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From Stephan Ewen <se...@apache.org>
Subject Re: Failing kafka consumer unable to cancel
Date Tue, 17 Nov 2015 10:26:22 GMT
Another idea: The bug is fixed in the Zookeeper Client that Kafka uses, so
if we can bump the transitive dependency, that might fix it...

On Tue, Nov 17, 2015 at 11:19 AM, Stephan Ewen <sewen@apache.org> wrote:

> Hey!
>
> The problem here is that there is no such thing as proper thread killing
> in Java (at least it makes everything unstable if you do). Threads need to
> exit cooperatively.
>
> The Kafka Function calls simply are uninterruptibly stuck and never return
> (pretty bad bug in their Zookeeper Client). As far as I know one cannot
> clean this up properly unless one kills the process.
>
> We could try and work around this by running the Zookeeper commit in a
> dedicated lightweight thread that shares no resources and thus does not
> make the system unstable if stopped (against better advise ;-) )
>
> Stephan
>
>
>
>
>
> On Tue, Nov 17, 2015 at 10:43 AM, 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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