[jboss-jira] [JBoss JIRA] (JGRP-1377) Merge: add second line of defense for killing of runaway merge tasks

[Bela Ban (Resolved) (JIRA)]

     [ https://issues.jboss.org/browse/JGRP-1377?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban resolved JGRP-1377.
----------------------------

    Resolution: Done


More work will be done in 3.1, in JGRP-1379
                
> Merge: add second line of defense for killing of runaway merge tasks
> --------------------------------------------------------------------
>
>                 Key: JGRP-1377
>                 URL: https://issues.jboss.org/browse/JGRP-1377
>             Project: JGroups
>          Issue Type: Task
>            Reporter: Bela Ban
>            Assignee: Bela Ban
>             Fix For: 3.0
>
>
> This prevents the following scenario:
> - A merge ID is set and the merge task started
> - If the merge task ends without setting merge-id back to null, subsequent merge requests will be rejected, because the merge coordinator thinks there is a merge still ongoing
> - This should not happen, but I nevertheless want to add a second line of defense to prevent this
> SOLUTION:
> - Whenever a merge-id is assigned and the merge task started, we also keep track of the time this happened
> - A separate timer task is started and runs every (say) M seconds (e.g. 2 minutes)
> - The task checks whether the time stamp of the last merge (if not 0 (= no merge is running)) is more than N seconds old 
> - (M and N are configurable)
> - If this is the case, then we force-cancel the merge
> - The forceCancelMerge() operation is also exposed via JMX, so it can be invoked (e.g.) across a cluster: probe.sh op=GMS.forceCancelMerge

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