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https://issues.apache.org/jira/browse/BEAM-1784?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eugene Kirpichov closed BEAM-1784.
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Resolution: Fixed
Fix Version/s: First stable release
> DataflowPipelineJob.cancel() should be idempotent
> -------------------------------------------------
>
> Key: BEAM-1784
> URL: https://issues.apache.org/jira/browse/BEAM-1784
> Project: Beam
> Issue Type: Bug
> Components: runner-dataflow
> Reporter: Eugene Kirpichov
> Assignee: Eugene Kirpichov
> Fix For: First stable release
>
>
> Right now DataflowPipelineJob.cancel() issues an RPC to the Dataflow service
> and, if it fails, checks whether the job is in a terminal state - in that
> case the failure is ignored.
> Ideally, the Dataflow-side cancel call itself would be idempotent, and would
> succeed even if the job is already terminated. However, right now this is not
> the case.
> Additionally, Dataflow service can, for a short time, return RUNNING state
> even for a job that has already been cancelled (i.e. it will reject cancel()
> calls, but will report state as RUNNING).
> Because of this, if you call DataflowPipelineJob.cancel() multiple times, it
> might fail (throw an exception). Calling cancel() multiple times should,
> logically, be ok. So, to partially work around these issues of the Dataflow
> service, we can make DataflowPipelineJob.cancel() be idempotent by itself,
> i.e. absorb duplicate cancel() requests. This, of course, doesn't address the
> case when the job terminates externally almost concurrently to calling
> DataflowPipelineJob.cancel() - but it's an improvement.
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