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https://issues.apache.org/jira/browse/AMQ-5340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14601121#comment-14601121
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Christopher L. Shannon commented on AMQ-5340:
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[~gtully],
I agree, not checking expiry for browsers makes sense. This almost works but
it appears there is something else that would need to be changed too...The
problem is when running the test case against this change, the last run breaks.
The {{enumeration.hasMoreElements()}} returns true but the only thing pending
is the NULL control message so then {{enumeration.nextElement()}} returns null.
It's detecting that no new messages were added in the iterate() method in
Queue and calling brwoser.decrementQueueRef() which sends the NULL control
message. I haven't looked at it yet to figure out why it's doing that.
> QueueBrowser with expired messages hangs until woken by expired messages
> background job
> ---------------------------------------------------------------------------------------
>
> Key: AMQ-5340
> URL: https://issues.apache.org/jira/browse/AMQ-5340
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.9.0, 5.10.0
> Reporter: Vermeulen
> Priority: Critical
> Labels: QueueBrowser
> Attachments: AMQ5340BrowsingPerformanceBug.java,
> AMQ5340BrowsingPerformanceBugCorrected.java, AMQ5340BrowsingWithSpring.java
>
>
> I would expect browsing a queue with only a few messages to not take a long
> time. Indeed it normally takes only a few ms. in my application. But
> sometimes the ActiveMQQueueBrowser hangs for up to 30 seconds at method
> before returning!
> When the issue occurs, the loop in hasMoreElements() calls waitForMessage()
> multiple times which times out after 2s at semaphore.wait(2000) without
> receiving any message from the broker. I found that when the broker's
> background job that checks for expired messages runs, the browser happens to
> be woken even if there are no expired messages. So setting the
> expireMessagesPeriod to a low value (e.g. 200ms) is a good workaround for
> this issue, but this is quite brittle because it uses internal broker
> implementation that may not even be related to the issue!
> To reproduce:
> - (this is what I do in my application) create a queue, send a few message
> with an expiration time of 10 seconds and repeatedly browse it until it is
> empty. If I browse the queue after these 10 seconds have passed, the issue
> occurs!
> - I can always reproduce the issue by running AMQ580BrowsingBug from the
> related bug report AMQ-4595: this browsing test seems to always hang. I
> slightly adjusted the test so you can easily change the expired messages
> period and see the runtime differ when changing this.
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