duke@435: /*
trims@2708:  * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "classfile/systemDictionary.hpp"
stefank@2314: #include "code/codeCache.hpp"
stefank@2314: #include "code/icBuffer.hpp"
stefank@2314: #include "code/nmethod.hpp"
stefank@2314: #include "code/pcDesc.hpp"
stefank@2314: #include "code/scopeDesc.hpp"
stefank@2314: #include "gc_interface/collectedHeap.hpp"
stefank@2314: #include "interpreter/interpreter.hpp"
stefank@2314: #include "memory/resourceArea.hpp"
stefank@2314: #include "memory/universe.inline.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
coleenp@2497: #include "oops/symbol.hpp"
stefank@2314: #include "runtime/compilationPolicy.hpp"
stefank@2314: #include "runtime/deoptimization.hpp"
stefank@2314: #include "runtime/frame.inline.hpp"
stefank@2314: #include "runtime/interfaceSupport.hpp"
stefank@2314: #include "runtime/mutexLocker.hpp"
stefank@2314: #include "runtime/osThread.hpp"
stefank@2314: #include "runtime/safepoint.hpp"
stefank@2314: #include "runtime/signature.hpp"
stefank@2314: #include "runtime/stubCodeGenerator.hpp"
stefank@2314: #include "runtime/stubRoutines.hpp"
stefank@2314: #include "runtime/sweeper.hpp"
stefank@2314: #include "runtime/synchronizer.hpp"
stefank@2314: #include "services/runtimeService.hpp"
stefank@2314: #include "utilities/events.hpp"
stefank@2314: #ifdef TARGET_ARCH_x86
stefank@2314: # include "nativeInst_x86.hpp"
stefank@2314: # include "vmreg_x86.inline.hpp"
stefank@2314: #endif
stefank@2314: #ifdef TARGET_ARCH_sparc
stefank@2314: # include "nativeInst_sparc.hpp"
stefank@2314: # include "vmreg_sparc.inline.hpp"
stefank@2314: #endif
stefank@2314: #ifdef TARGET_ARCH_zero
stefank@2314: # include "nativeInst_zero.hpp"
stefank@2314: # include "vmreg_zero.inline.hpp"
stefank@2314: #endif
bobv@2508: #ifdef TARGET_ARCH_arm
bobv@2508: # include "nativeInst_arm.hpp"
bobv@2508: # include "vmreg_arm.inline.hpp"
bobv@2508: #endif
bobv@2508: #ifdef TARGET_ARCH_ppc
bobv@2508: # include "nativeInst_ppc.hpp"
bobv@2508: # include "vmreg_ppc.inline.hpp"
bobv@2508: #endif
stefank@2314: #ifdef TARGET_OS_FAMILY_linux
stefank@2314: # include "thread_linux.inline.hpp"
stefank@2314: #endif
stefank@2314: #ifdef TARGET_OS_FAMILY_solaris
stefank@2314: # include "thread_solaris.inline.hpp"
stefank@2314: #endif
stefank@2314: #ifdef TARGET_OS_FAMILY_windows
stefank@2314: # include "thread_windows.inline.hpp"
stefank@2314: #endif
never@3156: #ifdef TARGET_OS_FAMILY_bsd
never@3156: # include "thread_bsd.inline.hpp"
never@3156: #endif
stefank@2314: #ifndef SERIALGC
stefank@2314: #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
stefank@2314: #include "gc_implementation/shared/concurrentGCThread.hpp"
stefank@2314: #endif
stefank@2314: #ifdef COMPILER1
stefank@2314: #include "c1/c1_globals.hpp"
stefank@2314: #endif
duke@435: 
duke@435: // --------------------------------------------------------------------------------------------------
duke@435: // Implementation of Safepoint begin/end
duke@435: 
duke@435: SafepointSynchronize::SynchronizeState volatile SafepointSynchronize::_state = SafepointSynchronize::_not_synchronized;
duke@435: volatile int  SafepointSynchronize::_waiting_to_block = 0;
duke@435: volatile int SafepointSynchronize::_safepoint_counter = 0;
xlu@1726: long  SafepointSynchronize::_end_of_last_safepoint = 0;
duke@435: static volatile int PageArmed = 0 ;        // safepoint polling page is RO|RW vs PROT_NONE
duke@435: static volatile int TryingToBlock = 0 ;    // proximate value -- for advisory use only
duke@435: static bool timeout_error_printed = false;
duke@435: 
duke@435: // Roll all threads forward to a safepoint and suspend them all
duke@435: void SafepointSynchronize::begin() {
duke@435: 
duke@435:   Thread* myThread = Thread::current();
duke@435:   assert(myThread->is_VM_thread(), "Only VM thread may execute a safepoint");
duke@435: 
xlu@1726:   if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@1726:     _safepoint_begin_time = os::javaTimeNanos();
xlu@1726:     _ts_of_current_safepoint = tty->time_stamp().seconds();
xlu@1726:   }
duke@435: 
duke@435: #ifndef SERIALGC
duke@435:   if (UseConcMarkSweepGC) {
duke@435:     // In the future we should investigate whether CMS can use the
duke@435:     // more-general mechanism below.  DLD (01/05).
duke@435:     ConcurrentMarkSweepThread::synchronize(false);
ysr@1280:   } else if (UseG1GC) {
duke@435:     ConcurrentGCThread::safepoint_synchronize();
duke@435:   }
duke@435: #endif // SERIALGC
duke@435: 
duke@435:   // By getting the Threads_lock, we assure that no threads are about to start or
duke@435:   // exit. It is released again in SafepointSynchronize::end().
duke@435:   Threads_lock->lock();
duke@435: 
duke@435:   assert( _state == _not_synchronized, "trying to safepoint synchronize with wrong state");
duke@435: 
duke@435:   int nof_threads = Threads::number_of_threads();
duke@435: 
duke@435:   if (TraceSafepoint) {
duke@435:     tty->print_cr("Safepoint synchronization initiated. (%d)", nof_threads);
duke@435:   }
duke@435: 
duke@435:   RuntimeService::record_safepoint_begin();
duke@435: 
duke@435:   {
duke@435:   MutexLocker mu(Safepoint_lock);
duke@435: 
duke@435:   // Set number of threads to wait for, before we initiate the callbacks
duke@435:   _waiting_to_block = nof_threads;
duke@435:   TryingToBlock     = 0 ;
duke@435:   int still_running = nof_threads;
duke@435: 
duke@435:   // Save the starting time, so that it can be compared to see if this has taken
duke@435:   // too long to complete.
duke@435:   jlong safepoint_limit_time;
duke@435:   timeout_error_printed = false;
duke@435: 
xlu@1438:   // PrintSafepointStatisticsTimeout can be specified separately. When
xlu@1438:   // specified, PrintSafepointStatistics will be set to true in
xlu@1438:   // deferred_initialize_stat method. The initialization has to be done
xlu@1438:   // early enough to avoid any races. See bug 6880029 for details.
xlu@1438:   if (PrintSafepointStatistics || PrintSafepointStatisticsTimeout > 0) {
xlu@1438:     deferred_initialize_stat();
xlu@1438:   }
xlu@1438: 
duke@435:   // Begin the process of bringing the system to a safepoint.
duke@435:   // Java threads can be in several different states and are
duke@435:   // stopped by different mechanisms:
duke@435:   //
duke@435:   //  1. Running interpreted
duke@435:   //     The interpeter dispatch table is changed to force it to
duke@435:   //     check for a safepoint condition between bytecodes.
duke@435:   //  2. Running in native code
duke@435:   //     When returning from the native code, a Java thread must check
duke@435:   //     the safepoint _state to see if we must block.  If the
duke@435:   //     VM thread sees a Java thread in native, it does
duke@435:   //     not wait for this thread to block.  The order of the memory
duke@435:   //     writes and reads of both the safepoint state and the Java
duke@435:   //     threads state is critical.  In order to guarantee that the
duke@435:   //     memory writes are serialized with respect to each other,
duke@435:   //     the VM thread issues a memory barrier instruction
duke@435:   //     (on MP systems).  In order to avoid the overhead of issuing
duke@435:   //     a memory barrier for each Java thread making native calls, each Java
duke@435:   //     thread performs a write to a single memory page after changing
duke@435:   //     the thread state.  The VM thread performs a sequence of
duke@435:   //     mprotect OS calls which forces all previous writes from all
duke@435:   //     Java threads to be serialized.  This is done in the
duke@435:   //     os::serialize_thread_states() call.  This has proven to be
duke@435:   //     much more efficient than executing a membar instruction
duke@435:   //     on every call to native code.
duke@435:   //  3. Running compiled Code
duke@435:   //     Compiled code reads a global (Safepoint Polling) page that
duke@435:   //     is set to fault if we are trying to get to a safepoint.
duke@435:   //  4. Blocked
duke@435:   //     A thread which is blocked will not be allowed to return from the
duke@435:   //     block condition until the safepoint operation is complete.
duke@435:   //  5. In VM or Transitioning between states
duke@435:   //     If a Java thread is currently running in the VM or transitioning
duke@435:   //     between states, the safepointing code will wait for the thread to
duke@435:   //     block itself when it attempts transitions to a new state.
duke@435:   //
duke@435:   _state            = _synchronizing;
duke@435:   OrderAccess::fence();
duke@435: 
duke@435:   // Flush all thread states to memory
duke@435:   if (!UseMembar) {
duke@435:     os::serialize_thread_states();
duke@435:   }
duke@435: 
duke@435:   // Make interpreter safepoint aware
duke@435:   Interpreter::notice_safepoints();
duke@435: 
duke@435:   if (UseCompilerSafepoints && DeferPollingPageLoopCount < 0) {
duke@435:     // Make polling safepoint aware
duke@435:     guarantee (PageArmed == 0, "invariant") ;
duke@435:     PageArmed = 1 ;
duke@435:     os::make_polling_page_unreadable();
duke@435:   }
duke@435: 
duke@435:   // Consider using active_processor_count() ... but that call is expensive.
duke@435:   int ncpus = os::processor_count() ;
duke@435: 
duke@435: #ifdef ASSERT
duke@435:   for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
duke@435:     assert(cur->safepoint_state()->is_running(), "Illegal initial state");
duke@435:   }
duke@435: #endif // ASSERT
duke@435: 
duke@435:   if (SafepointTimeout)
duke@435:     safepoint_limit_time = os::javaTimeNanos() + (jlong)SafepointTimeoutDelay * MICROUNITS;
duke@435: 
duke@435:   // Iterate through all threads until it have been determined how to stop them all at a safepoint
duke@435:   unsigned int iterations = 0;
duke@435:   int steps = 0 ;
duke@435:   while(still_running > 0) {
duke@435:     for (JavaThread *cur = Threads::first(); cur != NULL; cur = cur->next()) {
duke@435:       assert(!cur->is_ConcurrentGC_thread(), "A concurrent GC thread is unexpectly being suspended");
duke@435:       ThreadSafepointState *cur_state = cur->safepoint_state();
duke@435:       if (cur_state->is_running()) {
duke@435:         cur_state->examine_state_of_thread();
duke@435:         if (!cur_state->is_running()) {
duke@435:            still_running--;
duke@435:            // consider adjusting steps downward:
duke@435:            //   steps = 0
duke@435:            //   steps -= NNN
duke@435:            //   steps >>= 1
duke@435:            //   steps = MIN(steps, 2000-100)
duke@435:            //   if (iterations != 0) steps -= NNN
duke@435:         }
duke@435:         if (TraceSafepoint && Verbose) cur_state->print();
duke@435:       }
duke@435:     }
duke@435: 
xlu@1438:     if (PrintSafepointStatistics && iterations == 0) {
duke@435:       begin_statistics(nof_threads, still_running);
duke@435:     }
duke@435: 
duke@435:     if (still_running > 0) {
duke@435:       // Check for if it takes to long
duke@435:       if (SafepointTimeout && safepoint_limit_time < os::javaTimeNanos()) {
duke@435:         print_safepoint_timeout(_spinning_timeout);
duke@435:       }
duke@435: 
duke@435:       // Spin to avoid context switching.
duke@435:       // There's a tension between allowing the mutators to run (and rendezvous)
duke@435:       // vs spinning.  As the VM thread spins, wasting cycles, it consumes CPU that
duke@435:       // a mutator might otherwise use profitably to reach a safepoint.  Excessive
duke@435:       // spinning by the VM thread on a saturated system can increase rendezvous latency.
duke@435:       // Blocking or yielding incur their own penalties in the form of context switching
duke@435:       // and the resultant loss of $ residency.
duke@435:       //
duke@435:       // Further complicating matters is that yield() does not work as naively expected
duke@435:       // on many platforms -- yield() does not guarantee that any other ready threads
duke@435:       // will run.   As such we revert yield_all() after some number of iterations.
duke@435:       // Yield_all() is implemented as a short unconditional sleep on some platforms.
duke@435:       // Typical operating systems round a "short" sleep period up to 10 msecs, so sleeping
duke@435:       // can actually increase the time it takes the VM thread to detect that a system-wide
duke@435:       // stop-the-world safepoint has been reached.  In a pathological scenario such as that
duke@435:       // described in CR6415670 the VMthread may sleep just before the mutator(s) become safe.
duke@435:       // In that case the mutators will be stalled waiting for the safepoint to complete and the
duke@435:       // the VMthread will be sleeping, waiting for the mutators to rendezvous.  The VMthread
duke@435:       // will eventually wake up and detect that all mutators are safe, at which point
duke@435:       // we'll again make progress.
duke@435:       //
duke@435:       // Beware too that that the VMThread typically runs at elevated priority.
duke@435:       // Its default priority is higher than the default mutator priority.
duke@435:       // Obviously, this complicates spinning.
duke@435:       //
duke@435:       // Note too that on Windows XP SwitchThreadTo() has quite different behavior than Sleep(0).
duke@435:       // Sleep(0) will _not yield to lower priority threads, while SwitchThreadTo() will.
duke@435:       //
duke@435:       // See the comments in synchronizer.cpp for additional remarks on spinning.
duke@435:       //
duke@435:       // In the future we might:
duke@435:       // 1. Modify the safepoint scheme to avoid potentally unbounded spinning.
duke@435:       //    This is tricky as the path used by a thread exiting the JVM (say on
duke@435:       //    on JNI call-out) simply stores into its state field.  The burden
duke@435:       //    is placed on the VM thread, which must poll (spin).
duke@435:       // 2. Find something useful to do while spinning.  If the safepoint is GC-related
duke@435:       //    we might aggressively scan the stacks of threads that are already safe.
duke@435:       // 3. Use Solaris schedctl to examine the state of the still-running mutators.
duke@435:       //    If all the mutators are ONPROC there's no reason to sleep or yield.
duke@435:       // 4. YieldTo() any still-running mutators that are ready but OFFPROC.
duke@435:       // 5. Check system saturation.  If the system is not fully saturated then
duke@435:       //    simply spin and avoid sleep/yield.
duke@435:       // 6. As still-running mutators rendezvous they could unpark the sleeping
duke@435:       //    VMthread.  This works well for still-running mutators that become
duke@435:       //    safe.  The VMthread must still poll for mutators that call-out.
duke@435:       // 7. Drive the policy on time-since-begin instead of iterations.
duke@435:       // 8. Consider making the spin duration a function of the # of CPUs:
duke@435:       //    Spin = (((ncpus-1) * M) + K) + F(still_running)
duke@435:       //    Alternately, instead of counting iterations of the outer loop
duke@435:       //    we could count the # of threads visited in the inner loop, above.
duke@435:       // 9. On windows consider using the return value from SwitchThreadTo()
duke@435:       //    to drive subsequent spin/SwitchThreadTo()/Sleep(N) decisions.
duke@435: 
duke@435:       if (UseCompilerSafepoints && int(iterations) == DeferPollingPageLoopCount) {
duke@435:          guarantee (PageArmed == 0, "invariant") ;
duke@435:          PageArmed = 1 ;
duke@435:          os::make_polling_page_unreadable();
duke@435:       }
duke@435: 
duke@435:       // Instead of (ncpus > 1) consider either (still_running < (ncpus + EPSILON)) or
duke@435:       // ((still_running + _waiting_to_block - TryingToBlock)) < ncpus)
duke@435:       ++steps ;
duke@435:       if (ncpus > 1 && steps < SafepointSpinBeforeYield) {
duke@435:         SpinPause() ;     // MP-Polite spin
duke@435:       } else
duke@435:       if (steps < DeferThrSuspendLoopCount) {
duke@435:         os::NakedYield() ;
duke@435:       } else {
duke@435:         os::yield_all(steps) ;
duke@435:         // Alternately, the VM thread could transiently depress its scheduling priority or
duke@435:         // transiently increase the priority of the tardy mutator(s).
duke@435:       }
duke@435: 
duke@435:       iterations ++ ;
duke@435:     }
duke@435:     assert(iterations < (uint)max_jint, "We have been iterating in the safepoint loop too long");
duke@435:   }
duke@435:   assert(still_running == 0, "sanity check");
duke@435: 
duke@435:   if (PrintSafepointStatistics) {
duke@435:     update_statistics_on_spin_end();
duke@435:   }
duke@435: 
duke@435:   // wait until all threads are stopped
duke@435:   while (_waiting_to_block > 0) {
duke@435:     if (TraceSafepoint) tty->print_cr("Waiting for %d thread(s) to block", _waiting_to_block);
duke@435:     if (!SafepointTimeout || timeout_error_printed) {
duke@435:       Safepoint_lock->wait(true);  // true, means with no safepoint checks
duke@435:     } else {
duke@435:       // Compute remaining time
duke@435:       jlong remaining_time = safepoint_limit_time - os::javaTimeNanos();
duke@435: 
duke@435:       // If there is no remaining time, then there is an error
duke@435:       if (remaining_time < 0 || Safepoint_lock->wait(true, remaining_time / MICROUNITS)) {
duke@435:         print_safepoint_timeout(_blocking_timeout);
duke@435:       }
duke@435:     }
duke@435:   }
duke@435:   assert(_waiting_to_block == 0, "sanity check");
duke@435: 
duke@435: #ifndef PRODUCT
duke@435:   if (SafepointTimeout) {
duke@435:     jlong current_time = os::javaTimeNanos();
duke@435:     if (safepoint_limit_time < current_time) {
duke@435:       tty->print_cr("# SafepointSynchronize: Finished after "
duke@435:                     INT64_FORMAT_W(6) " ms",
duke@435:                     ((current_time - safepoint_limit_time) / MICROUNITS +
duke@435:                      SafepointTimeoutDelay));
duke@435:     }
duke@435:   }
duke@435: #endif
duke@435: 
duke@435:   assert((_safepoint_counter & 0x1) == 0, "must be even");
duke@435:   assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@435:   _safepoint_counter ++;
duke@435: 
duke@435:   // Record state
duke@435:   _state = _synchronized;
duke@435: 
duke@435:   OrderAccess::fence();
duke@435: 
duke@435:   if (TraceSafepoint) {
duke@435:     VM_Operation *op = VMThread::vm_operation();
duke@435:     tty->print_cr("Entering safepoint region: %s", (op != NULL) ? op->name() : "no vm operation");
duke@435:   }
duke@435: 
duke@435:   RuntimeService::record_safepoint_synchronized();
duke@435:   if (PrintSafepointStatistics) {
duke@435:     update_statistics_on_sync_end(os::javaTimeNanos());
duke@435:   }
duke@435: 
duke@435:   // Call stuff that needs to be run when a safepoint is just about to be completed
duke@435:   do_cleanup_tasks();
xlu@1726: 
xlu@1726:   if (PrintSafepointStatistics) {
xlu@1726:     // Record how much time spend on the above cleanup tasks
xlu@1726:     update_statistics_on_cleanup_end(os::javaTimeNanos());
xlu@1726:   }
duke@435:   }
duke@435: }
duke@435: 
duke@435: // Wake up all threads, so they are ready to resume execution after the safepoint
duke@435: // operation has been carried out
duke@435: void SafepointSynchronize::end() {
duke@435: 
duke@435:   assert(Threads_lock->owned_by_self(), "must hold Threads_lock");
duke@435:   assert((_safepoint_counter & 0x1) == 1, "must be odd");
duke@435:   _safepoint_counter ++;
duke@435:   // memory fence isn't required here since an odd _safepoint_counter
duke@435:   // value can do no harm and a fence is issued below anyway.
duke@435: 
duke@435:   DEBUG_ONLY(Thread* myThread = Thread::current();)
duke@435:   assert(myThread->is_VM_thread(), "Only VM thread can execute a safepoint");
duke@435: 
duke@435:   if (PrintSafepointStatistics) {
duke@435:     end_statistics(os::javaTimeNanos());
duke@435:   }
duke@435: 
duke@435: #ifdef ASSERT
duke@435:   // A pending_exception cannot be installed during a safepoint.  The threads
duke@435:   // may install an async exception after they come back from a safepoint into
duke@435:   // pending_exception after they unblock.  But that should happen later.
duke@435:   for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@435:     assert (!(cur->has_pending_exception() &&
duke@435:               cur->safepoint_state()->is_at_poll_safepoint()),
duke@435:             "safepoint installed a pending exception");
duke@435:   }
duke@435: #endif // ASSERT
duke@435: 
duke@435:   if (PageArmed) {
duke@435:     // Make polling safepoint aware
duke@435:     os::make_polling_page_readable();
duke@435:     PageArmed = 0 ;
duke@435:   }
duke@435: 
duke@435:   // Remove safepoint check from interpreter
duke@435:   Interpreter::ignore_safepoints();
duke@435: 
duke@435:   {
duke@435:     MutexLocker mu(Safepoint_lock);
duke@435: 
duke@435:     assert(_state == _synchronized, "must be synchronized before ending safepoint synchronization");
duke@435: 
duke@435:     // Set to not synchronized, so the threads will not go into the signal_thread_blocked method
duke@435:     // when they get restarted.
duke@435:     _state = _not_synchronized;
duke@435:     OrderAccess::fence();
duke@435: 
duke@435:     if (TraceSafepoint) {
duke@435:        tty->print_cr("Leaving safepoint region");
duke@435:     }
duke@435: 
duke@435:     // Start suspended threads
duke@435:     for(JavaThread *current = Threads::first(); current; current = current->next()) {
twisti@1040:       // A problem occurring on Solaris is when attempting to restart threads
duke@435:       // the first #cpus - 1 go well, but then the VMThread is preempted when we get
duke@435:       // to the next one (since it has been running the longest).  We then have
duke@435:       // to wait for a cpu to become available before we can continue restarting
duke@435:       // threads.
duke@435:       // FIXME: This causes the performance of the VM to degrade when active and with
duke@435:       // large numbers of threads.  Apparently this is due to the synchronous nature
duke@435:       // of suspending threads.
duke@435:       //
duke@435:       // TODO-FIXME: the comments above are vestigial and no longer apply.
duke@435:       // Furthermore, using solaris' schedctl in this particular context confers no benefit
duke@435:       if (VMThreadHintNoPreempt) {
duke@435:         os::hint_no_preempt();
duke@435:       }
duke@435:       ThreadSafepointState* cur_state = current->safepoint_state();
duke@435:       assert(cur_state->type() != ThreadSafepointState::_running, "Thread not suspended at safepoint");
duke@435:       cur_state->restart();
duke@435:       assert(cur_state->is_running(), "safepoint state has not been reset");
duke@435:     }
duke@435: 
duke@435:     RuntimeService::record_safepoint_end();
duke@435: 
duke@435:     // Release threads lock, so threads can be created/destroyed again. It will also starts all threads
duke@435:     // blocked in signal_thread_blocked
duke@435:     Threads_lock->unlock();
duke@435: 
duke@435:   }
duke@435: #ifndef SERIALGC
duke@435:   // If there are any concurrent GC threads resume them.
duke@435:   if (UseConcMarkSweepGC) {
duke@435:     ConcurrentMarkSweepThread::desynchronize(false);
ysr@1280:   } else if (UseG1GC) {
duke@435:     ConcurrentGCThread::safepoint_desynchronize();
duke@435:   }
duke@435: #endif // SERIALGC
xlu@1726:   // record this time so VMThread can keep track how much time has elasped
xlu@1726:   // since last safepoint.
xlu@1726:   _end_of_last_safepoint = os::javaTimeMillis();
duke@435: }
duke@435: 
duke@435: bool SafepointSynchronize::is_cleanup_needed() {
duke@435:   // Need a safepoint if some inline cache buffers is non-empty
duke@435:   if (!InlineCacheBuffer::is_empty()) return true;
duke@435:   return false;
duke@435: }
duke@435: 
duke@435: 
duke@435: 
duke@435: // Various cleaning tasks that should be done periodically at safepoints
duke@435: void SafepointSynchronize::do_cleanup_tasks() {
xlu@1726:   {
xlu@1756:     TraceTime t1("deflating idle monitors", TraceSafepointCleanupTime);
xlu@1726:     ObjectSynchronizer::deflate_idle_monitors();
duke@435:   }
duke@435: 
xlu@1726:   {
xlu@1756:     TraceTime t2("updating inline caches", TraceSafepointCleanupTime);
xlu@1726:     InlineCacheBuffer::update_inline_caches();
xlu@1726:   }
iveresov@2138:   {
iveresov@2138:     TraceTime t3("compilation policy safepoint handler", TraceSafepointCleanupTime);
iveresov@2138:     CompilationPolicy::policy()->do_safepoint_work();
duke@435:   }
xlu@1726: 
xlu@1756:   TraceTime t4("sweeping nmethods", TraceSafepointCleanupTime);
never@1893:   NMethodSweeper::scan_stacks();
minqi@2964: 
minqi@2964:   // rotate log files?
minqi@2964:   if (UseGCLogFileRotation) {
minqi@2964:     gclog_or_tty->rotate_log();
minqi@2964:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: bool SafepointSynchronize::safepoint_safe(JavaThread *thread, JavaThreadState state) {
duke@435:   switch(state) {
duke@435:   case _thread_in_native:
duke@435:     // native threads are safe if they have no java stack or have walkable stack
duke@435:     return !thread->has_last_Java_frame() || thread->frame_anchor()->walkable();
duke@435: 
duke@435:    // blocked threads should have already have walkable stack
duke@435:   case _thread_blocked:
duke@435:     assert(!thread->has_last_Java_frame() || thread->frame_anchor()->walkable(), "blocked and not walkable");
duke@435:     return true;
duke@435: 
duke@435:   default:
duke@435:     return false;
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // -------------------------------------------------------------------------------------------------------
duke@435: // Implementation of Safepoint callback point
duke@435: 
duke@435: void SafepointSynchronize::block(JavaThread *thread) {
duke@435:   assert(thread != NULL, "thread must be set");
duke@435:   assert(thread->is_Java_thread(), "not a Java thread");
duke@435: 
duke@435:   // Threads shouldn't block if they are in the middle of printing, but...
duke@435:   ttyLocker::break_tty_lock_for_safepoint(os::current_thread_id());
duke@435: 
duke@435:   // Only bail from the block() call if the thread is gone from the
duke@435:   // thread list; starting to exit should still block.
duke@435:   if (thread->is_terminated()) {
duke@435:      // block current thread if we come here from native code when VM is gone
duke@435:      thread->block_if_vm_exited();
duke@435: 
duke@435:      // otherwise do nothing
duke@435:      return;
duke@435:   }
duke@435: 
duke@435:   JavaThreadState state = thread->thread_state();
duke@435:   thread->frame_anchor()->make_walkable(thread);
duke@435: 
duke@435:   // Check that we have a valid thread_state at this point
duke@435:   switch(state) {
duke@435:     case _thread_in_vm_trans:
duke@435:     case _thread_in_Java:        // From compiled code
duke@435: 
duke@435:       // We are highly likely to block on the Safepoint_lock. In order to avoid blocking in this case,
duke@435:       // we pretend we are still in the VM.
duke@435:       thread->set_thread_state(_thread_in_vm);
duke@435: 
duke@435:       if (is_synchronizing()) {
duke@435:          Atomic::inc (&TryingToBlock) ;
duke@435:       }
duke@435: 
duke@435:       // We will always be holding the Safepoint_lock when we are examine the state
duke@435:       // of a thread. Hence, the instructions between the Safepoint_lock->lock() and
duke@435:       // Safepoint_lock->unlock() are happening atomic with regards to the safepoint code
duke@435:       Safepoint_lock->lock_without_safepoint_check();
duke@435:       if (is_synchronizing()) {
duke@435:         // Decrement the number of threads to wait for and signal vm thread
duke@435:         assert(_waiting_to_block > 0, "sanity check");
duke@435:         _waiting_to_block--;
duke@435:         thread->safepoint_state()->set_has_called_back(true);
duke@435: 
duke@435:         // Consider (_waiting_to_block < 2) to pipeline the wakeup of the VM thread
duke@435:         if (_waiting_to_block == 0) {
duke@435:           Safepoint_lock->notify_all();
duke@435:         }
duke@435:       }
duke@435: 
duke@435:       // We transition the thread to state _thread_blocked here, but
duke@435:       // we can't do our usual check for external suspension and then
duke@435:       // self-suspend after the lock_without_safepoint_check() call
duke@435:       // below because we are often called during transitions while
duke@435:       // we hold different locks. That would leave us suspended while
duke@435:       // holding a resource which results in deadlocks.
duke@435:       thread->set_thread_state(_thread_blocked);
duke@435:       Safepoint_lock->unlock();
duke@435: 
duke@435:       // We now try to acquire the threads lock. Since this lock is hold by the VM thread during
duke@435:       // the entire safepoint, the threads will all line up here during the safepoint.
duke@435:       Threads_lock->lock_without_safepoint_check();
duke@435:       // restore original state. This is important if the thread comes from compiled code, so it
duke@435:       // will continue to execute with the _thread_in_Java state.
duke@435:       thread->set_thread_state(state);
duke@435:       Threads_lock->unlock();
duke@435:       break;
duke@435: 
duke@435:     case _thread_in_native_trans:
duke@435:     case _thread_blocked_trans:
duke@435:     case _thread_new_trans:
duke@435:       if (thread->safepoint_state()->type() == ThreadSafepointState::_call_back) {
duke@435:         thread->print_thread_state();
duke@435:         fatal("Deadlock in safepoint code.  "
duke@435:               "Should have called back to the VM before blocking.");
duke@435:       }
duke@435: 
duke@435:       // We transition the thread to state _thread_blocked here, but
duke@435:       // we can't do our usual check for external suspension and then
duke@435:       // self-suspend after the lock_without_safepoint_check() call
duke@435:       // below because we are often called during transitions while
duke@435:       // we hold different locks. That would leave us suspended while
duke@435:       // holding a resource which results in deadlocks.
duke@435:       thread->set_thread_state(_thread_blocked);
duke@435: 
duke@435:       // It is not safe to suspend a thread if we discover it is in _thread_in_native_trans. Hence,
duke@435:       // the safepoint code might still be waiting for it to block. We need to change the state here,
duke@435:       // so it can see that it is at a safepoint.
duke@435: 
duke@435:       // Block until the safepoint operation is completed.
duke@435:       Threads_lock->lock_without_safepoint_check();
duke@435: 
duke@435:       // Restore state
duke@435:       thread->set_thread_state(state);
duke@435: 
duke@435:       Threads_lock->unlock();
duke@435:       break;
duke@435: 
duke@435:     default:
jcoomes@1845:      fatal(err_msg("Illegal threadstate encountered: %d", state));
duke@435:   }
duke@435: 
duke@435:   // Check for pending. async. exceptions or suspends - except if the
duke@435:   // thread was blocked inside the VM. has_special_runtime_exit_condition()
duke@435:   // is called last since it grabs a lock and we only want to do that when
duke@435:   // we must.
duke@435:   //
duke@435:   // Note: we never deliver an async exception at a polling point as the
duke@435:   // compiler may not have an exception handler for it. The polling
duke@435:   // code will notice the async and deoptimize and the exception will
duke@435:   // be delivered. (Polling at a return point is ok though). Sure is
duke@435:   // a lot of bother for a deprecated feature...
duke@435:   //
duke@435:   // We don't deliver an async exception if the thread state is
duke@435:   // _thread_in_native_trans so JNI functions won't be called with
duke@435:   // a surprising pending exception. If the thread state is going back to java,
duke@435:   // async exception is checked in check_special_condition_for_native_trans().
duke@435: 
duke@435:   if (state != _thread_blocked_trans &&
duke@435:       state != _thread_in_vm_trans &&
duke@435:       thread->has_special_runtime_exit_condition()) {
duke@435:     thread->handle_special_runtime_exit_condition(
duke@435:       !thread->is_at_poll_safepoint() && (state != _thread_in_native_trans));
duke@435:   }
duke@435: }
duke@435: 
duke@435: // ------------------------------------------------------------------------------------------------------
duke@435: // Exception handlers
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: #ifdef _LP64
duke@435: #define PTR_PAD ""
duke@435: #else
duke@435: #define PTR_PAD "        "
duke@435: #endif
duke@435: 
duke@435: static void print_ptrs(intptr_t oldptr, intptr_t newptr, bool wasoop) {
duke@435:   bool is_oop = newptr ? ((oop)newptr)->is_oop() : false;
duke@435:   tty->print_cr(PTR_FORMAT PTR_PAD " %s %c " PTR_FORMAT PTR_PAD " %s %s",
duke@435:                 oldptr, wasoop?"oop":"   ", oldptr == newptr ? ' ' : '!',
duke@435:                 newptr, is_oop?"oop":"   ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":"     "));
duke@435: }
duke@435: 
duke@435: static void print_longs(jlong oldptr, jlong newptr, bool wasoop) {
duke@435:   bool is_oop = newptr ? ((oop)(intptr_t)newptr)->is_oop() : false;
duke@435:   tty->print_cr(PTR64_FORMAT " %s %c " PTR64_FORMAT " %s %s",
duke@435:                 oldptr, wasoop?"oop":"   ", oldptr == newptr ? ' ' : '!',
duke@435:                 newptr, is_oop?"oop":"   ", (wasoop && !is_oop) ? "STALE" : ((wasoop==false&&is_oop==false&&oldptr !=newptr)?"STOMP":"     "));
duke@435: }
duke@435: 
duke@435: #ifdef SPARC
duke@435: static void print_me(intptr_t *new_sp, intptr_t *old_sp, bool *was_oops) {
duke@435: #ifdef _LP64
duke@435:   tty->print_cr("--------+------address-----+------before-----------+-------after----------+");
duke@435:   const int incr = 1;           // Increment to skip a long, in units of intptr_t
duke@435: #else
duke@435:   tty->print_cr("--------+--address-+------before-----------+-------after----------+");
duke@435:   const int incr = 2;           // Increment to skip a long, in units of intptr_t
duke@435: #endif
duke@435:   tty->print_cr("---SP---|");
duke@435:   for( int i=0; i<16; i++ ) {
duke@435:     tty->print("blob %c%d |"PTR_FORMAT" ","LO"[i>>3],i&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
duke@435:   tty->print_cr("--------|");
duke@435:   for( int i1=0; i1<frame::memory_parameter_word_sp_offset-16; i1++ ) {
duke@435:     tty->print("argv pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
duke@435:   tty->print("     pad|"PTR_FORMAT" ",new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++);
duke@435:   tty->print_cr("--------|");
duke@435:   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;
duke@435:   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;
duke@435:   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;
duke@435:   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;
duke@435:   tty->print_cr(" FSR    |"PTR_FORMAT" "PTR64_FORMAT"       "PTR64_FORMAT,new_sp,*(jlong*)old_sp,*(jlong*)new_sp);
duke@435:   old_sp += incr; new_sp += incr; was_oops += incr;
duke@435:   // Skip the floats
duke@435:   tty->print_cr("--Float-|"PTR_FORMAT,new_sp);
duke@435:   tty->print_cr("---FP---|");
duke@435:   old_sp += incr*32;  new_sp += incr*32;  was_oops += incr*32;
duke@435:   for( int i2=0; i2<16; i2++ ) {
duke@435:     tty->print("call %c%d |"PTR_FORMAT" ","LI"[i2>>3],i2&7,new_sp); print_ptrs(*old_sp++,*new_sp++,*was_oops++); }
duke@435:   tty->print_cr("");
duke@435: }
duke@435: #endif  // SPARC
duke@435: #endif  // PRODUCT
duke@435: 
duke@435: 
duke@435: void SafepointSynchronize::handle_polling_page_exception(JavaThread *thread) {
duke@435:   assert(thread->is_Java_thread(), "polling reference encountered by VM thread");
duke@435:   assert(thread->thread_state() == _thread_in_Java, "should come from Java code");
duke@435:   assert(SafepointSynchronize::is_synchronizing(), "polling encountered outside safepoint synchronization");
duke@435: 
duke@435:   // Uncomment this to get some serious before/after printing of the
duke@435:   // Sparc safepoint-blob frame structure.
duke@435:   /*
duke@435:   intptr_t* sp = thread->last_Java_sp();
duke@435:   intptr_t stack_copy[150];
duke@435:   for( int i=0; i<150; i++ ) stack_copy[i] = sp[i];
duke@435:   bool was_oops[150];
duke@435:   for( int i=0; i<150; i++ )
duke@435:     was_oops[i] = stack_copy[i] ? ((oop)stack_copy[i])->is_oop() : false;
duke@435:   */
duke@435: 
duke@435:   if (ShowSafepointMsgs) {
duke@435:     tty->print("handle_polling_page_exception: ");
duke@435:   }
duke@435: 
duke@435:   if (PrintSafepointStatistics) {
duke@435:     inc_page_trap_count();
duke@435:   }
duke@435: 
duke@435:   ThreadSafepointState* state = thread->safepoint_state();
duke@435: 
duke@435:   state->handle_polling_page_exception();
duke@435:   // print_me(sp,stack_copy,was_oops);
duke@435: }
duke@435: 
duke@435: 
duke@435: void SafepointSynchronize::print_safepoint_timeout(SafepointTimeoutReason reason) {
duke@435:   if (!timeout_error_printed) {
duke@435:     timeout_error_printed = true;
duke@435:     // Print out the thread infor which didn't reach the safepoint for debugging
duke@435:     // purposes (useful when there are lots of threads in the debugger).
duke@435:     tty->print_cr("");
duke@435:     tty->print_cr("# SafepointSynchronize::begin: Timeout detected:");
duke@435:     if (reason ==  _spinning_timeout) {
duke@435:       tty->print_cr("# SafepointSynchronize::begin: Timed out while spinning to reach a safepoint.");
duke@435:     } else if (reason == _blocking_timeout) {
duke@435:       tty->print_cr("# SafepointSynchronize::begin: Timed out while waiting for threads to stop.");
duke@435:     }
duke@435: 
duke@435:     tty->print_cr("# SafepointSynchronize::begin: Threads which did not reach the safepoint:");
duke@435:     ThreadSafepointState *cur_state;
duke@435:     ResourceMark rm;
duke@435:     for(JavaThread *cur_thread = Threads::first(); cur_thread;
duke@435:         cur_thread = cur_thread->next()) {
duke@435:       cur_state = cur_thread->safepoint_state();
duke@435: 
duke@435:       if (cur_thread->thread_state() != _thread_blocked &&
duke@435:           ((reason == _spinning_timeout && cur_state->is_running()) ||
duke@435:            (reason == _blocking_timeout && !cur_state->has_called_back()))) {
duke@435:         tty->print("# ");
duke@435:         cur_thread->print();
duke@435:         tty->print_cr("");
duke@435:       }
duke@435:     }
duke@435:     tty->print_cr("# SafepointSynchronize::begin: (End of list)");
duke@435:   }
duke@435: 
duke@435:   // To debug the long safepoint, specify both DieOnSafepointTimeout &
duke@435:   // ShowMessageBoxOnError.
duke@435:   if (DieOnSafepointTimeout) {
duke@435:     char msg[1024];
duke@435:     VM_Operation *op = VMThread::vm_operation();
xlu@948:     sprintf(msg, "Safepoint sync time longer than " INTX_FORMAT "ms detected when executing %s.",
duke@435:             SafepointTimeoutDelay,
duke@435:             op != NULL ? op->name() : "no vm operation");
duke@435:     fatal(msg);
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // -------------------------------------------------------------------------------------------------------
duke@435: // Implementation of ThreadSafepointState
duke@435: 
duke@435: ThreadSafepointState::ThreadSafepointState(JavaThread *thread) {
duke@435:   _thread = thread;
duke@435:   _type   = _running;
duke@435:   _has_called_back = false;
duke@435:   _at_poll_safepoint = false;
duke@435: }
duke@435: 
duke@435: void ThreadSafepointState::create(JavaThread *thread) {
duke@435:   ThreadSafepointState *state = new ThreadSafepointState(thread);
duke@435:   thread->set_safepoint_state(state);
duke@435: }
duke@435: 
duke@435: void ThreadSafepointState::destroy(JavaThread *thread) {
duke@435:   if (thread->safepoint_state()) {
duke@435:     delete(thread->safepoint_state());
duke@435:     thread->set_safepoint_state(NULL);
duke@435:   }
duke@435: }
duke@435: 
duke@435: void ThreadSafepointState::examine_state_of_thread() {
duke@435:   assert(is_running(), "better be running or just have hit safepoint poll");
duke@435: 
duke@435:   JavaThreadState state = _thread->thread_state();
duke@435: 
never@2082:   // Save the state at the start of safepoint processing.
never@2082:   _orig_thread_state = state;
never@2082: 
duke@435:   // Check for a thread that is suspended. Note that thread resume tries
duke@435:   // to grab the Threads_lock which we own here, so a thread cannot be
duke@435:   // resumed during safepoint synchronization.
duke@435: 
dcubed@1414:   // We check to see if this thread is suspended without locking to
dcubed@1414:   // avoid deadlocking with a third thread that is waiting for this
dcubed@1414:   // thread to be suspended. The third thread can notice the safepoint
dcubed@1414:   // that we're trying to start at the beginning of its SR_lock->wait()
dcubed@1414:   // call. If that happens, then the third thread will block on the
dcubed@1414:   // safepoint while still holding the underlying SR_lock. We won't be
dcubed@1414:   // able to get the SR_lock and we'll deadlock.
dcubed@1414:   //
dcubed@1414:   // We don't need to grab the SR_lock here for two reasons:
dcubed@1414:   // 1) The suspend flags are both volatile and are set with an
dcubed@1414:   //    Atomic::cmpxchg() call so we should see the suspended
dcubed@1414:   //    state right away.
dcubed@1414:   // 2) We're being called from the safepoint polling loop; if
dcubed@1414:   //    we don't see the suspended state on this iteration, then
dcubed@1414:   //    we'll come around again.
dcubed@1414:   //
dcubed@1414:   bool is_suspended = _thread->is_ext_suspended();
duke@435:   if (is_suspended) {
duke@435:     roll_forward(_at_safepoint);
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   // Some JavaThread states have an initial safepoint state of
duke@435:   // running, but are actually at a safepoint. We will happily
duke@435:   // agree and update the safepoint state here.
duke@435:   if (SafepointSynchronize::safepoint_safe(_thread, state)) {
duke@435:       roll_forward(_at_safepoint);
duke@435:       return;
duke@435:   }
duke@435: 
duke@435:   if (state == _thread_in_vm) {
duke@435:     roll_forward(_call_back);
duke@435:     return;
duke@435:   }
duke@435: 
duke@435:   // All other thread states will continue to run until they
duke@435:   // transition and self-block in state _blocked
duke@435:   // Safepoint polling in compiled code causes the Java threads to do the same.
duke@435:   // Note: new threads may require a malloc so they must be allowed to finish
duke@435: 
duke@435:   assert(is_running(), "examine_state_of_thread on non-running thread");
duke@435:   return;
duke@435: }
duke@435: 
duke@435: // Returns true is thread could not be rolled forward at present position.
duke@435: void ThreadSafepointState::roll_forward(suspend_type type) {
duke@435:   _type = type;
duke@435: 
duke@435:   switch(_type) {
duke@435:     case _at_safepoint:
duke@435:       SafepointSynchronize::signal_thread_at_safepoint();
duke@435:       break;
duke@435: 
duke@435:     case _call_back:
duke@435:       set_has_called_back(false);
duke@435:       break;
duke@435: 
duke@435:     case _running:
duke@435:     default:
duke@435:       ShouldNotReachHere();
duke@435:   }
duke@435: }
duke@435: 
duke@435: void ThreadSafepointState::restart() {
duke@435:   switch(type()) {
duke@435:     case _at_safepoint:
duke@435:     case _call_back:
duke@435:       break;
duke@435: 
duke@435:     case _running:
duke@435:     default:
duke@435:        tty->print_cr("restart thread "INTPTR_FORMAT" with state %d",
duke@435:                       _thread, _type);
duke@435:        _thread->print();
duke@435:       ShouldNotReachHere();
duke@435:   }
duke@435:   _type = _running;
duke@435:   set_has_called_back(false);
duke@435: }
duke@435: 
duke@435: 
duke@435: void ThreadSafepointState::print_on(outputStream *st) const {
duke@435:   const char *s;
duke@435: 
duke@435:   switch(_type) {
duke@435:     case _running                : s = "_running";              break;
duke@435:     case _at_safepoint           : s = "_at_safepoint";         break;
duke@435:     case _call_back              : s = "_call_back";            break;
duke@435:     default:
duke@435:       ShouldNotReachHere();
duke@435:   }
duke@435: 
duke@435:   st->print_cr("Thread: " INTPTR_FORMAT
duke@435:               "  [0x%2x] State: %s _has_called_back %d _at_poll_safepoint %d",
duke@435:                _thread, _thread->osthread()->thread_id(), s, _has_called_back,
duke@435:                _at_poll_safepoint);
duke@435: 
duke@435:   _thread->print_thread_state_on(st);
duke@435: }
duke@435: 
duke@435: 
duke@435: // ---------------------------------------------------------------------------------------------------------------------
duke@435: 
duke@435: // Block the thread at the safepoint poll or poll return.
duke@435: void ThreadSafepointState::handle_polling_page_exception() {
duke@435: 
duke@435:   // Check state.  block() will set thread state to thread_in_vm which will
duke@435:   // cause the safepoint state _type to become _call_back.
duke@435:   assert(type() == ThreadSafepointState::_running,
duke@435:          "polling page exception on thread not running state");
duke@435: 
duke@435:   // Step 1: Find the nmethod from the return address
duke@435:   if (ShowSafepointMsgs && Verbose) {
duke@435:     tty->print_cr("Polling page exception at " INTPTR_FORMAT, thread()->saved_exception_pc());
duke@435:   }
duke@435:   address real_return_addr = thread()->saved_exception_pc();
duke@435: 
duke@435:   CodeBlob *cb = CodeCache::find_blob(real_return_addr);
duke@435:   assert(cb != NULL && cb->is_nmethod(), "return address should be in nmethod");
duke@435:   nmethod* nm = (nmethod*)cb;
duke@435: 
duke@435:   // Find frame of caller
duke@435:   frame stub_fr = thread()->last_frame();
duke@435:   CodeBlob* stub_cb = stub_fr.cb();
duke@435:   assert(stub_cb->is_safepoint_stub(), "must be a safepoint stub");
duke@435:   RegisterMap map(thread(), true);
duke@435:   frame caller_fr = stub_fr.sender(&map);
duke@435: 
duke@435:   // Should only be poll_return or poll
duke@435:   assert( nm->is_at_poll_or_poll_return(real_return_addr), "should not be at call" );
duke@435: 
duke@435:   // This is a poll immediately before a return. The exception handling code
duke@435:   // has already had the effect of causing the return to occur, so the execution
duke@435:   // will continue immediately after the call. In addition, the oopmap at the
duke@435:   // return point does not mark the return value as an oop (if it is), so
duke@435:   // it needs a handle here to be updated.
duke@435:   if( nm->is_at_poll_return(real_return_addr) ) {
duke@435:     // See if return type is an oop.
duke@435:     bool return_oop = nm->method()->is_returning_oop();
duke@435:     Handle return_value;
duke@435:     if (return_oop) {
duke@435:       // The oop result has been saved on the stack together with all
duke@435:       // the other registers. In order to preserve it over GCs we need
duke@435:       // to keep it in a handle.
duke@435:       oop result = caller_fr.saved_oop_result(&map);
duke@435:       assert(result == NULL || result->is_oop(), "must be oop");
duke@435:       return_value = Handle(thread(), result);
duke@435:       assert(Universe::heap()->is_in_or_null(result), "must be heap pointer");
duke@435:     }
duke@435: 
duke@435:     // Block the thread
duke@435:     SafepointSynchronize::block(thread());
duke@435: 
duke@435:     // restore oop result, if any
duke@435:     if (return_oop) {
duke@435:       caller_fr.set_saved_oop_result(&map, return_value());
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   // This is a safepoint poll. Verify the return address and block.
duke@435:   else {
duke@435:     set_at_poll_safepoint(true);
duke@435: 
duke@435:     // verify the blob built the "return address" correctly
duke@435:     assert(real_return_addr == caller_fr.pc(), "must match");
duke@435: 
duke@435:     // Block the thread
duke@435:     SafepointSynchronize::block(thread());
duke@435:     set_at_poll_safepoint(false);
duke@435: 
duke@435:     // If we have a pending async exception deoptimize the frame
duke@435:     // as otherwise we may never deliver it.
duke@435:     if (thread()->has_async_condition()) {
duke@435:       ThreadInVMfromJavaNoAsyncException __tiv(thread());
never@2260:       Deoptimization::deoptimize_frame(thread(), caller_fr.id());
duke@435:     }
duke@435: 
duke@435:     // If an exception has been installed we must check for a pending deoptimization
duke@435:     // Deoptimize frame if exception has been thrown.
duke@435: 
duke@435:     if (thread()->has_pending_exception() ) {
duke@435:       RegisterMap map(thread(), true);
duke@435:       frame caller_fr = stub_fr.sender(&map);
duke@435:       if (caller_fr.is_deoptimized_frame()) {
duke@435:         // The exception patch will destroy registers that are still
duke@435:         // live and will be needed during deoptimization. Defer the
duke@435:         // Async exception should have defered the exception until the
duke@435:         // next safepoint which will be detected when we get into
duke@435:         // the interpreter so if we have an exception now things
duke@435:         // are messed up.
duke@435: 
duke@435:         fatal("Exception installed and deoptimization is pending");
duke@435:       }
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: //
duke@435: //                     Statistics & Instrumentations
duke@435: //
duke@435: SafepointSynchronize::SafepointStats*  SafepointSynchronize::_safepoint_stats = NULL;
xlu@1726: jlong  SafepointSynchronize::_safepoint_begin_time = 0;
duke@435: int    SafepointSynchronize::_cur_stat_index = 0;
duke@435: julong SafepointSynchronize::_safepoint_reasons[VM_Operation::VMOp_Terminating];
duke@435: julong SafepointSynchronize::_coalesced_vmop_count = 0;
duke@435: jlong  SafepointSynchronize::_max_sync_time = 0;
xlu@1726: jlong  SafepointSynchronize::_max_vmop_time = 0;
xlu@1726: float  SafepointSynchronize::_ts_of_current_safepoint = 0.0f;
duke@435: 
xlu@1726: static jlong  cleanup_end_time = 0;
duke@435: static bool   need_to_track_page_armed_status = false;
duke@435: static bool   init_done = false;
duke@435: 
xlu@1726: // Helper method to print the header.
xlu@1726: static void print_header() {
xlu@1726:   tty->print("         vmop                    "
xlu@1726:              "[threads: total initially_running wait_to_block]    ");
xlu@1726:   tty->print("[time: spin block sync cleanup vmop] ");
xlu@1726: 
xlu@1726:   // no page armed status printed out if it is always armed.
xlu@1726:   if (need_to_track_page_armed_status) {
xlu@1726:     tty->print("page_armed ");
xlu@1726:   }
xlu@1726: 
xlu@1726:   tty->print_cr("page_trap_count");
xlu@1726: }
xlu@1726: 
duke@435: void SafepointSynchronize::deferred_initialize_stat() {
duke@435:   if (init_done) return;
duke@435: 
duke@435:   if (PrintSafepointStatisticsCount <= 0) {
duke@435:     fatal("Wrong PrintSafepointStatisticsCount");
duke@435:   }
duke@435: 
duke@435:   // If PrintSafepointStatisticsTimeout is specified, the statistics data will
duke@435:   // be printed right away, in which case, _safepoint_stats will regress to
duke@435:   // a single element array. Otherwise, it is a circular ring buffer with default
duke@435:   // size of PrintSafepointStatisticsCount.
duke@435:   int stats_array_size;
duke@435:   if (PrintSafepointStatisticsTimeout > 0) {
duke@435:     stats_array_size = 1;
duke@435:     PrintSafepointStatistics = true;
duke@435:   } else {
duke@435:     stats_array_size = PrintSafepointStatisticsCount;
duke@435:   }
duke@435:   _safepoint_stats = (SafepointStats*)os::malloc(stats_array_size
duke@435:                                                  * sizeof(SafepointStats));
duke@435:   guarantee(_safepoint_stats != NULL,
duke@435:             "not enough memory for safepoint instrumentation data");
duke@435: 
duke@435:   if (UseCompilerSafepoints && DeferPollingPageLoopCount >= 0) {
duke@435:     need_to_track_page_armed_status = true;
duke@435:   }
duke@435:   init_done = true;
duke@435: }
duke@435: 
duke@435: void SafepointSynchronize::begin_statistics(int nof_threads, int nof_running) {
xlu@1438:   assert(init_done, "safepoint statistics array hasn't been initialized");
duke@435:   SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@435: 
xlu@1726:   spstat->_time_stamp = _ts_of_current_safepoint;
xlu@1726: 
duke@435:   VM_Operation *op = VMThread::vm_operation();
duke@435:   spstat->_vmop_type = (op != NULL ? op->type() : -1);
duke@435:   if (op != NULL) {
duke@435:     _safepoint_reasons[spstat->_vmop_type]++;
duke@435:   }
duke@435: 
duke@435:   spstat->_nof_total_threads = nof_threads;
duke@435:   spstat->_nof_initial_running_threads = nof_running;
duke@435:   spstat->_nof_threads_hit_page_trap = 0;
duke@435: 
duke@435:   // Records the start time of spinning. The real time spent on spinning
duke@435:   // will be adjusted when spin is done. Same trick is applied for time
duke@435:   // spent on waiting for threads to block.
duke@435:   if (nof_running != 0) {
duke@435:     spstat->_time_to_spin = os::javaTimeNanos();
duke@435:   }  else {
duke@435:     spstat->_time_to_spin = 0;
duke@435:   }
duke@435: }
duke@435: 
duke@435: void SafepointSynchronize::update_statistics_on_spin_end() {
duke@435:   SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@435: 
duke@435:   jlong cur_time = os::javaTimeNanos();
duke@435: 
duke@435:   spstat->_nof_threads_wait_to_block = _waiting_to_block;
duke@435:   if (spstat->_nof_initial_running_threads != 0) {
duke@435:     spstat->_time_to_spin = cur_time - spstat->_time_to_spin;
duke@435:   }
duke@435: 
duke@435:   if (need_to_track_page_armed_status) {
duke@435:     spstat->_page_armed = (PageArmed == 1);
duke@435:   }
duke@435: 
duke@435:   // Records the start time of waiting for to block. Updated when block is done.
duke@435:   if (_waiting_to_block != 0) {
duke@435:     spstat->_time_to_wait_to_block = cur_time;
duke@435:   } else {
duke@435:     spstat->_time_to_wait_to_block = 0;
duke@435:   }
duke@435: }
duke@435: 
duke@435: void SafepointSynchronize::update_statistics_on_sync_end(jlong end_time) {
duke@435:   SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@435: 
duke@435:   if (spstat->_nof_threads_wait_to_block != 0) {
duke@435:     spstat->_time_to_wait_to_block = end_time -
duke@435:       spstat->_time_to_wait_to_block;
duke@435:   }
duke@435: 
duke@435:   // Records the end time of sync which will be used to calculate the total
duke@435:   // vm operation time. Again, the real time spending in syncing will be deducted
duke@435:   // from the start of the sync time later when end_statistics is called.
xlu@1726:   spstat->_time_to_sync = end_time - _safepoint_begin_time;
duke@435:   if (spstat->_time_to_sync > _max_sync_time) {
duke@435:     _max_sync_time = spstat->_time_to_sync;
duke@435:   }
xlu@1726: 
xlu@1726:   spstat->_time_to_do_cleanups = end_time;
xlu@1726: }
xlu@1726: 
xlu@1726: void SafepointSynchronize::update_statistics_on_cleanup_end(jlong end_time) {
xlu@1726:   SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
xlu@1726: 
xlu@1726:   // Record how long spent in cleanup tasks.
xlu@1726:   spstat->_time_to_do_cleanups = end_time - spstat->_time_to_do_cleanups;
xlu@1726: 
xlu@1726:   cleanup_end_time = end_time;
duke@435: }
duke@435: 
duke@435: void SafepointSynchronize::end_statistics(jlong vmop_end_time) {
duke@435:   SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@435: 
duke@435:   // Update the vm operation time.
xlu@1726:   spstat->_time_to_exec_vmop = vmop_end_time -  cleanup_end_time;
xlu@1726:   if (spstat->_time_to_exec_vmop > _max_vmop_time) {
xlu@1726:     _max_vmop_time = spstat->_time_to_exec_vmop;
xlu@1726:   }
duke@435:   // Only the sync time longer than the specified
duke@435:   // PrintSafepointStatisticsTimeout will be printed out right away.
duke@435:   // By default, it is -1 meaning all samples will be put into the list.
duke@435:   if ( PrintSafepointStatisticsTimeout > 0) {
duke@435:     if (spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@435:       print_statistics();
duke@435:     }
duke@435:   } else {
duke@435:     // The safepoint statistics will be printed out when the _safepoin_stats
duke@435:     // array fills up.
xlu@1726:     if (_cur_stat_index == PrintSafepointStatisticsCount - 1) {
duke@435:       print_statistics();
duke@435:       _cur_stat_index = 0;
xlu@1726:     } else {
xlu@1726:       _cur_stat_index++;
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: void SafepointSynchronize::print_statistics() {
duke@435:   SafepointStats* sstats = _safepoint_stats;
duke@435: 
xlu@1726:   for (int index = 0; index <= _cur_stat_index; index++) {
xlu@1726:     if (index % 30 == 0) {
xlu@1726:       print_header();
xlu@1726:     }
duke@435:     sstats = &_safepoint_stats[index];
xlu@1726:     tty->print("%.3f: ", sstats->_time_stamp);
xlu@1726:     tty->print("%-26s       ["
duke@435:                INT32_FORMAT_W(8)INT32_FORMAT_W(11)INT32_FORMAT_W(15)
xlu@1726:                "    ]    ",
duke@435:                sstats->_vmop_type == -1 ? "no vm operation" :
duke@435:                VM_Operation::name(sstats->_vmop_type),
duke@435:                sstats->_nof_total_threads,
duke@435:                sstats->_nof_initial_running_threads,
duke@435:                sstats->_nof_threads_wait_to_block);
duke@435:     // "/ MICROUNITS " is to convert the unit from nanos to millis.
xlu@1726:     tty->print("  ["
xlu@1726:                INT64_FORMAT_W(6)INT64_FORMAT_W(6)
xlu@1726:                INT64_FORMAT_W(6)INT64_FORMAT_W(6)
xlu@1726:                INT64_FORMAT_W(6)"    ]  ",
duke@435:                sstats->_time_to_spin / MICROUNITS,
duke@435:                sstats->_time_to_wait_to_block / MICROUNITS,
duke@435:                sstats->_time_to_sync / MICROUNITS,
xlu@1726:                sstats->_time_to_do_cleanups / MICROUNITS,
xlu@1726:                sstats->_time_to_exec_vmop / MICROUNITS);
duke@435: 
duke@435:     if (need_to_track_page_armed_status) {
duke@435:       tty->print(INT32_FORMAT"         ", sstats->_page_armed);
duke@435:     }
duke@435:     tty->print_cr(INT32_FORMAT"   ", sstats->_nof_threads_hit_page_trap);
duke@435:   }
duke@435: }
duke@435: 
duke@435: // This method will be called when VM exits. It will first call
duke@435: // print_statistics to print out the rest of the sampling.  Then
duke@435: // it tries to summarize the sampling.
duke@435: void SafepointSynchronize::print_stat_on_exit() {
duke@435:   if (_safepoint_stats == NULL) return;
duke@435: 
duke@435:   SafepointStats *spstat = &_safepoint_stats[_cur_stat_index];
duke@435: 
duke@435:   // During VM exit, end_statistics may not get called and in that
duke@435:   // case, if the sync time is less than PrintSafepointStatisticsTimeout,
duke@435:   // don't print it out.
duke@435:   // Approximate the vm op time.
duke@435:   _safepoint_stats[_cur_stat_index]._time_to_exec_vmop =
xlu@1726:     os::javaTimeNanos() - cleanup_end_time;
duke@435: 
duke@435:   if ( PrintSafepointStatisticsTimeout < 0 ||
duke@435:        spstat->_time_to_sync > PrintSafepointStatisticsTimeout * MICROUNITS) {
duke@435:     print_statistics();
duke@435:   }
duke@435:   tty->print_cr("");
duke@435: 
duke@435:   // Print out polling page sampling status.
duke@435:   if (!need_to_track_page_armed_status) {
duke@435:     if (UseCompilerSafepoints) {
duke@435:       tty->print_cr("Polling page always armed");
duke@435:     }
duke@435:   } else {
duke@435:     tty->print_cr("Defer polling page loop count = %d\n",
duke@435:                  DeferPollingPageLoopCount);
duke@435:   }
duke@435: 
duke@435:   for (int index = 0; index < VM_Operation::VMOp_Terminating; index++) {
duke@435:     if (_safepoint_reasons[index] != 0) {
duke@435:       tty->print_cr("%-26s"UINT64_FORMAT_W(10), VM_Operation::name(index),
duke@435:                     _safepoint_reasons[index]);
duke@435:     }
duke@435:   }
duke@435: 
duke@435:   tty->print_cr(UINT64_FORMAT_W(5)" VM operations coalesced during safepoint",
duke@435:                 _coalesced_vmop_count);
duke@435:   tty->print_cr("Maximum sync time  "INT64_FORMAT_W(5)" ms",
duke@435:                 _max_sync_time / MICROUNITS);
xlu@1726:   tty->print_cr("Maximum vm operation time (except for Exit VM operation)  "
xlu@1726:                 INT64_FORMAT_W(5)" ms",
xlu@1726:                 _max_vmop_time / MICROUNITS);
duke@435: }
duke@435: 
duke@435: // ------------------------------------------------------------------------------------------------
duke@435: // Non-product code
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: 
duke@435: void SafepointSynchronize::print_state() {
duke@435:   if (_state == _not_synchronized) {
duke@435:     tty->print_cr("not synchronized");
duke@435:   } else if (_state == _synchronizing || _state == _synchronized) {
duke@435:     tty->print_cr("State: %s", (_state == _synchronizing) ? "synchronizing" :
duke@435:                   "synchronized");
duke@435: 
duke@435:     for(JavaThread *cur = Threads::first(); cur; cur = cur->next()) {
duke@435:        cur->safepoint_state()->print();
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: void SafepointSynchronize::safepoint_msg(const char* format, ...) {
duke@435:   if (ShowSafepointMsgs) {
duke@435:     va_list ap;
duke@435:     va_start(ap, format);
duke@435:     tty->vprint_cr(format, ap);
duke@435:     va_end(ap);
duke@435:   }
duke@435: }
duke@435: 
duke@435: #endif // !PRODUCT