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ASF GitHub Bot logged work on BEAM-4798: ---------------------------------------- Author: ASF GitHub Bot Created on: 20/Jul/18 09:23 Start Date: 20/Jul/18 09:23 Worklog Time Spent: 10m Work Description: aljoscha commented on a change in pull request #5996: [BEAM-4798] Fix IndexOutOfBoundsException in Flink runner URL: https://github.com/apache/beam/pull/5996#discussion_r203985863 ########## File path: runners/flink/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/UnboundedSourceWrapper.java ########## @@ -202,7 +202,15 @@ public void run(SourceContext<WindowedValue<ValueWithRecordId<OutputT>>> ctx) th ReaderInvocationUtil<OutputT, UnboundedSource.UnboundedReader<OutputT>> readerInvoker = new ReaderInvocationUtil<>(stepName, serializedOptions.get(), metricContainer); - if (localReaders.size() == 1) { + if (localReaders.size() == 0) { + // It can happen when value of parallelism is greater than number of IO readers (for example, + // parallelism is 2 and number of Kafka topic partitions is 1). In this case, we just idle + // this executor. + LOG.warn("Number of readers is 0, idle"); + while (isRunning) { Review comment: we can just let this fall through to the idle loop at the end ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org Issue Time Tracking ------------------- Worklog Id: (was: 125410) Time Spent: 40m (was: 0.5h) > IndexOutOfBoundsException when Flink parallelism > 1 > ---------------------------------------------------- > > Key: BEAM-4798 > URL: https://issues.apache.org/jira/browse/BEAM-4798 > Project: Beam > Issue Type: Bug > Components: runner-flink > Affects Versions: 2.4.0, 2.5.0 > Reporter: Alexey Romanenko > Assignee: Alexey Romanenko > Priority: Major > Time Spent: 40m > Remaining Estimate: 0h > > Running job on Flink in streaming mode and get data from a Kafka topic with > parallelism > 1 causes an exception: > {noformat} > Caused by: java.lang.IndexOutOfBoundsException: Index: 0, Size: 0 > at java.util.ArrayList.rangeCheck(ArrayList.java:657) > at java.util.ArrayList.get(ArrayList.java:433) > at > org.apache.beam.runners.flink.translation.wrappers.streaming.io.UnboundedSourceWrapper.run(UnboundedSourceWrapper.java:277) > at > org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:87) > at > org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:56) > at > org.apache.flink.streaming.runtime.tasks.SourceStreamTask.run(SourceStreamTask.java:99) > at > org.apache.flink.streaming.runtime.tasks.StoppableSourceStreamTask.run(StoppableSourceStreamTask.java:45) > at > org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:306) > at org.apache.flink.runtime.taskmanager.Task.run(Task.java:703) > at java.lang.Thread.run(Thread.java:748) > {noformat} > It happens when number of Kafka topic partitions is less than value of > parallelism (number of task slots). > So, workaround for now can be to set parallelism <= number of topic > partitions, thus if parallelism=2 then number_partitions >= 2 -- This message was sent by Atlassian JIRA (v7.6.3#76005)