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From "Chris Westin (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-2370) Missing cancellation acknowledgements leave orphaned cancelled queries around
Date Tue, 03 Mar 2015 23:29:04 GMT
Chris Westin created DRILL-2370:

             Summary: Missing cancellation acknowledgements leave orphaned cancelled queries
                 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: Chris Westin

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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