1 /* 2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoader.hpp" 27 #include "classfile/javaClasses.hpp" 28 #include "classfile/moduleEntry.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/scopeDesc.hpp" 33 #include "compiler/compileBroker.hpp" 34 #include "compiler/compileTask.hpp" 35 #include "gc/shared/gcId.hpp" 36 #include "gc/shared/gcLocker.inline.hpp" 37 #include "gc/shared/workgroup.hpp" 38 #include "interpreter/interpreter.hpp" 39 #include "interpreter/linkResolver.hpp" 40 #include "interpreter/oopMapCache.hpp" 41 #include "jvmtifiles/jvmtiEnv.hpp" 42 #include "logging/log.hpp" 43 #include "logging/logConfiguration.hpp" 44 #include "memory/metaspaceShared.hpp" 45 #include "memory/oopFactory.hpp" 46 #include "memory/resourceArea.hpp" 47 #include "memory/universe.inline.hpp" 48 #include "oops/instanceKlass.hpp" 49 #include "oops/objArrayOop.hpp" 50 #include "oops/oop.inline.hpp" 51 #include "oops/symbol.hpp" 52 #include "oops/verifyOopClosure.hpp" 53 #include "prims/jvm_misc.hpp" 54 #include "prims/jvmtiExport.hpp" 55 #include "prims/jvmtiThreadState.hpp" 56 #include "prims/privilegedStack.hpp" 57 #include "runtime/arguments.hpp" 58 #include "runtime/atomic.hpp" 59 #include "runtime/biasedLocking.hpp" 60 #include "runtime/commandLineFlagConstraintList.hpp" 61 #include "runtime/commandLineFlagWriteableList.hpp" 62 #include "runtime/commandLineFlagRangeList.hpp" 63 #include "runtime/deoptimization.hpp" 64 #include "runtime/fprofiler.hpp" 65 #include "runtime/frame.inline.hpp" 66 #include "runtime/globals.hpp" 67 #include "runtime/init.hpp" 68 #include "runtime/interfaceSupport.hpp" 69 #include "runtime/java.hpp" 70 #include "runtime/javaCalls.hpp" 71 #include "runtime/jniPeriodicChecker.hpp" 72 #include "runtime/timerTrace.hpp" 73 #include "runtime/memprofiler.hpp" 74 #include "runtime/mutexLocker.hpp" 75 #include "runtime/objectMonitor.hpp" 76 #include "runtime/orderAccess.inline.hpp" 77 #include "runtime/osThread.hpp" 78 #include "runtime/safepoint.hpp" 79 #include "runtime/sharedRuntime.hpp" 80 #include "runtime/statSampler.hpp" 81 #include "runtime/stubRoutines.hpp" 82 #include "runtime/sweeper.hpp" 83 #include "runtime/task.hpp" 84 #include "runtime/thread.inline.hpp" 85 #include "runtime/threadCritical.hpp" 86 #include "runtime/vframe.hpp" 87 #include "runtime/vframeArray.hpp" 88 #include "runtime/vframe_hp.hpp" 89 #include "runtime/vmThread.hpp" 90 #include "runtime/vm_operations.hpp" 91 #include "runtime/vm_version.hpp" 92 #include "services/attachListener.hpp" 93 #include "services/management.hpp" 94 #include "services/memTracker.hpp" 95 #include "services/threadService.hpp" 96 #include "trace/traceMacros.hpp" 97 #include "trace/tracing.hpp" 98 #include "utilities/defaultStream.hpp" 99 #include "utilities/dtrace.hpp" 100 #include "utilities/events.hpp" 101 #include "utilities/macros.hpp" 102 #include "utilities/preserveException.hpp" 103 #if INCLUDE_ALL_GCS 104 #include "gc/cms/concurrentMarkSweepThread.hpp" 105 #include "gc/g1/concurrentMarkThread.inline.hpp" 106 #include "gc/parallel/pcTasks.hpp" 107 #endif // INCLUDE_ALL_GCS 108 #if INCLUDE_JVMCI 109 #include "jvmci/jvmciCompiler.hpp" 110 #include "jvmci/jvmciRuntime.hpp" 111 #endif 112 #ifdef COMPILER1 113 #include "c1/c1_Compiler.hpp" 114 #endif 115 #ifdef COMPILER2 116 #include "opto/c2compiler.hpp" 117 #include "opto/idealGraphPrinter.hpp" 118 #endif 119 #if INCLUDE_RTM_OPT 120 #include "runtime/rtmLocking.hpp" 121 #endif 122 123 // Initialization after module runtime initialization 124 void universe_post_module_init(); // must happen after call_initPhase2 125 126 #ifdef DTRACE_ENABLED 127 128 // Only bother with this argument setup if dtrace is available 129 130 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 131 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 132 133 #define DTRACE_THREAD_PROBE(probe, javathread) \ 134 { \ 135 ResourceMark rm(this); \ 136 int len = 0; \ 137 const char* name = (javathread)->get_thread_name(); \ 138 len = strlen(name); \ 139 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 140 (char *) name, len, \ 141 java_lang_Thread::thread_id((javathread)->threadObj()), \ 142 (uintptr_t) (javathread)->osthread()->thread_id(), \ 143 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 144 } 145 146 #else // ndef DTRACE_ENABLED 147 148 #define DTRACE_THREAD_PROBE(probe, javathread) 149 150 #endif // ndef DTRACE_ENABLED 151 152 #ifndef USE_LIBRARY_BASED_TLS_ONLY 153 // Current thread is maintained as a thread-local variable 154 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 155 #endif 156 // Class hierarchy 157 // - Thread 158 // - VMThread 159 // - WatcherThread 160 // - ConcurrentMarkSweepThread 161 // - JavaThread 162 // - CompilerThread 163 164 // ======= Thread ======== 165 // Support for forcing alignment of thread objects for biased locking 166 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 167 if (UseBiasedLocking) { 168 const int alignment = markOopDesc::biased_lock_alignment; 169 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 170 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 171 : AllocateHeap(aligned_size, flags, CURRENT_PC, 172 AllocFailStrategy::RETURN_NULL); 173 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 174 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 175 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 176 "JavaThread alignment code overflowed allocated storage"); 177 if (aligned_addr != real_malloc_addr) { 178 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 179 p2i(real_malloc_addr), 180 p2i(aligned_addr)); 181 } 182 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 183 return aligned_addr; 184 } else { 185 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 186 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 187 } 188 } 189 190 void Thread::operator delete(void* p) { 191 if (UseBiasedLocking) { 192 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 193 FreeHeap(real_malloc_addr); 194 } else { 195 FreeHeap(p); 196 } 197 } 198 199 200 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 201 // JavaThread 202 203 204 Thread::Thread() { 205 // stack and get_thread 206 set_stack_base(NULL); 207 set_stack_size(0); 208 set_self_raw_id(0); 209 set_lgrp_id(-1); 210 DEBUG_ONLY(clear_suspendible_thread();) 211 212 // allocated data structures 213 set_osthread(NULL); 214 set_resource_area(new (mtThread)ResourceArea()); 215 DEBUG_ONLY(_current_resource_mark = NULL;) 216 set_handle_area(new (mtThread) HandleArea(NULL)); 217 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 218 set_active_handles(NULL); 219 set_free_handle_block(NULL); 220 set_last_handle_mark(NULL); 221 222 // This initial value ==> never claimed. 223 _oops_do_parity = 0; 224 225 // the handle mark links itself to last_handle_mark 226 new HandleMark(this); 227 228 // plain initialization 229 debug_only(_owned_locks = NULL;) 230 debug_only(_allow_allocation_count = 0;) 231 NOT_PRODUCT(_allow_safepoint_count = 0;) 232 NOT_PRODUCT(_skip_gcalot = false;) 233 _jvmti_env_iteration_count = 0; 234 set_allocated_bytes(0); 235 _vm_operation_started_count = 0; 236 _vm_operation_completed_count = 0; 237 _current_pending_monitor = NULL; 238 _current_pending_monitor_is_from_java = true; 239 _current_waiting_monitor = NULL; 240 _num_nested_signal = 0; 241 omFreeList = NULL; 242 omFreeCount = 0; 243 omFreeProvision = 32; 244 omInUseList = NULL; 245 omInUseCount = 0; 246 247 #ifdef ASSERT 248 _visited_for_critical_count = false; 249 #endif 250 251 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 252 Monitor::_safepoint_check_sometimes); 253 _suspend_flags = 0; 254 255 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 256 _hashStateX = os::random(); 257 _hashStateY = 842502087; 258 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 259 _hashStateW = 273326509; 260 261 _OnTrap = 0; 262 _schedctl = NULL; 263 _Stalled = 0; 264 _TypeTag = 0x2BAD; 265 266 // Many of the following fields are effectively final - immutable 267 // Note that nascent threads can't use the Native Monitor-Mutex 268 // construct until the _MutexEvent is initialized ... 269 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 270 // we might instead use a stack of ParkEvents that we could provision on-demand. 271 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 272 // and ::Release() 273 _ParkEvent = ParkEvent::Allocate(this); 274 _SleepEvent = ParkEvent::Allocate(this); 275 _MutexEvent = ParkEvent::Allocate(this); 276 _MuxEvent = ParkEvent::Allocate(this); 277 278 #ifdef CHECK_UNHANDLED_OOPS 279 if (CheckUnhandledOops) { 280 _unhandled_oops = new UnhandledOops(this); 281 } 282 #endif // CHECK_UNHANDLED_OOPS 283 #ifdef ASSERT 284 if (UseBiasedLocking) { 285 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 286 assert(this == _real_malloc_address || 287 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 288 "bug in forced alignment of thread objects"); 289 } 290 #endif // ASSERT 291 } 292 293 void Thread::initialize_thread_current() { 294 #ifndef USE_LIBRARY_BASED_TLS_ONLY 295 assert(_thr_current == NULL, "Thread::current already initialized"); 296 _thr_current = this; 297 #endif 298 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 299 ThreadLocalStorage::set_thread(this); 300 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 301 } 302 303 void Thread::clear_thread_current() { 304 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 305 #ifndef USE_LIBRARY_BASED_TLS_ONLY 306 _thr_current = NULL; 307 #endif 308 ThreadLocalStorage::set_thread(NULL); 309 } 310 311 void Thread::record_stack_base_and_size() { 312 set_stack_base(os::current_stack_base()); 313 set_stack_size(os::current_stack_size()); 314 // CR 7190089: on Solaris, primordial thread's stack is adjusted 315 // in initialize_thread(). Without the adjustment, stack size is 316 // incorrect if stack is set to unlimited (ulimit -s unlimited). 317 // So far, only Solaris has real implementation of initialize_thread(). 318 // 319 // set up any platform-specific state. 320 os::initialize_thread(this); 321 322 // Set stack limits after thread is initialized. 323 if (is_Java_thread()) { 324 ((JavaThread*) this)->set_stack_overflow_limit(); 325 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 326 } 327 #if INCLUDE_NMT 328 // record thread's native stack, stack grows downward 329 MemTracker::record_thread_stack(stack_end(), stack_size()); 330 #endif // INCLUDE_NMT 331 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 332 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 333 os::current_thread_id(), p2i(stack_base() - stack_size()), 334 p2i(stack_base()), stack_size()/1024); 335 } 336 337 338 Thread::~Thread() { 339 EVENT_THREAD_DESTRUCT(this); 340 341 // stack_base can be NULL if the thread is never started or exited before 342 // record_stack_base_and_size called. Although, we would like to ensure 343 // that all started threads do call record_stack_base_and_size(), there is 344 // not proper way to enforce that. 345 #if INCLUDE_NMT 346 if (_stack_base != NULL) { 347 MemTracker::release_thread_stack(stack_end(), stack_size()); 348 #ifdef ASSERT 349 set_stack_base(NULL); 350 #endif 351 } 352 #endif // INCLUDE_NMT 353 354 // deallocate data structures 355 delete resource_area(); 356 // since the handle marks are using the handle area, we have to deallocated the root 357 // handle mark before deallocating the thread's handle area, 358 assert(last_handle_mark() != NULL, "check we have an element"); 359 delete last_handle_mark(); 360 assert(last_handle_mark() == NULL, "check we have reached the end"); 361 362 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 363 // We NULL out the fields for good hygiene. 364 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 365 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 366 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 367 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 368 369 delete handle_area(); 370 delete metadata_handles(); 371 372 // SR_handler uses this as a termination indicator - 373 // needs to happen before os::free_thread() 374 delete _SR_lock; 375 _SR_lock = NULL; 376 377 // osthread() can be NULL, if creation of thread failed. 378 if (osthread() != NULL) os::free_thread(osthread()); 379 380 // clear Thread::current if thread is deleting itself. 381 // Needed to ensure JNI correctly detects non-attached threads. 382 if (this == Thread::current()) { 383 clear_thread_current(); 384 } 385 386 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 387 } 388 389 // NOTE: dummy function for assertion purpose. 390 void Thread::run() { 391 ShouldNotReachHere(); 392 } 393 394 #ifdef ASSERT 395 // Private method to check for dangling thread pointer 396 void check_for_dangling_thread_pointer(Thread *thread) { 397 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 398 "possibility of dangling Thread pointer"); 399 } 400 #endif 401 402 ThreadPriority Thread::get_priority(const Thread* const thread) { 403 ThreadPriority priority; 404 // Can return an error! 405 (void)os::get_priority(thread, priority); 406 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 407 return priority; 408 } 409 410 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 411 debug_only(check_for_dangling_thread_pointer(thread);) 412 // Can return an error! 413 (void)os::set_priority(thread, priority); 414 } 415 416 417 void Thread::start(Thread* thread) { 418 // Start is different from resume in that its safety is guaranteed by context or 419 // being called from a Java method synchronized on the Thread object. 420 if (!DisableStartThread) { 421 if (thread->is_Java_thread()) { 422 // Initialize the thread state to RUNNABLE before starting this thread. 423 // Can not set it after the thread started because we do not know the 424 // exact thread state at that time. It could be in MONITOR_WAIT or 425 // in SLEEPING or some other state. 426 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 427 java_lang_Thread::RUNNABLE); 428 } 429 os::start_thread(thread); 430 } 431 } 432 433 // Enqueue a VM_Operation to do the job for us - sometime later 434 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 435 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 436 VMThread::execute(vm_stop); 437 } 438 439 440 // Check if an external suspend request has completed (or has been 441 // cancelled). Returns true if the thread is externally suspended and 442 // false otherwise. 443 // 444 // The bits parameter returns information about the code path through 445 // the routine. Useful for debugging: 446 // 447 // set in is_ext_suspend_completed(): 448 // 0x00000001 - routine was entered 449 // 0x00000010 - routine return false at end 450 // 0x00000100 - thread exited (return false) 451 // 0x00000200 - suspend request cancelled (return false) 452 // 0x00000400 - thread suspended (return true) 453 // 0x00001000 - thread is in a suspend equivalent state (return true) 454 // 0x00002000 - thread is native and walkable (return true) 455 // 0x00004000 - thread is native_trans and walkable (needed retry) 456 // 457 // set in wait_for_ext_suspend_completion(): 458 // 0x00010000 - routine was entered 459 // 0x00020000 - suspend request cancelled before loop (return false) 460 // 0x00040000 - thread suspended before loop (return true) 461 // 0x00080000 - suspend request cancelled in loop (return false) 462 // 0x00100000 - thread suspended in loop (return true) 463 // 0x00200000 - suspend not completed during retry loop (return false) 464 465 // Helper class for tracing suspend wait debug bits. 466 // 467 // 0x00000100 indicates that the target thread exited before it could 468 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 469 // 0x00080000 each indicate a cancelled suspend request so they don't 470 // count as wait failures either. 471 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 472 473 class TraceSuspendDebugBits : public StackObj { 474 private: 475 JavaThread * jt; 476 bool is_wait; 477 bool called_by_wait; // meaningful when !is_wait 478 uint32_t * bits; 479 480 public: 481 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 482 uint32_t *_bits) { 483 jt = _jt; 484 is_wait = _is_wait; 485 called_by_wait = _called_by_wait; 486 bits = _bits; 487 } 488 489 ~TraceSuspendDebugBits() { 490 if (!is_wait) { 491 #if 1 492 // By default, don't trace bits for is_ext_suspend_completed() calls. 493 // That trace is very chatty. 494 return; 495 #else 496 if (!called_by_wait) { 497 // If tracing for is_ext_suspend_completed() is enabled, then only 498 // trace calls to it from wait_for_ext_suspend_completion() 499 return; 500 } 501 #endif 502 } 503 504 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 505 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 506 MutexLocker ml(Threads_lock); // needed for get_thread_name() 507 ResourceMark rm; 508 509 tty->print_cr( 510 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 511 jt->get_thread_name(), *bits); 512 513 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 514 } 515 } 516 } 517 }; 518 #undef DEBUG_FALSE_BITS 519 520 521 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 522 uint32_t *bits) { 523 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 524 525 bool did_trans_retry = false; // only do thread_in_native_trans retry once 526 bool do_trans_retry; // flag to force the retry 527 528 *bits |= 0x00000001; 529 530 do { 531 do_trans_retry = false; 532 533 if (is_exiting()) { 534 // Thread is in the process of exiting. This is always checked 535 // first to reduce the risk of dereferencing a freed JavaThread. 536 *bits |= 0x00000100; 537 return false; 538 } 539 540 if (!is_external_suspend()) { 541 // Suspend request is cancelled. This is always checked before 542 // is_ext_suspended() to reduce the risk of a rogue resume 543 // confusing the thread that made the suspend request. 544 *bits |= 0x00000200; 545 return false; 546 } 547 548 if (is_ext_suspended()) { 549 // thread is suspended 550 *bits |= 0x00000400; 551 return true; 552 } 553 554 // Now that we no longer do hard suspends of threads running 555 // native code, the target thread can be changing thread state 556 // while we are in this routine: 557 // 558 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 559 // 560 // We save a copy of the thread state as observed at this moment 561 // and make our decision about suspend completeness based on the 562 // copy. This closes the race where the thread state is seen as 563 // _thread_in_native_trans in the if-thread_blocked check, but is 564 // seen as _thread_blocked in if-thread_in_native_trans check. 565 JavaThreadState save_state = thread_state(); 566 567 if (save_state == _thread_blocked && is_suspend_equivalent()) { 568 // If the thread's state is _thread_blocked and this blocking 569 // condition is known to be equivalent to a suspend, then we can 570 // consider the thread to be externally suspended. This means that 571 // the code that sets _thread_blocked has been modified to do 572 // self-suspension if the blocking condition releases. We also 573 // used to check for CONDVAR_WAIT here, but that is now covered by 574 // the _thread_blocked with self-suspension check. 575 // 576 // Return true since we wouldn't be here unless there was still an 577 // external suspend request. 578 *bits |= 0x00001000; 579 return true; 580 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 581 // Threads running native code will self-suspend on native==>VM/Java 582 // transitions. If its stack is walkable (should always be the case 583 // unless this function is called before the actual java_suspend() 584 // call), then the wait is done. 585 *bits |= 0x00002000; 586 return true; 587 } else if (!called_by_wait && !did_trans_retry && 588 save_state == _thread_in_native_trans && 589 frame_anchor()->walkable()) { 590 // The thread is transitioning from thread_in_native to another 591 // thread state. check_safepoint_and_suspend_for_native_trans() 592 // will force the thread to self-suspend. If it hasn't gotten 593 // there yet we may have caught the thread in-between the native 594 // code check above and the self-suspend. Lucky us. If we were 595 // called by wait_for_ext_suspend_completion(), then it 596 // will be doing the retries so we don't have to. 597 // 598 // Since we use the saved thread state in the if-statement above, 599 // there is a chance that the thread has already transitioned to 600 // _thread_blocked by the time we get here. In that case, we will 601 // make a single unnecessary pass through the logic below. This 602 // doesn't hurt anything since we still do the trans retry. 603 604 *bits |= 0x00004000; 605 606 // Once the thread leaves thread_in_native_trans for another 607 // thread state, we break out of this retry loop. We shouldn't 608 // need this flag to prevent us from getting back here, but 609 // sometimes paranoia is good. 610 did_trans_retry = true; 611 612 // We wait for the thread to transition to a more usable state. 613 for (int i = 1; i <= SuspendRetryCount; i++) { 614 // We used to do an "os::yield_all(i)" call here with the intention 615 // that yielding would increase on each retry. However, the parameter 616 // is ignored on Linux which means the yield didn't scale up. Waiting 617 // on the SR_lock below provides a much more predictable scale up for 618 // the delay. It also provides a simple/direct point to check for any 619 // safepoint requests from the VMThread 620 621 // temporarily drops SR_lock while doing wait with safepoint check 622 // (if we're a JavaThread - the WatcherThread can also call this) 623 // and increase delay with each retry 624 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 625 626 // check the actual thread state instead of what we saved above 627 if (thread_state() != _thread_in_native_trans) { 628 // the thread has transitioned to another thread state so 629 // try all the checks (except this one) one more time. 630 do_trans_retry = true; 631 break; 632 } 633 } // end retry loop 634 635 636 } 637 } while (do_trans_retry); 638 639 *bits |= 0x00000010; 640 return false; 641 } 642 643 // Wait for an external suspend request to complete (or be cancelled). 644 // Returns true if the thread is externally suspended and false otherwise. 645 // 646 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 647 uint32_t *bits) { 648 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 649 false /* !called_by_wait */, bits); 650 651 // local flag copies to minimize SR_lock hold time 652 bool is_suspended; 653 bool pending; 654 uint32_t reset_bits; 655 656 // set a marker so is_ext_suspend_completed() knows we are the caller 657 *bits |= 0x00010000; 658 659 // We use reset_bits to reinitialize the bits value at the top of 660 // each retry loop. This allows the caller to make use of any 661 // unused bits for their own marking purposes. 662 reset_bits = *bits; 663 664 { 665 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 666 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 667 delay, bits); 668 pending = is_external_suspend(); 669 } 670 // must release SR_lock to allow suspension to complete 671 672 if (!pending) { 673 // A cancelled suspend request is the only false return from 674 // is_ext_suspend_completed() that keeps us from entering the 675 // retry loop. 676 *bits |= 0x00020000; 677 return false; 678 } 679 680 if (is_suspended) { 681 *bits |= 0x00040000; 682 return true; 683 } 684 685 for (int i = 1; i <= retries; i++) { 686 *bits = reset_bits; // reinit to only track last retry 687 688 // We used to do an "os::yield_all(i)" call here with the intention 689 // that yielding would increase on each retry. However, the parameter 690 // is ignored on Linux which means the yield didn't scale up. Waiting 691 // on the SR_lock below provides a much more predictable scale up for 692 // the delay. It also provides a simple/direct point to check for any 693 // safepoint requests from the VMThread 694 695 { 696 MutexLocker ml(SR_lock()); 697 // wait with safepoint check (if we're a JavaThread - the WatcherThread 698 // can also call this) and increase delay with each retry 699 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 700 701 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 702 delay, bits); 703 704 // It is possible for the external suspend request to be cancelled 705 // (by a resume) before the actual suspend operation is completed. 706 // Refresh our local copy to see if we still need to wait. 707 pending = is_external_suspend(); 708 } 709 710 if (!pending) { 711 // A cancelled suspend request is the only false return from 712 // is_ext_suspend_completed() that keeps us from staying in the 713 // retry loop. 714 *bits |= 0x00080000; 715 return false; 716 } 717 718 if (is_suspended) { 719 *bits |= 0x00100000; 720 return true; 721 } 722 } // end retry loop 723 724 // thread did not suspend after all our retries 725 *bits |= 0x00200000; 726 return false; 727 } 728 729 #ifndef PRODUCT 730 void JavaThread::record_jump(address target, address instr, const char* file, 731 int line) { 732 733 // This should not need to be atomic as the only way for simultaneous 734 // updates is via interrupts. Even then this should be rare or non-existent 735 // and we don't care that much anyway. 736 737 int index = _jmp_ring_index; 738 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 739 _jmp_ring[index]._target = (intptr_t) target; 740 _jmp_ring[index]._instruction = (intptr_t) instr; 741 _jmp_ring[index]._file = file; 742 _jmp_ring[index]._line = line; 743 } 744 #endif // PRODUCT 745 746 // Called by flat profiler 747 // Callers have already called wait_for_ext_suspend_completion 748 // The assertion for that is currently too complex to put here: 749 bool JavaThread::profile_last_Java_frame(frame* _fr) { 750 bool gotframe = false; 751 // self suspension saves needed state. 752 if (has_last_Java_frame() && _anchor.walkable()) { 753 *_fr = pd_last_frame(); 754 gotframe = true; 755 } 756 return gotframe; 757 } 758 759 void Thread::interrupt(Thread* thread) { 760 debug_only(check_for_dangling_thread_pointer(thread);) 761 os::interrupt(thread); 762 } 763 764 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 765 debug_only(check_for_dangling_thread_pointer(thread);) 766 // Note: If clear_interrupted==false, this simply fetches and 767 // returns the value of the field osthread()->interrupted(). 768 return os::is_interrupted(thread, clear_interrupted); 769 } 770 771 772 // GC Support 773 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 774 jint thread_parity = _oops_do_parity; 775 if (thread_parity != strong_roots_parity) { 776 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 777 if (res == thread_parity) { 778 return true; 779 } else { 780 guarantee(res == strong_roots_parity, "Or else what?"); 781 return false; 782 } 783 } 784 return false; 785 } 786 787 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 788 active_handles()->oops_do(f); 789 // Do oop for ThreadShadow 790 f->do_oop((oop*)&_pending_exception); 791 handle_area()->oops_do(f); 792 793 if (MonitorInUseLists) { 794 // When using thread local monitor lists, we scan them here, 795 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 796 ObjectSynchronizer::thread_local_used_oops_do(this, f); 797 } 798 } 799 800 void Thread::metadata_handles_do(void f(Metadata*)) { 801 // Only walk the Handles in Thread. 802 if (metadata_handles() != NULL) { 803 for (int i = 0; i< metadata_handles()->length(); i++) { 804 f(metadata_handles()->at(i)); 805 } 806 } 807 } 808 809 void Thread::print_on(outputStream* st) const { 810 // get_priority assumes osthread initialized 811 if (osthread() != NULL) { 812 int os_prio; 813 if (os::get_native_priority(this, &os_prio) == OS_OK) { 814 st->print("os_prio=%d ", os_prio); 815 } 816 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 817 ext().print_on(st); 818 osthread()->print_on(st); 819 } 820 debug_only(if (WizardMode) print_owned_locks_on(st);) 821 } 822 823 // Thread::print_on_error() is called by fatal error handler. Don't use 824 // any lock or allocate memory. 825 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 826 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 827 828 if (is_VM_thread()) { st->print("VMThread"); } 829 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 830 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 831 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 832 else { st->print("Thread"); } 833 834 if (is_Named_thread()) { 835 st->print(" \"%s\"", name()); 836 } 837 838 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 839 p2i(stack_end()), p2i(stack_base())); 840 841 if (osthread()) { 842 st->print(" [id=%d]", osthread()->thread_id()); 843 } 844 } 845 846 #ifdef ASSERT 847 void Thread::print_owned_locks_on(outputStream* st) const { 848 Monitor *cur = _owned_locks; 849 if (cur == NULL) { 850 st->print(" (no locks) "); 851 } else { 852 st->print_cr(" Locks owned:"); 853 while (cur) { 854 cur->print_on(st); 855 cur = cur->next(); 856 } 857 } 858 } 859 860 static int ref_use_count = 0; 861 862 bool Thread::owns_locks_but_compiled_lock() const { 863 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 864 if (cur != Compile_lock) return true; 865 } 866 return false; 867 } 868 869 870 #endif 871 872 #ifndef PRODUCT 873 874 // The flag: potential_vm_operation notifies if this particular safepoint state could potential 875 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 876 // no threads which allow_vm_block's are held 877 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 878 // Check if current thread is allowed to block at a safepoint 879 if (!(_allow_safepoint_count == 0)) { 880 fatal("Possible safepoint reached by thread that does not allow it"); 881 } 882 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 883 fatal("LEAF method calling lock?"); 884 } 885 886 #ifdef ASSERT 887 if (potential_vm_operation && is_Java_thread() 888 && !Universe::is_bootstrapping()) { 889 // Make sure we do not hold any locks that the VM thread also uses. 890 // This could potentially lead to deadlocks 891 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 892 // Threads_lock is special, since the safepoint synchronization will not start before this is 893 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 894 // since it is used to transfer control between JavaThreads and the VMThread 895 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 896 if ((cur->allow_vm_block() && 897 cur != Threads_lock && 898 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 899 cur != VMOperationRequest_lock && 900 cur != VMOperationQueue_lock) || 901 cur->rank() == Mutex::special) { 902 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 903 } 904 } 905 } 906 907 if (GCALotAtAllSafepoints) { 908 // We could enter a safepoint here and thus have a gc 909 InterfaceSupport::check_gc_alot(); 910 } 911 #endif 912 } 913 #endif 914 915 bool Thread::is_in_stack(address adr) const { 916 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 917 address end = os::current_stack_pointer(); 918 // Allow non Java threads to call this without stack_base 919 if (_stack_base == NULL) return true; 920 if (stack_base() >= adr && adr >= end) return true; 921 922 return false; 923 } 924 925 bool Thread::is_in_usable_stack(address adr) const { 926 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 927 size_t usable_stack_size = _stack_size - stack_guard_size; 928 929 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 930 } 931 932 933 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 934 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 935 // used for compilation in the future. If that change is made, the need for these methods 936 // should be revisited, and they should be removed if possible. 937 938 bool Thread::is_lock_owned(address adr) const { 939 return on_local_stack(adr); 940 } 941 942 bool Thread::set_as_starting_thread() { 943 // NOTE: this must be called inside the main thread. 944 return os::create_main_thread((JavaThread*)this); 945 } 946 947 static void initialize_class(Symbol* class_name, TRAPS) { 948 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 949 InstanceKlass::cast(klass)->initialize(CHECK); 950 } 951 952 953 // Creates the initial ThreadGroup 954 static Handle create_initial_thread_group(TRAPS) { 955 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 956 InstanceKlass* ik = InstanceKlass::cast(k); 957 958 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 959 { 960 JavaValue result(T_VOID); 961 JavaCalls::call_special(&result, 962 system_instance, 963 ik, 964 vmSymbols::object_initializer_name(), 965 vmSymbols::void_method_signature(), 966 CHECK_NH); 967 } 968 Universe::set_system_thread_group(system_instance()); 969 970 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 971 { 972 JavaValue result(T_VOID); 973 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 974 JavaCalls::call_special(&result, 975 main_instance, 976 ik, 977 vmSymbols::object_initializer_name(), 978 vmSymbols::threadgroup_string_void_signature(), 979 system_instance, 980 string, 981 CHECK_NH); 982 } 983 return main_instance; 984 } 985 986 // Creates the initial Thread 987 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 988 TRAPS) { 989 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 990 InstanceKlass* ik = InstanceKlass::cast(k); 991 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 992 993 java_lang_Thread::set_thread(thread_oop(), thread); 994 java_lang_Thread::set_priority(thread_oop(), NormPriority); 995 thread->set_threadObj(thread_oop()); 996 997 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 998 999 JavaValue result(T_VOID); 1000 JavaCalls::call_special(&result, thread_oop, 1001 ik, 1002 vmSymbols::object_initializer_name(), 1003 vmSymbols::threadgroup_string_void_signature(), 1004 thread_group, 1005 string, 1006 CHECK_NULL); 1007 return thread_oop(); 1008 } 1009 1010 char java_runtime_name[128] = ""; 1011 char java_runtime_version[128] = ""; 1012 1013 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1014 static const char* get_java_runtime_name(TRAPS) { 1015 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1016 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1017 fieldDescriptor fd; 1018 bool found = k != NULL && 1019 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1020 vmSymbols::string_signature(), &fd); 1021 if (found) { 1022 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1023 if (name_oop == NULL) { 1024 return NULL; 1025 } 1026 const char* name = java_lang_String::as_utf8_string(name_oop, 1027 java_runtime_name, 1028 sizeof(java_runtime_name)); 1029 return name; 1030 } else { 1031 return NULL; 1032 } 1033 } 1034 1035 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1036 static const char* get_java_runtime_version(TRAPS) { 1037 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1038 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1039 fieldDescriptor fd; 1040 bool found = k != NULL && 1041 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1042 vmSymbols::string_signature(), &fd); 1043 if (found) { 1044 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1045 if (name_oop == NULL) { 1046 return NULL; 1047 } 1048 const char* name = java_lang_String::as_utf8_string(name_oop, 1049 java_runtime_version, 1050 sizeof(java_runtime_version)); 1051 return name; 1052 } else { 1053 return NULL; 1054 } 1055 } 1056 1057 // General purpose hook into Java code, run once when the VM is initialized. 1058 // The Java library method itself may be changed independently from the VM. 1059 static void call_postVMInitHook(TRAPS) { 1060 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1061 if (klass != NULL) { 1062 JavaValue result(T_VOID); 1063 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1064 vmSymbols::void_method_signature(), 1065 CHECK); 1066 } 1067 } 1068 1069 static void reset_vm_info_property(TRAPS) { 1070 // the vm info string 1071 ResourceMark rm(THREAD); 1072 const char *vm_info = VM_Version::vm_info_string(); 1073 1074 // java.lang.System class 1075 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1076 1077 // setProperty arguments 1078 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1079 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1080 1081 // return value 1082 JavaValue r(T_OBJECT); 1083 1084 // public static String setProperty(String key, String value); 1085 JavaCalls::call_static(&r, 1086 klass, 1087 vmSymbols::setProperty_name(), 1088 vmSymbols::string_string_string_signature(), 1089 key_str, 1090 value_str, 1091 CHECK); 1092 } 1093 1094 1095 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1096 bool daemon, TRAPS) { 1097 assert(thread_group.not_null(), "thread group should be specified"); 1098 assert(threadObj() == NULL, "should only create Java thread object once"); 1099 1100 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1101 InstanceKlass* ik = InstanceKlass::cast(k); 1102 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1103 1104 java_lang_Thread::set_thread(thread_oop(), this); 1105 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1106 set_threadObj(thread_oop()); 1107 1108 JavaValue result(T_VOID); 1109 if (thread_name != NULL) { 1110 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1111 // Thread gets assigned specified name and null target 1112 JavaCalls::call_special(&result, 1113 thread_oop, 1114 ik, 1115 vmSymbols::object_initializer_name(), 1116 vmSymbols::threadgroup_string_void_signature(), 1117 thread_group, // Argument 1 1118 name, // Argument 2 1119 THREAD); 1120 } else { 1121 // Thread gets assigned name "Thread-nnn" and null target 1122 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1123 JavaCalls::call_special(&result, 1124 thread_oop, 1125 ik, 1126 vmSymbols::object_initializer_name(), 1127 vmSymbols::threadgroup_runnable_void_signature(), 1128 thread_group, // Argument 1 1129 Handle(), // Argument 2 1130 THREAD); 1131 } 1132 1133 1134 if (daemon) { 1135 java_lang_Thread::set_daemon(thread_oop()); 1136 } 1137 1138 if (HAS_PENDING_EXCEPTION) { 1139 return; 1140 } 1141 1142 Klass* group = SystemDictionary::ThreadGroup_klass(); 1143 Handle threadObj(THREAD, this->threadObj()); 1144 1145 JavaCalls::call_special(&result, 1146 thread_group, 1147 group, 1148 vmSymbols::add_method_name(), 1149 vmSymbols::thread_void_signature(), 1150 threadObj, // Arg 1 1151 THREAD); 1152 } 1153 1154 // NamedThread -- non-JavaThread subclasses with multiple 1155 // uniquely named instances should derive from this. 1156 NamedThread::NamedThread() : Thread() { 1157 _name = NULL; 1158 _processed_thread = NULL; 1159 _gc_id = GCId::undefined(); 1160 } 1161 1162 NamedThread::~NamedThread() { 1163 if (_name != NULL) { 1164 FREE_C_HEAP_ARRAY(char, _name); 1165 _name = NULL; 1166 } 1167 } 1168 1169 void NamedThread::set_name(const char* format, ...) { 1170 guarantee(_name == NULL, "Only get to set name once."); 1171 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1172 guarantee(_name != NULL, "alloc failure"); 1173 va_list ap; 1174 va_start(ap, format); 1175 jio_vsnprintf(_name, max_name_len, format, ap); 1176 va_end(ap); 1177 } 1178 1179 void NamedThread::initialize_named_thread() { 1180 set_native_thread_name(name()); 1181 } 1182 1183 void NamedThread::print_on(outputStream* st) const { 1184 st->print("\"%s\" ", name()); 1185 Thread::print_on(st); 1186 st->cr(); 1187 } 1188 1189 1190 // ======= WatcherThread ======== 1191 1192 // The watcher thread exists to simulate timer interrupts. It should 1193 // be replaced by an abstraction over whatever native support for 1194 // timer interrupts exists on the platform. 1195 1196 WatcherThread* WatcherThread::_watcher_thread = NULL; 1197 bool WatcherThread::_startable = false; 1198 volatile bool WatcherThread::_should_terminate = false; 1199 1200 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { 1201 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1202 if (os::create_thread(this, os::watcher_thread)) { 1203 _watcher_thread = this; 1204 1205 // Set the watcher thread to the highest OS priority which should not be 1206 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1207 // is created. The only normal thread using this priority is the reference 1208 // handler thread, which runs for very short intervals only. 1209 // If the VMThread's priority is not lower than the WatcherThread profiling 1210 // will be inaccurate. 1211 os::set_priority(this, MaxPriority); 1212 if (!DisableStartThread) { 1213 os::start_thread(this); 1214 } 1215 } 1216 } 1217 1218 int WatcherThread::sleep() const { 1219 // The WatcherThread does not participate in the safepoint protocol 1220 // for the PeriodicTask_lock because it is not a JavaThread. 1221 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1222 1223 if (_should_terminate) { 1224 // check for termination before we do any housekeeping or wait 1225 return 0; // we did not sleep. 1226 } 1227 1228 // remaining will be zero if there are no tasks, 1229 // causing the WatcherThread to sleep until a task is 1230 // enrolled 1231 int remaining = PeriodicTask::time_to_wait(); 1232 int time_slept = 0; 1233 1234 // we expect this to timeout - we only ever get unparked when 1235 // we should terminate or when a new task has been enrolled 1236 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1237 1238 jlong time_before_loop = os::javaTimeNanos(); 1239 1240 while (true) { 1241 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1242 remaining); 1243 jlong now = os::javaTimeNanos(); 1244 1245 if (remaining == 0) { 1246 // if we didn't have any tasks we could have waited for a long time 1247 // consider the time_slept zero and reset time_before_loop 1248 time_slept = 0; 1249 time_before_loop = now; 1250 } else { 1251 // need to recalculate since we might have new tasks in _tasks 1252 time_slept = (int) ((now - time_before_loop) / 1000000); 1253 } 1254 1255 // Change to task list or spurious wakeup of some kind 1256 if (timedout || _should_terminate) { 1257 break; 1258 } 1259 1260 remaining = PeriodicTask::time_to_wait(); 1261 if (remaining == 0) { 1262 // Last task was just disenrolled so loop around and wait until 1263 // another task gets enrolled 1264 continue; 1265 } 1266 1267 remaining -= time_slept; 1268 if (remaining <= 0) { 1269 break; 1270 } 1271 } 1272 1273 return time_slept; 1274 } 1275 1276 void WatcherThread::run() { 1277 assert(this == watcher_thread(), "just checking"); 1278 1279 this->record_stack_base_and_size(); 1280 this->set_native_thread_name(this->name()); 1281 this->set_active_handles(JNIHandleBlock::allocate_block()); 1282 while (true) { 1283 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1284 assert(watcher_thread() == this, "thread consistency check"); 1285 1286 // Calculate how long it'll be until the next PeriodicTask work 1287 // should be done, and sleep that amount of time. 1288 int time_waited = sleep(); 1289 1290 if (is_error_reported()) { 1291 // A fatal error has happened, the error handler(VMError::report_and_die) 1292 // should abort JVM after creating an error log file. However in some 1293 // rare cases, the error handler itself might deadlock. Here periodically 1294 // check for error reporting timeouts, and if it happens, just proceed to 1295 // abort the VM. 1296 1297 // This code is in WatcherThread because WatcherThread wakes up 1298 // periodically so the fatal error handler doesn't need to do anything; 1299 // also because the WatcherThread is less likely to crash than other 1300 // threads. 1301 1302 for (;;) { 1303 // Note: we use naked sleep in this loop because we want to avoid using 1304 // any kind of VM infrastructure which may be broken at this point. 1305 if (VMError::check_timeout()) { 1306 // We hit error reporting timeout. Error reporting was interrupted and 1307 // will be wrapping things up now (closing files etc). Give it some more 1308 // time, then quit the VM. 1309 os::naked_short_sleep(200); 1310 // Print a message to stderr. 1311 fdStream err(defaultStream::output_fd()); 1312 err.print_raw_cr("# [ timer expired, abort... ]"); 1313 // skip atexit/vm_exit/vm_abort hooks 1314 os::die(); 1315 } 1316 1317 // Wait a second, then recheck for timeout. 1318 os::naked_short_sleep(999); 1319 } 1320 } 1321 1322 if (_should_terminate) { 1323 // check for termination before posting the next tick 1324 break; 1325 } 1326 1327 PeriodicTask::real_time_tick(time_waited); 1328 } 1329 1330 // Signal that it is terminated 1331 { 1332 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1333 _watcher_thread = NULL; 1334 Terminator_lock->notify(); 1335 } 1336 } 1337 1338 void WatcherThread::start() { 1339 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1340 1341 if (watcher_thread() == NULL && _startable) { 1342 _should_terminate = false; 1343 // Create the single instance of WatcherThread 1344 new WatcherThread(); 1345 } 1346 } 1347 1348 void WatcherThread::make_startable() { 1349 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1350 _startable = true; 1351 } 1352 1353 void WatcherThread::stop() { 1354 { 1355 // Follow normal safepoint aware lock enter protocol since the 1356 // WatcherThread is stopped by another JavaThread. 1357 MutexLocker ml(PeriodicTask_lock); 1358 _should_terminate = true; 1359 1360 WatcherThread* watcher = watcher_thread(); 1361 if (watcher != NULL) { 1362 // unpark the WatcherThread so it can see that it should terminate 1363 watcher->unpark(); 1364 } 1365 } 1366 1367 MutexLocker mu(Terminator_lock); 1368 1369 while (watcher_thread() != NULL) { 1370 // This wait should make safepoint checks, wait without a timeout, 1371 // and wait as a suspend-equivalent condition. 1372 // 1373 // Note: If the FlatProfiler is running, then this thread is waiting 1374 // for the WatcherThread to terminate and the WatcherThread, via the 1375 // FlatProfiler task, is waiting for the external suspend request on 1376 // this thread to complete. wait_for_ext_suspend_completion() will 1377 // eventually timeout, but that takes time. Making this wait a 1378 // suspend-equivalent condition solves that timeout problem. 1379 // 1380 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1381 Mutex::_as_suspend_equivalent_flag); 1382 } 1383 } 1384 1385 void WatcherThread::unpark() { 1386 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1387 PeriodicTask_lock->notify(); 1388 } 1389 1390 void WatcherThread::print_on(outputStream* st) const { 1391 st->print("\"%s\" ", name()); 1392 Thread::print_on(st); 1393 st->cr(); 1394 } 1395 1396 // ======= JavaThread ======== 1397 1398 #if INCLUDE_JVMCI 1399 1400 jlong* JavaThread::_jvmci_old_thread_counters; 1401 1402 bool jvmci_counters_include(JavaThread* thread) { 1403 oop threadObj = thread->threadObj(); 1404 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1405 } 1406 1407 void JavaThread::collect_counters(typeArrayOop array) { 1408 if (JVMCICounterSize > 0) { 1409 MutexLocker tl(Threads_lock); 1410 for (int i = 0; i < array->length(); i++) { 1411 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1412 } 1413 for (JavaThread* tp = Threads::first(); tp != NULL; tp = tp->next()) { 1414 if (jvmci_counters_include(tp)) { 1415 for (int i = 0; i < array->length(); i++) { 1416 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1417 } 1418 } 1419 } 1420 } 1421 } 1422 1423 #endif // INCLUDE_JVMCI 1424 1425 // A JavaThread is a normal Java thread 1426 1427 void JavaThread::initialize() { 1428 // Initialize fields 1429 1430 set_saved_exception_pc(NULL); 1431 set_threadObj(NULL); 1432 _anchor.clear(); 1433 set_entry_point(NULL); 1434 set_jni_functions(jni_functions()); 1435 set_callee_target(NULL); 1436 set_vm_result(NULL); 1437 set_vm_result_2(NULL); 1438 set_vframe_array_head(NULL); 1439 set_vframe_array_last(NULL); 1440 set_deferred_locals(NULL); 1441 set_deopt_mark(NULL); 1442 set_deopt_compiled_method(NULL); 1443 clear_must_deopt_id(); 1444 set_monitor_chunks(NULL); 1445 set_next(NULL); 1446 set_thread_state(_thread_new); 1447 _terminated = _not_terminated; 1448 _privileged_stack_top = NULL; 1449 _array_for_gc = NULL; 1450 _suspend_equivalent = false; 1451 _in_deopt_handler = 0; 1452 _doing_unsafe_access = false; 1453 _stack_guard_state = stack_guard_unused; 1454 #if INCLUDE_JVMCI 1455 _pending_monitorenter = false; 1456 _pending_deoptimization = -1; 1457 _pending_failed_speculation = NULL; 1458 _pending_transfer_to_interpreter = false; 1459 _adjusting_comp_level = false; 1460 _jvmci._alternate_call_target = NULL; 1461 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1462 if (JVMCICounterSize > 0) { 1463 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1464 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1465 } else { 1466 _jvmci_counters = NULL; 1467 } 1468 #endif // INCLUDE_JVMCI 1469 _reserved_stack_activation = NULL; // stack base not known yet 1470 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1471 _exception_pc = 0; 1472 _exception_handler_pc = 0; 1473 _is_method_handle_return = 0; 1474 _jvmti_thread_state= NULL; 1475 _should_post_on_exceptions_flag = JNI_FALSE; 1476 _jvmti_get_loaded_classes_closure = NULL; 1477 _interp_only_mode = 0; 1478 _special_runtime_exit_condition = _no_async_condition; 1479 _pending_async_exception = NULL; 1480 _thread_stat = NULL; 1481 _thread_stat = new ThreadStatistics(); 1482 _blocked_on_compilation = false; 1483 _jni_active_critical = 0; 1484 _pending_jni_exception_check_fn = NULL; 1485 _do_not_unlock_if_synchronized = false; 1486 _cached_monitor_info = NULL; 1487 _parker = Parker::Allocate(this); 1488 1489 #ifndef PRODUCT 1490 _jmp_ring_index = 0; 1491 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1492 record_jump(NULL, NULL, NULL, 0); 1493 } 1494 #endif // PRODUCT 1495 1496 set_thread_profiler(NULL); 1497 if (FlatProfiler::is_active()) { 1498 // This is where we would decide to either give each thread it's own profiler 1499 // or use one global one from FlatProfiler, 1500 // or up to some count of the number of profiled threads, etc. 1501 ThreadProfiler* pp = new ThreadProfiler(); 1502 pp->engage(); 1503 set_thread_profiler(pp); 1504 } 1505 1506 // Setup safepoint state info for this thread 1507 ThreadSafepointState::create(this); 1508 1509 debug_only(_java_call_counter = 0); 1510 1511 // JVMTI PopFrame support 1512 _popframe_condition = popframe_inactive; 1513 _popframe_preserved_args = NULL; 1514 _popframe_preserved_args_size = 0; 1515 _frames_to_pop_failed_realloc = 0; 1516 1517 pd_initialize(); 1518 } 1519 1520 #if INCLUDE_ALL_GCS 1521 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1522 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1523 #endif // INCLUDE_ALL_GCS 1524 1525 JavaThread::JavaThread(bool is_attaching_via_jni) : 1526 Thread() 1527 #if INCLUDE_ALL_GCS 1528 , _satb_mark_queue(&_satb_mark_queue_set), 1529 _dirty_card_queue(&_dirty_card_queue_set) 1530 #endif // INCLUDE_ALL_GCS 1531 { 1532 initialize(); 1533 if (is_attaching_via_jni) { 1534 _jni_attach_state = _attaching_via_jni; 1535 } else { 1536 _jni_attach_state = _not_attaching_via_jni; 1537 } 1538 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1539 } 1540 1541 bool JavaThread::reguard_stack(address cur_sp) { 1542 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1543 && _stack_guard_state != stack_guard_reserved_disabled) { 1544 return true; // Stack already guarded or guard pages not needed. 1545 } 1546 1547 if (register_stack_overflow()) { 1548 // For those architectures which have separate register and 1549 // memory stacks, we must check the register stack to see if 1550 // it has overflowed. 1551 return false; 1552 } 1553 1554 // Java code never executes within the yellow zone: the latter is only 1555 // there to provoke an exception during stack banging. If java code 1556 // is executing there, either StackShadowPages should be larger, or 1557 // some exception code in c1, c2 or the interpreter isn't unwinding 1558 // when it should. 1559 guarantee(cur_sp > stack_reserved_zone_base(), 1560 "not enough space to reguard - increase StackShadowPages"); 1561 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1562 enable_stack_yellow_reserved_zone(); 1563 if (reserved_stack_activation() != stack_base()) { 1564 set_reserved_stack_activation(stack_base()); 1565 } 1566 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1567 set_reserved_stack_activation(stack_base()); 1568 enable_stack_reserved_zone(); 1569 } 1570 return true; 1571 } 1572 1573 bool JavaThread::reguard_stack(void) { 1574 return reguard_stack(os::current_stack_pointer()); 1575 } 1576 1577 1578 void JavaThread::block_if_vm_exited() { 1579 if (_terminated == _vm_exited) { 1580 // _vm_exited is set at safepoint, and Threads_lock is never released 1581 // we will block here forever 1582 Threads_lock->lock_without_safepoint_check(); 1583 ShouldNotReachHere(); 1584 } 1585 } 1586 1587 1588 // Remove this ifdef when C1 is ported to the compiler interface. 1589 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1590 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1591 1592 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1593 Thread() 1594 #if INCLUDE_ALL_GCS 1595 , _satb_mark_queue(&_satb_mark_queue_set), 1596 _dirty_card_queue(&_dirty_card_queue_set) 1597 #endif // INCLUDE_ALL_GCS 1598 { 1599 initialize(); 1600 _jni_attach_state = _not_attaching_via_jni; 1601 set_entry_point(entry_point); 1602 // Create the native thread itself. 1603 // %note runtime_23 1604 os::ThreadType thr_type = os::java_thread; 1605 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1606 os::java_thread; 1607 os::create_thread(this, thr_type, stack_sz); 1608 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1609 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1610 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1611 // the exception consists of creating the exception object & initializing it, initialization 1612 // will leave the VM via a JavaCall and then all locks must be unlocked). 1613 // 1614 // The thread is still suspended when we reach here. Thread must be explicit started 1615 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1616 // by calling Threads:add. The reason why this is not done here, is because the thread 1617 // object must be fully initialized (take a look at JVM_Start) 1618 } 1619 1620 JavaThread::~JavaThread() { 1621 1622 // JSR166 -- return the parker to the free list 1623 Parker::Release(_parker); 1624 _parker = NULL; 1625 1626 // Free any remaining previous UnrollBlock 1627 vframeArray* old_array = vframe_array_last(); 1628 1629 if (old_array != NULL) { 1630 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1631 old_array->set_unroll_block(NULL); 1632 delete old_info; 1633 delete old_array; 1634 } 1635 1636 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1637 if (deferred != NULL) { 1638 // This can only happen if thread is destroyed before deoptimization occurs. 1639 assert(deferred->length() != 0, "empty array!"); 1640 do { 1641 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1642 deferred->remove_at(0); 1643 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1644 delete dlv; 1645 } while (deferred->length() != 0); 1646 delete deferred; 1647 } 1648 1649 // All Java related clean up happens in exit 1650 ThreadSafepointState::destroy(this); 1651 if (_thread_profiler != NULL) delete _thread_profiler; 1652 if (_thread_stat != NULL) delete _thread_stat; 1653 1654 #if INCLUDE_JVMCI 1655 if (JVMCICounterSize > 0) { 1656 if (jvmci_counters_include(this)) { 1657 for (int i = 0; i < JVMCICounterSize; i++) { 1658 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1659 } 1660 } 1661 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1662 } 1663 #endif // INCLUDE_JVMCI 1664 } 1665 1666 1667 // The first routine called by a new Java thread 1668 void JavaThread::run() { 1669 // initialize thread-local alloc buffer related fields 1670 this->initialize_tlab(); 1671 1672 // used to test validity of stack trace backs 1673 this->record_base_of_stack_pointer(); 1674 1675 // Record real stack base and size. 1676 this->record_stack_base_and_size(); 1677 1678 this->create_stack_guard_pages(); 1679 1680 this->cache_global_variables(); 1681 1682 // Thread is now sufficient initialized to be handled by the safepoint code as being 1683 // in the VM. Change thread state from _thread_new to _thread_in_vm 1684 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1685 1686 assert(JavaThread::current() == this, "sanity check"); 1687 assert(!Thread::current()->owns_locks(), "sanity check"); 1688 1689 DTRACE_THREAD_PROBE(start, this); 1690 1691 // This operation might block. We call that after all safepoint checks for a new thread has 1692 // been completed. 1693 this->set_active_handles(JNIHandleBlock::allocate_block()); 1694 1695 if (JvmtiExport::should_post_thread_life()) { 1696 JvmtiExport::post_thread_start(this); 1697 } 1698 1699 EventThreadStart event; 1700 if (event.should_commit()) { 1701 event.set_thread(THREAD_TRACE_ID(this)); 1702 event.commit(); 1703 } 1704 1705 // We call another function to do the rest so we are sure that the stack addresses used 1706 // from there will be lower than the stack base just computed 1707 thread_main_inner(); 1708 1709 // Note, thread is no longer valid at this point! 1710 } 1711 1712 1713 void JavaThread::thread_main_inner() { 1714 assert(JavaThread::current() == this, "sanity check"); 1715 assert(this->threadObj() != NULL, "just checking"); 1716 1717 // Execute thread entry point unless this thread has a pending exception 1718 // or has been stopped before starting. 1719 // Note: Due to JVM_StopThread we can have pending exceptions already! 1720 if (!this->has_pending_exception() && 1721 !java_lang_Thread::is_stillborn(this->threadObj())) { 1722 { 1723 ResourceMark rm(this); 1724 this->set_native_thread_name(this->get_thread_name()); 1725 } 1726 HandleMark hm(this); 1727 this->entry_point()(this, this); 1728 } 1729 1730 DTRACE_THREAD_PROBE(stop, this); 1731 1732 this->exit(false); 1733 delete this; 1734 } 1735 1736 1737 static void ensure_join(JavaThread* thread) { 1738 // We do not need to grap the Threads_lock, since we are operating on ourself. 1739 Handle threadObj(thread, thread->threadObj()); 1740 assert(threadObj.not_null(), "java thread object must exist"); 1741 ObjectLocker lock(threadObj, thread); 1742 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1743 thread->clear_pending_exception(); 1744 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1745 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1746 // Clear the native thread instance - this makes isAlive return false and allows the join() 1747 // to complete once we've done the notify_all below 1748 java_lang_Thread::set_thread(threadObj(), NULL); 1749 lock.notify_all(thread); 1750 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1751 thread->clear_pending_exception(); 1752 } 1753 1754 1755 // For any new cleanup additions, please check to see if they need to be applied to 1756 // cleanup_failed_attach_current_thread as well. 1757 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1758 assert(this == JavaThread::current(), "thread consistency check"); 1759 1760 HandleMark hm(this); 1761 Handle uncaught_exception(this, this->pending_exception()); 1762 this->clear_pending_exception(); 1763 Handle threadObj(this, this->threadObj()); 1764 assert(threadObj.not_null(), "Java thread object should be created"); 1765 1766 if (get_thread_profiler() != NULL) { 1767 get_thread_profiler()->disengage(); 1768 ResourceMark rm; 1769 get_thread_profiler()->print(get_thread_name()); 1770 } 1771 1772 1773 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1774 { 1775 EXCEPTION_MARK; 1776 1777 CLEAR_PENDING_EXCEPTION; 1778 } 1779 if (!destroy_vm) { 1780 if (uncaught_exception.not_null()) { 1781 EXCEPTION_MARK; 1782 // Call method Thread.dispatchUncaughtException(). 1783 Klass* thread_klass = SystemDictionary::Thread_klass(); 1784 JavaValue result(T_VOID); 1785 JavaCalls::call_virtual(&result, 1786 threadObj, thread_klass, 1787 vmSymbols::dispatchUncaughtException_name(), 1788 vmSymbols::throwable_void_signature(), 1789 uncaught_exception, 1790 THREAD); 1791 if (HAS_PENDING_EXCEPTION) { 1792 ResourceMark rm(this); 1793 jio_fprintf(defaultStream::error_stream(), 1794 "\nException: %s thrown from the UncaughtExceptionHandler" 1795 " in thread \"%s\"\n", 1796 pending_exception()->klass()->external_name(), 1797 get_thread_name()); 1798 CLEAR_PENDING_EXCEPTION; 1799 } 1800 } 1801 1802 // Called before the java thread exit since we want to read info 1803 // from java_lang_Thread object 1804 EventThreadEnd event; 1805 if (event.should_commit()) { 1806 event.set_thread(THREAD_TRACE_ID(this)); 1807 event.commit(); 1808 } 1809 1810 // Call after last event on thread 1811 EVENT_THREAD_EXIT(this); 1812 1813 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1814 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1815 // is deprecated anyhow. 1816 if (!is_Compiler_thread()) { 1817 int count = 3; 1818 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1819 EXCEPTION_MARK; 1820 JavaValue result(T_VOID); 1821 Klass* thread_klass = SystemDictionary::Thread_klass(); 1822 JavaCalls::call_virtual(&result, 1823 threadObj, thread_klass, 1824 vmSymbols::exit_method_name(), 1825 vmSymbols::void_method_signature(), 1826 THREAD); 1827 CLEAR_PENDING_EXCEPTION; 1828 } 1829 } 1830 // notify JVMTI 1831 if (JvmtiExport::should_post_thread_life()) { 1832 JvmtiExport::post_thread_end(this); 1833 } 1834 1835 // We have notified the agents that we are exiting, before we go on, 1836 // we must check for a pending external suspend request and honor it 1837 // in order to not surprise the thread that made the suspend request. 1838 while (true) { 1839 { 1840 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1841 if (!is_external_suspend()) { 1842 set_terminated(_thread_exiting); 1843 ThreadService::current_thread_exiting(this); 1844 break; 1845 } 1846 // Implied else: 1847 // Things get a little tricky here. We have a pending external 1848 // suspend request, but we are holding the SR_lock so we 1849 // can't just self-suspend. So we temporarily drop the lock 1850 // and then self-suspend. 1851 } 1852 1853 ThreadBlockInVM tbivm(this); 1854 java_suspend_self(); 1855 1856 // We're done with this suspend request, but we have to loop around 1857 // and check again. Eventually we will get SR_lock without a pending 1858 // external suspend request and will be able to mark ourselves as 1859 // exiting. 1860 } 1861 // no more external suspends are allowed at this point 1862 } else { 1863 // before_exit() has already posted JVMTI THREAD_END events 1864 } 1865 1866 // Notify waiters on thread object. This has to be done after exit() is called 1867 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1868 // group should have the destroyed bit set before waiters are notified). 1869 ensure_join(this); 1870 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1871 1872 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1873 // held by this thread must be released. The spec does not distinguish 1874 // between JNI-acquired and regular Java monitors. We can only see 1875 // regular Java monitors here if monitor enter-exit matching is broken. 1876 // 1877 // Optionally release any monitors for regular JavaThread exits. This 1878 // is provided as a work around for any bugs in monitor enter-exit 1879 // matching. This can be expensive so it is not enabled by default. 1880 // 1881 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1882 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1883 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1884 // Sanity check even though JNI DetachCurrentThread() would have 1885 // returned JNI_ERR if there was a Java frame. JavaThread exit 1886 // should be done executing Java code by the time we get here. 1887 assert(!this->has_last_Java_frame(), 1888 "should not have a Java frame when detaching or exiting"); 1889 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1890 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1891 } 1892 1893 // These things needs to be done while we are still a Java Thread. Make sure that thread 1894 // is in a consistent state, in case GC happens 1895 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1896 1897 if (active_handles() != NULL) { 1898 JNIHandleBlock* block = active_handles(); 1899 set_active_handles(NULL); 1900 JNIHandleBlock::release_block(block); 1901 } 1902 1903 if (free_handle_block() != NULL) { 1904 JNIHandleBlock* block = free_handle_block(); 1905 set_free_handle_block(NULL); 1906 JNIHandleBlock::release_block(block); 1907 } 1908 1909 // These have to be removed while this is still a valid thread. 1910 remove_stack_guard_pages(); 1911 1912 if (UseTLAB) { 1913 tlab().make_parsable(true); // retire TLAB 1914 } 1915 1916 if (JvmtiEnv::environments_might_exist()) { 1917 JvmtiExport::cleanup_thread(this); 1918 } 1919 1920 // We must flush any deferred card marks before removing a thread from 1921 // the list of active threads. 1922 Universe::heap()->flush_deferred_store_barrier(this); 1923 assert(deferred_card_mark().is_empty(), "Should have been flushed"); 1924 1925 #if INCLUDE_ALL_GCS 1926 // We must flush the G1-related buffers before removing a thread 1927 // from the list of active threads. We must do this after any deferred 1928 // card marks have been flushed (above) so that any entries that are 1929 // added to the thread's dirty card queue as a result are not lost. 1930 if (UseG1GC) { 1931 flush_barrier_queues(); 1932 } 1933 #endif // INCLUDE_ALL_GCS 1934 1935 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 1936 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 1937 os::current_thread_id()); 1938 1939 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1940 Threads::remove(this); 1941 } 1942 1943 #if INCLUDE_ALL_GCS 1944 // Flush G1-related queues. 1945 void JavaThread::flush_barrier_queues() { 1946 satb_mark_queue().flush(); 1947 dirty_card_queue().flush(); 1948 } 1949 1950 void JavaThread::initialize_queues() { 1951 assert(!SafepointSynchronize::is_at_safepoint(), 1952 "we should not be at a safepoint"); 1953 1954 SATBMarkQueue& satb_queue = satb_mark_queue(); 1955 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1956 // The SATB queue should have been constructed with its active 1957 // field set to false. 1958 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1959 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1960 // If we are creating the thread during a marking cycle, we should 1961 // set the active field of the SATB queue to true. 1962 if (satb_queue_set.is_active()) { 1963 satb_queue.set_active(true); 1964 } 1965 1966 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1967 // The dirty card queue should have been constructed with its 1968 // active field set to true. 1969 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1970 } 1971 #endif // INCLUDE_ALL_GCS 1972 1973 void JavaThread::cleanup_failed_attach_current_thread() { 1974 if (get_thread_profiler() != NULL) { 1975 get_thread_profiler()->disengage(); 1976 ResourceMark rm; 1977 get_thread_profiler()->print(get_thread_name()); 1978 } 1979 1980 if (active_handles() != NULL) { 1981 JNIHandleBlock* block = active_handles(); 1982 set_active_handles(NULL); 1983 JNIHandleBlock::release_block(block); 1984 } 1985 1986 if (free_handle_block() != NULL) { 1987 JNIHandleBlock* block = free_handle_block(); 1988 set_free_handle_block(NULL); 1989 JNIHandleBlock::release_block(block); 1990 } 1991 1992 // These have to be removed while this is still a valid thread. 1993 remove_stack_guard_pages(); 1994 1995 if (UseTLAB) { 1996 tlab().make_parsable(true); // retire TLAB, if any 1997 } 1998 1999 #if INCLUDE_ALL_GCS 2000 if (UseG1GC) { 2001 flush_barrier_queues(); 2002 } 2003 #endif // INCLUDE_ALL_GCS 2004 2005 Threads::remove(this); 2006 delete this; 2007 } 2008 2009 2010 2011 2012 JavaThread* JavaThread::active() { 2013 Thread* thread = Thread::current(); 2014 if (thread->is_Java_thread()) { 2015 return (JavaThread*) thread; 2016 } else { 2017 assert(thread->is_VM_thread(), "this must be a vm thread"); 2018 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2019 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2020 assert(ret->is_Java_thread(), "must be a Java thread"); 2021 return ret; 2022 } 2023 } 2024 2025 bool JavaThread::is_lock_owned(address adr) const { 2026 if (Thread::is_lock_owned(adr)) return true; 2027 2028 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2029 if (chunk->contains(adr)) return true; 2030 } 2031 2032 return false; 2033 } 2034 2035 2036 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2037 chunk->set_next(monitor_chunks()); 2038 set_monitor_chunks(chunk); 2039 } 2040 2041 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2042 guarantee(monitor_chunks() != NULL, "must be non empty"); 2043 if (monitor_chunks() == chunk) { 2044 set_monitor_chunks(chunk->next()); 2045 } else { 2046 MonitorChunk* prev = monitor_chunks(); 2047 while (prev->next() != chunk) prev = prev->next(); 2048 prev->set_next(chunk->next()); 2049 } 2050 } 2051 2052 // JVM support. 2053 2054 // Note: this function shouldn't block if it's called in 2055 // _thread_in_native_trans state (such as from 2056 // check_special_condition_for_native_trans()). 2057 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2058 2059 if (has_last_Java_frame() && has_async_condition()) { 2060 // If we are at a polling page safepoint (not a poll return) 2061 // then we must defer async exception because live registers 2062 // will be clobbered by the exception path. Poll return is 2063 // ok because the call we a returning from already collides 2064 // with exception handling registers and so there is no issue. 2065 // (The exception handling path kills call result registers but 2066 // this is ok since the exception kills the result anyway). 2067 2068 if (is_at_poll_safepoint()) { 2069 // if the code we are returning to has deoptimized we must defer 2070 // the exception otherwise live registers get clobbered on the 2071 // exception path before deoptimization is able to retrieve them. 2072 // 2073 RegisterMap map(this, false); 2074 frame caller_fr = last_frame().sender(&map); 2075 assert(caller_fr.is_compiled_frame(), "what?"); 2076 if (caller_fr.is_deoptimized_frame()) { 2077 log_info(exceptions)("deferred async exception at compiled safepoint"); 2078 return; 2079 } 2080 } 2081 } 2082 2083 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2084 if (condition == _no_async_condition) { 2085 // Conditions have changed since has_special_runtime_exit_condition() 2086 // was called: 2087 // - if we were here only because of an external suspend request, 2088 // then that was taken care of above (or cancelled) so we are done 2089 // - if we were here because of another async request, then it has 2090 // been cleared between the has_special_runtime_exit_condition() 2091 // and now so again we are done 2092 return; 2093 } 2094 2095 // Check for pending async. exception 2096 if (_pending_async_exception != NULL) { 2097 // Only overwrite an already pending exception, if it is not a threadDeath. 2098 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2099 2100 // We cannot call Exceptions::_throw(...) here because we cannot block 2101 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2102 2103 if (log_is_enabled(Info, exceptions)) { 2104 ResourceMark rm; 2105 outputStream* logstream = Log(exceptions)::info_stream(); 2106 logstream->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2107 if (has_last_Java_frame()) { 2108 frame f = last_frame(); 2109 logstream->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2110 } 2111 logstream->print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2112 } 2113 _pending_async_exception = NULL; 2114 clear_has_async_exception(); 2115 } 2116 } 2117 2118 if (check_unsafe_error && 2119 condition == _async_unsafe_access_error && !has_pending_exception()) { 2120 condition = _no_async_condition; // done 2121 switch (thread_state()) { 2122 case _thread_in_vm: { 2123 JavaThread* THREAD = this; 2124 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2125 } 2126 case _thread_in_native: { 2127 ThreadInVMfromNative tiv(this); 2128 JavaThread* THREAD = this; 2129 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2130 } 2131 case _thread_in_Java: { 2132 ThreadInVMfromJava tiv(this); 2133 JavaThread* THREAD = this; 2134 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2135 } 2136 default: 2137 ShouldNotReachHere(); 2138 } 2139 } 2140 2141 assert(condition == _no_async_condition || has_pending_exception() || 2142 (!check_unsafe_error && condition == _async_unsafe_access_error), 2143 "must have handled the async condition, if no exception"); 2144 } 2145 2146 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2147 // 2148 // Check for pending external suspend. Internal suspend requests do 2149 // not use handle_special_runtime_exit_condition(). 2150 // If JNIEnv proxies are allowed, don't self-suspend if the target 2151 // thread is not the current thread. In older versions of jdbx, jdbx 2152 // threads could call into the VM with another thread's JNIEnv so we 2153 // can be here operating on behalf of a suspended thread (4432884). 2154 bool do_self_suspend = is_external_suspend_with_lock(); 2155 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2156 // 2157 // Because thread is external suspended the safepoint code will count 2158 // thread as at a safepoint. This can be odd because we can be here 2159 // as _thread_in_Java which would normally transition to _thread_blocked 2160 // at a safepoint. We would like to mark the thread as _thread_blocked 2161 // before calling java_suspend_self like all other callers of it but 2162 // we must then observe proper safepoint protocol. (We can't leave 2163 // _thread_blocked with a safepoint in progress). However we can be 2164 // here as _thread_in_native_trans so we can't use a normal transition 2165 // constructor/destructor pair because they assert on that type of 2166 // transition. We could do something like: 2167 // 2168 // JavaThreadState state = thread_state(); 2169 // set_thread_state(_thread_in_vm); 2170 // { 2171 // ThreadBlockInVM tbivm(this); 2172 // java_suspend_self() 2173 // } 2174 // set_thread_state(_thread_in_vm_trans); 2175 // if (safepoint) block; 2176 // set_thread_state(state); 2177 // 2178 // but that is pretty messy. Instead we just go with the way the 2179 // code has worked before and note that this is the only path to 2180 // java_suspend_self that doesn't put the thread in _thread_blocked 2181 // mode. 2182 2183 frame_anchor()->make_walkable(this); 2184 java_suspend_self(); 2185 2186 // We might be here for reasons in addition to the self-suspend request 2187 // so check for other async requests. 2188 } 2189 2190 if (check_asyncs) { 2191 check_and_handle_async_exceptions(); 2192 } 2193 } 2194 2195 void JavaThread::send_thread_stop(oop java_throwable) { 2196 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2197 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2198 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2199 2200 // Do not throw asynchronous exceptions against the compiler thread 2201 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2202 if (!can_call_java()) return; 2203 2204 { 2205 // Actually throw the Throwable against the target Thread - however 2206 // only if there is no thread death exception installed already. 2207 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2208 // If the topmost frame is a runtime stub, then we are calling into 2209 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2210 // must deoptimize the caller before continuing, as the compiled exception handler table 2211 // may not be valid 2212 if (has_last_Java_frame()) { 2213 frame f = last_frame(); 2214 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2215 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2216 RegisterMap reg_map(this, UseBiasedLocking); 2217 frame compiled_frame = f.sender(®_map); 2218 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2219 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2220 } 2221 } 2222 } 2223 2224 // Set async. pending exception in thread. 2225 set_pending_async_exception(java_throwable); 2226 2227 if (log_is_enabled(Info, exceptions)) { 2228 ResourceMark rm; 2229 log_info(exceptions)("Pending Async. exception installed of type: %s", 2230 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2231 } 2232 // for AbortVMOnException flag 2233 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2234 } 2235 } 2236 2237 2238 // Interrupt thread so it will wake up from a potential wait() 2239 Thread::interrupt(this); 2240 } 2241 2242 // External suspension mechanism. 2243 // 2244 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2245 // to any VM_locks and it is at a transition 2246 // Self-suspension will happen on the transition out of the vm. 2247 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2248 // 2249 // Guarantees on return: 2250 // + Target thread will not execute any new bytecode (that's why we need to 2251 // force a safepoint) 2252 // + Target thread will not enter any new monitors 2253 // 2254 void JavaThread::java_suspend() { 2255 { MutexLocker mu(Threads_lock); 2256 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2257 return; 2258 } 2259 } 2260 2261 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2262 if (!is_external_suspend()) { 2263 // a racing resume has cancelled us; bail out now 2264 return; 2265 } 2266 2267 // suspend is done 2268 uint32_t debug_bits = 0; 2269 // Warning: is_ext_suspend_completed() may temporarily drop the 2270 // SR_lock to allow the thread to reach a stable thread state if 2271 // it is currently in a transient thread state. 2272 if (is_ext_suspend_completed(false /* !called_by_wait */, 2273 SuspendRetryDelay, &debug_bits)) { 2274 return; 2275 } 2276 } 2277 2278 VM_ThreadSuspend vm_suspend; 2279 VMThread::execute(&vm_suspend); 2280 } 2281 2282 // Part II of external suspension. 2283 // A JavaThread self suspends when it detects a pending external suspend 2284 // request. This is usually on transitions. It is also done in places 2285 // where continuing to the next transition would surprise the caller, 2286 // e.g., monitor entry. 2287 // 2288 // Returns the number of times that the thread self-suspended. 2289 // 2290 // Note: DO NOT call java_suspend_self() when you just want to block current 2291 // thread. java_suspend_self() is the second stage of cooperative 2292 // suspension for external suspend requests and should only be used 2293 // to complete an external suspend request. 2294 // 2295 int JavaThread::java_suspend_self() { 2296 int ret = 0; 2297 2298 // we are in the process of exiting so don't suspend 2299 if (is_exiting()) { 2300 clear_external_suspend(); 2301 return ret; 2302 } 2303 2304 assert(_anchor.walkable() || 2305 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2306 "must have walkable stack"); 2307 2308 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2309 2310 assert(!this->is_ext_suspended(), 2311 "a thread trying to self-suspend should not already be suspended"); 2312 2313 if (this->is_suspend_equivalent()) { 2314 // If we are self-suspending as a result of the lifting of a 2315 // suspend equivalent condition, then the suspend_equivalent 2316 // flag is not cleared until we set the ext_suspended flag so 2317 // that wait_for_ext_suspend_completion() returns consistent 2318 // results. 2319 this->clear_suspend_equivalent(); 2320 } 2321 2322 // A racing resume may have cancelled us before we grabbed SR_lock 2323 // above. Or another external suspend request could be waiting for us 2324 // by the time we return from SR_lock()->wait(). The thread 2325 // that requested the suspension may already be trying to walk our 2326 // stack and if we return now, we can change the stack out from under 2327 // it. This would be a "bad thing (TM)" and cause the stack walker 2328 // to crash. We stay self-suspended until there are no more pending 2329 // external suspend requests. 2330 while (is_external_suspend()) { 2331 ret++; 2332 this->set_ext_suspended(); 2333 2334 // _ext_suspended flag is cleared by java_resume() 2335 while (is_ext_suspended()) { 2336 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2337 } 2338 } 2339 2340 return ret; 2341 } 2342 2343 #ifdef ASSERT 2344 // verify the JavaThread has not yet been published in the Threads::list, and 2345 // hence doesn't need protection from concurrent access at this stage 2346 void JavaThread::verify_not_published() { 2347 if (!Threads_lock->owned_by_self()) { 2348 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2349 assert(!Threads::includes(this), 2350 "java thread shouldn't have been published yet!"); 2351 } else { 2352 assert(!Threads::includes(this), 2353 "java thread shouldn't have been published yet!"); 2354 } 2355 } 2356 #endif 2357 2358 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2359 // progress or when _suspend_flags is non-zero. 2360 // Current thread needs to self-suspend if there is a suspend request and/or 2361 // block if a safepoint is in progress. 2362 // Async exception ISN'T checked. 2363 // Note only the ThreadInVMfromNative transition can call this function 2364 // directly and when thread state is _thread_in_native_trans 2365 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2366 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2367 2368 JavaThread *curJT = JavaThread::current(); 2369 bool do_self_suspend = thread->is_external_suspend(); 2370 2371 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2372 2373 // If JNIEnv proxies are allowed, don't self-suspend if the target 2374 // thread is not the current thread. In older versions of jdbx, jdbx 2375 // threads could call into the VM with another thread's JNIEnv so we 2376 // can be here operating on behalf of a suspended thread (4432884). 2377 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2378 JavaThreadState state = thread->thread_state(); 2379 2380 // We mark this thread_blocked state as a suspend-equivalent so 2381 // that a caller to is_ext_suspend_completed() won't be confused. 2382 // The suspend-equivalent state is cleared by java_suspend_self(). 2383 thread->set_suspend_equivalent(); 2384 2385 // If the safepoint code sees the _thread_in_native_trans state, it will 2386 // wait until the thread changes to other thread state. There is no 2387 // guarantee on how soon we can obtain the SR_lock and complete the 2388 // self-suspend request. It would be a bad idea to let safepoint wait for 2389 // too long. Temporarily change the state to _thread_blocked to 2390 // let the VM thread know that this thread is ready for GC. The problem 2391 // of changing thread state is that safepoint could happen just after 2392 // java_suspend_self() returns after being resumed, and VM thread will 2393 // see the _thread_blocked state. We must check for safepoint 2394 // after restoring the state and make sure we won't leave while a safepoint 2395 // is in progress. 2396 thread->set_thread_state(_thread_blocked); 2397 thread->java_suspend_self(); 2398 thread->set_thread_state(state); 2399 // Make sure new state is seen by VM thread 2400 if (os::is_MP()) { 2401 if (UseMembar) { 2402 // Force a fence between the write above and read below 2403 OrderAccess::fence(); 2404 } else { 2405 // Must use this rather than serialization page in particular on Windows 2406 InterfaceSupport::serialize_memory(thread); 2407 } 2408 } 2409 } 2410 2411 if (SafepointSynchronize::do_call_back()) { 2412 // If we are safepointing, then block the caller which may not be 2413 // the same as the target thread (see above). 2414 SafepointSynchronize::block(curJT); 2415 } 2416 2417 if (thread->is_deopt_suspend()) { 2418 thread->clear_deopt_suspend(); 2419 RegisterMap map(thread, false); 2420 frame f = thread->last_frame(); 2421 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2422 f = f.sender(&map); 2423 } 2424 if (f.id() == thread->must_deopt_id()) { 2425 thread->clear_must_deopt_id(); 2426 f.deoptimize(thread); 2427 } else { 2428 fatal("missed deoptimization!"); 2429 } 2430 } 2431 } 2432 2433 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2434 // progress or when _suspend_flags is non-zero. 2435 // Current thread needs to self-suspend if there is a suspend request and/or 2436 // block if a safepoint is in progress. 2437 // Also check for pending async exception (not including unsafe access error). 2438 // Note only the native==>VM/Java barriers can call this function and when 2439 // thread state is _thread_in_native_trans. 2440 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2441 check_safepoint_and_suspend_for_native_trans(thread); 2442 2443 if (thread->has_async_exception()) { 2444 // We are in _thread_in_native_trans state, don't handle unsafe 2445 // access error since that may block. 2446 thread->check_and_handle_async_exceptions(false); 2447 } 2448 } 2449 2450 // This is a variant of the normal 2451 // check_special_condition_for_native_trans with slightly different 2452 // semantics for use by critical native wrappers. It does all the 2453 // normal checks but also performs the transition back into 2454 // thread_in_Java state. This is required so that critical natives 2455 // can potentially block and perform a GC if they are the last thread 2456 // exiting the GCLocker. 2457 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2458 check_special_condition_for_native_trans(thread); 2459 2460 // Finish the transition 2461 thread->set_thread_state(_thread_in_Java); 2462 2463 if (thread->do_critical_native_unlock()) { 2464 ThreadInVMfromJavaNoAsyncException tiv(thread); 2465 GCLocker::unlock_critical(thread); 2466 thread->clear_critical_native_unlock(); 2467 } 2468 } 2469 2470 // We need to guarantee the Threads_lock here, since resumes are not 2471 // allowed during safepoint synchronization 2472 // Can only resume from an external suspension 2473 void JavaThread::java_resume() { 2474 assert_locked_or_safepoint(Threads_lock); 2475 2476 // Sanity check: thread is gone, has started exiting or the thread 2477 // was not externally suspended. 2478 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2479 return; 2480 } 2481 2482 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2483 2484 clear_external_suspend(); 2485 2486 if (is_ext_suspended()) { 2487 clear_ext_suspended(); 2488 SR_lock()->notify_all(); 2489 } 2490 } 2491 2492 size_t JavaThread::_stack_red_zone_size = 0; 2493 size_t JavaThread::_stack_yellow_zone_size = 0; 2494 size_t JavaThread::_stack_reserved_zone_size = 0; 2495 size_t JavaThread::_stack_shadow_zone_size = 0; 2496 2497 void JavaThread::create_stack_guard_pages() { 2498 if (!os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) { return; } 2499 address low_addr = stack_end(); 2500 size_t len = stack_guard_zone_size(); 2501 2502 int must_commit = os::must_commit_stack_guard_pages(); 2503 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2504 2505 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2506 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2507 return; 2508 } 2509 2510 if (os::guard_memory((char *) low_addr, len)) { 2511 _stack_guard_state = stack_guard_enabled; 2512 } else { 2513 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2514 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2515 if (os::uncommit_memory((char *) low_addr, len)) { 2516 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2517 } 2518 return; 2519 } 2520 2521 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2522 PTR_FORMAT "-" PTR_FORMAT ".", 2523 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2524 } 2525 2526 void JavaThread::remove_stack_guard_pages() { 2527 assert(Thread::current() == this, "from different thread"); 2528 if (_stack_guard_state == stack_guard_unused) return; 2529 address low_addr = stack_end(); 2530 size_t len = stack_guard_zone_size(); 2531 2532 if (os::must_commit_stack_guard_pages()) { 2533 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2534 _stack_guard_state = stack_guard_unused; 2535 } else { 2536 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2537 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2538 return; 2539 } 2540 } else { 2541 if (_stack_guard_state == stack_guard_unused) return; 2542 if (os::unguard_memory((char *) low_addr, len)) { 2543 _stack_guard_state = stack_guard_unused; 2544 } else { 2545 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2546 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2547 return; 2548 } 2549 } 2550 2551 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2552 PTR_FORMAT "-" PTR_FORMAT ".", 2553 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2554 } 2555 2556 void JavaThread::enable_stack_reserved_zone() { 2557 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2558 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2559 2560 // The base notation is from the stack's point of view, growing downward. 2561 // We need to adjust it to work correctly with guard_memory() 2562 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2563 2564 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2565 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2566 2567 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2568 _stack_guard_state = stack_guard_enabled; 2569 } else { 2570 warning("Attempt to guard stack reserved zone failed."); 2571 } 2572 enable_register_stack_guard(); 2573 } 2574 2575 void JavaThread::disable_stack_reserved_zone() { 2576 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2577 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2578 2579 // Simply return if called for a thread that does not use guard pages. 2580 if (_stack_guard_state == stack_guard_unused) return; 2581 2582 // The base notation is from the stack's point of view, growing downward. 2583 // We need to adjust it to work correctly with guard_memory() 2584 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2585 2586 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2587 _stack_guard_state = stack_guard_reserved_disabled; 2588 } else { 2589 warning("Attempt to unguard stack reserved zone failed."); 2590 } 2591 disable_register_stack_guard(); 2592 } 2593 2594 void JavaThread::enable_stack_yellow_reserved_zone() { 2595 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2596 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2597 2598 // The base notation is from the stacks point of view, growing downward. 2599 // We need to adjust it to work correctly with guard_memory() 2600 address base = stack_red_zone_base(); 2601 2602 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2603 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2604 2605 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2606 _stack_guard_state = stack_guard_enabled; 2607 } else { 2608 warning("Attempt to guard stack yellow zone failed."); 2609 } 2610 enable_register_stack_guard(); 2611 } 2612 2613 void JavaThread::disable_stack_yellow_reserved_zone() { 2614 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2615 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2616 2617 // Simply return if called for a thread that does not use guard pages. 2618 if (_stack_guard_state == stack_guard_unused) return; 2619 2620 // The base notation is from the stacks point of view, growing downward. 2621 // We need to adjust it to work correctly with guard_memory() 2622 address base = stack_red_zone_base(); 2623 2624 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2625 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2626 } else { 2627 warning("Attempt to unguard stack yellow zone failed."); 2628 } 2629 disable_register_stack_guard(); 2630 } 2631 2632 void JavaThread::enable_stack_red_zone() { 2633 // The base notation is from the stacks point of view, growing downward. 2634 // We need to adjust it to work correctly with guard_memory() 2635 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2636 address base = stack_red_zone_base() - stack_red_zone_size(); 2637 2638 guarantee(base < stack_base(), "Error calculating stack red zone"); 2639 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2640 2641 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2642 warning("Attempt to guard stack red zone failed."); 2643 } 2644 } 2645 2646 void JavaThread::disable_stack_red_zone() { 2647 // The base notation is from the stacks point of view, growing downward. 2648 // We need to adjust it to work correctly with guard_memory() 2649 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2650 address base = stack_red_zone_base() - stack_red_zone_size(); 2651 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2652 warning("Attempt to unguard stack red zone failed."); 2653 } 2654 } 2655 2656 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2657 // ignore is there is no stack 2658 if (!has_last_Java_frame()) return; 2659 // traverse the stack frames. Starts from top frame. 2660 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2661 frame* fr = fst.current(); 2662 f(fr, fst.register_map()); 2663 } 2664 } 2665 2666 2667 #ifndef PRODUCT 2668 // Deoptimization 2669 // Function for testing deoptimization 2670 void JavaThread::deoptimize() { 2671 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2672 StackFrameStream fst(this, UseBiasedLocking); 2673 bool deopt = false; // Dump stack only if a deopt actually happens. 2674 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2675 // Iterate over all frames in the thread and deoptimize 2676 for (; !fst.is_done(); fst.next()) { 2677 if (fst.current()->can_be_deoptimized()) { 2678 2679 if (only_at) { 2680 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2681 // consists of comma or carriage return separated numbers so 2682 // search for the current bci in that string. 2683 address pc = fst.current()->pc(); 2684 nmethod* nm = (nmethod*) fst.current()->cb(); 2685 ScopeDesc* sd = nm->scope_desc_at(pc); 2686 char buffer[8]; 2687 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2688 size_t len = strlen(buffer); 2689 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2690 while (found != NULL) { 2691 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2692 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2693 // Check that the bci found is bracketed by terminators. 2694 break; 2695 } 2696 found = strstr(found + 1, buffer); 2697 } 2698 if (!found) { 2699 continue; 2700 } 2701 } 2702 2703 if (DebugDeoptimization && !deopt) { 2704 deopt = true; // One-time only print before deopt 2705 tty->print_cr("[BEFORE Deoptimization]"); 2706 trace_frames(); 2707 trace_stack(); 2708 } 2709 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2710 } 2711 } 2712 2713 if (DebugDeoptimization && deopt) { 2714 tty->print_cr("[AFTER Deoptimization]"); 2715 trace_frames(); 2716 } 2717 } 2718 2719 2720 // Make zombies 2721 void JavaThread::make_zombies() { 2722 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2723 if (fst.current()->can_be_deoptimized()) { 2724 // it is a Java nmethod 2725 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2726 nm->make_not_entrant(); 2727 } 2728 } 2729 } 2730 #endif // PRODUCT 2731 2732 2733 void JavaThread::deoptimized_wrt_marked_nmethods() { 2734 if (!has_last_Java_frame()) return; 2735 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2736 StackFrameStream fst(this, UseBiasedLocking); 2737 for (; !fst.is_done(); fst.next()) { 2738 if (fst.current()->should_be_deoptimized()) { 2739 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2740 } 2741 } 2742 } 2743 2744 2745 // If the caller is a NamedThread, then remember, in the current scope, 2746 // the given JavaThread in its _processed_thread field. 2747 class RememberProcessedThread: public StackObj { 2748 NamedThread* _cur_thr; 2749 public: 2750 RememberProcessedThread(JavaThread* jthr) { 2751 Thread* thread = Thread::current(); 2752 if (thread->is_Named_thread()) { 2753 _cur_thr = (NamedThread *)thread; 2754 _cur_thr->set_processed_thread(jthr); 2755 } else { 2756 _cur_thr = NULL; 2757 } 2758 } 2759 2760 ~RememberProcessedThread() { 2761 if (_cur_thr) { 2762 _cur_thr->set_processed_thread(NULL); 2763 } 2764 } 2765 }; 2766 2767 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2768 // Verify that the deferred card marks have been flushed. 2769 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2770 2771 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2772 // since there may be more than one thread using each ThreadProfiler. 2773 2774 // Traverse the GCHandles 2775 Thread::oops_do(f, cf); 2776 2777 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2778 2779 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2780 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2781 2782 if (has_last_Java_frame()) { 2783 // Record JavaThread to GC thread 2784 RememberProcessedThread rpt(this); 2785 2786 // Traverse the privileged stack 2787 if (_privileged_stack_top != NULL) { 2788 _privileged_stack_top->oops_do(f); 2789 } 2790 2791 // traverse the registered growable array 2792 if (_array_for_gc != NULL) { 2793 for (int index = 0; index < _array_for_gc->length(); index++) { 2794 f->do_oop(_array_for_gc->adr_at(index)); 2795 } 2796 } 2797 2798 // Traverse the monitor chunks 2799 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2800 chunk->oops_do(f); 2801 } 2802 2803 // Traverse the execution stack 2804 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2805 fst.current()->oops_do(f, cf, fst.register_map()); 2806 } 2807 } 2808 2809 // callee_target is never live across a gc point so NULL it here should 2810 // it still contain a methdOop. 2811 2812 set_callee_target(NULL); 2813 2814 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2815 // If we have deferred set_locals there might be oops waiting to be 2816 // written 2817 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2818 if (list != NULL) { 2819 for (int i = 0; i < list->length(); i++) { 2820 list->at(i)->oops_do(f); 2821 } 2822 } 2823 2824 // Traverse instance variables at the end since the GC may be moving things 2825 // around using this function 2826 f->do_oop((oop*) &_threadObj); 2827 f->do_oop((oop*) &_vm_result); 2828 f->do_oop((oop*) &_exception_oop); 2829 f->do_oop((oop*) &_pending_async_exception); 2830 2831 if (jvmti_thread_state() != NULL) { 2832 jvmti_thread_state()->oops_do(f); 2833 } 2834 } 2835 2836 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2837 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2838 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2839 2840 if (has_last_Java_frame()) { 2841 // Traverse the execution stack 2842 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2843 fst.current()->nmethods_do(cf); 2844 } 2845 } 2846 } 2847 2848 void JavaThread::metadata_do(void f(Metadata*)) { 2849 if (has_last_Java_frame()) { 2850 // Traverse the execution stack to call f() on the methods in the stack 2851 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2852 fst.current()->metadata_do(f); 2853 } 2854 } else if (is_Compiler_thread()) { 2855 // need to walk ciMetadata in current compile tasks to keep alive. 2856 CompilerThread* ct = (CompilerThread*)this; 2857 if (ct->env() != NULL) { 2858 ct->env()->metadata_do(f); 2859 } 2860 if (ct->task() != NULL) { 2861 ct->task()->metadata_do(f); 2862 } 2863 } 2864 } 2865 2866 // Printing 2867 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2868 switch (_thread_state) { 2869 case _thread_uninitialized: return "_thread_uninitialized"; 2870 case _thread_new: return "_thread_new"; 2871 case _thread_new_trans: return "_thread_new_trans"; 2872 case _thread_in_native: return "_thread_in_native"; 2873 case _thread_in_native_trans: return "_thread_in_native_trans"; 2874 case _thread_in_vm: return "_thread_in_vm"; 2875 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2876 case _thread_in_Java: return "_thread_in_Java"; 2877 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2878 case _thread_blocked: return "_thread_blocked"; 2879 case _thread_blocked_trans: return "_thread_blocked_trans"; 2880 default: return "unknown thread state"; 2881 } 2882 } 2883 2884 #ifndef PRODUCT 2885 void JavaThread::print_thread_state_on(outputStream *st) const { 2886 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2887 }; 2888 void JavaThread::print_thread_state() const { 2889 print_thread_state_on(tty); 2890 } 2891 #endif // PRODUCT 2892 2893 // Called by Threads::print() for VM_PrintThreads operation 2894 void JavaThread::print_on(outputStream *st) const { 2895 st->print_raw("\""); 2896 st->print_raw(get_thread_name()); 2897 st->print_raw("\" "); 2898 oop thread_oop = threadObj(); 2899 if (thread_oop != NULL) { 2900 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); 2901 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2902 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2903 } 2904 Thread::print_on(st); 2905 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2906 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2907 if (thread_oop != NULL) { 2908 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2909 } 2910 #ifndef PRODUCT 2911 print_thread_state_on(st); 2912 _safepoint_state->print_on(st); 2913 #endif // PRODUCT 2914 if (is_Compiler_thread()) { 2915 CompilerThread* ct = (CompilerThread*)this; 2916 if (ct->task() != NULL) { 2917 st->print(" Compiling: "); 2918 ct->task()->print(st, NULL, true, false); 2919 } else { 2920 st->print(" No compile task"); 2921 } 2922 st->cr(); 2923 } 2924 } 2925 2926 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2927 st->print("%s", get_thread_name_string(buf, buflen)); 2928 } 2929 2930 // Called by fatal error handler. The difference between this and 2931 // JavaThread::print() is that we can't grab lock or allocate memory. 2932 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2933 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2934 oop thread_obj = threadObj(); 2935 if (thread_obj != NULL) { 2936 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2937 } 2938 st->print(" ["); 2939 st->print("%s", _get_thread_state_name(_thread_state)); 2940 if (osthread()) { 2941 st->print(", id=%d", osthread()->thread_id()); 2942 } 2943 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2944 p2i(stack_end()), p2i(stack_base())); 2945 st->print("]"); 2946 return; 2947 } 2948 2949 // Verification 2950 2951 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2952 2953 void JavaThread::verify() { 2954 // Verify oops in the thread. 2955 oops_do(&VerifyOopClosure::verify_oop, NULL); 2956 2957 // Verify the stack frames. 2958 frames_do(frame_verify); 2959 } 2960 2961 // CR 6300358 (sub-CR 2137150) 2962 // Most callers of this method assume that it can't return NULL but a 2963 // thread may not have a name whilst it is in the process of attaching to 2964 // the VM - see CR 6412693, and there are places where a JavaThread can be 2965 // seen prior to having it's threadObj set (eg JNI attaching threads and 2966 // if vm exit occurs during initialization). These cases can all be accounted 2967 // for such that this method never returns NULL. 2968 const char* JavaThread::get_thread_name() const { 2969 #ifdef ASSERT 2970 // early safepoints can hit while current thread does not yet have TLS 2971 if (!SafepointSynchronize::is_at_safepoint()) { 2972 Thread *cur = Thread::current(); 2973 if (!(cur->is_Java_thread() && cur == this)) { 2974 // Current JavaThreads are allowed to get their own name without 2975 // the Threads_lock. 2976 assert_locked_or_safepoint(Threads_lock); 2977 } 2978 } 2979 #endif // ASSERT 2980 return get_thread_name_string(); 2981 } 2982 2983 // Returns a non-NULL representation of this thread's name, or a suitable 2984 // descriptive string if there is no set name 2985 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2986 const char* name_str; 2987 oop thread_obj = threadObj(); 2988 if (thread_obj != NULL) { 2989 oop name = java_lang_Thread::name(thread_obj); 2990 if (name != NULL) { 2991 if (buf == NULL) { 2992 name_str = java_lang_String::as_utf8_string(name); 2993 } else { 2994 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 2995 } 2996 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 2997 name_str = "<no-name - thread is attaching>"; 2998 } else { 2999 name_str = Thread::name(); 3000 } 3001 } else { 3002 name_str = Thread::name(); 3003 } 3004 assert(name_str != NULL, "unexpected NULL thread name"); 3005 return name_str; 3006 } 3007 3008 3009 const char* JavaThread::get_threadgroup_name() const { 3010 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3011 oop thread_obj = threadObj(); 3012 if (thread_obj != NULL) { 3013 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3014 if (thread_group != NULL) { 3015 // ThreadGroup.name can be null 3016 return java_lang_ThreadGroup::name(thread_group); 3017 } 3018 } 3019 return NULL; 3020 } 3021 3022 const char* JavaThread::get_parent_name() const { 3023 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3024 oop thread_obj = threadObj(); 3025 if (thread_obj != NULL) { 3026 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3027 if (thread_group != NULL) { 3028 oop parent = java_lang_ThreadGroup::parent(thread_group); 3029 if (parent != NULL) { 3030 // ThreadGroup.name can be null 3031 return java_lang_ThreadGroup::name(parent); 3032 } 3033 } 3034 } 3035 return NULL; 3036 } 3037 3038 ThreadPriority JavaThread::java_priority() const { 3039 oop thr_oop = threadObj(); 3040 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3041 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3042 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3043 return priority; 3044 } 3045 3046 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3047 3048 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3049 // Link Java Thread object <-> C++ Thread 3050 3051 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3052 // and put it into a new Handle. The Handle "thread_oop" can then 3053 // be used to pass the C++ thread object to other methods. 3054 3055 // Set the Java level thread object (jthread) field of the 3056 // new thread (a JavaThread *) to C++ thread object using the 3057 // "thread_oop" handle. 3058 3059 // Set the thread field (a JavaThread *) of the 3060 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3061 3062 Handle thread_oop(Thread::current(), 3063 JNIHandles::resolve_non_null(jni_thread)); 3064 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3065 "must be initialized"); 3066 set_threadObj(thread_oop()); 3067 java_lang_Thread::set_thread(thread_oop(), this); 3068 3069 if (prio == NoPriority) { 3070 prio = java_lang_Thread::priority(thread_oop()); 3071 assert(prio != NoPriority, "A valid priority should be present"); 3072 } 3073 3074 // Push the Java priority down to the native thread; needs Threads_lock 3075 Thread::set_priority(this, prio); 3076 3077 prepare_ext(); 3078 3079 // Add the new thread to the Threads list and set it in motion. 3080 // We must have threads lock in order to call Threads::add. 3081 // It is crucial that we do not block before the thread is 3082 // added to the Threads list for if a GC happens, then the java_thread oop 3083 // will not be visited by GC. 3084 Threads::add(this); 3085 } 3086 3087 oop JavaThread::current_park_blocker() { 3088 // Support for JSR-166 locks 3089 oop thread_oop = threadObj(); 3090 if (thread_oop != NULL && 3091 JDK_Version::current().supports_thread_park_blocker()) { 3092 return java_lang_Thread::park_blocker(thread_oop); 3093 } 3094 return NULL; 3095 } 3096 3097 3098 void JavaThread::print_stack_on(outputStream* st) { 3099 if (!has_last_Java_frame()) return; 3100 ResourceMark rm; 3101 HandleMark hm; 3102 3103 RegisterMap reg_map(this); 3104 vframe* start_vf = last_java_vframe(®_map); 3105 int count = 0; 3106 for (vframe* f = start_vf; f; f = f->sender()) { 3107 if (f->is_java_frame()) { 3108 javaVFrame* jvf = javaVFrame::cast(f); 3109 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3110 3111 // Print out lock information 3112 if (JavaMonitorsInStackTrace) { 3113 jvf->print_lock_info_on(st, count); 3114 } 3115 } else { 3116 // Ignore non-Java frames 3117 } 3118 3119 // Bail-out case for too deep stacks 3120 count++; 3121 if (MaxJavaStackTraceDepth == count) return; 3122 } 3123 } 3124 3125 3126 // JVMTI PopFrame support 3127 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3128 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3129 if (in_bytes(size_in_bytes) != 0) { 3130 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3131 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3132 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3133 } 3134 } 3135 3136 void* JavaThread::popframe_preserved_args() { 3137 return _popframe_preserved_args; 3138 } 3139 3140 ByteSize JavaThread::popframe_preserved_args_size() { 3141 return in_ByteSize(_popframe_preserved_args_size); 3142 } 3143 3144 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3145 int sz = in_bytes(popframe_preserved_args_size()); 3146 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3147 return in_WordSize(sz / wordSize); 3148 } 3149 3150 void JavaThread::popframe_free_preserved_args() { 3151 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3152 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3153 _popframe_preserved_args = NULL; 3154 _popframe_preserved_args_size = 0; 3155 } 3156 3157 #ifndef PRODUCT 3158 3159 void JavaThread::trace_frames() { 3160 tty->print_cr("[Describe stack]"); 3161 int frame_no = 1; 3162 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3163 tty->print(" %d. ", frame_no++); 3164 fst.current()->print_value_on(tty, this); 3165 tty->cr(); 3166 } 3167 } 3168 3169 class PrintAndVerifyOopClosure: public OopClosure { 3170 protected: 3171 template <class T> inline void do_oop_work(T* p) { 3172 oop obj = oopDesc::load_decode_heap_oop(p); 3173 if (obj == NULL) return; 3174 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3175 if (obj->is_oop_or_null()) { 3176 if (obj->is_objArray()) { 3177 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3178 } else { 3179 obj->print(); 3180 } 3181 } else { 3182 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3183 } 3184 tty->cr(); 3185 } 3186 public: 3187 virtual void do_oop(oop* p) { do_oop_work(p); } 3188 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3189 }; 3190 3191 3192 static void oops_print(frame* f, const RegisterMap *map) { 3193 PrintAndVerifyOopClosure print; 3194 f->print_value(); 3195 f->oops_do(&print, NULL, (RegisterMap*)map); 3196 } 3197 3198 // Print our all the locations that contain oops and whether they are 3199 // valid or not. This useful when trying to find the oldest frame 3200 // where an oop has gone bad since the frame walk is from youngest to 3201 // oldest. 3202 void JavaThread::trace_oops() { 3203 tty->print_cr("[Trace oops]"); 3204 frames_do(oops_print); 3205 } 3206 3207 3208 #ifdef ASSERT 3209 // Print or validate the layout of stack frames 3210 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3211 ResourceMark rm; 3212 PRESERVE_EXCEPTION_MARK; 3213 FrameValues values; 3214 int frame_no = 0; 3215 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3216 fst.current()->describe(values, ++frame_no); 3217 if (depth == frame_no) break; 3218 } 3219 if (validate_only) { 3220 values.validate(); 3221 } else { 3222 tty->print_cr("[Describe stack layout]"); 3223 values.print(this); 3224 } 3225 } 3226 #endif 3227 3228 void JavaThread::trace_stack_from(vframe* start_vf) { 3229 ResourceMark rm; 3230 int vframe_no = 1; 3231 for (vframe* f = start_vf; f; f = f->sender()) { 3232 if (f->is_java_frame()) { 3233 javaVFrame::cast(f)->print_activation(vframe_no++); 3234 } else { 3235 f->print(); 3236 } 3237 if (vframe_no > StackPrintLimit) { 3238 tty->print_cr("...<more frames>..."); 3239 return; 3240 } 3241 } 3242 } 3243 3244 3245 void JavaThread::trace_stack() { 3246 if (!has_last_Java_frame()) return; 3247 ResourceMark rm; 3248 HandleMark hm; 3249 RegisterMap reg_map(this); 3250 trace_stack_from(last_java_vframe(®_map)); 3251 } 3252 3253 3254 #endif // PRODUCT 3255 3256 3257 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3258 assert(reg_map != NULL, "a map must be given"); 3259 frame f = last_frame(); 3260 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3261 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3262 } 3263 return NULL; 3264 } 3265 3266 3267 Klass* JavaThread::security_get_caller_class(int depth) { 3268 vframeStream vfst(this); 3269 vfst.security_get_caller_frame(depth); 3270 if (!vfst.at_end()) { 3271 return vfst.method()->method_holder(); 3272 } 3273 return NULL; 3274 } 3275 3276 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3277 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3278 CompileBroker::compiler_thread_loop(); 3279 } 3280 3281 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3282 NMethodSweeper::sweeper_loop(); 3283 } 3284 3285 // Create a CompilerThread 3286 CompilerThread::CompilerThread(CompileQueue* queue, 3287 CompilerCounters* counters) 3288 : JavaThread(&compiler_thread_entry) { 3289 _env = NULL; 3290 _log = NULL; 3291 _task = NULL; 3292 _queue = queue; 3293 _counters = counters; 3294 _buffer_blob = NULL; 3295 _compiler = NULL; 3296 3297 #ifndef PRODUCT 3298 _ideal_graph_printer = NULL; 3299 #endif 3300 } 3301 3302 bool CompilerThread::can_call_java() const { 3303 return _compiler != NULL && _compiler->is_jvmci(); 3304 } 3305 3306 // Create sweeper thread 3307 CodeCacheSweeperThread::CodeCacheSweeperThread() 3308 : JavaThread(&sweeper_thread_entry) { 3309 _scanned_compiled_method = NULL; 3310 } 3311 3312 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3313 JavaThread::oops_do(f, cf); 3314 if (_scanned_compiled_method != NULL && cf != NULL) { 3315 // Safepoints can occur when the sweeper is scanning an nmethod so 3316 // process it here to make sure it isn't unloaded in the middle of 3317 // a scan. 3318 cf->do_code_blob(_scanned_compiled_method); 3319 } 3320 } 3321 3322 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3323 JavaThread::nmethods_do(cf); 3324 if (_scanned_compiled_method != NULL && cf != NULL) { 3325 // Safepoints can occur when the sweeper is scanning an nmethod so 3326 // process it here to make sure it isn't unloaded in the middle of 3327 // a scan. 3328 cf->do_code_blob(_scanned_compiled_method); 3329 } 3330 } 3331 3332 3333 // ======= Threads ======== 3334 3335 // The Threads class links together all active threads, and provides 3336 // operations over all threads. It is protected by its own Mutex 3337 // lock, which is also used in other contexts to protect thread 3338 // operations from having the thread being operated on from exiting 3339 // and going away unexpectedly (e.g., safepoint synchronization) 3340 3341 JavaThread* Threads::_thread_list = NULL; 3342 int Threads::_number_of_threads = 0; 3343 int Threads::_number_of_non_daemon_threads = 0; 3344 int Threads::_return_code = 0; 3345 int Threads::_thread_claim_parity = 0; 3346 size_t JavaThread::_stack_size_at_create = 0; 3347 #ifdef ASSERT 3348 bool Threads::_vm_complete = false; 3349 #endif 3350 3351 // All JavaThreads 3352 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 3353 3354 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3355 void Threads::threads_do(ThreadClosure* tc) { 3356 assert_locked_or_safepoint(Threads_lock); 3357 // ALL_JAVA_THREADS iterates through all JavaThreads 3358 ALL_JAVA_THREADS(p) { 3359 tc->do_thread(p); 3360 } 3361 // Someday we could have a table or list of all non-JavaThreads. 3362 // For now, just manually iterate through them. 3363 tc->do_thread(VMThread::vm_thread()); 3364 Universe::heap()->gc_threads_do(tc); 3365 WatcherThread *wt = WatcherThread::watcher_thread(); 3366 // Strictly speaking, the following NULL check isn't sufficient to make sure 3367 // the data for WatcherThread is still valid upon being examined. However, 3368 // considering that WatchThread terminates when the VM is on the way to 3369 // exit at safepoint, the chance of the above is extremely small. The right 3370 // way to prevent termination of WatcherThread would be to acquire 3371 // Terminator_lock, but we can't do that without violating the lock rank 3372 // checking in some cases. 3373 if (wt != NULL) { 3374 tc->do_thread(wt); 3375 } 3376 3377 // If CompilerThreads ever become non-JavaThreads, add them here 3378 } 3379 3380 // The system initialization in the library has three phases. 3381 // 3382 // Phase 1: java.lang.System class initialization 3383 // java.lang.System is a primordial class loaded and initialized 3384 // by the VM early during startup. java.lang.System.<clinit> 3385 // only does registerNatives and keeps the rest of the class 3386 // initialization work later until thread initialization completes. 3387 // 3388 // System.initPhase1 initializes the system properties, the static 3389 // fields in, out, and err. Set up java signal handlers, OS-specific 3390 // system settings, and thread group of the main thread. 3391 static void call_initPhase1(TRAPS) { 3392 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3393 JavaValue result(T_VOID); 3394 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3395 vmSymbols::void_method_signature(), CHECK); 3396 } 3397 3398 // Phase 2. Module system initialization 3399 // This will initialize the module system. Only java.base classes 3400 // can be loaded until phase 2 completes. 3401 // 3402 // Call System.initPhase2 after the compiler initialization and jsr292 3403 // classes get initialized because module initialization runs a lot of java 3404 // code, that for performance reasons, should be compiled. Also, this will 3405 // enable the startup code to use lambda and other language features in this 3406 // phase and onward. 3407 // 3408 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3409 static void call_initPhase2(TRAPS) { 3410 TraceTime timer("Phase2 initialization", TRACETIME_LOG(Info, module, startuptime)); 3411 3412 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3413 3414 JavaValue result(T_INT); 3415 JavaCallArguments args; 3416 args.push_int(DisplayVMOutputToStderr); 3417 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3418 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3419 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3420 if (result.get_jint() != JNI_OK) { 3421 vm_exit_during_initialization(); // no message or exception 3422 } 3423 3424 universe_post_module_init(); 3425 } 3426 3427 // Phase 3. final setup - set security manager, system class loader and TCCL 3428 // 3429 // This will instantiate and set the security manager, set the system class 3430 // loader as well as the thread context class loader. The security manager 3431 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3432 // other modules or the application's classpath. 3433 static void call_initPhase3(TRAPS) { 3434 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3435 JavaValue result(T_VOID); 3436 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3437 vmSymbols::void_method_signature(), CHECK); 3438 } 3439 3440 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3441 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3442 3443 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3444 create_vm_init_libraries(); 3445 } 3446 3447 initialize_class(vmSymbols::java_lang_String(), CHECK); 3448 3449 // Inject CompactStrings value after the static initializers for String ran. 3450 java_lang_String::set_compact_strings(CompactStrings); 3451 3452 // Initialize java_lang.System (needed before creating the thread) 3453 initialize_class(vmSymbols::java_lang_System(), CHECK); 3454 // The VM creates & returns objects of this class. Make sure it's initialized. 3455 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3456 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3457 Handle thread_group = create_initial_thread_group(CHECK); 3458 Universe::set_main_thread_group(thread_group()); 3459 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3460 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3461 main_thread->set_threadObj(thread_object); 3462 // Set thread status to running since main thread has 3463 // been started and running. 3464 java_lang_Thread::set_thread_status(thread_object, 3465 java_lang_Thread::RUNNABLE); 3466 3467 // The VM creates objects of this class. 3468 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3469 3470 // The VM preresolves methods to these classes. Make sure that they get initialized 3471 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3472 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3473 3474 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3475 call_initPhase1(CHECK); 3476 3477 // get the Java runtime name after java.lang.System is initialized 3478 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3479 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3480 3481 // an instance of OutOfMemory exception has been allocated earlier 3482 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3483 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3484 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3485 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3486 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3487 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3488 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3489 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3490 } 3491 3492 void Threads::initialize_jsr292_core_classes(TRAPS) { 3493 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3494 3495 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3496 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3497 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3498 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3499 } 3500 3501 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3502 extern void JDK_Version_init(); 3503 3504 // Preinitialize version info. 3505 VM_Version::early_initialize(); 3506 3507 // Check version 3508 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3509 3510 // Initialize library-based TLS 3511 ThreadLocalStorage::init(); 3512 3513 // Initialize the output stream module 3514 ostream_init(); 3515 3516 // Process java launcher properties. 3517 Arguments::process_sun_java_launcher_properties(args); 3518 3519 // Initialize the os module 3520 os::init(); 3521 3522 // Record VM creation timing statistics 3523 TraceVmCreationTime create_vm_timer; 3524 create_vm_timer.start(); 3525 3526 // Initialize system properties. 3527 Arguments::init_system_properties(); 3528 3529 // So that JDK version can be used as a discriminator when parsing arguments 3530 JDK_Version_init(); 3531 3532 // Update/Initialize System properties after JDK version number is known 3533 Arguments::init_version_specific_system_properties(); 3534 3535 // Make sure to initialize log configuration *before* parsing arguments 3536 LogConfiguration::initialize(create_vm_timer.begin_time()); 3537 3538 // Parse arguments 3539 jint parse_result = Arguments::parse(args); 3540 if (parse_result != JNI_OK) return parse_result; 3541 3542 os::init_before_ergo(); 3543 3544 jint ergo_result = Arguments::apply_ergo(); 3545 if (ergo_result != JNI_OK) return ergo_result; 3546 3547 // Final check of all ranges after ergonomics which may change values. 3548 if (!CommandLineFlagRangeList::check_ranges()) { 3549 return JNI_EINVAL; 3550 } 3551 3552 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3553 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3554 if (!constraint_result) { 3555 return JNI_EINVAL; 3556 } 3557 3558 CommandLineFlagWriteableList::mark_startup(); 3559 3560 if (PauseAtStartup) { 3561 os::pause(); 3562 } 3563 3564 HOTSPOT_VM_INIT_BEGIN(); 3565 3566 // Timing (must come after argument parsing) 3567 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3568 3569 // Initialize the os module after parsing the args 3570 jint os_init_2_result = os::init_2(); 3571 if (os_init_2_result != JNI_OK) return os_init_2_result; 3572 3573 jint adjust_after_os_result = Arguments::adjust_after_os(); 3574 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3575 3576 // Initialize output stream logging 3577 ostream_init_log(); 3578 3579 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3580 // Must be before create_vm_init_agents() 3581 if (Arguments::init_libraries_at_startup()) { 3582 convert_vm_init_libraries_to_agents(); 3583 } 3584 3585 // Launch -agentlib/-agentpath and converted -Xrun agents 3586 if (Arguments::init_agents_at_startup()) { 3587 create_vm_init_agents(); 3588 } 3589 3590 // Initialize Threads state 3591 _thread_list = NULL; 3592 _number_of_threads = 0; 3593 _number_of_non_daemon_threads = 0; 3594 3595 // Initialize global data structures and create system classes in heap 3596 vm_init_globals(); 3597 3598 #if INCLUDE_JVMCI 3599 if (JVMCICounterSize > 0) { 3600 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3601 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3602 } else { 3603 JavaThread::_jvmci_old_thread_counters = NULL; 3604 } 3605 #endif // INCLUDE_JVMCI 3606 3607 // Attach the main thread to this os thread 3608 JavaThread* main_thread = new JavaThread(); 3609 main_thread->set_thread_state(_thread_in_vm); 3610 main_thread->initialize_thread_current(); 3611 // must do this before set_active_handles 3612 main_thread->record_stack_base_and_size(); 3613 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3614 3615 if (!main_thread->set_as_starting_thread()) { 3616 vm_shutdown_during_initialization( 3617 "Failed necessary internal allocation. Out of swap space"); 3618 delete main_thread; 3619 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3620 return JNI_ENOMEM; 3621 } 3622 3623 // Enable guard page *after* os::create_main_thread(), otherwise it would 3624 // crash Linux VM, see notes in os_linux.cpp. 3625 main_thread->create_stack_guard_pages(); 3626 3627 // Initialize Java-Level synchronization subsystem 3628 ObjectMonitor::Initialize(); 3629 3630 // Initialize global modules 3631 jint status = init_globals(); 3632 if (status != JNI_OK) { 3633 delete main_thread; 3634 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3635 return status; 3636 } 3637 3638 if (TRACE_INITIALIZE() != JNI_OK) { 3639 vm_exit_during_initialization("Failed to initialize tracing backend"); 3640 } 3641 3642 // Should be done after the heap is fully created 3643 main_thread->cache_global_variables(); 3644 3645 HandleMark hm; 3646 3647 { MutexLocker mu(Threads_lock); 3648 Threads::add(main_thread); 3649 } 3650 3651 // Any JVMTI raw monitors entered in onload will transition into 3652 // real raw monitor. VM is setup enough here for raw monitor enter. 3653 JvmtiExport::transition_pending_onload_raw_monitors(); 3654 3655 // Create the VMThread 3656 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3657 3658 VMThread::create(); 3659 Thread* vmthread = VMThread::vm_thread(); 3660 3661 if (!os::create_thread(vmthread, os::vm_thread)) { 3662 vm_exit_during_initialization("Cannot create VM thread. " 3663 "Out of system resources."); 3664 } 3665 3666 // Wait for the VM thread to become ready, and VMThread::run to initialize 3667 // Monitors can have spurious returns, must always check another state flag 3668 { 3669 MutexLocker ml(Notify_lock); 3670 os::start_thread(vmthread); 3671 while (vmthread->active_handles() == NULL) { 3672 Notify_lock->wait(); 3673 } 3674 } 3675 } 3676 3677 assert(Universe::is_fully_initialized(), "not initialized"); 3678 if (VerifyDuringStartup) { 3679 // Make sure we're starting with a clean slate. 3680 VM_Verify verify_op; 3681 VMThread::execute(&verify_op); 3682 } 3683 3684 Thread* THREAD = Thread::current(); 3685 3686 // At this point, the Universe is initialized, but we have not executed 3687 // any byte code. Now is a good time (the only time) to dump out the 3688 // internal state of the JVM for sharing. 3689 if (DumpSharedSpaces) { 3690 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3691 ShouldNotReachHere(); 3692 } 3693 3694 // Always call even when there are not JVMTI environments yet, since environments 3695 // may be attached late and JVMTI must track phases of VM execution 3696 JvmtiExport::enter_early_start_phase(); 3697 3698 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3699 JvmtiExport::post_early_vm_start(); 3700 3701 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3702 3703 // We need this for ClassDataSharing - the initial vm.info property is set 3704 // with the default value of CDS "sharing" which may be reset through 3705 // command line options. 3706 reset_vm_info_property(CHECK_JNI_ERR); 3707 3708 quicken_jni_functions(); 3709 3710 // No more stub generation allowed after that point. 3711 StubCodeDesc::freeze(); 3712 3713 // Set flag that basic initialization has completed. Used by exceptions and various 3714 // debug stuff, that does not work until all basic classes have been initialized. 3715 set_init_completed(); 3716 3717 LogConfiguration::post_initialize(); 3718 Metaspace::post_initialize(); 3719 3720 HOTSPOT_VM_INIT_END(); 3721 3722 // record VM initialization completion time 3723 #if INCLUDE_MANAGEMENT 3724 Management::record_vm_init_completed(); 3725 #endif // INCLUDE_MANAGEMENT 3726 3727 // Signal Dispatcher needs to be started before VMInit event is posted 3728 os::signal_init(CHECK_JNI_ERR); 3729 3730 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3731 if (!DisableAttachMechanism) { 3732 AttachListener::vm_start(); 3733 if (StartAttachListener || AttachListener::init_at_startup()) { 3734 AttachListener::init(); 3735 } 3736 } 3737 3738 // Launch -Xrun agents 3739 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3740 // back-end can launch with -Xdebug -Xrunjdwp. 3741 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3742 create_vm_init_libraries(); 3743 } 3744 3745 if (CleanChunkPoolAsync) { 3746 Chunk::start_chunk_pool_cleaner_task(); 3747 } 3748 3749 // initialize compiler(s) 3750 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) || INCLUDE_JVMCI 3751 CompileBroker::compilation_init(CHECK_JNI_ERR); 3752 #endif 3753 3754 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3755 // It is done after compilers are initialized, because otherwise compilations of 3756 // signature polymorphic MH intrinsics can be missed 3757 // (see SystemDictionary::find_method_handle_intrinsic). 3758 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3759 3760 // This will initialize the module system. Only java.base classes can be 3761 // loaded until phase 2 completes 3762 call_initPhase2(CHECK_JNI_ERR); 3763 3764 // Always call even when there are not JVMTI environments yet, since environments 3765 // may be attached late and JVMTI must track phases of VM execution 3766 JvmtiExport::enter_start_phase(); 3767 3768 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3769 JvmtiExport::post_vm_start(); 3770 3771 // Final system initialization including security manager and system class loader 3772 call_initPhase3(CHECK_JNI_ERR); 3773 3774 // cache the system class loader 3775 SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR)); 3776 3777 #if INCLUDE_JVMCI 3778 if (EnableJVMCI) { 3779 // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled. 3780 // The JVMCI Java initialization code will read this flag and 3781 // do the printing if it's set. 3782 bool init = JVMCIPrintProperties; 3783 3784 if (!init) { 3785 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3786 // compilations via JVMCI will not actually block until JVMCI is initialized. 3787 init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3788 } 3789 3790 if (init) { 3791 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3792 } 3793 } 3794 #endif 3795 3796 // Always call even when there are not JVMTI environments yet, since environments 3797 // may be attached late and JVMTI must track phases of VM execution 3798 JvmtiExport::enter_live_phase(); 3799 3800 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3801 JvmtiExport::post_vm_initialized(); 3802 3803 if (TRACE_START() != JNI_OK) { 3804 vm_exit_during_initialization("Failed to start tracing backend."); 3805 } 3806 3807 #if INCLUDE_MANAGEMENT 3808 Management::initialize(THREAD); 3809 3810 if (HAS_PENDING_EXCEPTION) { 3811 // management agent fails to start possibly due to 3812 // configuration problem and is responsible for printing 3813 // stack trace if appropriate. Simply exit VM. 3814 vm_exit(1); 3815 } 3816 #endif // INCLUDE_MANAGEMENT 3817 3818 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3819 if (MemProfiling) MemProfiler::engage(); 3820 StatSampler::engage(); 3821 if (CheckJNICalls) JniPeriodicChecker::engage(); 3822 3823 BiasedLocking::init(); 3824 3825 #if INCLUDE_RTM_OPT 3826 RTMLockingCounters::init(); 3827 #endif 3828 3829 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3830 call_postVMInitHook(THREAD); 3831 // The Java side of PostVMInitHook.run must deal with all 3832 // exceptions and provide means of diagnosis. 3833 if (HAS_PENDING_EXCEPTION) { 3834 CLEAR_PENDING_EXCEPTION; 3835 } 3836 } 3837 3838 { 3839 MutexLocker ml(PeriodicTask_lock); 3840 // Make sure the WatcherThread can be started by WatcherThread::start() 3841 // or by dynamic enrollment. 3842 WatcherThread::make_startable(); 3843 // Start up the WatcherThread if there are any periodic tasks 3844 // NOTE: All PeriodicTasks should be registered by now. If they 3845 // aren't, late joiners might appear to start slowly (we might 3846 // take a while to process their first tick). 3847 if (PeriodicTask::num_tasks() > 0) { 3848 WatcherThread::start(); 3849 } 3850 } 3851 3852 create_vm_timer.end(); 3853 #ifdef ASSERT 3854 _vm_complete = true; 3855 #endif 3856 return JNI_OK; 3857 } 3858 3859 // type for the Agent_OnLoad and JVM_OnLoad entry points 3860 extern "C" { 3861 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3862 } 3863 // Find a command line agent library and return its entry point for 3864 // -agentlib: -agentpath: -Xrun 3865 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3866 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3867 const char *on_load_symbols[], 3868 size_t num_symbol_entries) { 3869 OnLoadEntry_t on_load_entry = NULL; 3870 void *library = NULL; 3871 3872 if (!agent->valid()) { 3873 char buffer[JVM_MAXPATHLEN]; 3874 char ebuf[1024] = ""; 3875 const char *name = agent->name(); 3876 const char *msg = "Could not find agent library "; 3877 3878 // First check to see if agent is statically linked into executable 3879 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3880 library = agent->os_lib(); 3881 } else if (agent->is_absolute_path()) { 3882 library = os::dll_load(name, ebuf, sizeof ebuf); 3883 if (library == NULL) { 3884 const char *sub_msg = " in absolute path, with error: "; 3885 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3886 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3887 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3888 // If we can't find the agent, exit. 3889 vm_exit_during_initialization(buf, NULL); 3890 FREE_C_HEAP_ARRAY(char, buf); 3891 } 3892 } else { 3893 // Try to load the agent from the standard dll directory 3894 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), 3895 name)) { 3896 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3897 } 3898 if (library == NULL) { // Try the local directory 3899 char ns[1] = {0}; 3900 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { 3901 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3902 } 3903 if (library == NULL) { 3904 const char *sub_msg = " on the library path, with error: "; 3905 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3906 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3907 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3908 // If we can't find the agent, exit. 3909 vm_exit_during_initialization(buf, NULL); 3910 FREE_C_HEAP_ARRAY(char, buf); 3911 } 3912 } 3913 } 3914 agent->set_os_lib(library); 3915 agent->set_valid(); 3916 } 3917 3918 // Find the OnLoad function. 3919 on_load_entry = 3920 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 3921 false, 3922 on_load_symbols, 3923 num_symbol_entries)); 3924 return on_load_entry; 3925 } 3926 3927 // Find the JVM_OnLoad entry point 3928 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3929 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3930 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3931 } 3932 3933 // Find the Agent_OnLoad entry point 3934 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3935 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3936 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3937 } 3938 3939 // For backwards compatibility with -Xrun 3940 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3941 // treated like -agentpath: 3942 // Must be called before agent libraries are created 3943 void Threads::convert_vm_init_libraries_to_agents() { 3944 AgentLibrary* agent; 3945 AgentLibrary* next; 3946 3947 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3948 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3949 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3950 3951 // If there is an JVM_OnLoad function it will get called later, 3952 // otherwise see if there is an Agent_OnLoad 3953 if (on_load_entry == NULL) { 3954 on_load_entry = lookup_agent_on_load(agent); 3955 if (on_load_entry != NULL) { 3956 // switch it to the agent list -- so that Agent_OnLoad will be called, 3957 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3958 Arguments::convert_library_to_agent(agent); 3959 } else { 3960 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3961 } 3962 } 3963 } 3964 } 3965 3966 // Create agents for -agentlib: -agentpath: and converted -Xrun 3967 // Invokes Agent_OnLoad 3968 // Called very early -- before JavaThreads exist 3969 void Threads::create_vm_init_agents() { 3970 extern struct JavaVM_ main_vm; 3971 AgentLibrary* agent; 3972 3973 JvmtiExport::enter_onload_phase(); 3974 3975 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3976 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3977 3978 if (on_load_entry != NULL) { 3979 // Invoke the Agent_OnLoad function 3980 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3981 if (err != JNI_OK) { 3982 vm_exit_during_initialization("agent library failed to init", agent->name()); 3983 } 3984 } else { 3985 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3986 } 3987 } 3988 JvmtiExport::enter_primordial_phase(); 3989 } 3990 3991 extern "C" { 3992 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3993 } 3994 3995 void Threads::shutdown_vm_agents() { 3996 // Send any Agent_OnUnload notifications 3997 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3998 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 3999 extern struct JavaVM_ main_vm; 4000 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4001 4002 // Find the Agent_OnUnload function. 4003 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4004 os::find_agent_function(agent, 4005 false, 4006 on_unload_symbols, 4007 num_symbol_entries)); 4008 4009 // Invoke the Agent_OnUnload function 4010 if (unload_entry != NULL) { 4011 JavaThread* thread = JavaThread::current(); 4012 ThreadToNativeFromVM ttn(thread); 4013 HandleMark hm(thread); 4014 (*unload_entry)(&main_vm); 4015 } 4016 } 4017 } 4018 4019 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4020 // Invokes JVM_OnLoad 4021 void Threads::create_vm_init_libraries() { 4022 extern struct JavaVM_ main_vm; 4023 AgentLibrary* agent; 4024 4025 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4026 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4027 4028 if (on_load_entry != NULL) { 4029 // Invoke the JVM_OnLoad function 4030 JavaThread* thread = JavaThread::current(); 4031 ThreadToNativeFromVM ttn(thread); 4032 HandleMark hm(thread); 4033 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4034 if (err != JNI_OK) { 4035 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4036 } 4037 } else { 4038 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4039 } 4040 } 4041 } 4042 4043 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { 4044 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); 4045 4046 JavaThread* java_thread = NULL; 4047 // Sequential search for now. Need to do better optimization later. 4048 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { 4049 oop tobj = thread->threadObj(); 4050 if (!thread->is_exiting() && 4051 tobj != NULL && 4052 java_tid == java_lang_Thread::thread_id(tobj)) { 4053 java_thread = thread; 4054 break; 4055 } 4056 } 4057 return java_thread; 4058 } 4059 4060 4061 // Last thread running calls java.lang.Shutdown.shutdown() 4062 void JavaThread::invoke_shutdown_hooks() { 4063 HandleMark hm(this); 4064 4065 // We could get here with a pending exception, if so clear it now. 4066 if (this->has_pending_exception()) { 4067 this->clear_pending_exception(); 4068 } 4069 4070 EXCEPTION_MARK; 4071 Klass* shutdown_klass = 4072 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4073 THREAD); 4074 if (shutdown_klass != NULL) { 4075 // SystemDictionary::resolve_or_null will return null if there was 4076 // an exception. If we cannot load the Shutdown class, just don't 4077 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4078 // and finalizers (if runFinalizersOnExit is set) won't be run. 4079 // Note that if a shutdown hook was registered or runFinalizersOnExit 4080 // was called, the Shutdown class would have already been loaded 4081 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 4082 JavaValue result(T_VOID); 4083 JavaCalls::call_static(&result, 4084 shutdown_klass, 4085 vmSymbols::shutdown_method_name(), 4086 vmSymbols::void_method_signature(), 4087 THREAD); 4088 } 4089 CLEAR_PENDING_EXCEPTION; 4090 } 4091 4092 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4093 // the program falls off the end of main(). Another VM exit path is through 4094 // vm_exit() when the program calls System.exit() to return a value or when 4095 // there is a serious error in VM. The two shutdown paths are not exactly 4096 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4097 // and VM_Exit op at VM level. 4098 // 4099 // Shutdown sequence: 4100 // + Shutdown native memory tracking if it is on 4101 // + Wait until we are the last non-daemon thread to execute 4102 // <-- every thing is still working at this moment --> 4103 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4104 // shutdown hooks, run finalizers if finalization-on-exit 4105 // + Call before_exit(), prepare for VM exit 4106 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4107 // currently the only user of this mechanism is File.deleteOnExit()) 4108 // > stop flat profiler, StatSampler, watcher thread, CMS threads, 4109 // post thread end and vm death events to JVMTI, 4110 // stop signal thread 4111 // + Call JavaThread::exit(), it will: 4112 // > release JNI handle blocks, remove stack guard pages 4113 // > remove this thread from Threads list 4114 // <-- no more Java code from this thread after this point --> 4115 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4116 // the compiler threads at safepoint 4117 // <-- do not use anything that could get blocked by Safepoint --> 4118 // + Disable tracing at JNI/JVM barriers 4119 // + Set _vm_exited flag for threads that are still running native code 4120 // + Delete this thread 4121 // + Call exit_globals() 4122 // > deletes tty 4123 // > deletes PerfMemory resources 4124 // + Return to caller 4125 4126 bool Threads::destroy_vm() { 4127 JavaThread* thread = JavaThread::current(); 4128 4129 #ifdef ASSERT 4130 _vm_complete = false; 4131 #endif 4132 // Wait until we are the last non-daemon thread to execute 4133 { MutexLocker nu(Threads_lock); 4134 while (Threads::number_of_non_daemon_threads() > 1) 4135 // This wait should make safepoint checks, wait without a timeout, 4136 // and wait as a suspend-equivalent condition. 4137 // 4138 // Note: If the FlatProfiler is running and this thread is waiting 4139 // for another non-daemon thread to finish, then the FlatProfiler 4140 // is waiting for the external suspend request on this thread to 4141 // complete. wait_for_ext_suspend_completion() will eventually 4142 // timeout, but that takes time. Making this wait a suspend- 4143 // equivalent condition solves that timeout problem. 4144 // 4145 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4146 Mutex::_as_suspend_equivalent_flag); 4147 } 4148 4149 // Hang forever on exit if we are reporting an error. 4150 if (ShowMessageBoxOnError && is_error_reported()) { 4151 os::infinite_sleep(); 4152 } 4153 os::wait_for_keypress_at_exit(); 4154 4155 // run Java level shutdown hooks 4156 thread->invoke_shutdown_hooks(); 4157 4158 before_exit(thread); 4159 4160 thread->exit(true); 4161 4162 // Stop VM thread. 4163 { 4164 // 4945125 The vm thread comes to a safepoint during exit. 4165 // GC vm_operations can get caught at the safepoint, and the 4166 // heap is unparseable if they are caught. Grab the Heap_lock 4167 // to prevent this. The GC vm_operations will not be able to 4168 // queue until after the vm thread is dead. After this point, 4169 // we'll never emerge out of the safepoint before the VM exits. 4170 4171 MutexLocker ml(Heap_lock); 4172 4173 VMThread::wait_for_vm_thread_exit(); 4174 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4175 VMThread::destroy(); 4176 } 4177 4178 // clean up ideal graph printers 4179 #if defined(COMPILER2) && !defined(PRODUCT) 4180 IdealGraphPrinter::clean_up(); 4181 #endif 4182 4183 // Now, all Java threads are gone except daemon threads. Daemon threads 4184 // running Java code or in VM are stopped by the Safepoint. However, 4185 // daemon threads executing native code are still running. But they 4186 // will be stopped at native=>Java/VM barriers. Note that we can't 4187 // simply kill or suspend them, as it is inherently deadlock-prone. 4188 4189 VM_Exit::set_vm_exited(); 4190 4191 notify_vm_shutdown(); 4192 4193 delete thread; 4194 4195 #if INCLUDE_JVMCI 4196 if (JVMCICounterSize > 0) { 4197 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4198 } 4199 #endif 4200 4201 // exit_globals() will delete tty 4202 exit_globals(); 4203 4204 LogConfiguration::finalize(); 4205 4206 return true; 4207 } 4208 4209 4210 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4211 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4212 return is_supported_jni_version(version); 4213 } 4214 4215 4216 jboolean Threads::is_supported_jni_version(jint version) { 4217 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4218 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4219 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4220 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4221 if (version == JNI_VERSION_9) return JNI_TRUE; 4222 return JNI_FALSE; 4223 } 4224 4225 4226 void Threads::add(JavaThread* p, bool force_daemon) { 4227 // The threads lock must be owned at this point 4228 assert_locked_or_safepoint(Threads_lock); 4229 4230 // See the comment for this method in thread.hpp for its purpose and 4231 // why it is called here. 4232 p->initialize_queues(); 4233 p->set_next(_thread_list); 4234 _thread_list = p; 4235 _number_of_threads++; 4236 oop threadObj = p->threadObj(); 4237 bool daemon = true; 4238 // Bootstrapping problem: threadObj can be null for initial 4239 // JavaThread (or for threads attached via JNI) 4240 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4241 _number_of_non_daemon_threads++; 4242 daemon = false; 4243 } 4244 4245 ThreadService::add_thread(p, daemon); 4246 4247 // Possible GC point. 4248 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4249 } 4250 4251 void Threads::remove(JavaThread* p) { 4252 4253 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4254 ObjectSynchronizer::omFlush(p); 4255 4256 // Extra scope needed for Thread_lock, so we can check 4257 // that we do not remove thread without safepoint code notice 4258 { MutexLocker ml(Threads_lock); 4259 4260 assert(includes(p), "p must be present"); 4261 4262 JavaThread* current = _thread_list; 4263 JavaThread* prev = NULL; 4264 4265 while (current != p) { 4266 prev = current; 4267 current = current->next(); 4268 } 4269 4270 if (prev) { 4271 prev->set_next(current->next()); 4272 } else { 4273 _thread_list = p->next(); 4274 } 4275 _number_of_threads--; 4276 oop threadObj = p->threadObj(); 4277 bool daemon = true; 4278 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4279 _number_of_non_daemon_threads--; 4280 daemon = false; 4281 4282 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4283 // on destroy_vm will wake up. 4284 if (number_of_non_daemon_threads() == 1) { 4285 Threads_lock->notify_all(); 4286 } 4287 } 4288 ThreadService::remove_thread(p, daemon); 4289 4290 // Make sure that safepoint code disregard this thread. This is needed since 4291 // the thread might mess around with locks after this point. This can cause it 4292 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4293 // of this thread since it is removed from the queue. 4294 p->set_terminated_value(); 4295 } // unlock Threads_lock 4296 4297 // Since Events::log uses a lock, we grab it outside the Threads_lock 4298 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4299 } 4300 4301 // Threads_lock must be held when this is called (or must be called during a safepoint) 4302 bool Threads::includes(JavaThread* p) { 4303 assert(Threads_lock->is_locked(), "sanity check"); 4304 ALL_JAVA_THREADS(q) { 4305 if (q == p) { 4306 return true; 4307 } 4308 } 4309 return false; 4310 } 4311 4312 // Operations on the Threads list for GC. These are not explicitly locked, 4313 // but the garbage collector must provide a safe context for them to run. 4314 // In particular, these things should never be called when the Threads_lock 4315 // is held by some other thread. (Note: the Safepoint abstraction also 4316 // uses the Threads_lock to guarantee this property. It also makes sure that 4317 // all threads gets blocked when exiting or starting). 4318 4319 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4320 ALL_JAVA_THREADS(p) { 4321 p->oops_do(f, cf); 4322 } 4323 VMThread::vm_thread()->oops_do(f, cf); 4324 } 4325 4326 void Threads::change_thread_claim_parity() { 4327 // Set the new claim parity. 4328 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4329 "Not in range."); 4330 _thread_claim_parity++; 4331 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4332 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4333 "Not in range."); 4334 } 4335 4336 #ifdef ASSERT 4337 void Threads::assert_all_threads_claimed() { 4338 ALL_JAVA_THREADS(p) { 4339 const int thread_parity = p->oops_do_parity(); 4340 assert((thread_parity == _thread_claim_parity), 4341 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4342 } 4343 } 4344 #endif // ASSERT 4345 4346 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4347 int cp = Threads::thread_claim_parity(); 4348 ALL_JAVA_THREADS(p) { 4349 if (p->claim_oops_do(is_par, cp)) { 4350 p->oops_do(f, cf); 4351 } 4352 } 4353 VMThread* vmt = VMThread::vm_thread(); 4354 if (vmt->claim_oops_do(is_par, cp)) { 4355 vmt->oops_do(f, cf); 4356 } 4357 } 4358 4359 #if INCLUDE_ALL_GCS 4360 // Used by ParallelScavenge 4361 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4362 ALL_JAVA_THREADS(p) { 4363 q->enqueue(new ThreadRootsTask(p)); 4364 } 4365 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4366 } 4367 4368 // Used by Parallel Old 4369 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4370 ALL_JAVA_THREADS(p) { 4371 q->enqueue(new ThreadRootsMarkingTask(p)); 4372 } 4373 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4374 } 4375 #endif // INCLUDE_ALL_GCS 4376 4377 void Threads::nmethods_do(CodeBlobClosure* cf) { 4378 ALL_JAVA_THREADS(p) { 4379 // This is used by the code cache sweeper to mark nmethods that are active 4380 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4381 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4382 if(!p->is_Code_cache_sweeper_thread()) { 4383 p->nmethods_do(cf); 4384 } 4385 } 4386 } 4387 4388 void Threads::metadata_do(void f(Metadata*)) { 4389 ALL_JAVA_THREADS(p) { 4390 p->metadata_do(f); 4391 } 4392 } 4393 4394 class ThreadHandlesClosure : public ThreadClosure { 4395 void (*_f)(Metadata*); 4396 public: 4397 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4398 virtual void do_thread(Thread* thread) { 4399 thread->metadata_handles_do(_f); 4400 } 4401 }; 4402 4403 void Threads::metadata_handles_do(void f(Metadata*)) { 4404 // Only walk the Handles in Thread. 4405 ThreadHandlesClosure handles_closure(f); 4406 threads_do(&handles_closure); 4407 } 4408 4409 void Threads::deoptimized_wrt_marked_nmethods() { 4410 ALL_JAVA_THREADS(p) { 4411 p->deoptimized_wrt_marked_nmethods(); 4412 } 4413 } 4414 4415 4416 // Get count Java threads that are waiting to enter the specified monitor. 4417 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 4418 address monitor, 4419 bool doLock) { 4420 assert(doLock || SafepointSynchronize::is_at_safepoint(), 4421 "must grab Threads_lock or be at safepoint"); 4422 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4423 4424 int i = 0; 4425 { 4426 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4427 ALL_JAVA_THREADS(p) { 4428 if (!p->can_call_java()) continue; 4429 4430 address pending = (address)p->current_pending_monitor(); 4431 if (pending == monitor) { // found a match 4432 if (i < count) result->append(p); // save the first count matches 4433 i++; 4434 } 4435 } 4436 } 4437 return result; 4438 } 4439 4440 4441 JavaThread *Threads::owning_thread_from_monitor_owner(address owner, 4442 bool doLock) { 4443 assert(doLock || 4444 Threads_lock->owned_by_self() || 4445 SafepointSynchronize::is_at_safepoint(), 4446 "must grab Threads_lock or be at safepoint"); 4447 4448 // NULL owner means not locked so we can skip the search 4449 if (owner == NULL) return NULL; 4450 4451 { 4452 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4453 ALL_JAVA_THREADS(p) { 4454 // first, see if owner is the address of a Java thread 4455 if (owner == (address)p) return p; 4456 } 4457 } 4458 // Cannot assert on lack of success here since this function may be 4459 // used by code that is trying to report useful problem information 4460 // like deadlock detection. 4461 if (UseHeavyMonitors) return NULL; 4462 4463 // If we didn't find a matching Java thread and we didn't force use of 4464 // heavyweight monitors, then the owner is the stack address of the 4465 // Lock Word in the owning Java thread's stack. 4466 // 4467 JavaThread* the_owner = NULL; 4468 { 4469 MutexLockerEx ml(doLock ? Threads_lock : NULL); 4470 ALL_JAVA_THREADS(q) { 4471 if (q->is_lock_owned(owner)) { 4472 the_owner = q; 4473 break; 4474 } 4475 } 4476 } 4477 // cannot assert on lack of success here; see above comment 4478 return the_owner; 4479 } 4480 4481 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4482 void Threads::print_on(outputStream* st, bool print_stacks, 4483 bool internal_format, bool print_concurrent_locks) { 4484 char buf[32]; 4485 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4486 4487 st->print_cr("Full thread dump %s (%s %s):", 4488 Abstract_VM_Version::vm_name(), 4489 Abstract_VM_Version::vm_release(), 4490 Abstract_VM_Version::vm_info_string()); 4491 st->cr(); 4492 4493 #if INCLUDE_SERVICES 4494 // Dump concurrent locks 4495 ConcurrentLocksDump concurrent_locks; 4496 if (print_concurrent_locks) { 4497 concurrent_locks.dump_at_safepoint(); 4498 } 4499 #endif // INCLUDE_SERVICES 4500 4501 ALL_JAVA_THREADS(p) { 4502 ResourceMark rm; 4503 p->print_on(st); 4504 if (print_stacks) { 4505 if (internal_format) { 4506 p->trace_stack(); 4507 } else { 4508 p->print_stack_on(st); 4509 } 4510 } 4511 st->cr(); 4512 #if INCLUDE_SERVICES 4513 if (print_concurrent_locks) { 4514 concurrent_locks.print_locks_on(p, st); 4515 } 4516 #endif // INCLUDE_SERVICES 4517 } 4518 4519 VMThread::vm_thread()->print_on(st); 4520 st->cr(); 4521 Universe::heap()->print_gc_threads_on(st); 4522 WatcherThread* wt = WatcherThread::watcher_thread(); 4523 if (wt != NULL) { 4524 wt->print_on(st); 4525 st->cr(); 4526 } 4527 st->flush(); 4528 } 4529 4530 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4531 int buflen, bool* found_current) { 4532 if (this_thread != NULL) { 4533 bool is_current = (current == this_thread); 4534 *found_current = *found_current || is_current; 4535 st->print("%s", is_current ? "=>" : " "); 4536 4537 st->print(PTR_FORMAT, p2i(this_thread)); 4538 st->print(" "); 4539 this_thread->print_on_error(st, buf, buflen); 4540 st->cr(); 4541 } 4542 } 4543 4544 class PrintOnErrorClosure : public ThreadClosure { 4545 outputStream* _st; 4546 Thread* _current; 4547 char* _buf; 4548 int _buflen; 4549 bool* _found_current; 4550 public: 4551 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4552 int buflen, bool* found_current) : 4553 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4554 4555 virtual void do_thread(Thread* thread) { 4556 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4557 } 4558 }; 4559 4560 // Threads::print_on_error() is called by fatal error handler. It's possible 4561 // that VM is not at safepoint and/or current thread is inside signal handler. 4562 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4563 // memory (even in resource area), it might deadlock the error handler. 4564 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4565 int buflen) { 4566 bool found_current = false; 4567 st->print_cr("Java Threads: ( => current thread )"); 4568 ALL_JAVA_THREADS(thread) { 4569 print_on_error(thread, st, current, buf, buflen, &found_current); 4570 } 4571 st->cr(); 4572 4573 st->print_cr("Other Threads:"); 4574 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4575 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4576 4577 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4578 Universe::heap()->gc_threads_do(&print_closure); 4579 4580 if (!found_current) { 4581 st->cr(); 4582 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4583 current->print_on_error(st, buf, buflen); 4584 st->cr(); 4585 } 4586 st->cr(); 4587 st->print_cr("Threads with active compile tasks:"); 4588 print_threads_compiling(st, buf, buflen); 4589 } 4590 4591 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4592 ALL_JAVA_THREADS(thread) { 4593 if (thread->is_Compiler_thread()) { 4594 CompilerThread* ct = (CompilerThread*) thread; 4595 if (ct->task() != NULL) { 4596 thread->print_name_on_error(st, buf, buflen); 4597 ct->task()->print(st, NULL, true, true); 4598 } 4599 } 4600 } 4601 } 4602 4603 4604 // Internal SpinLock and Mutex 4605 // Based on ParkEvent 4606 4607 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4608 // 4609 // We employ SpinLocks _only for low-contention, fixed-length 4610 // short-duration critical sections where we're concerned 4611 // about native mutex_t or HotSpot Mutex:: latency. 4612 // The mux construct provides a spin-then-block mutual exclusion 4613 // mechanism. 4614 // 4615 // Testing has shown that contention on the ListLock guarding gFreeList 4616 // is common. If we implement ListLock as a simple SpinLock it's common 4617 // for the JVM to devolve to yielding with little progress. This is true 4618 // despite the fact that the critical sections protected by ListLock are 4619 // extremely short. 4620 // 4621 // TODO-FIXME: ListLock should be of type SpinLock. 4622 // We should make this a 1st-class type, integrated into the lock 4623 // hierarchy as leaf-locks. Critically, the SpinLock structure 4624 // should have sufficient padding to avoid false-sharing and excessive 4625 // cache-coherency traffic. 4626 4627 4628 typedef volatile int SpinLockT; 4629 4630 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4631 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4632 return; // normal fast-path return 4633 } 4634 4635 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4636 TEVENT(SpinAcquire - ctx); 4637 int ctr = 0; 4638 int Yields = 0; 4639 for (;;) { 4640 while (*adr != 0) { 4641 ++ctr; 4642 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4643 if (Yields > 5) { 4644 os::naked_short_sleep(1); 4645 } else { 4646 os::naked_yield(); 4647 ++Yields; 4648 } 4649 } else { 4650 SpinPause(); 4651 } 4652 } 4653 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4654 } 4655 } 4656 4657 void Thread::SpinRelease(volatile int * adr) { 4658 assert(*adr != 0, "invariant"); 4659 OrderAccess::fence(); // guarantee at least release consistency. 4660 // Roach-motel semantics. 4661 // It's safe if subsequent LDs and STs float "up" into the critical section, 4662 // but prior LDs and STs within the critical section can't be allowed 4663 // to reorder or float past the ST that releases the lock. 4664 // Loads and stores in the critical section - which appear in program 4665 // order before the store that releases the lock - must also appear 4666 // before the store that releases the lock in memory visibility order. 4667 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4668 // the ST of 0 into the lock-word which releases the lock, so fence 4669 // more than covers this on all platforms. 4670 *adr = 0; 4671 } 4672 4673 // muxAcquire and muxRelease: 4674 // 4675 // * muxAcquire and muxRelease support a single-word lock-word construct. 4676 // The LSB of the word is set IFF the lock is held. 4677 // The remainder of the word points to the head of a singly-linked list 4678 // of threads blocked on the lock. 4679 // 4680 // * The current implementation of muxAcquire-muxRelease uses its own 4681 // dedicated Thread._MuxEvent instance. If we're interested in 4682 // minimizing the peak number of extant ParkEvent instances then 4683 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4684 // as certain invariants were satisfied. Specifically, care would need 4685 // to be taken with regards to consuming unpark() "permits". 4686 // A safe rule of thumb is that a thread would never call muxAcquire() 4687 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4688 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4689 // consume an unpark() permit intended for monitorenter, for instance. 4690 // One way around this would be to widen the restricted-range semaphore 4691 // implemented in park(). Another alternative would be to provide 4692 // multiple instances of the PlatformEvent() for each thread. One 4693 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4694 // 4695 // * Usage: 4696 // -- Only as leaf locks 4697 // -- for short-term locking only as muxAcquire does not perform 4698 // thread state transitions. 4699 // 4700 // Alternatives: 4701 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4702 // but with parking or spin-then-park instead of pure spinning. 4703 // * Use Taura-Oyama-Yonenzawa locks. 4704 // * It's possible to construct a 1-0 lock if we encode the lockword as 4705 // (List,LockByte). Acquire will CAS the full lockword while Release 4706 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4707 // acquiring threads use timers (ParkTimed) to detect and recover from 4708 // the stranding window. Thread/Node structures must be aligned on 256-byte 4709 // boundaries by using placement-new. 4710 // * Augment MCS with advisory back-link fields maintained with CAS(). 4711 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4712 // The validity of the backlinks must be ratified before we trust the value. 4713 // If the backlinks are invalid the exiting thread must back-track through the 4714 // the forward links, which are always trustworthy. 4715 // * Add a successor indication. The LockWord is currently encoded as 4716 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4717 // to provide the usual futile-wakeup optimization. 4718 // See RTStt for details. 4719 // * Consider schedctl.sc_nopreempt to cover the critical section. 4720 // 4721 4722 4723 typedef volatile intptr_t MutexT; // Mux Lock-word 4724 enum MuxBits { LOCKBIT = 1 }; 4725 4726 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4727 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4728 if (w == 0) return; 4729 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4730 return; 4731 } 4732 4733 TEVENT(muxAcquire - Contention); 4734 ParkEvent * const Self = Thread::current()->_MuxEvent; 4735 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4736 for (;;) { 4737 int its = (os::is_MP() ? 100 : 0) + 1; 4738 4739 // Optional spin phase: spin-then-park strategy 4740 while (--its >= 0) { 4741 w = *Lock; 4742 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4743 return; 4744 } 4745 } 4746 4747 Self->reset(); 4748 Self->OnList = intptr_t(Lock); 4749 // The following fence() isn't _strictly necessary as the subsequent 4750 // CAS() both serializes execution and ratifies the fetched *Lock value. 4751 OrderAccess::fence(); 4752 for (;;) { 4753 w = *Lock; 4754 if ((w & LOCKBIT) == 0) { 4755 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4756 Self->OnList = 0; // hygiene - allows stronger asserts 4757 return; 4758 } 4759 continue; // Interference -- *Lock changed -- Just retry 4760 } 4761 assert(w & LOCKBIT, "invariant"); 4762 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4763 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4764 } 4765 4766 while (Self->OnList != 0) { 4767 Self->park(); 4768 } 4769 } 4770 } 4771 4772 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4773 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0); 4774 if (w == 0) return; 4775 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4776 return; 4777 } 4778 4779 TEVENT(muxAcquire - Contention); 4780 ParkEvent * ReleaseAfter = NULL; 4781 if (ev == NULL) { 4782 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4783 } 4784 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4785 for (;;) { 4786 guarantee(ev->OnList == 0, "invariant"); 4787 int its = (os::is_MP() ? 100 : 0) + 1; 4788 4789 // Optional spin phase: spin-then-park strategy 4790 while (--its >= 0) { 4791 w = *Lock; 4792 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4793 if (ReleaseAfter != NULL) { 4794 ParkEvent::Release(ReleaseAfter); 4795 } 4796 return; 4797 } 4798 } 4799 4800 ev->reset(); 4801 ev->OnList = intptr_t(Lock); 4802 // The following fence() isn't _strictly necessary as the subsequent 4803 // CAS() both serializes execution and ratifies the fetched *Lock value. 4804 OrderAccess::fence(); 4805 for (;;) { 4806 w = *Lock; 4807 if ((w & LOCKBIT) == 0) { 4808 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4809 ev->OnList = 0; 4810 // We call ::Release while holding the outer lock, thus 4811 // artificially lengthening the critical section. 4812 // Consider deferring the ::Release() until the subsequent unlock(), 4813 // after we've dropped the outer lock. 4814 if (ReleaseAfter != NULL) { 4815 ParkEvent::Release(ReleaseAfter); 4816 } 4817 return; 4818 } 4819 continue; // Interference -- *Lock changed -- Just retry 4820 } 4821 assert(w & LOCKBIT, "invariant"); 4822 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4823 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4824 } 4825 4826 while (ev->OnList != 0) { 4827 ev->park(); 4828 } 4829 } 4830 } 4831 4832 // Release() must extract a successor from the list and then wake that thread. 4833 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4834 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4835 // Release() would : 4836 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4837 // (B) Extract a successor from the private list "in-hand" 4838 // (C) attempt to CAS() the residual back into *Lock over null. 4839 // If there were any newly arrived threads and the CAS() would fail. 4840 // In that case Release() would detach the RATs, re-merge the list in-hand 4841 // with the RATs and repeat as needed. Alternately, Release() might 4842 // detach and extract a successor, but then pass the residual list to the wakee. 4843 // The wakee would be responsible for reattaching and remerging before it 4844 // competed for the lock. 4845 // 4846 // Both "pop" and DMR are immune from ABA corruption -- there can be 4847 // multiple concurrent pushers, but only one popper or detacher. 4848 // This implementation pops from the head of the list. This is unfair, 4849 // but tends to provide excellent throughput as hot threads remain hot. 4850 // (We wake recently run threads first). 4851 // 4852 // All paths through muxRelease() will execute a CAS. 4853 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4854 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4855 // executed within the critical section are complete and globally visible before the 4856 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4857 void Thread::muxRelease(volatile intptr_t * Lock) { 4858 for (;;) { 4859 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT); 4860 assert(w & LOCKBIT, "invariant"); 4861 if (w == LOCKBIT) return; 4862 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4863 assert(List != NULL, "invariant"); 4864 assert(List->OnList == intptr_t(Lock), "invariant"); 4865 ParkEvent * const nxt = List->ListNext; 4866 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4867 4868 // The following CAS() releases the lock and pops the head element. 4869 // The CAS() also ratifies the previously fetched lock-word value. 4870 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4871 continue; 4872 } 4873 List->OnList = 0; 4874 OrderAccess::fence(); 4875 List->unpark(); 4876 return; 4877 } 4878 } 4879 4880 4881 void Threads::verify() { 4882 ALL_JAVA_THREADS(p) { 4883 p->verify(); 4884 } 4885 VMThread* thread = VMThread::vm_thread(); 4886 if (thread != NULL) thread->verify(); 4887 }