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From "Chris Westin (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-2370) Missing cancellation acknowledgements leave orphaned cancelled queries around
Date Wed, 15 Apr 2015 20:29:58 GMT

    [ https://issues.apache.org/jira/browse/DRILL-2370?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14496879#comment-14496879
] 

Chris Westin commented on DRILL-2370:
-------------------------------------

[~jnadeau], it seems like your changes with the new NodeTracker handle dead nodes and take
care of this. Do you agree?

> Missing cancellation acknowledgements leave orphaned cancelled queries around
> -----------------------------------------------------------------------------
>
>                 Key: DRILL-2370
>                 URL: https://issues.apache.org/jira/browse/DRILL-2370
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Flow
>    Affects Versions: 0.7.0
>            Reporter: Chris Westin
>            Assignee: Jacques Nadeau
>             Fix For: 0.9.0
>
>
> When a query is cancelled (say by Foreman.cancel()), Foreman moves to the CANCELLED state,
which indicates that cancellation is in progress. Cancellation requests are sent to remote
drill fragments. These should be replied to via QueryManager.statusUpdate() (inherited from
FragmentStatusListener), which in turn updates Foreman. However, if any of the cancellation
requests are not acknowledged (due to drillbit failure, RPC timeout, etc), then the being-cancelled
query will stay that way indefinitely. We need to have a way to find such queries and force
them to be cleaned up. This may require substituting stub listeners for some of the objects
involved in case cancellation acknowledgements still arrive even later still -- these need
to be safely invokable by the RPC layer even though the query they referred to is gone.



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