_str = Thread::name(); 3078 } 3079 } else { 3080 name_str = Thread::name(); 3081 } 3082 assert(name_str != NULL, "unexpected NULL thread name"); 3083 return name_str; 3084 } 3085 3086 3087 const char* JavaThread::get_threadgroup_name() const { 3088 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3089 oop thread_obj = threadObj(); 3090 if (thread_obj != NULL) { 3091 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3092 if (thread_group != NULL) { 3093 // ThreadGroup.name can be null 3094 return java_lang_ThreadGroup::name(thread_group); 3095 } 3096 } 3097 return NULL; 3098 } 3099 3100 const char* JavaThread::get_parent_name() const { 3101 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3102 oop thread_obj = threadObj(); 3103 if (thread_obj != NULL) { 3104 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3105 if (thread_group != NULL) { 3106 oop parent = java_lang_ThreadGroup::parent(thread_group); 3107 if (parent != NULL) { 3108 // ThreadGroup.name can be null 3109 return java_lang_ThreadGroup::name(parent); 3110 } 3111 } 3112 } 3113 return NULL; 3114 } 3115 3116 ThreadPriority JavaThread::java_priority() const { 3117 oop thr_oop = threadObj(); 3118 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3119 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3120 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3121 return priority; 3122 } 3123 3124 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3125 3126 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3127 // Link Java Thread object <-> C++ Thread 3128 3129 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3130 // and put it into a new Handle. The Handle "thread_oop" can then 3131 // be used to pass the C++ thread object to other methods. 3132 3133 // Set the Java level thread object (jthread) field of the 3134 // new thread (a JavaThread *) to C++ thread object using the 3135 // "thread_oop" handle. 3136 3137 // Set the thread field (a JavaThread *) of the 3138 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3139 3140 Handle thread_oop(Thread::current(), 3141 JNIHandles::resolve_non_null(jni_thread)); 3142 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3143 "must be initialized"); 3144 set_threadObj(thread_oop()); 3145 java_lang_Thread::set_thread(thread_oop(), this); 3146 3147 if (prio == NoPriority) { 3148 prio = java_lang_Thread::priority(thread_oop()); 3149 assert(prio != NoPriority, "A valid priority should be present"); 3150 } 3151 3152 // Push the Java priority down to the native thread; needs Threads_lock 3153 Thread::set_priority(this, prio); 3154 3155 // Add the new thread to the Threads list and set it in motion. 3156 // We must have threads lock in order to call Threads::add. 3157 // It is crucial that we do not block before the thread is 3158 // added to the Threads list for if a GC happens, then the java_thread oop 3159 // will not be visited by GC. 3160 Threads::add(this); 3161 } 3162 3163 oop JavaThread::current_park_blocker() { 3164 // Support for JSR-166 locks 3165 oop thread_oop = threadObj(); 3166 if (thread_oop != NULL && 3167 JDK_Version::current().supports_thread_park_blocker()) { 3168 return java_lang_Thread::park_blocker(thread_oop); 3169 } 3170 return NULL; 3171 } 3172 3173 3174 void JavaThread::print_stack_on(outputStream* st) { 3175 if (!has_last_Java_frame()) return; 3176 ResourceMark rm; 3177 HandleMark hm; 3178 3179 RegisterMap reg_map(this); 3180 vframe* start_vf = last_java_vframe(®_map); 3181 int count = 0; 3182 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3183 if (f->is_java_frame()) { 3184 javaVFrame* jvf = javaVFrame::cast(f); 3185 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3186 3187 // Print out lock information 3188 if (JavaMonitorsInStackTrace) { 3189 jvf->print_lock_info_on(st, count); 3190 } 3191 } else { 3192 // Ignore non-Java frames 3193 } 3194 3195 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3196 count++; 3197 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3198 } 3199 } 3200 3201 3202 // JVMTI PopFrame support 3203 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3204 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3205 if (in_bytes(size_in_bytes) != 0) { 3206 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3207 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3208 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3209 } 3210 } 3211 3212 void* JavaThread::popframe_preserved_args() { 3213 return _popframe_preserved_args; 3214 } 3215 3216 ByteSize JavaThread::popframe_preserved_args_size() { 3217 return in_ByteSize(_popframe_preserved_args_size); 3218 } 3219 3220 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3221 int sz = in_bytes(popframe_preserved_args_size()); 3222 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3223 return in_WordSize(sz / wordSize); 3224 } 3225 3226 void JavaThread::popframe_free_preserved_args() { 3227 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3228 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3229 _popframe_preserved_args = NULL; 3230 _popframe_preserved_args_size = 0; 3231 } 3232 3233 #ifndef PRODUCT 3234 3235 void JavaThread::trace_frames() { 3236 tty->print_cr("[Describe stack]"); 3237 int frame_no = 1; 3238 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3239 tty->print(" %d. ", frame_no++); 3240 fst.current()->print_value_on(tty, this); 3241 tty->cr(); 3242 } 3243 } 3244 3245 class PrintAndVerifyOopClosure: public OopClosure { 3246 protected: 3247 template <class T> inline void do_oop_work(T* p) { 3248 oop obj = RawAccess<>::oop_load(p); 3249 if (obj == NULL) return; 3250 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3251 if (oopDesc::is_oop_or_null(obj)) { 3252 if (obj->is_objArray()) { 3253 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3254 } else { 3255 obj->print(); 3256 } 3257 } else { 3258 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3259 } 3260 tty->cr(); 3261 } 3262 public: 3263 virtual void do_oop(oop* p) { do_oop_work(p); } 3264 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3265 }; 3266 3267 3268 static void oops_print(frame* f, const RegisterMap *map) { 3269 PrintAndVerifyOopClosure print; 3270 f->print_value(); 3271 f->oops_do(&print, NULL, (RegisterMap*)map); 3272 } 3273 3274 // Print our all the locations that contain oops and whether they are 3275 // valid or not. This useful when trying to find the oldest frame 3276 // where an oop has gone bad since the frame walk is from youngest to 3277 // oldest. 3278 void JavaThread::trace_oops() { 3279 tty->print_cr("[Trace oops]"); 3280 frames_do(oops_print); 3281 } 3282 3283 3284 #ifdef ASSERT 3285 // Print or validate the layout of stack frames 3286 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3287 ResourceMark rm; 3288 PRESERVE_EXCEPTION_MARK; 3289 FrameValues values; 3290 int frame_no = 0; 3291 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3292 fst.current()->describe(values, ++frame_no); 3293 if (depth == frame_no) break; 3294 } 3295 if (validate_only) { 3296 values.validate(); 3297 } else { 3298 tty->print_cr("[Describe stack layout]"); 3299 values.print(this); 3300 } 3301 } 3302 #endif 3303 3304 void JavaThread::trace_stack_from(vframe* start_vf) { 3305 ResourceMark rm; 3306 int vframe_no = 1; 3307 for (vframe* f = start_vf; f; f = f->sender()) { 3308 if (f->is_java_frame()) { 3309 javaVFrame::cast(f)->print_activation(vframe_no++); 3310 } else { 3311 f->print(); 3312 } 3313 if (vframe_no > StackPrintLimit) { 3314 tty->print_cr("...<more frames>..."); 3315 return; 3316 } 3317 } 3318 } 3319 3320 3321 void JavaThread::trace_stack() { 3322 if (!has_last_Java_frame()) return; 3323 ResourceMark rm; 3324 HandleMark hm; 3325 RegisterMap reg_map(this); 3326 trace_stack_from(last_java_vframe(®_map)); 3327 } 3328 3329 3330 #endif // PRODUCT 3331 3332 3333 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3334 assert(reg_map != NULL, "a map must be given"); 3335 frame f = last_frame(); 3336 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3337 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3338 } 3339 return NULL; 3340 } 3341 3342 3343 Klass* JavaThread::security_get_caller_class(int depth) { 3344 vframeStream vfst(this); 3345 vfst.security_get_caller_frame(depth); 3346 if (!vfst.at_end()) { 3347 return vfst.method()->method_holder(); 3348 } 3349 return NULL; 3350 } 3351 3352 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3353 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3354 CompileBroker::compiler_thread_loop(); 3355 } 3356 3357 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3358 NMethodSweeper::sweeper_loop(); 3359 } 3360 3361 // Create a CompilerThread 3362 CompilerThread::CompilerThread(CompileQueue* queue, 3363 CompilerCounters* counters) 3364 : JavaThread(&compiler_thread_entry) { 3365 _env = NULL; 3366 _log = NULL; 3367 _task = NULL; 3368 _queue = queue; 3369 _counters = counters; 3370 _buffer_blob = NULL; 3371 _compiler = NULL; 3372 3373 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3374 resource_area()->bias_to(mtCompiler); 3375 3376 #ifndef PRODUCT 3377 _ideal_graph_printer = NULL; 3378 #endif 3379 } 3380 3381 bool CompilerThread::can_call_java() const { 3382 return _compiler != NULL && _compiler->is_jvmci(); 3383 } 3384 3385 // Create sweeper thread 3386 CodeCacheSweeperThread::CodeCacheSweeperThread() 3387 : JavaThread(&sweeper_thread_entry) { 3388 _scanned_compiled_method = NULL; 3389 } 3390 3391 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3392 JavaThread::oops_do(f, cf); 3393 if (_scanned_compiled_method != NULL && cf != NULL) { 3394 // Safepoints can occur when the sweeper is scanning an nmethod so 3395 // process it here to make sure it isn't unloaded in the middle of 3396 // a scan. 3397 cf->do_code_blob(_scanned_compiled_method); 3398 } 3399 } 3400 3401 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3402 JavaThread::nmethods_do(cf); 3403 if (_scanned_compiled_method != NULL && cf != NULL) { 3404 // Safepoints can occur when the sweeper is scanning an nmethod so 3405 // process it here to make sure it isn't unloaded in the middle of 3406 // a scan. 3407 cf->do_code_blob(_scanned_compiled_method); 3408 } 3409 } 3410 3411 3412 // ======= Threads ======== 3413 3414 // The Threads class links together all active threads, and provides 3415 // operations over all threads. It is protected by the Threads_lock, 3416 // which is also used in other global contexts like safepointing. 3417 // ThreadsListHandles are used to safely perform operations on one 3418 // or more threads without the risk of the thread exiting during the 3419 // operation. 3420 // 3421 // Note: The Threads_lock is currently more widely used than we 3422 // would like. We are actively migrating Threads_lock uses to other 3423 // mechanisms in order to reduce Threads_lock contention. 3424 3425 JavaThread* Threads::_thread_list = NULL; 3426 int Threads::_number_of_threads = 0; 3427 int Threads::_number_of_non_daemon_threads = 0; 3428 int Threads::_return_code = 0; 3429 int Threads::_thread_claim_parity = 0; 3430 size_t JavaThread::_stack_size_at_create = 0; 3431 3432 #ifdef ASSERT 3433 bool Threads::_vm_complete = false; 3434 #endif 3435 3436 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3437 Prefetch::read((void*)addr, prefetch_interval); 3438 return *addr; 3439 } 3440 3441 // Possibly the ugliest for loop the world has seen. C++ does not allow 3442 // multiple types in the declaration section of the for loop. In this case 3443 // we are only dealing with pointers and hence can cast them. It looks ugly 3444 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3445 #define DO_JAVA_THREADS(LIST, X) \ 3446 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3447 *MACRO_list = (JavaThread*)(LIST), \ 3448 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3449 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3450 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3451 MACRO_current_p != MACRO_end; \ 3452 MACRO_current_p++, \ 3453 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3454 3455 // All JavaThreads 3456 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3457 3458 // All non-JavaThreads (i.e., every non-JavaThread in the system). 3459 void Threads::non_java_threads_do(ThreadClosure* tc) { 3460 // Someday we could have a table or list of all non-JavaThreads. 3461 // For now, just manually iterate through them. 3462 tc->do_thread(VMThread::vm_thread()); 3463 if (Universe::heap() != NULL) { 3464 Universe::heap()->gc_threads_do(tc); 3465 } 3466 WatcherThread *wt = WatcherThread::watcher_thread(); 3467 // Strictly speaking, the following NULL check isn't sufficient to make sure 3468 // the data for WatcherThread is still valid upon being examined. However, 3469 // considering that WatchThread terminates when the VM is on the way to 3470 // exit at safepoint, the chance of the above is extremely small. The right 3471 // way to prevent termination of WatcherThread would be to acquire 3472 // Terminator_lock, but we can't do that without violating the lock rank 3473 // checking in some cases. 3474 if (wt != NULL) { 3475 tc->do_thread(wt); 3476 } 3477 3478 #if INCLUDE_TRACE 3479 Thread* sampler_thread = TracingExport::sampler_thread_acquire(); 3480 if (sampler_thread != NULL) { 3481 tc->do_thread(sampler_thread); 3482 } 3483 #endif 3484 3485 // If CompilerThreads ever become non-JavaThreads, add them here 3486 } 3487 3488 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system). 3489 void Threads::threads_do(ThreadClosure* tc) { 3490 assert_locked_or_safepoint(Threads_lock); 3491 // ALL_JAVA_THREADS iterates through all JavaThreads. 3492 ALL_JAVA_THREADS(p) { 3493 tc->do_thread(p); 3494 } 3495 non_java_threads_do(tc); 3496 } 3497 3498 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3499 int cp = Threads::thread_claim_parity(); 3500 ALL_JAVA_THREADS(p) { 3501 if (p->claim_oops_do(is_par, cp)) { 3502 tc->do_thread(p); 3503 } 3504 } 3505 VMThread* vmt = VMThread::vm_thread(); 3506 if (vmt->claim_oops_do(is_par, cp)) { 3507 tc->do_thread(vmt); 3508 } 3509 } 3510 3511 // The system initialization in the library has three phases. 3512 // 3513 // Phase 1: java.lang.System class initialization 3514 // java.lang.System is a primordial class loaded and initialized 3515 // by the VM early during startup. java.lang.System.<clinit> 3516 // only does registerNatives and keeps the rest of the class 3517 // initialization work later until thread initialization completes. 3518 // 3519 // System.initPhase1 initializes the system properties, the static 3520 // fields in, out, and err. Set up java signal handlers, OS-specific 3521 // system settings, and thread group of the main thread. 3522 static void call_initPhase1(TRAPS) { 3523 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3524 JavaValue result(T_VOID); 3525 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3526 vmSymbols::void_method_signature(), CHECK); 3527 } 3528 3529 // Phase 2. Module system initialization 3530 // This will initialize the module system. Only java.base classes 3531 // can be loaded until phase 2 completes. 3532 // 3533 // Call System.initPhase2 after the compiler initialization and jsr292 3534 // classes get initialized because module initialization runs a lot of java 3535 // code, that for performance reasons, should be compiled. Also, this will 3536 // enable the startup code to use lambda and other language features in this 3537 // phase and onward. 3538 // 3539 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3540 static void call_initPhase2(TRAPS) { 3541 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3542 3543 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3544 3545 JavaValue result(T_INT); 3546 JavaCallArguments args; 3547 args.push_int(DisplayVMOutputToStderr); 3548 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3549 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3550 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3551 if (result.get_jint() != JNI_OK) { 3552 vm_exit_during_initialization(); // no message or exception 3553 } 3554 3555 universe_post_module_init(); 3556 } 3557 3558 // Phase 3. final setup - set security manager, system class loader and TCCL 3559 // 3560 // This will instantiate and set the security manager, set the system class 3561 // loader as well as the thread context class loader. The security manager 3562 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3563 // other modules or the application's classpath. 3564 static void call_initPhase3(TRAPS) { 3565 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3566 JavaValue result(T_VOID); 3567 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3568 vmSymbols::void_method_signature(), CHECK); 3569 } 3570 3571 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3572 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3573 3574 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3575 create_vm_init_libraries(); 3576 } 3577 3578 initialize_class(vmSymbols::java_lang_String(), CHECK); 3579 3580 // Inject CompactStrings value after the static initializers for String ran. 3581 java_lang_String::set_compact_strings(CompactStrings); 3582 3583 // Initialize java_lang.System (needed before creating the thread) 3584 initialize_class(vmSymbols::java_lang_System(), CHECK); 3585 // The VM creates & returns objects of this class. Make sure it's initialized. 3586 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3587 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3588 Handle thread_group = create_initial_thread_group(CHECK); 3589 Universe::set_main_thread_group(thread_group()); 3590 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3591 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3592 main_thread->set_threadObj(thread_object); 3593 // Set thread status to running since main thread has 3594 // been started and running. 3595 java_lang_Thread::set_thread_status(thread_object, 3596 java_lang_Thread::RUNNABLE); 3597 3598 // The VM creates objects of this class. 3599 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3600 3601 // The VM preresolves methods to these classes. Make sure that they get initialized 3602 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3603 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3604 3605 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3606 call_initPhase1(CHECK); 3607 3608 // get the Java runtime name after java.lang.System is initialized 3609 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3610 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3611 3612 // an instance of OutOfMemory exception has been allocated earlier 3613 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3614 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3615 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3616 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3617 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3618 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3619 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3620 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3621 } 3622 3623 void Threads::initialize_jsr292_core_classes(TRAPS) { 3624 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3625 3626 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3627 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3628 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3629 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3630 } 3631 3632 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3633 extern void JDK_Version_init(); 3634 3635 // Preinitialize version info. 3636 VM_Version::early_initialize(); 3637 3638 // Check version 3639 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3640 3641 // Initialize library-based TLS 3642 ThreadLocalStorage::init(); 3643 3644 // Initialize the output stream module 3645 ostream_init(); 3646 3647 // Process java launcher properties. 3648 Arguments::process_sun_java_launcher_properties(args); 3649 3650 // Initialize the os module 3651 os::init(); 3652 3653 // Record VM creation timing statistics 3654 TraceVmCreationTime create_vm_timer; 3655 create_vm_timer.start(); 3656 3657 // Initialize system properties. 3658 Arguments::init_system_properties(); 3659 3660 // So that JDK version can be used as a discriminator when parsing arguments 3661 JDK_Version_init(); 3662 3663 // Update/Initialize System properties after JDK version number is known 3664 Arguments::init_version_specific_system_properties(); 3665 3666 // Make sure to initialize log configuration *before* parsing arguments 3667 LogConfiguration::initialize(create_vm_timer.begin_time()); 3668 3669 // Parse arguments 3670 // Note: this internally calls os::init_container_support() 3671 jint parse_result = Arguments::parse(args); 3672 if (parse_result != JNI_OK) return parse_result; 3673 3674 os::init_before_ergo(); 3675 3676 jint ergo_result = Arguments::apply_ergo(); 3677 if (ergo_result != JNI_OK) return ergo_result; 3678 3679 // Final check of all ranges after ergonomics which may change values. 3680 if (!CommandLineFlagRangeList::check_ranges()) { 3681 return JNI_EINVAL; 3682 } 3683 3684 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3685 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3686 if (!constraint_result) { 3687 return JNI_EINVAL; 3688 } 3689 3690 CommandLineFlagWriteableList::mark_startup(); 3691 3692 if (PauseAtStartup) { 3693 os::pause(); 3694 } 3695 3696 HOTSPOT_VM_INIT_BEGIN(); 3697 3698 // Timing (must come after argument parsing) 3699 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3700 3701 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3702 // Initialize assert poison page mechanism. 3703 if (ShowRegistersOnAssert) { 3704 initialize_assert_poison(); 3705 } 3706 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3707 3708 // Initialize the os module after parsing the args 3709 jint os_init_2_result = os::init_2(); 3710 if (os_init_2_result != JNI_OK) return os_init_2_result; 3711 3712 SafepointMechanism::initialize(); 3713 3714 jint adjust_after_os_result = Arguments::adjust_after_os(); 3715 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3716 3717 // Initialize output stream logging 3718 ostream_init_log(); 3719 3720 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3721 // Must be before create_vm_init_agents() 3722 if (Arguments::init_libraries_at_startup()) { 3723 convert_vm_init_libraries_to_agents(); 3724 } 3725 3726 // Launch -agentlib/-agentpath and converted -Xrun agents 3727 if (Arguments::init_agents_at_startup()) { 3728 create_vm_init_agents(); 3729 } 3730 3731 // Initialize Threads state 3732 _thread_list = NULL; 3733 _number_of_threads = 0; 3734 _number_of_non_daemon_threads = 0; 3735 3736 // Initialize global data structures and create system classes in heap 3737 vm_init_globals(); 3738 3739 #if INCLUDE_JVMCI 3740 if (JVMCICounterSize > 0) { 3741 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3742 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3743 } else { 3744 JavaThread::_jvmci_old_thread_counters = NULL; 3745 } 3746 #endif // INCLUDE_JVMCI 3747 3748 // Attach the main thread to this os thread 3749 JavaThread* main_thread = new JavaThread(); 3750 main_thread->set_thread_state(_thread_in_vm); 3751 main_thread->initialize_thread_current(); 3752 // must do this before set_active_handles 3753 main_thread->record_stack_base_and_size(); 3754 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3755 3756 if (!main_thread->set_as_starting_thread()) { 3757 vm_shutdown_during_initialization( 3758 "Failed necessary internal allocation. Out of swap space"); 3759 main_thread->smr_delete(); 3760 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3761 return JNI_ENOMEM; 3762 } 3763 3764 // Enable guard page *after* os::create_main_thread(), otherwise it would 3765 // crash Linux VM, see notes in os_linux.cpp. 3766 main_thread->create_stack_guard_pages(); 3767 3768 // Initialize Java-Level synchronization subsystem 3769 ObjectMonitor::Initialize(); 3770 3771 // Initialize global modules 3772 jint status = init_globals(); 3773 if (status != JNI_OK) { 3774 main_thread->smr_delete(); 3775 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3776 return status; 3777 } 3778 3779 if (TRACE_INITIALIZE() != JNI_OK) { 3780 vm_exit_during_initialization("Failed to initialize tracing backend"); 3781 } 3782 3783 // Should be done after the heap is fully created 3784 main_thread->cache_global_variables(); 3785 3786 HandleMark hm; 3787 3788 { MutexLocker mu(Threads_lock); 3789 Threads::add(main_thread); 3790 } 3791 3792 // Any JVMTI raw monitors entered in onload will transition into 3793 // real raw monitor. VM is setup enough here for raw monitor enter. 3794 JvmtiExport::transition_pending_onload_raw_monitors(); 3795 3796 // Create the VMThread 3797 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3798 3799 VMThread::create(); 3800 Thread* vmthread = VMThread::vm_thread(); 3801 3802 if (!os::create_thread(vmthread, os::vm_thread)) { 3803 vm_exit_during_initialization("Cannot create VM thread. " 3804 "Out of system resources."); 3805 } 3806 3807 // Wait for the VM thread to become ready, and VMThread::run to initialize 3808 // Monitors can have spurious returns, must always check another state flag 3809 { 3810 MutexLocker ml(Notify_lock); 3811 os::start_thread(vmthread); 3812 while (vmthread->active_handles() == NULL) { 3813 Notify_lock->wait(); 3814 } 3815 } 3816 } 3817 3818 assert(Universe::is_fully_initialized(), "not initialized"); 3819 if (VerifyDuringStartup) { 3820 // Make sure we're starting with a clean slate. 3821 VM_Verify verify_op; 3822 VMThread::execute(&verify_op); 3823 } 3824 3825 Thread* THREAD = Thread::current(); 3826 3827 // Always call even when there are not JVMTI environments yet, since environments 3828 // may be attached late and JVMTI must track phases of VM execution 3829 JvmtiExport::enter_early_start_phase(); 3830 3831 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3832 JvmtiExport::post_early_vm_start(); 3833 3834 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3835 3836 // We need this for ClassDataSharing - the initial vm.info property is set 3837 // with the default value of CDS "sharing" which may be reset through 3838 // command line options. 3839 reset_vm_info_property(CHECK_JNI_ERR); 3840 3841 quicken_jni_functions(); 3842 3843 // No more stub generation allowed after that point. 3844 StubCodeDesc::freeze(); 3845 3846 // Set flag that basic initialization has completed. Used by exceptions and various 3847 // debug stuff, that does not work until all basic classes have been initialized. 3848 set_init_completed(); 3849 3850 LogConfiguration::post_initialize(); 3851 Metaspace::post_initialize(); 3852 3853 HOTSPOT_VM_INIT_END(); 3854 3855 // record VM initialization completion time 3856 #if INCLUDE_MANAGEMENT 3857 Management::record_vm_init_completed(); 3858 #endif // INCLUDE_MANAGEMENT 3859 3860 // Signal Dispatcher needs to be started before VMInit event is posted 3861 os::signal_init(CHECK_JNI_ERR); 3862 3863 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3864 if (!DisableAttachMechanism) { 3865 AttachListener::vm_start(); 3866 if (StartAttachListener || AttachListener::init_at_startup()) { 3867 AttachListener::init(); 3868 } 3869 } 3870 3871 // Launch -Xrun agents 3872 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3873 // back-end can launch with -Xdebug -Xrunjdwp. 3874 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3875 create_vm_init_libraries(); 3876 } 3877 3878 if (CleanChunkPoolAsync) { 3879 Chunk::start_chunk_pool_cleaner_task(); 3880 } 3881 3882 // initialize compiler(s) 3883 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3884 #if INCLUDE_JVMCI 3885 bool force_JVMCI_intialization = false; 3886 if (EnableJVMCI) { 3887 // Initialize JVMCI eagerly when it is explicitly requested. 3888 // Or when JVMCIPrintProperties is enabled. 3889 // The JVMCI Java initialization code will read this flag and 3890 // do the printing if it's set. 3891 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3892 3893 if (!force_JVMCI_intialization) { 3894 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3895 // compilations via JVMCI will not actually block until JVMCI is initialized. 3896 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3897 } 3898 } 3899 #endif 3900 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3901 // Postpone completion of compiler initialization to after JVMCI 3902 // is initialized to avoid timeouts of blocking compilations. 3903 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3904 CompileBroker::compilation_init_phase2(); 3905 } 3906 #endif 3907 3908 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3909 // It is done after compilers are initialized, because otherwise compilations of 3910 // signature polymorphic MH intrinsics can be missed 3911 // (see SystemDictionary::find_method_handle_intrinsic). 3912 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3913 3914 // This will initialize the module system. Only java.base classes can be 3915 // loaded until phase 2 completes 3916 call_initPhase2(CHECK_JNI_ERR); 3917 3918 // Always call even when there are not JVMTI environments yet, since environments 3919 // may be attached late and JVMTI must track phases of VM execution 3920 JvmtiExport::enter_start_phase(); 3921 3922 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3923 JvmtiExport::post_vm_start(); 3924 3925 // Final system initialization including security manager and system class loader 3926 call_initPhase3(CHECK_JNI_ERR); 3927 3928 // cache the system and platform class loaders 3929 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3930 3931 #if INCLUDE_CDS 3932 if (DumpSharedSpaces) { 3933 // capture the module path info from the ModuleEntryTable 3934 ClassLoader::initialize_module_path(THREAD); 3935 } 3936 #endif 3937 3938 #if INCLUDE_JVMCI 3939 if (force_JVMCI_intialization) { 3940 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3941 CompileBroker::compilation_init_phase2(); 3942 } 3943 #endif 3944 3945 // Always call even when there are not JVMTI environments yet, since environments 3946 // may be attached late and JVMTI must track phases of VM execution 3947 JvmtiExport::enter_live_phase(); 3948 3949 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3950 JvmtiExport::post_vm_initialized(); 3951 3952 if (TRACE_START() != JNI_OK) { 3953 vm_exit_during_initialization("Failed to start tracing backend."); 3954 } 3955 3956 #if INCLUDE_MANAGEMENT 3957 Management::initialize(THREAD); 3958 3959 if (HAS_PENDING_EXCEPTION) { 3960 // management agent fails to start possibly due to 3961 // configuration problem and is responsible for printing 3962 // stack trace if appropriate. Simply exit VM. 3963 vm_exit(1); 3964 } 3965 #endif // INCLUDE_MANAGEMENT 3966 3967 if (MemProfiling) MemProfiler::engage(); 3968 StatSampler::engage(); 3969 if (CheckJNICalls) JniPeriodicChecker::engage(); 3970 3971 BiasedLocking::init(); 3972 3973 #if INCLUDE_RTM_OPT 3974 RTMLockingCounters::init(); 3975 #endif 3976 3977 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3978 call_postVMInitHook(THREAD); 3979 // The Java side of PostVMInitHook.run must deal with all 3980 // exceptions and provide means of diagnosis. 3981 if (HAS_PENDING_EXCEPTION) { 3982 CLEAR_PENDING_EXCEPTION; 3983 } 3984 } 3985 3986 { 3987 MutexLocker ml(PeriodicTask_lock); 3988 // Make sure the WatcherThread can be started by WatcherThread::start() 3989 // or by dynamic enrollment. 3990 WatcherThread::make_startable(); 3991 // Start up the WatcherThread if there are any periodic tasks 3992 // NOTE: All PeriodicTasks should be registered by now. If they 3993 // aren't, late joiners might appear to start slowly (we might 3994 // take a while to process their first tick). 3995 if (PeriodicTask::num_tasks() > 0) { 3996 WatcherThread::start(); 3997 } 3998 } 3999 4000 create_vm_timer.end(); 4001 #ifdef ASSERT 4002 _vm_complete = true; 4003 #endif 4004 4005 if (DumpSharedSpaces) { 4006 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 4007 ShouldNotReachHere(); 4008 } 4009 4010 return JNI_OK; 4011 } 4012 4013 // type for the Agent_OnLoad and JVM_OnLoad entry points 4014 extern "C" { 4015 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 4016 } 4017 // Find a command line agent library and return its entry point for 4018 // -agentlib: -agentpath: -Xrun 4019 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 4020 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 4021 const char *on_load_symbols[], 4022 size_t num_symbol_entries) { 4023 OnLoadEntry_t on_load_entry = NULL; 4024 void *library = NULL; 4025 4026 if (!agent->valid()) { 4027 char buffer[JVM_MAXPATHLEN]; 4028 char ebuf[1024] = ""; 4029 const char *name = agent->name(); 4030 const char *msg = "Could not find agent library "; 4031 4032 // First check to see if agent is statically linked into executable 4033 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 4034 library = agent->os_lib(); 4035 } else if (agent->is_absolute_path()) { 4036 library = os::dll_load(name, ebuf, sizeof ebuf); 4037 if (library == NULL) { 4038 const char *sub_msg = " in absolute path, with error: "; 4039 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 4040 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4041 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4042 // If we can't find the agent, exit. 4043 vm_exit_during_initialization(buf, NULL); 4044 FREE_C_HEAP_ARRAY(char, buf); 4045 } 4046 } else { 4047 // Try to load the agent from the standard dll directory 4048 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4049 name)) { 4050 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4051 } 4052 if (library == NULL) { // Try the library path directory. 4053 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4054 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4055 } 4056 if (library == NULL) { 4057 const char *sub_msg = " on the library path, with error: "; 4058 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4059 4060 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4061 strlen(ebuf) + strlen(sub_msg2) + 1; 4062 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4063 if (!agent->is_instrument_lib()) { 4064 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4065 } else { 4066 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4067 } 4068 // If we can't find the agent, exit. 4069 vm_exit_during_initialization(buf, NULL); 4070 FREE_C_HEAP_ARRAY(char, buf); 4071 } 4072 } 4073 } 4074 agent->set_os_lib(library); 4075 agent->set_valid(); 4076 } 4077 4078 // Find the OnLoad function. 4079 on_load_entry = 4080 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4081 false, 4082 on_load_symbols, 4083 num_symbol_entries)); 4084 return on_load_entry; 4085 } 4086 4087 // Find the JVM_OnLoad entry point 4088 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4089 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4090 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4091 } 4092 4093 // Find the Agent_OnLoad entry point 4094 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4095 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4096 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4097 } 4098 4099 // For backwards compatibility with -Xrun 4100 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4101 // treated like -agentpath: 4102 // Must be called before agent libraries are created 4103 void Threads::convert_vm_init_libraries_to_agents() { 4104 AgentLibrary* agent; 4105 AgentLibrary* next; 4106 4107 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4108 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4109 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4110 4111 // If there is an JVM_OnLoad function it will get called later, 4112 // otherwise see if there is an Agent_OnLoad 4113 if (on_load_entry == NULL) { 4114 on_load_entry = lookup_agent_on_load(agent); 4115 if (on_load_entry != NULL) { 4116 // switch it to the agent list -- so that Agent_OnLoad will be called, 4117 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4118 Arguments::convert_library_to_agent(agent); 4119 } else { 4120 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4121 } 4122 } 4123 } 4124 } 4125 4126 // Create agents for -agentlib: -agentpath: and converted -Xrun 4127 // Invokes Agent_OnLoad 4128 // Called very early -- before JavaThreads exist 4129 void Threads::create_vm_init_agents() { 4130 extern struct JavaVM_ main_vm; 4131 AgentLibrary* agent; 4132 4133 JvmtiExport::enter_onload_phase(); 4134 4135 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4136 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4137 4138 if (on_load_entry != NULL) { 4139 // Invoke the Agent_OnLoad function 4140 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4141 if (err != JNI_OK) { 4142 vm_exit_during_initialization("agent library failed to init", agent->name()); 4143 } 4144 } else { 4145 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4146 } 4147 } 4148 JvmtiExport::enter_primordial_phase(); 4149 } 4150 4151 extern "C" { 4152 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4153 } 4154 4155 void Threads::shutdown_vm_agents() { 4156 // Send any Agent_OnUnload notifications 4157 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4158 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4159 extern struct JavaVM_ main_vm; 4160 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4161 4162 // Find the Agent_OnUnload function. 4163 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4164 os::find_agent_function(agent, 4165 false, 4166 on_unload_symbols, 4167 num_symbol_entries)); 4168 4169 // Invoke the Agent_OnUnload function 4170 if (unload_entry != NULL) { 4171 JavaThread* thread = JavaThread::current(); 4172 ThreadToNativeFromVM ttn(thread); 4173 HandleMark hm(thread); 4174 (*unload_entry)(&main_vm); 4175 } 4176 } 4177 } 4178 4179 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4180 // Invokes JVM_OnLoad 4181 void Threads::create_vm_init_libraries() { 4182 extern struct JavaVM_ main_vm; 4183 AgentLibrary* agent; 4184 4185 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4186 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4187 4188 if (on_load_entry != NULL) { 4189 // Invoke the JVM_OnLoad function 4190 JavaThread* thread = JavaThread::current(); 4191 ThreadToNativeFromVM ttn(thread); 4192 HandleMark hm(thread); 4193 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4194 if (err != JNI_OK) { 4195 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4196 } 4197 } else { 4198 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4199 } 4200 } 4201 } 4202 4203 4204 // Last thread running calls java.lang.Shutdown.shutdown() 4205 void JavaThread::invoke_shutdown_hooks() { 4206 HandleMark hm(this); 4207 4208 // We could get here with a pending exception, if so clear it now. 4209 if (this->has_pending_exception()) { 4210 this->clear_pending_exception(); 4211 } 4212 4213 EXCEPTION_MARK; 4214 Klass* shutdown_klass = 4215 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4216 THREAD); 4217 if (shutdown_klass != NULL) { 4218 // SystemDictionary::resolve_or_null will return null if there was 4219 // an exception. If we cannot load the Shutdown class, just don't 4220 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4221 // won't be run. Note that if a shutdown hook was registered, 4222 // the Shutdown class would have already been loaded 4223 // (Runtime.addShutdownHook will load it). 4224 JavaValue result(T_VOID); 4225 JavaCalls::call_static(&result, 4226 shutdown_klass, 4227 vmSymbols::shutdown_method_name(), 4228 vmSymbols::void_method_signature(), 4229 THREAD); 4230 } 4231 CLEAR_PENDING_EXCEPTION; 4232 } 4233 4234 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4235 // the program falls off the end of main(). Another VM exit path is through 4236 // vm_exit() when the program calls System.exit() to return a value or when 4237 // there is a serious error in VM. The two shutdown paths are not exactly 4238 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4239 // and VM_Exit op at VM level. 4240 // 4241 // Shutdown sequence: 4242 // + Shutdown native memory tracking if it is on 4243 // + Wait until we are the last non-daemon thread to execute 4244 // <-- every thing is still working at this moment --> 4245 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4246 // shutdown hooks 4247 // + Call before_exit(), prepare for VM exit 4248 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4249 // currently the only user of this mechanism is File.deleteOnExit()) 4250 // > stop StatSampler, watcher thread, CMS threads, 4251 // post thread end and vm death events to JVMTI, 4252 // stop signal thread 4253 // + Call JavaThread::exit(), it will: 4254 // > release JNI handle blocks, remove stack guard pages 4255 // > remove this thread from Threads list 4256 // <-- no more Java code from this thread after this point --> 4257 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4258 // the compiler threads at safepoint 4259 // <-- do not use anything that could get blocked by Safepoint --> 4260 // + Disable tracing at JNI/JVM barriers 4261 // + Set _vm_exited flag for threads that are still running native code 4262 // + Delete this thread 4263 // + Call exit_globals() 4264 // > deletes tty 4265 // > deletes PerfMemory resources 4266 // + Return to caller 4267 4268 bool Threads::destroy_vm() { 4269 JavaThread* thread = JavaThread::current(); 4270 4271 #ifdef ASSERT 4272 _vm_complete = false; 4273 #endif 4274 // Wait until we are the last non-daemon thread to execute 4275 { MutexLocker nu(Threads_lock); 4276 while (Threads::number_of_non_daemon_threads() > 1) 4277 // This wait should make safepoint checks, wait without a timeout, 4278 // and wait as a suspend-equivalent condition. 4279 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4280 Mutex::_as_suspend_equivalent_flag); 4281 } 4282 4283 EventShutdown e; 4284 if (e.should_commit()) { 4285 e.set_reason("No remaining non-daemon Java threads"); 4286 e.commit(); 4287 } 4288 4289 // Hang forever on exit if we are reporting an error. 4290 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4291 os::infinite_sleep(); 4292 } 4293 os::wait_for_keypress_at_exit(); 4294 4295 // run Java level shutdown hooks 4296 thread->invoke_shutdown_hooks(); 4297 4298 before_exit(thread); 4299 4300 thread->exit(true); 4301 4302 // Stop VM thread. 4303 { 4304 // 4945125 The vm thread comes to a safepoint during exit. 4305 // GC vm_operations can get caught at the safepoint, and the 4306 // heap is unparseable if they are caught. Grab the Heap_lock 4307 // to prevent this. The GC vm_operations will not be able to 4308 // queue until after the vm thread is dead. After this point, 4309 // we'll never emerge out of the safepoint before the VM exits. 4310 4311 MutexLocker ml(Heap_lock); 4312 4313 VMThread::wait_for_vm_thread_exit(); 4314 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4315 VMThread::destroy(); 4316 } 4317 4318 // Now, all Java threads are gone except daemon threads. Daemon threads 4319 // running Java code or in VM are stopped by the Safepoint. However, 4320 // daemon threads executing native code are still running. But they 4321 // will be stopped at native=>Java/VM barriers. Note that we can't 4322 // simply kill or suspend them, as it is inherently deadlock-prone. 4323 4324 VM_Exit::set_vm_exited(); 4325 4326 // Clean up ideal graph printers after the VMThread has started 4327 // the final safepoint which will block all the Compiler threads. 4328 // Note that this Thread has already logically exited so the 4329 // clean_up() function's use of a JavaThreadIteratorWithHandle 4330 // would be a problem except set_vm_exited() has remembered the 4331 // shutdown thread which is granted a policy exception. 4332 #if defined(COMPILER2) && !defined(PRODUCT) 4333 IdealGraphPrinter::clean_up(); 4334 #endif 4335 4336 notify_vm_shutdown(); 4337 4338 // We are after VM_Exit::set_vm_exited() so we can't call 4339 // thread->smr_delete() or we will block on the Threads_lock. 4340 // Deleting the shutdown thread here is safe because another 4341 // JavaThread cannot have an active ThreadsListHandle for 4342 // this JavaThread. 4343 delete thread; 4344 4345 #if INCLUDE_JVMCI 4346 if (JVMCICounterSize > 0) { 4347 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4348 } 4349 #endif 4350 4351 // exit_globals() will delete tty 4352 exit_globals(); 4353 4354 LogConfiguration::finalize(); 4355 4356 return true; 4357 } 4358 4359 4360 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4361 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4362 return is_supported_jni_version(version); 4363 } 4364 4365 4366 jboolean Threads::is_supported_jni_version(jint version) { 4367 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4368 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4369 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4370 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4371 if (version == JNI_VERSION_9) return JNI_TRUE; 4372 if (version == JNI_VERSION_10) return JNI_TRUE; 4373 return JNI_FALSE; 4374 } 4375 4376 4377 void Threads::add(JavaThread* p, bool force_daemon) { 4378 // The threads lock must be owned at this point 4379 assert_locked_or_safepoint(Threads_lock); 4380 4381 BarrierSet::barrier_set()->on_thread_attach(p); 4382 4383 p->set_next(_thread_list); 4384 _thread_list = p; 4385 4386 // Once a JavaThread is added to the Threads list, smr_delete() has 4387 // to be used to delete it. Otherwise we can just delete it directly. 4388 p->set_on_thread_list(); 4389 4390 _number_of_threads++; 4391 oop threadObj = p->threadObj(); 4392 bool daemon = true; 4393 // Bootstrapping problem: threadObj can be null for initial 4394 // JavaThread (or for threads attached via JNI) 4395 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4396 _number_of_non_daemon_threads++; 4397 daemon = false; 4398 } 4399 4400 ThreadService::add_thread(p, daemon); 4401 4402 // Maintain fast thread list 4403 ThreadsSMRSupport::add_thread(p); 4404 4405 // Possible GC point. 4406 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4407 } 4408 4409 void Threads::remove(JavaThread* p) { 4410 4411 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4412 ObjectSynchronizer::omFlush(p); 4413 4414 // Extra scope needed for Thread_lock, so we can check 4415 // that we do not remove thread without safepoint code notice 4416 { MutexLocker ml(Threads_lock); 4417 4418 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4419 4420 // Maintain fast thread list 4421 ThreadsSMRSupport::remove_thread(p); 4422 4423 JavaThread* current = _thread_list; 4424 JavaThread* prev = NULL; 4425 4426 while (current != p) { 4427 prev = current; 4428 current = current->next(); 4429 } 4430 4431 if (prev) { 4432 prev->set_next(current->next()); 4433 } else { 4434 _thread_list = p->next(); 4435 } 4436 4437 _number_of_threads--; 4438 oop threadObj = p->threadObj(); 4439 bool daemon = true; 4440 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4441 _number_of_non_daemon_threads--; 4442 daemon = false; 4443 4444 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4445 // on destroy_vm will wake up. 4446 if (number_of_non_daemon_threads() == 1) { 4447 Threads_lock->notify_all(); 4448 } 4449 } 4450 ThreadService::remove_thread(p, daemon); 4451 4452 // Make sure that safepoint code disregard this thread. This is needed since 4453 // the thread might mess around with locks after this point. This can cause it 4454 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4455 // of this thread since it is removed from the queue. 4456 p->set_terminated_value(); 4457 } // unlock Threads_lock 4458 4459 // Since Events::log uses a lock, we grab it outside the Threads_lock 4460 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4461 } 4462 4463 // Operations on the Threads list for GC. These are not explicitly locked, 4464 // but the garbage collector must provide a safe context for them to run. 4465 // In particular, these things should never be called when the Threads_lock 4466 // is held by some other thread. (Note: the Safepoint abstraction also 4467 // uses the Threads_lock to guarantee this property. It also makes sure that 4468 // all threads gets blocked when exiting or starting). 4469 4470 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4471 ALL_JAVA_THREADS(p) { 4472 p->oops_do(f, cf); 4473 } 4474 VMThread::vm_thread()->oops_do(f, cf); 4475 } 4476 4477 void Threads::change_thread_claim_parity() { 4478 // Set the new claim parity. 4479 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4480 "Not in range."); 4481 _thread_claim_parity++; 4482 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4483 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4484 "Not in range."); 4485 } 4486 4487 #ifdef ASSERT 4488 void Threads::assert_all_threads_claimed() { 4489 ALL_JAVA_THREADS(p) { 4490 const int thread_parity = p->oops_do_parity(); 4491 assert((thread_parity == _thread_claim_parity), 4492 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4493 } 4494 VMThread* vmt = VMThread::vm_thread(); 4495 const int thread_parity = vmt->oops_do_parity(); 4496 assert((thread_parity == _thread_claim_parity), 4497 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4498 } 4499 #endif // ASSERT 4500 4501 class ParallelOopsDoThreadClosure : public ThreadClosure { 4502 private: 4503 OopClosure* _f; 4504 CodeBlobClosure* _cf; 4505 public: 4506 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4507 void do_thread(Thread* t) { 4508 t->oops_do(_f, _cf); 4509 } 4510 }; 4511 4512 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4513 ParallelOopsDoThreadClosure tc(f, cf); 4514 possibly_parallel_threads_do(is_par, &tc); 4515 } 4516 4517 #if INCLUDE_ALL_GCS 4518 // Used by ParallelScavenge 4519 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4520 ALL_JAVA_THREADS(p) { 4521 q->enqueue(new ThreadRootsTask(p)); 4522 } 4523 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4524 } 4525 4526 // Used by Parallel Old 4527 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4528 ALL_JAVA_THREADS(p) { 4529 q->enqueue(new ThreadRootsMarkingTask(p)); 4530 } 4531 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4532 } 4533 #endif // INCLUDE_ALL_GCS 4534 4535 void Threads::nmethods_do(CodeBlobClosure* cf) { 4536 ALL_JAVA_THREADS(p) { 4537 // This is used by the code cache sweeper to mark nmethods that are active 4538 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4539 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4540 if(!p->is_Code_cache_sweeper_thread()) { 4541 p->nmethods_do(cf); 4542 } 4543 } 4544 } 4545 4546 void Threads::metadata_do(void f(Metadata*)) { 4547 ALL_JAVA_THREADS(p) { 4548 p->metadata_do(f); 4549 } 4550 } 4551 4552 class ThreadHandlesClosure : public ThreadClosure { 4553 void (*_f)(Metadata*); 4554 public: 4555 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4556 virtual void do_thread(Thread* thread) { 4557 thread->metadata_handles_do(_f); 4558 } 4559 }; 4560 4561 void Threads::metadata_handles_do(void f(Metadata*)) { 4562 // Only walk the Handles in Thread. 4563 ThreadHandlesClosure handles_closure(f); 4564 threads_do(&handles_closure); 4565 } 4566 4567 void Threads::deoptimized_wrt_marked_nmethods() { 4568 ALL_JAVA_THREADS(p) { 4569 p->deoptimized_wrt_marked_nmethods(); 4570 } 4571 } 4572 4573 4574 // Get count Java threads that are waiting to enter the specified monitor. 4575 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4576 int count, 4577 address monitor) { 4578 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4579 4580 int i = 0; 4581 DO_JAVA_THREADS(t_list, p) { 4582 if (!p->can_call_java()) continue; 4583 4584 address pending = (address)p->current_pending_monitor(); 4585 if (pending == monitor) { // found a match 4586 if (i < count) result->append(p); // save the first count matches 4587 i++; 4588 } 4589 } 4590 4591 return result; 4592 } 4593 4594 4595 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4596 address owner) { 4597 // NULL owner means not locked so we can skip the search 4598 if (owner == NULL) return NULL; 4599 4600 DO_JAVA_THREADS(t_list, p) { 4601 // first, see if owner is the address of a Java thread 4602 if (owner == (address)p) return p; 4603 } 4604 4605 // Cannot assert on lack of success here since this function may be 4606 // used by code that is trying to report useful problem information 4607 // like deadlock detection. 4608 if (UseHeavyMonitors) return NULL; 4609 4610 // If we didn't find a matching Java thread and we didn't force use of 4611 // heavyweight monitors, then the owner is the stack address of the 4612 // Lock Word in the owning Java thread's stack. 4613 // 4614 JavaThread* the_owner = NULL; 4615 DO_JAVA_THREADS(t_list, q) { 4616 if (q->is_lock_owned(owner)) { 4617 the_owner = q; 4618 break; 4619 } 4620 } 4621 4622 // cannot assert on lack of success here; see above comment 4623 return the_owner; 4624 } 4625 4626 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4627 void Threads::print_on(outputStream* st, bool print_stacks, 4628 bool internal_format, bool print_concurrent_locks) { 4629 char buf[32]; 4630 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4631 4632 st->print_cr("Full thread dump %s (%s %s):", 4633 Abstract_VM_Version::vm_name(), 4634 Abstract_VM_Version::vm_release(), 4635 Abstract_VM_Version::vm_info_string()); 4636 st->cr(); 4637 4638 #if INCLUDE_SERVICES 4639 // Dump concurrent locks 4640 ConcurrentLocksDump concurrent_locks; 4641 if (print_concurrent_locks) { 4642 concurrent_locks.dump_at_safepoint(); 4643 } 4644 #endif // INCLUDE_SERVICES 4645 4646 ThreadsSMRSupport::print_info_on(st); 4647 st->cr(); 4648 4649 ALL_JAVA_THREADS(p) { 4650 ResourceMark rm; 4651 p->print_on(st); 4652 if (print_stacks) { 4653 if (internal_format) { 4654 p->trace_stack(); 4655 } else { 4656 p->print_stack_on(st); 4657 } 4658 } 4659 st->cr(); 4660 #if INCLUDE_SERVICES 4661 if (print_concurrent_locks) { 4662 concurrent_locks.print_locks_on(p, st); 4663 } 4664 #endif // INCLUDE_SERVICES 4665 } 4666 4667 VMThread::vm_thread()->print_on(st); 4668 st->cr(); 4669 Universe::heap()->print_gc_threads_on(st); 4670 WatcherThread* wt = WatcherThread::watcher_thread(); 4671 if (wt != NULL) { 4672 wt->print_on(st); 4673 st->cr(); 4674 } 4675 4676 st->flush(); 4677 } 4678 4679 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4680 int buflen, bool* found_current) { 4681 if (this_thread != NULL) { 4682 bool is_current = (current == this_thread); 4683 *found_current = *found_current || is_current; 4684 st->print("%s", is_current ? "=>" : " "); 4685 4686 st->print(PTR_FORMAT, p2i(this_thread)); 4687 st->print(" "); 4688 this_thread->print_on_error(st, buf, buflen); 4689 st->cr(); 4690 } 4691 } 4692 4693 class PrintOnErrorClosure : public ThreadClosure { 4694 outputStream* _st; 4695 Thread* _current; 4696 char* _buf; 4697 int _buflen; 4698 bool* _found_current; 4699 public: 4700 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4701 int buflen, bool* found_current) : 4702 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4703 4704 virtual void do_thread(Thread* thread) { 4705 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4706 } 4707 }; 4708 4709 // Threads::print_on_error() is called by fatal error handler. It's possible 4710 // that VM is not at safepoint and/or current thread is inside signal handler. 4711 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4712 // memory (even in resource area), it might deadlock the error handler. 4713 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4714 int buflen) { 4715 ThreadsSMRSupport::print_info_on(st); 4716 st->cr(); 4717 4718 bool found_current = false; 4719 st->print_cr("Java Threads: ( => current thread )"); 4720 ALL_JAVA_THREADS(thread) { 4721 print_on_error(thread, st, current, buf, buflen, &found_current); 4722 } 4723 st->cr(); 4724 4725 st->print_cr("Other Threads:"); 4726 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4727 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4728 4729 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4730 Universe::heap()->gc_threads_do(&print_closure); 4731 4732 if (!found_current) { 4733 st->cr(); 4734 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4735 current->print_on_error(st, buf, buflen); 4736 st->cr(); 4737 } 4738 st->cr(); 4739 4740 st->print_cr("Threads with active compile tasks:"); 4741 print_threads_compiling(st, buf, buflen); 4742 } 4743 4744 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4745 ALL_JAVA_THREADS(thread) { 4746 if (thread->is_Compiler_thread()) { 4747 CompilerThread* ct = (CompilerThread*) thread; 4748 4749 // Keep task in local variable for NULL check. 4750 // ct->_task might be set to NULL by concurring compiler thread 4751 // because it completed the compilation. The task is never freed, 4752 // though, just returned to a free list. 4753 CompileTask* task = ct->task(); 4754 if (task != NULL) { 4755 thread->print_name_on_error(st, buf, buflen); 4756 task->print(st, NULL, true, true); 4757 } 4758 } 4759 } 4760 } 4761 4762 4763 // Internal SpinLock and Mutex 4764 // Based on ParkEvent 4765 4766 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4767 // 4768 // We employ SpinLocks _only for low-contention, fixed-length 4769 // short-duration critical sections where we're concerned 4770 // about native mutex_t or HotSpot Mutex:: latency. 4771 // The mux construct provides a spin-then-block mutual exclusion 4772 // mechanism. 4773 // 4774 // Testing has shown that contention on the ListLock guarding gFreeList 4775 // is common. If we implement ListLock as a simple SpinLock it's common 4776 // for the JVM to devolve to yielding with little progress. This is true 4777 // despite the fact that the critical sections protected by ListLock are 4778 // extremely short. 4779 // 4780 // TODO-FIXME: ListLock should be of type SpinLock. 4781 // We should make this a 1st-class type, integrated into the lock 4782 // hierarchy as leaf-locks. Critically, the SpinLock structure 4783 // should have sufficient padding to avoid false-sharing and excessive 4784 // cache-coherency traffic. 4785 4786 4787 typedef volatile int SpinLockT; 4788 4789 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4790 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4791 return; // normal fast-path return 4792 } 4793 4794 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4795 TEVENT(SpinAcquire - ctx); 4796 int ctr = 0; 4797 int Yields = 0; 4798 for (;;) { 4799 while (*adr != 0) { 4800 ++ctr; 4801 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4802 if (Yields > 5) { 4803 os::naked_short_sleep(1); 4804 } else { 4805 os::naked_yield(); 4806 ++Yields; 4807 } 4808 } else { 4809 SpinPause(); 4810 } 4811 } 4812 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4813 } 4814 } 4815 4816 void Thread::SpinRelease(volatile int * adr) { 4817 assert(*adr != 0, "invariant"); 4818 OrderAccess::fence(); // guarantee at least release consistency. 4819 // Roach-motel semantics. 4820 // It's safe if subsequent LDs and STs float "up" into the critical section, 4821 // but prior LDs and STs within the critical section can't be allowed 4822 // to reorder or float past the ST that releases the lock. 4823 // Loads and stores in the critical section - which appear in program 4824 // order before the store that releases the lock - must also appear 4825 // before the store that releases the lock in memory visibility order. 4826 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4827 // the ST of 0 into the lock-word which releases the lock, so fence 4828 // more than covers this on all platforms. 4829 *adr = 0; 4830 } 4831 4832 // muxAcquire and muxRelease: 4833 // 4834 // * muxAcquire and muxRelease support a single-word lock-word construct. 4835 // The LSB of the word is set IFF the lock is held. 4836 // The remainder of the word points to the head of a singly-linked list 4837 // of threads blocked on the lock. 4838 // 4839 // * The current implementation of muxAcquire-muxRelease uses its own 4840 // dedicated Thread._MuxEvent instance. If we're interested in 4841 // minimizing the peak number of extant ParkEvent instances then 4842 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4843 // as certain invariants were satisfied. Specifically, care would need 4844 // to be taken with regards to consuming unpark() "permits". 4845 // A safe rule of thumb is that a thread would never call muxAcquire() 4846 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4847 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4848 // consume an unpark() permit intended for monitorenter, for instance. 4849 // One way around this would be to widen the restricted-range semaphore 4850 // implemented in park(). Another alternative would be to provide 4851 // multiple instances of the PlatformEvent() for each thread. One 4852 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4853 // 4854 // * Usage: 4855 // -- Only as leaf locks 4856 // -- for short-term locking only as muxAcquire does not perform 4857 // thread state transitions. 4858 // 4859 // Alternatives: 4860 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4861 // but with parking or spin-then-park instead of pure spinning. 4862 // * Use Taura-Oyama-Yonenzawa locks. 4863 // * It's possible to construct a 1-0 lock if we encode the lockword as 4864 // (List,LockByte). Acquire will CAS the full lockword while Release 4865 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4866 // acquiring threads use timers (ParkTimed) to detect and recover from 4867 // the stranding window. Thread/Node structures must be aligned on 256-byte 4868 // boundaries by using placement-new. 4869 // * Augment MCS with advisory back-link fields maintained with CAS(). 4870 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4871 // The validity of the backlinks must be ratified before we trust the value. 4872 // If the backlinks are invalid the exiting thread must back-track through the 4873 // the forward links, which are always trustworthy. 4874 // * Add a successor indication. The LockWord is currently encoded as 4875 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4876 // to provide the usual futile-wakeup optimization. 4877 // See RTStt for details. 4878 // * Consider schedctl.sc_nopreempt to cover the critical section. 4879 // 4880 4881 4882 const intptr_t LOCKBIT = 1; 4883 4884 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4885 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4886 if (w == 0) return; 4887 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4888 return; 4889 } 4890 4891 TEVENT(muxAcquire - Contention); 4892 ParkEvent * const Self = Thread::current()->_MuxEvent; 4893 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4894 for (;;) { 4895 int its = (os::is_MP() ? 100 : 0) + 1; 4896 4897 // Optional spin phase: spin-then-park strategy 4898 while (--its >= 0) { 4899 w = *Lock; 4900 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4901 return; 4902 } 4903 } 4904 4905 Self->reset(); 4906 Self->OnList = intptr_t(Lock); 4907 // The following fence() isn't _strictly necessary as the subsequent 4908 // CAS() both serializes execution and ratifies the fetched *Lock value. 4909 OrderAccess::fence(); 4910 for (;;) { 4911 w = *Lock; 4912 if ((w & LOCKBIT) == 0) { 4913 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4914 Self->OnList = 0; // hygiene - allows stronger asserts 4915 return; 4916 } 4917 continue; // Interference -- *Lock changed -- Just retry 4918 } 4919 assert(w & LOCKBIT, "invariant"); 4920 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4921 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4922 } 4923 4924 while (Self->OnList != 0) { 4925 Self->park(); 4926 } 4927 } 4928 } 4929 4930 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4931 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4932 if (w == 0) return; 4933 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4934 return; 4935 } 4936 4937 TEVENT(muxAcquire - Contention); 4938 ParkEvent * ReleaseAfter = NULL; 4939 if (ev == NULL) { 4940 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4941 } 4942 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4943 for (;;) { 4944 guarantee(ev->OnList == 0, "invariant"); 4945 int its = (os::is_MP() ? 100 : 0) + 1; 4946 4947 // Optional spin phase: spin-then-park strategy 4948 while (--its >= 0) { 4949 w = *Lock; 4950 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4951 if (ReleaseAfter != NULL) { 4952 ParkEvent::Release(ReleaseAfter); 4953 } 4954 return; 4955 } 4956 } 4957 4958 ev->reset(); 4959 ev->OnList = intptr_t(Lock); 4960 // The following fence() isn't _strictly necessary as the subsequent 4961 // CAS() both serializes execution and ratifies the fetched *Lock value. 4962 OrderAccess::fence(); 4963 for (;;) { 4964 w = *Lock; 4965 if ((w & LOCKBIT) == 0) { 4966 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4967 ev->OnList = 0; 4968 // We call ::Release while holding the outer lock, thus 4969 // artificially lengthening the critical section. 4970 // Consider deferring the ::Release() until the subsequent unlock(), 4971 // after we've dropped the outer lock. 4972 if (ReleaseAfter != NULL) { 4973 ParkEvent::Release(ReleaseAfter); 4974 } 4975 return; 4976 } 4977 continue; // Interference -- *Lock changed -- Just retry 4978 } 4979 assert(w & LOCKBIT, "invariant"); 4980 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4981 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4982 } 4983 4984 while (ev->OnList != 0) { 4985 ev->park(); 4986 } 4987 } 4988 } 4989 4990 // Release() must extract a successor from the list and then wake that thread. 4991 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4992 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4993 // Release() would : 4994 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4995 // (B) Extract a successor from the private list "in-hand" 4996 // (C) attempt to CAS() the residual back into *Lock over null. 4997 // If there were any newly arrived threads and the CAS() would fail. 4998 // In that case Release() would detach the RATs, re-merge the list in-hand 4999 // with the RATs and repeat as needed. Alternately, Release() might 5000 // detach and extract a successor, but then pass the residual list to the wakee. 5001 // The wakee would be responsible for reattaching and remerging before it 5002 // competed for the lock. 5003 // 5004 // Both "pop" and DMR are immune from ABA corruption -- there can be 5005 // multiple concurrent pushers, but only one popper or detacher. 5006 // This implementation pops from the head of the list. This is unfair, 5007 // but tends to provide excellent throughput as hot threads remain hot. 5008 // (We wake recently run threads first). 5009 // 5010 // All paths through muxRelease() will execute a CAS. 5011 // Release consistency -- We depend on the CAS in muxRelease() to provide full 5012 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 5013 // executed within the critical section are complete and globally visible before the 5014 // store (CAS) to the lock-word that releases the lock becomes globally visible. 5015 void Thread::muxRelease(volatile intptr_t * Lock) { 5016 for (;;) { 5017 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 5018 assert(w & LOCKBIT, "invariant"); 5019 if (w == LOCKBIT) return; 5020 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 5021 assert(List != NULL, "invariant"); 5022 assert(List->OnList == intptr_t(Lock), "invariant"); 5023 ParkEvent * const nxt = List->ListNext; 5024 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 5025 5026 // The following CAS() releases the lock and pops the head element. 5027 // The CAS() also ratifies the previously fetched lock-word value. 5028 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 5029 continue; 5030 } 5031 List->OnList = 0; 5032 OrderAccess::fence(); 5033 List->unpark(); 5034 return; 5035 } 5036 } 5037 5038 5039 void Threads::verify() { 5040 ALL_JAVA_THREADS(p) { 5041 p->verify(); 5042 } 5043 VMThread* thread = VMThread::vm_thread(); 5044 if (thread != NULL) thread->verify(); 5045 }