[jira] [Commented] (BEAM-1835) NPE in DirectRunner PubsubReader.ackBatch

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BEAM-1835?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15955995#comment-15955995 ] 

ASF GitHub Bot commented on BEAM-1835:
--------------------------------------

Github user asfgit closed the pull request at:

    https://github.com/apache/beam/pull/2368


> NPE in DirectRunner PubsubReader.ackBatch
> -----------------------------------------
>
>                 Key: BEAM-1835
>                 URL: https://issues.apache.org/jira/browse/BEAM-1835
>             Project: Beam
>          Issue Type: Bug
>          Components: runner-direct, sdk-java-core
>            Reporter: Rafal Wojdyla
>            Assignee: Rafal Wojdyla
>             Fix For: First stable release
>
>
> DirectRunner streaming mode throws null pointer exception:
> {noformat}
> org.apache.beam.sdk.io.PubsubUnboundedSource$PubsubReader.ackBatch(PubsubUnboundedSource.java:639)
>   at org.apache.beam.sdk.io.PubsubUnboundedSource$PubsubCheckpoint.finalizeCheckpoint(PubsubUnboundedSource.java:312)
>   at org.apache.beam.runners.direct.UnboundedReadEvaluatorFactory$UnboundedReadEvaluator.finishRead(UnboundedReadEvaluatorFactory.java:223)
>   at org.apache.beam.runners.direct.UnboundedReadEvaluatorFactory$UnboundedReadEvaluator.processElement(UnboundedReadEvaluatorFactory.java:144)
>   at org.apache.beam.runners.direct.TransformExecutor.processElements(TransformExecutor.java:139)
>   at org.apache.beam.runners.direct.TransformExecutor.run(TransformExecutor.java:107)
>   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
>   at java.util.concurrent.FutureTask.run(FutureTask.java:266)
>   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
>   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
>   at java.lang.Thread.run(Thread.java:745)
> {noformat}
> This does not happen always, but for large enough number of events it's pretty reproducible. The problems seems to be the concurrent reuse of a reader among multiple threads, and a race condition, when one of the threads "decided" to close the reader, based on:
> {code}
> private static final double DEFAULT_READER_REUSE_CHANCE = 0.95;
> {code}
> the close, nulls out pubsub client:
> {code}
>     @Override
>     public void close() throws IOException {
>       if (pubsubClient != null) {
>         pubsubClient.close();
>         pubsubClient = null;
>       }
>     }
> {code}
> which if still in use by other thread will result in NPE above.



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