1 /* 2 * Copyright (c) 1997, 2017, 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/scopeDesc.hpp" 33 #include "compiler/compileBroker.hpp" 34 #include "compiler/compileTask.hpp" 35 #include "gc/shared/gcId.hpp" 36 #include "gc/shared/gcLocker.inline.hpp" 37 #include "gc/shared/workgroup.hpp" 38 #include "interpreter/interpreter.hpp" 39 #include "interpreter/linkResolver.hpp" 40 #include "interpreter/oopMapCache.hpp" 41 #include "jvmtifiles/jvmtiEnv.hpp" 42 #include "logging/log.hpp" 43 #include "logging/logConfiguration.hpp" 44 #include "memory/metaspaceShared.hpp" 45 #include "memory/oopFactory.hpp" 46 #include "memory/resourceArea.hpp" 47 #include "memory/universe.inline.hpp" 48 #include "oops/instanceKlass.hpp" 49 #include "oops/objArrayOop.hpp" 50 #include "oops/oop.inline.hpp" 51 #include "oops/symbol.hpp" 52 #include "oops/verifyOopClosure.hpp" 53 #include "prims/jvm_misc.hpp" 54 #include "prims/jvmtiExport.hpp" 55 #include "prims/jvmtiThreadState.hpp" 56 #include "prims/privilegedStack.hpp" 57 #include "runtime/arguments.hpp" 58 #include "runtime/atomic.hpp" 59 #include "runtime/biasedLocking.hpp" 60 #include "runtime/commandLineFlagConstraintList.hpp" 61 #include "runtime/commandLineFlagWriteableList.hpp" 62 #include "runtime/commandLineFlagRangeList.hpp" 63 #include "runtime/deoptimization.hpp" 64 #include "runtime/fprofiler.hpp" 65 #include "runtime/frame.inline.hpp" 66 #include "runtime/globals.hpp" 67 #include "runtime/init.hpp" 68 #include "runtime/interfaceSupport.hpp" 69 #include "runtime/java.hpp" 70 #include "runtime/javaCalls.hpp" 71 #include "runtime/jniPeriodicChecker.hpp" 72 #include "runtime/timerTrace.hpp" 73 #include "runtime/memprofiler.hpp" 74 #include "runtime/mutexLocker.hpp" 75 #include "runtime/objectMonitor.hpp" 76 #include "runtime/orderAccess.inline.hpp" 77 #include "runtime/osThread.hpp" 78 #include "runtime/safepoint.hpp" 79 #include "runtime/sharedRuntime.hpp" 80 #include "runtime/statSampler.hpp" 81 #include "runtime/stubRoutines.hpp" 82 #include "runtime/sweeper.hpp" 83 #include "runtime/task.hpp" 84 #include "runtime/thread.inline.hpp" 85 #include "runtime/threadCritical.hpp" 86 #include "runtime/vframe.hpp" 87 #include "runtime/vframeArray.hpp" 88 #include "runtime/vframe_hp.hpp" 89 #include "runtime/vmThread.hpp" 90 #include "runtime/vm_operations.hpp" 91 #include "runtime/vm_version.hpp" 92 #include "services/attachListener.hpp" 93 #include "services/management.hpp" 94 #include "services/memTracker.hpp" 95 #include "services/threadService.hpp" 96 #include "trace/traceMacros.hpp" 97 #include "trace/tracing.hpp" 98 #include "utilities/defaultStream.hpp" 99 #include "utilities/dtrace.hpp" 100 #include "utilities/events.hpp" 101 #include "utilities/macros.hpp" 102 #include "utilities/preserveException.hpp" 103 #if INCLUDE_ALL_GCS 104 #include "gc/cms/concurrentMarkSweepThread.hpp" 105 #include "gc/g1/concurrentMarkThread.inline.hpp" 106 #include "gc/parallel/pcTasks.hpp" 107 #endif // INCLUDE_ALL_GCS 108 #if INCLUDE_JVMCI 109 #include "jvmci/jvmciCompiler.hpp" 110 #include "jvmci/jvmciRuntime.hpp" 111 #endif 112 #ifdef COMPILER1 113 #include "c1/c1_Compiler.hpp" 114 #endif 115 #ifdef COMPILER2 116 #include "opto/c2compiler.hpp" 117 #include "opto/idealGraphPrinter.hpp" 118 #endif 119 #if INCLUDE_RTM_OPT 120 #include "runtime/rtmLocking.hpp" 121 #endif 122 123 // Initialization after module runtime initialization 124 void universe_post_module_init(); // must happen after call_initPhase2 125 126 #ifdef DTRACE_ENABLED 127 128 // Only bother with this argument setup if dtrace is available 129 130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 132 133 #define DTRACE_THREAD_PROBE(probe, javathread) \ 134 { \ 135 ResourceMark rm(this); \ 136 int len = 0; \ 137 const char* name = (javathread)->get_thread_name(); \ 138 len = strlen(name); \ 139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 140 (char *) name, len, \ 141 java_lang_Thread::thread_id((javathread)->threadObj()), \ 142 (uintptr_t) (javathread)->osthread()->thread_id(), \ 143 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 144 } 145 146 #else // ndef DTRACE_ENABLED 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) 149 150 #endif // ndef DTRACE_ENABLED 151 152 #ifndef USE_LIBRARY_BASED_TLS_ONLY 153 // Current thread is maintained as a thread-local variable 154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 155 #endif 156 // Class hierarchy 157 // - Thread 158 // - VMThread 159 // - WatcherThread 160 // - ConcurrentMarkSweepThread 161 // - JavaThread 162 // - CompilerThread 163 164 // ======= Thread ======== 165 // Support for forcing alignment of thread objects for biased locking 166 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 167 if (UseBiasedLocking) { 168 const int alignment = markOopDesc::biased_lock_alignment; 169 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 170 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 171 : AllocateHeap(aligned_size, flags, CURRENT_PC, 172 AllocFailStrategy::RETURN_NULL); 173 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 174 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 175 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 176 "JavaThread alignment code overflowed allocated storage"); 177 if (aligned_addr != real_malloc_addr) { 178 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 179 p2i(real_malloc_addr), 180 p2i(aligned_addr)); 181 } 182 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 183 return aligned_addr; 184 } else { 185 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 186 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 187 } 188 } 189 190 void Thread::operator delete(void* p) { 191 if (UseBiasedLocking) { 192 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 193 FreeHeap(real_malloc_addr); 194 } else { 195 FreeHeap(p); 196 } 197 } 198 199 200 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 201 // JavaThread 202 203 204 Thread::Thread() { 205 // stack and get_thread 206 set_stack_base(NULL); 207 set_stack_size(0); 208 set_self_raw_id(0); 209 set_lgrp_id(-1); 210 DEBUG_ONLY(clear_suspendible_thread();) 211 212 // allocated data structures 213 set_osthread(NULL); 214 set_resource_area(new (mtThread)ResourceArea()); 215 DEBUG_ONLY(_current_resource_mark = NULL;) 216 set_handle_area(new (mtThread) HandleArea(NULL)); 217 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 218 set_active_handles(NULL); 219 set_free_handle_block(NULL); 220 set_last_handle_mark(NULL); 221 222 // This initial value ==> never claimed. 223 _oops_do_parity = 0; 224 225 // the handle mark links itself to last_handle_mark 226 new HandleMark(this); 227 228 // plain initialization 229 debug_only(_owned_locks = NULL;) 230 debug_only(_allow_allocation_count = 0;) 231 NOT_PRODUCT(_allow_safepoint_count = 0;) 232 NOT_PRODUCT(_skip_gcalot = false;) 233 _jvmti_env_iteration_count = 0; 234 set_allocated_bytes(0); 235 _vm_operation_started_count = 0; 236 _vm_operation_completed_count = 0; 237 _current_pending_monitor = NULL; 238 _current_pending_monitor_is_from_java = true; 239 _current_waiting_monitor = NULL; 240 _num_nested_signal = 0; 241 omFreeList = NULL; 242 omFreeCount = 0; 243 omFreeProvision = 32; 244 omInUseList = NULL; 245 omInUseCount = 0; 246 247 #ifdef ASSERT 248 _visited_for_critical_count = false; 249 #endif 250 251 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 252 Monitor::_safepoint_check_sometimes); 253 _suspend_flags = 0; 254 255 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 256 _hashStateX = os::random(); 257 _hashStateY = 842502087; 258 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 259 _hashStateW = 273326509; 260 261 _OnTrap = 0; 262 _schedctl = NULL; 263 _Stalled = 0; 264 _TypeTag = 0x2BAD; 265 266 // Many of the following fields are effectively final - immutable 267 // Note that nascent threads can't use the Native Monitor-Mutex 268 // construct until the _MutexEvent is initialized ... 269 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 270 // we might instead use a stack of ParkEvents that we could provision on-demand. 271 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 272 // and ::Release() 273 _ParkEvent = ParkEvent::Allocate(this); 274 _SleepEvent = ParkEvent::Allocate(this); 275 _MutexEvent = ParkEvent::Allocate(this); 276 _MuxEvent = ParkEvent::Allocate(this); 277 278 #ifdef CHECK_UNHANDLED_OOPS 279 if (CheckUnhandledOops) { 280 _unhandled_oops = new UnhandledOops(this); 281 } 282 #endif // CHECK_UNHANDLED_OOPS 283 #ifdef ASSERT 284 if (UseBiasedLocking) { 285 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 286 assert(this == _real_malloc_address || 287 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 288 "bug in forced alignment of thread objects"); 289 } 290 #endif // ASSERT 291 } 292 293 void Thread::initialize_thread_current() { 294 #ifndef USE_LIBRARY_BASED_TLS_ONLY 295 assert(_thr_current == NULL, "Thread::current already initialized"); 296 _thr_current = this; 297 #endif 298 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 299 ThreadLocalStorage::set_thread(this); 300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 301 } 302 303 void Thread::clear_thread_current() { 304 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 305 #ifndef USE_LIBRARY_BASED_TLS_ONLY 306 _thr_current = NULL; 307 #endif 308 ThreadLocalStorage::set_thread(NULL); 309 } 310 311 void Thread::record_stack_base_and_size() { 312 set_stack_base(os::current_stack_base()); 313 set_stack_size(os::current_stack_size()); 314 // CR 7190089: on Solaris, primordial thread's stack is adjusted 315 // in initialize_thread(). Without the adjustment, stack size is 316 // incorrect if stack is set to unlimited (ulimit -s unlimited). 317 // So far, only Solaris has real implementation of initialize_thread(). 318 // 319 // set up any platform-specific state. 320 os::initialize_thread(this); 321 322 // Set stack limits after thread is initialized. 323 if (is_Java_thread()) { 324 ((JavaThread*) this)->set_stack_overflow_limit(); 325 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 326 } 327 #if INCLUDE_NMT 328 // record thread's native stack, stack grows downward 329 MemTracker::record_thread_stack(stack_end(), stack_size()); 330 #endif // INCLUDE_NMT 331 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 332 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 333 os::current_thread_id(), p2i(stack_base() - stack_size()), 334 p2i(stack_base()), stack_size()/1024); 335 } 336 337 338 Thread::~Thread() { 339 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 340 ObjectSynchronizer::omFlush(this); 341 342 EVENT_THREAD_DESTRUCT(this); 343 344 // stack_base can be NULL if the thread is never started or exited before 345 // record_stack_base_and_size called. Although, we would like to ensure 346 // that all started threads do call record_stack_base_and_size(), there is 347 // not proper way to enforce that. 348 #if INCLUDE_NMT 349 if (_stack_base != NULL) { 350 MemTracker::release_thread_stack(stack_end(), stack_size()); 351 #ifdef ASSERT 352 set_stack_base(NULL); 353 #endif 354 } 355 #endif // INCLUDE_NMT 356 357 // deallocate data structures 358 delete resource_area(); 359 // since the handle marks are using the handle area, we have to deallocated the root 360 // handle mark before deallocating the thread's handle area, 361 assert(last_handle_mark() != NULL, "check we have an element"); 362 delete last_handle_mark(); 363 assert(last_handle_mark() == NULL, "check we have reached the end"); 364 365 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 366 // We NULL out the fields for good hygiene. 367 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 368 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 369 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 370 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 371 372 delete handle_area(); 373 delete metadata_handles(); 374 375 // SR_handler uses this as a termination indicator - 376 // needs to happen before os::free_thread() 377 delete _SR_lock; 378 _SR_lock = NULL; 379 380 // osthread() can be NULL, if creation of thread failed. 381 if (osthread() != NULL) os::free_thread(osthread()); 382 383 // clear Thread::current if thread is deleting itself. 384 // Needed to ensure JNI correctly detects non-attached threads. 385 if (this == Thread::current()) { 386 clear_thread_current(); 387 } 388 389 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 390 } 391 392 // NOTE: dummy function for assertion purpose. 393 void Thread::run() { 394 ShouldNotReachHere(); 395 } 396 397 #ifdef ASSERT 398 // Private method to check for dangling thread pointer 399 void check_for_dangling_thread_pointer(Thread *thread) { 400 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 401 "possibility of dangling Thread pointer"); 402 } 403 #endif 404 405 ThreadPriority Thread::get_priority(const Thread* const thread) { 406 ThreadPriority priority; 407 // Can return an error! 408 (void)os::get_priority(thread, priority); 409 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 410 return priority; 411 } 412 413 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 414 debug_only(check_for_dangling_thread_pointer(thread);) 415 // Can return an error! 416 (void)os::set_priority(thread, priority); 417 } 418 419 420 void Thread::start(Thread* thread) { 421 // Start is different from resume in that its safety is guaranteed by context or 422 // being called from a Java method synchronized on the Thread object. 423 if (!DisableStartThread) { 424 if (thread->is_Java_thread()) { 425 // Initialize the thread state to RUNNABLE before starting this thread. 426 // Can not set it after the thread started because we do not know the 427 // exact thread state at that time. It could be in MONITOR_WAIT or 428 // in SLEEPING or some other state. 429 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 430 java_lang_Thread::RUNNABLE); 431 } 432 os::start_thread(thread); 433 } 434 } 435 436 // Enqueue a VM_Operation to do the job for us - sometime later 437 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 438 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 439 VMThread::execute(vm_stop); 440 } 441 442 443 // Check if an external suspend request has completed (or has been 444 // cancelled). Returns true if the thread is externally suspended and 445 // false otherwise. 446 // 447 // The bits parameter returns information about the code path through 448 // the routine. Useful for debugging: 449 // 450 // set in is_ext_suspend_completed(): 451 // 0x00000001 - routine was entered 452 // 0x00000010 - routine return false at end 453 // 0x00000100 - thread exited (return false) 454 // 0x00000200 - suspend request cancelled (return false) 455 // 0x00000400 - thread suspended (return true) 456 // 0x00001000 - thread is in a suspend equivalent state (return true) 457 // 0x00002000 - thread is native and walkable (return true) 458 // 0x00004000 - thread is native_trans and walkable (needed retry) 459 // 460 // set in wait_for_ext_suspend_completion(): 461 // 0x00010000 - routine was entered 462 // 0x00020000 - suspend request cancelled before loop (return false) 463 // 0x00040000 - thread suspended before loop (return true) 464 // 0x00080000 - suspend request cancelled in loop (return false) 465 // 0x00100000 - thread suspended in loop (return true) 466 // 0x00200000 - suspend not completed during retry loop (return false) 467 468 // Helper class for tracing suspend wait debug bits. 469 // 470 // 0x00000100 indicates that the target thread exited before it could 471 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 472 // 0x00080000 each indicate a cancelled suspend request so they don't 473 // count as wait failures either. 474 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 475 476 class TraceSuspendDebugBits : public StackObj { 477 private: 478 JavaThread * jt; 479 bool is_wait; 480 bool called_by_wait; // meaningful when !is_wait 481 uint32_t * bits; 482 483 public: 484 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 485 uint32_t *_bits) { 486 jt = _jt; 487 is_wait = _is_wait; 488 called_by_wait = _called_by_wait; 489 bits = _bits; 490 } 491 492 ~TraceSuspendDebugBits() { 493 if (!is_wait) { 494 #if 1 495 // By default, don't trace bits for is_ext_suspend_completed() calls. 496 // That trace is very chatty. 497 return; 498 #else 499 if (!called_by_wait) { 500 // If tracing for is_ext_suspend_completed() is enabled, then only 501 // trace calls to it from wait_for_ext_suspend_completion() 502 return; 503 } 504 #endif 505 } 506 507 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 508 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 509 MutexLocker ml(Threads_lock); // needed for get_thread_name() 510 ResourceMark rm; 511 512 tty->print_cr( 513 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 514 jt->get_thread_name(), *bits); 515 516 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 517 } 518 } 519 } 520 }; 521 #undef DEBUG_FALSE_BITS 522 523 524 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 525 uint32_t *bits) { 526 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 527 528 bool did_trans_retry = false; // only do thread_in_native_trans retry once 529 bool do_trans_retry; // flag to force the retry 530 531 *bits |= 0x00000001; 532 533 do { 534 do_trans_retry = false; 535 536 if (is_exiting()) { 537 // Thread is in the process of exiting. This is always checked 538 // first to reduce the risk of dereferencing a freed JavaThread. 539 *bits |= 0x00000100; 540 return false; 541 } 542 543 if (!is_external_suspend()) { 544 // Suspend request is cancelled. This is always checked before 545 // is_ext_suspended() to reduce the risk of a rogue resume 546 // confusing the thread that made the suspend request. 547 *bits |= 0x00000200; 548 return false; 549 } 550 551 if (is_ext_suspended()) { 552 // thread is suspended 553 *bits |= 0x00000400; 554 return true; 555 } 556 557 // Now that we no longer do hard suspends of threads running 558 // native code, the target thread can be changing thread state 559 // while we are in this routine: 560 // 561 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 562 // 563 // We save a copy of the thread state as observed at this moment 564 // and make our decision about suspend completeness based on the 565 // copy. This closes the race where the thread state is seen as 566 // _thread_in_native_trans in the if-thread_blocked check, but is 567 // seen as _thread_blocked in if-thread_in_native_trans check. 568 JavaThreadState save_state = thread_state(); 569 570 if (save_state == _thread_blocked && is_suspend_equivalent()) { 571 // If the thread's state is _thread_blocked and this blocking 572 // condition is known to be equivalent to a suspend, then we can 573 // consider the thread to be externally suspended. This means that 574 // the code that sets _thread_blocked has been modified to do 575 // self-suspension if the blocking condition releases. We also 576 // used to check for CONDVAR_WAIT here, but that is now covered by 577 // the _thread_blocked with self-suspension check. 578 // 579 // Return true since we wouldn't be here unless there was still an 580 // external suspend request. 581 *bits |= 0x00001000; 582 return true; 583 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 584 // Threads running native code will self-suspend on native==>VM/Java 585 // transitions. If its stack is walkable (should always be the case 586 // unless this function is called before the actual java_suspend() 587 // call), then the wait is done. 588 *bits |= 0x00002000; 589 return true; 590 } else if (!called_by_wait && !did_trans_retry && 591 save_state == _thread_in_native_trans && 592 frame_anchor()->walkable()) { 593 // The thread is transitioning from thread_in_native to another 594 // thread state. check_safepoint_and_suspend_for_native_trans() 595 // will force the thread to self-suspend. If it hasn't gotten 596 // there yet we may have caught the thread in-between the native 597 // code check above and the self-suspend. Lucky us. If we were 598 // called by wait_for_ext_suspend_completion(), then it 599 // will be doing the retries so we don't have to. 600 // 601 // Since we use the saved thread state in the if-statement above, 602 // there is a chance that the thread has already transitioned to 603 // _thread_blocked by the time we get here. In that case, we will 604 // make a single unnecessary pass through the logic below. This 605 // doesn't hurt anything since we still do the trans retry. 606 607 *bits |= 0x00004000; 608 609 // Once the thread leaves thread_in_native_trans for another 610 // thread state, we break out of this retry loop. We shouldn't 611 // need this flag to prevent us from getting back here, but 612 // sometimes paranoia is good. 613 did_trans_retry = true; 614 615 // We wait for the thread to transition to a more usable state. 616 for (int i = 1; i <= SuspendRetryCount; i++) { 617 // We used to do an "os::yield_all(i)" call here with the intention 618 // that yielding would increase on each retry. However, the parameter 619 // is ignored on Linux which means the yield didn't scale up. Waiting 620 // on the SR_lock below provides a much more predictable scale up for 621 // the delay. It also provides a simple/direct point to check for any 622 // safepoint requests from the VMThread 623 624 // temporarily drops SR_lock while doing wait with safepoint check 625 // (if we're a JavaThread - the WatcherThread can also call this) 626 // and increase delay with each retry 627 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 628 629 // check the actual thread state instead of what we saved above 630 if (thread_state() != _thread_in_native_trans) { 631 // the thread has transitioned to another thread state so 632 // try all the checks (except this one) one more time. 633 do_trans_retry = true; 634 break; 635 } 636 } // end retry loop 637 638 639 } 640 } while (do_trans_retry); 641 642 *bits |= 0x00000010; 643 return false; 644 } 645 646 // Wait for an external suspend request to complete (or be cancelled). 647 // Returns true if the thread is externally suspended and false otherwise. 648 // 649 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 650 uint32_t *bits) { 651 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 652 false /* !called_by_wait */, bits); 653 654 // local flag copies to minimize SR_lock hold time 655 bool is_suspended; 656 bool pending; 657 uint32_t reset_bits; 658 659 // set a marker so is_ext_suspend_completed() knows we are the caller 660 *bits |= 0x00010000; 661 662 // We use reset_bits to reinitialize the bits value at the top of 663 // each retry loop. This allows the caller to make use of any 664 // unused bits for their own marking purposes. 665 reset_bits = *bits; 666 667 { 668 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 669 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 670 delay, bits); 671 pending = is_external_suspend(); 672 } 673 // must release SR_lock to allow suspension to complete 674 675 if (!pending) { 676 // A cancelled suspend request is the only false return from 677 // is_ext_suspend_completed() that keeps us from entering the 678 // retry loop. 679 *bits |= 0x00020000; 680 return false; 681 } 682 683 if (is_suspended) { 684 *bits |= 0x00040000; 685 return true; 686 } 687 688 for (int i = 1; i <= retries; i++) { 689 *bits = reset_bits; // reinit to only track last retry 690 691 // We used to do an "os::yield_all(i)" call here with the intention 692 // that yielding would increase on each retry. However, the parameter 693 // is ignored on Linux which means the yield didn't scale up. Waiting 694 // on the SR_lock below provides a much more predictable scale up for 695 // the delay. It also provides a simple/direct point to check for any 696 // safepoint requests from the VMThread 697 698 { 699 MutexLocker ml(SR_lock()); 700 // wait with safepoint check (if we're a JavaThread - the WatcherThread 701 // can also call this) and increase delay with each retry 702 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 703 704 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 705 delay, bits); 706 707 // It is possible for the external suspend request to be cancelled 708 // (by a resume) before the actual suspend operation is completed. 709 // Refresh our local copy to see if we still need to wait. 710 pending = is_external_suspend(); 711 } 712 713 if (!pending) { 714 // A cancelled suspend request is the only false return from 715 // is_ext_suspend_completed() that keeps us from staying in the 716 // retry loop. 717 *bits |= 0x00080000; 718 return false; 719 } 720 721 if (is_suspended) { 722 *bits |= 0x00100000; 723 return true; 724 } 725 } // end retry loop 726 727 // thread did not suspend after all our retries 728 *bits |= 0x00200000; 729 return false; 730 } 731 732 #ifndef PRODUCT 733 void JavaThread::record_jump(address target, address instr, const char* file, 734 int line) { 735 736 // This should not need to be atomic as the only way for simultaneous 737 // updates is via interrupts. Even then this should be rare or non-existent 738 // and we don't care that much anyway. 739 740 int index = _jmp_ring_index; 741 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 742 _jmp_ring[index]._target = (intptr_t) target; 743 _jmp_ring[index]._instruction = (intptr_t) instr; 744 _jmp_ring[index]._file = file; 745 _jmp_ring[index]._line = line; 746 } 747 #endif // PRODUCT 748 749 // Called by flat profiler 750 // Callers have already called wait_for_ext_suspend_completion 751 // The assertion for that is currently too complex to put here: 752 bool JavaThread::profile_last_Java_frame(frame* _fr) { 753 bool gotframe = false; 754 // self suspension saves needed state. 755 if (has_last_Java_frame() && _anchor.walkable()) { 756 *_fr = pd_last_frame(); 757 gotframe = true; 758 } 759 return gotframe; 760 } 761 762 void Thread::interrupt(Thread* thread) { 763 debug_only(check_for_dangling_thread_pointer(thread);) 764 os::interrupt(thread); 765 } 766 767 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 768 debug_only(check_for_dangling_thread_pointer(thread);) 769 // Note: If clear_interrupted==false, this simply fetches and 770 // returns the value of the field osthread()->interrupted(). 771 return os::is_interrupted(thread, clear_interrupted); 772 } 773 774 775 // GC Support 776 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 777 jint thread_parity = _oops_do_parity; 778 if (thread_parity != strong_roots_parity) { 779 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 780 if (res == thread_parity) { 781 return true; 782 } else { 783 guarantee(res == strong_roots_parity, "Or else what?"); 784 return false; 785 } 786 } 787 return false; 788 } 789 790 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 791 active_handles()->oops_do(f); 792 // Do oop for ThreadShadow 793 f->do_oop((oop*)&_pending_exception); 794 handle_area()->oops_do(f); 795 796 if (MonitorInUseLists) { 797 // When using thread local monitor lists, we scan them here, 798 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 799 ObjectSynchronizer::thread_local_used_oops_do(this, f); 800 } 801 } 802 803 void Thread::metadata_handles_do(void f(Metadata*)) { 804 // Only walk the Handles in Thread. 805 if (metadata_handles() != NULL) { 806 for (int i = 0; i< metadata_handles()->length(); i++) { 807 f(metadata_handles()->at(i)); 808 } 809 } 810 } 811 812 void Thread::print_on(outputStream* st) const { 813 // get_priority assumes osthread initialized 814 if (osthread() != NULL) { 815 int os_prio; 816 if (os::get_native_priority(this, &os_prio) == OS_OK) { 817 st->print("os_prio=%d ", os_prio); 818 } 819 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 820 ext().print_on(st); 821 osthread()->print_on(st); 822 } 823 debug_only(if (WizardMode) print_owned_locks_on(st);) 824 } 825 826 // Thread::print_on_error() is called by fatal error handler. Don't use 827 // any lock or allocate memory. 828 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 829 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 830 831 if (is_VM_thread()) { st->print("VMThread"); } 832 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 833 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 834 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 835 else { st->print("Thread"); } 836 837 if (is_Named_thread()) { 838 st->print(" \"%s\"", name()); 839 } 840 841 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 842 p2i(stack_end()), p2i(stack_base())); 843 844 if (osthread()) { 845 st->print(" [id=%d]", osthread()->thread_id()); 846 } 847 } 848 849 #ifdef ASSERT 850 void Thread::print_owned_locks_on(outputStream* st) const { 851 Monitor *cur = _owned_locks; 852 if (cur == NULL) { 853 st->print(" (no locks) "); 854 } else { 855 st->print_cr(" Locks owned:"); 856 while (cur) { 857 cur->print_on(st); 858 cur = cur->next(); 859 } 860 } 861 } 862 863 static int ref_use_count = 0; 864 865 bool Thread::owns_locks_but_compiled_lock() const { 866 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 867 if (cur != Compile_lock) return true; 868 } 869 return false; 870 } 871 872 873 #endif 874 875 #ifndef PRODUCT 876 877 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 878 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 879 // no threads which allow_vm_block's are held 880 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 881 // Check if current thread is allowed to block at a safepoint 882 if (!(_allow_safepoint_count == 0)) { 883 fatal("Possible safepoint reached by thread that does not allow it"); 884 } 885 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 886 fatal("LEAF method calling lock?"); 887 } 888 889 #ifdef ASSERT 890 if (potential_vm_operation && is_Java_thread() 891 && !Universe::is_bootstrapping()) { 892 // Make sure we do not hold any locks that the VM thread also uses. 893 // This could potentially lead to deadlocks 894 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 895 // Threads_lock is special, since the safepoint synchronization will not start before this is 896 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 897 // since it is used to transfer control between JavaThreads and the VMThread 898 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 899 if ((cur->allow_vm_block() && 900 cur != Threads_lock && 901 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 902 cur != VMOperationRequest_lock && 903 cur != VMOperationQueue_lock) || 904 cur->rank() == Mutex::special) { 905 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 906 } 907 } 908 } 909 910 if (GCALotAtAllSafepoints) { 911 // We could enter a safepoint here and thus have a gc 912 InterfaceSupport::check_gc_alot(); 913 } 914 #endif 915 } 916 #endif 917 918 bool Thread::is_in_stack(address adr) const { 919 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 920 address end = os::current_stack_pointer(); 921 // Allow non Java threads to call this without stack_base 922 if (_stack_base == NULL) return true; 923 if (stack_base() >= adr && adr >= end) return true; 924 925 return false; 926 } 927 928 bool Thread::is_in_usable_stack(address adr) const { 929 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 930 size_t usable_stack_size = _stack_size - stack_guard_size; 931 932 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 933 } 934 935 936 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 937 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 938 // used for compilation in the future. If that change is made, the need for these methods 939 // should be revisited, and they should be removed if possible. 940 941 bool Thread::is_lock_owned(address adr) const { 942 return on_local_stack(adr); 943 } 944 945 bool Thread::set_as_starting_thread() { 946 // NOTE: this must be called inside the main thread. 947 return os::create_main_thread((JavaThread*)this); 948 } 949 950 static void initialize_class(Symbol* class_name, TRAPS) { 951 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 952 InstanceKlass::cast(klass)->initialize(CHECK); 953 } 954 955 956 // Creates the initial ThreadGroup 957 static Handle create_initial_thread_group(TRAPS) { 958 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 959 InstanceKlass* ik = InstanceKlass::cast(k); 960 961 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 962 { 963 JavaValue result(T_VOID); 964 JavaCalls::call_special(&result, 965 system_instance, 966 ik, 967 vmSymbols::object_initializer_name(), 968 vmSymbols::void_method_signature(), 969 CHECK_NH); 970 } 971 Universe::set_system_thread_group(system_instance()); 972 973 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 974 { 975 JavaValue result(T_VOID); 976 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 977 JavaCalls::call_special(&result, 978 main_instance, 979 ik, 980 vmSymbols::object_initializer_name(), 981 vmSymbols::threadgroup_string_void_signature(), 982 system_instance, 983 string, 984 CHECK_NH); 985 } 986 return main_instance; 987 } 988 989 // Creates the initial Thread 990 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 991 TRAPS) { 992 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 993 InstanceKlass* ik = InstanceKlass::cast(k); 994 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 995 996 java_lang_Thread::set_thread(thread_oop(), thread); 997 java_lang_Thread::set_priority(thread_oop(), NormPriority); 998 thread->set_threadObj(thread_oop()); 999 1000 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1001 1002 JavaValue result(T_VOID); 1003 JavaCalls::call_special(&result, thread_oop, 1004 ik, 1005 vmSymbols::object_initializer_name(), 1006 vmSymbols::threadgroup_string_void_signature(), 1007 thread_group, 1008 string, 1009 CHECK_NULL); 1010 return thread_oop(); 1011 } 1012 1013 char java_runtime_name[128] = ""; 1014 char java_runtime_version[128] = ""; 1015 1016 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1017 static const char* get_java_runtime_name(TRAPS) { 1018 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1019 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1020 fieldDescriptor fd; 1021 bool found = k != NULL && 1022 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1023 vmSymbols::string_signature(), &fd); 1024 if (found) { 1025 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1026 if (name_oop == NULL) { 1027 return NULL; 1028 } 1029 const char* name = java_lang_String::as_utf8_string(name_oop, 1030 java_runtime_name, 1031 sizeof(java_runtime_name)); 1032 return name; 1033 } else { 1034 return NULL; 1035 } 1036 } 1037 1038 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1039 static const char* get_java_runtime_version(TRAPS) { 1040 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1041 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1042 fieldDescriptor fd; 1043 bool found = k != NULL && 1044 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1045 vmSymbols::string_signature(), &fd); 1046 if (found) { 1047 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1048 if (name_oop == NULL) { 1049 return NULL; 1050 } 1051 const char* name = java_lang_String::as_utf8_string(name_oop, 1052 java_runtime_version, 1053 sizeof(java_runtime_version)); 1054 return name; 1055 } else { 1056 return NULL; 1057 } 1058 } 1059 1060 // General purpose hook into Java code, run once when the VM is initialized. 1061 // The Java library method itself may be changed independently from the VM. 1062 static void call_postVMInitHook(TRAPS) { 1063 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1064 if (klass != NULL) { 1065 JavaValue result(T_VOID); 1066 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1067 vmSymbols::void_method_signature(), 1068 CHECK); 1069 } 1070 } 1071 1072 static void reset_vm_info_property(TRAPS) { 1073 // the vm info string 1074 ResourceMark rm(THREAD); 1075 const char *vm_info = VM_Version::vm_info_string(); 1076 1077 // java.lang.System class 1078 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1079 1080 // setProperty arguments 1081 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1082 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1083 1084 // return value 1085 JavaValue r(T_OBJECT); 1086 1087 // public static String setProperty(String key, String value); 1088 JavaCalls::call_static(&r, 1089 klass, 1090 vmSymbols::setProperty_name(), 1091 vmSymbols::string_string_string_signature(), 1092 key_str, 1093 value_str, 1094 CHECK); 1095 } 1096 1097 1098 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1099 bool daemon, TRAPS) { 1100 assert(thread_group.not_null(), "thread group should be specified"); 1101 assert(threadObj() == NULL, "should only create Java thread object once"); 1102 1103 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1104 InstanceKlass* ik = InstanceKlass::cast(k); 1105 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1106 1107 java_lang_Thread::set_thread(thread_oop(), this); 1108 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1109 set_threadObj(thread_oop()); 1110 1111 JavaValue result(T_VOID); 1112 if (thread_name != NULL) { 1113 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1114 // Thread gets assigned specified name and null target 1115 JavaCalls::call_special(&result, 1116 thread_oop, 1117 ik, 1118 vmSymbols::object_initializer_name(), 1119 vmSymbols::threadgroup_string_void_signature(), 1120 thread_group, // Argument 1 1121 name, // Argument 2 1122 THREAD); 1123 } else { 1124 // Thread gets assigned name "Thread-nnn" and null target 1125 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1126 JavaCalls::call_special(&result, 1127 thread_oop, 1128 ik, 1129 vmSymbols::object_initializer_name(), 1130 vmSymbols::threadgroup_runnable_void_signature(), 1131 thread_group, // Argument 1 1132 Handle(), // Argument 2 1133 THREAD); 1134 } 1135 1136 1137 if (daemon) { 1138 java_lang_Thread::set_daemon(thread_oop()); 1139 } 1140 1141 if (HAS_PENDING_EXCEPTION) { 1142 return; 1143 } 1144 1145 Klass* group = SystemDictionary::ThreadGroup_klass(); 1146 Handle threadObj(THREAD, this->threadObj()); 1147 1148 JavaCalls::call_special(&result, 1149 thread_group, 1150 group, 1151 vmSymbols::add_method_name(), 1152 vmSymbols::thread_void_signature(), 1153 threadObj, // Arg 1 1154 THREAD); 1155 } 1156 1157 // NamedThread -- non-JavaThread subclasses with multiple 1158 // uniquely named instances should derive from this. 1159 NamedThread::NamedThread() : Thread() { 1160 _name = NULL; 1161 _processed_thread = NULL; 1162 _gc_id = GCId::undefined(); 1163 } 1164 1165 NamedThread::~NamedThread() { 1166 if (_name != NULL) { 1167 FREE_C_HEAP_ARRAY(char, _name); 1168 _name = NULL; 1169 } 1170 } 1171 1172 void NamedThread::set_name(const char* format, ...) { 1173 guarantee(_name == NULL, "Only get to set name once."); 1174 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1175 guarantee(_name != NULL, "alloc failure"); 1176 va_list ap; 1177 va_start(ap, format); 1178 jio_vsnprintf(_name, max_name_len, format, ap); 1179 va_end(ap); 1180 } 1181 1182 void NamedThread::initialize_named_thread() { 1183 set_native_thread_name(name()); 1184 } 1185 1186 void NamedThread::print_on(outputStream* st) const { 1187 st->print("\"%s\" ", name()); 1188 Thread::print_on(st); 1189 st->cr(); 1190 } 1191 1192 1193 // ======= WatcherThread ======== 1194 1195 // The watcher thread exists to simulate timer interrupts. It should 1196 // be replaced by an abstraction over whatever native support for 1197 // timer interrupts exists on the platform. 1198 1199 WatcherThread* WatcherThread::_watcher_thread = NULL; 1200 bool WatcherThread::_startable = false; 1201 volatile bool WatcherThread::_should_terminate = false; 1202 1203 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1204 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1205 if (os::create_thread(this, os::watcher_thread)) { 1206 _watcher_thread = this; 1207 1208 // Set the watcher thread to the highest OS priority which should not be 1209 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1210 // is created. The only normal thread using this priority is the reference 1211 // handler thread, which runs for very short intervals only. 1212 // If the VMThread's priority is not lower than the WatcherThread profiling 1213 // will be inaccurate. 1214 os::set_priority(this, MaxPriority); 1215 if (!DisableStartThread) { 1216 os::start_thread(this); 1217 } 1218 } 1219 } 1220 1221 int WatcherThread::sleep() const { 1222 // The WatcherThread does not participate in the safepoint protocol 1223 // for the PeriodicTask_lock because it is not a JavaThread. 1224 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1225 1226 if (_should_terminate) { 1227 // check for termination before we do any housekeeping or wait 1228 return 0; // we did not sleep. 1229 } 1230 1231 // remaining will be zero if there are no tasks, 1232 // causing the WatcherThread to sleep until a task is 1233 // enrolled 1234 int remaining = PeriodicTask::time_to_wait(); 1235 int time_slept = 0; 1236 1237 // we expect this to timeout - we only ever get unparked when 1238 // we should terminate or when a new task has been enrolled 1239 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1240 1241 jlong time_before_loop = os::javaTimeNanos(); 1242 1243 while (true) { 1244 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1245 remaining); 1246 jlong now = os::javaTimeNanos(); 1247 1248 if (remaining == 0) { 1249 // if we didn't have any tasks we could have waited for a long time 1250 // consider the time_slept zero and reset time_before_loop 1251 time_slept = 0; 1252 time_before_loop = now; 1253 } else { 1254 // need to recalculate since we might have new tasks in _tasks 1255 time_slept = (int) ((now - time_before_loop) / 1000000); 1256 } 1257 1258 // Change to task list or spurious wakeup of some kind 1259 if (timedout || _should_terminate) { 1260 break; 1261 } 1262 1263 remaining = PeriodicTask::time_to_wait(); 1264 if (remaining == 0) { 1265 // Last task was just disenrolled so loop around and wait until 1266 // another task gets enrolled 1267 continue; 1268 } 1269 1270 remaining -= time_slept; 1271 if (remaining <= 0) { 1272 break; 1273 } 1274 } 1275 1276 return time_slept; 1277 } 1278 1279 void WatcherThread::run() { 1280 assert(this == watcher_thread(), "just checking"); 1281 1282 this->record_stack_base_and_size(); 1283 this->set_native_thread_name(this->name()); 1284 this->set_active_handles(JNIHandleBlock::allocate_block()); 1285 while (true) { 1286 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1287 assert(watcher_thread() == this, "thread consistency check"); 1288 1289 // Calculate how long it'll be until the next PeriodicTask work 1290 // should be done, and sleep that amount of time. 1291 int time_waited = sleep(); 1292 1293 if (is_error_reported()) { 1294 // A fatal error has happened, the error handler(VMError::report_and_die) 1295 // should abort JVM after creating an error log file. However in some 1296 // rare cases, the error handler itself might deadlock. Here periodically 1297 // check for error reporting timeouts, and if it happens, just proceed to 1298 // abort the VM. 1299 1300 // This code is in WatcherThread because WatcherThread wakes up 1301 // periodically so the fatal error handler doesn't need to do anything; 1302 // also because the WatcherThread is less likely to crash than other 1303 // threads. 1304 1305 for (;;) { 1306 // Note: we use naked sleep in this loop because we want to avoid using 1307 // any kind of VM infrastructure which may be broken at this point. 1308 if (VMError::check_timeout()) { 1309 // We hit error reporting timeout. Error reporting was interrupted and 1310 // will be wrapping things up now (closing files etc). Give it some more 1311 // time, then quit the VM. 1312 os::naked_short_sleep(200); 1313 // Print a message to stderr. 1314 fdStream err(defaultStream::output_fd()); 1315 err.print_raw_cr("# [ timer expired, abort... ]"); 1316 // skip atexit/vm_exit/vm_abort hooks 1317 os::die(); 1318 } 1319 1320 // Wait a second, then recheck for timeout. 1321 os::naked_short_sleep(999); 1322 } 1323 } 1324 1325 if (_should_terminate) { 1326 // check for termination before posting the next tick 1327 break; 1328 } 1329 1330 PeriodicTask::real_time_tick(time_waited); 1331 } 1332 1333 // Signal that it is terminated 1334 { 1335 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1336 _watcher_thread = NULL; 1337 Terminator_lock->notify(); 1338 } 1339 } 1340 1341 void WatcherThread::start() { 1342 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1343 1344 if (watcher_thread() == NULL && _startable) { 1345 _should_terminate = false; 1346 // Create the single instance of WatcherThread 1347 new WatcherThread(); 1348 } 1349 } 1350 1351 void WatcherThread::make_startable() { 1352 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1353 _startable = true; 1354 } 1355 1356 void WatcherThread::stop() { 1357 { 1358 // Follow normal safepoint aware lock enter protocol since the 1359 // WatcherThread is stopped by another JavaThread. 1360 MutexLocker ml(PeriodicTask_lock); 1361 _should_terminate = true; 1362 1363 WatcherThread* watcher = watcher_thread(); 1364 if (watcher != NULL) { 1365 // unpark the WatcherThread so it can see that it should terminate 1366 watcher->unpark(); 1367 } 1368 } 1369 1370 MutexLocker mu(Terminator_lock); 1371 1372 while (watcher_thread() != NULL) { 1373 // This wait should make safepoint checks, wait without a timeout, 1374 // and wait as a suspend-equivalent condition. 1375 // 1376 // Note: If the FlatProfiler is running, then this thread is waiting 1377 // for the WatcherThread to terminate and the WatcherThread, via the 1378 // FlatProfiler task, is waiting for the external suspend request on 1379 // this thread to complete. wait_for_ext_suspend_completion() will 1380 // eventually timeout, but that takes time. Making this wait a 1381 // suspend-equivalent condition solves that timeout problem. 1382 // 1383 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1384 Mutex::_as_suspend_equivalent_flag); 1385 } 1386 } 1387 1388 void WatcherThread::unpark() { 1389 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1390 PeriodicTask_lock->notify(); 1391 } 1392 1393 void WatcherThread::print_on(outputStream* st) const { 1394 st->print("\"%s\" ", name()); 1395 Thread::print_on(st); 1396 st->cr(); 1397 } 1398 1399 // ======= JavaThread ======== 1400 1401 #if INCLUDE_JVMCI 1402 1403 jlong* JavaThread::_jvmci_old_thread_counters; 1404 1405 bool jvmci_counters_include(JavaThread* thread) { 1406 oop threadObj = thread->threadObj(); 1407 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1408 } 1409 1410 void JavaThread::collect_counters(typeArrayOop array) { 1411 if (JVMCICounterSize > 0) { 1412 MutexLocker tl(Threads_lock); 1413 for (int i = 0; i < array->length(); i++) { 1414 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1415 } 1416 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1417 if (jvmci_counters_include(tp)) { 1418 for (int i = 0; i < array->length(); i++) { 1419 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1420 } 1421 } 1422 } 1423 } 1424 } 1425 1426 #endif // INCLUDE_JVMCI 1427 1428 // A JavaThread is a normal Java thread 1429 1430 void JavaThread::initialize() { 1431 // Initialize fields 1432 1433 set_saved_exception_pc(NULL); 1434 set_threadObj(NULL); 1435 _anchor.clear(); 1436 set_entry_point(NULL); 1437 set_jni_functions(jni_functions()); 1438 set_callee_target(NULL); 1439 set_vm_result(NULL); 1440 set_vm_result_2(NULL); 1441 set_vframe_array_head(NULL); 1442 set_vframe_array_last(NULL); 1443 set_deferred_locals(NULL); 1444 set_deopt_mark(NULL); 1445 set_deopt_compiled_method(NULL); 1446 clear_must_deopt_id(); 1447 set_monitor_chunks(NULL); 1448 set_next(NULL); 1449 set_thread_state(_thread_new); 1450 _terminated = _not_terminated; 1451 _privileged_stack_top = NULL; 1452 _array_for_gc = NULL; 1453 _suspend_equivalent = false; 1454 _in_deopt_handler = 0; 1455 _doing_unsafe_access = false; 1456 _stack_guard_state = stack_guard_unused; 1457 #if INCLUDE_JVMCI 1458 _pending_monitorenter = false; 1459 _pending_deoptimization = -1; 1460 _pending_failed_speculation = NULL; 1461 _pending_transfer_to_interpreter = false; 1462 _adjusting_comp_level = false; 1463 _jvmci._alternate_call_target = NULL; 1464 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1465 if (JVMCICounterSize > 0) { 1466 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1467 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1468 } else { 1469 _jvmci_counters = NULL; 1470 } 1471 #endif // INCLUDE_JVMCI 1472 _reserved_stack_activation = NULL; // stack base not known yet 1473 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1474 _exception_pc = 0; 1475 _exception_handler_pc = 0; 1476 _is_method_handle_return = 0; 1477 _jvmti_thread_state= NULL; 1478 _should_post_on_exceptions_flag = JNI_FALSE; 1479 _jvmti_get_loaded_classes_closure = NULL; 1480 _interp_only_mode = 0; 1481 _special_runtime_exit_condition = _no_async_condition; 1482 _pending_async_exception = NULL; 1483 _thread_stat = NULL; 1484 _thread_stat = new ThreadStatistics(); 1485 _blocked_on_compilation = false; 1486 _jni_active_critical = 0; 1487 _pending_jni_exception_check_fn = NULL; 1488 _do_not_unlock_if_synchronized = false; 1489 _cached_monitor_info = NULL; 1490 _parker = Parker::Allocate(this); 1491 _bytes_until_sample = 0; 1492 1493 #ifndef PRODUCT 1494 _jmp_ring_index = 0; 1495 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1496 record_jump(NULL, NULL, NULL, 0); 1497 } 1498 #endif // PRODUCT 1499 1500 set_thread_profiler(NULL); 1501 if (FlatProfiler::is_active()) { 1502 // This is where we would decide to either give each thread it's own profiler 1503 // or use one global one from FlatProfiler, 1504 // or up to some count of the number of profiled threads, etc. 1505 ThreadProfiler* pp = new ThreadProfiler(); 1506 pp->engage(); 1507 set_thread_profiler(pp); 1508 } 1509 1510 // Setup safepoint state info for this thread 1511 ThreadSafepointState::create(this); 1512 1513 debug_only(_java_call_counter = 0); 1514 1515 // JVMTI PopFrame support 1516 _popframe_condition = popframe_inactive; 1517 _popframe_preserved_args = NULL; 1518 _popframe_preserved_args_size = 0; 1519 _frames_to_pop_failed_realloc = 0; 1520 1521 pd_initialize(); 1522 } 1523 1524 #if INCLUDE_ALL_GCS 1525 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1526 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1527 #endif // INCLUDE_ALL_GCS 1528 1529 JavaThread::JavaThread(bool is_attaching_via_jni) : 1530 Thread() 1531 #if INCLUDE_ALL_GCS 1532 , _satb_mark_queue(&_satb_mark_queue_set), 1533 _dirty_card_queue(&_dirty_card_queue_set) 1534 #endif // INCLUDE_ALL_GCS 1535 { 1536 initialize(); 1537 if (is_attaching_via_jni) { 1538 _jni_attach_state = _attaching_via_jni; 1539 } else { 1540 _jni_attach_state = _not_attaching_via_jni; 1541 } 1542 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1543 } 1544 1545 bool JavaThread::reguard_stack(address cur_sp) { 1546 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1547 && _stack_guard_state != stack_guard_reserved_disabled) { 1548 return true; // Stack already guarded or guard pages not needed. 1549 } 1550 1551 if (register_stack_overflow()) { 1552 // For those architectures which have separate register and 1553 // memory stacks, we must check the register stack to see if 1554 // it has overflowed. 1555 return false; 1556 } 1557 1558 // Java code never executes within the yellow zone: the latter is only 1559 // there to provoke an exception during stack banging. If java code 1560 // is executing there, either StackShadowPages should be larger, or 1561 // some exception code in c1, c2 or the interpreter isn't unwinding 1562 // when it should. 1563 guarantee(cur_sp > stack_reserved_zone_base(), 1564 "not enough space to reguard - increase StackShadowPages"); 1565 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1566 enable_stack_yellow_reserved_zone(); 1567 if (reserved_stack_activation() != stack_base()) { 1568 set_reserved_stack_activation(stack_base()); 1569 } 1570 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1571 set_reserved_stack_activation(stack_base()); 1572 enable_stack_reserved_zone(); 1573 } 1574 return true; 1575 } 1576 1577 bool JavaThread::reguard_stack(void) { 1578 return reguard_stack(os::current_stack_pointer()); 1579 } 1580 1581 1582 void JavaThread::block_if_vm_exited() { 1583 if (_terminated == _vm_exited) { 1584 // _vm_exited is set at safepoint, and Threads_lock is never released 1585 // we will block here forever 1586 Threads_lock->lock_without_safepoint_check(); 1587 ShouldNotReachHere(); 1588 } 1589 } 1590 1591 1592 // Remove this ifdef when C1 is ported to the compiler interface. 1593 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1594 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1595 1596 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1597 Thread() 1598 #if INCLUDE_ALL_GCS 1599 , _satb_mark_queue(&_satb_mark_queue_set), 1600 _dirty_card_queue(&_dirty_card_queue_set) 1601 #endif // INCLUDE_ALL_GCS 1602 { 1603 initialize(); 1604 _jni_attach_state = _not_attaching_via_jni; 1605 set_entry_point(entry_point); 1606 // Create the native thread itself. 1607 // %note runtime_23 1608 os::ThreadType thr_type = os::java_thread; 1609 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1610 os::java_thread; 1611 os::create_thread(this, thr_type, stack_sz); 1612 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1613 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1614 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1615 // the exception consists of creating the exception object & initializing it, initialization 1616 // will leave the VM via a JavaCall and then all locks must be unlocked). 1617 // 1618 // The thread is still suspended when we reach here. Thread must be explicit started 1619 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1620 // by calling Threads:add. The reason why this is not done here, is because the thread 1621 // object must be fully initialized (take a look at JVM_Start) 1622 } 1623 1624 JavaThread::~JavaThread() { 1625 1626 // JSR166 -- return the parker to the free list 1627 Parker::Release(_parker); 1628 _parker = NULL; 1629 1630 // Free any remaining previous UnrollBlock 1631 vframeArray* old_array = vframe_array_last(); 1632 1633 if (old_array != NULL) { 1634 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1635 old_array->set_unroll_block(NULL); 1636 delete old_info; 1637 delete old_array; 1638 } 1639 1640 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1641 if (deferred != NULL) { 1642 // This can only happen if thread is destroyed before deoptimization occurs. 1643 assert(deferred->length() != 0, "empty array!"); 1644 do { 1645 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1646 deferred->remove_at(0); 1647 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1648 delete dlv; 1649 } while (deferred->length() != 0); 1650 delete deferred; 1651 } 1652 1653 // All Java related clean up happens in exit 1654 ThreadSafepointState::destroy(this); 1655 if (_thread_profiler != NULL) delete _thread_profiler; 1656 if (_thread_stat != NULL) delete _thread_stat; 1657 1658 #if INCLUDE_JVMCI 1659 if (JVMCICounterSize > 0) { 1660 if (jvmci_counters_include(this)) { 1661 for (int i = 0; i < JVMCICounterSize; i++) { 1662 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1663 } 1664 } 1665 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1666 } 1667 #endif // INCLUDE_JVMCI 1668 } 1669 1670 1671 // The first routine called by a new Java thread 1672 void JavaThread::run() { 1673 // initialize thread-local alloc buffer related fields 1674 this->initialize_tlab(); 1675 1676 // used to test validity of stack trace backs 1677 this->record_base_of_stack_pointer(); 1678 1679 // Record real stack base and size. 1680 this->record_stack_base_and_size(); 1681 1682 this->create_stack_guard_pages(); 1683 1684 this->cache_global_variables(); 1685 1686 // Thread is now sufficient initialized to be handled by the safepoint code as being 1687 // in the VM. Change thread state from _thread_new to _thread_in_vm 1688 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1689 1690 assert(JavaThread::current() == this, "sanity check"); 1691 assert(!Thread::current()->owns_locks(), "sanity check"); 1692 1693 DTRACE_THREAD_PROBE(start, this); 1694 1695 // This operation might block. We call that after all safepoint checks for a new thread has 1696 // been completed. 1697 this->set_active_handles(JNIHandleBlock::allocate_block()); 1698 1699 if (JvmtiExport::should_post_thread_life()) { 1700 JvmtiExport::post_thread_start(this); 1701 } 1702 1703 EventThreadStart event; 1704 if (event.should_commit()) { 1705 event.set_thread(THREAD_TRACE_ID(this)); 1706 event.commit(); 1707 } 1708 1709 // We call another function to do the rest so we are sure that the stack addresses used 1710 // from there will be lower than the stack base just computed 1711 thread_main_inner(); 1712 1713 // Note, thread is no longer valid at this point! 1714 } 1715 1716 1717 void JavaThread::thread_main_inner() { 1718 assert(JavaThread::current() == this, "sanity check"); 1719 assert(this->threadObj() != NULL, "just checking"); 1720 1721 // Execute thread entry point unless this thread has a pending exception 1722 // or has been stopped before starting. 1723 // Note: Due to JVM_StopThread we can have pending exceptions already! 1724 if (!this->has_pending_exception() && 1725 !java_lang_Thread::is_stillborn(this->threadObj())) { 1726 { 1727 ResourceMark rm(this); 1728 this->set_native_thread_name(this->get_thread_name()); 1729 } 1730 HandleMark hm(this); 1731 this->entry_point()(this, this); 1732 } 1733 1734 DTRACE_THREAD_PROBE(stop, this); 1735 1736 this->exit(false); 1737 delete this; 1738 } 1739 1740 1741 static void ensure_join(JavaThread* thread) { 1742 // We do not need to grap the Threads_lock, since we are operating on ourself. 1743 Handle threadObj(thread, thread->threadObj()); 1744 assert(threadObj.not_null(), "java thread object must exist"); 1745 ObjectLocker lock(threadObj, thread); 1746 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1747 thread->clear_pending_exception(); 1748 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1749 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1750 // Clear the native thread instance - this makes isAlive return false and allows the join() 1751 // to complete once we've done the notify_all below 1752 java_lang_Thread::set_thread(threadObj(), NULL); 1753 lock.notify_all(thread); 1754 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1755 thread->clear_pending_exception(); 1756 } 1757 1758 1759 // For any new cleanup additions, please check to see if they need to be applied to 1760 // cleanup_failed_attach_current_thread as well. 1761 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1762 assert(this == JavaThread::current(), "thread consistency check"); 1763 1764 HandleMark hm(this); 1765 Handle uncaught_exception(this, this->pending_exception()); 1766 this->clear_pending_exception(); 1767 Handle threadObj(this, this->threadObj()); 1768 assert(threadObj.not_null(), "Java thread object should be created"); 1769 1770 if (get_thread_profiler() != NULL) { 1771 get_thread_profiler()->disengage(); 1772 ResourceMark rm; 1773 get_thread_profiler()->print(get_thread_name()); 1774 } 1775 1776 1777 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1778 { 1779 EXCEPTION_MARK; 1780 1781 CLEAR_PENDING_EXCEPTION; 1782 } 1783 if (!destroy_vm) { 1784 if (uncaught_exception.not_null()) { 1785 EXCEPTION_MARK; 1786 // Call method Thread.dispatchUncaughtException(). 1787 Klass* thread_klass = SystemDictionary::Thread_klass(); 1788 JavaValue result(T_VOID); 1789 JavaCalls::call_virtual(&result, 1790 threadObj, thread_klass, 1791 vmSymbols::dispatchUncaughtException_name(), 1792 vmSymbols::throwable_void_signature(), 1793 uncaught_exception, 1794 THREAD); 1795 if (HAS_PENDING_EXCEPTION) { 1796 ResourceMark rm(this); 1797 jio_fprintf(defaultStream::error_stream(), 1798 "\nException: %s thrown from the UncaughtExceptionHandler" 1799 " in thread \"%s\"\n", 1800 pending_exception()->klass()->external_name(), 1801 get_thread_name()); 1802 CLEAR_PENDING_EXCEPTION; 1803 } 1804 } 1805 1806 // Called before the java thread exit since we want to read info 1807 // from java_lang_Thread object 1808 EventThreadEnd event; 1809 if (event.should_commit()) { 1810 event.set_thread(THREAD_TRACE_ID(this)); 1811 event.commit(); 1812 } 1813 1814 // Call after last event on thread 1815 EVENT_THREAD_EXIT(this); 1816 1817 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1818 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1819 // is deprecated anyhow. 1820 if (!is_Compiler_thread()) { 1821 int count = 3; 1822 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1823 EXCEPTION_MARK; 1824 JavaValue result(T_VOID); 1825 Klass* thread_klass = SystemDictionary::Thread_klass(); 1826 JavaCalls::call_virtual(&result, 1827 threadObj, thread_klass, 1828 vmSymbols::exit_method_name(), 1829 vmSymbols::void_method_signature(), 1830 THREAD); 1831 CLEAR_PENDING_EXCEPTION; 1832 } 1833 } 1834 // notify JVMTI 1835 if (JvmtiExport::should_post_thread_life()) { 1836 JvmtiExport::post_thread_end(this); 1837 } 1838 1839 // We have notified the agents that we are exiting, before we go on, 1840 // we must check for a pending external suspend request and honor it 1841 // in order to not surprise the thread that made the suspend request. 1842 while (true) { 1843 { 1844 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1845 if (!is_external_suspend()) { 1846 set_terminated(_thread_exiting); 1847 ThreadService::current_thread_exiting(this); 1848 break; 1849 } 1850 // Implied else: 1851 // Things get a little tricky here. We have a pending external 1852 // suspend request, but we are holding the SR_lock so we 1853 // can't just self-suspend. So we temporarily drop the lock 1854 // and then self-suspend. 1855 } 1856 1857 ThreadBlockInVM tbivm(this); 1858 java_suspend_self(); 1859 1860 // We're done with this suspend request, but we have to loop around 1861 // and check again. Eventually we will get SR_lock without a pending 1862 // external suspend request and will be able to mark ourselves as 1863 // exiting. 1864 } 1865 // no more external suspends are allowed at this point 1866 } else { 1867 // before_exit() has already posted JVMTI THREAD_END events 1868 } 1869 1870 // Notify waiters on thread object. This has to be done after exit() is called 1871 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1872 // group should have the destroyed bit set before waiters are notified). 1873 ensure_join(this); 1874 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1875 1876 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1877 // held by this thread must be released. The spec does not distinguish 1878 // between JNI-acquired and regular Java monitors. We can only see 1879 // regular Java monitors here if monitor enter-exit matching is broken. 1880 // 1881 // Optionally release any monitors for regular JavaThread exits. This 1882 // is provided as a work around for any bugs in monitor enter-exit 1883 // matching. This can be expensive so it is not enabled by default. 1884 // 1885 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1886 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1887 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1888 // Sanity check even though JNI DetachCurrentThread() would have 1889 // returned JNI_ERR if there was a Java frame. JavaThread exit 1890 // should be done executing Java code by the time we get here. 1891 assert(!this->has_last_Java_frame(), 1892 "should not have a Java frame when detaching or exiting"); 1893 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1894 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1895 } 1896 1897 // These things needs to be done while we are still a Java Thread. Make sure that thread 1898 // is in a consistent state, in case GC happens 1899 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1900 1901 if (active_handles() != NULL) { 1902 JNIHandleBlock* block = active_handles(); 1903 set_active_handles(NULL); 1904 JNIHandleBlock::release_block(block); 1905 } 1906 1907 if (free_handle_block() != NULL) { 1908 JNIHandleBlock* block = free_handle_block(); 1909 set_free_handle_block(NULL); 1910 JNIHandleBlock::release_block(block); 1911 } 1912 1913 // These have to be removed while this is still a valid thread. 1914 remove_stack_guard_pages(); 1915 1916 if (UseTLAB) { 1917 tlab().make_parsable(true); // retire TLAB 1918 } 1919 1920 if (JvmtiEnv::environments_might_exist()) { 1921 JvmtiExport::cleanup_thread(this); 1922 } 1923 1924 // We must flush any deferred card marks before removing a thread from 1925 // the list of active threads. 1926 Universe::heap()->flush_deferred_store_barrier(this); 1927 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1928 1929 #if INCLUDE_ALL_GCS 1930 // We must flush the G1-related buffers before removing a thread 1931 // from the list of active threads. We must do this after any deferred 1932 // card marks have been flushed (above) so that any entries that are 1933 // added to the thread's dirty card queue as a result are not lost. 1934 if (UseG1GC) { 1935 flush_barrier_queues(); 1936 } 1937 #endif // INCLUDE_ALL_GCS 1938 1939 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1940 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1941 os::current_thread_id()); 1942 1943 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1944 Threads::remove(this); 1945 } 1946 1947 #if INCLUDE_ALL_GCS 1948 // Flush G1-related queues. 1949 void JavaThread::flush_barrier_queues() { 1950 satb_mark_queue().flush(); 1951 dirty_card_queue().flush(); 1952 } 1953 1954 void JavaThread::initialize_queues() { 1955 assert(!SafepointSynchronize::is_at_safepoint(), 1956 "we should not be at a safepoint"); 1957 1958 SATBMarkQueue& satb_queue = satb_mark_queue(); 1959 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1960 // The SATB queue should have been constructed with its active 1961 // field set to false. 1962 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1963 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1964 // If we are creating the thread during a marking cycle, we should 1965 // set the active field of the SATB queue to true. 1966 if (satb_queue_set.is_active()) { 1967 satb_queue.set_active(true); 1968 } 1969 1970 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1971 // The dirty card queue should have been constructed with its 1972 // active field set to true. 1973 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1974 } 1975 #endif // INCLUDE_ALL_GCS 1976 1977 void JavaThread::cleanup_failed_attach_current_thread() { 1978 if (get_thread_profiler() != NULL) { 1979 get_thread_profiler()->disengage(); 1980 ResourceMark rm; 1981 get_thread_profiler()->print(get_thread_name()); 1982 } 1983 1984 if (active_handles() != NULL) { 1985 JNIHandleBlock* block = active_handles(); 1986 set_active_handles(NULL); 1987 JNIHandleBlock::release_block(block); 1988 } 1989 1990 if (free_handle_block() != NULL) { 1991 JNIHandleBlock* block = free_handle_block(); 1992 set_free_handle_block(NULL); 1993 JNIHandleBlock::release_block(block); 1994 } 1995 1996 // These have to be removed while this is still a valid thread. 1997 remove_stack_guard_pages(); 1998 1999 if (UseTLAB) { 2000 tlab().make_parsable(true); // retire TLAB, if any 2001 } 2002 2003 #if INCLUDE_ALL_GCS 2004 if (UseG1GC) { 2005 flush_barrier_queues(); 2006 } 2007 #endif // INCLUDE_ALL_GCS 2008 2009 Threads::remove(this); 2010 delete this; 2011 } 2012 2013 2014 2015 2016 JavaThread* JavaThread::active() { 2017 Thread* thread = Thread::current(); 2018 if (thread->is_Java_thread()) { 2019 return (JavaThread*) thread; 2020 } else { 2021 assert(thread->is_VM_thread(), "this must be a vm thread"); 2022 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2023 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2024 assert(ret->is_Java_thread(), "must be a Java thread"); 2025 return ret; 2026 } 2027 } 2028 2029 bool JavaThread::is_lock_owned(address adr) const { 2030 if (Thread::is_lock_owned(adr)) return true; 2031 2032 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2033 if (chunk->contains(adr)) return true; 2034 } 2035 2036 return false; 2037 } 2038 2039 2040 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2041 chunk->set_next(monitor_chunks()); 2042 set_monitor_chunks(chunk); 2043 } 2044 2045 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2046 guarantee(monitor_chunks() != NULL, "must be non empty"); 2047 if (monitor_chunks() == chunk) { 2048 set_monitor_chunks(chunk->next()); 2049 } else { 2050 MonitorChunk* prev = monitor_chunks(); 2051 while (prev->next() != chunk) prev = prev->next(); 2052 prev->set_next(chunk->next()); 2053 } 2054 } 2055 2056 // JVM support. 2057 2058 // Note: this function shouldn't block if it's called in 2059 // _thread_in_native_trans state (such as from 2060 // check_special_condition_for_native_trans()). 2061 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2062 2063 if (has_last_Java_frame() && has_async_condition()) { 2064 // If we are at a polling page safepoint (not a poll return) 2065 // then we must defer async exception because live registers 2066 // will be clobbered by the exception path. Poll return is 2067 // ok because the call we a returning from already collides 2068 // with exception handling registers and so there is no issue. 2069 // (The exception handling path kills call result registers but 2070 // this is ok since the exception kills the result anyway). 2071 2072 if (is_at_poll_safepoint()) { 2073 // if the code we are returning to has deoptimized we must defer 2074 // the exception otherwise live registers get clobbered on the 2075 // exception path before deoptimization is able to retrieve them. 2076 // 2077 RegisterMap map(this, false); 2078 frame caller_fr = last_frame().sender(&map); 2079 assert(caller_fr.is_compiled_frame(), "what?"); 2080 if (caller_fr.is_deoptimized_frame()) { 2081 log_info(exceptions)("deferred async exception at compiled safepoint"); 2082 return; 2083 } 2084 } 2085 } 2086 2087 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2088 if (condition == _no_async_condition) { 2089 // Conditions have changed since has_special_runtime_exit_condition() 2090 // was called: 2091 // - if we were here only because of an external suspend request, 2092 // then that was taken care of above (or cancelled) so we are done 2093 // - if we were here because of another async request, then it has 2094 // been cleared between the has_special_runtime_exit_condition() 2095 // and now so again we are done 2096 return; 2097 } 2098 2099 // Check for pending async. exception 2100 if (_pending_async_exception != NULL) { 2101 // Only overwrite an already pending exception, if it is not a threadDeath. 2102 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2103 2104 // We cannot call Exceptions::_throw(...) here because we cannot block 2105 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2106 2107 if (log_is_enabled(Info, exceptions)) { 2108 ResourceMark rm; 2109 outputStream* logstream = Log(exceptions)::info_stream(); 2110 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2111 if (has_last_Java_frame()) { 2112 frame f = last_frame(); 2113 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2114 } 2115 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2116 } 2117 _pending_async_exception = NULL; 2118 clear_has_async_exception(); 2119 } 2120 } 2121 2122 if (check_unsafe_error && 2123 condition == _async_unsafe_access_error && !has_pending_exception()) { 2124 condition = _no_async_condition; // done 2125 switch (thread_state()) { 2126 case _thread_in_vm: { 2127 JavaThread* THREAD = this; 2128 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2129 } 2130 case _thread_in_native: { 2131 ThreadInVMfromNative tiv(this); 2132 JavaThread* THREAD = this; 2133 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2134 } 2135 case _thread_in_Java: { 2136 ThreadInVMfromJava tiv(this); 2137 JavaThread* THREAD = this; 2138 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2139 } 2140 default: 2141 ShouldNotReachHere(); 2142 } 2143 } 2144 2145 assert(condition == _no_async_condition || has_pending_exception() || 2146 (!check_unsafe_error && condition == _async_unsafe_access_error), 2147 "must have handled the async condition, if no exception"); 2148 } 2149 2150 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2151 // 2152 // Check for pending external suspend. Internal suspend requests do 2153 // not use handle_special_runtime_exit_condition(). 2154 // If JNIEnv proxies are allowed, don't self-suspend if the target 2155 // thread is not the current thread. In older versions of jdbx, jdbx 2156 // threads could call into the VM with another thread's JNIEnv so we 2157 // can be here operating on behalf of a suspended thread (4432884). 2158 bool do_self_suspend = is_external_suspend_with_lock(); 2159 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2160 // 2161 // Because thread is external suspended the safepoint code will count 2162 // thread as at a safepoint. This can be odd because we can be here 2163 // as _thread_in_Java which would normally transition to _thread_blocked 2164 // at a safepoint. We would like to mark the thread as _thread_blocked 2165 // before calling java_suspend_self like all other callers of it but 2166 // we must then observe proper safepoint protocol. (We can't leave 2167 // _thread_blocked with a safepoint in progress). However we can be 2168 // here as _thread_in_native_trans so we can't use a normal transition 2169 // constructor/destructor pair because they assert on that type of 2170 // transition. We could do something like: 2171 // 2172 // JavaThreadState state = thread_state(); 2173 // set_thread_state(_thread_in_vm); 2174 // { 2175 // ThreadBlockInVM tbivm(this); 2176 // java_suspend_self() 2177 // } 2178 // set_thread_state(_thread_in_vm_trans); 2179 // if (safepoint) block; 2180 // set_thread_state(state); 2181 // 2182 // but that is pretty messy. Instead we just go with the way the 2183 // code has worked before and note that this is the only path to 2184 // java_suspend_self that doesn't put the thread in _thread_blocked 2185 // mode. 2186 2187 frame_anchor()->make_walkable(this); 2188 java_suspend_self(); 2189 2190 // We might be here for reasons in addition to the self-suspend request 2191 // so check for other async requests. 2192 } 2193 2194 if (check_asyncs) { 2195 check_and_handle_async_exceptions(); 2196 } 2197 } 2198 2199 void JavaThread::send_thread_stop(oop java_throwable) { 2200 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2201 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2202 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2203 2204 // Do not throw asynchronous exceptions against the compiler thread 2205 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2206 if (!can_call_java()) return; 2207 2208 { 2209 // Actually throw the Throwable against the target Thread - however 2210 // only if there is no thread death exception installed already. 2211 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2212 // If the topmost frame is a runtime stub, then we are calling into 2213 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2214 // must deoptimize the caller before continuing, as the compiled exception handler table 2215 // may not be valid 2216 if (has_last_Java_frame()) { 2217 frame f = last_frame(); 2218 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2219 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2220 RegisterMap reg_map(this, UseBiasedLocking); 2221 frame compiled_frame = f.sender(®_map); 2222 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2223 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2224 } 2225 } 2226 } 2227 2228 // Set async. pending exception in thread. 2229 set_pending_async_exception(java_throwable); 2230 2231 if (log_is_enabled(Info, exceptions)) { 2232 ResourceMark rm; 2233 log_info(exceptions)("Pending Async. exception installed of type: %s", 2234 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2235 } 2236 // for AbortVMOnException flag 2237 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2238 } 2239 } 2240 2241 2242 // Interrupt thread so it will wake up from a potential wait() 2243 Thread::interrupt(this); 2244 } 2245 2246 // External suspension mechanism. 2247 // 2248 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2249 // to any VM_locks and it is at a transition 2250 // Self-suspension will happen on the transition out of the vm. 2251 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2252 // 2253 // Guarantees on return: 2254 // + Target thread will not execute any new bytecode (that's why we need to 2255 // force a safepoint) 2256 // + Target thread will not enter any new monitors 2257 // 2258 void JavaThread::java_suspend() { 2259 { MutexLocker mu(Threads_lock); 2260 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2261 return; 2262 } 2263 } 2264 2265 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2266 if (!is_external_suspend()) { 2267 // a racing resume has cancelled us; bail out now 2268 return; 2269 } 2270 2271 // suspend is done 2272 uint32_t debug_bits = 0; 2273 // Warning: is_ext_suspend_completed() may temporarily drop the 2274 // SR_lock to allow the thread to reach a stable thread state if 2275 // it is currently in a transient thread state. 2276 if (is_ext_suspend_completed(false /* !called_by_wait */, 2277 SuspendRetryDelay, &debug_bits)) { 2278 return; 2279 } 2280 } 2281 2282 VM_ForceSafepoint vm_suspend; 2283 VMThread::execute(&vm_suspend); 2284 } 2285 2286 // Part II of external suspension. 2287 // A JavaThread self suspends when it detects a pending external suspend 2288 // request. This is usually on transitions. It is also done in places 2289 // where continuing to the next transition would surprise the caller, 2290 // e.g., monitor entry. 2291 // 2292 // Returns the number of times that the thread self-suspended. 2293 // 2294 // Note: DO NOT call java_suspend_self() when you just want to block current 2295 // thread. java_suspend_self() is the second stage of cooperative 2296 // suspension for external suspend requests and should only be used 2297 // to complete an external suspend request. 2298 // 2299 int JavaThread::java_suspend_self() { 2300 int ret = 0; 2301 2302 // we are in the process of exiting so don't suspend 2303 if (is_exiting()) { 2304 clear_external_suspend(); 2305 return ret; 2306 } 2307 2308 assert(_anchor.walkable() || 2309 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2310 "must have walkable stack"); 2311 2312 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2313 2314 assert(!this->is_ext_suspended(), 2315 "a thread trying to self-suspend should not already be suspended"); 2316 2317 if (this->is_suspend_equivalent()) { 2318 // If we are self-suspending as a result of the lifting of a 2319 // suspend equivalent condition, then the suspend_equivalent 2320 // flag is not cleared until we set the ext_suspended flag so 2321 // that wait_for_ext_suspend_completion() returns consistent 2322 // results. 2323 this->clear_suspend_equivalent(); 2324 } 2325 2326 // A racing resume may have cancelled us before we grabbed SR_lock 2327 // above. Or another external suspend request could be waiting for us 2328 // by the time we return from SR_lock()->wait(). The thread 2329 // that requested the suspension may already be trying to walk our 2330 // stack and if we return now, we can change the stack out from under 2331 // it. This would be a "bad thing (TM)" and cause the stack walker 2332 // to crash. We stay self-suspended until there are no more pending 2333 // external suspend requests. 2334 while (is_external_suspend()) { 2335 ret++; 2336 this->set_ext_suspended(); 2337 2338 // _ext_suspended flag is cleared by java_resume() 2339 while (is_ext_suspended()) { 2340 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2341 } 2342 } 2343 2344 return ret; 2345 } 2346 2347 #ifdef ASSERT 2348 // verify the JavaThread has not yet been published in the Threads::list, and 2349 // hence doesn't need protection from concurrent access at this stage 2350 void JavaThread::verify_not_published() { 2351 if (!Threads_lock->owned_by_self()) { 2352 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2353 assert(!Threads::includes(this), 2354 "java thread shouldn't have been published yet!"); 2355 } else { 2356 assert(!Threads::includes(this), 2357 "java thread shouldn't have been published yet!"); 2358 } 2359 } 2360 #endif 2361 2362 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2363 // progress or when _suspend_flags is non-zero. 2364 // Current thread needs to self-suspend if there is a suspend request and/or 2365 // block if a safepoint is in progress. 2366 // Async exception ISN'T checked. 2367 // Note only the ThreadInVMfromNative transition can call this function 2368 // directly and when thread state is _thread_in_native_trans 2369 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2370 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2371 2372 JavaThread *curJT = JavaThread::current(); 2373 bool do_self_suspend = thread->is_external_suspend(); 2374 2375 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2376 2377 // If JNIEnv proxies are allowed, don't self-suspend if the target 2378 // thread is not the current thread. In older versions of jdbx, jdbx 2379 // threads could call into the VM with another thread's JNIEnv so we 2380 // can be here operating on behalf of a suspended thread (4432884). 2381 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2382 JavaThreadState state = thread->thread_state(); 2383 2384 // We mark this thread_blocked state as a suspend-equivalent so 2385 // that a caller to is_ext_suspend_completed() won't be confused. 2386 // The suspend-equivalent state is cleared by java_suspend_self(). 2387 thread->set_suspend_equivalent(); 2388 2389 // If the safepoint code sees the _thread_in_native_trans state, it will 2390 // wait until the thread changes to other thread state. There is no 2391 // guarantee on how soon we can obtain the SR_lock and complete the 2392 // self-suspend request. It would be a bad idea to let safepoint wait for 2393 // too long. Temporarily change the state to _thread_blocked to 2394 // let the VM thread know that this thread is ready for GC. The problem 2395 // of changing thread state is that safepoint could happen just after 2396 // java_suspend_self() returns after being resumed, and VM thread will 2397 // see the _thread_blocked state. We must check for safepoint 2398 // after restoring the state and make sure we won't leave while a safepoint 2399 // is in progress. 2400 thread->set_thread_state(_thread_blocked); 2401 thread->java_suspend_self(); 2402 thread->set_thread_state(state); 2403 // Make sure new state is seen by VM thread 2404 if (os::is_MP()) { 2405 if (UseMembar) { 2406 // Force a fence between the write above and read below 2407 OrderAccess::fence(); 2408 } else { 2409 // Must use this rather than serialization page in particular on Windows 2410 InterfaceSupport::serialize_memory(thread); 2411 } 2412 } 2413 } 2414 2415 if (SafepointSynchronize::do_call_back()) { 2416 // If we are safepointing, then block the caller which may not be 2417 // the same as the target thread (see above). 2418 SafepointSynchronize::block(curJT); 2419 } 2420 2421 if (thread->is_deopt_suspend()) { 2422 thread->clear_deopt_suspend(); 2423 RegisterMap map(thread, false); 2424 frame f = thread->last_frame(); 2425 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2426 f = f.sender(&map); 2427 } 2428 if (f.id() == thread->must_deopt_id()) { 2429 thread->clear_must_deopt_id(); 2430 f.deoptimize(thread); 2431 } else { 2432 fatal("missed deoptimization!"); 2433 } 2434 } 2435 } 2436 2437 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2438 // progress or when _suspend_flags is non-zero. 2439 // Current thread needs to self-suspend if there is a suspend request and/or 2440 // block if a safepoint is in progress. 2441 // Also check for pending async exception (not including unsafe access error). 2442 // Note only the native==>VM/Java barriers can call this function and when 2443 // thread state is _thread_in_native_trans. 2444 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2445 check_safepoint_and_suspend_for_native_trans(thread); 2446 2447 if (thread->has_async_exception()) { 2448 // We are in _thread_in_native_trans state, don't handle unsafe 2449 // access error since that may block. 2450 thread->check_and_handle_async_exceptions(false); 2451 } 2452 } 2453 2454 // This is a variant of the normal 2455 // check_special_condition_for_native_trans with slightly different 2456 // semantics for use by critical native wrappers. It does all the 2457 // normal checks but also performs the transition back into 2458 // thread_in_Java state. This is required so that critical natives 2459 // can potentially block and perform a GC if they are the last thread 2460 // exiting the GCLocker. 2461 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2462 check_special_condition_for_native_trans(thread); 2463 2464 // Finish the transition 2465 thread->set_thread_state(_thread_in_Java); 2466 2467 if (thread->do_critical_native_unlock()) { 2468 ThreadInVMfromJavaNoAsyncException tiv(thread); 2469 GCLocker::unlock_critical(thread); 2470 thread->clear_critical_native_unlock(); 2471 } 2472 } 2473 2474 // We need to guarantee the Threads_lock here, since resumes are not 2475 // allowed during safepoint synchronization 2476 // Can only resume from an external suspension 2477 void JavaThread::java_resume() { 2478 assert_locked_or_safepoint(Threads_lock); 2479 2480 // Sanity check: thread is gone, has started exiting or the thread 2481 // was not externally suspended. 2482 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2483 return; 2484 } 2485 2486 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2487 2488 clear_external_suspend(); 2489 2490 if (is_ext_suspended()) { 2491 clear_ext_suspended(); 2492 SR_lock()->notify_all(); 2493 } 2494 } 2495 2496 size_t JavaThread::_stack_red_zone_size = 0; 2497 size_t JavaThread::_stack_yellow_zone_size = 0; 2498 size_t JavaThread::_stack_reserved_zone_size = 0; 2499 size_t JavaThread::_stack_shadow_zone_size = 0; 2500 2501 void JavaThread::create_stack_guard_pages() { 2502 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2503 address low_addr = stack_end(); 2504 size_t len = stack_guard_zone_size(); 2505 2506 int must_commit = os::must_commit_stack_guard_pages(); 2507 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2508 2509 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2510 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2511 return; 2512 } 2513 2514 if (os::guard_memory((char *) low_addr, len)) { 2515 _stack_guard_state = stack_guard_enabled; 2516 } else { 2517 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2518 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2519 if (os::uncommit_memory((char *) low_addr, len)) { 2520 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2521 } 2522 return; 2523 } 2524 2525 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2526 PTR_FORMAT "-" PTR_FORMAT ".", 2527 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2528 } 2529 2530 void JavaThread::remove_stack_guard_pages() { 2531 assert(Thread::current() == this, "from different thread"); 2532 if (_stack_guard_state == stack_guard_unused) return; 2533 address low_addr = stack_end(); 2534 size_t len = stack_guard_zone_size(); 2535 2536 if (os::must_commit_stack_guard_pages()) { 2537 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2538 _stack_guard_state = stack_guard_unused; 2539 } else { 2540 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2541 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2542 return; 2543 } 2544 } else { 2545 if (_stack_guard_state == stack_guard_unused) return; 2546 if (os::unguard_memory((char *) low_addr, len)) { 2547 _stack_guard_state = stack_guard_unused; 2548 } else { 2549 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2550 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2551 return; 2552 } 2553 } 2554 2555 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2556 PTR_FORMAT "-" PTR_FORMAT ".", 2557 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2558 } 2559 2560 void JavaThread::enable_stack_reserved_zone() { 2561 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2562 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2563 2564 // The base notation is from the stack's point of view, growing downward. 2565 // We need to adjust it to work correctly with guard_memory() 2566 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2567 2568 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2569 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2570 2571 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2572 _stack_guard_state = stack_guard_enabled; 2573 } else { 2574 warning("Attempt to guard stack reserved zone failed."); 2575 } 2576 enable_register_stack_guard(); 2577 } 2578 2579 void JavaThread::disable_stack_reserved_zone() { 2580 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2581 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2582 2583 // Simply return if called for a thread that does not use guard pages. 2584 if (_stack_guard_state == stack_guard_unused) return; 2585 2586 // The base notation is from the stack's point of view, growing downward. 2587 // We need to adjust it to work correctly with guard_memory() 2588 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2589 2590 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2591 _stack_guard_state = stack_guard_reserved_disabled; 2592 } else { 2593 warning("Attempt to unguard stack reserved zone failed."); 2594 } 2595 disable_register_stack_guard(); 2596 } 2597 2598 void JavaThread::enable_stack_yellow_reserved_zone() { 2599 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2600 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2601 2602 // The base notation is from the stacks point of view, growing downward. 2603 // We need to adjust it to work correctly with guard_memory() 2604 address base = stack_red_zone_base(); 2605 2606 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2607 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2608 2609 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2610 _stack_guard_state = stack_guard_enabled; 2611 } else { 2612 warning("Attempt to guard stack yellow zone failed."); 2613 } 2614 enable_register_stack_guard(); 2615 } 2616 2617 void JavaThread::disable_stack_yellow_reserved_zone() { 2618 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2619 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2620 2621 // Simply return if called for a thread that does not use guard pages. 2622 if (_stack_guard_state == stack_guard_unused) return; 2623 2624 // The base notation is from the stacks point of view, growing downward. 2625 // We need to adjust it to work correctly with guard_memory() 2626 address base = stack_red_zone_base(); 2627 2628 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2629 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2630 } else { 2631 warning("Attempt to unguard stack yellow zone failed."); 2632 } 2633 disable_register_stack_guard(); 2634 } 2635 2636 void JavaThread::enable_stack_red_zone() { 2637 // The base notation is from the stacks point of view, growing downward. 2638 // We need to adjust it to work correctly with guard_memory() 2639 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2640 address base = stack_red_zone_base() - stack_red_zone_size(); 2641 2642 guarantee(base < stack_base(), "Error calculating stack red zone"); 2643 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2644 2645 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2646 warning("Attempt to guard stack red zone failed."); 2647 } 2648 } 2649 2650 void JavaThread::disable_stack_red_zone() { 2651 // The base notation is from the stacks point of view, growing downward. 2652 // We need to adjust it to work correctly with guard_memory() 2653 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2654 address base = stack_red_zone_base() - stack_red_zone_size(); 2655 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2656 warning("Attempt to unguard stack red zone failed."); 2657 } 2658 } 2659 2660 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2661 // ignore is there is no stack 2662 if (!has_last_Java_frame()) return; 2663 // traverse the stack frames. Starts from top frame. 2664 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2665 frame* fr = fst.current(); 2666 f(fr, fst.register_map()); 2667 } 2668 } 2669 2670 2671 #ifndef PRODUCT 2672 // Deoptimization 2673 // Function for testing deoptimization 2674 void JavaThread::deoptimize() { 2675 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2676 StackFrameStream fst(this, UseBiasedLocking); 2677 bool deopt = false; // Dump stack only if a deopt actually happens. 2678 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2679 // Iterate over all frames in the thread and deoptimize 2680 for (; !fst.is_done(); fst.next()) { 2681 if (fst.current()->can_be_deoptimized()) { 2682 2683 if (only_at) { 2684 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2685 // consists of comma or carriage return separated numbers so 2686 // search for the current bci in that string. 2687 address pc = fst.current()->pc(); 2688 nmethod* nm = (nmethod*) fst.current()->cb(); 2689 ScopeDesc* sd = nm->scope_desc_at(pc); 2690 char buffer[8]; 2691 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2692 size_t len = strlen(buffer); 2693 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2694 while (found != NULL) { 2695 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2696 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2697 // Check that the bci found is bracketed by terminators. 2698 break; 2699 } 2700 found = strstr(found + 1, buffer); 2701 } 2702 if (!found) { 2703 continue; 2704 } 2705 } 2706 2707 if (DebugDeoptimization && !deopt) { 2708 deopt = true; // One-time only print before deopt 2709 tty->print_cr("[BEFORE Deoptimization]"); 2710 trace_frames(); 2711 trace_stack(); 2712 } 2713 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2714 } 2715 } 2716 2717 if (DebugDeoptimization && deopt) { 2718 tty->print_cr("[AFTER Deoptimization]"); 2719 trace_frames(); 2720 } 2721 } 2722 2723 2724 // Make zombies 2725 void JavaThread::make_zombies() { 2726 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2727 if (fst.current()->can_be_deoptimized()) { 2728 // it is a Java nmethod 2729 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2730 nm->make_not_entrant(); 2731 } 2732 } 2733 } 2734 #endif // PRODUCT 2735 2736 2737 void JavaThread::deoptimized_wrt_marked_nmethods() { 2738 if (!has_last_Java_frame()) return; 2739 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2740 StackFrameStream fst(this, UseBiasedLocking); 2741 for (; !fst.is_done(); fst.next()) { 2742 if (fst.current()->should_be_deoptimized()) { 2743 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2744 } 2745 } 2746 } 2747 2748 2749 // If the caller is a NamedThread, then remember, in the current scope, 2750 // the given JavaThread in its _processed_thread field. 2751 class RememberProcessedThread: public StackObj { 2752 NamedThread* _cur_thr; 2753 public: 2754 RememberProcessedThread(JavaThread* jthr) { 2755 Thread* thread = Thread::current(); 2756 if (thread->is_Named_thread()) { 2757 _cur_thr = (NamedThread *)thread; 2758 _cur_thr->set_processed_thread(jthr); 2759 } else { 2760 _cur_thr = NULL; 2761 } 2762 } 2763 2764 ~RememberProcessedThread() { 2765 if (_cur_thr) { 2766 _cur_thr->set_processed_thread(NULL); 2767 } 2768 } 2769 }; 2770 2771 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2772 // Verify that the deferred card marks have been flushed. 2773 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2774 2775 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2776 // since there may be more than one thread using each ThreadProfiler. 2777 2778 // Traverse the GCHandles 2779 Thread::oops_do(f, cf); 2780 2781 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2782 2783 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2784 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2785 2786 if (has_last_Java_frame()) { 2787 // Record JavaThread to GC thread 2788 RememberProcessedThread rpt(this); 2789 2790 // Traverse the privileged stack 2791 if (_privileged_stack_top != NULL) { 2792 _privileged_stack_top->oops_do(f); 2793 } 2794 2795 // traverse the registered growable array 2796 if (_array_for_gc != NULL) { 2797 for (int index = 0; index < _array_for_gc->length(); index++) { 2798 f->do_oop(_array_for_gc->adr_at(index)); 2799 } 2800 } 2801 2802 // Traverse the monitor chunks 2803 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2804 chunk->oops_do(f); 2805 } 2806 2807 // Traverse the execution stack 2808 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2809 fst.current()->oops_do(f, cf, fst.register_map()); 2810 } 2811 } 2812 2813 // callee_target is never live across a gc point so NULL it here should 2814 // it still contain a methdOop. 2815 2816 set_callee_target(NULL); 2817 2818 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2819 // If we have deferred set_locals there might be oops waiting to be 2820 // written 2821 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2822 if (list != NULL) { 2823 for (int i = 0; i < list->length(); i++) { 2824 list->at(i)->oops_do(f); 2825 } 2826 } 2827 2828 // Traverse instance variables at the end since the GC may be moving things 2829 // around using this function 2830 f->do_oop((oop*) &_threadObj); 2831 f->do_oop((oop*) &_vm_result); 2832 f->do_oop((oop*) &_exception_oop); 2833 f->do_oop((oop*) &_pending_async_exception); 2834 2835 if (jvmti_thread_state() != NULL) { 2836 jvmti_thread_state()->oops_do(f); 2837 } 2838 } 2839 2840 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2841 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2842 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2843 2844 if (has_last_Java_frame()) { 2845 // Traverse the execution stack 2846 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2847 fst.current()->nmethods_do(cf); 2848 } 2849 } 2850 } 2851 2852 void JavaThread::metadata_do(void f(Metadata*)) { 2853 if (has_last_Java_frame()) { 2854 // Traverse the execution stack to call f() on the methods in the stack 2855 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2856 fst.current()->metadata_do(f); 2857 } 2858 } else if (is_Compiler_thread()) { 2859 // need to walk ciMetadata in current compile tasks to keep alive. 2860 CompilerThread* ct = (CompilerThread*)this; 2861 if (ct->env() != NULL) { 2862 ct->env()->metadata_do(f); 2863 } 2864 if (ct->task() != NULL) { 2865 ct->task()->metadata_do(f); 2866 } 2867 } 2868 } 2869 2870 // Printing 2871 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2872 switch (_thread_state) { 2873 case _thread_uninitialized: return "_thread_uninitialized"; 2874 case _thread_new: return "_thread_new"; 2875 case _thread_new_trans: return "_thread_new_trans"; 2876 case _thread_in_native: return "_thread_in_native"; 2877 case _thread_in_native_trans: return "_thread_in_native_trans"; 2878 case _thread_in_vm: return "_thread_in_vm"; 2879 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2880 case _thread_in_Java: return "_thread_in_Java"; 2881 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2882 case _thread_blocked: return "_thread_blocked"; 2883 case _thread_blocked_trans: return "_thread_blocked_trans"; 2884 default: return "unknown thread state"; 2885 } 2886 } 2887 2888 #ifndef PRODUCT 2889 void JavaThread::print_thread_state_on(outputStream *st) const { 2890 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2891 }; 2892 void JavaThread::print_thread_state() const { 2893 print_thread_state_on(tty); 2894 } 2895 #endif // PRODUCT 2896 2897 // Called by Threads::print() for VM_PrintThreads operation 2898 void JavaThread::print_on(outputStream *st) const { 2899 st->print_raw("\""); 2900 st->print_raw(get_thread_name()); 2901 st->print_raw("\" "); 2902 oop thread_oop = threadObj(); 2903 if (thread_oop != NULL) { 2904 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2905 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2906 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2907 } 2908 Thread::print_on(st); 2909 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2910 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2911 if (thread_oop != NULL) { 2912 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2913 } 2914 #ifndef PRODUCT 2915 print_thread_state_on(st); 2916 _safepoint_state->print_on(st); 2917 #endif // PRODUCT 2918 if (is_Compiler_thread()) { 2919 CompilerThread* ct = (CompilerThread*)this; 2920 if (ct->task() != NULL) { 2921 st->print(" Compiling: "); 2922 ct->task()->print(st, NULL, true, false); 2923 } else { 2924 st->print(" No compile task"); 2925 } 2926 st->cr(); 2927 } 2928 } 2929 2930 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2931 st->print("%s", get_thread_name_string(buf, buflen)); 2932 } 2933 2934 // Called by fatal error handler. The difference between this and 2935 // JavaThread::print() is that we can't grab lock or allocate memory. 2936 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2937 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2938 oop thread_obj = threadObj(); 2939 if (thread_obj != NULL) { 2940 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2941 } 2942 st->print(" ["); 2943 st->print("%s", _get_thread_state_name(_thread_state)); 2944 if (osthread()) { 2945 st->print(", id=%d", osthread()->thread_id()); 2946 } 2947 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2948 p2i(stack_end()), p2i(stack_base())); 2949 st->print("]"); 2950 return; 2951 } 2952 2953 // Verification 2954 2955 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2956 2957 void JavaThread::verify() { 2958 // Verify oops in the thread. 2959 oops_do(&VerifyOopClosure::verify_oop, NULL); 2960 2961 // Verify the stack frames. 2962 frames_do(frame_verify); 2963 } 2964 2965 // CR 6300358 (sub-CR 2137150) 2966 // Most callers of this method assume that it can't return NULL but a 2967 // thread may not have a name whilst it is in the process of attaching to 2968 // the VM - see CR 6412693, and there are places where a JavaThread can be 2969 // seen prior to having it's threadObj set (eg JNI attaching threads and 2970 // if vm exit occurs during initialization). These cases can all be accounted 2971 // for such that this method never returns NULL. 2972 const char* JavaThread::get_thread_name() const { 2973 #ifdef ASSERT 2974 // early safepoints can hit while current thread does not yet have TLS 2975 if (!SafepointSynchronize::is_at_safepoint()) { 2976 Thread *cur = Thread::current(); 2977 if (!(cur->is_Java_thread() && cur == this)) { 2978 // Current JavaThreads are allowed to get their own name without 2979 // the Threads_lock. 2980 assert_locked_or_safepoint(Threads_lock); 2981 } 2982 } 2983 #endif // ASSERT 2984 return get_thread_name_string(); 2985 } 2986 2987 // Returns a non-NULL representation of this thread's name, or a suitable 2988 // descriptive string if there is no set name 2989 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2990 const char* name_str; 2991 oop thread_obj = threadObj(); 2992 if (thread_obj != NULL) { 2993 oop name = java_lang_Thread::name(thread_obj); 2994 if (name != NULL) { 2995 if (buf == NULL) { 2996 name_str = java_lang_String::as_utf8_string(name); 2997 } else { 2998 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2999 } 3000 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3001 name_str = "<no-name - thread is attaching>"; 3002 } else { 3003 name_str = Thread::name(); 3004 } 3005 } else { 3006 name_str = Thread::name(); 3007 } 3008 assert(name_str != NULL, "unexpected NULL thread name"); 3009 return name_str; 3010 } 3011 3012 3013 const char* JavaThread::get_threadgroup_name() const { 3014 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3015 oop thread_obj = threadObj(); 3016 if (thread_obj != NULL) { 3017 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3018 if (thread_group != NULL) { 3019 // ThreadGroup.name can be null 3020 return java_lang_ThreadGroup::name(thread_group); 3021 } 3022 } 3023 return NULL; 3024 } 3025 3026 const char* JavaThread::get_parent_name() const { 3027 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3028 oop thread_obj = threadObj(); 3029 if (thread_obj != NULL) { 3030 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3031 if (thread_group != NULL) { 3032 oop parent = java_lang_ThreadGroup::parent(thread_group); 3033 if (parent != NULL) { 3034 // ThreadGroup.name can be null 3035 return java_lang_ThreadGroup::name(parent); 3036 } 3037 } 3038 } 3039 return NULL; 3040 } 3041 3042 ThreadPriority JavaThread::java_priority() const { 3043 oop thr_oop = threadObj(); 3044 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3045 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3046 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3047 return priority; 3048 } 3049 3050 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3051 3052 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3053 // Link Java Thread object <-> C++ Thread 3054 3055 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3056 // and put it into a new Handle. The Handle "thread_oop" can then 3057 // be used to pass the C++ thread object to other methods. 3058 3059 // Set the Java level thread object (jthread) field of the 3060 // new thread (a JavaThread *) to C++ thread object using the 3061 // "thread_oop" handle. 3062 3063 // Set the thread field (a JavaThread *) of the 3064 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3065 3066 Handle thread_oop(Thread::current(), 3067 JNIHandles::resolve_non_null(jni_thread)); 3068 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3069 "must be initialized"); 3070 set_threadObj(thread_oop()); 3071 java_lang_Thread::set_thread(thread_oop(), this); 3072 3073 if (prio == NoPriority) { 3074 prio = java_lang_Thread::priority(thread_oop()); 3075 assert(prio != NoPriority, "A valid priority should be present"); 3076 } 3077 3078 // Push the Java priority down to the native thread; needs Threads_lock 3079 Thread::set_priority(this, prio); 3080 3081 prepare_ext(); 3082 3083 // Add the new thread to the Threads list and set it in motion. 3084 // We must have threads lock in order to call Threads::add. 3085 // It is crucial that we do not block before the thread is 3086 // added to the Threads list for if a GC happens, then the java_thread oop 3087 // will not be visited by GC. 3088 Threads::add(this); 3089 } 3090 3091 oop JavaThread::current_park_blocker() { 3092 // Support for JSR-166 locks 3093 oop thread_oop = threadObj(); 3094 if (thread_oop != NULL && 3095 JDK_Version::current().supports_thread_park_blocker()) { 3096 return java_lang_Thread::park_blocker(thread_oop); 3097 } 3098 return NULL; 3099 } 3100 3101 3102 void JavaThread::print_stack_on(outputStream* st) { 3103 if (!has_last_Java_frame()) return; 3104 ResourceMark rm; 3105 HandleMark hm; 3106 3107 RegisterMap reg_map(this); 3108 vframe* start_vf = last_java_vframe(®_map); 3109 int count = 0; 3110 for (vframe* f = start_vf; f; f = f->sender()) { 3111 if (f->is_java_frame()) { 3112 javaVFrame* jvf = javaVFrame::cast(f); 3113 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3114 3115 // Print out lock information 3116 if (JavaMonitorsInStackTrace) { 3117 jvf->print_lock_info_on(st, count); 3118 } 3119 } else { 3120 // Ignore non-Java frames 3121 } 3122 3123 // Bail-out case for too deep stacks 3124 count++; 3125 if (MaxJavaStackTraceDepth == count) return; 3126 } 3127 } 3128 3129 3130 // JVMTI PopFrame support 3131 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3132 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3133 if (in_bytes(size_in_bytes) != 0) { 3134 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3135 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3136 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3137 } 3138 } 3139 3140 void* JavaThread::popframe_preserved_args() { 3141 return _popframe_preserved_args; 3142 } 3143 3144 ByteSize JavaThread::popframe_preserved_args_size() { 3145 return in_ByteSize(_popframe_preserved_args_size); 3146 } 3147 3148 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3149 int sz = in_bytes(popframe_preserved_args_size()); 3150 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3151 return in_WordSize(sz / wordSize); 3152 } 3153 3154 void JavaThread::popframe_free_preserved_args() { 3155 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3156 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3157 _popframe_preserved_args = NULL; 3158 _popframe_preserved_args_size = 0; 3159 } 3160 3161 #ifndef PRODUCT 3162 3163 void JavaThread::trace_frames() { 3164 tty->print_cr("[Describe stack]"); 3165 int frame_no = 1; 3166 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3167 tty->print(" %d. ", frame_no++); 3168 fst.current()->print_value_on(tty, this); 3169 tty->cr(); 3170 } 3171 } 3172 3173 class PrintAndVerifyOopClosure: public OopClosure { 3174 protected: 3175 template <class T> inline void do_oop_work(T* p) { 3176 oop obj = oopDesc::load_decode_heap_oop(p); 3177 if (obj == NULL) return; 3178 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3179 if (obj->is_oop_or_null()) { 3180 if (obj->is_objArray()) { 3181 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3182 } else { 3183 obj->print(); 3184 } 3185 } else { 3186 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3187 } 3188 tty->cr(); 3189 } 3190 public: 3191 virtual void do_oop(oop* p) { do_oop_work(p); } 3192 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3193 }; 3194 3195 3196 static void oops_print(frame* f, const RegisterMap *map) { 3197 PrintAndVerifyOopClosure print; 3198 f->print_value(); 3199 f->oops_do(&print, NULL, (RegisterMap*)map); 3200 } 3201 3202 // Print our all the locations that contain oops and whether they are 3203 // valid or not. This useful when trying to find the oldest frame 3204 // where an oop has gone bad since the frame walk is from youngest to 3205 // oldest. 3206 void JavaThread::trace_oops() { 3207 tty->print_cr("[Trace oops]"); 3208 frames_do(oops_print); 3209 } 3210 3211 3212 #ifdef ASSERT 3213 // Print or validate the layout of stack frames 3214 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3215 ResourceMark rm; 3216 PRESERVE_EXCEPTION_MARK; 3217 FrameValues values; 3218 int frame_no = 0; 3219 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3220 fst.current()->describe(values, ++frame_no); 3221 if (depth == frame_no) break; 3222 } 3223 if (validate_only) { 3224 values.validate(); 3225 } else { 3226 tty->print_cr("[Describe stack layout]"); 3227 values.print(this); 3228 } 3229 } 3230 #endif 3231 3232 void JavaThread::trace_stack_from(vframe* start_vf) { 3233 ResourceMark rm; 3234 int vframe_no = 1; 3235 for (vframe* f = start_vf; f; f = f->sender()) { 3236 if (f->is_java_frame()) { 3237 javaVFrame::cast(f)->print_activation(vframe_no++); 3238 } else { 3239 f->print(); 3240 } 3241 if (vframe_no > StackPrintLimit) { 3242 tty->print_cr("...<more frames>..."); 3243 return; 3244 } 3245 } 3246 } 3247 3248 3249 void JavaThread::trace_stack() { 3250 if (!has_last_Java_frame()) return; 3251 ResourceMark rm; 3252 HandleMark hm; 3253 RegisterMap reg_map(this); 3254 trace_stack_from(last_java_vframe(®_map)); 3255 } 3256 3257 3258 #endif // PRODUCT 3259 3260 3261 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3262 assert(reg_map != NULL, "a map must be given"); 3263 frame f = last_frame(); 3264 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3265 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3266 } 3267 return NULL; 3268 } 3269 3270 3271 Klass* JavaThread::security_get_caller_class(int depth) { 3272 vframeStream vfst(this); 3273 vfst.security_get_caller_frame(depth); 3274 if (!vfst.at_end()) { 3275 return vfst.method()->method_holder(); 3276 } 3277 return NULL; 3278 } 3279 3280 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3281 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3282 CompileBroker::compiler_thread_loop(); 3283 } 3284 3285 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3286 NMethodSweeper::sweeper_loop(); 3287 } 3288 3289 // Create a CompilerThread 3290 CompilerThread::CompilerThread(CompileQueue* queue, 3291 CompilerCounters* counters) 3292 : JavaThread(&compiler_thread_entry) { 3293 _env = NULL; 3294 _log = NULL; 3295 _task = NULL; 3296 _queue = queue; 3297 _counters = counters; 3298 _buffer_blob = NULL; 3299 _compiler = NULL; 3300 3301 #ifndef PRODUCT 3302 _ideal_graph_printer = NULL; 3303 #endif 3304 } 3305 3306 bool CompilerThread::can_call_java() const { 3307 return _compiler != NULL && _compiler->is_jvmci(); 3308 } 3309 3310 // Create sweeper thread 3311 CodeCacheSweeperThread::CodeCacheSweeperThread() 3312 : JavaThread(&sweeper_thread_entry) { 3313 _scanned_compiled_method = NULL; 3314 } 3315 3316 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3317 JavaThread::oops_do(f, cf); 3318 if (_scanned_compiled_method != NULL && cf != NULL) { 3319 // Safepoints can occur when the sweeper is scanning an nmethod so 3320 // process it here to make sure it isn't unloaded in the middle of 3321 // a scan. 3322 cf->do_code_blob(_scanned_compiled_method); 3323 } 3324 } 3325 3326 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3327 JavaThread::nmethods_do(cf); 3328 if (_scanned_compiled_method != NULL && cf != NULL) { 3329 // Safepoints can occur when the sweeper is scanning an nmethod so 3330 // process it here to make sure it isn't unloaded in the middle of 3331 // a scan. 3332 cf->do_code_blob(_scanned_compiled_method); 3333 } 3334 } 3335 3336 3337 // ======= Threads ======== 3338 3339 // The Threads class links together all active threads, and provides 3340 // operations over all threads. It is protected by its own Mutex 3341 // lock, which is also used in other contexts to protect thread 3342 // operations from having the thread being operated on from exiting 3343 // and going away unexpectedly (e.g., safepoint synchronization) 3344 3345 JavaThread* Threads::_thread_list = NULL; 3346 int Threads::_number_of_threads = 0; 3347 int Threads::_number_of_non_daemon_threads = 0; 3348 int Threads::_return_code = 0; 3349 int Threads::_thread_claim_parity = 0; 3350 size_t JavaThread::_stack_size_at_create = 0; 3351 #ifdef ASSERT 3352 bool Threads::_vm_complete = false; 3353 #endif 3354 3355 // All JavaThreads 3356 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3357 3358 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3359 void Threads::threads_do(ThreadClosure* tc) { 3360 assert_locked_or_safepoint(Threads_lock); 3361 // ALL_JAVA_THREADS iterates through all JavaThreads 3362 ALL_JAVA_THREADS(p) { 3363 tc->do_thread(p); 3364 } 3365 // Someday we could have a table or list of all non-JavaThreads. 3366 // For now, just manually iterate through them. 3367 tc->do_thread(VMThread::vm_thread()); 3368 Universe::heap()->gc_threads_do(tc); 3369 WatcherThread *wt = WatcherThread::watcher_thread(); 3370 // Strictly speaking, the following NULL check isn't sufficient to make sure 3371 // the data for WatcherThread is still valid upon being examined. However, 3372 // considering that WatchThread terminates when the VM is on the way to 3373 // exit at safepoint, the chance of the above is extremely small. The right 3374 // way to prevent termination of WatcherThread would be to acquire 3375 // Terminator_lock, but we can't do that without violating the lock rank 3376 // checking in some cases. 3377 if (wt != NULL) { 3378 tc->do_thread(wt); 3379 } 3380 3381 // If CompilerThreads ever become non-JavaThreads, add them here 3382 } 3383 3384 // The system initialization in the library has three phases. 3385 // 3386 // Phase 1: java.lang.System class initialization 3387 // java.lang.System is a primordial class loaded and initialized 3388 // by the VM early during startup. java.lang.System.<clinit> 3389 // only does registerNatives and keeps the rest of the class 3390 // initialization work later until thread initialization completes. 3391 // 3392 // System.initPhase1 initializes the system properties, the static 3393 // fields in, out, and err. Set up java signal handlers, OS-specific 3394 // system settings, and thread group of the main thread. 3395 static void call_initPhase1(TRAPS) { 3396 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3397 JavaValue result(T_VOID); 3398 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3399 vmSymbols::void_method_signature(), CHECK); 3400 } 3401 3402 // Phase 2. Module system initialization 3403 // This will initialize the module system. Only java.base classes 3404 // can be loaded until phase 2 completes. 3405 // 3406 // Call System.initPhase2 after the compiler initialization and jsr292 3407 // classes get initialized because module initialization runs a lot of java 3408 // code, that for performance reasons, should be compiled. Also, this will 3409 // enable the startup code to use lambda and other language features in this 3410 // phase and onward. 3411 // 3412 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3413 static void call_initPhase2(TRAPS) { 3414 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime)); 3415 3416 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3417 3418 JavaValue result(T_INT); 3419 JavaCallArguments args; 3420 args.push_int(DisplayVMOutputToStderr); 3421 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3422 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3423 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3424 if (result.get_jint() != JNI_OK) { 3425 vm_exit_during_initialization(); // no message or exception 3426 } 3427 3428 universe_post_module_init(); 3429 } 3430 3431 // Phase 3. final setup - set security manager, system class loader and TCCL 3432 // 3433 // This will instantiate and set the security manager, set the system class 3434 // loader as well as the thread context class loader. The security manager 3435 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3436 // other modules or the application's classpath. 3437 static void call_initPhase3(TRAPS) { 3438 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3439 JavaValue result(T_VOID); 3440 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3441 vmSymbols::void_method_signature(), CHECK); 3442 } 3443 3444 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3445 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3446 3447 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3448 create_vm_init_libraries(); 3449 } 3450 3451 initialize_class(vmSymbols::java_lang_String(), CHECK); 3452 3453 // Inject CompactStrings value after the static initializers for String ran. 3454 java_lang_String::set_compact_strings(CompactStrings); 3455 3456 // Initialize java_lang.System (needed before creating the thread) 3457 initialize_class(vmSymbols::java_lang_System(), CHECK); 3458 // The VM creates & returns objects of this class. Make sure it's initialized. 3459 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3460 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3461 Handle thread_group = create_initial_thread_group(CHECK); 3462 Universe::set_main_thread_group(thread_group()); 3463 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3464 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3465 main_thread->set_threadObj(thread_object); 3466 // Set thread status to running since main thread has 3467 // been started and running. 3468 java_lang_Thread::set_thread_status(thread_object, 3469 java_lang_Thread::RUNNABLE); 3470 3471 // The VM creates objects of this class. 3472 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3473 3474 // The VM preresolves methods to these classes. Make sure that they get initialized 3475 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3476 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3477 3478 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3479 call_initPhase1(CHECK); 3480 3481 // get the Java runtime name after java.lang.System is initialized 3482 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3483 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3484 3485 // an instance of OutOfMemory exception has been allocated earlier 3486 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3487 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3488 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3489 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3490 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3491 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3492 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3493 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3494 } 3495 3496 void Threads::initialize_jsr292_core_classes(TRAPS) { 3497 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3498 3499 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3500 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3501 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3502 } 3503 3504 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3505 extern void JDK_Version_init(); 3506 3507 // Preinitialize version info. 3508 VM_Version::early_initialize(); 3509 3510 // Check version 3511 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3512 3513 // Initialize library-based TLS 3514 ThreadLocalStorage::init(); 3515 3516 // Initialize the output stream module 3517 ostream_init(); 3518 3519 // Process java launcher properties. 3520 Arguments::process_sun_java_launcher_properties(args); 3521 3522 // Initialize the os module 3523 os::init(); 3524 3525 // Record VM creation timing statistics 3526 TraceVmCreationTime create_vm_timer; 3527 create_vm_timer.start(); 3528 3529 // Initialize system properties. 3530 Arguments::init_system_properties(); 3531 3532 // So that JDK version can be used as a discriminator when parsing arguments 3533 JDK_Version_init(); 3534 3535 // Update/Initialize System properties after JDK version number is known 3536 Arguments::init_version_specific_system_properties(); 3537 3538 // Make sure to initialize log configuration *before* parsing arguments 3539 LogConfiguration::initialize(create_vm_timer.begin_time()); 3540 3541 // Parse arguments 3542 jint parse_result = Arguments::parse(args); 3543 if (parse_result != JNI_OK) return parse_result; 3544 3545 os::init_before_ergo(); 3546 3547 jint ergo_result = Arguments::apply_ergo(); 3548 if (ergo_result != JNI_OK) return ergo_result; 3549 3550 // Final check of all ranges after ergonomics which may change values. 3551 if (!CommandLineFlagRangeList::check_ranges()) { 3552 return JNI_EINVAL; 3553 } 3554 3555 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3556 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3557 if (!constraint_result) { 3558 return JNI_EINVAL; 3559 } 3560 3561 CommandLineFlagWriteableList::mark_startup(); 3562 3563 if (PauseAtStartup) { 3564 os::pause(); 3565 } 3566 3567 HOTSPOT_VM_INIT_BEGIN(); 3568 3569 // Timing (must come after argument parsing) 3570 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3571 3572 // Initialize the os module after parsing the args 3573 jint os_init_2_result = os::init_2(); 3574 if (os_init_2_result != JNI_OK) return os_init_2_result; 3575 3576 jint adjust_after_os_result = Arguments::adjust_after_os(); 3577 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3578 3579 // Initialize output stream logging 3580 ostream_init_log(); 3581 3582 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3583 // Must be before create_vm_init_agents() 3584 if (Arguments::init_libraries_at_startup()) { 3585 convert_vm_init_libraries_to_agents(); 3586 } 3587 3588 // Launch -agentlib/-agentpath and converted -Xrun agents 3589 if (Arguments::init_agents_at_startup()) { 3590 create_vm_init_agents(); 3591 } 3592 3593 // Initialize Threads state 3594 _thread_list = NULL; 3595 _number_of_threads = 0; 3596 _number_of_non_daemon_threads = 0; 3597 3598 // Initialize global data structures and create system classes in heap 3599 vm_init_globals(); 3600 3601 #if INCLUDE_JVMCI 3602 if (JVMCICounterSize > 0) { 3603 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3604 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3605 } else { 3606 JavaThread::_jvmci_old_thread_counters = NULL; 3607 } 3608 #endif // INCLUDE_JVMCI 3609 3610 // Attach the main thread to this os thread 3611 JavaThread* main_thread = new JavaThread(); 3612 main_thread->set_thread_state(_thread_in_vm); 3613 main_thread->initialize_thread_current(); 3614 // must do this before set_active_handles 3615 main_thread->record_stack_base_and_size(); 3616 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3617 3618 if (!main_thread->set_as_starting_thread()) { 3619 vm_shutdown_during_initialization( 3620 "Failed necessary internal allocation. Out of swap space"); 3621 delete main_thread; 3622 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3623 return JNI_ENOMEM; 3624 } 3625 3626 // Enable guard page *after* os::create_main_thread(), otherwise it would 3627 // crash Linux VM, see notes in os_linux.cpp. 3628 main_thread->create_stack_guard_pages(); 3629 3630 // Initialize Java-Level synchronization subsystem 3631 ObjectMonitor::Initialize(); 3632 3633 // Initialize global modules 3634 jint status = init_globals(); 3635 if (status != JNI_OK) { 3636 delete main_thread; 3637 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3638 return status; 3639 } 3640 3641 if (TRACE_INITIALIZE() != JNI_OK) { 3642 vm_exit_during_initialization("Failed to initialize tracing backend"); 3643 } 3644 3645 // Should be done after the heap is fully created 3646 main_thread->cache_global_variables(); 3647 3648 HandleMark hm; 3649 3650 { MutexLocker mu(Threads_lock); 3651 Threads::add(main_thread); 3652 } 3653 3654 // Any JVMTI raw monitors entered in onload will transition into 3655 // real raw monitor. VM is setup enough here for raw monitor enter. 3656 JvmtiExport::transition_pending_onload_raw_monitors(); 3657 3658 // Create the VMThread 3659 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3660 3661 VMThread::create(); 3662 Thread* vmthread = VMThread::vm_thread(); 3663 3664 if (!os::create_thread(vmthread, os::vm_thread)) { 3665 vm_exit_during_initialization("Cannot create VM thread. " 3666 "Out of system resources."); 3667 } 3668 3669 // Wait for the VM thread to become ready, and VMThread::run to initialize 3670 // Monitors can have spurious returns, must always check another state flag 3671 { 3672 MutexLocker ml(Notify_lock); 3673 os::start_thread(vmthread); 3674 while (vmthread->active_handles() == NULL) { 3675 Notify_lock->wait(); 3676 } 3677 } 3678 } 3679 3680 assert(Universe::is_fully_initialized(), "not initialized"); 3681 if (VerifyDuringStartup) { 3682 // Make sure we're starting with a clean slate. 3683 VM_Verify verify_op; 3684 VMThread::execute(&verify_op); 3685 } 3686 3687 Thread* THREAD = Thread::current(); 3688 3689 // At this point, the Universe is initialized, but we have not executed 3690 // any byte code. Now is a good time (the only time) to dump out the 3691 // internal state of the JVM for sharing. 3692 if (DumpSharedSpaces) { 3693 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3694 ShouldNotReachHere(); 3695 } 3696 3697 // Always call even when there are not JVMTI environments yet, since environments 3698 // may be attached late and JVMTI must track phases of VM execution 3699 JvmtiExport::enter_early_start_phase(); 3700 3701 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3702 JvmtiExport::post_early_vm_start(); 3703 3704 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3705 3706 // We need this for ClassDataSharing - the initial vm.info property is set 3707 // with the default value of CDS "sharing" which may be reset through 3708 // command line options. 3709 reset_vm_info_property(CHECK_JNI_ERR); 3710 3711 quicken_jni_functions(); 3712 3713 // No more stub generation allowed after that point. 3714 StubCodeDesc::freeze(); 3715 3716 // Set flag that basic initialization has completed. Used by exceptions and various 3717 // debug stuff, that does not work until all basic classes have been initialized. 3718 set_init_completed(); 3719 3720 LogConfiguration::post_initialize(); 3721 Metaspace::post_initialize(); 3722 3723 HOTSPOT_VM_INIT_END(); 3724 3725 // record VM initialization completion time 3726 #if INCLUDE_MANAGEMENT 3727 Management::record_vm_init_completed(); 3728 #endif // INCLUDE_MANAGEMENT 3729 3730 // Signal Dispatcher needs to be started before VMInit event is posted 3731 os::signal_init(CHECK_JNI_ERR); 3732 3733 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3734 if (!DisableAttachMechanism) { 3735 AttachListener::vm_start(); 3736 if (StartAttachListener || AttachListener::init_at_startup()) { 3737 AttachListener::init(); 3738 } 3739 } 3740 3741 // Launch -Xrun agents 3742 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3743 // back-end can launch with -Xdebug -Xrunjdwp. 3744 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3745 create_vm_init_libraries(); 3746 } 3747 3748 if (CleanChunkPoolAsync) { 3749 Chunk::start_chunk_pool_cleaner_task(); 3750 } 3751 3752 // initialize compiler(s) 3753 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3754 CompileBroker::compilation_init(CHECK_JNI_ERR); 3755 #endif 3756 3757 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3758 // It is done after compilers are initialized, because otherwise compilations of 3759 // signature polymorphic MH intrinsics can be missed 3760 // (see SystemDictionary::find_method_handle_intrinsic). 3761 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3762 3763 // This will initialize the module system. Only java.base classes can be 3764 // loaded until phase 2 completes 3765 call_initPhase2(CHECK_JNI_ERR); 3766 3767 // Always call even when there are not JVMTI environments yet, since environments 3768 // may be attached late and JVMTI must track phases of VM execution 3769 JvmtiExport::enter_start_phase(); 3770 3771 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3772 JvmtiExport::post_vm_start(); 3773 3774 // Final system initialization including security manager and system class loader 3775 call_initPhase3(CHECK_JNI_ERR); 3776 3777 // cache the system class loader 3778 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3779 3780 #if INCLUDE_JVMCI 3781 if (EnableJVMCI) { 3782 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3783 // The JVMCI Java initialization code will read this flag and 3784 // do the printing if it's set. 3785 bool init = JVMCIPrintProperties; 3786 3787 if (!init) { 3788 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3789 // compilations via JVMCI will not actually block until JVMCI is initialized. 3790 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3791 } 3792 3793 if (init) { 3794 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3795 } 3796 } 3797 #endif 3798 3799 // Always call even when there are not JVMTI environments yet, since environments 3800 // may be attached late and JVMTI must track phases of VM execution 3801 JvmtiExport::enter_live_phase(); 3802 3803 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3804 JvmtiExport::post_vm_initialized(); 3805 3806 if (TRACE_START() != JNI_OK) { 3807 vm_exit_during_initialization("Failed to start tracing backend."); 3808 } 3809 3810 #if INCLUDE_MANAGEMENT 3811 Management::initialize(THREAD); 3812 3813 if (HAS_PENDING_EXCEPTION) { 3814 // management agent fails to start possibly due to 3815 // configuration problem and is responsible for printing 3816 // stack trace if appropriate. Simply exit VM. 3817 vm_exit(1); 3818 } 3819 #endif // INCLUDE_MANAGEMENT 3820 3821 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3822 if (MemProfiling) MemProfiler::engage(); 3823 StatSampler::engage(); 3824 if (CheckJNICalls) JniPeriodicChecker::engage(); 3825 3826 BiasedLocking::init(); 3827 3828 #if INCLUDE_RTM_OPT 3829 RTMLockingCounters::init(); 3830 #endif 3831 3832 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3833 call_postVMInitHook(THREAD); 3834 // The Java side of PostVMInitHook.run must deal with all 3835 // exceptions and provide means of diagnosis. 3836 if (HAS_PENDING_EXCEPTION) { 3837 CLEAR_PENDING_EXCEPTION; 3838 } 3839 } 3840 3841 { 3842 MutexLocker ml(PeriodicTask_lock); 3843 // Make sure the WatcherThread can be started by WatcherThread::start() 3844 // or by dynamic enrollment. 3845 WatcherThread::make_startable(); 3846 // Start up the WatcherThread if there are any periodic tasks 3847 // NOTE: All PeriodicTasks should be registered by now. If they 3848 // aren't, late joiners might appear to start slowly (we might 3849 // take a while to process their first tick). 3850 if (PeriodicTask::num_tasks() > 0) { 3851 WatcherThread::start(); 3852 } 3853 } 3854 3855 create_vm_timer.end(); 3856 #ifdef ASSERT 3857 _vm_complete = true; 3858 #endif 3859 return JNI_OK; 3860 } 3861 3862 // type for the Agent_OnLoad and JVM_OnLoad entry points 3863 extern "C" { 3864 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3865 } 3866 // Find a command line agent library and return its entry point for 3867 // -agentlib: -agentpath: -Xrun 3868 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3869 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3870 const char *on_load_symbols[], 3871 size_t num_symbol_entries) { 3872 OnLoadEntry_t on_load_entry = NULL; 3873 void *library = NULL; 3874 3875 if (!agent->valid()) { 3876 char buffer[JVM_MAXPATHLEN]; 3877 char ebuf[1024] = ""; 3878 const char *name = agent->name(); 3879 const char *msg = "Could not find agent library "; 3880 3881 // First check to see if agent is statically linked into executable 3882 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3883 library = agent->os_lib(); 3884 } else if (agent->is_absolute_path()) { 3885 library = os::dll_load(name, ebuf, sizeof ebuf); 3886 if (library == NULL) { 3887 const char *sub_msg = " in absolute path, with error: "; 3888 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3889 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3890 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3891 // If we can't find the agent, exit. 3892 vm_exit_during_initialization(buf, NULL); 3893 FREE_C_HEAP_ARRAY(char, buf); 3894 } 3895 } else { 3896 // Try to load the agent from the standard dll directory 3897 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3898 name)) { 3899 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3900 } 3901 if (library == NULL) { // Try the local directory 3902 char ns[1] = {0}; 3903 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3904 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3905 } 3906 if (library == NULL) { 3907 const char *sub_msg = " on the library path, with error: "; 3908 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3909 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3910 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3911 // If we can't find the agent, exit. 3912 vm_exit_during_initialization(buf, NULL); 3913 FREE_C_HEAP_ARRAY(char, buf); 3914 } 3915 } 3916 } 3917 agent->set_os_lib(library); 3918 agent->set_valid(); 3919 } 3920 3921 // Find the OnLoad function. 3922 on_load_entry = 3923 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3924 false, 3925 on_load_symbols, 3926 num_symbol_entries)); 3927 return on_load_entry; 3928 } 3929 3930 // Find the JVM_OnLoad entry point 3931 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3932 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3933 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3934 } 3935 3936 // Find the Agent_OnLoad entry point 3937 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3938 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3939 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3940 } 3941 3942 // For backwards compatibility with -Xrun 3943 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3944 // treated like -agentpath: 3945 // Must be called before agent libraries are created 3946 void Threads::convert_vm_init_libraries_to_agents() { 3947 AgentLibrary* agent; 3948 AgentLibrary* next; 3949 3950 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3951 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3952 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3953 3954 // If there is an JVM_OnLoad function it will get called later, 3955 // otherwise see if there is an Agent_OnLoad 3956 if (on_load_entry == NULL) { 3957 on_load_entry = lookup_agent_on_load(agent); 3958 if (on_load_entry != NULL) { 3959 // switch it to the agent list -- so that Agent_OnLoad will be called, 3960 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3961 Arguments::convert_library_to_agent(agent); 3962 } else { 3963 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3964 } 3965 } 3966 } 3967 } 3968 3969 // Create agents for -agentlib: -agentpath: and converted -Xrun 3970 // Invokes Agent_OnLoad 3971 // Called very early -- before JavaThreads exist 3972 void Threads::create_vm_init_agents() { 3973 extern struct JavaVM_ main_vm; 3974 AgentLibrary* agent; 3975 3976 JvmtiExport::enter_onload_phase(); 3977 3978 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3979 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3980 3981 if (on_load_entry != NULL) { 3982 // Invoke the Agent_OnLoad function 3983 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3984 if (err != JNI_OK) { 3985 vm_exit_during_initialization("agent library failed to init", agent->name()); 3986 } 3987 } else { 3988 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3989 } 3990 } 3991 JvmtiExport::enter_primordial_phase(); 3992 } 3993 3994 extern "C" { 3995 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3996 } 3997 3998 void Threads::shutdown_vm_agents() { 3999 // Send any Agent_OnUnload notifications 4000 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4001 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4002 extern struct JavaVM_ main_vm; 4003 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4004 4005 // Find the Agent_OnUnload function. 4006 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4007 os::find_agent_function(agent, 4008 false, 4009 on_unload_symbols, 4010 num_symbol_entries)); 4011 4012 // Invoke the Agent_OnUnload function 4013 if (unload_entry != NULL) { 4014 JavaThread* thread = JavaThread::current(); 4015 ThreadToNativeFromVM ttn(thread); 4016 HandleMark hm(thread); 4017 (*unload_entry)(&main_vm); 4018 } 4019 } 4020 } 4021 4022 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4023 // Invokes JVM_OnLoad 4024 void Threads::create_vm_init_libraries() { 4025 extern struct JavaVM_ main_vm; 4026 AgentLibrary* agent; 4027 4028 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4029 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4030 4031 if (on_load_entry != NULL) { 4032 // Invoke the JVM_OnLoad function 4033 JavaThread* thread = JavaThread::current(); 4034 ThreadToNativeFromVM ttn(thread); 4035 HandleMark hm(thread); 4036 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4037 if (err != JNI_OK) { 4038 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4039 } 4040 } else { 4041 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4042 } 4043 } 4044 } 4045 4046 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4047 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4048 4049 JavaThread* java_thread = NULL; 4050 // Sequential search for now. Need to do better optimization later. 4051 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4052 oop tobj = thread->threadObj(); 4053 if (!thread->is_exiting() && 4054 tobj != NULL && 4055 java_tid == java_lang_Thread::thread_id(tobj)) { 4056 java_thread = thread; 4057 break; 4058 } 4059 } 4060 return java_thread; 4061 } 4062 4063 4064 // Last thread running calls java.lang.Shutdown.shutdown() 4065 void JavaThread::invoke_shutdown_hooks() { 4066 HandleMark hm(this); 4067 4068 // We could get here with a pending exception, if so clear it now. 4069 if (this->has_pending_exception()) { 4070 this->clear_pending_exception(); 4071 } 4072 4073 EXCEPTION_MARK; 4074 Klass* shutdown_klass = 4075 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4076 THREAD); 4077 if (shutdown_klass != NULL) { 4078 // SystemDictionary::resolve_or_null will return null if there was 4079 // an exception. If we cannot load the Shutdown class, just don't 4080 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4081 // and finalizers (if runFinalizersOnExit is set) won't be run. 4082 // Note that if a shutdown hook was registered or runFinalizersOnExit 4083 // was called, the Shutdown class would have already been loaded 4084 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4085 JavaValue result(T_VOID); 4086 JavaCalls::call_static(&result, 4087 shutdown_klass, 4088 vmSymbols::shutdown_method_name(), 4089 vmSymbols::void_method_signature(), 4090 THREAD); 4091 } 4092 CLEAR_PENDING_EXCEPTION; 4093 } 4094 4095 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4096 // the program falls off the end of main(). Another VM exit path is through 4097 // vm_exit() when the program calls System.exit() to return a value or when 4098 // there is a serious error in VM. The two shutdown paths are not exactly 4099 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4100 // and VM_Exit op at VM level. 4101 // 4102 // Shutdown sequence: 4103 // + Shutdown native memory tracking if it is on 4104 // + Wait until we are the last non-daemon thread to execute 4105 // <-- every thing is still working at this moment --> 4106 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4107 // shutdown hooks, run finalizers if finalization-on-exit 4108 // + Call before_exit(), prepare for VM exit 4109 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4110 // currently the only user of this mechanism is File.deleteOnExit()) 4111 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4112 // post thread end and vm death events to JVMTI, 4113 // stop signal thread 4114 // + Call JavaThread::exit(), it will: 4115 // > release JNI handle blocks, remove stack guard pages 4116 // > remove this thread from Threads list 4117 // <-- no more Java code from this thread after this point --> 4118 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4119 // the compiler threads at safepoint 4120 // <-- do not use anything that could get blocked by Safepoint --> 4121 // + Disable tracing at JNI/JVM barriers 4122 // + Set _vm_exited flag for threads that are still running native code 4123 // + Delete this thread 4124 // + Call exit_globals() 4125 // > deletes tty 4126 // > deletes PerfMemory resources 4127 // + Return to caller 4128 4129 bool Threads::destroy_vm() { 4130 JavaThread* thread = JavaThread::current(); 4131 4132 #ifdef ASSERT 4133 _vm_complete = false; 4134 #endif 4135 // Wait until we are the last non-daemon thread to execute 4136 { MutexLocker nu(Threads_lock); 4137 while (Threads::number_of_non_daemon_threads() > 1) 4138 // This wait should make safepoint checks, wait without a timeout, 4139 // and wait as a suspend-equivalent condition. 4140 // 4141 // Note: If the FlatProfiler is running and this thread is waiting 4142 // for another non-daemon thread to finish, then the FlatProfiler 4143 // is waiting for the external suspend request on this thread to 4144 // complete. wait_for_ext_suspend_completion() will eventually 4145 // timeout, but that takes time. Making this wait a suspend- 4146 // equivalent condition solves that timeout problem. 4147 // 4148 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4149 Mutex::_as_suspend_equivalent_flag); 4150 } 4151 4152 // Hang forever on exit if we are reporting an error. 4153 if (ShowMessageBoxOnError && is_error_reported()) { 4154 os::infinite_sleep(); 4155 } 4156 os::wait_for_keypress_at_exit(); 4157 4158 // run Java level shutdown hooks 4159 thread->invoke_shutdown_hooks(); 4160 4161 before_exit(thread); 4162 4163 thread->exit(true); 4164 4165 // Stop VM thread. 4166 { 4167 // 4945125 The vm thread comes to a safepoint during exit. 4168 // GC vm_operations can get caught at the safepoint, and the 4169 // heap is unparseable if they are caught. Grab the Heap_lock 4170 // to prevent this. The GC vm_operations will not be able to 4171 // queue until after the vm thread is dead. After this point, 4172 // we'll never emerge out of the safepoint before the VM exits. 4173 4174 MutexLocker ml(Heap_lock); 4175 4176 VMThread::wait_for_vm_thread_exit(); 4177 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4178 VMThread::destroy(); 4179 } 4180 4181 // clean up ideal graph printers 4182 #if defined(COMPILER2) && !defined(PRODUCT) 4183 IdealGraphPrinter::clean_up(); 4184 #endif 4185 4186 // Now, all Java threads are gone except daemon threads. Daemon threads 4187 // running Java code or in VM are stopped by the Safepoint. However, 4188 // daemon threads executing native code are still running. But they 4189 // will be stopped at native=>Java/VM barriers. Note that we can't 4190 // simply kill or suspend them, as it is inherently deadlock-prone. 4191 4192 VM_Exit::set_vm_exited(); 4193 4194 notify_vm_shutdown(); 4195 4196 delete thread; 4197 4198 #if INCLUDE_JVMCI 4199 if (JVMCICounterSize > 0) { 4200 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4201 } 4202 #endif 4203 4204 // exit_globals() will delete tty 4205 exit_globals(); 4206 4207 LogConfiguration::finalize(); 4208 4209 return true; 4210 } 4211 4212 4213 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4214 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4215 return is_supported_jni_version(version); 4216 } 4217 4218 4219 jboolean Threads::is_supported_jni_version(jint version) { 4220 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4221 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4222 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4223 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4224 if (version == JNI_VERSION_9) return JNI_TRUE; 4225 return JNI_FALSE; 4226 } 4227 4228 4229 void Threads::add(JavaThread* p, bool force_daemon) { 4230 // The threads lock must be owned at this point 4231 assert_locked_or_safepoint(Threads_lock); 4232 4233 // See the comment for this method in thread.hpp for its purpose and 4234 // why it is called here. 4235 p->initialize_queues(); 4236 p->set_next(_thread_list); 4237 _thread_list = p; 4238 _number_of_threads++; 4239 oop threadObj = p->threadObj(); 4240 bool daemon = true; 4241 // Bootstrapping problem: threadObj can be null for initial 4242 // JavaThread (or for threads attached via JNI) 4243 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4244 _number_of_non_daemon_threads++; 4245 daemon = false; 4246 } 4247 4248 ThreadService::add_thread(p, daemon); 4249 4250 // Possible GC point. 4251 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4252 } 4253 4254 void Threads::remove(JavaThread* p) { 4255 // Extra scope needed for Thread_lock, so we can check 4256 // that we do not remove thread without safepoint code notice 4257 { MutexLocker ml(Threads_lock); 4258 4259 assert(includes(p), "p must be present"); 4260 4261 JavaThread* current = _thread_list; 4262 JavaThread* prev = NULL; 4263 4264 while (current != p) { 4265 prev = current; 4266 current = current->next(); 4267 } 4268 4269 if (prev) { 4270 prev->set_next(current->next()); 4271 } else { 4272 _thread_list = p->next(); 4273 } 4274 _number_of_threads--; 4275 oop threadObj = p->threadObj(); 4276 bool daemon = true; 4277 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4278 _number_of_non_daemon_threads--; 4279 daemon = false; 4280 4281 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4282 // on destroy_vm will wake up. 4283 if (number_of_non_daemon_threads() == 1) { 4284 Threads_lock->notify_all(); 4285 } 4286 } 4287 ThreadService::remove_thread(p, daemon); 4288 4289 // Make sure that safepoint code disregard this thread. This is needed since 4290 // the thread might mess around with locks after this point. This can cause it 4291 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4292 // of this thread since it is removed from the queue. 4293 p->set_terminated_value(); 4294 } // unlock Threads_lock 4295 4296 // Since Events::log uses a lock, we grab it outside the Threads_lock 4297 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4298 } 4299 4300 // Threads_lock must be held when this is called (or must be called during a safepoint) 4301 bool Threads::includes(JavaThread* p) { 4302 assert(Threads_lock->is_locked(), "sanity check"); 4303 ALL_JAVA_THREADS(q) { 4304 if (q == p) { 4305 return true; 4306 } 4307 } 4308 return false; 4309 } 4310 4311 // Operations on the Threads list for GC. These are not explicitly locked, 4312 // but the garbage collector must provide a safe context for them to run. 4313 // In particular, these things should never be called when the Threads_lock 4314 // is held by some other thread. (Note: the Safepoint abstraction also 4315 // uses the Threads_lock to guarantee this property. It also makes sure that 4316 // all threads gets blocked when exiting or starting). 4317 4318 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4319 ALL_JAVA_THREADS(p) { 4320 p->oops_do(f, cf); 4321 } 4322 VMThread::vm_thread()->oops_do(f, cf); 4323 } 4324 4325 void Threads::change_thread_claim_parity() { 4326 // Set the new claim parity. 4327 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4328 "Not in range."); 4329 _thread_claim_parity++; 4330 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4331 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4332 "Not in range."); 4333 } 4334 4335 #ifdef ASSERT 4336 void Threads::assert_all_threads_claimed() { 4337 ALL_JAVA_THREADS(p) { 4338 const int thread_parity = p->oops_do_parity(); 4339 assert((thread_parity == _thread_claim_parity), 4340 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4341 } 4342 } 4343 #endif // ASSERT 4344 4345 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4346 int cp = Threads::thread_claim_parity(); 4347 ALL_JAVA_THREADS(p) { 4348 if (p->claim_oops_do(is_par, cp)) { 4349 p->oops_do(f, cf); 4350 } 4351 } 4352 VMThread* vmt = VMThread::vm_thread(); 4353 if (vmt->claim_oops_do(is_par, cp)) { 4354 vmt->oops_do(f, cf); 4355 } 4356 } 4357 4358 #if INCLUDE_ALL_GCS 4359 // Used by ParallelScavenge 4360 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4361 ALL_JAVA_THREADS(p) { 4362 q->enqueue(new ThreadRootsTask(p)); 4363 } 4364 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4365 } 4366 4367 // Used by Parallel Old 4368 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4369 ALL_JAVA_THREADS(p) { 4370 q->enqueue(new ThreadRootsMarkingTask(p)); 4371 } 4372 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4373 } 4374 #endif // INCLUDE_ALL_GCS 4375 4376 void Threads::nmethods_do(CodeBlobClosure* cf) { 4377 ALL_JAVA_THREADS(p) { 4378 // This is used by the code cache sweeper to mark nmethods that are active 4379 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4380 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4381 if(!p->is_Code_cache_sweeper_thread()) { 4382 p->nmethods_do(cf); 4383 } 4384 } 4385 } 4386 4387 void Threads::metadata_do(void f(Metadata*)) { 4388 ALL_JAVA_THREADS(p) { 4389 p->metadata_do(f); 4390 } 4391 } 4392 4393 class ThreadHandlesClosure : public ThreadClosure { 4394 void (*_f)(Metadata*); 4395 public: 4396 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4397 virtual void do_thread(Thread* thread) { 4398 thread->metadata_handles_do(_f); 4399 } 4400 }; 4401 4402 void Threads::metadata_handles_do(void f(Metadata*)) { 4403 // Only walk the Handles in Thread. 4404 ThreadHandlesClosure handles_closure(f); 4405 threads_do(&handles_closure); 4406 } 4407 4408 void Threads::deoptimized_wrt_marked_nmethods() { 4409 ALL_JAVA_THREADS(p) { 4410 p->deoptimized_wrt_marked_nmethods(); 4411 } 4412 } 4413 4414 4415 // Get count Java threads that are waiting to enter the specified monitor. 4416 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4417 address monitor, 4418 bool doLock) { 4419 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4420 "must grab Threads_lock or be at safepoint"); 4421 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4422 4423 int i = 0; 4424 { 4425 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4426 ALL_JAVA_THREADS(p) { 4427 if (!p->can_call_java()) continue; 4428 4429 address pending = (address)p->current_pending_monitor(); 4430 if (pending == monitor) { // found a match 4431 if (i < count) result->append(p); // save the first count matches 4432 i++; 4433 } 4434 } 4435 } 4436 return result; 4437 } 4438 4439 4440 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4441 bool doLock) { 4442 assert(doLock || 4443 Threads_lock->owned_by_self() || 4444 SafepointSynchronize::is_at_safepoint(), 4445 "must grab Threads_lock or be at safepoint"); 4446 4447 // NULL owner means not locked so we can skip the search 4448 if (owner == NULL) return NULL; 4449 4450 { 4451 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4452 ALL_JAVA_THREADS(p) { 4453 // first, see if owner is the address of a Java thread 4454 if (owner == (address)p) return p; 4455 } 4456 } 4457 // Cannot assert on lack of success here since this function may be 4458 // used by code that is trying to report useful problem information 4459 // like deadlock detection. 4460 if (UseHeavyMonitors) return NULL; 4461 4462 // If we didn't find a matching Java thread and we didn't force use of 4463 // heavyweight monitors, then the owner is the stack address of the 4464 // Lock Word in the owning Java thread's stack. 4465 // 4466 JavaThread* the_owner = NULL; 4467 { 4468 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4469 ALL_JAVA_THREADS(q) { 4470 if (q->is_lock_owned(owner)) { 4471 the_owner = q; 4472 break; 4473 } 4474 } 4475 } 4476 // cannot assert on lack of success here; see above comment 4477 return the_owner; 4478 } 4479 4480 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4481 void Threads::print_on(outputStream* st, bool print_stacks, 4482 bool internal_format, bool print_concurrent_locks) { 4483 char buf[32]; 4484 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4485 4486 st->print_cr("Full thread dump %s (%s %s):", 4487 Abstract_VM_Version::vm_name(), 4488 Abstract_VM_Version::vm_release(), 4489 Abstract_VM_Version::vm_info_string()); 4490 st->cr(); 4491 4492 #if INCLUDE_SERVICES 4493 // Dump concurrent locks 4494 ConcurrentLocksDump concurrent_locks; 4495 if (print_concurrent_locks) { 4496 concurrent_locks.dump_at_safepoint(); 4497 } 4498 #endif // INCLUDE_SERVICES 4499 4500 ALL_JAVA_THREADS(p) { 4501 ResourceMark rm; 4502 p->print_on(st); 4503 if (print_stacks) { 4504 if (internal_format) { 4505 p->trace_stack(); 4506 } else { 4507 p->print_stack_on(st); 4508 } 4509 } 4510 st->cr(); 4511 #if INCLUDE_SERVICES 4512 if (print_concurrent_locks) { 4513 concurrent_locks.print_locks_on(p, st); 4514 } 4515 #endif // INCLUDE_SERVICES 4516 } 4517 4518 VMThread::vm_thread()->print_on(st); 4519 st->cr(); 4520 Universe::heap()->print_gc_threads_on(st); 4521 WatcherThread* wt = WatcherThread::watcher_thread(); 4522 if (wt != NULL) { 4523 wt->print_on(st); 4524 st->cr(); 4525 } 4526 st->flush(); 4527 } 4528 4529 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4530 int buflen, bool* found_current) { 4531 if (this_thread != NULL) { 4532 bool is_current = (current == this_thread); 4533 *found_current = *found_current || is_current; 4534 st->print("%s", is_current ? "=>" : " "); 4535 4536 st->print(PTR_FORMAT, p2i(this_thread)); 4537 st->print(" "); 4538 this_thread->print_on_error(st, buf, buflen); 4539 st->cr(); 4540 } 4541 } 4542 4543 class PrintOnErrorClosure : public ThreadClosure { 4544 outputStream* _st; 4545 Thread* _current; 4546 char* _buf; 4547 int _buflen; 4548 bool* _found_current; 4549 public: 4550 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4551 int buflen, bool* found_current) : 4552 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4553 4554 virtual void do_thread(Thread* thread) { 4555 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4556 } 4557 }; 4558 4559 // Threads::print_on_error() is called by fatal error handler. It's possible 4560 // that VM is not at safepoint and/or current thread is inside signal handler. 4561 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4562 // memory (even in resource area), it might deadlock the error handler. 4563 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4564 int buflen) { 4565 bool found_current = false; 4566 st->print_cr("Java Threads: ( => current thread )"); 4567 ALL_JAVA_THREADS(thread) { 4568 print_on_error(thread, st, current, buf, buflen, &found_current); 4569 } 4570 st->cr(); 4571 4572 st->print_cr("Other Threads:"); 4573 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4574 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4575 4576 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4577 Universe::heap()->gc_threads_do(&print_closure); 4578 4579 if (!found_current) { 4580 st->cr(); 4581 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4582 current->print_on_error(st, buf, buflen); 4583 st->cr(); 4584 } 4585 st->cr(); 4586 st->print_cr("Threads with active compile tasks:"); 4587 print_threads_compiling(st, buf, buflen); 4588 } 4589 4590 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4591 ALL_JAVA_THREADS(thread) { 4592 if (thread->is_Compiler_thread()) { 4593 CompilerThread* ct = (CompilerThread*) thread; 4594 if (ct->task() != NULL) { 4595 thread->print_name_on_error(st, buf, buflen); 4596 ct->task()->print(st, NULL, true, true); 4597 } 4598 } 4599 } 4600 } 4601 4602 4603 // Internal SpinLock and Mutex 4604 // Based on ParkEvent 4605 4606 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4607 // 4608 // We employ SpinLocks _only for low-contention, fixed-length 4609 // short-duration critical sections where we're concerned 4610 // about native mutex_t or HotSpot Mutex:: latency. 4611 // The mux construct provides a spin-then-block mutual exclusion 4612 // mechanism. 4613 // 4614 // Testing has shown that contention on the ListLock guarding gFreeList 4615 // is common. If we implement ListLock as a simple SpinLock it's common 4616 // for the JVM to devolve to yielding with little progress. This is true 4617 // despite the fact that the critical sections protected by ListLock are 4618 // extremely short. 4619 // 4620 // TODO-FIXME: ListLock should be of type SpinLock. 4621 // We should make this a 1st-class type, integrated into the lock 4622 // hierarchy as leaf-locks. Critically, the SpinLock structure 4623 // should have sufficient padding to avoid false-sharing and excessive 4624 // cache-coherency traffic. 4625 4626 4627 typedef volatile int SpinLockT; 4628 4629 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4630 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4631 return; // normal fast-path return 4632 } 4633 4634 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4635 TEVENT(SpinAcquire - ctx); 4636 int ctr = 0; 4637 int Yields = 0; 4638 for (;;) { 4639 while (*adr != 0) { 4640 ++ctr; 4641 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4642 if (Yields > 5) { 4643 os::naked_short_sleep(1); 4644 } else { 4645 os::naked_yield(); 4646 ++Yields; 4647 } 4648 } else { 4649 SpinPause(); 4650 } 4651 } 4652 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4653 } 4654 } 4655 4656 void Thread::SpinRelease(volatile int * adr) { 4657 assert(*adr != 0, "invariant"); 4658 OrderAccess::fence(); // guarantee at least release consistency. 4659 // Roach-motel semantics. 4660 // It's safe if subsequent LDs and STs float "up" into the critical section, 4661 // but prior LDs and STs within the critical section can't be allowed 4662 // to reorder or float past the ST that releases the lock. 4663 // Loads and stores in the critical section - which appear in program 4664 // order before the store that releases the lock - must also appear 4665 // before the store that releases the lock in memory visibility order. 4666 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4667 // the ST of 0 into the lock-word which releases the lock, so fence 4668 // more than covers this on all platforms. 4669 *adr = 0; 4670 } 4671 4672 // muxAcquire and muxRelease: 4673 // 4674 // * muxAcquire and muxRelease support a single-word lock-word construct. 4675 // The LSB of the word is set IFF the lock is held. 4676 // The remainder of the word points to the head of a singly-linked list 4677 // of threads blocked on the lock. 4678 // 4679 // * The current implementation of muxAcquire-muxRelease uses its own 4680 // dedicated Thread._MuxEvent instance. If we're interested in 4681 // minimizing the peak number of extant ParkEvent instances then 4682 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4683 // as certain invariants were satisfied. Specifically, care would need 4684 // to be taken with regards to consuming unpark() "permits". 4685 // A safe rule of thumb is that a thread would never call muxAcquire() 4686 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4687 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4688 // consume an unpark() permit intended for monitorenter, for instance. 4689 // One way around this would be to widen the restricted-range semaphore 4690 // implemented in park(). Another alternative would be to provide 4691 // multiple instances of the PlatformEvent() for each thread. One 4692 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4693 // 4694 // * Usage: 4695 // -- Only as leaf locks 4696 // -- for short-term locking only as muxAcquire does not perform 4697 // thread state transitions. 4698 // 4699 // Alternatives: 4700 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4701 // but with parking or spin-then-park instead of pure spinning. 4702 // * Use Taura-Oyama-Yonenzawa locks. 4703 // * It's possible to construct a 1-0 lock if we encode the lockword as 4704 // (List,LockByte). Acquire will CAS the full lockword while Release 4705 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4706 // acquiring threads use timers (ParkTimed) to detect and recover from 4707 // the stranding window. Thread/Node structures must be aligned on 256-byte 4708 // boundaries by using placement-new. 4709 // * Augment MCS with advisory back-link fields maintained with CAS(). 4710 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4711 // The validity of the backlinks must be ratified before we trust the value. 4712 // If the backlinks are invalid the exiting thread must back-track through the 4713 // the forward links, which are always trustworthy. 4714 // * Add a successor indication. The LockWord is currently encoded as 4715 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4716 // to provide the usual futile-wakeup optimization. 4717 // See RTStt for details. 4718 // * Consider schedctl.sc_nopreempt to cover the critical section. 4719 // 4720 4721 4722 typedef volatile intptr_t MutexT; // Mux Lock-word 4723 enum MuxBits { LOCKBIT = 1 }; 4724 4725 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4726 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4727 if (w == 0) return; 4728 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4729 return; 4730 } 4731 4732 TEVENT(muxAcquire - Contention); 4733 ParkEvent * const Self = Thread::current()->_MuxEvent; 4734 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4735 for (;;) { 4736 int its = (os::is_MP() ? 100 : 0) + 1; 4737 4738 // Optional spin phase: spin-then-park strategy 4739 while (--its >= 0) { 4740 w = *Lock; 4741 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4742 return; 4743 } 4744 } 4745 4746 Self->reset(); 4747 Self->OnList = intptr_t(Lock); 4748 // The following fence() isn't _strictly necessary as the subsequent 4749 // CAS() both serializes execution and ratifies the fetched *Lock value. 4750 OrderAccess::fence(); 4751 for (;;) { 4752 w = *Lock; 4753 if ((w & LOCKBIT) == 0) { 4754 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4755 Self->OnList = 0; // hygiene - allows stronger asserts 4756 return; 4757 } 4758 continue; // Interference -- *Lock changed -- Just retry 4759 } 4760 assert(w & LOCKBIT, "invariant"); 4761 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4762 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4763 } 4764 4765 while (Self->OnList != 0) { 4766 Self->park(); 4767 } 4768 } 4769 } 4770 4771 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4772 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4773 if (w == 0) return; 4774 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4775 return; 4776 } 4777 4778 TEVENT(muxAcquire - Contention); 4779 ParkEvent * ReleaseAfter = NULL; 4780 if (ev == NULL) { 4781 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4782 } 4783 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4784 for (;;) { 4785 guarantee(ev->OnList == 0, "invariant"); 4786 int its = (os::is_MP() ? 100 : 0) + 1; 4787 4788 // Optional spin phase: spin-then-park strategy 4789 while (--its >= 0) { 4790 w = *Lock; 4791 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4792 if (ReleaseAfter != NULL) { 4793 ParkEvent::Release(ReleaseAfter); 4794 } 4795 return; 4796 } 4797 } 4798 4799 ev->reset(); 4800 ev->OnList = intptr_t(Lock); 4801 // The following fence() isn't _strictly necessary as the subsequent 4802 // CAS() both serializes execution and ratifies the fetched *Lock value. 4803 OrderAccess::fence(); 4804 for (;;) { 4805 w = *Lock; 4806 if ((w & LOCKBIT) == 0) { 4807 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4808 ev->OnList = 0; 4809 // We call ::Release while holding the outer lock, thus 4810 // artificially lengthening the critical section. 4811 // Consider deferring the ::Release() until the subsequent unlock(), 4812 // after we've dropped the outer lock. 4813 if (ReleaseAfter != NULL) { 4814 ParkEvent::Release(ReleaseAfter); 4815 } 4816 return; 4817 } 4818 continue; // Interference -- *Lock changed -- Just retry 4819 } 4820 assert(w & LOCKBIT, "invariant"); 4821 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4822 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4823 } 4824 4825 while (ev->OnList != 0) { 4826 ev->park(); 4827 } 4828 } 4829 } 4830 4831 // Release() must extract a successor from the list and then wake that thread. 4832 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4833 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4834 // Release() would : 4835 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4836 // (B) Extract a successor from the private list "in-hand" 4837 // (C) attempt to CAS() the residual back into *Lock over null. 4838 // If there were any newly arrived threads and the CAS() would fail. 4839 // In that case Release() would detach the RATs, re-merge the list in-hand 4840 // with the RATs and repeat as needed. Alternately, Release() might 4841 // detach and extract a successor, but then pass the residual list to the wakee. 4842 // The wakee would be responsible for reattaching and remerging before it 4843 // competed for the lock. 4844 // 4845 // Both "pop" and DMR are immune from ABA corruption -- there can be 4846 // multiple concurrent pushers, but only one popper or detacher. 4847 // This implementation pops from the head of the list. This is unfair, 4848 // but tends to provide excellent throughput as hot threads remain hot. 4849 // (We wake recently run threads first). 4850 // 4851 // All paths through muxRelease() will execute a CAS. 4852 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4853 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4854 // executed within the critical section are complete and globally visible before the 4855 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4856 void Thread::muxRelease(volatile intptr_t * Lock) { 4857 for (;;) { 4858 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4859 assert(w & LOCKBIT, "invariant"); 4860 if (w == LOCKBIT) return; 4861 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4862 assert(List != NULL, "invariant"); 4863 assert(List->OnList == intptr_t(Lock), "invariant"); 4864 ParkEvent * const nxt = List->ListNext; 4865 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4866 4867 // The following CAS() releases the lock and pops the head element. 4868 // The CAS() also ratifies the previously fetched lock-word value. 4869 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4870 continue; 4871 } 4872 List->OnList = 0; 4873 OrderAccess::fence(); 4874 List->unpark(); 4875 return; 4876 } 4877 } 4878 4879 4880 void Threads::verify() { 4881 ALL_JAVA_THREADS(p) { 4882 p->verify(); 4883 } 4884 VMThread* thread = VMThread::vm_thread(); 4885 if (thread != NULL) thread->verify(); 4886 }