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src/hotspot/share/runtime/objectMonitor.cpp
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rev 56634 : imported patch 8230876.patch
rev 56635 : 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; merge with 8230876.patch; merge with jdk-14+15; merge with jdk-14+18.
rev 56637 : Add OM_CACHE_LINE_SIZE so that ObjectMonitor cache line sizes can be experimented with independently of DEFAULT_CACHE_LINE_SIZE; for SPARC and X64 configs that use 128 for DEFAULT_CACHE_LINE_SIZE, we are experimenting with 64; move _previous_owner_tid and _allocation_state fields to share the cache line with ObjectMonitor::_header; put ObjectMonitor::_ref_count on its own cache line after _owner; add 'int* count_p' parameter to deflate_monitor_list() and deflate_monitor_list_using_JT() and push counter updates down to where the ObjectMonitors are actually removed from the in-use lists; monitors_iterate() async deflation check should use negative ref_count; add 'JavaThread* target' param to deflate_per_thread_idle_monitors_using_JT() add deflate_common_idle_monitors_using_JT() to make it clear which JavaThread* is the target of the work and which is the calling JavaThread* (self); g_free_list, g_om_in_use_list and g_om_in_use_count are now static to synchronizer.cpp (reduce scope); add more diagnostic info to some assert()'s; minor code cleanups and code motion; save_om_ptr() should detect a race with a deflating thread that is bailing out and cause a retry when the ref_count field is not positive; merge with jdk-14+11; add special GC support for TestHumongousClassLoader.java; merge with 8230184.patch; merge with jdk-14+14; merge with jdk-14+18.
rev 56639 : loosen a couple more counter checks due to races observed in testing; simplify om_release() extraction of mid since list head or cur_mid_in_use is marked; simplify deflate_monitor_list() extraction of mid since there are no parallel deleters due to the safepoint; simplify deflate_monitor_list_using_JT() extraction of mid since list head or cur_mid_in_use is marked; prepend_block_to_lists() - simplify based on David H's comments; does not need load_acquire() or release_store() because of the cmpxchg(); prepend_to_common() - simplify to use mark_next_loop() for m and use mark_list_head() and release_store() for the non-empty list case; add more debugging for "Non-balanced monitor enter/exit" failure mode; fix race in inflate() in the "CASE: neutral" code path; install_displaced_markword_in_object() does not need to clear the header field since that is handled when the ObjectMonitor is moved from the global free list; LSuccess should clear boxReg to set ICC.ZF=1 to avoid depending on existing boxReg contents; update fast_unlock() to detect when object no longer refers to the same ObjectMonitor and take fast path exit instead; clarify fast_lock() code where we detect when object no longer refers to the same ObjectMonitor; add/update comments for movptr() calls where we move a literal into an Address; remove set_owner(); refactor setting of owner field into set_owner_from(2 versions), set_owner_from_BasicLock(), and try_set_owner_from(); the new functions include monitorinflation+owner logging; extract debug code from v2.06 and v2.07 and move to v2.07.debug; change 'jccb' -> 'jcc' and 'jmpb' -> 'jmp' as needed; checkpoint initial version of MacroAssembler::inc_om_ref_count(); update LP64 MacroAssembler::fast_lock() and fast_unlock() to use inc_om_ref_count(); fast_lock() return flag setting logic can use 'testptr(tmpReg, tmpReg)' instead of 'cmpptr(tmpReg, 0)' since that's more efficient; fast_unlock() LSuccess return flag setting logic can use 'testl (boxReg, 0)' instead of 'xorptr(boxReg, boxReg)' since that's more efficient; cleanup "fast-path" vs "fast path" and "slow-path" vs "slow path"; update MacroAssembler::rtm_inflated_locking() to use inc_om_ref_count(); update MacroAssembler::fast_lock() to preserve the flags before decrementing ref_count and restore the flags afterwards; this is more clean than depending on the contents of rax/tmpReg; coleenp CR - refactor async monitor deflation work from ServiceThread::service_thread_entry() to ObjectSynchronizer::deflate_idle_monitors_using_JT(); rehn,eosterlund CR - add support for HandshakeAfterDeflateIdleMonitors for platforms that don't have ObjectMonitor ref_count support implemented in C2 fast_lock() and fast_unlock().
*** 237,251 ****
// -----------------------------------------------------------------------------
// Enter support
void ObjectMonitor::enter(TRAPS) {
// The following code is ordered to check the most common cases first
// and to reduce RTS->RTO cache line upgrades on SPARC and IA32 processors.
Thread * const Self = THREAD;
! void * cur = Atomic::cmpxchg(Self, &_owner, (void*)NULL);
if (cur == NULL) {
assert(_recursions == 0, "invariant");
return;
}
--- 237,253 ----
// -----------------------------------------------------------------------------
// Enter support
void ObjectMonitor::enter(TRAPS) {
+ ADIM_guarantee(ref_count() > 0, "must be positive: ref_count=%d", ref_count());
+
// The following code is ordered to check the most common cases first
// and to reduce RTS->RTO cache line upgrades on SPARC and IA32 processors.
Thread * const Self = THREAD;
! void* cur = try_set_owner_from(Self, NULL);
if (cur == NULL) {
assert(_recursions == 0, "invariant");
return;
}
*** 256,268 ****
}
if (Self->is_lock_owned ((address)cur)) {
assert(_recursions == 0, "internal state error");
_recursions = 1;
! // Commute owner from a thread-specific on-stack BasicLockObject address to
! // a full-fledged "Thread *".
! _owner = Self;
return;
}
// We've encountered genuine contention.
assert(Self->_Stalled == 0, "invariant");
--- 258,278 ----
}
if (Self->is_lock_owned ((address)cur)) {
assert(_recursions == 0, "internal state error");
_recursions = 1;
! set_owner_from_BasicLock(Self, cur); // Convert from BasicLock* to Thread*.
! return;
! }
!
! if (AsyncDeflateIdleMonitors &&
! try_set_owner_from(Self, 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(_recursions == 0, "invariant");
return;
}
// We've encountered genuine contention.
assert(Self->_Stalled == 0, "invariant");
*** 273,284 ****
// transitions. The following spin is strictly optional ...
// Note that if we acquire the monitor from an initial spin
// we forgo posting JVMTI events and firing DTRACE probes.
if (TrySpin(Self) > 0) {
assert(_owner == Self, "must be Self: owner=" INTPTR_FORMAT, p2i(_owner));
! assert(_recursions == 0, "must be 0: recursions=" INTPTR_FORMAT,
! _recursions);
assert(((oop)object())->mark() == markWord::encode(this),
"object mark must match encoded this: mark=" INTPTR_FORMAT
", encoded this=" INTPTR_FORMAT, ((oop)object())->mark().value(),
markWord::encode(this).value());
Self->_Stalled = 0;
--- 283,293 ----
// transitions. The following spin is strictly optional ...
// Note that if we acquire the monitor from an initial spin
// we forgo posting JVMTI events and firing DTRACE probes.
if (TrySpin(Self) > 0) {
assert(_owner == Self, "must be Self: owner=" INTPTR_FORMAT, p2i(_owner));
! assert(_recursions == 0, "must be 0: recursions=" INTX_FORMAT, _recursions);
assert(((oop)object())->mark() == markWord::encode(this),
"object mark must match encoded this: mark=" INTPTR_FORMAT
", encoded this=" INTPTR_FORMAT, ((oop)object())->mark().value(),
markWord::encode(this).value());
Self->_Stalled = 0;
*** 289,304 ****
assert(_succ != Self, "invariant");
assert(Self->is_Java_thread(), "invariant");
JavaThread * jt = (JavaThread *) Self;
assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
assert(jt->thread_state() != _thread_blocked, "invariant");
! assert(this->object() != NULL, "invariant");
! assert(_contentions >= 0, "invariant");
! // Prevent deflation at STW-time. See deflate_idle_monitors() and is_busy().
! // Ensure the object-monitor relationship remains stable while there's contention.
! Atomic::inc(&_contentions);
JFR_ONLY(JfrConditionalFlushWithStacktrace<EventJavaMonitorEnter> flush(jt);)
EventJavaMonitorEnter event;
if (event.should_commit()) {
event.set_monitorClass(((oop)this->object())->klass());
--- 298,315 ----
assert(_succ != Self, "invariant");
assert(Self->is_Java_thread(), "invariant");
JavaThread * jt = (JavaThread *) Self;
assert(!SafepointSynchronize::is_at_safepoint(), "invariant");
assert(jt->thread_state() != _thread_blocked, "invariant");
! assert(AsyncDeflateIdleMonitors || this->object() != NULL, "invariant");
! assert(_contentions >= 0, "must not be negative: contentions=%d", _contentions);
! // Prevent deflation. See ObjectSynchronizer::deflate_monitor(),
! // ObjectSynchronizer::deflate_monitor_using_JT() and is_busy().
! // Ensure the object <-> monitor relationship remains stable while
! // there's contention.
! Atomic::add(1, &_contentions);
JFR_ONLY(JfrConditionalFlushWithStacktrace<EventJavaMonitorEnter> flush(jt);)
EventJavaMonitorEnter event;
if (event.should_commit()) {
event.set_monitorClass(((oop)this->object())->klass());
*** 356,366 ****
// states will still report that the thread is blocked trying to
// acquire it.
}
Atomic::dec(&_contentions);
! assert(_contentions >= 0, "invariant");
Self->_Stalled = 0;
// Must either set _recursions = 0 or ASSERT _recursions == 0.
assert(_recursions == 0, "invariant");
assert(_owner == Self, "invariant");
--- 367,377 ----
// states will still report that the thread is blocked trying to
// acquire it.
}
Atomic::dec(&_contentions);
! assert(_contentions >= 0, "must not be negative: contentions=%d", _contentions);
Self->_Stalled = 0;
// Must either set _recursions = 0 or ASSERT _recursions == 0.
assert(_recursions == 0, "invariant");
assert(_owner == Self, "invariant");
*** 400,432 ****
// Callers must compensate as needed.
int ObjectMonitor::TryLock(Thread * Self) {
void * own = _owner;
if (own != NULL) return 0;
! if (Atomic::replace_if_null(Self, &_owner)) {
assert(_recursions == 0, "invariant");
return 1;
}
// The lock had been free momentarily, but we lost the race to the lock.
// Interference -- the CAS failed.
// We can either return -1 or retry.
// Retry doesn't make as much sense because the lock was just acquired.
return -1;
}
// Convert the fields used by is_busy() to a string that can be
// used for diagnostic output.
const char* ObjectMonitor::is_busy_to_string(stringStream* ss) {
! ss->print("is_busy: contentions=%d, waiters=%d, owner=" INTPTR_FORMAT
! ", cxq=" INTPTR_FORMAT ", EntryList=" INTPTR_FORMAT, _contentions,
! _waiters, p2i(_owner), p2i(_cxq), p2i(_EntryList));
return ss->base();
}
#define MAX_RECHECK_INTERVAL 1000
void ObjectMonitor::EnterI(TRAPS) {
Thread * const Self = THREAD;
assert(Self->is_Java_thread(), "invariant");
assert(((JavaThread *) Self)->thread_state() == _thread_blocked, "invariant");
// Try the lock - TATAS
--- 411,525 ----
// Callers must compensate as needed.
int ObjectMonitor::TryLock(Thread * Self) {
void * own = _owner;
if (own != NULL) return 0;
! if (try_set_owner_from(Self, NULL) == NULL) {
assert(_recursions == 0, "invariant");
return 1;
}
// The lock had been free momentarily, but we lost the race to the lock.
// Interference -- the CAS failed.
// We can either return -1 or retry.
// Retry doesn't make as much sense because the lock was just acquired.
return -1;
}
+ // Install the displaced mark word (dmw) of a deflating ObjectMonitor
+ // into the header of the object associated with the monitor. This
+ // idempotent method is called by a thread that is deflating a
+ // monitor and by other threads that have detected a race with the
+ // deflation process.
+ void ObjectMonitor::install_displaced_markword_in_object(const oop obj) {
+ // This function must only be called when (owner == DEFLATER_MARKER
+ // && ref_count <= 0), but we can't guarantee that here because
+ // those values could change when the ObjectMonitor gets moved from
+ // the global free list to a per-thread free list.
+
+ guarantee(obj != NULL, "must be non-NULL");
+ if (object() != obj) {
+ // ObjectMonitor's object ref no longer refers to the target object
+ // so the object's header has already been restored.
+ return;
+ }
+
+ markWord dmw = header();
+ if (dmw.value() == 0) {
+ // ObjectMonitor's header/dmw has been cleared so the ObjectMonitor
+ // has been deflated and taken off the global free list.
+ return;
+ }
+
+ // A non-NULL dmw has to be either neutral (not locked and not marked)
+ // or is already participating in this restoration protocol.
+ assert(dmw.is_neutral() || (dmw.is_marked() && dmw.hash() == 0),
+ "failed precondition: dmw=" INTPTR_FORMAT, dmw.value());
+
+ markWord marked_dmw = markWord::zero();
+ if (!dmw.is_marked() && dmw.hash() == 0) {
+ // This dmw has not yet started the restoration protocol so we
+ // mark a copy of the dmw to begin the protocol.
+ // Note: A dmw with a hashcode does not take this code path.
+ marked_dmw = dmw.set_marked();
+
+ // All of the callers to this function can be racing with each
+ // other trying to update the _header field.
+ dmw = (markWord) Atomic::cmpxchg(marked_dmw, &_header, dmw);
+ if (dmw.value() == 0) {
+ // ObjectMonitor's header/dmw has been cleared so the object's
+ // header has already been restored.
+ return;
+ }
+ // The _header field is now marked. The winner's 'dmw' variable
+ // contains the original, unmarked header/dmw value and any
+ // losers have a marked header/dmw value that will be cleaned
+ // up below.
+ }
+
+ if (dmw.is_marked()) {
+ // Clear the mark from the header/dmw copy in preparation for
+ // possible restoration from this thread.
+ assert(dmw.hash() == 0, "hashcode must be 0: dmw=" INTPTR_FORMAT,
+ dmw.value());
+ dmw = dmw.set_unmarked();
+ }
+ assert(dmw.is_neutral(), "must be neutral: dmw=" INTPTR_FORMAT, dmw.value());
+
+ // Install displaced mark word if the object's header still points
+ // to this ObjectMonitor. All racing callers to this function will
+ // reach this point, but only one can win.
+ obj->cas_set_mark(dmw, markWord::encode(this));
+
+ // Note: It does not matter which thread restored the header/dmw
+ // into the object's header. The thread deflating the monitor just
+ // wanted the object's header restored and it is. The threads that
+ // detected a race with the deflation process also wanted the
+ // object's header restored before they retry their operation and
+ // because it is restored they will only retry once.
+ }
+
// Convert the fields used by is_busy() to a string that can be
// used for diagnostic output.
const char* ObjectMonitor::is_busy_to_string(stringStream* ss) {
! ss->print("is_busy: contentions=%d, waiters=%d, ", _contentions, _waiters);
! if (!AsyncDeflateIdleMonitors) {
! ss->print("owner=" INTPTR_FORMAT, p2i(_owner));
! } else if (_owner != DEFLATER_MARKER) {
! ss->print("owner=" INTPTR_FORMAT, p2i(_owner));
! } else {
! ss->print("owner=" INTPTR_FORMAT, NULL);
! }
! ss->print(", cxq=" INTPTR_FORMAT ", EntryList=" INTPTR_FORMAT, p2i(_cxq),
! p2i(_EntryList));
return ss->base();
}
#define MAX_RECHECK_INTERVAL 1000
void ObjectMonitor::EnterI(TRAPS) {
+ ADIM_guarantee(ref_count() > 0, "must be positive: ref_count=%d", ref_count());
+
Thread * const Self = THREAD;
assert(Self->is_Java_thread(), "invariant");
assert(((JavaThread *) Self)->thread_state() == _thread_blocked, "invariant");
// Try the lock - TATAS
*** 435,444 ****
--- 528,548 ----
assert(_owner == Self, "invariant");
assert(_Responsible != Self, "invariant");
return;
}
+ if (AsyncDeflateIdleMonitors &&
+ try_set_owner_from(Self, 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(_succ != Self, "invariant");
+ assert(_Responsible != Self, "invariant");
+ return;
+ }
+
assert(InitDone, "Unexpectedly not initialized");
// We try one round of spinning *before* enqueueing Self.
//
// If the _owner is ready but OFFPROC we could use a YieldTo()
*** 551,560 ****
--- 655,673 ----
Self->_ParkEvent->park();
}
if (TryLock(Self) > 0) break;
+ if (AsyncDeflateIdleMonitors &&
+ try_set_owner_from(Self, 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.
+ break;
+ }
+
// The lock is still contested.
// Keep a tally of the # of futile wakeups.
// Note that the counter is not protected by a lock or updated by atomics.
// That is by design - we trade "lossy" counters which are exposed to
// races during updates for a lower probe effect.
*** 655,664 ****
--- 768,779 ----
// monitor reentry in wait().
//
// In the future we should reconcile EnterI() and ReenterI().
void ObjectMonitor::ReenterI(Thread * Self, ObjectWaiter * SelfNode) {
+ ADIM_guarantee(ref_count() > 0, "must be positive: ref_count=%d", ref_count());
+
assert(Self != NULL, "invariant");
assert(SelfNode != NULL, "invariant");
assert(SelfNode->_thread == Self, "invariant");
assert(_waiters > 0, "invariant");
assert(((oop)(object()))->mark() == markWord::encode(this), "invariant");
*** 672,681 ****
--- 787,805 ----
assert(_owner != Self, "invariant");
if (TryLock(Self) > 0) break;
if (TrySpin(Self) > 0) break;
+ if (AsyncDeflateIdleMonitors &&
+ try_set_owner_from(Self, 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.
+ break;
+ }
+
// State transition wrappers around park() ...
// ReenterI() wisely defers state transitions until
// it's clear we must park the thread.
{
OSThreadContendState osts(Self->osthread());
*** 861,877 ****
// of such futile wakups is low.
void ObjectMonitor::exit(bool not_suspended, TRAPS) {
Thread * const Self = THREAD;
if (THREAD != _owner) {
! if (THREAD->is_lock_owned((address) _owner)) {
! // Transmute _owner from a BasicLock pointer to a Thread address.
! // We don't need to hold _mutex for this transition.
! // Non-null to Non-null is safe as long as all readers can
! // tolerate either flavor.
assert(_recursions == 0, "invariant");
! _owner = THREAD;
_recursions = 0;
} else {
// Apparent unbalanced locking ...
// Naively we'd like to throw IllegalMonitorStateException.
// As a practical matter we can neither allocate nor throw an
--- 985,998 ----
// of such futile wakups is low.
void ObjectMonitor::exit(bool not_suspended, TRAPS) {
Thread * const Self = THREAD;
if (THREAD != _owner) {
! void* cur = _owner;
! if (THREAD->is_lock_owned((address)cur)) {
assert(_recursions == 0, "invariant");
! set_owner_from_BasicLock(Self, cur); // Convert from BasicLock* to Thread*.
_recursions = 0;
} else {
// Apparent unbalanced locking ...
// Naively we'd like to throw IllegalMonitorStateException.
// As a practical matter we can neither allocate nor throw an
*** 879,889 ****
// see x86_32.ad Fast_Unlock() and the I1 and I2 properties.
// Upon deeper reflection, however, in a properly run JVM the only
// way we should encounter this situation is in the presence of
// unbalanced JNI locking. TODO: CheckJNICalls.
// See also: CR4414101
! assert(false, "Non-balanced monitor enter/exit! Likely JNI locking");
return;
}
}
if (_recursions != 0) {
--- 1000,1017 ----
// see x86_32.ad Fast_Unlock() and the I1 and I2 properties.
// Upon deeper reflection, however, in a properly run JVM the only
// way we should encounter this situation is in the presence of
// unbalanced JNI locking. TODO: CheckJNICalls.
// See also: CR4414101
! tty->print_cr("ERROR: ObjectMonitor::exit(): thread=" INTPTR_FORMAT
! " is exiting an ObjectMonitor it does not own.",
! p2i(THREAD));
! tty->print_cr("The imbalance is possibly caused by JNI locking.");
! print_debug_style_on(tty);
! // Changing this from an assert() to ADIM_guarantee() may run
! // afoul of any test that is inducing non-balanced JNI locking.
! ADIM_guarantee(false, "Non-balanced monitor enter/exit!");
return;
}
}
if (_recursions != 0) {
*** 908,919 ****
--- 1036,1051 ----
// release semantics: prior loads and stores from within the critical section
// must not float (reorder) past the following store that drops the lock.
// On SPARC that requires MEMBAR #loadstore|#storestore.
// But of course in TSO #loadstore|#storestore is not required.
+ if (AsyncDeflateIdleMonitors) {
+ set_owner_from(NULL, Self);
+ } else {
OrderAccess::release_store(&_owner, (void*)NULL); // drop the lock
OrderAccess::storeload(); // See if we need to wake a successor
+ }
if ((intptr_t(_EntryList)|intptr_t(_cxq)) == 0 || _succ != NULL) {
return;
}
// Other threads are blocked trying to acquire the lock.
*** 951,961 ****
// Only the current lock owner can manipulate the EntryList or
// drain _cxq, so we need to reacquire the lock. If we fail
// to reacquire the lock the responsibility for ensuring succession
// falls to the new owner.
//
! if (!Atomic::replace_if_null(THREAD, &_owner)) {
return;
}
guarantee(_owner == THREAD, "invariant");
--- 1083,1093 ----
// Only the current lock owner can manipulate the EntryList or
// drain _cxq, so we need to reacquire the lock. If we fail
// to reacquire the lock the responsibility for ensuring succession
// falls to the new owner.
//
! if (try_set_owner_from(Self, NULL) != NULL) {
return;
}
guarantee(_owner == THREAD, "invariant");
*** 1084,1095 ****
--- 1216,1231 ----
// The thread associated with Wakee may have grabbed the lock and "Wakee" may be
// out-of-scope (non-extant).
Wakee = NULL;
// Drop the lock
+ if (AsyncDeflateIdleMonitors) {
+ set_owner_from(NULL, Self);
+ } else {
OrderAccess::release_store(&_owner, (void*)NULL);
OrderAccess::fence(); // ST _owner vs LD in unpark()
+ }
DTRACE_MONITOR_PROBE(contended__exit, this, object(), Self);
Trigger->unpark();
// Maintain stats and report events to JVMTI
*** 1112,1124 ****
JavaThread *jt = (JavaThread *)THREAD;
assert(InitDone, "Unexpectedly not initialized");
if (THREAD != _owner) {
! if (THREAD->is_lock_owned ((address)_owner)) {
assert(_recursions == 0, "internal state error");
! _owner = THREAD; // Convert from basiclock addr to Thread addr
_recursions = 0;
}
}
guarantee(Self == _owner, "complete_exit not owner");
--- 1248,1261 ----
JavaThread *jt = (JavaThread *)THREAD;
assert(InitDone, "Unexpectedly not initialized");
if (THREAD != _owner) {
! void* cur = _owner;
! if (THREAD->is_lock_owned((address)cur)) {
assert(_recursions == 0, "internal state error");
! set_owner_from_BasicLock(Self, cur); // Convert from BasicLock* to Thread*.
_recursions = 0;
}
}
guarantee(Self == _owner, "complete_exit not owner");
*** 1135,1148 ****
Thread * const Self = THREAD;
assert(Self->is_Java_thread(), "Must be Java thread!");
JavaThread *jt = (JavaThread *)THREAD;
guarantee(_owner != Self, "reenter already owner");
! enter(THREAD); // enter the monitor
guarantee(_recursions == 0, "reenter recursion");
_recursions = recursions;
- return;
}
// Checks that the current THREAD owns this monitor and causes an
// immediate return if it doesn't. We don't use the CHECK macro
// because we want the IMSE to be the only exception that is thrown
--- 1272,1285 ----
Thread * const Self = THREAD;
assert(Self->is_Java_thread(), "Must be Java thread!");
JavaThread *jt = (JavaThread *)THREAD;
guarantee(_owner != Self, "reenter already owner");
! enter(THREAD);
! // Entered the monitor.
guarantee(_recursions == 0, "reenter recursion");
_recursions = recursions;
}
// Checks that the current THREAD owns this monitor and causes an
// immediate return if it doesn't. We don't use the CHECK macro
// because we want the IMSE to be the only exception that is thrown
*** 1162,1173 ****
// is not the owner, that exception will be replaced by the IMSE.
bool ObjectMonitor::check_owner(Thread* THREAD) {
if (_owner == THREAD) {
return true;
}
! if (THREAD->is_lock_owned((address)_owner)) {
! _owner = THREAD; // convert from BasicLock addr to Thread addr
_recursions = 0;
return true;
}
THROW_MSG_(vmSymbols::java_lang_IllegalMonitorStateException(),
"current thread is not owner", false);
--- 1299,1311 ----
// is not the owner, that exception will be replaced by the IMSE.
bool ObjectMonitor::check_owner(Thread* THREAD) {
if (_owner == THREAD) {
return true;
}
! void* cur = _owner;
! if (THREAD->is_lock_owned((address)cur)) {
! set_owner_from_BasicLock(THREAD, cur); // Convert from BasicLock* to Thread*.
_recursions = 0;
return true;
}
THROW_MSG_(vmSymbols::java_lang_IllegalMonitorStateException(),
"current thread is not owner", false);
*** 1668,1678 ****
// the spin without prejudice or apply a "penalty" to the
// spin count-down variable "ctr", reducing it by 100, say.
Thread * ox = (Thread *) _owner;
if (ox == NULL) {
! ox = (Thread*)Atomic::cmpxchg(Self, &_owner, (void*)NULL);
if (ox == NULL) {
// The CAS succeeded -- this thread acquired ownership
// Take care of some bookkeeping to exit spin state.
if (_succ == Self) {
_succ = NULL;
--- 1806,1816 ----
// the spin without prejudice or apply a "penalty" to the
// spin count-down variable "ctr", reducing it by 100, say.
Thread * ox = (Thread *) _owner;
if (ox == NULL) {
! ox = (Thread*)try_set_owner_from(Self, NULL);
if (ox == NULL) {
// The CAS succeeded -- this thread acquired ownership
// Take care of some bookkeeping to exit spin state.
if (_succ == Self) {
_succ = NULL;
*** 1932,1944 ****
}
DEBUG_ONLY(InitDone = true;)
}
void ObjectMonitor::print_on(outputStream* st) const {
// The minimal things to print for markWord printing, more can be added for debugging and logging.
st->print("{contentions=0x%08x,waiters=0x%08x"
! ",recursions=" INTPTR_FORMAT ",owner=" INTPTR_FORMAT "}",
contentions(), waiters(), recursions(),
p2i(owner()));
}
void ObjectMonitor::print() const { print_on(tty); }
--- 2070,2249 ----
}
DEBUG_ONLY(InitDone = true;)
}
+ // For internal use by ObjectSynchronizer::monitors_iterate().
+ ObjectMonitorHandle::ObjectMonitorHandle(ObjectMonitor * om_ptr) {
+ om_ptr->inc_ref_count();
+ _om_ptr = om_ptr;
+ }
+
+ ObjectMonitorHandle::~ObjectMonitorHandle() {
+ if (_om_ptr != NULL) {
+ _om_ptr->dec_ref_count();
+ _om_ptr = NULL;
+ }
+ }
+
+ // Save the ObjectMonitor* associated with the specified markWord and
+ // increment the ref_count. This function should only be called if
+ // the caller has verified mark.has_monitor() == true. The object
+ // parameter is needed to verify that ObjectMonitor* has not been
+ // deflated and reused for another object.
+ //
+ // This function returns true if the ObjectMonitor* has been safely
+ // saved. This function returns false if we have lost a race with
+ // async deflation; the caller should retry as appropriate.
+ //
+ bool ObjectMonitorHandle::save_om_ptr(oop object, markWord mark) {
+ guarantee(mark.has_monitor(), "sanity check: mark=" INTPTR_FORMAT,
+ mark.value());
+
+ ObjectMonitor * om_ptr = mark.monitor();
+ om_ptr->inc_ref_count();
+
+ if (AsyncDeflateIdleMonitors) {
+ // Race here if monitor is not owned! The above ref_count bump
+ // will cause subsequent async deflation to skip it. However,
+ // previous or concurrent async deflation is a race.
+ if (om_ptr->owner_is_DEFLATER_MARKER() && om_ptr->ref_count() <= 0) {
+ // Async deflation is in progress and our ref_count increment
+ // above lost the race to async deflation. Attempt to restore
+ // the header/dmw to the object's header so that we only retry
+ // once if the deflater thread happens to be slow.
+ om_ptr->install_displaced_markword_in_object(object);
+ om_ptr->dec_ref_count();
+ return false;
+ }
+ if (om_ptr->ref_count() <= 0) {
+ // Async deflation is in the process of bailing out, but has not
+ // yet restored the ref_count field so we return false to force
+ // a retry. We want a positive ref_count value for a true return.
+ om_ptr->dec_ref_count();
+ return false;
+ }
+ // The ObjectMonitor could have been deflated and reused for
+ // another object before we bumped the ref_count so make sure
+ // our object still refers to this ObjectMonitor.
+ const markWord tmp = object->mark();
+ if (!tmp.has_monitor() || tmp.monitor() != om_ptr) {
+ // Async deflation and reuse won the race so we have to retry.
+ // Skip object header restoration since that's already done.
+ om_ptr->dec_ref_count();
+ return false;
+ }
+ }
+
+ ADIM_guarantee(_om_ptr == NULL, "sanity check: _om_ptr=" INTPTR_FORMAT,
+ p2i(_om_ptr));
+ _om_ptr = om_ptr;
+ return true;
+ }
+
+ // For internal use by ObjectSynchronizer::inflate().
+ void ObjectMonitorHandle::set_om_ptr(ObjectMonitor * om_ptr) {
+ if (_om_ptr == NULL) {
+ ADIM_guarantee(om_ptr != NULL, "cannot clear an unset om_ptr");
+ om_ptr->inc_ref_count();
+ _om_ptr = om_ptr;
+ } else {
+ ADIM_guarantee(om_ptr == NULL, "can only clear a set om_ptr");
+ _om_ptr->dec_ref_count();
+ _om_ptr = NULL;
+ }
+ }
+
void ObjectMonitor::print_on(outputStream* st) const {
// The minimal things to print for markWord printing, more can be added for debugging and logging.
st->print("{contentions=0x%08x,waiters=0x%08x"
! ",recursions=" INTX_FORMAT ",owner=" INTPTR_FORMAT "}",
contentions(), waiters(), recursions(),
p2i(owner()));
}
void ObjectMonitor::print() const { print_on(tty); }
+
+ // Print the ObjectMonitor like a debugger would:
+ //
+ // (ObjectMonitor) 0x00007fdfb6012e40 = {
+ // _header = (_value = 1)
+ // _object = 0x000000070ff45fd0
+ // _allocation_state = Old
+ // _pad_buf0 = {
+ // [0] = '\0'
+ // ...
+ // [43] = '\0'
+ // }
+ // _owner = 0x0000000000000000
+ // _previous_owner_tid = 0
+ // _pad_buf1 = {
+ // [0] = '\0'
+ // ...
+ // [47] = '\0'
+ // }
+ // _ref_count = 1
+ // _pad_buf2 = {
+ // [0] = '\0'
+ // ...
+ // [59] = '\0'
+ // }
+ // _next_om = 0x0000000000000000
+ // _recursions = 0
+ // _EntryList = 0x0000000000000000
+ // _cxq = 0x0000000000000000
+ // _succ = 0x0000000000000000
+ // _Responsible = 0x0000000000000000
+ // _Spinner = 0
+ // _SpinDuration = 5000
+ // _contentions = 0
+ // _WaitSet = 0x0000700009756248
+ // _waiters = 1
+ // _WaitSetLock = 0
+ // }
+ //
+ void ObjectMonitor::print_debug_style_on(outputStream* st) const {
+ st->print_cr("(ObjectMonitor *) " INTPTR_FORMAT " = {", p2i(this));
+ st->print_cr(" _header = " INTPTR_FORMAT, header().value());
+ st->print_cr(" _object = " INTPTR_FORMAT, p2i(_object));
+ st->print(" _allocation_state = ");
+ if (is_free()) {
+ st->print("Free");
+ } else if (is_old()) {
+ st->print("Old");
+ } else if (is_new()) {
+ st->print("New");
+ } else {
+ st->print("unknown=%d", _allocation_state);
+ }
+ st->cr();
+ st->print_cr(" _pad_buf0 = {");
+ st->print_cr(" [0] = '\\0'");
+ st->print_cr(" ...");
+ st->print_cr(" [%d] = '\\0'", (int)sizeof(_pad_buf0) - 1);
+ st->print_cr(" }");
+ st->print_cr(" _owner = " INTPTR_FORMAT, p2i(_owner));
+ st->print_cr(" _previous_owner_tid = " JLONG_FORMAT, _previous_owner_tid);
+ st->print_cr(" _pad_buf1 = {");
+ st->print_cr(" [0] = '\\0'");
+ st->print_cr(" ...");
+ st->print_cr(" [%d] = '\\0'", (int)sizeof(_pad_buf1) - 1);
+ st->print_cr(" }");
+ st->print_cr(" _ref_count = %d", ref_count());
+ st->print_cr(" _pad_buf2 = {");
+ st->print_cr(" [0] = '\\0'");
+ st->print_cr(" ...");
+ st->print_cr(" [%d] = '\\0'", (int)sizeof(_pad_buf1) - 1);
+ st->print_cr(" }");
+ st->print_cr(" _next_om = " INTPTR_FORMAT, p2i(_next_om));
+ st->print_cr(" _recursions = " INTX_FORMAT, _recursions);
+ st->print_cr(" _EntryList = " INTPTR_FORMAT, p2i(_EntryList));
+ st->print_cr(" _cxq = " INTPTR_FORMAT, p2i(_cxq));
+ st->print_cr(" _succ = " INTPTR_FORMAT, p2i(_succ));
+ st->print_cr(" _Responsible = " INTPTR_FORMAT, p2i(_Responsible));
+ st->print_cr(" _Spinner = %d", _Spinner);
+ st->print_cr(" _SpinDuration = %d", _SpinDuration);
+ st->print_cr(" _contentions = %d", _contentions);
+ st->print_cr(" _WaitSet = " INTPTR_FORMAT, p2i(_WaitSet));
+ st->print_cr(" _waiters = %d", _waiters);
+ st->print_cr(" _WaitSetLock = %d", _WaitSetLock);
+ st->print_cr("}");
+ }
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