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.h" 54 #include "prims/jvm_misc.hpp" 55 #include "prims/jvmtiExport.hpp" 56 #include "prims/jvmtiThreadState.hpp" 57 #include "prims/privilegedStack.hpp" 58 #include "runtime/arguments.hpp" 59 #include "runtime/atomic.hpp" 60 #include "runtime/biasedLocking.hpp" 61 #include "runtime/commandLineFlagConstraintList.hpp" 62 #include "runtime/commandLineFlagWriteableList.hpp" 63 #include "runtime/commandLineFlagRangeList.hpp" 64 #include "runtime/deoptimization.hpp" 65 #include "runtime/fprofiler.hpp" 66 #include "runtime/frame.inline.hpp" 67 #include "runtime/globals.hpp" 68 #include "runtime/init.hpp" 69 #include "runtime/interfaceSupport.hpp" 70 #include "runtime/java.hpp" 71 #include "runtime/javaCalls.hpp" 72 #include "runtime/jniPeriodicChecker.hpp" 73 #include "runtime/timerTrace.hpp" 74 #include "runtime/memprofiler.hpp" 75 #include "runtime/mutexLocker.hpp" 76 #include "runtime/objectMonitor.hpp" 77 #include "runtime/orderAccess.inline.hpp" 78 #include "runtime/osThread.hpp" 79 #include "runtime/safepoint.hpp" 80 #include "runtime/sharedRuntime.hpp" 81 #include "runtime/statSampler.hpp" 82 #include "runtime/stubRoutines.hpp" 83 #include "runtime/sweeper.hpp" 84 #include "runtime/task.hpp" 85 #include "runtime/thread.inline.hpp" 86 #include "runtime/threadCritical.hpp" 87 #include "runtime/vframe.hpp" 88 #include "runtime/vframeArray.hpp" 89 #include "runtime/vframe_hp.hpp" 90 #include "runtime/vmThread.hpp" 91 #include "runtime/vm_operations.hpp" 92 #include "runtime/vm_version.hpp" 93 #include "services/attachListener.hpp" 94 #include "services/management.hpp" 95 #include "services/memTracker.hpp" 96 #include "services/threadService.hpp" 97 #include "trace/traceMacros.hpp" 98 #include "trace/tracing.hpp" 99 #include "utilities/defaultStream.hpp" 100 #include "utilities/dtrace.hpp" 101 #include "utilities/events.hpp" 102 #include "utilities/macros.hpp" 103 #include "utilities/preserveException.hpp" 104 #if INCLUDE_ALL_GCS 105 #include "gc/cms/concurrentMarkSweepThread.hpp" 106 #include "gc/g1/concurrentMarkThread.inline.hpp" 107 #include "gc/parallel/pcTasks.hpp" 108 #endif // INCLUDE_ALL_GCS 109 #if INCLUDE_JVMCI 110 #include "jvmci/jvmciCompiler.hpp" 111 #include "jvmci/jvmciRuntime.hpp" 112 #endif 113 #ifdef COMPILER1 114 #include "c1/c1_Compiler.hpp" 115 #endif 116 #ifdef COMPILER2 117 #include "opto/c2compiler.hpp" 118 #include "opto/idealGraphPrinter.hpp" 119 #endif 120 #if INCLUDE_RTM_OPT 121 #include "runtime/rtmLocking.hpp" 122 #endif 123 124 // Initialization after module runtime initialization 125 void universe_post_module_init(); // must happen after call_initPhase2 126 127 #ifdef DTRACE_ENABLED 128 129 // Only bother with this argument setup if dtrace is available 130 131 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 132 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 133 134 #define DTRACE_THREAD_PROBE(probe, javathread) \ 135 { \ 136 ResourceMark rm(this); \ 137 int len = 0; \ 138 const char* name = (javathread)->get_thread_name(); \ 139 len = strlen(name); \ 140 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 141 (char *) name, len, \ 142 java_lang_Thread::thread_id((javathread)->threadObj()), \ 143 (uintptr_t) (javathread)->osthread()->thread_id(), \ 144 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 145 } 146 147 #else // ndef DTRACE_ENABLED 148 149 #define DTRACE_THREAD_PROBE(probe, javathread) 150 151 #endif // ndef DTRACE_ENABLED 152 153 #ifndef USE_LIBRARY_BASED_TLS_ONLY 154 // Current thread is maintained as a thread-local variable 155 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 156 #endif 157 // Class hierarchy 158 // - Thread 159 // - VMThread 160 // - WatcherThread 161 // - ConcurrentMarkSweepThread 162 // - JavaThread 163 // - CompilerThread 164 165 // ======= Thread ======== 166 // Support for forcing alignment of thread objects for biased locking 167 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 168 if (UseBiasedLocking) { 169 const int alignment = markOopDesc::biased_lock_alignment; 170 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 171 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 172 : AllocateHeap(aligned_size, flags, CURRENT_PC, 173 AllocFailStrategy::RETURN_NULL); 174 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 175 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 176 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 177 "JavaThread alignment code overflowed allocated storage"); 178 if (aligned_addr != real_malloc_addr) { 179 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 180 p2i(real_malloc_addr), 181 p2i(aligned_addr)); 182 } 183 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 184 return aligned_addr; 185 } else { 186 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 187 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 188 } 189 } 190 191 void Thread::operator delete(void* p) { 192 if (UseBiasedLocking) { 193 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 194 FreeHeap(real_malloc_addr); 195 } else { 196 FreeHeap(p); 197 } 198 } 199 200 201 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 202 // JavaThread 203 204 205 Thread::Thread() { 206 // stack and get_thread 207 set_stack_base(NULL); 208 set_stack_size(0); 209 set_self_raw_id(0); 210 set_lgrp_id(-1); 211 DEBUG_ONLY(clear_suspendible_thread();) 212 213 // allocated data structures 214 set_osthread(NULL); 215 set_resource_area(new (mtThread)ResourceArea()); 216 DEBUG_ONLY(_current_resource_mark = NULL;) 217 set_handle_area(new (mtThread) HandleArea(NULL)); 218 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 219 set_active_handles(NULL); 220 set_free_handle_block(NULL); 221 set_last_handle_mark(NULL); 222 223 // This initial value ==> never claimed. 224 _oops_do_parity = 0; 225 226 // the handle mark links itself to last_handle_mark 227 new HandleMark(this); 228 229 // plain initialization 230 debug_only(_owned_locks = NULL;) 231 debug_only(_allow_allocation_count = 0;) 232 NOT_PRODUCT(_allow_safepoint_count = 0;) 233 NOT_PRODUCT(_skip_gcalot = false;) 234 _jvmti_env_iteration_count = 0; 235 set_allocated_bytes(0); 236 _vm_operation_started_count = 0; 237 _vm_operation_completed_count = 0; 238 _current_pending_monitor = NULL; 239 _current_pending_monitor_is_from_java = true; 240 _current_waiting_monitor = NULL; 241 _num_nested_signal = 0; 242 omFreeList = NULL; 243 omFreeCount = 0; 244 omFreeProvision = 32; 245 omInUseList = NULL; 246 omInUseCount = 0; 247 248 #ifdef ASSERT 249 _visited_for_critical_count = false; 250 #endif 251 252 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 253 Monitor::_safepoint_check_sometimes); 254 _suspend_flags = 0; 255 256 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 257 _hashStateX = os::random(); 258 _hashStateY = 842502087; 259 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 260 _hashStateW = 273326509; 261 262 _OnTrap = 0; 263 _schedctl = NULL; 264 _Stalled = 0; 265 _TypeTag = 0x2BAD; 266 267 // Many of the following fields are effectively final - immutable 268 // Note that nascent threads can't use the Native Monitor-Mutex 269 // construct until the _MutexEvent is initialized ... 270 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 271 // we might instead use a stack of ParkEvents that we could provision on-demand. 272 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 273 // and ::Release() 274 _ParkEvent = ParkEvent::Allocate(this); 275 _SleepEvent = ParkEvent::Allocate(this); 276 _MutexEvent = ParkEvent::Allocate(this); 277 _MuxEvent = ParkEvent::Allocate(this); 278 279 #ifdef CHECK_UNHANDLED_OOPS 280 if (CheckUnhandledOops) { 281 _unhandled_oops = new UnhandledOops(this); 282 } 283 #endif // CHECK_UNHANDLED_OOPS 284 #ifdef ASSERT 285 if (UseBiasedLocking) { 286 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 287 assert(this == _real_malloc_address || 288 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 289 "bug in forced alignment of thread objects"); 290 } 291 #endif // ASSERT 292 } 293 294 void Thread::initialize_thread_current() { 295 #ifndef USE_LIBRARY_BASED_TLS_ONLY 296 assert(_thr_current == NULL, "Thread::current already initialized"); 297 _thr_current = this; 298 #endif 299 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 300 ThreadLocalStorage::set_thread(this); 301 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 302 } 303 304 void Thread::clear_thread_current() { 305 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 306 #ifndef USE_LIBRARY_BASED_TLS_ONLY 307 _thr_current = NULL; 308 #endif 309 ThreadLocalStorage::set_thread(NULL); 310 } 311 312 void Thread::record_stack_base_and_size() { 313 set_stack_base(os::current_stack_base()); 314 set_stack_size(os::current_stack_size()); 315 // CR 7190089: on Solaris, primordial thread's stack is adjusted 316 // in initialize_thread(). Without the adjustment, stack size is 317 // incorrect if stack is set to unlimited (ulimit -s unlimited). 318 // So far, only Solaris has real implementation of initialize_thread(). 319 // 320 // set up any platform-specific state. 321 os::initialize_thread(this); 322 323 // Set stack limits after thread is initialized. 324 if (is_Java_thread()) { 325 ((JavaThread*) this)->set_stack_overflow_limit(); 326 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 327 } 328 #if INCLUDE_NMT 329 // record thread's native stack, stack grows downward 330 MemTracker::record_thread_stack(stack_end(), stack_size()); 331 #endif // INCLUDE_NMT 332 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 333 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 334 os::current_thread_id(), p2i(stack_base() - stack_size()), 335 p2i(stack_base()), stack_size()/1024); 336 } 337 338 339 Thread::~Thread() { 340 EVENT_THREAD_DESTRUCT(this); 341 342 // stack_base can be NULL if the thread is never started or exited before 343 // record_stack_base_and_size called. Although, we would like to ensure 344 // that all started threads do call record_stack_base_and_size(), there is 345 // not proper way to enforce that. 346 #if INCLUDE_NMT 347 if (_stack_base != NULL) { 348 MemTracker::release_thread_stack(stack_end(), stack_size()); 349 #ifdef ASSERT 350 set_stack_base(NULL); 351 #endif 352 } 353 #endif // INCLUDE_NMT 354 355 // deallocate data structures 356 delete resource_area(); 357 // since the handle marks are using the handle area, we have to deallocated the root 358 // handle mark before deallocating the thread's handle area, 359 assert(last_handle_mark() != NULL, "check we have an element"); 360 delete last_handle_mark(); 361 assert(last_handle_mark() == NULL, "check we have reached the end"); 362 363 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 364 // We NULL out the fields for good hygiene. 365 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 366 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 367 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 368 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 369 370 delete handle_area(); 371 delete metadata_handles(); 372 373 // SR_handler uses this as a termination indicator - 374 // needs to happen before os::free_thread() 375 delete _SR_lock; 376 _SR_lock = NULL; 377 378 // osthread() can be NULL, if creation of thread failed. 379 if (osthread() != NULL) os::free_thread(osthread()); 380 381 // clear Thread::current if thread is deleting itself. 382 // Needed to ensure JNI correctly detects non-attached threads. 383 if (this == Thread::current()) { 384 clear_thread_current(); 385 } 386 387 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 388 } 389 390 // NOTE: dummy function for assertion purpose. 391 void Thread::run() { 392 ShouldNotReachHere(); 393 } 394 395 #ifdef ASSERT 396 // Private method to check for dangling thread pointer 397 void check_for_dangling_thread_pointer(Thread *thread) { 398 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 399 "possibility of dangling Thread pointer"); 400 } 401 #endif 402 403 ThreadPriority Thread::get_priority(const Thread* const thread) { 404 ThreadPriority priority; 405 // Can return an error! 406 (void)os::get_priority(thread, priority); 407 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 408 return priority; 409 } 410 411 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 412 debug_only(check_for_dangling_thread_pointer(thread);) 413 // Can return an error! 414 (void)os::set_priority(thread, priority); 415 } 416 417 418 void Thread::start(Thread* thread) { 419 // Start is different from resume in that its safety is guaranteed by context or 420 // being called from a Java method synchronized on the Thread object. 421 if (!DisableStartThread) { 422 if (thread->is_Java_thread()) { 423 // Initialize the thread state to RUNNABLE before starting this thread. 424 // Can not set it after the thread started because we do not know the 425 // exact thread state at that time. It could be in MONITOR_WAIT or 426 // in SLEEPING or some other state. 427 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 428 java_lang_Thread::RUNNABLE); 429 } 430 os::start_thread(thread); 431 } 432 } 433 434 // Enqueue a VM_Operation to do the job for us - sometime later 435 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 436 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 437 VMThread::execute(vm_stop); 438 } 439 440 441 // Check if an external suspend request has completed (or has been 442 // cancelled). Returns true if the thread is externally suspended and 443 // false otherwise. 444 // 445 // The bits parameter returns information about the code path through 446 // the routine. Useful for debugging: 447 // 448 // set in is_ext_suspend_completed(): 449 // 0x00000001 - routine was entered 450 // 0x00000010 - routine return false at end 451 // 0x00000100 - thread exited (return false) 452 // 0x00000200 - suspend request cancelled (return false) 453 // 0x00000400 - thread suspended (return true) 454 // 0x00001000 - thread is in a suspend equivalent state (return true) 455 // 0x00002000 - thread is native and walkable (return true) 456 // 0x00004000 - thread is native_trans and walkable (needed retry) 457 // 458 // set in wait_for_ext_suspend_completion(): 459 // 0x00010000 - routine was entered 460 // 0x00020000 - suspend request cancelled before loop (return false) 461 // 0x00040000 - thread suspended before loop (return true) 462 // 0x00080000 - suspend request cancelled in loop (return false) 463 // 0x00100000 - thread suspended in loop (return true) 464 // 0x00200000 - suspend not completed during retry loop (return false) 465 466 // Helper class for tracing suspend wait debug bits. 467 // 468 // 0x00000100 indicates that the target thread exited before it could 469 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 470 // 0x00080000 each indicate a cancelled suspend request so they don't 471 // count as wait failures either. 472 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 473 474 class TraceSuspendDebugBits : public StackObj { 475 private: 476 JavaThread * jt; 477 bool is_wait; 478 bool called_by_wait; // meaningful when !is_wait 479 uint32_t * bits; 480 481 public: 482 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 483 uint32_t *_bits) { 484 jt = _jt; 485 is_wait = _is_wait; 486 called_by_wait = _called_by_wait; 487 bits = _bits; 488 } 489 490 ~TraceSuspendDebugBits() { 491 if (!is_wait) { 492 #if 1 493 // By default, don't trace bits for is_ext_suspend_completed() calls. 494 // That trace is very chatty. 495 return; 496 #else 497 if (!called_by_wait) { 498 // If tracing for is_ext_suspend_completed() is enabled, then only 499 // trace calls to it from wait_for_ext_suspend_completion() 500 return; 501 } 502 #endif 503 } 504 505 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 506 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 507 MutexLocker ml(Threads_lock); // needed for get_thread_name() 508 ResourceMark rm; 509 510 tty->print_cr( 511 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 512 jt->get_thread_name(), *bits); 513 514 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 515 } 516 } 517 } 518 }; 519 #undef DEBUG_FALSE_BITS 520 521 522 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 523 uint32_t *bits) { 524 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 525 526 bool did_trans_retry = false; // only do thread_in_native_trans retry once 527 bool do_trans_retry; // flag to force the retry 528 529 *bits |= 0x00000001; 530 531 do { 532 do_trans_retry = false; 533 534 if (is_exiting()) { 535 // Thread is in the process of exiting. This is always checked 536 // first to reduce the risk of dereferencing a freed JavaThread. 537 *bits |= 0x00000100; 538 return false; 539 } 540 541 if (!is_external_suspend()) { 542 // Suspend request is cancelled. This is always checked before 543 // is_ext_suspended() to reduce the risk of a rogue resume 544 // confusing the thread that made the suspend request. 545 *bits |= 0x00000200; 546 return false; 547 } 548 549 if (is_ext_suspended()) { 550 // thread is suspended 551 *bits |= 0x00000400; 552 return true; 553 } 554 555 // Now that we no longer do hard suspends of threads running 556 // native code, the target thread can be changing thread state 557 // while we are in this routine: 558 // 559 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 560 // 561 // We save a copy of the thread state as observed at this moment 562 // and make our decision about suspend completeness based on the 563 // copy. This closes the race where the thread state is seen as 564 // _thread_in_native_trans in the if-thread_blocked check, but is 565 // seen as _thread_blocked in if-thread_in_native_trans check. 566 JavaThreadState save_state = thread_state(); 567 568 if (save_state == _thread_blocked && is_suspend_equivalent()) { 569 // If the thread's state is _thread_blocked and this blocking 570 // condition is known to be equivalent to a suspend, then we can 571 // consider the thread to be externally suspended. This means that 572 // the code that sets _thread_blocked has been modified to do 573 // self-suspension if the blocking condition releases. We also 574 // used to check for CONDVAR_WAIT here, but that is now covered by 575 // the _thread_blocked with self-suspension check. 576 // 577 // Return true since we wouldn't be here unless there was still an 578 // external suspend request. 579 *bits |= 0x00001000; 580 return true; 581 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 582 // Threads running native code will self-suspend on native==>VM/Java 583 // transitions. If its stack is walkable (should always be the case 584 // unless this function is called before the actual java_suspend() 585 // call), then the wait is done. 586 *bits |= 0x00002000; 587 return true; 588 } else if (!called_by_wait && !did_trans_retry && 589 save_state == _thread_in_native_trans && 590 frame_anchor()->walkable()) { 591 // The thread is transitioning from thread_in_native to another 592 // thread state. check_safepoint_and_suspend_for_native_trans() 593 // will force the thread to self-suspend. If it hasn't gotten 594 // there yet we may have caught the thread in-between the native 595 // code check above and the self-suspend. Lucky us. If we were 596 // called by wait_for_ext_suspend_completion(), then it 597 // will be doing the retries so we don't have to. 598 // 599 // Since we use the saved thread state in the if-statement above, 600 // there is a chance that the thread has already transitioned to 601 // _thread_blocked by the time we get here. In that case, we will 602 // make a single unnecessary pass through the logic below. This 603 // doesn't hurt anything since we still do the trans retry. 604 605 *bits |= 0x00004000; 606 607 // Once the thread leaves thread_in_native_trans for another 608 // thread state, we break out of this retry loop. We shouldn't 609 // need this flag to prevent us from getting back here, but 610 // sometimes paranoia is good. 611 did_trans_retry = true; 612 613 // We wait for the thread to transition to a more usable state. 614 for (int i = 1; i <= SuspendRetryCount; i++) { 615 // We used to do an "os::yield_all(i)" call here with the intention 616 // that yielding would increase on each retry. However, the parameter 617 // is ignored on Linux which means the yield didn't scale up. Waiting 618 // on the SR_lock below provides a much more predictable scale up for 619 // the delay. It also provides a simple/direct point to check for any 620 // safepoint requests from the VMThread 621 622 // temporarily drops SR_lock while doing wait with safepoint check 623 // (if we're a JavaThread - the WatcherThread can also call this) 624 // and increase delay with each retry 625 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 626 627 // check the actual thread state instead of what we saved above 628 if (thread_state() != _thread_in_native_trans) { 629 // the thread has transitioned to another thread state so 630 // try all the checks (except this one) one more time. 631 do_trans_retry = true; 632 break; 633 } 634 } // end retry loop 635 636 637 } 638 } while (do_trans_retry); 639 640 *bits |= 0x00000010; 641 return false; 642 } 643 644 // Wait for an external suspend request to complete (or be cancelled). 645 // Returns true if the thread is externally suspended and false otherwise. 646 // 647 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 648 uint32_t *bits) { 649 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 650 false /* !called_by_wait */, bits); 651 652 // local flag copies to minimize SR_lock hold time 653 bool is_suspended; 654 bool pending; 655 uint32_t reset_bits; 656 657 // set a marker so is_ext_suspend_completed() knows we are the caller 658 *bits |= 0x00010000; 659 660 // We use reset_bits to reinitialize the bits value at the top of 661 // each retry loop. This allows the caller to make use of any 662 // unused bits for their own marking purposes. 663 reset_bits = *bits; 664 665 { 666 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 667 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 668 delay, bits); 669 pending = is_external_suspend(); 670 } 671 // must release SR_lock to allow suspension to complete 672 673 if (!pending) { 674 // A cancelled suspend request is the only false return from 675 // is_ext_suspend_completed() that keeps us from entering the 676 // retry loop. 677 *bits |= 0x00020000; 678 return false; 679 } 680 681 if (is_suspended) { 682 *bits |= 0x00040000; 683 return true; 684 } 685 686 for (int i = 1; i <= retries; i++) { 687 *bits = reset_bits; // reinit to only track last retry 688 689 // We used to do an "os::yield_all(i)" call here with the intention 690 // that yielding would increase on each retry. However, the parameter 691 // is ignored on Linux which means the yield didn't scale up. Waiting 692 // on the SR_lock below provides a much more predictable scale up for 693 // the delay. It also provides a simple/direct point to check for any 694 // safepoint requests from the VMThread 695 696 { 697 MutexLocker ml(SR_lock()); 698 // wait with safepoint check (if we're a JavaThread - the WatcherThread 699 // can also call this) and increase delay with each retry 700 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 701 702 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 703 delay, bits); 704 705 // It is possible for the external suspend request to be cancelled 706 // (by a resume) before the actual suspend operation is completed. 707 // Refresh our local copy to see if we still need to wait. 708 pending = is_external_suspend(); 709 } 710 711 if (!pending) { 712 // A cancelled suspend request is the only false return from 713 // is_ext_suspend_completed() that keeps us from staying in the 714 // retry loop. 715 *bits |= 0x00080000; 716 return false; 717 } 718 719 if (is_suspended) { 720 *bits |= 0x00100000; 721 return true; 722 } 723 } // end retry loop 724 725 // thread did not suspend after all our retries 726 *bits |= 0x00200000; 727 return false; 728 } 729 730 #ifndef PRODUCT 731 void JavaThread::record_jump(address target, address instr, const char* file, 732 int line) { 733 734 // This should not need to be atomic as the only way for simultaneous 735 // updates is via interrupts. Even then this should be rare or non-existent 736 // and we don't care that much anyway. 737 738 int index = _jmp_ring_index; 739 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 740 _jmp_ring[index]._target = (intptr_t) target; 741 _jmp_ring[index]._instruction = (intptr_t) instr; 742 _jmp_ring[index]._file = file; 743 _jmp_ring[index]._line = line; 744 } 745 #endif // PRODUCT 746 747 // Called by flat profiler 748 // Callers have already called wait_for_ext_suspend_completion 749 // The assertion for that is currently too complex to put here: 750 bool JavaThread::profile_last_Java_frame(frame* _fr) { 751 bool gotframe = false; 752 // self suspension saves needed state. 753 if (has_last_Java_frame() && _anchor.walkable()) { 754 *_fr = pd_last_frame(); 755 gotframe = true; 756 } 757 return gotframe; 758 } 759 760 void Thread::interrupt(Thread* thread) { 761 debug_only(check_for_dangling_thread_pointer(thread);) 762 os::interrupt(thread); 763 } 764 765 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 766 debug_only(check_for_dangling_thread_pointer(thread);) 767 // Note: If clear_interrupted==false, this simply fetches and 768 // returns the value of the field osthread()->interrupted(). 769 return os::is_interrupted(thread, clear_interrupted); 770 } 771 772 773 // GC Support 774 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 775 jint thread_parity = _oops_do_parity; 776 if (thread_parity != strong_roots_parity) { 777 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 778 if (res == thread_parity) { 779 return true; 780 } else { 781 guarantee(res == strong_roots_parity, "Or else what?"); 782 return false; 783 } 784 } 785 return false; 786 } 787 788 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 789 active_handles()->oops_do(f); 790 // Do oop for ThreadShadow 791 f->do_oop((oop*)&_pending_exception); 792 handle_area()->oops_do(f); 793 794 if (MonitorInUseLists) { 795 // When using thread local monitor lists, we scan them here, 796 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 797 ObjectSynchronizer::thread_local_used_oops_do(this, f); 798 } 799 } 800 801 void Thread::metadata_handles_do(void f(Metadata*)) { 802 // Only walk the Handles in Thread. 803 if (metadata_handles() != NULL) { 804 for (int i = 0; i< metadata_handles()->length(); i++) { 805 f(metadata_handles()->at(i)); 806 } 807 } 808 } 809 810 void Thread::print_on(outputStream* st) const { 811 // get_priority assumes osthread initialized 812 if (osthread() != NULL) { 813 int os_prio; 814 if (os::get_native_priority(this, &os_prio) == OS_OK) { 815 st->print("os_prio=%d ", os_prio); 816 } 817 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 818 ext().print_on(st); 819 osthread()->print_on(st); 820 } 821 debug_only(if (WizardMode) print_owned_locks_on(st);) 822 } 823 824 // Thread::print_on_error() is called by fatal error handler. Don't use 825 // any lock or allocate memory. 826 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 827 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 828 829 if (is_VM_thread()) { st->print("VMThread"); } 830 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 831 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 832 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 833 else { st->print("Thread"); } 834 835 if (is_Named_thread()) { 836 st->print(" \"%s\"", name()); 837 } 838 839 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 840 p2i(stack_end()), p2i(stack_base())); 841 842 if (osthread()) { 843 st->print(" [id=%d]", osthread()->thread_id()); 844 } 845 } 846 847 #ifdef ASSERT 848 void Thread::print_owned_locks_on(outputStream* st) const { 849 Monitor *cur = _owned_locks; 850 if (cur == NULL) { 851 st->print(" (no locks) "); 852 } else { 853 st->print_cr(" Locks owned:"); 854 while (cur) { 855 cur->print_on(st); 856 cur = cur->next(); 857 } 858 } 859 } 860 861 static int ref_use_count = 0; 862 863 bool Thread::owns_locks_but_compiled_lock() const { 864 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 865 if (cur != Compile_lock) return true; 866 } 867 return false; 868 } 869 870 871 #endif 872 873 #ifndef PRODUCT 874 875 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 876 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 877 // no threads which allow_vm_block's are held 878 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 879 // Check if current thread is allowed to block at a safepoint 880 if (!(_allow_safepoint_count == 0)) { 881 fatal("Possible safepoint reached by thread that does not allow it"); 882 } 883 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 884 fatal("LEAF method calling lock?"); 885 } 886 887 #ifdef ASSERT 888 if (potential_vm_operation && is_Java_thread() 889 && !Universe::is_bootstrapping()) { 890 // Make sure we do not hold any locks that the VM thread also uses. 891 // This could potentially lead to deadlocks 892 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 893 // Threads_lock is special, since the safepoint synchronization will not start before this is 894 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 895 // since it is used to transfer control between JavaThreads and the VMThread 896 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 897 if ((cur->allow_vm_block() && 898 cur != Threads_lock && 899 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 900 cur != VMOperationRequest_lock && 901 cur != VMOperationQueue_lock) || 902 cur->rank() == Mutex::special) { 903 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 904 } 905 } 906 } 907 908 if (GCALotAtAllSafepoints) { 909 // We could enter a safepoint here and thus have a gc 910 InterfaceSupport::check_gc_alot(); 911 } 912 #endif 913 } 914 #endif 915 916 bool Thread::is_in_stack(address adr) const { 917 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 918 address end = os::current_stack_pointer(); 919 // Allow non Java threads to call this without stack_base 920 if (_stack_base == NULL) return true; 921 if (stack_base() >= adr && adr >= end) return true; 922 923 return false; 924 } 925 926 bool Thread::is_in_usable_stack(address adr) const { 927 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 928 size_t usable_stack_size = _stack_size - stack_guard_size; 929 930 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 931 } 932 933 934 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 935 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 936 // used for compilation in the future. If that change is made, the need for these methods 937 // should be revisited, and they should be removed if possible. 938 939 bool Thread::is_lock_owned(address adr) const { 940 return on_local_stack(adr); 941 } 942 943 bool Thread::set_as_starting_thread() { 944 // NOTE: this must be called inside the main thread. 945 return os::create_main_thread((JavaThread*)this); 946 } 947 948 static void initialize_class(Symbol* class_name, TRAPS) { 949 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 950 InstanceKlass::cast(klass)->initialize(CHECK); 951 } 952 953 954 // Creates the initial ThreadGroup 955 static Handle create_initial_thread_group(TRAPS) { 956 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 957 InstanceKlass* ik = InstanceKlass::cast(k); 958 959 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 960 { 961 JavaValue result(T_VOID); 962 JavaCalls::call_special(&result, 963 system_instance, 964 ik, 965 vmSymbols::object_initializer_name(), 966 vmSymbols::void_method_signature(), 967 CHECK_NH); 968 } 969 Universe::set_system_thread_group(system_instance()); 970 971 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 972 { 973 JavaValue result(T_VOID); 974 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 975 JavaCalls::call_special(&result, 976 main_instance, 977 ik, 978 vmSymbols::object_initializer_name(), 979 vmSymbols::threadgroup_string_void_signature(), 980 system_instance, 981 string, 982 CHECK_NH); 983 } 984 return main_instance; 985 } 986 987 // Creates the initial Thread 988 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 989 TRAPS) { 990 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 991 InstanceKlass* ik = InstanceKlass::cast(k); 992 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 993 994 java_lang_Thread::set_thread(thread_oop(), thread); 995 java_lang_Thread::set_priority(thread_oop(), NormPriority); 996 thread->set_threadObj(thread_oop()); 997 998 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 999 1000 JavaValue result(T_VOID); 1001 JavaCalls::call_special(&result, thread_oop, 1002 ik, 1003 vmSymbols::object_initializer_name(), 1004 vmSymbols::threadgroup_string_void_signature(), 1005 thread_group, 1006 string, 1007 CHECK_NULL); 1008 return thread_oop(); 1009 } 1010 1011 char java_runtime_name[128] = ""; 1012 char java_runtime_version[128] = ""; 1013 1014 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1015 static const char* get_java_runtime_name(TRAPS) { 1016 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1017 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1018 fieldDescriptor fd; 1019 bool found = k != NULL && 1020 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1021 vmSymbols::string_signature(), &fd); 1022 if (found) { 1023 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1024 if (name_oop == NULL) { 1025 return NULL; 1026 } 1027 const char* name = java_lang_String::as_utf8_string(name_oop, 1028 java_runtime_name, 1029 sizeof(java_runtime_name)); 1030 return name; 1031 } else { 1032 return NULL; 1033 } 1034 } 1035 1036 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1037 static const char* get_java_runtime_version(TRAPS) { 1038 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1039 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1040 fieldDescriptor fd; 1041 bool found = k != NULL && 1042 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1043 vmSymbols::string_signature(), &fd); 1044 if (found) { 1045 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1046 if (name_oop == NULL) { 1047 return NULL; 1048 } 1049 const char* name = java_lang_String::as_utf8_string(name_oop, 1050 java_runtime_version, 1051 sizeof(java_runtime_version)); 1052 return name; 1053 } else { 1054 return NULL; 1055 } 1056 } 1057 1058 // General purpose hook into Java code, run once when the VM is initialized. 1059 // The Java library method itself may be changed independently from the VM. 1060 static void call_postVMInitHook(TRAPS) { 1061 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1062 if (klass != NULL) { 1063 JavaValue result(T_VOID); 1064 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1065 vmSymbols::void_method_signature(), 1066 CHECK); 1067 } 1068 } 1069 1070 static void reset_vm_info_property(TRAPS) { 1071 // the vm info string 1072 ResourceMark rm(THREAD); 1073 const char *vm_info = VM_Version::vm_info_string(); 1074 1075 // java.lang.System class 1076 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1077 1078 // setProperty arguments 1079 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1080 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1081 1082 // return value 1083 JavaValue r(T_OBJECT); 1084 1085 // public static String setProperty(String key, String value); 1086 JavaCalls::call_static(&r, 1087 klass, 1088 vmSymbols::setProperty_name(), 1089 vmSymbols::string_string_string_signature(), 1090 key_str, 1091 value_str, 1092 CHECK); 1093 } 1094 1095 1096 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1097 bool daemon, TRAPS) { 1098 assert(thread_group.not_null(), "thread group should be specified"); 1099 assert(threadObj() == NULL, "should only create Java thread object once"); 1100 1101 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1102 InstanceKlass* ik = InstanceKlass::cast(k); 1103 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1104 1105 java_lang_Thread::set_thread(thread_oop(), this); 1106 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1107 set_threadObj(thread_oop()); 1108 1109 JavaValue result(T_VOID); 1110 if (thread_name != NULL) { 1111 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1112 // Thread gets assigned specified name and null target 1113 JavaCalls::call_special(&result, 1114 thread_oop, 1115 ik, 1116 vmSymbols::object_initializer_name(), 1117 vmSymbols::threadgroup_string_void_signature(), 1118 thread_group, // Argument 1 1119 name, // Argument 2 1120 THREAD); 1121 } else { 1122 // Thread gets assigned name "Thread-nnn" and null target 1123 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1124 JavaCalls::call_special(&result, 1125 thread_oop, 1126 ik, 1127 vmSymbols::object_initializer_name(), 1128 vmSymbols::threadgroup_runnable_void_signature(), 1129 thread_group, // Argument 1 1130 Handle(), // Argument 2 1131 THREAD); 1132 } 1133 1134 1135 if (daemon) { 1136 java_lang_Thread::set_daemon(thread_oop()); 1137 } 1138 1139 if (HAS_PENDING_EXCEPTION) { 1140 return; 1141 } 1142 1143 Klass* group = SystemDictionary::ThreadGroup_klass(); 1144 Handle threadObj(THREAD, this->threadObj()); 1145 1146 JavaCalls::call_special(&result, 1147 thread_group, 1148 group, 1149 vmSymbols::add_method_name(), 1150 vmSymbols::thread_void_signature(), 1151 threadObj, // Arg 1 1152 THREAD); 1153 } 1154 1155 // NamedThread -- non-JavaThread subclasses with multiple 1156 // uniquely named instances should derive from this. 1157 NamedThread::NamedThread() : Thread() { 1158 _name = NULL; 1159 _processed_thread = NULL; 1160 _gc_id = GCId::undefined(); 1161 } 1162 1163 NamedThread::~NamedThread() { 1164 if (_name != NULL) { 1165 FREE_C_HEAP_ARRAY(char, _name); 1166 _name = NULL; 1167 } 1168 } 1169 1170 void NamedThread::set_name(const char* format, ...) { 1171 guarantee(_name == NULL, "Only get to set name once."); 1172 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1173 guarantee(_name != NULL, "alloc failure"); 1174 va_list ap; 1175 va_start(ap, format); 1176 jio_vsnprintf(_name, max_name_len, format, ap); 1177 va_end(ap); 1178 } 1179 1180 void NamedThread::initialize_named_thread() { 1181 set_native_thread_name(name()); 1182 } 1183 1184 void NamedThread::print_on(outputStream* st) const { 1185 st->print("\"%s\" ", name()); 1186 Thread::print_on(st); 1187 st->cr(); 1188 } 1189 1190 1191 // ======= WatcherThread ======== 1192 1193 // The watcher thread exists to simulate timer interrupts. It should 1194 // be replaced by an abstraction over whatever native support for 1195 // timer interrupts exists on the platform. 1196 1197 WatcherThread* WatcherThread::_watcher_thread = NULL; 1198 bool WatcherThread::_startable = false; 1199 volatile bool WatcherThread::_should_terminate = false; 1200 1201 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1202 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1203 if (os::create_thread(this, os::watcher_thread)) { 1204 _watcher_thread = this; 1205 1206 // Set the watcher thread to the highest OS priority which should not be 1207 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1208 // is created. The only normal thread using this priority is the reference 1209 // handler thread, which runs for very short intervals only. 1210 // If the VMThread's priority is not lower than the WatcherThread profiling 1211 // will be inaccurate. 1212 os::set_priority(this, MaxPriority); 1213 if (!DisableStartThread) { 1214 os::start_thread(this); 1215 } 1216 } 1217 } 1218 1219 int WatcherThread::sleep() const { 1220 // The WatcherThread does not participate in the safepoint protocol 1221 // for the PeriodicTask_lock because it is not a JavaThread. 1222 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1223 1224 if (_should_terminate) { 1225 // check for termination before we do any housekeeping or wait 1226 return 0; // we did not sleep. 1227 } 1228 1229 // remaining will be zero if there are no tasks, 1230 // causing the WatcherThread to sleep until a task is 1231 // enrolled 1232 int remaining = PeriodicTask::time_to_wait(); 1233 int time_slept = 0; 1234 1235 // we expect this to timeout - we only ever get unparked when 1236 // we should terminate or when a new task has been enrolled 1237 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1238 1239 jlong time_before_loop = os::javaTimeNanos(); 1240 1241 while (true) { 1242 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1243 remaining); 1244 jlong now = os::javaTimeNanos(); 1245 1246 if (remaining == 0) { 1247 // if we didn't have any tasks we could have waited for a long time 1248 // consider the time_slept zero and reset time_before_loop 1249 time_slept = 0; 1250 time_before_loop = now; 1251 } else { 1252 // need to recalculate since we might have new tasks in _tasks 1253 time_slept = (int) ((now - time_before_loop) / 1000000); 1254 } 1255 1256 // Change to task list or spurious wakeup of some kind 1257 if (timedout || _should_terminate) { 1258 break; 1259 } 1260 1261 remaining = PeriodicTask::time_to_wait(); 1262 if (remaining == 0) { 1263 // Last task was just disenrolled so loop around and wait until 1264 // another task gets enrolled 1265 continue; 1266 } 1267 1268 remaining -= time_slept; 1269 if (remaining <= 0) { 1270 break; 1271 } 1272 } 1273 1274 return time_slept; 1275 } 1276 1277 void WatcherThread::run() { 1278 assert(this == watcher_thread(), "just checking"); 1279 1280 this->record_stack_base_and_size(); 1281 this->set_native_thread_name(this->name()); 1282 this->set_active_handles(JNIHandleBlock::allocate_block()); 1283 while (true) { 1284 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1285 assert(watcher_thread() == this, "thread consistency check"); 1286 1287 // Calculate how long it'll be until the next PeriodicTask work 1288 // should be done, and sleep that amount of time. 1289 int time_waited = sleep(); 1290 1291 if (is_error_reported()) { 1292 // A fatal error has happened, the error handler(VMError::report_and_die) 1293 // should abort JVM after creating an error log file. However in some 1294 // rare cases, the error handler itself might deadlock. Here periodically 1295 // check for error reporting timeouts, and if it happens, just proceed to 1296 // abort the VM. 1297 1298 // This code is in WatcherThread because WatcherThread wakes up 1299 // periodically so the fatal error handler doesn't need to do anything; 1300 // also because the WatcherThread is less likely to crash than other 1301 // threads. 1302 1303 for (;;) { 1304 // Note: we use naked sleep in this loop because we want to avoid using 1305 // any kind of VM infrastructure which may be broken at this point. 1306 if (VMError::check_timeout()) { 1307 // We hit error reporting timeout. Error reporting was interrupted and 1308 // will be wrapping things up now (closing files etc). Give it some more 1309 // time, then quit the VM. 1310 os::naked_short_sleep(200); 1311 // Print a message to stderr. 1312 fdStream err(defaultStream::output_fd()); 1313 err.print_raw_cr("# [ timer expired, abort... ]"); 1314 // skip atexit/vm_exit/vm_abort hooks 1315 os::die(); 1316 } 1317 1318 // Wait a second, then recheck for timeout. 1319 os::naked_short_sleep(999); 1320 } 1321 } 1322 1323 if (_should_terminate) { 1324 // check for termination before posting the next tick 1325 break; 1326 } 1327 1328 PeriodicTask::real_time_tick(time_waited); 1329 } 1330 1331 // Signal that it is terminated 1332 { 1333 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1334 _watcher_thread = NULL; 1335 Terminator_lock->notify(); 1336 } 1337 } 1338 1339 void WatcherThread::start() { 1340 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1341 1342 if (watcher_thread() == NULL && _startable) { 1343 _should_terminate = false; 1344 // Create the single instance of WatcherThread 1345 new WatcherThread(); 1346 } 1347 } 1348 1349 void WatcherThread::make_startable() { 1350 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1351 _startable = true; 1352 } 1353 1354 void WatcherThread::stop() { 1355 { 1356 // Follow normal safepoint aware lock enter protocol since the 1357 // WatcherThread is stopped by another JavaThread. 1358 MutexLocker ml(PeriodicTask_lock); 1359 _should_terminate = true; 1360 1361 WatcherThread* watcher = watcher_thread(); 1362 if (watcher != NULL) { 1363 // unpark the WatcherThread so it can see that it should terminate 1364 watcher->unpark(); 1365 } 1366 } 1367 1368 MutexLocker mu(Terminator_lock); 1369 1370 while (watcher_thread() != NULL) { 1371 // This wait should make safepoint checks, wait without a timeout, 1372 // and wait as a suspend-equivalent condition. 1373 // 1374 // Note: If the FlatProfiler is running, then this thread is waiting 1375 // for the WatcherThread to terminate and the WatcherThread, via the 1376 // FlatProfiler task, is waiting for the external suspend request on 1377 // this thread to complete. wait_for_ext_suspend_completion() will 1378 // eventually timeout, but that takes time. Making this wait a 1379 // suspend-equivalent condition solves that timeout problem. 1380 // 1381 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1382 Mutex::_as_suspend_equivalent_flag); 1383 } 1384 } 1385 1386 void WatcherThread::unpark() { 1387 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1388 PeriodicTask_lock->notify(); 1389 } 1390 1391 void WatcherThread::print_on(outputStream* st) const { 1392 st->print("\"%s\" ", name()); 1393 Thread::print_on(st); 1394 st->cr(); 1395 } 1396 1397 // ======= JavaThread ======== 1398 1399 #if INCLUDE_JVMCI 1400 1401 jlong* JavaThread::_jvmci_old_thread_counters; 1402 1403 bool jvmci_counters_include(JavaThread* thread) { 1404 oop threadObj = thread->threadObj(); 1405 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1406 } 1407 1408 void JavaThread::collect_counters(typeArrayOop array) { 1409 if (JVMCICounterSize > 0) { 1410 MutexLocker tl(Threads_lock); 1411 for (int i = 0; i < array->length(); i++) { 1412 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1413 } 1414 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1415 if (jvmci_counters_include(tp)) { 1416 for (int i = 0; i < array->length(); i++) { 1417 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1418 } 1419 } 1420 } 1421 } 1422 } 1423 1424 #endif // INCLUDE_JVMCI 1425 1426 // A JavaThread is a normal Java thread 1427 1428 void JavaThread::initialize() { 1429 // Initialize fields 1430 1431 set_saved_exception_pc(NULL); 1432 set_threadObj(NULL); 1433 _anchor.clear(); 1434 set_entry_point(NULL); 1435 set_jni_functions(jni_functions()); 1436 set_callee_target(NULL); 1437 set_vm_result(NULL); 1438 set_vm_result_2(NULL); 1439 set_vframe_array_head(NULL); 1440 set_vframe_array_last(NULL); 1441 set_deferred_locals(NULL); 1442 set_deopt_mark(NULL); 1443 set_deopt_compiled_method(NULL); 1444 clear_must_deopt_id(); 1445 set_monitor_chunks(NULL); 1446 set_next(NULL); 1447 set_thread_state(_thread_new); 1448 _terminated = _not_terminated; 1449 _privileged_stack_top = NULL; 1450 _array_for_gc = NULL; 1451 _suspend_equivalent = false; 1452 _in_deopt_handler = 0; 1453 _doing_unsafe_access = false; 1454 _stack_guard_state = stack_guard_unused; 1455 #if INCLUDE_JVMCI 1456 _pending_monitorenter = false; 1457 _pending_deoptimization = -1; 1458 _pending_failed_speculation = NULL; 1459 _pending_transfer_to_interpreter = false; 1460 _adjusting_comp_level = false; 1461 _jvmci._alternate_call_target = NULL; 1462 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1463 if (JVMCICounterSize > 0) { 1464 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1465 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1466 } else { 1467 _jvmci_counters = NULL; 1468 } 1469 #endif // INCLUDE_JVMCI 1470 _reserved_stack_activation = NULL; // stack base not known yet 1471 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1472 _exception_pc = 0; 1473 _exception_handler_pc = 0; 1474 _is_method_handle_return = 0; 1475 _jvmti_thread_state= NULL; 1476 _should_post_on_exceptions_flag = JNI_FALSE; 1477 _jvmti_get_loaded_classes_closure = NULL; 1478 _interp_only_mode = 0; 1479 _special_runtime_exit_condition = _no_async_condition; 1480 _pending_async_exception = NULL; 1481 _thread_stat = NULL; 1482 _thread_stat = new ThreadStatistics(); 1483 _blocked_on_compilation = false; 1484 _jni_active_critical = 0; 1485 _pending_jni_exception_check_fn = NULL; 1486 _do_not_unlock_if_synchronized = false; 1487 _cached_monitor_info = NULL; 1488 _parker = Parker::Allocate(this); 1489 1490 #ifndef PRODUCT 1491 _jmp_ring_index = 0; 1492 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1493 record_jump(NULL, NULL, NULL, 0); 1494 } 1495 #endif // PRODUCT 1496 1497 set_thread_profiler(NULL); 1498 if (FlatProfiler::is_active()) { 1499 // This is where we would decide to either give each thread it's own profiler 1500 // or use one global one from FlatProfiler, 1501 // or up to some count of the number of profiled threads, etc. 1502 ThreadProfiler* pp = new ThreadProfiler(); 1503 pp->engage(); 1504 set_thread_profiler(pp); 1505 } 1506 1507 // Setup safepoint state info for this thread 1508 ThreadSafepointState::create(this); 1509 1510 debug_only(_java_call_counter = 0); 1511 1512 // JVMTI PopFrame support 1513 _popframe_condition = popframe_inactive; 1514 _popframe_preserved_args = NULL; 1515 _popframe_preserved_args_size = 0; 1516 _frames_to_pop_failed_realloc = 0; 1517 1518 pd_initialize(); 1519 } 1520 1521 #if INCLUDE_ALL_GCS 1522 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1523 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1524 #endif // INCLUDE_ALL_GCS 1525 1526 JavaThread::JavaThread(bool is_attaching_via_jni) : 1527 Thread() 1528 #if INCLUDE_ALL_GCS 1529 , _satb_mark_queue(&_satb_mark_queue_set), 1530 _dirty_card_queue(&_dirty_card_queue_set) 1531 #endif // INCLUDE_ALL_GCS 1532 { 1533 initialize(); 1534 if (is_attaching_via_jni) { 1535 _jni_attach_state = _attaching_via_jni; 1536 } else { 1537 _jni_attach_state = _not_attaching_via_jni; 1538 } 1539 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1540 } 1541 1542 bool JavaThread::reguard_stack(address cur_sp) { 1543 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1544 && _stack_guard_state != stack_guard_reserved_disabled) { 1545 return true; // Stack already guarded or guard pages not needed. 1546 } 1547 1548 if (register_stack_overflow()) { 1549 // For those architectures which have separate register and 1550 // memory stacks, we must check the register stack to see if 1551 // it has overflowed. 1552 return false; 1553 } 1554 1555 // Java code never executes within the yellow zone: the latter is only 1556 // there to provoke an exception during stack banging. If java code 1557 // is executing there, either StackShadowPages should be larger, or 1558 // some exception code in c1, c2 or the interpreter isn't unwinding 1559 // when it should. 1560 guarantee(cur_sp > stack_reserved_zone_base(), 1561 "not enough space to reguard - increase StackShadowPages"); 1562 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1563 enable_stack_yellow_reserved_zone(); 1564 if (reserved_stack_activation() != stack_base()) { 1565 set_reserved_stack_activation(stack_base()); 1566 } 1567 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1568 set_reserved_stack_activation(stack_base()); 1569 enable_stack_reserved_zone(); 1570 } 1571 return true; 1572 } 1573 1574 bool JavaThread::reguard_stack(void) { 1575 return reguard_stack(os::current_stack_pointer()); 1576 } 1577 1578 1579 void JavaThread::block_if_vm_exited() { 1580 if (_terminated == _vm_exited) { 1581 // _vm_exited is set at safepoint, and Threads_lock is never released 1582 // we will block here forever 1583 Threads_lock->lock_without_safepoint_check(); 1584 ShouldNotReachHere(); 1585 } 1586 } 1587 1588 1589 // Remove this ifdef when C1 is ported to the compiler interface. 1590 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1591 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1592 1593 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1594 Thread() 1595 #if INCLUDE_ALL_GCS 1596 , _satb_mark_queue(&_satb_mark_queue_set), 1597 _dirty_card_queue(&_dirty_card_queue_set) 1598 #endif // INCLUDE_ALL_GCS 1599 { 1600 initialize(); 1601 _jni_attach_state = _not_attaching_via_jni; 1602 set_entry_point(entry_point); 1603 // Create the native thread itself. 1604 // %note runtime_23 1605 os::ThreadType thr_type = os::java_thread; 1606 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1607 os::java_thread; 1608 os::create_thread(this, thr_type, stack_sz); 1609 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1610 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1611 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1612 // the exception consists of creating the exception object & initializing it, initialization 1613 // will leave the VM via a JavaCall and then all locks must be unlocked). 1614 // 1615 // The thread is still suspended when we reach here. Thread must be explicit started 1616 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1617 // by calling Threads:add. The reason why this is not done here, is because the thread 1618 // object must be fully initialized (take a look at JVM_Start) 1619 } 1620 1621 JavaThread::~JavaThread() { 1622 1623 // JSR166 -- return the parker to the free list 1624 Parker::Release(_parker); 1625 _parker = NULL; 1626 1627 // Free any remaining previous UnrollBlock 1628 vframeArray* old_array = vframe_array_last(); 1629 1630 if (old_array != NULL) { 1631 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1632 old_array->set_unroll_block(NULL); 1633 delete old_info; 1634 delete old_array; 1635 } 1636 1637 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1638 if (deferred != NULL) { 1639 // This can only happen if thread is destroyed before deoptimization occurs. 1640 assert(deferred->length() != 0, "empty array!"); 1641 do { 1642 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1643 deferred->remove_at(0); 1644 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1645 delete dlv; 1646 } while (deferred->length() != 0); 1647 delete deferred; 1648 } 1649 1650 // All Java related clean up happens in exit 1651 ThreadSafepointState::destroy(this); 1652 if (_thread_profiler != NULL) delete _thread_profiler; 1653 if (_thread_stat != NULL) delete _thread_stat; 1654 1655 #if INCLUDE_JVMCI 1656 if (JVMCICounterSize > 0) { 1657 if (jvmci_counters_include(this)) { 1658 for (int i = 0; i < JVMCICounterSize; i++) { 1659 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1660 } 1661 } 1662 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1663 } 1664 #endif // INCLUDE_JVMCI 1665 } 1666 1667 1668 // The first routine called by a new Java thread 1669 void JavaThread::run() { 1670 // initialize thread-local alloc buffer related fields 1671 this->initialize_tlab(); 1672 1673 // used to test validity of stack trace backs 1674 this->record_base_of_stack_pointer(); 1675 1676 // Record real stack base and size. 1677 this->record_stack_base_and_size(); 1678 1679 this->create_stack_guard_pages(); 1680 1681 this->cache_global_variables(); 1682 1683 // Thread is now sufficient initialized to be handled by the safepoint code as being 1684 // in the VM. Change thread state from _thread_new to _thread_in_vm 1685 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1686 1687 assert(JavaThread::current() == this, "sanity check"); 1688 assert(!Thread::current()->owns_locks(), "sanity check"); 1689 1690 DTRACE_THREAD_PROBE(start, this); 1691 1692 // This operation might block. We call that after all safepoint checks for a new thread has 1693 // been completed. 1694 this->set_active_handles(JNIHandleBlock::allocate_block()); 1695 1696 if (JvmtiExport::should_post_thread_life()) { 1697 JvmtiExport::post_thread_start(this); 1698 } 1699 1700 EventThreadStart event; 1701 if (event.should_commit()) { 1702 event.set_thread(THREAD_TRACE_ID(this)); 1703 event.commit(); 1704 } 1705 1706 // We call another function to do the rest so we are sure that the stack addresses used 1707 // from there will be lower than the stack base just computed 1708 thread_main_inner(); 1709 1710 // Note, thread is no longer valid at this point! 1711 } 1712 1713 1714 void JavaThread::thread_main_inner() { 1715 assert(JavaThread::current() == this, "sanity check"); 1716 assert(this->threadObj() != NULL, "just checking"); 1717 1718 // Execute thread entry point unless this thread has a pending exception 1719 // or has been stopped before starting. 1720 // Note: Due to JVM_StopThread we can have pending exceptions already! 1721 if (!this->has_pending_exception() && 1722 !java_lang_Thread::is_stillborn(this->threadObj())) { 1723 { 1724 ResourceMark rm(this); 1725 this->set_native_thread_name(this->get_thread_name()); 1726 } 1727 HandleMark hm(this); 1728 this->entry_point()(this, this); 1729 } 1730 1731 DTRACE_THREAD_PROBE(stop, this); 1732 1733 this->exit(false); 1734 delete this; 1735 } 1736 1737 1738 static void ensure_join(JavaThread* thread) { 1739 // We do not need to grap the Threads_lock, since we are operating on ourself. 1740 Handle threadObj(thread, thread->threadObj()); 1741 assert(threadObj.not_null(), "java thread object must exist"); 1742 ObjectLocker lock(threadObj, thread); 1743 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1744 thread->clear_pending_exception(); 1745 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1746 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1747 // Clear the native thread instance - this makes isAlive return false and allows the join() 1748 // to complete once we've done the notify_all below 1749 java_lang_Thread::set_thread(threadObj(), NULL); 1750 lock.notify_all(thread); 1751 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1752 thread->clear_pending_exception(); 1753 } 1754 1755 1756 // For any new cleanup additions, please check to see if they need to be applied to 1757 // cleanup_failed_attach_current_thread as well. 1758 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1759 assert(this == JavaThread::current(), "thread consistency check"); 1760 1761 HandleMark hm(this); 1762 Handle uncaught_exception(this, this->pending_exception()); 1763 this->clear_pending_exception(); 1764 Handle threadObj(this, this->threadObj()); 1765 assert(threadObj.not_null(), "Java thread object should be created"); 1766 1767 if (get_thread_profiler() != NULL) { 1768 get_thread_profiler()->disengage(); 1769 ResourceMark rm; 1770 get_thread_profiler()->print(get_thread_name()); 1771 } 1772 1773 1774 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1775 { 1776 EXCEPTION_MARK; 1777 1778 CLEAR_PENDING_EXCEPTION; 1779 } 1780 if (!destroy_vm) { 1781 if (uncaught_exception.not_null()) { 1782 EXCEPTION_MARK; 1783 // Call method Thread.dispatchUncaughtException(). 1784 Klass* thread_klass = SystemDictionary::Thread_klass(); 1785 JavaValue result(T_VOID); 1786 JavaCalls::call_virtual(&result, 1787 threadObj, thread_klass, 1788 vmSymbols::dispatchUncaughtException_name(), 1789 vmSymbols::throwable_void_signature(), 1790 uncaught_exception, 1791 THREAD); 1792 if (HAS_PENDING_EXCEPTION) { 1793 ResourceMark rm(this); 1794 jio_fprintf(defaultStream::error_stream(), 1795 "\nException: %s thrown from the UncaughtExceptionHandler" 1796 " in thread \"%s\"\n", 1797 pending_exception()->klass()->external_name(), 1798 get_thread_name()); 1799 CLEAR_PENDING_EXCEPTION; 1800 } 1801 } 1802 1803 // Called before the java thread exit since we want to read info 1804 // from java_lang_Thread object 1805 EventThreadEnd event; 1806 if (event.should_commit()) { 1807 event.set_thread(THREAD_TRACE_ID(this)); 1808 event.commit(); 1809 } 1810 1811 // Call after last event on thread 1812 EVENT_THREAD_EXIT(this); 1813 1814 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1815 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1816 // is deprecated anyhow. 1817 if (!is_Compiler_thread()) { 1818 int count = 3; 1819 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1820 EXCEPTION_MARK; 1821 JavaValue result(T_VOID); 1822 Klass* thread_klass = SystemDictionary::Thread_klass(); 1823 JavaCalls::call_virtual(&result, 1824 threadObj, thread_klass, 1825 vmSymbols::exit_method_name(), 1826 vmSymbols::void_method_signature(), 1827 THREAD); 1828 CLEAR_PENDING_EXCEPTION; 1829 } 1830 } 1831 // notify JVMTI 1832 if (JvmtiExport::should_post_thread_life()) { 1833 JvmtiExport::post_thread_end(this); 1834 } 1835 1836 // We have notified the agents that we are exiting, before we go on, 1837 // we must check for a pending external suspend request and honor it 1838 // in order to not surprise the thread that made the suspend request. 1839 while (true) { 1840 { 1841 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1842 if (!is_external_suspend()) { 1843 set_terminated(_thread_exiting); 1844 ThreadService::current_thread_exiting(this); 1845 break; 1846 } 1847 // Implied else: 1848 // Things get a little tricky here. We have a pending external 1849 // suspend request, but we are holding the SR_lock so we 1850 // can't just self-suspend. So we temporarily drop the lock 1851 // and then self-suspend. 1852 } 1853 1854 ThreadBlockInVM tbivm(this); 1855 java_suspend_self(); 1856 1857 // We're done with this suspend request, but we have to loop around 1858 // and check again. Eventually we will get SR_lock without a pending 1859 // external suspend request and will be able to mark ourselves as 1860 // exiting. 1861 } 1862 // no more external suspends are allowed at this point 1863 } else { 1864 // before_exit() has already posted JVMTI THREAD_END events 1865 } 1866 1867 // Notify waiters on thread object. This has to be done after exit() is called 1868 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1869 // group should have the destroyed bit set before waiters are notified). 1870 ensure_join(this); 1871 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1872 1873 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1874 // held by this thread must be released. The spec does not distinguish 1875 // between JNI-acquired and regular Java monitors. We can only see 1876 // regular Java monitors here if monitor enter-exit matching is broken. 1877 // 1878 // Optionally release any monitors for regular JavaThread exits. This 1879 // is provided as a work around for any bugs in monitor enter-exit 1880 // matching. This can be expensive so it is not enabled by default. 1881 // 1882 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1883 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1884 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1885 // Sanity check even though JNI DetachCurrentThread() would have 1886 // returned JNI_ERR if there was a Java frame. JavaThread exit 1887 // should be done executing Java code by the time we get here. 1888 assert(!this->has_last_Java_frame(), 1889 "should not have a Java frame when detaching or exiting"); 1890 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1891 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1892 } 1893 1894 // These things needs to be done while we are still a Java Thread. Make sure that thread 1895 // is in a consistent state, in case GC happens 1896 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1897 1898 if (active_handles() != NULL) { 1899 JNIHandleBlock* block = active_handles(); 1900 set_active_handles(NULL); 1901 JNIHandleBlock::release_block(block); 1902 } 1903 1904 if (free_handle_block() != NULL) { 1905 JNIHandleBlock* block = free_handle_block(); 1906 set_free_handle_block(NULL); 1907 JNIHandleBlock::release_block(block); 1908 } 1909 1910 // These have to be removed while this is still a valid thread. 1911 remove_stack_guard_pages(); 1912 1913 if (UseTLAB) { 1914 tlab().make_parsable(true); // retire TLAB 1915 } 1916 1917 if (JvmtiEnv::environments_might_exist()) { 1918 JvmtiExport::cleanup_thread(this); 1919 } 1920 1921 // We must flush any deferred card marks before removing a thread from 1922 // the list of active threads. 1923 Universe::heap()->flush_deferred_store_barrier(this); 1924 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1925 1926 #if INCLUDE_ALL_GCS 1927 // We must flush the G1-related buffers before removing a thread 1928 // from the list of active threads. We must do this after any deferred 1929 // card marks have been flushed (above) so that any entries that are 1930 // added to the thread's dirty card queue as a result are not lost. 1931 if (UseG1GC) { 1932 flush_barrier_queues(); 1933 } 1934 #endif // INCLUDE_ALL_GCS 1935 1936 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1937 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1938 os::current_thread_id()); 1939 1940 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1941 Threads::remove(this); 1942 } 1943 1944 #if INCLUDE_ALL_GCS 1945 // Flush G1-related queues. 1946 void JavaThread::flush_barrier_queues() { 1947 satb_mark_queue().flush(); 1948 dirty_card_queue().flush(); 1949 } 1950 1951 void JavaThread::initialize_queues() { 1952 assert(!SafepointSynchronize::is_at_safepoint(), 1953 "we should not be at a safepoint"); 1954 1955 SATBMarkQueue& satb_queue = satb_mark_queue(); 1956 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1957 // The SATB queue should have been constructed with its active 1958 // field set to false. 1959 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1960 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1961 // If we are creating the thread during a marking cycle, we should 1962 // set the active field of the SATB queue to true. 1963 if (satb_queue_set.is_active()) { 1964 satb_queue.set_active(true); 1965 } 1966 1967 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1968 // The dirty card queue should have been constructed with its 1969 // active field set to true. 1970 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1971 } 1972 #endif // INCLUDE_ALL_GCS 1973 1974 void JavaThread::cleanup_failed_attach_current_thread() { 1975 if (get_thread_profiler() != NULL) { 1976 get_thread_profiler()->disengage(); 1977 ResourceMark rm; 1978 get_thread_profiler()->print(get_thread_name()); 1979 } 1980 1981 if (active_handles() != NULL) { 1982 JNIHandleBlock* block = active_handles(); 1983 set_active_handles(NULL); 1984 JNIHandleBlock::release_block(block); 1985 } 1986 1987 if (free_handle_block() != NULL) { 1988 JNIHandleBlock* block = free_handle_block(); 1989 set_free_handle_block(NULL); 1990 JNIHandleBlock::release_block(block); 1991 } 1992 1993 // These have to be removed while this is still a valid thread. 1994 remove_stack_guard_pages(); 1995 1996 if (UseTLAB) { 1997 tlab().make_parsable(true); // retire TLAB, if any 1998 } 1999 2000 #if INCLUDE_ALL_GCS 2001 if (UseG1GC) { 2002 flush_barrier_queues(); 2003 } 2004 #endif // INCLUDE_ALL_GCS 2005 2006 Threads::remove(this); 2007 delete this; 2008 } 2009 2010 2011 2012 2013 JavaThread* JavaThread::active() { 2014 Thread* thread = Thread::current(); 2015 if (thread->is_Java_thread()) { 2016 return (JavaThread*) thread; 2017 } else { 2018 assert(thread->is_VM_thread(), "this must be a vm thread"); 2019 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2020 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2021 assert(ret->is_Java_thread(), "must be a Java thread"); 2022 return ret; 2023 } 2024 } 2025 2026 bool JavaThread::is_lock_owned(address adr) const { 2027 if (Thread::is_lock_owned(adr)) return true; 2028 2029 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2030 if (chunk->contains(adr)) return true; 2031 } 2032 2033 return false; 2034 } 2035 2036 2037 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2038 chunk->set_next(monitor_chunks()); 2039 set_monitor_chunks(chunk); 2040 } 2041 2042 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2043 guarantee(monitor_chunks() != NULL, "must be non empty"); 2044 if (monitor_chunks() == chunk) { 2045 set_monitor_chunks(chunk->next()); 2046 } else { 2047 MonitorChunk* prev = monitor_chunks(); 2048 while (prev->next() != chunk) prev = prev->next(); 2049 prev->set_next(chunk->next()); 2050 } 2051 } 2052 2053 // JVM support. 2054 2055 // Note: this function shouldn't block if it's called in 2056 // _thread_in_native_trans state (such as from 2057 // check_special_condition_for_native_trans()). 2058 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2059 2060 if (has_last_Java_frame() && has_async_condition()) { 2061 // If we are at a polling page safepoint (not a poll return) 2062 // then we must defer async exception because live registers 2063 // will be clobbered by the exception path. Poll return is 2064 // ok because the call we a returning from already collides 2065 // with exception handling registers and so there is no issue. 2066 // (The exception handling path kills call result registers but 2067 // this is ok since the exception kills the result anyway). 2068 2069 if (is_at_poll_safepoint()) { 2070 // if the code we are returning to has deoptimized we must defer 2071 // the exception otherwise live registers get clobbered on the 2072 // exception path before deoptimization is able to retrieve them. 2073 // 2074 RegisterMap map(this, false); 2075 frame caller_fr = last_frame().sender(&map); 2076 assert(caller_fr.is_compiled_frame(), "what?"); 2077 if (caller_fr.is_deoptimized_frame()) { 2078 log_info(exceptions)("deferred async exception at compiled safepoint"); 2079 return; 2080 } 2081 } 2082 } 2083 2084 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2085 if (condition == _no_async_condition) { 2086 // Conditions have changed since has_special_runtime_exit_condition() 2087 // was called: 2088 // - if we were here only because of an external suspend request, 2089 // then that was taken care of above (or cancelled) so we are done 2090 // - if we were here because of another async request, then it has 2091 // been cleared between the has_special_runtime_exit_condition() 2092 // and now so again we are done 2093 return; 2094 } 2095 2096 // Check for pending async. exception 2097 if (_pending_async_exception != NULL) { 2098 // Only overwrite an already pending exception, if it is not a threadDeath. 2099 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2100 2101 // We cannot call Exceptions::_throw(...) here because we cannot block 2102 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2103 2104 if (log_is_enabled(Info, exceptions)) { 2105 ResourceMark rm; 2106 outputStream* logstream = Log(exceptions)::info_stream(); 2107 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2108 if (has_last_Java_frame()) { 2109 frame f = last_frame(); 2110 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2111 } 2112 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2113 } 2114 _pending_async_exception = NULL; 2115 clear_has_async_exception(); 2116 } 2117 } 2118 2119 if (check_unsafe_error && 2120 condition == _async_unsafe_access_error && !has_pending_exception()) { 2121 condition = _no_async_condition; // done 2122 switch (thread_state()) { 2123 case _thread_in_vm: { 2124 JavaThread* THREAD = this; 2125 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2126 } 2127 case _thread_in_native: { 2128 ThreadInVMfromNative tiv(this); 2129 JavaThread* THREAD = this; 2130 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2131 } 2132 case _thread_in_Java: { 2133 ThreadInVMfromJava tiv(this); 2134 JavaThread* THREAD = this; 2135 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2136 } 2137 default: 2138 ShouldNotReachHere(); 2139 } 2140 } 2141 2142 assert(condition == _no_async_condition || has_pending_exception() || 2143 (!check_unsafe_error && condition == _async_unsafe_access_error), 2144 "must have handled the async condition, if no exception"); 2145 } 2146 2147 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2148 // 2149 // Check for pending external suspend. Internal suspend requests do 2150 // not use handle_special_runtime_exit_condition(). 2151 // If JNIEnv proxies are allowed, don't self-suspend if the target 2152 // thread is not the current thread. In older versions of jdbx, jdbx 2153 // threads could call into the VM with another thread's JNIEnv so we 2154 // can be here operating on behalf of a suspended thread (4432884). 2155 bool do_self_suspend = is_external_suspend_with_lock(); 2156 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2157 // 2158 // Because thread is external suspended the safepoint code will count 2159 // thread as at a safepoint. This can be odd because we can be here 2160 // as _thread_in_Java which would normally transition to _thread_blocked 2161 // at a safepoint. We would like to mark the thread as _thread_blocked 2162 // before calling java_suspend_self like all other callers of it but 2163 // we must then observe proper safepoint protocol. (We can't leave 2164 // _thread_blocked with a safepoint in progress). However we can be 2165 // here as _thread_in_native_trans so we can't use a normal transition 2166 // constructor/destructor pair because they assert on that type of 2167 // transition. We could do something like: 2168 // 2169 // JavaThreadState state = thread_state(); 2170 // set_thread_state(_thread_in_vm); 2171 // { 2172 // ThreadBlockInVM tbivm(this); 2173 // java_suspend_self() 2174 // } 2175 // set_thread_state(_thread_in_vm_trans); 2176 // if (safepoint) block; 2177 // set_thread_state(state); 2178 // 2179 // but that is pretty messy. Instead we just go with the way the 2180 // code has worked before and note that this is the only path to 2181 // java_suspend_self that doesn't put the thread in _thread_blocked 2182 // mode. 2183 2184 frame_anchor()->make_walkable(this); 2185 java_suspend_self(); 2186 2187 // We might be here for reasons in addition to the self-suspend request 2188 // so check for other async requests. 2189 } 2190 2191 if (check_asyncs) { 2192 check_and_handle_async_exceptions(); 2193 } 2194 } 2195 2196 void JavaThread::send_thread_stop(oop java_throwable) { 2197 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2198 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2199 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2200 2201 // Do not throw asynchronous exceptions against the compiler thread 2202 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2203 if (!can_call_java()) return; 2204 2205 { 2206 // Actually throw the Throwable against the target Thread - however 2207 // only if there is no thread death exception installed already. 2208 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2209 // If the topmost frame is a runtime stub, then we are calling into 2210 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2211 // must deoptimize the caller before continuing, as the compiled exception handler table 2212 // may not be valid 2213 if (has_last_Java_frame()) { 2214 frame f = last_frame(); 2215 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2216 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2217 RegisterMap reg_map(this, UseBiasedLocking); 2218 frame compiled_frame = f.sender(®_map); 2219 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2220 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2221 } 2222 } 2223 } 2224 2225 // Set async. pending exception in thread. 2226 set_pending_async_exception(java_throwable); 2227 2228 if (log_is_enabled(Info, exceptions)) { 2229 ResourceMark rm; 2230 log_info(exceptions)("Pending Async. exception installed of type: %s", 2231 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2232 } 2233 // for AbortVMOnException flag 2234 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2235 } 2236 } 2237 2238 2239 // Interrupt thread so it will wake up from a potential wait() 2240 Thread::interrupt(this); 2241 } 2242 2243 // External suspension mechanism. 2244 // 2245 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2246 // to any VM_locks and it is at a transition 2247 // Self-suspension will happen on the transition out of the vm. 2248 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2249 // 2250 // Guarantees on return: 2251 // + Target thread will not execute any new bytecode (that's why we need to 2252 // force a safepoint) 2253 // + Target thread will not enter any new monitors 2254 // 2255 void JavaThread::java_suspend() { 2256 { MutexLocker mu(Threads_lock); 2257 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2258 return; 2259 } 2260 } 2261 2262 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2263 if (!is_external_suspend()) { 2264 // a racing resume has cancelled us; bail out now 2265 return; 2266 } 2267 2268 // suspend is done 2269 uint32_t debug_bits = 0; 2270 // Warning: is_ext_suspend_completed() may temporarily drop the 2271 // SR_lock to allow the thread to reach a stable thread state if 2272 // it is currently in a transient thread state. 2273 if (is_ext_suspend_completed(false /* !called_by_wait */, 2274 SuspendRetryDelay, &debug_bits)) { 2275 return; 2276 } 2277 } 2278 2279 VM_ThreadSuspend vm_suspend; 2280 VMThread::execute(&vm_suspend); 2281 } 2282 2283 // Part II of external suspension. 2284 // A JavaThread self suspends when it detects a pending external suspend 2285 // request. This is usually on transitions. It is also done in places 2286 // where continuing to the next transition would surprise the caller, 2287 // e.g., monitor entry. 2288 // 2289 // Returns the number of times that the thread self-suspended. 2290 // 2291 // Note: DO NOT call java_suspend_self() when you just want to block current 2292 // thread. java_suspend_self() is the second stage of cooperative 2293 // suspension for external suspend requests and should only be used 2294 // to complete an external suspend request. 2295 // 2296 int JavaThread::java_suspend_self() { 2297 int ret = 0; 2298 2299 // we are in the process of exiting so don't suspend 2300 if (is_exiting()) { 2301 clear_external_suspend(); 2302 return ret; 2303 } 2304 2305 assert(_anchor.walkable() || 2306 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2307 "must have walkable stack"); 2308 2309 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2310 2311 assert(!this->is_ext_suspended(), 2312 "a thread trying to self-suspend should not already be suspended"); 2313 2314 if (this->is_suspend_equivalent()) { 2315 // If we are self-suspending as a result of the lifting of a 2316 // suspend equivalent condition, then the suspend_equivalent 2317 // flag is not cleared until we set the ext_suspended flag so 2318 // that wait_for_ext_suspend_completion() returns consistent 2319 // results. 2320 this->clear_suspend_equivalent(); 2321 } 2322 2323 // A racing resume may have cancelled us before we grabbed SR_lock 2324 // above. Or another external suspend request could be waiting for us 2325 // by the time we return from SR_lock()->wait(). The thread 2326 // that requested the suspension may already be trying to walk our 2327 // stack and if we return now, we can change the stack out from under 2328 // it. This would be a "bad thing (TM)" and cause the stack walker 2329 // to crash. We stay self-suspended until there are no more pending 2330 // external suspend requests. 2331 while (is_external_suspend()) { 2332 ret++; 2333 this->set_ext_suspended(); 2334 2335 // _ext_suspended flag is cleared by java_resume() 2336 while (is_ext_suspended()) { 2337 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2338 } 2339 } 2340 2341 return ret; 2342 } 2343 2344 #ifdef ASSERT 2345 // verify the JavaThread has not yet been published in the Threads::list, and 2346 // hence doesn't need protection from concurrent access at this stage 2347 void JavaThread::verify_not_published() { 2348 if (!Threads_lock->owned_by_self()) { 2349 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2350 assert(!Threads::includes(this), 2351 "java thread shouldn't have been published yet!"); 2352 } else { 2353 assert(!Threads::includes(this), 2354 "java thread shouldn't have been published yet!"); 2355 } 2356 } 2357 #endif 2358 2359 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2360 // progress or when _suspend_flags is non-zero. 2361 // Current thread needs to self-suspend if there is a suspend request and/or 2362 // block if a safepoint is in progress. 2363 // Async exception ISN'T checked. 2364 // Note only the ThreadInVMfromNative transition can call this function 2365 // directly and when thread state is _thread_in_native_trans 2366 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2367 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2368 2369 JavaThread *curJT = JavaThread::current(); 2370 bool do_self_suspend = thread->is_external_suspend(); 2371 2372 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2373 2374 // If JNIEnv proxies are allowed, don't self-suspend if the target 2375 // thread is not the current thread. In older versions of jdbx, jdbx 2376 // threads could call into the VM with another thread's JNIEnv so we 2377 // can be here operating on behalf of a suspended thread (4432884). 2378 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2379 JavaThreadState state = thread->thread_state(); 2380 2381 // We mark this thread_blocked state as a suspend-equivalent so 2382 // that a caller to is_ext_suspend_completed() won't be confused. 2383 // The suspend-equivalent state is cleared by java_suspend_self(). 2384 thread->set_suspend_equivalent(); 2385 2386 // If the safepoint code sees the _thread_in_native_trans state, it will 2387 // wait until the thread changes to other thread state. There is no 2388 // guarantee on how soon we can obtain the SR_lock and complete the 2389 // self-suspend request. It would be a bad idea to let safepoint wait for 2390 // too long. Temporarily change the state to _thread_blocked to 2391 // let the VM thread know that this thread is ready for GC. The problem 2392 // of changing thread state is that safepoint could happen just after 2393 // java_suspend_self() returns after being resumed, and VM thread will 2394 // see the _thread_blocked state. We must check for safepoint 2395 // after restoring the state and make sure we won't leave while a safepoint 2396 // is in progress. 2397 thread->set_thread_state(_thread_blocked); 2398 thread->java_suspend_self(); 2399 thread->set_thread_state(state); 2400 // Make sure new state is seen by VM thread 2401 if (os::is_MP()) { 2402 if (UseMembar) { 2403 // Force a fence between the write above and read below 2404 OrderAccess::fence(); 2405 } else { 2406 // Must use this rather than serialization page in particular on Windows 2407 InterfaceSupport::serialize_memory(thread); 2408 } 2409 } 2410 } 2411 2412 if (SafepointSynchronize::do_call_back()) { 2413 // If we are safepointing, then block the caller which may not be 2414 // the same as the target thread (see above). 2415 SafepointSynchronize::block(curJT); 2416 } 2417 2418 if (thread->is_deopt_suspend()) { 2419 thread->clear_deopt_suspend(); 2420 RegisterMap map(thread, false); 2421 frame f = thread->last_frame(); 2422 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2423 f = f.sender(&map); 2424 } 2425 if (f.id() == thread->must_deopt_id()) { 2426 thread->clear_must_deopt_id(); 2427 f.deoptimize(thread); 2428 } else { 2429 fatal("missed deoptimization!"); 2430 } 2431 } 2432 } 2433 2434 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2435 // progress or when _suspend_flags is non-zero. 2436 // Current thread needs to self-suspend if there is a suspend request and/or 2437 // block if a safepoint is in progress. 2438 // Also check for pending async exception (not including unsafe access error). 2439 // Note only the native==>VM/Java barriers can call this function and when 2440 // thread state is _thread_in_native_trans. 2441 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2442 check_safepoint_and_suspend_for_native_trans(thread); 2443 2444 if (thread->has_async_exception()) { 2445 // We are in _thread_in_native_trans state, don't handle unsafe 2446 // access error since that may block. 2447 thread->check_and_handle_async_exceptions(false); 2448 } 2449 } 2450 2451 // This is a variant of the normal 2452 // check_special_condition_for_native_trans with slightly different 2453 // semantics for use by critical native wrappers. It does all the 2454 // normal checks but also performs the transition back into 2455 // thread_in_Java state. This is required so that critical natives 2456 // can potentially block and perform a GC if they are the last thread 2457 // exiting the GCLocker. 2458 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2459 check_special_condition_for_native_trans(thread); 2460 2461 // Finish the transition 2462 thread->set_thread_state(_thread_in_Java); 2463 2464 if (thread->do_critical_native_unlock()) { 2465 ThreadInVMfromJavaNoAsyncException tiv(thread); 2466 GCLocker::unlock_critical(thread); 2467 thread->clear_critical_native_unlock(); 2468 } 2469 } 2470 2471 // We need to guarantee the Threads_lock here, since resumes are not 2472 // allowed during safepoint synchronization 2473 // Can only resume from an external suspension 2474 void JavaThread::java_resume() { 2475 assert_locked_or_safepoint(Threads_lock); 2476 2477 // Sanity check: thread is gone, has started exiting or the thread 2478 // was not externally suspended. 2479 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2480 return; 2481 } 2482 2483 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2484 2485 clear_external_suspend(); 2486 2487 if (is_ext_suspended()) { 2488 clear_ext_suspended(); 2489 SR_lock()->notify_all(); 2490 } 2491 } 2492 2493 size_t JavaThread::_stack_red_zone_size = 0; 2494 size_t JavaThread::_stack_yellow_zone_size = 0; 2495 size_t JavaThread::_stack_reserved_zone_size = 0; 2496 size_t JavaThread::_stack_shadow_zone_size = 0; 2497 2498 void JavaThread::create_stack_guard_pages() { 2499 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2500 address low_addr = stack_end(); 2501 size_t len = stack_guard_zone_size(); 2502 2503 int must_commit = os::must_commit_stack_guard_pages(); 2504 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2505 2506 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2507 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2508 return; 2509 } 2510 2511 if (os::guard_memory((char *) low_addr, len)) { 2512 _stack_guard_state = stack_guard_enabled; 2513 } else { 2514 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2515 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2516 if (os::uncommit_memory((char *) low_addr, len)) { 2517 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2518 } 2519 return; 2520 } 2521 2522 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2523 PTR_FORMAT "-" PTR_FORMAT ".", 2524 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2525 } 2526 2527 void JavaThread::remove_stack_guard_pages() { 2528 assert(Thread::current() == this, "from different thread"); 2529 if (_stack_guard_state == stack_guard_unused) return; 2530 address low_addr = stack_end(); 2531 size_t len = stack_guard_zone_size(); 2532 2533 if (os::must_commit_stack_guard_pages()) { 2534 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2535 _stack_guard_state = stack_guard_unused; 2536 } else { 2537 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2538 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2539 return; 2540 } 2541 } else { 2542 if (_stack_guard_state == stack_guard_unused) return; 2543 if (os::unguard_memory((char *) low_addr, len)) { 2544 _stack_guard_state = stack_guard_unused; 2545 } else { 2546 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2547 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2548 return; 2549 } 2550 } 2551 2552 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2553 PTR_FORMAT "-" PTR_FORMAT ".", 2554 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2555 } 2556 2557 void JavaThread::enable_stack_reserved_zone() { 2558 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2559 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2560 2561 // The base notation is from the stack's point of view, growing downward. 2562 // We need to adjust it to work correctly with guard_memory() 2563 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2564 2565 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2566 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2567 2568 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2569 _stack_guard_state = stack_guard_enabled; 2570 } else { 2571 warning("Attempt to guard stack reserved zone failed."); 2572 } 2573 enable_register_stack_guard(); 2574 } 2575 2576 void JavaThread::disable_stack_reserved_zone() { 2577 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2578 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2579 2580 // Simply return if called for a thread that does not use guard pages. 2581 if (_stack_guard_state == stack_guard_unused) return; 2582 2583 // The base notation is from the stack's point of view, growing downward. 2584 // We need to adjust it to work correctly with guard_memory() 2585 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2586 2587 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2588 _stack_guard_state = stack_guard_reserved_disabled; 2589 } else { 2590 warning("Attempt to unguard stack reserved zone failed."); 2591 } 2592 disable_register_stack_guard(); 2593 } 2594 2595 void JavaThread::enable_stack_yellow_reserved_zone() { 2596 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2597 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2598 2599 // The base notation is from the stacks point of view, growing downward. 2600 // We need to adjust it to work correctly with guard_memory() 2601 address base = stack_red_zone_base(); 2602 2603 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2604 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2605 2606 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2607 _stack_guard_state = stack_guard_enabled; 2608 } else { 2609 warning("Attempt to guard stack yellow zone failed."); 2610 } 2611 enable_register_stack_guard(); 2612 } 2613 2614 void JavaThread::disable_stack_yellow_reserved_zone() { 2615 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2616 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2617 2618 // Simply return if called for a thread that does not use guard pages. 2619 if (_stack_guard_state == stack_guard_unused) return; 2620 2621 // The base notation is from the stacks point of view, growing downward. 2622 // We need to adjust it to work correctly with guard_memory() 2623 address base = stack_red_zone_base(); 2624 2625 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2626 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2627 } else { 2628 warning("Attempt to unguard stack yellow zone failed."); 2629 } 2630 disable_register_stack_guard(); 2631 } 2632 2633 void JavaThread::enable_stack_red_zone() { 2634 // The base notation is from the stacks point of view, growing downward. 2635 // We need to adjust it to work correctly with guard_memory() 2636 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2637 address base = stack_red_zone_base() - stack_red_zone_size(); 2638 2639 guarantee(base < stack_base(), "Error calculating stack red zone"); 2640 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2641 2642 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2643 warning("Attempt to guard stack red zone failed."); 2644 } 2645 } 2646 2647 void JavaThread::disable_stack_red_zone() { 2648 // The base notation is from the stacks point of view, growing downward. 2649 // We need to adjust it to work correctly with guard_memory() 2650 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2651 address base = stack_red_zone_base() - stack_red_zone_size(); 2652 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2653 warning("Attempt to unguard stack red zone failed."); 2654 } 2655 } 2656 2657 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2658 // ignore is there is no stack 2659 if (!has_last_Java_frame()) return; 2660 // traverse the stack frames. Starts from top frame. 2661 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2662 frame* fr = fst.current(); 2663 f(fr, fst.register_map()); 2664 } 2665 } 2666 2667 2668 #ifndef PRODUCT 2669 // Deoptimization 2670 // Function for testing deoptimization 2671 void JavaThread::deoptimize() { 2672 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2673 StackFrameStream fst(this, UseBiasedLocking); 2674 bool deopt = false; // Dump stack only if a deopt actually happens. 2675 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2676 // Iterate over all frames in the thread and deoptimize 2677 for (; !fst.is_done(); fst.next()) { 2678 if (fst.current()->can_be_deoptimized()) { 2679 2680 if (only_at) { 2681 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2682 // consists of comma or carriage return separated numbers so 2683 // search for the current bci in that string. 2684 address pc = fst.current()->pc(); 2685 nmethod* nm = (nmethod*) fst.current()->cb(); 2686 ScopeDesc* sd = nm->scope_desc_at(pc); 2687 char buffer[8]; 2688 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2689 size_t len = strlen(buffer); 2690 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2691 while (found != NULL) { 2692 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2693 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2694 // Check that the bci found is bracketed by terminators. 2695 break; 2696 } 2697 found = strstr(found + 1, buffer); 2698 } 2699 if (!found) { 2700 continue; 2701 } 2702 } 2703 2704 if (DebugDeoptimization && !deopt) { 2705 deopt = true; // One-time only print before deopt 2706 tty->print_cr("[BEFORE Deoptimization]"); 2707 trace_frames(); 2708 trace_stack(); 2709 } 2710 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2711 } 2712 } 2713 2714 if (DebugDeoptimization && deopt) { 2715 tty->print_cr("[AFTER Deoptimization]"); 2716 trace_frames(); 2717 } 2718 } 2719 2720 2721 // Make zombies 2722 void JavaThread::make_zombies() { 2723 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2724 if (fst.current()->can_be_deoptimized()) { 2725 // it is a Java nmethod 2726 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2727 nm->make_not_entrant(); 2728 } 2729 } 2730 } 2731 #endif // PRODUCT 2732 2733 2734 void JavaThread::deoptimized_wrt_marked_nmethods() { 2735 if (!has_last_Java_frame()) return; 2736 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2737 StackFrameStream fst(this, UseBiasedLocking); 2738 for (; !fst.is_done(); fst.next()) { 2739 if (fst.current()->should_be_deoptimized()) { 2740 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2741 } 2742 } 2743 } 2744 2745 2746 // If the caller is a NamedThread, then remember, in the current scope, 2747 // the given JavaThread in its _processed_thread field. 2748 class RememberProcessedThread: public StackObj { 2749 NamedThread* _cur_thr; 2750 public: 2751 RememberProcessedThread(JavaThread* jthr) { 2752 Thread* thread = Thread::current(); 2753 if (thread->is_Named_thread()) { 2754 _cur_thr = (NamedThread *)thread; 2755 _cur_thr->set_processed_thread(jthr); 2756 } else { 2757 _cur_thr = NULL; 2758 } 2759 } 2760 2761 ~RememberProcessedThread() { 2762 if (_cur_thr) { 2763 _cur_thr->set_processed_thread(NULL); 2764 } 2765 } 2766 }; 2767 2768 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2769 // Verify that the deferred card marks have been flushed. 2770 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2771 2772 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2773 // since there may be more than one thread using each ThreadProfiler. 2774 2775 // Traverse the GCHandles 2776 Thread::oops_do(f, cf); 2777 2778 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2779 2780 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2781 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2782 2783 if (has_last_Java_frame()) { 2784 // Record JavaThread to GC thread 2785 RememberProcessedThread rpt(this); 2786 2787 // Traverse the privileged stack 2788 if (_privileged_stack_top != NULL) { 2789 _privileged_stack_top->oops_do(f); 2790 } 2791 2792 // traverse the registered growable array 2793 if (_array_for_gc != NULL) { 2794 for (int index = 0; index < _array_for_gc->length(); index++) { 2795 f->do_oop(_array_for_gc->adr_at(index)); 2796 } 2797 } 2798 2799 // Traverse the monitor chunks 2800 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2801 chunk->oops_do(f); 2802 } 2803 2804 // Traverse the execution stack 2805 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2806 fst.current()->oops_do(f, cf, fst.register_map()); 2807 } 2808 } 2809 2810 // callee_target is never live across a gc point so NULL it here should 2811 // it still contain a methdOop. 2812 2813 set_callee_target(NULL); 2814 2815 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2816 // If we have deferred set_locals there might be oops waiting to be 2817 // written 2818 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2819 if (list != NULL) { 2820 for (int i = 0; i < list->length(); i++) { 2821 list->at(i)->oops_do(f); 2822 } 2823 } 2824 2825 // Traverse instance variables at the end since the GC may be moving things 2826 // around using this function 2827 f->do_oop((oop*) &_threadObj); 2828 f->do_oop((oop*) &_vm_result); 2829 f->do_oop((oop*) &_exception_oop); 2830 f->do_oop((oop*) &_pending_async_exception); 2831 2832 if (jvmti_thread_state() != NULL) { 2833 jvmti_thread_state()->oops_do(f); 2834 } 2835 } 2836 2837 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2838 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2839 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2840 2841 if (has_last_Java_frame()) { 2842 // Traverse the execution stack 2843 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2844 fst.current()->nmethods_do(cf); 2845 } 2846 } 2847 } 2848 2849 void JavaThread::metadata_do(void f(Metadata*)) { 2850 if (has_last_Java_frame()) { 2851 // Traverse the execution stack to call f() on the methods in the stack 2852 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2853 fst.current()->metadata_do(f); 2854 } 2855 } else if (is_Compiler_thread()) { 2856 // need to walk ciMetadata in current compile tasks to keep alive. 2857 CompilerThread* ct = (CompilerThread*)this; 2858 if (ct->env() != NULL) { 2859 ct->env()->metadata_do(f); 2860 } 2861 if (ct->task() != NULL) { 2862 ct->task()->metadata_do(f); 2863 } 2864 } 2865 } 2866 2867 // Printing 2868 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2869 switch (_thread_state) { 2870 case _thread_uninitialized: return "_thread_uninitialized"; 2871 case _thread_new: return "_thread_new"; 2872 case _thread_new_trans: return "_thread_new_trans"; 2873 case _thread_in_native: return "_thread_in_native"; 2874 case _thread_in_native_trans: return "_thread_in_native_trans"; 2875 case _thread_in_vm: return "_thread_in_vm"; 2876 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2877 case _thread_in_Java: return "_thread_in_Java"; 2878 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2879 case _thread_blocked: return "_thread_blocked"; 2880 case _thread_blocked_trans: return "_thread_blocked_trans"; 2881 default: return "unknown thread state"; 2882 } 2883 } 2884 2885 #ifndef PRODUCT 2886 void JavaThread::print_thread_state_on(outputStream *st) const { 2887 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2888 }; 2889 void JavaThread::print_thread_state() const { 2890 print_thread_state_on(tty); 2891 } 2892 #endif // PRODUCT 2893 2894 // Called by Threads::print() for VM_PrintThreads operation 2895 void JavaThread::print_on(outputStream *st) const { 2896 st->print_raw("\""); 2897 st->print_raw(get_thread_name()); 2898 st->print_raw("\" "); 2899 oop thread_oop = threadObj(); 2900 if (thread_oop != NULL) { 2901 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2902 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2903 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2904 } 2905 Thread::print_on(st); 2906 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2907 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2908 if (thread_oop != NULL) { 2909 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2910 } 2911 #ifndef PRODUCT 2912 print_thread_state_on(st); 2913 _safepoint_state->print_on(st); 2914 #endif // PRODUCT 2915 if (is_Compiler_thread()) { 2916 CompilerThread* ct = (CompilerThread*)this; 2917 if (ct->task() != NULL) { 2918 st->print(" Compiling: "); 2919 ct->task()->print(st, NULL, true, false); 2920 } else { 2921 st->print(" No compile task"); 2922 } 2923 st->cr(); 2924 } 2925 } 2926 2927 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2928 st->print("%s", get_thread_name_string(buf, buflen)); 2929 } 2930 2931 // Called by fatal error handler. The difference between this and 2932 // JavaThread::print() is that we can't grab lock or allocate memory. 2933 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2934 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2935 oop thread_obj = threadObj(); 2936 if (thread_obj != NULL) { 2937 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2938 } 2939 st->print(" ["); 2940 st->print("%s", _get_thread_state_name(_thread_state)); 2941 if (osthread()) { 2942 st->print(", id=%d", osthread()->thread_id()); 2943 } 2944 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2945 p2i(stack_end()), p2i(stack_base())); 2946 st->print("]"); 2947 return; 2948 } 2949 2950 // Verification 2951 2952 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2953 2954 void JavaThread::verify() { 2955 // Verify oops in the thread. 2956 oops_do(&VerifyOopClosure::verify_oop, NULL); 2957 2958 // Verify the stack frames. 2959 frames_do(frame_verify); 2960 } 2961 2962 // CR 6300358 (sub-CR 2137150) 2963 // Most callers of this method assume that it can't return NULL but a 2964 // thread may not have a name whilst it is in the process of attaching to 2965 // the VM - see CR 6412693, and there are places where a JavaThread can be 2966 // seen prior to having it's threadObj set (eg JNI attaching threads and 2967 // if vm exit occurs during initialization). These cases can all be accounted 2968 // for such that this method never returns NULL. 2969 const char* JavaThread::get_thread_name() const { 2970 #ifdef ASSERT 2971 // early safepoints can hit while current thread does not yet have TLS 2972 if (!SafepointSynchronize::is_at_safepoint()) { 2973 Thread *cur = Thread::current(); 2974 if (!(cur->is_Java_thread() && cur == this)) { 2975 // Current JavaThreads are allowed to get their own name without 2976 // the Threads_lock. 2977 assert_locked_or_safepoint(Threads_lock); 2978 } 2979 } 2980 #endif // ASSERT 2981 return get_thread_name_string(); 2982 } 2983 2984 // Returns a non-NULL representation of this thread's name, or a suitable 2985 // descriptive string if there is no set name 2986 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2987 const char* name_str; 2988 oop thread_obj = threadObj(); 2989 if (thread_obj != NULL) { 2990 oop name = java_lang_Thread::name(thread_obj); 2991 if (name != NULL) { 2992 if (buf == NULL) { 2993 name_str = java_lang_String::as_utf8_string(name); 2994 } else { 2995 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2996 } 2997 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2998 name_str = "<no-name - thread is attaching>"; 2999 } else { 3000 name_str = Thread::name(); 3001 } 3002 } else { 3003 name_str = Thread::name(); 3004 } 3005 assert(name_str != NULL, "unexpected NULL thread name"); 3006 return name_str; 3007 } 3008 3009 3010 const char* JavaThread::get_threadgroup_name() const { 3011 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3012 oop thread_obj = threadObj(); 3013 if (thread_obj != NULL) { 3014 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3015 if (thread_group != NULL) { 3016 // ThreadGroup.name can be null 3017 return java_lang_ThreadGroup::name(thread_group); 3018 } 3019 } 3020 return NULL; 3021 } 3022 3023 const char* JavaThread::get_parent_name() const { 3024 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3025 oop thread_obj = threadObj(); 3026 if (thread_obj != NULL) { 3027 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3028 if (thread_group != NULL) { 3029 oop parent = java_lang_ThreadGroup::parent(thread_group); 3030 if (parent != NULL) { 3031 // ThreadGroup.name can be null 3032 return java_lang_ThreadGroup::name(parent); 3033 } 3034 } 3035 } 3036 return NULL; 3037 } 3038 3039 ThreadPriority JavaThread::java_priority() const { 3040 oop thr_oop = threadObj(); 3041 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3042 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3043 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3044 return priority; 3045 } 3046 3047 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3048 3049 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3050 // Link Java Thread object <-> C++ Thread 3051 3052 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3053 // and put it into a new Handle. The Handle "thread_oop" can then 3054 // be used to pass the C++ thread object to other methods. 3055 3056 // Set the Java level thread object (jthread) field of the 3057 // new thread (a JavaThread *) to C++ thread object using the 3058 // "thread_oop" handle. 3059 3060 // Set the thread field (a JavaThread *) of the 3061 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3062 3063 Handle thread_oop(Thread::current(), 3064 JNIHandles::resolve_non_null(jni_thread)); 3065 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3066 "must be initialized"); 3067 set_threadObj(thread_oop()); 3068 java_lang_Thread::set_thread(thread_oop(), this); 3069 3070 if (prio == NoPriority) { 3071 prio = java_lang_Thread::priority(thread_oop()); 3072 assert(prio != NoPriority, "A valid priority should be present"); 3073 } 3074 3075 // Push the Java priority down to the native thread; needs Threads_lock 3076 Thread::set_priority(this, prio); 3077 3078 prepare_ext(); 3079 3080 // Add the new thread to the Threads list and set it in motion. 3081 // We must have threads lock in order to call Threads::add. 3082 // It is crucial that we do not block before the thread is 3083 // added to the Threads list for if a GC happens, then the java_thread oop 3084 // will not be visited by GC. 3085 Threads::add(this); 3086 } 3087 3088 oop JavaThread::current_park_blocker() { 3089 // Support for JSR-166 locks 3090 oop thread_oop = threadObj(); 3091 if (thread_oop != NULL && 3092 JDK_Version::current().supports_thread_park_blocker()) { 3093 return java_lang_Thread::park_blocker(thread_oop); 3094 } 3095 return NULL; 3096 } 3097 3098 3099 void JavaThread::print_stack_on(outputStream* st) { 3100 if (!has_last_Java_frame()) return; 3101 ResourceMark rm; 3102 HandleMark hm; 3103 3104 RegisterMap reg_map(this); 3105 vframe* start_vf = last_java_vframe(®_map); 3106 int count = 0; 3107 for (vframe* f = start_vf; f; f = f->sender()) { 3108 if (f->is_java_frame()) { 3109 javaVFrame* jvf = javaVFrame::cast(f); 3110 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3111 3112 // Print out lock information 3113 if (JavaMonitorsInStackTrace) { 3114 jvf->print_lock_info_on(st, count); 3115 } 3116 } else { 3117 // Ignore non-Java frames 3118 } 3119 3120 // Bail-out case for too deep stacks 3121 count++; 3122 if (MaxJavaStackTraceDepth == count) return; 3123 } 3124 } 3125 3126 3127 // JVMTI PopFrame support 3128 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3129 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3130 if (in_bytes(size_in_bytes) != 0) { 3131 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3132 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3133 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3134 } 3135 } 3136 3137 void* JavaThread::popframe_preserved_args() { 3138 return _popframe_preserved_args; 3139 } 3140 3141 ByteSize JavaThread::popframe_preserved_args_size() { 3142 return in_ByteSize(_popframe_preserved_args_size); 3143 } 3144 3145 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3146 int sz = in_bytes(popframe_preserved_args_size()); 3147 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3148 return in_WordSize(sz / wordSize); 3149 } 3150 3151 void JavaThread::popframe_free_preserved_args() { 3152 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3153 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3154 _popframe_preserved_args = NULL; 3155 _popframe_preserved_args_size = 0; 3156 } 3157 3158 #ifndef PRODUCT 3159 3160 void JavaThread::trace_frames() { 3161 tty->print_cr("[Describe stack]"); 3162 int frame_no = 1; 3163 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3164 tty->print(" %d. ", frame_no++); 3165 fst.current()->print_value_on(tty, this); 3166 tty->cr(); 3167 } 3168 } 3169 3170 class PrintAndVerifyOopClosure: public OopClosure { 3171 protected: 3172 template <class T> inline void do_oop_work(T* p) { 3173 oop obj = oopDesc::load_decode_heap_oop(p); 3174 if (obj == NULL) return; 3175 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3176 if (obj->is_oop_or_null()) { 3177 if (obj->is_objArray()) { 3178 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3179 } else { 3180 obj->print(); 3181 } 3182 } else { 3183 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3184 } 3185 tty->cr(); 3186 } 3187 public: 3188 virtual void do_oop(oop* p) { do_oop_work(p); } 3189 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3190 }; 3191 3192 3193 static void oops_print(frame* f, const RegisterMap *map) { 3194 PrintAndVerifyOopClosure print; 3195 f->print_value(); 3196 f->oops_do(&print, NULL, (RegisterMap*)map); 3197 } 3198 3199 // Print our all the locations that contain oops and whether they are 3200 // valid or not. This useful when trying to find the oldest frame 3201 // where an oop has gone bad since the frame walk is from youngest to 3202 // oldest. 3203 void JavaThread::trace_oops() { 3204 tty->print_cr("[Trace oops]"); 3205 frames_do(oops_print); 3206 } 3207 3208 3209 #ifdef ASSERT 3210 // Print or validate the layout of stack frames 3211 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3212 ResourceMark rm; 3213 PRESERVE_EXCEPTION_MARK; 3214 FrameValues values; 3215 int frame_no = 0; 3216 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3217 fst.current()->describe(values, ++frame_no); 3218 if (depth == frame_no) break; 3219 } 3220 if (validate_only) { 3221 values.validate(); 3222 } else { 3223 tty->print_cr("[Describe stack layout]"); 3224 values.print(this); 3225 } 3226 } 3227 #endif 3228 3229 void JavaThread::trace_stack_from(vframe* start_vf) { 3230 ResourceMark rm; 3231 int vframe_no = 1; 3232 for (vframe* f = start_vf; f; f = f->sender()) { 3233 if (f->is_java_frame()) { 3234 javaVFrame::cast(f)->print_activation(vframe_no++); 3235 } else { 3236 f->print(); 3237 } 3238 if (vframe_no > StackPrintLimit) { 3239 tty->print_cr("...<more frames>..."); 3240 return; 3241 } 3242 } 3243 } 3244 3245 3246 void JavaThread::trace_stack() { 3247 if (!has_last_Java_frame()) return; 3248 ResourceMark rm; 3249 HandleMark hm; 3250 RegisterMap reg_map(this); 3251 trace_stack_from(last_java_vframe(®_map)); 3252 } 3253 3254 3255 #endif // PRODUCT 3256 3257 3258 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3259 assert(reg_map != NULL, "a map must be given"); 3260 frame f = last_frame(); 3261 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3262 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3263 } 3264 return NULL; 3265 } 3266 3267 3268 Klass* JavaThread::security_get_caller_class(int depth) { 3269 vframeStream vfst(this); 3270 vfst.security_get_caller_frame(depth); 3271 if (!vfst.at_end()) { 3272 return vfst.method()->method_holder(); 3273 } 3274 return NULL; 3275 } 3276 3277 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3278 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3279 CompileBroker::compiler_thread_loop(); 3280 } 3281 3282 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3283 NMethodSweeper::sweeper_loop(); 3284 } 3285 3286 // Create a CompilerThread 3287 CompilerThread::CompilerThread(CompileQueue* queue, 3288 CompilerCounters* counters) 3289 : JavaThread(&compiler_thread_entry) { 3290 _env = NULL; 3291 _log = NULL; 3292 _task = NULL; 3293 _queue = queue; 3294 _counters = counters; 3295 _buffer_blob = NULL; 3296 _compiler = NULL; 3297 3298 #ifndef PRODUCT 3299 _ideal_graph_printer = NULL; 3300 #endif 3301 } 3302 3303 bool CompilerThread::can_call_java() const { 3304 return _compiler != NULL && _compiler->is_jvmci(); 3305 } 3306 3307 // Create sweeper thread 3308 CodeCacheSweeperThread::CodeCacheSweeperThread() 3309 : JavaThread(&sweeper_thread_entry) { 3310 _scanned_compiled_method = NULL; 3311 } 3312 3313 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3314 JavaThread::oops_do(f, cf); 3315 if (_scanned_compiled_method != NULL && cf != NULL) { 3316 // Safepoints can occur when the sweeper is scanning an nmethod so 3317 // process it here to make sure it isn't unloaded in the middle of 3318 // a scan. 3319 cf->do_code_blob(_scanned_compiled_method); 3320 } 3321 } 3322 3323 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3324 JavaThread::nmethods_do(cf); 3325 if (_scanned_compiled_method != NULL && cf != NULL) { 3326 // Safepoints can occur when the sweeper is scanning an nmethod so 3327 // process it here to make sure it isn't unloaded in the middle of 3328 // a scan. 3329 cf->do_code_blob(_scanned_compiled_method); 3330 } 3331 } 3332 3333 3334 // ======= Threads ======== 3335 3336 // The Threads class links together all active threads, and provides 3337 // operations over all threads. It is protected by its own Mutex 3338 // lock, which is also used in other contexts to protect thread 3339 // operations from having the thread being operated on from exiting 3340 // and going away unexpectedly (e.g., safepoint synchronization) 3341 3342 JavaThread* Threads::_thread_list = NULL; 3343 int Threads::_number_of_threads = 0; 3344 int Threads::_number_of_non_daemon_threads = 0; 3345 int Threads::_return_code = 0; 3346 int Threads::_thread_claim_parity = 0; 3347 size_t JavaThread::_stack_size_at_create = 0; 3348 #ifdef ASSERT 3349 bool Threads::_vm_complete = false; 3350 #endif 3351 3352 // All JavaThreads 3353 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3354 3355 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3356 void Threads::threads_do(ThreadClosure* tc) { 3357 assert_locked_or_safepoint(Threads_lock); 3358 // ALL_JAVA_THREADS iterates through all JavaThreads 3359 ALL_JAVA_THREADS(p) { 3360 tc->do_thread(p); 3361 } 3362 // Someday we could have a table or list of all non-JavaThreads. 3363 // For now, just manually iterate through them. 3364 tc->do_thread(VMThread::vm_thread()); 3365 Universe::heap()->gc_threads_do(tc); 3366 WatcherThread *wt = WatcherThread::watcher_thread(); 3367 // Strictly speaking, the following NULL check isn't sufficient to make sure 3368 // the data for WatcherThread is still valid upon being examined. However, 3369 // considering that WatchThread terminates when the VM is on the way to 3370 // exit at safepoint, the chance of the above is extremely small. The right 3371 // way to prevent termination of WatcherThread would be to acquire 3372 // Terminator_lock, but we can't do that without violating the lock rank 3373 // checking in some cases. 3374 if (wt != NULL) { 3375 tc->do_thread(wt); 3376 } 3377 3378 // If CompilerThreads ever become non-JavaThreads, add them here 3379 } 3380 3381 // The system initialization in the library has three phases. 3382 // 3383 // Phase 1: java.lang.System class initialization 3384 // java.lang.System is a primordial class loaded and initialized 3385 // by the VM early during startup. java.lang.System.<clinit> 3386 // only does registerNatives and keeps the rest of the class 3387 // initialization work later until thread initialization completes. 3388 // 3389 // System.initPhase1 initializes the system properties, the static 3390 // fields in, out, and err. Set up java signal handlers, OS-specific 3391 // system settings, and thread group of the main thread. 3392 static void call_initPhase1(TRAPS) { 3393 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3394 JavaValue result(T_VOID); 3395 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3396 vmSymbols::void_method_signature(), CHECK); 3397 } 3398 3399 // Phase 2. Module system initialization 3400 // This will initialize the module system. Only java.base classes 3401 // can be loaded until phase 2 completes. 3402 // 3403 // Call System.initPhase2 after the compiler initialization and jsr292 3404 // classes get initialized because module initialization runs a lot of java 3405 // code, that for performance reasons, should be compiled. Also, this will 3406 // enable the startup code to use lambda and other language features in this 3407 // phase and onward. 3408 // 3409 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3410 static void call_initPhase2(TRAPS) { 3411 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime)); 3412 3413 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3414 3415 JavaValue result(T_INT); 3416 JavaCallArguments args; 3417 args.push_int(DisplayVMOutputToStderr); 3418 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3419 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3420 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3421 if (result.get_jint() != JNI_OK) { 3422 vm_exit_during_initialization(); // no message or exception 3423 } 3424 3425 universe_post_module_init(); 3426 } 3427 3428 // Phase 3. final setup - set security manager, system class loader and TCCL 3429 // 3430 // This will instantiate and set the security manager, set the system class 3431 // loader as well as the thread context class loader. The security manager 3432 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3433 // other modules or the application's classpath. 3434 static void call_initPhase3(TRAPS) { 3435 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3436 JavaValue result(T_VOID); 3437 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3438 vmSymbols::void_method_signature(), CHECK); 3439 } 3440 3441 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3442 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3443 3444 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3445 create_vm_init_libraries(); 3446 } 3447 3448 initialize_class(vmSymbols::java_lang_String(), CHECK); 3449 3450 // Inject CompactStrings value after the static initializers for String ran. 3451 java_lang_String::set_compact_strings(CompactStrings); 3452 3453 // Initialize java_lang.System (needed before creating the thread) 3454 initialize_class(vmSymbols::java_lang_System(), CHECK); 3455 // The VM creates & returns objects of this class. Make sure it's initialized. 3456 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3457 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3458 Handle thread_group = create_initial_thread_group(CHECK); 3459 Universe::set_main_thread_group(thread_group()); 3460 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3461 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3462 main_thread->set_threadObj(thread_object); 3463 // Set thread status to running since main thread has 3464 // been started and running. 3465 java_lang_Thread::set_thread_status(thread_object, 3466 java_lang_Thread::RUNNABLE); 3467 3468 // The VM creates objects of this class. 3469 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3470 3471 // The VM preresolves methods to these classes. Make sure that they get initialized 3472 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3473 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3474 3475 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3476 call_initPhase1(CHECK); 3477 3478 // get the Java runtime name after java.lang.System is initialized 3479 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3480 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3481 3482 // an instance of OutOfMemory exception has been allocated earlier 3483 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3484 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3485 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3486 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3487 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3488 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3489 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3490 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3491 } 3492 3493 void Threads::initialize_jsr292_core_classes(TRAPS) { 3494 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3495 3496 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3497 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3498 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3499 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3500 } 3501 3502 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3503 extern void JDK_Version_init(); 3504 3505 // Preinitialize version info. 3506 VM_Version::early_initialize(); 3507 3508 // Check version 3509 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3510 3511 // Initialize library-based TLS 3512 ThreadLocalStorage::init(); 3513 3514 // Initialize the output stream module 3515 ostream_init(); 3516 3517 // Process java launcher properties. 3518 Arguments::process_sun_java_launcher_properties(args); 3519 3520 // Initialize the os module 3521 os::init(); 3522 3523 // Record VM creation timing statistics 3524 TraceVmCreationTime create_vm_timer; 3525 create_vm_timer.start(); 3526 3527 // Initialize system properties. 3528 Arguments::init_system_properties(); 3529 3530 // So that JDK version can be used as a discriminator when parsing arguments 3531 JDK_Version_init(); 3532 3533 // Update/Initialize System properties after JDK version number is known 3534 Arguments::init_version_specific_system_properties(); 3535 3536 // Make sure to initialize log configuration *before* parsing arguments 3537 LogConfiguration::initialize(create_vm_timer.begin_time()); 3538 3539 // Parse arguments 3540 jint parse_result = Arguments::parse(args); 3541 if (parse_result != JNI_OK) return parse_result; 3542 3543 os::init_before_ergo(); 3544 3545 jint ergo_result = Arguments::apply_ergo(); 3546 if (ergo_result != JNI_OK) return ergo_result; 3547 3548 // Final check of all ranges after ergonomics which may change values. 3549 if (!CommandLineFlagRangeList::check_ranges()) { 3550 return JNI_EINVAL; 3551 } 3552 3553 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3554 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3555 if (!constraint_result) { 3556 return JNI_EINVAL; 3557 } 3558 3559 CommandLineFlagWriteableList::mark_startup(); 3560 3561 if (PauseAtStartup) { 3562 os::pause(); 3563 } 3564 3565 HOTSPOT_VM_INIT_BEGIN(); 3566 3567 // Timing (must come after argument parsing) 3568 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3569 3570 // Initialize the os module after parsing the args 3571 jint os_init_2_result = os::init_2(); 3572 if (os_init_2_result != JNI_OK) return os_init_2_result; 3573 3574 jint adjust_after_os_result = Arguments::adjust_after_os(); 3575 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3576 3577 // Initialize output stream logging 3578 ostream_init_log(); 3579 3580 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3581 // Must be before create_vm_init_agents() 3582 if (Arguments::init_libraries_at_startup()) { 3583 convert_vm_init_libraries_to_agents(); 3584 } 3585 3586 // Launch -agentlib/-agentpath and converted -Xrun agents 3587 if (Arguments::init_agents_at_startup()) { 3588 create_vm_init_agents(); 3589 } 3590 3591 // Initialize Threads state 3592 _thread_list = NULL; 3593 _number_of_threads = 0; 3594 _number_of_non_daemon_threads = 0; 3595 3596 // Initialize global data structures and create system classes in heap 3597 vm_init_globals(); 3598 3599 #if INCLUDE_JVMCI 3600 if (JVMCICounterSize > 0) { 3601 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3602 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3603 } else { 3604 JavaThread::_jvmci_old_thread_counters = NULL; 3605 } 3606 #endif // INCLUDE_JVMCI 3607 3608 // Attach the main thread to this os thread 3609 JavaThread* main_thread = new JavaThread(); 3610 main_thread->set_thread_state(_thread_in_vm); 3611 main_thread->initialize_thread_current(); 3612 // must do this before set_active_handles 3613 main_thread->record_stack_base_and_size(); 3614 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3615 3616 if (!main_thread->set_as_starting_thread()) { 3617 vm_shutdown_during_initialization( 3618 "Failed necessary internal allocation. Out of swap space"); 3619 delete main_thread; 3620 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3621 return JNI_ENOMEM; 3622 } 3623 3624 // Enable guard page *after* os::create_main_thread(), otherwise it would 3625 // crash Linux VM, see notes in os_linux.cpp. 3626 main_thread->create_stack_guard_pages(); 3627 3628 // Initialize Java-Level synchronization subsystem 3629 ObjectMonitor::Initialize(); 3630 3631 // Initialize global modules 3632 jint status = init_globals(); 3633 if (status != JNI_OK) { 3634 delete main_thread; 3635 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3636 return status; 3637 } 3638 3639 if (TRACE_INITIALIZE() != JNI_OK) { 3640 vm_exit_during_initialization("Failed to initialize tracing backend"); 3641 } 3642 3643 // Should be done after the heap is fully created 3644 main_thread->cache_global_variables(); 3645 3646 HandleMark hm; 3647 3648 { MutexLocker mu(Threads_lock); 3649 Threads::add(main_thread); 3650 } 3651 3652 // Any JVMTI raw monitors entered in onload will transition into 3653 // real raw monitor. VM is setup enough here for raw monitor enter. 3654 JvmtiExport::transition_pending_onload_raw_monitors(); 3655 3656 // Create the VMThread 3657 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3658 3659 VMThread::create(); 3660 Thread* vmthread = VMThread::vm_thread(); 3661 3662 if (!os::create_thread(vmthread, os::vm_thread)) { 3663 vm_exit_during_initialization("Cannot create VM thread. " 3664 "Out of system resources."); 3665 } 3666 3667 // Wait for the VM thread to become ready, and VMThread::run to initialize 3668 // Monitors can have spurious returns, must always check another state flag 3669 { 3670 MutexLocker ml(Notify_lock); 3671 os::start_thread(vmthread); 3672 while (vmthread->active_handles() == NULL) { 3673 Notify_lock->wait(); 3674 } 3675 } 3676 } 3677 3678 assert(Universe::is_fully_initialized(), "not initialized"); 3679 if (VerifyDuringStartup) { 3680 // Make sure we're starting with a clean slate. 3681 VM_Verify verify_op; 3682 VMThread::execute(&verify_op); 3683 } 3684 3685 Thread* THREAD = Thread::current(); 3686 3687 // At this point, the Universe is initialized, but we have not executed 3688 // any byte code. Now is a good time (the only time) to dump out the 3689 // internal state of the JVM for sharing. 3690 if (DumpSharedSpaces) { 3691 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3692 ShouldNotReachHere(); 3693 } 3694 3695 // Always call even when there are not JVMTI environments yet, since environments 3696 // may be attached late and JVMTI must track phases of VM execution 3697 JvmtiExport::enter_early_start_phase(); 3698 3699 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3700 JvmtiExport::post_early_vm_start(); 3701 3702 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3703 3704 // We need this for ClassDataSharing - the initial vm.info property is set 3705 // with the default value of CDS "sharing" which may be reset through 3706 // command line options. 3707 reset_vm_info_property(CHECK_JNI_ERR); 3708 3709 quicken_jni_functions(); 3710 3711 // No more stub generation allowed after that point. 3712 StubCodeDesc::freeze(); 3713 3714 // Set flag that basic initialization has completed. Used by exceptions and various 3715 // debug stuff, that does not work until all basic classes have been initialized. 3716 set_init_completed(); 3717 3718 LogConfiguration::post_initialize(); 3719 Metaspace::post_initialize(); 3720 3721 HOTSPOT_VM_INIT_END(); 3722 3723 // record VM initialization completion time 3724 #if INCLUDE_MANAGEMENT 3725 Management::record_vm_init_completed(); 3726 #endif // INCLUDE_MANAGEMENT 3727 3728 // Signal Dispatcher needs to be started before VMInit event is posted 3729 os::signal_init(CHECK_JNI_ERR); 3730 3731 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3732 if (!DisableAttachMechanism) { 3733 AttachListener::vm_start(); 3734 if (StartAttachListener || AttachListener::init_at_startup()) { 3735 AttachListener::init(); 3736 } 3737 } 3738 3739 // Launch -Xrun agents 3740 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3741 // back-end can launch with -Xdebug -Xrunjdwp. 3742 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3743 create_vm_init_libraries(); 3744 } 3745 3746 if (CleanChunkPoolAsync) { 3747 Chunk::start_chunk_pool_cleaner_task(); 3748 } 3749 3750 // initialize compiler(s) 3751 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3752 CompileBroker::compilation_init(CHECK_JNI_ERR); 3753 #endif 3754 3755 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3756 // It is done after compilers are initialized, because otherwise compilations of 3757 // signature polymorphic MH intrinsics can be missed 3758 // (see SystemDictionary::find_method_handle_intrinsic). 3759 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3760 3761 // This will initialize the module system. Only java.base classes can be 3762 // loaded until phase 2 completes 3763 call_initPhase2(CHECK_JNI_ERR); 3764 3765 // Always call even when there are not JVMTI environments yet, since environments 3766 // may be attached late and JVMTI must track phases of VM execution 3767 JvmtiExport::enter_start_phase(); 3768 3769 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3770 JvmtiExport::post_vm_start(); 3771 3772 // Final system initialization including security manager and system class loader 3773 call_initPhase3(CHECK_JNI_ERR); 3774 3775 // cache the system class loader 3776 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3777 3778 #if INCLUDE_JVMCI 3779 if (EnableJVMCI) { 3780 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3781 // The JVMCI Java initialization code will read this flag and 3782 // do the printing if it's set. 3783 bool init = JVMCIPrintProperties; 3784 3785 if (!init) { 3786 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3787 // compilations via JVMCI will not actually block until JVMCI is initialized. 3788 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3789 } 3790 3791 if (init) { 3792 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3793 } 3794 } 3795 #endif 3796 3797 // Always call even when there are not JVMTI environments yet, since environments 3798 // may be attached late and JVMTI must track phases of VM execution 3799 JvmtiExport::enter_live_phase(); 3800 3801 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3802 JvmtiExport::post_vm_initialized(); 3803 3804 if (TRACE_START() != JNI_OK) { 3805 vm_exit_during_initialization("Failed to start tracing backend."); 3806 } 3807 3808 #if INCLUDE_MANAGEMENT 3809 Management::initialize(THREAD); 3810 3811 if (HAS_PENDING_EXCEPTION) { 3812 // management agent fails to start possibly due to 3813 // configuration problem and is responsible for printing 3814 // stack trace if appropriate. Simply exit VM. 3815 vm_exit(1); 3816 } 3817 #endif // INCLUDE_MANAGEMENT 3818 3819 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3820 if (MemProfiling) MemProfiler::engage(); 3821 StatSampler::engage(); 3822 if (CheckJNICalls) JniPeriodicChecker::engage(); 3823 3824 BiasedLocking::init(); 3825 3826 #if INCLUDE_RTM_OPT 3827 RTMLockingCounters::init(); 3828 #endif 3829 3830 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3831 call_postVMInitHook(THREAD); 3832 // The Java side of PostVMInitHook.run must deal with all 3833 // exceptions and provide means of diagnosis. 3834 if (HAS_PENDING_EXCEPTION) { 3835 CLEAR_PENDING_EXCEPTION; 3836 } 3837 } 3838 3839 { 3840 MutexLocker ml(PeriodicTask_lock); 3841 // Make sure the WatcherThread can be started by WatcherThread::start() 3842 // or by dynamic enrollment. 3843 WatcherThread::make_startable(); 3844 // Start up the WatcherThread if there are any periodic tasks 3845 // NOTE: All PeriodicTasks should be registered by now. If they 3846 // aren't, late joiners might appear to start slowly (we might 3847 // take a while to process their first tick). 3848 if (PeriodicTask::num_tasks() > 0) { 3849 WatcherThread::start(); 3850 } 3851 } 3852 3853 create_vm_timer.end(); 3854 #ifdef ASSERT 3855 _vm_complete = true; 3856 #endif 3857 return JNI_OK; 3858 } 3859 3860 // type for the Agent_OnLoad and JVM_OnLoad entry points 3861 extern "C" { 3862 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3863 } 3864 // Find a command line agent library and return its entry point for 3865 // -agentlib: -agentpath: -Xrun 3866 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3867 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3868 const char *on_load_symbols[], 3869 size_t num_symbol_entries) { 3870 OnLoadEntry_t on_load_entry = NULL; 3871 void *library = NULL; 3872 3873 if (!agent->valid()) { 3874 char buffer[JVM_MAXPATHLEN]; 3875 char ebuf[1024] = ""; 3876 const char *name = agent->name(); 3877 const char *msg = "Could not find agent library "; 3878 3879 // First check to see if agent is statically linked into executable 3880 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3881 library = agent->os_lib(); 3882 } else if (agent->is_absolute_path()) { 3883 library = os::dll_load(name, ebuf, sizeof ebuf); 3884 if (library == NULL) { 3885 const char *sub_msg = " in absolute path, with error: "; 3886 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3887 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3888 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3889 // If we can't find the agent, exit. 3890 vm_exit_during_initialization(buf, NULL); 3891 FREE_C_HEAP_ARRAY(char, buf); 3892 } 3893 } else { 3894 // Try to load the agent from the standard dll directory 3895 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3896 name)) { 3897 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3898 } 3899 if (library == NULL) { // Try the local directory 3900 char ns[1] = {0}; 3901 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3902 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3903 } 3904 if (library == NULL) { 3905 const char *sub_msg = " on the library path, with error: "; 3906 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3907 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3908 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3909 // If we can't find the agent, exit. 3910 vm_exit_during_initialization(buf, NULL); 3911 FREE_C_HEAP_ARRAY(char, buf); 3912 } 3913 } 3914 } 3915 agent->set_os_lib(library); 3916 agent->set_valid(); 3917 } 3918 3919 // Find the OnLoad function. 3920 on_load_entry = 3921 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3922 false, 3923 on_load_symbols, 3924 num_symbol_entries)); 3925 return on_load_entry; 3926 } 3927 3928 // Find the JVM_OnLoad entry point 3929 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3930 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3931 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3932 } 3933 3934 // Find the Agent_OnLoad entry point 3935 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3936 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3937 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3938 } 3939 3940 // For backwards compatibility with -Xrun 3941 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3942 // treated like -agentpath: 3943 // Must be called before agent libraries are created 3944 void Threads::convert_vm_init_libraries_to_agents() { 3945 AgentLibrary* agent; 3946 AgentLibrary* next; 3947 3948 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3949 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3950 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3951 3952 // If there is an JVM_OnLoad function it will get called later, 3953 // otherwise see if there is an Agent_OnLoad 3954 if (on_load_entry == NULL) { 3955 on_load_entry = lookup_agent_on_load(agent); 3956 if (on_load_entry != NULL) { 3957 // switch it to the agent list -- so that Agent_OnLoad will be called, 3958 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3959 Arguments::convert_library_to_agent(agent); 3960 } else { 3961 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3962 } 3963 } 3964 } 3965 } 3966 3967 // Create agents for -agentlib: -agentpath: and converted -Xrun 3968 // Invokes Agent_OnLoad 3969 // Called very early -- before JavaThreads exist 3970 void Threads::create_vm_init_agents() { 3971 extern struct JavaVM_ main_vm; 3972 AgentLibrary* agent; 3973 3974 JvmtiExport::enter_onload_phase(); 3975 3976 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3977 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3978 3979 if (on_load_entry != NULL) { 3980 // Invoke the Agent_OnLoad function 3981 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3982 if (err != JNI_OK) { 3983 vm_exit_during_initialization("agent library failed to init", agent->name()); 3984 } 3985 } else { 3986 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3987 } 3988 } 3989 JvmtiExport::enter_primordial_phase(); 3990 } 3991 3992 extern "C" { 3993 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3994 } 3995 3996 void Threads::shutdown_vm_agents() { 3997 // Send any Agent_OnUnload notifications 3998 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3999 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4000 extern struct JavaVM_ main_vm; 4001 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4002 4003 // Find the Agent_OnUnload function. 4004 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4005 os::find_agent_function(agent, 4006 false, 4007 on_unload_symbols, 4008 num_symbol_entries)); 4009 4010 // Invoke the Agent_OnUnload function 4011 if (unload_entry != NULL) { 4012 JavaThread* thread = JavaThread::current(); 4013 ThreadToNativeFromVM ttn(thread); 4014 HandleMark hm(thread); 4015 (*unload_entry)(&main_vm); 4016 } 4017 } 4018 } 4019 4020 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4021 // Invokes JVM_OnLoad 4022 void Threads::create_vm_init_libraries() { 4023 extern struct JavaVM_ main_vm; 4024 AgentLibrary* agent; 4025 4026 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4027 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4028 4029 if (on_load_entry != NULL) { 4030 // Invoke the JVM_OnLoad function 4031 JavaThread* thread = JavaThread::current(); 4032 ThreadToNativeFromVM ttn(thread); 4033 HandleMark hm(thread); 4034 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4035 if (err != JNI_OK) { 4036 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4037 } 4038 } else { 4039 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4040 } 4041 } 4042 } 4043 4044 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4045 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4046 4047 JavaThread* java_thread = NULL; 4048 // Sequential search for now. Need to do better optimization later. 4049 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4050 oop tobj = thread->threadObj(); 4051 if (!thread->is_exiting() && 4052 tobj != NULL && 4053 java_tid == java_lang_Thread::thread_id(tobj)) { 4054 java_thread = thread; 4055 break; 4056 } 4057 } 4058 return java_thread; 4059 } 4060 4061 4062 // Last thread running calls java.lang.Shutdown.shutdown() 4063 void JavaThread::invoke_shutdown_hooks() { 4064 HandleMark hm(this); 4065 4066 // We could get here with a pending exception, if so clear it now. 4067 if (this->has_pending_exception()) { 4068 this->clear_pending_exception(); 4069 } 4070 4071 EXCEPTION_MARK; 4072 Klass* shutdown_klass = 4073 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4074 THREAD); 4075 if (shutdown_klass != NULL) { 4076 // SystemDictionary::resolve_or_null will return null if there was 4077 // an exception. If we cannot load the Shutdown class, just don't 4078 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4079 // and finalizers (if runFinalizersOnExit is set) won't be run. 4080 // Note that if a shutdown hook was registered or runFinalizersOnExit 4081 // was called, the Shutdown class would have already been loaded 4082 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4083 JavaValue result(T_VOID); 4084 JavaCalls::call_static(&result, 4085 shutdown_klass, 4086 vmSymbols::shutdown_method_name(), 4087 vmSymbols::void_method_signature(), 4088 THREAD); 4089 } 4090 CLEAR_PENDING_EXCEPTION; 4091 } 4092 4093 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4094 // the program falls off the end of main(). Another VM exit path is through 4095 // vm_exit() when the program calls System.exit() to return a value or when 4096 // there is a serious error in VM. The two shutdown paths are not exactly 4097 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4098 // and VM_Exit op at VM level. 4099 // 4100 // Shutdown sequence: 4101 // + Shutdown native memory tracking if it is on 4102 // + Wait until we are the last non-daemon thread to execute 4103 // <-- every thing is still working at this moment --> 4104 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4105 // shutdown hooks, run finalizers if finalization-on-exit 4106 // + Call before_exit(), prepare for VM exit 4107 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4108 // currently the only user of this mechanism is File.deleteOnExit()) 4109 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4110 // post thread end and vm death events to JVMTI, 4111 // stop signal thread 4112 // + Call JavaThread::exit(), it will: 4113 // > release JNI handle blocks, remove stack guard pages 4114 // > remove this thread from Threads list 4115 // <-- no more Java code from this thread after this point --> 4116 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4117 // the compiler threads at safepoint 4118 // <-- do not use anything that could get blocked by Safepoint --> 4119 // + Disable tracing at JNI/JVM barriers 4120 // + Set _vm_exited flag for threads that are still running native code 4121 // + Delete this thread 4122 // + Call exit_globals() 4123 // > deletes tty 4124 // > deletes PerfMemory resources 4125 // + Return to caller 4126 4127 bool Threads::destroy_vm() { 4128 JavaThread* thread = JavaThread::current(); 4129 4130 #ifdef ASSERT 4131 _vm_complete = false; 4132 #endif 4133 // Wait until we are the last non-daemon thread to execute 4134 { MutexLocker nu(Threads_lock); 4135 while (Threads::number_of_non_daemon_threads() > 1) 4136 // This wait should make safepoint checks, wait without a timeout, 4137 // and wait as a suspend-equivalent condition. 4138 // 4139 // Note: If the FlatProfiler is running and this thread is waiting 4140 // for another non-daemon thread to finish, then the FlatProfiler 4141 // is waiting for the external suspend request on this thread to 4142 // complete. wait_for_ext_suspend_completion() will eventually 4143 // timeout, but that takes time. Making this wait a suspend- 4144 // equivalent condition solves that timeout problem. 4145 // 4146 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4147 Mutex::_as_suspend_equivalent_flag); 4148 } 4149 4150 // Hang forever on exit if we are reporting an error. 4151 if (ShowMessageBoxOnError && is_error_reported()) { 4152 os::infinite_sleep(); 4153 } 4154 os::wait_for_keypress_at_exit(); 4155 4156 // run Java level shutdown hooks 4157 thread->invoke_shutdown_hooks(); 4158 4159 before_exit(thread); 4160 4161 thread->exit(true); 4162 4163 // Stop VM thread. 4164 { 4165 // 4945125 The vm thread comes to a safepoint during exit. 4166 // GC vm_operations can get caught at the safepoint, and the 4167 // heap is unparseable if they are caught. Grab the Heap_lock 4168 // to prevent this. The GC vm_operations will not be able to 4169 // queue until after the vm thread is dead. After this point, 4170 // we'll never emerge out of the safepoint before the VM exits. 4171 4172 MutexLocker ml(Heap_lock); 4173 4174 VMThread::wait_for_vm_thread_exit(); 4175 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4176 VMThread::destroy(); 4177 } 4178 4179 // clean up ideal graph printers 4180 #if defined(COMPILER2) && !defined(PRODUCT) 4181 IdealGraphPrinter::clean_up(); 4182 #endif 4183 4184 // Now, all Java threads are gone except daemon threads. Daemon threads 4185 // running Java code or in VM are stopped by the Safepoint. However, 4186 // daemon threads executing native code are still running. But they 4187 // will be stopped at native=>Java/VM barriers. Note that we can't 4188 // simply kill or suspend them, as it is inherently deadlock-prone. 4189 4190 VM_Exit::set_vm_exited(); 4191 4192 notify_vm_shutdown(); 4193 4194 delete thread; 4195 4196 #if INCLUDE_JVMCI 4197 if (JVMCICounterSize > 0) { 4198 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4199 } 4200 #endif 4201 4202 // exit_globals() will delete tty 4203 exit_globals(); 4204 4205 LogConfiguration::finalize(); 4206 4207 return true; 4208 } 4209 4210 4211 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4212 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4213 return is_supported_jni_version(version); 4214 } 4215 4216 4217 jboolean Threads::is_supported_jni_version(jint version) { 4218 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4219 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4220 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4221 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4222 if (version == JNI_VERSION_9) return JNI_TRUE; 4223 return JNI_FALSE; 4224 } 4225 4226 4227 void Threads::add(JavaThread* p, bool force_daemon) { 4228 // The threads lock must be owned at this point 4229 assert_locked_or_safepoint(Threads_lock); 4230 4231 // See the comment for this method in thread.hpp for its purpose and 4232 // why it is called here. 4233 p->initialize_queues(); 4234 p->set_next(_thread_list); 4235 _thread_list = p; 4236 _number_of_threads++; 4237 oop threadObj = p->threadObj(); 4238 bool daemon = true; 4239 // Bootstrapping problem: threadObj can be null for initial 4240 // JavaThread (or for threads attached via JNI) 4241 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4242 _number_of_non_daemon_threads++; 4243 daemon = false; 4244 } 4245 4246 ThreadService::add_thread(p, daemon); 4247 4248 // Possible GC point. 4249 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4250 } 4251 4252 void Threads::remove(JavaThread* p) { 4253 4254 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4255 ObjectSynchronizer::omFlush(p); 4256 4257 // Extra scope needed for Thread_lock, so we can check 4258 // that we do not remove thread without safepoint code notice 4259 { MutexLocker ml(Threads_lock); 4260 4261 assert(includes(p), "p must be present"); 4262 4263 JavaThread* current = _thread_list; 4264 JavaThread* prev = NULL; 4265 4266 while (current != p) { 4267 prev = current; 4268 current = current->next(); 4269 } 4270 4271 if (prev) { 4272 prev->set_next(current->next()); 4273 } else { 4274 _thread_list = p->next(); 4275 } 4276 _number_of_threads--; 4277 oop threadObj = p->threadObj(); 4278 bool daemon = true; 4279 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4280 _number_of_non_daemon_threads--; 4281 daemon = false; 4282 4283 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4284 // on destroy_vm will wake up. 4285 if (number_of_non_daemon_threads() == 1) { 4286 Threads_lock->notify_all(); 4287 } 4288 } 4289 ThreadService::remove_thread(p, daemon); 4290 4291 // Make sure that safepoint code disregard this thread. This is needed since 4292 // the thread might mess around with locks after this point. This can cause it 4293 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4294 // of this thread since it is removed from the queue. 4295 p->set_terminated_value(); 4296 } // unlock Threads_lock 4297 4298 // Since Events::log uses a lock, we grab it outside the Threads_lock 4299 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4300 } 4301 4302 // Threads_lock must be held when this is called (or must be called during a safepoint) 4303 bool Threads::includes(JavaThread* p) { 4304 assert(Threads_lock->is_locked(), "sanity check"); 4305 ALL_JAVA_THREADS(q) { 4306 if (q == p) { 4307 return true; 4308 } 4309 } 4310 return false; 4311 } 4312 4313 // Operations on the Threads list for GC. These are not explicitly locked, 4314 // but the garbage collector must provide a safe context for them to run. 4315 // In particular, these things should never be called when the Threads_lock 4316 // is held by some other thread. (Note: the Safepoint abstraction also 4317 // uses the Threads_lock to guarantee this property. It also makes sure that 4318 // all threads gets blocked when exiting or starting). 4319 4320 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4321 ALL_JAVA_THREADS(p) { 4322 p->oops_do(f, cf); 4323 } 4324 VMThread::vm_thread()->oops_do(f, cf); 4325 } 4326 4327 void Threads::change_thread_claim_parity() { 4328 // Set the new claim parity. 4329 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4330 "Not in range."); 4331 _thread_claim_parity++; 4332 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4333 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4334 "Not in range."); 4335 } 4336 4337 #ifdef ASSERT 4338 void Threads::assert_all_threads_claimed() { 4339 ALL_JAVA_THREADS(p) { 4340 const int thread_parity = p->oops_do_parity(); 4341 assert((thread_parity == _thread_claim_parity), 4342 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4343 } 4344 } 4345 #endif // ASSERT 4346 4347 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4348 int cp = Threads::thread_claim_parity(); 4349 ALL_JAVA_THREADS(p) { 4350 if (p->claim_oops_do(is_par, cp)) { 4351 p->oops_do(f, cf); 4352 } 4353 } 4354 VMThread* vmt = VMThread::vm_thread(); 4355 if (vmt->claim_oops_do(is_par, cp)) { 4356 vmt->oops_do(f, cf); 4357 } 4358 } 4359 4360 #if INCLUDE_ALL_GCS 4361 // Used by ParallelScavenge 4362 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4363 ALL_JAVA_THREADS(p) { 4364 q->enqueue(new ThreadRootsTask(p)); 4365 } 4366 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4367 } 4368 4369 // Used by Parallel Old 4370 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4371 ALL_JAVA_THREADS(p) { 4372 q->enqueue(new ThreadRootsMarkingTask(p)); 4373 } 4374 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4375 } 4376 #endif // INCLUDE_ALL_GCS 4377 4378 void Threads::nmethods_do(CodeBlobClosure* cf) { 4379 ALL_JAVA_THREADS(p) { 4380 // This is used by the code cache sweeper to mark nmethods that are active 4381 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4382 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4383 if(!p->is_Code_cache_sweeper_thread()) { 4384 p->nmethods_do(cf); 4385 } 4386 } 4387 } 4388 4389 void Threads::metadata_do(void f(Metadata*)) { 4390 ALL_JAVA_THREADS(p) { 4391 p->metadata_do(f); 4392 } 4393 } 4394 4395 class ThreadHandlesClosure : public ThreadClosure { 4396 void (*_f)(Metadata*); 4397 public: 4398 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4399 virtual void do_thread(Thread* thread) { 4400 thread->metadata_handles_do(_f); 4401 } 4402 }; 4403 4404 void Threads::metadata_handles_do(void f(Metadata*)) { 4405 // Only walk the Handles in Thread. 4406 ThreadHandlesClosure handles_closure(f); 4407 threads_do(&handles_closure); 4408 } 4409 4410 void Threads::deoptimized_wrt_marked_nmethods() { 4411 ALL_JAVA_THREADS(p) { 4412 p->deoptimized_wrt_marked_nmethods(); 4413 } 4414 } 4415 4416 4417 // Get count Java threads that are waiting to enter the specified monitor. 4418 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4419 address monitor, 4420 bool doLock) { 4421 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4422 "must grab Threads_lock or be at safepoint"); 4423 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4424 4425 int i = 0; 4426 { 4427 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4428 ALL_JAVA_THREADS(p) { 4429 if (!p->can_call_java()) continue; 4430 4431 address pending = (address)p->current_pending_monitor(); 4432 if (pending == monitor) { // found a match 4433 if (i < count) result->append(p); // save the first count matches 4434 i++; 4435 } 4436 } 4437 } 4438 return result; 4439 } 4440 4441 4442 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4443 bool doLock) { 4444 assert(doLock || 4445 Threads_lock->owned_by_self() || 4446 SafepointSynchronize::is_at_safepoint(), 4447 "must grab Threads_lock or be at safepoint"); 4448 4449 // NULL owner means not locked so we can skip the search 4450 if (owner == NULL) return NULL; 4451 4452 { 4453 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4454 ALL_JAVA_THREADS(p) { 4455 // first, see if owner is the address of a Java thread 4456 if (owner == (address)p) return p; 4457 } 4458 } 4459 // Cannot assert on lack of success here since this function may be 4460 // used by code that is trying to report useful problem information 4461 // like deadlock detection. 4462 if (UseHeavyMonitors) return NULL; 4463 4464 // If we didn't find a matching Java thread and we didn't force use of 4465 // heavyweight monitors, then the owner is the stack address of the 4466 // Lock Word in the owning Java thread's stack. 4467 // 4468 JavaThread* the_owner = NULL; 4469 { 4470 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4471 ALL_JAVA_THREADS(q) { 4472 if (q->is_lock_owned(owner)) { 4473 the_owner = q; 4474 break; 4475 } 4476 } 4477 } 4478 // cannot assert on lack of success here; see above comment 4479 return the_owner; 4480 } 4481 4482 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4483 void Threads::print_on(outputStream* st, bool print_stacks, 4484 bool internal_format, bool print_concurrent_locks) { 4485 char buf[32]; 4486 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4487 4488 st->print_cr("Full thread dump %s (%s %s):", 4489 Abstract_VM_Version::vm_name(), 4490 Abstract_VM_Version::vm_release(), 4491 Abstract_VM_Version::vm_info_string()); 4492 st->cr(); 4493 4494 #if INCLUDE_SERVICES 4495 // Dump concurrent locks 4496 ConcurrentLocksDump concurrent_locks; 4497 if (print_concurrent_locks) { 4498 concurrent_locks.dump_at_safepoint(); 4499 } 4500 #endif // INCLUDE_SERVICES 4501 4502 ALL_JAVA_THREADS(p) { 4503 ResourceMark rm; 4504 p->print_on(st); 4505 if (print_stacks) { 4506 if (internal_format) { 4507 p->trace_stack(); 4508 } else { 4509 p->print_stack_on(st); 4510 } 4511 } 4512 st->cr(); 4513 #if INCLUDE_SERVICES 4514 if (print_concurrent_locks) { 4515 concurrent_locks.print_locks_on(p, st); 4516 } 4517 #endif // INCLUDE_SERVICES 4518 } 4519 4520 VMThread::vm_thread()->print_on(st); 4521 st->cr(); 4522 Universe::heap()->print_gc_threads_on(st); 4523 WatcherThread* wt = WatcherThread::watcher_thread(); 4524 if (wt != NULL) { 4525 wt->print_on(st); 4526 st->cr(); 4527 } 4528 st->flush(); 4529 } 4530 4531 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4532 int buflen, bool* found_current) { 4533 if (this_thread != NULL) { 4534 bool is_current = (current == this_thread); 4535 *found_current = *found_current || is_current; 4536 st->print("%s", is_current ? "=>" : " "); 4537 4538 st->print(PTR_FORMAT, p2i(this_thread)); 4539 st->print(" "); 4540 this_thread->print_on_error(st, buf, buflen); 4541 st->cr(); 4542 } 4543 } 4544 4545 class PrintOnErrorClosure : public ThreadClosure { 4546 outputStream* _st; 4547 Thread* _current; 4548 char* _buf; 4549 int _buflen; 4550 bool* _found_current; 4551 public: 4552 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4553 int buflen, bool* found_current) : 4554 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4555 4556 virtual void do_thread(Thread* thread) { 4557 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4558 } 4559 }; 4560 4561 // Threads::print_on_error() is called by fatal error handler. It's possible 4562 // that VM is not at safepoint and/or current thread is inside signal handler. 4563 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4564 // memory (even in resource area), it might deadlock the error handler. 4565 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4566 int buflen) { 4567 bool found_current = false; 4568 st->print_cr("Java Threads: ( => current thread )"); 4569 ALL_JAVA_THREADS(thread) { 4570 print_on_error(thread, st, current, buf, buflen, &found_current); 4571 } 4572 st->cr(); 4573 4574 st->print_cr("Other Threads:"); 4575 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4576 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4577 4578 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4579 Universe::heap()->gc_threads_do(&print_closure); 4580 4581 if (!found_current) { 4582 st->cr(); 4583 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4584 current->print_on_error(st, buf, buflen); 4585 st->cr(); 4586 } 4587 st->cr(); 4588 st->print_cr("Threads with active compile tasks:"); 4589 print_threads_compiling(st, buf, buflen); 4590 } 4591 4592 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4593 ALL_JAVA_THREADS(thread) { 4594 if (thread->is_Compiler_thread()) { 4595 CompilerThread* ct = (CompilerThread*) thread; 4596 if (ct->task() != NULL) { 4597 thread->print_name_on_error(st, buf, buflen); 4598 ct->task()->print(st, NULL, true, true); 4599 } 4600 } 4601 } 4602 } 4603 4604 4605 // Internal SpinLock and Mutex 4606 // Based on ParkEvent 4607 4608 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4609 // 4610 // We employ SpinLocks _only for low-contention, fixed-length 4611 // short-duration critical sections where we're concerned 4612 // about native mutex_t or HotSpot Mutex:: latency. 4613 // The mux construct provides a spin-then-block mutual exclusion 4614 // mechanism. 4615 // 4616 // Testing has shown that contention on the ListLock guarding gFreeList 4617 // is common. If we implement ListLock as a simple SpinLock it's common 4618 // for the JVM to devolve to yielding with little progress. This is true 4619 // despite the fact that the critical sections protected by ListLock are 4620 // extremely short. 4621 // 4622 // TODO-FIXME: ListLock should be of type SpinLock. 4623 // We should make this a 1st-class type, integrated into the lock 4624 // hierarchy as leaf-locks. Critically, the SpinLock structure 4625 // should have sufficient padding to avoid false-sharing and excessive 4626 // cache-coherency traffic. 4627 4628 4629 typedef volatile int SpinLockT; 4630 4631 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4632 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4633 return; // normal fast-path return 4634 } 4635 4636 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4637 TEVENT(SpinAcquire - ctx); 4638 int ctr = 0; 4639 int Yields = 0; 4640 for (;;) { 4641 while (*adr != 0) { 4642 ++ctr; 4643 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4644 if (Yields > 5) { 4645 os::naked_short_sleep(1); 4646 } else { 4647 os::naked_yield(); 4648 ++Yields; 4649 } 4650 } else { 4651 SpinPause(); 4652 } 4653 } 4654 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4655 } 4656 } 4657 4658 void Thread::SpinRelease(volatile int * adr) { 4659 assert(*adr != 0, "invariant"); 4660 OrderAccess::fence(); // guarantee at least release consistency. 4661 // Roach-motel semantics. 4662 // It's safe if subsequent LDs and STs float "up" into the critical section, 4663 // but prior LDs and STs within the critical section can't be allowed 4664 // to reorder or float past the ST that releases the lock. 4665 // Loads and stores in the critical section - which appear in program 4666 // order before the store that releases the lock - must also appear 4667 // before the store that releases the lock in memory visibility order. 4668 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4669 // the ST of 0 into the lock-word which releases the lock, so fence 4670 // more than covers this on all platforms. 4671 *adr = 0; 4672 } 4673 4674 // muxAcquire and muxRelease: 4675 // 4676 // * muxAcquire and muxRelease support a single-word lock-word construct. 4677 // The LSB of the word is set IFF the lock is held. 4678 // The remainder of the word points to the head of a singly-linked list 4679 // of threads blocked on the lock. 4680 // 4681 // * The current implementation of muxAcquire-muxRelease uses its own 4682 // dedicated Thread._MuxEvent instance. If we're interested in 4683 // minimizing the peak number of extant ParkEvent instances then 4684 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4685 // as certain invariants were satisfied. Specifically, care would need 4686 // to be taken with regards to consuming unpark() "permits". 4687 // A safe rule of thumb is that a thread would never call muxAcquire() 4688 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4689 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4690 // consume an unpark() permit intended for monitorenter, for instance. 4691 // One way around this would be to widen the restricted-range semaphore 4692 // implemented in park(). Another alternative would be to provide 4693 // multiple instances of the PlatformEvent() for each thread. One 4694 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4695 // 4696 // * Usage: 4697 // -- Only as leaf locks 4698 // -- for short-term locking only as muxAcquire does not perform 4699 // thread state transitions. 4700 // 4701 // Alternatives: 4702 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4703 // but with parking or spin-then-park instead of pure spinning. 4704 // * Use Taura-Oyama-Yonenzawa locks. 4705 // * It's possible to construct a 1-0 lock if we encode the lockword as 4706 // (List,LockByte). Acquire will CAS the full lockword while Release 4707 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4708 // acquiring threads use timers (ParkTimed) to detect and recover from 4709 // the stranding window. Thread/Node structures must be aligned on 256-byte 4710 // boundaries by using placement-new. 4711 // * Augment MCS with advisory back-link fields maintained with CAS(). 4712 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4713 // The validity of the backlinks must be ratified before we trust the value. 4714 // If the backlinks are invalid the exiting thread must back-track through the 4715 // the forward links, which are always trustworthy. 4716 // * Add a successor indication. The LockWord is currently encoded as 4717 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4718 // to provide the usual futile-wakeup optimization. 4719 // See RTStt for details. 4720 // * Consider schedctl.sc_nopreempt to cover the critical section. 4721 // 4722 4723 4724 typedef volatile intptr_t MutexT; // Mux Lock-word 4725 enum MuxBits { LOCKBIT = 1 }; 4726 4727 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4728 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4729 if (w == 0) return; 4730 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4731 return; 4732 } 4733 4734 TEVENT(muxAcquire - Contention); 4735 ParkEvent * const Self = Thread::current()->_MuxEvent; 4736 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4737 for (;;) { 4738 int its = (os::is_MP() ? 100 : 0) + 1; 4739 4740 // Optional spin phase: spin-then-park strategy 4741 while (--its >= 0) { 4742 w = *Lock; 4743 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4744 return; 4745 } 4746 } 4747 4748 Self->reset(); 4749 Self->OnList = intptr_t(Lock); 4750 // The following fence() isn't _strictly necessary as the subsequent 4751 // CAS() both serializes execution and ratifies the fetched *Lock value. 4752 OrderAccess::fence(); 4753 for (;;) { 4754 w = *Lock; 4755 if ((w & LOCKBIT) == 0) { 4756 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4757 Self->OnList = 0; // hygiene - allows stronger asserts 4758 return; 4759 } 4760 continue; // Interference -- *Lock changed -- Just retry 4761 } 4762 assert(w & LOCKBIT, "invariant"); 4763 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4764 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4765 } 4766 4767 while (Self->OnList != 0) { 4768 Self->park(); 4769 } 4770 } 4771 } 4772 4773 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4774 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4775 if (w == 0) return; 4776 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4777 return; 4778 } 4779 4780 TEVENT(muxAcquire - Contention); 4781 ParkEvent * ReleaseAfter = NULL; 4782 if (ev == NULL) { 4783 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4784 } 4785 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4786 for (;;) { 4787 guarantee(ev->OnList == 0, "invariant"); 4788 int its = (os::is_MP() ? 100 : 0) + 1; 4789 4790 // Optional spin phase: spin-then-park strategy 4791 while (--its >= 0) { 4792 w = *Lock; 4793 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4794 if (ReleaseAfter != NULL) { 4795 ParkEvent::Release(ReleaseAfter); 4796 } 4797 return; 4798 } 4799 } 4800 4801 ev->reset(); 4802 ev->OnList = intptr_t(Lock); 4803 // The following fence() isn't _strictly necessary as the subsequent 4804 // CAS() both serializes execution and ratifies the fetched *Lock value. 4805 OrderAccess::fence(); 4806 for (;;) { 4807 w = *Lock; 4808 if ((w & LOCKBIT) == 0) { 4809 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4810 ev->OnList = 0; 4811 // We call ::Release while holding the outer lock, thus 4812 // artificially lengthening the critical section. 4813 // Consider deferring the ::Release() until the subsequent unlock(), 4814 // after we've dropped the outer lock. 4815 if (ReleaseAfter != NULL) { 4816 ParkEvent::Release(ReleaseAfter); 4817 } 4818 return; 4819 } 4820 continue; // Interference -- *Lock changed -- Just retry 4821 } 4822 assert(w & LOCKBIT, "invariant"); 4823 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4824 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4825 } 4826 4827 while (ev->OnList != 0) { 4828 ev->park(); 4829 } 4830 } 4831 } 4832 4833 // Release() must extract a successor from the list and then wake that thread. 4834 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4835 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4836 // Release() would : 4837 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4838 // (B) Extract a successor from the private list "in-hand" 4839 // (C) attempt to CAS() the residual back into *Lock over null. 4840 // If there were any newly arrived threads and the CAS() would fail. 4841 // In that case Release() would detach the RATs, re-merge the list in-hand 4842 // with the RATs and repeat as needed. Alternately, Release() might 4843 // detach and extract a successor, but then pass the residual list to the wakee. 4844 // The wakee would be responsible for reattaching and remerging before it 4845 // competed for the lock. 4846 // 4847 // Both "pop" and DMR are immune from ABA corruption -- there can be 4848 // multiple concurrent pushers, but only one popper or detacher. 4849 // This implementation pops from the head of the list. This is unfair, 4850 // but tends to provide excellent throughput as hot threads remain hot. 4851 // (We wake recently run threads first). 4852 // 4853 // All paths through muxRelease() will execute a CAS. 4854 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4855 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4856 // executed within the critical section are complete and globally visible before the 4857 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4858 void Thread::muxRelease(volatile intptr_t * Lock) { 4859 for (;;) { 4860 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4861 assert(w & LOCKBIT, "invariant"); 4862 if (w == LOCKBIT) return; 4863 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4864 assert(List != NULL, "invariant"); 4865 assert(List->OnList == intptr_t(Lock), "invariant"); 4866 ParkEvent * const nxt = List->ListNext; 4867 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4868 4869 // The following CAS() releases the lock and pops the head element. 4870 // The CAS() also ratifies the previously fetched lock-word value. 4871 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4872 continue; 4873 } 4874 List->OnList = 0; 4875 OrderAccess::fence(); 4876 List->unpark(); 4877 return; 4878 } 4879 } 4880 4881 4882 void Threads::verify() { 4883 ALL_JAVA_THREADS(p) { 4884 p->verify(); 4885 } 4886 VMThread* thread = VMThread::vm_thread(); 4887 if (thread != NULL) thread->verify(); 4888 }