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src/hotspot/share/runtime/synchronizer.cpp
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rev 54109 : Add logging to ObjectSynchronizer::omFlush(), add global count logging at Info level to ObjectSynchronizer::finish_deflate_idle_monitors(); for monitorinflation logging, switch from cumulative "deflating per-thread idle monitors" mesgs to per-thread "deflating per-thread idle monitors" mesgs; fix timer bug in deflate_thread_local_monitors() where time to acquire gListLock wasn't counted; fix misc typos.
rev 54110 : Checkpoint latest preliminary review patches for full OpenJDK review.
*** 122,131 ****
--- 122,133 ----
// global monitor in-use list, for moribund threads,
// monitors they inflated need to be scanned for deflation
ObjectMonitor * volatile ObjectSynchronizer::gOmInUseList = NULL;
// count of entries in gOmInUseList
int ObjectSynchronizer::gOmInUseCount = 0;
+ bool ObjectSynchronizer::_gOmShouldDeflateIdleMonitors = false;
+ bool volatile ObjectSynchronizer::_is_cleanup_requested = false;
static volatile intptr_t gListLock = 0; // protects global monitor lists
static volatile int gMonitorFreeCount = 0; // # on gFreeList
static volatile int gMonitorPopulation = 0; // # Extant -- in circulation
*** 208,221 ****
assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
assert(Self->is_Java_thread(), "invariant");
assert(((JavaThread *) Self)->thread_state() == _thread_in_Java, "invariant");
NoSafepointVerifier nsv;
if (obj == NULL) return false; // Need to throw NPE
const markOop mark = obj->mark();
if (mark->has_monitor()) {
! ObjectMonitor * const m = mark->monitor();
assert(oopDesc::equals((oop) m->object(), obj), "invariant");
Thread * const owner = (Thread *) m->_owner;
// Lock contention and Transactional Lock Elision (TLE) diagnostics
// and observability
--- 210,231 ----
assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
assert(Self->is_Java_thread(), "invariant");
assert(((JavaThread *) Self)->thread_state() == _thread_in_Java, "invariant");
NoSafepointVerifier nsv;
if (obj == NULL) return false; // Need to throw NPE
+
+ while (true) {
const markOop mark = obj->mark();
if (mark->has_monitor()) {
! ObjectMonitorHandle omh;
! if (!omh.save_om_ptr(obj, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! continue;
! }
! ObjectMonitor * const m = omh.om_ptr();
assert(oopDesc::equals((oop) m->object(), obj), "invariant");
Thread * const owner = (Thread *) m->_owner;
// Lock contention and Transactional Lock Elision (TLE) diagnostics
// and observability
*** 243,252 ****
--- 253,264 ----
assert(m->_recursions == 0, "invariant");
assert(m->_owner == Self, "invariant");
return true;
}
}
+ break;
+ }
// Note that we could inflate in quick_enter.
// This is likely a useful optimization
// Critically, in quick_enter() we must not:
// -- perform bias revocation, or
*** 325,343 ****
return;
}
}
// We have to take the slow-path of possible inflation and then exit.
! inflate(THREAD, object, inflate_cause_vm_internal)->exit(true, THREAD);
}
// -----------------------------------------------------------------------------
// Interpreter/Compiler Slow Case
// This routine is used to handle interpreter/compiler slow case
// We don't need to use fast path here, because it must have been
// failed in the interpreter/compiler code.
void ObjectSynchronizer::slow_enter(Handle obj, BasicLock* lock, TRAPS) {
markOop mark = obj->mark();
assert(!mark->has_bias_pattern(), "should not see bias pattern here");
if (mark->is_neutral()) {
// Anticipate successful CAS -- the ST of the displaced mark must
--- 337,359 ----
return;
}
}
// We have to take the slow-path of possible inflation and then exit.
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, object, inflate_cause_vm_internal);
! omh.om_ptr()->exit(true, THREAD);
}
// -----------------------------------------------------------------------------
// Interpreter/Compiler Slow Case
// This routine is used to handle interpreter/compiler slow case
// We don't need to use fast path here, because it must have been
// failed in the interpreter/compiler code.
void ObjectSynchronizer::slow_enter(Handle obj, BasicLock* lock, TRAPS) {
+ bool do_loop = true;
+ while (do_loop) {
markOop mark = obj->mark();
assert(!mark->has_bias_pattern(), "should not see bias pattern here");
if (mark->is_neutral()) {
// Anticipate successful CAS -- the ST of the displaced mark must
*** 358,368 ****
// The object header will never be displaced to this lock,
// so it does not matter what the value is, except that it
// must be non-zero to avoid looking like a re-entrant lock,
// and must not look locked either.
lock->set_displaced_header(markOopDesc::unused_mark());
! inflate(THREAD, obj(), inflate_cause_monitor_enter)->enter(THREAD);
}
// This routine is used to handle interpreter/compiler slow case
// We don't need to use fast path here, because it must have
// failed in the interpreter/compiler code. Simply use the heavy
--- 374,387 ----
// The object header will never be displaced to this lock,
// so it does not matter what the value is, except that it
// must be non-zero to avoid looking like a re-entrant lock,
// and must not look locked either.
lock->set_displaced_header(markOopDesc::unused_mark());
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_monitor_enter);
! do_loop = !omh.om_ptr()->enter(THREAD);
! }
}
// This routine is used to handle interpreter/compiler slow case
// We don't need to use fast path here, because it must have
// failed in the interpreter/compiler code. Simply use the heavy
*** 387,411 ****
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
! ObjectMonitor* monitor = inflate(THREAD, obj(), inflate_cause_vm_internal);
!
! return monitor->complete_exit(THREAD);
}
// NOTE: must use heavy weight monitor to handle complete_exit/reenter()
void ObjectSynchronizer::reenter(Handle obj, intptr_t recursion, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
! ObjectMonitor* monitor = inflate(THREAD, obj(), inflate_cause_vm_internal);
!
! monitor->reenter(recursion, THREAD);
}
// -----------------------------------------------------------------------------
// JNI locks on java objects
// NOTE: must use heavy weight monitor to handle jni monitor enter
void ObjectSynchronizer::jni_enter(Handle obj, TRAPS) {
--- 406,434 ----
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_vm_internal);
! intptr_t ret_code = omh.om_ptr()->complete_exit(THREAD);
! return ret_code;
}
// NOTE: must use heavy weight monitor to handle complete_exit/reenter()
void ObjectSynchronizer::reenter(Handle obj, intptr_t recursion, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
! bool do_loop = true;
! while (do_loop) {
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_vm_internal);
! do_loop = !omh.om_ptr()->reenter(recursion, THREAD);
! }
}
// -----------------------------------------------------------------------------
// JNI locks on java objects
// NOTE: must use heavy weight monitor to handle jni monitor enter
void ObjectSynchronizer::jni_enter(Handle obj, TRAPS) {
*** 413,423 ****
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
THREAD->set_current_pending_monitor_is_from_java(false);
! inflate(THREAD, obj(), inflate_cause_jni_enter)->enter(THREAD);
THREAD->set_current_pending_monitor_is_from_java(true);
}
// NOTE: must use heavy weight monitor to handle jni monitor exit
void ObjectSynchronizer::jni_exit(oop obj, Thread* THREAD) {
--- 436,451 ----
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
THREAD->set_current_pending_monitor_is_from_java(false);
! bool do_loop = true;
! while (do_loop) {
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_jni_enter);
! do_loop = !omh.om_ptr()->enter(THREAD);
! }
THREAD->set_current_pending_monitor_is_from_java(true);
}
// NOTE: must use heavy weight monitor to handle jni monitor exit
void ObjectSynchronizer::jni_exit(oop obj, Thread* THREAD) {
*** 426,436 ****
BiasedLocking::revoke_and_rebias(h_obj, false, THREAD);
obj = h_obj();
}
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
! ObjectMonitor* monitor = inflate(THREAD, obj, inflate_cause_jni_exit);
// If this thread has locked the object, exit the monitor. Note: can't use
// monitor->check(CHECK); must exit even if an exception is pending.
if (monitor->check(THREAD)) {
monitor->exit(true, THREAD);
}
--- 454,466 ----
BiasedLocking::revoke_and_rebias(h_obj, false, THREAD);
obj = h_obj();
}
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj, inflate_cause_jni_exit);
! ObjectMonitor * monitor = omh.om_ptr();
// If this thread has locked the object, exit the monitor. Note: can't use
// monitor->check(CHECK); must exit even if an exception is pending.
if (monitor->check(THREAD)) {
monitor->exit(true, THREAD);
}
*** 466,496 ****
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
if (millis < 0) {
THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "timeout value is negative");
}
! ObjectMonitor* monitor = inflate(THREAD, obj(), inflate_cause_wait);
DTRACE_MONITOR_WAIT_PROBE(monitor, obj(), THREAD, millis);
monitor->wait(millis, true, THREAD);
// This dummy call is in place to get around dtrace bug 6254741. Once
// that's fixed we can uncomment the following line, remove the call
// and change this function back into a "void" func.
// DTRACE_MONITOR_PROBE(waited, monitor, obj(), THREAD);
! return dtrace_waited_probe(monitor, obj, THREAD);
}
void ObjectSynchronizer::waitUninterruptibly(Handle obj, jlong millis, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
if (millis < 0) {
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "timeout value is negative");
}
! inflate(THREAD, obj(), inflate_cause_wait)->wait(millis, false, THREAD);
}
void ObjectSynchronizer::notify(Handle obj, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
--- 496,531 ----
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
if (millis < 0) {
THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "timeout value is negative");
}
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_wait);
! ObjectMonitor * monitor = omh.om_ptr();
DTRACE_MONITOR_WAIT_PROBE(monitor, obj(), THREAD, millis);
monitor->wait(millis, true, THREAD);
// This dummy call is in place to get around dtrace bug 6254741. Once
// that's fixed we can uncomment the following line, remove the call
// and change this function back into a "void" func.
// DTRACE_MONITOR_PROBE(waited, monitor, obj(), THREAD);
! int ret_code = dtrace_waited_probe(monitor, obj, THREAD);
! return ret_code;
}
void ObjectSynchronizer::waitUninterruptibly(Handle obj, jlong millis, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
assert(!obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
if (millis < 0) {
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "timeout value is negative");
}
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_wait);
! omh.om_ptr()->wait(millis, false, THREAD);
}
void ObjectSynchronizer::notify(Handle obj, TRAPS) {
if (UseBiasedLocking) {
BiasedLocking::revoke_and_rebias(obj, false, THREAD);
*** 499,509 ****
markOop mark = obj->mark();
if (mark->has_locker() && THREAD->is_lock_owned((address)mark->locker())) {
return;
}
! inflate(THREAD, obj(), inflate_cause_notify)->notify(THREAD);
}
// NOTE: see comment of notify()
void ObjectSynchronizer::notifyall(Handle obj, TRAPS) {
if (UseBiasedLocking) {
--- 534,546 ----
markOop mark = obj->mark();
if (mark->has_locker() && THREAD->is_lock_owned((address)mark->locker())) {
return;
}
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_notify);
! omh.om_ptr()->notify(THREAD);
}
// NOTE: see comment of notify()
void ObjectSynchronizer::notifyall(Handle obj, TRAPS) {
if (UseBiasedLocking) {
*** 513,523 ****
markOop mark = obj->mark();
if (mark->has_locker() && THREAD->is_lock_owned((address)mark->locker())) {
return;
}
! inflate(THREAD, obj(), inflate_cause_notify)->notifyAll(THREAD);
}
// -----------------------------------------------------------------------------
// Hash Code handling
//
--- 550,562 ----
markOop mark = obj->mark();
if (mark->has_locker() && THREAD->is_lock_owned((address)mark->locker())) {
return;
}
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_notify);
! omh.om_ptr()->notifyAll(THREAD);
}
// -----------------------------------------------------------------------------
// Hash Code handling
//
*** 707,716 ****
--- 746,756 ----
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
Self->is_Java_thread() , "invariant");
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
((JavaThread *)Self)->thread_state() != _thread_blocked, "invariant");
+ Retry:
ObjectMonitor* monitor = NULL;
markOop temp, test;
intptr_t hash;
markOop mark = ReadStableMark(obj);
*** 731,741 ****
}
// If atomic operation failed, we must inflate the header
// into heavy weight monitor. We could add more code here
// for fast path, but it does not worth the complexity.
} else if (mark->has_monitor()) {
! monitor = mark->monitor();
temp = monitor->header();
assert(temp->is_neutral(), "invariant: header=" INTPTR_FORMAT, p2i((address)temp));
hash = temp->hash();
if (hash != 0) {
return hash;
--- 771,787 ----
}
// If atomic operation failed, we must inflate the header
// into heavy weight monitor. We could add more code here
// for fast path, but it does not worth the complexity.
} else if (mark->has_monitor()) {
! ObjectMonitorHandle omh;
! if (!omh.save_om_ptr(obj, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! goto Retry;
! }
! monitor = omh.om_ptr();
temp = monitor->header();
assert(temp->is_neutral(), "invariant: header=" INTPTR_FORMAT, p2i((address)temp));
hash = temp->hash();
if (hash != 0) {
return hash;
*** 758,768 ****
// Any change to stack may not propagate to other threads
// correctly.
}
// Inflate the monitor to set hash code
! monitor = inflate(Self, obj, inflate_cause_hash_code);
// Load displaced header and check it has hash code
mark = monitor->header();
assert(mark->is_neutral(), "invariant: header=" INTPTR_FORMAT, p2i((address)mark));
hash = mark->hash();
if (hash == 0) {
--- 804,816 ----
// Any change to stack may not propagate to other threads
// correctly.
}
// Inflate the monitor to set hash code
! ObjectMonitorHandle omh;
! inflate(&omh, Self, obj, inflate_cause_hash_code);
! monitor = omh.om_ptr();
// Load displaced header and check it has hash code
mark = monitor->header();
assert(mark->is_neutral(), "invariant: header=" INTPTR_FORMAT, p2i((address)mark));
hash = mark->hash();
if (hash == 0) {
*** 798,821 ****
}
assert(thread == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
markOop mark = ReadStableMark(obj);
// Uncontended case, header points to stack
if (mark->has_locker()) {
return thread->is_lock_owned((address)mark->locker());
}
// Contended case, header points to ObjectMonitor (tagged pointer)
if (mark->has_monitor()) {
! ObjectMonitor* monitor = mark->monitor();
! return monitor->is_entered(thread) != 0;
}
// Unlocked case, header in place
assert(mark->is_neutral(), "sanity check");
return false;
}
// Be aware of this method could revoke bias of the lock object.
// This method queries the ownership of the lock handle specified by 'h_obj'.
// If the current thread owns the lock, it returns owner_self. If no
--- 846,877 ----
}
assert(thread == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
+ while (true) {
markOop mark = ReadStableMark(obj);
// Uncontended case, header points to stack
if (mark->has_locker()) {
return thread->is_lock_owned((address)mark->locker());
}
// Contended case, header points to ObjectMonitor (tagged pointer)
if (mark->has_monitor()) {
! ObjectMonitorHandle omh;
! if (!omh.save_om_ptr(obj, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! continue;
! }
! bool ret_code = omh.om_ptr()->is_entered(thread) != 0;
! return ret_code;
}
// Unlocked case, header in place
assert(mark->is_neutral(), "sanity check");
return false;
+ }
}
// Be aware of this method could revoke bias of the lock object.
// This method queries the ownership of the lock handle specified by 'h_obj'.
// If the current thread owns the lock, it returns owner_self. If no
*** 837,867 ****
"biases should be revoked by now");
}
assert(self == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
markOop mark = ReadStableMark(obj);
// CASE: stack-locked. Mark points to a BasicLock on the owner's stack.
if (mark->has_locker()) {
return self->is_lock_owned((address)mark->locker()) ?
owner_self : owner_other;
}
// CASE: inflated. Mark (tagged pointer) points to an ObjectMonitor.
// The Object:ObjectMonitor relationship is stable as long as we're
! // not at a safepoint.
if (mark->has_monitor()) {
! void * owner = mark->monitor()->_owner;
if (owner == NULL) return owner_none;
return (owner == self ||
self->is_lock_owned((address)owner)) ? owner_self : owner_other;
}
// CASE: neutral
assert(mark->is_neutral(), "sanity check");
return owner_none; // it's unlocked
}
// FIXME: jvmti should call this
JavaThread* ObjectSynchronizer::get_lock_owner(ThreadsList * t_list, Handle h_obj) {
if (UseBiasedLocking) {
--- 893,933 ----
"biases should be revoked by now");
}
assert(self == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
+
+ while (true) {
markOop mark = ReadStableMark(obj);
// CASE: stack-locked. Mark points to a BasicLock on the owner's stack.
if (mark->has_locker()) {
return self->is_lock_owned((address)mark->locker()) ?
owner_self : owner_other;
}
// CASE: inflated. Mark (tagged pointer) points to an ObjectMonitor.
// The Object:ObjectMonitor relationship is stable as long as we're
! // not at a safepoint and AsyncDeflateIdleMonitors is false.
if (mark->has_monitor()) {
! ObjectMonitorHandle omh;
! if (!omh.save_om_ptr(obj, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! continue;
! }
! ObjectMonitor * monitor = omh.om_ptr();
! void * owner = monitor->_owner;
if (owner == NULL) return owner_none;
return (owner == self ||
self->is_lock_owned((address)owner)) ? owner_self : owner_other;
}
// CASE: neutral
assert(mark->is_neutral(), "sanity check");
return owner_none; // it's unlocked
+ }
}
// FIXME: jvmti should call this
JavaThread* ObjectSynchronizer::get_lock_owner(ThreadsList * t_list, Handle h_obj) {
if (UseBiasedLocking) {
*** 872,893 ****
}
assert(!h_obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
oop obj = h_obj();
- address owner = NULL;
markOop mark = ReadStableMark(obj);
// Uncontended case, header points to stack
if (mark->has_locker()) {
owner = (address) mark->locker();
}
// Contended case, header points to ObjectMonitor (tagged pointer)
else if (mark->has_monitor()) {
! ObjectMonitor* monitor = mark->monitor();
assert(monitor != NULL, "monitor should be non-null");
owner = (address) monitor->owner();
}
if (owner != NULL) {
--- 938,966 ----
}
assert(!h_obj->mark()->has_bias_pattern(), "biases should be revoked by now");
}
oop obj = h_obj();
+ while (true) {
+ address owner = NULL;
markOop mark = ReadStableMark(obj);
// Uncontended case, header points to stack
if (mark->has_locker()) {
owner = (address) mark->locker();
}
// Contended case, header points to ObjectMonitor (tagged pointer)
else if (mark->has_monitor()) {
! ObjectMonitorHandle omh;
! if (!omh.save_om_ptr(obj, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! continue;
! }
! ObjectMonitor* monitor = omh.om_ptr();
assert(monitor != NULL, "monitor should be non-null");
owner = (address) monitor->owner();
}
if (owner != NULL) {
*** 899,920 ****
// Cannot have assertion since this object may have been
// locked by another thread when reaching here.
// assert(mark->is_neutral(), "sanity check");
return NULL;
}
// Visitors ...
void ObjectSynchronizer::monitors_iterate(MonitorClosure* closure) {
PaddedEnd<ObjectMonitor> * block = OrderAccess::load_acquire(&gBlockList);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
for (int i = _BLOCKSIZE - 1; i > 0; i--) {
ObjectMonitor* mid = (ObjectMonitor *)(block + i);
! oop object = (oop)mid->object();
! if (object != NULL) {
closure->do_monitor(mid);
}
}
block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
}
--- 972,1004 ----
// Cannot have assertion since this object may have been
// locked by another thread when reaching here.
// assert(mark->is_neutral(), "sanity check");
return NULL;
+ }
}
// Visitors ...
void ObjectSynchronizer::monitors_iterate(MonitorClosure* closure) {
PaddedEnd<ObjectMonitor> * block = OrderAccess::load_acquire(&gBlockList);
while (block != NULL) {
assert(block->object() == CHAINMARKER, "must be a block header");
for (int i = _BLOCKSIZE - 1; i > 0; i--) {
ObjectMonitor* mid = (ObjectMonitor *)(block + i);
! if (mid->is_active()) {
! ObjectMonitorHandle omh(mid);
!
! if (mid->object() == NULL ||
! (AsyncDeflateIdleMonitors && mid->_owner == DEFLATER_MARKER)) {
! // Only process with closure if the object is set.
! // For async deflation, race here if monitor is not owned!
! // The above ref_count bump (in ObjectMonitorHandle ctr)
! // will cause subsequent async deflation to skip it.
! // However, previous or concurrent async deflation is a race.
! continue;
! }
closure->do_monitor(mid);
}
}
block = (PaddedEnd<ObjectMonitor> *)block->FreeNext;
}
*** 1021,1037 ****
// The VMThread will delete the op when completed.
VMThread::execute(new VM_ScavengeMonitors());
}
}
! ObjectMonitor* ObjectSynchronizer::omAlloc(Thread * Self) {
// A large MAXPRIVATE value reduces both list lock contention
// and list coherency traffic, but also tends to increase the
// number of objectMonitors in circulation as well as the STW
// scavenge costs. As usual, we lean toward time in space-time
// tradeoffs.
const int MAXPRIVATE = 1024;
for (;;) {
ObjectMonitor * m;
// 1: try to allocate from the thread's local omFreeList.
// Threads will attempt to allocate first from their local list, then
--- 1105,1136 ----
// The VMThread will delete the op when completed.
VMThread::execute(new VM_ScavengeMonitors());
}
}
! ObjectMonitor* ObjectSynchronizer::omAlloc(Thread * Self,
! const InflateCause cause) {
// A large MAXPRIVATE value reduces both list lock contention
// and list coherency traffic, but also tends to increase the
// number of objectMonitors in circulation as well as the STW
// scavenge costs. As usual, we lean toward time in space-time
// tradeoffs.
const int MAXPRIVATE = 1024;
+
+ if (AsyncDeflateIdleMonitors) {
+ JavaThread * jt = (JavaThread *)Self;
+ if (jt->omShouldDeflateIdleMonitors && jt->omInUseCount > 0 &&
+ cause != inflate_cause_vm_internal) {
+ // Deflate any per-thread idle monitors for this JavaThread if
+ // this is not an internal inflation. Clean up your own mess.
+ // (Gibbs Rule 45) Otherwise, skip this cleanup.
+ // deflate_global_idle_monitors_using_JT() is called by the ServiceThread.
+ debug_only(jt->check_for_valid_safepoint_state(false);)
+ ObjectSynchronizer::deflate_per_thread_idle_monitors_using_JT();
+ }
+ }
+
for (;;) {
ObjectMonitor * m;
// 1: try to allocate from the thread's local omFreeList.
// Threads will attempt to allocate first from their local list, then
*** 1042,1051 ****
--- 1141,1151 ----
m = Self->omFreeList;
if (m != NULL) {
Self->omFreeList = m->FreeNext;
Self->omFreeCount--;
guarantee(m->object() == NULL, "invariant");
+ m->set_allocation_state(ObjectMonitor::New);
m->FreeNext = Self->omInUseList;
Self->omInUseList = m;
Self->omInUseCount++;
return m;
}
*** 1063,1074 ****
--- 1163,1179 ----
for (int i = Self->omFreeProvision; --i >= 0 && gFreeList != NULL;) {
gMonitorFreeCount--;
ObjectMonitor * take = gFreeList;
gFreeList = take->FreeNext;
guarantee(take->object() == NULL, "invariant");
+ if (AsyncDeflateIdleMonitors) {
+ take->set_owner(NULL);
+ take->_count = 0;
+ }
guarantee(!take->is_busy(), "invariant");
take->Recycle();
+ assert(take->is_free(), "invariant");
omRelease(Self, take, false);
}
Thread::muxRelease(&gListLock);
Self->omFreeProvision += 1 + (Self->omFreeProvision/2);
if (Self->omFreeProvision > MAXPRIVATE) Self->omFreeProvision = MAXPRIVATE;
*** 1117,1126 ****
--- 1222,1232 ----
// linkage should be reconsidered. A better implementation would
// look like: class Block { Block * next; int N; ObjectMonitor Body [N] ; }
for (int i = 1; i < _BLOCKSIZE; i++) {
temp[i].FreeNext = (ObjectMonitor *)&temp[i+1];
+ assert(temp[i].is_free(), "invariant");
}
// terminate the last monitor as the end of list
temp[_BLOCKSIZE - 1].FreeNext = NULL;
*** 1159,1175 ****
// attempt failed. This doesn't allow unbounded #s of monitors to
// accumulate on a thread's free list.
//
// Key constraint: all ObjectMonitors on a thread's free list and the global
// free list must have their object field set to null. This prevents the
! // scavenger -- deflate_monitor_list() -- from reclaiming them.
void ObjectSynchronizer::omRelease(Thread * Self, ObjectMonitor * m,
bool fromPerThreadAlloc) {
guarantee(m->header() == NULL, "invariant");
guarantee(m->object() == NULL, "invariant");
guarantee(((m->is_busy()|m->_recursions) == 0), "freeing in-use monitor");
// Remove from omInUseList
if (fromPerThreadAlloc) {
ObjectMonitor* cur_mid_in_use = NULL;
bool extracted = false;
for (ObjectMonitor* mid = Self->omInUseList; mid != NULL; cur_mid_in_use = mid, mid = mid->FreeNext) {
--- 1265,1283 ----
// attempt failed. This doesn't allow unbounded #s of monitors to
// accumulate on a thread's free list.
//
// Key constraint: all ObjectMonitors on a thread's free list and the global
// free list must have their object field set to null. This prevents the
! // scavenger -- deflate_monitor_list() or deflate_monitor_list_using_JT()
! // -- from reclaiming them while we are trying to release them.
void ObjectSynchronizer::omRelease(Thread * Self, ObjectMonitor * m,
bool fromPerThreadAlloc) {
guarantee(m->header() == NULL, "invariant");
guarantee(m->object() == NULL, "invariant");
guarantee(((m->is_busy()|m->_recursions) == 0), "freeing in-use monitor");
+ m->set_allocation_state(ObjectMonitor::Free);
// Remove from omInUseList
if (fromPerThreadAlloc) {
ObjectMonitor* cur_mid_in_use = NULL;
bool extracted = false;
for (ObjectMonitor* mid = Self->omInUseList; mid != NULL; cur_mid_in_use = mid, mid = mid->FreeNext) {
*** 1188,1197 ****
--- 1296,1306 ----
assert(extracted, "Should have extracted from in-use list");
}
// FreeNext is used for both omInUseList and omFreeList, so clear old before setting new
m->FreeNext = Self->omFreeList;
+ guarantee(m->is_free(), "invariant");
Self->omFreeList = m;
Self->omFreeCount++;
}
// Return the monitors of a moribund thread's local free list to
*** 1211,1220 ****
--- 1320,1333 ----
// interleave with the deflate_idle_monitors scavenge operator. In particular,
// this ensures that the thread's monitors are scanned by a GC safepoint,
// either via Thread::oops_do() (if safepoint happens before omFlush()) or via
// ObjectSynchronizer::oops_do() (if it happens after omFlush() and the thread's
// monitors have been transferred to the global in-use list).
+ //
+ // With AsyncDeflateIdleMonitors, deflate_global_idle_monitors_using_JT()
+ // and deflate_per_thread_idle_monitors_using_JT() (in another thread) can
+ // run at the same time as omFlush() so we have to be careful.
void ObjectSynchronizer::omFlush(Thread * Self) {
ObjectMonitor * list = Self->omFreeList; // Null-terminated SLL
ObjectMonitor * tail = NULL;
int tally = 0;
*** 1230,1240 ****
guarantee(s->object() == NULL, "invariant");
guarantee(!s->is_busy(), "invariant");
s->set_owner(NULL); // redundant but good hygiene
}
guarantee(tail != NULL, "invariant");
! assert(Self->omFreeCount == tally, "free-count off");
Self->omFreeList = NULL;
Self->omFreeCount = 0;
}
ObjectMonitor * inUseList = Self->omInUseList;
--- 1343,1353 ----
guarantee(s->object() == NULL, "invariant");
guarantee(!s->is_busy(), "invariant");
s->set_owner(NULL); // redundant but good hygiene
}
guarantee(tail != NULL, "invariant");
! guarantee(Self->omFreeCount == tally, "free-count off");
Self->omFreeList = NULL;
Self->omFreeCount = 0;
}
ObjectMonitor * inUseList = Self->omInUseList;
*** 1247,1259 ****
// Link them to inUseTail, which will be linked into the global in-use list
// gOmInUseList below, under the gListLock
for (cur_om = inUseList; cur_om != NULL; cur_om = cur_om->FreeNext) {
inUseTail = cur_om;
inUseTally++;
}
guarantee(inUseTail != NULL, "invariant");
! assert(Self->omInUseCount == inUseTally, "in-use count off");
Self->omInUseList = NULL;
Self->omInUseCount = 0;
}
Thread::muxAcquire(&gListLock, "omFlush");
--- 1360,1373 ----
// Link them to inUseTail, which will be linked into the global in-use list
// gOmInUseList below, under the gListLock
for (cur_om = inUseList; cur_om != NULL; cur_om = cur_om->FreeNext) {
inUseTail = cur_om;
inUseTally++;
+ guarantee(cur_om->is_active(), "invariant");
}
guarantee(inUseTail != NULL, "invariant");
! guarantee(Self->omInUseCount == inUseTally, "in-use count off");
Self->omInUseList = NULL;
Self->omInUseCount = 0;
}
Thread::muxAcquire(&gListLock, "omFlush");
*** 1297,1319 ****
event->set_cause((u1)cause);
event->commit();
}
// Fast path code shared by multiple functions
! void ObjectSynchronizer::inflate_helper(oop obj) {
markOop mark = obj->mark();
if (mark->has_monitor()) {
! assert(ObjectSynchronizer::verify_objmon_isinpool(mark->monitor()), "monitor is invalid");
! assert(mark->monitor()->header()->is_neutral(), "monitor must record a good object header");
return;
}
- inflate(Thread::current(), obj, inflate_cause_vm_internal);
}
! ObjectMonitor* ObjectSynchronizer::inflate(Thread * Self,
! oop object,
! const InflateCause cause) {
// Inflate mutates the heap ...
// Relaxing assertion for bug 6320749.
assert(Universe::verify_in_progress() ||
!SafepointSynchronize::is_at_safepoint(), "invariant");
--- 1411,1442 ----
event->set_cause((u1)cause);
event->commit();
}
// Fast path code shared by multiple functions
! void ObjectSynchronizer::inflate_helper(ObjectMonitorHandle * omh_p, oop obj) {
! while (true) {
markOop mark = obj->mark();
if (mark->has_monitor()) {
! if (!omh_p->save_om_ptr(obj, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! continue;
! }
! ObjectMonitor * monitor = omh_p->om_ptr();
! assert(ObjectSynchronizer::verify_objmon_isinpool(monitor), "monitor is invalid");
! markOop dmw = monitor->header();
! assert(dmw->is_neutral(), "sanity check: header=" INTPTR_FORMAT, p2i((address)dmw));
! return;
! }
! inflate(omh_p, Thread::current(), obj, inflate_cause_vm_internal);
return;
}
}
! void ObjectSynchronizer::inflate(ObjectMonitorHandle * omh_p, Thread * Self,
! oop object, const InflateCause cause) {
// Inflate mutates the heap ...
// Relaxing assertion for bug 6320749.
assert(Universe::verify_in_progress() ||
!SafepointSynchronize::is_at_safepoint(), "invariant");
*** 1330,1345 ****
// * Neutral - aggressively inflate the object.
// * BIASED - Illegal. We should never see this
// CASE: inflated
if (mark->has_monitor()) {
! ObjectMonitor * inf = mark->monitor();
markOop dmw = inf->header();
assert(dmw->is_neutral(), "invariant: header=" INTPTR_FORMAT, p2i((address)dmw));
assert(oopDesc::equals((oop) inf->object(), object), "invariant");
assert(ObjectSynchronizer::verify_objmon_isinpool(inf), "monitor is invalid");
! return inf;
}
// CASE: inflation in progress - inflating over a stack-lock.
// Some other thread is converting from stack-locked to inflated.
// Only that thread can complete inflation -- other threads must wait.
--- 1453,1473 ----
// * Neutral - aggressively inflate the object.
// * BIASED - Illegal. We should never see this
// CASE: inflated
if (mark->has_monitor()) {
! if (!omh_p->save_om_ptr(object, mark)) {
! // Lost a race with async deflation so try again.
! assert(AsyncDeflateIdleMonitors, "sanity check");
! continue;
! }
! ObjectMonitor * inf = omh_p->om_ptr();
markOop dmw = inf->header();
assert(dmw->is_neutral(), "invariant: header=" INTPTR_FORMAT, p2i((address)dmw));
assert(oopDesc::equals((oop) inf->object(), object), "invariant");
assert(ObjectSynchronizer::verify_objmon_isinpool(inf), "monitor is invalid");
! return;
}
// CASE: inflation in progress - inflating over a stack-lock.
// Some other thread is converting from stack-locked to inflated.
// Only that thread can complete inflation -- other threads must wait.
*** 1371,1381 ****
// See the comments in omAlloc().
LogStreamHandle(Trace, monitorinflation) lsh;
if (mark->has_locker()) {
! ObjectMonitor * m = omAlloc(Self);
// Optimistically prepare the objectmonitor - anticipate successful CAS
// We do this before the CAS in order to minimize the length of time
// in which INFLATING appears in the mark.
m->Recycle();
m->_Responsible = NULL;
--- 1499,1520 ----
// See the comments in omAlloc().
LogStreamHandle(Trace, monitorinflation) lsh;
if (mark->has_locker()) {
! ObjectMonitor * m;
! if (!AsyncDeflateIdleMonitors || cause == inflate_cause_vm_internal) {
! // If !AsyncDeflateIdleMonitors or if an internal inflation, then
! // we won't stop for a potential safepoint in omAlloc.
! m = omAlloc(Self, cause);
! } else {
! // If AsyncDeflateIdleMonitors and not an internal inflation, then
! // we may stop for a safepoint in omAlloc() so protect object.
! Handle h_obj(Self, object);
! m = omAlloc(Self, cause);
! object = h_obj(); // Refresh object.
! }
// Optimistically prepare the objectmonitor - anticipate successful CAS
// We do this before the CAS in order to minimize the length of time
// in which INFLATING appears in the mark.
m->Recycle();
m->_Responsible = NULL;
*** 1448,1458 ****
p2i(object->mark()), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! return m;
}
// CASE: neutral
// TODO-FIXME: for entry we currently inflate and then try to CAS _owner.
// If we know we're inflating for entry it's better to inflate by swinging a
--- 1587,1599 ----
p2i(object->mark()), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! assert(!m->is_free(), "post-condition");
! omh_p->set_om_ptr(m);
! return;
}
// CASE: neutral
// TODO-FIXME: for entry we currently inflate and then try to CAS _owner.
// If we know we're inflating for entry it's better to inflate by swinging a
*** 1462,1472 ****
// to inflate and then CAS() again to try to swing _owner from NULL to Self.
// An inflateTry() method that we could call from fast_enter() and slow_enter()
// would be useful.
assert(mark->is_neutral(), "invariant");
! ObjectMonitor * m = omAlloc(Self);
// prepare m for installation - set monitor to initial state
m->Recycle();
m->set_header(mark);
m->set_owner(NULL);
m->set_object(object);
--- 1603,1624 ----
// to inflate and then CAS() again to try to swing _owner from NULL to Self.
// An inflateTry() method that we could call from fast_enter() and slow_enter()
// would be useful.
assert(mark->is_neutral(), "invariant");
! ObjectMonitor * m;
! if (!AsyncDeflateIdleMonitors || cause == inflate_cause_vm_internal) {
! // If !AsyncDeflateIdleMonitors or if an internal inflation, then
! // we won't stop for a potential safepoint in omAlloc.
! m = omAlloc(Self, cause);
! } else {
! // If AsyncDeflateIdleMonitors and not an internal inflation, then
! // we may stop for a safepoint in omAlloc() so protect object.
! Handle h_obj(Self, object);
! m = omAlloc(Self, cause);
! object = h_obj(); // Refresh object.
! }
// prepare m for installation - set monitor to initial state
m->Recycle();
m->set_header(mark);
m->set_owner(NULL);
m->set_object(object);
*** 1496,1506 ****
p2i(object->mark()), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! return m;
}
}
// We create a list of in-use monitors for each thread.
--- 1648,1659 ----
p2i(object->mark()), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! omh_p->set_om_ptr(m);
! return;
}
}
// We create a list of in-use monitors for each thread.
*** 1522,1531 ****
--- 1675,1708 ----
// Perversely, the heap size -- and thus the STW safepoint rate --
// typically drives the scavenge rate. Large heaps can mean infrequent GC,
// which in turn can mean large(r) numbers of objectmonitors in circulation.
// This is an unfortunate aspect of this design.
+ void ObjectSynchronizer::do_safepoint_work(DeflateMonitorCounters* _counters) {
+ if (!AsyncDeflateIdleMonitors) {
+ // Use the older mechanism for the global in-use list.
+ ObjectSynchronizer::deflate_idle_monitors(_counters);
+ return;
+ }
+
+ assert(_counters == NULL, "not used with AsyncDeflateIdleMonitors");
+
+ log_debug(monitorinflation)("requesting deflation of idle monitors.");
+ // Request deflation of global idle monitors by the ServiceThread:
+ _gOmShouldDeflateIdleMonitors = true;
+ MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
+ Service_lock->notify_all();
+
+ // Request deflation of per-thread idle monitors by each JavaThread:
+ for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
+ if (jt->omInUseCount > 0) {
+ // This JavaThread is using monitors so check it.
+ jt->omShouldDeflateIdleMonitors = true;
+ }
+ }
+ }
+
// Deflate a single monitor if not in-use
// Return true if deflated, false if in-use
bool ObjectSynchronizer::deflate_monitor(ObjectMonitor* mid, oop obj,
ObjectMonitor** freeHeadp,
ObjectMonitor** freeTailp) {
*** 1552,1561 ****
--- 1729,1739 ----
// Restore the header back to obj
obj->release_set_mark(mid->header());
mid->clear();
assert(mid->object() == NULL, "invariant");
+ assert(mid->is_free(), "invariant");
// Move the object to the working free list defined by freeHeadp, freeTailp
if (*freeHeadp == NULL) *freeHeadp = mid;
if (*freeTailp != NULL) {
ObjectMonitor * prevtail = *freeTailp;
*** 1566,1575 ****
--- 1744,1879 ----
deflated = true;
}
return deflated;
}
+ // Deflate the specified ObjectMonitor if not in-use using a JavaThread.
+ // Returns true if it was deflated and false otherwise.
+ //
+ // The async deflation protocol sets _owner to DEFLATER_MARKER and
+ // makes _count negative as signals to contending threads that an
+ // async deflation is in progress. There are a number of checks as
+ // part of the protocol to make sure that the calling thread has
+ // not lost the race to a contending thread.
+ //
+ // The ObjectMonitor has been successfully async deflated when:
+ // (_owner == DEFLATER_MARKER && _count < 0). Contending threads that
+ // see those values know to retry their operation.
+ //
+ bool ObjectSynchronizer::deflate_monitor_using_JT(ObjectMonitor* mid,
+ ObjectMonitor** freeHeadp,
+ ObjectMonitor** freeTailp) {
+ assert(AsyncDeflateIdleMonitors, "sanity check");
+ assert(Thread::current()->is_Java_thread(), "precondition");
+ // A newly allocated ObjectMonitor should not be seen here so we
+ // avoid an endless inflate/deflate cycle.
+ assert(mid->is_old(), "precondition");
+
+ if (mid->is_busy() || mid->ref_count() != 0) {
+ // Easy checks are first - the ObjectMonitor is busy or ObjectMonitor*
+ // is in use so no deflation.
+ return false;
+ }
+
+ if (Atomic::cmpxchg(DEFLATER_MARKER, &mid->_owner, (void*)NULL) == NULL) {
+ // ObjectMonitor is not owned by another thread. Our setting
+ // _owner to DEFLATER_MARKER forces any contending thread through
+ // the slow path. This is just the first part of the async
+ // deflation dance.
+
+ if (mid->_waiters != 0 || mid->ref_count() != 0) {
+ // Another thread has raced to enter the ObjectMonitor after
+ // mid->is_busy() above and has already waited on it which
+ // makes it busy so no deflation. Or the ObjectMonitor* is
+ // in use for some other operation like inflate(). Restore
+ // _owner to NULL if it is still DEFLATER_MARKER.
+ Atomic::cmpxchg((void*)NULL, &mid->_owner, DEFLATER_MARKER);
+ return false;
+ }
+
+ if (Atomic::cmpxchg(-max_jint, &mid->_count, (jint)0) == 0) {
+ // Make _count negative to force racing threads to retry.
+ // This is the second part of the async deflation dance.
+
+ if (mid->_owner == DEFLATER_MARKER) {
+ // If _owner is still DEFLATER_MARKER, then we have successfully
+ // signaled any racing threads to retry. If it is not, then we
+ // have lost the race to another thread and the ObjectMonitor is
+ // now busy. This is the third and final part of the async
+ // deflation dance.
+ // Note: This _owner check solves the ABA problem with _count
+ // where another thread acquired the ObjectMonitor, finished
+ // using it and restored the _count to zero.
+
+ // Sanity checks for the races:
+ guarantee(mid->_waiters == 0, "should be no waiters");
+ guarantee(mid->_cxq == NULL, "should be no contending threads");
+ guarantee(mid->_EntryList == NULL, "should be no entering threads");
+
+ if (log_is_enabled(Trace, monitorinflation)) {
+ oop obj = (oop) mid->object();
+ assert(obj != NULL, "sanity check");
+ if (obj->is_instance()) {
+ ResourceMark rm;
+ log_trace(monitorinflation)("deflate_monitor_using_JT: "
+ "object=" INTPTR_FORMAT ", mark=" INTPTR_FORMAT ", type='%s'",
+ p2i(obj), p2i(obj->mark()),
+ obj->klass()->external_name());
+ }
+ }
+
+ // Install the old mark word if nobody else has already done it.
+ mid->install_displaced_markword_in_object();
+ mid->clear_using_JT();
+
+ assert(mid->object() == NULL, "invariant");
+ assert(mid->is_free(), "invariant");
+
+ // Move the deflated ObjectMonitor to the working free list
+ // defined by freeHeadp and freeTailp.
+ if (*freeHeadp == NULL) {
+ // First one on the list.
+ *freeHeadp = mid;
+ }
+ if (*freeTailp != NULL) {
+ // We append to the list so the caller can use mid->FreeNext
+ // to fix the linkages in its context.
+ ObjectMonitor * prevtail = *freeTailp;
+ assert(prevtail->FreeNext == NULL, "not cleaned up by the caller");
+ prevtail->FreeNext = mid;
+ }
+ *freeTailp = mid;
+
+ // At this point, mid->FreeNext still refers to its current
+ // value and another ObjectMonitor's FreeNext field still
+ // refers to this ObjectMonitor. Those linkages have to be
+ // cleaned up by the caller who has the complete context.
+
+ // We leave _owner == DEFLATER_MARKER and _count < 0 to
+ // force any racing threads to retry.
+ return true; // Success, ObjectMonitor has been deflated.
+ }
+
+ // The _owner was changed from DEFLATER_MARKER so we lost the
+ // race since the ObjectMonitor is now busy. Add back max_jint
+ // to restore the _count field to its proper value (which may
+ // not be what we saw above).
+ Atomic::add(max_jint, &mid->_count);
+
+ assert(mid->_count >= 0, "_count should not be negative");
+ }
+
+ // The _count was no longer 0 so we lost the race since the
+ // ObjectMonitor is now busy.
+ assert(mid->_owner != DEFLATER_MARKER, "should no longer be set");
+ }
+
+ // The _owner field is no longer NULL so we lost the race since the
+ // ObjectMonitor is now busy.
+ return false;
+ }
+
// Walk a given monitor list, and deflate idle monitors
// The given list could be a per-thread list or a global list
// Caller acquires gListLock as needed.
//
// In the case of parallel processing of thread local monitor lists,
*** 1609,1627 ****
--- 1913,2013 ----
}
}
return deflated_count;
}
+ // Walk a given ObjectMonitor list and deflate idle ObjectMonitors using
+ // a JavaThread. Returns the number of deflated ObjectMonitors. The given
+ // list could be a per-thread in-use list or the global in-use list.
+ // Caller acquires gListLock as appropriate. If a safepoint has started,
+ // then we save state via savedMidInUsep and return to the caller to
+ // honor the safepoint.
+ //
+ int ObjectSynchronizer::deflate_monitor_list_using_JT(ObjectMonitor** listHeadp,
+ ObjectMonitor** freeHeadp,
+ ObjectMonitor** freeTailp,
+ ObjectMonitor** savedMidInUsep) {
+ assert(AsyncDeflateIdleMonitors, "sanity check");
+ assert(Thread::current()->is_Java_thread(), "precondition");
+
+ ObjectMonitor* mid;
+ ObjectMonitor* next;
+ ObjectMonitor* cur_mid_in_use = NULL;
+ int deflated_count = 0;
+
+ if (*savedMidInUsep == NULL) {
+ // No saved state so start at the beginning.
+ mid = *listHeadp;
+ } else {
+ // We're restarting after a safepoint so restore the necessary state
+ // before we resume.
+ cur_mid_in_use = *savedMidInUsep;
+ mid = cur_mid_in_use->FreeNext;
+ }
+ while (mid != NULL) {
+ // Only try to deflate if there is an associated Java object and if
+ // mid is old (is not newly allocated and is not newly freed).
+ if (mid->object() != NULL && mid->is_old() &&
+ deflate_monitor_using_JT(mid, freeHeadp, freeTailp)) {
+ // Deflation succeeded so update the in-use list.
+ if (mid == *listHeadp) {
+ *listHeadp = mid->FreeNext;
+ } else if (cur_mid_in_use != NULL) {
+ // Maintain the current in-use list.
+ cur_mid_in_use->FreeNext = mid->FreeNext;
+ }
+ next = mid->FreeNext;
+ mid->FreeNext = NULL;
+ // At this point mid is disconnected from the in-use list
+ // and is the current tail in the freeHeadp list.
+ mid = next;
+ deflated_count++;
+ } else {
+ // mid is considered in-use if it does not have an associated
+ // Java object or mid is not old or deflation did not succeed.
+ // A mid->is_new() node can be seen here when it is freshly returned
+ // by omAlloc() (and skips the deflation code path).
+ // A mid->is_old() node can be seen here when deflation failed.
+ // A mid->is_free() node can be seen here when a fresh node from
+ // omAlloc() is released by omRelease() due to losing the race
+ // in inflate().
+
+ if (mid->object() != NULL && mid->is_new()) {
+ // mid has an associated Java object and has now been seen
+ // as newly allocated so mark it as "old".
+ mid->set_allocation_state(ObjectMonitor::Old);
+ }
+ cur_mid_in_use = mid;
+ mid = mid->FreeNext;
+
+ if (SafepointSynchronize::is_synchronizing() &&
+ cur_mid_in_use != *listHeadp && cur_mid_in_use->is_old()) {
+ // If a safepoint has started and cur_mid_in_use is not the list
+ // head and is old, then it is safe to use as saved state. Return
+ // to the caller so gListLock can be dropped as appropriate
+ // before blocking.
+ *savedMidInUsep = cur_mid_in_use;
+ return deflated_count;
+ }
+ }
+ }
+ // We finished the list without a safepoint starting so there's
+ // no need to save state.
+ *savedMidInUsep = NULL;
+ return deflated_count;
+ }
+
void ObjectSynchronizer::prepare_deflate_idle_monitors(DeflateMonitorCounters* counters) {
counters->nInuse = 0; // currently associated with objects
counters->nInCirculation = 0; // extant
counters->nScavenged = 0; // reclaimed (global and per-thread)
counters->perThreadScavenged = 0; // per-thread scavenge total
counters->perThreadTimes = 0.0; // per-thread scavenge times
}
void ObjectSynchronizer::deflate_idle_monitors(DeflateMonitorCounters* counters) {
+ assert(!AsyncDeflateIdleMonitors, "sanity check");
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
bool deflated = false;
ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged monitors
ObjectMonitor * freeTailp = NULL;
*** 1671,1689 ****
--- 2057,2231 ----
if (ls != NULL) {
ls->print_cr("deflating global idle monitors, %3.7f secs, %d monitors", timer.seconds(), deflated_count);
}
}
+ // Deflate global idle ObjectMonitors using a JavaThread.
+ //
+ void ObjectSynchronizer::deflate_global_idle_monitors_using_JT() {
+ assert(AsyncDeflateIdleMonitors, "sanity check");
+ assert(Thread::current()->is_Java_thread(), "precondition");
+ JavaThread * cur_jt = JavaThread::current();
+
+ _gOmShouldDeflateIdleMonitors = false;
+
+ int deflated_count = 0;
+ ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged ObjectMonitors
+ ObjectMonitor * freeTailp = NULL;
+ ObjectMonitor * savedMidInUsep = NULL;
+ elapsedTimer timer;
+
+ if (log_is_enabled(Info, monitorinflation)) {
+ timer.start();
+ }
+ Thread::muxAcquire(&gListLock, "deflate_global_idle_monitors_using_JT(1)");
+ OM_PERFDATA_OP(MonExtant, set_value(gOmInUseCount));
+
+ do {
+ int local_deflated_count = deflate_monitor_list_using_JT((ObjectMonitor **)&gOmInUseList, &freeHeadp, &freeTailp, &savedMidInUsep);
+ gOmInUseCount -= local_deflated_count;
+ deflated_count += local_deflated_count;
+
+ if (freeHeadp != NULL) {
+ // Move the scavenged ObjectMonitors to the global free list.
+ guarantee(freeTailp != NULL && local_deflated_count > 0, "freeTailp=" INTPTR_FORMAT ", local_deflated_count=%d", p2i(freeTailp), local_deflated_count);
+ assert(freeTailp->FreeNext == NULL, "invariant");
+
+ // Constant-time list splice - prepend scavenged segment to gFreeList.
+ freeTailp->FreeNext = gFreeList;
+ gFreeList = freeHeadp;
+
+ gMonitorFreeCount += local_deflated_count;
+ OM_PERFDATA_OP(Deflations, inc(local_deflated_count));
+ }
+
+ if (savedMidInUsep != NULL) {
+ // deflate_monitor_list_using_JT() detected a safepoint starting.
+ Thread::muxRelease(&gListLock);
+ timer.stop();
+ {
+ log_debug(monitorinflation)("pausing deflation of global idle monitors for a safepoint.");
+ assert(SafepointSynchronize::is_synchronizing(), "sanity check");
+ ThreadBlockInVM blocker(cur_jt);
+ }
+ // Prepare for another loop after the safepoint.
+ freeHeadp = NULL;
+ freeTailp = NULL;
+ if (log_is_enabled(Info, monitorinflation)) {
+ timer.start();
+ }
+ Thread::muxAcquire(&gListLock, "deflate_global_idle_monitors_using_JT(2)");
+ }
+ } while (savedMidInUsep != NULL);
+ Thread::muxRelease(&gListLock);
+ timer.stop();
+
+ LogStreamHandle(Debug, monitorinflation) lsh_debug;
+ LogStreamHandle(Info, monitorinflation) lsh_info;
+ LogStream * ls = NULL;
+ if (log_is_enabled(Debug, monitorinflation)) {
+ ls = &lsh_debug;
+ } else if (deflated_count != 0 && log_is_enabled(Info, monitorinflation)) {
+ ls = &lsh_info;
+ }
+ if (ls != NULL) {
+ ls->print_cr("async-deflating global idle monitors, %3.7f secs, %d monitors", timer.seconds(), deflated_count);
+ }
+ }
+
+ // Deflate per-thread idle ObjectMonitors using a JavaThread.
+ //
+ void ObjectSynchronizer::deflate_per_thread_idle_monitors_using_JT() {
+ assert(AsyncDeflateIdleMonitors, "sanity check");
+ assert(Thread::current()->is_Java_thread(), "precondition");
+ JavaThread * cur_jt = JavaThread::current();
+
+ cur_jt->omShouldDeflateIdleMonitors = false;
+
+ int deflated_count = 0;
+ ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged ObjectMonitors
+ ObjectMonitor * freeTailp = NULL;
+ ObjectMonitor * savedMidInUsep = NULL;
+ elapsedTimer timer;
+
+ if (log_is_enabled(Info, monitorinflation)) {
+ timer.start();
+ }
+
+ OM_PERFDATA_OP(MonExtant, inc(cur_jt->omInUseCount));
+ do {
+ int local_deflated_count = deflate_monitor_list_using_JT(cur_jt->omInUseList_addr(), &freeHeadp, &freeTailp, &savedMidInUsep);
+ cur_jt->omInUseCount -= local_deflated_count;
+ deflated_count += local_deflated_count;
+
+ if (freeHeadp != NULL) {
+ // Move the scavenged ObjectMonitors to the global free list.
+ Thread::muxAcquire(&gListLock, "deflate_per_thread_idle_monitors_using_JT");
+ guarantee(freeTailp != NULL && local_deflated_count > 0, "freeTailp=" INTPTR_FORMAT ", local_deflated_count=%d", p2i(freeTailp), local_deflated_count);
+ assert(freeTailp->FreeNext == NULL, "invariant");
+
+ // Constant-time list splice - prepend scavenged segment to gFreeList.
+ freeTailp->FreeNext = gFreeList;
+ gFreeList = freeHeadp;
+
+ gMonitorFreeCount += local_deflated_count;
+ OM_PERFDATA_OP(Deflations, inc(local_deflated_count));
+ Thread::muxRelease(&gListLock);
+ // Prepare for another loop on the current JavaThread.
+ freeHeadp = NULL;
+ freeTailp = NULL;
+ }
+ timer.stop();
+
+ if (savedMidInUsep != NULL) {
+ // deflate_monitor_list_using_JT() detected a safepoint starting.
+ {
+ log_debug(monitorinflation)("jt=" INTPTR_FORMAT ": pausing deflation of per-thread idle monitors for a safepoint.", p2i(cur_jt));
+ assert(SafepointSynchronize::is_synchronizing(), "sanity check");
+ ThreadBlockInVM blocker(cur_jt);
+ }
+ // Prepare for another loop on the current JavaThread after
+ // the safepoint.
+ if (log_is_enabled(Info, monitorinflation)) {
+ timer.start();
+ }
+ }
+ } while (savedMidInUsep != NULL);
+
+ LogStreamHandle(Debug, monitorinflation) lsh_debug;
+ LogStreamHandle(Info, monitorinflation) lsh_info;
+ LogStream * ls = NULL;
+ if (log_is_enabled(Debug, monitorinflation)) {
+ ls = &lsh_debug;
+ } else if (deflated_count != 0 && log_is_enabled(Info, monitorinflation)) {
+ ls = &lsh_info;
+ }
+ if (ls != NULL) {
+ ls->print_cr("jt=" INTPTR_FORMAT ": async-deflating per-thread idle monitors, %3.7f secs, %d monitors", p2i(cur_jt), timer.seconds(), deflated_count);
+ }
+ }
+
void ObjectSynchronizer::finish_deflate_idle_monitors(DeflateMonitorCounters* counters) {
// Report the cumulative time for deflating each thread's idle
// monitors. Note: if the work is split among more than one
// worker thread, then the reported time will likely be more
// than a beginning to end measurement of the phase.
+ // Note: AsyncDeflateIdleMonitors only deflates per-thread idle
+ // monitors at a safepoint when a special cleanup has been requested.
log_info(safepoint, cleanup)("deflating per-thread idle monitors, %3.7f secs, monitors=%d", counters->perThreadTimes, counters->perThreadScavenged);
+ bool needs_special_cleanup = is_cleanup_requested();
+ if (!AsyncDeflateIdleMonitors || needs_special_cleanup) {
+ // AsyncDeflateIdleMonitors does not use these counters unless
+ // there is a special cleanup request.
+
gMonitorFreeCount += counters->nScavenged;
+ OM_PERFDATA_OP(Deflations, inc(counters->nScavenged));
+ OM_PERFDATA_OP(MonExtant, set_value(counters->nInCirculation));
+ }
+
if (log_is_enabled(Debug, monitorinflation)) {
// exit_globals()'s call to audit_and_print_stats() is done
// at the Info level.
ObjectSynchronizer::audit_and_print_stats(false /* on_exit */);
} else if (log_is_enabled(Info, monitorinflation)) {
*** 1693,1713 ****
gOmInUseCount, gMonitorFreeCount);
Thread::muxRelease(&gListLock);
}
ForceMonitorScavenge = 0; // Reset
-
- OM_PERFDATA_OP(Deflations, inc(counters->nScavenged));
- OM_PERFDATA_OP(MonExtant, set_value(counters->nInCirculation));
-
GVars.stwRandom = os::random();
GVars.stwCycle++;
}
void ObjectSynchronizer::deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged monitors
ObjectMonitor * freeTailp = NULL;
elapsedTimer timer;
if (log_is_enabled(Info, safepoint, cleanup) ||
--- 2235,2262 ----
gOmInUseCount, gMonitorFreeCount);
Thread::muxRelease(&gListLock);
}
ForceMonitorScavenge = 0; // Reset
GVars.stwRandom = os::random();
GVars.stwCycle++;
+ if (needs_special_cleanup) {
+ set_is_cleanup_requested(false); // special clean up is done
+ }
}
void ObjectSynchronizer::deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+ if (AsyncDeflateIdleMonitors) {
+ // Nothing to do when idle ObjectMonitors are deflated using a
+ // JavaThread unless a special cleanup has been requested.
+ if (!is_cleanup_requested()) {
+ return;
+ }
+ }
+
ObjectMonitor * freeHeadp = NULL; // Local SLL of scavenged monitors
ObjectMonitor * freeTailp = NULL;
elapsedTimer timer;
if (log_is_enabled(Info, safepoint, cleanup) ||
*** 1915,1925 ****
}
// Check a free monitor entry; log any errors.
void ObjectSynchronizer::chk_free_entry(JavaThread * jt, ObjectMonitor * n,
outputStream * out, int *error_cnt_p) {
! if (n->is_busy()) {
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must not be busy.", p2i(jt),
p2i(n));
} else {
--- 2464,2475 ----
}
// Check a free monitor entry; log any errors.
void ObjectSynchronizer::chk_free_entry(JavaThread * jt, ObjectMonitor * n,
outputStream * out, int *error_cnt_p) {
! if ((!AsyncDeflateIdleMonitors && n->is_busy()) ||
! (AsyncDeflateIdleMonitors && n->is_busy_async())) {
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must not be busy.", p2i(jt),
p2i(n));
} else {
*** 2107,2147 ****
}
if (gOmInUseCount > 0) {
out->print_cr("In-use global monitor info:");
out->print_cr("(B -> is_busy, H -> has hashcode, L -> lock status)");
! out->print_cr("%18s %s %18s %18s",
! "monitor", "BHL", "object", "object type");
! out->print_cr("================== === ================== ==================");
for (ObjectMonitor * n = gOmInUseList; n != NULL; n = n->FreeNext) {
const oop obj = (oop) n->object();
const markOop mark = n->header();
ResourceMark rm;
! out->print_cr(INTPTR_FORMAT " %d%d%d " INTPTR_FORMAT " %s", p2i(n),
! n->is_busy() != 0, mark->hash() != 0, n->owner() != NULL,
! p2i(obj), obj->klass()->external_name());
}
}
if (!on_exit) {
Thread::muxRelease(&gListLock);
}
out->print_cr("In-use per-thread monitor info:");
out->print_cr("(B -> is_busy, H -> has hashcode, L -> lock status)");
! out->print_cr("%18s %18s %s %18s %18s",
! "jt", "monitor", "BHL", "object", "object type");
! out->print_cr("================== ================== === ================== ==================");
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
for (ObjectMonitor * n = jt->omInUseList; n != NULL; n = n->FreeNext) {
const oop obj = (oop) n->object();
const markOop mark = n->header();
ResourceMark rm;
! out->print_cr(INTPTR_FORMAT " " INTPTR_FORMAT " %d%d%d " INTPTR_FORMAT
! " %s", p2i(jt), p2i(n), n->is_busy() != 0,
! mark->hash() != 0, n->owner() != NULL, p2i(obj),
! obj->klass()->external_name());
}
}
out->flush();
}
--- 2657,2698 ----
}
if (gOmInUseCount > 0) {
out->print_cr("In-use global monitor info:");
out->print_cr("(B -> is_busy, H -> has hashcode, L -> lock status)");
! out->print_cr("%18s %s %7s %18s %18s",
! "monitor", "BHL", "ref_cnt", "object", "object type");
! out->print_cr("================== === ======= ================== ==================");
for (ObjectMonitor * n = gOmInUseList; n != NULL; n = n->FreeNext) {
const oop obj = (oop) n->object();
const markOop mark = n->header();
ResourceMark rm;
! out->print_cr(INTPTR_FORMAT " %d%d%d %7d " INTPTR_FORMAT " %s",
! p2i(n), n->is_busy() != 0, mark->hash() != 0,
! n->owner() != NULL, (int)n->ref_count(), p2i(obj),
! obj->klass()->external_name());
}
}
if (!on_exit) {
Thread::muxRelease(&gListLock);
}
out->print_cr("In-use per-thread monitor info:");
out->print_cr("(B -> is_busy, H -> has hashcode, L -> lock status)");
! out->print_cr("%18s %18s %s %7s %18s %18s",
! "jt", "monitor", "BHL", "ref_cnt", "object", "object type");
! out->print_cr("================== ================== === ======= ================== ==================");
for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
for (ObjectMonitor * n = jt->omInUseList; n != NULL; n = n->FreeNext) {
const oop obj = (oop) n->object();
const markOop mark = n->header();
ResourceMark rm;
! out->print_cr(INTPTR_FORMAT " " INTPTR_FORMAT " %d%d%d %7d "
! INTPTR_FORMAT " %s", p2i(jt), p2i(n), n->is_busy() != 0,
! mark->hash() != 0, n->owner() != NULL, (int)n->ref_count(),
! p2i(obj), obj->klass()->external_name());
}
}
out->flush();
}
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