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https://issues.apache.org/activemq/browse/AMQ-2908?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=61769#action_61769
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Gary Tully commented on AMQ-2908:
---------------------------------
a code change like that without a test to validate is just a good start. To
have it committed to trunk it needs a test to validate:
1) the issue still exists
2) to protect the fix into the future
I guess a slow client ack consumer can fill the prefetch and an appropriate ttl
can have them expire, but I wonder what type of client would cause this
behavior is real life, until it acks there will be no further dispatch.
There is an existing check for message expiry on dispatch and on receiving an
ack.
> Slow consumer stops receiving messages because
> PrefetchSubscription.dispatched is filled with expired messages.
> ---------------------------------------------------------------------------------------------------------------
>
> Key: AMQ-2908
> URL: https://issues.apache.org/activemq/browse/AMQ-2908
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.3.2
> Reporter: Siim Kaalep
>
> Slow consumer gets stuck when consuming from queue that has expiring messages
> in it.
> Looked into broker while it got stuck and saw that
> PrefetchSubscription.dispatched is full of expired messages.
> WORKAROUND
> Into doActualDispatch added check that if subscription is full, it will
> remove all expired message from dispatch.
> {code}
> Index:
> trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/PrefetchSubscription.java
> ===================================================================
> ---
> trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/PrefetchSubscription.java
> (revision 42304)
> +++
> trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/PrefetchSubscription.java
> (working copy)
> @@ -400,6 +400,21 @@
> }
> }
>
> + public void removeExpiredMessagesFromDispatch() {
> + synchronized(dispatchLock) {
> + for (Iterator<MessageReference> iter =
> dispatched.iterator(); iter.hasNext(); ) {
> + final MessageReference node = iter.next();
> + if (node.isExpired()) {
> + if (broker.isExpired(node)) {
> +
> node.getRegionDestination().messageExpired(context, this, node);
> + }
> + dispatched.remove(node);
> +
> node.getRegionDestination().getDestinationStatistics().getInflight().decrement();
> + }
> + }
> + }
> + }
> +
> /**
> * Checks an ack versus the contents of the dispatched list.
> *
> {code}
> {code}
> Index:
> trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/Queue.java
> ===================================================================
> ---
> trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/Queue.java
> (revision 42304)
> +++
> trunk/activemq-core/src/main/java/org/apache/activemq/broker/region/Queue.java
> (working copy)
> @@ -1543,6 +1543,9 @@
> }
> if (dispatchSelector.canSelect(s, node)) {
> if (!fullConsumers.contains(s)) {
> + if (s.isFull() && s instanceof
> PrefetchSubscription) {
> +
> ((PrefetchSubscription)s).removeExpiredMessagesFromDispatch();
> + }
> if (!s.isFull()) {
> // Dispatch it.
> s.add(node);
> {code}
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