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src/hotspot/share/runtime/synchronizer.cpp
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rev 56044 : imported patch 8230184.patch
rev 56046 : v2.00 -> v2.05 (CR5/v2.05/8-for-jdk13) patches combined into one; merge with 8229212.patch; merge with jdk-14+11; merge with 8230184.patch.
*** 123,132 ****
--- 123,135 ----
ObjectMonitor* volatile ObjectSynchronizer::g_free_list = NULL;
// Global ObjectMonitor in-use list. When a JavaThread is exiting,
// ObjectMonitors on its per-thread in-use list are prepended here.
ObjectMonitor* volatile ObjectSynchronizer::g_om_in_use_list = NULL;
int ObjectSynchronizer::g_om_in_use_count = 0; // # on g_om_in_use_list
+ bool volatile ObjectSynchronizer::_is_async_deflation_requested = false;
+ bool volatile ObjectSynchronizer::_is_special_deflation_requested = false;
+ jlong ObjectSynchronizer::_last_async_deflation_time_ns = 0;
static volatile intptr_t gListLock = 0; // protects global monitor lists
static volatile int g_om_free_count = 0; // # on g_free_list
static volatile int g_om_population = 0; // # Extant -- in circulation
*** 209,222 ****
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 markWord 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
--- 212,233 ----
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 markWord 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
*** 242,251 ****
--- 253,274 ----
if (owner == NULL && Atomic::replace_if_null(self, &(m->_owner))) {
assert(m->_recursions == 0, "invariant");
return true;
}
+
+ if (AsyncDeflateIdleMonitors &&
+ Atomic::cmpxchg(self, &m->_owner, DEFLATER_MARKER) == DEFLATER_MARKER) {
+ // The deflation protocol finished the first part (setting owner),
+ // but it failed the second part (making ref_count negative) and
+ // bailed. Or the ObjectMonitor was async deflated and reused.
+ // Acquired the monitor.
+ assert(m->_recursions == 0, "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:
*** 325,335 ****
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
--- 348,360 ----
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
*** 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(markWord::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
--- 383,395 ----
// 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(markWord::unused_mark());
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_monitor_enter);
! 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) {
--- 414,439 ----
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");
}
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_vm_internal);
! 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) {
--- 441,453 ----
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);
! ObjectMonitorHandle omh;
! inflate(&omh, THREAD, obj(), inflate_cause_jni_enter);
! 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. We
// intentionally do not use CHECK here because we must exit the
// monitor even if an exception is pending.
if (monitor->check_owner(THREAD)) {
monitor->exit(true, THREAD);
--- 456,468 ----
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. We
// intentionally do not use CHECK here because we must exit the
// monitor even if an exception is pending.
if (monitor->check_owner(THREAD)) {
monitor->exit(true, THREAD);
*** 467,497 ****
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::wait_uninterruptibly(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);
--- 499,534 ----
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::wait_uninterruptibly(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);
*** 500,510 ****
markWord 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) {
--- 537,549 ----
markWord 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) {
*** 514,524 ****
markWord 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
//
--- 553,565 ----
markWord 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
//
*** 708,717 ****
--- 749,759 ----
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
self->is_Java_thread() , "invariant");
assert(Universe::verify_in_progress() || DumpSharedSpaces ||
((JavaThread *)self)->thread_state() != _thread_blocked, "invariant");
+ while (true) {
ObjectMonitor* monitor = NULL;
markWord temp, test;
intptr_t hash;
markWord mark = read_stable_mark(obj);
*** 732,742 ****
}
// 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, temp.value());
hash = temp.hash();
if (hash != 0) {
return hash;
--- 774,790 ----
}
// 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");
! continue;
! }
! monitor = omh.om_ptr();
temp = monitor->header();
assert(temp.is_neutral(), "invariant: header=" INTPTR_FORMAT, temp.value());
hash = temp.hash();
if (hash != 0) {
return hash;
*** 758,768 ****
// during an inflate() call so any change to that stack memory
// 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, mark.value());
hash = mark.hash();
if (hash == 0) {
--- 806,818 ----
// during an inflate() call so any change to that stack memory
// 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, mark.value());
hash = mark.hash();
if (hash == 0) {
*** 774,790 ****
--- 824,845 ----
if (test != mark) {
// The only non-deflation update to the ObjectMonitor's
// header/dmw field is to merge in the hash code. If someone
// adds a new usage of the header/dmw field, please update
// this code.
+ // ObjectMonitor::install_displaced_markword_in_object()
+ // does mark the header/dmw field as part of async deflation,
+ // but that protocol cannot happen now due to the
+ // ObjectMonitorHandle above.
hash = test.hash();
assert(test.is_neutral(), "invariant: header=" INTPTR_FORMAT, test.value());
assert(hash != 0, "Trivial unexpected object/monitor header usage.");
}
}
// We finally get the hash
return hash;
+ }
}
// Deprecated -- use FastHashCode() instead.
intptr_t ObjectSynchronizer::identity_hash_value_for(Handle obj) {
*** 800,823 ****
}
assert(thread == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
markWord mark = read_stable_mark(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
--- 855,886 ----
}
assert(thread == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
+ while (true) {
markWord mark = read_stable_mark(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
*** 839,869 ****
"biases should be revoked by now");
}
assert(self == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
markWord mark = read_stable_mark(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) {
--- 902,942 ----
"biases should be revoked by now");
}
assert(self == JavaThread::current(), "Can only be called on current thread");
oop obj = h_obj();
+
+ while (true) {
markWord mark = read_stable_mark(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) {
*** 874,895 ****
}
assert(!h_obj->mark().has_bias_pattern(), "biases should be revoked by now");
}
oop obj = h_obj();
- address owner = NULL;
markWord mark = read_stable_mark(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) {
--- 947,975 ----
}
assert(!h_obj->mark().has_bias_pattern(), "biases should be revoked by now");
}
oop obj = h_obj();
+ while (true) {
+ address owner = NULL;
markWord mark = read_stable_mark(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) {
*** 901,923 ****
// 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) {
PaddedObjectMonitor* block = OrderAccess::load_acquire(&g_block_list);
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) {
// Only process with closure if the object is set.
closure->do_monitor(mid);
}
}
block = (PaddedObjectMonitor*)block->_next_om;
}
--- 981,1013 ----
// 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) {
PaddedObjectMonitor* block = OrderAccess::load_acquire(&g_block_list);
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 = (PaddedObjectMonitor*)block->_next_om;
}
*** 925,946 ****
static bool monitors_used_above_threshold() {
if (g_om_population == 0) {
return false;
}
int monitors_used = g_om_population - g_om_free_count;
int monitor_usage = (monitors_used * 100LL) / g_om_population;
return monitor_usage > MonitorUsedDeflationThreshold;
}
! bool ObjectSynchronizer::is_cleanup_needed() {
! if (MonitorUsedDeflationThreshold > 0) {
! return monitors_used_above_threshold();
}
return false;
}
void ObjectSynchronizer::oops_do(OopClosure* f) {
// We only scan the global used list here (for moribund threads), and
// the thread-local monitors in Thread::oops_do().
global_used_oops_do(f);
}
--- 1015,1084 ----
static bool monitors_used_above_threshold() {
if (g_om_population == 0) {
return false;
}
+ if (MonitorUsedDeflationThreshold > 0) {
int monitors_used = g_om_population - g_om_free_count;
int monitor_usage = (monitors_used * 100LL) / g_om_population;
return monitor_usage > MonitorUsedDeflationThreshold;
+ }
+ return false;
}
! // Returns true if MonitorBound is set (> 0) and if the specified
! // cnt is > MonitorBound. Otherwise returns false.
! static bool is_MonitorBound_exceeded(const int cnt) {
! const int mx = MonitorBound;
! return mx > 0 && cnt > mx;
! }
!
! bool ObjectSynchronizer::is_async_deflation_needed() {
! if (!AsyncDeflateIdleMonitors) {
! return false;
! }
! if (is_async_deflation_requested()) {
! // Async deflation request.
! return true;
! }
! if (AsyncDeflationInterval > 0 &&
! time_since_last_async_deflation_ms() > AsyncDeflationInterval &&
! monitors_used_above_threshold()) {
! // It's been longer than our specified deflate interval and there
! // are too many monitors in use. We don't deflate more frequently
! // than AsyncDeflationInterval (unless is_async_deflation_requested)
! // in order to not swamp the ServiceThread.
! _last_async_deflation_time_ns = os::javaTimeNanos();
! return true;
! }
! if (is_MonitorBound_exceeded(g_om_population - g_om_free_count)) {
! // Not enough ObjectMonitors on the global free list.
! return true;
}
return false;
}
+ bool ObjectSynchronizer::is_safepoint_deflation_needed() {
+ if (!AsyncDeflateIdleMonitors) {
+ if (monitors_used_above_threshold()) {
+ // Too many monitors in use.
+ return true;
+ }
+ return false;
+ }
+ if (is_special_deflation_requested()) {
+ // For AsyncDeflateIdleMonitors only do a safepoint deflation
+ // if there is a special deflation request.
+ return true;
+ }
+ return false;
+ }
+
+ jlong ObjectSynchronizer::time_since_last_async_deflation_ms() {
+ return (os::javaTimeNanos() - _last_async_deflation_time_ns) / (NANOUNITS / MILLIUNITS);
+ }
+
void ObjectSynchronizer::oops_do(OopClosure* f) {
// We only scan the global used list here (for moribund threads), and
// the thread-local monitors in Thread::oops_do().
global_used_oops_do(f);
}
*** 988,997 ****
--- 1126,1136 ----
// Constraining monitor pool growth via MonitorBound ...
//
// If MonitorBound is not set (<= 0), MonitorBound checks are disabled.
//
+ // When safepoint deflation is being used (!AsyncDeflateIdleMonitors):
// The monitor pool is grow-only. We scavenge at STW safepoint-time, but the
// the rate of scavenging is driven primarily by GC. As such, we can find
// an inordinate number of monitors in circulation.
// To avoid that scenario we can artificially induce a STW safepoint
// if the pool appears to be growing past some reasonable bound.
*** 1002,1018 ****
// we'll incur more safepoints, which are harmful to performance.
// See also: GuaranteedSafepointInterval
//
// The current implementation uses asynchronous VM operations.
//
! // If MonitorBound is set, the boundry applies to
// (g_om_population - g_om_free_count)
// i.e., if there are not enough ObjectMonitors on the global free list,
// then a safepoint deflation is induced. Picking a good MonitorBound value
// is non-trivial.
static void InduceScavenge(Thread* self, const char * Whence) {
// Induce STW safepoint to trim monitors
// Ultimately, this results in a call to deflate_idle_monitors() in the near future.
// More precisely, trigger an asynchronous STW safepoint as the number
// of active monitors passes the specified threshold.
// TODO: assert thread state is reasonable
--- 1141,1170 ----
// we'll incur more safepoints, which are harmful to performance.
// See also: GuaranteedSafepointInterval
//
// The current implementation uses asynchronous VM operations.
//
! // When safepoint deflation is being used and MonitorBound is set, the
! // boundry applies to
// (g_om_population - g_om_free_count)
// i.e., if there are not enough ObjectMonitors on the global free list,
// then a safepoint deflation is induced. Picking a good MonitorBound value
// is non-trivial.
+ //
+ // When async deflation is being used:
+ // The monitor pool is still grow-only. Async deflation is requested
+ // by a safepoint's cleanup phase or by the ServiceThread at periodic
+ // intervals when is_async_deflation_needed() returns true. In
+ // addition to other policies that are checked, if there are not
+ // enough ObjectMonitors on the global free list, then
+ // is_async_deflation_needed() will return true. The ServiceThread
+ // calls deflate_global_idle_monitors_using_JT() and also sets the
+ // per-thread om_request_deflation flag as needed.
static void InduceScavenge(Thread* self, const char * Whence) {
+ assert(!AsyncDeflateIdleMonitors, "is not used by async deflation");
+
// Induce STW safepoint to trim monitors
// Ultimately, this results in a call to deflate_idle_monitors() in the near future.
// More precisely, trigger an asynchronous STW safepoint as the number
// of active monitors passes the specified threshold.
// TODO: assert thread state is reasonable
*** 1024,1040 ****
// The VMThread will delete the op when completed.
VMThread::execute(new VM_ScavengeMonitors());
}
}
! ObjectMonitor* ObjectSynchronizer::om_alloc(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;
stringStream ss;
for (;;) {
ObjectMonitor* m;
// 1: try to allocate from the thread's local om_free_list.
--- 1176,1210 ----
// The VMThread will delete the op when completed.
VMThread::execute(new VM_ScavengeMonitors());
}
}
! ObjectMonitor* ObjectSynchronizer::om_alloc(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->om_request_deflation && jt->om_in_use_count > 0 &&
+ cause != inflate_cause_vm_internal) {
+ // Deflate any per-thread idle monitors for this JavaThread if
+ // this is not an internal inflation; internal inflations can
+ // occur in places where it is not safe to pause for a safepoint.
+ // Clean up your own mess (Gibbs Rule 45). Otherwise, skip this
+ // deflation. deflate_global_idle_monitors_using_JT() is called
+ // by the ServiceThread. Per-thread async deflation is triggered
+ // by the ServiceThread via om_request_deflation.
+ debug_only(jt->check_for_valid_safepoint_state(false);)
+ ObjectSynchronizer::deflate_per_thread_idle_monitors_using_JT();
+ }
+ }
+
stringStream ss;
for (;;) {
ObjectMonitor* m;
// 1: try to allocate from the thread's local om_free_list.
*** 1046,1055 ****
--- 1216,1226 ----
m = self->om_free_list;
if (m != NULL) {
self->om_free_list = m->_next_om;
self->om_free_count--;
guarantee(m->object() == NULL, "invariant");
+ m->set_allocation_state(ObjectMonitor::New);
m->_next_om = self->om_in_use_list;
self->om_in_use_list = m;
self->om_in_use_count++;
return m;
}
*** 1067,1085 ****
for (int i = self->om_free_provision; --i >= 0 && g_free_list != NULL;) {
g_om_free_count--;
ObjectMonitor* take = g_free_list;
g_free_list = take->_next_om;
guarantee(take->object() == NULL, "invariant");
take->Recycle();
om_release(self, take, false);
}
Thread::muxRelease(&gListLock);
self->om_free_provision += 1 + (self->om_free_provision/2);
if (self->om_free_provision > MAXPRIVATE) self->om_free_provision = MAXPRIVATE;
! const int mx = MonitorBound;
! if (mx > 0 && (g_om_population-g_om_free_count) > mx) {
// Not enough ObjectMonitors on the global free list.
// We can't safely induce a STW safepoint from om_alloc() as our thread
// state may not be appropriate for such activities and callers may hold
// naked oops, so instead we defer the action.
InduceScavenge(self, "om_alloc");
--- 1238,1273 ----
for (int i = self->om_free_provision; --i >= 0 && g_free_list != NULL;) {
g_om_free_count--;
ObjectMonitor* take = g_free_list;
g_free_list = take->_next_om;
guarantee(take->object() == NULL, "invariant");
+ if (AsyncDeflateIdleMonitors) {
+ // We allowed 3 field values to linger during async deflation.
+ // We clear header and restore ref_count here, but we leave
+ // owner == DEFLATER_MARKER so the simple C2 ObjectMonitor
+ // enter optimization can no longer race with async deflation
+ // and reuse.
+ take->set_header(markWord::zero());
+ if (take->ref_count() < 0) {
+ // Add back max_jint to restore the ref_count field to its
+ // proper value.
+ Atomic::add(max_jint, &take->_ref_count);
+
+ assert(take->ref_count() >= 0, "must not be negative: ref_count=%d",
+ take->ref_count());
+ }
+ }
take->Recycle();
+ assert(take->is_free(), "invariant");
om_release(self, take, false);
}
Thread::muxRelease(&gListLock);
self->om_free_provision += 1 + (self->om_free_provision/2);
if (self->om_free_provision > MAXPRIVATE) self->om_free_provision = MAXPRIVATE;
! if (!AsyncDeflateIdleMonitors &&
! is_MonitorBound_exceeded(g_om_population - g_om_free_count)) {
// Not enough ObjectMonitors on the global free list.
// We can't safely induce a STW safepoint from om_alloc() as our thread
// state may not be appropriate for such activities and callers may hold
// naked oops, so instead we defer the action.
InduceScavenge(self, "om_alloc");
*** 1120,1129 ****
--- 1308,1318 ----
// 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]._next_om = (ObjectMonitor *)&temp[i+1];
+ assert(temp[i].is_free(), "invariant");
}
// terminate the last monitor as the end of list
temp[_BLOCKSIZE - 1]._next_om = NULL;
*** 1162,1182 ****
// a CAS 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 while we
! // are trying to release them.
void ObjectSynchronizer::om_release(Thread* self, ObjectMonitor* m,
bool from_per_thread_alloc) {
guarantee(m->header().value() == 0, "invariant");
guarantee(m->object() == NULL, "invariant");
stringStream ss;
guarantee((m->is_busy() | m->_recursions) == 0, "freeing in-use monitor: "
"%s, recursions=" INTPTR_FORMAT, m->is_busy_to_string(&ss),
m->_recursions);
// _next_om is used for both per-thread in-use and free lists so
// we have to remove 'm' from the in-use list first (as needed).
if (from_per_thread_alloc) {
// Need to remove 'm' from om_in_use_list.
ObjectMonitor* cur_mid_in_use = NULL;
--- 1351,1372 ----
// a CAS 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::om_release(Thread* self, ObjectMonitor* m,
bool from_per_thread_alloc) {
guarantee(m->header().value() == 0, "invariant");
guarantee(m->object() == NULL, "invariant");
stringStream ss;
guarantee((m->is_busy() | m->_recursions) == 0, "freeing in-use monitor: "
"%s, recursions=" INTPTR_FORMAT, m->is_busy_to_string(&ss),
m->_recursions);
+ m->set_allocation_state(ObjectMonitor::Free);
// _next_om is used for both per-thread in-use and free lists so
// we have to remove 'm' from the in-use list first (as needed).
if (from_per_thread_alloc) {
// Need to remove 'm' from om_in_use_list.
ObjectMonitor* cur_mid_in_use = NULL;
*** 1196,1205 ****
--- 1386,1396 ----
}
assert(extracted, "Should have extracted from in-use list");
}
m->_next_om = self->om_free_list;
+ guarantee(m->is_free(), "invariant");
self->om_free_list = m;
self->om_free_count++;
}
// Return ObjectMonitors on a moribund thread's free and in-use
*** 1212,1221 ****
--- 1403,1416 ----
// a safepoint and interleave with deflate_idle_monitors(). In
// particular, this ensures that the thread's in-use monitors are
// scanned by a GC safepoint, either via Thread::oops_do() (before
// om_flush() is called) or via ObjectSynchronizer::oops_do() (after
// om_flush() is called).
+ //
+ // 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 om_flush() so we have to be careful.
void ObjectSynchronizer::om_flush(Thread* self) {
ObjectMonitor* free_list = self->om_free_list;
ObjectMonitor* free_tail = NULL;
int free_count = 0;
*** 1229,1239 ****
free_tail = s;
guarantee(s->object() == NULL, "invariant");
guarantee(!s->is_busy(), "must be !is_busy: %s", s->is_busy_to_string(&ss));
}
guarantee(free_tail != NULL, "invariant");
! assert(self->om_free_count == free_count, "free-count off");
self->om_free_list = NULL;
self->om_free_count = 0;
}
ObjectMonitor* in_use_list = self->om_in_use_list;
--- 1424,1434 ----
free_tail = s;
guarantee(s->object() == NULL, "invariant");
guarantee(!s->is_busy(), "must be !is_busy: %s", s->is_busy_to_string(&ss));
}
guarantee(free_tail != NULL, "invariant");
! ADIM_guarantee(self->om_free_count == free_count, "free-count off");
self->om_free_list = NULL;
self->om_free_count = 0;
}
ObjectMonitor* in_use_list = self->om_in_use_list;
*** 1246,1258 ****
// in-use list g_om_in_use_list below, under the gListLock.
ObjectMonitor *cur_om;
for (cur_om = in_use_list; cur_om != NULL; cur_om = cur_om->_next_om) {
in_use_tail = cur_om;
in_use_count++;
}
guarantee(in_use_tail != NULL, "invariant");
! assert(self->om_in_use_count == in_use_count, "in-use count off");
self->om_in_use_list = NULL;
self->om_in_use_count = 0;
}
Thread::muxAcquire(&gListLock, "om_flush");
--- 1441,1454 ----
// in-use list g_om_in_use_list below, under the gListLock.
ObjectMonitor *cur_om;
for (cur_om = in_use_list; cur_om != NULL; cur_om = cur_om->_next_om) {
in_use_tail = cur_om;
in_use_count++;
+ ADIM_guarantee(cur_om->is_active(), "invariant");
}
guarantee(in_use_tail != NULL, "invariant");
! ADIM_guarantee(self->om_in_use_count == in_use_count, "in-use count off");
self->om_in_use_list = NULL;
self->om_in_use_count = 0;
}
Thread::muxAcquire(&gListLock, "om_flush");
*** 1296,1318 ****
event->set_cause((u1)cause);
event->commit();
}
// Fast path code shared by multiple functions
! void ObjectSynchronizer::inflate_helper(oop obj) {
markWord 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");
--- 1492,1523 ----
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) {
markWord 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");
! markWord dmw = monitor->header();
! assert(dmw.is_neutral(), "sanity check: header=" INTPTR_FORMAT, dmw.value());
! 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");
*** 1329,1344 ****
// * Neutral - aggressively inflate the object.
// * BIASED - Illegal. We should never see this
// CASE: inflated
if (mark.has_monitor()) {
! ObjectMonitor* inf = mark.monitor();
markWord dmw = inf->header();
assert(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
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.
--- 1534,1554 ----
// * 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();
markWord dmw = inf->header();
assert(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
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.
*** 1370,1380 ****
// See the comments in om_alloc().
LogStreamHandle(Trace, monitorinflation) lsh;
if (mark.has_locker()) {
! ObjectMonitor* m = om_alloc(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;
--- 1580,1601 ----
// See the comments in om_alloc().
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 om_alloc.
! m = om_alloc(self, cause);
! } else {
! // If AsyncDeflateIdleMonitors and not an internal inflation, then
! // we may stop for a safepoint in om_alloc() so protect object.
! Handle h_obj(self, object);
! m = om_alloc(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;
*** 1417,1427 ****
// object is in the mark. Furthermore the owner can't complete
// an unlock on the object, either.
markWord dmw = mark.displaced_mark_helper();
// Catch if the object's header is not neutral (not locked and
// not marked is what we care about here).
! assert(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
// Setup monitor fields to proper values -- prepare the monitor
m->set_header(dmw);
// Optimization: if the mark.locker stack address is associated
--- 1638,1648 ----
// object is in the mark. Furthermore the owner can't complete
// an unlock on the object, either.
markWord dmw = mark.displaced_mark_helper();
// Catch if the object's header is not neutral (not locked and
// not marked is what we care about here).
! ADIM_guarantee(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
// Setup monitor fields to proper values -- prepare the monitor
m->set_header(dmw);
// Optimization: if the mark.locker stack address is associated
*** 1431,1440 ****
--- 1652,1665 ----
// with CAS. That is, we can avoid the xchg-NULL .... ST idiom.
m->set_owner(mark.locker());
m->set_object(object);
// TODO-FIXME: assert BasicLock->dhw != 0.
+ omh_p->set_om_ptr(m);
+ assert(m->is_new(), "freshly allocated monitor must be new");
+ m->set_allocation_state(ObjectMonitor::Old);
+
// Must preserve store ordering. The monitor state must
// be stable at the time of publishing the monitor address.
guarantee(object->mark() == markWord::INFLATING(), "invariant");
object->release_set_mark(markWord::encode(m));
*** 1448,1458 ****
object->mark().value(), 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
--- 1673,1684 ----
object->mark().value(), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! ADIM_guarantee(!m->is_free(), "inflated monitor to be returned cannot be free");
! 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
*** 1463,1485 ****
// An inflateTry() method that we could call from fast_enter() and slow_enter()
// would be useful.
// Catch if the object's header is not neutral (not locked and
// not marked is what we care about here).
! assert(mark.is_neutral(), "invariant: header=" INTPTR_FORMAT, mark.value());
! ObjectMonitor* m = om_alloc(self);
// prepare m for installation - set monitor to initial state
m->Recycle();
m->set_header(mark);
m->set_object(object);
m->_Responsible = NULL;
m->_SpinDuration = ObjectMonitor::Knob_SpinLimit; // consider: keep metastats by type/class
if (object->cas_set_mark(markWord::encode(m), mark) != mark) {
m->set_header(markWord::zero());
m->set_object(NULL);
m->Recycle();
om_release(self, m, true);
m = NULL;
continue;
// interference - the markword changed - just retry.
// The state-transitions are one-way, so there's no chance of
--- 1689,1731 ----
// An inflateTry() method that we could call from fast_enter() and slow_enter()
// would be useful.
// Catch if the object's header is not neutral (not locked and
// not marked is what we care about here).
! ADIM_guarantee(mark.is_neutral(), "invariant: header=" INTPTR_FORMAT, mark.value());
! 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 om_alloc.
! m = om_alloc(self, cause);
! } else {
! // If AsyncDeflateIdleMonitors and not an internal inflation, then
! // we may stop for a safepoint in om_alloc() so protect object.
! Handle h_obj(self, object);
! m = om_alloc(self, cause);
! object = h_obj(); // Refresh object.
! }
// prepare m for installation - set monitor to initial state
m->Recycle();
m->set_header(mark);
+ // If we leave _owner == DEFLATER_MARKER here, then the simple C2
+ // ObjectMonitor enter optimization can no longer race with async
+ // deflation and reuse.
m->set_object(object);
m->_Responsible = NULL;
m->_SpinDuration = ObjectMonitor::Knob_SpinLimit; // consider: keep metastats by type/class
+ omh_p->set_om_ptr(m);
+ assert(m->is_new(), "freshly allocated monitor must be new");
+ m->set_allocation_state(ObjectMonitor::Old);
+
if (object->cas_set_mark(markWord::encode(m), mark) != mark) {
m->set_header(markWord::zero());
m->set_object(NULL);
m->Recycle();
+ omh_p->set_om_ptr(NULL);
+ // om_release() will reset the allocation state
om_release(self, m, true);
m = NULL;
continue;
// interference - the markword changed - just retry.
// The state-transitions are one-way, so there's no chance of
*** 1496,1512 ****
object->mark().value(), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! return m;
}
}
// We maintain a list of in-use monitors for each thread.
//
// deflate_thread_local_monitors() scans a single thread's in-use list, while
// deflate_idle_monitors() scans only a global list of in-use monitors which
// is populated only as a thread dies (see om_flush()).
//
// These operations are called at all safepoints, immediately after mutators
--- 1742,1760 ----
object->mark().value(), object->klass()->external_name());
}
if (event.should_commit()) {
post_monitor_inflate_event(&event, object, cause);
}
! ADIM_guarantee(!m->is_free(), "inflated monitor to be returned cannot be free");
! return;
}
}
// We maintain a list of in-use monitors for each thread.
//
+ // For safepoint based deflation:
// deflate_thread_local_monitors() scans a single thread's in-use list, while
// deflate_idle_monitors() scans only a global list of in-use monitors which
// is populated only as a thread dies (see om_flush()).
//
// These operations are called at all safepoints, immediately after mutators
*** 1521,1530 ****
--- 1769,1803 ----
//
// 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.
+ //
+ // For async deflation:
+ // If a special deflation request is made, then the safepoint based
+ // deflation mechanism is used. Otherwise, an async deflation request
+ // is registered with the ServiceThread and it is notified.
+
+ void ObjectSynchronizer::do_safepoint_work(DeflateMonitorCounters* _counters) {
+ assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+
+ // The per-thread in-use lists are handled in
+ // ParallelSPCleanupThreadClosure::do_thread().
+
+ if (!AsyncDeflateIdleMonitors || is_special_deflation_requested()) {
+ // Use the older mechanism for the global in-use list or if a
+ // special deflation has been requested before the safepoint.
+ ObjectSynchronizer::deflate_idle_monitors(_counters);
+ return;
+ }
+
+ log_debug(monitorinflation)("requesting async deflation of idle monitors.");
+ // Request deflation of idle monitors by the ServiceThread:
+ set_is_async_deflation_requested(true);
+ MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
+ ml.notify_all();
+ }
// 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** free_head_p,
*** 1539,1549 ****
guarantee(mark.monitor() == mid, "should match: monitor()=" INTPTR_FORMAT
", mid=" INTPTR_FORMAT, p2i(mark.monitor()), p2i(mid));
const markWord dmw = mid->header();
guarantee(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
! if (mid->is_busy()) {
deflated = false;
} else {
// Deflate the monitor if it is no longer being used
// It's idle - scavenge and return to the global free list
// plain old deflation ...
--- 1812,1824 ----
guarantee(mark.monitor() == mid, "should match: monitor()=" INTPTR_FORMAT
", mid=" INTPTR_FORMAT, p2i(mark.monitor()), p2i(mid));
const markWord dmw = mid->header();
guarantee(dmw.is_neutral(), "invariant: header=" INTPTR_FORMAT, dmw.value());
! if (mid->is_busy() || mid->ref_count() != 0) {
! // Easy checks are first - the ObjectMonitor is busy or ObjectMonitor*
! // is in use so no deflation.
deflated = false;
} else {
// Deflate the monitor if it is no longer being used
// It's idle - scavenge and return to the global free list
// plain old deflation ...
*** 1555,1568 ****
--- 1830,1850 ----
mark.value(), obj->klass()->external_name());
}
// Restore the header back to obj
obj->release_set_mark(dmw);
+ if (AsyncDeflateIdleMonitors) {
+ // clear() expects the owner field to be NULL and we won't race
+ // with the simple C2 ObjectMonitor enter optimization since
+ // we're at a safepoint.
+ mid->set_owner(NULL);
+ }
mid->clear();
assert(mid->object() == NULL, "invariant: object=" INTPTR_FORMAT,
p2i(mid->object()));
+ assert(mid->is_free(), "invariant");
// Move the deflated ObjectMonitor to the working free list
// defined by free_head_p and free_tail_p.
if (*free_head_p == NULL) *free_head_p = mid;
if (*free_tail_p != NULL) {
*** 1581,1590 ****
--- 1863,2012 ----
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 ref_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 or to a thread that just
+ // wants to use the ObjectMonitor*.
+ //
+ // The ObjectMonitor has been successfully async deflated when:
+ // (owner == DEFLATER_MARKER && ref_count < 0)
+ // Contending threads or ObjectMonitor* using threads that see those
+ // values know to retry their operation.
+ //
+ bool ObjectSynchronizer::deflate_monitor_using_JT(ObjectMonitor* mid,
+ ObjectMonitor** free_head_p,
+ ObjectMonitor** free_tail_p) {
+ 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(), "must be old: allocation_state=%d",
+ (int) mid->allocation_state());
+
+ 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::replace_if_null(DEFLATER_MARKER, &(mid->_owner))) {
+ // 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->_contentions != 0 || mid->_waiters != 0) {
+ // Another thread has raced to enter the ObjectMonitor after
+ // mid->is_busy() above or has already entered and waited on
+ // it which makes it busy so no deflation. 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->_ref_count, (jint)0) == 0) {
+ // Make ref_count negative to force any contending threads or
+ // ObjectMonitor* using threads to retry. This is the second
+ // part of the async deflation dance.
+
+ if (mid->owner_is_DEFLATER_MARKER()) {
+ // If owner is still DEFLATER_MARKER, then we have successfully
+ // signaled any contending threads to retry. If it is not, then we
+ // have lost the race to an entering 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 ref_count
+ // where another thread acquired the ObjectMonitor, finished
+ // using it and restored the ref_count to zero.
+
+ // Sanity checks for the races:
+ guarantee(mid->_contentions == 0, "must be 0: contentions=%d",
+ mid->_contentions);
+ guarantee(mid->_waiters == 0, "must be 0: waiters=%d", mid->_waiters);
+ guarantee(mid->_cxq == NULL, "must be no contending threads: cxq="
+ INTPTR_FORMAT, p2i(mid->_cxq));
+ guarantee(mid->_EntryList == NULL,
+ "must be no entering threads: EntryList=" INTPTR_FORMAT,
+ p2i(mid->_EntryList));
+
+ const oop obj = (oop) mid->object();
+ if (log_is_enabled(Trace, monitorinflation)) {
+ ResourceMark rm;
+ log_trace(monitorinflation)("deflate_monitor_using_JT: "
+ "object=" INTPTR_FORMAT ", mark="
+ INTPTR_FORMAT ", type='%s'",
+ p2i(obj), obj->mark().value(),
+ obj->klass()->external_name());
+ }
+
+ // Install the old mark word if nobody else has already done it.
+ mid->install_displaced_markword_in_object(obj);
+ mid->clear_using_JT();
+
+ assert(mid->object() == NULL, "must be NULL: object=" INTPTR_FORMAT,
+ p2i(mid->object()));
+ assert(mid->is_free(), "must be free: allocation_state=%d",
+ (int) mid->allocation_state());
+
+ // Move the deflated ObjectMonitor to the working free list
+ // defined by free_head_p and free_tail_p.
+ if (*free_head_p == NULL) {
+ // First one on the list.
+ *free_head_p = mid;
+ }
+ if (*free_tail_p != NULL) {
+ // We append to the list so the caller can use mid->_next_om
+ // to fix the linkages in its context.
+ ObjectMonitor* prevtail = *free_tail_p;
+ // Should have been cleaned up by the caller:
+ assert(prevtail->_next_om == NULL, "must be NULL: _next_om="
+ INTPTR_FORMAT, p2i(prevtail->_next_om));
+ prevtail->_next_om = mid;
+ }
+ *free_tail_p = mid;
+
+ // At this point, mid->_next_om still refers to its current
+ // value and another ObjectMonitor's _next_om 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 ref_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 ref_count field to its
+ // proper value (which may not be what we saw above):
+ Atomic::add(max_jint, &mid->_ref_count);
+
+ assert(mid->ref_count() >= 0, "must not be negative: ref_count=%d",
+ mid->ref_count());
+ return false;
+ }
+
+ // The ref_count was no longer 0 so we lost the race since the
+ // ObjectMonitor is now busy or the ObjectMonitor* is now is use.
+ // Restore owner to NULL if it is still DEFLATER_MARKER:
+ Atomic::cmpxchg((void*)NULL, &mid->_owner, DEFLATER_MARKER);
+ }
+
+ // 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,
*** 1625,1644 ****
--- 2047,2151 ----
}
}
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 saved_mid_in_use_p and return to the caller to
+ // honor the safepoint.
+ //
+ int ObjectSynchronizer::deflate_monitor_list_using_JT(ObjectMonitor** list_p,
+ ObjectMonitor** free_head_p,
+ ObjectMonitor** free_tail_p,
+ ObjectMonitor** saved_mid_in_use_p) {
+ 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 (*saved_mid_in_use_p == NULL) {
+ // No saved state so start at the beginning.
+ mid = *list_p;
+ } else {
+ // We're restarting after a safepoint so restore the necessary state
+ // before we resume.
+ cur_mid_in_use = *saved_mid_in_use_p;
+ mid = cur_mid_in_use->_next_om;
+ }
+ 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, free_head_p, free_tail_p)) {
+ // Deflation succeeded so update the in-use list.
+ if (mid == *list_p) {
+ *list_p = mid->_next_om;
+ } else if (cur_mid_in_use != NULL) {
+ // Maintain the current in-use list.
+ cur_mid_in_use->_next_om = mid->_next_om;
+ }
+ next = mid->_next_om;
+ mid->_next_om = NULL;
+ // At this point mid is disconnected from the in-use list
+ // and is the current tail in the free_head_p 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 om_alloc() (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
+ // om_alloc() is released by om_release() due to losing the race
+ // in inflate().
+
+ cur_mid_in_use = mid;
+ mid = mid->_next_om;
+
+ if (SafepointSynchronize::is_synchronizing() &&
+ cur_mid_in_use != *list_p && 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.
+ *saved_mid_in_use_p = cur_mid_in_use;
+ return deflated_count;
+ }
+ }
+ }
+ // We finished the list without a safepoint starting so there's
+ // no need to save state.
+ *saved_mid_in_use_p = NULL;
+ return deflated_count;
+ }
+
void ObjectSynchronizer::prepare_deflate_idle_monitors(DeflateMonitorCounters* counters) {
counters->n_in_use = 0; // currently associated with objects
counters->n_in_circulation = 0; // extant
counters->n_scavenged = 0; // reclaimed (global and per-thread)
counters->per_thread_scavenged = 0; // per-thread scavenge total
counters->per_thread_times = 0.0; // per-thread scavenge times
}
void ObjectSynchronizer::deflate_idle_monitors(DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+
+ if (AsyncDeflateIdleMonitors) {
+ // Nothing to do when global idle ObjectMonitors are deflated using
+ // a JavaThread unless a special deflation has been requested.
+ if (!is_special_deflation_requested()) {
+ return;
+ }
+ }
+
bool deflated = false;
ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors
ObjectMonitor* free_tail_p = NULL;
elapsedTimer timer;
*** 1687,1705 ****
--- 2194,2343 ----
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* self = JavaThread::current();
+
+ deflate_common_idle_monitors_using_JT(true /* is_global */, self);
+ }
+
+ // 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* self = JavaThread::current();
+
+ self->om_request_deflation = false;
+
+ deflate_common_idle_monitors_using_JT(false /* !is_global */, self);
+ }
+
+ // Deflate global or per-thread idle ObjectMonitors using a JavaThread.
+ //
+ void ObjectSynchronizer::deflate_common_idle_monitors_using_JT(bool is_global, JavaThread* self) {
+ int deflated_count = 0;
+ ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged ObjectMonitors
+ ObjectMonitor* free_tail_p = NULL;
+ ObjectMonitor* saved_mid_in_use_p = NULL;
+ elapsedTimer timer;
+
+ if (log_is_enabled(Info, monitorinflation)) {
+ timer.start();
+ }
+
+ if (is_global) {
+ Thread::muxAcquire(&gListLock, "deflate_global_idle_monitors_using_JT(1)");
+ OM_PERFDATA_OP(MonExtant, set_value(g_om_in_use_count));
+ } else {
+ OM_PERFDATA_OP(MonExtant, inc(self->om_in_use_count));
+ }
+
+ do {
+ int local_deflated_count;
+ if (is_global) {
+ local_deflated_count = deflate_monitor_list_using_JT((ObjectMonitor **)&g_om_in_use_list, &free_head_p, &free_tail_p, &saved_mid_in_use_p);
+ g_om_in_use_count -= local_deflated_count;
+ } else {
+ local_deflated_count = deflate_monitor_list_using_JT(self->om_in_use_list_addr(), &free_head_p, &free_tail_p, &saved_mid_in_use_p);
+ self->om_in_use_count -= local_deflated_count;
+ }
+ deflated_count += local_deflated_count;
+
+ if (free_head_p != NULL) {
+ // Move the scavenged ObjectMonitors to the global free list.
+ guarantee(free_tail_p != NULL && local_deflated_count > 0, "free_tail_p=" INTPTR_FORMAT ", local_deflated_count=%d", p2i(free_tail_p), local_deflated_count);
+ assert(free_tail_p->_next_om == NULL, "invariant");
+
+ if (!is_global) {
+ Thread::muxAcquire(&gListLock, "deflate_per_thread_idle_monitors_using_JT(2)");
+ }
+ // Constant-time list splice - prepend scavenged segment to g_free_list.
+ free_tail_p->_next_om = g_free_list;
+ g_free_list = free_head_p;
+
+ g_om_free_count += local_deflated_count;
+ OM_PERFDATA_OP(Deflations, inc(local_deflated_count));
+ if (!is_global) {
+ Thread::muxRelease(&gListLock);
+ }
+ }
+
+ if (saved_mid_in_use_p != NULL) {
+ // deflate_monitor_list_using_JT() detected a safepoint starting.
+ if (is_global) {
+ Thread::muxRelease(&gListLock);
+ }
+ timer.stop();
+ {
+ if (is_global) {
+ log_debug(monitorinflation)("pausing deflation of global idle monitors for a safepoint.");
+ } else {
+ log_debug(monitorinflation)("jt=" INTPTR_FORMAT ": pausing deflation of per-thread idle monitors for a safepoint.", p2i(self));
+ }
+ assert(SafepointSynchronize::is_synchronizing(), "sanity check");
+ ThreadBlockInVM blocker(self);
+ }
+ // Prepare for another loop after the safepoint.
+ free_head_p = NULL;
+ free_tail_p = NULL;
+ if (log_is_enabled(Info, monitorinflation)) {
+ timer.start();
+ }
+ if (is_global) {
+ Thread::muxAcquire(&gListLock, "deflate_global_idle_monitors_using_JT(3)");
+ }
+ }
+ } while (saved_mid_in_use_p != NULL);
+ if (is_global) {
+ 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) {
+ if (is_global) {
+ ls->print_cr("async-deflating global idle monitors, %3.7f secs, %d monitors", timer.seconds(), deflated_count);
+ } else {
+ ls->print_cr("jt=" INTPTR_FORMAT ": async-deflating per-thread idle monitors, %3.7f secs, %d monitors", p2i(self), 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 deflation has been requested.
log_info(safepoint, cleanup)("deflating per-thread idle monitors, %3.7f secs, monitors=%d", counters->per_thread_times, counters->per_thread_scavenged);
+ bool needs_special_deflation = is_special_deflation_requested();
+ if (!AsyncDeflateIdleMonitors || needs_special_deflation) {
+ // AsyncDeflateIdleMonitors does not use these counters unless
+ // there is a special deflation request.
+
g_om_free_count += counters->n_scavenged;
+ OM_PERFDATA_OP(Deflations, inc(counters->n_scavenged));
+ OM_PERFDATA_OP(MonExtant, set_value(counters->n_in_circulation));
+ }
+
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)) {
*** 1709,1729 ****
g_om_in_use_count, g_om_free_count);
Thread::muxRelease(&gListLock);
}
ForceMonitorScavenge = 0; // Reset
-
- OM_PERFDATA_OP(Deflations, inc(counters->n_scavenged));
- OM_PERFDATA_OP(MonExtant, set_value(counters->n_in_circulation));
-
GVars.stw_random = os::random();
GVars.stw_cycle++;
}
void ObjectSynchronizer::deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors
ObjectMonitor* free_tail_p = NULL;
elapsedTimer timer;
if (log_is_enabled(Info, safepoint, cleanup) ||
--- 2347,2378 ----
g_om_in_use_count, g_om_free_count);
Thread::muxRelease(&gListLock);
}
ForceMonitorScavenge = 0; // Reset
GVars.stw_random = os::random();
GVars.stw_cycle++;
+ if (needs_special_deflation) {
+ set_is_special_deflation_requested(false); // special deflation is done
+ }
}
void ObjectSynchronizer::deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters) {
assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+ if (AsyncDeflateIdleMonitors) {
+ if (!is_special_deflation_requested()) {
+ // Mark the JavaThread for idle monitor deflation if a special
+ // deflation has NOT been requested.
+ if (thread->om_in_use_count > 0) {
+ // This JavaThread is using monitors so mark it.
+ thread->om_request_deflation = true;
+ }
+ return;
+ }
+ }
+
ObjectMonitor* free_head_p = NULL; // Local SLL of scavenged monitors
ObjectMonitor* free_tail_p = NULL;
elapsedTimer timer;
if (log_is_enabled(Info, safepoint, cleanup) ||
*** 1946,1962 ****
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must have NULL _header "
"field: _header=" INTPTR_FORMAT, p2i(jt), p2i(n),
n->header().value());
! } else {
out->print_cr("ERROR: monitor=" INTPTR_FORMAT ": free global monitor "
"must have NULL _header field: _header=" INTPTR_FORMAT,
p2i(n), n->header().value());
- }
*error_cnt_p = *error_cnt_p + 1;
}
if (n->object() != NULL) {
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must have NULL _object "
"field: _object=" INTPTR_FORMAT, p2i(jt), p2i(n),
--- 2595,2612 ----
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must have NULL _header "
"field: _header=" INTPTR_FORMAT, p2i(jt), p2i(n),
n->header().value());
! *error_cnt_p = *error_cnt_p + 1;
! } else if (!AsyncDeflateIdleMonitors) {
out->print_cr("ERROR: monitor=" INTPTR_FORMAT ": free global monitor "
"must have NULL _header field: _header=" INTPTR_FORMAT,
p2i(n), n->header().value());
*error_cnt_p = *error_cnt_p + 1;
}
+ }
if (n->object() != NULL) {
if (jt != NULL) {
out->print_cr("ERROR: jt=" INTPTR_FORMAT ", monitor=" INTPTR_FORMAT
": free per-thread monitor must have NULL _object "
"field: _object=" INTPTR_FORMAT, p2i(jt), p2i(n),
*** 2119,2138 ****
stringStream ss;
if (g_om_in_use_count > 0) {
out->print_cr("In-use global monitor info:");
out->print_cr("(B -> is_busy, H -> has hash code, L -> lock status)");
! out->print_cr("%18s %s %18s %18s",
! "monitor", "BHL", "object", "object type");
! out->print_cr("================== === ================== ==================");
for (ObjectMonitor* n = g_om_in_use_list; n != NULL; n = n->_next_om) {
const oop obj = (oop) n->object();
const markWord mark = n->header();
ResourceMark rm;
! out->print(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 (n->is_busy() != 0) {
out->print(" (%s)", n->is_busy_to_string(&ss));
ss.reset();
}
out->cr();
--- 2769,2789 ----
stringStream ss;
if (g_om_in_use_count > 0) {
out->print_cr("In-use global monitor info:");
out->print_cr("(B -> is_busy, H -> has hash code, L -> lock status)");
! out->print_cr("%18s %s %7s %18s %18s",
! "monitor", "BHL", "ref_cnt", "object", "object type");
! out->print_cr("================== === ======= ================== ==================");
for (ObjectMonitor* n = g_om_in_use_list; n != NULL; n = n->_next_om) {
const oop obj = (oop) n->object();
const markWord mark = n->header();
ResourceMark rm;
! out->print(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 (n->is_busy() != 0) {
out->print(" (%s)", n->is_busy_to_string(&ss));
ss.reset();
}
out->cr();
*** 2143,2164 ****
Thread::muxRelease(&gListLock);
}
out->print_cr("In-use per-thread monitor info:");
out->print_cr("(B -> is_busy, H -> has hash code, 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->om_in_use_list; n != NULL; n = n->_next_om) {
const oop obj = (oop) n->object();
const markWord mark = n->header();
ResourceMark rm;
! out->print(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());
if (n->is_busy() != 0) {
out->print(" (%s)", n->is_busy_to_string(&ss));
ss.reset();
}
out->cr();
--- 2794,2815 ----
Thread::muxRelease(&gListLock);
}
out->print_cr("In-use per-thread monitor info:");
out->print_cr("(B -> is_busy, H -> has hash code, 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->om_in_use_list; n != NULL; n = n->_next_om) {
const oop obj = (oop) n->object();
const markWord mark = n->header();
ResourceMark rm;
! out->print(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());
if (n->is_busy() != 0) {
out->print(" (%s)", n->is_busy_to_string(&ss));
ss.reset();
}
out->cr();
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