1 /* 2 * Copyright (c) 1997, 2016, 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 "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/moduleEntry.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/codeCacheExtensions.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/gcId.hpp" 37 #include "gc/shared/gcLocker.inline.hpp" 38 #include "gc/shared/workgroup.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "interpreter/linkResolver.hpp" 41 #include "interpreter/oopMapCache.hpp" 42 #include "jvmtifiles/jvmtiEnv.hpp" 43 #include "logging/log.hpp" 44 #include "logging/logConfiguration.hpp" 45 #include "memory/metaspaceShared.hpp" 46 #include "memory/oopFactory.hpp" 47 #include "memory/resourceArea.hpp" 48 #include "memory/universe.inline.hpp" 49 #include "oops/instanceKlass.hpp" 50 #include "oops/objArrayOop.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "oops/symbol.hpp" 53 #include "oops/verifyOopClosure.hpp" 54 #include "prims/jvm_misc.hpp" 55 #include "prims/jvmtiExport.hpp" 56 #include "prims/jvmtiThreadState.hpp" 57 #include "prims/privilegedStack.hpp" 58 #include "runtime/arguments.hpp" 59 #include "runtime/atomic.hpp" 60 #include "runtime/biasedLocking.hpp" 61 #include "runtime/commandLineFlagConstraintList.hpp" 62 #include "runtime/commandLineFlagWriteableList.hpp" 63 #include "runtime/commandLineFlagRangeList.hpp" 64 #include "runtime/deoptimization.hpp" 65 #include "runtime/fprofiler.hpp" 66 #include "runtime/frame.inline.hpp" 67 #include "runtime/globals.hpp" 68 #include "runtime/init.hpp" 69 #include "runtime/interfaceSupport.hpp" 70 #include "runtime/java.hpp" 71 #include "runtime/javaCalls.hpp" 72 #include "runtime/jniPeriodicChecker.hpp" 73 #include "runtime/timerTrace.hpp" 74 #include "runtime/memprofiler.hpp" 75 #include "runtime/mutexLocker.hpp" 76 #include "runtime/objectMonitor.hpp" 77 #include "runtime/orderAccess.inline.hpp" 78 #include "runtime/osThread.hpp" 79 #include "runtime/safepoint.hpp" 80 #include "runtime/sharedRuntime.hpp" 81 #include "runtime/statSampler.hpp" 82 #include "runtime/stubRoutines.hpp" 83 #include "runtime/sweeper.hpp" 84 #include "runtime/task.hpp" 85 #include "runtime/thread.inline.hpp" 86 #include "runtime/threadCritical.hpp" 87 #include "runtime/vframe.hpp" 88 #include "runtime/vframeArray.hpp" 89 #include "runtime/vframe_hp.hpp" 90 #include "runtime/vmThread.hpp" 91 #include "runtime/vm_operations.hpp" 92 #include "runtime/vm_version.hpp" 93 #include "services/attachListener.hpp" 94 #include "services/management.hpp" 95 #include "services/memTracker.hpp" 96 #include "services/threadService.hpp" 97 #include "trace/traceMacros.hpp" 98 #include "trace/tracing.hpp" 99 #include "utilities/defaultStream.hpp" 100 #include "utilities/dtrace.hpp" 101 #include "utilities/events.hpp" 102 #include "utilities/macros.hpp" 103 #include "utilities/preserveException.hpp" 104 #if INCLUDE_ALL_GCS 105 #include "gc/cms/concurrentMarkSweepThread.hpp" 106 #include "gc/g1/concurrentMarkThread.inline.hpp" 107 #include "gc/parallel/pcTasks.hpp" 108 #endif // INCLUDE_ALL_GCS 109 #if INCLUDE_JVMCI 110 #include "jvmci/jvmciCompiler.hpp" 111 #include "jvmci/jvmciRuntime.hpp" 112 #endif 113 #ifdef COMPILER1 114 #include "c1/c1_Compiler.hpp" 115 #endif 116 #ifdef COMPILER2 117 #include "opto/c2compiler.hpp" 118 #include "opto/idealGraphPrinter.hpp" 119 #endif 120 #if INCLUDE_RTM_OPT 121 #include "runtime/rtmLocking.hpp" 122 #endif 123 124 // Initialization after module runtime initialization 125 void universe_post_module_init(); // must happen after call_initPhase2 126 127 #ifdef DTRACE_ENABLED 128 129 // Only bother with this argument setup if dtrace is available 130 131 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 132 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 133 134 #define DTRACE_THREAD_PROBE(probe, javathread) \ 135 { \ 136 ResourceMark rm(this); \ 137 int len = 0; \ 138 const char* name = (javathread)->get_thread_name(); \ 139 len = strlen(name); \ 140 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 141 (char *) name, len, \ 142 java_lang_Thread::thread_id((javathread)->threadObj()), \ 143 (uintptr_t) (javathread)->osthread()->thread_id(), \ 144 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 145 } 146 147 #else // ndef DTRACE_ENABLED 148 149 #define DTRACE_THREAD_PROBE(probe, javathread) 150 151 #endif // ndef DTRACE_ENABLED 152 153 #ifndef USE_LIBRARY_BASED_TLS_ONLY 154 // Current thread is maintained as a thread-local variable 155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 156 #endif 157 // Class hierarchy 158 // - Thread 159 // - VMThread 160 // - WatcherThread 161 // - ConcurrentMarkSweepThread 162 // - JavaThread 163 // - CompilerThread 164 165 // ======= Thread ======== 166 // Support for forcing alignment of thread objects for biased locking 167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 168 if (UseBiasedLocking) { 169 const int alignment = markOopDesc::biased_lock_alignment; 170 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 172 : AllocateHeap(aligned_size, flags, CURRENT_PC, 173 AllocFailStrategy::RETURN_NULL); 174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 177 "JavaThread alignment code overflowed allocated storage"); 178 if (aligned_addr != real_malloc_addr) { 179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 180 p2i(real_malloc_addr), 181 p2i(aligned_addr)); 182 } 183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 184 return aligned_addr; 185 } else { 186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 188 } 189 } 190 191 void Thread::operator delete(void* p) { 192 if (UseBiasedLocking) { 193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 194 FreeHeap(real_malloc_addr); 195 } else { 196 FreeHeap(p); 197 } 198 } 199 200 201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 202 // JavaThread 203 204 205 Thread::Thread() { 206 // stack and get_thread 207 set_stack_base(NULL); 208 set_stack_size(0); 209 set_self_raw_id(0); 210 set_lgrp_id(-1); 211 DEBUG_ONLY(clear_suspendible_thread();) 212 213 // allocated data structures 214 set_osthread(NULL); 215 set_resource_area(new (mtThread)ResourceArea()); 216 DEBUG_ONLY(_current_resource_mark = NULL;) 217 set_handle_area(new (mtThread) HandleArea(NULL)); 218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 219 set_active_handles(NULL); 220 set_free_handle_block(NULL); 221 set_last_handle_mark(NULL); 222 223 // This initial value ==> never claimed. 224 _oops_do_parity = 0; 225 226 // the handle mark links itself to last_handle_mark 227 new HandleMark(this); 228 229 // plain initialization 230 debug_only(_owned_locks = NULL;) 231 debug_only(_allow_allocation_count = 0;) 232 NOT_PRODUCT(_allow_safepoint_count = 0;) 233 NOT_PRODUCT(_skip_gcalot = false;) 234 _jvmti_env_iteration_count = 0; 235 set_allocated_bytes(0); 236 _vm_operation_started_count = 0; 237 _vm_operation_completed_count = 0; 238 _current_pending_monitor = NULL; 239 _current_pending_monitor_is_from_java = true; 240 _current_waiting_monitor = NULL; 241 _num_nested_signal = 0; 242 omFreeList = NULL; 243 omFreeCount = 0; 244 omFreeProvision = 32; 245 omInUseList = NULL; 246 omInUseCount = 0; 247 248 #ifdef ASSERT 249 _visited_for_critical_count = false; 250 #endif 251 252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 253 Monitor::_safepoint_check_sometimes); 254 _suspend_flags = 0; 255 256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 257 _hashStateX = os::random(); 258 _hashStateY = 842502087; 259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 260 _hashStateW = 273326509; 261 262 _OnTrap = 0; 263 _schedctl = NULL; 264 _Stalled = 0; 265 _TypeTag = 0x2BAD; 266 267 // Many of the following fields are effectively final - immutable 268 // Note that nascent threads can't use the Native Monitor-Mutex 269 // construct until the _MutexEvent is initialized ... 270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 271 // we might instead use a stack of ParkEvents that we could provision on-demand. 272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 273 // and ::Release() 274 _ParkEvent = ParkEvent::Allocate(this); 275 _SleepEvent = ParkEvent::Allocate(this); 276 _MutexEvent = ParkEvent::Allocate(this); 277 _MuxEvent = ParkEvent::Allocate(this); 278 279 #ifdef CHECK_UNHANDLED_OOPS 280 if (CheckUnhandledOops) { 281 _unhandled_oops = new UnhandledOops(this); 282 } 283 #endif // CHECK_UNHANDLED_OOPS 284 #ifdef ASSERT 285 if (UseBiasedLocking) { 286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 287 assert(this == _real_malloc_address || 288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 289 "bug in forced alignment of thread objects"); 290 } 291 #endif // ASSERT 292 } 293 294 void Thread::initialize_thread_current() { 295 #ifndef USE_LIBRARY_BASED_TLS_ONLY 296 assert(_thr_current == NULL, "Thread::current already initialized"); 297 _thr_current = this; 298 #endif 299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 300 ThreadLocalStorage::set_thread(this); 301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 302 } 303 304 void Thread::clear_thread_current() { 305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 306 #ifndef USE_LIBRARY_BASED_TLS_ONLY 307 _thr_current = NULL; 308 #endif 309 ThreadLocalStorage::set_thread(NULL); 310 } 311 312 void Thread::record_stack_base_and_size() { 313 set_stack_base(os::current_stack_base()); 314 set_stack_size(os::current_stack_size()); 315 // CR 7190089: on Solaris, primordial thread's stack is adjusted 316 // in initialize_thread(). Without the adjustment, stack size is 317 // incorrect if stack is set to unlimited (ulimit -s unlimited). 318 // So far, only Solaris has real implementation of initialize_thread(). 319 // 320 // set up any platform-specific state. 321 os::initialize_thread(this); 322 323 // Set stack limits after thread is initialized. 324 if (is_Java_thread()) { 325 ((JavaThread*) this)->set_stack_overflow_limit(); 326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 327 } 328 #if INCLUDE_NMT 329 // record thread's native stack, stack grows downward 330 MemTracker::record_thread_stack(stack_end(), stack_size()); 331 #endif // INCLUDE_NMT 332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 334 os::current_thread_id(), p2i(stack_base() - stack_size()), 335 p2i(stack_base()), stack_size()/1024); 336 } 337 338 339 Thread::~Thread() { 340 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 341 ObjectSynchronizer::omFlush(this); 342 343 EVENT_THREAD_DESTRUCT(this); 344 345 // stack_base can be NULL if the thread is never started or exited before 346 // record_stack_base_and_size called. Although, we would like to ensure 347 // that all started threads do call record_stack_base_and_size(), there is 348 // not proper way to enforce that. 349 #if INCLUDE_NMT 350 if (_stack_base != NULL) { 351 MemTracker::release_thread_stack(stack_end(), stack_size()); 352 #ifdef ASSERT 353 set_stack_base(NULL); 354 #endif 355 } 356 #endif // INCLUDE_NMT 357 358 // deallocate data structures 359 delete resource_area(); 360 // since the handle marks are using the handle area, we have to deallocated the root 361 // handle mark before deallocating the thread's handle area, 362 assert(last_handle_mark() != NULL, "check we have an element"); 363 delete last_handle_mark(); 364 assert(last_handle_mark() == NULL, "check we have reached the end"); 365 366 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 367 // We NULL out the fields for good hygiene. 368 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 369 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 370 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 371 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 372 373 delete handle_area(); 374 delete metadata_handles(); 375 376 // SR_handler uses this as a termination indicator - 377 // needs to happen before os::free_thread() 378 delete _SR_lock; 379 _SR_lock = NULL; 380 381 // osthread() can be NULL, if creation of thread failed. 382 if (osthread() != NULL) os::free_thread(osthread()); 383 384 // clear Thread::current if thread is deleting itself. 385 // Needed to ensure JNI correctly detects non-attached threads. 386 if (this == Thread::current()) { 387 clear_thread_current(); 388 } 389 390 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 391 } 392 393 // NOTE: dummy function for assertion purpose. 394 void Thread::run() { 395 ShouldNotReachHere(); 396 } 397 398 #ifdef ASSERT 399 // Private method to check for dangling thread pointer 400 void check_for_dangling_thread_pointer(Thread *thread) { 401 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 402 "possibility of dangling Thread pointer"); 403 } 404 #endif 405 406 ThreadPriority Thread::get_priority(const Thread* const thread) { 407 ThreadPriority priority; 408 // Can return an error! 409 (void)os::get_priority(thread, priority); 410 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 411 return priority; 412 } 413 414 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 415 debug_only(check_for_dangling_thread_pointer(thread);) 416 // Can return an error! 417 (void)os::set_priority(thread, priority); 418 } 419 420 421 void Thread::start(Thread* thread) { 422 // Start is different from resume in that its safety is guaranteed by context or 423 // being called from a Java method synchronized on the Thread object. 424 if (!DisableStartThread) { 425 if (thread->is_Java_thread()) { 426 // Initialize the thread state to RUNNABLE before starting this thread. 427 // Can not set it after the thread started because we do not know the 428 // exact thread state at that time. It could be in MONITOR_WAIT or 429 // in SLEEPING or some other state. 430 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 431 java_lang_Thread::RUNNABLE); 432 } 433 os::start_thread(thread); 434 } 435 } 436 437 // Enqueue a VM_Operation to do the job for us - sometime later 438 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 439 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 440 VMThread::execute(vm_stop); 441 } 442 443 444 // Check if an external suspend request has completed (or has been 445 // cancelled). Returns true if the thread is externally suspended and 446 // false otherwise. 447 // 448 // The bits parameter returns information about the code path through 449 // the routine. Useful for debugging: 450 // 451 // set in is_ext_suspend_completed(): 452 // 0x00000001 - routine was entered 453 // 0x00000010 - routine return false at end 454 // 0x00000100 - thread exited (return false) 455 // 0x00000200 - suspend request cancelled (return false) 456 // 0x00000400 - thread suspended (return true) 457 // 0x00001000 - thread is in a suspend equivalent state (return true) 458 // 0x00002000 - thread is native and walkable (return true) 459 // 0x00004000 - thread is native_trans and walkable (needed retry) 460 // 461 // set in wait_for_ext_suspend_completion(): 462 // 0x00010000 - routine was entered 463 // 0x00020000 - suspend request cancelled before loop (return false) 464 // 0x00040000 - thread suspended before loop (return true) 465 // 0x00080000 - suspend request cancelled in loop (return false) 466 // 0x00100000 - thread suspended in loop (return true) 467 // 0x00200000 - suspend not completed during retry loop (return false) 468 469 // Helper class for tracing suspend wait debug bits. 470 // 471 // 0x00000100 indicates that the target thread exited before it could 472 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 473 // 0x00080000 each indicate a cancelled suspend request so they don't 474 // count as wait failures either. 475 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 476 477 class TraceSuspendDebugBits : public StackObj { 478 private: 479 JavaThread * jt; 480 bool is_wait; 481 bool called_by_wait; // meaningful when !is_wait 482 uint32_t * bits; 483 484 public: 485 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 486 uint32_t *_bits) { 487 jt = _jt; 488 is_wait = _is_wait; 489 called_by_wait = _called_by_wait; 490 bits = _bits; 491 } 492 493 ~TraceSuspendDebugBits() { 494 if (!is_wait) { 495 #if 1 496 // By default, don't trace bits for is_ext_suspend_completed() calls. 497 // That trace is very chatty. 498 return; 499 #else 500 if (!called_by_wait) { 501 // If tracing for is_ext_suspend_completed() is enabled, then only 502 // trace calls to it from wait_for_ext_suspend_completion() 503 return; 504 } 505 #endif 506 } 507 508 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 509 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 510 MutexLocker ml(Threads_lock); // needed for get_thread_name() 511 ResourceMark rm; 512 513 tty->print_cr( 514 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 515 jt->get_thread_name(), *bits); 516 517 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 518 } 519 } 520 } 521 }; 522 #undef DEBUG_FALSE_BITS 523 524 525 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 526 uint32_t *bits) { 527 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 528 529 bool did_trans_retry = false; // only do thread_in_native_trans retry once 530 bool do_trans_retry; // flag to force the retry 531 532 *bits |= 0x00000001; 533 534 do { 535 do_trans_retry = false; 536 537 if (is_exiting()) { 538 // Thread is in the process of exiting. This is always checked 539 // first to reduce the risk of dereferencing a freed JavaThread. 540 *bits |= 0x00000100; 541 return false; 542 } 543 544 if (!is_external_suspend()) { 545 // Suspend request is cancelled. This is always checked before 546 // is_ext_suspended() to reduce the risk of a rogue resume 547 // confusing the thread that made the suspend request. 548 *bits |= 0x00000200; 549 return false; 550 } 551 552 if (is_ext_suspended()) { 553 // thread is suspended 554 *bits |= 0x00000400; 555 return true; 556 } 557 558 // Now that we no longer do hard suspends of threads running 559 // native code, the target thread can be changing thread state 560 // while we are in this routine: 561 // 562 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 563 // 564 // We save a copy of the thread state as observed at this moment 565 // and make our decision about suspend completeness based on the 566 // copy. This closes the race where the thread state is seen as 567 // _thread_in_native_trans in the if-thread_blocked check, but is 568 // seen as _thread_blocked in if-thread_in_native_trans check. 569 JavaThreadState save_state = thread_state(); 570 571 if (save_state == _thread_blocked && is_suspend_equivalent()) { 572 // If the thread's state is _thread_blocked and this blocking 573 // condition is known to be equivalent to a suspend, then we can 574 // consider the thread to be externally suspended. This means that 575 // the code that sets _thread_blocked has been modified to do 576 // self-suspension if the blocking condition releases. We also 577 // used to check for CONDVAR_WAIT here, but that is now covered by 578 // the _thread_blocked with self-suspension check. 579 // 580 // Return true since we wouldn't be here unless there was still an 581 // external suspend request. 582 *bits |= 0x00001000; 583 return true; 584 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 585 // Threads running native code will self-suspend on native==>VM/Java 586 // transitions. If its stack is walkable (should always be the case 587 // unless this function is called before the actual java_suspend() 588 // call), then the wait is done. 589 *bits |= 0x00002000; 590 return true; 591 } else if (!called_by_wait && !did_trans_retry && 592 save_state == _thread_in_native_trans && 593 frame_anchor()->walkable()) { 594 // The thread is transitioning from thread_in_native to another 595 // thread state. check_safepoint_and_suspend_for_native_trans() 596 // will force the thread to self-suspend. If it hasn't gotten 597 // there yet we may have caught the thread in-between the native 598 // code check above and the self-suspend. Lucky us. If we were 599 // called by wait_for_ext_suspend_completion(), then it 600 // will be doing the retries so we don't have to. 601 // 602 // Since we use the saved thread state in the if-statement above, 603 // there is a chance that the thread has already transitioned to 604 // _thread_blocked by the time we get here. In that case, we will 605 // make a single unnecessary pass through the logic below. This 606 // doesn't hurt anything since we still do the trans retry. 607 608 *bits |= 0x00004000; 609 610 // Once the thread leaves thread_in_native_trans for another 611 // thread state, we break out of this retry loop. We shouldn't 612 // need this flag to prevent us from getting back here, but 613 // sometimes paranoia is good. 614 did_trans_retry = true; 615 616 // We wait for the thread to transition to a more usable state. 617 for (int i = 1; i <= SuspendRetryCount; i++) { 618 // We used to do an "os::yield_all(i)" call here with the intention 619 // that yielding would increase on each retry. However, the parameter 620 // is ignored on Linux which means the yield didn't scale up. Waiting 621 // on the SR_lock below provides a much more predictable scale up for 622 // the delay. It also provides a simple/direct point to check for any 623 // safepoint requests from the VMThread 624 625 // temporarily drops SR_lock while doing wait with safepoint check 626 // (if we're a JavaThread - the WatcherThread can also call this) 627 // and increase delay with each retry 628 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 629 630 // check the actual thread state instead of what we saved above 631 if (thread_state() != _thread_in_native_trans) { 632 // the thread has transitioned to another thread state so 633 // try all the checks (except this one) one more time. 634 do_trans_retry = true; 635 break; 636 } 637 } // end retry loop 638 639 640 } 641 } while (do_trans_retry); 642 643 *bits |= 0x00000010; 644 return false; 645 } 646 647 // Wait for an external suspend request to complete (or be cancelled). 648 // Returns true if the thread is externally suspended and false otherwise. 649 // 650 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 651 uint32_t *bits) { 652 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 653 false /* !called_by_wait */, bits); 654 655 // local flag copies to minimize SR_lock hold time 656 bool is_suspended; 657 bool pending; 658 uint32_t reset_bits; 659 660 // set a marker so is_ext_suspend_completed() knows we are the caller 661 *bits |= 0x00010000; 662 663 // We use reset_bits to reinitialize the bits value at the top of 664 // each retry loop. This allows the caller to make use of any 665 // unused bits for their own marking purposes. 666 reset_bits = *bits; 667 668 { 669 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 670 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 671 delay, bits); 672 pending = is_external_suspend(); 673 } 674 // must release SR_lock to allow suspension to complete 675 676 if (!pending) { 677 // A cancelled suspend request is the only false return from 678 // is_ext_suspend_completed() that keeps us from entering the 679 // retry loop. 680 *bits |= 0x00020000; 681 return false; 682 } 683 684 if (is_suspended) { 685 *bits |= 0x00040000; 686 return true; 687 } 688 689 for (int i = 1; i <= retries; i++) { 690 *bits = reset_bits; // reinit to only track last retry 691 692 // We used to do an "os::yield_all(i)" call here with the intention 693 // that yielding would increase on each retry. However, the parameter 694 // is ignored on Linux which means the yield didn't scale up. Waiting 695 // on the SR_lock below provides a much more predictable scale up for 696 // the delay. It also provides a simple/direct point to check for any 697 // safepoint requests from the VMThread 698 699 { 700 MutexLocker ml(SR_lock()); 701 // wait with safepoint check (if we're a JavaThread - the WatcherThread 702 // can also call this) and increase delay with each retry 703 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 704 705 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 706 delay, bits); 707 708 // It is possible for the external suspend request to be cancelled 709 // (by a resume) before the actual suspend operation is completed. 710 // Refresh our local copy to see if we still need to wait. 711 pending = is_external_suspend(); 712 } 713 714 if (!pending) { 715 // A cancelled suspend request is the only false return from 716 // is_ext_suspend_completed() that keeps us from staying in the 717 // retry loop. 718 *bits |= 0x00080000; 719 return false; 720 } 721 722 if (is_suspended) { 723 *bits |= 0x00100000; 724 return true; 725 } 726 } // end retry loop 727 728 // thread did not suspend after all our retries 729 *bits |= 0x00200000; 730 return false; 731 } 732 733 #ifndef PRODUCT 734 void JavaThread::record_jump(address target, address instr, const char* file, 735 int line) { 736 737 // This should not need to be atomic as the only way for simultaneous 738 // updates is via interrupts. Even then this should be rare or non-existent 739 // and we don't care that much anyway. 740 741 int index = _jmp_ring_index; 742 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 743 _jmp_ring[index]._target = (intptr_t) target; 744 _jmp_ring[index]._instruction = (intptr_t) instr; 745 _jmp_ring[index]._file = file; 746 _jmp_ring[index]._line = line; 747 } 748 #endif // PRODUCT 749 750 // Called by flat profiler 751 // Callers have already called wait_for_ext_suspend_completion 752 // The assertion for that is currently too complex to put here: 753 bool JavaThread::profile_last_Java_frame(frame* _fr) { 754 bool gotframe = false; 755 // self suspension saves needed state. 756 if (has_last_Java_frame() && _anchor.walkable()) { 757 *_fr = pd_last_frame(); 758 gotframe = true; 759 } 760 return gotframe; 761 } 762 763 void Thread::interrupt(Thread* thread) { 764 debug_only(check_for_dangling_thread_pointer(thread);) 765 os::interrupt(thread); 766 } 767 768 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 769 debug_only(check_for_dangling_thread_pointer(thread);) 770 // Note: If clear_interrupted==false, this simply fetches and 771 // returns the value of the field osthread()->interrupted(). 772 return os::is_interrupted(thread, clear_interrupted); 773 } 774 775 776 // GC Support 777 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 778 jint thread_parity = _oops_do_parity; 779 if (thread_parity != strong_roots_parity) { 780 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 781 if (res == thread_parity) { 782 return true; 783 } else { 784 guarantee(res == strong_roots_parity, "Or else what?"); 785 return false; 786 } 787 } 788 return false; 789 } 790 791 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 792 active_handles()->oops_do(f); 793 // Do oop for ThreadShadow 794 f->do_oop((oop*)&_pending_exception); 795 handle_area()->oops_do(f); 796 } 797 798 void Thread::metadata_handles_do(void f(Metadata*)) { 799 // Only walk the Handles in Thread. 800 if (metadata_handles() != NULL) { 801 for (int i = 0; i< metadata_handles()->length(); i++) { 802 f(metadata_handles()->at(i)); 803 } 804 } 805 } 806 807 void Thread::print_on(outputStream* st) const { 808 // get_priority assumes osthread initialized 809 if (osthread() != NULL) { 810 int os_prio; 811 if (os::get_native_priority(this, &os_prio) == OS_OK) { 812 st->print("os_prio=%d ", os_prio); 813 } 814 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 815 ext().print_on(st); 816 osthread()->print_on(st); 817 } 818 debug_only(if (WizardMode) print_owned_locks_on(st);) 819 } 820 821 // Thread::print_on_error() is called by fatal error handler. Don't use 822 // any lock or allocate memory. 823 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 824 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 825 826 if (is_VM_thread()) { st->print("VMThread"); } 827 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 828 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 829 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 830 else { st->print("Thread"); } 831 832 if (is_Named_thread()) { 833 st->print(" \"%s\"", name()); 834 } 835 836 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 837 p2i(stack_end()), p2i(stack_base())); 838 839 if (osthread()) { 840 st->print(" [id=%d]", osthread()->thread_id()); 841 } 842 } 843 844 #ifdef ASSERT 845 void Thread::print_owned_locks_on(outputStream* st) const { 846 Monitor *cur = _owned_locks; 847 if (cur == NULL) { 848 st->print(" (no locks) "); 849 } else { 850 st->print_cr(" Locks owned:"); 851 while (cur) { 852 cur->print_on(st); 853 cur = cur->next(); 854 } 855 } 856 } 857 858 static int ref_use_count = 0; 859 860 bool Thread::owns_locks_but_compiled_lock() const { 861 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 862 if (cur != Compile_lock) return true; 863 } 864 return false; 865 } 866 867 868 #endif 869 870 #ifndef PRODUCT 871 872 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 873 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 874 // no threads which allow_vm_block's are held 875 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 876 // Check if current thread is allowed to block at a safepoint 877 if (!(_allow_safepoint_count == 0)) { 878 fatal("Possible safepoint reached by thread that does not allow it"); 879 } 880 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 881 fatal("LEAF method calling lock?"); 882 } 883 884 #ifdef ASSERT 885 if (potential_vm_operation && is_Java_thread() 886 && !Universe::is_bootstrapping()) { 887 // Make sure we do not hold any locks that the VM thread also uses. 888 // This could potentially lead to deadlocks 889 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 890 // Threads_lock is special, since the safepoint synchronization will not start before this is 891 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 892 // since it is used to transfer control between JavaThreads and the VMThread 893 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 894 if ((cur->allow_vm_block() && 895 cur != Threads_lock && 896 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 897 cur != VMOperationRequest_lock && 898 cur != VMOperationQueue_lock) || 899 cur->rank() == Mutex::special) { 900 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 901 } 902 } 903 } 904 905 if (GCALotAtAllSafepoints) { 906 // We could enter a safepoint here and thus have a gc 907 InterfaceSupport::check_gc_alot(); 908 } 909 #endif 910 } 911 #endif 912 913 bool Thread::is_in_stack(address adr) const { 914 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 915 address end = os::current_stack_pointer(); 916 // Allow non Java threads to call this without stack_base 917 if (_stack_base == NULL) return true; 918 if (stack_base() >= adr && adr >= end) return true; 919 920 return false; 921 } 922 923 bool Thread::is_in_usable_stack(address adr) const { 924 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 925 size_t usable_stack_size = _stack_size - stack_guard_size; 926 927 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 928 } 929 930 931 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 932 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 933 // used for compilation in the future. If that change is made, the need for these methods 934 // should be revisited, and they should be removed if possible. 935 936 bool Thread::is_lock_owned(address adr) const { 937 return on_local_stack(adr); 938 } 939 940 bool Thread::set_as_starting_thread() { 941 // NOTE: this must be called inside the main thread. 942 return os::create_main_thread((JavaThread*)this); 943 } 944 945 static void initialize_class(Symbol* class_name, TRAPS) { 946 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 947 InstanceKlass::cast(klass)->initialize(CHECK); 948 } 949 950 951 // Creates the initial ThreadGroup 952 static Handle create_initial_thread_group(TRAPS) { 953 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 954 instanceKlassHandle klass (THREAD, k); 955 956 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 957 { 958 JavaValue result(T_VOID); 959 JavaCalls::call_special(&result, 960 system_instance, 961 klass, 962 vmSymbols::object_initializer_name(), 963 vmSymbols::void_method_signature(), 964 CHECK_NH); 965 } 966 Universe::set_system_thread_group(system_instance()); 967 968 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 969 { 970 JavaValue result(T_VOID); 971 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 972 JavaCalls::call_special(&result, 973 main_instance, 974 klass, 975 vmSymbols::object_initializer_name(), 976 vmSymbols::threadgroup_string_void_signature(), 977 system_instance, 978 string, 979 CHECK_NH); 980 } 981 return main_instance; 982 } 983 984 // Creates the initial Thread 985 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 986 TRAPS) { 987 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 988 instanceKlassHandle klass (THREAD, k); 989 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 990 991 java_lang_Thread::set_thread(thread_oop(), thread); 992 java_lang_Thread::set_priority(thread_oop(), NormPriority); 993 thread->set_threadObj(thread_oop()); 994 995 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 996 997 JavaValue result(T_VOID); 998 JavaCalls::call_special(&result, thread_oop, 999 klass, 1000 vmSymbols::object_initializer_name(), 1001 vmSymbols::threadgroup_string_void_signature(), 1002 thread_group, 1003 string, 1004 CHECK_NULL); 1005 return thread_oop(); 1006 } 1007 1008 char java_runtime_name[128] = ""; 1009 char java_runtime_version[128] = ""; 1010 1011 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1012 static const char* get_java_runtime_name(TRAPS) { 1013 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1014 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1015 fieldDescriptor fd; 1016 bool found = k != NULL && 1017 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1018 vmSymbols::string_signature(), &fd); 1019 if (found) { 1020 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1021 if (name_oop == NULL) { 1022 return NULL; 1023 } 1024 const char* name = java_lang_String::as_utf8_string(name_oop, 1025 java_runtime_name, 1026 sizeof(java_runtime_name)); 1027 return name; 1028 } else { 1029 return NULL; 1030 } 1031 } 1032 1033 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1034 static const char* get_java_runtime_version(TRAPS) { 1035 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1036 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1037 fieldDescriptor fd; 1038 bool found = k != NULL && 1039 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1040 vmSymbols::string_signature(), &fd); 1041 if (found) { 1042 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1043 if (name_oop == NULL) { 1044 return NULL; 1045 } 1046 const char* name = java_lang_String::as_utf8_string(name_oop, 1047 java_runtime_version, 1048 sizeof(java_runtime_version)); 1049 return name; 1050 } else { 1051 return NULL; 1052 } 1053 } 1054 1055 // General purpose hook into Java code, run once when the VM is initialized. 1056 // The Java library method itself may be changed independently from the VM. 1057 static void call_postVMInitHook(TRAPS) { 1058 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1059 instanceKlassHandle klass (THREAD, k); 1060 if (klass.not_null()) { 1061 JavaValue result(T_VOID); 1062 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1063 vmSymbols::void_method_signature(), 1064 CHECK); 1065 } 1066 } 1067 1068 static void reset_vm_info_property(TRAPS) { 1069 // the vm info string 1070 ResourceMark rm(THREAD); 1071 const char *vm_info = VM_Version::vm_info_string(); 1072 1073 // java.lang.System class 1074 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1075 instanceKlassHandle klass (THREAD, k); 1076 1077 // setProperty arguments 1078 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1079 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1080 1081 // return value 1082 JavaValue r(T_OBJECT); 1083 1084 // public static String setProperty(String key, String value); 1085 JavaCalls::call_static(&r, 1086 klass, 1087 vmSymbols::setProperty_name(), 1088 vmSymbols::string_string_string_signature(), 1089 key_str, 1090 value_str, 1091 CHECK); 1092 } 1093 1094 1095 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1096 bool daemon, TRAPS) { 1097 assert(thread_group.not_null(), "thread group should be specified"); 1098 assert(threadObj() == NULL, "should only create Java thread object once"); 1099 1100 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1101 instanceKlassHandle klass (THREAD, k); 1102 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1103 1104 java_lang_Thread::set_thread(thread_oop(), this); 1105 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1106 set_threadObj(thread_oop()); 1107 1108 JavaValue result(T_VOID); 1109 if (thread_name != NULL) { 1110 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1111 // Thread gets assigned specified name and null target 1112 JavaCalls::call_special(&result, 1113 thread_oop, 1114 klass, 1115 vmSymbols::object_initializer_name(), 1116 vmSymbols::threadgroup_string_void_signature(), 1117 thread_group, // Argument 1 1118 name, // Argument 2 1119 THREAD); 1120 } else { 1121 // Thread gets assigned name "Thread-nnn" and null target 1122 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1123 JavaCalls::call_special(&result, 1124 thread_oop, 1125 klass, 1126 vmSymbols::object_initializer_name(), 1127 vmSymbols::threadgroup_runnable_void_signature(), 1128 thread_group, // Argument 1 1129 Handle(), // Argument 2 1130 THREAD); 1131 } 1132 1133 1134 if (daemon) { 1135 java_lang_Thread::set_daemon(thread_oop()); 1136 } 1137 1138 if (HAS_PENDING_EXCEPTION) { 1139 return; 1140 } 1141 1142 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass()); 1143 Handle threadObj(THREAD, this->threadObj()); 1144 1145 JavaCalls::call_special(&result, 1146 thread_group, 1147 group, 1148 vmSymbols::add_method_name(), 1149 vmSymbols::thread_void_signature(), 1150 threadObj, // Arg 1 1151 THREAD); 1152 } 1153 1154 // NamedThread -- non-JavaThread subclasses with multiple 1155 // uniquely named instances should derive from this. 1156 NamedThread::NamedThread() : Thread() { 1157 _name = NULL; 1158 _processed_thread = NULL; 1159 _gc_id = GCId::undefined(); 1160 } 1161 1162 NamedThread::~NamedThread() { 1163 if (_name != NULL) { 1164 FREE_C_HEAP_ARRAY(char, _name); 1165 _name = NULL; 1166 } 1167 } 1168 1169 void NamedThread::set_name(const char* format, ...) { 1170 guarantee(_name == NULL, "Only get to set name once."); 1171 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1172 guarantee(_name != NULL, "alloc failure"); 1173 va_list ap; 1174 va_start(ap, format); 1175 jio_vsnprintf(_name, max_name_len, format, ap); 1176 va_end(ap); 1177 } 1178 1179 void NamedThread::initialize_named_thread() { 1180 set_native_thread_name(name()); 1181 } 1182 1183 void NamedThread::print_on(outputStream* st) const { 1184 st->print("\"%s\" ", name()); 1185 Thread::print_on(st); 1186 st->cr(); 1187 } 1188 1189 1190 // ======= WatcherThread ======== 1191 1192 // The watcher thread exists to simulate timer interrupts. It should 1193 // be replaced by an abstraction over whatever native support for 1194 // timer interrupts exists on the platform. 1195 1196 WatcherThread* WatcherThread::_watcher_thread = NULL; 1197 bool WatcherThread::_startable = false; 1198 volatile bool WatcherThread::_should_terminate = false; 1199 1200 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1201 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1202 if (os::create_thread(this, os::watcher_thread)) { 1203 _watcher_thread = this; 1204 1205 // Set the watcher thread to the highest OS priority which should not be 1206 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1207 // is created. The only normal thread using this priority is the reference 1208 // handler thread, which runs for very short intervals only. 1209 // If the VMThread's priority is not lower than the WatcherThread profiling 1210 // will be inaccurate. 1211 os::set_priority(this, MaxPriority); 1212 if (!DisableStartThread) { 1213 os::start_thread(this); 1214 } 1215 } 1216 } 1217 1218 int WatcherThread::sleep() const { 1219 // The WatcherThread does not participate in the safepoint protocol 1220 // for the PeriodicTask_lock because it is not a JavaThread. 1221 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1222 1223 if (_should_terminate) { 1224 // check for termination before we do any housekeeping or wait 1225 return 0; // we did not sleep. 1226 } 1227 1228 // remaining will be zero if there are no tasks, 1229 // causing the WatcherThread to sleep until a task is 1230 // enrolled 1231 int remaining = PeriodicTask::time_to_wait(); 1232 int time_slept = 0; 1233 1234 // we expect this to timeout - we only ever get unparked when 1235 // we should terminate or when a new task has been enrolled 1236 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1237 1238 jlong time_before_loop = os::javaTimeNanos(); 1239 1240 while (true) { 1241 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1242 remaining); 1243 jlong now = os::javaTimeNanos(); 1244 1245 if (remaining == 0) { 1246 // if we didn't have any tasks we could have waited for a long time 1247 // consider the time_slept zero and reset time_before_loop 1248 time_slept = 0; 1249 time_before_loop = now; 1250 } else { 1251 // need to recalculate since we might have new tasks in _tasks 1252 time_slept = (int) ((now - time_before_loop) / 1000000); 1253 } 1254 1255 // Change to task list or spurious wakeup of some kind 1256 if (timedout || _should_terminate) { 1257 break; 1258 } 1259 1260 remaining = PeriodicTask::time_to_wait(); 1261 if (remaining == 0) { 1262 // Last task was just disenrolled so loop around and wait until 1263 // another task gets enrolled 1264 continue; 1265 } 1266 1267 remaining -= time_slept; 1268 if (remaining <= 0) { 1269 break; 1270 } 1271 } 1272 1273 return time_slept; 1274 } 1275 1276 void WatcherThread::run() { 1277 assert(this == watcher_thread(), "just checking"); 1278 1279 this->record_stack_base_and_size(); 1280 this->set_native_thread_name(this->name()); 1281 this->set_active_handles(JNIHandleBlock::allocate_block()); 1282 while (true) { 1283 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1284 assert(watcher_thread() == this, "thread consistency check"); 1285 1286 // Calculate how long it'll be until the next PeriodicTask work 1287 // should be done, and sleep that amount of time. 1288 int time_waited = sleep(); 1289 1290 if (is_error_reported()) { 1291 // A fatal error has happened, the error handler(VMError::report_and_die) 1292 // should abort JVM after creating an error log file. However in some 1293 // rare cases, the error handler itself might deadlock. Here we try to 1294 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1295 // 1296 // This code is in WatcherThread because WatcherThread wakes up 1297 // periodically so the fatal error handler doesn't need to do anything; 1298 // also because the WatcherThread is less likely to crash than other 1299 // threads. 1300 1301 for (;;) { 1302 if (!ShowMessageBoxOnError 1303 && (OnError == NULL || OnError[0] == '\0') 1304 && Arguments::abort_hook() == NULL) { 1305 os::sleep(this, (jlong)ErrorLogTimeout * 1000, false); // in seconds 1306 fdStream err(defaultStream::output_fd()); 1307 err.print_raw_cr("# [ timer expired, abort... ]"); 1308 // skip atexit/vm_exit/vm_abort hooks 1309 os::die(); 1310 } 1311 1312 // Wake up 5 seconds later, the fatal handler may reset OnError or 1313 // ShowMessageBoxOnError when it is ready to abort. 1314 os::sleep(this, 5 * 1000, false); 1315 } 1316 } 1317 1318 if (_should_terminate) { 1319 // check for termination before posting the next tick 1320 break; 1321 } 1322 1323 PeriodicTask::real_time_tick(time_waited); 1324 } 1325 1326 // Signal that it is terminated 1327 { 1328 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1329 _watcher_thread = NULL; 1330 Terminator_lock->notify(); 1331 } 1332 } 1333 1334 void WatcherThread::start() { 1335 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1336 1337 if (watcher_thread() == NULL && _startable) { 1338 _should_terminate = false; 1339 // Create the single instance of WatcherThread 1340 new WatcherThread(); 1341 } 1342 } 1343 1344 void WatcherThread::make_startable() { 1345 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1346 _startable = true; 1347 } 1348 1349 void WatcherThread::stop() { 1350 { 1351 // Follow normal safepoint aware lock enter protocol since the 1352 // WatcherThread is stopped by another JavaThread. 1353 MutexLocker ml(PeriodicTask_lock); 1354 _should_terminate = true; 1355 1356 WatcherThread* watcher = watcher_thread(); 1357 if (watcher != NULL) { 1358 // unpark the WatcherThread so it can see that it should terminate 1359 watcher->unpark(); 1360 } 1361 } 1362 1363 MutexLocker mu(Terminator_lock); 1364 1365 while (watcher_thread() != NULL) { 1366 // This wait should make safepoint checks, wait without a timeout, 1367 // and wait as a suspend-equivalent condition. 1368 // 1369 // Note: If the FlatProfiler is running, then this thread is waiting 1370 // for the WatcherThread to terminate and the WatcherThread, via the 1371 // FlatProfiler task, is waiting for the external suspend request on 1372 // this thread to complete. wait_for_ext_suspend_completion() will 1373 // eventually timeout, but that takes time. Making this wait a 1374 // suspend-equivalent condition solves that timeout problem. 1375 // 1376 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1377 Mutex::_as_suspend_equivalent_flag); 1378 } 1379 } 1380 1381 void WatcherThread::unpark() { 1382 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1383 PeriodicTask_lock->notify(); 1384 } 1385 1386 void WatcherThread::print_on(outputStream* st) const { 1387 st->print("\"%s\" ", name()); 1388 Thread::print_on(st); 1389 st->cr(); 1390 } 1391 1392 // ======= JavaThread ======== 1393 1394 #if INCLUDE_JVMCI 1395 1396 jlong* JavaThread::_jvmci_old_thread_counters; 1397 1398 bool jvmci_counters_include(JavaThread* thread) { 1399 oop threadObj = thread->threadObj(); 1400 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1401 } 1402 1403 void JavaThread::collect_counters(typeArrayOop array) { 1404 if (JVMCICounterSize > 0) { 1405 MutexLocker tl(Threads_lock); 1406 for (int i = 0; i < array->length(); i++) { 1407 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1408 } 1409 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1410 if (jvmci_counters_include(tp)) { 1411 for (int i = 0; i < array->length(); i++) { 1412 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1413 } 1414 } 1415 } 1416 } 1417 } 1418 1419 #endif // INCLUDE_JVMCI 1420 1421 // A JavaThread is a normal Java thread 1422 1423 void JavaThread::initialize() { 1424 // Initialize fields 1425 1426 set_saved_exception_pc(NULL); 1427 set_threadObj(NULL); 1428 _anchor.clear(); 1429 set_entry_point(NULL); 1430 set_jni_functions(jni_functions()); 1431 set_callee_target(NULL); 1432 set_vm_result(NULL); 1433 set_vm_result_2(NULL); 1434 set_vframe_array_head(NULL); 1435 set_vframe_array_last(NULL); 1436 set_deferred_locals(NULL); 1437 set_deopt_mark(NULL); 1438 set_deopt_compiled_method(NULL); 1439 clear_must_deopt_id(); 1440 set_monitor_chunks(NULL); 1441 set_next(NULL); 1442 set_thread_state(_thread_new); 1443 _terminated = _not_terminated; 1444 _privileged_stack_top = NULL; 1445 _array_for_gc = NULL; 1446 _suspend_equivalent = false; 1447 _in_deopt_handler = 0; 1448 _doing_unsafe_access = false; 1449 _stack_guard_state = stack_guard_unused; 1450 #if INCLUDE_JVMCI 1451 _pending_monitorenter = false; 1452 _pending_deoptimization = -1; 1453 _pending_failed_speculation = NULL; 1454 _pending_transfer_to_interpreter = false; 1455 _adjusting_comp_level = false; 1456 _jvmci._alternate_call_target = NULL; 1457 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1458 if (JVMCICounterSize > 0) { 1459 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1460 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1461 } else { 1462 _jvmci_counters = NULL; 1463 } 1464 #endif // INCLUDE_JVMCI 1465 _reserved_stack_activation = NULL; // stack base not known yet 1466 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1467 _exception_pc = 0; 1468 _exception_handler_pc = 0; 1469 _is_method_handle_return = 0; 1470 _jvmti_thread_state= NULL; 1471 _should_post_on_exceptions_flag = JNI_FALSE; 1472 _jvmti_get_loaded_classes_closure = NULL; 1473 _interp_only_mode = 0; 1474 _special_runtime_exit_condition = _no_async_condition; 1475 _pending_async_exception = NULL; 1476 _thread_stat = NULL; 1477 _thread_stat = new ThreadStatistics(); 1478 _blocked_on_compilation = false; 1479 _jni_active_critical = 0; 1480 _pending_jni_exception_check_fn = NULL; 1481 _do_not_unlock_if_synchronized = false; 1482 _cached_monitor_info = NULL; 1483 _parker = Parker::Allocate(this); 1484 1485 #ifndef PRODUCT 1486 _jmp_ring_index = 0; 1487 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1488 record_jump(NULL, NULL, NULL, 0); 1489 } 1490 #endif // PRODUCT 1491 1492 set_thread_profiler(NULL); 1493 if (FlatProfiler::is_active()) { 1494 // This is where we would decide to either give each thread it's own profiler 1495 // or use one global one from FlatProfiler, 1496 // or up to some count of the number of profiled threads, etc. 1497 ThreadProfiler* pp = new ThreadProfiler(); 1498 pp->engage(); 1499 set_thread_profiler(pp); 1500 } 1501 1502 // Setup safepoint state info for this thread 1503 ThreadSafepointState::create(this); 1504 1505 debug_only(_java_call_counter = 0); 1506 1507 // JVMTI PopFrame support 1508 _popframe_condition = popframe_inactive; 1509 _popframe_preserved_args = NULL; 1510 _popframe_preserved_args_size = 0; 1511 _frames_to_pop_failed_realloc = 0; 1512 1513 pd_initialize(); 1514 } 1515 1516 #if INCLUDE_ALL_GCS 1517 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1518 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1519 #endif // INCLUDE_ALL_GCS 1520 1521 JavaThread::JavaThread(bool is_attaching_via_jni) : 1522 Thread() 1523 #if INCLUDE_ALL_GCS 1524 , _satb_mark_queue(&_satb_mark_queue_set), 1525 _dirty_card_queue(&_dirty_card_queue_set) 1526 #endif // INCLUDE_ALL_GCS 1527 { 1528 initialize(); 1529 if (is_attaching_via_jni) { 1530 _jni_attach_state = _attaching_via_jni; 1531 } else { 1532 _jni_attach_state = _not_attaching_via_jni; 1533 } 1534 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1535 } 1536 1537 bool JavaThread::reguard_stack(address cur_sp) { 1538 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1539 && _stack_guard_state != stack_guard_reserved_disabled) { 1540 return true; // Stack already guarded or guard pages not needed. 1541 } 1542 1543 if (register_stack_overflow()) { 1544 // For those architectures which have separate register and 1545 // memory stacks, we must check the register stack to see if 1546 // it has overflowed. 1547 return false; 1548 } 1549 1550 // Java code never executes within the yellow zone: the latter is only 1551 // there to provoke an exception during stack banging. If java code 1552 // is executing there, either StackShadowPages should be larger, or 1553 // some exception code in c1, c2 or the interpreter isn't unwinding 1554 // when it should. 1555 guarantee(cur_sp > stack_reserved_zone_base(), 1556 "not enough space to reguard - increase StackShadowPages"); 1557 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1558 enable_stack_yellow_reserved_zone(); 1559 if (reserved_stack_activation() != stack_base()) { 1560 set_reserved_stack_activation(stack_base()); 1561 } 1562 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1563 set_reserved_stack_activation(stack_base()); 1564 enable_stack_reserved_zone(); 1565 } 1566 return true; 1567 } 1568 1569 bool JavaThread::reguard_stack(void) { 1570 return reguard_stack(os::current_stack_pointer()); 1571 } 1572 1573 1574 void JavaThread::block_if_vm_exited() { 1575 if (_terminated == _vm_exited) { 1576 // _vm_exited is set at safepoint, and Threads_lock is never released 1577 // we will block here forever 1578 Threads_lock->lock_without_safepoint_check(); 1579 ShouldNotReachHere(); 1580 } 1581 } 1582 1583 1584 // Remove this ifdef when C1 is ported to the compiler interface. 1585 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1586 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1587 1588 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1589 Thread() 1590 #if INCLUDE_ALL_GCS 1591 , _satb_mark_queue(&_satb_mark_queue_set), 1592 _dirty_card_queue(&_dirty_card_queue_set) 1593 #endif // INCLUDE_ALL_GCS 1594 { 1595 initialize(); 1596 _jni_attach_state = _not_attaching_via_jni; 1597 set_entry_point(entry_point); 1598 // Create the native thread itself. 1599 // %note runtime_23 1600 os::ThreadType thr_type = os::java_thread; 1601 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1602 os::java_thread; 1603 os::create_thread(this, thr_type, stack_sz); 1604 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1605 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1606 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1607 // the exception consists of creating the exception object & initializing it, initialization 1608 // will leave the VM via a JavaCall and then all locks must be unlocked). 1609 // 1610 // The thread is still suspended when we reach here. Thread must be explicit started 1611 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1612 // by calling Threads:add. The reason why this is not done here, is because the thread 1613 // object must be fully initialized (take a look at JVM_Start) 1614 } 1615 1616 JavaThread::~JavaThread() { 1617 1618 // JSR166 -- return the parker to the free list 1619 Parker::Release(_parker); 1620 _parker = NULL; 1621 1622 // Free any remaining previous UnrollBlock 1623 vframeArray* old_array = vframe_array_last(); 1624 1625 if (old_array != NULL) { 1626 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1627 old_array->set_unroll_block(NULL); 1628 delete old_info; 1629 delete old_array; 1630 } 1631 1632 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1633 if (deferred != NULL) { 1634 // This can only happen if thread is destroyed before deoptimization occurs. 1635 assert(deferred->length() != 0, "empty array!"); 1636 do { 1637 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1638 deferred->remove_at(0); 1639 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1640 delete dlv; 1641 } while (deferred->length() != 0); 1642 delete deferred; 1643 } 1644 1645 // All Java related clean up happens in exit 1646 ThreadSafepointState::destroy(this); 1647 if (_thread_profiler != NULL) delete _thread_profiler; 1648 if (_thread_stat != NULL) delete _thread_stat; 1649 1650 #if INCLUDE_JVMCI 1651 if (JVMCICounterSize > 0) { 1652 if (jvmci_counters_include(this)) { 1653 for (int i = 0; i < JVMCICounterSize; i++) { 1654 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1655 } 1656 } 1657 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1658 } 1659 #endif // INCLUDE_JVMCI 1660 } 1661 1662 1663 // The first routine called by a new Java thread 1664 void JavaThread::run() { 1665 // initialize thread-local alloc buffer related fields 1666 this->initialize_tlab(); 1667 1668 // used to test validity of stack trace backs 1669 this->record_base_of_stack_pointer(); 1670 1671 // Record real stack base and size. 1672 this->record_stack_base_and_size(); 1673 1674 this->create_stack_guard_pages(); 1675 1676 this->cache_global_variables(); 1677 1678 // Thread is now sufficient initialized to be handled by the safepoint code as being 1679 // in the VM. Change thread state from _thread_new to _thread_in_vm 1680 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1681 1682 assert(JavaThread::current() == this, "sanity check"); 1683 assert(!Thread::current()->owns_locks(), "sanity check"); 1684 1685 DTRACE_THREAD_PROBE(start, this); 1686 1687 // This operation might block. We call that after all safepoint checks for a new thread has 1688 // been completed. 1689 this->set_active_handles(JNIHandleBlock::allocate_block()); 1690 1691 if (JvmtiExport::should_post_thread_life()) { 1692 JvmtiExport::post_thread_start(this); 1693 } 1694 1695 EventThreadStart event; 1696 if (event.should_commit()) { 1697 event.set_thread(THREAD_TRACE_ID(this)); 1698 event.commit(); 1699 } 1700 1701 // We call another function to do the rest so we are sure that the stack addresses used 1702 // from there will be lower than the stack base just computed 1703 thread_main_inner(); 1704 1705 // Note, thread is no longer valid at this point! 1706 } 1707 1708 1709 void JavaThread::thread_main_inner() { 1710 assert(JavaThread::current() == this, "sanity check"); 1711 assert(this->threadObj() != NULL, "just checking"); 1712 1713 // Execute thread entry point unless this thread has a pending exception 1714 // or has been stopped before starting. 1715 // Note: Due to JVM_StopThread we can have pending exceptions already! 1716 if (!this->has_pending_exception() && 1717 !java_lang_Thread::is_stillborn(this->threadObj())) { 1718 { 1719 ResourceMark rm(this); 1720 this->set_native_thread_name(this->get_thread_name()); 1721 } 1722 HandleMark hm(this); 1723 this->entry_point()(this, this); 1724 } 1725 1726 DTRACE_THREAD_PROBE(stop, this); 1727 1728 this->exit(false); 1729 delete this; 1730 } 1731 1732 1733 static void ensure_join(JavaThread* thread) { 1734 // We do not need to grap the Threads_lock, since we are operating on ourself. 1735 Handle threadObj(thread, thread->threadObj()); 1736 assert(threadObj.not_null(), "java thread object must exist"); 1737 ObjectLocker lock(threadObj, thread); 1738 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1739 thread->clear_pending_exception(); 1740 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1741 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1742 // Clear the native thread instance - this makes isAlive return false and allows the join() 1743 // to complete once we've done the notify_all below 1744 java_lang_Thread::set_thread(threadObj(), NULL); 1745 lock.notify_all(thread); 1746 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1747 thread->clear_pending_exception(); 1748 } 1749 1750 1751 // For any new cleanup additions, please check to see if they need to be applied to 1752 // cleanup_failed_attach_current_thread as well. 1753 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1754 assert(this == JavaThread::current(), "thread consistency check"); 1755 1756 HandleMark hm(this); 1757 Handle uncaught_exception(this, this->pending_exception()); 1758 this->clear_pending_exception(); 1759 Handle threadObj(this, this->threadObj()); 1760 assert(threadObj.not_null(), "Java thread object should be created"); 1761 1762 if (get_thread_profiler() != NULL) { 1763 get_thread_profiler()->disengage(); 1764 ResourceMark rm; 1765 get_thread_profiler()->print(get_thread_name()); 1766 } 1767 1768 1769 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1770 { 1771 EXCEPTION_MARK; 1772 1773 CLEAR_PENDING_EXCEPTION; 1774 } 1775 if (!destroy_vm) { 1776 if (uncaught_exception.not_null()) { 1777 EXCEPTION_MARK; 1778 // Call method Thread.dispatchUncaughtException(). 1779 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1780 JavaValue result(T_VOID); 1781 JavaCalls::call_virtual(&result, 1782 threadObj, thread_klass, 1783 vmSymbols::dispatchUncaughtException_name(), 1784 vmSymbols::throwable_void_signature(), 1785 uncaught_exception, 1786 THREAD); 1787 if (HAS_PENDING_EXCEPTION) { 1788 ResourceMark rm(this); 1789 jio_fprintf(defaultStream::error_stream(), 1790 "\nException: %s thrown from the UncaughtExceptionHandler" 1791 " in thread \"%s\"\n", 1792 pending_exception()->klass()->external_name(), 1793 get_thread_name()); 1794 CLEAR_PENDING_EXCEPTION; 1795 } 1796 } 1797 1798 // Called before the java thread exit since we want to read info 1799 // from java_lang_Thread object 1800 EventThreadEnd event; 1801 if (event.should_commit()) { 1802 event.set_thread(THREAD_TRACE_ID(this)); 1803 event.commit(); 1804 } 1805 1806 // Call after last event on thread 1807 EVENT_THREAD_EXIT(this); 1808 1809 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1810 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1811 // is deprecated anyhow. 1812 if (!is_Compiler_thread()) { 1813 int count = 3; 1814 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1815 EXCEPTION_MARK; 1816 JavaValue result(T_VOID); 1817 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1818 JavaCalls::call_virtual(&result, 1819 threadObj, thread_klass, 1820 vmSymbols::exit_method_name(), 1821 vmSymbols::void_method_signature(), 1822 THREAD); 1823 CLEAR_PENDING_EXCEPTION; 1824 } 1825 } 1826 // notify JVMTI 1827 if (JvmtiExport::should_post_thread_life()) { 1828 JvmtiExport::post_thread_end(this); 1829 } 1830 1831 // We have notified the agents that we are exiting, before we go on, 1832 // we must check for a pending external suspend request and honor it 1833 // in order to not surprise the thread that made the suspend request. 1834 while (true) { 1835 { 1836 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1837 if (!is_external_suspend()) { 1838 set_terminated(_thread_exiting); 1839 ThreadService::current_thread_exiting(this); 1840 break; 1841 } 1842 // Implied else: 1843 // Things get a little tricky here. We have a pending external 1844 // suspend request, but we are holding the SR_lock so we 1845 // can't just self-suspend. So we temporarily drop the lock 1846 // and then self-suspend. 1847 } 1848 1849 ThreadBlockInVM tbivm(this); 1850 java_suspend_self(); 1851 1852 // We're done with this suspend request, but we have to loop around 1853 // and check again. Eventually we will get SR_lock without a pending 1854 // external suspend request and will be able to mark ourselves as 1855 // exiting. 1856 } 1857 // no more external suspends are allowed at this point 1858 } else { 1859 // before_exit() has already posted JVMTI THREAD_END events 1860 } 1861 1862 // Notify waiters on thread object. This has to be done after exit() is called 1863 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1864 // group should have the destroyed bit set before waiters are notified). 1865 ensure_join(this); 1866 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1867 1868 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1869 // held by this thread must be released. The spec does not distinguish 1870 // between JNI-acquired and regular Java monitors. We can only see 1871 // regular Java monitors here if monitor enter-exit matching is broken. 1872 // 1873 // Optionally release any monitors for regular JavaThread exits. This 1874 // is provided as a work around for any bugs in monitor enter-exit 1875 // matching. This can be expensive so it is not enabled by default. 1876 // 1877 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1878 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1879 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1880 // Sanity check even though JNI DetachCurrentThread() would have 1881 // returned JNI_ERR if there was a Java frame. JavaThread exit 1882 // should be done executing Java code by the time we get here. 1883 assert(!this->has_last_Java_frame(), 1884 "should not have a Java frame when detaching or exiting"); 1885 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1886 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1887 } 1888 1889 // These things needs to be done while we are still a Java Thread. Make sure that thread 1890 // is in a consistent state, in case GC happens 1891 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1892 1893 if (active_handles() != NULL) { 1894 JNIHandleBlock* block = active_handles(); 1895 set_active_handles(NULL); 1896 JNIHandleBlock::release_block(block); 1897 } 1898 1899 if (free_handle_block() != NULL) { 1900 JNIHandleBlock* block = free_handle_block(); 1901 set_free_handle_block(NULL); 1902 JNIHandleBlock::release_block(block); 1903 } 1904 1905 // These have to be removed while this is still a valid thread. 1906 remove_stack_guard_pages(); 1907 1908 if (UseTLAB) { 1909 tlab().make_parsable(true); // retire TLAB 1910 } 1911 1912 if (JvmtiEnv::environments_might_exist()) { 1913 JvmtiExport::cleanup_thread(this); 1914 } 1915 1916 // We must flush any deferred card marks before removing a thread from 1917 // the list of active threads. 1918 Universe::heap()->flush_deferred_store_barrier(this); 1919 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1920 1921 #if INCLUDE_ALL_GCS 1922 // We must flush the G1-related buffers before removing a thread 1923 // from the list of active threads. We must do this after any deferred 1924 // card marks have been flushed (above) so that any entries that are 1925 // added to the thread's dirty card queue as a result are not lost. 1926 if (UseG1GC) { 1927 flush_barrier_queues(); 1928 } 1929 #endif // INCLUDE_ALL_GCS 1930 1931 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1932 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1933 os::current_thread_id()); 1934 1935 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1936 Threads::remove(this); 1937 } 1938 1939 #if INCLUDE_ALL_GCS 1940 // Flush G1-related queues. 1941 void JavaThread::flush_barrier_queues() { 1942 satb_mark_queue().flush(); 1943 dirty_card_queue().flush(); 1944 } 1945 1946 void JavaThread::initialize_queues() { 1947 assert(!SafepointSynchronize::is_at_safepoint(), 1948 "we should not be at a safepoint"); 1949 1950 SATBMarkQueue& satb_queue = satb_mark_queue(); 1951 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1952 // The SATB queue should have been constructed with its active 1953 // field set to false. 1954 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1955 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1956 // If we are creating the thread during a marking cycle, we should 1957 // set the active field of the SATB queue to true. 1958 if (satb_queue_set.is_active()) { 1959 satb_queue.set_active(true); 1960 } 1961 1962 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1963 // The dirty card queue should have been constructed with its 1964 // active field set to true. 1965 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1966 } 1967 #endif // INCLUDE_ALL_GCS 1968 1969 void JavaThread::cleanup_failed_attach_current_thread() { 1970 if (get_thread_profiler() != NULL) { 1971 get_thread_profiler()->disengage(); 1972 ResourceMark rm; 1973 get_thread_profiler()->print(get_thread_name()); 1974 } 1975 1976 if (active_handles() != NULL) { 1977 JNIHandleBlock* block = active_handles(); 1978 set_active_handles(NULL); 1979 JNIHandleBlock::release_block(block); 1980 } 1981 1982 if (free_handle_block() != NULL) { 1983 JNIHandleBlock* block = free_handle_block(); 1984 set_free_handle_block(NULL); 1985 JNIHandleBlock::release_block(block); 1986 } 1987 1988 // These have to be removed while this is still a valid thread. 1989 remove_stack_guard_pages(); 1990 1991 if (UseTLAB) { 1992 tlab().make_parsable(true); // retire TLAB, if any 1993 } 1994 1995 #if INCLUDE_ALL_GCS 1996 if (UseG1GC) { 1997 flush_barrier_queues(); 1998 } 1999 #endif // INCLUDE_ALL_GCS 2000 2001 Threads::remove(this); 2002 delete this; 2003 } 2004 2005 2006 2007 2008 JavaThread* JavaThread::active() { 2009 Thread* thread = Thread::current(); 2010 if (thread->is_Java_thread()) { 2011 return (JavaThread*) thread; 2012 } else { 2013 assert(thread->is_VM_thread(), "this must be a vm thread"); 2014 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2015 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2016 assert(ret->is_Java_thread(), "must be a Java thread"); 2017 return ret; 2018 } 2019 } 2020 2021 bool JavaThread::is_lock_owned(address adr) const { 2022 if (Thread::is_lock_owned(adr)) return true; 2023 2024 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2025 if (chunk->contains(adr)) return true; 2026 } 2027 2028 return false; 2029 } 2030 2031 2032 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2033 chunk->set_next(monitor_chunks()); 2034 set_monitor_chunks(chunk); 2035 } 2036 2037 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2038 guarantee(monitor_chunks() != NULL, "must be non empty"); 2039 if (monitor_chunks() == chunk) { 2040 set_monitor_chunks(chunk->next()); 2041 } else { 2042 MonitorChunk* prev = monitor_chunks(); 2043 while (prev->next() != chunk) prev = prev->next(); 2044 prev->set_next(chunk->next()); 2045 } 2046 } 2047 2048 // JVM support. 2049 2050 // Note: this function shouldn't block if it's called in 2051 // _thread_in_native_trans state (such as from 2052 // check_special_condition_for_native_trans()). 2053 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2054 2055 if (has_last_Java_frame() && has_async_condition()) { 2056 // If we are at a polling page safepoint (not a poll return) 2057 // then we must defer async exception because live registers 2058 // will be clobbered by the exception path. Poll return is 2059 // ok because the call we a returning from already collides 2060 // with exception handling registers and so there is no issue. 2061 // (The exception handling path kills call result registers but 2062 // this is ok since the exception kills the result anyway). 2063 2064 if (is_at_poll_safepoint()) { 2065 // if the code we are returning to has deoptimized we must defer 2066 // the exception otherwise live registers get clobbered on the 2067 // exception path before deoptimization is able to retrieve them. 2068 // 2069 RegisterMap map(this, false); 2070 frame caller_fr = last_frame().sender(&map); 2071 assert(caller_fr.is_compiled_frame(), "what?"); 2072 if (caller_fr.is_deoptimized_frame()) { 2073 log_info(exceptions)("deferred async exception at compiled safepoint"); 2074 return; 2075 } 2076 } 2077 } 2078 2079 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2080 if (condition == _no_async_condition) { 2081 // Conditions have changed since has_special_runtime_exit_condition() 2082 // was called: 2083 // - if we were here only because of an external suspend request, 2084 // then that was taken care of above (or cancelled) so we are done 2085 // - if we were here because of another async request, then it has 2086 // been cleared between the has_special_runtime_exit_condition() 2087 // and now so again we are done 2088 return; 2089 } 2090 2091 // Check for pending async. exception 2092 if (_pending_async_exception != NULL) { 2093 // Only overwrite an already pending exception, if it is not a threadDeath. 2094 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2095 2096 // We cannot call Exceptions::_throw(...) here because we cannot block 2097 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2098 2099 if (log_is_enabled(Info, exceptions)) { 2100 ResourceMark rm; 2101 outputStream* logstream = Log(exceptions)::info_stream(); 2102 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2103 if (has_last_Java_frame()) { 2104 frame f = last_frame(); 2105 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2106 } 2107 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2108 } 2109 _pending_async_exception = NULL; 2110 clear_has_async_exception(); 2111 } 2112 } 2113 2114 if (check_unsafe_error && 2115 condition == _async_unsafe_access_error && !has_pending_exception()) { 2116 condition = _no_async_condition; // done 2117 switch (thread_state()) { 2118 case _thread_in_vm: { 2119 JavaThread* THREAD = this; 2120 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2121 } 2122 case _thread_in_native: { 2123 ThreadInVMfromNative tiv(this); 2124 JavaThread* THREAD = this; 2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2126 } 2127 case _thread_in_Java: { 2128 ThreadInVMfromJava tiv(this); 2129 JavaThread* THREAD = this; 2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2131 } 2132 default: 2133 ShouldNotReachHere(); 2134 } 2135 } 2136 2137 assert(condition == _no_async_condition || has_pending_exception() || 2138 (!check_unsafe_error && condition == _async_unsafe_access_error), 2139 "must have handled the async condition, if no exception"); 2140 } 2141 2142 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2143 // 2144 // Check for pending external suspend. Internal suspend requests do 2145 // not use handle_special_runtime_exit_condition(). 2146 // If JNIEnv proxies are allowed, don't self-suspend if the target 2147 // thread is not the current thread. In older versions of jdbx, jdbx 2148 // threads could call into the VM with another thread's JNIEnv so we 2149 // can be here operating on behalf of a suspended thread (4432884). 2150 bool do_self_suspend = is_external_suspend_with_lock(); 2151 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2152 // 2153 // Because thread is external suspended the safepoint code will count 2154 // thread as at a safepoint. This can be odd because we can be here 2155 // as _thread_in_Java which would normally transition to _thread_blocked 2156 // at a safepoint. We would like to mark the thread as _thread_blocked 2157 // before calling java_suspend_self like all other callers of it but 2158 // we must then observe proper safepoint protocol. (We can't leave 2159 // _thread_blocked with a safepoint in progress). However we can be 2160 // here as _thread_in_native_trans so we can't use a normal transition 2161 // constructor/destructor pair because they assert on that type of 2162 // transition. We could do something like: 2163 // 2164 // JavaThreadState state = thread_state(); 2165 // set_thread_state(_thread_in_vm); 2166 // { 2167 // ThreadBlockInVM tbivm(this); 2168 // java_suspend_self() 2169 // } 2170 // set_thread_state(_thread_in_vm_trans); 2171 // if (safepoint) block; 2172 // set_thread_state(state); 2173 // 2174 // but that is pretty messy. Instead we just go with the way the 2175 // code has worked before and note that this is the only path to 2176 // java_suspend_self that doesn't put the thread in _thread_blocked 2177 // mode. 2178 2179 frame_anchor()->make_walkable(this); 2180 java_suspend_self(); 2181 2182 // We might be here for reasons in addition to the self-suspend request 2183 // so check for other async requests. 2184 } 2185 2186 if (check_asyncs) { 2187 check_and_handle_async_exceptions(); 2188 } 2189 } 2190 2191 void JavaThread::send_thread_stop(oop java_throwable) { 2192 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2193 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2194 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2195 2196 // Do not throw asynchronous exceptions against the compiler thread 2197 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2198 if (!can_call_java()) return; 2199 2200 { 2201 // Actually throw the Throwable against the target Thread - however 2202 // only if there is no thread death exception installed already. 2203 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2204 // If the topmost frame is a runtime stub, then we are calling into 2205 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2206 // must deoptimize the caller before continuing, as the compiled exception handler table 2207 // may not be valid 2208 if (has_last_Java_frame()) { 2209 frame f = last_frame(); 2210 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2211 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2212 RegisterMap reg_map(this, UseBiasedLocking); 2213 frame compiled_frame = f.sender(®_map); 2214 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2215 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2216 } 2217 } 2218 } 2219 2220 // Set async. pending exception in thread. 2221 set_pending_async_exception(java_throwable); 2222 2223 if (log_is_enabled(Info, exceptions)) { 2224 ResourceMark rm; 2225 log_info(exceptions)("Pending Async. exception installed of type: %s", 2226 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2227 } 2228 // for AbortVMOnException flag 2229 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2230 } 2231 } 2232 2233 2234 // Interrupt thread so it will wake up from a potential wait() 2235 Thread::interrupt(this); 2236 } 2237 2238 // External suspension mechanism. 2239 // 2240 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2241 // to any VM_locks and it is at a transition 2242 // Self-suspension will happen on the transition out of the vm. 2243 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2244 // 2245 // Guarantees on return: 2246 // + Target thread will not execute any new bytecode (that's why we need to 2247 // force a safepoint) 2248 // + Target thread will not enter any new monitors 2249 // 2250 void JavaThread::java_suspend() { 2251 { MutexLocker mu(Threads_lock); 2252 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2253 return; 2254 } 2255 } 2256 2257 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2258 if (!is_external_suspend()) { 2259 // a racing resume has cancelled us; bail out now 2260 return; 2261 } 2262 2263 // suspend is done 2264 uint32_t debug_bits = 0; 2265 // Warning: is_ext_suspend_completed() may temporarily drop the 2266 // SR_lock to allow the thread to reach a stable thread state if 2267 // it is currently in a transient thread state. 2268 if (is_ext_suspend_completed(false /* !called_by_wait */, 2269 SuspendRetryDelay, &debug_bits)) { 2270 return; 2271 } 2272 } 2273 2274 VM_ForceSafepoint vm_suspend; 2275 VMThread::execute(&vm_suspend); 2276 } 2277 2278 // Part II of external suspension. 2279 // A JavaThread self suspends when it detects a pending external suspend 2280 // request. This is usually on transitions. It is also done in places 2281 // where continuing to the next transition would surprise the caller, 2282 // e.g., monitor entry. 2283 // 2284 // Returns the number of times that the thread self-suspended. 2285 // 2286 // Note: DO NOT call java_suspend_self() when you just want to block current 2287 // thread. java_suspend_self() is the second stage of cooperative 2288 // suspension for external suspend requests and should only be used 2289 // to complete an external suspend request. 2290 // 2291 int JavaThread::java_suspend_self() { 2292 int ret = 0; 2293 2294 // we are in the process of exiting so don't suspend 2295 if (is_exiting()) { 2296 clear_external_suspend(); 2297 return ret; 2298 } 2299 2300 assert(_anchor.walkable() || 2301 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2302 "must have walkable stack"); 2303 2304 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2305 2306 assert(!this->is_ext_suspended(), 2307 "a thread trying to self-suspend should not already be suspended"); 2308 2309 if (this->is_suspend_equivalent()) { 2310 // If we are self-suspending as a result of the lifting of a 2311 // suspend equivalent condition, then the suspend_equivalent 2312 // flag is not cleared until we set the ext_suspended flag so 2313 // that wait_for_ext_suspend_completion() returns consistent 2314 // results. 2315 this->clear_suspend_equivalent(); 2316 } 2317 2318 // A racing resume may have cancelled us before we grabbed SR_lock 2319 // above. Or another external suspend request could be waiting for us 2320 // by the time we return from SR_lock()->wait(). The thread 2321 // that requested the suspension may already be trying to walk our 2322 // stack and if we return now, we can change the stack out from under 2323 // it. This would be a "bad thing (TM)" and cause the stack walker 2324 // to crash. We stay self-suspended until there are no more pending 2325 // external suspend requests. 2326 while (is_external_suspend()) { 2327 ret++; 2328 this->set_ext_suspended(); 2329 2330 // _ext_suspended flag is cleared by java_resume() 2331 while (is_ext_suspended()) { 2332 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2333 } 2334 } 2335 2336 return ret; 2337 } 2338 2339 #ifdef ASSERT 2340 // verify the JavaThread has not yet been published in the Threads::list, and 2341 // hence doesn't need protection from concurrent access at this stage 2342 void JavaThread::verify_not_published() { 2343 if (!Threads_lock->owned_by_self()) { 2344 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2345 assert(!Threads::includes(this), 2346 "java thread shouldn't have been published yet!"); 2347 } else { 2348 assert(!Threads::includes(this), 2349 "java thread shouldn't have been published yet!"); 2350 } 2351 } 2352 #endif 2353 2354 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2355 // progress or when _suspend_flags is non-zero. 2356 // Current thread needs to self-suspend if there is a suspend request and/or 2357 // block if a safepoint is in progress. 2358 // Async exception ISN'T checked. 2359 // Note only the ThreadInVMfromNative transition can call this function 2360 // directly and when thread state is _thread_in_native_trans 2361 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2362 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2363 2364 JavaThread *curJT = JavaThread::current(); 2365 bool do_self_suspend = thread->is_external_suspend(); 2366 2367 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2368 2369 // If JNIEnv proxies are allowed, don't self-suspend if the target 2370 // thread is not the current thread. In older versions of jdbx, jdbx 2371 // threads could call into the VM with another thread's JNIEnv so we 2372 // can be here operating on behalf of a suspended thread (4432884). 2373 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2374 JavaThreadState state = thread->thread_state(); 2375 2376 // We mark this thread_blocked state as a suspend-equivalent so 2377 // that a caller to is_ext_suspend_completed() won't be confused. 2378 // The suspend-equivalent state is cleared by java_suspend_self(). 2379 thread->set_suspend_equivalent(); 2380 2381 // If the safepoint code sees the _thread_in_native_trans state, it will 2382 // wait until the thread changes to other thread state. There is no 2383 // guarantee on how soon we can obtain the SR_lock and complete the 2384 // self-suspend request. It would be a bad idea to let safepoint wait for 2385 // too long. Temporarily change the state to _thread_blocked to 2386 // let the VM thread know that this thread is ready for GC. The problem 2387 // of changing thread state is that safepoint could happen just after 2388 // java_suspend_self() returns after being resumed, and VM thread will 2389 // see the _thread_blocked state. We must check for safepoint 2390 // after restoring the state and make sure we won't leave while a safepoint 2391 // is in progress. 2392 thread->set_thread_state(_thread_blocked); 2393 thread->java_suspend_self(); 2394 thread->set_thread_state(state); 2395 // Make sure new state is seen by VM thread 2396 if (os::is_MP()) { 2397 if (UseMembar) { 2398 // Force a fence between the write above and read below 2399 OrderAccess::fence(); 2400 } else { 2401 // Must use this rather than serialization page in particular on Windows 2402 InterfaceSupport::serialize_memory(thread); 2403 } 2404 } 2405 } 2406 2407 if (SafepointSynchronize::do_call_back()) { 2408 // If we are safepointing, then block the caller which may not be 2409 // the same as the target thread (see above). 2410 SafepointSynchronize::block(curJT); 2411 } 2412 2413 if (thread->is_deopt_suspend()) { 2414 thread->clear_deopt_suspend(); 2415 RegisterMap map(thread, false); 2416 frame f = thread->last_frame(); 2417 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2418 f = f.sender(&map); 2419 } 2420 if (f.id() == thread->must_deopt_id()) { 2421 thread->clear_must_deopt_id(); 2422 f.deoptimize(thread); 2423 } else { 2424 fatal("missed deoptimization!"); 2425 } 2426 } 2427 } 2428 2429 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2430 // progress or when _suspend_flags is non-zero. 2431 // Current thread needs to self-suspend if there is a suspend request and/or 2432 // block if a safepoint is in progress. 2433 // Also check for pending async exception (not including unsafe access error). 2434 // Note only the native==>VM/Java barriers can call this function and when 2435 // thread state is _thread_in_native_trans. 2436 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2437 check_safepoint_and_suspend_for_native_trans(thread); 2438 2439 if (thread->has_async_exception()) { 2440 // We are in _thread_in_native_trans state, don't handle unsafe 2441 // access error since that may block. 2442 thread->check_and_handle_async_exceptions(false); 2443 } 2444 } 2445 2446 // This is a variant of the normal 2447 // check_special_condition_for_native_trans with slightly different 2448 // semantics for use by critical native wrappers. It does all the 2449 // normal checks but also performs the transition back into 2450 // thread_in_Java state. This is required so that critical natives 2451 // can potentially block and perform a GC if they are the last thread 2452 // exiting the GCLocker. 2453 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2454 check_special_condition_for_native_trans(thread); 2455 2456 // Finish the transition 2457 thread->set_thread_state(_thread_in_Java); 2458 2459 if (thread->do_critical_native_unlock()) { 2460 ThreadInVMfromJavaNoAsyncException tiv(thread); 2461 GCLocker::unlock_critical(thread); 2462 thread->clear_critical_native_unlock(); 2463 } 2464 } 2465 2466 // We need to guarantee the Threads_lock here, since resumes are not 2467 // allowed during safepoint synchronization 2468 // Can only resume from an external suspension 2469 void JavaThread::java_resume() { 2470 assert_locked_or_safepoint(Threads_lock); 2471 2472 // Sanity check: thread is gone, has started exiting or the thread 2473 // was not externally suspended. 2474 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2475 return; 2476 } 2477 2478 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2479 2480 clear_external_suspend(); 2481 2482 if (is_ext_suspended()) { 2483 clear_ext_suspended(); 2484 SR_lock()->notify_all(); 2485 } 2486 } 2487 2488 size_t JavaThread::_stack_red_zone_size = 0; 2489 size_t JavaThread::_stack_yellow_zone_size = 0; 2490 size_t JavaThread::_stack_reserved_zone_size = 0; 2491 size_t JavaThread::_stack_shadow_zone_size = 0; 2492 2493 void JavaThread::create_stack_guard_pages() { 2494 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2495 address low_addr = stack_end(); 2496 size_t len = stack_guard_zone_size(); 2497 2498 int must_commit = os::must_commit_stack_guard_pages(); 2499 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2500 2501 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2502 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2503 return; 2504 } 2505 2506 if (os::guard_memory((char *) low_addr, len)) { 2507 _stack_guard_state = stack_guard_enabled; 2508 } else { 2509 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2510 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2511 if (os::uncommit_memory((char *) low_addr, len)) { 2512 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2513 } 2514 return; 2515 } 2516 2517 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2518 PTR_FORMAT "-" PTR_FORMAT ".", 2519 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2520 } 2521 2522 void JavaThread::remove_stack_guard_pages() { 2523 assert(Thread::current() == this, "from different thread"); 2524 if (_stack_guard_state == stack_guard_unused) return; 2525 address low_addr = stack_end(); 2526 size_t len = stack_guard_zone_size(); 2527 2528 if (os::must_commit_stack_guard_pages()) { 2529 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2530 _stack_guard_state = stack_guard_unused; 2531 } else { 2532 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2533 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2534 return; 2535 } 2536 } else { 2537 if (_stack_guard_state == stack_guard_unused) return; 2538 if (os::unguard_memory((char *) low_addr, len)) { 2539 _stack_guard_state = stack_guard_unused; 2540 } else { 2541 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2542 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2543 return; 2544 } 2545 } 2546 2547 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2548 PTR_FORMAT "-" PTR_FORMAT ".", 2549 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2550 } 2551 2552 void JavaThread::enable_stack_reserved_zone() { 2553 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2554 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2555 2556 // The base notation is from the stack's point of view, growing downward. 2557 // We need to adjust it to work correctly with guard_memory() 2558 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2559 2560 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2561 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2562 2563 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2564 _stack_guard_state = stack_guard_enabled; 2565 } else { 2566 warning("Attempt to guard stack reserved zone failed."); 2567 } 2568 enable_register_stack_guard(); 2569 } 2570 2571 void JavaThread::disable_stack_reserved_zone() { 2572 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2573 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2574 2575 // Simply return if called for a thread that does not use guard pages. 2576 if (_stack_guard_state == stack_guard_unused) return; 2577 2578 // The base notation is from the stack's point of view, growing downward. 2579 // We need to adjust it to work correctly with guard_memory() 2580 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2581 2582 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2583 _stack_guard_state = stack_guard_reserved_disabled; 2584 } else { 2585 warning("Attempt to unguard stack reserved zone failed."); 2586 } 2587 disable_register_stack_guard(); 2588 } 2589 2590 void JavaThread::enable_stack_yellow_reserved_zone() { 2591 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2592 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2593 2594 // The base notation is from the stacks point of view, growing downward. 2595 // We need to adjust it to work correctly with guard_memory() 2596 address base = stack_red_zone_base(); 2597 2598 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2599 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2600 2601 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2602 _stack_guard_state = stack_guard_enabled; 2603 } else { 2604 warning("Attempt to guard stack yellow zone failed."); 2605 } 2606 enable_register_stack_guard(); 2607 } 2608 2609 void JavaThread::disable_stack_yellow_reserved_zone() { 2610 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2611 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2612 2613 // Simply return if called for a thread that does not use guard pages. 2614 if (_stack_guard_state == stack_guard_unused) return; 2615 2616 // The base notation is from the stacks point of view, growing downward. 2617 // We need to adjust it to work correctly with guard_memory() 2618 address base = stack_red_zone_base(); 2619 2620 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2621 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2622 } else { 2623 warning("Attempt to unguard stack yellow zone failed."); 2624 } 2625 disable_register_stack_guard(); 2626 } 2627 2628 void JavaThread::enable_stack_red_zone() { 2629 // The base notation is from the stacks point of view, growing downward. 2630 // We need to adjust it to work correctly with guard_memory() 2631 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2632 address base = stack_red_zone_base() - stack_red_zone_size(); 2633 2634 guarantee(base < stack_base(), "Error calculating stack red zone"); 2635 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2636 2637 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2638 warning("Attempt to guard stack red zone failed."); 2639 } 2640 } 2641 2642 void JavaThread::disable_stack_red_zone() { 2643 // The base notation is from the stacks point of view, growing downward. 2644 // We need to adjust it to work correctly with guard_memory() 2645 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2646 address base = stack_red_zone_base() - stack_red_zone_size(); 2647 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2648 warning("Attempt to unguard stack red zone failed."); 2649 } 2650 } 2651 2652 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2653 // ignore is there is no stack 2654 if (!has_last_Java_frame()) return; 2655 // traverse the stack frames. Starts from top frame. 2656 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2657 frame* fr = fst.current(); 2658 f(fr, fst.register_map()); 2659 } 2660 } 2661 2662 2663 #ifndef PRODUCT 2664 // Deoptimization 2665 // Function for testing deoptimization 2666 void JavaThread::deoptimize() { 2667 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2668 StackFrameStream fst(this, UseBiasedLocking); 2669 bool deopt = false; // Dump stack only if a deopt actually happens. 2670 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2671 // Iterate over all frames in the thread and deoptimize 2672 for (; !fst.is_done(); fst.next()) { 2673 if (fst.current()->can_be_deoptimized()) { 2674 2675 if (only_at) { 2676 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2677 // consists of comma or carriage return separated numbers so 2678 // search for the current bci in that string. 2679 address pc = fst.current()->pc(); 2680 nmethod* nm = (nmethod*) fst.current()->cb(); 2681 ScopeDesc* sd = nm->scope_desc_at(pc); 2682 char buffer[8]; 2683 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2684 size_t len = strlen(buffer); 2685 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2686 while (found != NULL) { 2687 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2688 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2689 // Check that the bci found is bracketed by terminators. 2690 break; 2691 } 2692 found = strstr(found + 1, buffer); 2693 } 2694 if (!found) { 2695 continue; 2696 } 2697 } 2698 2699 if (DebugDeoptimization && !deopt) { 2700 deopt = true; // One-time only print before deopt 2701 tty->print_cr("[BEFORE Deoptimization]"); 2702 trace_frames(); 2703 trace_stack(); 2704 } 2705 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2706 } 2707 } 2708 2709 if (DebugDeoptimization && deopt) { 2710 tty->print_cr("[AFTER Deoptimization]"); 2711 trace_frames(); 2712 } 2713 } 2714 2715 2716 // Make zombies 2717 void JavaThread::make_zombies() { 2718 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2719 if (fst.current()->can_be_deoptimized()) { 2720 // it is a Java nmethod 2721 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2722 nm->make_not_entrant(); 2723 } 2724 } 2725 } 2726 #endif // PRODUCT 2727 2728 2729 void JavaThread::deoptimized_wrt_marked_nmethods() { 2730 if (!has_last_Java_frame()) return; 2731 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2732 StackFrameStream fst(this, UseBiasedLocking); 2733 for (; !fst.is_done(); fst.next()) { 2734 if (fst.current()->should_be_deoptimized()) { 2735 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2736 } 2737 } 2738 } 2739 2740 2741 // If the caller is a NamedThread, then remember, in the current scope, 2742 // the given JavaThread in its _processed_thread field. 2743 class RememberProcessedThread: public StackObj { 2744 NamedThread* _cur_thr; 2745 public: 2746 RememberProcessedThread(JavaThread* jthr) { 2747 Thread* thread = Thread::current(); 2748 if (thread->is_Named_thread()) { 2749 _cur_thr = (NamedThread *)thread; 2750 _cur_thr->set_processed_thread(jthr); 2751 } else { 2752 _cur_thr = NULL; 2753 } 2754 } 2755 2756 ~RememberProcessedThread() { 2757 if (_cur_thr) { 2758 _cur_thr->set_processed_thread(NULL); 2759 } 2760 } 2761 }; 2762 2763 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2764 // Verify that the deferred card marks have been flushed. 2765 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2766 2767 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2768 // since there may be more than one thread using each ThreadProfiler. 2769 2770 // Traverse the GCHandles 2771 Thread::oops_do(f, cf); 2772 2773 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2774 2775 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2776 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2777 2778 if (has_last_Java_frame()) { 2779 // Record JavaThread to GC thread 2780 RememberProcessedThread rpt(this); 2781 2782 // Traverse the privileged stack 2783 if (_privileged_stack_top != NULL) { 2784 _privileged_stack_top->oops_do(f); 2785 } 2786 2787 // traverse the registered growable array 2788 if (_array_for_gc != NULL) { 2789 for (int index = 0; index < _array_for_gc->length(); index++) { 2790 f->do_oop(_array_for_gc->adr_at(index)); 2791 } 2792 } 2793 2794 // Traverse the monitor chunks 2795 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2796 chunk->oops_do(f); 2797 } 2798 2799 // Traverse the execution stack 2800 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2801 fst.current()->oops_do(f, cf, fst.register_map()); 2802 } 2803 } 2804 2805 // callee_target is never live across a gc point so NULL it here should 2806 // it still contain a methdOop. 2807 2808 set_callee_target(NULL); 2809 2810 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2811 // If we have deferred set_locals there might be oops waiting to be 2812 // written 2813 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2814 if (list != NULL) { 2815 for (int i = 0; i < list->length(); i++) { 2816 list->at(i)->oops_do(f); 2817 } 2818 } 2819 2820 // Traverse instance variables at the end since the GC may be moving things 2821 // around using this function 2822 f->do_oop((oop*) &_threadObj); 2823 f->do_oop((oop*) &_vm_result); 2824 f->do_oop((oop*) &_exception_oop); 2825 f->do_oop((oop*) &_pending_async_exception); 2826 2827 if (jvmti_thread_state() != NULL) { 2828 jvmti_thread_state()->oops_do(f); 2829 } 2830 } 2831 2832 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2833 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2834 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2835 2836 if (has_last_Java_frame()) { 2837 // Traverse the execution stack 2838 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2839 fst.current()->nmethods_do(cf); 2840 } 2841 } 2842 } 2843 2844 void JavaThread::metadata_do(void f(Metadata*)) { 2845 if (has_last_Java_frame()) { 2846 // Traverse the execution stack to call f() on the methods in the stack 2847 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2848 fst.current()->metadata_do(f); 2849 } 2850 } else if (is_Compiler_thread()) { 2851 // need to walk ciMetadata in current compile tasks to keep alive. 2852 CompilerThread* ct = (CompilerThread*)this; 2853 if (ct->env() != NULL) { 2854 ct->env()->metadata_do(f); 2855 } 2856 if (ct->task() != NULL) { 2857 ct->task()->metadata_do(f); 2858 } 2859 } 2860 } 2861 2862 // Printing 2863 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2864 switch (_thread_state) { 2865 case _thread_uninitialized: return "_thread_uninitialized"; 2866 case _thread_new: return "_thread_new"; 2867 case _thread_new_trans: return "_thread_new_trans"; 2868 case _thread_in_native: return "_thread_in_native"; 2869 case _thread_in_native_trans: return "_thread_in_native_trans"; 2870 case _thread_in_vm: return "_thread_in_vm"; 2871 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2872 case _thread_in_Java: return "_thread_in_Java"; 2873 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2874 case _thread_blocked: return "_thread_blocked"; 2875 case _thread_blocked_trans: return "_thread_blocked_trans"; 2876 default: return "unknown thread state"; 2877 } 2878 } 2879 2880 #ifndef PRODUCT 2881 void JavaThread::print_thread_state_on(outputStream *st) const { 2882 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2883 }; 2884 void JavaThread::print_thread_state() const { 2885 print_thread_state_on(tty); 2886 } 2887 #endif // PRODUCT 2888 2889 // Called by Threads::print() for VM_PrintThreads operation 2890 void JavaThread::print_on(outputStream *st) const { 2891 st->print_raw("\""); 2892 st->print_raw(get_thread_name()); 2893 st->print_raw("\" "); 2894 oop thread_oop = threadObj(); 2895 if (thread_oop != NULL) { 2896 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2897 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2898 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2899 } 2900 Thread::print_on(st); 2901 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2902 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2903 if (thread_oop != NULL) { 2904 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2905 } 2906 #ifndef PRODUCT 2907 print_thread_state_on(st); 2908 _safepoint_state->print_on(st); 2909 #endif // PRODUCT 2910 if (is_Compiler_thread()) { 2911 CompilerThread* ct = (CompilerThread*)this; 2912 if (ct->task() != NULL) { 2913 st->print(" Compiling: "); 2914 ct->task()->print(st, NULL, true, false); 2915 } else { 2916 st->print(" No compile task"); 2917 } 2918 st->cr(); 2919 } 2920 } 2921 2922 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2923 st->print("%s", get_thread_name_string(buf, buflen)); 2924 } 2925 2926 // Called by fatal error handler. The difference between this and 2927 // JavaThread::print() is that we can't grab lock or allocate memory. 2928 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2929 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2930 oop thread_obj = threadObj(); 2931 if (thread_obj != NULL) { 2932 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2933 } 2934 st->print(" ["); 2935 st->print("%s", _get_thread_state_name(_thread_state)); 2936 if (osthread()) { 2937 st->print(", id=%d", osthread()->thread_id()); 2938 } 2939 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2940 p2i(stack_end()), p2i(stack_base())); 2941 st->print("]"); 2942 return; 2943 } 2944 2945 // Verification 2946 2947 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2948 2949 void JavaThread::verify() { 2950 // Verify oops in the thread. 2951 oops_do(&VerifyOopClosure::verify_oop, NULL); 2952 2953 // Verify the stack frames. 2954 frames_do(frame_verify); 2955 } 2956 2957 // CR 6300358 (sub-CR 2137150) 2958 // Most callers of this method assume that it can't return NULL but a 2959 // thread may not have a name whilst it is in the process of attaching to 2960 // the VM - see CR 6412693, and there are places where a JavaThread can be 2961 // seen prior to having it's threadObj set (eg JNI attaching threads and 2962 // if vm exit occurs during initialization). These cases can all be accounted 2963 // for such that this method never returns NULL. 2964 const char* JavaThread::get_thread_name() const { 2965 #ifdef ASSERT 2966 // early safepoints can hit while current thread does not yet have TLS 2967 if (!SafepointSynchronize::is_at_safepoint()) { 2968 Thread *cur = Thread::current(); 2969 if (!(cur->is_Java_thread() && cur == this)) { 2970 // Current JavaThreads are allowed to get their own name without 2971 // the Threads_lock. 2972 assert_locked_or_safepoint(Threads_lock); 2973 } 2974 } 2975 #endif // ASSERT 2976 return get_thread_name_string(); 2977 } 2978 2979 // Returns a non-NULL representation of this thread's name, or a suitable 2980 // descriptive string if there is no set name 2981 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2982 const char* name_str; 2983 oop thread_obj = threadObj(); 2984 if (thread_obj != NULL) { 2985 oop name = java_lang_Thread::name(thread_obj); 2986 if (name != NULL) { 2987 if (buf == NULL) { 2988 name_str = java_lang_String::as_utf8_string(name); 2989 } else { 2990 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2991 } 2992 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2993 name_str = "<no-name - thread is attaching>"; 2994 } else { 2995 name_str = Thread::name(); 2996 } 2997 } else { 2998 name_str = Thread::name(); 2999 } 3000 assert(name_str != NULL, "unexpected NULL thread name"); 3001 return name_str; 3002 } 3003 3004 3005 const char* JavaThread::get_threadgroup_name() const { 3006 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3007 oop thread_obj = threadObj(); 3008 if (thread_obj != NULL) { 3009 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3010 if (thread_group != NULL) { 3011 // ThreadGroup.name can be null 3012 return java_lang_ThreadGroup::name(thread_group); 3013 } 3014 } 3015 return NULL; 3016 } 3017 3018 const char* JavaThread::get_parent_name() const { 3019 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3020 oop thread_obj = threadObj(); 3021 if (thread_obj != NULL) { 3022 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3023 if (thread_group != NULL) { 3024 oop parent = java_lang_ThreadGroup::parent(thread_group); 3025 if (parent != NULL) { 3026 // ThreadGroup.name can be null 3027 return java_lang_ThreadGroup::name(parent); 3028 } 3029 } 3030 } 3031 return NULL; 3032 } 3033 3034 ThreadPriority JavaThread::java_priority() const { 3035 oop thr_oop = threadObj(); 3036 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3037 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3038 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3039 return priority; 3040 } 3041 3042 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3043 3044 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3045 // Link Java Thread object <-> C++ Thread 3046 3047 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3048 // and put it into a new Handle. The Handle "thread_oop" can then 3049 // be used to pass the C++ thread object to other methods. 3050 3051 // Set the Java level thread object (jthread) field of the 3052 // new thread (a JavaThread *) to C++ thread object using the 3053 // "thread_oop" handle. 3054 3055 // Set the thread field (a JavaThread *) of the 3056 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3057 3058 Handle thread_oop(Thread::current(), 3059 JNIHandles::resolve_non_null(jni_thread)); 3060 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3061 "must be initialized"); 3062 set_threadObj(thread_oop()); 3063 java_lang_Thread::set_thread(thread_oop(), this); 3064 3065 if (prio == NoPriority) { 3066 prio = java_lang_Thread::priority(thread_oop()); 3067 assert(prio != NoPriority, "A valid priority should be present"); 3068 } 3069 3070 // Push the Java priority down to the native thread; needs Threads_lock 3071 Thread::set_priority(this, prio); 3072 3073 prepare_ext(); 3074 3075 // Add the new thread to the Threads list and set it in motion. 3076 // We must have threads lock in order to call Threads::add. 3077 // It is crucial that we do not block before the thread is 3078 // added to the Threads list for if a GC happens, then the java_thread oop 3079 // will not be visited by GC. 3080 Threads::add(this); 3081 } 3082 3083 oop JavaThread::current_park_blocker() { 3084 // Support for JSR-166 locks 3085 oop thread_oop = threadObj(); 3086 if (thread_oop != NULL && 3087 JDK_Version::current().supports_thread_park_blocker()) { 3088 return java_lang_Thread::park_blocker(thread_oop); 3089 } 3090 return NULL; 3091 } 3092 3093 3094 void JavaThread::print_stack_on(outputStream* st) { 3095 if (!has_last_Java_frame()) return; 3096 ResourceMark rm; 3097 HandleMark hm; 3098 3099 RegisterMap reg_map(this); 3100 vframe* start_vf = last_java_vframe(®_map); 3101 int count = 0; 3102 for (vframe* f = start_vf; f; f = f->sender()) { 3103 if (f->is_java_frame()) { 3104 javaVFrame* jvf = javaVFrame::cast(f); 3105 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3106 3107 // Print out lock information 3108 if (JavaMonitorsInStackTrace) { 3109 jvf->print_lock_info_on(st, count); 3110 } 3111 } else { 3112 // Ignore non-Java frames 3113 } 3114 3115 // Bail-out case for too deep stacks 3116 count++; 3117 if (MaxJavaStackTraceDepth == count) return; 3118 } 3119 } 3120 3121 3122 // JVMTI PopFrame support 3123 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3124 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3125 if (in_bytes(size_in_bytes) != 0) { 3126 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3127 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3128 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3129 } 3130 } 3131 3132 void* JavaThread::popframe_preserved_args() { 3133 return _popframe_preserved_args; 3134 } 3135 3136 ByteSize JavaThread::popframe_preserved_args_size() { 3137 return in_ByteSize(_popframe_preserved_args_size); 3138 } 3139 3140 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3141 int sz = in_bytes(popframe_preserved_args_size()); 3142 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3143 return in_WordSize(sz / wordSize); 3144 } 3145 3146 void JavaThread::popframe_free_preserved_args() { 3147 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3148 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3149 _popframe_preserved_args = NULL; 3150 _popframe_preserved_args_size = 0; 3151 } 3152 3153 #ifndef PRODUCT 3154 3155 void JavaThread::trace_frames() { 3156 tty->print_cr("[Describe stack]"); 3157 int frame_no = 1; 3158 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3159 tty->print(" %d. ", frame_no++); 3160 fst.current()->print_value_on(tty, this); 3161 tty->cr(); 3162 } 3163 } 3164 3165 class PrintAndVerifyOopClosure: public OopClosure { 3166 protected: 3167 template <class T> inline void do_oop_work(T* p) { 3168 oop obj = oopDesc::load_decode_heap_oop(p); 3169 if (obj == NULL) return; 3170 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3171 if (obj->is_oop_or_null()) { 3172 if (obj->is_objArray()) { 3173 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3174 } else { 3175 obj->print(); 3176 } 3177 } else { 3178 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3179 } 3180 tty->cr(); 3181 } 3182 public: 3183 virtual void do_oop(oop* p) { do_oop_work(p); } 3184 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3185 }; 3186 3187 3188 static void oops_print(frame* f, const RegisterMap *map) { 3189 PrintAndVerifyOopClosure print; 3190 f->print_value(); 3191 f->oops_do(&print, NULL, (RegisterMap*)map); 3192 } 3193 3194 // Print our all the locations that contain oops and whether they are 3195 // valid or not. This useful when trying to find the oldest frame 3196 // where an oop has gone bad since the frame walk is from youngest to 3197 // oldest. 3198 void JavaThread::trace_oops() { 3199 tty->print_cr("[Trace oops]"); 3200 frames_do(oops_print); 3201 } 3202 3203 3204 #ifdef ASSERT 3205 // Print or validate the layout of stack frames 3206 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3207 ResourceMark rm; 3208 PRESERVE_EXCEPTION_MARK; 3209 FrameValues values; 3210 int frame_no = 0; 3211 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3212 fst.current()->describe(values, ++frame_no); 3213 if (depth == frame_no) break; 3214 } 3215 if (validate_only) { 3216 values.validate(); 3217 } else { 3218 tty->print_cr("[Describe stack layout]"); 3219 values.print(this); 3220 } 3221 } 3222 #endif 3223 3224 void JavaThread::trace_stack_from(vframe* start_vf) { 3225 ResourceMark rm; 3226 int vframe_no = 1; 3227 for (vframe* f = start_vf; f; f = f->sender()) { 3228 if (f->is_java_frame()) { 3229 javaVFrame::cast(f)->print_activation(vframe_no++); 3230 } else { 3231 f->print(); 3232 } 3233 if (vframe_no > StackPrintLimit) { 3234 tty->print_cr("...<more frames>..."); 3235 return; 3236 } 3237 } 3238 } 3239 3240 3241 void JavaThread::trace_stack() { 3242 if (!has_last_Java_frame()) return; 3243 ResourceMark rm; 3244 HandleMark hm; 3245 RegisterMap reg_map(this); 3246 trace_stack_from(last_java_vframe(®_map)); 3247 } 3248 3249 3250 #endif // PRODUCT 3251 3252 3253 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3254 assert(reg_map != NULL, "a map must be given"); 3255 frame f = last_frame(); 3256 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3257 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3258 } 3259 return NULL; 3260 } 3261 3262 3263 Klass* JavaThread::security_get_caller_class(int depth) { 3264 vframeStream vfst(this); 3265 vfst.security_get_caller_frame(depth); 3266 if (!vfst.at_end()) { 3267 return vfst.method()->method_holder(); 3268 } 3269 return NULL; 3270 } 3271 3272 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3273 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3274 CompileBroker::compiler_thread_loop(); 3275 } 3276 3277 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3278 NMethodSweeper::sweeper_loop(); 3279 } 3280 3281 // Create a CompilerThread 3282 CompilerThread::CompilerThread(CompileQueue* queue, 3283 CompilerCounters* counters) 3284 : JavaThread(&compiler_thread_entry) { 3285 _env = NULL; 3286 _log = NULL; 3287 _task = NULL; 3288 _queue = queue; 3289 _counters = counters; 3290 _buffer_blob = NULL; 3291 _compiler = NULL; 3292 3293 #ifndef PRODUCT 3294 _ideal_graph_printer = NULL; 3295 #endif 3296 } 3297 3298 bool CompilerThread::can_call_java() const { 3299 return _compiler != NULL && _compiler->is_jvmci(); 3300 } 3301 3302 // Create sweeper thread 3303 CodeCacheSweeperThread::CodeCacheSweeperThread() 3304 : JavaThread(&sweeper_thread_entry) { 3305 _scanned_compiled_method = NULL; 3306 } 3307 3308 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3309 JavaThread::oops_do(f, cf); 3310 if (_scanned_compiled_method != NULL && cf != NULL) { 3311 // Safepoints can occur when the sweeper is scanning an nmethod so 3312 // process it here to make sure it isn't unloaded in the middle of 3313 // a scan. 3314 cf->do_code_blob(_scanned_compiled_method); 3315 } 3316 } 3317 3318 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3319 JavaThread::nmethods_do(cf); 3320 if (_scanned_compiled_method != NULL && cf != NULL) { 3321 // Safepoints can occur when the sweeper is scanning an nmethod so 3322 // process it here to make sure it isn't unloaded in the middle of 3323 // a scan. 3324 cf->do_code_blob(_scanned_compiled_method); 3325 } 3326 } 3327 3328 3329 // ======= Threads ======== 3330 3331 // The Threads class links together all active threads, and provides 3332 // operations over all threads. It is protected by its own Mutex 3333 // lock, which is also used in other contexts to protect thread 3334 // operations from having the thread being operated on from exiting 3335 // and going away unexpectedly (e.g., safepoint synchronization) 3336 3337 JavaThread* Threads::_thread_list = NULL; 3338 int Threads::_number_of_threads = 0; 3339 int Threads::_number_of_non_daemon_threads = 0; 3340 int Threads::_return_code = 0; 3341 int Threads::_thread_claim_parity = 0; 3342 size_t JavaThread::_stack_size_at_create = 0; 3343 #ifdef ASSERT 3344 bool Threads::_vm_complete = false; 3345 #endif 3346 3347 // All JavaThreads 3348 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3349 3350 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3351 void Threads::threads_do(ThreadClosure* tc) { 3352 assert_locked_or_safepoint(Threads_lock); 3353 // ALL_JAVA_THREADS iterates through all JavaThreads 3354 ALL_JAVA_THREADS(p) { 3355 tc->do_thread(p); 3356 } 3357 // Someday we could have a table or list of all non-JavaThreads. 3358 // For now, just manually iterate through them. 3359 tc->do_thread(VMThread::vm_thread()); 3360 Universe::heap()->gc_threads_do(tc); 3361 WatcherThread *wt = WatcherThread::watcher_thread(); 3362 // Strictly speaking, the following NULL check isn't sufficient to make sure 3363 // the data for WatcherThread is still valid upon being examined. However, 3364 // considering that WatchThread terminates when the VM is on the way to 3365 // exit at safepoint, the chance of the above is extremely small. The right 3366 // way to prevent termination of WatcherThread would be to acquire 3367 // Terminator_lock, but we can't do that without violating the lock rank 3368 // checking in some cases. 3369 if (wt != NULL) { 3370 tc->do_thread(wt); 3371 } 3372 3373 // If CompilerThreads ever become non-JavaThreads, add them here 3374 } 3375 3376 // The system initialization in the library has three phases. 3377 // 3378 // Phase 1: java.lang.System class initialization 3379 // java.lang.System is a primordial class loaded and initialized 3380 // by the VM early during startup. java.lang.System.<clinit> 3381 // only does registerNatives and keeps the rest of the class 3382 // initialization work later until thread initialization completes. 3383 // 3384 // System.initPhase1 initializes the system properties, the static 3385 // fields in, out, and err. Set up java signal handlers, OS-specific 3386 // system settings, and thread group of the main thread. 3387 static void call_initPhase1(TRAPS) { 3388 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3389 instanceKlassHandle klass (THREAD, k); 3390 3391 JavaValue result(T_VOID); 3392 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3393 vmSymbols::void_method_signature(), CHECK); 3394 } 3395 3396 // Phase 2. Module system initialization 3397 // This will initialize the module system. Only java.base classes 3398 // can be loaded until phase 2 completes. 3399 // 3400 // Call System.initPhase2 after the compiler initialization and jsr292 3401 // classes get initialized because module initialization runs a lot of java 3402 // code, that for performance reasons, should be compiled. Also, this will 3403 // enable the startup code to use lambda and other language features in this 3404 // phase and onward. 3405 // 3406 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3407 static void call_initPhase2(TRAPS) { 3408 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, modules, startuptime)); 3409 3410 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3411 instanceKlassHandle klass (THREAD, k); 3412 3413 JavaValue result(T_VOID); 3414 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3415 vmSymbols::void_method_signature(), CHECK); 3416 universe_post_module_init(); 3417 } 3418 3419 // Phase 3. final setup - set security manager, system class loader and TCCL 3420 // 3421 // This will instantiate and set the security manager, set the system class 3422 // loader as well as the thread context class loader. The security manager 3423 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3424 // other modules or the application's classpath. 3425 static void call_initPhase3(TRAPS) { 3426 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3427 instanceKlassHandle klass (THREAD, k); 3428 3429 JavaValue result(T_VOID); 3430 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3431 vmSymbols::void_method_signature(), CHECK); 3432 } 3433 3434 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3435 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3436 3437 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3438 create_vm_init_libraries(); 3439 } 3440 3441 initialize_class(vmSymbols::java_lang_String(), CHECK); 3442 3443 // Inject CompactStrings value after the static initializers for String ran. 3444 java_lang_String::set_compact_strings(CompactStrings); 3445 3446 // Initialize java_lang.System (needed before creating the thread) 3447 initialize_class(vmSymbols::java_lang_System(), CHECK); 3448 // The VM creates & returns objects of this class. Make sure it's initialized. 3449 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3450 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3451 Handle thread_group = create_initial_thread_group(CHECK); 3452 Universe::set_main_thread_group(thread_group()); 3453 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3454 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3455 main_thread->set_threadObj(thread_object); 3456 // Set thread status to running since main thread has 3457 // been started and running. 3458 java_lang_Thread::set_thread_status(thread_object, 3459 java_lang_Thread::RUNNABLE); 3460 3461 // The VM creates objects of this class. 3462 initialize_class(vmSymbols::java_lang_reflect_Module(), CHECK); 3463 3464 // The VM preresolves methods to these classes. Make sure that they get initialized 3465 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3466 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3467 3468 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3469 call_initPhase1(CHECK); 3470 3471 // get the Java runtime name after java.lang.System is initialized 3472 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3473 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3474 3475 // an instance of OutOfMemory exception has been allocated earlier 3476 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3477 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3478 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3479 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3480 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3481 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3482 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3483 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3484 } 3485 3486 void Threads::initialize_jsr292_core_classes(TRAPS) { 3487 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3488 3489 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3490 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3491 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3492 } 3493 3494 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3495 extern void JDK_Version_init(); 3496 3497 // Preinitialize version info. 3498 VM_Version::early_initialize(); 3499 3500 // Check version 3501 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3502 3503 // Initialize library-based TLS 3504 ThreadLocalStorage::init(); 3505 3506 // Initialize the output stream module 3507 ostream_init(); 3508 3509 // Process java launcher properties. 3510 Arguments::process_sun_java_launcher_properties(args); 3511 3512 // Initialize the os module 3513 os::init(); 3514 3515 // Record VM creation timing statistics 3516 TraceVmCreationTime create_vm_timer; 3517 create_vm_timer.start(); 3518 3519 // Initialize system properties. 3520 Arguments::init_system_properties(); 3521 3522 // So that JDK version can be used as a discriminator when parsing arguments 3523 JDK_Version_init(); 3524 3525 // Update/Initialize System properties after JDK version number is known 3526 Arguments::init_version_specific_system_properties(); 3527 3528 // Make sure to initialize log configuration *before* parsing arguments 3529 LogConfiguration::initialize(create_vm_timer.begin_time()); 3530 3531 // Parse arguments 3532 jint parse_result = Arguments::parse(args); 3533 if (parse_result != JNI_OK) return parse_result; 3534 3535 os::init_before_ergo(); 3536 3537 jint ergo_result = Arguments::apply_ergo(); 3538 if (ergo_result != JNI_OK) return ergo_result; 3539 3540 // Final check of all ranges after ergonomics which may change values. 3541 if (!CommandLineFlagRangeList::check_ranges()) { 3542 return JNI_EINVAL; 3543 } 3544 3545 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3546 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3547 if (!constraint_result) { 3548 return JNI_EINVAL; 3549 } 3550 3551 CommandLineFlagWriteableList::mark_startup(); 3552 3553 if (PauseAtStartup) { 3554 os::pause(); 3555 } 3556 3557 HOTSPOT_VM_INIT_BEGIN(); 3558 3559 // Timing (must come after argument parsing) 3560 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3561 3562 // Initialize the os module after parsing the args 3563 jint os_init_2_result = os::init_2(); 3564 if (os_init_2_result != JNI_OK) return os_init_2_result; 3565 3566 jint adjust_after_os_result = Arguments::adjust_after_os(); 3567 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3568 3569 // Initialize output stream logging 3570 ostream_init_log(); 3571 3572 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3573 // Must be before create_vm_init_agents() 3574 if (Arguments::init_libraries_at_startup()) { 3575 convert_vm_init_libraries_to_agents(); 3576 } 3577 3578 // Launch -agentlib/-agentpath and converted -Xrun agents 3579 if (Arguments::init_agents_at_startup()) { 3580 create_vm_init_agents(); 3581 } 3582 3583 // Initialize Threads state 3584 _thread_list = NULL; 3585 _number_of_threads = 0; 3586 _number_of_non_daemon_threads = 0; 3587 3588 // Initialize global data structures and create system classes in heap 3589 vm_init_globals(); 3590 3591 #if INCLUDE_JVMCI 3592 if (JVMCICounterSize > 0) { 3593 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3594 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3595 } else { 3596 JavaThread::_jvmci_old_thread_counters = NULL; 3597 } 3598 #endif // INCLUDE_JVMCI 3599 3600 // Attach the main thread to this os thread 3601 JavaThread* main_thread = new JavaThread(); 3602 main_thread->set_thread_state(_thread_in_vm); 3603 main_thread->initialize_thread_current(); 3604 // must do this before set_active_handles 3605 main_thread->record_stack_base_and_size(); 3606 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3607 3608 if (!main_thread->set_as_starting_thread()) { 3609 vm_shutdown_during_initialization( 3610 "Failed necessary internal allocation. Out of swap space"); 3611 delete main_thread; 3612 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3613 return JNI_ENOMEM; 3614 } 3615 3616 // Enable guard page *after* os::create_main_thread(), otherwise it would 3617 // crash Linux VM, see notes in os_linux.cpp. 3618 main_thread->create_stack_guard_pages(); 3619 3620 // Initialize Java-Level synchronization subsystem 3621 ObjectMonitor::Initialize(); 3622 3623 // Initialize global modules 3624 jint status = init_globals(); 3625 if (status != JNI_OK) { 3626 delete main_thread; 3627 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3628 return status; 3629 } 3630 3631 if (TRACE_INITIALIZE() != JNI_OK) { 3632 vm_exit_during_initialization("Failed to initialize tracing backend"); 3633 } 3634 3635 // Should be done after the heap is fully created 3636 main_thread->cache_global_variables(); 3637 3638 HandleMark hm; 3639 3640 { MutexLocker mu(Threads_lock); 3641 Threads::add(main_thread); 3642 } 3643 3644 // Any JVMTI raw monitors entered in onload will transition into 3645 // real raw monitor. VM is setup enough here for raw monitor enter. 3646 JvmtiExport::transition_pending_onload_raw_monitors(); 3647 3648 // Create the VMThread 3649 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3650 3651 VMThread::create(); 3652 Thread* vmthread = VMThread::vm_thread(); 3653 3654 if (!os::create_thread(vmthread, os::vm_thread)) { 3655 vm_exit_during_initialization("Cannot create VM thread. " 3656 "Out of system resources."); 3657 } 3658 3659 // Wait for the VM thread to become ready, and VMThread::run to initialize 3660 // Monitors can have spurious returns, must always check another state flag 3661 { 3662 MutexLocker ml(Notify_lock); 3663 os::start_thread(vmthread); 3664 while (vmthread->active_handles() == NULL) { 3665 Notify_lock->wait(); 3666 } 3667 } 3668 } 3669 3670 assert(Universe::is_fully_initialized(), "not initialized"); 3671 if (VerifyDuringStartup) { 3672 // Make sure we're starting with a clean slate. 3673 VM_Verify verify_op; 3674 VMThread::execute(&verify_op); 3675 } 3676 3677 Thread* THREAD = Thread::current(); 3678 3679 // At this point, the Universe is initialized, but we have not executed 3680 // any byte code. Now is a good time (the only time) to dump out the 3681 // internal state of the JVM for sharing. 3682 if (DumpSharedSpaces) { 3683 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3684 ShouldNotReachHere(); 3685 } 3686 3687 // Always call even when there are not JVMTI environments yet, since environments 3688 // may be attached late and JVMTI must track phases of VM execution 3689 JvmtiExport::enter_early_start_phase(); 3690 3691 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3692 JvmtiExport::post_early_vm_start(); 3693 3694 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3695 3696 // We need this for ClassDataSharing - the initial vm.info property is set 3697 // with the default value of CDS "sharing" which may be reset through 3698 // command line options. 3699 reset_vm_info_property(CHECK_JNI_ERR); 3700 3701 quicken_jni_functions(); 3702 3703 // No more stub generation allowed after that point. 3704 StubCodeDesc::freeze(); 3705 3706 // Set flag that basic initialization has completed. Used by exceptions and various 3707 // debug stuff, that does not work until all basic classes have been initialized. 3708 set_init_completed(); 3709 3710 LogConfiguration::post_initialize(); 3711 Metaspace::post_initialize(); 3712 3713 HOTSPOT_VM_INIT_END(); 3714 3715 // record VM initialization completion time 3716 #if INCLUDE_MANAGEMENT 3717 Management::record_vm_init_completed(); 3718 #endif // INCLUDE_MANAGEMENT 3719 3720 // Signal Dispatcher needs to be started before VMInit event is posted 3721 os::signal_init(); 3722 3723 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3724 if (!DisableAttachMechanism) { 3725 AttachListener::vm_start(); 3726 if (StartAttachListener || AttachListener::init_at_startup()) { 3727 AttachListener::init(); 3728 } 3729 } 3730 3731 // Launch -Xrun agents 3732 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3733 // back-end can launch with -Xdebug -Xrunjdwp. 3734 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3735 create_vm_init_libraries(); 3736 } 3737 3738 if (CleanChunkPoolAsync) { 3739 Chunk::start_chunk_pool_cleaner_task(); 3740 } 3741 3742 // initialize compiler(s) 3743 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3744 CompileBroker::compilation_init(CHECK_JNI_ERR); 3745 #endif 3746 3747 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3748 // It is done after compilers are initialized, because otherwise compilations of 3749 // signature polymorphic MH intrinsics can be missed 3750 // (see SystemDictionary::find_method_handle_intrinsic). 3751 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3752 3753 // This will initialize the module system. Only java.base classes can be 3754 // loaded until phase 2 completes 3755 call_initPhase2(CHECK_JNI_ERR); 3756 3757 // Always call even when there are not JVMTI environments yet, since environments 3758 // may be attached late and JVMTI must track phases of VM execution 3759 JvmtiExport::enter_start_phase(); 3760 3761 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3762 JvmtiExport::post_vm_start(); 3763 3764 // Final system initialization including security manager and system class loader 3765 call_initPhase3(CHECK_JNI_ERR); 3766 3767 // cache the system class loader 3768 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3769 3770 #if INCLUDE_JVMCI 3771 if (EnableJVMCI) { 3772 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3773 // The JVMCI Java initialization code will read this flag and 3774 // do the printing if it's set. 3775 bool init = JVMCIPrintProperties; 3776 3777 if (!init) { 3778 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3779 // compilations via JVMCI will not actually block until JVMCI is initialized. 3780 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3781 } 3782 3783 if (init) { 3784 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3785 } 3786 } 3787 #endif 3788 3789 // Always call even when there are not JVMTI environments yet, since environments 3790 // may be attached late and JVMTI must track phases of VM execution 3791 JvmtiExport::enter_live_phase(); 3792 3793 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3794 JvmtiExport::post_vm_initialized(); 3795 3796 if (TRACE_START() != JNI_OK) { 3797 vm_exit_during_initialization("Failed to start tracing backend."); 3798 } 3799 3800 #if INCLUDE_MANAGEMENT 3801 Management::initialize(THREAD); 3802 3803 if (HAS_PENDING_EXCEPTION) { 3804 // management agent fails to start possibly due to 3805 // configuration problem and is responsible for printing 3806 // stack trace if appropriate. Simply exit VM. 3807 vm_exit(1); 3808 } 3809 #endif // INCLUDE_MANAGEMENT 3810 3811 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3812 if (MemProfiling) MemProfiler::engage(); 3813 StatSampler::engage(); 3814 if (CheckJNICalls) JniPeriodicChecker::engage(); 3815 3816 BiasedLocking::init(); 3817 3818 #if INCLUDE_RTM_OPT 3819 RTMLockingCounters::init(); 3820 #endif 3821 3822 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3823 call_postVMInitHook(THREAD); 3824 // The Java side of PostVMInitHook.run must deal with all 3825 // exceptions and provide means of diagnosis. 3826 if (HAS_PENDING_EXCEPTION) { 3827 CLEAR_PENDING_EXCEPTION; 3828 } 3829 } 3830 3831 { 3832 MutexLocker ml(PeriodicTask_lock); 3833 // Make sure the WatcherThread can be started by WatcherThread::start() 3834 // or by dynamic enrollment. 3835 WatcherThread::make_startable(); 3836 // Start up the WatcherThread if there are any periodic tasks 3837 // NOTE: All PeriodicTasks should be registered by now. If they 3838 // aren't, late joiners might appear to start slowly (we might 3839 // take a while to process their first tick). 3840 if (PeriodicTask::num_tasks() > 0) { 3841 WatcherThread::start(); 3842 } 3843 } 3844 3845 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM); 3846 3847 create_vm_timer.end(); 3848 #ifdef ASSERT 3849 _vm_complete = true; 3850 #endif 3851 return JNI_OK; 3852 } 3853 3854 // type for the Agent_OnLoad and JVM_OnLoad entry points 3855 extern "C" { 3856 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3857 } 3858 // Find a command line agent library and return its entry point for 3859 // -agentlib: -agentpath: -Xrun 3860 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3861 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3862 const char *on_load_symbols[], 3863 size_t num_symbol_entries) { 3864 OnLoadEntry_t on_load_entry = NULL; 3865 void *library = NULL; 3866 3867 if (!agent->valid()) { 3868 char buffer[JVM_MAXPATHLEN]; 3869 char ebuf[1024] = ""; 3870 const char *name = agent->name(); 3871 const char *msg = "Could not find agent library "; 3872 3873 // First check to see if agent is statically linked into executable 3874 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3875 library = agent->os_lib(); 3876 } else if (agent->is_absolute_path()) { 3877 library = os::dll_load(name, ebuf, sizeof ebuf); 3878 if (library == NULL) { 3879 const char *sub_msg = " in absolute path, with error: "; 3880 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3881 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3882 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3883 // If we can't find the agent, exit. 3884 vm_exit_during_initialization(buf, NULL); 3885 FREE_C_HEAP_ARRAY(char, buf); 3886 } 3887 } else { 3888 // Try to load the agent from the standard dll directory 3889 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3890 name)) { 3891 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3892 } 3893 if (library == NULL) { // Try the local directory 3894 char ns[1] = {0}; 3895 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3896 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3897 } 3898 if (library == NULL) { 3899 const char *sub_msg = " on the library path, with error: "; 3900 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3901 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3902 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3903 // If we can't find the agent, exit. 3904 vm_exit_during_initialization(buf, NULL); 3905 FREE_C_HEAP_ARRAY(char, buf); 3906 } 3907 } 3908 } 3909 agent->set_os_lib(library); 3910 agent->set_valid(); 3911 } 3912 3913 // Find the OnLoad function. 3914 on_load_entry = 3915 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3916 false, 3917 on_load_symbols, 3918 num_symbol_entries)); 3919 return on_load_entry; 3920 } 3921 3922 // Find the JVM_OnLoad entry point 3923 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3924 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3925 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3926 } 3927 3928 // Find the Agent_OnLoad entry point 3929 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3930 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3931 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3932 } 3933 3934 // For backwards compatibility with -Xrun 3935 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3936 // treated like -agentpath: 3937 // Must be called before agent libraries are created 3938 void Threads::convert_vm_init_libraries_to_agents() { 3939 AgentLibrary* agent; 3940 AgentLibrary* next; 3941 3942 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3943 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3944 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3945 3946 // If there is an JVM_OnLoad function it will get called later, 3947 // otherwise see if there is an Agent_OnLoad 3948 if (on_load_entry == NULL) { 3949 on_load_entry = lookup_agent_on_load(agent); 3950 if (on_load_entry != NULL) { 3951 // switch it to the agent list -- so that Agent_OnLoad will be called, 3952 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3953 Arguments::convert_library_to_agent(agent); 3954 } else { 3955 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3956 } 3957 } 3958 } 3959 } 3960 3961 // Create agents for -agentlib: -agentpath: and converted -Xrun 3962 // Invokes Agent_OnLoad 3963 // Called very early -- before JavaThreads exist 3964 void Threads::create_vm_init_agents() { 3965 extern struct JavaVM_ main_vm; 3966 AgentLibrary* agent; 3967 3968 JvmtiExport::enter_onload_phase(); 3969 3970 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3971 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3972 3973 if (on_load_entry != NULL) { 3974 // Invoke the Agent_OnLoad function 3975 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3976 if (err != JNI_OK) { 3977 vm_exit_during_initialization("agent library failed to init", agent->name()); 3978 } 3979 } else { 3980 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3981 } 3982 } 3983 JvmtiExport::enter_primordial_phase(); 3984 } 3985 3986 extern "C" { 3987 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3988 } 3989 3990 void Threads::shutdown_vm_agents() { 3991 // Send any Agent_OnUnload notifications 3992 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3993 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3994 extern struct JavaVM_ main_vm; 3995 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3996 3997 // Find the Agent_OnUnload function. 3998 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3999 os::find_agent_function(agent, 4000 false, 4001 on_unload_symbols, 4002 num_symbol_entries)); 4003 4004 // Invoke the Agent_OnUnload function 4005 if (unload_entry != NULL) { 4006 JavaThread* thread = JavaThread::current(); 4007 ThreadToNativeFromVM ttn(thread); 4008 HandleMark hm(thread); 4009 (*unload_entry)(&main_vm); 4010 } 4011 } 4012 } 4013 4014 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4015 // Invokes JVM_OnLoad 4016 void Threads::create_vm_init_libraries() { 4017 extern struct JavaVM_ main_vm; 4018 AgentLibrary* agent; 4019 4020 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4021 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4022 4023 if (on_load_entry != NULL) { 4024 // Invoke the JVM_OnLoad function 4025 JavaThread* thread = JavaThread::current(); 4026 ThreadToNativeFromVM ttn(thread); 4027 HandleMark hm(thread); 4028 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4029 if (err != JNI_OK) { 4030 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4031 } 4032 } else { 4033 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4034 } 4035 } 4036 } 4037 4038 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4039 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4040 4041 JavaThread* java_thread = NULL; 4042 // Sequential search for now. Need to do better optimization later. 4043 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4044 oop tobj = thread->threadObj(); 4045 if (!thread->is_exiting() && 4046 tobj != NULL && 4047 java_tid == java_lang_Thread::thread_id(tobj)) { 4048 java_thread = thread; 4049 break; 4050 } 4051 } 4052 return java_thread; 4053 } 4054 4055 4056 // Last thread running calls java.lang.Shutdown.shutdown() 4057 void JavaThread::invoke_shutdown_hooks() { 4058 HandleMark hm(this); 4059 4060 // We could get here with a pending exception, if so clear it now. 4061 if (this->has_pending_exception()) { 4062 this->clear_pending_exception(); 4063 } 4064 4065 EXCEPTION_MARK; 4066 Klass* k = 4067 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4068 THREAD); 4069 if (k != NULL) { 4070 // SystemDictionary::resolve_or_null will return null if there was 4071 // an exception. If we cannot load the Shutdown class, just don't 4072 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4073 // and finalizers (if runFinalizersOnExit is set) won't be run. 4074 // Note that if a shutdown hook was registered or runFinalizersOnExit 4075 // was called, the Shutdown class would have already been loaded 4076 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4077 instanceKlassHandle shutdown_klass (THREAD, k); 4078 JavaValue result(T_VOID); 4079 JavaCalls::call_static(&result, 4080 shutdown_klass, 4081 vmSymbols::shutdown_method_name(), 4082 vmSymbols::void_method_signature(), 4083 THREAD); 4084 } 4085 CLEAR_PENDING_EXCEPTION; 4086 } 4087 4088 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4089 // the program falls off the end of main(). Another VM exit path is through 4090 // vm_exit() when the program calls System.exit() to return a value or when 4091 // there is a serious error in VM. The two shutdown paths are not exactly 4092 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4093 // and VM_Exit op at VM level. 4094 // 4095 // Shutdown sequence: 4096 // + Shutdown native memory tracking if it is on 4097 // + Wait until we are the last non-daemon thread to execute 4098 // <-- every thing is still working at this moment --> 4099 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4100 // shutdown hooks, run finalizers if finalization-on-exit 4101 // + Call before_exit(), prepare for VM exit 4102 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4103 // currently the only user of this mechanism is File.deleteOnExit()) 4104 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4105 // post thread end and vm death events to JVMTI, 4106 // stop signal thread 4107 // + Call JavaThread::exit(), it will: 4108 // > release JNI handle blocks, remove stack guard pages 4109 // > remove this thread from Threads list 4110 // <-- no more Java code from this thread after this point --> 4111 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4112 // the compiler threads at safepoint 4113 // <-- do not use anything that could get blocked by Safepoint --> 4114 // + Disable tracing at JNI/JVM barriers 4115 // + Set _vm_exited flag for threads that are still running native code 4116 // + Delete this thread 4117 // + Call exit_globals() 4118 // > deletes tty 4119 // > deletes PerfMemory resources 4120 // + Return to caller 4121 4122 bool Threads::destroy_vm() { 4123 JavaThread* thread = JavaThread::current(); 4124 4125 #ifdef ASSERT 4126 _vm_complete = false; 4127 #endif 4128 // Wait until we are the last non-daemon thread to execute 4129 { MutexLocker nu(Threads_lock); 4130 while (Threads::number_of_non_daemon_threads() > 1) 4131 // This wait should make safepoint checks, wait without a timeout, 4132 // and wait as a suspend-equivalent condition. 4133 // 4134 // Note: If the FlatProfiler is running and this thread is waiting 4135 // for another non-daemon thread to finish, then the FlatProfiler 4136 // is waiting for the external suspend request on this thread to 4137 // complete. wait_for_ext_suspend_completion() will eventually 4138 // timeout, but that takes time. Making this wait a suspend- 4139 // equivalent condition solves that timeout problem. 4140 // 4141 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4142 Mutex::_as_suspend_equivalent_flag); 4143 } 4144 4145 // Hang forever on exit if we are reporting an error. 4146 if (ShowMessageBoxOnError && is_error_reported()) { 4147 os::infinite_sleep(); 4148 } 4149 os::wait_for_keypress_at_exit(); 4150 4151 // run Java level shutdown hooks 4152 thread->invoke_shutdown_hooks(); 4153 4154 before_exit(thread); 4155 4156 thread->exit(true); 4157 4158 // Stop VM thread. 4159 { 4160 // 4945125 The vm thread comes to a safepoint during exit. 4161 // GC vm_operations can get caught at the safepoint, and the 4162 // heap is unparseable if they are caught. Grab the Heap_lock 4163 // to prevent this. The GC vm_operations will not be able to 4164 // queue until after the vm thread is dead. After this point, 4165 // we'll never emerge out of the safepoint before the VM exits. 4166 4167 MutexLocker ml(Heap_lock); 4168 4169 VMThread::wait_for_vm_thread_exit(); 4170 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4171 VMThread::destroy(); 4172 } 4173 4174 // clean up ideal graph printers 4175 #if defined(COMPILER2) && !defined(PRODUCT) 4176 IdealGraphPrinter::clean_up(); 4177 #endif 4178 4179 // Now, all Java threads are gone except daemon threads. Daemon threads 4180 // running Java code or in VM are stopped by the Safepoint. However, 4181 // daemon threads executing native code are still running. But they 4182 // will be stopped at native=>Java/VM barriers. Note that we can't 4183 // simply kill or suspend them, as it is inherently deadlock-prone. 4184 4185 VM_Exit::set_vm_exited(); 4186 4187 notify_vm_shutdown(); 4188 4189 delete thread; 4190 4191 #if INCLUDE_JVMCI 4192 if (JVMCICounterSize > 0) { 4193 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4194 } 4195 #endif 4196 4197 // exit_globals() will delete tty 4198 exit_globals(); 4199 4200 LogConfiguration::finalize(); 4201 4202 return true; 4203 } 4204 4205 4206 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4207 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4208 return is_supported_jni_version(version); 4209 } 4210 4211 4212 jboolean Threads::is_supported_jni_version(jint version) { 4213 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4214 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4215 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4216 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4217 if (version == JNI_VERSION_9) return JNI_TRUE; 4218 return JNI_FALSE; 4219 } 4220 4221 4222 void Threads::add(JavaThread* p, bool force_daemon) { 4223 // The threads lock must be owned at this point 4224 assert_locked_or_safepoint(Threads_lock); 4225 4226 // See the comment for this method in thread.hpp for its purpose and 4227 // why it is called here. 4228 p->initialize_queues(); 4229 p->set_next(_thread_list); 4230 _thread_list = p; 4231 _number_of_threads++; 4232 oop threadObj = p->threadObj(); 4233 bool daemon = true; 4234 // Bootstrapping problem: threadObj can be null for initial 4235 // JavaThread (or for threads attached via JNI) 4236 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4237 _number_of_non_daemon_threads++; 4238 daemon = false; 4239 } 4240 4241 ThreadService::add_thread(p, daemon); 4242 4243 // Possible GC point. 4244 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4245 } 4246 4247 void Threads::remove(JavaThread* p) { 4248 // Extra scope needed for Thread_lock, so we can check 4249 // that we do not remove thread without safepoint code notice 4250 { MutexLocker ml(Threads_lock); 4251 4252 assert(includes(p), "p must be present"); 4253 4254 JavaThread* current = _thread_list; 4255 JavaThread* prev = NULL; 4256 4257 while (current != p) { 4258 prev = current; 4259 current = current->next(); 4260 } 4261 4262 if (prev) { 4263 prev->set_next(current->next()); 4264 } else { 4265 _thread_list = p->next(); 4266 } 4267 _number_of_threads--; 4268 oop threadObj = p->threadObj(); 4269 bool daemon = true; 4270 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4271 _number_of_non_daemon_threads--; 4272 daemon = false; 4273 4274 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4275 // on destroy_vm will wake up. 4276 if (number_of_non_daemon_threads() == 1) { 4277 Threads_lock->notify_all(); 4278 } 4279 } 4280 ThreadService::remove_thread(p, daemon); 4281 4282 // Make sure that safepoint code disregard this thread. This is needed since 4283 // the thread might mess around with locks after this point. This can cause it 4284 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4285 // of this thread since it is removed from the queue. 4286 p->set_terminated_value(); 4287 } // unlock Threads_lock 4288 4289 // Since Events::log uses a lock, we grab it outside the Threads_lock 4290 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4291 } 4292 4293 // Threads_lock must be held when this is called (or must be called during a safepoint) 4294 bool Threads::includes(JavaThread* p) { 4295 assert(Threads_lock->is_locked(), "sanity check"); 4296 ALL_JAVA_THREADS(q) { 4297 if (q == p) { 4298 return true; 4299 } 4300 } 4301 return false; 4302 } 4303 4304 // Operations on the Threads list for GC. These are not explicitly locked, 4305 // but the garbage collector must provide a safe context for them to run. 4306 // In particular, these things should never be called when the Threads_lock 4307 // is held by some other thread. (Note: the Safepoint abstraction also 4308 // uses the Threads_lock to guarantee this property. It also makes sure that 4309 // all threads gets blocked when exiting or starting). 4310 4311 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4312 ALL_JAVA_THREADS(p) { 4313 p->oops_do(f, cf); 4314 } 4315 VMThread::vm_thread()->oops_do(f, cf); 4316 } 4317 4318 void Threads::change_thread_claim_parity() { 4319 // Set the new claim parity. 4320 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4321 "Not in range."); 4322 _thread_claim_parity++; 4323 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4324 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4325 "Not in range."); 4326 } 4327 4328 #ifdef ASSERT 4329 void Threads::assert_all_threads_claimed() { 4330 ALL_JAVA_THREADS(p) { 4331 const int thread_parity = p->oops_do_parity(); 4332 assert((thread_parity == _thread_claim_parity), 4333 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4334 } 4335 } 4336 #endif // ASSERT 4337 4338 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4339 int cp = Threads::thread_claim_parity(); 4340 ALL_JAVA_THREADS(p) { 4341 if (p->claim_oops_do(is_par, cp)) { 4342 p->oops_do(f, cf); 4343 } 4344 } 4345 VMThread* vmt = VMThread::vm_thread(); 4346 if (vmt->claim_oops_do(is_par, cp)) { 4347 vmt->oops_do(f, cf); 4348 } 4349 } 4350 4351 #if INCLUDE_ALL_GCS 4352 // Used by ParallelScavenge 4353 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4354 ALL_JAVA_THREADS(p) { 4355 q->enqueue(new ThreadRootsTask(p)); 4356 } 4357 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4358 } 4359 4360 // Used by Parallel Old 4361 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4362 ALL_JAVA_THREADS(p) { 4363 q->enqueue(new ThreadRootsMarkingTask(p)); 4364 } 4365 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4366 } 4367 #endif // INCLUDE_ALL_GCS 4368 4369 void Threads::nmethods_do(CodeBlobClosure* cf) { 4370 ALL_JAVA_THREADS(p) { 4371 // This is used by the code cache sweeper to mark nmethods that are active 4372 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4373 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4374 if(!p->is_Code_cache_sweeper_thread()) { 4375 p->nmethods_do(cf); 4376 } 4377 } 4378 } 4379 4380 void Threads::metadata_do(void f(Metadata*)) { 4381 ALL_JAVA_THREADS(p) { 4382 p->metadata_do(f); 4383 } 4384 } 4385 4386 class ThreadHandlesClosure : public ThreadClosure { 4387 void (*_f)(Metadata*); 4388 public: 4389 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4390 virtual void do_thread(Thread* thread) { 4391 thread->metadata_handles_do(_f); 4392 } 4393 }; 4394 4395 void Threads::metadata_handles_do(void f(Metadata*)) { 4396 // Only walk the Handles in Thread. 4397 ThreadHandlesClosure handles_closure(f); 4398 threads_do(&handles_closure); 4399 } 4400 4401 void Threads::deoptimized_wrt_marked_nmethods() { 4402 ALL_JAVA_THREADS(p) { 4403 p->deoptimized_wrt_marked_nmethods(); 4404 } 4405 } 4406 4407 4408 // Get count Java threads that are waiting to enter the specified monitor. 4409 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4410 address monitor, 4411 bool doLock) { 4412 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4413 "must grab Threads_lock or be at safepoint"); 4414 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4415 4416 int i = 0; 4417 { 4418 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4419 ALL_JAVA_THREADS(p) { 4420 if (!p->can_call_java()) continue; 4421 4422 address pending = (address)p->current_pending_monitor(); 4423 if (pending == monitor) { // found a match 4424 if (i < count) result->append(p); // save the first count matches 4425 i++; 4426 } 4427 } 4428 } 4429 return result; 4430 } 4431 4432 4433 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4434 bool doLock) { 4435 assert(doLock || 4436 Threads_lock->owned_by_self() || 4437 SafepointSynchronize::is_at_safepoint(), 4438 "must grab Threads_lock or be at safepoint"); 4439 4440 // NULL owner means not locked so we can skip the search 4441 if (owner == NULL) return NULL; 4442 4443 { 4444 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4445 ALL_JAVA_THREADS(p) { 4446 // first, see if owner is the address of a Java thread 4447 if (owner == (address)p) return p; 4448 } 4449 } 4450 // Cannot assert on lack of success here since this function may be 4451 // used by code that is trying to report useful problem information 4452 // like deadlock detection. 4453 if (UseHeavyMonitors) return NULL; 4454 4455 // If we didn't find a matching Java thread and we didn't force use of 4456 // heavyweight monitors, then the owner is the stack address of the 4457 // Lock Word in the owning Java thread's stack. 4458 // 4459 JavaThread* the_owner = NULL; 4460 { 4461 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4462 ALL_JAVA_THREADS(q) { 4463 if (q->is_lock_owned(owner)) { 4464 the_owner = q; 4465 break; 4466 } 4467 } 4468 } 4469 // cannot assert on lack of success here; see above comment 4470 return the_owner; 4471 } 4472 4473 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4474 void Threads::print_on(outputStream* st, bool print_stacks, 4475 bool internal_format, bool print_concurrent_locks) { 4476 char buf[32]; 4477 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4478 4479 st->print_cr("Full thread dump %s (%s %s):", 4480 Abstract_VM_Version::vm_name(), 4481 Abstract_VM_Version::vm_release(), 4482 Abstract_VM_Version::vm_info_string()); 4483 st->cr(); 4484 4485 #if INCLUDE_SERVICES 4486 // Dump concurrent locks 4487 ConcurrentLocksDump concurrent_locks; 4488 if (print_concurrent_locks) { 4489 concurrent_locks.dump_at_safepoint(); 4490 } 4491 #endif // INCLUDE_SERVICES 4492 4493 ALL_JAVA_THREADS(p) { 4494 ResourceMark rm; 4495 p->print_on(st); 4496 if (print_stacks) { 4497 if (internal_format) { 4498 p->trace_stack(); 4499 } else { 4500 p->print_stack_on(st); 4501 } 4502 } 4503 st->cr(); 4504 #if INCLUDE_SERVICES 4505 if (print_concurrent_locks) { 4506 concurrent_locks.print_locks_on(p, st); 4507 } 4508 #endif // INCLUDE_SERVICES 4509 } 4510 4511 VMThread::vm_thread()->print_on(st); 4512 st->cr(); 4513 Universe::heap()->print_gc_threads_on(st); 4514 WatcherThread* wt = WatcherThread::watcher_thread(); 4515 if (wt != NULL) { 4516 wt->print_on(st); 4517 st->cr(); 4518 } 4519 st->flush(); 4520 } 4521 4522 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4523 int buflen, bool* found_current) { 4524 if (this_thread != NULL) { 4525 bool is_current = (current == this_thread); 4526 *found_current = *found_current || is_current; 4527 st->print("%s", is_current ? "=>" : " "); 4528 4529 st->print(PTR_FORMAT, p2i(this_thread)); 4530 st->print(" "); 4531 this_thread->print_on_error(st, buf, buflen); 4532 st->cr(); 4533 } 4534 } 4535 4536 class PrintOnErrorClosure : public ThreadClosure { 4537 outputStream* _st; 4538 Thread* _current; 4539 char* _buf; 4540 int _buflen; 4541 bool* _found_current; 4542 public: 4543 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4544 int buflen, bool* found_current) : 4545 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4546 4547 virtual void do_thread(Thread* thread) { 4548 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4549 } 4550 }; 4551 4552 // Threads::print_on_error() is called by fatal error handler. It's possible 4553 // that VM is not at safepoint and/or current thread is inside signal handler. 4554 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4555 // memory (even in resource area), it might deadlock the error handler. 4556 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4557 int buflen) { 4558 bool found_current = false; 4559 st->print_cr("Java Threads: ( => current thread )"); 4560 ALL_JAVA_THREADS(thread) { 4561 print_on_error(thread, st, current, buf, buflen, &found_current); 4562 } 4563 st->cr(); 4564 4565 st->print_cr("Other Threads:"); 4566 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4567 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4568 4569 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4570 Universe::heap()->gc_threads_do(&print_closure); 4571 4572 if (!found_current) { 4573 st->cr(); 4574 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4575 current->print_on_error(st, buf, buflen); 4576 st->cr(); 4577 } 4578 st->cr(); 4579 st->print_cr("Threads with active compile tasks:"); 4580 print_threads_compiling(st, buf, buflen); 4581 } 4582 4583 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4584 ALL_JAVA_THREADS(thread) { 4585 if (thread->is_Compiler_thread()) { 4586 CompilerThread* ct = (CompilerThread*) thread; 4587 if (ct->task() != NULL) { 4588 thread->print_name_on_error(st, buf, buflen); 4589 ct->task()->print(st, NULL, true, true); 4590 } 4591 } 4592 } 4593 } 4594 4595 4596 // Internal SpinLock and Mutex 4597 // Based on ParkEvent 4598 4599 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4600 // 4601 // We employ SpinLocks _only for low-contention, fixed-length 4602 // short-duration critical sections where we're concerned 4603 // about native mutex_t or HotSpot Mutex:: latency. 4604 // The mux construct provides a spin-then-block mutual exclusion 4605 // mechanism. 4606 // 4607 // Testing has shown that contention on the ListLock guarding gFreeList 4608 // is common. If we implement ListLock as a simple SpinLock it's common 4609 // for the JVM to devolve to yielding with little progress. This is true 4610 // despite the fact that the critical sections protected by ListLock are 4611 // extremely short. 4612 // 4613 // TODO-FIXME: ListLock should be of type SpinLock. 4614 // We should make this a 1st-class type, integrated into the lock 4615 // hierarchy as leaf-locks. Critically, the SpinLock structure 4616 // should have sufficient padding to avoid false-sharing and excessive 4617 // cache-coherency traffic. 4618 4619 4620 typedef volatile int SpinLockT; 4621 4622 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4623 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4624 return; // normal fast-path return 4625 } 4626 4627 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4628 TEVENT(SpinAcquire - ctx); 4629 int ctr = 0; 4630 int Yields = 0; 4631 for (;;) { 4632 while (*adr != 0) { 4633 ++ctr; 4634 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4635 if (Yields > 5) { 4636 os::naked_short_sleep(1); 4637 } else { 4638 os::naked_yield(); 4639 ++Yields; 4640 } 4641 } else { 4642 SpinPause(); 4643 } 4644 } 4645 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4646 } 4647 } 4648 4649 void Thread::SpinRelease(volatile int * adr) { 4650 assert(*adr != 0, "invariant"); 4651 OrderAccess::fence(); // guarantee at least release consistency. 4652 // Roach-motel semantics. 4653 // It's safe if subsequent LDs and STs float "up" into the critical section, 4654 // but prior LDs and STs within the critical section can't be allowed 4655 // to reorder or float past the ST that releases the lock. 4656 // Loads and stores in the critical section - which appear in program 4657 // order before the store that releases the lock - must also appear 4658 // before the store that releases the lock in memory visibility order. 4659 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4660 // the ST of 0 into the lock-word which releases the lock, so fence 4661 // more than covers this on all platforms. 4662 *adr = 0; 4663 } 4664 4665 // muxAcquire and muxRelease: 4666 // 4667 // * muxAcquire and muxRelease support a single-word lock-word construct. 4668 // The LSB of the word is set IFF the lock is held. 4669 // The remainder of the word points to the head of a singly-linked list 4670 // of threads blocked on the lock. 4671 // 4672 // * The current implementation of muxAcquire-muxRelease uses its own 4673 // dedicated Thread._MuxEvent instance. If we're interested in 4674 // minimizing the peak number of extant ParkEvent instances then 4675 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4676 // as certain invariants were satisfied. Specifically, care would need 4677 // to be taken with regards to consuming unpark() "permits". 4678 // A safe rule of thumb is that a thread would never call muxAcquire() 4679 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4680 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4681 // consume an unpark() permit intended for monitorenter, for instance. 4682 // One way around this would be to widen the restricted-range semaphore 4683 // implemented in park(). Another alternative would be to provide 4684 // multiple instances of the PlatformEvent() for each thread. One 4685 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4686 // 4687 // * Usage: 4688 // -- Only as leaf locks 4689 // -- for short-term locking only as muxAcquire does not perform 4690 // thread state transitions. 4691 // 4692 // Alternatives: 4693 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4694 // but with parking or spin-then-park instead of pure spinning. 4695 // * Use Taura-Oyama-Yonenzawa locks. 4696 // * It's possible to construct a 1-0 lock if we encode the lockword as 4697 // (List,LockByte). Acquire will CAS the full lockword while Release 4698 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4699 // acquiring threads use timers (ParkTimed) to detect and recover from 4700 // the stranding window. Thread/Node structures must be aligned on 256-byte 4701 // boundaries by using placement-new. 4702 // * Augment MCS with advisory back-link fields maintained with CAS(). 4703 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4704 // The validity of the backlinks must be ratified before we trust the value. 4705 // If the backlinks are invalid the exiting thread must back-track through the 4706 // the forward links, which are always trustworthy. 4707 // * Add a successor indication. The LockWord is currently encoded as 4708 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4709 // to provide the usual futile-wakeup optimization. 4710 // See RTStt for details. 4711 // * Consider schedctl.sc_nopreempt to cover the critical section. 4712 // 4713 4714 4715 typedef volatile intptr_t MutexT; // Mux Lock-word 4716 enum MuxBits { LOCKBIT = 1 }; 4717 4718 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4719 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4720 if (w == 0) return; 4721 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4722 return; 4723 } 4724 4725 TEVENT(muxAcquire - Contention); 4726 ParkEvent * const Self = Thread::current()->_MuxEvent; 4727 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4728 for (;;) { 4729 int its = (os::is_MP() ? 100 : 0) + 1; 4730 4731 // Optional spin phase: spin-then-park strategy 4732 while (--its >= 0) { 4733 w = *Lock; 4734 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4735 return; 4736 } 4737 } 4738 4739 Self->reset(); 4740 Self->OnList = intptr_t(Lock); 4741 // The following fence() isn't _strictly necessary as the subsequent 4742 // CAS() both serializes execution and ratifies the fetched *Lock value. 4743 OrderAccess::fence(); 4744 for (;;) { 4745 w = *Lock; 4746 if ((w & LOCKBIT) == 0) { 4747 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4748 Self->OnList = 0; // hygiene - allows stronger asserts 4749 return; 4750 } 4751 continue; // Interference -- *Lock changed -- Just retry 4752 } 4753 assert(w & LOCKBIT, "invariant"); 4754 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4755 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4756 } 4757 4758 while (Self->OnList != 0) { 4759 Self->park(); 4760 } 4761 } 4762 } 4763 4764 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4765 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4766 if (w == 0) return; 4767 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4768 return; 4769 } 4770 4771 TEVENT(muxAcquire - Contention); 4772 ParkEvent * ReleaseAfter = NULL; 4773 if (ev == NULL) { 4774 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4775 } 4776 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4777 for (;;) { 4778 guarantee(ev->OnList == 0, "invariant"); 4779 int its = (os::is_MP() ? 100 : 0) + 1; 4780 4781 // Optional spin phase: spin-then-park strategy 4782 while (--its >= 0) { 4783 w = *Lock; 4784 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4785 if (ReleaseAfter != NULL) { 4786 ParkEvent::Release(ReleaseAfter); 4787 } 4788 return; 4789 } 4790 } 4791 4792 ev->reset(); 4793 ev->OnList = intptr_t(Lock); 4794 // The following fence() isn't _strictly necessary as the subsequent 4795 // CAS() both serializes execution and ratifies the fetched *Lock value. 4796 OrderAccess::fence(); 4797 for (;;) { 4798 w = *Lock; 4799 if ((w & LOCKBIT) == 0) { 4800 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4801 ev->OnList = 0; 4802 // We call ::Release while holding the outer lock, thus 4803 // artificially lengthening the critical section. 4804 // Consider deferring the ::Release() until the subsequent unlock(), 4805 // after we've dropped the outer lock. 4806 if (ReleaseAfter != NULL) { 4807 ParkEvent::Release(ReleaseAfter); 4808 } 4809 return; 4810 } 4811 continue; // Interference -- *Lock changed -- Just retry 4812 } 4813 assert(w & LOCKBIT, "invariant"); 4814 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4815 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4816 } 4817 4818 while (ev->OnList != 0) { 4819 ev->park(); 4820 } 4821 } 4822 } 4823 4824 // Release() must extract a successor from the list and then wake that thread. 4825 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4826 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4827 // Release() would : 4828 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4829 // (B) Extract a successor from the private list "in-hand" 4830 // (C) attempt to CAS() the residual back into *Lock over null. 4831 // If there were any newly arrived threads and the CAS() would fail. 4832 // In that case Release() would detach the RATs, re-merge the list in-hand 4833 // with the RATs and repeat as needed. Alternately, Release() might 4834 // detach and extract a successor, but then pass the residual list to the wakee. 4835 // The wakee would be responsible for reattaching and remerging before it 4836 // competed for the lock. 4837 // 4838 // Both "pop" and DMR are immune from ABA corruption -- there can be 4839 // multiple concurrent pushers, but only one popper or detacher. 4840 // This implementation pops from the head of the list. This is unfair, 4841 // but tends to provide excellent throughput as hot threads remain hot. 4842 // (We wake recently run threads first). 4843 // 4844 // All paths through muxRelease() will execute a CAS. 4845 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4846 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4847 // executed within the critical section are complete and globally visible before the 4848 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4849 void Thread::muxRelease(volatile intptr_t * Lock) { 4850 for (;;) { 4851 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4852 assert(w & LOCKBIT, "invariant"); 4853 if (w == LOCKBIT) return; 4854 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4855 assert(List != NULL, "invariant"); 4856 assert(List->OnList == intptr_t(Lock), "invariant"); 4857 ParkEvent * const nxt = List->ListNext; 4858 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4859 4860 // The following CAS() releases the lock and pops the head element. 4861 // The CAS() also ratifies the previously fetched lock-word value. 4862 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4863 continue; 4864 } 4865 List->OnList = 0; 4866 OrderAccess::fence(); 4867 List->unpark(); 4868 return; 4869 } 4870 } 4871 4872 4873 void Threads::verify() { 4874 ALL_JAVA_THREADS(p) { 4875 p->verify(); 4876 } 4877 VMThread* thread = VMThread::vm_thread(); 4878 if (thread != NULL) thread->verify(); 4879 }