thread.cpp revision 2062:3582bf76420e
1/* 2 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26#include "classfile/classLoader.hpp" 27#include "classfile/javaClasses.hpp" 28#include "classfile/systemDictionary.hpp" 29#include "classfile/vmSymbols.hpp" 30#include "code/scopeDesc.hpp" 31#include "compiler/compileBroker.hpp" 32#include "interpreter/interpreter.hpp" 33#include "interpreter/linkResolver.hpp" 34#include "jvmtifiles/jvmtiEnv.hpp" 35#include "memory/oopFactory.hpp" 36#include "memory/universe.inline.hpp" 37#include "oops/instanceKlass.hpp" 38#include "oops/objArrayOop.hpp" 39#include "oops/oop.inline.hpp" 40#include "oops/symbol.hpp" 41#include "prims/jvm_misc.hpp" 42#include "prims/jvmtiExport.hpp" 43#include "prims/jvmtiThreadState.hpp" 44#include "prims/privilegedStack.hpp" 45#include "runtime/aprofiler.hpp" 46#include "runtime/arguments.hpp" 47#include "runtime/biasedLocking.hpp" 48#include "runtime/deoptimization.hpp" 49#include "runtime/fprofiler.hpp" 50#include "runtime/frame.inline.hpp" 51#include "runtime/init.hpp" 52#include "runtime/interfaceSupport.hpp" 53#include "runtime/java.hpp" 54#include "runtime/javaCalls.hpp" 55#include "runtime/jniPeriodicChecker.hpp" 56#include "runtime/memprofiler.hpp" 57#include "runtime/mutexLocker.hpp" 58#include "runtime/objectMonitor.hpp" 59#include "runtime/osThread.hpp" 60#include "runtime/safepoint.hpp" 61#include "runtime/sharedRuntime.hpp" 62#include "runtime/statSampler.hpp" 63#include "runtime/stubRoutines.hpp" 64#include "runtime/task.hpp" 65#include "runtime/threadCritical.hpp" 66#include "runtime/threadLocalStorage.hpp" 67#include "runtime/vframe.hpp" 68#include "runtime/vframeArray.hpp" 69#include "runtime/vframe_hp.hpp" 70#include "runtime/vmThread.hpp" 71#include "runtime/vm_operations.hpp" 72#include "services/attachListener.hpp" 73#include "services/management.hpp" 74#include "services/threadService.hpp" 75#include "utilities/defaultStream.hpp" 76#include "utilities/dtrace.hpp" 77#include "utilities/events.hpp" 78#include "utilities/preserveException.hpp" 79#ifdef TARGET_OS_FAMILY_linux 80# include "os_linux.inline.hpp" 81# include "thread_linux.inline.hpp" 82#endif 83#ifdef TARGET_OS_FAMILY_solaris 84# include "os_solaris.inline.hpp" 85# include "thread_solaris.inline.hpp" 86#endif 87#ifdef TARGET_OS_FAMILY_windows 88# include "os_windows.inline.hpp" 89# include "thread_windows.inline.hpp" 90#endif 91#ifndef SERIALGC 92#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 93#include "gc_implementation/g1/concurrentMarkThread.inline.hpp" 94#include "gc_implementation/parallelScavenge/pcTasks.hpp" 95#endif 96#ifdef COMPILER1 97#include "c1/c1_Compiler.hpp" 98#endif 99#ifdef COMPILER2 100#include "opto/c2compiler.hpp" 101#include "opto/idealGraphPrinter.hpp" 102#endif 103 104#ifdef DTRACE_ENABLED 105 106// Only bother with this argument setup if dtrace is available 107 108HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin); 109HS_DTRACE_PROBE_DECL(hotspot, vm__init__end); 110HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t, 111 intptr_t, intptr_t, bool); 112HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t, 113 intptr_t, intptr_t, bool); 114 115#define DTRACE_THREAD_PROBE(probe, javathread) \ 116 { \ 117 ResourceMark rm(this); \ 118 int len = 0; \ 119 const char* name = (javathread)->get_thread_name(); \ 120 len = strlen(name); \ 121 HS_DTRACE_PROBE5(hotspot, thread__##probe, \ 122 name, len, \ 123 java_lang_Thread::thread_id((javathread)->threadObj()), \ 124 (javathread)->osthread()->thread_id(), \ 125 java_lang_Thread::is_daemon((javathread)->threadObj())); \ 126 } 127 128#else // ndef DTRACE_ENABLED 129 130#define DTRACE_THREAD_PROBE(probe, javathread) 131 132#endif // ndef DTRACE_ENABLED 133 134// Class hierarchy 135// - Thread 136// - VMThread 137// - WatcherThread 138// - ConcurrentMarkSweepThread 139// - JavaThread 140// - CompilerThread 141 142// ======= Thread ======== 143 144// Support for forcing alignment of thread objects for biased locking 145void* Thread::operator new(size_t size) { 146 if (UseBiasedLocking) { 147 const int alignment = markOopDesc::biased_lock_alignment; 148 size_t aligned_size = size + (alignment - sizeof(intptr_t)); 149 void* real_malloc_addr = CHeapObj::operator new(aligned_size); 150 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); 151 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= 152 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), 153 "JavaThread alignment code overflowed allocated storage"); 154 if (TraceBiasedLocking) { 155 if (aligned_addr != real_malloc_addr) 156 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, 157 real_malloc_addr, aligned_addr); 158 } 159 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; 160 return aligned_addr; 161 } else { 162 return CHeapObj::operator new(size); 163 } 164} 165 166void Thread::operator delete(void* p) { 167 if (UseBiasedLocking) { 168 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; 169 CHeapObj::operator delete(real_malloc_addr); 170 } else { 171 CHeapObj::operator delete(p); 172 } 173} 174 175 176// Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, 177// JavaThread 178 179 180Thread::Thread() { 181 // stack and get_thread 182 set_stack_base(NULL); 183 set_stack_size(0); 184 set_self_raw_id(0); 185 set_lgrp_id(-1); 186 187 // allocated data structures 188 set_osthread(NULL); 189 set_resource_area(new ResourceArea()); 190 set_handle_area(new HandleArea(NULL)); 191 set_active_handles(NULL); 192 set_free_handle_block(NULL); 193 set_last_handle_mark(NULL); 194 195 // This initial value ==> never claimed. 196 _oops_do_parity = 0; 197 198 // the handle mark links itself to last_handle_mark 199 new HandleMark(this); 200 201 // plain initialization 202 debug_only(_owned_locks = NULL;) 203 debug_only(_allow_allocation_count = 0;) 204 NOT_PRODUCT(_allow_safepoint_count = 0;) 205 NOT_PRODUCT(_skip_gcalot = false;) 206 CHECK_UNHANDLED_OOPS_ONLY(_gc_locked_out_count = 0;) 207 _jvmti_env_iteration_count = 0; 208 set_allocated_bytes(0); 209 _vm_operation_started_count = 0; 210 _vm_operation_completed_count = 0; 211 _current_pending_monitor = NULL; 212 _current_pending_monitor_is_from_java = true; 213 _current_waiting_monitor = NULL; 214 _num_nested_signal = 0; 215 omFreeList = NULL ; 216 omFreeCount = 0 ; 217 omFreeProvision = 32 ; 218 omInUseList = NULL ; 219 omInUseCount = 0 ; 220 221 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); 222 _suspend_flags = 0; 223 224 // thread-specific hashCode stream generator state - Marsaglia shift-xor form 225 _hashStateX = os::random() ; 226 _hashStateY = 842502087 ; 227 _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ; 228 _hashStateW = 273326509 ; 229 230 _OnTrap = 0 ; 231 _schedctl = NULL ; 232 _Stalled = 0 ; 233 _TypeTag = 0x2BAD ; 234 235 // Many of the following fields are effectively final - immutable 236 // Note that nascent threads can't use the Native Monitor-Mutex 237 // construct until the _MutexEvent is initialized ... 238 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents 239 // we might instead use a stack of ParkEvents that we could provision on-demand. 240 // The stack would act as a cache to avoid calls to ParkEvent::Allocate() 241 // and ::Release() 242 _ParkEvent = ParkEvent::Allocate (this) ; 243 _SleepEvent = ParkEvent::Allocate (this) ; 244 _MutexEvent = ParkEvent::Allocate (this) ; 245 _MuxEvent = ParkEvent::Allocate (this) ; 246 247#ifdef CHECK_UNHANDLED_OOPS 248 if (CheckUnhandledOops) { 249 _unhandled_oops = new UnhandledOops(this); 250 } 251#endif // CHECK_UNHANDLED_OOPS 252#ifdef ASSERT 253 if (UseBiasedLocking) { 254 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); 255 assert(this == _real_malloc_address || 256 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), 257 "bug in forced alignment of thread objects"); 258 } 259#endif /* ASSERT */ 260} 261 262void Thread::initialize_thread_local_storage() { 263 // Note: Make sure this method only calls 264 // non-blocking operations. Otherwise, it might not work 265 // with the thread-startup/safepoint interaction. 266 267 // During Java thread startup, safepoint code should allow this 268 // method to complete because it may need to allocate memory to 269 // store information for the new thread. 270 271 // initialize structure dependent on thread local storage 272 ThreadLocalStorage::set_thread(this); 273 274 // set up any platform-specific state. 275 os::initialize_thread(); 276 277} 278 279void Thread::record_stack_base_and_size() { 280 set_stack_base(os::current_stack_base()); 281 set_stack_size(os::current_stack_size()); 282} 283 284 285Thread::~Thread() { 286 // Reclaim the objectmonitors from the omFreeList of the moribund thread. 287 ObjectSynchronizer::omFlush (this) ; 288 289 // deallocate data structures 290 delete resource_area(); 291 // since the handle marks are using the handle area, we have to deallocated the root 292 // handle mark before deallocating the thread's handle area, 293 assert(last_handle_mark() != NULL, "check we have an element"); 294 delete last_handle_mark(); 295 assert(last_handle_mark() == NULL, "check we have reached the end"); 296 297 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. 298 // We NULL out the fields for good hygiene. 299 ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ; 300 ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ; 301 ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ; 302 ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ; 303 304 delete handle_area(); 305 306 // osthread() can be NULL, if creation of thread failed. 307 if (osthread() != NULL) os::free_thread(osthread()); 308 309 delete _SR_lock; 310 311 // clear thread local storage if the Thread is deleting itself 312 if (this == Thread::current()) { 313 ThreadLocalStorage::set_thread(NULL); 314 } else { 315 // In the case where we're not the current thread, invalidate all the 316 // caches in case some code tries to get the current thread or the 317 // thread that was destroyed, and gets stale information. 318 ThreadLocalStorage::invalidate_all(); 319 } 320 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) 321} 322 323// NOTE: dummy function for assertion purpose. 324void Thread::run() { 325 ShouldNotReachHere(); 326} 327 328#ifdef ASSERT 329// Private method to check for dangling thread pointer 330void check_for_dangling_thread_pointer(Thread *thread) { 331 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), 332 "possibility of dangling Thread pointer"); 333} 334#endif 335 336 337#ifndef PRODUCT 338// Tracing method for basic thread operations 339void Thread::trace(const char* msg, const Thread* const thread) { 340 if (!TraceThreadEvents) return; 341 ResourceMark rm; 342 ThreadCritical tc; 343 const char *name = "non-Java thread"; 344 int prio = -1; 345 if (thread->is_Java_thread() 346 && !thread->is_Compiler_thread()) { 347 // The Threads_lock must be held to get information about 348 // this thread but may not be in some situations when 349 // tracing thread events. 350 bool release_Threads_lock = false; 351 if (!Threads_lock->owned_by_self()) { 352 Threads_lock->lock(); 353 release_Threads_lock = true; 354 } 355 JavaThread* jt = (JavaThread *)thread; 356 name = (char *)jt->get_thread_name(); 357 oop thread_oop = jt->threadObj(); 358 if (thread_oop != NULL) { 359 prio = java_lang_Thread::priority(thread_oop); 360 } 361 if (release_Threads_lock) { 362 Threads_lock->unlock(); 363 } 364 } 365 tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); 366} 367#endif 368 369 370ThreadPriority Thread::get_priority(const Thread* const thread) { 371 trace("get priority", thread); 372 ThreadPriority priority; 373 // Can return an error! 374 (void)os::get_priority(thread, priority); 375 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); 376 return priority; 377} 378 379void Thread::set_priority(Thread* thread, ThreadPriority priority) { 380 trace("set priority", thread); 381 debug_only(check_for_dangling_thread_pointer(thread);) 382 // Can return an error! 383 (void)os::set_priority(thread, priority); 384} 385 386 387void Thread::start(Thread* thread) { 388 trace("start", thread); 389 // Start is different from resume in that its safety is guaranteed by context or 390 // being called from a Java method synchronized on the Thread object. 391 if (!DisableStartThread) { 392 if (thread->is_Java_thread()) { 393 // Initialize the thread state to RUNNABLE before starting this thread. 394 // Can not set it after the thread started because we do not know the 395 // exact thread state at that time. It could be in MONITOR_WAIT or 396 // in SLEEPING or some other state. 397 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), 398 java_lang_Thread::RUNNABLE); 399 } 400 os::start_thread(thread); 401 } 402} 403 404// Enqueue a VM_Operation to do the job for us - sometime later 405void Thread::send_async_exception(oop java_thread, oop java_throwable) { 406 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); 407 VMThread::execute(vm_stop); 408} 409 410 411// 412// Check if an external suspend request has completed (or has been 413// cancelled). Returns true if the thread is externally suspended and 414// false otherwise. 415// 416// The bits parameter returns information about the code path through 417// the routine. Useful for debugging: 418// 419// set in is_ext_suspend_completed(): 420// 0x00000001 - routine was entered 421// 0x00000010 - routine return false at end 422// 0x00000100 - thread exited (return false) 423// 0x00000200 - suspend request cancelled (return false) 424// 0x00000400 - thread suspended (return true) 425// 0x00001000 - thread is in a suspend equivalent state (return true) 426// 0x00002000 - thread is native and walkable (return true) 427// 0x00004000 - thread is native_trans and walkable (needed retry) 428// 429// set in wait_for_ext_suspend_completion(): 430// 0x00010000 - routine was entered 431// 0x00020000 - suspend request cancelled before loop (return false) 432// 0x00040000 - thread suspended before loop (return true) 433// 0x00080000 - suspend request cancelled in loop (return false) 434// 0x00100000 - thread suspended in loop (return true) 435// 0x00200000 - suspend not completed during retry loop (return false) 436// 437 438// Helper class for tracing suspend wait debug bits. 439// 440// 0x00000100 indicates that the target thread exited before it could 441// self-suspend which is not a wait failure. 0x00000200, 0x00020000 and 442// 0x00080000 each indicate a cancelled suspend request so they don't 443// count as wait failures either. 444#define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) 445 446class TraceSuspendDebugBits : public StackObj { 447 private: 448 JavaThread * jt; 449 bool is_wait; 450 bool called_by_wait; // meaningful when !is_wait 451 uint32_t * bits; 452 453 public: 454 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, 455 uint32_t *_bits) { 456 jt = _jt; 457 is_wait = _is_wait; 458 called_by_wait = _called_by_wait; 459 bits = _bits; 460 } 461 462 ~TraceSuspendDebugBits() { 463 if (!is_wait) { 464#if 1 465 // By default, don't trace bits for is_ext_suspend_completed() calls. 466 // That trace is very chatty. 467 return; 468#else 469 if (!called_by_wait) { 470 // If tracing for is_ext_suspend_completed() is enabled, then only 471 // trace calls to it from wait_for_ext_suspend_completion() 472 return; 473 } 474#endif 475 } 476 477 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { 478 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { 479 MutexLocker ml(Threads_lock); // needed for get_thread_name() 480 ResourceMark rm; 481 482 tty->print_cr( 483 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", 484 jt->get_thread_name(), *bits); 485 486 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); 487 } 488 } 489 } 490}; 491#undef DEBUG_FALSE_BITS 492 493 494bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) { 495 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); 496 497 bool did_trans_retry = false; // only do thread_in_native_trans retry once 498 bool do_trans_retry; // flag to force the retry 499 500 *bits |= 0x00000001; 501 502 do { 503 do_trans_retry = false; 504 505 if (is_exiting()) { 506 // Thread is in the process of exiting. This is always checked 507 // first to reduce the risk of dereferencing a freed JavaThread. 508 *bits |= 0x00000100; 509 return false; 510 } 511 512 if (!is_external_suspend()) { 513 // Suspend request is cancelled. This is always checked before 514 // is_ext_suspended() to reduce the risk of a rogue resume 515 // confusing the thread that made the suspend request. 516 *bits |= 0x00000200; 517 return false; 518 } 519 520 if (is_ext_suspended()) { 521 // thread is suspended 522 *bits |= 0x00000400; 523 return true; 524 } 525 526 // Now that we no longer do hard suspends of threads running 527 // native code, the target thread can be changing thread state 528 // while we are in this routine: 529 // 530 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked 531 // 532 // We save a copy of the thread state as observed at this moment 533 // and make our decision about suspend completeness based on the 534 // copy. This closes the race where the thread state is seen as 535 // _thread_in_native_trans in the if-thread_blocked check, but is 536 // seen as _thread_blocked in if-thread_in_native_trans check. 537 JavaThreadState save_state = thread_state(); 538 539 if (save_state == _thread_blocked && is_suspend_equivalent()) { 540 // If the thread's state is _thread_blocked and this blocking 541 // condition is known to be equivalent to a suspend, then we can 542 // consider the thread to be externally suspended. This means that 543 // the code that sets _thread_blocked has been modified to do 544 // self-suspension if the blocking condition releases. We also 545 // used to check for CONDVAR_WAIT here, but that is now covered by 546 // the _thread_blocked with self-suspension check. 547 // 548 // Return true since we wouldn't be here unless there was still an 549 // external suspend request. 550 *bits |= 0x00001000; 551 return true; 552 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { 553 // Threads running native code will self-suspend on native==>VM/Java 554 // transitions. If its stack is walkable (should always be the case 555 // unless this function is called before the actual java_suspend() 556 // call), then the wait is done. 557 *bits |= 0x00002000; 558 return true; 559 } else if (!called_by_wait && !did_trans_retry && 560 save_state == _thread_in_native_trans && 561 frame_anchor()->walkable()) { 562 // The thread is transitioning from thread_in_native to another 563 // thread state. check_safepoint_and_suspend_for_native_trans() 564 // will force the thread to self-suspend. If it hasn't gotten 565 // there yet we may have caught the thread in-between the native 566 // code check above and the self-suspend. Lucky us. If we were 567 // called by wait_for_ext_suspend_completion(), then it 568 // will be doing the retries so we don't have to. 569 // 570 // Since we use the saved thread state in the if-statement above, 571 // there is a chance that the thread has already transitioned to 572 // _thread_blocked by the time we get here. In that case, we will 573 // make a single unnecessary pass through the logic below. This 574 // doesn't hurt anything since we still do the trans retry. 575 576 *bits |= 0x00004000; 577 578 // Once the thread leaves thread_in_native_trans for another 579 // thread state, we break out of this retry loop. We shouldn't 580 // need this flag to prevent us from getting back here, but 581 // sometimes paranoia is good. 582 did_trans_retry = true; 583 584 // We wait for the thread to transition to a more usable state. 585 for (int i = 1; i <= SuspendRetryCount; i++) { 586 // We used to do an "os::yield_all(i)" call here with the intention 587 // that yielding would increase on each retry. However, the parameter 588 // is ignored on Linux which means the yield didn't scale up. Waiting 589 // on the SR_lock below provides a much more predictable scale up for 590 // the delay. It also provides a simple/direct point to check for any 591 // safepoint requests from the VMThread 592 593 // temporarily drops SR_lock while doing wait with safepoint check 594 // (if we're a JavaThread - the WatcherThread can also call this) 595 // and increase delay with each retry 596 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 597 598 // check the actual thread state instead of what we saved above 599 if (thread_state() != _thread_in_native_trans) { 600 // the thread has transitioned to another thread state so 601 // try all the checks (except this one) one more time. 602 do_trans_retry = true; 603 break; 604 } 605 } // end retry loop 606 607 608 } 609 } while (do_trans_retry); 610 611 *bits |= 0x00000010; 612 return false; 613} 614 615// 616// Wait for an external suspend request to complete (or be cancelled). 617// Returns true if the thread is externally suspended and false otherwise. 618// 619bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, 620 uint32_t *bits) { 621 TraceSuspendDebugBits tsdb(this, true /* is_wait */, 622 false /* !called_by_wait */, bits); 623 624 // local flag copies to minimize SR_lock hold time 625 bool is_suspended; 626 bool pending; 627 uint32_t reset_bits; 628 629 // set a marker so is_ext_suspend_completed() knows we are the caller 630 *bits |= 0x00010000; 631 632 // We use reset_bits to reinitialize the bits value at the top of 633 // each retry loop. This allows the caller to make use of any 634 // unused bits for their own marking purposes. 635 reset_bits = *bits; 636 637 { 638 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 639 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 640 delay, bits); 641 pending = is_external_suspend(); 642 } 643 // must release SR_lock to allow suspension to complete 644 645 if (!pending) { 646 // A cancelled suspend request is the only false return from 647 // is_ext_suspend_completed() that keeps us from entering the 648 // retry loop. 649 *bits |= 0x00020000; 650 return false; 651 } 652 653 if (is_suspended) { 654 *bits |= 0x00040000; 655 return true; 656 } 657 658 for (int i = 1; i <= retries; i++) { 659 *bits = reset_bits; // reinit to only track last retry 660 661 // We used to do an "os::yield_all(i)" call here with the intention 662 // that yielding would increase on each retry. However, the parameter 663 // is ignored on Linux which means the yield didn't scale up. Waiting 664 // on the SR_lock below provides a much more predictable scale up for 665 // the delay. It also provides a simple/direct point to check for any 666 // safepoint requests from the VMThread 667 668 { 669 MutexLocker ml(SR_lock()); 670 // wait with safepoint check (if we're a JavaThread - the WatcherThread 671 // can also call this) and increase delay with each retry 672 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); 673 674 is_suspended = is_ext_suspend_completed(true /* called_by_wait */, 675 delay, bits); 676 677 // It is possible for the external suspend request to be cancelled 678 // (by a resume) before the actual suspend operation is completed. 679 // Refresh our local copy to see if we still need to wait. 680 pending = is_external_suspend(); 681 } 682 683 if (!pending) { 684 // A cancelled suspend request is the only false return from 685 // is_ext_suspend_completed() that keeps us from staying in the 686 // retry loop. 687 *bits |= 0x00080000; 688 return false; 689 } 690 691 if (is_suspended) { 692 *bits |= 0x00100000; 693 return true; 694 } 695 } // end retry loop 696 697 // thread did not suspend after all our retries 698 *bits |= 0x00200000; 699 return false; 700} 701 702#ifndef PRODUCT 703void JavaThread::record_jump(address target, address instr, const char* file, int line) { 704 705 // This should not need to be atomic as the only way for simultaneous 706 // updates is via interrupts. Even then this should be rare or non-existant 707 // and we don't care that much anyway. 708 709 int index = _jmp_ring_index; 710 _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1); 711 _jmp_ring[index]._target = (intptr_t) target; 712 _jmp_ring[index]._instruction = (intptr_t) instr; 713 _jmp_ring[index]._file = file; 714 _jmp_ring[index]._line = line; 715} 716#endif /* PRODUCT */ 717 718// Called by flat profiler 719// Callers have already called wait_for_ext_suspend_completion 720// The assertion for that is currently too complex to put here: 721bool JavaThread::profile_last_Java_frame(frame* _fr) { 722 bool gotframe = false; 723 // self suspension saves needed state. 724 if (has_last_Java_frame() && _anchor.walkable()) { 725 *_fr = pd_last_frame(); 726 gotframe = true; 727 } 728 return gotframe; 729} 730 731void Thread::interrupt(Thread* thread) { 732 trace("interrupt", thread); 733 debug_only(check_for_dangling_thread_pointer(thread);) 734 os::interrupt(thread); 735} 736 737bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { 738 trace("is_interrupted", thread); 739 debug_only(check_for_dangling_thread_pointer(thread);) 740 // Note: If clear_interrupted==false, this simply fetches and 741 // returns the value of the field osthread()->interrupted(). 742 return os::is_interrupted(thread, clear_interrupted); 743} 744 745 746// GC Support 747bool Thread::claim_oops_do_par_case(int strong_roots_parity) { 748 jint thread_parity = _oops_do_parity; 749 if (thread_parity != strong_roots_parity) { 750 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); 751 if (res == thread_parity) return true; 752 else { 753 guarantee(res == strong_roots_parity, "Or else what?"); 754 assert(SharedHeap::heap()->n_par_threads() > 0, 755 "Should only fail when parallel."); 756 return false; 757 } 758 } 759 assert(SharedHeap::heap()->n_par_threads() > 0, 760 "Should only fail when parallel."); 761 return false; 762} 763 764void Thread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 765 active_handles()->oops_do(f); 766 // Do oop for ThreadShadow 767 f->do_oop((oop*)&_pending_exception); 768 handle_area()->oops_do(f); 769} 770 771void Thread::nmethods_do(CodeBlobClosure* cf) { 772 // no nmethods in a generic thread... 773} 774 775void Thread::print_on(outputStream* st) const { 776 // get_priority assumes osthread initialized 777 if (osthread() != NULL) { 778 st->print("prio=%d tid=" INTPTR_FORMAT " ", get_priority(this), this); 779 osthread()->print_on(st); 780 } 781 debug_only(if (WizardMode) print_owned_locks_on(st);) 782} 783 784// Thread::print_on_error() is called by fatal error handler. Don't use 785// any lock or allocate memory. 786void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { 787 if (is_VM_thread()) st->print("VMThread"); 788 else if (is_Compiler_thread()) st->print("CompilerThread"); 789 else if (is_Java_thread()) st->print("JavaThread"); 790 else if (is_GC_task_thread()) st->print("GCTaskThread"); 791 else if (is_Watcher_thread()) st->print("WatcherThread"); 792 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); 793 else st->print("Thread"); 794 795 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", 796 _stack_base - _stack_size, _stack_base); 797 798 if (osthread()) { 799 st->print(" [id=%d]", osthread()->thread_id()); 800 } 801} 802 803#ifdef ASSERT 804void Thread::print_owned_locks_on(outputStream* st) const { 805 Monitor *cur = _owned_locks; 806 if (cur == NULL) { 807 st->print(" (no locks) "); 808 } else { 809 st->print_cr(" Locks owned:"); 810 while(cur) { 811 cur->print_on(st); 812 cur = cur->next(); 813 } 814 } 815} 816 817static int ref_use_count = 0; 818 819bool Thread::owns_locks_but_compiled_lock() const { 820 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 821 if (cur != Compile_lock) return true; 822 } 823 return false; 824} 825 826 827#endif 828 829#ifndef PRODUCT 830 831// The flag: potential_vm_operation notifies if this particular safepoint state could potential 832// invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that 833// no threads which allow_vm_block's are held 834void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { 835 // Check if current thread is allowed to block at a safepoint 836 if (!(_allow_safepoint_count == 0)) 837 fatal("Possible safepoint reached by thread that does not allow it"); 838 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { 839 fatal("LEAF method calling lock?"); 840 } 841 842#ifdef ASSERT 843 if (potential_vm_operation && is_Java_thread() 844 && !Universe::is_bootstrapping()) { 845 // Make sure we do not hold any locks that the VM thread also uses. 846 // This could potentially lead to deadlocks 847 for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { 848 // Threads_lock is special, since the safepoint synchronization will not start before this is 849 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, 850 // since it is used to transfer control between JavaThreads and the VMThread 851 // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first! 852 if ( (cur->allow_vm_block() && 853 cur != Threads_lock && 854 cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation 855 cur != VMOperationRequest_lock && 856 cur != VMOperationQueue_lock) || 857 cur->rank() == Mutex::special) { 858 warning("Thread holding lock at safepoint that vm can block on: %s", cur->name()); 859 } 860 } 861 } 862 863 if (GCALotAtAllSafepoints) { 864 // We could enter a safepoint here and thus have a gc 865 InterfaceSupport::check_gc_alot(); 866 } 867#endif 868} 869#endif 870 871bool Thread::is_in_stack(address adr) const { 872 assert(Thread::current() == this, "is_in_stack can only be called from current thread"); 873 address end = os::current_stack_pointer(); 874 if (stack_base() >= adr && adr >= end) return true; 875 876 return false; 877} 878 879 880// We had to move these methods here, because vm threads get into ObjectSynchronizer::enter 881// However, there is a note in JavaThread::is_lock_owned() about the VM threads not being 882// used for compilation in the future. If that change is made, the need for these methods 883// should be revisited, and they should be removed if possible. 884 885bool Thread::is_lock_owned(address adr) const { 886 return on_local_stack(adr); 887} 888 889bool Thread::set_as_starting_thread() { 890 // NOTE: this must be called inside the main thread. 891 return os::create_main_thread((JavaThread*)this); 892} 893 894static void initialize_class(Symbol* class_name, TRAPS) { 895 klassOop klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); 896 instanceKlass::cast(klass)->initialize(CHECK); 897} 898 899 900// Creates the initial ThreadGroup 901static Handle create_initial_thread_group(TRAPS) { 902 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); 903 instanceKlassHandle klass (THREAD, k); 904 905 Handle system_instance = klass->allocate_instance_handle(CHECK_NH); 906 { 907 JavaValue result(T_VOID); 908 JavaCalls::call_special(&result, 909 system_instance, 910 klass, 911 vmSymbols::object_initializer_name(), 912 vmSymbols::void_method_signature(), 913 CHECK_NH); 914 } 915 Universe::set_system_thread_group(system_instance()); 916 917 Handle main_instance = klass->allocate_instance_handle(CHECK_NH); 918 { 919 JavaValue result(T_VOID); 920 Handle string = java_lang_String::create_from_str("main", CHECK_NH); 921 JavaCalls::call_special(&result, 922 main_instance, 923 klass, 924 vmSymbols::object_initializer_name(), 925 vmSymbols::threadgroup_string_void_signature(), 926 system_instance, 927 string, 928 CHECK_NH); 929 } 930 return main_instance; 931} 932 933// Creates the initial Thread 934static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) { 935 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); 936 instanceKlassHandle klass (THREAD, k); 937 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); 938 939 java_lang_Thread::set_thread(thread_oop(), thread); 940 java_lang_Thread::set_priority(thread_oop(), NormPriority); 941 thread->set_threadObj(thread_oop()); 942 943 Handle string = java_lang_String::create_from_str("main", CHECK_NULL); 944 945 JavaValue result(T_VOID); 946 JavaCalls::call_special(&result, thread_oop, 947 klass, 948 vmSymbols::object_initializer_name(), 949 vmSymbols::threadgroup_string_void_signature(), 950 thread_group, 951 string, 952 CHECK_NULL); 953 return thread_oop(); 954} 955 956static void call_initializeSystemClass(TRAPS) { 957 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 958 instanceKlassHandle klass (THREAD, k); 959 960 JavaValue result(T_VOID); 961 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), 962 vmSymbols::void_method_signature(), CHECK); 963} 964 965#ifdef KERNEL 966static void set_jkernel_boot_classloader_hook(TRAPS) { 967 klassOop k = SystemDictionary::sun_jkernel_DownloadManager_klass(); 968 instanceKlassHandle klass (THREAD, k); 969 970 if (k == NULL) { 971 // sun.jkernel.DownloadManager may not present in the JDK; just return 972 return; 973 } 974 975 JavaValue result(T_VOID); 976 JavaCalls::call_static(&result, klass, vmSymbols::setBootClassLoaderHook_name(), 977 vmSymbols::void_method_signature(), CHECK); 978} 979#endif // KERNEL 980 981// General purpose hook into Java code, run once when the VM is initialized. 982// The Java library method itself may be changed independently from the VM. 983static void call_postVMInitHook(TRAPS) { 984 klassOop k = SystemDictionary::sun_misc_PostVMInitHook_klass(); 985 instanceKlassHandle klass (THREAD, k); 986 if (klass.not_null()) { 987 JavaValue result(T_VOID); 988 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), 989 vmSymbols::void_method_signature(), 990 CHECK); 991 } 992} 993 994static void reset_vm_info_property(TRAPS) { 995 // the vm info string 996 ResourceMark rm(THREAD); 997 const char *vm_info = VM_Version::vm_info_string(); 998 999 // java.lang.System class 1000 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); 1001 instanceKlassHandle klass (THREAD, k); 1002 1003 // setProperty arguments 1004 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); 1005 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); 1006 1007 // return value 1008 JavaValue r(T_OBJECT); 1009 1010 // public static String setProperty(String key, String value); 1011 JavaCalls::call_static(&r, 1012 klass, 1013 vmSymbols::setProperty_name(), 1014 vmSymbols::string_string_string_signature(), 1015 key_str, 1016 value_str, 1017 CHECK); 1018} 1019 1020 1021void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) { 1022 assert(thread_group.not_null(), "thread group should be specified"); 1023 assert(threadObj() == NULL, "should only create Java thread object once"); 1024 1025 klassOop k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); 1026 instanceKlassHandle klass (THREAD, k); 1027 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); 1028 1029 java_lang_Thread::set_thread(thread_oop(), this); 1030 java_lang_Thread::set_priority(thread_oop(), NormPriority); 1031 set_threadObj(thread_oop()); 1032 1033 JavaValue result(T_VOID); 1034 if (thread_name != NULL) { 1035 Handle name = java_lang_String::create_from_str(thread_name, CHECK); 1036 // Thread gets assigned specified name and null target 1037 JavaCalls::call_special(&result, 1038 thread_oop, 1039 klass, 1040 vmSymbols::object_initializer_name(), 1041 vmSymbols::threadgroup_string_void_signature(), 1042 thread_group, // Argument 1 1043 name, // Argument 2 1044 THREAD); 1045 } else { 1046 // Thread gets assigned name "Thread-nnn" and null target 1047 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) 1048 JavaCalls::call_special(&result, 1049 thread_oop, 1050 klass, 1051 vmSymbols::object_initializer_name(), 1052 vmSymbols::threadgroup_runnable_void_signature(), 1053 thread_group, // Argument 1 1054 Handle(), // Argument 2 1055 THREAD); 1056 } 1057 1058 1059 if (daemon) { 1060 java_lang_Thread::set_daemon(thread_oop()); 1061 } 1062 1063 if (HAS_PENDING_EXCEPTION) { 1064 return; 1065 } 1066 1067 KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); 1068 Handle threadObj(this, this->threadObj()); 1069 1070 JavaCalls::call_special(&result, 1071 thread_group, 1072 group, 1073 vmSymbols::add_method_name(), 1074 vmSymbols::thread_void_signature(), 1075 threadObj, // Arg 1 1076 THREAD); 1077 1078 1079} 1080 1081// NamedThread -- non-JavaThread subclasses with multiple 1082// uniquely named instances should derive from this. 1083NamedThread::NamedThread() : Thread() { 1084 _name = NULL; 1085 _processed_thread = NULL; 1086} 1087 1088NamedThread::~NamedThread() { 1089 if (_name != NULL) { 1090 FREE_C_HEAP_ARRAY(char, _name); 1091 _name = NULL; 1092 } 1093} 1094 1095void NamedThread::set_name(const char* format, ...) { 1096 guarantee(_name == NULL, "Only get to set name once."); 1097 _name = NEW_C_HEAP_ARRAY(char, max_name_len); 1098 guarantee(_name != NULL, "alloc failure"); 1099 va_list ap; 1100 va_start(ap, format); 1101 jio_vsnprintf(_name, max_name_len, format, ap); 1102 va_end(ap); 1103} 1104 1105// ======= WatcherThread ======== 1106 1107// The watcher thread exists to simulate timer interrupts. It should 1108// be replaced by an abstraction over whatever native support for 1109// timer interrupts exists on the platform. 1110 1111WatcherThread* WatcherThread::_watcher_thread = NULL; 1112volatile bool WatcherThread::_should_terminate = false; 1113 1114WatcherThread::WatcherThread() : Thread() { 1115 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); 1116 if (os::create_thread(this, os::watcher_thread)) { 1117 _watcher_thread = this; 1118 1119 // Set the watcher thread to the highest OS priority which should not be 1120 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY 1121 // is created. The only normal thread using this priority is the reference 1122 // handler thread, which runs for very short intervals only. 1123 // If the VMThread's priority is not lower than the WatcherThread profiling 1124 // will be inaccurate. 1125 os::set_priority(this, MaxPriority); 1126 if (!DisableStartThread) { 1127 os::start_thread(this); 1128 } 1129 } 1130} 1131 1132void WatcherThread::run() { 1133 assert(this == watcher_thread(), "just checking"); 1134 1135 this->record_stack_base_and_size(); 1136 this->initialize_thread_local_storage(); 1137 this->set_active_handles(JNIHandleBlock::allocate_block()); 1138 while(!_should_terminate) { 1139 assert(watcher_thread() == Thread::current(), "thread consistency check"); 1140 assert(watcher_thread() == this, "thread consistency check"); 1141 1142 // Calculate how long it'll be until the next PeriodicTask work 1143 // should be done, and sleep that amount of time. 1144 size_t time_to_wait = PeriodicTask::time_to_wait(); 1145 1146 // we expect this to timeout - we only ever get unparked when 1147 // we should terminate 1148 { 1149 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); 1150 1151 jlong prev_time = os::javaTimeNanos(); 1152 for (;;) { 1153 int res= _SleepEvent->park(time_to_wait); 1154 if (res == OS_TIMEOUT || _should_terminate) 1155 break; 1156 // spurious wakeup of some kind 1157 jlong now = os::javaTimeNanos(); 1158 time_to_wait -= (now - prev_time) / 1000000; 1159 if (time_to_wait <= 0) 1160 break; 1161 prev_time = now; 1162 } 1163 } 1164 1165 if (is_error_reported()) { 1166 // A fatal error has happened, the error handler(VMError::report_and_die) 1167 // should abort JVM after creating an error log file. However in some 1168 // rare cases, the error handler itself might deadlock. Here we try to 1169 // kill JVM if the fatal error handler fails to abort in 2 minutes. 1170 // 1171 // This code is in WatcherThread because WatcherThread wakes up 1172 // periodically so the fatal error handler doesn't need to do anything; 1173 // also because the WatcherThread is less likely to crash than other 1174 // threads. 1175 1176 for (;;) { 1177 if (!ShowMessageBoxOnError 1178 && (OnError == NULL || OnError[0] == '\0') 1179 && Arguments::abort_hook() == NULL) { 1180 os::sleep(this, 2 * 60 * 1000, false); 1181 fdStream err(defaultStream::output_fd()); 1182 err.print_raw_cr("# [ timer expired, abort... ]"); 1183 // skip atexit/vm_exit/vm_abort hooks 1184 os::die(); 1185 } 1186 1187 // Wake up 5 seconds later, the fatal handler may reset OnError or 1188 // ShowMessageBoxOnError when it is ready to abort. 1189 os::sleep(this, 5 * 1000, false); 1190 } 1191 } 1192 1193 PeriodicTask::real_time_tick(time_to_wait); 1194 1195 // If we have no more tasks left due to dynamic disenrollment, 1196 // shut down the thread since we don't currently support dynamic enrollment 1197 if (PeriodicTask::num_tasks() == 0) { 1198 _should_terminate = true; 1199 } 1200 } 1201 1202 // Signal that it is terminated 1203 { 1204 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); 1205 _watcher_thread = NULL; 1206 Terminator_lock->notify(); 1207 } 1208 1209 // Thread destructor usually does this.. 1210 ThreadLocalStorage::set_thread(NULL); 1211} 1212 1213void WatcherThread::start() { 1214 if (watcher_thread() == NULL) { 1215 _should_terminate = false; 1216 // Create the single instance of WatcherThread 1217 new WatcherThread(); 1218 } 1219} 1220 1221void WatcherThread::stop() { 1222 // it is ok to take late safepoints here, if needed 1223 MutexLocker mu(Terminator_lock); 1224 _should_terminate = true; 1225 OrderAccess::fence(); // ensure WatcherThread sees update in main loop 1226 1227 Thread* watcher = watcher_thread(); 1228 if (watcher != NULL) 1229 watcher->_SleepEvent->unpark(); 1230 1231 while(watcher_thread() != NULL) { 1232 // This wait should make safepoint checks, wait without a timeout, 1233 // and wait as a suspend-equivalent condition. 1234 // 1235 // Note: If the FlatProfiler is running, then this thread is waiting 1236 // for the WatcherThread to terminate and the WatcherThread, via the 1237 // FlatProfiler task, is waiting for the external suspend request on 1238 // this thread to complete. wait_for_ext_suspend_completion() will 1239 // eventually timeout, but that takes time. Making this wait a 1240 // suspend-equivalent condition solves that timeout problem. 1241 // 1242 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 1243 Mutex::_as_suspend_equivalent_flag); 1244 } 1245} 1246 1247void WatcherThread::print_on(outputStream* st) const { 1248 st->print("\"%s\" ", name()); 1249 Thread::print_on(st); 1250 st->cr(); 1251} 1252 1253// ======= JavaThread ======== 1254 1255// A JavaThread is a normal Java thread 1256 1257void JavaThread::initialize() { 1258 // Initialize fields 1259 1260 // Set the claimed par_id to -1 (ie not claiming any par_ids) 1261 set_claimed_par_id(-1); 1262 1263 set_saved_exception_pc(NULL); 1264 set_threadObj(NULL); 1265 _anchor.clear(); 1266 set_entry_point(NULL); 1267 set_jni_functions(jni_functions()); 1268 set_callee_target(NULL); 1269 set_vm_result(NULL); 1270 set_vm_result_2(NULL); 1271 set_vframe_array_head(NULL); 1272 set_vframe_array_last(NULL); 1273 set_deferred_locals(NULL); 1274 set_deopt_mark(NULL); 1275 set_deopt_nmethod(NULL); 1276 clear_must_deopt_id(); 1277 set_monitor_chunks(NULL); 1278 set_next(NULL); 1279 set_thread_state(_thread_new); 1280 _terminated = _not_terminated; 1281 _privileged_stack_top = NULL; 1282 _array_for_gc = NULL; 1283 _suspend_equivalent = false; 1284 _in_deopt_handler = 0; 1285 _doing_unsafe_access = false; 1286 _stack_guard_state = stack_guard_unused; 1287 _exception_oop = NULL; 1288 _exception_pc = 0; 1289 _exception_handler_pc = 0; 1290 _exception_stack_size = 0; 1291 _is_method_handle_return = 0; 1292 _jvmti_thread_state= NULL; 1293 _should_post_on_exceptions_flag = JNI_FALSE; 1294 _jvmti_get_loaded_classes_closure = NULL; 1295 _interp_only_mode = 0; 1296 _special_runtime_exit_condition = _no_async_condition; 1297 _pending_async_exception = NULL; 1298 _is_compiling = false; 1299 _thread_stat = NULL; 1300 _thread_stat = new ThreadStatistics(); 1301 _blocked_on_compilation = false; 1302 _jni_active_critical = 0; 1303 _do_not_unlock_if_synchronized = false; 1304 _cached_monitor_info = NULL; 1305 _parker = Parker::Allocate(this) ; 1306 1307#ifndef PRODUCT 1308 _jmp_ring_index = 0; 1309 for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) { 1310 record_jump(NULL, NULL, NULL, 0); 1311 } 1312#endif /* PRODUCT */ 1313 1314 set_thread_profiler(NULL); 1315 if (FlatProfiler::is_active()) { 1316 // This is where we would decide to either give each thread it's own profiler 1317 // or use one global one from FlatProfiler, 1318 // or up to some count of the number of profiled threads, etc. 1319 ThreadProfiler* pp = new ThreadProfiler(); 1320 pp->engage(); 1321 set_thread_profiler(pp); 1322 } 1323 1324 // Setup safepoint state info for this thread 1325 ThreadSafepointState::create(this); 1326 1327 debug_only(_java_call_counter = 0); 1328 1329 // JVMTI PopFrame support 1330 _popframe_condition = popframe_inactive; 1331 _popframe_preserved_args = NULL; 1332 _popframe_preserved_args_size = 0; 1333 1334 pd_initialize(); 1335} 1336 1337#ifndef SERIALGC 1338SATBMarkQueueSet JavaThread::_satb_mark_queue_set; 1339DirtyCardQueueSet JavaThread::_dirty_card_queue_set; 1340#endif // !SERIALGC 1341 1342JavaThread::JavaThread(bool is_attaching) : 1343 Thread() 1344#ifndef SERIALGC 1345 , _satb_mark_queue(&_satb_mark_queue_set), 1346 _dirty_card_queue(&_dirty_card_queue_set) 1347#endif // !SERIALGC 1348{ 1349 initialize(); 1350 _is_attaching = is_attaching; 1351 assert(_deferred_card_mark.is_empty(), "Default MemRegion ctor"); 1352} 1353 1354bool JavaThread::reguard_stack(address cur_sp) { 1355 if (_stack_guard_state != stack_guard_yellow_disabled) { 1356 return true; // Stack already guarded or guard pages not needed. 1357 } 1358 1359 if (register_stack_overflow()) { 1360 // For those architectures which have separate register and 1361 // memory stacks, we must check the register stack to see if 1362 // it has overflowed. 1363 return false; 1364 } 1365 1366 // Java code never executes within the yellow zone: the latter is only 1367 // there to provoke an exception during stack banging. If java code 1368 // is executing there, either StackShadowPages should be larger, or 1369 // some exception code in c1, c2 or the interpreter isn't unwinding 1370 // when it should. 1371 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); 1372 1373 enable_stack_yellow_zone(); 1374 return true; 1375} 1376 1377bool JavaThread::reguard_stack(void) { 1378 return reguard_stack(os::current_stack_pointer()); 1379} 1380 1381 1382void JavaThread::block_if_vm_exited() { 1383 if (_terminated == _vm_exited) { 1384 // _vm_exited is set at safepoint, and Threads_lock is never released 1385 // we will block here forever 1386 Threads_lock->lock_without_safepoint_check(); 1387 ShouldNotReachHere(); 1388 } 1389} 1390 1391 1392// Remove this ifdef when C1 is ported to the compiler interface. 1393static void compiler_thread_entry(JavaThread* thread, TRAPS); 1394 1395JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : 1396 Thread() 1397#ifndef SERIALGC 1398 , _satb_mark_queue(&_satb_mark_queue_set), 1399 _dirty_card_queue(&_dirty_card_queue_set) 1400#endif // !SERIALGC 1401{ 1402 if (TraceThreadEvents) { 1403 tty->print_cr("creating thread %p", this); 1404 } 1405 initialize(); 1406 _is_attaching = false; 1407 set_entry_point(entry_point); 1408 // Create the native thread itself. 1409 // %note runtime_23 1410 os::ThreadType thr_type = os::java_thread; 1411 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : 1412 os::java_thread; 1413 os::create_thread(this, thr_type, stack_sz); 1414 1415 // The _osthread may be NULL here because we ran out of memory (too many threads active). 1416 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller 1417 // may hold a lock and all locks must be unlocked before throwing the exception (throwing 1418 // the exception consists of creating the exception object & initializing it, initialization 1419 // will leave the VM via a JavaCall and then all locks must be unlocked). 1420 // 1421 // The thread is still suspended when we reach here. Thread must be explicit started 1422 // by creator! Furthermore, the thread must also explicitly be added to the Threads list 1423 // by calling Threads:add. The reason why this is not done here, is because the thread 1424 // object must be fully initialized (take a look at JVM_Start) 1425} 1426 1427JavaThread::~JavaThread() { 1428 if (TraceThreadEvents) { 1429 tty->print_cr("terminate thread %p", this); 1430 } 1431 1432 // JSR166 -- return the parker to the free list 1433 Parker::Release(_parker); 1434 _parker = NULL ; 1435 1436 // Free any remaining previous UnrollBlock 1437 vframeArray* old_array = vframe_array_last(); 1438 1439 if (old_array != NULL) { 1440 Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); 1441 old_array->set_unroll_block(NULL); 1442 delete old_info; 1443 delete old_array; 1444 } 1445 1446 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals(); 1447 if (deferred != NULL) { 1448 // This can only happen if thread is destroyed before deoptimization occurs. 1449 assert(deferred->length() != 0, "empty array!"); 1450 do { 1451 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); 1452 deferred->remove_at(0); 1453 // individual jvmtiDeferredLocalVariableSet are CHeapObj's 1454 delete dlv; 1455 } while (deferred->length() != 0); 1456 delete deferred; 1457 } 1458 1459 // All Java related clean up happens in exit 1460 ThreadSafepointState::destroy(this); 1461 if (_thread_profiler != NULL) delete _thread_profiler; 1462 if (_thread_stat != NULL) delete _thread_stat; 1463} 1464 1465 1466// The first routine called by a new Java thread 1467void JavaThread::run() { 1468 // initialize thread-local alloc buffer related fields 1469 this->initialize_tlab(); 1470 1471 // used to test validitity of stack trace backs 1472 this->record_base_of_stack_pointer(); 1473 1474 // Record real stack base and size. 1475 this->record_stack_base_and_size(); 1476 1477 // Initialize thread local storage; set before calling MutexLocker 1478 this->initialize_thread_local_storage(); 1479 1480 this->create_stack_guard_pages(); 1481 1482 this->cache_global_variables(); 1483 1484 // Thread is now sufficient initialized to be handled by the safepoint code as being 1485 // in the VM. Change thread state from _thread_new to _thread_in_vm 1486 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); 1487 1488 assert(JavaThread::current() == this, "sanity check"); 1489 assert(!Thread::current()->owns_locks(), "sanity check"); 1490 1491 DTRACE_THREAD_PROBE(start, this); 1492 1493 // This operation might block. We call that after all safepoint checks for a new thread has 1494 // been completed. 1495 this->set_active_handles(JNIHandleBlock::allocate_block()); 1496 1497 if (JvmtiExport::should_post_thread_life()) { 1498 JvmtiExport::post_thread_start(this); 1499 } 1500 1501 // We call another function to do the rest so we are sure that the stack addresses used 1502 // from there will be lower than the stack base just computed 1503 thread_main_inner(); 1504 1505 // Note, thread is no longer valid at this point! 1506} 1507 1508 1509void JavaThread::thread_main_inner() { 1510 assert(JavaThread::current() == this, "sanity check"); 1511 assert(this->threadObj() != NULL, "just checking"); 1512 1513 // Execute thread entry point unless this thread has a pending exception 1514 // or has been stopped before starting. 1515 // Note: Due to JVM_StopThread we can have pending exceptions already! 1516 if (!this->has_pending_exception() && 1517 !java_lang_Thread::is_stillborn(this->threadObj())) { 1518 HandleMark hm(this); 1519 this->entry_point()(this, this); 1520 } 1521 1522 DTRACE_THREAD_PROBE(stop, this); 1523 1524 this->exit(false); 1525 delete this; 1526} 1527 1528 1529static void ensure_join(JavaThread* thread) { 1530 // We do not need to grap the Threads_lock, since we are operating on ourself. 1531 Handle threadObj(thread, thread->threadObj()); 1532 assert(threadObj.not_null(), "java thread object must exist"); 1533 ObjectLocker lock(threadObj, thread); 1534 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1535 thread->clear_pending_exception(); 1536 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. 1537 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); 1538 // Clear the native thread instance - this makes isAlive return false and allows the join() 1539 // to complete once we've done the notify_all below 1540 java_lang_Thread::set_thread(threadObj(), NULL); 1541 lock.notify_all(thread); 1542 // Ignore pending exception (ThreadDeath), since we are exiting anyway 1543 thread->clear_pending_exception(); 1544} 1545 1546 1547// For any new cleanup additions, please check to see if they need to be applied to 1548// cleanup_failed_attach_current_thread as well. 1549void JavaThread::exit(bool destroy_vm, ExitType exit_type) { 1550 assert(this == JavaThread::current(), "thread consistency check"); 1551 if (!InitializeJavaLangSystem) return; 1552 1553 HandleMark hm(this); 1554 Handle uncaught_exception(this, this->pending_exception()); 1555 this->clear_pending_exception(); 1556 Handle threadObj(this, this->threadObj()); 1557 assert(threadObj.not_null(), "Java thread object should be created"); 1558 1559 if (get_thread_profiler() != NULL) { 1560 get_thread_profiler()->disengage(); 1561 ResourceMark rm; 1562 get_thread_profiler()->print(get_thread_name()); 1563 } 1564 1565 1566 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place 1567 { 1568 EXCEPTION_MARK; 1569 1570 CLEAR_PENDING_EXCEPTION; 1571 } 1572 // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This 1573 // has to be fixed by a runtime query method 1574 if (!destroy_vm || JDK_Version::is_jdk12x_version()) { 1575 // JSR-166: change call from from ThreadGroup.uncaughtException to 1576 // java.lang.Thread.dispatchUncaughtException 1577 if (uncaught_exception.not_null()) { 1578 Handle group(this, java_lang_Thread::threadGroup(threadObj())); 1579 Events::log("uncaught exception INTPTR_FORMAT " " INTPTR_FORMAT " " INTPTR_FORMAT", 1580 (address)uncaught_exception(), (address)threadObj(), (address)group()); 1581 { 1582 EXCEPTION_MARK; 1583 // Check if the method Thread.dispatchUncaughtException() exists. If so 1584 // call it. Otherwise we have an older library without the JSR-166 changes, 1585 // so call ThreadGroup.uncaughtException() 1586 KlassHandle recvrKlass(THREAD, threadObj->klass()); 1587 CallInfo callinfo; 1588 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1589 LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass, 1590 vmSymbols::dispatchUncaughtException_name(), 1591 vmSymbols::throwable_void_signature(), 1592 KlassHandle(), false, false, THREAD); 1593 CLEAR_PENDING_EXCEPTION; 1594 methodHandle method = callinfo.selected_method(); 1595 if (method.not_null()) { 1596 JavaValue result(T_VOID); 1597 JavaCalls::call_virtual(&result, 1598 threadObj, thread_klass, 1599 vmSymbols::dispatchUncaughtException_name(), 1600 vmSymbols::throwable_void_signature(), 1601 uncaught_exception, 1602 THREAD); 1603 } else { 1604 KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass()); 1605 JavaValue result(T_VOID); 1606 JavaCalls::call_virtual(&result, 1607 group, thread_group, 1608 vmSymbols::uncaughtException_name(), 1609 vmSymbols::thread_throwable_void_signature(), 1610 threadObj, // Arg 1 1611 uncaught_exception, // Arg 2 1612 THREAD); 1613 } 1614 CLEAR_PENDING_EXCEPTION; 1615 } 1616 } 1617 1618 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during 1619 // the execution of the method. If that is not enough, then we don't really care. Thread.stop 1620 // is deprecated anyhow. 1621 { int count = 3; 1622 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { 1623 EXCEPTION_MARK; 1624 JavaValue result(T_VOID); 1625 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); 1626 JavaCalls::call_virtual(&result, 1627 threadObj, thread_klass, 1628 vmSymbols::exit_method_name(), 1629 vmSymbols::void_method_signature(), 1630 THREAD); 1631 CLEAR_PENDING_EXCEPTION; 1632 } 1633 } 1634 1635 // notify JVMTI 1636 if (JvmtiExport::should_post_thread_life()) { 1637 JvmtiExport::post_thread_end(this); 1638 } 1639 1640 // We have notified the agents that we are exiting, before we go on, 1641 // we must check for a pending external suspend request and honor it 1642 // in order to not surprise the thread that made the suspend request. 1643 while (true) { 1644 { 1645 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 1646 if (!is_external_suspend()) { 1647 set_terminated(_thread_exiting); 1648 ThreadService::current_thread_exiting(this); 1649 break; 1650 } 1651 // Implied else: 1652 // Things get a little tricky here. We have a pending external 1653 // suspend request, but we are holding the SR_lock so we 1654 // can't just self-suspend. So we temporarily drop the lock 1655 // and then self-suspend. 1656 } 1657 1658 ThreadBlockInVM tbivm(this); 1659 java_suspend_self(); 1660 1661 // We're done with this suspend request, but we have to loop around 1662 // and check again. Eventually we will get SR_lock without a pending 1663 // external suspend request and will be able to mark ourselves as 1664 // exiting. 1665 } 1666 // no more external suspends are allowed at this point 1667 } else { 1668 // before_exit() has already posted JVMTI THREAD_END events 1669 } 1670 1671 // Notify waiters on thread object. This has to be done after exit() is called 1672 // on the thread (if the thread is the last thread in a daemon ThreadGroup the 1673 // group should have the destroyed bit set before waiters are notified). 1674 ensure_join(this); 1675 assert(!this->has_pending_exception(), "ensure_join should have cleared"); 1676 1677 // 6282335 JNI DetachCurrentThread spec states that all Java monitors 1678 // held by this thread must be released. A detach operation must only 1679 // get here if there are no Java frames on the stack. Therefore, any 1680 // owned monitors at this point MUST be JNI-acquired monitors which are 1681 // pre-inflated and in the monitor cache. 1682 // 1683 // ensure_join() ignores IllegalThreadStateExceptions, and so does this. 1684 if (exit_type == jni_detach && JNIDetachReleasesMonitors) { 1685 assert(!this->has_last_Java_frame(), "detaching with Java frames?"); 1686 ObjectSynchronizer::release_monitors_owned_by_thread(this); 1687 assert(!this->has_pending_exception(), "release_monitors should have cleared"); 1688 } 1689 1690 // These things needs to be done while we are still a Java Thread. Make sure that thread 1691 // is in a consistent state, in case GC happens 1692 assert(_privileged_stack_top == NULL, "must be NULL when we get here"); 1693 1694 if (active_handles() != NULL) { 1695 JNIHandleBlock* block = active_handles(); 1696 set_active_handles(NULL); 1697 JNIHandleBlock::release_block(block); 1698 } 1699 1700 if (free_handle_block() != NULL) { 1701 JNIHandleBlock* block = free_handle_block(); 1702 set_free_handle_block(NULL); 1703 JNIHandleBlock::release_block(block); 1704 } 1705 1706 // These have to be removed while this is still a valid thread. 1707 remove_stack_guard_pages(); 1708 1709 if (UseTLAB) { 1710 tlab().make_parsable(true); // retire TLAB 1711 } 1712 1713 if (JvmtiEnv::environments_might_exist()) { 1714 JvmtiExport::cleanup_thread(this); 1715 } 1716 1717#ifndef SERIALGC 1718 // We must flush G1-related buffers before removing a thread from 1719 // the list of active threads. 1720 if (UseG1GC) { 1721 flush_barrier_queues(); 1722 } 1723#endif 1724 1725 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread 1726 Threads::remove(this); 1727} 1728 1729#ifndef SERIALGC 1730// Flush G1-related queues. 1731void JavaThread::flush_barrier_queues() { 1732 satb_mark_queue().flush(); 1733 dirty_card_queue().flush(); 1734} 1735 1736void JavaThread::initialize_queues() { 1737 assert(!SafepointSynchronize::is_at_safepoint(), 1738 "we should not be at a safepoint"); 1739 1740 ObjPtrQueue& satb_queue = satb_mark_queue(); 1741 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); 1742 // The SATB queue should have been constructed with its active 1743 // field set to false. 1744 assert(!satb_queue.is_active(), "SATB queue should not be active"); 1745 assert(satb_queue.is_empty(), "SATB queue should be empty"); 1746 // If we are creating the thread during a marking cycle, we should 1747 // set the active field of the SATB queue to true. 1748 if (satb_queue_set.is_active()) { 1749 satb_queue.set_active(true); 1750 } 1751 1752 DirtyCardQueue& dirty_queue = dirty_card_queue(); 1753 // The dirty card queue should have been constructed with its 1754 // active field set to true. 1755 assert(dirty_queue.is_active(), "dirty card queue should be active"); 1756} 1757#endif // !SERIALGC 1758 1759void JavaThread::cleanup_failed_attach_current_thread() { 1760 if (get_thread_profiler() != NULL) { 1761 get_thread_profiler()->disengage(); 1762 ResourceMark rm; 1763 get_thread_profiler()->print(get_thread_name()); 1764 } 1765 1766 if (active_handles() != NULL) { 1767 JNIHandleBlock* block = active_handles(); 1768 set_active_handles(NULL); 1769 JNIHandleBlock::release_block(block); 1770 } 1771 1772 if (free_handle_block() != NULL) { 1773 JNIHandleBlock* block = free_handle_block(); 1774 set_free_handle_block(NULL); 1775 JNIHandleBlock::release_block(block); 1776 } 1777 1778 // These have to be removed while this is still a valid thread. 1779 remove_stack_guard_pages(); 1780 1781 if (UseTLAB) { 1782 tlab().make_parsable(true); // retire TLAB, if any 1783 } 1784 1785#ifndef SERIALGC 1786 if (UseG1GC) { 1787 flush_barrier_queues(); 1788 } 1789#endif 1790 1791 Threads::remove(this); 1792 delete this; 1793} 1794 1795 1796 1797 1798JavaThread* JavaThread::active() { 1799 Thread* thread = ThreadLocalStorage::thread(); 1800 assert(thread != NULL, "just checking"); 1801 if (thread->is_Java_thread()) { 1802 return (JavaThread*) thread; 1803 } else { 1804 assert(thread->is_VM_thread(), "this must be a vm thread"); 1805 VM_Operation* op = ((VMThread*) thread)->vm_operation(); 1806 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); 1807 assert(ret->is_Java_thread(), "must be a Java thread"); 1808 return ret; 1809 } 1810} 1811 1812bool JavaThread::is_lock_owned(address adr) const { 1813 if (Thread::is_lock_owned(adr)) return true; 1814 1815 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 1816 if (chunk->contains(adr)) return true; 1817 } 1818 1819 return false; 1820} 1821 1822 1823void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { 1824 chunk->set_next(monitor_chunks()); 1825 set_monitor_chunks(chunk); 1826} 1827 1828void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { 1829 guarantee(monitor_chunks() != NULL, "must be non empty"); 1830 if (monitor_chunks() == chunk) { 1831 set_monitor_chunks(chunk->next()); 1832 } else { 1833 MonitorChunk* prev = monitor_chunks(); 1834 while (prev->next() != chunk) prev = prev->next(); 1835 prev->set_next(chunk->next()); 1836 } 1837} 1838 1839// JVM support. 1840 1841// Note: this function shouldn't block if it's called in 1842// _thread_in_native_trans state (such as from 1843// check_special_condition_for_native_trans()). 1844void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { 1845 1846 if (has_last_Java_frame() && has_async_condition()) { 1847 // If we are at a polling page safepoint (not a poll return) 1848 // then we must defer async exception because live registers 1849 // will be clobbered by the exception path. Poll return is 1850 // ok because the call we a returning from already collides 1851 // with exception handling registers and so there is no issue. 1852 // (The exception handling path kills call result registers but 1853 // this is ok since the exception kills the result anyway). 1854 1855 if (is_at_poll_safepoint()) { 1856 // if the code we are returning to has deoptimized we must defer 1857 // the exception otherwise live registers get clobbered on the 1858 // exception path before deoptimization is able to retrieve them. 1859 // 1860 RegisterMap map(this, false); 1861 frame caller_fr = last_frame().sender(&map); 1862 assert(caller_fr.is_compiled_frame(), "what?"); 1863 if (caller_fr.is_deoptimized_frame()) { 1864 if (TraceExceptions) { 1865 ResourceMark rm; 1866 tty->print_cr("deferred async exception at compiled safepoint"); 1867 } 1868 return; 1869 } 1870 } 1871 } 1872 1873 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); 1874 if (condition == _no_async_condition) { 1875 // Conditions have changed since has_special_runtime_exit_condition() 1876 // was called: 1877 // - if we were here only because of an external suspend request, 1878 // then that was taken care of above (or cancelled) so we are done 1879 // - if we were here because of another async request, then it has 1880 // been cleared between the has_special_runtime_exit_condition() 1881 // and now so again we are done 1882 return; 1883 } 1884 1885 // Check for pending async. exception 1886 if (_pending_async_exception != NULL) { 1887 // Only overwrite an already pending exception, if it is not a threadDeath. 1888 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { 1889 1890 // We cannot call Exceptions::_throw(...) here because we cannot block 1891 set_pending_exception(_pending_async_exception, __FILE__, __LINE__); 1892 1893 if (TraceExceptions) { 1894 ResourceMark rm; 1895 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); 1896 if (has_last_Java_frame() ) { 1897 frame f = last_frame(); 1898 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); 1899 } 1900 tty->print_cr(" of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 1901 } 1902 _pending_async_exception = NULL; 1903 clear_has_async_exception(); 1904 } 1905 } 1906 1907 if (check_unsafe_error && 1908 condition == _async_unsafe_access_error && !has_pending_exception()) { 1909 condition = _no_async_condition; // done 1910 switch (thread_state()) { 1911 case _thread_in_vm: 1912 { 1913 JavaThread* THREAD = this; 1914 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1915 } 1916 case _thread_in_native: 1917 { 1918 ThreadInVMfromNative tiv(this); 1919 JavaThread* THREAD = this; 1920 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); 1921 } 1922 case _thread_in_Java: 1923 { 1924 ThreadInVMfromJava tiv(this); 1925 JavaThread* THREAD = this; 1926 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); 1927 } 1928 default: 1929 ShouldNotReachHere(); 1930 } 1931 } 1932 1933 assert(condition == _no_async_condition || has_pending_exception() || 1934 (!check_unsafe_error && condition == _async_unsafe_access_error), 1935 "must have handled the async condition, if no exception"); 1936} 1937 1938void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { 1939 // 1940 // Check for pending external suspend. Internal suspend requests do 1941 // not use handle_special_runtime_exit_condition(). 1942 // If JNIEnv proxies are allowed, don't self-suspend if the target 1943 // thread is not the current thread. In older versions of jdbx, jdbx 1944 // threads could call into the VM with another thread's JNIEnv so we 1945 // can be here operating on behalf of a suspended thread (4432884). 1946 bool do_self_suspend = is_external_suspend_with_lock(); 1947 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { 1948 // 1949 // Because thread is external suspended the safepoint code will count 1950 // thread as at a safepoint. This can be odd because we can be here 1951 // as _thread_in_Java which would normally transition to _thread_blocked 1952 // at a safepoint. We would like to mark the thread as _thread_blocked 1953 // before calling java_suspend_self like all other callers of it but 1954 // we must then observe proper safepoint protocol. (We can't leave 1955 // _thread_blocked with a safepoint in progress). However we can be 1956 // here as _thread_in_native_trans so we can't use a normal transition 1957 // constructor/destructor pair because they assert on that type of 1958 // transition. We could do something like: 1959 // 1960 // JavaThreadState state = thread_state(); 1961 // set_thread_state(_thread_in_vm); 1962 // { 1963 // ThreadBlockInVM tbivm(this); 1964 // java_suspend_self() 1965 // } 1966 // set_thread_state(_thread_in_vm_trans); 1967 // if (safepoint) block; 1968 // set_thread_state(state); 1969 // 1970 // but that is pretty messy. Instead we just go with the way the 1971 // code has worked before and note that this is the only path to 1972 // java_suspend_self that doesn't put the thread in _thread_blocked 1973 // mode. 1974 1975 frame_anchor()->make_walkable(this); 1976 java_suspend_self(); 1977 1978 // We might be here for reasons in addition to the self-suspend request 1979 // so check for other async requests. 1980 } 1981 1982 if (check_asyncs) { 1983 check_and_handle_async_exceptions(); 1984 } 1985} 1986 1987void JavaThread::send_thread_stop(oop java_throwable) { 1988 assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); 1989 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); 1990 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); 1991 1992 // Do not throw asynchronous exceptions against the compiler thread 1993 // (the compiler thread should not be a Java thread -- fix in 1.4.2) 1994 if (is_Compiler_thread()) return; 1995 1996 { 1997 // Actually throw the Throwable against the target Thread - however 1998 // only if there is no thread death exception installed already. 1999 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { 2000 // If the topmost frame is a runtime stub, then we are calling into 2001 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) 2002 // must deoptimize the caller before continuing, as the compiled exception handler table 2003 // may not be valid 2004 if (has_last_Java_frame()) { 2005 frame f = last_frame(); 2006 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { 2007 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2008 RegisterMap reg_map(this, UseBiasedLocking); 2009 frame compiled_frame = f.sender(®_map); 2010 if (compiled_frame.can_be_deoptimized()) { 2011 Deoptimization::deoptimize(this, compiled_frame, ®_map); 2012 } 2013 } 2014 } 2015 2016 // Set async. pending exception in thread. 2017 set_pending_async_exception(java_throwable); 2018 2019 if (TraceExceptions) { 2020 ResourceMark rm; 2021 tty->print_cr("Pending Async. exception installed of type: %s", instanceKlass::cast(_pending_async_exception->klass())->external_name()); 2022 } 2023 // for AbortVMOnException flag 2024 NOT_PRODUCT(Exceptions::debug_check_abort(instanceKlass::cast(_pending_async_exception->klass())->external_name())); 2025 } 2026 } 2027 2028 2029 // Interrupt thread so it will wake up from a potential wait() 2030 Thread::interrupt(this); 2031} 2032 2033// External suspension mechanism. 2034// 2035// Tell the VM to suspend a thread when ever it knows that it does not hold on 2036// to any VM_locks and it is at a transition 2037// Self-suspension will happen on the transition out of the vm. 2038// Catch "this" coming in from JNIEnv pointers when the thread has been freed 2039// 2040// Guarantees on return: 2041// + Target thread will not execute any new bytecode (that's why we need to 2042// force a safepoint) 2043// + Target thread will not enter any new monitors 2044// 2045void JavaThread::java_suspend() { 2046 { MutexLocker mu(Threads_lock); 2047 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { 2048 return; 2049 } 2050 } 2051 2052 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2053 if (!is_external_suspend()) { 2054 // a racing resume has cancelled us; bail out now 2055 return; 2056 } 2057 2058 // suspend is done 2059 uint32_t debug_bits = 0; 2060 // Warning: is_ext_suspend_completed() may temporarily drop the 2061 // SR_lock to allow the thread to reach a stable thread state if 2062 // it is currently in a transient thread state. 2063 if (is_ext_suspend_completed(false /* !called_by_wait */, 2064 SuspendRetryDelay, &debug_bits) ) { 2065 return; 2066 } 2067 } 2068 2069 VM_ForceSafepoint vm_suspend; 2070 VMThread::execute(&vm_suspend); 2071} 2072 2073// Part II of external suspension. 2074// A JavaThread self suspends when it detects a pending external suspend 2075// request. This is usually on transitions. It is also done in places 2076// where continuing to the next transition would surprise the caller, 2077// e.g., monitor entry. 2078// 2079// Returns the number of times that the thread self-suspended. 2080// 2081// Note: DO NOT call java_suspend_self() when you just want to block current 2082// thread. java_suspend_self() is the second stage of cooperative 2083// suspension for external suspend requests and should only be used 2084// to complete an external suspend request. 2085// 2086int JavaThread::java_suspend_self() { 2087 int ret = 0; 2088 2089 // we are in the process of exiting so don't suspend 2090 if (is_exiting()) { 2091 clear_external_suspend(); 2092 return ret; 2093 } 2094 2095 assert(_anchor.walkable() || 2096 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), 2097 "must have walkable stack"); 2098 2099 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2100 2101 assert(!this->is_ext_suspended(), 2102 "a thread trying to self-suspend should not already be suspended"); 2103 2104 if (this->is_suspend_equivalent()) { 2105 // If we are self-suspending as a result of the lifting of a 2106 // suspend equivalent condition, then the suspend_equivalent 2107 // flag is not cleared until we set the ext_suspended flag so 2108 // that wait_for_ext_suspend_completion() returns consistent 2109 // results. 2110 this->clear_suspend_equivalent(); 2111 } 2112 2113 // A racing resume may have cancelled us before we grabbed SR_lock 2114 // above. Or another external suspend request could be waiting for us 2115 // by the time we return from SR_lock()->wait(). The thread 2116 // that requested the suspension may already be trying to walk our 2117 // stack and if we return now, we can change the stack out from under 2118 // it. This would be a "bad thing (TM)" and cause the stack walker 2119 // to crash. We stay self-suspended until there are no more pending 2120 // external suspend requests. 2121 while (is_external_suspend()) { 2122 ret++; 2123 this->set_ext_suspended(); 2124 2125 // _ext_suspended flag is cleared by java_resume() 2126 while (is_ext_suspended()) { 2127 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); 2128 } 2129 } 2130 2131 return ret; 2132} 2133 2134#ifdef ASSERT 2135// verify the JavaThread has not yet been published in the Threads::list, and 2136// hence doesn't need protection from concurrent access at this stage 2137void JavaThread::verify_not_published() { 2138 if (!Threads_lock->owned_by_self()) { 2139 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); 2140 assert( !Threads::includes(this), 2141 "java thread shouldn't have been published yet!"); 2142 } 2143 else { 2144 assert( !Threads::includes(this), 2145 "java thread shouldn't have been published yet!"); 2146 } 2147} 2148#endif 2149 2150// Slow path when the native==>VM/Java barriers detect a safepoint is in 2151// progress or when _suspend_flags is non-zero. 2152// Current thread needs to self-suspend if there is a suspend request and/or 2153// block if a safepoint is in progress. 2154// Async exception ISN'T checked. 2155// Note only the ThreadInVMfromNative transition can call this function 2156// directly and when thread state is _thread_in_native_trans 2157void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { 2158 assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); 2159 2160 JavaThread *curJT = JavaThread::current(); 2161 bool do_self_suspend = thread->is_external_suspend(); 2162 2163 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); 2164 2165 // If JNIEnv proxies are allowed, don't self-suspend if the target 2166 // thread is not the current thread. In older versions of jdbx, jdbx 2167 // threads could call into the VM with another thread's JNIEnv so we 2168 // can be here operating on behalf of a suspended thread (4432884). 2169 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { 2170 JavaThreadState state = thread->thread_state(); 2171 2172 // We mark this thread_blocked state as a suspend-equivalent so 2173 // that a caller to is_ext_suspend_completed() won't be confused. 2174 // The suspend-equivalent state is cleared by java_suspend_self(). 2175 thread->set_suspend_equivalent(); 2176 2177 // If the safepoint code sees the _thread_in_native_trans state, it will 2178 // wait until the thread changes to other thread state. There is no 2179 // guarantee on how soon we can obtain the SR_lock and complete the 2180 // self-suspend request. It would be a bad idea to let safepoint wait for 2181 // too long. Temporarily change the state to _thread_blocked to 2182 // let the VM thread know that this thread is ready for GC. The problem 2183 // of changing thread state is that safepoint could happen just after 2184 // java_suspend_self() returns after being resumed, and VM thread will 2185 // see the _thread_blocked state. We must check for safepoint 2186 // after restoring the state and make sure we won't leave while a safepoint 2187 // is in progress. 2188 thread->set_thread_state(_thread_blocked); 2189 thread->java_suspend_self(); 2190 thread->set_thread_state(state); 2191 // Make sure new state is seen by VM thread 2192 if (os::is_MP()) { 2193 if (UseMembar) { 2194 // Force a fence between the write above and read below 2195 OrderAccess::fence(); 2196 } else { 2197 // Must use this rather than serialization page in particular on Windows 2198 InterfaceSupport::serialize_memory(thread); 2199 } 2200 } 2201 } 2202 2203 if (SafepointSynchronize::do_call_back()) { 2204 // If we are safepointing, then block the caller which may not be 2205 // the same as the target thread (see above). 2206 SafepointSynchronize::block(curJT); 2207 } 2208 2209 if (thread->is_deopt_suspend()) { 2210 thread->clear_deopt_suspend(); 2211 RegisterMap map(thread, false); 2212 frame f = thread->last_frame(); 2213 while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { 2214 f = f.sender(&map); 2215 } 2216 if (f.id() == thread->must_deopt_id()) { 2217 thread->clear_must_deopt_id(); 2218 f.deoptimize(thread); 2219 } else { 2220 fatal("missed deoptimization!"); 2221 } 2222 } 2223} 2224 2225// Slow path when the native==>VM/Java barriers detect a safepoint is in 2226// progress or when _suspend_flags is non-zero. 2227// Current thread needs to self-suspend if there is a suspend request and/or 2228// block if a safepoint is in progress. 2229// Also check for pending async exception (not including unsafe access error). 2230// Note only the native==>VM/Java barriers can call this function and when 2231// thread state is _thread_in_native_trans. 2232void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { 2233 check_safepoint_and_suspend_for_native_trans(thread); 2234 2235 if (thread->has_async_exception()) { 2236 // We are in _thread_in_native_trans state, don't handle unsafe 2237 // access error since that may block. 2238 thread->check_and_handle_async_exceptions(false); 2239 } 2240} 2241 2242// We need to guarantee the Threads_lock here, since resumes are not 2243// allowed during safepoint synchronization 2244// Can only resume from an external suspension 2245void JavaThread::java_resume() { 2246 assert_locked_or_safepoint(Threads_lock); 2247 2248 // Sanity check: thread is gone, has started exiting or the thread 2249 // was not externally suspended. 2250 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { 2251 return; 2252 } 2253 2254 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); 2255 2256 clear_external_suspend(); 2257 2258 if (is_ext_suspended()) { 2259 clear_ext_suspended(); 2260 SR_lock()->notify_all(); 2261 } 2262} 2263 2264void JavaThread::create_stack_guard_pages() { 2265 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; 2266 address low_addr = stack_base() - stack_size(); 2267 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2268 2269 int allocate = os::allocate_stack_guard_pages(); 2270 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); 2271 2272 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { 2273 warning("Attempt to allocate stack guard pages failed."); 2274 return; 2275 } 2276 2277 if (os::guard_memory((char *) low_addr, len)) { 2278 _stack_guard_state = stack_guard_enabled; 2279 } else { 2280 warning("Attempt to protect stack guard pages failed."); 2281 if (os::uncommit_memory((char *) low_addr, len)) { 2282 warning("Attempt to deallocate stack guard pages failed."); 2283 } 2284 } 2285} 2286 2287void JavaThread::remove_stack_guard_pages() { 2288 if (_stack_guard_state == stack_guard_unused) return; 2289 address low_addr = stack_base() - stack_size(); 2290 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); 2291 2292 if (os::allocate_stack_guard_pages()) { 2293 if (os::remove_stack_guard_pages((char *) low_addr, len)) { 2294 _stack_guard_state = stack_guard_unused; 2295 } else { 2296 warning("Attempt to deallocate stack guard pages failed."); 2297 } 2298 } else { 2299 if (_stack_guard_state == stack_guard_unused) return; 2300 if (os::unguard_memory((char *) low_addr, len)) { 2301 _stack_guard_state = stack_guard_unused; 2302 } else { 2303 warning("Attempt to unprotect stack guard pages failed."); 2304 } 2305 } 2306} 2307 2308void JavaThread::enable_stack_yellow_zone() { 2309 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2310 assert(_stack_guard_state != stack_guard_enabled, "already enabled"); 2311 2312 // The base notation is from the stacks point of view, growing downward. 2313 // We need to adjust it to work correctly with guard_memory() 2314 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2315 2316 guarantee(base < stack_base(),"Error calculating stack yellow zone"); 2317 guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone"); 2318 2319 if (os::guard_memory((char *) base, stack_yellow_zone_size())) { 2320 _stack_guard_state = stack_guard_enabled; 2321 } else { 2322 warning("Attempt to guard stack yellow zone failed."); 2323 } 2324 enable_register_stack_guard(); 2325} 2326 2327void JavaThread::disable_stack_yellow_zone() { 2328 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2329 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); 2330 2331 // Simply return if called for a thread that does not use guard pages. 2332 if (_stack_guard_state == stack_guard_unused) return; 2333 2334 // The base notation is from the stacks point of view, growing downward. 2335 // We need to adjust it to work correctly with guard_memory() 2336 address base = stack_yellow_zone_base() - stack_yellow_zone_size(); 2337 2338 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { 2339 _stack_guard_state = stack_guard_yellow_disabled; 2340 } else { 2341 warning("Attempt to unguard stack yellow zone failed."); 2342 } 2343 disable_register_stack_guard(); 2344} 2345 2346void JavaThread::enable_stack_red_zone() { 2347 // The base notation is from the stacks point of view, growing downward. 2348 // We need to adjust it to work correctly with guard_memory() 2349 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2350 address base = stack_red_zone_base() - stack_red_zone_size(); 2351 2352 guarantee(base < stack_base(),"Error calculating stack red zone"); 2353 guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone"); 2354 2355 if(!os::guard_memory((char *) base, stack_red_zone_size())) { 2356 warning("Attempt to guard stack red zone failed."); 2357 } 2358} 2359 2360void JavaThread::disable_stack_red_zone() { 2361 // The base notation is from the stacks point of view, growing downward. 2362 // We need to adjust it to work correctly with guard_memory() 2363 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); 2364 address base = stack_red_zone_base() - stack_red_zone_size(); 2365 if (!os::unguard_memory((char *)base, stack_red_zone_size())) { 2366 warning("Attempt to unguard stack red zone failed."); 2367 } 2368} 2369 2370void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { 2371 // ignore is there is no stack 2372 if (!has_last_Java_frame()) return; 2373 // traverse the stack frames. Starts from top frame. 2374 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2375 frame* fr = fst.current(); 2376 f(fr, fst.register_map()); 2377 } 2378} 2379 2380 2381#ifndef PRODUCT 2382// Deoptimization 2383// Function for testing deoptimization 2384void JavaThread::deoptimize() { 2385 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2386 StackFrameStream fst(this, UseBiasedLocking); 2387 bool deopt = false; // Dump stack only if a deopt actually happens. 2388 bool only_at = strlen(DeoptimizeOnlyAt) > 0; 2389 // Iterate over all frames in the thread and deoptimize 2390 for(; !fst.is_done(); fst.next()) { 2391 if(fst.current()->can_be_deoptimized()) { 2392 2393 if (only_at) { 2394 // Deoptimize only at particular bcis. DeoptimizeOnlyAt 2395 // consists of comma or carriage return separated numbers so 2396 // search for the current bci in that string. 2397 address pc = fst.current()->pc(); 2398 nmethod* nm = (nmethod*) fst.current()->cb(); 2399 ScopeDesc* sd = nm->scope_desc_at( pc); 2400 char buffer[8]; 2401 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); 2402 size_t len = strlen(buffer); 2403 const char * found = strstr(DeoptimizeOnlyAt, buffer); 2404 while (found != NULL) { 2405 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && 2406 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { 2407 // Check that the bci found is bracketed by terminators. 2408 break; 2409 } 2410 found = strstr(found + 1, buffer); 2411 } 2412 if (!found) { 2413 continue; 2414 } 2415 } 2416 2417 if (DebugDeoptimization && !deopt) { 2418 deopt = true; // One-time only print before deopt 2419 tty->print_cr("[BEFORE Deoptimization]"); 2420 trace_frames(); 2421 trace_stack(); 2422 } 2423 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2424 } 2425 } 2426 2427 if (DebugDeoptimization && deopt) { 2428 tty->print_cr("[AFTER Deoptimization]"); 2429 trace_frames(); 2430 } 2431} 2432 2433 2434// Make zombies 2435void JavaThread::make_zombies() { 2436 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2437 if (fst.current()->can_be_deoptimized()) { 2438 // it is a Java nmethod 2439 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); 2440 nm->make_not_entrant(); 2441 } 2442 } 2443} 2444#endif // PRODUCT 2445 2446 2447void JavaThread::deoptimized_wrt_marked_nmethods() { 2448 if (!has_last_Java_frame()) return; 2449 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass 2450 StackFrameStream fst(this, UseBiasedLocking); 2451 for(; !fst.is_done(); fst.next()) { 2452 if (fst.current()->should_be_deoptimized()) { 2453 Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); 2454 } 2455 } 2456} 2457 2458 2459// GC support 2460static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); } 2461 2462void JavaThread::gc_epilogue() { 2463 frames_do(frame_gc_epilogue); 2464} 2465 2466 2467static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); } 2468 2469void JavaThread::gc_prologue() { 2470 frames_do(frame_gc_prologue); 2471} 2472 2473// If the caller is a NamedThread, then remember, in the current scope, 2474// the given JavaThread in its _processed_thread field. 2475class RememberProcessedThread: public StackObj { 2476 NamedThread* _cur_thr; 2477public: 2478 RememberProcessedThread(JavaThread* jthr) { 2479 Thread* thread = Thread::current(); 2480 if (thread->is_Named_thread()) { 2481 _cur_thr = (NamedThread *)thread; 2482 _cur_thr->set_processed_thread(jthr); 2483 } else { 2484 _cur_thr = NULL; 2485 } 2486 } 2487 2488 ~RememberProcessedThread() { 2489 if (_cur_thr) { 2490 _cur_thr->set_processed_thread(NULL); 2491 } 2492 } 2493}; 2494 2495void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) { 2496 // Verify that the deferred card marks have been flushed. 2497 assert(deferred_card_mark().is_empty(), "Should be empty during GC"); 2498 2499 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do 2500 // since there may be more than one thread using each ThreadProfiler. 2501 2502 // Traverse the GCHandles 2503 Thread::oops_do(f, cf); 2504 2505 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2506 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2507 2508 if (has_last_Java_frame()) { 2509 // Record JavaThread to GC thread 2510 RememberProcessedThread rpt(this); 2511 2512 // Traverse the privileged stack 2513 if (_privileged_stack_top != NULL) { 2514 _privileged_stack_top->oops_do(f); 2515 } 2516 2517 // traverse the registered growable array 2518 if (_array_for_gc != NULL) { 2519 for (int index = 0; index < _array_for_gc->length(); index++) { 2520 f->do_oop(_array_for_gc->adr_at(index)); 2521 } 2522 } 2523 2524 // Traverse the monitor chunks 2525 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { 2526 chunk->oops_do(f); 2527 } 2528 2529 // Traverse the execution stack 2530 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2531 fst.current()->oops_do(f, cf, fst.register_map()); 2532 } 2533 } 2534 2535 // callee_target is never live across a gc point so NULL it here should 2536 // it still contain a methdOop. 2537 2538 set_callee_target(NULL); 2539 2540 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); 2541 // If we have deferred set_locals there might be oops waiting to be 2542 // written 2543 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals(); 2544 if (list != NULL) { 2545 for (int i = 0; i < list->length(); i++) { 2546 list->at(i)->oops_do(f); 2547 } 2548 } 2549 2550 // Traverse instance variables at the end since the GC may be moving things 2551 // around using this function 2552 f->do_oop((oop*) &_threadObj); 2553 f->do_oop((oop*) &_vm_result); 2554 f->do_oop((oop*) &_vm_result_2); 2555 f->do_oop((oop*) &_exception_oop); 2556 f->do_oop((oop*) &_pending_async_exception); 2557 2558 if (jvmti_thread_state() != NULL) { 2559 jvmti_thread_state()->oops_do(f); 2560 } 2561} 2562 2563void JavaThread::nmethods_do(CodeBlobClosure* cf) { 2564 Thread::nmethods_do(cf); // (super method is a no-op) 2565 2566 assert( (!has_last_Java_frame() && java_call_counter() == 0) || 2567 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); 2568 2569 if (has_last_Java_frame()) { 2570 // Traverse the execution stack 2571 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2572 fst.current()->nmethods_do(cf); 2573 } 2574 } 2575} 2576 2577// Printing 2578const char* _get_thread_state_name(JavaThreadState _thread_state) { 2579 switch (_thread_state) { 2580 case _thread_uninitialized: return "_thread_uninitialized"; 2581 case _thread_new: return "_thread_new"; 2582 case _thread_new_trans: return "_thread_new_trans"; 2583 case _thread_in_native: return "_thread_in_native"; 2584 case _thread_in_native_trans: return "_thread_in_native_trans"; 2585 case _thread_in_vm: return "_thread_in_vm"; 2586 case _thread_in_vm_trans: return "_thread_in_vm_trans"; 2587 case _thread_in_Java: return "_thread_in_Java"; 2588 case _thread_in_Java_trans: return "_thread_in_Java_trans"; 2589 case _thread_blocked: return "_thread_blocked"; 2590 case _thread_blocked_trans: return "_thread_blocked_trans"; 2591 default: return "unknown thread state"; 2592 } 2593} 2594 2595#ifndef PRODUCT 2596void JavaThread::print_thread_state_on(outputStream *st) const { 2597 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); 2598}; 2599void JavaThread::print_thread_state() const { 2600 print_thread_state_on(tty); 2601}; 2602#endif // PRODUCT 2603 2604// Called by Threads::print() for VM_PrintThreads operation 2605void JavaThread::print_on(outputStream *st) const { 2606 st->print("\"%s\" ", get_thread_name()); 2607 oop thread_oop = threadObj(); 2608 if (thread_oop != NULL && java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); 2609 Thread::print_on(st); 2610 // print guess for valid stack memory region (assume 4K pages); helps lock debugging 2611 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); 2612 if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) { 2613 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); 2614 } 2615#ifndef PRODUCT 2616 print_thread_state_on(st); 2617 _safepoint_state->print_on(st); 2618#endif // PRODUCT 2619} 2620 2621// Called by fatal error handler. The difference between this and 2622// JavaThread::print() is that we can't grab lock or allocate memory. 2623void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { 2624 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); 2625 oop thread_obj = threadObj(); 2626 if (thread_obj != NULL) { 2627 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); 2628 } 2629 st->print(" ["); 2630 st->print("%s", _get_thread_state_name(_thread_state)); 2631 if (osthread()) { 2632 st->print(", id=%d", osthread()->thread_id()); 2633 } 2634 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", 2635 _stack_base - _stack_size, _stack_base); 2636 st->print("]"); 2637 return; 2638} 2639 2640// Verification 2641 2642static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } 2643 2644void JavaThread::verify() { 2645 // Verify oops in the thread. 2646 oops_do(&VerifyOopClosure::verify_oop, NULL); 2647 2648 // Verify the stack frames. 2649 frames_do(frame_verify); 2650} 2651 2652// CR 6300358 (sub-CR 2137150) 2653// Most callers of this method assume that it can't return NULL but a 2654// thread may not have a name whilst it is in the process of attaching to 2655// the VM - see CR 6412693, and there are places where a JavaThread can be 2656// seen prior to having it's threadObj set (eg JNI attaching threads and 2657// if vm exit occurs during initialization). These cases can all be accounted 2658// for such that this method never returns NULL. 2659const char* JavaThread::get_thread_name() const { 2660#ifdef ASSERT 2661 // early safepoints can hit while current thread does not yet have TLS 2662 if (!SafepointSynchronize::is_at_safepoint()) { 2663 Thread *cur = Thread::current(); 2664 if (!(cur->is_Java_thread() && cur == this)) { 2665 // Current JavaThreads are allowed to get their own name without 2666 // the Threads_lock. 2667 assert_locked_or_safepoint(Threads_lock); 2668 } 2669 } 2670#endif // ASSERT 2671 return get_thread_name_string(); 2672} 2673 2674// Returns a non-NULL representation of this thread's name, or a suitable 2675// descriptive string if there is no set name 2676const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { 2677 const char* name_str; 2678 oop thread_obj = threadObj(); 2679 if (thread_obj != NULL) { 2680 typeArrayOop name = java_lang_Thread::name(thread_obj); 2681 if (name != NULL) { 2682 if (buf == NULL) { 2683 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2684 } 2685 else { 2686 name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen); 2687 } 2688 } 2689 else if (is_attaching()) { // workaround for 6412693 - see 6404306 2690 name_str = "<no-name - thread is attaching>"; 2691 } 2692 else { 2693 name_str = Thread::name(); 2694 } 2695 } 2696 else { 2697 name_str = Thread::name(); 2698 } 2699 assert(name_str != NULL, "unexpected NULL thread name"); 2700 return name_str; 2701} 2702 2703 2704const char* JavaThread::get_threadgroup_name() const { 2705 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2706 oop thread_obj = threadObj(); 2707 if (thread_obj != NULL) { 2708 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2709 if (thread_group != NULL) { 2710 typeArrayOop name = java_lang_ThreadGroup::name(thread_group); 2711 // ThreadGroup.name can be null 2712 if (name != NULL) { 2713 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2714 return str; 2715 } 2716 } 2717 } 2718 return NULL; 2719} 2720 2721const char* JavaThread::get_parent_name() const { 2722 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) 2723 oop thread_obj = threadObj(); 2724 if (thread_obj != NULL) { 2725 oop thread_group = java_lang_Thread::threadGroup(thread_obj); 2726 if (thread_group != NULL) { 2727 oop parent = java_lang_ThreadGroup::parent(thread_group); 2728 if (parent != NULL) { 2729 typeArrayOop name = java_lang_ThreadGroup::name(parent); 2730 // ThreadGroup.name can be null 2731 if (name != NULL) { 2732 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); 2733 return str; 2734 } 2735 } 2736 } 2737 } 2738 return NULL; 2739} 2740 2741ThreadPriority JavaThread::java_priority() const { 2742 oop thr_oop = threadObj(); 2743 if (thr_oop == NULL) return NormPriority; // Bootstrapping 2744 ThreadPriority priority = java_lang_Thread::priority(thr_oop); 2745 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); 2746 return priority; 2747} 2748 2749void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { 2750 2751 assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); 2752 // Link Java Thread object <-> C++ Thread 2753 2754 // Get the C++ thread object (an oop) from the JNI handle (a jthread) 2755 // and put it into a new Handle. The Handle "thread_oop" can then 2756 // be used to pass the C++ thread object to other methods. 2757 2758 // Set the Java level thread object (jthread) field of the 2759 // new thread (a JavaThread *) to C++ thread object using the 2760 // "thread_oop" handle. 2761 2762 // Set the thread field (a JavaThread *) of the 2763 // oop representing the java_lang_Thread to the new thread (a JavaThread *). 2764 2765 Handle thread_oop(Thread::current(), 2766 JNIHandles::resolve_non_null(jni_thread)); 2767 assert(instanceKlass::cast(thread_oop->klass())->is_linked(), 2768 "must be initialized"); 2769 set_threadObj(thread_oop()); 2770 java_lang_Thread::set_thread(thread_oop(), this); 2771 2772 if (prio == NoPriority) { 2773 prio = java_lang_Thread::priority(thread_oop()); 2774 assert(prio != NoPriority, "A valid priority should be present"); 2775 } 2776 2777 // Push the Java priority down to the native thread; needs Threads_lock 2778 Thread::set_priority(this, prio); 2779 2780 // Add the new thread to the Threads list and set it in motion. 2781 // We must have threads lock in order to call Threads::add. 2782 // It is crucial that we do not block before the thread is 2783 // added to the Threads list for if a GC happens, then the java_thread oop 2784 // will not be visited by GC. 2785 Threads::add(this); 2786} 2787 2788oop JavaThread::current_park_blocker() { 2789 // Support for JSR-166 locks 2790 oop thread_oop = threadObj(); 2791 if (thread_oop != NULL && 2792 JDK_Version::current().supports_thread_park_blocker()) { 2793 return java_lang_Thread::park_blocker(thread_oop); 2794 } 2795 return NULL; 2796} 2797 2798 2799void JavaThread::print_stack_on(outputStream* st) { 2800 if (!has_last_Java_frame()) return; 2801 ResourceMark rm; 2802 HandleMark hm; 2803 2804 RegisterMap reg_map(this); 2805 vframe* start_vf = last_java_vframe(®_map); 2806 int count = 0; 2807 for (vframe* f = start_vf; f; f = f->sender() ) { 2808 if (f->is_java_frame()) { 2809 javaVFrame* jvf = javaVFrame::cast(f); 2810 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); 2811 2812 // Print out lock information 2813 if (JavaMonitorsInStackTrace) { 2814 jvf->print_lock_info_on(st, count); 2815 } 2816 } else { 2817 // Ignore non-Java frames 2818 } 2819 2820 // Bail-out case for too deep stacks 2821 count++; 2822 if (MaxJavaStackTraceDepth == count) return; 2823 } 2824} 2825 2826 2827// JVMTI PopFrame support 2828void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { 2829 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); 2830 if (in_bytes(size_in_bytes) != 0) { 2831 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes)); 2832 _popframe_preserved_args_size = in_bytes(size_in_bytes); 2833 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); 2834 } 2835} 2836 2837void* JavaThread::popframe_preserved_args() { 2838 return _popframe_preserved_args; 2839} 2840 2841ByteSize JavaThread::popframe_preserved_args_size() { 2842 return in_ByteSize(_popframe_preserved_args_size); 2843} 2844 2845WordSize JavaThread::popframe_preserved_args_size_in_words() { 2846 int sz = in_bytes(popframe_preserved_args_size()); 2847 assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); 2848 return in_WordSize(sz / wordSize); 2849} 2850 2851void JavaThread::popframe_free_preserved_args() { 2852 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); 2853 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args); 2854 _popframe_preserved_args = NULL; 2855 _popframe_preserved_args_size = 0; 2856} 2857 2858#ifndef PRODUCT 2859 2860void JavaThread::trace_frames() { 2861 tty->print_cr("[Describe stack]"); 2862 int frame_no = 1; 2863 for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { 2864 tty->print(" %d. ", frame_no++); 2865 fst.current()->print_value_on(tty,this); 2866 tty->cr(); 2867 } 2868} 2869 2870 2871void JavaThread::trace_stack_from(vframe* start_vf) { 2872 ResourceMark rm; 2873 int vframe_no = 1; 2874 for (vframe* f = start_vf; f; f = f->sender() ) { 2875 if (f->is_java_frame()) { 2876 javaVFrame::cast(f)->print_activation(vframe_no++); 2877 } else { 2878 f->print(); 2879 } 2880 if (vframe_no > StackPrintLimit) { 2881 tty->print_cr("...<more frames>..."); 2882 return; 2883 } 2884 } 2885} 2886 2887 2888void JavaThread::trace_stack() { 2889 if (!has_last_Java_frame()) return; 2890 ResourceMark rm; 2891 HandleMark hm; 2892 RegisterMap reg_map(this); 2893 trace_stack_from(last_java_vframe(®_map)); 2894} 2895 2896 2897#endif // PRODUCT 2898 2899 2900javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { 2901 assert(reg_map != NULL, "a map must be given"); 2902 frame f = last_frame(); 2903 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) { 2904 if (vf->is_java_frame()) return javaVFrame::cast(vf); 2905 } 2906 return NULL; 2907} 2908 2909 2910klassOop JavaThread::security_get_caller_class(int depth) { 2911 vframeStream vfst(this); 2912 vfst.security_get_caller_frame(depth); 2913 if (!vfst.at_end()) { 2914 return vfst.method()->method_holder(); 2915 } 2916 return NULL; 2917} 2918 2919static void compiler_thread_entry(JavaThread* thread, TRAPS) { 2920 assert(thread->is_Compiler_thread(), "must be compiler thread"); 2921 CompileBroker::compiler_thread_loop(); 2922} 2923 2924// Create a CompilerThread 2925CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters) 2926: JavaThread(&compiler_thread_entry) { 2927 _env = NULL; 2928 _log = NULL; 2929 _task = NULL; 2930 _queue = queue; 2931 _counters = counters; 2932 _buffer_blob = NULL; 2933 2934#ifndef PRODUCT 2935 _ideal_graph_printer = NULL; 2936#endif 2937} 2938 2939 2940// ======= Threads ======== 2941 2942// The Threads class links together all active threads, and provides 2943// operations over all threads. It is protected by its own Mutex 2944// lock, which is also used in other contexts to protect thread 2945// operations from having the thread being operated on from exiting 2946// and going away unexpectedly (e.g., safepoint synchronization) 2947 2948JavaThread* Threads::_thread_list = NULL; 2949int Threads::_number_of_threads = 0; 2950int Threads::_number_of_non_daemon_threads = 0; 2951int Threads::_return_code = 0; 2952size_t JavaThread::_stack_size_at_create = 0; 2953 2954// All JavaThreads 2955#define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) 2956 2957void os_stream(); 2958 2959// All JavaThreads + all non-JavaThreads (i.e., every thread in the system) 2960void Threads::threads_do(ThreadClosure* tc) { 2961 assert_locked_or_safepoint(Threads_lock); 2962 // ALL_JAVA_THREADS iterates through all JavaThreads 2963 ALL_JAVA_THREADS(p) { 2964 tc->do_thread(p); 2965 } 2966 // Someday we could have a table or list of all non-JavaThreads. 2967 // For now, just manually iterate through them. 2968 tc->do_thread(VMThread::vm_thread()); 2969 Universe::heap()->gc_threads_do(tc); 2970 WatcherThread *wt = WatcherThread::watcher_thread(); 2971 // Strictly speaking, the following NULL check isn't sufficient to make sure 2972 // the data for WatcherThread is still valid upon being examined. However, 2973 // considering that WatchThread terminates when the VM is on the way to 2974 // exit at safepoint, the chance of the above is extremely small. The right 2975 // way to prevent termination of WatcherThread would be to acquire 2976 // Terminator_lock, but we can't do that without violating the lock rank 2977 // checking in some cases. 2978 if (wt != NULL) 2979 tc->do_thread(wt); 2980 2981 // If CompilerThreads ever become non-JavaThreads, add them here 2982} 2983 2984jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { 2985 2986 extern void JDK_Version_init(); 2987 2988 // Check version 2989 if (!is_supported_jni_version(args->version)) return JNI_EVERSION; 2990 2991 // Initialize the output stream module 2992 ostream_init(); 2993 2994 // Process java launcher properties. 2995 Arguments::process_sun_java_launcher_properties(args); 2996 2997 // Initialize the os module before using TLS 2998 os::init(); 2999 3000 // Initialize system properties. 3001 Arguments::init_system_properties(); 3002 3003 // So that JDK version can be used as a discrimintor when parsing arguments 3004 JDK_Version_init(); 3005 3006 // Update/Initialize System properties after JDK version number is known 3007 Arguments::init_version_specific_system_properties(); 3008 3009 // Parse arguments 3010 jint parse_result = Arguments::parse(args); 3011 if (parse_result != JNI_OK) return parse_result; 3012 3013 if (PauseAtStartup) { 3014 os::pause(); 3015 } 3016 3017 HS_DTRACE_PROBE(hotspot, vm__init__begin); 3018 3019 // Record VM creation timing statistics 3020 TraceVmCreationTime create_vm_timer; 3021 create_vm_timer.start(); 3022 3023 // Timing (must come after argument parsing) 3024 TraceTime timer("Create VM", TraceStartupTime); 3025 3026 // Initialize the os module after parsing the args 3027 jint os_init_2_result = os::init_2(); 3028 if (os_init_2_result != JNI_OK) return os_init_2_result; 3029 3030 // Initialize output stream logging 3031 ostream_init_log(); 3032 3033 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad 3034 // Must be before create_vm_init_agents() 3035 if (Arguments::init_libraries_at_startup()) { 3036 convert_vm_init_libraries_to_agents(); 3037 } 3038 3039 // Launch -agentlib/-agentpath and converted -Xrun agents 3040 if (Arguments::init_agents_at_startup()) { 3041 create_vm_init_agents(); 3042 } 3043 3044 // Initialize Threads state 3045 _thread_list = NULL; 3046 _number_of_threads = 0; 3047 _number_of_non_daemon_threads = 0; 3048 3049 // Initialize TLS 3050 ThreadLocalStorage::init(); 3051 3052 // Initialize global data structures and create system classes in heap 3053 vm_init_globals(); 3054 3055 // Attach the main thread to this os thread 3056 JavaThread* main_thread = new JavaThread(); 3057 main_thread->set_thread_state(_thread_in_vm); 3058 // must do this before set_active_handles and initialize_thread_local_storage 3059 // Note: on solaris initialize_thread_local_storage() will (indirectly) 3060 // change the stack size recorded here to one based on the java thread 3061 // stacksize. This adjusted size is what is used to figure the placement 3062 // of the guard pages. 3063 main_thread->record_stack_base_and_size(); 3064 main_thread->initialize_thread_local_storage(); 3065 3066 main_thread->set_active_handles(JNIHandleBlock::allocate_block()); 3067 3068 if (!main_thread->set_as_starting_thread()) { 3069 vm_shutdown_during_initialization( 3070 "Failed necessary internal allocation. Out of swap space"); 3071 delete main_thread; 3072 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3073 return JNI_ENOMEM; 3074 } 3075 3076 // Enable guard page *after* os::create_main_thread(), otherwise it would 3077 // crash Linux VM, see notes in os_linux.cpp. 3078 main_thread->create_stack_guard_pages(); 3079 3080 // Initialize Java-Level synchronization subsystem 3081 ObjectMonitor::Initialize() ; 3082 3083 // Initialize global modules 3084 jint status = init_globals(); 3085 if (status != JNI_OK) { 3086 delete main_thread; 3087 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again 3088 return status; 3089 } 3090 3091 // Should be done after the heap is fully created 3092 main_thread->cache_global_variables(); 3093 3094 HandleMark hm; 3095 3096 { MutexLocker mu(Threads_lock); 3097 Threads::add(main_thread); 3098 } 3099 3100 // Any JVMTI raw monitors entered in onload will transition into 3101 // real raw monitor. VM is setup enough here for raw monitor enter. 3102 JvmtiExport::transition_pending_onload_raw_monitors(); 3103 3104 if (VerifyBeforeGC && 3105 Universe::heap()->total_collections() >= VerifyGCStartAt) { 3106 Universe::heap()->prepare_for_verify(); 3107 Universe::verify(); // make sure we're starting with a clean slate 3108 } 3109 3110 // Create the VMThread 3111 { TraceTime timer("Start VMThread", TraceStartupTime); 3112 VMThread::create(); 3113 Thread* vmthread = VMThread::vm_thread(); 3114 3115 if (!os::create_thread(vmthread, os::vm_thread)) 3116 vm_exit_during_initialization("Cannot create VM thread. Out of system resources."); 3117 3118 // Wait for the VM thread to become ready, and VMThread::run to initialize 3119 // Monitors can have spurious returns, must always check another state flag 3120 { 3121 MutexLocker ml(Notify_lock); 3122 os::start_thread(vmthread); 3123 while (vmthread->active_handles() == NULL) { 3124 Notify_lock->wait(); 3125 } 3126 } 3127 } 3128 3129 assert (Universe::is_fully_initialized(), "not initialized"); 3130 EXCEPTION_MARK; 3131 3132 // At this point, the Universe is initialized, but we have not executed 3133 // any byte code. Now is a good time (the only time) to dump out the 3134 // internal state of the JVM for sharing. 3135 3136 if (DumpSharedSpaces) { 3137 Universe::heap()->preload_and_dump(CHECK_0); 3138 ShouldNotReachHere(); 3139 } 3140 3141 // Always call even when there are not JVMTI environments yet, since environments 3142 // may be attached late and JVMTI must track phases of VM execution 3143 JvmtiExport::enter_start_phase(); 3144 3145 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. 3146 JvmtiExport::post_vm_start(); 3147 3148 { 3149 TraceTime timer("Initialize java.lang classes", TraceStartupTime); 3150 3151 if (EagerXrunInit && Arguments::init_libraries_at_startup()) { 3152 create_vm_init_libraries(); 3153 } 3154 3155 if (InitializeJavaLangString) { 3156 initialize_class(vmSymbols::java_lang_String(), CHECK_0); 3157 } else { 3158 warning("java.lang.String not initialized"); 3159 } 3160 3161 if (AggressiveOpts) { 3162 { 3163 // Forcibly initialize java/util/HashMap and mutate the private 3164 // static final "frontCacheEnabled" field before we start creating instances 3165#ifdef ASSERT 3166 klassOop tmp_k = SystemDictionary::find(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3167 assert(tmp_k == NULL, "java/util/HashMap should not be loaded yet"); 3168#endif 3169 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_util_HashMap(), Handle(), Handle(), CHECK_0); 3170 KlassHandle k = KlassHandle(THREAD, k_o); 3171 guarantee(k.not_null(), "Must find java/util/HashMap"); 3172 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3173 ik->initialize(CHECK_0); 3174 fieldDescriptor fd; 3175 // Possible we might not find this field; if so, don't break 3176 if (ik->find_local_field(vmSymbols::frontCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3177 k()->bool_field_put(fd.offset(), true); 3178 } 3179 } 3180 3181 if (UseStringCache) { 3182 // Forcibly initialize java/lang/StringValue and mutate the private 3183 // static final "stringCacheEnabled" field before we start creating instances 3184 klassOop k_o = SystemDictionary::resolve_or_null(vmSymbols::java_lang_StringValue(), Handle(), Handle(), CHECK_0); 3185 // Possible that StringValue isn't present: if so, silently don't break 3186 if (k_o != NULL) { 3187 KlassHandle k = KlassHandle(THREAD, k_o); 3188 instanceKlassHandle ik = instanceKlassHandle(THREAD, k()); 3189 ik->initialize(CHECK_0); 3190 fieldDescriptor fd; 3191 // Possible we might not find this field: if so, silently don't break 3192 if (ik->find_local_field(vmSymbols::stringCacheEnabled_name(), vmSymbols::bool_signature(), &fd)) { 3193 k()->bool_field_put(fd.offset(), true); 3194 } 3195 } 3196 } 3197 } 3198 3199 // Initialize java_lang.System (needed before creating the thread) 3200 if (InitializeJavaLangSystem) { 3201 initialize_class(vmSymbols::java_lang_System(), CHECK_0); 3202 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0); 3203 Handle thread_group = create_initial_thread_group(CHECK_0); 3204 Universe::set_main_thread_group(thread_group()); 3205 initialize_class(vmSymbols::java_lang_Thread(), CHECK_0); 3206 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0); 3207 main_thread->set_threadObj(thread_object); 3208 // Set thread status to running since main thread has 3209 // been started and running. 3210 java_lang_Thread::set_thread_status(thread_object, 3211 java_lang_Thread::RUNNABLE); 3212 3213 // The VM preresolve methods to these classes. Make sure that get initialized 3214 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0); 3215 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0); 3216 // The VM creates & returns objects of this class. Make sure it's initialized. 3217 initialize_class(vmSymbols::java_lang_Class(), CHECK_0); 3218 call_initializeSystemClass(CHECK_0); 3219 } else { 3220 warning("java.lang.System not initialized"); 3221 } 3222 3223 // an instance of OutOfMemory exception has been allocated earlier 3224 if (InitializeJavaLangExceptionsErrors) { 3225 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0); 3226 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0); 3227 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0); 3228 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0); 3229 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0); 3230 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0); 3231 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0); 3232 } else { 3233 warning("java.lang.OutOfMemoryError has not been initialized"); 3234 warning("java.lang.NullPointerException has not been initialized"); 3235 warning("java.lang.ClassCastException has not been initialized"); 3236 warning("java.lang.ArrayStoreException has not been initialized"); 3237 warning("java.lang.ArithmeticException has not been initialized"); 3238 warning("java.lang.StackOverflowError has not been initialized"); 3239 } 3240 } 3241 3242 // See : bugid 4211085. 3243 // Background : the static initializer of java.lang.Compiler tries to read 3244 // property"java.compiler" and read & write property "java.vm.info". 3245 // When a security manager is installed through the command line 3246 // option "-Djava.security.manager", the above properties are not 3247 // readable and the static initializer for java.lang.Compiler fails 3248 // resulting in a NoClassDefFoundError. This can happen in any 3249 // user code which calls methods in java.lang.Compiler. 3250 // Hack : the hack is to pre-load and initialize this class, so that only 3251 // system domains are on the stack when the properties are read. 3252 // Currently even the AWT code has calls to methods in java.lang.Compiler. 3253 // On the classic VM, java.lang.Compiler is loaded very early to load the JIT. 3254 // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and 3255 // read and write"java.vm.info" in the default policy file. See bugid 4211383 3256 // Once that is done, we should remove this hack. 3257 initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0); 3258 3259 // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to 3260 // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot 3261 // compiler does not get loaded through java.lang.Compiler). "java -version" with the 3262 // hotspot vm says "nojit" all the time which is confusing. So, we reset it here. 3263 // This should also be taken out as soon as 4211383 gets fixed. 3264 reset_vm_info_property(CHECK_0); 3265 3266 quicken_jni_functions(); 3267 3268 // Set flag that basic initialization has completed. Used by exceptions and various 3269 // debug stuff, that does not work until all basic classes have been initialized. 3270 set_init_completed(); 3271 3272 HS_DTRACE_PROBE(hotspot, vm__init__end); 3273 3274 // record VM initialization completion time 3275 Management::record_vm_init_completed(); 3276 3277 // Compute system loader. Note that this has to occur after set_init_completed, since 3278 // valid exceptions may be thrown in the process. 3279 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and 3280 // set_init_completed has just been called, causing exceptions not to be shortcut 3281 // anymore. We call vm_exit_during_initialization directly instead. 3282 SystemDictionary::compute_java_system_loader(THREAD); 3283 if (HAS_PENDING_EXCEPTION) { 3284 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3285 } 3286 3287#ifdef KERNEL 3288 if (JDK_Version::is_gte_jdk17x_version()) { 3289 set_jkernel_boot_classloader_hook(THREAD); 3290 } 3291#endif // KERNEL 3292 3293#ifndef SERIALGC 3294 // Support for ConcurrentMarkSweep. This should be cleaned up 3295 // and better encapsulated. The ugly nested if test would go away 3296 // once things are properly refactored. XXX YSR 3297 if (UseConcMarkSweepGC || UseG1GC) { 3298 if (UseConcMarkSweepGC) { 3299 ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD); 3300 } else { 3301 ConcurrentMarkThread::makeSurrogateLockerThread(THREAD); 3302 } 3303 if (HAS_PENDING_EXCEPTION) { 3304 vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); 3305 } 3306 } 3307#endif // SERIALGC 3308 3309 // Always call even when there are not JVMTI environments yet, since environments 3310 // may be attached late and JVMTI must track phases of VM execution 3311 JvmtiExport::enter_live_phase(); 3312 3313 // Signal Dispatcher needs to be started before VMInit event is posted 3314 os::signal_init(); 3315 3316 // Start Attach Listener if +StartAttachListener or it can't be started lazily 3317 if (!DisableAttachMechanism) { 3318 if (StartAttachListener || AttachListener::init_at_startup()) { 3319 AttachListener::init(); 3320 } 3321 } 3322 3323 // Launch -Xrun agents 3324 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP 3325 // back-end can launch with -Xdebug -Xrunjdwp. 3326 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { 3327 create_vm_init_libraries(); 3328 } 3329 3330 // Notify JVMTI agents that VM initialization is complete - nop if no agents. 3331 JvmtiExport::post_vm_initialized(); 3332 3333 Chunk::start_chunk_pool_cleaner_task(); 3334 3335 // initialize compiler(s) 3336 CompileBroker::compilation_init(); 3337 3338 Management::initialize(THREAD); 3339 if (HAS_PENDING_EXCEPTION) { 3340 // management agent fails to start possibly due to 3341 // configuration problem and is responsible for printing 3342 // stack trace if appropriate. Simply exit VM. 3343 vm_exit(1); 3344 } 3345 3346 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); 3347 if (Arguments::has_alloc_profile()) AllocationProfiler::engage(); 3348 if (MemProfiling) MemProfiler::engage(); 3349 StatSampler::engage(); 3350 if (CheckJNICalls) JniPeriodicChecker::engage(); 3351 3352 BiasedLocking::init(); 3353 3354 if (JDK_Version::current().post_vm_init_hook_enabled()) { 3355 call_postVMInitHook(THREAD); 3356 // The Java side of PostVMInitHook.run must deal with all 3357 // exceptions and provide means of diagnosis. 3358 if (HAS_PENDING_EXCEPTION) { 3359 CLEAR_PENDING_EXCEPTION; 3360 } 3361 } 3362 3363 // Start up the WatcherThread if there are any periodic tasks 3364 // NOTE: All PeriodicTasks should be registered by now. If they 3365 // aren't, late joiners might appear to start slowly (we might 3366 // take a while to process their first tick). 3367 if (PeriodicTask::num_tasks() > 0) { 3368 WatcherThread::start(); 3369 } 3370 3371 // Give os specific code one last chance to start 3372 os::init_3(); 3373 3374 create_vm_timer.end(); 3375 return JNI_OK; 3376} 3377 3378// type for the Agent_OnLoad and JVM_OnLoad entry points 3379extern "C" { 3380 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); 3381} 3382// Find a command line agent library and return its entry point for 3383// -agentlib: -agentpath: -Xrun 3384// num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. 3385static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) { 3386 OnLoadEntry_t on_load_entry = NULL; 3387 void *library = agent->os_lib(); // check if we have looked it up before 3388 3389 if (library == NULL) { 3390 char buffer[JVM_MAXPATHLEN]; 3391 char ebuf[1024]; 3392 const char *name = agent->name(); 3393 const char *msg = "Could not find agent library "; 3394 3395 if (agent->is_absolute_path()) { 3396 library = os::dll_load(name, ebuf, sizeof ebuf); 3397 if (library == NULL) { 3398 const char *sub_msg = " in absolute path, with error: "; 3399 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3400 char *buf = NEW_C_HEAP_ARRAY(char, len); 3401 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3402 // If we can't find the agent, exit. 3403 vm_exit_during_initialization(buf, NULL); 3404 FREE_C_HEAP_ARRAY(char, buf); 3405 } 3406 } else { 3407 // Try to load the agent from the standard dll directory 3408 os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name); 3409 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3410#ifdef KERNEL 3411 // Download instrument dll 3412 if (library == NULL && strcmp(name, "instrument") == 0) { 3413 char *props = Arguments::get_kernel_properties(); 3414 char *home = Arguments::get_java_home(); 3415 const char *fmt = "%s/bin/java %s -Dkernel.background.download=false" 3416 " sun.jkernel.DownloadManager -download client_jvm"; 3417 size_t length = strlen(props) + strlen(home) + strlen(fmt) + 1; 3418 char *cmd = NEW_C_HEAP_ARRAY(char, length); 3419 jio_snprintf(cmd, length, fmt, home, props); 3420 int status = os::fork_and_exec(cmd); 3421 FreeHeap(props); 3422 if (status == -1) { 3423 warning(cmd); 3424 vm_exit_during_initialization("fork_and_exec failed: %s", 3425 strerror(errno)); 3426 } 3427 FREE_C_HEAP_ARRAY(char, cmd); 3428 // when this comes back the instrument.dll should be where it belongs. 3429 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3430 } 3431#endif // KERNEL 3432 if (library == NULL) { // Try the local directory 3433 char ns[1] = {0}; 3434 os::dll_build_name(buffer, sizeof(buffer), ns, name); 3435 library = os::dll_load(buffer, ebuf, sizeof ebuf); 3436 if (library == NULL) { 3437 const char *sub_msg = " on the library path, with error: "; 3438 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; 3439 char *buf = NEW_C_HEAP_ARRAY(char, len); 3440 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); 3441 // If we can't find the agent, exit. 3442 vm_exit_during_initialization(buf, NULL); 3443 FREE_C_HEAP_ARRAY(char, buf); 3444 } 3445 } 3446 } 3447 agent->set_os_lib(library); 3448 } 3449 3450 // Find the OnLoad function. 3451 for (size_t symbol_index = 0; symbol_index < num_symbol_entries; symbol_index++) { 3452 on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::dll_lookup(library, on_load_symbols[symbol_index])); 3453 if (on_load_entry != NULL) break; 3454 } 3455 return on_load_entry; 3456} 3457 3458// Find the JVM_OnLoad entry point 3459static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { 3460 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; 3461 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3462} 3463 3464// Find the Agent_OnLoad entry point 3465static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { 3466 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; 3467 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); 3468} 3469 3470// For backwards compatibility with -Xrun 3471// Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be 3472// treated like -agentpath: 3473// Must be called before agent libraries are created 3474void Threads::convert_vm_init_libraries_to_agents() { 3475 AgentLibrary* agent; 3476 AgentLibrary* next; 3477 3478 for (agent = Arguments::libraries(); agent != NULL; agent = next) { 3479 next = agent->next(); // cache the next agent now as this agent may get moved off this list 3480 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3481 3482 // If there is an JVM_OnLoad function it will get called later, 3483 // otherwise see if there is an Agent_OnLoad 3484 if (on_load_entry == NULL) { 3485 on_load_entry = lookup_agent_on_load(agent); 3486 if (on_load_entry != NULL) { 3487 // switch it to the agent list -- so that Agent_OnLoad will be called, 3488 // JVM_OnLoad won't be attempted and Agent_OnUnload will 3489 Arguments::convert_library_to_agent(agent); 3490 } else { 3491 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); 3492 } 3493 } 3494 } 3495} 3496 3497// Create agents for -agentlib: -agentpath: and converted -Xrun 3498// Invokes Agent_OnLoad 3499// Called very early -- before JavaThreads exist 3500void Threads::create_vm_init_agents() { 3501 extern struct JavaVM_ main_vm; 3502 AgentLibrary* agent; 3503 3504 JvmtiExport::enter_onload_phase(); 3505 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3506 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); 3507 3508 if (on_load_entry != NULL) { 3509 // Invoke the Agent_OnLoad function 3510 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3511 if (err != JNI_OK) { 3512 vm_exit_during_initialization("agent library failed to init", agent->name()); 3513 } 3514 } else { 3515 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); 3516 } 3517 } 3518 JvmtiExport::enter_primordial_phase(); 3519} 3520 3521extern "C" { 3522 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); 3523} 3524 3525void Threads::shutdown_vm_agents() { 3526 // Send any Agent_OnUnload notifications 3527 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; 3528 extern struct JavaVM_ main_vm; 3529 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { 3530 3531 // Find the Agent_OnUnload function. 3532 for (uint symbol_index = 0; symbol_index < ARRAY_SIZE(on_unload_symbols); symbol_index++) { 3533 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, 3534 os::dll_lookup(agent->os_lib(), on_unload_symbols[symbol_index])); 3535 3536 // Invoke the Agent_OnUnload function 3537 if (unload_entry != NULL) { 3538 JavaThread* thread = JavaThread::current(); 3539 ThreadToNativeFromVM ttn(thread); 3540 HandleMark hm(thread); 3541 (*unload_entry)(&main_vm); 3542 break; 3543 } 3544 } 3545 } 3546} 3547 3548// Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries 3549// Invokes JVM_OnLoad 3550void Threads::create_vm_init_libraries() { 3551 extern struct JavaVM_ main_vm; 3552 AgentLibrary* agent; 3553 3554 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { 3555 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); 3556 3557 if (on_load_entry != NULL) { 3558 // Invoke the JVM_OnLoad function 3559 JavaThread* thread = JavaThread::current(); 3560 ThreadToNativeFromVM ttn(thread); 3561 HandleMark hm(thread); 3562 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); 3563 if (err != JNI_OK) { 3564 vm_exit_during_initialization("-Xrun library failed to init", agent->name()); 3565 } 3566 } else { 3567 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); 3568 } 3569 } 3570} 3571 3572// Last thread running calls java.lang.Shutdown.shutdown() 3573void JavaThread::invoke_shutdown_hooks() { 3574 HandleMark hm(this); 3575 3576 // We could get here with a pending exception, if so clear it now. 3577 if (this->has_pending_exception()) { 3578 this->clear_pending_exception(); 3579 } 3580 3581 EXCEPTION_MARK; 3582 klassOop k = 3583 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), 3584 THREAD); 3585 if (k != NULL) { 3586 // SystemDictionary::resolve_or_null will return null if there was 3587 // an exception. If we cannot load the Shutdown class, just don't 3588 // call Shutdown.shutdown() at all. This will mean the shutdown hooks 3589 // and finalizers (if runFinalizersOnExit is set) won't be run. 3590 // Note that if a shutdown hook was registered or runFinalizersOnExit 3591 // was called, the Shutdown class would have already been loaded 3592 // (Runtime.addShutdownHook and runFinalizersOnExit will load it). 3593 instanceKlassHandle shutdown_klass (THREAD, k); 3594 JavaValue result(T_VOID); 3595 JavaCalls::call_static(&result, 3596 shutdown_klass, 3597 vmSymbols::shutdown_method_name(), 3598 vmSymbols::void_method_signature(), 3599 THREAD); 3600 } 3601 CLEAR_PENDING_EXCEPTION; 3602} 3603 3604// Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when 3605// the program falls off the end of main(). Another VM exit path is through 3606// vm_exit() when the program calls System.exit() to return a value or when 3607// there is a serious error in VM. The two shutdown paths are not exactly 3608// the same, but they share Shutdown.shutdown() at Java level and before_exit() 3609// and VM_Exit op at VM level. 3610// 3611// Shutdown sequence: 3612// + Wait until we are the last non-daemon thread to execute 3613// <-- every thing is still working at this moment --> 3614// + Call java.lang.Shutdown.shutdown(), which will invoke Java level 3615// shutdown hooks, run finalizers if finalization-on-exit 3616// + Call before_exit(), prepare for VM exit 3617// > run VM level shutdown hooks (they are registered through JVM_OnExit(), 3618// currently the only user of this mechanism is File.deleteOnExit()) 3619// > stop flat profiler, StatSampler, watcher thread, CMS threads, 3620// post thread end and vm death events to JVMTI, 3621// stop signal thread 3622// + Call JavaThread::exit(), it will: 3623// > release JNI handle blocks, remove stack guard pages 3624// > remove this thread from Threads list 3625// <-- no more Java code from this thread after this point --> 3626// + Stop VM thread, it will bring the remaining VM to a safepoint and stop 3627// the compiler threads at safepoint 3628// <-- do not use anything that could get blocked by Safepoint --> 3629// + Disable tracing at JNI/JVM barriers 3630// + Set _vm_exited flag for threads that are still running native code 3631// + Delete this thread 3632// + Call exit_globals() 3633// > deletes tty 3634// > deletes PerfMemory resources 3635// + Return to caller 3636 3637bool Threads::destroy_vm() { 3638 JavaThread* thread = JavaThread::current(); 3639 3640 // Wait until we are the last non-daemon thread to execute 3641 { MutexLocker nu(Threads_lock); 3642 while (Threads::number_of_non_daemon_threads() > 1 ) 3643 // This wait should make safepoint checks, wait without a timeout, 3644 // and wait as a suspend-equivalent condition. 3645 // 3646 // Note: If the FlatProfiler is running and this thread is waiting 3647 // for another non-daemon thread to finish, then the FlatProfiler 3648 // is waiting for the external suspend request on this thread to 3649 // complete. wait_for_ext_suspend_completion() will eventually 3650 // timeout, but that takes time. Making this wait a suspend- 3651 // equivalent condition solves that timeout problem. 3652 // 3653 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, 3654 Mutex::_as_suspend_equivalent_flag); 3655 } 3656 3657 // Hang forever on exit if we are reporting an error. 3658 if (ShowMessageBoxOnError && is_error_reported()) { 3659 os::infinite_sleep(); 3660 } 3661 3662 if (JDK_Version::is_jdk12x_version()) { 3663 // We are the last thread running, so check if finalizers should be run. 3664 // For 1.3 or later this is done in thread->invoke_shutdown_hooks() 3665 HandleMark rm(thread); 3666 Universe::run_finalizers_on_exit(); 3667 } else { 3668 // run Java level shutdown hooks 3669 thread->invoke_shutdown_hooks(); 3670 } 3671 3672 before_exit(thread); 3673 3674 thread->exit(true); 3675 3676 // Stop VM thread. 3677 { 3678 // 4945125 The vm thread comes to a safepoint during exit. 3679 // GC vm_operations can get caught at the safepoint, and the 3680 // heap is unparseable if they are caught. Grab the Heap_lock 3681 // to prevent this. The GC vm_operations will not be able to 3682 // queue until after the vm thread is dead. 3683 MutexLocker ml(Heap_lock); 3684 3685 VMThread::wait_for_vm_thread_exit(); 3686 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); 3687 VMThread::destroy(); 3688 } 3689 3690 // clean up ideal graph printers 3691#if defined(COMPILER2) && !defined(PRODUCT) 3692 IdealGraphPrinter::clean_up(); 3693#endif 3694 3695 // Now, all Java threads are gone except daemon threads. Daemon threads 3696 // running Java code or in VM are stopped by the Safepoint. However, 3697 // daemon threads executing native code are still running. But they 3698 // will be stopped at native=>Java/VM barriers. Note that we can't 3699 // simply kill or suspend them, as it is inherently deadlock-prone. 3700 3701#ifndef PRODUCT 3702 // disable function tracing at JNI/JVM barriers 3703 TraceJNICalls = false; 3704 TraceJVMCalls = false; 3705 TraceRuntimeCalls = false; 3706#endif 3707 3708 VM_Exit::set_vm_exited(); 3709 3710 notify_vm_shutdown(); 3711 3712 delete thread; 3713 3714 // exit_globals() will delete tty 3715 exit_globals(); 3716 3717 return true; 3718} 3719 3720 3721jboolean Threads::is_supported_jni_version_including_1_1(jint version) { 3722 if (version == JNI_VERSION_1_1) return JNI_TRUE; 3723 return is_supported_jni_version(version); 3724} 3725 3726 3727jboolean Threads::is_supported_jni_version(jint version) { 3728 if (version == JNI_VERSION_1_2) return JNI_TRUE; 3729 if (version == JNI_VERSION_1_4) return JNI_TRUE; 3730 if (version == JNI_VERSION_1_6) return JNI_TRUE; 3731 return JNI_FALSE; 3732} 3733 3734 3735void Threads::add(JavaThread* p, bool force_daemon) { 3736 // The threads lock must be owned at this point 3737 assert_locked_or_safepoint(Threads_lock); 3738 3739 // See the comment for this method in thread.hpp for its purpose and 3740 // why it is called here. 3741 p->initialize_queues(); 3742 p->set_next(_thread_list); 3743 _thread_list = p; 3744 _number_of_threads++; 3745 oop threadObj = p->threadObj(); 3746 bool daemon = true; 3747 // Bootstrapping problem: threadObj can be null for initial 3748 // JavaThread (or for threads attached via JNI) 3749 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { 3750 _number_of_non_daemon_threads++; 3751 daemon = false; 3752 } 3753 3754 ThreadService::add_thread(p, daemon); 3755 3756 // Possible GC point. 3757 Events::log("Thread added: " INTPTR_FORMAT, p); 3758} 3759 3760void Threads::remove(JavaThread* p) { 3761 // Extra scope needed for Thread_lock, so we can check 3762 // that we do not remove thread without safepoint code notice 3763 { MutexLocker ml(Threads_lock); 3764 3765 assert(includes(p), "p must be present"); 3766 3767 JavaThread* current = _thread_list; 3768 JavaThread* prev = NULL; 3769 3770 while (current != p) { 3771 prev = current; 3772 current = current->next(); 3773 } 3774 3775 if (prev) { 3776 prev->set_next(current->next()); 3777 } else { 3778 _thread_list = p->next(); 3779 } 3780 _number_of_threads--; 3781 oop threadObj = p->threadObj(); 3782 bool daemon = true; 3783 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { 3784 _number_of_non_daemon_threads--; 3785 daemon = false; 3786 3787 // Only one thread left, do a notify on the Threads_lock so a thread waiting 3788 // on destroy_vm will wake up. 3789 if (number_of_non_daemon_threads() == 1) 3790 Threads_lock->notify_all(); 3791 } 3792 ThreadService::remove_thread(p, daemon); 3793 3794 // Make sure that safepoint code disregard this thread. This is needed since 3795 // the thread might mess around with locks after this point. This can cause it 3796 // to do callbacks into the safepoint code. However, the safepoint code is not aware 3797 // of this thread since it is removed from the queue. 3798 p->set_terminated_value(); 3799 } // unlock Threads_lock 3800 3801 // Since Events::log uses a lock, we grab it outside the Threads_lock 3802 Events::log("Thread exited: " INTPTR_FORMAT, p); 3803} 3804 3805// Threads_lock must be held when this is called (or must be called during a safepoint) 3806bool Threads::includes(JavaThread* p) { 3807 assert(Threads_lock->is_locked(), "sanity check"); 3808 ALL_JAVA_THREADS(q) { 3809 if (q == p ) { 3810 return true; 3811 } 3812 } 3813 return false; 3814} 3815 3816// Operations on the Threads list for GC. These are not explicitly locked, 3817// but the garbage collector must provide a safe context for them to run. 3818// In particular, these things should never be called when the Threads_lock 3819// is held by some other thread. (Note: the Safepoint abstraction also 3820// uses the Threads_lock to gurantee this property. It also makes sure that 3821// all threads gets blocked when exiting or starting). 3822 3823void Threads::oops_do(OopClosure* f, CodeBlobClosure* cf) { 3824 ALL_JAVA_THREADS(p) { 3825 p->oops_do(f, cf); 3826 } 3827 VMThread::vm_thread()->oops_do(f, cf); 3828} 3829 3830void Threads::possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf) { 3831 // Introduce a mechanism allowing parallel threads to claim threads as 3832 // root groups. Overhead should be small enough to use all the time, 3833 // even in sequential code. 3834 SharedHeap* sh = SharedHeap::heap(); 3835 bool is_par = (sh->n_par_threads() > 0); 3836 int cp = SharedHeap::heap()->strong_roots_parity(); 3837 ALL_JAVA_THREADS(p) { 3838 if (p->claim_oops_do(is_par, cp)) { 3839 p->oops_do(f, cf); 3840 } 3841 } 3842 VMThread* vmt = VMThread::vm_thread(); 3843 if (vmt->claim_oops_do(is_par, cp)) 3844 vmt->oops_do(f, cf); 3845} 3846 3847#ifndef SERIALGC 3848// Used by ParallelScavenge 3849void Threads::create_thread_roots_tasks(GCTaskQueue* q) { 3850 ALL_JAVA_THREADS(p) { 3851 q->enqueue(new ThreadRootsTask(p)); 3852 } 3853 q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); 3854} 3855 3856// Used by Parallel Old 3857void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { 3858 ALL_JAVA_THREADS(p) { 3859 q->enqueue(new ThreadRootsMarkingTask(p)); 3860 } 3861 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); 3862} 3863#endif // SERIALGC 3864 3865void Threads::nmethods_do(CodeBlobClosure* cf) { 3866 ALL_JAVA_THREADS(p) { 3867 p->nmethods_do(cf); 3868 } 3869 VMThread::vm_thread()->nmethods_do(cf); 3870} 3871 3872void Threads::gc_epilogue() { 3873 ALL_JAVA_THREADS(p) { 3874 p->gc_epilogue(); 3875 } 3876} 3877 3878void Threads::gc_prologue() { 3879 ALL_JAVA_THREADS(p) { 3880 p->gc_prologue(); 3881 } 3882} 3883 3884void Threads::deoptimized_wrt_marked_nmethods() { 3885 ALL_JAVA_THREADS(p) { 3886 p->deoptimized_wrt_marked_nmethods(); 3887 } 3888} 3889 3890 3891// Get count Java threads that are waiting to enter the specified monitor. 3892GrowableArray<JavaThread*>* Threads::get_pending_threads(int count, 3893 address monitor, bool doLock) { 3894 assert(doLock || SafepointSynchronize::is_at_safepoint(), 3895 "must grab Threads_lock or be at safepoint"); 3896 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count); 3897 3898 int i = 0; 3899 { 3900 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3901 ALL_JAVA_THREADS(p) { 3902 if (p->is_Compiler_thread()) continue; 3903 3904 address pending = (address)p->current_pending_monitor(); 3905 if (pending == monitor) { // found a match 3906 if (i < count) result->append(p); // save the first count matches 3907 i++; 3908 } 3909 } 3910 } 3911 return result; 3912} 3913 3914 3915JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) { 3916 assert(doLock || 3917 Threads_lock->owned_by_self() || 3918 SafepointSynchronize::is_at_safepoint(), 3919 "must grab Threads_lock or be at safepoint"); 3920 3921 // NULL owner means not locked so we can skip the search 3922 if (owner == NULL) return NULL; 3923 3924 { 3925 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3926 ALL_JAVA_THREADS(p) { 3927 // first, see if owner is the address of a Java thread 3928 if (owner == (address)p) return p; 3929 } 3930 } 3931 assert(UseHeavyMonitors == false, "Did not find owning Java thread with UseHeavyMonitors enabled"); 3932 if (UseHeavyMonitors) return NULL; 3933 3934 // 3935 // If we didn't find a matching Java thread and we didn't force use of 3936 // heavyweight monitors, then the owner is the stack address of the 3937 // Lock Word in the owning Java thread's stack. 3938 // 3939 JavaThread* the_owner = NULL; 3940 { 3941 MutexLockerEx ml(doLock ? Threads_lock : NULL); 3942 ALL_JAVA_THREADS(q) { 3943 if (q->is_lock_owned(owner)) { 3944 the_owner = q; 3945 break; 3946 } 3947 } 3948 } 3949 assert(the_owner != NULL, "Did not find owning Java thread for lock word address"); 3950 return the_owner; 3951} 3952 3953// Threads::print_on() is called at safepoint by VM_PrintThreads operation. 3954void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) { 3955 char buf[32]; 3956 st->print_cr(os::local_time_string(buf, sizeof(buf))); 3957 3958 st->print_cr("Full thread dump %s (%s %s):", 3959 Abstract_VM_Version::vm_name(), 3960 Abstract_VM_Version::vm_release(), 3961 Abstract_VM_Version::vm_info_string() 3962 ); 3963 st->cr(); 3964 3965#ifndef SERIALGC 3966 // Dump concurrent locks 3967 ConcurrentLocksDump concurrent_locks; 3968 if (print_concurrent_locks) { 3969 concurrent_locks.dump_at_safepoint(); 3970 } 3971#endif // SERIALGC 3972 3973 ALL_JAVA_THREADS(p) { 3974 ResourceMark rm; 3975 p->print_on(st); 3976 if (print_stacks) { 3977 if (internal_format) { 3978 p->trace_stack(); 3979 } else { 3980 p->print_stack_on(st); 3981 } 3982 } 3983 st->cr(); 3984#ifndef SERIALGC 3985 if (print_concurrent_locks) { 3986 concurrent_locks.print_locks_on(p, st); 3987 } 3988#endif // SERIALGC 3989 } 3990 3991 VMThread::vm_thread()->print_on(st); 3992 st->cr(); 3993 Universe::heap()->print_gc_threads_on(st); 3994 WatcherThread* wt = WatcherThread::watcher_thread(); 3995 if (wt != NULL) wt->print_on(st); 3996 st->cr(); 3997 CompileBroker::print_compiler_threads_on(st); 3998 st->flush(); 3999} 4000 4001// Threads::print_on_error() is called by fatal error handler. It's possible 4002// that VM is not at safepoint and/or current thread is inside signal handler. 4003// Don't print stack trace, as the stack may not be walkable. Don't allocate 4004// memory (even in resource area), it might deadlock the error handler. 4005void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { 4006 bool found_current = false; 4007 st->print_cr("Java Threads: ( => current thread )"); 4008 ALL_JAVA_THREADS(thread) { 4009 bool is_current = (current == thread); 4010 found_current = found_current || is_current; 4011 4012 st->print("%s", is_current ? "=>" : " "); 4013 4014 st->print(PTR_FORMAT, thread); 4015 st->print(" "); 4016 thread->print_on_error(st, buf, buflen); 4017 st->cr(); 4018 } 4019 st->cr(); 4020 4021 st->print_cr("Other Threads:"); 4022 if (VMThread::vm_thread()) { 4023 bool is_current = (current == VMThread::vm_thread()); 4024 found_current = found_current || is_current; 4025 st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); 4026 4027 st->print(PTR_FORMAT, VMThread::vm_thread()); 4028 st->print(" "); 4029 VMThread::vm_thread()->print_on_error(st, buf, buflen); 4030 st->cr(); 4031 } 4032 WatcherThread* wt = WatcherThread::watcher_thread(); 4033 if (wt != NULL) { 4034 bool is_current = (current == wt); 4035 found_current = found_current || is_current; 4036 st->print("%s", is_current ? "=>" : " "); 4037 4038 st->print(PTR_FORMAT, wt); 4039 st->print(" "); 4040 wt->print_on_error(st, buf, buflen); 4041 st->cr(); 4042 } 4043 if (!found_current) { 4044 st->cr(); 4045 st->print("=>" PTR_FORMAT " (exited) ", current); 4046 current->print_on_error(st, buf, buflen); 4047 st->cr(); 4048 } 4049} 4050 4051// Internal SpinLock and Mutex 4052// Based on ParkEvent 4053 4054// Ad-hoc mutual exclusion primitives: SpinLock and Mux 4055// 4056// We employ SpinLocks _only for low-contention, fixed-length 4057// short-duration critical sections where we're concerned 4058// about native mutex_t or HotSpot Mutex:: latency. 4059// The mux construct provides a spin-then-block mutual exclusion 4060// mechanism. 4061// 4062// Testing has shown that contention on the ListLock guarding gFreeList 4063// is common. If we implement ListLock as a simple SpinLock it's common 4064// for the JVM to devolve to yielding with little progress. This is true 4065// despite the fact that the critical sections protected by ListLock are 4066// extremely short. 4067// 4068// TODO-FIXME: ListLock should be of type SpinLock. 4069// We should make this a 1st-class type, integrated into the lock 4070// hierarchy as leaf-locks. Critically, the SpinLock structure 4071// should have sufficient padding to avoid false-sharing and excessive 4072// cache-coherency traffic. 4073 4074 4075typedef volatile int SpinLockT ; 4076 4077void Thread::SpinAcquire (volatile int * adr, const char * LockName) { 4078 if (Atomic::cmpxchg (1, adr, 0) == 0) { 4079 return ; // normal fast-path return 4080 } 4081 4082 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. 4083 TEVENT (SpinAcquire - ctx) ; 4084 int ctr = 0 ; 4085 int Yields = 0 ; 4086 for (;;) { 4087 while (*adr != 0) { 4088 ++ctr ; 4089 if ((ctr & 0xFFF) == 0 || !os::is_MP()) { 4090 if (Yields > 5) { 4091 // Consider using a simple NakedSleep() instead. 4092 // Then SpinAcquire could be called by non-JVM threads 4093 Thread::current()->_ParkEvent->park(1) ; 4094 } else { 4095 os::NakedYield() ; 4096 ++Yields ; 4097 } 4098 } else { 4099 SpinPause() ; 4100 } 4101 } 4102 if (Atomic::cmpxchg (1, adr, 0) == 0) return ; 4103 } 4104} 4105 4106void Thread::SpinRelease (volatile int * adr) { 4107 assert (*adr != 0, "invariant") ; 4108 OrderAccess::fence() ; // guarantee at least release consistency. 4109 // Roach-motel semantics. 4110 // It's safe if subsequent LDs and STs float "up" into the critical section, 4111 // but prior LDs and STs within the critical section can't be allowed 4112 // to reorder or float past the ST that releases the lock. 4113 *adr = 0 ; 4114} 4115 4116// muxAcquire and muxRelease: 4117// 4118// * muxAcquire and muxRelease support a single-word lock-word construct. 4119// The LSB of the word is set IFF the lock is held. 4120// The remainder of the word points to the head of a singly-linked list 4121// of threads blocked on the lock. 4122// 4123// * The current implementation of muxAcquire-muxRelease uses its own 4124// dedicated Thread._MuxEvent instance. If we're interested in 4125// minimizing the peak number of extant ParkEvent instances then 4126// we could eliminate _MuxEvent and "borrow" _ParkEvent as long 4127// as certain invariants were satisfied. Specifically, care would need 4128// to be taken with regards to consuming unpark() "permits". 4129// A safe rule of thumb is that a thread would never call muxAcquire() 4130// if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently 4131// park(). Otherwise the _ParkEvent park() operation in muxAcquire() could 4132// consume an unpark() permit intended for monitorenter, for instance. 4133// One way around this would be to widen the restricted-range semaphore 4134// implemented in park(). Another alternative would be to provide 4135// multiple instances of the PlatformEvent() for each thread. One 4136// instance would be dedicated to muxAcquire-muxRelease, for instance. 4137// 4138// * Usage: 4139// -- Only as leaf locks 4140// -- for short-term locking only as muxAcquire does not perform 4141// thread state transitions. 4142// 4143// Alternatives: 4144// * We could implement muxAcquire and muxRelease with MCS or CLH locks 4145// but with parking or spin-then-park instead of pure spinning. 4146// * Use Taura-Oyama-Yonenzawa locks. 4147// * It's possible to construct a 1-0 lock if we encode the lockword as 4148// (List,LockByte). Acquire will CAS the full lockword while Release 4149// will STB 0 into the LockByte. The 1-0 scheme admits stranding, so 4150// acquiring threads use timers (ParkTimed) to detect and recover from 4151// the stranding window. Thread/Node structures must be aligned on 256-byte 4152// boundaries by using placement-new. 4153// * Augment MCS with advisory back-link fields maintained with CAS(). 4154// Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. 4155// The validity of the backlinks must be ratified before we trust the value. 4156// If the backlinks are invalid the exiting thread must back-track through the 4157// the forward links, which are always trustworthy. 4158// * Add a successor indication. The LockWord is currently encoded as 4159// (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable 4160// to provide the usual futile-wakeup optimization. 4161// See RTStt for details. 4162// * Consider schedctl.sc_nopreempt to cover the critical section. 4163// 4164 4165 4166typedef volatile intptr_t MutexT ; // Mux Lock-word 4167enum MuxBits { LOCKBIT = 1 } ; 4168 4169void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) { 4170 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4171 if (w == 0) return ; 4172 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4173 return ; 4174 } 4175 4176 TEVENT (muxAcquire - Contention) ; 4177 ParkEvent * const Self = Thread::current()->_MuxEvent ; 4178 assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ; 4179 for (;;) { 4180 int its = (os::is_MP() ? 100 : 0) + 1 ; 4181 4182 // Optional spin phase: spin-then-park strategy 4183 while (--its >= 0) { 4184 w = *Lock ; 4185 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4186 return ; 4187 } 4188 } 4189 4190 Self->reset() ; 4191 Self->OnList = intptr_t(Lock) ; 4192 // The following fence() isn't _strictly necessary as the subsequent 4193 // CAS() both serializes execution and ratifies the fetched *Lock value. 4194 OrderAccess::fence(); 4195 for (;;) { 4196 w = *Lock ; 4197 if ((w & LOCKBIT) == 0) { 4198 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4199 Self->OnList = 0 ; // hygiene - allows stronger asserts 4200 return ; 4201 } 4202 continue ; // Interference -- *Lock changed -- Just retry 4203 } 4204 assert (w & LOCKBIT, "invariant") ; 4205 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4206 if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ; 4207 } 4208 4209 while (Self->OnList != 0) { 4210 Self->park() ; 4211 } 4212 } 4213} 4214 4215void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) { 4216 intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; 4217 if (w == 0) return ; 4218 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4219 return ; 4220 } 4221 4222 TEVENT (muxAcquire - Contention) ; 4223 ParkEvent * ReleaseAfter = NULL ; 4224 if (ev == NULL) { 4225 ev = ReleaseAfter = ParkEvent::Allocate (NULL) ; 4226 } 4227 assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ; 4228 for (;;) { 4229 guarantee (ev->OnList == 0, "invariant") ; 4230 int its = (os::is_MP() ? 100 : 0) + 1 ; 4231 4232 // Optional spin phase: spin-then-park strategy 4233 while (--its >= 0) { 4234 w = *Lock ; 4235 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4236 if (ReleaseAfter != NULL) { 4237 ParkEvent::Release (ReleaseAfter) ; 4238 } 4239 return ; 4240 } 4241 } 4242 4243 ev->reset() ; 4244 ev->OnList = intptr_t(Lock) ; 4245 // The following fence() isn't _strictly necessary as the subsequent 4246 // CAS() both serializes execution and ratifies the fetched *Lock value. 4247 OrderAccess::fence(); 4248 for (;;) { 4249 w = *Lock ; 4250 if ((w & LOCKBIT) == 0) { 4251 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { 4252 ev->OnList = 0 ; 4253 // We call ::Release while holding the outer lock, thus 4254 // artificially lengthening the critical section. 4255 // Consider deferring the ::Release() until the subsequent unlock(), 4256 // after we've dropped the outer lock. 4257 if (ReleaseAfter != NULL) { 4258 ParkEvent::Release (ReleaseAfter) ; 4259 } 4260 return ; 4261 } 4262 continue ; // Interference -- *Lock changed -- Just retry 4263 } 4264 assert (w & LOCKBIT, "invariant") ; 4265 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT ); 4266 if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ; 4267 } 4268 4269 while (ev->OnList != 0) { 4270 ev->park() ; 4271 } 4272 } 4273} 4274 4275// Release() must extract a successor from the list and then wake that thread. 4276// It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme 4277// similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based 4278// Release() would : 4279// (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. 4280// (B) Extract a successor from the private list "in-hand" 4281// (C) attempt to CAS() the residual back into *Lock over null. 4282// If there were any newly arrived threads and the CAS() would fail. 4283// In that case Release() would detach the RATs, re-merge the list in-hand 4284// with the RATs and repeat as needed. Alternately, Release() might 4285// detach and extract a successor, but then pass the residual list to the wakee. 4286// The wakee would be responsible for reattaching and remerging before it 4287// competed for the lock. 4288// 4289// Both "pop" and DMR are immune from ABA corruption -- there can be 4290// multiple concurrent pushers, but only one popper or detacher. 4291// This implementation pops from the head of the list. This is unfair, 4292// but tends to provide excellent throughput as hot threads remain hot. 4293// (We wake recently run threads first). 4294 4295void Thread::muxRelease (volatile intptr_t * Lock) { 4296 for (;;) { 4297 const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ; 4298 assert (w & LOCKBIT, "invariant") ; 4299 if (w == LOCKBIT) return ; 4300 ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ; 4301 assert (List != NULL, "invariant") ; 4302 assert (List->OnList == intptr_t(Lock), "invariant") ; 4303 ParkEvent * nxt = List->ListNext ; 4304 4305 // The following CAS() releases the lock and pops the head element. 4306 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { 4307 continue ; 4308 } 4309 List->OnList = 0 ; 4310 OrderAccess::fence() ; 4311 List->unpark () ; 4312 return ; 4313 } 4314} 4315 4316 4317void Threads::verify() { 4318 ALL_JAVA_THREADS(p) { 4319 p->verify(); 4320 } 4321 VMThread* thread = VMThread::vm_thread(); 4322 if (thread != NULL) thread->verify(); 4323} 4324