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/*
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* Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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# include "incls/_precompiled.incl"
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# include "incls/_safepoint.cpp.incl"
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// --------------------------------------------------------------------------------------------------
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// Implementation of Safepoint begin/end
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SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
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volatile int SafepointSynchronize::_waiting_to_block = 0;
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jlong SafepointSynchronize::_last_safepoint = 0;
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volatile int SafepointSynchronize::_safepoint_counter = 0;
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static volatile int PageArmed = 0 ; // safepoint polling page is RO|RW vs PROT_NONE
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static volatile int TryingToBlock = 0 ; // proximate value -- for advisory use only
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static bool timeout_error_printed = false;
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// Roll all threads forward to a safepoint and suspend them all
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void SafepointSynchronize::begin() {
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Thread* myThread = Thread::current();
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assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
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_last_safepoint = os::javaTimeNanos();
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#ifndef SERIALGC
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if (UseConcMarkSweepGC) {
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// In the future we should investigate whether CMS can use the
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// more-general mechanism below. DLD (01/05).
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ConcurrentMarkSweepThread::synchronize(false);
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} else {
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ConcurrentGCThread::safepoint_synchronize();
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}
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#endif // SERIALGC
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// By getting the Threads_lock, we assure that no threads are about to start or
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// exit. It is released again in SafepointSynchronize::end().
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Threads_lock->lock();
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assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
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int nof_threads = Threads::number_of_threads();
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if (TraceSafepoint) {
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tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
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}
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RuntimeService::record_safepoint_begin();
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{
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MutexLocker mu(Safepoint_lock);
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// Set number of threads to wait for, before we initiate the callbacks
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_waiting_to_block = nof_threads;
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TryingToBlock = 0 ;
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int still_running = nof_threads;
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// Save the starting time, so that it can be compared to see if this has taken
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// too long to complete.
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jlong safepoint_limit_time;
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timeout_error_printed = false;
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// Begin the process of bringing the system to a safepoint.
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// Java threads can be in several different states and are
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// stopped by different mechanisms:
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//
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// 1. Running interpreted
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// The interpeter dispatch table is changed to force it to
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// check for a safepoint condition between bytecodes.
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// 2. Running in native code
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// When returning from the native code, a Java thread must check
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// the safepoint _state to see if we must block. If the
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// VM thread sees a Java thread in native, it does
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// not wait for this thread to block. The order of the memory
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// writes and reads of both the safepoint state and the Java
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// threads state is critical. In order to guarantee that the
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// memory writes are serialized with respect to each other,
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// the VM thread issues a memory barrier instruction
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// (on MP systems). In order to avoid the overhead of issuing
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// a memory barrier for each Java thread making native calls, each Java
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// thread performs a write to a single memory page after changing
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// the thread state. The VM thread performs a sequence of
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// mprotect OS calls which forces all previous writes from all
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// Java threads to be serialized. This is done in the
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// os::serialize_thread_states() call. This has proven to be
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// much more efficient than executing a membar instruction
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// on every call to native code.
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// 3. Running compiled Code
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// Compiled code reads a global (Safepoint Polling) page that
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// is set to fault if we are trying to get to a safepoint.
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// 4. Blocked
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// A thread which is blocked will not be allowed to return from the
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// block condition until the safepoint operation is complete.
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// 5. In VM or Transitioning between states
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// If a Java thread is currently running in the VM or transitioning
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// between states, the safepointing code will wait for the thread to
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// block itself when it attempts transitions to a new state.
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//
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_state = _synchronizing;
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OrderAccess::fence();
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// Flush all thread states to memory
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if (!UseMembar) {
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os::serialize_thread_states();
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}
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// Make interpreter safepoint aware
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Interpreter::notice_safepoints();
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if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
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// Make polling safepoint aware
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guarantee (PageArmed == 0, "invariant") ;
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PageArmed = 1 ;
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os::make_polling_page_unreadable();
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}
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// Consider using active_processor_count() ... but that call is expensive.
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int ncpus = os::processor_count() ;
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#ifdef ASSERT
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for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
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assert(cur->safepoint_state()->is_running(), "Illegal initial state");
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}
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#endif // ASSERT
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if (SafepointTimeout)
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safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
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// Iterate through all threads until it have been determined how to stop them all at a safepoint
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unsigned int iterations = 0;
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int steps = 0 ;
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while(still_running > 0) {
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for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
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assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
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ThreadSafepointState *cur_state = cur->safepoint_state();
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if (cur_state->is_running()) {
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cur_state->examine_state_of_thread();
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if (!cur_state->is_running()) {
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still_running--;
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// consider adjusting steps downward:
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// steps = 0
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// steps -= NNN
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// steps >>= 1
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// steps = MIN(steps, 2000-100)
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// if (iterations != 0) steps -= NNN
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}
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if (TraceSafepoint && Verbose) cur_state->print();
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}
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}
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if ( (PrintSafepointStatistics || (PrintSafepointStatisticsTimeout > 0))
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&& iterations == 0) {
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begin_statistics(nof_threads, still_running);
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}
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if (still_running > 0) {
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// Check for if it takes to long
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if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
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print_safepoint_timeout(_spinning_timeout);
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}
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// Spin to avoid context switching.
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// There's a tension between allowing the mutators to run (and rendezvous)
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// vs spinning. As the VM thread spins, wasting cycles, it consumes CPU that
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// a mutator might otherwise use profitably to reach a safepoint. Excessive
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// spinning by the VM thread on a saturated system can increase rendezvous latency.
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// Blocking or yielding incur their own penalties in the form of context switching
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// and the resultant loss of $ residency.
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//
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// Further complicating matters is that yield() does not work as naively expected
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// on many platforms -- yield() does not guarantee that any other ready threads
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// will run. As such we revert yield_all() after some number of iterations.
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// Yield_all() is implemented as a short unconditional sleep on some platforms.
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// Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
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// can actually increase the time it takes the VM thread to detect that a system-wide
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// stop-the-world safepoint has been reached. In a pathological scenario such as that
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// described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
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// In that case the mutators will be stalled waiting for the safepoint to complete and the
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// the VMthread will be sleeping, waiting for the mutators to rendezvous. The VMthread
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// will eventually wake up and detect that all mutators are safe, at which point
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// we'll again make progress.
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//
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// Beware too that that the VMThread typically runs at elevated priority.
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// Its default priority is higher than the default mutator priority.
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// Obviously, this complicates spinning.
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//
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// Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
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// Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
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//
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// See the comments in synchronizer.cpp for additional remarks on spinning.
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//
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// In the future we might:
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// 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
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// This is tricky as the path used by a thread exiting the JVM (say on
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// on JNI call-out) simply stores into its state field. The burden
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// is placed on the VM thread, which must poll (spin).
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// 2. Find something useful to do while spinning. If the safepoint is GC-related
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// we might aggressively scan the stacks of threads that are already safe.
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// 3. Use Solaris schedctl to examine the state of the still-running mutators.
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// If all the mutators are ONPROC there's no reason to sleep or yield.
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// 4. YieldTo() any still-running mutators that are ready but OFFPROC.
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// 5. Check system saturation. If the system is not fully saturated then
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// simply spin and avoid sleep/yield.
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// 6. As still-running mutators rendezvous they could unpark the sleeping
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// VMthread. This works well for still-running mutators that become
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// safe. The VMthread must still poll for mutators that call-out.
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// 7. Drive the policy on time-since-begin instead of iterations.
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// 8. Consider making the spin duration a function of the # of CPUs:
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// Spin = (((ncpus-1) * M) + K) + F(still_running)
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// Alternately, instead of counting iterations of the outer loop
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// we could count the # of threads visited in the inner loop, above.
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// 9. On windows consider using the return value from SwitchThreadTo()
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// to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
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if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
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guarantee (PageArmed == 0, "invariant") ;
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PageArmed = 1 ;
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os::make_polling_page_unreadable();
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}
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// Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
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// ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
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++steps ;
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if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
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SpinPause() ; // MP-Polite spin
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} else
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if (steps < DeferThrSuspendLoopCount) {
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os::NakedYield() ;
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} else {
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os::yield_all(steps) ;
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// Alternately, the VM thread could transiently depress its scheduling priority or
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// transiently increase the priority of the tardy mutator(s).
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}
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iterations ++ ;
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}
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assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
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}
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assert(still_running == 0, "sanity check");
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if (PrintSafepointStatistics) {
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update_statistics_on_spin_end();
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}
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// wait until all threads are stopped
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while (_waiting_to_block > 0) {
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if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
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if (!SafepointTimeout || timeout_error_printed) {
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Safepoint_lock->wait(true); // true, means with no safepoint checks
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} else {
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// Compute remaining time
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jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
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// If there is no remaining time, then there is an error
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if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
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print_safepoint_timeout(_blocking_timeout);
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}
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}
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}
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assert(_waiting_to_block == 0, "sanity check");
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#ifndef PRODUCT
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if (SafepointTimeout) {
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jlong current_time = os::javaTimeNanos();
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if (safepoint_limit_time < current_time) {
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tty->print_cr("# SafepointSynchronize: Finished after "
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INT64_FORMAT_W(6) " ms",
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((current_time - safepoint_limit_time) / MICROUNITS +
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SafepointTimeoutDelay));
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}
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}
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#endif
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assert((_safepoint_counter & 0x1) == 0, "must be even");
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assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
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_safepoint_counter ++;
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// Record state
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_state = _synchronized;
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OrderAccess::fence();
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if (TraceSafepoint) {
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VM_Operation *op = VMThread::vm_operation();
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tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
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}
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RuntimeService::record_safepoint_synchronized();
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if (PrintSafepointStatistics) {
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update_statistics_on_sync_end(os::javaTimeNanos());
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}
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// Call stuff that needs to be run when a safepoint is just about to be completed
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do_cleanup_tasks();
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}
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}
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// Wake up all threads, so they are ready to resume execution after the safepoint
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// operation has been carried out
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void SafepointSynchronize::end() {
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assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
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assert((_safepoint_counter & 0x1) == 1, "must be odd");
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_safepoint_counter ++;
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// memory fence isn't required here since an odd _safepoint_counter
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// value can do no harm and a fence is issued below anyway.
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DEBUG_ONLY(Thread* myThread = Thread::current();)
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assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
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if (PrintSafepointStatistics) {
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end_statistics(os::javaTimeNanos());
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}
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#ifdef ASSERT
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// A pending_exception cannot be installed during a safepoint. The threads
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// may install an async exception after they come back from a safepoint into
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// pending_exception after they unblock. But that should happen later.
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for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
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assert (!(cur->has_pending_exception() &&
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cur->safepoint_state()->is_at_poll_safepoint()),
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"safepoint installed a pending exception");
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}
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#endif // ASSERT
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if (PageArmed) {
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// Make polling safepoint aware
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os::make_polling_page_readable();
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PageArmed = 0 ;
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}
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// Remove safepoint check from interpreter
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Interpreter::ignore_safepoints();
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{
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MutexLocker mu(Safepoint_lock);
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assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
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// Set to not synchronized, so the threads will not go into the signal_thread_blocked method
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// when they get restarted.
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_state = _not_synchronized;
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OrderAccess::fence();
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if (TraceSafepoint) {
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tty->print_cr("Leaving safepoint region");
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}
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// Start suspended threads
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for(JavaThread *current = Threads::first(); current; current = current->next()) {
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// A problem occuring on Solaris is when attempting to restart threads
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// the first #cpus - 1 go well, but then the VMThread is preempted when we get
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// to the next one (since it has been running the longest). We then have
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// to wait for a cpu to become available before we can continue restarting
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// threads.
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// FIXME: This causes the performance of the VM to degrade when active and with
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// large numbers of threads. Apparently this is due to the synchronous nature
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// of suspending threads.
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//
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|
381 |
// TODO-FIXME: the comments above are vestigial and no longer apply.
|
|
382 |
// Furthermore, using solaris' schedctl in this particular context confers no benefit
|
|
383 |
if (VMThreadHintNoPreempt) {
|
|
384 |
os::hint_no_preempt();
|
|
385 |
}
|
|
386 |
ThreadSafepointState* cur_state = current->safepoint_state();
|
|
387 |
assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
|
|
388 |
cur_state->restart();
|
|
389 |
assert(cur_state->is_running(), "safepoint state has not been reset");
|
|
390 |
}
|
|
391 |
|
|
392 |
RuntimeService::record_safepoint_end();
|
|
393 |
|
|
394 |
// Release threads lock, so threads can be created/destroyed again. It will also starts all threads
|
|
395 |
// blocked in signal_thread_blocked
|
|
396 |
Threads_lock->unlock();
|
|
397 |
|
|
398 |
}
|
|
399 |
#ifndef SERIALGC
|
|
400 |
// If there are any concurrent GC threads resume them.
|
|
401 |
if (UseConcMarkSweepGC) {
|
|
402 |
ConcurrentMarkSweepThread::desynchronize(false);
|
|
403 |
} else {
|
|
404 |
ConcurrentGCThread::safepoint_desynchronize();
|
|
405 |
}
|
|
406 |
#endif // SERIALGC
|
|
407 |
}
|
|
408 |
|
|
409 |
bool SafepointSynchronize::is_cleanup_needed() {
|
|
410 |
// Need a safepoint if some inline cache buffers is non-empty
|
|
411 |
if (!InlineCacheBuffer::is_empty()) return true;
|
|
412 |
return false;
|
|
413 |
}
|
|
414 |
|
|
415 |
jlong CounterDecay::_last_timestamp = 0;
|
|
416 |
|
|
417 |
static void do_method(methodOop m) {
|
|
418 |
m->invocation_counter()->decay();
|
|
419 |
}
|
|
420 |
|
|
421 |
void CounterDecay::decay() {
|
|
422 |
_last_timestamp = os::javaTimeMillis();
|
|
423 |
|
|
424 |
// This operation is going to be performed only at the end of a safepoint
|
|
425 |
// and hence GC's will not be going on, all Java mutators are suspended
|
|
426 |
// at this point and hence SystemDictionary_lock is also not needed.
|
|
427 |
assert(SafepointSynchronize::is_at_safepoint(), "can only be executed at a safepoint");
|
|
428 |
int nclasses = SystemDictionary::number_of_classes();
|
|
429 |
double classes_per_tick = nclasses * (CounterDecayMinIntervalLength * 1e-3 /
|
|
430 |
CounterHalfLifeTime);
|
|
431 |
for (int i = 0; i < classes_per_tick; i++) {
|
|
432 |
klassOop k = SystemDictionary::try_get_next_class();
|
|
433 |
if (k != NULL && k->klass_part()->oop_is_instance()) {
|
|
434 |
instanceKlass::cast(k)->methods_do(do_method);
|
|
435 |
}
|
|
436 |
}
|
|
437 |
}
|
|
438 |
|
|
439 |
// Various cleaning tasks that should be done periodically at safepoints
|
|
440 |
void SafepointSynchronize::do_cleanup_tasks() {
|
|
441 |
jlong cleanup_time;
|
|
442 |
|
|
443 |
// Update fat-monitor pool, since this is a safepoint.
|
|
444 |
if (TraceSafepoint) {
|
|
445 |
cleanup_time = os::javaTimeNanos();
|
|
446 |
}
|
|
447 |
|
|
448 |
ObjectSynchronizer::deflate_idle_monitors();
|
|
449 |
InlineCacheBuffer::update_inline_caches();
|
|
450 |
if(UseCounterDecay && CounterDecay::is_decay_needed()) {
|
|
451 |
CounterDecay::decay();
|
|
452 |
}
|
|
453 |
NMethodSweeper::sweep();
|
|
454 |
|
|
455 |
if (TraceSafepoint) {
|
|
456 |
tty->print_cr("do_cleanup_tasks takes "INT64_FORMAT_W(6) "ms",
|
|
457 |
(os::javaTimeNanos() - cleanup_time) / MICROUNITS);
|
|
458 |
}
|
|
459 |
}
|
|
460 |
|
|
461 |
|
|
462 |
bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
|
|
463 |
switch(state) {
|
|
464 |
case _thread_in_native:
|
|
465 |
// native threads are safe if they have no java stack or have walkable stack
|
|
466 |
return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
|
|
467 |
|
|
468 |
// blocked threads should have already have walkable stack
|
|
469 |
case _thread_blocked:
|
|
470 |
assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
|
|
471 |
return true;
|
|
472 |
|
|
473 |
default:
|
|
474 |
return false;
|
|
475 |
}
|
|
476 |
}
|
|
477 |
|
|
478 |
|
|
479 |
// -------------------------------------------------------------------------------------------------------
|
|
480 |
// Implementation of Safepoint callback point
|
|
481 |
|
|
482 |
void SafepointSynchronize::block(JavaThread *thread) {
|
|
483 |
assert(thread != NULL, "thread must be set");
|
|
484 |
assert(thread->is_Java_thread(), "not a Java thread");
|
|
485 |
|
|
486 |
// Threads shouldn't block if they are in the middle of printing, but...
|
|
487 |
ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
|
|
488 |
|
|
489 |
// Only bail from the block() call if the thread is gone from the
|
|
490 |
// thread list; starting to exit should still block.
|
|
491 |
if (thread->is_terminated()) {
|
|
492 |
// block current thread if we come here from native code when VM is gone
|
|
493 |
thread->block_if_vm_exited();
|
|
494 |
|
|
495 |
// otherwise do nothing
|
|
496 |
return;
|
|
497 |
}
|
|
498 |
|
|
499 |
JavaThreadState state = thread->thread_state();
|
|
500 |
thread->frame_anchor()->make_walkable(thread);
|
|
501 |
|
|
502 |
// Check that we have a valid thread_state at this point
|
|
503 |
switch(state) {
|
|
504 |
case _thread_in_vm_trans:
|
|
505 |
case _thread_in_Java: // From compiled code
|
|
506 |
|
|
507 |
// We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
|
|
508 |
// we pretend we are still in the VM.
|
|
509 |
thread->set_thread_state(_thread_in_vm);
|
|
510 |
|
|
511 |
if (is_synchronizing()) {
|
|
512 |
Atomic::inc (&TryingToBlock) ;
|
|
513 |
}
|
|
514 |
|
|
515 |
// We will always be holding the Safepoint_lock when we are examine the state
|
|
516 |
// of a thread. Hence, the instructions between the Safepoint_lock->lock() and
|
|
517 |
// Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
|
|
518 |
Safepoint_lock->lock_without_safepoint_check();
|
|
519 |
if (is_synchronizing()) {
|
|
520 |
// Decrement the number of threads to wait for and signal vm thread
|
|
521 |
assert(_waiting_to_block > 0, "sanity check");
|
|
522 |
_waiting_to_block--;
|
|
523 |
thread->safepoint_state()->set_has_called_back(true);
|
|
524 |
|
|
525 |
// Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
|
|
526 |
if (_waiting_to_block == 0) {
|
|
527 |
Safepoint_lock->notify_all();
|
|
528 |
}
|
|
529 |
}
|
|
530 |
|
|
531 |
// We transition the thread to state _thread_blocked here, but
|
|
532 |
// we can't do our usual check for external suspension and then
|
|
533 |
// self-suspend after the lock_without_safepoint_check() call
|
|
534 |
// below because we are often called during transitions while
|
|
535 |
// we hold different locks. That would leave us suspended while
|
|
536 |
// holding a resource which results in deadlocks.
|
|
537 |
thread->set_thread_state(_thread_blocked);
|
|
538 |
Safepoint_lock->unlock();
|
|
539 |
|
|
540 |
// We now try to acquire the threads lock. Since this lock is hold by the VM thread during
|
|
541 |
// the entire safepoint, the threads will all line up here during the safepoint.
|
|
542 |
Threads_lock->lock_without_safepoint_check();
|
|
543 |
// restore original state. This is important if the thread comes from compiled code, so it
|
|
544 |
// will continue to execute with the _thread_in_Java state.
|
|
545 |
thread->set_thread_state(state);
|
|
546 |
Threads_lock->unlock();
|
|
547 |
break;
|
|
548 |
|
|
549 |
case _thread_in_native_trans:
|
|
550 |
case _thread_blocked_trans:
|
|
551 |
case _thread_new_trans:
|
|
552 |
if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
|
|
553 |
thread->print_thread_state();
|
|
554 |
fatal("Deadlock in safepoint code. "
|
|
555 |
"Should have called back to the VM before blocking.");
|
|
556 |
}
|
|
557 |
|
|
558 |
// We transition the thread to state _thread_blocked here, but
|
|
559 |
// we can't do our usual check for external suspension and then
|
|
560 |
// self-suspend after the lock_without_safepoint_check() call
|
|
561 |
// below because we are often called during transitions while
|
|
562 |
// we hold different locks. That would leave us suspended while
|
|
563 |
// holding a resource which results in deadlocks.
|
|
564 |
thread->set_thread_state(_thread_blocked);
|
|
565 |
|
|
566 |
// It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
|
|
567 |
// the safepoint code might still be waiting for it to block. We need to change the state here,
|
|
568 |
// so it can see that it is at a safepoint.
|
|
569 |
|
|
570 |
// Block until the safepoint operation is completed.
|
|
571 |
Threads_lock->lock_without_safepoint_check();
|
|
572 |
|
|
573 |
// Restore state
|
|
574 |
thread->set_thread_state(state);
|
|
575 |
|
|
576 |
Threads_lock->unlock();
|
|
577 |
break;
|
|
578 |
|
|
579 |
default:
|
|
580 |
fatal1("Illegal threadstate encountered: %d", state);
|
|
581 |
}
|
|
582 |
|
|
583 |
// Check for pending. async. exceptions or suspends - except if the
|
|
584 |
// thread was blocked inside the VM. has_special_runtime_exit_condition()
|
|
585 |
// is called last since it grabs a lock and we only want to do that when
|
|
586 |
// we must.
|
|
587 |
//
|
|
588 |
// Note: we never deliver an async exception at a polling point as the
|
|
589 |
// compiler may not have an exception handler for it. The polling
|
|
590 |
// code will notice the async and deoptimize and the exception will
|
|
591 |
// be delivered. (Polling at a return point is ok though). Sure is
|
|
592 |
// a lot of bother for a deprecated feature...
|
|
593 |
//
|
|
594 |
// We don't deliver an async exception if the thread state is
|
|
595 |
// _thread_in_native_trans so JNI functions won't be called with
|
|
596 |
// a surprising pending exception. If the thread state is going back to java,
|
|
597 |
// async exception is checked in check_special_condition_for_native_trans().
|
|
598 |
|
|
599 |
if (state != _thread_blocked_trans &&
|
|
600 |
state != _thread_in_vm_trans &&
|
|
601 |
thread->has_special_runtime_exit_condition()) {
|
|
602 |
thread->handle_special_runtime_exit_condition(
|
|
603 |
!thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
|
|
604 |
}
|
|
605 |
}
|
|
606 |
|
|
607 |
// ------------------------------------------------------------------------------------------------------
|
|
608 |
// Exception handlers
|
|
609 |
|
|
610 |
#ifndef PRODUCT
|
|
611 |
#ifdef _LP64
|
|
612 |
#define PTR_PAD ""
|
|
613 |
#else
|
|
614 |
#define PTR_PAD " "
|
|
615 |
#endif
|
|
616 |
|
|
617 |
static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
|
|
618 |
bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
|
|
619 |
tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
|
|
620 |
oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
|
|
621 |
newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
|
|
622 |
}
|
|
623 |
|
|
624 |
static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
|
|
625 |
bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
|
|
626 |
tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
|
|
627 |
oldptr, wasoop?"oop":" ", oldptr == newptr ? ' ' : '!',
|
|
628 |
newptr, is_oop?"oop":" ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":" "));
|
|
629 |
}
|
|
630 |
|
|
631 |
#ifdef SPARC
|
|
632 |
static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
|
|
633 |
#ifdef _LP64
|
|
634 |
tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
|
|
635 |
const int incr = 1; // Increment to skip a long, in units of intptr_t
|
|
636 |
#else
|
|
637 |
tty->print_cr("--------+--address-+------before-----------+-------after----------+");
|
|
638 |
const int incr = 2; // Increment to skip a long, in units of intptr_t
|
|
639 |
#endif
|
|
640 |
tty->print_cr("---SP---|");
|
|
641 |
for( int i=0; i<16; i++ ) {
|
|
642 |
tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
|
|
643 |
tty->print_cr("--------|");
|
|
644 |
for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
|
|
645 |
tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
|
|
646 |
tty->print(" pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
|
|
647 |
tty->print_cr("--------|");
|
|
648 |
tty->print(" G1 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
|
|
649 |
tty->print(" G3 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
|
|
650 |
tty->print(" G4 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
|
|
651 |
tty->print(" G5 |"PTR_FORMAT" ",new_sp); print_longs(*(jlong*)old_sp,*(jlong*)new_sp,was_oops[incr-1]); old_sp += incr; new_sp += incr; was_oops += incr;
|
|
652 |
tty->print_cr(" FSR |"PTR_FORMAT" "PTR64_FORMAT" "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
|
|
653 |
old_sp += incr; new_sp += incr; was_oops += incr;
|
|
654 |
// Skip the floats
|
|
655 |
tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
|
|
656 |
tty->print_cr("---FP---|");
|
|
657 |
old_sp += incr*32; new_sp += incr*32; was_oops += incr*32;
|
|
658 |
for( int i2=0; i2<16; i2++ ) {
|
|
659 |
tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
|
|
660 |
tty->print_cr("");
|
|
661 |
}
|
|
662 |
#endif // SPARC
|
|
663 |
#endif // PRODUCT
|
|
664 |
|
|
665 |
|
|
666 |
void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
|
|
667 |
assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
|
|
668 |
assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
|
|
669 |
assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
|
|
670 |
|
|
671 |
// Uncomment this to get some serious before/after printing of the
|
|
672 |
// Sparc safepoint-blob frame structure.
|
|
673 |
/*
|
|
674 |
intptr_t* sp = thread->last_Java_sp();
|
|
675 |
intptr_t stack_copy[150];
|
|
676 |
for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
|
|
677 |
bool was_oops[150];
|
|
678 |
for( int i=0; i<150; i++ )
|
|
679 |
was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
|
|
680 |
*/
|
|
681 |
|
|
682 |
if (ShowSafepointMsgs) {
|
|
683 |
tty->print("handle_polling_page_exception: ");
|
|
684 |
}
|
|
685 |
|
|
686 |
if (PrintSafepointStatistics) {
|
|
687 |
inc_page_trap_count();
|
|
688 |
}
|
|
689 |
|
|
690 |
ThreadSafepointState* state = thread->safepoint_state();
|
|
691 |
|
|
692 |
state->handle_polling_page_exception();
|
|
693 |
// print_me(sp,stack_copy,was_oops);
|
|
694 |
}
|
|
695 |
|
|
696 |
|
|
697 |
void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
|
|
698 |
if (!timeout_error_printed) {
|
|
699 |
timeout_error_printed = true;
|
|
700 |
// Print out the thread infor which didn't reach the safepoint for debugging
|
|
701 |
// purposes (useful when there are lots of threads in the debugger).
|
|
702 |
tty->print_cr("");
|
|
703 |
tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
|
|
704 |
if (reason == _spinning_timeout) {
|
|
705 |
tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
|
|
706 |
} else if (reason == _blocking_timeout) {
|
|
707 |
tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
|
|
708 |
}
|
|
709 |
|
|
710 |
tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
|
|
711 |
ThreadSafepointState *cur_state;
|
|
712 |
ResourceMark rm;
|
|
713 |
for(JavaThread *cur_thread = Threads::first(); cur_thread;
|
|
714 |
cur_thread = cur_thread->next()) {
|
|
715 |
cur_state = cur_thread->safepoint_state();
|
|
716 |
|
|
717 |
if (cur_thread->thread_state() != _thread_blocked &&
|
|
718 |
((reason == _spinning_timeout && cur_state->is_running()) ||
|
|
719 |
(reason == _blocking_timeout && !cur_state->has_called_back()))) {
|
|
720 |
tty->print("# ");
|
|
721 |
cur_thread->print();
|
|
722 |
tty->print_cr("");
|
|
723 |
}
|
|
724 |
}
|
|
725 |
tty->print_cr("# SafepointSynchronize::begin: (End of list)");
|
|
726 |
}
|
|
727 |
|
|
728 |
// To debug the long safepoint, specify both DieOnSafepointTimeout &
|
|
729 |
// ShowMessageBoxOnError.
|
|
730 |
if (DieOnSafepointTimeout) {
|
|
731 |
char msg[1024];
|
|
732 |
VM_Operation *op = VMThread::vm_operation();
|
|
733 |
sprintf(msg, "Safepoint sync time longer than %d ms detected when executing %s.",
|
|
734 |
SafepointTimeoutDelay,
|
|
735 |
op != NULL ? op->name() : "no vm operation");
|
|
736 |
fatal(msg);
|
|
737 |
}
|
|
738 |
}
|
|
739 |
|
|
740 |
|
|
741 |
// -------------------------------------------------------------------------------------------------------
|
|
742 |
// Implementation of ThreadSafepointState
|
|
743 |
|
|
744 |
ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
|
|
745 |
_thread = thread;
|
|
746 |
_type = _running;
|
|
747 |
_has_called_back = false;
|
|
748 |
_at_poll_safepoint = false;
|
|
749 |
}
|
|
750 |
|
|
751 |
void ThreadSafepointState::create(JavaThread *thread) {
|
|
752 |
ThreadSafepointState *state = new ThreadSafepointState(thread);
|
|
753 |
thread->set_safepoint_state(state);
|
|
754 |
}
|
|
755 |
|
|
756 |
void ThreadSafepointState::destroy(JavaThread *thread) {
|
|
757 |
if (thread->safepoint_state()) {
|
|
758 |
delete(thread->safepoint_state());
|
|
759 |
thread->set_safepoint_state(NULL);
|
|
760 |
}
|
|
761 |
}
|
|
762 |
|
|
763 |
void ThreadSafepointState::examine_state_of_thread() {
|
|
764 |
assert(is_running(), "better be running or just have hit safepoint poll");
|
|
765 |
|
|
766 |
JavaThreadState state = _thread->thread_state();
|
|
767 |
|
|
768 |
// Check for a thread that is suspended. Note that thread resume tries
|
|
769 |
// to grab the Threads_lock which we own here, so a thread cannot be
|
|
770 |
// resumed during safepoint synchronization.
|
|
771 |
|
|
772 |
// We check with locking because another thread that has not yet
|
|
773 |
// synchronized may be trying to suspend this one.
|
|
774 |
bool is_suspended = _thread->is_any_suspended_with_lock();
|
|
775 |
if (is_suspended) {
|
|
776 |
roll_forward(_at_safepoint);
|
|
777 |
return;
|
|
778 |
}
|
|
779 |
|
|
780 |
// Some JavaThread states have an initial safepoint state of
|
|
781 |
// running, but are actually at a safepoint. We will happily
|
|
782 |
// agree and update the safepoint state here.
|
|
783 |
if (SafepointSynchronize::safepoint_safe(_thread, state)) {
|
|
784 |
roll_forward(_at_safepoint);
|
|
785 |
return;
|
|
786 |
}
|
|
787 |
|
|
788 |
if (state == _thread_in_vm) {
|
|
789 |
roll_forward(_call_back);
|
|
790 |
return;
|
|
791 |
}
|
|
792 |
|
|
793 |
// All other thread states will continue to run until they
|
|
794 |
// transition and self-block in state _blocked
|
|
795 |
// Safepoint polling in compiled code causes the Java threads to do the same.
|
|
796 |
// Note: new threads may require a malloc so they must be allowed to finish
|
|
797 |
|
|
798 |
assert(is_running(), "examine_state_of_thread on non-running thread");
|
|
799 |
return;
|
|
800 |
}
|
|
801 |
|
|
802 |
// Returns true is thread could not be rolled forward at present position.
|
|
803 |
void ThreadSafepointState::roll_forward(suspend_type type) {
|
|
804 |
_type = type;
|
|
805 |
|
|
806 |
switch(_type) {
|
|
807 |
case _at_safepoint:
|
|
808 |
SafepointSynchronize::signal_thread_at_safepoint();
|
|
809 |
break;
|
|
810 |
|
|
811 |
case _call_back:
|
|
812 |
set_has_called_back(false);
|
|
813 |
break;
|
|
814 |
|
|
815 |
case _running:
|
|
816 |
default:
|
|
817 |
ShouldNotReachHere();
|
|
818 |
}
|
|
819 |
}
|
|
820 |
|
|
821 |
void ThreadSafepointState::restart() {
|
|
822 |
switch(type()) {
|
|
823 |
case _at_safepoint:
|
|
824 |
case _call_back:
|
|
825 |
break;
|
|
826 |
|
|
827 |
case _running:
|
|
828 |
default:
|
|
829 |
tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
|
|
830 |
_thread, _type);
|
|
831 |
_thread->print();
|
|
832 |
ShouldNotReachHere();
|
|
833 |
}
|
|
834 |
_type = _running;
|
|
835 |
set_has_called_back(false);
|
|
836 |
}
|
|
837 |
|
|
838 |
|
|
839 |
void ThreadSafepointState::print_on(outputStream *st) const {
|
|
840 |
const char *s;
|
|
841 |
|
|
842 |
switch(_type) {
|
|
843 |
case _running : s = "_running"; break;
|
|
844 |
case _at_safepoint : s = "_at_safepoint"; break;
|
|
845 |
case _call_back : s = "_call_back"; break;
|
|
846 |
default:
|
|
847 |
ShouldNotReachHere();
|
|
848 |
}
|
|
849 |
|
|
850 |
st->print_cr("Thread: " INTPTR_FORMAT
|
|
851 |
" [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
|
|
852 |
_thread, _thread->osthread()->thread_id(), s, _has_called_back,
|
|
853 |
_at_poll_safepoint);
|
|
854 |
|
|
855 |
_thread->print_thread_state_on(st);
|
|
856 |
}
|
|
857 |
|
|
858 |
|
|
859 |
// ---------------------------------------------------------------------------------------------------------------------
|
|
860 |
|
|
861 |
// Block the thread at the safepoint poll or poll return.
|
|
862 |
void ThreadSafepointState::handle_polling_page_exception() {
|
|
863 |
|
|
864 |
// Check state. block() will set thread state to thread_in_vm which will
|
|
865 |
// cause the safepoint state _type to become _call_back.
|
|
866 |
assert(type() == ThreadSafepointState::_running,
|
|
867 |
"polling page exception on thread not running state");
|
|
868 |
|
|
869 |
// Step 1: Find the nmethod from the return address
|
|
870 |
if (ShowSafepointMsgs && Verbose) {
|
|
871 |
tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
|
|
872 |
}
|
|
873 |
address real_return_addr = thread()->saved_exception_pc();
|
|
874 |
|
|
875 |
CodeBlob *cb = CodeCache::find_blob(real_return_addr);
|
|
876 |
assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
|
|
877 |
nmethod* nm = (nmethod*)cb;
|
|
878 |
|
|
879 |
// Find frame of caller
|
|
880 |
frame stub_fr = thread()->last_frame();
|
|
881 |
CodeBlob* stub_cb = stub_fr.cb();
|
|
882 |
assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
|
|
883 |
RegisterMap map(thread(), true);
|
|
884 |
frame caller_fr = stub_fr.sender(&map);
|
|
885 |
|
|
886 |
// Should only be poll_return or poll
|
|
887 |
assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
|
|
888 |
|
|
889 |
// This is a poll immediately before a return. The exception handling code
|
|
890 |
// has already had the effect of causing the return to occur, so the execution
|
|
891 |
// will continue immediately after the call. In addition, the oopmap at the
|
|
892 |
// return point does not mark the return value as an oop (if it is), so
|
|
893 |
// it needs a handle here to be updated.
|
|
894 |
if( nm->is_at_poll_return(real_return_addr) ) {
|
|
895 |
// See if return type is an oop.
|
|
896 |
bool return_oop = nm->method()->is_returning_oop();
|
|
897 |
Handle return_value;
|
|
898 |
if (return_oop) {
|
|
899 |
// The oop result has been saved on the stack together with all
|
|
900 |
// the other registers. In order to preserve it over GCs we need
|
|
901 |
// to keep it in a handle.
|
|
902 |
oop result = caller_fr.saved_oop_result(&map);
|
|
903 |
assert(result == NULL || result->is_oop(), "must be oop");
|
|
904 |
return_value = Handle(thread(), result);
|
|
905 |
assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
|
|
906 |
}
|
|
907 |
|
|
908 |
// Block the thread
|
|
909 |
SafepointSynchronize::block(thread());
|
|
910 |
|
|
911 |
// restore oop result, if any
|
|
912 |
if (return_oop) {
|
|
913 |
caller_fr.set_saved_oop_result(&map, return_value());
|
|
914 |
}
|
|
915 |
}
|
|
916 |
|
|
917 |
// This is a safepoint poll. Verify the return address and block.
|
|
918 |
else {
|
|
919 |
set_at_poll_safepoint(true);
|
|
920 |
|
|
921 |
// verify the blob built the "return address" correctly
|
|
922 |
assert(real_return_addr == caller_fr.pc(), "must match");
|
|
923 |
|
|
924 |
// Block the thread
|
|
925 |
SafepointSynchronize::block(thread());
|
|
926 |
set_at_poll_safepoint(false);
|
|
927 |
|
|
928 |
// If we have a pending async exception deoptimize the frame
|
|
929 |
// as otherwise we may never deliver it.
|
|
930 |
if (thread()->has_async_condition()) {
|
|
931 |
ThreadInVMfromJavaNoAsyncException __tiv(thread());
|
|
932 |
VM_DeoptimizeFrame deopt(thread(), caller_fr.id());
|
|
933 |
VMThread::execute(&deopt);
|
|
934 |
}
|
|
935 |
|
|
936 |
// If an exception has been installed we must check for a pending deoptimization
|
|
937 |
// Deoptimize frame if exception has been thrown.
|
|
938 |
|
|
939 |
if (thread()->has_pending_exception() ) {
|
|
940 |
RegisterMap map(thread(), true);
|
|
941 |
frame caller_fr = stub_fr.sender(&map);
|
|
942 |
if (caller_fr.is_deoptimized_frame()) {
|
|
943 |
// The exception patch will destroy registers that are still
|
|
944 |
// live and will be needed during deoptimization. Defer the
|
|
945 |
// Async exception should have defered the exception until the
|
|
946 |
// next safepoint which will be detected when we get into
|
|
947 |
// the interpreter so if we have an exception now things
|
|
948 |
// are messed up.
|
|
949 |
|
|
950 |
fatal("Exception installed and deoptimization is pending");
|
|
951 |
}
|
|
952 |
}
|
|
953 |
}
|
|
954 |
}
|
|
955 |
|
|
956 |
|
|
957 |
//
|
|
958 |
// Statistics & Instrumentations
|
|
959 |
//
|
|
960 |
SafepointSynchronize::SafepointStats* SafepointSynchronize::_safepoint_stats = NULL;
|
|
961 |
int SafepointSynchronize::_cur_stat_index = 0;
|
|
962 |
julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
|
|
963 |
julong SafepointSynchronize::_coalesced_vmop_count = 0;
|
|
964 |
jlong SafepointSynchronize::_max_sync_time = 0;
|
|
965 |
|
|
966 |
// last_safepoint_start_time records the start time of last safepoint.
|
|
967 |
static jlong last_safepoint_start_time = 0;
|
|
968 |
static jlong sync_end_time = 0;
|
|
969 |
static bool need_to_track_page_armed_status = false;
|
|
970 |
static bool init_done = false;
|
|
971 |
|
|
972 |
void SafepointSynchronize::deferred_initialize_stat() {
|
|
973 |
if (init_done) return;
|
|
974 |
|
|
975 |
if (PrintSafepointStatisticsCount <= 0) {
|
|
976 |
fatal("Wrong PrintSafepointStatisticsCount");
|
|
977 |
}
|
|
978 |
|
|
979 |
// If PrintSafepointStatisticsTimeout is specified, the statistics data will
|
|
980 |
// be printed right away, in which case, _safepoint_stats will regress to
|
|
981 |
// a single element array. Otherwise, it is a circular ring buffer with default
|
|
982 |
// size of PrintSafepointStatisticsCount.
|
|
983 |
int stats_array_size;
|
|
984 |
if (PrintSafepointStatisticsTimeout > 0) {
|
|
985 |
stats_array_size = 1;
|
|
986 |
PrintSafepointStatistics = true;
|
|
987 |
} else {
|
|
988 |
stats_array_size = PrintSafepointStatisticsCount;
|
|
989 |
}
|
|
990 |
_safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
|
|
991 |
* sizeof(SafepointStats));
|
|
992 |
guarantee(_safepoint_stats != NULL,
|
|
993 |
"not enough memory for safepoint instrumentation data");
|
|
994 |
|
|
995 |
if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
|
|
996 |
need_to_track_page_armed_status = true;
|
|
997 |
}
|
|
998 |
|
|
999 |
tty->print(" vmop_name "
|
|
1000 |
"[threads: total initially_running wait_to_block] ");
|
|
1001 |
tty->print("[time: spin block sync] "
|
|
1002 |
"[vmop_time time_elapsed] ");
|
|
1003 |
|
|
1004 |
// no page armed status printed out if it is always armed.
|
|
1005 |
if (need_to_track_page_armed_status) {
|
|
1006 |
tty->print("page_armed ");
|
|
1007 |
}
|
|
1008 |
|
|
1009 |
tty->print_cr("page_trap_count");
|
|
1010 |
|
|
1011 |
init_done = true;
|
|
1012 |
}
|
|
1013 |
|
|
1014 |
void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
|
|
1015 |
deferred_initialize_stat();
|
|
1016 |
|
|
1017 |
SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
1018 |
|
|
1019 |
VM_Operation *op = VMThread::vm_operation();
|
|
1020 |
spstat->_vmop_type = (op != NULL ? op->type() : -1);
|
|
1021 |
if (op != NULL) {
|
|
1022 |
_safepoint_reasons[spstat->_vmop_type]++;
|
|
1023 |
}
|
|
1024 |
|
|
1025 |
spstat->_nof_total_threads = nof_threads;
|
|
1026 |
spstat->_nof_initial_running_threads = nof_running;
|
|
1027 |
spstat->_nof_threads_hit_page_trap = 0;
|
|
1028 |
|
|
1029 |
// Records the start time of spinning. The real time spent on spinning
|
|
1030 |
// will be adjusted when spin is done. Same trick is applied for time
|
|
1031 |
// spent on waiting for threads to block.
|
|
1032 |
if (nof_running != 0) {
|
|
1033 |
spstat->_time_to_spin = os::javaTimeNanos();
|
|
1034 |
} else {
|
|
1035 |
spstat->_time_to_spin = 0;
|
|
1036 |
}
|
|
1037 |
|
|
1038 |
if (last_safepoint_start_time == 0) {
|
|
1039 |
spstat->_time_elapsed_since_last_safepoint = 0;
|
|
1040 |
} else {
|
|
1041 |
spstat->_time_elapsed_since_last_safepoint = _last_safepoint -
|
|
1042 |
last_safepoint_start_time;
|
|
1043 |
}
|
|
1044 |
last_safepoint_start_time = _last_safepoint;
|
|
1045 |
}
|
|
1046 |
|
|
1047 |
void SafepointSynchronize::update_statistics_on_spin_end() {
|
|
1048 |
SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
1049 |
|
|
1050 |
jlong cur_time = os::javaTimeNanos();
|
|
1051 |
|
|
1052 |
spstat->_nof_threads_wait_to_block = _waiting_to_block;
|
|
1053 |
if (spstat->_nof_initial_running_threads != 0) {
|
|
1054 |
spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
|
|
1055 |
}
|
|
1056 |
|
|
1057 |
if (need_to_track_page_armed_status) {
|
|
1058 |
spstat->_page_armed = (PageArmed == 1);
|
|
1059 |
}
|
|
1060 |
|
|
1061 |
// Records the start time of waiting for to block. Updated when block is done.
|
|
1062 |
if (_waiting_to_block != 0) {
|
|
1063 |
spstat->_time_to_wait_to_block = cur_time;
|
|
1064 |
} else {
|
|
1065 |
spstat->_time_to_wait_to_block = 0;
|
|
1066 |
}
|
|
1067 |
}
|
|
1068 |
|
|
1069 |
void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
|
|
1070 |
SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
1071 |
|
|
1072 |
if (spstat->_nof_threads_wait_to_block != 0) {
|
|
1073 |
spstat->_time_to_wait_to_block = end_time -
|
|
1074 |
spstat->_time_to_wait_to_block;
|
|
1075 |
}
|
|
1076 |
|
|
1077 |
// Records the end time of sync which will be used to calculate the total
|
|
1078 |
// vm operation time. Again, the real time spending in syncing will be deducted
|
|
1079 |
// from the start of the sync time later when end_statistics is called.
|
|
1080 |
spstat->_time_to_sync = end_time - _last_safepoint;
|
|
1081 |
if (spstat->_time_to_sync > _max_sync_time) {
|
|
1082 |
_max_sync_time = spstat->_time_to_sync;
|
|
1083 |
}
|
|
1084 |
sync_end_time = end_time;
|
|
1085 |
}
|
|
1086 |
|
|
1087 |
void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
|
|
1088 |
SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
1089 |
|
|
1090 |
// Update the vm operation time.
|
|
1091 |
spstat->_time_to_exec_vmop = vmop_end_time - sync_end_time;
|
|
1092 |
// Only the sync time longer than the specified
|
|
1093 |
// PrintSafepointStatisticsTimeout will be printed out right away.
|
|
1094 |
// By default, it is -1 meaning all samples will be put into the list.
|
|
1095 |
if ( PrintSafepointStatisticsTimeout > 0) {
|
|
1096 |
if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
|
|
1097 |
print_statistics();
|
|
1098 |
}
|
|
1099 |
} else {
|
|
1100 |
// The safepoint statistics will be printed out when the _safepoin_stats
|
|
1101 |
// array fills up.
|
|
1102 |
if (_cur_stat_index != PrintSafepointStatisticsCount - 1) {
|
|
1103 |
_cur_stat_index ++;
|
|
1104 |
} else {
|
|
1105 |
print_statistics();
|
|
1106 |
_cur_stat_index = 0;
|
|
1107 |
tty->print_cr("");
|
|
1108 |
}
|
|
1109 |
}
|
|
1110 |
}
|
|
1111 |
|
|
1112 |
void SafepointSynchronize::print_statistics() {
|
|
1113 |
int index;
|
|
1114 |
SafepointStats* sstats = _safepoint_stats;
|
|
1115 |
|
|
1116 |
for (index = 0; index <= _cur_stat_index; index++) {
|
|
1117 |
sstats = &_safepoint_stats[index];
|
|
1118 |
tty->print("%-28s ["
|
|
1119 |
INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
|
|
1120 |
"] ",
|
|
1121 |
sstats->_vmop_type == -1 ? "no vm operation" :
|
|
1122 |
VM_Operation::name(sstats->_vmop_type),
|
|
1123 |
sstats->_nof_total_threads,
|
|
1124 |
sstats->_nof_initial_running_threads,
|
|
1125 |
sstats->_nof_threads_wait_to_block);
|
|
1126 |
// "/ MICROUNITS " is to convert the unit from nanos to millis.
|
|
1127 |
tty->print(" ["
|
|
1128 |
INT64_FORMAT_W(6)INT64_FORMAT_W(6)INT64_FORMAT_W(6)
|
|
1129 |
"] "
|
|
1130 |
"["INT64_FORMAT_W(6)INT64_FORMAT_W(9) "] ",
|
|
1131 |
sstats->_time_to_spin / MICROUNITS,
|
|
1132 |
sstats->_time_to_wait_to_block / MICROUNITS,
|
|
1133 |
sstats->_time_to_sync / MICROUNITS,
|
|
1134 |
sstats->_time_to_exec_vmop / MICROUNITS,
|
|
1135 |
sstats->_time_elapsed_since_last_safepoint / MICROUNITS);
|
|
1136 |
|
|
1137 |
if (need_to_track_page_armed_status) {
|
|
1138 |
tty->print(INT32_FORMAT" ", sstats->_page_armed);
|
|
1139 |
}
|
|
1140 |
tty->print_cr(INT32_FORMAT" ", sstats->_nof_threads_hit_page_trap);
|
|
1141 |
}
|
|
1142 |
}
|
|
1143 |
|
|
1144 |
// This method will be called when VM exits. It will first call
|
|
1145 |
// print_statistics to print out the rest of the sampling. Then
|
|
1146 |
// it tries to summarize the sampling.
|
|
1147 |
void SafepointSynchronize::print_stat_on_exit() {
|
|
1148 |
if (_safepoint_stats == NULL) return;
|
|
1149 |
|
|
1150 |
SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
|
|
1151 |
|
|
1152 |
// During VM exit, end_statistics may not get called and in that
|
|
1153 |
// case, if the sync time is less than PrintSafepointStatisticsTimeout,
|
|
1154 |
// don't print it out.
|
|
1155 |
// Approximate the vm op time.
|
|
1156 |
_safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
|
|
1157 |
os::javaTimeNanos() - sync_end_time;
|
|
1158 |
|
|
1159 |
if ( PrintSafepointStatisticsTimeout < 0 ||
|
|
1160 |
spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
|
|
1161 |
print_statistics();
|
|
1162 |
}
|
|
1163 |
tty->print_cr("");
|
|
1164 |
|
|
1165 |
// Print out polling page sampling status.
|
|
1166 |
if (!need_to_track_page_armed_status) {
|
|
1167 |
if (UseCompilerSafepoints) {
|
|
1168 |
tty->print_cr("Polling page always armed");
|
|
1169 |
}
|
|
1170 |
} else {
|
|
1171 |
tty->print_cr("Defer polling page loop count = %d\n",
|
|
1172 |
DeferPollingPageLoopCount);
|
|
1173 |
}
|
|
1174 |
|
|
1175 |
for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
|
|
1176 |
if (_safepoint_reasons[index] != 0) {
|
|
1177 |
tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
|
|
1178 |
_safepoint_reasons[index]);
|
|
1179 |
}
|
|
1180 |
}
|
|
1181 |
|
|
1182 |
tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
|
|
1183 |
_coalesced_vmop_count);
|
|
1184 |
tty->print_cr("Maximum sync time "INT64_FORMAT_W(5)" ms",
|
|
1185 |
_max_sync_time / MICROUNITS);
|
|
1186 |
}
|
|
1187 |
|
|
1188 |
// ------------------------------------------------------------------------------------------------
|
|
1189 |
// Non-product code
|
|
1190 |
|
|
1191 |
#ifndef PRODUCT
|
|
1192 |
|
|
1193 |
void SafepointSynchronize::print_state() {
|
|
1194 |
if (_state == _not_synchronized) {
|
|
1195 |
tty->print_cr("not synchronized");
|
|
1196 |
} else if (_state == _synchronizing || _state == _synchronized) {
|
|
1197 |
tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
|
|
1198 |
"synchronized");
|
|
1199 |
|
|
1200 |
for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
|
|
1201 |
cur->safepoint_state()->print();
|
|
1202 |
}
|
|
1203 |
}
|
|
1204 |
}
|
|
1205 |
|
|
1206 |
void SafepointSynchronize::safepoint_msg(const char* format, ...) {
|
|
1207 |
if (ShowSafepointMsgs) {
|
|
1208 |
va_list ap;
|
|
1209 |
va_start(ap, format);
|
|
1210 |
tty->vprint_cr(format, ap);
|
|
1211 |
va_end(ap);
|
|
1212 |
}
|
|
1213 |
}
|
|
1214 |
|
|
1215 |
#endif // !PRODUCT
|