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https://issues.apache.org/jira/browse/AMQ-7132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16743370#comment-16743370
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Christopher L. Shannon commented on AMQ-7132:
---------------------------------------------
I am running Java 8 and so is Jenkins. All 3 tests hang for me running on the
latest Fedora (just like Jenkins)
It hangs from me both from Eclipse and from Maven. I'll take a look at it
tomorrow closer.
> ActiveMQ reads lots of index pages upon startup (after a graceful or
> ungraceful shutdown)
> -----------------------------------------------------------------------------------------
>
> Key: AMQ-7132
> URL: https://issues.apache.org/jira/browse/AMQ-7132
> Project: ActiveMQ
> Issue Type: Improvement
> Components: KahaDB
> Affects Versions: 5.15.8
> Reporter: Alan Protasio
> Assignee: Christopher L. Shannon
> Priority: Major
> Fix For: 5.16.0
>
>
> Hi.
> We noticed that ActiveMQ reads lots of pages in the index file when is
> starting up to recover the destinations statistics:
> [https://github.com/apache/activemq/blob/master/activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/KahaDBStore.java#L819]
> Nowadays, in order to do that, activemq traverse the
> storedDestination.locationIndex to get the messageCount and totalMessageSize
> of each destination. For destinations with lots of messages this process can
> take a while making the startup process take long time.
> In a case of a master-slave broker, this prevent the broker to fast failover
> and does not meet what is stated on
> [http://activemq.apache.org/shared-file-system-master-slave.html.]
> {quote}If you have a SAN or shared file system it can be used to provide
> _high availability_ such that if a broker is killed, another broker can take
> over immediately.
> {quote}
> One solution for this is keep track of the destination statistics summary in
> the index file and doing so, we dont need to read all the locationIndex on
> the start up.
> The code change proposed is backward compatible but need a bump on the kahadb
> version. If this information is not in the index, the broker will fall back
> to the current implementation, which means that the first time people upgrade
> to the new version, it will still have to read the locationIndex, but
> subsequent restarts will be fast.
> This change should have a negligible performance impact during normal
> activemq operation, as this change introduce a few more bytes of data to the
> index and this information will be on checkpoints. Also, this new information
> is synchronized with the locationIndex as they are update at the same
> transaction.
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