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https://issues.apache.org/jira/browse/AMQ-3161?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Craig Condit updated AMQ-3161:
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Attachment: checkpoint-thread.patch
This patch to MessageDatabase.java prevents accidental launching of multiple
Journal checkpoint worker threads.
> Race condition in ActiveMQ Journal Checkpoint worker thread cleanup leads to
> multiple running instances
> -------------------------------------------------------------------------------------------------------
>
> Key: AMQ-3161
> URL: https://issues.apache.org/jira/browse/AMQ-3161
> Project: ActiveMQ
> Issue Type: Bug
> Components: Message Store
> Affects Versions: 5.4.2
> Environment: CentOS 5.2
> Reporter: Craig Condit
> Priority: Critical
> Attachments: checkpoint-thread.patch
>
>
> If the ActiveMQ Journal Checkpoint worker thread dies for any reason, any
> updates to KahaDB trigger the thread to be restarted. Unfortunately, there is
> a race condition between the Thread.isAlive() check and the restart of the
> thread, potentially leading to multiple instances of the thread being
> spawned. We have observed in a busy environment as many as 8-10 instances of
> this thread, all waking up every 5 seconds to perform database checkpoints,
> bringing throughput on the broker to a halt.
> The attached patch adds a lock around access to creation/destruction of this
> thread and prevents a second instance from being launched inadvertently.
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