1 /* 2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "jvm.h" 27 #include "classfile/classLoader.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/scopeDesc.hpp" 34 #include "compiler/compileBroker.hpp" 35 #include "compiler/compileTask.hpp" 36 #include "gc/shared/gcId.hpp" 37 #include "gc/shared/gcLocker.inline.hpp" 38 #include "gc/shared/workgroup.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "interpreter/linkResolver.hpp" 41 #include "interpreter/oopMapCache.hpp" 42 #include "jvmtifiles/jvmtiEnv.hpp" 43 #include "logging/log.hpp" 44 #include "logging/logConfiguration.hpp" 45 #include "logging/logStream.hpp" 46 #include "memory/allocation.inline.hpp" 47 #include "memory/metaspaceShared.hpp" 48 #include "memory/oopFactory.hpp" 49 #include "memory/resourceArea.hpp" 50 #include "memory/universe.hpp" 51 #include "oops/access.inline.hpp" 52 #include "oops/instanceKlass.hpp" 53 #include "oops/objArrayOop.hpp" 54 #include "oops/oop.inline.hpp" 55 #include "oops/symbol.hpp" 56 #include "oops/typeArrayOop.inline.hpp" 57 #include "oops/verifyOopClosure.hpp" 58 #include "prims/jvm_misc.hpp" 59 #include "prims/jvmtiExport.hpp" 60 #include "prims/jvmtiThreadState.hpp" 61 #include "prims/privilegedStack.hpp" 62 #include "runtime/arguments.hpp" 63 #include "runtime/atomic.hpp" 64 #include "runtime/biasedLocking.hpp" 65 #include "runtime/commandLineFlagConstraintList.hpp" 66 #include "runtime/commandLineFlagWriteableList.hpp" 67 #include "runtime/commandLineFlagRangeList.hpp" 68 #include "runtime/deoptimization.hpp" 69 #include "runtime/frame.inline.hpp" 70 #include "runtime/globals.hpp" 71 #include "runtime/handshake.hpp" 72 #include "runtime/init.hpp" 73 #include "runtime/interfaceSupport.inline.hpp" 74 #include "runtime/java.hpp" 75 #include "runtime/javaCalls.hpp" 76 #include "runtime/jniHandles.inline.hpp" 77 #include "runtime/jniPeriodicChecker.hpp" 78 #include "runtime/memprofiler.hpp" 79 #include "runtime/mutexLocker.hpp" 80 #include "runtime/objectMonitor.hpp" 81 #include "runtime/orderAccess.inline.hpp" 82 #include "runtime/osThread.hpp" 83 #include "runtime/prefetch.inline.hpp" 84 #include "runtime/safepoint.hpp" 85 #include "runtime/safepointMechanism.inline.hpp" 86 #include "runtime/sharedRuntime.hpp" 87 #include "runtime/statSampler.hpp" 88 #include "runtime/stubRoutines.hpp" 89 #include "runtime/sweeper.hpp" 90 #include "runtime/task.hpp" 91 #include "runtime/thread.inline.hpp" 92 #include "runtime/threadCritical.hpp" 93 #include "runtime/threadSMR.inline.hpp" 94 #include "runtime/timer.hpp" 95 #include "runtime/timerTrace.hpp" 96 #include "runtime/vframe.inline.hpp" 97 #include "runtime/vframeArray.hpp" 98 #include "runtime/vframe_hp.hpp" 99 #include "runtime/vmThread.hpp" 100 #include "runtime/vm_operations.hpp" 101 #include "runtime/vm_version.hpp" 102 #include "services/attachListener.hpp" 103 #include "services/management.hpp" 104 #include "services/memTracker.hpp" 105 #include "services/threadService.hpp" 106 #include "trace/traceMacros.hpp" 107 #include "trace/tracing.hpp" 108 #include "utilities/align.hpp" 109 #include "utilities/defaultStream.hpp" 110 #include "utilities/dtrace.hpp" 111 #include "utilities/events.hpp" 112 #include "utilities/macros.hpp" 113 #include "utilities/preserveException.hpp" 114 #include "utilities/vmError.hpp" 115 #if INCLUDE_ALL_GCS 116 #include "gc/cms/concurrentMarkSweepThread.hpp" 117 #include "gc/g1/concurrentMarkThread.inline.hpp" 118 #include "gc/parallel/pcTasks.hpp" 119 #endif // INCLUDE_ALL_GCS 120 #if INCLUDE_JVMCI 121 #include "jvmci/jvmciCompiler.hpp" 122 #include "jvmci/jvmciRuntime.hpp" 123 #include "logging/logHandle.hpp" 124 #endif 125 #ifdef COMPILER1 126 #include "c1/c1_Compiler.hpp" 127 #endif 128 #ifdef COMPILER2 129 #include "opto/c2compiler.hpp" 130 #include "opto/idealGraphPrinter.hpp" 131 #endif 132 #if INCLUDE_RTM_OPT 133 #include "runtime/rtmLocking.hpp" 134 #endif 135 136 // Initialization after module runtime initialization 137 void universe_post_module_init(); // must happen after call_initPhase2 138 139 #ifdef DTRACE_ENABLED 140 141 // Only bother with this argument setup if dtrace is available 142 143 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START 144 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP 145 146 #define DTRACE_THREAD_PROBE(probe, javathread) \ 147 { \ 148 ResourceMark rm(this); \ 149 int len = 0; \ 150 const char* name = (javathread)->get_thread_name(); \ 151 len = strlen(name); \ 152 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \ 153 (char *) name, len, \ 154 java_lang_Thread::thread_id((javathread)->threadObj()), \ 155 (uintptr_t) (javathread)->osthread()->thread_id(), \ 156 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 157 } 158 159 #else // ndef DTRACE_ENABLED 160 161 #define DTRACE_THREAD_PROBE(probe, javathread) 162 163 #endif // ndef DTRACE_ENABLED 164 165 #ifndef USE_LIBRARY_BASED_TLS_ONLY 166 // Current thread is maintained as a thread-local variable 167 THREAD_LOCAL_DECL Thread* Thread::_thr_current = NULL; 168 #endif 169 // Class hierarchy 170 // - Thread 171 // - VMThread 172 // - WatcherThread 173 // - ConcurrentMarkSweepThread 174 // - JavaThread 175 // - CompilerThread 176 177 // ======= Thread ======== 178 // Support for forcing alignment of thread objects for biased locking 179 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { 180 if (UseBiasedLocking) { 181 const int alignment = markOopDesc::biased_lock_alignment; 182 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 183 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) 184 : AllocateHeap(aligned_size, flags, CURRENT_PC, 185 AllocFailStrategy::RETURN_NULL); 186 void* aligned_addr = align_up(real_malloc_addr, alignment); 187 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 188 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 189 "JavaThread alignment code overflowed allocated storage"); 190 if (aligned_addr != real_malloc_addr) { 191 log_info(biasedlocking)("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 192 p2i(real_malloc_addr), 193 p2i(aligned_addr)); 194 } 195 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 196 return aligned_addr; 197 } else { 198 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) 199 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); 200 } 201 } 202 203 void Thread::operator delete(void* p) { 204 if (UseBiasedLocking) { 205 FreeHeap(((Thread*) p)->_real_malloc_address); 206 } else { 207 FreeHeap(p); 208 } 209 } 210 211 void JavaThread::smr_delete() { 212 if (_on_thread_list) { 213 ThreadsSMRSupport::smr_delete(this); 214 } else { 215 delete this; 216 } 217 } 218 219 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 220 // JavaThread 221 222 223 Thread::Thread() { 224 // stack and get_thread 225 set_stack_base(NULL); 226 set_stack_size(0); 227 set_self_raw_id(0); 228 set_lgrp_id(-1); 229 DEBUG_ONLY(clear_suspendible_thread();) 230 231 // allocated data structures 232 set_osthread(NULL); 233 set_resource_area(new (mtThread)ResourceArea()); 234 DEBUG_ONLY(_current_resource_mark = NULL;) 235 set_handle_area(new (mtThread) HandleArea(NULL)); 236 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true)); 237 set_active_handles(NULL); 238 set_free_handle_block(NULL); 239 set_last_handle_mark(NULL); 240 _heap_sampler.set_thread(this); 241 242 // This initial value ==> never claimed. 243 _oops_do_parity = 0; 244 _threads_hazard_ptr = NULL; 245 _nested_threads_hazard_ptr = NULL; 246 _nested_threads_hazard_ptr_cnt = 0; 247 248 // the handle mark links itself to last_handle_mark 249 new HandleMark(this); 250 251 // plain initialization 252 debug_only(_owned_locks = NULL;) 253 debug_only(_allow_allocation_count = 0;) 254 NOT_PRODUCT(_allow_safepoint_count = 0;) 255 NOT_PRODUCT(_skip_gcalot = false;) 256 _jvmti_env_iteration_count = 0; 257 set_allocated_bytes(0); 258 _vm_operation_started_count = 0; 259 _vm_operation_completed_count = 0; 260 _current_pending_monitor = NULL; 261 _current_pending_monitor_is_from_java = true; 262 _current_waiting_monitor = NULL; 263 _num_nested_signal = 0; 264 omFreeList = NULL; 265 omFreeCount = 0; 266 omFreeProvision = 32; 267 omInUseList = NULL; 268 omInUseCount = 0; 269 270 #ifdef ASSERT 271 _visited_for_critical_count = false; 272 #endif 273 274 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true, 275 Monitor::_safepoint_check_sometimes); 276 _suspend_flags = 0; 277 278 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 279 _hashStateX = os::random(); 280 _hashStateY = 842502087; 281 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ; 282 _hashStateW = 273326509; 283 284 _OnTrap = 0; 285 _schedctl = NULL; 286 _Stalled = 0; 287 _TypeTag = 0x2BAD; 288 289 // Many of the following fields are effectively final - immutable 290 // Note that nascent threads can't use the Native Monitor-Mutex 291 // construct until the _MutexEvent is initialized ... 292 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 293 // we might instead use a stack of ParkEvents that we could provision on-demand. 294 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 295 // and ::Release() 296 _ParkEvent = ParkEvent::Allocate(this); 297 _SleepEvent = ParkEvent::Allocate(this); 298 _MutexEvent = ParkEvent::Allocate(this); 299 _MuxEvent = ParkEvent::Allocate(this); 300 301 #ifdef CHECK_UNHANDLED_OOPS 302 if (CheckUnhandledOops) { 303 _unhandled_oops = new UnhandledOops(this); 304 } 305 #endif // CHECK_UNHANDLED_OOPS 306 #ifdef ASSERT 307 if (UseBiasedLocking) { 308 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 309 assert(this == _real_malloc_address || 310 this == align_up(_real_malloc_address, (int)markOopDesc::biased_lock_alignment), 311 "bug in forced alignment of thread objects"); 312 } 313 #endif // ASSERT 314 } 315 316 void Thread::initialize_thread_current() { 317 #ifndef USE_LIBRARY_BASED_TLS_ONLY 318 assert(_thr_current == NULL, "Thread::current already initialized"); 319 _thr_current = this; 320 #endif 321 assert(ThreadLocalStorage::thread() == NULL, "ThreadLocalStorage::thread already initialized"); 322 ThreadLocalStorage::set_thread(this); 323 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 324 } 325 326 void Thread::clear_thread_current() { 327 assert(Thread::current() == ThreadLocalStorage::thread(), "TLS mismatch!"); 328 #ifndef USE_LIBRARY_BASED_TLS_ONLY 329 _thr_current = NULL; 330 #endif 331 ThreadLocalStorage::set_thread(NULL); 332 } 333 334 void Thread::record_stack_base_and_size() { 335 set_stack_base(os::current_stack_base()); 336 set_stack_size(os::current_stack_size()); 337 // CR 7190089: on Solaris, primordial thread's stack is adjusted 338 // in initialize_thread(). Without the adjustment, stack size is 339 // incorrect if stack is set to unlimited (ulimit -s unlimited). 340 // So far, only Solaris has real implementation of initialize_thread(). 341 // 342 // set up any platform-specific state. 343 os::initialize_thread(this); 344 345 // Set stack limits after thread is initialized. 346 if (is_Java_thread()) { 347 ((JavaThread*) this)->set_stack_overflow_limit(); 348 ((JavaThread*) this)->set_reserved_stack_activation(stack_base()); 349 } 350 #if INCLUDE_NMT 351 // record thread's native stack, stack grows downward 352 MemTracker::record_thread_stack(stack_end(), stack_size()); 353 #endif // INCLUDE_NMT 354 log_debug(os, thread)("Thread " UINTX_FORMAT " stack dimensions: " 355 PTR_FORMAT "-" PTR_FORMAT " (" SIZE_FORMAT "k).", 356 os::current_thread_id(), p2i(stack_base() - stack_size()), 357 p2i(stack_base()), stack_size()/1024); 358 } 359 360 361 Thread::~Thread() { 362 EVENT_THREAD_DESTRUCT(this); 363 364 // stack_base can be NULL if the thread is never started or exited before 365 // record_stack_base_and_size called. Although, we would like to ensure 366 // that all started threads do call record_stack_base_and_size(), there is 367 // not proper way to enforce that. 368 #if INCLUDE_NMT 369 if (_stack_base != NULL) { 370 MemTracker::release_thread_stack(stack_end(), stack_size()); 371 #ifdef ASSERT 372 set_stack_base(NULL); 373 #endif 374 } 375 #endif // INCLUDE_NMT 376 377 // deallocate data structures 378 delete resource_area(); 379 // since the handle marks are using the handle area, we have to deallocated the root 380 // handle mark before deallocating the thread's handle area, 381 assert(last_handle_mark() != NULL, "check we have an element"); 382 delete last_handle_mark(); 383 assert(last_handle_mark() == NULL, "check we have reached the end"); 384 385 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 386 // We NULL out the fields for good hygiene. 387 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL; 388 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL; 389 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL; 390 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL; 391 392 delete handle_area(); 393 delete metadata_handles(); 394 395 // SR_handler uses this as a termination indicator - 396 // needs to happen before os::free_thread() 397 delete _SR_lock; 398 _SR_lock = NULL; 399 400 // osthread() can be NULL, if creation of thread failed. 401 if (osthread() != NULL) os::free_thread(osthread()); 402 403 // clear Thread::current if thread is deleting itself. 404 // Needed to ensure JNI correctly detects non-attached threads. 405 if (this == Thread::current()) { 406 clear_thread_current(); 407 } 408 409 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 410 } 411 412 // NOTE: dummy function for assertion purpose. 413 void Thread::run() { 414 ShouldNotReachHere(); 415 } 416 417 #ifdef ASSERT 418 // A JavaThread is considered "dangling" if it is not the current 419 // thread, has been added the Threads list, the system is not at a 420 // safepoint and the Thread is not "protected". 421 // 422 void Thread::check_for_dangling_thread_pointer(Thread *thread) { 423 assert(!thread->is_Java_thread() || Thread::current() == thread || 424 !((JavaThread *) thread)->on_thread_list() || 425 SafepointSynchronize::is_at_safepoint() || 426 ThreadsSMRSupport::is_a_protected_JavaThread_with_lock((JavaThread *) thread), 427 "possibility of dangling Thread pointer"); 428 } 429 #endif 430 431 ThreadPriority Thread::get_priority(const Thread* const thread) { 432 ThreadPriority priority; 433 // Can return an error! 434 (void)os::get_priority(thread, priority); 435 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 436 return priority; 437 } 438 439 void Thread::set_priority(Thread* thread, ThreadPriority priority) { 440 debug_only(check_for_dangling_thread_pointer(thread);) 441 // Can return an error! 442 (void)os::set_priority(thread, priority); 443 } 444 445 446 void Thread::start(Thread* thread) { 447 // Start is different from resume in that its safety is guaranteed by context or 448 // being called from a Java method synchronized on the Thread object. 449 if (!DisableStartThread) { 450 if (thread->is_Java_thread()) { 451 // Initialize the thread state to RUNNABLE before starting this thread. 452 // Can not set it after the thread started because we do not know the 453 // exact thread state at that time. It could be in MONITOR_WAIT or 454 // in SLEEPING or some other state. 455 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 456 java_lang_Thread::RUNNABLE); 457 } 458 os::start_thread(thread); 459 } 460 } 461 462 // Enqueue a VM_Operation to do the job for us - sometime later 463 void Thread::send_async_exception(oop java_thread, oop java_throwable) { 464 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 465 VMThread::execute(vm_stop); 466 } 467 468 469 // Check if an external suspend request has completed (or has been 470 // cancelled). Returns true if the thread is externally suspended and 471 // false otherwise. 472 // 473 // The bits parameter returns information about the code path through 474 // the routine. Useful for debugging: 475 // 476 // set in is_ext_suspend_completed(): 477 // 0x00000001 - routine was entered 478 // 0x00000010 - routine return false at end 479 // 0x00000100 - thread exited (return false) 480 // 0x00000200 - suspend request cancelled (return false) 481 // 0x00000400 - thread suspended (return true) 482 // 0x00001000 - thread is in a suspend equivalent state (return true) 483 // 0x00002000 - thread is native and walkable (return true) 484 // 0x00004000 - thread is native_trans and walkable (needed retry) 485 // 486 // set in wait_for_ext_suspend_completion(): 487 // 0x00010000 - routine was entered 488 // 0x00020000 - suspend request cancelled before loop (return false) 489 // 0x00040000 - thread suspended before loop (return true) 490 // 0x00080000 - suspend request cancelled in loop (return false) 491 // 0x00100000 - thread suspended in loop (return true) 492 // 0x00200000 - suspend not completed during retry loop (return false) 493 494 // Helper class for tracing suspend wait debug bits. 495 // 496 // 0x00000100 indicates that the target thread exited before it could 497 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 498 // 0x00080000 each indicate a cancelled suspend request so they don't 499 // count as wait failures either. 500 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 501 502 class TraceSuspendDebugBits : public StackObj { 503 private: 504 JavaThread * jt; 505 bool is_wait; 506 bool called_by_wait; // meaningful when !is_wait 507 uint32_t * bits; 508 509 public: 510 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 511 uint32_t *_bits) { 512 jt = _jt; 513 is_wait = _is_wait; 514 called_by_wait = _called_by_wait; 515 bits = _bits; 516 } 517 518 ~TraceSuspendDebugBits() { 519 if (!is_wait) { 520 #if 1 521 // By default, don't trace bits for is_ext_suspend_completed() calls. 522 // That trace is very chatty. 523 return; 524 #else 525 if (!called_by_wait) { 526 // If tracing for is_ext_suspend_completed() is enabled, then only 527 // trace calls to it from wait_for_ext_suspend_completion() 528 return; 529 } 530 #endif 531 } 532 533 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 534 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 535 MutexLocker ml(Threads_lock); // needed for get_thread_name() 536 ResourceMark rm; 537 538 tty->print_cr( 539 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 540 jt->get_thread_name(), *bits); 541 542 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 543 } 544 } 545 } 546 }; 547 #undef DEBUG_FALSE_BITS 548 549 550 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, 551 uint32_t *bits) { 552 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 553 554 bool did_trans_retry = false; // only do thread_in_native_trans retry once 555 bool do_trans_retry; // flag to force the retry 556 557 *bits |= 0x00000001; 558 559 do { 560 do_trans_retry = false; 561 562 if (is_exiting()) { 563 // Thread is in the process of exiting. This is always checked 564 // first to reduce the risk of dereferencing a freed JavaThread. 565 *bits |= 0x00000100; 566 return false; 567 } 568 569 if (!is_external_suspend()) { 570 // Suspend request is cancelled. This is always checked before 571 // is_ext_suspended() to reduce the risk of a rogue resume 572 // confusing the thread that made the suspend request. 573 *bits |= 0x00000200; 574 return false; 575 } 576 577 if (is_ext_suspended()) { 578 // thread is suspended 579 *bits |= 0x00000400; 580 return true; 581 } 582 583 // Now that we no longer do hard suspends of threads running 584 // native code, the target thread can be changing thread state 585 // while we are in this routine: 586 // 587 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 588 // 589 // We save a copy of the thread state as observed at this moment 590 // and make our decision about suspend completeness based on the 591 // copy. This closes the race where the thread state is seen as 592 // _thread_in_native_trans in the if-thread_blocked check, but is 593 // seen as _thread_blocked in if-thread_in_native_trans check. 594 JavaThreadState save_state = thread_state(); 595 596 if (save_state == _thread_blocked && is_suspend_equivalent()) { 597 // If the thread's state is _thread_blocked and this blocking 598 // condition is known to be equivalent to a suspend, then we can 599 // consider the thread to be externally suspended. This means that 600 // the code that sets _thread_blocked has been modified to do 601 // self-suspension if the blocking condition releases. We also 602 // used to check for CONDVAR_WAIT here, but that is now covered by 603 // the _thread_blocked with self-suspension check. 604 // 605 // Return true since we wouldn't be here unless there was still an 606 // external suspend request. 607 *bits |= 0x00001000; 608 return true; 609 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 610 // Threads running native code will self-suspend on native==>VM/Java 611 // transitions. If its stack is walkable (should always be the case 612 // unless this function is called before the actual java_suspend() 613 // call), then the wait is done. 614 *bits |= 0x00002000; 615 return true; 616 } else if (!called_by_wait && !did_trans_retry && 617 save_state == _thread_in_native_trans && 618 frame_anchor()->walkable()) { 619 // The thread is transitioning from thread_in_native to another 620 // thread state. check_safepoint_and_suspend_for_native_trans() 621 // will force the thread to self-suspend. If it hasn't gotten 622 // there yet we may have caught the thread in-between the native 623 // code check above and the self-suspend. Lucky us. If we were 624 // called by wait_for_ext_suspend_completion(), then it 625 // will be doing the retries so we don't have to. 626 // 627 // Since we use the saved thread state in the if-statement above, 628 // there is a chance that the thread has already transitioned to 629 // _thread_blocked by the time we get here. In that case, we will 630 // make a single unnecessary pass through the logic below. This 631 // doesn't hurt anything since we still do the trans retry. 632 633 *bits |= 0x00004000; 634 635 // Once the thread leaves thread_in_native_trans for another 636 // thread state, we break out of this retry loop. We shouldn't 637 // need this flag to prevent us from getting back here, but 638 // sometimes paranoia is good. 639 did_trans_retry = true; 640 641 // We wait for the thread to transition to a more usable state. 642 for (int i = 1; i <= SuspendRetryCount; i++) { 643 // We used to do an "os::yield_all(i)" call here with the intention 644 // that yielding would increase on each retry. However, the parameter 645 // is ignored on Linux which means the yield didn't scale up. Waiting 646 // on the SR_lock below provides a much more predictable scale up for 647 // the delay. It also provides a simple/direct point to check for any 648 // safepoint requests from the VMThread 649 650 // temporarily drops SR_lock while doing wait with safepoint check 651 // (if we're a JavaThread - the WatcherThread can also call this) 652 // and increase delay with each retry 653 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 654 655 // check the actual thread state instead of what we saved above 656 if (thread_state() != _thread_in_native_trans) { 657 // the thread has transitioned to another thread state so 658 // try all the checks (except this one) one more time. 659 do_trans_retry = true; 660 break; 661 } 662 } // end retry loop 663 664 665 } 666 } while (do_trans_retry); 667 668 *bits |= 0x00000010; 669 return false; 670 } 671 672 // Wait for an external suspend request to complete (or be cancelled). 673 // Returns true if the thread is externally suspended and false otherwise. 674 // 675 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 676 uint32_t *bits) { 677 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 678 false /* !called_by_wait */, bits); 679 680 // local flag copies to minimize SR_lock hold time 681 bool is_suspended; 682 bool pending; 683 uint32_t reset_bits; 684 685 // set a marker so is_ext_suspend_completed() knows we are the caller 686 *bits |= 0x00010000; 687 688 // We use reset_bits to reinitialize the bits value at the top of 689 // each retry loop. This allows the caller to make use of any 690 // unused bits for their own marking purposes. 691 reset_bits = *bits; 692 693 { 694 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 695 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 696 delay, bits); 697 pending = is_external_suspend(); 698 } 699 // must release SR_lock to allow suspension to complete 700 701 if (!pending) { 702 // A cancelled suspend request is the only false return from 703 // is_ext_suspend_completed() that keeps us from entering the 704 // retry loop. 705 *bits |= 0x00020000; 706 return false; 707 } 708 709 if (is_suspended) { 710 *bits |= 0x00040000; 711 return true; 712 } 713 714 for (int i = 1; i <= retries; i++) { 715 *bits = reset_bits; // reinit to only track last retry 716 717 // We used to do an "os::yield_all(i)" call here with the intention 718 // that yielding would increase on each retry. However, the parameter 719 // is ignored on Linux which means the yield didn't scale up. Waiting 720 // on the SR_lock below provides a much more predictable scale up for 721 // the delay. It also provides a simple/direct point to check for any 722 // safepoint requests from the VMThread 723 724 { 725 MutexLocker ml(SR_lock()); 726 // wait with safepoint check (if we're a JavaThread - the WatcherThread 727 // can also call this) and increase delay with each retry 728 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 729 730 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 731 delay, bits); 732 733 // It is possible for the external suspend request to be cancelled 734 // (by a resume) before the actual suspend operation is completed. 735 // Refresh our local copy to see if we still need to wait. 736 pending = is_external_suspend(); 737 } 738 739 if (!pending) { 740 // A cancelled suspend request is the only false return from 741 // is_ext_suspend_completed() that keeps us from staying in the 742 // retry loop. 743 *bits |= 0x00080000; 744 return false; 745 } 746 747 if (is_suspended) { 748 *bits |= 0x00100000; 749 return true; 750 } 751 } // end retry loop 752 753 // thread did not suspend after all our retries 754 *bits |= 0x00200000; 755 return false; 756 } 757 758 // Called from API entry points which perform stack walking. If the 759 // associated JavaThread is the current thread, then wait_for_suspend 760 // is not used. Otherwise, it determines if we should wait for the 761 // "other" thread to complete external suspension. (NOTE: in future 762 // releases the suspension mechanism should be reimplemented so this 763 // is not necessary.) 764 // 765 bool 766 JavaThread::is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits) { 767 if (this != JavaThread::current()) { 768 // "other" threads require special handling. 769 if (wait_for_suspend) { 770 // We are allowed to wait for the external suspend to complete 771 // so give the other thread a chance to get suspended. 772 if (!wait_for_ext_suspend_completion(SuspendRetryCount, 773 SuspendRetryDelay, bits)) { 774 // Didn't make it so let the caller know. 775 return false; 776 } 777 } 778 // We aren't allowed to wait for the external suspend to complete 779 // so if the other thread isn't externally suspended we need to 780 // let the caller know. 781 else if (!is_ext_suspend_completed_with_lock(bits)) { 782 return false; 783 } 784 } 785 786 return true; 787 } 788 789 #ifndef PRODUCT 790 void JavaThread::record_jump(address target, address instr, const char* file, 791 int line) { 792 793 // This should not need to be atomic as the only way for simultaneous 794 // updates is via interrupts. Even then this should be rare or non-existent 795 // and we don't care that much anyway. 796 797 int index = _jmp_ring_index; 798 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1); 799 _jmp_ring[index]._target = (intptr_t) target; 800 _jmp_ring[index]._instruction = (intptr_t) instr; 801 _jmp_ring[index]._file = file; 802 _jmp_ring[index]._line = line; 803 } 804 #endif // PRODUCT 805 806 void Thread::interrupt(Thread* thread) { 807 debug_only(check_for_dangling_thread_pointer(thread);) 808 os::interrupt(thread); 809 } 810 811 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 812 debug_only(check_for_dangling_thread_pointer(thread);) 813 // Note: If clear_interrupted==false, this simply fetches and 814 // returns the value of the field osthread()->interrupted(). 815 return os::is_interrupted(thread, clear_interrupted); 816 } 817 818 819 // GC Support 820 bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 821 int thread_parity = _oops_do_parity; 822 if (thread_parity != strong_roots_parity) { 823 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 824 if (res == thread_parity) { 825 return true; 826 } else { 827 guarantee(res == strong_roots_parity, "Or else what?"); 828 return false; 829 } 830 } 831 return false; 832 } 833 834 void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 835 active_handles()->oops_do(f); 836 // Do oop for ThreadShadow 837 f->do_oop((oop*)&_pending_exception); 838 handle_area()->oops_do(f); 839 840 if (MonitorInUseLists) { 841 // When using thread local monitor lists, we scan them here, 842 // and the remaining global monitors in ObjectSynchronizer::oops_do(). 843 ObjectSynchronizer::thread_local_used_oops_do(this, f); 844 } 845 } 846 847 void Thread::metadata_handles_do(void f(Metadata*)) { 848 // Only walk the Handles in Thread. 849 if (metadata_handles() != NULL) { 850 for (int i = 0; i< metadata_handles()->length(); i++) { 851 f(metadata_handles()->at(i)); 852 } 853 } 854 } 855 856 void Thread::print_on(outputStream* st) const { 857 // get_priority assumes osthread initialized 858 if (osthread() != NULL) { 859 int os_prio; 860 if (os::get_native_priority(this, &os_prio) == OS_OK) { 861 st->print("os_prio=%d ", os_prio); 862 } 863 st->print("tid=" INTPTR_FORMAT " ", p2i(this)); 864 osthread()->print_on(st); 865 } 866 if (_threads_hazard_ptr != NULL) { 867 st->print("_threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 868 } 869 if (_nested_threads_hazard_ptr != NULL) { 870 print_nested_threads_hazard_ptrs_on(st); 871 } 872 st->print(" "); 873 debug_only(if (WizardMode) print_owned_locks_on(st);) 874 } 875 876 void Thread::print_nested_threads_hazard_ptrs_on(outputStream* st) const { 877 assert(_nested_threads_hazard_ptr != NULL, "must be set to print"); 878 879 if (EnableThreadSMRStatistics) { 880 st->print(", _nested_threads_hazard_ptr_cnt=%u", _nested_threads_hazard_ptr_cnt); 881 } 882 st->print(", _nested_threads_hazard_ptrs="); 883 for (NestedThreadsList* node = _nested_threads_hazard_ptr; node != NULL; 884 node = node->next()) { 885 if (node != _nested_threads_hazard_ptr) { 886 // First node does not need a comma-space separator. 887 st->print(", "); 888 } 889 st->print(INTPTR_FORMAT, p2i(node->t_list())); 890 } 891 } 892 893 // Thread::print_on_error() is called by fatal error handler. Don't use 894 // any lock or allocate memory. 895 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 896 assert(!(is_Compiler_thread() || is_Java_thread()), "Can't call name() here if it allocates"); 897 898 if (is_VM_thread()) { st->print("VMThread"); } 899 else if (is_GC_task_thread()) { st->print("GCTaskThread"); } 900 else if (is_Watcher_thread()) { st->print("WatcherThread"); } 901 else if (is_ConcurrentGC_thread()) { st->print("ConcurrentGCThread"); } 902 else { st->print("Thread"); } 903 904 if (is_Named_thread()) { 905 st->print(" \"%s\"", name()); 906 } 907 908 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 909 p2i(stack_end()), p2i(stack_base())); 910 911 if (osthread()) { 912 st->print(" [id=%d]", osthread()->thread_id()); 913 } 914 915 if (_threads_hazard_ptr != NULL) { 916 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 917 } 918 if (_nested_threads_hazard_ptr != NULL) { 919 print_nested_threads_hazard_ptrs_on(st); 920 } 921 } 922 923 void Thread::print_value_on(outputStream* st) const { 924 if (is_Named_thread()) { 925 st->print(" \"%s\" ", name()); 926 } 927 st->print(INTPTR_FORMAT, p2i(this)); // print address 928 } 929 930 #ifdef ASSERT 931 void Thread::print_owned_locks_on(outputStream* st) const { 932 Monitor *cur = _owned_locks; 933 if (cur == NULL) { 934 st->print(" (no locks) "); 935 } else { 936 st->print_cr(" Locks owned:"); 937 while (cur) { 938 cur->print_on(st); 939 cur = cur->next(); 940 } 941 } 942 } 943 944 static int ref_use_count = 0; 945 946 bool Thread::owns_locks_but_compiled_lock() const { 947 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 948 if (cur != Compile_lock) return true; 949 } 950 return false; 951 } 952 953 954 #endif 955 956 #ifndef PRODUCT 957 958 // The flag: potential_vm_operation notifies if this particular safepoint state could potentially 959 // invoke the vm-thread (e.g., an oop allocation). In that case, we also have to make sure that 960 // no threads which allow_vm_block's are held 961 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 962 // Check if current thread is allowed to block at a safepoint 963 if (!(_allow_safepoint_count == 0)) { 964 fatal("Possible safepoint reached by thread that does not allow it"); 965 } 966 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 967 fatal("LEAF method calling lock?"); 968 } 969 970 #ifdef ASSERT 971 if (potential_vm_operation && is_Java_thread() 972 && !Universe::is_bootstrapping()) { 973 // Make sure we do not hold any locks that the VM thread also uses. 974 // This could potentially lead to deadlocks 975 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) { 976 // Threads_lock is special, since the safepoint synchronization will not start before this is 977 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 978 // since it is used to transfer control between JavaThreads and the VMThread 979 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first! 980 if ((cur->allow_vm_block() && 981 cur != Threads_lock && 982 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation 983 cur != VMOperationRequest_lock && 984 cur != VMOperationQueue_lock) || 985 cur->rank() == Mutex::special) { 986 fatal("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 987 } 988 } 989 } 990 991 if (GCALotAtAllSafepoints) { 992 // We could enter a safepoint here and thus have a gc 993 InterfaceSupport::check_gc_alot(); 994 } 995 #endif 996 } 997 #endif 998 999 bool Thread::is_in_stack(address adr) const { 1000 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 1001 address end = os::current_stack_pointer(); 1002 // Allow non Java threads to call this without stack_base 1003 if (_stack_base == NULL) return true; 1004 if (stack_base() >= adr && adr >= end) return true; 1005 1006 return false; 1007 } 1008 1009 bool Thread::is_in_usable_stack(address adr) const { 1010 size_t stack_guard_size = os::uses_stack_guard_pages() ? JavaThread::stack_guard_zone_size() : 0; 1011 size_t usable_stack_size = _stack_size - stack_guard_size; 1012 1013 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); 1014 } 1015 1016 1017 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 1018 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 1019 // used for compilation in the future. If that change is made, the need for these methods 1020 // should be revisited, and they should be removed if possible. 1021 1022 bool Thread::is_lock_owned(address adr) const { 1023 return on_local_stack(adr); 1024 } 1025 1026 bool Thread::set_as_starting_thread() { 1027 // NOTE: this must be called inside the main thread. 1028 return os::create_main_thread((JavaThread*)this); 1029 } 1030 1031 static void initialize_class(Symbol* class_name, TRAPS) { 1032 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 1033 InstanceKlass::cast(klass)->initialize(CHECK); 1034 } 1035 1036 1037 // Creates the initial ThreadGroup 1038 static Handle create_initial_thread_group(TRAPS) { 1039 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 1040 InstanceKlass* ik = InstanceKlass::cast(k); 1041 1042 Handle system_instance = ik->allocate_instance_handle(CHECK_NH); 1043 { 1044 JavaValue result(T_VOID); 1045 JavaCalls::call_special(&result, 1046 system_instance, 1047 ik, 1048 vmSymbols::object_initializer_name(), 1049 vmSymbols::void_method_signature(), 1050 CHECK_NH); 1051 } 1052 Universe::set_system_thread_group(system_instance()); 1053 1054 Handle main_instance = ik->allocate_instance_handle(CHECK_NH); 1055 { 1056 JavaValue result(T_VOID); 1057 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 1058 JavaCalls::call_special(&result, 1059 main_instance, 1060 ik, 1061 vmSymbols::object_initializer_name(), 1062 vmSymbols::threadgroup_string_void_signature(), 1063 system_instance, 1064 string, 1065 CHECK_NH); 1066 } 1067 return main_instance; 1068 } 1069 1070 // Creates the initial Thread 1071 static oop create_initial_thread(Handle thread_group, JavaThread* thread, 1072 TRAPS) { 1073 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 1074 InstanceKlass* ik = InstanceKlass::cast(k); 1075 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK_NULL); 1076 1077 java_lang_Thread::set_thread(thread_oop(), thread); 1078 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1079 thread->set_threadObj(thread_oop()); 1080 1081 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 1082 1083 JavaValue result(T_VOID); 1084 JavaCalls::call_special(&result, thread_oop, 1085 ik, 1086 vmSymbols::object_initializer_name(), 1087 vmSymbols::threadgroup_string_void_signature(), 1088 thread_group, 1089 string, 1090 CHECK_NULL); 1091 return thread_oop(); 1092 } 1093 1094 char java_runtime_name[128] = ""; 1095 char java_runtime_version[128] = ""; 1096 1097 // extract the JRE name from java.lang.VersionProps.java_runtime_name 1098 static const char* get_java_runtime_name(TRAPS) { 1099 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1100 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1101 fieldDescriptor fd; 1102 bool found = k != NULL && 1103 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), 1104 vmSymbols::string_signature(), &fd); 1105 if (found) { 1106 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1107 if (name_oop == NULL) { 1108 return NULL; 1109 } 1110 const char* name = java_lang_String::as_utf8_string(name_oop, 1111 java_runtime_name, 1112 sizeof(java_runtime_name)); 1113 return name; 1114 } else { 1115 return NULL; 1116 } 1117 } 1118 1119 // extract the JRE version from java.lang.VersionProps.java_runtime_version 1120 static const char* get_java_runtime_version(TRAPS) { 1121 Klass* k = SystemDictionary::find(vmSymbols::java_lang_VersionProps(), 1122 Handle(), Handle(), CHECK_AND_CLEAR_NULL); 1123 fieldDescriptor fd; 1124 bool found = k != NULL && 1125 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), 1126 vmSymbols::string_signature(), &fd); 1127 if (found) { 1128 oop name_oop = k->java_mirror()->obj_field(fd.offset()); 1129 if (name_oop == NULL) { 1130 return NULL; 1131 } 1132 const char* name = java_lang_String::as_utf8_string(name_oop, 1133 java_runtime_version, 1134 sizeof(java_runtime_version)); 1135 return name; 1136 } else { 1137 return NULL; 1138 } 1139 } 1140 1141 // General purpose hook into Java code, run once when the VM is initialized. 1142 // The Java library method itself may be changed independently from the VM. 1143 static void call_postVMInitHook(TRAPS) { 1144 Klass* klass = SystemDictionary::resolve_or_null(vmSymbols::jdk_internal_vm_PostVMInitHook(), THREAD); 1145 if (klass != NULL) { 1146 JavaValue result(T_VOID); 1147 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 1148 vmSymbols::void_method_signature(), 1149 CHECK); 1150 } 1151 } 1152 1153 static void reset_vm_info_property(TRAPS) { 1154 // the vm info string 1155 ResourceMark rm(THREAD); 1156 const char *vm_info = VM_Version::vm_info_string(); 1157 1158 // java.lang.System class 1159 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1160 1161 // setProperty arguments 1162 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1163 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1164 1165 // return value 1166 JavaValue r(T_OBJECT); 1167 1168 // public static String setProperty(String key, String value); 1169 JavaCalls::call_static(&r, 1170 klass, 1171 vmSymbols::setProperty_name(), 1172 vmSymbols::string_string_string_signature(), 1173 key_str, 1174 value_str, 1175 CHECK); 1176 } 1177 1178 1179 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name, 1180 bool daemon, TRAPS) { 1181 assert(thread_group.not_null(), "thread group should be specified"); 1182 assert(threadObj() == NULL, "should only create Java thread object once"); 1183 1184 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1185 InstanceKlass* ik = InstanceKlass::cast(k); 1186 instanceHandle thread_oop = ik->allocate_instance_handle(CHECK); 1187 1188 java_lang_Thread::set_thread(thread_oop(), this); 1189 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1190 set_threadObj(thread_oop()); 1191 1192 JavaValue result(T_VOID); 1193 if (thread_name != NULL) { 1194 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1195 // Thread gets assigned specified name and null target 1196 JavaCalls::call_special(&result, 1197 thread_oop, 1198 ik, 1199 vmSymbols::object_initializer_name(), 1200 vmSymbols::threadgroup_string_void_signature(), 1201 thread_group, // Argument 1 1202 name, // Argument 2 1203 THREAD); 1204 } else { 1205 // Thread gets assigned name "Thread-nnn" and null target 1206 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1207 JavaCalls::call_special(&result, 1208 thread_oop, 1209 ik, 1210 vmSymbols::object_initializer_name(), 1211 vmSymbols::threadgroup_runnable_void_signature(), 1212 thread_group, // Argument 1 1213 Handle(), // Argument 2 1214 THREAD); 1215 } 1216 1217 1218 if (daemon) { 1219 java_lang_Thread::set_daemon(thread_oop()); 1220 } 1221 1222 if (HAS_PENDING_EXCEPTION) { 1223 return; 1224 } 1225 1226 Klass* group = SystemDictionary::ThreadGroup_klass(); 1227 Handle threadObj(THREAD, this->threadObj()); 1228 1229 JavaCalls::call_special(&result, 1230 thread_group, 1231 group, 1232 vmSymbols::add_method_name(), 1233 vmSymbols::thread_void_signature(), 1234 threadObj, // Arg 1 1235 THREAD); 1236 } 1237 1238 // NamedThread -- non-JavaThread subclasses with multiple 1239 // uniquely named instances should derive from this. 1240 NamedThread::NamedThread() : Thread() { 1241 _name = NULL; 1242 _processed_thread = NULL; 1243 _gc_id = GCId::undefined(); 1244 } 1245 1246 NamedThread::~NamedThread() { 1247 if (_name != NULL) { 1248 FREE_C_HEAP_ARRAY(char, _name); 1249 _name = NULL; 1250 } 1251 } 1252 1253 void NamedThread::set_name(const char* format, ...) { 1254 guarantee(_name == NULL, "Only get to set name once."); 1255 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); 1256 guarantee(_name != NULL, "alloc failure"); 1257 va_list ap; 1258 va_start(ap, format); 1259 jio_vsnprintf(_name, max_name_len, format, ap); 1260 va_end(ap); 1261 } 1262 1263 void NamedThread::initialize_named_thread() { 1264 set_native_thread_name(name()); 1265 } 1266 1267 void NamedThread::print_on(outputStream* st) const { 1268 st->print("\"%s\" ", name()); 1269 Thread::print_on(st); 1270 st->cr(); 1271 } 1272 1273 1274 // ======= WatcherThread ======== 1275 1276 // The watcher thread exists to simulate timer interrupts. It should 1277 // be replaced by an abstraction over whatever native support for 1278 // timer interrupts exists on the platform. 1279 1280 WatcherThread* WatcherThread::_watcher_thread = NULL; 1281 bool WatcherThread::_startable = false; 1282 volatile bool WatcherThread::_should_terminate = false; 1283 1284 WatcherThread::WatcherThread() : Thread() { 1285 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1286 if (os::create_thread(this, os::watcher_thread)) { 1287 _watcher_thread = this; 1288 1289 // Set the watcher thread to the highest OS priority which should not be 1290 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1291 // is created. The only normal thread using this priority is the reference 1292 // handler thread, which runs for very short intervals only. 1293 // If the VMThread's priority is not lower than the WatcherThread profiling 1294 // will be inaccurate. 1295 os::set_priority(this, MaxPriority); 1296 if (!DisableStartThread) { 1297 os::start_thread(this); 1298 } 1299 } 1300 } 1301 1302 int WatcherThread::sleep() const { 1303 // The WatcherThread does not participate in the safepoint protocol 1304 // for the PeriodicTask_lock because it is not a JavaThread. 1305 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); 1306 1307 if (_should_terminate) { 1308 // check for termination before we do any housekeeping or wait 1309 return 0; // we did not sleep. 1310 } 1311 1312 // remaining will be zero if there are no tasks, 1313 // causing the WatcherThread to sleep until a task is 1314 // enrolled 1315 int remaining = PeriodicTask::time_to_wait(); 1316 int time_slept = 0; 1317 1318 // we expect this to timeout - we only ever get unparked when 1319 // we should terminate or when a new task has been enrolled 1320 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1321 1322 jlong time_before_loop = os::javaTimeNanos(); 1323 1324 while (true) { 1325 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, 1326 remaining); 1327 jlong now = os::javaTimeNanos(); 1328 1329 if (remaining == 0) { 1330 // if we didn't have any tasks we could have waited for a long time 1331 // consider the time_slept zero and reset time_before_loop 1332 time_slept = 0; 1333 time_before_loop = now; 1334 } else { 1335 // need to recalculate since we might have new tasks in _tasks 1336 time_slept = (int) ((now - time_before_loop) / 1000000); 1337 } 1338 1339 // Change to task list or spurious wakeup of some kind 1340 if (timedout || _should_terminate) { 1341 break; 1342 } 1343 1344 remaining = PeriodicTask::time_to_wait(); 1345 if (remaining == 0) { 1346 // Last task was just disenrolled so loop around and wait until 1347 // another task gets enrolled 1348 continue; 1349 } 1350 1351 remaining -= time_slept; 1352 if (remaining <= 0) { 1353 break; 1354 } 1355 } 1356 1357 return time_slept; 1358 } 1359 1360 void WatcherThread::run() { 1361 assert(this == watcher_thread(), "just checking"); 1362 1363 this->record_stack_base_and_size(); 1364 this->set_native_thread_name(this->name()); 1365 this->set_active_handles(JNIHandleBlock::allocate_block()); 1366 while (true) { 1367 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1368 assert(watcher_thread() == this, "thread consistency check"); 1369 1370 // Calculate how long it'll be until the next PeriodicTask work 1371 // should be done, and sleep that amount of time. 1372 int time_waited = sleep(); 1373 1374 if (VMError::is_error_reported()) { 1375 // A fatal error has happened, the error handler(VMError::report_and_die) 1376 // should abort JVM after creating an error log file. However in some 1377 // rare cases, the error handler itself might deadlock. Here periodically 1378 // check for error reporting timeouts, and if it happens, just proceed to 1379 // abort the VM. 1380 1381 // This code is in WatcherThread because WatcherThread wakes up 1382 // periodically so the fatal error handler doesn't need to do anything; 1383 // also because the WatcherThread is less likely to crash than other 1384 // threads. 1385 1386 for (;;) { 1387 // Note: we use naked sleep in this loop because we want to avoid using 1388 // any kind of VM infrastructure which may be broken at this point. 1389 if (VMError::check_timeout()) { 1390 // We hit error reporting timeout. Error reporting was interrupted and 1391 // will be wrapping things up now (closing files etc). Give it some more 1392 // time, then quit the VM. 1393 os::naked_short_sleep(200); 1394 // Print a message to stderr. 1395 fdStream err(defaultStream::output_fd()); 1396 err.print_raw_cr("# [ timer expired, abort... ]"); 1397 // skip atexit/vm_exit/vm_abort hooks 1398 os::die(); 1399 } 1400 1401 // Wait a second, then recheck for timeout. 1402 os::naked_short_sleep(999); 1403 } 1404 } 1405 1406 if (_should_terminate) { 1407 // check for termination before posting the next tick 1408 break; 1409 } 1410 1411 PeriodicTask::real_time_tick(time_waited); 1412 } 1413 1414 // Signal that it is terminated 1415 { 1416 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1417 _watcher_thread = NULL; 1418 Terminator_lock->notify(); 1419 } 1420 } 1421 1422 void WatcherThread::start() { 1423 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1424 1425 if (watcher_thread() == NULL && _startable) { 1426 _should_terminate = false; 1427 // Create the single instance of WatcherThread 1428 new WatcherThread(); 1429 } 1430 } 1431 1432 void WatcherThread::make_startable() { 1433 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1434 _startable = true; 1435 } 1436 1437 void WatcherThread::stop() { 1438 { 1439 // Follow normal safepoint aware lock enter protocol since the 1440 // WatcherThread is stopped by another JavaThread. 1441 MutexLocker ml(PeriodicTask_lock); 1442 _should_terminate = true; 1443 1444 WatcherThread* watcher = watcher_thread(); 1445 if (watcher != NULL) { 1446 // unpark the WatcherThread so it can see that it should terminate 1447 watcher->unpark(); 1448 } 1449 } 1450 1451 MutexLocker mu(Terminator_lock); 1452 1453 while (watcher_thread() != NULL) { 1454 // This wait should make safepoint checks, wait without a timeout, 1455 // and wait as a suspend-equivalent condition. 1456 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1457 Mutex::_as_suspend_equivalent_flag); 1458 } 1459 } 1460 1461 void WatcherThread::unpark() { 1462 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); 1463 PeriodicTask_lock->notify(); 1464 } 1465 1466 void WatcherThread::print_on(outputStream* st) const { 1467 st->print("\"%s\" ", name()); 1468 Thread::print_on(st); 1469 st->cr(); 1470 } 1471 1472 // ======= JavaThread ======== 1473 1474 #if INCLUDE_JVMCI 1475 1476 jlong* JavaThread::_jvmci_old_thread_counters; 1477 1478 bool jvmci_counters_include(JavaThread* thread) { 1479 oop threadObj = thread->threadObj(); 1480 return !JVMCICountersExcludeCompiler || !thread->is_Compiler_thread(); 1481 } 1482 1483 void JavaThread::collect_counters(typeArrayOop array) { 1484 if (JVMCICounterSize > 0) { 1485 MutexLocker tl(Threads_lock); 1486 JavaThreadIteratorWithHandle jtiwh; 1487 for (int i = 0; i < array->length(); i++) { 1488 array->long_at_put(i, _jvmci_old_thread_counters[i]); 1489 } 1490 for (; JavaThread *tp = jtiwh.next(); ) { 1491 if (jvmci_counters_include(tp)) { 1492 for (int i = 0; i < array->length(); i++) { 1493 array->long_at_put(i, array->long_at(i) + tp->_jvmci_counters[i]); 1494 } 1495 } 1496 } 1497 } 1498 } 1499 1500 #endif // INCLUDE_JVMCI 1501 1502 // A JavaThread is a normal Java thread 1503 1504 void JavaThread::initialize() { 1505 // Initialize fields 1506 1507 set_saved_exception_pc(NULL); 1508 set_threadObj(NULL); 1509 _anchor.clear(); 1510 set_entry_point(NULL); 1511 set_jni_functions(jni_functions()); 1512 set_callee_target(NULL); 1513 set_vm_result(NULL); 1514 set_vm_result_2(NULL); 1515 set_vframe_array_head(NULL); 1516 set_vframe_array_last(NULL); 1517 set_deferred_locals(NULL); 1518 set_deopt_mark(NULL); 1519 set_deopt_compiled_method(NULL); 1520 clear_must_deopt_id(); 1521 set_monitor_chunks(NULL); 1522 set_next(NULL); 1523 _on_thread_list = false; 1524 set_thread_state(_thread_new); 1525 _terminated = _not_terminated; 1526 _privileged_stack_top = NULL; 1527 _array_for_gc = NULL; 1528 _suspend_equivalent = false; 1529 _in_deopt_handler = 0; 1530 _doing_unsafe_access = false; 1531 _stack_guard_state = stack_guard_unused; 1532 #if INCLUDE_JVMCI 1533 _pending_monitorenter = false; 1534 _pending_deoptimization = -1; 1535 _pending_failed_speculation = NULL; 1536 _pending_transfer_to_interpreter = false; 1537 _adjusting_comp_level = false; 1538 _jvmci._alternate_call_target = NULL; 1539 assert(_jvmci._implicit_exception_pc == NULL, "must be"); 1540 if (JVMCICounterSize > 0) { 1541 _jvmci_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 1542 memset(_jvmci_counters, 0, sizeof(jlong) * JVMCICounterSize); 1543 } else { 1544 _jvmci_counters = NULL; 1545 } 1546 #endif // INCLUDE_JVMCI 1547 _reserved_stack_activation = NULL; // stack base not known yet 1548 (void)const_cast<oop&>(_exception_oop = oop(NULL)); 1549 _exception_pc = 0; 1550 _exception_handler_pc = 0; 1551 _is_method_handle_return = 0; 1552 _jvmti_thread_state= NULL; 1553 _should_post_on_exceptions_flag = JNI_FALSE; 1554 _jvmti_get_loaded_classes_closure = NULL; 1555 _interp_only_mode = 0; 1556 _special_runtime_exit_condition = _no_async_condition; 1557 _pending_async_exception = NULL; 1558 _thread_stat = NULL; 1559 _thread_stat = new ThreadStatistics(); 1560 _blocked_on_compilation = false; 1561 _jni_active_critical = 0; 1562 _pending_jni_exception_check_fn = NULL; 1563 _do_not_unlock_if_synchronized = false; 1564 _cached_monitor_info = NULL; 1565 _parker = Parker::Allocate(this); 1566 1567 #ifndef PRODUCT 1568 _jmp_ring_index = 0; 1569 for (int ji = 0; ji < jump_ring_buffer_size; ji++) { 1570 record_jump(NULL, NULL, NULL, 0); 1571 } 1572 #endif // PRODUCT 1573 1574 // Setup safepoint state info for this thread 1575 ThreadSafepointState::create(this); 1576 1577 debug_only(_java_call_counter = 0); 1578 1579 // JVMTI PopFrame support 1580 _popframe_condition = popframe_inactive; 1581 _popframe_preserved_args = NULL; 1582 _popframe_preserved_args_size = 0; 1583 _frames_to_pop_failed_realloc = 0; 1584 1585 if (SafepointMechanism::uses_thread_local_poll()) { 1586 SafepointMechanism::initialize_header(this); 1587 } 1588 1589 pd_initialize(); 1590 } 1591 1592 #if INCLUDE_ALL_GCS 1593 SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1594 DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1595 #endif // INCLUDE_ALL_GCS 1596 1597 JavaThread::JavaThread(bool is_attaching_via_jni) : 1598 Thread() 1599 #if INCLUDE_ALL_GCS 1600 , _satb_mark_queue(&_satb_mark_queue_set), 1601 _dirty_card_queue(&_dirty_card_queue_set) 1602 #endif // INCLUDE_ALL_GCS 1603 { 1604 initialize(); 1605 if (is_attaching_via_jni) { 1606 _jni_attach_state = _attaching_via_jni; 1607 } else { 1608 _jni_attach_state = _not_attaching_via_jni; 1609 } 1610 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); 1611 } 1612 1613 bool JavaThread::reguard_stack(address cur_sp) { 1614 if (_stack_guard_state != stack_guard_yellow_reserved_disabled 1615 && _stack_guard_state != stack_guard_reserved_disabled) { 1616 return true; // Stack already guarded or guard pages not needed. 1617 } 1618 1619 if (register_stack_overflow()) { 1620 // For those architectures which have separate register and 1621 // memory stacks, we must check the register stack to see if 1622 // it has overflowed. 1623 return false; 1624 } 1625 1626 // Java code never executes within the yellow zone: the latter is only 1627 // there to provoke an exception during stack banging. If java code 1628 // is executing there, either StackShadowPages should be larger, or 1629 // some exception code in c1, c2 or the interpreter isn't unwinding 1630 // when it should. 1631 guarantee(cur_sp > stack_reserved_zone_base(), 1632 "not enough space to reguard - increase StackShadowPages"); 1633 if (_stack_guard_state == stack_guard_yellow_reserved_disabled) { 1634 enable_stack_yellow_reserved_zone(); 1635 if (reserved_stack_activation() != stack_base()) { 1636 set_reserved_stack_activation(stack_base()); 1637 } 1638 } else if (_stack_guard_state == stack_guard_reserved_disabled) { 1639 set_reserved_stack_activation(stack_base()); 1640 enable_stack_reserved_zone(); 1641 } 1642 return true; 1643 } 1644 1645 bool JavaThread::reguard_stack(void) { 1646 return reguard_stack(os::current_stack_pointer()); 1647 } 1648 1649 1650 void JavaThread::block_if_vm_exited() { 1651 if (_terminated == _vm_exited) { 1652 // _vm_exited is set at safepoint, and Threads_lock is never released 1653 // we will block here forever 1654 Threads_lock->lock_without_safepoint_check(); 1655 ShouldNotReachHere(); 1656 } 1657 } 1658 1659 1660 // Remove this ifdef when C1 is ported to the compiler interface. 1661 static void compiler_thread_entry(JavaThread* thread, TRAPS); 1662 static void sweeper_thread_entry(JavaThread* thread, TRAPS); 1663 1664 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1665 Thread() 1666 #if INCLUDE_ALL_GCS 1667 , _satb_mark_queue(&_satb_mark_queue_set), 1668 _dirty_card_queue(&_dirty_card_queue_set) 1669 #endif // INCLUDE_ALL_GCS 1670 { 1671 initialize(); 1672 _jni_attach_state = _not_attaching_via_jni; 1673 set_entry_point(entry_point); 1674 // Create the native thread itself. 1675 // %note runtime_23 1676 os::ThreadType thr_type = os::java_thread; 1677 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1678 os::java_thread; 1679 os::create_thread(this, thr_type, stack_sz); 1680 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1681 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1682 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1683 // the exception consists of creating the exception object & initializing it, initialization 1684 // will leave the VM via a JavaCall and then all locks must be unlocked). 1685 // 1686 // The thread is still suspended when we reach here. Thread must be explicit started 1687 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1688 // by calling Threads:add. The reason why this is not done here, is because the thread 1689 // object must be fully initialized (take a look at JVM_Start) 1690 } 1691 1692 JavaThread::~JavaThread() { 1693 1694 // JSR166 -- return the parker to the free list 1695 Parker::Release(_parker); 1696 _parker = NULL; 1697 1698 // Free any remaining previous UnrollBlock 1699 vframeArray* old_array = vframe_array_last(); 1700 1701 if (old_array != NULL) { 1702 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1703 old_array->set_unroll_block(NULL); 1704 delete old_info; 1705 delete old_array; 1706 } 1707 1708 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1709 if (deferred != NULL) { 1710 // This can only happen if thread is destroyed before deoptimization occurs. 1711 assert(deferred->length() != 0, "empty array!"); 1712 do { 1713 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1714 deferred->remove_at(0); 1715 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1716 delete dlv; 1717 } while (deferred->length() != 0); 1718 delete deferred; 1719 } 1720 1721 // All Java related clean up happens in exit 1722 ThreadSafepointState::destroy(this); 1723 if (_thread_stat != NULL) delete _thread_stat; 1724 1725 #if INCLUDE_JVMCI 1726 if (JVMCICounterSize > 0) { 1727 if (jvmci_counters_include(this)) { 1728 for (int i = 0; i < JVMCICounterSize; i++) { 1729 _jvmci_old_thread_counters[i] += _jvmci_counters[i]; 1730 } 1731 } 1732 FREE_C_HEAP_ARRAY(jlong, _jvmci_counters); 1733 } 1734 #endif // INCLUDE_JVMCI 1735 } 1736 1737 1738 // The first routine called by a new Java thread 1739 void JavaThread::run() { 1740 // initialize thread-local alloc buffer related fields 1741 this->initialize_tlab(); 1742 1743 // used to test validity of stack trace backs 1744 this->record_base_of_stack_pointer(); 1745 1746 // Record real stack base and size. 1747 this->record_stack_base_and_size(); 1748 1749 this->create_stack_guard_pages(); 1750 1751 this->cache_global_variables(); 1752 1753 // Thread is now sufficient initialized to be handled by the safepoint code as being 1754 // in the VM. Change thread state from _thread_new to _thread_in_vm 1755 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1756 1757 assert(JavaThread::current() == this, "sanity check"); 1758 assert(!Thread::current()->owns_locks(), "sanity check"); 1759 1760 DTRACE_THREAD_PROBE(start, this); 1761 1762 // This operation might block. We call that after all safepoint checks for a new thread has 1763 // been completed. 1764 this->set_active_handles(JNIHandleBlock::allocate_block()); 1765 1766 if (JvmtiExport::should_post_thread_life()) { 1767 JvmtiExport::post_thread_start(this); 1768 } 1769 1770 EventThreadStart event; 1771 if (event.should_commit()) { 1772 event.set_thread(THREAD_TRACE_ID(this)); 1773 event.commit(); 1774 } 1775 1776 // We call another function to do the rest so we are sure that the stack addresses used 1777 // from there will be lower than the stack base just computed 1778 thread_main_inner(); 1779 1780 // Note, thread is no longer valid at this point! 1781 } 1782 1783 1784 void JavaThread::thread_main_inner() { 1785 assert(JavaThread::current() == this, "sanity check"); 1786 assert(this->threadObj() != NULL, "just checking"); 1787 1788 // Execute thread entry point unless this thread has a pending exception 1789 // or has been stopped before starting. 1790 // Note: Due to JVM_StopThread we can have pending exceptions already! 1791 if (!this->has_pending_exception() && 1792 !java_lang_Thread::is_stillborn(this->threadObj())) { 1793 { 1794 ResourceMark rm(this); 1795 this->set_native_thread_name(this->get_thread_name()); 1796 } 1797 HandleMark hm(this); 1798 this->entry_point()(this, this); 1799 } 1800 1801 DTRACE_THREAD_PROBE(stop, this); 1802 1803 this->exit(false); 1804 this->smr_delete(); 1805 } 1806 1807 1808 static void ensure_join(JavaThread* thread) { 1809 // We do not need to grab the Threads_lock, since we are operating on ourself. 1810 Handle threadObj(thread, thread->threadObj()); 1811 assert(threadObj.not_null(), "java thread object must exist"); 1812 ObjectLocker lock(threadObj, thread); 1813 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1814 thread->clear_pending_exception(); 1815 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1816 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1817 // Clear the native thread instance - this makes isAlive return false and allows the join() 1818 // to complete once we've done the notify_all below 1819 java_lang_Thread::set_thread(threadObj(), NULL); 1820 lock.notify_all(thread); 1821 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1822 thread->clear_pending_exception(); 1823 } 1824 1825 1826 // For any new cleanup additions, please check to see if they need to be applied to 1827 // cleanup_failed_attach_current_thread as well. 1828 void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1829 assert(this == JavaThread::current(), "thread consistency check"); 1830 1831 elapsedTimer _timer_exit_phase1; 1832 elapsedTimer _timer_exit_phase2; 1833 elapsedTimer _timer_exit_phase3; 1834 elapsedTimer _timer_exit_phase4; 1835 1836 if (log_is_enabled(Debug, os, thread, timer)) { 1837 _timer_exit_phase1.start(); 1838 } 1839 1840 HandleMark hm(this); 1841 Handle uncaught_exception(this, this->pending_exception()); 1842 this->clear_pending_exception(); 1843 Handle threadObj(this, this->threadObj()); 1844 assert(threadObj.not_null(), "Java thread object should be created"); 1845 1846 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1847 { 1848 EXCEPTION_MARK; 1849 1850 CLEAR_PENDING_EXCEPTION; 1851 } 1852 if (!destroy_vm) { 1853 if (uncaught_exception.not_null()) { 1854 EXCEPTION_MARK; 1855 // Call method Thread.dispatchUncaughtException(). 1856 Klass* thread_klass = SystemDictionary::Thread_klass(); 1857 JavaValue result(T_VOID); 1858 JavaCalls::call_virtual(&result, 1859 threadObj, thread_klass, 1860 vmSymbols::dispatchUncaughtException_name(), 1861 vmSymbols::throwable_void_signature(), 1862 uncaught_exception, 1863 THREAD); 1864 if (HAS_PENDING_EXCEPTION) { 1865 ResourceMark rm(this); 1866 jio_fprintf(defaultStream::error_stream(), 1867 "\nException: %s thrown from the UncaughtExceptionHandler" 1868 " in thread \"%s\"\n", 1869 pending_exception()->klass()->external_name(), 1870 get_thread_name()); 1871 CLEAR_PENDING_EXCEPTION; 1872 } 1873 } 1874 1875 // Called before the java thread exit since we want to read info 1876 // from java_lang_Thread object 1877 EventThreadEnd event; 1878 if (event.should_commit()) { 1879 event.set_thread(THREAD_TRACE_ID(this)); 1880 event.commit(); 1881 } 1882 1883 // Call after last event on thread 1884 EVENT_THREAD_EXIT(this); 1885 1886 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1887 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1888 // is deprecated anyhow. 1889 if (!is_Compiler_thread()) { 1890 int count = 3; 1891 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1892 EXCEPTION_MARK; 1893 JavaValue result(T_VOID); 1894 Klass* thread_klass = SystemDictionary::Thread_klass(); 1895 JavaCalls::call_virtual(&result, 1896 threadObj, thread_klass, 1897 vmSymbols::exit_method_name(), 1898 vmSymbols::void_method_signature(), 1899 THREAD); 1900 CLEAR_PENDING_EXCEPTION; 1901 } 1902 } 1903 // notify JVMTI 1904 if (JvmtiExport::should_post_thread_life()) { 1905 JvmtiExport::post_thread_end(this); 1906 } 1907 1908 // We have notified the agents that we are exiting, before we go on, 1909 // we must check for a pending external suspend request and honor it 1910 // in order to not surprise the thread that made the suspend request. 1911 while (true) { 1912 { 1913 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1914 if (!is_external_suspend()) { 1915 set_terminated(_thread_exiting); 1916 ThreadService::current_thread_exiting(this); 1917 break; 1918 } 1919 // Implied else: 1920 // Things get a little tricky here. We have a pending external 1921 // suspend request, but we are holding the SR_lock so we 1922 // can't just self-suspend. So we temporarily drop the lock 1923 // and then self-suspend. 1924 } 1925 1926 ThreadBlockInVM tbivm(this); 1927 java_suspend_self(); 1928 1929 // We're done with this suspend request, but we have to loop around 1930 // and check again. Eventually we will get SR_lock without a pending 1931 // external suspend request and will be able to mark ourselves as 1932 // exiting. 1933 } 1934 // no more external suspends are allowed at this point 1935 } else { 1936 // before_exit() has already posted JVMTI THREAD_END events 1937 } 1938 1939 if (log_is_enabled(Debug, os, thread, timer)) { 1940 _timer_exit_phase1.stop(); 1941 _timer_exit_phase2.start(); 1942 } 1943 // Notify waiters on thread object. This has to be done after exit() is called 1944 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1945 // group should have the destroyed bit set before waiters are notified). 1946 ensure_join(this); 1947 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1948 1949 if (log_is_enabled(Debug, os, thread, timer)) { 1950 _timer_exit_phase2.stop(); 1951 _timer_exit_phase3.start(); 1952 } 1953 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1954 // held by this thread must be released. The spec does not distinguish 1955 // between JNI-acquired and regular Java monitors. We can only see 1956 // regular Java monitors here if monitor enter-exit matching is broken. 1957 // 1958 // Optionally release any monitors for regular JavaThread exits. This 1959 // is provided as a work around for any bugs in monitor enter-exit 1960 // matching. This can be expensive so it is not enabled by default. 1961 // 1962 // ensure_join() ignores IllegalThreadStateExceptions, and so does 1963 // ObjectSynchronizer::release_monitors_owned_by_thread(). 1964 if (exit_type == jni_detach || ObjectMonitor::Knob_ExitRelease) { 1965 // Sanity check even though JNI DetachCurrentThread() would have 1966 // returned JNI_ERR if there was a Java frame. JavaThread exit 1967 // should be done executing Java code by the time we get here. 1968 assert(!this->has_last_Java_frame(), 1969 "should not have a Java frame when detaching or exiting"); 1970 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1971 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1972 } 1973 1974 // These things needs to be done while we are still a Java Thread. Make sure that thread 1975 // is in a consistent state, in case GC happens 1976 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1977 1978 if (active_handles() != NULL) { 1979 JNIHandleBlock* block = active_handles(); 1980 set_active_handles(NULL); 1981 JNIHandleBlock::release_block(block); 1982 } 1983 1984 if (free_handle_block() != NULL) { 1985 JNIHandleBlock* block = free_handle_block(); 1986 set_free_handle_block(NULL); 1987 JNIHandleBlock::release_block(block); 1988 } 1989 1990 // These have to be removed while this is still a valid thread. 1991 remove_stack_guard_pages(); 1992 1993 if (UseTLAB) { 1994 tlab().make_parsable(true); // retire TLAB 1995 } 1996 1997 if (JvmtiEnv::environments_might_exist()) { 1998 JvmtiExport::cleanup_thread(this); 1999 } 2000 2001 // We must flush any deferred card marks and other various GC barrier 2002 // related buffers (e.g. G1 SATB buffer and G1 dirty card queue buffer) 2003 // before removing a thread from the list of active threads. 2004 BarrierSet::barrier_set()->on_thread_detach(this); 2005 2006 log_info(os, thread)("JavaThread %s (tid: " UINTX_FORMAT ").", 2007 exit_type == JavaThread::normal_exit ? "exiting" : "detaching", 2008 os::current_thread_id()); 2009 2010 if (log_is_enabled(Debug, os, thread, timer)) { 2011 _timer_exit_phase3.stop(); 2012 _timer_exit_phase4.start(); 2013 } 2014 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 2015 Threads::remove(this); 2016 2017 if (log_is_enabled(Debug, os, thread, timer)) { 2018 _timer_exit_phase4.stop(); 2019 ResourceMark rm(this); 2020 log_debug(os, thread, timer)("name='%s'" 2021 ", exit-phase1=" JLONG_FORMAT 2022 ", exit-phase2=" JLONG_FORMAT 2023 ", exit-phase3=" JLONG_FORMAT 2024 ", exit-phase4=" JLONG_FORMAT, 2025 get_thread_name(), 2026 _timer_exit_phase1.milliseconds(), 2027 _timer_exit_phase2.milliseconds(), 2028 _timer_exit_phase3.milliseconds(), 2029 _timer_exit_phase4.milliseconds()); 2030 } 2031 } 2032 2033 void JavaThread::cleanup_failed_attach_current_thread() { 2034 if (active_handles() != NULL) { 2035 JNIHandleBlock* block = active_handles(); 2036 set_active_handles(NULL); 2037 JNIHandleBlock::release_block(block); 2038 } 2039 2040 if (free_handle_block() != NULL) { 2041 JNIHandleBlock* block = free_handle_block(); 2042 set_free_handle_block(NULL); 2043 JNIHandleBlock::release_block(block); 2044 } 2045 2046 // These have to be removed while this is still a valid thread. 2047 remove_stack_guard_pages(); 2048 2049 if (UseTLAB) { 2050 tlab().make_parsable(true); // retire TLAB, if any 2051 } 2052 2053 2054 BarrierSet::barrier_set()->on_thread_detach(this); 2055 2056 Threads::remove(this); 2057 this->smr_delete(); 2058 } 2059 2060 JavaThread* JavaThread::active() { 2061 Thread* thread = Thread::current(); 2062 if (thread->is_Java_thread()) { 2063 return (JavaThread*) thread; 2064 } else { 2065 assert(thread->is_VM_thread(), "this must be a vm thread"); 2066 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 2067 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 2068 assert(ret->is_Java_thread(), "must be a Java thread"); 2069 return ret; 2070 } 2071 } 2072 2073 bool JavaThread::is_lock_owned(address adr) const { 2074 if (Thread::is_lock_owned(adr)) return true; 2075 2076 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2077 if (chunk->contains(adr)) return true; 2078 } 2079 2080 return false; 2081 } 2082 2083 2084 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 2085 chunk->set_next(monitor_chunks()); 2086 set_monitor_chunks(chunk); 2087 } 2088 2089 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 2090 guarantee(monitor_chunks() != NULL, "must be non empty"); 2091 if (monitor_chunks() == chunk) { 2092 set_monitor_chunks(chunk->next()); 2093 } else { 2094 MonitorChunk* prev = monitor_chunks(); 2095 while (prev->next() != chunk) prev = prev->next(); 2096 prev->set_next(chunk->next()); 2097 } 2098 } 2099 2100 // JVM support. 2101 2102 // Note: this function shouldn't block if it's called in 2103 // _thread_in_native_trans state (such as from 2104 // check_special_condition_for_native_trans()). 2105 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 2106 2107 if (has_last_Java_frame() && has_async_condition()) { 2108 // If we are at a polling page safepoint (not a poll return) 2109 // then we must defer async exception because live registers 2110 // will be clobbered by the exception path. Poll return is 2111 // ok because the call we a returning from already collides 2112 // with exception handling registers and so there is no issue. 2113 // (The exception handling path kills call result registers but 2114 // this is ok since the exception kills the result anyway). 2115 2116 if (is_at_poll_safepoint()) { 2117 // if the code we are returning to has deoptimized we must defer 2118 // the exception otherwise live registers get clobbered on the 2119 // exception path before deoptimization is able to retrieve them. 2120 // 2121 RegisterMap map(this, false); 2122 frame caller_fr = last_frame().sender(&map); 2123 assert(caller_fr.is_compiled_frame(), "what?"); 2124 if (caller_fr.is_deoptimized_frame()) { 2125 log_info(exceptions)("deferred async exception at compiled safepoint"); 2126 return; 2127 } 2128 } 2129 } 2130 2131 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 2132 if (condition == _no_async_condition) { 2133 // Conditions have changed since has_special_runtime_exit_condition() 2134 // was called: 2135 // - if we were here only because of an external suspend request, 2136 // then that was taken care of above (or cancelled) so we are done 2137 // - if we were here because of another async request, then it has 2138 // been cleared between the has_special_runtime_exit_condition() 2139 // and now so again we are done 2140 return; 2141 } 2142 2143 // Check for pending async. exception 2144 if (_pending_async_exception != NULL) { 2145 // Only overwrite an already pending exception, if it is not a threadDeath. 2146 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 2147 2148 // We cannot call Exceptions::_throw(...) here because we cannot block 2149 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 2150 2151 LogTarget(Info, exceptions) lt; 2152 if (lt.is_enabled()) { 2153 ResourceMark rm; 2154 LogStream ls(lt); 2155 ls.print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", p2i(this)); 2156 if (has_last_Java_frame()) { 2157 frame f = last_frame(); 2158 ls.print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", p2i(f.pc()), p2i(f.sp())); 2159 } 2160 ls.print_cr(" of type: %s", _pending_async_exception->klass()->external_name()); 2161 } 2162 _pending_async_exception = NULL; 2163 clear_has_async_exception(); 2164 } 2165 } 2166 2167 if (check_unsafe_error && 2168 condition == _async_unsafe_access_error && !has_pending_exception()) { 2169 condition = _no_async_condition; // done 2170 switch (thread_state()) { 2171 case _thread_in_vm: { 2172 JavaThread* THREAD = this; 2173 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2174 } 2175 case _thread_in_native: { 2176 ThreadInVMfromNative tiv(this); 2177 JavaThread* THREAD = this; 2178 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 2179 } 2180 case _thread_in_Java: { 2181 ThreadInVMfromJava tiv(this); 2182 JavaThread* THREAD = this; 2183 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 2184 } 2185 default: 2186 ShouldNotReachHere(); 2187 } 2188 } 2189 2190 assert(condition == _no_async_condition || has_pending_exception() || 2191 (!check_unsafe_error && condition == _async_unsafe_access_error), 2192 "must have handled the async condition, if no exception"); 2193 } 2194 2195 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 2196 // 2197 // Check for pending external suspend. Internal suspend requests do 2198 // not use handle_special_runtime_exit_condition(). 2199 // If JNIEnv proxies are allowed, don't self-suspend if the target 2200 // thread is not the current thread. In older versions of jdbx, jdbx 2201 // threads could call into the VM with another thread's JNIEnv so we 2202 // can be here operating on behalf of a suspended thread (4432884). 2203 bool do_self_suspend = is_external_suspend_with_lock(); 2204 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 2205 // 2206 // Because thread is external suspended the safepoint code will count 2207 // thread as at a safepoint. This can be odd because we can be here 2208 // as _thread_in_Java which would normally transition to _thread_blocked 2209 // at a safepoint. We would like to mark the thread as _thread_blocked 2210 // before calling java_suspend_self like all other callers of it but 2211 // we must then observe proper safepoint protocol. (We can't leave 2212 // _thread_blocked with a safepoint in progress). However we can be 2213 // here as _thread_in_native_trans so we can't use a normal transition 2214 // constructor/destructor pair because they assert on that type of 2215 // transition. We could do something like: 2216 // 2217 // JavaThreadState state = thread_state(); 2218 // set_thread_state(_thread_in_vm); 2219 // { 2220 // ThreadBlockInVM tbivm(this); 2221 // java_suspend_self() 2222 // } 2223 // set_thread_state(_thread_in_vm_trans); 2224 // if (safepoint) block; 2225 // set_thread_state(state); 2226 // 2227 // but that is pretty messy. Instead we just go with the way the 2228 // code has worked before and note that this is the only path to 2229 // java_suspend_self that doesn't put the thread in _thread_blocked 2230 // mode. 2231 2232 frame_anchor()->make_walkable(this); 2233 java_suspend_self(); 2234 2235 // We might be here for reasons in addition to the self-suspend request 2236 // so check for other async requests. 2237 } 2238 2239 if (check_asyncs) { 2240 check_and_handle_async_exceptions(); 2241 } 2242 #if INCLUDE_TRACE 2243 if (is_trace_suspend()) { 2244 TRACE_SUSPEND_THREAD(this); 2245 } 2246 #endif 2247 } 2248 2249 void JavaThread::send_thread_stop(oop java_throwable) { 2250 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 2251 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 2252 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 2253 2254 // Do not throw asynchronous exceptions against the compiler thread 2255 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 2256 if (!can_call_java()) return; 2257 2258 { 2259 // Actually throw the Throwable against the target Thread - however 2260 // only if there is no thread death exception installed already. 2261 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2262 // If the topmost frame is a runtime stub, then we are calling into 2263 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2264 // must deoptimize the caller before continuing, as the compiled exception handler table 2265 // may not be valid 2266 if (has_last_Java_frame()) { 2267 frame f = last_frame(); 2268 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2269 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2270 RegisterMap reg_map(this, UseBiasedLocking); 2271 frame compiled_frame = f.sender(®_map); 2272 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { 2273 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2274 } 2275 } 2276 } 2277 2278 // Set async. pending exception in thread. 2279 set_pending_async_exception(java_throwable); 2280 2281 if (log_is_enabled(Info, exceptions)) { 2282 ResourceMark rm; 2283 log_info(exceptions)("Pending Async. exception installed of type: %s", 2284 InstanceKlass::cast(_pending_async_exception->klass())->external_name()); 2285 } 2286 // for AbortVMOnException flag 2287 Exceptions::debug_check_abort(_pending_async_exception->klass()->external_name()); 2288 } 2289 } 2290 2291 2292 // Interrupt thread so it will wake up from a potential wait() 2293 Thread::interrupt(this); 2294 } 2295 2296 // External suspension mechanism. 2297 // 2298 // Tell the VM to suspend a thread when ever it knows that it does not hold on 2299 // to any VM_locks and it is at a transition 2300 // Self-suspension will happen on the transition out of the vm. 2301 // Catch "this" coming in from JNIEnv pointers when the thread has been freed 2302 // 2303 // Guarantees on return: 2304 // + Target thread will not execute any new bytecode (that's why we need to 2305 // force a safepoint) 2306 // + Target thread will not enter any new monitors 2307 // 2308 void JavaThread::java_suspend() { 2309 ThreadsListHandle tlh; 2310 if (!tlh.includes(this) || threadObj() == NULL || is_exiting()) { 2311 return; 2312 } 2313 2314 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2315 if (!is_external_suspend()) { 2316 // a racing resume has cancelled us; bail out now 2317 return; 2318 } 2319 2320 // suspend is done 2321 uint32_t debug_bits = 0; 2322 // Warning: is_ext_suspend_completed() may temporarily drop the 2323 // SR_lock to allow the thread to reach a stable thread state if 2324 // it is currently in a transient thread state. 2325 if (is_ext_suspend_completed(false /* !called_by_wait */, 2326 SuspendRetryDelay, &debug_bits)) { 2327 return; 2328 } 2329 } 2330 2331 VM_ThreadSuspend vm_suspend; 2332 VMThread::execute(&vm_suspend); 2333 } 2334 2335 // Part II of external suspension. 2336 // A JavaThread self suspends when it detects a pending external suspend 2337 // request. This is usually on transitions. It is also done in places 2338 // where continuing to the next transition would surprise the caller, 2339 // e.g., monitor entry. 2340 // 2341 // Returns the number of times that the thread self-suspended. 2342 // 2343 // Note: DO NOT call java_suspend_self() when you just want to block current 2344 // thread. java_suspend_self() is the second stage of cooperative 2345 // suspension for external suspend requests and should only be used 2346 // to complete an external suspend request. 2347 // 2348 int JavaThread::java_suspend_self() { 2349 int ret = 0; 2350 2351 // we are in the process of exiting so don't suspend 2352 if (is_exiting()) { 2353 clear_external_suspend(); 2354 return ret; 2355 } 2356 2357 assert(_anchor.walkable() || 2358 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2359 "must have walkable stack"); 2360 2361 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2362 2363 assert(!this->is_ext_suspended(), 2364 "a thread trying to self-suspend should not already be suspended"); 2365 2366 if (this->is_suspend_equivalent()) { 2367 // If we are self-suspending as a result of the lifting of a 2368 // suspend equivalent condition, then the suspend_equivalent 2369 // flag is not cleared until we set the ext_suspended flag so 2370 // that wait_for_ext_suspend_completion() returns consistent 2371 // results. 2372 this->clear_suspend_equivalent(); 2373 } 2374 2375 // A racing resume may have cancelled us before we grabbed SR_lock 2376 // above. Or another external suspend request could be waiting for us 2377 // by the time we return from SR_lock()->wait(). The thread 2378 // that requested the suspension may already be trying to walk our 2379 // stack and if we return now, we can change the stack out from under 2380 // it. This would be a "bad thing (TM)" and cause the stack walker 2381 // to crash. We stay self-suspended until there are no more pending 2382 // external suspend requests. 2383 while (is_external_suspend()) { 2384 ret++; 2385 this->set_ext_suspended(); 2386 2387 // _ext_suspended flag is cleared by java_resume() 2388 while (is_ext_suspended()) { 2389 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2390 } 2391 } 2392 2393 return ret; 2394 } 2395 2396 #ifdef ASSERT 2397 // Verify the JavaThread has not yet been published in the Threads::list, and 2398 // hence doesn't need protection from concurrent access at this stage. 2399 void JavaThread::verify_not_published() { 2400 // Cannot create a ThreadsListHandle here and check !tlh.includes(this) 2401 // since an unpublished JavaThread doesn't participate in the 2402 // Thread-SMR protocol for keeping a ThreadsList alive. 2403 assert(!on_thread_list(), "JavaThread shouldn't have been published yet!"); 2404 } 2405 #endif 2406 2407 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2408 // progress or when _suspend_flags is non-zero. 2409 // Current thread needs to self-suspend if there is a suspend request and/or 2410 // block if a safepoint is in progress. 2411 // Async exception ISN'T checked. 2412 // Note only the ThreadInVMfromNative transition can call this function 2413 // directly and when thread state is _thread_in_native_trans 2414 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2415 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2416 2417 JavaThread *curJT = JavaThread::current(); 2418 bool do_self_suspend = thread->is_external_suspend(); 2419 2420 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2421 2422 // If JNIEnv proxies are allowed, don't self-suspend if the target 2423 // thread is not the current thread. In older versions of jdbx, jdbx 2424 // threads could call into the VM with another thread's JNIEnv so we 2425 // can be here operating on behalf of a suspended thread (4432884). 2426 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2427 JavaThreadState state = thread->thread_state(); 2428 2429 // We mark this thread_blocked state as a suspend-equivalent so 2430 // that a caller to is_ext_suspend_completed() won't be confused. 2431 // The suspend-equivalent state is cleared by java_suspend_self(). 2432 thread->set_suspend_equivalent(); 2433 2434 // If the safepoint code sees the _thread_in_native_trans state, it will 2435 // wait until the thread changes to other thread state. There is no 2436 // guarantee on how soon we can obtain the SR_lock and complete the 2437 // self-suspend request. It would be a bad idea to let safepoint wait for 2438 // too long. Temporarily change the state to _thread_blocked to 2439 // let the VM thread know that this thread is ready for GC. The problem 2440 // of changing thread state is that safepoint could happen just after 2441 // java_suspend_self() returns after being resumed, and VM thread will 2442 // see the _thread_blocked state. We must check for safepoint 2443 // after restoring the state and make sure we won't leave while a safepoint 2444 // is in progress. 2445 thread->set_thread_state(_thread_blocked); 2446 thread->java_suspend_self(); 2447 thread->set_thread_state(state); 2448 2449 InterfaceSupport::serialize_thread_state_with_handler(thread); 2450 } 2451 2452 SafepointMechanism::block_if_requested(curJT); 2453 2454 if (thread->is_deopt_suspend()) { 2455 thread->clear_deopt_suspend(); 2456 RegisterMap map(thread, false); 2457 frame f = thread->last_frame(); 2458 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2459 f = f.sender(&map); 2460 } 2461 if (f.id() == thread->must_deopt_id()) { 2462 thread->clear_must_deopt_id(); 2463 f.deoptimize(thread); 2464 } else { 2465 fatal("missed deoptimization!"); 2466 } 2467 } 2468 #if INCLUDE_TRACE 2469 if (thread->is_trace_suspend()) { 2470 TRACE_SUSPEND_THREAD(thread); 2471 } 2472 #endif 2473 } 2474 2475 // Slow path when the native==>VM/Java barriers detect a safepoint is in 2476 // progress or when _suspend_flags is non-zero. 2477 // Current thread needs to self-suspend if there is a suspend request and/or 2478 // block if a safepoint is in progress. 2479 // Also check for pending async exception (not including unsafe access error). 2480 // Note only the native==>VM/Java barriers can call this function and when 2481 // thread state is _thread_in_native_trans. 2482 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2483 check_safepoint_and_suspend_for_native_trans(thread); 2484 2485 if (thread->has_async_exception()) { 2486 // We are in _thread_in_native_trans state, don't handle unsafe 2487 // access error since that may block. 2488 thread->check_and_handle_async_exceptions(false); 2489 } 2490 } 2491 2492 // This is a variant of the normal 2493 // check_special_condition_for_native_trans with slightly different 2494 // semantics for use by critical native wrappers. It does all the 2495 // normal checks but also performs the transition back into 2496 // thread_in_Java state. This is required so that critical natives 2497 // can potentially block and perform a GC if they are the last thread 2498 // exiting the GCLocker. 2499 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { 2500 check_special_condition_for_native_trans(thread); 2501 2502 // Finish the transition 2503 thread->set_thread_state(_thread_in_Java); 2504 2505 if (thread->do_critical_native_unlock()) { 2506 ThreadInVMfromJavaNoAsyncException tiv(thread); 2507 GCLocker::unlock_critical(thread); 2508 thread->clear_critical_native_unlock(); 2509 } 2510 } 2511 2512 // We need to guarantee the Threads_lock here, since resumes are not 2513 // allowed during safepoint synchronization 2514 // Can only resume from an external suspension 2515 void JavaThread::java_resume() { 2516 assert_locked_or_safepoint(Threads_lock); 2517 2518 // Sanity check: thread is gone, has started exiting or the thread 2519 // was not externally suspended. 2520 ThreadsListHandle tlh; 2521 if (!tlh.includes(this) || is_exiting() || !is_external_suspend()) { 2522 return; 2523 } 2524 2525 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2526 2527 clear_external_suspend(); 2528 2529 if (is_ext_suspended()) { 2530 clear_ext_suspended(); 2531 SR_lock()->notify_all(); 2532 } 2533 } 2534 2535 size_t JavaThread::_stack_red_zone_size = 0; 2536 size_t JavaThread::_stack_yellow_zone_size = 0; 2537 size_t JavaThread::_stack_reserved_zone_size = 0; 2538 size_t JavaThread::_stack_shadow_zone_size = 0; 2539 2540 void JavaThread::create_stack_guard_pages() { 2541 if (!os::uses_stack_guard_pages() || 2542 _stack_guard_state != stack_guard_unused || 2543 (DisablePrimordialThreadGuardPages && os::is_primordial_thread())) { 2544 log_info(os, thread)("Stack guard page creation for thread " 2545 UINTX_FORMAT " disabled", os::current_thread_id()); 2546 return; 2547 } 2548 address low_addr = stack_end(); 2549 size_t len = stack_guard_zone_size(); 2550 2551 assert(is_aligned(low_addr, os::vm_page_size()), "Stack base should be the start of a page"); 2552 assert(is_aligned(len, os::vm_page_size()), "Stack size should be a multiple of page size"); 2553 2554 int must_commit = os::must_commit_stack_guard_pages(); 2555 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2556 2557 if (must_commit && !os::create_stack_guard_pages((char *) low_addr, len)) { 2558 log_warning(os, thread)("Attempt to allocate stack guard pages failed."); 2559 return; 2560 } 2561 2562 if (os::guard_memory((char *) low_addr, len)) { 2563 _stack_guard_state = stack_guard_enabled; 2564 } else { 2565 log_warning(os, thread)("Attempt to protect stack guard pages failed (" 2566 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2567 if (os::uncommit_memory((char *) low_addr, len)) { 2568 log_warning(os, thread)("Attempt to deallocate stack guard pages failed."); 2569 } 2570 return; 2571 } 2572 2573 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages activated: " 2574 PTR_FORMAT "-" PTR_FORMAT ".", 2575 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2576 } 2577 2578 void JavaThread::remove_stack_guard_pages() { 2579 assert(Thread::current() == this, "from different thread"); 2580 if (_stack_guard_state == stack_guard_unused) return; 2581 address low_addr = stack_end(); 2582 size_t len = stack_guard_zone_size(); 2583 2584 if (os::must_commit_stack_guard_pages()) { 2585 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2586 _stack_guard_state = stack_guard_unused; 2587 } else { 2588 log_warning(os, thread)("Attempt to deallocate stack guard pages failed (" 2589 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2590 return; 2591 } 2592 } else { 2593 if (_stack_guard_state == stack_guard_unused) return; 2594 if (os::unguard_memory((char *) low_addr, len)) { 2595 _stack_guard_state = stack_guard_unused; 2596 } else { 2597 log_warning(os, thread)("Attempt to unprotect stack guard pages failed (" 2598 PTR_FORMAT "-" PTR_FORMAT ").", p2i(low_addr), p2i(low_addr + len)); 2599 return; 2600 } 2601 } 2602 2603 log_debug(os, thread)("Thread " UINTX_FORMAT " stack guard pages removed: " 2604 PTR_FORMAT "-" PTR_FORMAT ".", 2605 os::current_thread_id(), p2i(low_addr), p2i(low_addr + len)); 2606 } 2607 2608 void JavaThread::enable_stack_reserved_zone() { 2609 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2610 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2611 2612 // The base notation is from the stack's point of view, growing downward. 2613 // We need to adjust it to work correctly with guard_memory() 2614 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2615 2616 guarantee(base < stack_base(),"Error calculating stack reserved zone"); 2617 guarantee(base < os::current_stack_pointer(),"Error calculating stack reserved zone"); 2618 2619 if (os::guard_memory((char *) base, stack_reserved_zone_size())) { 2620 _stack_guard_state = stack_guard_enabled; 2621 } else { 2622 warning("Attempt to guard stack reserved zone failed."); 2623 } 2624 enable_register_stack_guard(); 2625 } 2626 2627 void JavaThread::disable_stack_reserved_zone() { 2628 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2629 assert(_stack_guard_state != stack_guard_reserved_disabled, "already disabled"); 2630 2631 // Simply return if called for a thread that does not use guard pages. 2632 if (_stack_guard_state == stack_guard_unused) return; 2633 2634 // The base notation is from the stack's point of view, growing downward. 2635 // We need to adjust it to work correctly with guard_memory() 2636 address base = stack_reserved_zone_base() - stack_reserved_zone_size(); 2637 2638 if (os::unguard_memory((char *)base, stack_reserved_zone_size())) { 2639 _stack_guard_state = stack_guard_reserved_disabled; 2640 } else { 2641 warning("Attempt to unguard stack reserved zone failed."); 2642 } 2643 disable_register_stack_guard(); 2644 } 2645 2646 void JavaThread::enable_stack_yellow_reserved_zone() { 2647 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2648 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2649 2650 // The base notation is from the stacks point of view, growing downward. 2651 // We need to adjust it to work correctly with guard_memory() 2652 address base = stack_red_zone_base(); 2653 2654 guarantee(base < stack_base(), "Error calculating stack yellow zone"); 2655 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone"); 2656 2657 if (os::guard_memory((char *) base, stack_yellow_reserved_zone_size())) { 2658 _stack_guard_state = stack_guard_enabled; 2659 } else { 2660 warning("Attempt to guard stack yellow zone failed."); 2661 } 2662 enable_register_stack_guard(); 2663 } 2664 2665 void JavaThread::disable_stack_yellow_reserved_zone() { 2666 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2667 assert(_stack_guard_state != stack_guard_yellow_reserved_disabled, "already disabled"); 2668 2669 // Simply return if called for a thread that does not use guard pages. 2670 if (_stack_guard_state == stack_guard_unused) return; 2671 2672 // The base notation is from the stacks point of view, growing downward. 2673 // We need to adjust it to work correctly with guard_memory() 2674 address base = stack_red_zone_base(); 2675 2676 if (os::unguard_memory((char *)base, stack_yellow_reserved_zone_size())) { 2677 _stack_guard_state = stack_guard_yellow_reserved_disabled; 2678 } else { 2679 warning("Attempt to unguard stack yellow zone failed."); 2680 } 2681 disable_register_stack_guard(); 2682 } 2683 2684 void JavaThread::enable_stack_red_zone() { 2685 // The base notation is from the stacks point of view, growing downward. 2686 // We need to adjust it to work correctly with guard_memory() 2687 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2688 address base = stack_red_zone_base() - stack_red_zone_size(); 2689 2690 guarantee(base < stack_base(), "Error calculating stack red zone"); 2691 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone"); 2692 2693 if (!os::guard_memory((char *) base, stack_red_zone_size())) { 2694 warning("Attempt to guard stack red zone failed."); 2695 } 2696 } 2697 2698 void JavaThread::disable_stack_red_zone() { 2699 // The base notation is from the stacks point of view, growing downward. 2700 // We need to adjust it to work correctly with guard_memory() 2701 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2702 address base = stack_red_zone_base() - stack_red_zone_size(); 2703 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2704 warning("Attempt to unguard stack red zone failed."); 2705 } 2706 } 2707 2708 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2709 // ignore is there is no stack 2710 if (!has_last_Java_frame()) return; 2711 // traverse the stack frames. Starts from top frame. 2712 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2713 frame* fr = fst.current(); 2714 f(fr, fst.register_map()); 2715 } 2716 } 2717 2718 2719 #ifndef PRODUCT 2720 // Deoptimization 2721 // Function for testing deoptimization 2722 void JavaThread::deoptimize() { 2723 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2724 StackFrameStream fst(this, UseBiasedLocking); 2725 bool deopt = false; // Dump stack only if a deopt actually happens. 2726 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2727 // Iterate over all frames in the thread and deoptimize 2728 for (; !fst.is_done(); fst.next()) { 2729 if (fst.current()->can_be_deoptimized()) { 2730 2731 if (only_at) { 2732 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2733 // consists of comma or carriage return separated numbers so 2734 // search for the current bci in that string. 2735 address pc = fst.current()->pc(); 2736 nmethod* nm = (nmethod*) fst.current()->cb(); 2737 ScopeDesc* sd = nm->scope_desc_at(pc); 2738 char buffer[8]; 2739 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2740 size_t len = strlen(buffer); 2741 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2742 while (found != NULL) { 2743 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2744 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2745 // Check that the bci found is bracketed by terminators. 2746 break; 2747 } 2748 found = strstr(found + 1, buffer); 2749 } 2750 if (!found) { 2751 continue; 2752 } 2753 } 2754 2755 if (DebugDeoptimization && !deopt) { 2756 deopt = true; // One-time only print before deopt 2757 tty->print_cr("[BEFORE Deoptimization]"); 2758 trace_frames(); 2759 trace_stack(); 2760 } 2761 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2762 } 2763 } 2764 2765 if (DebugDeoptimization && deopt) { 2766 tty->print_cr("[AFTER Deoptimization]"); 2767 trace_frames(); 2768 } 2769 } 2770 2771 2772 // Make zombies 2773 void JavaThread::make_zombies() { 2774 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2775 if (fst.current()->can_be_deoptimized()) { 2776 // it is a Java nmethod 2777 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2778 nm->make_not_entrant(); 2779 } 2780 } 2781 } 2782 #endif // PRODUCT 2783 2784 2785 void JavaThread::deoptimized_wrt_marked_nmethods() { 2786 if (!has_last_Java_frame()) return; 2787 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2788 StackFrameStream fst(this, UseBiasedLocking); 2789 for (; !fst.is_done(); fst.next()) { 2790 if (fst.current()->should_be_deoptimized()) { 2791 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2792 } 2793 } 2794 } 2795 2796 2797 // If the caller is a NamedThread, then remember, in the current scope, 2798 // the given JavaThread in its _processed_thread field. 2799 class RememberProcessedThread: public StackObj { 2800 NamedThread* _cur_thr; 2801 public: 2802 RememberProcessedThread(JavaThread* jthr) { 2803 Thread* thread = Thread::current(); 2804 if (thread->is_Named_thread()) { 2805 _cur_thr = (NamedThread *)thread; 2806 _cur_thr->set_processed_thread(jthr); 2807 } else { 2808 _cur_thr = NULL; 2809 } 2810 } 2811 2812 ~RememberProcessedThread() { 2813 if (_cur_thr) { 2814 _cur_thr->set_processed_thread(NULL); 2815 } 2816 } 2817 }; 2818 2819 void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2820 // Verify that the deferred card marks have been flushed. 2821 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2822 2823 // Traverse the GCHandles 2824 Thread::oops_do(f, cf); 2825 2826 JVMCI_ONLY(f->do_oop((oop*)&_pending_failed_speculation);) 2827 2828 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2829 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2830 2831 if (has_last_Java_frame()) { 2832 // Record JavaThread to GC thread 2833 RememberProcessedThread rpt(this); 2834 2835 // Traverse the privileged stack 2836 if (_privileged_stack_top != NULL) { 2837 _privileged_stack_top->oops_do(f); 2838 } 2839 2840 // traverse the registered growable array 2841 if (_array_for_gc != NULL) { 2842 for (int index = 0; index < _array_for_gc->length(); index++) { 2843 f->do_oop(_array_for_gc->adr_at(index)); 2844 } 2845 } 2846 2847 // Traverse the monitor chunks 2848 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2849 chunk->oops_do(f); 2850 } 2851 2852 // Traverse the execution stack 2853 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2854 fst.current()->oops_do(f, cf, fst.register_map()); 2855 } 2856 } 2857 2858 // callee_target is never live across a gc point so NULL it here should 2859 // it still contain a methdOop. 2860 2861 set_callee_target(NULL); 2862 2863 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2864 // If we have deferred set_locals there might be oops waiting to be 2865 // written 2866 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2867 if (list != NULL) { 2868 for (int i = 0; i < list->length(); i++) { 2869 list->at(i)->oops_do(f); 2870 } 2871 } 2872 2873 // Traverse instance variables at the end since the GC may be moving things 2874 // around using this function 2875 f->do_oop((oop*) &_threadObj); 2876 f->do_oop((oop*) &_vm_result); 2877 f->do_oop((oop*) &_exception_oop); 2878 f->do_oop((oop*) &_pending_async_exception); 2879 2880 if (jvmti_thread_state() != NULL) { 2881 jvmti_thread_state()->oops_do(f); 2882 } 2883 } 2884 2885 void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2886 assert((!has_last_Java_frame() && java_call_counter() == 0) || 2887 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2888 2889 if (has_last_Java_frame()) { 2890 // Traverse the execution stack 2891 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2892 fst.current()->nmethods_do(cf); 2893 } 2894 } 2895 } 2896 2897 void JavaThread::metadata_do(void f(Metadata*)) { 2898 if (has_last_Java_frame()) { 2899 // Traverse the execution stack to call f() on the methods in the stack 2900 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2901 fst.current()->metadata_do(f); 2902 } 2903 } else if (is_Compiler_thread()) { 2904 // need to walk ciMetadata in current compile tasks to keep alive. 2905 CompilerThread* ct = (CompilerThread*)this; 2906 if (ct->env() != NULL) { 2907 ct->env()->metadata_do(f); 2908 } 2909 CompileTask* task = ct->task(); 2910 if (task != NULL) { 2911 task->metadata_do(f); 2912 } 2913 } 2914 } 2915 2916 // Printing 2917 const char* _get_thread_state_name(JavaThreadState _thread_state) { 2918 switch (_thread_state) { 2919 case _thread_uninitialized: return "_thread_uninitialized"; 2920 case _thread_new: return "_thread_new"; 2921 case _thread_new_trans: return "_thread_new_trans"; 2922 case _thread_in_native: return "_thread_in_native"; 2923 case _thread_in_native_trans: return "_thread_in_native_trans"; 2924 case _thread_in_vm: return "_thread_in_vm"; 2925 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2926 case _thread_in_Java: return "_thread_in_Java"; 2927 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2928 case _thread_blocked: return "_thread_blocked"; 2929 case _thread_blocked_trans: return "_thread_blocked_trans"; 2930 default: return "unknown thread state"; 2931 } 2932 } 2933 2934 #ifndef PRODUCT 2935 void JavaThread::print_thread_state_on(outputStream *st) const { 2936 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2937 }; 2938 void JavaThread::print_thread_state() const { 2939 print_thread_state_on(tty); 2940 } 2941 #endif // PRODUCT 2942 2943 // Called by Threads::print() for VM_PrintThreads operation 2944 void JavaThread::print_on(outputStream *st) const { 2945 st->print_raw("\""); 2946 st->print_raw(get_thread_name()); 2947 st->print_raw("\" "); 2948 oop thread_oop = threadObj(); 2949 if (thread_oop != NULL) { 2950 st->print("#" INT64_FORMAT " ", (int64_t)java_lang_Thread::thread_id(thread_oop)); 2951 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2952 st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); 2953 } 2954 Thread::print_on(st); 2955 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2956 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2957 if (thread_oop != NULL) { 2958 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2959 } 2960 #ifndef PRODUCT 2961 print_thread_state_on(st); 2962 _safepoint_state->print_on(st); 2963 #endif // PRODUCT 2964 if (is_Compiler_thread()) { 2965 CompileTask *task = ((CompilerThread*)this)->task(); 2966 if (task != NULL) { 2967 st->print(" Compiling: "); 2968 task->print(st, NULL, true, false); 2969 } else { 2970 st->print(" No compile task"); 2971 } 2972 st->cr(); 2973 } 2974 } 2975 2976 void JavaThread::print_name_on_error(outputStream* st, char *buf, int buflen) const { 2977 st->print("%s", get_thread_name_string(buf, buflen)); 2978 } 2979 2980 // Called by fatal error handler. The difference between this and 2981 // JavaThread::print() is that we can't grab lock or allocate memory. 2982 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2983 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2984 oop thread_obj = threadObj(); 2985 if (thread_obj != NULL) { 2986 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2987 } 2988 st->print(" ["); 2989 st->print("%s", _get_thread_state_name(_thread_state)); 2990 if (osthread()) { 2991 st->print(", id=%d", osthread()->thread_id()); 2992 } 2993 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2994 p2i(stack_end()), p2i(stack_base())); 2995 st->print("]"); 2996 2997 if (_threads_hazard_ptr != NULL) { 2998 st->print(" _threads_hazard_ptr=" INTPTR_FORMAT, p2i(_threads_hazard_ptr)); 2999 } 3000 if (_nested_threads_hazard_ptr != NULL) { 3001 print_nested_threads_hazard_ptrs_on(st); 3002 } 3003 return; 3004 } 3005 3006 // Verification 3007 3008 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 3009 3010 void JavaThread::verify() { 3011 // Verify oops in the thread. 3012 oops_do(&VerifyOopClosure::verify_oop, NULL); 3013 3014 // Verify the stack frames. 3015 frames_do(frame_verify); 3016 } 3017 3018 // CR 6300358 (sub-CR 2137150) 3019 // Most callers of this method assume that it can't return NULL but a 3020 // thread may not have a name whilst it is in the process of attaching to 3021 // the VM - see CR 6412693, and there are places where a JavaThread can be 3022 // seen prior to having it's threadObj set (eg JNI attaching threads and 3023 // if vm exit occurs during initialization). These cases can all be accounted 3024 // for such that this method never returns NULL. 3025 const char* JavaThread::get_thread_name() const { 3026 #ifdef ASSERT 3027 // early safepoints can hit while current thread does not yet have TLS 3028 if (!SafepointSynchronize::is_at_safepoint()) { 3029 Thread *cur = Thread::current(); 3030 if (!(cur->is_Java_thread() && cur == this)) { 3031 // Current JavaThreads are allowed to get their own name without 3032 // the Threads_lock. 3033 assert_locked_or_safepoint(Threads_lock); 3034 } 3035 } 3036 #endif // ASSERT 3037 return get_thread_name_string(); 3038 } 3039 3040 // Returns a non-NULL representation of this thread's name, or a suitable 3041 // descriptive string if there is no set name 3042 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 3043 const char* name_str; 3044 oop thread_obj = threadObj(); 3045 if (thread_obj != NULL) { 3046 oop name = java_lang_Thread::name(thread_obj); 3047 if (name != NULL) { 3048 if (buf == NULL) { 3049 name_str = java_lang_String::as_utf8_string(name); 3050 } else { 3051 name_str = java_lang_String::as_utf8_string(name, buf, buflen); 3052 } 3053 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 3054 name_str = "<no-name - thread is attaching>"; 3055 } else { 3056 name_str = Thread::name(); 3057 } 3058 } else { 3059 name_str = Thread::name(); 3060 } 3061 assert(name_str != NULL, "unexpected NULL thread name"); 3062 return name_str; 3063 } 3064 3065 3066 const char* JavaThread::get_threadgroup_name() const { 3067 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3068 oop thread_obj = threadObj(); 3069 if (thread_obj != NULL) { 3070 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3071 if (thread_group != NULL) { 3072 // ThreadGroup.name can be null 3073 return java_lang_ThreadGroup::name(thread_group); 3074 } 3075 } 3076 return NULL; 3077 } 3078 3079 const char* JavaThread::get_parent_name() const { 3080 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 3081 oop thread_obj = threadObj(); 3082 if (thread_obj != NULL) { 3083 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 3084 if (thread_group != NULL) { 3085 oop parent = java_lang_ThreadGroup::parent(thread_group); 3086 if (parent != NULL) { 3087 // ThreadGroup.name can be null 3088 return java_lang_ThreadGroup::name(parent); 3089 } 3090 } 3091 } 3092 return NULL; 3093 } 3094 3095 ThreadPriority JavaThread::java_priority() const { 3096 oop thr_oop = threadObj(); 3097 if (thr_oop == NULL) return NormPriority; // Bootstrapping 3098 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 3099 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 3100 return priority; 3101 } 3102 3103 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 3104 3105 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 3106 // Link Java Thread object <-> C++ Thread 3107 3108 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 3109 // and put it into a new Handle. The Handle "thread_oop" can then 3110 // be used to pass the C++ thread object to other methods. 3111 3112 // Set the Java level thread object (jthread) field of the 3113 // new thread (a JavaThread *) to C++ thread object using the 3114 // "thread_oop" handle. 3115 3116 // Set the thread field (a JavaThread *) of the 3117 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 3118 3119 Handle thread_oop(Thread::current(), 3120 JNIHandles::resolve_non_null(jni_thread)); 3121 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), 3122 "must be initialized"); 3123 set_threadObj(thread_oop()); 3124 java_lang_Thread::set_thread(thread_oop(), this); 3125 3126 if (prio == NoPriority) { 3127 prio = java_lang_Thread::priority(thread_oop()); 3128 assert(prio != NoPriority, "A valid priority should be present"); 3129 } 3130 3131 // Push the Java priority down to the native thread; needs Threads_lock 3132 Thread::set_priority(this, prio); 3133 3134 // Add the new thread to the Threads list and set it in motion. 3135 // We must have threads lock in order to call Threads::add. 3136 // It is crucial that we do not block before the thread is 3137 // added to the Threads list for if a GC happens, then the java_thread oop 3138 // will not be visited by GC. 3139 Threads::add(this); 3140 } 3141 3142 oop JavaThread::current_park_blocker() { 3143 // Support for JSR-166 locks 3144 oop thread_oop = threadObj(); 3145 if (thread_oop != NULL && 3146 JDK_Version::current().supports_thread_park_blocker()) { 3147 return java_lang_Thread::park_blocker(thread_oop); 3148 } 3149 return NULL; 3150 } 3151 3152 3153 void JavaThread::print_stack_on(outputStream* st) { 3154 if (!has_last_Java_frame()) return; 3155 ResourceMark rm; 3156 HandleMark hm; 3157 3158 RegisterMap reg_map(this); 3159 vframe* start_vf = last_java_vframe(®_map); 3160 int count = 0; 3161 for (vframe* f = start_vf; f != NULL; f = f->sender()) { 3162 if (f->is_java_frame()) { 3163 javaVFrame* jvf = javaVFrame::cast(f); 3164 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 3165 3166 // Print out lock information 3167 if (JavaMonitorsInStackTrace) { 3168 jvf->print_lock_info_on(st, count); 3169 } 3170 } else { 3171 // Ignore non-Java frames 3172 } 3173 3174 // Bail-out case for too deep stacks if MaxJavaStackTraceDepth > 0 3175 count++; 3176 if (MaxJavaStackTraceDepth > 0 && MaxJavaStackTraceDepth == count) return; 3177 } 3178 } 3179 3180 3181 // JVMTI PopFrame support 3182 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 3183 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 3184 if (in_bytes(size_in_bytes) != 0) { 3185 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); 3186 _popframe_preserved_args_size = in_bytes(size_in_bytes); 3187 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 3188 } 3189 } 3190 3191 void* JavaThread::popframe_preserved_args() { 3192 return _popframe_preserved_args; 3193 } 3194 3195 ByteSize JavaThread::popframe_preserved_args_size() { 3196 return in_ByteSize(_popframe_preserved_args_size); 3197 } 3198 3199 WordSize JavaThread::popframe_preserved_args_size_in_words() { 3200 int sz = in_bytes(popframe_preserved_args_size()); 3201 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 3202 return in_WordSize(sz / wordSize); 3203 } 3204 3205 void JavaThread::popframe_free_preserved_args() { 3206 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 3207 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 3208 _popframe_preserved_args = NULL; 3209 _popframe_preserved_args_size = 0; 3210 } 3211 3212 #ifndef PRODUCT 3213 3214 void JavaThread::trace_frames() { 3215 tty->print_cr("[Describe stack]"); 3216 int frame_no = 1; 3217 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) { 3218 tty->print(" %d. ", frame_no++); 3219 fst.current()->print_value_on(tty, this); 3220 tty->cr(); 3221 } 3222 } 3223 3224 class PrintAndVerifyOopClosure: public OopClosure { 3225 protected: 3226 template <class T> inline void do_oop_work(T* p) { 3227 oop obj = RawAccess<>::oop_load(p); 3228 if (obj == NULL) return; 3229 tty->print(INTPTR_FORMAT ": ", p2i(p)); 3230 if (oopDesc::is_oop_or_null(obj)) { 3231 if (obj->is_objArray()) { 3232 tty->print_cr("valid objArray: " INTPTR_FORMAT, p2i(obj)); 3233 } else { 3234 obj->print(); 3235 } 3236 } else { 3237 tty->print_cr("invalid oop: " INTPTR_FORMAT, p2i(obj)); 3238 } 3239 tty->cr(); 3240 } 3241 public: 3242 virtual void do_oop(oop* p) { do_oop_work(p); } 3243 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 3244 }; 3245 3246 3247 static void oops_print(frame* f, const RegisterMap *map) { 3248 PrintAndVerifyOopClosure print; 3249 f->print_value(); 3250 f->oops_do(&print, NULL, (RegisterMap*)map); 3251 } 3252 3253 // Print our all the locations that contain oops and whether they are 3254 // valid or not. This useful when trying to find the oldest frame 3255 // where an oop has gone bad since the frame walk is from youngest to 3256 // oldest. 3257 void JavaThread::trace_oops() { 3258 tty->print_cr("[Trace oops]"); 3259 frames_do(oops_print); 3260 } 3261 3262 3263 #ifdef ASSERT 3264 // Print or validate the layout of stack frames 3265 void JavaThread::print_frame_layout(int depth, bool validate_only) { 3266 ResourceMark rm; 3267 PRESERVE_EXCEPTION_MARK; 3268 FrameValues values; 3269 int frame_no = 0; 3270 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { 3271 fst.current()->describe(values, ++frame_no); 3272 if (depth == frame_no) break; 3273 } 3274 if (validate_only) { 3275 values.validate(); 3276 } else { 3277 tty->print_cr("[Describe stack layout]"); 3278 values.print(this); 3279 } 3280 } 3281 #endif 3282 3283 void JavaThread::trace_stack_from(vframe* start_vf) { 3284 ResourceMark rm; 3285 int vframe_no = 1; 3286 for (vframe* f = start_vf; f; f = f->sender()) { 3287 if (f->is_java_frame()) { 3288 javaVFrame::cast(f)->print_activation(vframe_no++); 3289 } else { 3290 f->print(); 3291 } 3292 if (vframe_no > StackPrintLimit) { 3293 tty->print_cr("...<more frames>..."); 3294 return; 3295 } 3296 } 3297 } 3298 3299 3300 void JavaThread::trace_stack() { 3301 if (!has_last_Java_frame()) return; 3302 ResourceMark rm; 3303 HandleMark hm; 3304 RegisterMap reg_map(this); 3305 trace_stack_from(last_java_vframe(®_map)); 3306 } 3307 3308 3309 #endif // PRODUCT 3310 3311 3312 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 3313 assert(reg_map != NULL, "a map must be given"); 3314 frame f = last_frame(); 3315 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) { 3316 if (vf->is_java_frame()) return javaVFrame::cast(vf); 3317 } 3318 return NULL; 3319 } 3320 3321 3322 Klass* JavaThread::security_get_caller_class(int depth) { 3323 vframeStream vfst(this); 3324 vfst.security_get_caller_frame(depth); 3325 if (!vfst.at_end()) { 3326 return vfst.method()->method_holder(); 3327 } 3328 return NULL; 3329 } 3330 3331 static void compiler_thread_entry(JavaThread* thread, TRAPS) { 3332 assert(thread->is_Compiler_thread(), "must be compiler thread"); 3333 CompileBroker::compiler_thread_loop(); 3334 } 3335 3336 static void sweeper_thread_entry(JavaThread* thread, TRAPS) { 3337 NMethodSweeper::sweeper_loop(); 3338 } 3339 3340 // Create a CompilerThread 3341 CompilerThread::CompilerThread(CompileQueue* queue, 3342 CompilerCounters* counters) 3343 : JavaThread(&compiler_thread_entry) { 3344 _env = NULL; 3345 _log = NULL; 3346 _task = NULL; 3347 _queue = queue; 3348 _counters = counters; 3349 _buffer_blob = NULL; 3350 _compiler = NULL; 3351 3352 // Compiler uses resource area for compilation, let's bias it to mtCompiler 3353 resource_area()->bias_to(mtCompiler); 3354 3355 #ifndef PRODUCT 3356 _ideal_graph_printer = NULL; 3357 #endif 3358 } 3359 3360 bool CompilerThread::can_call_java() const { 3361 return _compiler != NULL && _compiler->is_jvmci(); 3362 } 3363 3364 // Create sweeper thread 3365 CodeCacheSweeperThread::CodeCacheSweeperThread() 3366 : JavaThread(&sweeper_thread_entry) { 3367 _scanned_compiled_method = NULL; 3368 } 3369 3370 void CodeCacheSweeperThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3371 JavaThread::oops_do(f, cf); 3372 if (_scanned_compiled_method != NULL && cf != NULL) { 3373 // Safepoints can occur when the sweeper is scanning an nmethod so 3374 // process it here to make sure it isn't unloaded in the middle of 3375 // a scan. 3376 cf->do_code_blob(_scanned_compiled_method); 3377 } 3378 } 3379 3380 void CodeCacheSweeperThread::nmethods_do(CodeBlobClosure* cf) { 3381 JavaThread::nmethods_do(cf); 3382 if (_scanned_compiled_method != NULL && cf != NULL) { 3383 // Safepoints can occur when the sweeper is scanning an nmethod so 3384 // process it here to make sure it isn't unloaded in the middle of 3385 // a scan. 3386 cf->do_code_blob(_scanned_compiled_method); 3387 } 3388 } 3389 3390 3391 // ======= Threads ======== 3392 3393 // The Threads class links together all active threads, and provides 3394 // operations over all threads. It is protected by the Threads_lock, 3395 // which is also used in other global contexts like safepointing. 3396 // ThreadsListHandles are used to safely perform operations on one 3397 // or more threads without the risk of the thread exiting during the 3398 // operation. 3399 // 3400 // Note: The Threads_lock is currently more widely used than we 3401 // would like. We are actively migrating Threads_lock uses to other 3402 // mechanisms in order to reduce Threads_lock contention. 3403 3404 JavaThread* Threads::_thread_list = NULL; 3405 int Threads::_number_of_threads = 0; 3406 int Threads::_number_of_non_daemon_threads = 0; 3407 int Threads::_return_code = 0; 3408 int Threads::_thread_claim_parity = 0; 3409 size_t JavaThread::_stack_size_at_create = 0; 3410 3411 #ifdef ASSERT 3412 bool Threads::_vm_complete = false; 3413 #endif 3414 3415 static inline void *prefetch_and_load_ptr(void **addr, intx prefetch_interval) { 3416 Prefetch::read((void*)addr, prefetch_interval); 3417 return *addr; 3418 } 3419 3420 // Possibly the ugliest for loop the world has seen. C++ does not allow 3421 // multiple types in the declaration section of the for loop. In this case 3422 // we are only dealing with pointers and hence can cast them. It looks ugly 3423 // but macros are ugly and therefore it's fine to make things absurdly ugly. 3424 #define DO_JAVA_THREADS(LIST, X) \ 3425 for (JavaThread *MACRO_scan_interval = (JavaThread*)(uintptr_t)PrefetchScanIntervalInBytes, \ 3426 *MACRO_list = (JavaThread*)(LIST), \ 3427 **MACRO_end = ((JavaThread**)((ThreadsList*)MACRO_list)->threads()) + ((ThreadsList*)MACRO_list)->length(), \ 3428 **MACRO_current_p = (JavaThread**)((ThreadsList*)MACRO_list)->threads(), \ 3429 *X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval); \ 3430 MACRO_current_p != MACRO_end; \ 3431 MACRO_current_p++, \ 3432 X = (JavaThread*)prefetch_and_load_ptr((void**)MACRO_current_p, (intx)MACRO_scan_interval)) 3433 3434 // All JavaThreads 3435 #define ALL_JAVA_THREADS(X) DO_JAVA_THREADS(ThreadsSMRSupport::get_java_thread_list(), X) 3436 3437 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 3438 void Threads::threads_do(ThreadClosure* tc) { 3439 assert_locked_or_safepoint(Threads_lock); 3440 // ALL_JAVA_THREADS iterates through all JavaThreads 3441 ALL_JAVA_THREADS(p) { 3442 tc->do_thread(p); 3443 } 3444 // Someday we could have a table or list of all non-JavaThreads. 3445 // For now, just manually iterate through them. 3446 tc->do_thread(VMThread::vm_thread()); 3447 Universe::heap()->gc_threads_do(tc); 3448 WatcherThread *wt = WatcherThread::watcher_thread(); 3449 // Strictly speaking, the following NULL check isn't sufficient to make sure 3450 // the data for WatcherThread is still valid upon being examined. However, 3451 // considering that WatchThread terminates when the VM is on the way to 3452 // exit at safepoint, the chance of the above is extremely small. The right 3453 // way to prevent termination of WatcherThread would be to acquire 3454 // Terminator_lock, but we can't do that without violating the lock rank 3455 // checking in some cases. 3456 if (wt != NULL) { 3457 tc->do_thread(wt); 3458 } 3459 3460 // If CompilerThreads ever become non-JavaThreads, add them here 3461 } 3462 3463 void Threads::possibly_parallel_threads_do(bool is_par, ThreadClosure* tc) { 3464 int cp = Threads::thread_claim_parity(); 3465 ALL_JAVA_THREADS(p) { 3466 if (p->claim_oops_do(is_par, cp)) { 3467 tc->do_thread(p); 3468 } 3469 } 3470 VMThread* vmt = VMThread::vm_thread(); 3471 if (vmt->claim_oops_do(is_par, cp)) { 3472 tc->do_thread(vmt); 3473 } 3474 } 3475 3476 // The system initialization in the library has three phases. 3477 // 3478 // Phase 1: java.lang.System class initialization 3479 // java.lang.System is a primordial class loaded and initialized 3480 // by the VM early during startup. java.lang.System.<clinit> 3481 // only does registerNatives and keeps the rest of the class 3482 // initialization work later until thread initialization completes. 3483 // 3484 // System.initPhase1 initializes the system properties, the static 3485 // fields in, out, and err. Set up java signal handlers, OS-specific 3486 // system settings, and thread group of the main thread. 3487 static void call_initPhase1(TRAPS) { 3488 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3489 JavaValue result(T_VOID); 3490 JavaCalls::call_static(&result, klass, vmSymbols::initPhase1_name(), 3491 vmSymbols::void_method_signature(), CHECK); 3492 } 3493 3494 // Phase 2. Module system initialization 3495 // This will initialize the module system. Only java.base classes 3496 // can be loaded until phase 2 completes. 3497 // 3498 // Call System.initPhase2 after the compiler initialization and jsr292 3499 // classes get initialized because module initialization runs a lot of java 3500 // code, that for performance reasons, should be compiled. Also, this will 3501 // enable the startup code to use lambda and other language features in this 3502 // phase and onward. 3503 // 3504 // After phase 2, The VM will begin search classes from -Xbootclasspath/a. 3505 static void call_initPhase2(TRAPS) { 3506 TraceTime timer("Initialize module system", TRACETIME_LOG(Info, startuptime)); 3507 3508 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3509 3510 JavaValue result(T_INT); 3511 JavaCallArguments args; 3512 args.push_int(DisplayVMOutputToStderr); 3513 args.push_int(log_is_enabled(Debug, init)); // print stack trace if exception thrown 3514 JavaCalls::call_static(&result, klass, vmSymbols::initPhase2_name(), 3515 vmSymbols::boolean_boolean_int_signature(), &args, CHECK); 3516 if (result.get_jint() != JNI_OK) { 3517 vm_exit_during_initialization(); // no message or exception 3518 } 3519 3520 universe_post_module_init(); 3521 } 3522 3523 // Phase 3. final setup - set security manager, system class loader and TCCL 3524 // 3525 // This will instantiate and set the security manager, set the system class 3526 // loader as well as the thread context class loader. The security manager 3527 // and system class loader may be a custom class loaded from -Xbootclasspath/a, 3528 // other modules or the application's classpath. 3529 static void call_initPhase3(TRAPS) { 3530 Klass* klass = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 3531 JavaValue result(T_VOID); 3532 JavaCalls::call_static(&result, klass, vmSymbols::initPhase3_name(), 3533 vmSymbols::void_method_signature(), CHECK); 3534 } 3535 3536 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) { 3537 TraceTime timer("Initialize java.lang classes", TRACETIME_LOG(Info, startuptime)); 3538 3539 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3540 create_vm_init_libraries(); 3541 } 3542 3543 initialize_class(vmSymbols::java_lang_String(), CHECK); 3544 3545 // Inject CompactStrings value after the static initializers for String ran. 3546 java_lang_String::set_compact_strings(CompactStrings); 3547 3548 // Initialize java_lang.System (needed before creating the thread) 3549 initialize_class(vmSymbols::java_lang_System(), CHECK); 3550 // The VM creates & returns objects of this class. Make sure it's initialized. 3551 initialize_class(vmSymbols::java_lang_Class(), CHECK); 3552 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK); 3553 Handle thread_group = create_initial_thread_group(CHECK); 3554 Universe::set_main_thread_group(thread_group()); 3555 initialize_class(vmSymbols::java_lang_Thread(), CHECK); 3556 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK); 3557 main_thread->set_threadObj(thread_object); 3558 // Set thread status to running since main thread has 3559 // been started and running. 3560 java_lang_Thread::set_thread_status(thread_object, 3561 java_lang_Thread::RUNNABLE); 3562 3563 // The VM creates objects of this class. 3564 initialize_class(vmSymbols::java_lang_Module(), CHECK); 3565 3566 // The VM preresolves methods to these classes. Make sure that they get initialized 3567 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK); 3568 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK); 3569 3570 // Phase 1 of the system initialization in the library, java.lang.System class initialization 3571 call_initPhase1(CHECK); 3572 3573 // get the Java runtime name after java.lang.System is initialized 3574 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); 3575 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); 3576 3577 // an instance of OutOfMemory exception has been allocated earlier 3578 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK); 3579 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK); 3580 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK); 3581 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK); 3582 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK); 3583 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK); 3584 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK); 3585 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK); 3586 } 3587 3588 void Threads::initialize_jsr292_core_classes(TRAPS) { 3589 TraceTime timer("Initialize java.lang.invoke classes", TRACETIME_LOG(Info, startuptime)); 3590 3591 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK); 3592 initialize_class(vmSymbols::java_lang_invoke_ResolvedMethodName(), CHECK); 3593 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK); 3594 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK); 3595 } 3596 3597 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 3598 extern void JDK_Version_init(); 3599 3600 // Preinitialize version info. 3601 VM_Version::early_initialize(); 3602 3603 // Check version 3604 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 3605 3606 // Initialize library-based TLS 3607 ThreadLocalStorage::init(); 3608 3609 // Initialize the output stream module 3610 ostream_init(); 3611 3612 // Process java launcher properties. 3613 Arguments::process_sun_java_launcher_properties(args); 3614 3615 // Initialize the os module 3616 os::init(); 3617 3618 // Record VM creation timing statistics 3619 TraceVmCreationTime create_vm_timer; 3620 create_vm_timer.start(); 3621 3622 // Initialize system properties. 3623 Arguments::init_system_properties(); 3624 3625 // So that JDK version can be used as a discriminator when parsing arguments 3626 JDK_Version_init(); 3627 3628 // Update/Initialize System properties after JDK version number is known 3629 Arguments::init_version_specific_system_properties(); 3630 3631 // Make sure to initialize log configuration *before* parsing arguments 3632 LogConfiguration::initialize(create_vm_timer.begin_time()); 3633 3634 // Parse arguments 3635 // Note: this internally calls os::init_container_support() 3636 jint parse_result = Arguments::parse(args); 3637 if (parse_result != JNI_OK) return parse_result; 3638 3639 os::init_before_ergo(); 3640 3641 jint ergo_result = Arguments::apply_ergo(); 3642 if (ergo_result != JNI_OK) return ergo_result; 3643 3644 // Final check of all ranges after ergonomics which may change values. 3645 if (!CommandLineFlagRangeList::check_ranges()) { 3646 return JNI_EINVAL; 3647 } 3648 3649 // Final check of all 'AfterErgo' constraints after ergonomics which may change values. 3650 bool constraint_result = CommandLineFlagConstraintList::check_constraints(CommandLineFlagConstraint::AfterErgo); 3651 if (!constraint_result) { 3652 return JNI_EINVAL; 3653 } 3654 3655 CommandLineFlagWriteableList::mark_startup(); 3656 3657 if (PauseAtStartup) { 3658 os::pause(); 3659 } 3660 3661 HOTSPOT_VM_INIT_BEGIN(); 3662 3663 // Timing (must come after argument parsing) 3664 TraceTime timer("Create VM", TRACETIME_LOG(Info, startuptime)); 3665 3666 #ifdef CAN_SHOW_REGISTERS_ON_ASSERT 3667 // Initialize assert poison page mechanism. 3668 if (ShowRegistersOnAssert) { 3669 initialize_assert_poison(); 3670 } 3671 #endif // CAN_SHOW_REGISTERS_ON_ASSERT 3672 3673 // Initialize the os module after parsing the args 3674 jint os_init_2_result = os::init_2(); 3675 if (os_init_2_result != JNI_OK) return os_init_2_result; 3676 3677 SafepointMechanism::initialize(); 3678 3679 jint adjust_after_os_result = Arguments::adjust_after_os(); 3680 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; 3681 3682 // Initialize output stream logging 3683 ostream_init_log(); 3684 3685 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3686 // Must be before create_vm_init_agents() 3687 if (Arguments::init_libraries_at_startup()) { 3688 convert_vm_init_libraries_to_agents(); 3689 } 3690 3691 // Launch -agentlib/-agentpath and converted -Xrun agents 3692 if (Arguments::init_agents_at_startup()) { 3693 create_vm_init_agents(); 3694 } 3695 3696 // Initialize Threads state 3697 _thread_list = NULL; 3698 _number_of_threads = 0; 3699 _number_of_non_daemon_threads = 0; 3700 3701 // Initialize global data structures and create system classes in heap 3702 vm_init_globals(); 3703 3704 #if INCLUDE_JVMCI 3705 if (JVMCICounterSize > 0) { 3706 JavaThread::_jvmci_old_thread_counters = NEW_C_HEAP_ARRAY(jlong, JVMCICounterSize, mtInternal); 3707 memset(JavaThread::_jvmci_old_thread_counters, 0, sizeof(jlong) * JVMCICounterSize); 3708 } else { 3709 JavaThread::_jvmci_old_thread_counters = NULL; 3710 } 3711 #endif // INCLUDE_JVMCI 3712 3713 // Attach the main thread to this os thread 3714 JavaThread* main_thread = new JavaThread(); 3715 main_thread->set_thread_state(_thread_in_vm); 3716 main_thread->initialize_thread_current(); 3717 // must do this before set_active_handles 3718 main_thread->record_stack_base_and_size(); 3719 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3720 3721 if (!main_thread->set_as_starting_thread()) { 3722 vm_shutdown_during_initialization( 3723 "Failed necessary internal allocation. Out of swap space"); 3724 main_thread->smr_delete(); 3725 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3726 return JNI_ENOMEM; 3727 } 3728 3729 // Enable guard page *after* os::create_main_thread(), otherwise it would 3730 // crash Linux VM, see notes in os_linux.cpp. 3731 main_thread->create_stack_guard_pages(); 3732 3733 // Initialize Java-Level synchronization subsystem 3734 ObjectMonitor::Initialize(); 3735 3736 // Initialize global modules 3737 jint status = init_globals(); 3738 if (status != JNI_OK) { 3739 main_thread->smr_delete(); 3740 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3741 return status; 3742 } 3743 3744 if (TRACE_INITIALIZE() != JNI_OK) { 3745 vm_exit_during_initialization("Failed to initialize tracing backend"); 3746 } 3747 3748 // Should be done after the heap is fully created 3749 main_thread->cache_global_variables(); 3750 3751 HandleMark hm; 3752 3753 { MutexLocker mu(Threads_lock); 3754 Threads::add(main_thread); 3755 } 3756 3757 // Any JVMTI raw monitors entered in onload will transition into 3758 // real raw monitor. VM is setup enough here for raw monitor enter. 3759 JvmtiExport::transition_pending_onload_raw_monitors(); 3760 3761 // Create the VMThread 3762 { TraceTime timer("Start VMThread", TRACETIME_LOG(Info, startuptime)); 3763 3764 VMThread::create(); 3765 Thread* vmthread = VMThread::vm_thread(); 3766 3767 if (!os::create_thread(vmthread, os::vm_thread)) { 3768 vm_exit_during_initialization("Cannot create VM thread. " 3769 "Out of system resources."); 3770 } 3771 3772 // Wait for the VM thread to become ready, and VMThread::run to initialize 3773 // Monitors can have spurious returns, must always check another state flag 3774 { 3775 MutexLocker ml(Notify_lock); 3776 os::start_thread(vmthread); 3777 while (vmthread->active_handles() == NULL) { 3778 Notify_lock->wait(); 3779 } 3780 } 3781 } 3782 3783 assert(Universe::is_fully_initialized(), "not initialized"); 3784 if (VerifyDuringStartup) { 3785 // Make sure we're starting with a clean slate. 3786 VM_Verify verify_op; 3787 VMThread::execute(&verify_op); 3788 } 3789 3790 Thread* THREAD = Thread::current(); 3791 3792 // Always call even when there are not JVMTI environments yet, since environments 3793 // may be attached late and JVMTI must track phases of VM execution 3794 JvmtiExport::enter_early_start_phase(); 3795 3796 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3797 JvmtiExport::post_early_vm_start(); 3798 3799 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR); 3800 3801 // We need this for ClassDataSharing - the initial vm.info property is set 3802 // with the default value of CDS "sharing" which may be reset through 3803 // command line options. 3804 reset_vm_info_property(CHECK_JNI_ERR); 3805 3806 quicken_jni_functions(); 3807 3808 // No more stub generation allowed after that point. 3809 StubCodeDesc::freeze(); 3810 3811 // Set flag that basic initialization has completed. Used by exceptions and various 3812 // debug stuff, that does not work until all basic classes have been initialized. 3813 set_init_completed(); 3814 3815 LogConfiguration::post_initialize(); 3816 Metaspace::post_initialize(); 3817 3818 HOTSPOT_VM_INIT_END(); 3819 3820 // record VM initialization completion time 3821 #if INCLUDE_MANAGEMENT 3822 Management::record_vm_init_completed(); 3823 #endif // INCLUDE_MANAGEMENT 3824 3825 // Signal Dispatcher needs to be started before VMInit event is posted 3826 os::signal_init(CHECK_JNI_ERR); 3827 3828 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3829 if (!DisableAttachMechanism) { 3830 AttachListener::vm_start(); 3831 if (StartAttachListener || AttachListener::init_at_startup()) { 3832 AttachListener::init(); 3833 } 3834 } 3835 3836 // Launch -Xrun agents 3837 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3838 // back-end can launch with -Xdebug -Xrunjdwp. 3839 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3840 create_vm_init_libraries(); 3841 } 3842 3843 if (CleanChunkPoolAsync) { 3844 Chunk::start_chunk_pool_cleaner_task(); 3845 } 3846 3847 // initialize compiler(s) 3848 #if defined(COMPILER1) || COMPILER2_OR_JVMCI 3849 #if INCLUDE_JVMCI 3850 bool force_JVMCI_intialization = false; 3851 if (EnableJVMCI) { 3852 // Initialize JVMCI eagerly when it is explicitly requested. 3853 // Or when JVMCIPrintProperties is enabled. 3854 // The JVMCI Java initialization code will read this flag and 3855 // do the printing if it's set. 3856 force_JVMCI_intialization = EagerJVMCI || JVMCIPrintProperties; 3857 3858 if (!force_JVMCI_intialization) { 3859 // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking 3860 // compilations via JVMCI will not actually block until JVMCI is initialized. 3861 force_JVMCI_intialization = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation); 3862 } 3863 } 3864 #endif 3865 CompileBroker::compilation_init_phase1(CHECK_JNI_ERR); 3866 // Postpone completion of compiler initialization to after JVMCI 3867 // is initialized to avoid timeouts of blocking compilations. 3868 if (JVMCI_ONLY(!force_JVMCI_intialization) NOT_JVMCI(true)) { 3869 CompileBroker::compilation_init_phase2(); 3870 } 3871 #endif 3872 3873 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. 3874 // It is done after compilers are initialized, because otherwise compilations of 3875 // signature polymorphic MH intrinsics can be missed 3876 // (see SystemDictionary::find_method_handle_intrinsic). 3877 initialize_jsr292_core_classes(CHECK_JNI_ERR); 3878 3879 // This will initialize the module system. Only java.base classes can be 3880 // loaded until phase 2 completes 3881 call_initPhase2(CHECK_JNI_ERR); 3882 3883 // Always call even when there are not JVMTI environments yet, since environments 3884 // may be attached late and JVMTI must track phases of VM execution 3885 JvmtiExport::enter_start_phase(); 3886 3887 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3888 JvmtiExport::post_vm_start(); 3889 3890 // Final system initialization including security manager and system class loader 3891 call_initPhase3(CHECK_JNI_ERR); 3892 3893 // cache the system and platform class loaders 3894 SystemDictionary::compute_java_loaders(CHECK_JNI_ERR); 3895 3896 #if INCLUDE_JVMCI 3897 if (force_JVMCI_intialization) { 3898 JVMCIRuntime::force_initialization(CHECK_JNI_ERR); 3899 CompileBroker::compilation_init_phase2(); 3900 } 3901 #endif 3902 3903 // Always call even when there are not JVMTI environments yet, since environments 3904 // may be attached late and JVMTI must track phases of VM execution 3905 JvmtiExport::enter_live_phase(); 3906 3907 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3908 JvmtiExport::post_vm_initialized(); 3909 3910 if (TRACE_START() != JNI_OK) { 3911 vm_exit_during_initialization("Failed to start tracing backend."); 3912 } 3913 3914 #if INCLUDE_MANAGEMENT 3915 Management::initialize(THREAD); 3916 3917 if (HAS_PENDING_EXCEPTION) { 3918 // management agent fails to start possibly due to 3919 // configuration problem and is responsible for printing 3920 // stack trace if appropriate. Simply exit VM. 3921 vm_exit(1); 3922 } 3923 #endif // INCLUDE_MANAGEMENT 3924 3925 if (MemProfiling) MemProfiler::engage(); 3926 StatSampler::engage(); 3927 if (CheckJNICalls) JniPeriodicChecker::engage(); 3928 3929 BiasedLocking::init(); 3930 3931 #if INCLUDE_RTM_OPT 3932 RTMLockingCounters::init(); 3933 #endif 3934 3935 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3936 call_postVMInitHook(THREAD); 3937 // The Java side of PostVMInitHook.run must deal with all 3938 // exceptions and provide means of diagnosis. 3939 if (HAS_PENDING_EXCEPTION) { 3940 CLEAR_PENDING_EXCEPTION; 3941 } 3942 } 3943 3944 { 3945 MutexLocker ml(PeriodicTask_lock); 3946 // Make sure the WatcherThread can be started by WatcherThread::start() 3947 // or by dynamic enrollment. 3948 WatcherThread::make_startable(); 3949 // Start up the WatcherThread if there are any periodic tasks 3950 // NOTE: All PeriodicTasks should be registered by now. If they 3951 // aren't, late joiners might appear to start slowly (we might 3952 // take a while to process their first tick). 3953 if (PeriodicTask::num_tasks() > 0) { 3954 WatcherThread::start(); 3955 } 3956 } 3957 3958 create_vm_timer.end(); 3959 #ifdef ASSERT 3960 _vm_complete = true; 3961 #endif 3962 3963 if (DumpSharedSpaces) { 3964 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR); 3965 ShouldNotReachHere(); 3966 } 3967 3968 return JNI_OK; 3969 } 3970 3971 // type for the Agent_OnLoad and JVM_OnLoad entry points 3972 extern "C" { 3973 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3974 } 3975 // Find a command line agent library and return its entry point for 3976 // -agentlib: -agentpath: -Xrun 3977 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3978 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, 3979 const char *on_load_symbols[], 3980 size_t num_symbol_entries) { 3981 OnLoadEntry_t on_load_entry = NULL; 3982 void *library = NULL; 3983 3984 if (!agent->valid()) { 3985 char buffer[JVM_MAXPATHLEN]; 3986 char ebuf[1024] = ""; 3987 const char *name = agent->name(); 3988 const char *msg = "Could not find agent library "; 3989 3990 // First check to see if agent is statically linked into executable 3991 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { 3992 library = agent->os_lib(); 3993 } else if (agent->is_absolute_path()) { 3994 library = os::dll_load(name, ebuf, sizeof ebuf); 3995 if (library == NULL) { 3996 const char *sub_msg = " in absolute path, with error: "; 3997 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3998 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 3999 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4000 // If we can't find the agent, exit. 4001 vm_exit_during_initialization(buf, NULL); 4002 FREE_C_HEAP_ARRAY(char, buf); 4003 } 4004 } else { 4005 // Try to load the agent from the standard dll directory 4006 if (os::dll_locate_lib(buffer, sizeof(buffer), Arguments::get_dll_dir(), 4007 name)) { 4008 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4009 } 4010 if (library == NULL) { // Try the library path directory. 4011 if (os::dll_build_name(buffer, sizeof(buffer), name)) { 4012 library = os::dll_load(buffer, ebuf, sizeof ebuf); 4013 } 4014 if (library == NULL) { 4015 const char *sub_msg = " on the library path, with error: "; 4016 const char *sub_msg2 = "\nModule java.instrument may be missing from runtime image."; 4017 4018 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + 4019 strlen(ebuf) + strlen(sub_msg2) + 1; 4020 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); 4021 if (!agent->is_instrument_lib()) { 4022 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 4023 } else { 4024 jio_snprintf(buf, len, "%s%s%s%s%s", msg, name, sub_msg, ebuf, sub_msg2); 4025 } 4026 // If we can't find the agent, exit. 4027 vm_exit_during_initialization(buf, NULL); 4028 FREE_C_HEAP_ARRAY(char, buf); 4029 } 4030 } 4031 } 4032 agent->set_os_lib(library); 4033 agent->set_valid(); 4034 } 4035 4036 // Find the OnLoad function. 4037 on_load_entry = 4038 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, 4039 false, 4040 on_load_symbols, 4041 num_symbol_entries)); 4042 return on_load_entry; 4043 } 4044 4045 // Find the JVM_OnLoad entry point 4046 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 4047 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 4048 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4049 } 4050 4051 // Find the Agent_OnLoad entry point 4052 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 4053 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 4054 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 4055 } 4056 4057 // For backwards compatibility with -Xrun 4058 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 4059 // treated like -agentpath: 4060 // Must be called before agent libraries are created 4061 void Threads::convert_vm_init_libraries_to_agents() { 4062 AgentLibrary* agent; 4063 AgentLibrary* next; 4064 4065 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 4066 next = agent->next(); // cache the next agent now as this agent may get moved off this list 4067 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4068 4069 // If there is an JVM_OnLoad function it will get called later, 4070 // otherwise see if there is an Agent_OnLoad 4071 if (on_load_entry == NULL) { 4072 on_load_entry = lookup_agent_on_load(agent); 4073 if (on_load_entry != NULL) { 4074 // switch it to the agent list -- so that Agent_OnLoad will be called, 4075 // JVM_OnLoad won't be attempted and Agent_OnUnload will 4076 Arguments::convert_library_to_agent(agent); 4077 } else { 4078 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 4079 } 4080 } 4081 } 4082 } 4083 4084 // Create agents for -agentlib: -agentpath: and converted -Xrun 4085 // Invokes Agent_OnLoad 4086 // Called very early -- before JavaThreads exist 4087 void Threads::create_vm_init_agents() { 4088 extern struct JavaVM_ main_vm; 4089 AgentLibrary* agent; 4090 4091 JvmtiExport::enter_onload_phase(); 4092 4093 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4094 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 4095 4096 if (on_load_entry != NULL) { 4097 // Invoke the Agent_OnLoad function 4098 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4099 if (err != JNI_OK) { 4100 vm_exit_during_initialization("agent library failed to init", agent->name()); 4101 } 4102 } else { 4103 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 4104 } 4105 } 4106 JvmtiExport::enter_primordial_phase(); 4107 } 4108 4109 extern "C" { 4110 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 4111 } 4112 4113 void Threads::shutdown_vm_agents() { 4114 // Send any Agent_OnUnload notifications 4115 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 4116 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); 4117 extern struct JavaVM_ main_vm; 4118 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 4119 4120 // Find the Agent_OnUnload function. 4121 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 4122 os::find_agent_function(agent, 4123 false, 4124 on_unload_symbols, 4125 num_symbol_entries)); 4126 4127 // Invoke the Agent_OnUnload function 4128 if (unload_entry != NULL) { 4129 JavaThread* thread = JavaThread::current(); 4130 ThreadToNativeFromVM ttn(thread); 4131 HandleMark hm(thread); 4132 (*unload_entry)(&main_vm); 4133 } 4134 } 4135 } 4136 4137 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 4138 // Invokes JVM_OnLoad 4139 void Threads::create_vm_init_libraries() { 4140 extern struct JavaVM_ main_vm; 4141 AgentLibrary* agent; 4142 4143 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 4144 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 4145 4146 if (on_load_entry != NULL) { 4147 // Invoke the JVM_OnLoad function 4148 JavaThread* thread = JavaThread::current(); 4149 ThreadToNativeFromVM ttn(thread); 4150 HandleMark hm(thread); 4151 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 4152 if (err != JNI_OK) { 4153 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 4154 } 4155 } else { 4156 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 4157 } 4158 } 4159 } 4160 4161 4162 // Last thread running calls java.lang.Shutdown.shutdown() 4163 void JavaThread::invoke_shutdown_hooks() { 4164 HandleMark hm(this); 4165 4166 // We could get here with a pending exception, if so clear it now. 4167 if (this->has_pending_exception()) { 4168 this->clear_pending_exception(); 4169 } 4170 4171 EXCEPTION_MARK; 4172 Klass* shutdown_klass = 4173 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 4174 THREAD); 4175 if (shutdown_klass != NULL) { 4176 // SystemDictionary::resolve_or_null will return null if there was 4177 // an exception. If we cannot load the Shutdown class, just don't 4178 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 4179 // won't be run. Note that if a shutdown hook was registered, 4180 // the Shutdown class would have already been loaded 4181 // (Runtime.addShutdownHook will load it). 4182 JavaValue result(T_VOID); 4183 JavaCalls::call_static(&result, 4184 shutdown_klass, 4185 vmSymbols::shutdown_method_name(), 4186 vmSymbols::void_method_signature(), 4187 THREAD); 4188 } 4189 CLEAR_PENDING_EXCEPTION; 4190 } 4191 4192 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 4193 // the program falls off the end of main(). Another VM exit path is through 4194 // vm_exit() when the program calls System.exit() to return a value or when 4195 // there is a serious error in VM. The two shutdown paths are not exactly 4196 // the same, but they share Shutdown.shutdown() at Java level and before_exit() 4197 // and VM_Exit op at VM level. 4198 // 4199 // Shutdown sequence: 4200 // + Shutdown native memory tracking if it is on 4201 // + Wait until we are the last non-daemon thread to execute 4202 // <-- every thing is still working at this moment --> 4203 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level 4204 // shutdown hooks 4205 // + Call before_exit(), prepare for VM exit 4206 // > run VM level shutdown hooks (they are registered through JVM_OnExit(), 4207 // currently the only user of this mechanism is File.deleteOnExit()) 4208 // > stop StatSampler, watcher thread, CMS threads, 4209 // post thread end and vm death events to JVMTI, 4210 // stop signal thread 4211 // + Call JavaThread::exit(), it will: 4212 // > release JNI handle blocks, remove stack guard pages 4213 // > remove this thread from Threads list 4214 // <-- no more Java code from this thread after this point --> 4215 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop 4216 // the compiler threads at safepoint 4217 // <-- do not use anything that could get blocked by Safepoint --> 4218 // + Disable tracing at JNI/JVM barriers 4219 // + Set _vm_exited flag for threads that are still running native code 4220 // + Delete this thread 4221 // + Call exit_globals() 4222 // > deletes tty 4223 // > deletes PerfMemory resources 4224 // + Return to caller 4225 4226 bool Threads::destroy_vm() { 4227 JavaThread* thread = JavaThread::current(); 4228 4229 #ifdef ASSERT 4230 _vm_complete = false; 4231 #endif 4232 // Wait until we are the last non-daemon thread to execute 4233 { MutexLocker nu(Threads_lock); 4234 while (Threads::number_of_non_daemon_threads() > 1) 4235 // This wait should make safepoint checks, wait without a timeout, 4236 // and wait as a suspend-equivalent condition. 4237 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 4238 Mutex::_as_suspend_equivalent_flag); 4239 } 4240 4241 EventShutdown e; 4242 if (e.should_commit()) { 4243 e.set_reason("No remaining non-daemon Java threads"); 4244 e.commit(); 4245 } 4246 4247 // Hang forever on exit if we are reporting an error. 4248 if (ShowMessageBoxOnError && VMError::is_error_reported()) { 4249 os::infinite_sleep(); 4250 } 4251 os::wait_for_keypress_at_exit(); 4252 4253 // run Java level shutdown hooks 4254 thread->invoke_shutdown_hooks(); 4255 4256 before_exit(thread); 4257 4258 thread->exit(true); 4259 4260 // Stop VM thread. 4261 { 4262 // 4945125 The vm thread comes to a safepoint during exit. 4263 // GC vm_operations can get caught at the safepoint, and the 4264 // heap is unparseable if they are caught. Grab the Heap_lock 4265 // to prevent this. The GC vm_operations will not be able to 4266 // queue until after the vm thread is dead. After this point, 4267 // we'll never emerge out of the safepoint before the VM exits. 4268 4269 MutexLocker ml(Heap_lock); 4270 4271 VMThread::wait_for_vm_thread_exit(); 4272 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 4273 VMThread::destroy(); 4274 } 4275 4276 // Now, all Java threads are gone except daemon threads. Daemon threads 4277 // running Java code or in VM are stopped by the Safepoint. However, 4278 // daemon threads executing native code are still running. But they 4279 // will be stopped at native=>Java/VM barriers. Note that we can't 4280 // simply kill or suspend them, as it is inherently deadlock-prone. 4281 4282 VM_Exit::set_vm_exited(); 4283 4284 // Clean up ideal graph printers after the VMThread has started 4285 // the final safepoint which will block all the Compiler threads. 4286 // Note that this Thread has already logically exited so the 4287 // clean_up() function's use of a JavaThreadIteratorWithHandle 4288 // would be a problem except set_vm_exited() has remembered the 4289 // shutdown thread which is granted a policy exception. 4290 #if defined(COMPILER2) && !defined(PRODUCT) 4291 IdealGraphPrinter::clean_up(); 4292 #endif 4293 4294 notify_vm_shutdown(); 4295 4296 // We are after VM_Exit::set_vm_exited() so we can't call 4297 // thread->smr_delete() or we will block on the Threads_lock. 4298 // Deleting the shutdown thread here is safe because another 4299 // JavaThread cannot have an active ThreadsListHandle for 4300 // this JavaThread. 4301 delete thread; 4302 4303 #if INCLUDE_JVMCI 4304 if (JVMCICounterSize > 0) { 4305 FREE_C_HEAP_ARRAY(jlong, JavaThread::_jvmci_old_thread_counters); 4306 } 4307 #endif 4308 4309 // exit_globals() will delete tty 4310 exit_globals(); 4311 4312 LogConfiguration::finalize(); 4313 4314 return true; 4315 } 4316 4317 4318 jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 4319 if (version == JNI_VERSION_1_1) return JNI_TRUE; 4320 return is_supported_jni_version(version); 4321 } 4322 4323 4324 jboolean Threads::is_supported_jni_version(jint version) { 4325 if (version == JNI_VERSION_1_2) return JNI_TRUE; 4326 if (version == JNI_VERSION_1_4) return JNI_TRUE; 4327 if (version == JNI_VERSION_1_6) return JNI_TRUE; 4328 if (version == JNI_VERSION_1_8) return JNI_TRUE; 4329 if (version == JNI_VERSION_9) return JNI_TRUE; 4330 if (version == JNI_VERSION_10) return JNI_TRUE; 4331 return JNI_FALSE; 4332 } 4333 4334 4335 void Threads::add(JavaThread* p, bool force_daemon) { 4336 // The threads lock must be owned at this point 4337 assert_locked_or_safepoint(Threads_lock); 4338 4339 BarrierSet::barrier_set()->on_thread_attach(p); 4340 p->set_next(_thread_list); 4341 _thread_list = p; 4342 4343 // Once a JavaThread is added to the Threads list, smr_delete() has 4344 // to be used to delete it. Otherwise we can just delete it directly. 4345 p->set_on_thread_list(); 4346 4347 _number_of_threads++; 4348 oop threadObj = p->threadObj(); 4349 bool daemon = true; 4350 // Bootstrapping problem: threadObj can be null for initial 4351 // JavaThread (or for threads attached via JNI) 4352 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 4353 _number_of_non_daemon_threads++; 4354 daemon = false; 4355 } 4356 4357 ThreadService::add_thread(p, daemon); 4358 4359 // Maintain fast thread list 4360 ThreadsSMRSupport::add_thread(p); 4361 4362 // Possible GC point. 4363 Events::log(p, "Thread added: " INTPTR_FORMAT, p2i(p)); 4364 } 4365 4366 void Threads::remove(JavaThread* p) { 4367 4368 // Reclaim the objectmonitors from the omInUseList and omFreeList of the moribund thread. 4369 ObjectSynchronizer::omFlush(p); 4370 4371 // Extra scope needed for Thread_lock, so we can check 4372 // that we do not remove thread without safepoint code notice 4373 { MutexLocker ml(Threads_lock); 4374 4375 assert(ThreadsSMRSupport::get_java_thread_list()->includes(p), "p must be present"); 4376 4377 // Maintain fast thread list 4378 ThreadsSMRSupport::remove_thread(p); 4379 4380 JavaThread* current = _thread_list; 4381 JavaThread* prev = NULL; 4382 4383 while (current != p) { 4384 prev = current; 4385 current = current->next(); 4386 } 4387 4388 if (prev) { 4389 prev->set_next(current->next()); 4390 } else { 4391 _thread_list = p->next(); 4392 } 4393 4394 _number_of_threads--; 4395 oop threadObj = p->threadObj(); 4396 bool daemon = true; 4397 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 4398 _number_of_non_daemon_threads--; 4399 daemon = false; 4400 4401 // Only one thread left, do a notify on the Threads_lock so a thread waiting 4402 // on destroy_vm will wake up. 4403 if (number_of_non_daemon_threads() == 1) { 4404 Threads_lock->notify_all(); 4405 } 4406 } 4407 ThreadService::remove_thread(p, daemon); 4408 4409 // Make sure that safepoint code disregard this thread. This is needed since 4410 // the thread might mess around with locks after this point. This can cause it 4411 // to do callbacks into the safepoint code. However, the safepoint code is not aware 4412 // of this thread since it is removed from the queue. 4413 p->set_terminated_value(); 4414 } // unlock Threads_lock 4415 4416 // Since Events::log uses a lock, we grab it outside the Threads_lock 4417 Events::log(p, "Thread exited: " INTPTR_FORMAT, p2i(p)); 4418 } 4419 4420 // Operations on the Threads list for GC. These are not explicitly locked, 4421 // but the garbage collector must provide a safe context for them to run. 4422 // In particular, these things should never be called when the Threads_lock 4423 // is held by some other thread. (Note: the Safepoint abstraction also 4424 // uses the Threads_lock to guarantee this property. It also makes sure that 4425 // all threads gets blocked when exiting or starting). 4426 4427 void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 4428 ALL_JAVA_THREADS(p) { 4429 p->oops_do(f, cf); 4430 } 4431 VMThread::vm_thread()->oops_do(f, cf); 4432 } 4433 4434 void Threads::change_thread_claim_parity() { 4435 // Set the new claim parity. 4436 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2, 4437 "Not in range."); 4438 _thread_claim_parity++; 4439 if (_thread_claim_parity == 3) _thread_claim_parity = 1; 4440 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2, 4441 "Not in range."); 4442 } 4443 4444 #ifdef ASSERT 4445 void Threads::assert_all_threads_claimed() { 4446 ALL_JAVA_THREADS(p) { 4447 const int thread_parity = p->oops_do_parity(); 4448 assert((thread_parity == _thread_claim_parity), 4449 "Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity); 4450 } 4451 VMThread* vmt = VMThread::vm_thread(); 4452 const int thread_parity = vmt->oops_do_parity(); 4453 assert((thread_parity == _thread_claim_parity), 4454 "VMThread " PTR_FORMAT " has incorrect parity %d != %d", p2i(vmt), thread_parity, _thread_claim_parity); 4455 } 4456 #endif // ASSERT 4457 4458 class ParallelOopsDoThreadClosure : public ThreadClosure { 4459 private: 4460 OopClosure* _f; 4461 CodeBlobClosure* _cf; 4462 public: 4463 ParallelOopsDoThreadClosure(OopClosure* f, CodeBlobClosure* cf) : _f(f), _cf(cf) {} 4464 void do_thread(Thread* t) { 4465 t->oops_do(_f, _cf); 4466 } 4467 }; 4468 4469 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf) { 4470 ParallelOopsDoThreadClosure tc(f, cf); 4471 possibly_parallel_threads_do(is_par, &tc); 4472 } 4473 4474 #if INCLUDE_ALL_GCS 4475 // Used by ParallelScavenge 4476 void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 4477 ALL_JAVA_THREADS(p) { 4478 q->enqueue(new ThreadRootsTask(p)); 4479 } 4480 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 4481 } 4482 4483 // Used by Parallel Old 4484 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 4485 ALL_JAVA_THREADS(p) { 4486 q->enqueue(new ThreadRootsMarkingTask(p)); 4487 } 4488 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 4489 } 4490 #endif // INCLUDE_ALL_GCS 4491 4492 void Threads::nmethods_do(CodeBlobClosure* cf) { 4493 ALL_JAVA_THREADS(p) { 4494 // This is used by the code cache sweeper to mark nmethods that are active 4495 // on the stack of a Java thread. Ignore the sweeper thread itself to avoid 4496 // marking CodeCacheSweeperThread::_scanned_compiled_method as active. 4497 if(!p->is_Code_cache_sweeper_thread()) { 4498 p->nmethods_do(cf); 4499 } 4500 } 4501 } 4502 4503 void Threads::metadata_do(void f(Metadata*)) { 4504 ALL_JAVA_THREADS(p) { 4505 p->metadata_do(f); 4506 } 4507 } 4508 4509 class ThreadHandlesClosure : public ThreadClosure { 4510 void (*_f)(Metadata*); 4511 public: 4512 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {} 4513 virtual void do_thread(Thread* thread) { 4514 thread->metadata_handles_do(_f); 4515 } 4516 }; 4517 4518 void Threads::metadata_handles_do(void f(Metadata*)) { 4519 // Only walk the Handles in Thread. 4520 ThreadHandlesClosure handles_closure(f); 4521 threads_do(&handles_closure); 4522 } 4523 4524 void Threads::deoptimized_wrt_marked_nmethods() { 4525 ALL_JAVA_THREADS(p) { 4526 p->deoptimized_wrt_marked_nmethods(); 4527 } 4528 } 4529 4530 4531 // Get count Java threads that are waiting to enter the specified monitor. 4532 GrowableArray<JavaThread*>* Threads::get_pending_threads(ThreadsList * t_list, 4533 int count, 4534 address monitor) { 4535 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 4536 4537 int i = 0; 4538 DO_JAVA_THREADS(t_list, p) { 4539 if (!p->can_call_java()) continue; 4540 4541 address pending = (address)p->current_pending_monitor(); 4542 if (pending == monitor) { // found a match 4543 if (i < count) result->append(p); // save the first count matches 4544 i++; 4545 } 4546 } 4547 4548 return result; 4549 } 4550 4551 4552 JavaThread *Threads::owning_thread_from_monitor_owner(ThreadsList * t_list, 4553 address owner) { 4554 // NULL owner means not locked so we can skip the search 4555 if (owner == NULL) return NULL; 4556 4557 DO_JAVA_THREADS(t_list, p) { 4558 // first, see if owner is the address of a Java thread 4559 if (owner == (address)p) return p; 4560 } 4561 4562 // Cannot assert on lack of success here since this function may be 4563 // used by code that is trying to report useful problem information 4564 // like deadlock detection. 4565 if (UseHeavyMonitors) return NULL; 4566 4567 // If we didn't find a matching Java thread and we didn't force use of 4568 // heavyweight monitors, then the owner is the stack address of the 4569 // Lock Word in the owning Java thread's stack. 4570 // 4571 JavaThread* the_owner = NULL; 4572 DO_JAVA_THREADS(t_list, q) { 4573 if (q->is_lock_owned(owner)) { 4574 the_owner = q; 4575 break; 4576 } 4577 } 4578 4579 // cannot assert on lack of success here; see above comment 4580 return the_owner; 4581 } 4582 4583 // Threads::print_on() is called at safepoint by VM_PrintThreads operation. 4584 void Threads::print_on(outputStream* st, bool print_stacks, 4585 bool internal_format, bool print_concurrent_locks) { 4586 char buf[32]; 4587 st->print_raw_cr(os::local_time_string(buf, sizeof(buf))); 4588 4589 st->print_cr("Full thread dump %s (%s %s):", 4590 Abstract_VM_Version::vm_name(), 4591 Abstract_VM_Version::vm_release(), 4592 Abstract_VM_Version::vm_info_string()); 4593 st->cr(); 4594 4595 #if INCLUDE_SERVICES 4596 // Dump concurrent locks 4597 ConcurrentLocksDump concurrent_locks; 4598 if (print_concurrent_locks) { 4599 concurrent_locks.dump_at_safepoint(); 4600 } 4601 #endif // INCLUDE_SERVICES 4602 4603 ThreadsSMRSupport::print_info_on(st); 4604 st->cr(); 4605 4606 ALL_JAVA_THREADS(p) { 4607 ResourceMark rm; 4608 p->print_on(st); 4609 if (print_stacks) { 4610 if (internal_format) { 4611 p->trace_stack(); 4612 } else { 4613 p->print_stack_on(st); 4614 } 4615 } 4616 st->cr(); 4617 #if INCLUDE_SERVICES 4618 if (print_concurrent_locks) { 4619 concurrent_locks.print_locks_on(p, st); 4620 } 4621 #endif // INCLUDE_SERVICES 4622 } 4623 4624 VMThread::vm_thread()->print_on(st); 4625 st->cr(); 4626 Universe::heap()->print_gc_threads_on(st); 4627 WatcherThread* wt = WatcherThread::watcher_thread(); 4628 if (wt != NULL) { 4629 wt->print_on(st); 4630 st->cr(); 4631 } 4632 4633 st->flush(); 4634 } 4635 4636 void Threads::print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf, 4637 int buflen, bool* found_current) { 4638 if (this_thread != NULL) { 4639 bool is_current = (current == this_thread); 4640 *found_current = *found_current || is_current; 4641 st->print("%s", is_current ? "=>" : " "); 4642 4643 st->print(PTR_FORMAT, p2i(this_thread)); 4644 st->print(" "); 4645 this_thread->print_on_error(st, buf, buflen); 4646 st->cr(); 4647 } 4648 } 4649 4650 class PrintOnErrorClosure : public ThreadClosure { 4651 outputStream* _st; 4652 Thread* _current; 4653 char* _buf; 4654 int _buflen; 4655 bool* _found_current; 4656 public: 4657 PrintOnErrorClosure(outputStream* st, Thread* current, char* buf, 4658 int buflen, bool* found_current) : 4659 _st(st), _current(current), _buf(buf), _buflen(buflen), _found_current(found_current) {} 4660 4661 virtual void do_thread(Thread* thread) { 4662 Threads::print_on_error(thread, _st, _current, _buf, _buflen, _found_current); 4663 } 4664 }; 4665 4666 // Threads::print_on_error() is called by fatal error handler. It's possible 4667 // that VM is not at safepoint and/or current thread is inside signal handler. 4668 // Don't print stack trace, as the stack may not be walkable. Don't allocate 4669 // memory (even in resource area), it might deadlock the error handler. 4670 void Threads::print_on_error(outputStream* st, Thread* current, char* buf, 4671 int buflen) { 4672 ThreadsSMRSupport::print_info_on(st); 4673 st->cr(); 4674 4675 bool found_current = false; 4676 st->print_cr("Java Threads: ( => current thread )"); 4677 ALL_JAVA_THREADS(thread) { 4678 print_on_error(thread, st, current, buf, buflen, &found_current); 4679 } 4680 st->cr(); 4681 4682 st->print_cr("Other Threads:"); 4683 print_on_error(VMThread::vm_thread(), st, current, buf, buflen, &found_current); 4684 print_on_error(WatcherThread::watcher_thread(), st, current, buf, buflen, &found_current); 4685 4686 PrintOnErrorClosure print_closure(st, current, buf, buflen, &found_current); 4687 Universe::heap()->gc_threads_do(&print_closure); 4688 4689 if (!found_current) { 4690 st->cr(); 4691 st->print("=>" PTR_FORMAT " (exited) ", p2i(current)); 4692 current->print_on_error(st, buf, buflen); 4693 st->cr(); 4694 } 4695 st->cr(); 4696 4697 st->print_cr("Threads with active compile tasks:"); 4698 print_threads_compiling(st, buf, buflen); 4699 } 4700 4701 void Threads::print_threads_compiling(outputStream* st, char* buf, int buflen) { 4702 ALL_JAVA_THREADS(thread) { 4703 if (thread->is_Compiler_thread()) { 4704 CompilerThread* ct = (CompilerThread*) thread; 4705 4706 // Keep task in local variable for NULL check. 4707 // ct->_task might be set to NULL by concurring compiler thread 4708 // because it completed the compilation. The task is never freed, 4709 // though, just returned to a free list. 4710 CompileTask* task = ct->task(); 4711 if (task != NULL) { 4712 thread->print_name_on_error(st, buf, buflen); 4713 task->print(st, NULL, true, true); 4714 } 4715 } 4716 } 4717 } 4718 4719 4720 // Internal SpinLock and Mutex 4721 // Based on ParkEvent 4722 4723 // Ad-hoc mutual exclusion primitives: SpinLock and Mux 4724 // 4725 // We employ SpinLocks _only for low-contention, fixed-length 4726 // short-duration critical sections where we're concerned 4727 // about native mutex_t or HotSpot Mutex:: latency. 4728 // The mux construct provides a spin-then-block mutual exclusion 4729 // mechanism. 4730 // 4731 // Testing has shown that contention on the ListLock guarding gFreeList 4732 // is common. If we implement ListLock as a simple SpinLock it's common 4733 // for the JVM to devolve to yielding with little progress. This is true 4734 // despite the fact that the critical sections protected by ListLock are 4735 // extremely short. 4736 // 4737 // TODO-FIXME: ListLock should be of type SpinLock. 4738 // We should make this a 1st-class type, integrated into the lock 4739 // hierarchy as leaf-locks. Critically, the SpinLock structure 4740 // should have sufficient padding to avoid false-sharing and excessive 4741 // cache-coherency traffic. 4742 4743 4744 typedef volatile int SpinLockT; 4745 4746 void Thread::SpinAcquire(volatile int * adr, const char * LockName) { 4747 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4748 return; // normal fast-path return 4749 } 4750 4751 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4752 TEVENT(SpinAcquire - ctx); 4753 int ctr = 0; 4754 int Yields = 0; 4755 for (;;) { 4756 while (*adr != 0) { 4757 ++ctr; 4758 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4759 if (Yields > 5) { 4760 os::naked_short_sleep(1); 4761 } else { 4762 os::naked_yield(); 4763 ++Yields; 4764 } 4765 } else { 4766 SpinPause(); 4767 } 4768 } 4769 if (Atomic::cmpxchg(1, adr, 0) == 0) return; 4770 } 4771 } 4772 4773 void Thread::SpinRelease(volatile int * adr) { 4774 assert(*adr != 0, "invariant"); 4775 OrderAccess::fence(); // guarantee at least release consistency. 4776 // Roach-motel semantics. 4777 // It's safe if subsequent LDs and STs float "up" into the critical section, 4778 // but prior LDs and STs within the critical section can't be allowed 4779 // to reorder or float past the ST that releases the lock. 4780 // Loads and stores in the critical section - which appear in program 4781 // order before the store that releases the lock - must also appear 4782 // before the store that releases the lock in memory visibility order. 4783 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before 4784 // the ST of 0 into the lock-word which releases the lock, so fence 4785 // more than covers this on all platforms. 4786 *adr = 0; 4787 } 4788 4789 // muxAcquire and muxRelease: 4790 // 4791 // * muxAcquire and muxRelease support a single-word lock-word construct. 4792 // The LSB of the word is set IFF the lock is held. 4793 // The remainder of the word points to the head of a singly-linked list 4794 // of threads blocked on the lock. 4795 // 4796 // * The current implementation of muxAcquire-muxRelease uses its own 4797 // dedicated Thread._MuxEvent instance. If we're interested in 4798 // minimizing the peak number of extant ParkEvent instances then 4799 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4800 // as certain invariants were satisfied. Specifically, care would need 4801 // to be taken with regards to consuming unpark() "permits". 4802 // A safe rule of thumb is that a thread would never call muxAcquire() 4803 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4804 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4805 // consume an unpark() permit intended for monitorenter, for instance. 4806 // One way around this would be to widen the restricted-range semaphore 4807 // implemented in park(). Another alternative would be to provide 4808 // multiple instances of the PlatformEvent() for each thread. One 4809 // instance would be dedicated to muxAcquire-muxRelease, for instance. 4810 // 4811 // * Usage: 4812 // -- Only as leaf locks 4813 // -- for short-term locking only as muxAcquire does not perform 4814 // thread state transitions. 4815 // 4816 // Alternatives: 4817 // * We could implement muxAcquire and muxRelease with MCS or CLH locks 4818 // but with parking or spin-then-park instead of pure spinning. 4819 // * Use Taura-Oyama-Yonenzawa locks. 4820 // * It's possible to construct a 1-0 lock if we encode the lockword as 4821 // (List,LockByte). Acquire will CAS the full lockword while Release 4822 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4823 // acquiring threads use timers (ParkTimed) to detect and recover from 4824 // the stranding window. Thread/Node structures must be aligned on 256-byte 4825 // boundaries by using placement-new. 4826 // * Augment MCS with advisory back-link fields maintained with CAS(). 4827 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4828 // The validity of the backlinks must be ratified before we trust the value. 4829 // If the backlinks are invalid the exiting thread must back-track through the 4830 // the forward links, which are always trustworthy. 4831 // * Add a successor indication. The LockWord is currently encoded as 4832 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4833 // to provide the usual futile-wakeup optimization. 4834 // See RTStt for details. 4835 // * Consider schedctl.sc_nopreempt to cover the critical section. 4836 // 4837 4838 4839 const intptr_t LOCKBIT = 1; 4840 4841 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) { 4842 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4843 if (w == 0) return; 4844 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4845 return; 4846 } 4847 4848 TEVENT(muxAcquire - Contention); 4849 ParkEvent * const Self = Thread::current()->_MuxEvent; 4850 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant"); 4851 for (;;) { 4852 int its = (os::is_MP() ? 100 : 0) + 1; 4853 4854 // Optional spin phase: spin-then-park strategy 4855 while (--its >= 0) { 4856 w = *Lock; 4857 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4858 return; 4859 } 4860 } 4861 4862 Self->reset(); 4863 Self->OnList = intptr_t(Lock); 4864 // The following fence() isn't _strictly necessary as the subsequent 4865 // CAS() both serializes execution and ratifies the fetched *Lock value. 4866 OrderAccess::fence(); 4867 for (;;) { 4868 w = *Lock; 4869 if ((w & LOCKBIT) == 0) { 4870 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4871 Self->OnList = 0; // hygiene - allows stronger asserts 4872 return; 4873 } 4874 continue; // Interference -- *Lock changed -- Just retry 4875 } 4876 assert(w & LOCKBIT, "invariant"); 4877 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4878 if (Atomic::cmpxchg(intptr_t(Self)|LOCKBIT, Lock, w) == w) break; 4879 } 4880 4881 while (Self->OnList != 0) { 4882 Self->park(); 4883 } 4884 } 4885 } 4886 4887 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) { 4888 intptr_t w = Atomic::cmpxchg(LOCKBIT, Lock, (intptr_t)0); 4889 if (w == 0) return; 4890 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4891 return; 4892 } 4893 4894 TEVENT(muxAcquire - Contention); 4895 ParkEvent * ReleaseAfter = NULL; 4896 if (ev == NULL) { 4897 ev = ReleaseAfter = ParkEvent::Allocate(NULL); 4898 } 4899 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant"); 4900 for (;;) { 4901 guarantee(ev->OnList == 0, "invariant"); 4902 int its = (os::is_MP() ? 100 : 0) + 1; 4903 4904 // Optional spin phase: spin-then-park strategy 4905 while (--its >= 0) { 4906 w = *Lock; 4907 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4908 if (ReleaseAfter != NULL) { 4909 ParkEvent::Release(ReleaseAfter); 4910 } 4911 return; 4912 } 4913 } 4914 4915 ev->reset(); 4916 ev->OnList = intptr_t(Lock); 4917 // The following fence() isn't _strictly necessary as the subsequent 4918 // CAS() both serializes execution and ratifies the fetched *Lock value. 4919 OrderAccess::fence(); 4920 for (;;) { 4921 w = *Lock; 4922 if ((w & LOCKBIT) == 0) { 4923 if (Atomic::cmpxchg(w|LOCKBIT, Lock, w) == w) { 4924 ev->OnList = 0; 4925 // We call ::Release while holding the outer lock, thus 4926 // artificially lengthening the critical section. 4927 // Consider deferring the ::Release() until the subsequent unlock(), 4928 // after we've dropped the outer lock. 4929 if (ReleaseAfter != NULL) { 4930 ParkEvent::Release(ReleaseAfter); 4931 } 4932 return; 4933 } 4934 continue; // Interference -- *Lock changed -- Just retry 4935 } 4936 assert(w & LOCKBIT, "invariant"); 4937 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT); 4938 if (Atomic::cmpxchg(intptr_t(ev)|LOCKBIT, Lock, w) == w) break; 4939 } 4940 4941 while (ev->OnList != 0) { 4942 ev->park(); 4943 } 4944 } 4945 } 4946 4947 // Release() must extract a successor from the list and then wake that thread. 4948 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4949 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4950 // Release() would : 4951 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4952 // (B) Extract a successor from the private list "in-hand" 4953 // (C) attempt to CAS() the residual back into *Lock over null. 4954 // If there were any newly arrived threads and the CAS() would fail. 4955 // In that case Release() would detach the RATs, re-merge the list in-hand 4956 // with the RATs and repeat as needed. Alternately, Release() might 4957 // detach and extract a successor, but then pass the residual list to the wakee. 4958 // The wakee would be responsible for reattaching and remerging before it 4959 // competed for the lock. 4960 // 4961 // Both "pop" and DMR are immune from ABA corruption -- there can be 4962 // multiple concurrent pushers, but only one popper or detacher. 4963 // This implementation pops from the head of the list. This is unfair, 4964 // but tends to provide excellent throughput as hot threads remain hot. 4965 // (We wake recently run threads first). 4966 // 4967 // All paths through muxRelease() will execute a CAS. 4968 // Release consistency -- We depend on the CAS in muxRelease() to provide full 4969 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations 4970 // executed within the critical section are complete and globally visible before the 4971 // store (CAS) to the lock-word that releases the lock becomes globally visible. 4972 void Thread::muxRelease(volatile intptr_t * Lock) { 4973 for (;;) { 4974 const intptr_t w = Atomic::cmpxchg((intptr_t)0, Lock, LOCKBIT); 4975 assert(w & LOCKBIT, "invariant"); 4976 if (w == LOCKBIT) return; 4977 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT); 4978 assert(List != NULL, "invariant"); 4979 assert(List->OnList == intptr_t(Lock), "invariant"); 4980 ParkEvent * const nxt = List->ListNext; 4981 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant"); 4982 4983 // The following CAS() releases the lock and pops the head element. 4984 // The CAS() also ratifies the previously fetched lock-word value. 4985 if (Atomic::cmpxchg(intptr_t(nxt), Lock, w) != w) { 4986 continue; 4987 } 4988 List->OnList = 0; 4989 OrderAccess::fence(); 4990 List->unpark(); 4991 return; 4992 } 4993 } 4994 4995 4996 void Threads::verify() { 4997 ALL_JAVA_THREADS(p) { 4998 p->verify(); 4999 } 5000 VMThread* thread = VMThread::vm_thread(); 5001 if (thread != NULL) thread->verify(); 5002 }