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From "Tim Bain (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMQ-5542) KahaDB data files containing acknowledgements are deleted during cleanup
Date Thu, 29 Jan 2015 02:29:34 GMT

    [ https://issues.apache.org/jira/browse/AMQ-5542?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14296281#comment-14296281
] 

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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