Vermeulen created AMQ-5340:
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Summary: QueueBrowser hangs until accidentally 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: 5.10.0, 5.9.0
Reporter: Vermeulen
Priority: Critical
I would expected browsing a queue with only a few messages to not take 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 with that.
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