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https://issues.apache.org/jira/browse/AMQ-5542?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14296281#comment-14296281
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Tim Bain commented on AMQ-5542:
-------------------------------
One option to work around this problem might be to have a job that periodically
consumes all DLQ messages and re-sends them to the DLQ as a new message. That
way the dead messages are always near the newest messages in KahaDB and it can
delete the old files. You'll lose metadata about when the original message was
sent/received/etc., but that may be better than what you have now. (And you
could always wrap the original message, with all its metadata, in a wrapper
message if you wanted to keep that info.) This should still get fixed and the
improvement I submitted should still get implemented, but that workaround might
get you by until the improvement gets implemented.
> KahaDB data files containing acknowledgements are deleted during cleanup
> ------------------------------------------------------------------------
>
> Key: AMQ-5542
> URL: https://issues.apache.org/jira/browse/AMQ-5542
> Project: ActiveMQ
> Issue Type: Bug
> Components: Message Store
> Affects Versions: 5.10.0, 5.10.1
> Reporter: Sergiy Barlabanov
> Attachments: AMQ-5542.patch, AdjustedAMQ2832Test.patch
>
>
> AMQ-2832 was not fixed cleanly.
> The commit dd68c61e65f24b7dc498b36e34960a4bc46ded4b by Gary from 8.10.2010
> introduced a problem by deleting too many files.
> Scenarios we are facing currently in production:
> Data file #1 contains unconsumed messages sitting in a DLQ. So this file is
> not a cleanup candidate.
> The next file #2 contains acks of some messages from file #1. This file is
> not a cleanup candidate (because of ackMessageFileMap logic).
> The next file #3 contains acks of some messages from file #2. And this file
> is deleted during the cleanup procedure. So on Broker restart all messages
> from #2, whose acks were from the deleted file #3, are replayed!
> The reason is gcCandidates variable, which is a copy of gcCandidateSet (see
> MessageDatabase#checkpointUpdate at the end of the method -
> org/apache/activemq/store/kahadb/MessageDatabase.java:1659 on 5.10.0 tag). So
> when a candidate is deleted from gcCandidateSet
> (org/apache/activemq/store/kahadb/MessageDatabase.java:1668 on 5.10.0 tag),
> gcCandidates still contains that candidate and the comparison on
> org/apache/activemq/store/kahadb/MessageDatabase.java:1666 works wrong!
> I will try to adjust AMQ2832Test.
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