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https://issues.apache.org/jira/browse/STORM-497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14137192#comment-14137192
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ASF GitHub Bot commented on STORM-497:
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GitHub user revans2 opened a pull request:
https://github.com/apache/incubator-storm/pull/257
STORM-497: don't modify the mapping while the someone could be reading it.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/revans2/incubator-storm STORM-497
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-storm/pull/257.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #257
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commit f259f1da288171a9393fb500150d034ccca0d146
Author: Robert (Bobby) Evans <[email protected]>
Date: 2014-09-17T13:07:42Z
STORM-497: don't modify the mapping while the someone could be reading it.
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> b.s.m.netty.Server.getMessageQueueId is not thread safe, and can return null
> ----------------------------------------------------------------------------
>
> Key: STORM-497
> URL: https://issues.apache.org/jira/browse/STORM-497
> Project: Apache Storm (Incubating)
> Issue Type: Bug
> Affects Versions: 0.9.3-incubating
> Reporter: Robert Joseph Evans
> Priority: Critical
>
> b.s.m.netty.Server.getMessageQueueId
> https://github.com/apache/incubator-storm/blob/c5c3571ca15ee2dd675fb3cac44bd0f926ccfc67/storm-core/src/jvm/backtype/storm/messaging/netty/Server.java#L132-150
> If there is contention when updating taskToQueueId subsequent threads through
> the synchronized block do not set queueId and the function returns null.
> Also reading from a HashMap while someone else is updating it, even with a
> lock held, can result in a deadlock. I have seen this happen before on
> Hadoop. It is likely to be very rare, but I would rather use transactional
> memory, aka an AtomicReference, to avoid this entirely.
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