--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/safepoint.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,1425 @@
+/*
+ * 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