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ARTEMIS-1604 Artemis deadlock using MQTT Protocol 

Direct and async deliveries lock QueueImpl::this and
ServerConsumerImpl::this in different order causing deadlock:
has been introduced a deliverLock to prevent both type of delivers
to concurrently happen, making irrelevant the lock ordering.
This commit is contained in:
Francesco Nigro 2019-03-11 14:04:35 +01:00
parent a6dc57967b
commit c83fce8db4
1 changed files with 70 additions and 46 deletions
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28
artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/QueueImpl.java
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@ -39,6 +39,7 @@ import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicLongFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.activemq.artemis.api.config.ActiveMQDefaultConfiguration;
import org.apache.activemq.artemis.api.core.ActiveMQException;
@ -210,6 +211,9 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
private final Runnable deliverRunner = new DeliverRunner();
//This lock is used to prevent deadlocks between direct and async deliveries
private final ReentrantLock deliverLock = new ReentrantLock();
private volatile boolean depagePending = false;
private final StorageManager storageManager;
@ -881,7 +885,7 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
return;
}
if (supportsDirectDeliver && !directDeliver && direct && System.currentTimeMillis() - lastDirectDeliveryCheck > CHECK_QUEUE_SIZE_PERIOD) {
if (direct && supportsDirectDeliver && !directDeliver && System.currentTimeMillis() - lastDirectDeliveryCheck > CHECK_QUEUE_SIZE_PERIOD) {
if (logger.isTraceEnabled()) {
logger.trace("Checking to re-enable direct deliver on queue " + this.getName());
}
@ -3069,6 +3073,20 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
* This method delivers the reference on the callers thread - this can give us better latency in the case there is nothing in the queue
*/
private boolean deliverDirect(final MessageReference ref) {
//The order to enter the deliverLock re QueueImpl::this lock is very important:
//- acquire deliverLock::lock
//- acquire QueueImpl::this lock
//DeliverRunner::run is doing the same to avoid deadlocks.
//Without deliverLock, a directDeliver happening while a DeliverRunner::run
//could cause a deadlock.
//Both DeliverRunner::run and deliverDirect could trigger a ServerConsumerImpl::individualAcknowledge:
//- deliverDirect first acquire QueueImpl::this, then ServerConsumerImpl::this
//- DeliverRunner::run first acquire ServerConsumerImpl::this then QueueImpl::this
if (!deliverLock.tryLock()) {
logger.tracef("Cannot perform a directDelivery because there is a running async deliver");
return false;
}
try {
synchronized (this) {
if (!supportsDirectDeliver) {
return false;
@ -3121,6 +3139,9 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
}
return false;
}
} finally {
deliverLock.unlock();
}
}
private Consumer getGroupConsumer(SimpleString groupID) {
@ -3464,8 +3485,11 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
enterCritical(CRITICAL_DELIVER);
boolean needCheckDepage = false;
try {
synchronized (QueueImpl.this.deliverRunner) {
deliverLock.lock();
try {
needCheckDepage = deliver();
} finally {
deliverLock.unlock();
}
} finally {
leaveCritical(CRITICAL_DELIVER);