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From Ufuk Celebi <...@apache.org>
Subject Re: Failing kafka consumer unable to cancel
Date Tue, 17 Nov 2015 10:09:06 GMT
I had a quick chat with Robert and Stephan.

The problem is that the StreamTask cancellation needs to acquire a lock, which is held by
the Kafka client in an infinite loop.

At this point, I’m not sure what our options are here. Maybe Stephan or Robert can chime
in…

– Ufuk

> On 17 Nov 2015, at 10:43, Ufuk Celebi <uce@apache.org> wrote:
> 
> https://issues.apache.org/jira/browse/KAFKA-824
> 
> This has been fixed for Kafka’s 0.9.0 version.
> 
> We should investigate why the job gets stuck though. Do you have a stack trace or any
logs available?
> 
> – Ufuk
> 
>> On 17 Nov 2015, at 09:24, Gyula Fóra <gyfora@apache.org> wrote:
>> 
>> Hey guys,
>> 
>> I ran into some issue with the kafka consumers.
>> 
>> I am reading from more than 50 topics with parallelism 1, and while running
>> the job I got the following exception during the checkpoint notification
>> (offset committing):
>> 
>> java.lang.RuntimeException: Error while confirming checkpoint
>> at org.apache.flink.runtime.taskmanager.Task$2.run(Task.java:935)
>> at java.util.concurrent.Executors$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)
>> Caused by: java.lang.NullPointerException
>> at
>> org.I0Itec.zkclient.ZkConnection.writeDataReturnStat(ZkConnection.java:115)
>> at org.I0Itec.zkclient.ZkClient$10.call(ZkClient.java:817)
>> at org.I0Itec.zkclient.ZkClient.retryUntilConnected(ZkClient.java:675)
>> at org.I0Itec.zkclient.ZkClient.writeDataReturnStat(ZkClient.java:813)
>> at org.I0Itec.zkclient.ZkClient.writeData(ZkClient.java:808)
>> at org.I0Itec.zkclient.ZkClient.writeData(ZkClient.java:777)
>> at kafka.utils.ZkUtils$.updatePersistentPath(ZkUtils.scala:332)
>> at kafka.utils.ZkUtils.updatePersistentPath(ZkUtils.scala)
>> at
>> org.apache.flink.streaming.connectors.kafka.internals.ZookeeperOffsetHandler.setOffsetInZooKeeper(ZookeeperOffsetHandler.java:112)
>> at
>> org.apache.flink.streaming.connectors.kafka.internals.ZookeeperOffsetHandler.commit(ZookeeperOffsetHandler.java:80)
>> at
>> org.apache.flink.streaming.connectors.kafka.FlinkKafkaConsumer.notifyCheckpointComplete(FlinkKafkaConsumer.java:542)
>> at
>> org.apache.flink.streaming.api.operators.AbstractUdfStreamOperator.notifyOfCompletedCheckpoint(AbstractUdfStreamOperator.java:176)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.notifyCheckpointComplete(StreamTask.java:478)
>> at org.apache.flink.runtime.taskmanager.Task$2.run(Task.java:931)
>> ... 5 more
>> 
>> This happened at the same time on multiple kafka consumers. Could this be
>> some Zookeeper related issue? Maybe we should be aware of this.
>> 
>> Another problem is that subsequently the whole pipeline got stuck at the
>> sources while canceling so the job could never restart. Maybe it would be
>> worth killing the whole thing and restart in these situations?
>> 
>> Thanks,
>> Gyula
> 


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