| /* |
| * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "classfile/stringTable.hpp" |
| #include "classfile/symbolTable.hpp" |
| #include "classfile/systemDictionary.hpp" |
| #include "code/codeCache.hpp" |
| #include "code/icBuffer.hpp" |
| #include "code/nmethod.hpp" |
| #include "code/pcDesc.hpp" |
| #include "code/scopeDesc.hpp" |
| #include "gc/shared/collectedHeap.hpp" |
| #include "gc/shared/gcLocker.inline.hpp" |
| #include "gc/shared/strongRootsScope.hpp" |
| #include "gc/shared/workgroup.hpp" |
| #include "interpreter/interpreter.hpp" |
| #include "logging/log.hpp" |
| #include "logging/logStream.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "memory/universe.inline.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "oops/symbol.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/compilationPolicy.hpp" |
| #include "runtime/deoptimization.hpp" |
| #include "runtime/frame.inline.hpp" |
| #include "runtime/interfaceSupport.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "runtime/orderAccess.inline.hpp" |
| #include "runtime/osThread.hpp" |
| #include "runtime/safepoint.hpp" |
| #include "runtime/signature.hpp" |
| #include "runtime/stubCodeGenerator.hpp" |
| #include "runtime/stubRoutines.hpp" |
| #include "runtime/sweeper.hpp" |
| #include "runtime/synchronizer.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "runtime/timerTrace.hpp" |
| #include "services/runtimeService.hpp" |
| #include "trace/tracing.hpp" |
| #include "trace/traceMacros.hpp" |
| #include "utilities/events.hpp" |
| #include "utilities/macros.hpp" |
| #if INCLUDE_ALL_GCS |
| #include "gc/cms/concurrentMarkSweepThread.hpp" |
| #include "gc/g1/suspendibleThreadSet.hpp" |
| #endif // INCLUDE_ALL_GCS |
| #ifdef COMPILER1 |
| #include "c1/c1_globals.hpp" |
| #endif |
| |
| // -------------------------------------------------------------------------------------------------- |
| // Implementation of Safepoint begin/end |
| |
| SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized; |
| volatile int SafepointSynchronize::_waiting_to_block = 0; |
| volatile int SafepointSynchronize::_safepoint_counter = 0; |
| int SafepointSynchronize::_current_jni_active_count = 0; |
| long SafepointSynchronize::_end_of_last_safepoint = 0; |
| static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE |
| static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only |
| static bool timeout_error_printed = false; |
| |
| // Roll all threads forward to a safepoint and suspend them all |
| void SafepointSynchronize::begin() { |
| EventSafepointBegin begin_event; |
| Thread* myThread = Thread::current(); |
| assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint"); |
| |
| if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
| _safepoint_begin_time = os::javaTimeNanos(); |
| _ts_of_current_safepoint = tty->time_stamp().seconds(); |
| } |
| |
| #if INCLUDE_ALL_GCS |
| if (UseConcMarkSweepGC) { |
| // In the future we should investigate whether CMS can use the |
| // more-general mechanism below. DLD (01/05). |
| ConcurrentMarkSweepThread::synchronize(false); |
| } else if (UseG1GC) { |
| SuspendibleThreadSet::synchronize(); |
| } |
| #endif // INCLUDE_ALL_GCS |
| |
| // By getting the Threads_lock, we assure that no threads are about to start or |
| // exit. It is released again in SafepointSynchronize::end(). |
| Threads_lock->lock(); |
| |
| assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state"); |
| |
| int nof_threads = Threads::number_of_threads(); |
| |
| log_debug(safepoint)("Safepoint synchronization initiated. (%d)", nof_threads); |
| |
| RuntimeService::record_safepoint_begin(); |
| |
| MutexLocker mu(Safepoint_lock); |
| |
| // Reset the count of active JNI critical threads |
| _current_jni_active_count = 0; |
| |
| // Set number of threads to wait for, before we initiate the callbacks |
| _waiting_to_block = nof_threads; |
| TryingToBlock = 0 ; |
| int still_running = nof_threads; |
| |
| // Save the starting time, so that it can be compared to see if this has taken |
| // too long to complete. |
| jlong safepoint_limit_time = 0; |
| timeout_error_printed = false; |
| |
| // PrintSafepointStatisticsTimeout can be specified separately. When |
| // specified, PrintSafepointStatistics will be set to true in |
| // deferred_initialize_stat method. The initialization has to be done |
| // early enough to avoid any races. See bug 6880029 for details. |
| if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) { |
| deferred_initialize_stat(); |
| } |
| |
| // Begin the process of bringing the system to a safepoint. |
| // Java threads can be in several different states and are |
| // stopped by different mechanisms: |
| // |
| // 1. Running interpreted |
| // The interpreter dispatch table is changed to force it to |
| // check for a safepoint condition between bytecodes. |
| // 2. Running in native code |
| // When returning from the native code, a Java thread must check |
| // the safepoint _state to see if we must block. If the |
| // VM thread sees a Java thread in native, it does |
| // not wait for this thread to block. The order of the memory |
| // writes and reads of both the safepoint state and the Java |
| // threads state is critical. In order to guarantee that the |
| // memory writes are serialized with respect to each other, |
| // the VM thread issues a memory barrier instruction |
| // (on MP systems). In order to avoid the overhead of issuing |
| // a memory barrier for each Java thread making native calls, each Java |
| // thread performs a write to a single memory page after changing |
| // the thread state. The VM thread performs a sequence of |
| // mprotect OS calls which forces all previous writes from all |
| // Java threads to be serialized. This is done in the |
| // os::serialize_thread_states() call. This has proven to be |
| // much more efficient than executing a membar instruction |
| // on every call to native code. |
| // 3. Running compiled Code |
| // Compiled code reads a global (Safepoint Polling) page that |
| // is set to fault if we are trying to get to a safepoint. |
| // 4. Blocked |
| // A thread which is blocked will not be allowed to return from the |
| // block condition until the safepoint operation is complete. |
| // 5. In VM or Transitioning between states |
| // If a Java thread is currently running in the VM or transitioning |
| // between states, the safepointing code will wait for the thread to |
| // block itself when it attempts transitions to a new state. |
| // |
| { |
| EventSafepointStateSynchronization sync_event; |
| int initial_running = 0; |
| |
| _state = _synchronizing; |
| OrderAccess::fence(); |
| |
| // Flush all thread states to memory |
| if (!UseMembar) { |
| os::serialize_thread_states(); |
| } |
| |
| // Make interpreter safepoint aware |
| Interpreter::notice_safepoints(); |
| |
| if (DeferPollingPageLoopCount < 0) { |
| // Make polling safepoint aware |
| guarantee (PageArmed == 0, "invariant") ; |
| PageArmed = 1 ; |
| os::make_polling_page_unreadable(); |
| } |
| |
| // Consider using active_processor_count() ... but that call is expensive. |
| int ncpus = os::processor_count() ; |
| |
| #ifdef ASSERT |
| for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
| assert(cur->safepoint_state()->is_running(), "Illegal initial state"); |
| // Clear the visited flag to ensure that the critical counts are collected properly. |
| cur->set_visited_for_critical_count(false); |
| } |
| #endif // ASSERT |
| |
| if (SafepointTimeout) |
| safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS; |
| |
| // Iterate through all threads until it have been determined how to stop them all at a safepoint |
| unsigned int iterations = 0; |
| int steps = 0 ; |
| while(still_running > 0) { |
| for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
| assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended"); |
| ThreadSafepointState *cur_state = cur->safepoint_state(); |
| if (cur_state->is_running()) { |
| cur_state->examine_state_of_thread(); |
| if (!cur_state->is_running()) { |
| still_running--; |
| // consider adjusting steps downward: |
| // steps = 0 |
| // steps -= NNN |
| // steps >>= 1 |
| // steps = MIN(steps, 2000-100) |
| // if (iterations != 0) steps -= NNN |
| } |
| LogTarget(Trace, safepoint) lt; |
| if (lt.is_enabled()) { |
| ResourceMark rm; |
| LogStream ls(lt); |
| cur_state->print_on(&ls); |
| } |
| } |
| } |
| |
| if (iterations == 0) { |
| initial_running = still_running; |
| if (PrintSafepointStatistics) { |
| begin_statistics(nof_threads, still_running); |
| } |
| } |
| |
| if (still_running > 0) { |
| // Check for if it takes to long |
| if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) { |
| print_safepoint_timeout(_spinning_timeout); |
| } |
| |
| // Spin to avoid context switching. |
| // There's a tension between allowing the mutators to run (and rendezvous) |
| // vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that |
| // a mutator might otherwise use profitably to reach a safepoint. Excessive |
| // spinning by the VM thread on a saturated system can increase rendezvous latency. |
| // Blocking or yielding incur their own penalties in the form of context switching |
| // and the resultant loss of $ residency. |
| // |
| // Further complicating matters is that yield() does not work as naively expected |
| // on many platforms -- yield() does not guarantee that any other ready threads |
| // will run. As such we revert to naked_short_sleep() after some number of iterations. |
| // nakes_short_sleep() is implemented as a short unconditional sleep. |
| // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping |
| // can actually increase the time it takes the VM thread to detect that a system-wide |
| // stop-the-world safepoint has been reached. In a pathological scenario such as that |
| // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe. |
| // In that case the mutators will be stalled waiting for the safepoint to complete and the |
| // the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread |
| // will eventually wake up and detect that all mutators are safe, at which point |
| // we'll again make progress. |
| // |
| // Beware too that that the VMThread typically runs at elevated priority. |
| // Its default priority is higher than the default mutator priority. |
| // Obviously, this complicates spinning. |
| // |
| // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0). |
| // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will. |
| // |
| // See the comments in synchronizer.cpp for additional remarks on spinning. |
| // |
| // In the future we might: |
| // 1. Modify the safepoint scheme to avoid potentially unbounded spinning. |
| // This is tricky as the path used by a thread exiting the JVM (say on |
| // on JNI call-out) simply stores into its state field. The burden |
| // is placed on the VM thread, which must poll (spin). |
| // 2. Find something useful to do while spinning. If the safepoint is GC-related |
| // we might aggressively scan the stacks of threads that are already safe. |
| // 3. Use Solaris schedctl to examine the state of the still-running mutators. |
| // If all the mutators are ONPROC there's no reason to sleep or yield. |
| // 4. YieldTo() any still-running mutators that are ready but OFFPROC. |
| // 5. Check system saturation. If the system is not fully saturated then |
| // simply spin and avoid sleep/yield. |
| // 6. As still-running mutators rendezvous they could unpark the sleeping |
| // VMthread. This works well for still-running mutators that become |
| // safe. The VMthread must still poll for mutators that call-out. |
| // 7. Drive the policy on time-since-begin instead of iterations. |
| // 8. Consider making the spin duration a function of the # of CPUs: |
| // Spin = (((ncpus-1) * M) + K) + F(still_running) |
| // Alternately, instead of counting iterations of the outer loop |
| // we could count the # of threads visited in the inner loop, above. |
| // 9. On windows consider using the return value from SwitchThreadTo() |
| // to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions. |
| |
| if (int(iterations) == DeferPollingPageLoopCount) { |
| guarantee (PageArmed == 0, "invariant") ; |
| PageArmed = 1 ; |
| os::make_polling_page_unreadable(); |
| } |
| |
| // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or |
| // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus) |
| ++steps ; |
| if (ncpus > 1 && steps < SafepointSpinBeforeYield) { |
| SpinPause() ; // MP-Polite spin |
| } else |
| if (steps < DeferThrSuspendLoopCount) { |
| os::naked_yield() ; |
| } else { |
| os::naked_short_sleep(1); |
| } |
| |
| iterations ++ ; |
| } |
| assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long"); |
| } |
| assert(still_running == 0, "sanity check"); |
| |
| if (PrintSafepointStatistics) { |
| update_statistics_on_spin_end(); |
| } |
| |
| if (sync_event.should_commit()) { |
| sync_event.set_safepointId(safepoint_counter()); |
| sync_event.set_initialThreadCount(initial_running); |
| sync_event.set_runningThreadCount(_waiting_to_block); |
| sync_event.set_iterations(iterations); |
| sync_event.commit(); |
| } |
| } //EventSafepointStateSync |
| |
| // wait until all threads are stopped |
| { |
| EventSafepointWaitBlocked wait_blocked_event; |
| int initial_waiting_to_block = _waiting_to_block; |
| |
| while (_waiting_to_block > 0) { |
| log_debug(safepoint)("Waiting for %d thread(s) to block", _waiting_to_block); |
| if (!SafepointTimeout || timeout_error_printed) { |
| Safepoint_lock->wait(true); // true, means with no safepoint checks |
| } else { |
| // Compute remaining time |
| jlong remaining_time = safepoint_limit_time - os::javaTimeNanos(); |
| |
| // If there is no remaining time, then there is an error |
| if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) { |
| print_safepoint_timeout(_blocking_timeout); |
| } |
| } |
| } |
| assert(_waiting_to_block == 0, "sanity check"); |
| |
| #ifndef PRODUCT |
| if (SafepointTimeout) { |
| jlong current_time = os::javaTimeNanos(); |
| if (safepoint_limit_time < current_time) { |
| tty->print_cr("# SafepointSynchronize: Finished after " |
| INT64_FORMAT_W(6) " ms", |
| (int64_t)((current_time - safepoint_limit_time) / MICROUNITS + |
| (jlong)SafepointTimeoutDelay)); |
| } |
| } |
| #endif |
| |
| assert((_safepoint_counter & 0x1) == 0, "must be even"); |
| assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); |
| _safepoint_counter ++; |
| |
| // Record state |
| _state = _synchronized; |
| |
| OrderAccess::fence(); |
| |
| if (wait_blocked_event.should_commit()) { |
| wait_blocked_event.set_safepointId(safepoint_counter()); |
| wait_blocked_event.set_runningThreadCount(initial_waiting_to_block); |
| wait_blocked_event.commit(); |
| } |
| } // EventSafepointWaitBlocked |
| |
| #ifdef ASSERT |
| for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) { |
| // make sure all the threads were visited |
| assert(cur->was_visited_for_critical_count(), "missed a thread"); |
| } |
| #endif // ASSERT |
| |
| // Update the count of active JNI critical regions |
| GCLocker::set_jni_lock_count(_current_jni_active_count); |
| |
| if (log_is_enabled(Debug, safepoint)) { |
| log_debug(safepoint)("Entering safepoint region: %s", VMThread::vm_safepoint_description()); |
| } |
| |
| RuntimeService::record_safepoint_synchronized(); |
| if (PrintSafepointStatistics) { |
| update_statistics_on_sync_end(os::javaTimeNanos()); |
| } |
| |
| // Call stuff that needs to be run when a safepoint is just about to be completed |
| { |
| EventSafepointCleanup cleanup_event; |
| do_cleanup_tasks(); |
| if (cleanup_event.should_commit()) { |
| cleanup_event.set_safepointId(safepoint_counter()); |
| cleanup_event.commit(); |
| } |
| } |
| |
| if (PrintSafepointStatistics) { |
| // Record how much time spend on the above cleanup tasks |
| update_statistics_on_cleanup_end(os::javaTimeNanos()); |
| } |
| if (begin_event.should_commit()) { |
| begin_event.set_safepointId(safepoint_counter()); |
| begin_event.set_totalThreadCount(nof_threads); |
| begin_event.set_jniCriticalThreadCount(_current_jni_active_count); |
| begin_event.commit(); |
| } |
| } |
| |
| // Wake up all threads, so they are ready to resume execution after the safepoint |
| // operation has been carried out |
| void SafepointSynchronize::end() { |
| EventSafepointEnd event; |
| int safepoint_id = safepoint_counter(); // Keep the odd counter as "id" |
| |
| assert(Threads_lock->owned_by_self(), "must hold Threads_lock"); |
| assert((_safepoint_counter & 0x1) == 1, "must be odd"); |
| _safepoint_counter ++; |
| // memory fence isn't required here since an odd _safepoint_counter |
| // value can do no harm and a fence is issued below anyway. |
| |
| DEBUG_ONLY(Thread* myThread = Thread::current();) |
| assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint"); |
| |
| if (PrintSafepointStatistics) { |
| end_statistics(os::javaTimeNanos()); |
| } |
| |
| #ifdef ASSERT |
| // A pending_exception cannot be installed during a safepoint. The threads |
| // may install an async exception after they come back from a safepoint into |
| // pending_exception after they unblock. But that should happen later. |
| for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { |
| assert (!(cur->has_pending_exception() && |
| cur->safepoint_state()->is_at_poll_safepoint()), |
| "safepoint installed a pending exception"); |
| } |
| #endif // ASSERT |
| |
| if (PageArmed) { |
| // Make polling safepoint aware |
| os::make_polling_page_readable(); |
| PageArmed = 0 ; |
| } |
| |
| // Remove safepoint check from interpreter |
| Interpreter::ignore_safepoints(); |
| |
| { |
| MutexLocker mu(Safepoint_lock); |
| |
| assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization"); |
| |
| // Set to not synchronized, so the threads will not go into the signal_thread_blocked method |
| // when they get restarted. |
| _state = _not_synchronized; |
| OrderAccess::fence(); |
| |
| log_debug(safepoint)("Leaving safepoint region"); |
| |
| // Start suspended threads |
| for(JavaThread *current = Threads::first(); current; current = current->next()) { |
| // A problem occurring on Solaris is when attempting to restart threads |
| // the first #cpus - 1 go well, but then the VMThread is preempted when we get |
| // to the next one (since it has been running the longest). We then have |
| // to wait for a cpu to become available before we can continue restarting |
| // threads. |
| // FIXME: This causes the performance of the VM to degrade when active and with |
| // large numbers of threads. Apparently this is due to the synchronous nature |
| // of suspending threads. |
| // |
| // TODO-FIXME: the comments above are vestigial and no longer apply. |
| // Furthermore, using solaris' schedctl in this particular context confers no benefit |
| if (VMThreadHintNoPreempt) { |
| os::hint_no_preempt(); |
| } |
| ThreadSafepointState* cur_state = current->safepoint_state(); |
| assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint"); |
| cur_state->restart(); |
| assert(cur_state->is_running(), "safepoint state has not been reset"); |
| } |
| |
| RuntimeService::record_safepoint_end(); |
| |
| // Release threads lock, so threads can be created/destroyed again. It will also starts all threads |
| // blocked in signal_thread_blocked |
| Threads_lock->unlock(); |
| |
| } |
| #if INCLUDE_ALL_GCS |
| // If there are any concurrent GC threads resume them. |
| if (UseConcMarkSweepGC) { |
| ConcurrentMarkSweepThread::desynchronize(false); |
| } else if (UseG1GC) { |
| SuspendibleThreadSet::desynchronize(); |
| } |
| #endif // INCLUDE_ALL_GCS |
| // record this time so VMThread can keep track how much time has elapsed |
| // since last safepoint. |
| _end_of_last_safepoint = os::javaTimeMillis(); |
| |
| if (event.should_commit()) { |
| event.set_safepointId(safepoint_id); |
| event.commit(); |
| } |
| } |
| |
| bool SafepointSynchronize::is_cleanup_needed() { |
| // Need a safepoint if there are many monitors to deflate. |
| if (ObjectSynchronizer::is_cleanup_needed()) return true; |
| // Need a safepoint if some inline cache buffers is non-empty |
| if (!InlineCacheBuffer::is_empty()) return true; |
| return false; |
| } |
| |
| static void event_safepoint_cleanup_task_commit(EventSafepointCleanupTask& event, const char* name) { |
| if (event.should_commit()) { |
| event.set_safepointId(SafepointSynchronize::safepoint_counter()); |
| event.set_name(name); |
| event.commit(); |
| } |
| } |
| |
| class ParallelSPCleanupThreadClosure : public ThreadClosure { |
| private: |
| CodeBlobClosure* _nmethod_cl; |
| DeflateMonitorCounters* _counters; |
| |
| public: |
| ParallelSPCleanupThreadClosure(DeflateMonitorCounters* counters) : |
| _counters(counters), |
| _nmethod_cl(NMethodSweeper::prepare_mark_active_nmethods()) {} |
| |
| void do_thread(Thread* thread) { |
| ObjectSynchronizer::deflate_thread_local_monitors(thread, _counters); |
| if (_nmethod_cl != NULL && thread->is_Java_thread() && |
| ! thread->is_Code_cache_sweeper_thread()) { |
| JavaThread* jt = (JavaThread*) thread; |
| jt->nmethods_do(_nmethod_cl); |
| } |
| } |
| }; |
| |
| class ParallelSPCleanupTask : public AbstractGangTask { |
| private: |
| SubTasksDone _subtasks; |
| ParallelSPCleanupThreadClosure _cleanup_threads_cl; |
| uint _num_workers; |
| DeflateMonitorCounters* _counters; |
| public: |
| ParallelSPCleanupTask(uint num_workers, DeflateMonitorCounters* counters) : |
| AbstractGangTask("Parallel Safepoint Cleanup"), |
| _cleanup_threads_cl(ParallelSPCleanupThreadClosure(counters)), |
| _num_workers(num_workers), |
| _subtasks(SubTasksDone(SafepointSynchronize::SAFEPOINT_CLEANUP_NUM_TASKS)), |
| _counters(counters) {} |
| |
| void work(uint worker_id) { |
| // All threads deflate monitors and mark nmethods (if necessary). |
| Threads::parallel_java_threads_do(&_cleanup_threads_cl); |
| |
| if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_DEFLATE_MONITORS)) { |
| const char* name = "deflating idle monitors"; |
| EventSafepointCleanupTask event; |
| TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); |
| ObjectSynchronizer::deflate_idle_monitors(_counters); |
| event_safepoint_cleanup_task_commit(event, name); |
| } |
| |
| if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES)) { |
| const char* name = "updating inline caches"; |
| EventSafepointCleanupTask event; |
| TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); |
| InlineCacheBuffer::update_inline_caches(); |
| event_safepoint_cleanup_task_commit(event, name); |
| } |
| |
| if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_COMPILATION_POLICY)) { |
| const char* name = "compilation policy safepoint handler"; |
| EventSafepointCleanupTask event; |
| TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); |
| CompilationPolicy::policy()->do_safepoint_work(); |
| event_safepoint_cleanup_task_commit(event, name); |
| } |
| |
| if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH)) { |
| if (SymbolTable::needs_rehashing()) { |
| const char* name = "rehashing symbol table"; |
| EventSafepointCleanupTask event; |
| TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); |
| SymbolTable::rehash_table(); |
| event_safepoint_cleanup_task_commit(event, name); |
| } |
| } |
| |
| if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_STRING_TABLE_REHASH)) { |
| if (StringTable::needs_rehashing()) { |
| const char* name = "rehashing string table"; |
| EventSafepointCleanupTask event; |
| TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); |
| StringTable::rehash_table(); |
| event_safepoint_cleanup_task_commit(event, name); |
| } |
| } |
| |
| if (!_subtasks.is_task_claimed(SafepointSynchronize::SAFEPOINT_CLEANUP_CLD_PURGE)) { |
| // CMS delays purging the CLDG until the beginning of the next safepoint and to |
| // make sure concurrent sweep is done |
| const char* name = "purging class loader data graph"; |
| EventSafepointCleanupTask event; |
| TraceTime timer(name, TRACETIME_LOG(Info, safepoint, cleanup)); |
| ClassLoaderDataGraph::purge_if_needed(); |
| event_safepoint_cleanup_task_commit(event, name); |
| } |
| _subtasks.all_tasks_completed(_num_workers); |
| } |
| }; |
| |
| // Various cleaning tasks that should be done periodically at safepoints. |
| void SafepointSynchronize::do_cleanup_tasks() { |
| |
| TraceTime timer("safepoint cleanup tasks", TRACETIME_LOG(Info, safepoint, cleanup)); |
| |
| // Prepare for monitor deflation. |
| DeflateMonitorCounters deflate_counters; |
| ObjectSynchronizer::prepare_deflate_idle_monitors(&deflate_counters); |
| |
| CollectedHeap* heap = Universe::heap(); |
| assert(heap != NULL, "heap not initialized yet?"); |
| WorkGang* cleanup_workers = heap->get_safepoint_workers(); |
| if (cleanup_workers != NULL) { |
| // Parallel cleanup using GC provided thread pool. |
| uint num_cleanup_workers = cleanup_workers->active_workers(); |
| ParallelSPCleanupTask cleanup(num_cleanup_workers, &deflate_counters); |
| StrongRootsScope srs(num_cleanup_workers); |
| cleanup_workers->run_task(&cleanup); |
| } else { |
| // Serial cleanup using VMThread. |
| ParallelSPCleanupTask cleanup(1, &deflate_counters); |
| StrongRootsScope srs(1); |
| cleanup.work(0); |
| } |
| |
| // Finish monitor deflation. |
| ObjectSynchronizer::finish_deflate_idle_monitors(&deflate_counters); |
| } |
| |
| |
| bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) { |
| switch(state) { |
| case _thread_in_native: |
| // native threads are safe if they have no java stack or have walkable stack |
| return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable(); |
| |
| // blocked threads should have already have walkable stack |
| case _thread_blocked: |
| assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable"); |
| return true; |
| |
| default: |
| return false; |
| } |
| } |
| |
| |
| // See if the thread is running inside a lazy critical native and |
| // update the thread critical count if so. Also set a suspend flag to |
| // cause the native wrapper to return into the JVM to do the unlock |
| // once the native finishes. |
| void SafepointSynchronize::check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state) { |
| if (state == _thread_in_native && |
| thread->has_last_Java_frame() && |
| thread->frame_anchor()->walkable()) { |
| // This thread might be in a critical native nmethod so look at |
| // the top of the stack and increment the critical count if it |
| // is. |
| frame wrapper_frame = thread->last_frame(); |
| CodeBlob* stub_cb = wrapper_frame.cb(); |
| if (stub_cb != NULL && |
| stub_cb->is_nmethod() && |
| stub_cb->as_nmethod_or_null()->is_lazy_critical_native()) { |
| // A thread could potentially be in a critical native across |
| // more than one safepoint, so only update the critical state on |
| // the first one. When it returns it will perform the unlock. |
| if (!thread->do_critical_native_unlock()) { |
| #ifdef ASSERT |
| if (!thread->in_critical()) { |
| GCLocker::increment_debug_jni_lock_count(); |
| } |
| #endif |
| thread->enter_critical(); |
| // Make sure the native wrapper calls back on return to |
| // perform the needed critical unlock. |
| thread->set_critical_native_unlock(); |
| } |
| } |
| } |
| } |
| |
| |
| |
| // ------------------------------------------------------------------------------------------------------- |
| // Implementation of Safepoint callback point |
| |
| void SafepointSynchronize::block(JavaThread *thread) { |
| assert(thread != NULL, "thread must be set"); |
| assert(thread->is_Java_thread(), "not a Java thread"); |
| |
| // Threads shouldn't block if they are in the middle of printing, but... |
| ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id()); |
| |
| // Only bail from the block() call if the thread is gone from the |
| // thread list; starting to exit should still block. |
| if (thread->is_terminated()) { |
| // block current thread if we come here from native code when VM is gone |
| thread->block_if_vm_exited(); |
| |
| // otherwise do nothing |
| return; |
| } |
| |
| JavaThreadState state = thread->thread_state(); |
| thread->frame_anchor()->make_walkable(thread); |
| |
| // Check that we have a valid thread_state at this point |
| switch(state) { |
| case _thread_in_vm_trans: |
| case _thread_in_Java: // From compiled code |
| |
| // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case, |
| // we pretend we are still in the VM. |
| thread->set_thread_state(_thread_in_vm); |
| |
| if (is_synchronizing()) { |
| Atomic::inc (&TryingToBlock) ; |
| } |
| |
| // We will always be holding the Safepoint_lock when we are examine the state |
| // of a thread. Hence, the instructions between the Safepoint_lock->lock() and |
| // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code |
| Safepoint_lock->lock_without_safepoint_check(); |
| if (is_synchronizing()) { |
| // Decrement the number of threads to wait for and signal vm thread |
| assert(_waiting_to_block > 0, "sanity check"); |
| _waiting_to_block--; |
| thread->safepoint_state()->set_has_called_back(true); |
| |
| DEBUG_ONLY(thread->set_visited_for_critical_count(true)); |
| if (thread->in_critical()) { |
| // Notice that this thread is in a critical section |
| increment_jni_active_count(); |
| } |
| |
| // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread |
| if (_waiting_to_block == 0) { |
| Safepoint_lock->notify_all(); |
| } |
| } |
| |
| // We transition the thread to state _thread_blocked here, but |
| // we can't do our usual check for external suspension and then |
| // self-suspend after the lock_without_safepoint_check() call |
| // below because we are often called during transitions while |
| // we hold different locks. That would leave us suspended while |
| // holding a resource which results in deadlocks. |
| thread->set_thread_state(_thread_blocked); |
| Safepoint_lock->unlock(); |
| |
| // We now try to acquire the threads lock. Since this lock is hold by the VM thread during |
| // the entire safepoint, the threads will all line up here during the safepoint. |
| Threads_lock->lock_without_safepoint_check(); |
| // restore original state. This is important if the thread comes from compiled code, so it |
| // will continue to execute with the _thread_in_Java state. |
| thread->set_thread_state(state); |
| Threads_lock->unlock(); |
| break; |
| |
| case _thread_in_native_trans: |
| case _thread_blocked_trans: |
| case _thread_new_trans: |
| if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) { |
| thread->print_thread_state(); |
| fatal("Deadlock in safepoint code. " |
| "Should have called back to the VM before blocking."); |
| } |
| |
| // We transition the thread to state _thread_blocked here, but |
| // we can't do our usual check for external suspension and then |
| // self-suspend after the lock_without_safepoint_check() call |
| // below because we are often called during transitions while |
| // we hold different locks. That would leave us suspended while |
| // holding a resource which results in deadlocks. |
| thread->set_thread_state(_thread_blocked); |
| |
| // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence, |
| // the safepoint code might still be waiting for it to block. We need to change the state here, |
| // so it can see that it is at a safepoint. |
| |
| // Block until the safepoint operation is completed. |
| Threads_lock->lock_without_safepoint_check(); |
| |
| // Restore state |
| thread->set_thread_state(state); |
| |
| Threads_lock->unlock(); |
| break; |
| |
| default: |
| fatal("Illegal threadstate encountered: %d", state); |
| } |
| |
| // Check for pending. async. exceptions or suspends - except if the |
| // thread was blocked inside the VM. has_special_runtime_exit_condition() |
| // is called last since it grabs a lock and we only want to do that when |
| // we must. |
| // |
| // Note: we never deliver an async exception at a polling point as the |
| // compiler may not have an exception handler for it. The polling |
| // code will notice the async and deoptimize and the exception will |
| // be delivered. (Polling at a return point is ok though). Sure is |
| // a lot of bother for a deprecated feature... |
| // |
| // We don't deliver an async exception if the thread state is |
| // _thread_in_native_trans so JNI functions won't be called with |
| // a surprising pending exception. If the thread state is going back to java, |
| // async exception is checked in check_special_condition_for_native_trans(). |
| |
| if (state != _thread_blocked_trans && |
| state != _thread_in_vm_trans && |
| thread->has_special_runtime_exit_condition()) { |
| thread->handle_special_runtime_exit_condition( |
| !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans)); |
| } |
| } |
| |
| // ------------------------------------------------------------------------------------------------------ |
| // Exception handlers |
| |
| |
| void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) { |
| assert(thread->is_Java_thread(), "polling reference encountered by VM thread"); |
| assert(thread->thread_state() == _thread_in_Java, "should come from Java code"); |
| assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization"); |
| |
| if (ShowSafepointMsgs) { |
| tty->print("handle_polling_page_exception: "); |
| } |
| |
| if (PrintSafepointStatistics) { |
| inc_page_trap_count(); |
| } |
| |
| ThreadSafepointState* state = thread->safepoint_state(); |
| |
| state->handle_polling_page_exception(); |
| } |
| |
| |
| void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) { |
| if (!timeout_error_printed) { |
| timeout_error_printed = true; |
| // Print out the thread info which didn't reach the safepoint for debugging |
| // purposes (useful when there are lots of threads in the debugger). |
| tty->cr(); |
| tty->print_cr("# SafepointSynchronize::begin: Timeout detected:"); |
| if (reason == _spinning_timeout) { |
| tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint."); |
| } else if (reason == _blocking_timeout) { |
| tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop."); |
| } |
| |
| tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:"); |
| ThreadSafepointState *cur_state; |
| ResourceMark rm; |
| for(JavaThread *cur_thread = Threads::first(); cur_thread; |
| cur_thread = cur_thread->next()) { |
| cur_state = cur_thread->safepoint_state(); |
| |
| if (cur_thread->thread_state() != _thread_blocked && |
| ((reason == _spinning_timeout && cur_state->is_running()) || |
| (reason == _blocking_timeout && !cur_state->has_called_back()))) { |
| tty->print("# "); |
| cur_thread->print(); |
| tty->cr(); |
| } |
| } |
| tty->print_cr("# SafepointSynchronize::begin: (End of list)"); |
| } |
| |
| // To debug the long safepoint, specify both DieOnSafepointTimeout & |
| // ShowMessageBoxOnError. |
| if (DieOnSafepointTimeout) { |
| fatal("Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.", |
| SafepointTimeoutDelay, VMThread::vm_safepoint_description()); |
| } |
| } |
| |
| |
| // ------------------------------------------------------------------------------------------------------- |
| // Implementation of ThreadSafepointState |
| |
| ThreadSafepointState::ThreadSafepointState(JavaThread *thread) { |
| _thread = thread; |
| _type = _running; |
| _has_called_back = false; |
| _at_poll_safepoint = false; |
| } |
| |
| void ThreadSafepointState::create(JavaThread *thread) { |
| ThreadSafepointState *state = new ThreadSafepointState(thread); |
| thread->set_safepoint_state(state); |
| } |
| |
| void ThreadSafepointState::destroy(JavaThread *thread) { |
| if (thread->safepoint_state()) { |
| delete(thread->safepoint_state()); |
| thread->set_safepoint_state(NULL); |
| } |
| } |
| |
| void ThreadSafepointState::examine_state_of_thread() { |
| assert(is_running(), "better be running or just have hit safepoint poll"); |
| |
| JavaThreadState state = _thread->thread_state(); |
| |
| // Save the state at the start of safepoint processing. |
| _orig_thread_state = state; |
| |
| // Check for a thread that is suspended. Note that thread resume tries |
| // to grab the Threads_lock which we own here, so a thread cannot be |
| // resumed during safepoint synchronization. |
| |
| // We check to see if this thread is suspended without locking to |
| // avoid deadlocking with a third thread that is waiting for this |
| // thread to be suspended. The third thread can notice the safepoint |
| // that we're trying to start at the beginning of its SR_lock->wait() |
| // call. If that happens, then the third thread will block on the |
| // safepoint while still holding the underlying SR_lock. We won't be |
| // able to get the SR_lock and we'll deadlock. |
| // |
| // We don't need to grab the SR_lock here for two reasons: |
| // 1) The suspend flags are both volatile and are set with an |
| // Atomic::cmpxchg() call so we should see the suspended |
| // state right away. |
| // 2) We're being called from the safepoint polling loop; if |
| // we don't see the suspended state on this iteration, then |
| // we'll come around again. |
| // |
| bool is_suspended = _thread->is_ext_suspended(); |
| if (is_suspended) { |
| roll_forward(_at_safepoint); |
| return; |
| } |
| |
| // Some JavaThread states have an initial safepoint state of |
| // running, but are actually at a safepoint. We will happily |
| // agree and update the safepoint state here. |
| if (SafepointSynchronize::safepoint_safe(_thread, state)) { |
| SafepointSynchronize::check_for_lazy_critical_native(_thread, state); |
| roll_forward(_at_safepoint); |
| return; |
| } |
| |
| if (state == _thread_in_vm) { |
| roll_forward(_call_back); |
| return; |
| } |
| |
| // All other thread states will continue to run until they |
| // transition and self-block in state _blocked |
| // Safepoint polling in compiled code causes the Java threads to do the same. |
| // Note: new threads may require a malloc so they must be allowed to finish |
| |
| assert(is_running(), "examine_state_of_thread on non-running thread"); |
| return; |
| } |
| |
| // Returns true is thread could not be rolled forward at present position. |
| void ThreadSafepointState::roll_forward(suspend_type type) { |
| _type = type; |
| |
| switch(_type) { |
| case _at_safepoint: |
| SafepointSynchronize::signal_thread_at_safepoint(); |
| DEBUG_ONLY(_thread->set_visited_for_critical_count(true)); |
| if (_thread->in_critical()) { |
| // Notice that this thread is in a critical section |
| SafepointSynchronize::increment_jni_active_count(); |
| } |
| break; |
| |
| case _call_back: |
| set_has_called_back(false); |
| break; |
| |
| case _running: |
| default: |
| ShouldNotReachHere(); |
| } |
| } |
| |
| void ThreadSafepointState::restart() { |
| switch(type()) { |
| case _at_safepoint: |
| case _call_back: |
| break; |
| |
| case _running: |
| default: |
| tty->print_cr("restart thread " INTPTR_FORMAT " with state %d", |
| p2i(_thread), _type); |
| _thread->print(); |
| ShouldNotReachHere(); |
| } |
| _type = _running; |
| set_has_called_back(false); |
| } |
| |
| |
| void ThreadSafepointState::print_on(outputStream *st) const { |
| const char *s = NULL; |
| |
| switch(_type) { |
| case _running : s = "_running"; break; |
| case _at_safepoint : s = "_at_safepoint"; break; |
| case _call_back : s = "_call_back"; break; |
| default: |
| ShouldNotReachHere(); |
| } |
| |
| st->print_cr("Thread: " INTPTR_FORMAT |
| " [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d", |
| p2i(_thread), _thread->osthread()->thread_id(), s, _has_called_back, |
| _at_poll_safepoint); |
| |
| _thread->print_thread_state_on(st); |
| } |
| |
| // --------------------------------------------------------------------------------------------------------------------- |
| |
| // Block the thread at the safepoint poll or poll return. |
| void ThreadSafepointState::handle_polling_page_exception() { |
| |
| // Check state. block() will set thread state to thread_in_vm which will |
| // cause the safepoint state _type to become _call_back. |
| assert(type() == ThreadSafepointState::_running, |
| "polling page exception on thread not running state"); |
| |
| // Step 1: Find the nmethod from the return address |
| if (ShowSafepointMsgs && Verbose) { |
| tty->print_cr("Polling page exception at " INTPTR_FORMAT, p2i(thread()->saved_exception_pc())); |
| } |
| address real_return_addr = thread()->saved_exception_pc(); |
| |
| CodeBlob *cb = CodeCache::find_blob(real_return_addr); |
| assert(cb != NULL && cb->is_compiled(), "return address should be in nmethod"); |
| CompiledMethod* nm = (CompiledMethod*)cb; |
| |
| // Find frame of caller |
| frame stub_fr = thread()->last_frame(); |
| CodeBlob* stub_cb = stub_fr.cb(); |
| assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub"); |
| RegisterMap map(thread(), true); |
| frame caller_fr = stub_fr.sender(&map); |
| |
| // Should only be poll_return or poll |
| assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" ); |
| |
| // This is a poll immediately before a return. The exception handling code |
| // has already had the effect of causing the return to occur, so the execution |
| // will continue immediately after the call. In addition, the oopmap at the |
| // return point does not mark the return value as an oop (if it is), so |
| // it needs a handle here to be updated. |
| if( nm->is_at_poll_return(real_return_addr) ) { |
| // See if return type is an oop. |
| bool return_oop = nm->method()->is_returning_oop(); |
| Handle return_value; |
| if (return_oop) { |
| // The oop result has been saved on the stack together with all |
| // the other registers. In order to preserve it over GCs we need |
| // to keep it in a handle. |
| oop result = caller_fr.saved_oop_result(&map); |
| assert(oopDesc::is_oop_or_null(result), "must be oop"); |
| return_value = Handle(thread(), result); |
| assert(Universe::heap()->is_in_or_null(result), "must be heap pointer"); |
| } |
| |
| // Block the thread |
| SafepointSynchronize::block(thread()); |
| |
| // restore oop result, if any |
| if (return_oop) { |
| caller_fr.set_saved_oop_result(&map, return_value()); |
| } |
| } |
| |
| // This is a safepoint poll. Verify the return address and block. |
| else { |
| set_at_poll_safepoint(true); |
| |
| // verify the blob built the "return address" correctly |
| assert(real_return_addr == caller_fr.pc(), "must match"); |
| |
| // Block the thread |
| SafepointSynchronize::block(thread()); |
| set_at_poll_safepoint(false); |
| |
| // If we have a pending async exception deoptimize the frame |
| // as otherwise we may never deliver it. |
| if (thread()->has_async_condition()) { |
| ThreadInVMfromJavaNoAsyncException __tiv(thread()); |
| Deoptimization::deoptimize_frame(thread(), caller_fr.id()); |
| } |
| |
| // If an exception has been installed we must check for a pending deoptimization |
| // Deoptimize frame if exception has been thrown. |
| |
| if (thread()->has_pending_exception() ) { |
| RegisterMap map(thread(), true); |
| frame caller_fr = stub_fr.sender(&map); |
| if (caller_fr.is_deoptimized_frame()) { |
| // The exception patch will destroy registers that are still |
| // live and will be needed during deoptimization. Defer the |
| // Async exception should have deferred the exception until the |
| // next safepoint which will be detected when we get into |
| // the interpreter so if we have an exception now things |
| // are messed up. |
| |
| fatal("Exception installed and deoptimization is pending"); |
| } |
| } |
| } |
| } |
| |
| |
| // |
| // Statistics & Instrumentations |
| // |
| SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL; |
| jlong SafepointSynchronize::_safepoint_begin_time = 0; |
| int SafepointSynchronize::_cur_stat_index = 0; |
| julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating]; |
| julong SafepointSynchronize::_coalesced_vmop_count = 0; |
| jlong SafepointSynchronize::_max_sync_time = 0; |
| jlong SafepointSynchronize::_max_vmop_time = 0; |
| float SafepointSynchronize::_ts_of_current_safepoint = 0.0f; |
| |
| static jlong cleanup_end_time = 0; |
| static bool need_to_track_page_armed_status = false; |
| static bool init_done = false; |
| |
| // Helper method to print the header. |
| static void print_header() { |
| // The number of spaces is significant here, and should match the format |
| // specifiers in print_statistics(). |
| |
| tty->print(" vmop " |
| "[ threads: total initially_running wait_to_block ]" |
| "[ time: spin block sync cleanup vmop ] "); |
| |
| // no page armed status printed out if it is always armed. |
| if (need_to_track_page_armed_status) { |
| tty->print("page_armed "); |
| } |
| |
| tty->print_cr("page_trap_count"); |
| } |
| |
| void SafepointSynchronize::deferred_initialize_stat() { |
| if (init_done) return; |
| |
| // If PrintSafepointStatisticsTimeout is specified, the statistics data will |
| // be printed right away, in which case, _safepoint_stats will regress to |
| // a single element array. Otherwise, it is a circular ring buffer with default |
| // size of PrintSafepointStatisticsCount. |
| int stats_array_size; |
| if (PrintSafepointStatisticsTimeout > 0) { |
| stats_array_size = 1; |
| PrintSafepointStatistics = true; |
| } else { |
| stats_array_size = PrintSafepointStatisticsCount; |
| } |
| _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size |
| * sizeof(SafepointStats), mtInternal); |
| guarantee(_safepoint_stats != NULL, |
| "not enough memory for safepoint instrumentation data"); |
| |
| if (DeferPollingPageLoopCount >= 0) { |
| need_to_track_page_armed_status = true; |
| } |
| init_done = true; |
| } |
| |
| void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) { |
| assert(init_done, "safepoint statistics array hasn't been initialized"); |
| SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| |
| spstat->_time_stamp = _ts_of_current_safepoint; |
| |
| VM_Operation *op = VMThread::vm_operation(); |
| spstat->_vmop_type = (op != NULL ? op->type() : -1); |
| if (op != NULL) { |
| _safepoint_reasons[spstat->_vmop_type]++; |
| } |
| |
| spstat->_nof_total_threads = nof_threads; |
| spstat->_nof_initial_running_threads = nof_running; |
| spstat->_nof_threads_hit_page_trap = 0; |
| |
| // Records the start time of spinning. The real time spent on spinning |
| // will be adjusted when spin is done. Same trick is applied for time |
| // spent on waiting for threads to block. |
| if (nof_running != 0) { |
| spstat->_time_to_spin = os::javaTimeNanos(); |
| } else { |
| spstat->_time_to_spin = 0; |
| } |
| } |
| |
| void SafepointSynchronize::update_statistics_on_spin_end() { |
| SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| |
| jlong cur_time = os::javaTimeNanos(); |
| |
| spstat->_nof_threads_wait_to_block = _waiting_to_block; |
| if (spstat->_nof_initial_running_threads != 0) { |
| spstat->_time_to_spin = cur_time - spstat->_time_to_spin; |
| } |
| |
| if (need_to_track_page_armed_status) { |
| spstat->_page_armed = (PageArmed == 1); |
| } |
| |
| // Records the start time of waiting for to block. Updated when block is done. |
| if (_waiting_to_block != 0) { |
| spstat->_time_to_wait_to_block = cur_time; |
| } else { |
| spstat->_time_to_wait_to_block = 0; |
| } |
| } |
| |
| void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) { |
| SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| |
| if (spstat->_nof_threads_wait_to_block != 0) { |
| spstat->_time_to_wait_to_block = end_time - |
| spstat->_time_to_wait_to_block; |
| } |
| |
| // Records the end time of sync which will be used to calculate the total |
| // vm operation time. Again, the real time spending in syncing will be deducted |
| // from the start of the sync time later when end_statistics is called. |
| spstat->_time_to_sync = end_time - _safepoint_begin_time; |
| if (spstat->_time_to_sync > _max_sync_time) { |
| _max_sync_time = spstat->_time_to_sync; |
| } |
| |
| spstat->_time_to_do_cleanups = end_time; |
| } |
| |
| void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) { |
| SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| |
| // Record how long spent in cleanup tasks. |
| spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups; |
| |
| cleanup_end_time = end_time; |
| } |
| |
| void SafepointSynchronize::end_statistics(jlong vmop_end_time) { |
| SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| |
| // Update the vm operation time. |
| spstat->_time_to_exec_vmop = vmop_end_time - cleanup_end_time; |
| if (spstat->_time_to_exec_vmop > _max_vmop_time) { |
| _max_vmop_time = spstat->_time_to_exec_vmop; |
| } |
| // Only the sync time longer than the specified |
| // PrintSafepointStatisticsTimeout will be printed out right away. |
| // By default, it is -1 meaning all samples will be put into the list. |
| if ( PrintSafepointStatisticsTimeout > 0) { |
| if (spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) { |
| print_statistics(); |
| } |
| } else { |
| // The safepoint statistics will be printed out when the _safepoin_stats |
| // array fills up. |
| if (_cur_stat_index == PrintSafepointStatisticsCount - 1) { |
| print_statistics(); |
| _cur_stat_index = 0; |
| } else { |
| _cur_stat_index++; |
| } |
| } |
| } |
| |
| void SafepointSynchronize::print_statistics() { |
| for (int index = 0; index <= _cur_stat_index; index++) { |
| if (index % 30 == 0) { |
| print_header(); |
| } |
| SafepointStats* sstats = &_safepoint_stats[index]; |
| tty->print("%8.3f: ", sstats->_time_stamp); |
| tty->print("%-30s [ " |
| INT32_FORMAT_W(8) " " INT32_FORMAT_W(17) " " INT32_FORMAT_W(13) " " |
| "]", |
| (sstats->_vmop_type == -1 ? "no vm operation" : VM_Operation::name(sstats->_vmop_type)), |
| sstats->_nof_total_threads, |
| sstats->_nof_initial_running_threads, |
| sstats->_nof_threads_wait_to_block); |
| // "/ MICROUNITS " is to convert the unit from nanos to millis. |
| tty->print("[ " |
| INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " " |
| INT64_FORMAT_W(7) " " INT64_FORMAT_W(7) " " |
| INT64_FORMAT_W(7) " ] ", |
| (int64_t)(sstats->_time_to_spin / MICROUNITS), |
| (int64_t)(sstats->_time_to_wait_to_block / MICROUNITS), |
| (int64_t)(sstats->_time_to_sync / MICROUNITS), |
| (int64_t)(sstats->_time_to_do_cleanups / MICROUNITS), |
| (int64_t)(sstats->_time_to_exec_vmop / MICROUNITS)); |
| |
| if (need_to_track_page_armed_status) { |
| tty->print(INT32_FORMAT_W(10) " ", sstats->_page_armed); |
| } |
| tty->print_cr(INT32_FORMAT_W(15) " ", sstats->_nof_threads_hit_page_trap); |
| } |
| } |
| |
| // This method will be called when VM exits. It will first call |
| // print_statistics to print out the rest of the sampling. Then |
| // it tries to summarize the sampling. |
| void SafepointSynchronize::print_stat_on_exit() { |
| if (_safepoint_stats == NULL) return; |
| |
| SafepointStats *spstat = &_safepoint_stats[_cur_stat_index]; |
| |
| // During VM exit, end_statistics may not get called and in that |
| // case, if the sync time is less than PrintSafepointStatisticsTimeout, |
| // don't print it out. |
| // Approximate the vm op time. |
| _safepoint_stats[_cur_stat_index]._time_to_exec_vmop = |
| os::javaTimeNanos() - cleanup_end_time; |
| |
| if ( PrintSafepointStatisticsTimeout < 0 || |
| spstat->_time_to_sync > (jlong)PrintSafepointStatisticsTimeout * MICROUNITS) { |
| print_statistics(); |
| } |
| tty->cr(); |
| |
| // Print out polling page sampling status. |
| if (!need_to_track_page_armed_status) { |
| tty->print_cr("Polling page always armed"); |
| } else { |
| tty->print_cr("Defer polling page loop count = " INTX_FORMAT "\n", |
| DeferPollingPageLoopCount); |
| } |
| |
| for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) { |
| if (_safepoint_reasons[index] != 0) { |
| tty->print_cr("%-26s" UINT64_FORMAT_W(10), VM_Operation::name(index), |
| _safepoint_reasons[index]); |
| } |
| } |
| |
| tty->print_cr(UINT64_FORMAT_W(5) " VM operations coalesced during safepoint", |
| _coalesced_vmop_count); |
| tty->print_cr("Maximum sync time " INT64_FORMAT_W(5) " ms", |
| (int64_t)(_max_sync_time / MICROUNITS)); |
| tty->print_cr("Maximum vm operation time (except for Exit VM operation) " |
| INT64_FORMAT_W(5) " ms", |
| (int64_t)(_max_vmop_time / MICROUNITS)); |
| } |
| |
| // ------------------------------------------------------------------------------------------------ |
| // Non-product code |
| |
| #ifndef PRODUCT |
| |
| void SafepointSynchronize::print_state() { |
| if (_state == _not_synchronized) { |
| tty->print_cr("not synchronized"); |
| } else if (_state == _synchronizing || _state == _synchronized) { |
| tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" : |
| "synchronized"); |
| |
| for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) { |
| cur->safepoint_state()->print(); |
| } |
| } |
| } |
| |
| void SafepointSynchronize::safepoint_msg(const char* format, ...) { |
| if (ShowSafepointMsgs) { |
| va_list ap; |
| va_start(ap, format); |
| tty->vprint_cr(format, ap); |
| va_end(ap); |
| } |
| } |
| |
| #endif // !PRODUCT |