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Add pinning checks to blocking operations #24099

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89cf06a
Add pinning checks to blocking operations
tajila Jun 8, 2026
845ef4e
Add check for live Vthreads in pinned checks
tajila Jun 8, 2026
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8 changes: 8 additions & 0 deletions runtime/oti/j9.h
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Original file line number Diff line number Diff line change
Expand Up @@ -450,6 +450,14 @@ static_assert((LITERAL_STRLEN(J9_UNMODIFIABLE_CLASS_ANNOTATION) < (size_t)'/'),
} while (0)
#endif /* JAVA_SPEC_VERSION >= 24 */

#if JAVA_SPEC_VERSION >= 24
#define J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm) \
(J9_ARE_ANY_BITS_SET((vm)->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION) \
&& J9_ARE_ANY_BITS_SET((vm)->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION))
#else
#define J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm) (1 == 0)
#endif

#define DIR_LIB_STR "lib"

#if defined(J9VM_OPT_JFR)
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1 change: 1 addition & 0 deletions runtime/oti/j9consts.h
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Expand Up @@ -391,6 +391,7 @@ extern "C" {
#define J9_EXTENDED_RUNTIME3_GCCONTAINERHEURISTICS 0x400
#define J9_EXTENDED_RUNTIME3_USE_VECTOR_LENGTH_256 0x800
#define J9_EXTENDED_RUNTIME3_USE_VECTOR_LENGTH_512 0x1000
#define J9_EXTENDED_RUNTIME3_VTHREAD_CREATED 0x2000


#define J9_OBJECT_HEADER_AGE_DEFAULT 0xA /* OBJECT_HEADER_AGE_DEFAULT */
Expand Down
12 changes: 7 additions & 5 deletions runtime/vm/BytecodeInterpreter.hpp
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Expand Up @@ -1211,7 +1211,7 @@ class INTERPRETER_CLASS
rc = objectMonitorEnterNonBlocking(_currentThread, obj);
if (J9_OBJECT_MONITOR_BLOCKING == rc) {
#if JAVA_SPEC_VERSION >= 24
if (VM_ContinuationHelpers::isYieldableVirtualThread(_currentThread)) {
if (_pinningSupportEnabled && VM_ContinuationHelpers::isYieldableVirtualThread(_currentThread)) {
/* Try to yield the virtual thread if it will be blocked. */
updateVMStruct(REGISTER_ARGS);
rc = preparePinnedVirtualThreadForUnmount(_currentThread, obj, false);
Expand All @@ -1225,7 +1225,7 @@ class INTERPRETER_CLASS
}
}
#if JAVA_SPEC_VERSION >= 24
if (rc == (UDATA)obj) {
if (_pinningSupportEnabled && (rc == (UDATA)obj)) {
J9VMContinuation *continuation = _currentThread->currentContinuation;
if (NULL != continuation) {
if (J9_ARE_ALL_BITS_SET(continuation->runtimeFlags, J9VM_CONTINUATION_RUNTIMEFLAG_JVMTI_CONTENDED_MONITOR_ENTER_RECORDED)) {
Expand Down Expand Up @@ -3041,7 +3041,7 @@ class INTERPRETER_CLASS
{
if (VM_ObjectMonitor::getMonitorForNotify(_currentThread, receiver, &monitorPtr, true)) {
#if JAVA_SPEC_VERSION >= 24
if (J9_ARE_ANY_BITS_SET(_vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)) {
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(_vm)) {
j9objectmonitor_t lock = 0;
j9objectmonitor_t *lockEA = NULL;
J9ObjectMonitor *objectMonitor = NULL;
Expand Down Expand Up @@ -6001,7 +6001,7 @@ class INTERPRETER_CLASS
buildInternalNativeStackFrame(REGISTER_ARGS);
updateVMStruct(REGISTER_ARGS);
#if JAVA_SPEC_VERSION >= 24
if (J9_ARE_ANY_BITS_SET(_vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)
if (_pinningSupportEnabled)
&& (_currentThread->ownedMonitorCount > 0)
&& !isFinished
) {
Expand Down Expand Up @@ -10392,7 +10392,9 @@ class INTERPRETER_CLASS
#if defined(LOCAL_LITERALS)
J9Method *_literals = vmThread->literals;
#endif

#if JAVA_SPEC_VERSION >= 24
const bool _pinningSupportEnabled = J9_ARE_ANY_BITS_SET(vmThread->javaVM->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION
#endif /* JAVA_SPEC_VERSION >= 24 */
DEBUG_MUST_HAVE_VM_ACCESS(vmThread);
vmThread->jitStackFrameFlags = 0;

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2 changes: 2 additions & 0 deletions runtime/vm/ContinuationHelpers.cpp
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Expand Up @@ -45,6 +45,8 @@ createContinuation(J9VMThread *currentThread, j9object_t continuationObject)
I_64 start = j9time_hires_clock();
#endif /* defined(J9VM_PROF_CONTINUATION_ALLOCATION) */

vm->extendedRuntimeFlags3 |= J9_EXTENDED_RUNTIME3_VTHREAD_CREATED;

/* First check if local cache is available. */
if (NULL != currentThread->continuationT1Cache) {
for (U_32 i = 0; i < vm->continuationT1Size; i++) {
Expand Down
4 changes: 2 additions & 2 deletions runtime/vm/FastJNI_java_lang_Object.cpp
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Expand Up @@ -62,7 +62,7 @@ Fast_java_lang_Object_notifyAll(J9VMThread *currentThread, j9object_t receiverOb
if (VM_ObjectMonitor::getMonitorForNotify(currentThread, receiverObject, &monitorPtr, true)) {
#if JAVA_SPEC_VERSION >= 24
J9JavaVM *vm = currentThread->javaVM;
if (J9_ARE_ANY_BITS_SET(vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)) {
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm)) {
j9objectmonitor_t lock = 0;
j9objectmonitor_t *lockEA = NULL;
J9ObjectMonitor *objectMonitor = NULL;
Expand Down Expand Up @@ -107,7 +107,7 @@ Fast_java_lang_Object_notify(J9VMThread *currentThread, j9object_t receiverObjec
if (VM_ObjectMonitor::getMonitorForNotify(currentThread, receiverObject, &monitorPtr, true)) {
#if JAVA_SPEC_VERSION >= 24
J9JavaVM *vm = currentThread->javaVM;
if (J9_ARE_ANY_BITS_SET(vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)) {
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm)) {
j9objectmonitor_t lock = 0;
j9objectmonitor_t *lockEA = NULL;
J9ObjectMonitor *objectMonitor = NULL;
Expand Down
206 changes: 106 additions & 100 deletions runtime/vm/monhelpers.c
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Expand Up @@ -71,6 +71,9 @@ objectMonitorExit(J9VMThread* vmStruct, j9object_t object)
lock = J9_LOAD_LOCKWORD(vmStruct, lockEA);

if (J9_FLATLOCK_OWNER(lock) == vmStruct) {
#if JAVA_SPEC_VERSION >= 24
J9JavaVM *vm = vmStruct->javaVM;
#endif /* JAVA_SPEC_VERSION >= 24 */
/* The current thread owns the monitor, and it's a flat lock. */
UDATA count = (UDATA)lock & OBJECT_HEADER_LOCK_BITS_MASK;
/*
Expand All @@ -96,133 +99,136 @@ objectMonitorExit(J9VMThread* vmStruct, j9object_t object)
#endif /* if !(defined(AIXPPC) || defined(LINUXPPC)) */
#endif /* ifndef J9VM_THR_LOCK_RESERVATION */
#if JAVA_SPEC_VERSION >= 24
if (OBJECT_HEADER_LOCK_FLC == count) {
/* FLC set, non-recursive. */
J9ObjectMonitor *objectMonitor = objectMonitorInflate(vmStruct, object, lock);

if (NULL == objectMonitor) {
/* Out of memory - impossible? */
monitorExitWriteBarrier();
J9_STORE_LOCKWORD(vmStruct, lockEA, 0);
} else {
omrthread_monitor_t monitor = objectMonitor->monitor;
J9JavaVM *vm = vmStruct->javaVM;
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm)) {
if (OBJECT_HEADER_LOCK_FLC == count) {
/* FLC set, non-recursive. */
J9ObjectMonitor *objectMonitor = objectMonitorInflate(vmStruct, object, lock);

if (NULL == objectMonitor) {
/* Out of memory - impossible? */
monitorExitWriteBarrier();
J9_STORE_LOCKWORD(vmStruct, lockEA, 0);
} else {
omrthread_monitor_t monitor = objectMonitor->monitor;

TRIGGER_J9HOOK_VM_MONITOR_CONTENDED_EXIT(vm->hookInterface, vmStruct, monitor);
TRIGGER_J9HOOK_VM_MONITOR_CONTENDED_EXIT(vm->hookInterface, vmStruct, monitor);

omrthread_monitor_exit(monitor);
omrthread_monitor_exit(monitor);

if (J9_ARE_ANY_BITS_SET(vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)
&& (0 != objectMonitor->virtualThreadWaitCount)
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm)
&& (0 != objectMonitor->virtualThreadWaitCount)
) {
J9VM_SEND_VIRTUAL_UNBLOCKER_THREAD_SIGNAL(vm);
}
}
} else {
j9objectmonitor_t newLock = 0;
BOOLEAN casSuccess = FALSE;
if (0x00 == count) {
/* Just release the flatlock. */
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING)
&& J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING_RECURSION_MASK)
) {
J9VM_SEND_VIRTUAL_UNBLOCKER_THREAD_SIGNAL(vm);
/* Learning state case. */
newLock = lock - OBJECT_HEADER_LOCK_LEARNING_FIRST_RECURSION_BIT;
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING)) {
/* Lock is in Learning state but unowned.
* (if it were owned it would have been caught by the first Learning state check)
*/
goto done;
} else if (count >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT) {
/* Just decrement the flatlock recursion count. */
newLock = lock - OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT;
#ifdef J9VM_THR_LOCK_RESERVATION
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_RESERVED)) {
/* Lock is reserved but unowned.
* (if it were owned the count would be >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT)
*/
Trc_VM_objectMonitorExit_Exit_ReservedButUnownedFlatLock(vmStruct, lock, object);
goto done;
#endif /* J9VM_THR_LOCK_RESERVATION */
}

monitorExitWriteBarrier();
if (J9VMTHREAD_COMPRESS_OBJECT_REFERENCES(vmStruct)) {
casSuccess = (lock == compareAndSwapU32((uint32_t *)lockEA, (uint32_t)lock, (uint32_t)newLock));
} else {
casSuccess = (lock == compareAndSwapUDATA((uintptr_t *)lockEA, (uintptr_t)lock, (uintptr_t)newLock));
}

if (!casSuccess) {
/* Another thread has attempted to get the lock and may have update the FLC flag. */
goto restart;
}
}
} else {
j9objectmonitor_t newLock = 0;
BOOLEAN casSuccess = FALSE;
} else
#endif /* JAVA_SPEC_VERSION >= 24 */
{
if (0x00 == count) {
/* Just release the flatlock. */
monitorExitWriteBarrier();
J9_STORE_LOCKWORD(vmStruct, lockEA, 0);
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING)
&& J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING_RECURSION_MASK)
) {
/* Learning state case. */
newLock = lock - OBJECT_HEADER_LOCK_LEARNING_FIRST_RECURSION_BIT;
BOOLEAN casSuccess = FALSE;

if (1 == J9_FLATLOCK_COUNT(lock)) {
/* If RC field is 1, this fully unlocks the object so a write barrier is needed. */
monitorExitWriteBarrier();
}

if (J9VMTHREAD_COMPRESS_OBJECT_REFERENCES(vmStruct)) {
casSuccess = (lock == compareAndSwapU32((uint32_t*)lockEA, (uint32_t)lock,
(uint32_t)(lock - OBJECT_HEADER_LOCK_LEARNING_FIRST_RECURSION_BIT)));
} else {
casSuccess = (lock == compareAndSwapUDATA((uintptr_t*)lockEA, (uintptr_t)lock,
(uintptr_t)(lock - OBJECT_HEADER_LOCK_LEARNING_FIRST_RECURSION_BIT)));
}

if (!casSuccess) {
/*
* Another thread has attempted to get the lock and atomically changed the state to Flat.
* Start over and read the new lockword. The lock can not go back to Learning so this will
* only happen once.
*/
goto restart;
}
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING)) {
/* Lock is in Learning state but unowned.
* (if it were owned it would have been caught by the first Learning state check)
*/
* (if it were owned it would have been caught by the first Learning state check)
*/
Trc_VM_objectMonitorExit_Exit_LearningStateUnowned(vmStruct, lock, object);
goto done;
} else if (count >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT) {
/* Just decrement the flatlock recursion count. */
newLock = lock - OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT;
lock -= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT;
J9_STORE_LOCKWORD(vmStruct, lockEA, lock);
#ifdef J9VM_THR_LOCK_RESERVATION
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_RESERVED)) {
/* Lock is reserved but unowned.
* (if it were owned the count would be >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT)
*/
* (if it were owned the count would be >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT)
*/
Trc_VM_objectMonitorExit_Exit_ReservedButUnownedFlatLock(vmStruct, lock, object);
goto done;
#endif /* J9VM_THR_LOCK_RESERVATION */
}

monitorExitWriteBarrier();
if (J9VMTHREAD_COMPRESS_OBJECT_REFERENCES(vmStruct)) {
casSuccess = (lock == compareAndSwapU32((uint32_t *)lockEA, (uint32_t)lock, (uint32_t)newLock));
} else {
casSuccess = (lock == compareAndSwapUDATA((uintptr_t *)lockEA, (uintptr_t)lock, (uintptr_t)newLock));
}
/* FLC set, non-recursive. */
J9ObjectMonitor *objectMonitor = objectMonitorInflate(vmStruct, object, lock);

if (!casSuccess) {
/* Another thread has attempted to get the lock and may have update the FLC flag. */
goto restart;
if (NULL == objectMonitor) {
/* Out of memory - impossible? */
monitorExitWriteBarrier();
J9_STORE_LOCKWORD(vmStruct, lockEA, 0);
} else {
omrthread_monitor_t monitor = objectMonitor->monitor;
TRIGGER_J9HOOK_VM_MONITOR_CONTENDED_EXIT(vmStruct->javaVM->hookInterface, vmStruct, monitor);
omrthread_monitor_exit(monitor);
}
}
}
#else /* JAVA_SPEC_VERSION >= 24 */
if (0x00 == count) {
/* Just release the flatlock. */
monitorExitWriteBarrier();
J9_STORE_LOCKWORD(vmStruct, lockEA, 0);
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING)
&& J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING_RECURSION_MASK)
) {
/* Learning state case. */
BOOLEAN casSuccess = FALSE;

if (1 == J9_FLATLOCK_COUNT(lock)) {
/* If RC field is 1, this fully unlocks the object so a write barrier is needed. */
monitorExitWriteBarrier();
}

if (J9VMTHREAD_COMPRESS_OBJECT_REFERENCES(vmStruct)) {
casSuccess = (lock == compareAndSwapU32((uint32_t*)lockEA, (uint32_t)lock,
(uint32_t)(lock - OBJECT_HEADER_LOCK_LEARNING_FIRST_RECURSION_BIT)));
} else {
casSuccess = (lock == compareAndSwapUDATA((uintptr_t*)lockEA, (uintptr_t)lock,
(uintptr_t)(lock - OBJECT_HEADER_LOCK_LEARNING_FIRST_RECURSION_BIT)));
}

if (!casSuccess) {
/*
* Another thread has attempted to get the lock and atomically changed the state to Flat.
* Start over and read the new lockword. The lock can not go back to Learning so this will
* only happen once.
*/
goto restart;
}
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_LEARNING)) {
/* Lock is in Learning state but unowned.
* (if it were owned it would have been caught by the first Learning state check)
*/
Trc_VM_objectMonitorExit_Exit_LearningStateUnowned(vmStruct, lock, object);
goto done;
} else if (count >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT) {
/* Just decrement the flatlock recursion count. */
lock -= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT;
J9_STORE_LOCKWORD(vmStruct, lockEA, lock);
#ifdef J9VM_THR_LOCK_RESERVATION
} else if (J9_ARE_ANY_BITS_SET(count, OBJECT_HEADER_LOCK_RESERVED)) {
/* Lock is reserved but unowned.
* (if it were owned the count would be >= OBJECT_HEADER_LOCK_FIRST_RECURSION_BIT)
*/
Trc_VM_objectMonitorExit_Exit_ReservedButUnownedFlatLock(vmStruct, lock, object);
goto done;
#endif /* J9VM_THR_LOCK_RESERVATION */
} else {
/* FLC set, non-recursive. */
J9ObjectMonitor *objectMonitor = objectMonitorInflate(vmStruct, object, lock);

if (NULL == objectMonitor) {
/* Out of memory - impossible? */
monitorExitWriteBarrier();
J9_STORE_LOCKWORD(vmStruct, lockEA, 0);
} else {
omrthread_monitor_t monitor = objectMonitor->monitor;
TRIGGER_J9HOOK_VM_MONITOR_CONTENDED_EXIT(vmStruct->javaVM->hookInterface, vmStruct, monitor);
omrthread_monitor_exit(monitor);
}
}
#endif /* JAVA_SPEC_VERSION >= 24 */
Trc_VM_objectMonitorExit_Exit_FCBSet(vmStruct);
rc = 0;
goto done;
Expand Down Expand Up @@ -308,7 +314,7 @@ objectMonitorExit(J9VMThread* vmStruct, j9object_t object)
#endif /* JAVA_SPEC_VERSION >= 24 */
rc = omrthread_monitor_exit((omrthread_monitor_t)monitor);
#if JAVA_SPEC_VERSION >= 24
if (J9_ARE_ANY_BITS_SET(vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm)
&& (0 != objectMonitor->virtualThreadWaitCount)
) {
J9VM_SEND_VIRTUAL_UNBLOCKER_THREAD_SIGNAL(vm);
Expand Down
2 changes: 1 addition & 1 deletion runtime/vm/threadhelp.cpp
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Expand Up @@ -465,7 +465,7 @@ notifyUnblocker(void *userData)
{
J9VMThread *currentThread = (J9VMThread *)userData;
J9JavaVM *vm = currentThread->javaVM;
if (J9_ARE_ANY_BITS_SET(vm->extendedRuntimeFlags3, J9_EXTENDED_RUNTIME3_YIELD_PINNED_CONTINUATION)) {
if (J9VM_ARE_PINNED_YIELDABLE_VIRTUALTHREADS_ACTIVE(vm)) {
J9VM_SEND_VIRTUAL_UNBLOCKER_THREAD_SIGNAL(vm);
Trc_VM_ThreadHelp_notifyUnblocker(currentThread);
}
Expand Down