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From Aljoscha Krettek <aljos...@apache.org>
Subject Re: ArrayIndexOutOfBoundExceptions while processing valve output watermark and while applying ReduceFunction in reducing state
Date Thu, 12 Oct 2017 20:12:19 GMT
I think I finally found the problem, there was also already another bug report for this: https://issues.apache.org/jira/browse/FLINK-7484

> On 12. Oct 2017, at 18:22, Federico D'Ambrosio <federico.dambrosio@smartlab.ws>
wrote:
> 
> Hi Aljoscha, 
> 
> yes, just like you're guessing, without asynchronous checkpoints, there has been no crash
so far.
> 
> Regards,
> Federico
> 
> 2017-10-12 18:08 GMT+02:00 Aljoscha Krettek <aljoscha@apache.org <mailto:aljoscha@apache.org>>:
> Hi Federico,
> 
> I'm guessing the job is still working without asynchronous watermarks? I'm very eager
to figure out what is actually going wrong with asynchronous checkpoints.
> 
> Best,
> Aljoscha
> 
> 
>> On 2. Oct 2017, at 11:57, Federico D'Ambrosio <federico.dambrosio@smartlab.ws
<mailto:federico.dambrosio@smartlab.ws>> wrote:
>> 
>> As a followup:
>> 
>> the flink job has currently an uptime of almost 24 hours, with no checkpoint failed
or restart whereas, with async snapshots, it would have already crashed 50 or so times.
>> 
>> Regards,
>> Federico
>> 
>> 2017-09-30 19:01 GMT+02:00 Federico D'Ambrosio <federico.dambrosio@smartlab.ws
<mailto:federico.dambrosio@smartlab.ws>>:
>> Thank you very much, Gordon.
>> 
>> I'll try to run the job without the asynchronous snapshots first thing.
>> 
>> As for the Event data type: it's a case class with 2 fields: a String ID and a composite
case class (let's call it RealEvent) containing 3 fields of the following types: Information,
which is a case class with String fields, Coordinates, a nested case class with 2 Double and
InstantValues, with 3 Integers and a DateTime.This DateTime field in InstantValues is the
one being evalued in the maxBy (via InstantValues and RealEvent compareTo implementations,
because dot notation is not working in scala as of 1.3.2, FLINK-7629 <https://issues.apache.org/jira/browse/FLINK-7629>)
and that was the reason in the first place I had to register the JodaDateTimeSerializer with
Kryo.
>> 
>> Regards,
>> Federico
>> 
>> 
>> 
>> 
>> 2017-09-30 18:08 GMT+02:00 Tzu-Li (Gordon) Tai <tzulitai@apache.org <mailto:tzulitai@apache.org>>:
>> Hi,
>> 
>> Thanks for the extra info, it was helpful (I’m not sure why your first logs didn’t
have the full trace, though).
>> 
>> I spent some time digging through the error trace, and currently have some observations
I would like to go through first:
>> 
>> 1. So it seems like the ArrayIndexOutOfBoundsException was thrown while trying to
access the state and making a copy (via serialization) in the CopyOnWriteStateTable.
>> 2. The state that caused the exception seems to be the state of the reducing window
function (i.e. the maxBy). The state type should be the same as the records in your `events`
DataStream, which seems to be a Scala case class with some nested field that requires Kryo
for serialization.
>> 3. Somehow Kryo failed with the ArrayIndexOutOfBoundsException when trying to copy
that field ..
>> 
>> My current guess would perhaps be that the serializer internally used may have been
incorrectly shared, which is probably why this exception happens randomly for you.
>> I recall that there were similar issues that occurred before due to the fact that
some KryoSerializers aren't thread-safe and was incorrectly shared in Flink.
>> 
>> I may need some help from you to be able to look at this a bit more:
>> - Is it possible that you disable asynchronous snapshots and try running this job
a bit more to see if the problem still occurs? This is mainly to eliminate my guess on whether
or not there is some incorrect serializer usage in the CopyOnWriteStateTable.
>> - Could you let us know what your `events` DataStream records type case class looks
like?
>> 
>> Also looping in Aljoscha and Stefan here, as they would probably have more insights
in this.
>> 
>> Cheers,
>> Gordon
>> 
>> On 30 September 2017 at 10:56:33 AM, Federico D'Ambrosio (federico.dambrosio@smartlab.ws
<mailto:federico.dambrosio@smartlab.ws>) wrote:
>> 
>>> Hi Gordon,
>>> 
>>> I remembered that I had already seen this kind of exception once during the testing
of the current job and fortunately I had the complete stacktrace still saved on my pc:
>>> 
>>> Caused by: java.lang.ArrayIndexOutOfBoundsException: -1
>>>         at com.esotericsoftware.kryo.util.IntArray.pop(IntArray.java:157)
>>>         at com.esotericsoftware.kryo.Kryo.reference(Kryo.java:822)
>>>         at com.esotericsoftware.kryo.Kryo.copy(Kryo.java:863)
>>>         at org.apache.flink.api.java.typeutils.runtime.kryo.KryoSerializer.copy(KryoSerializer.java:176)
>>>         at org.apache.flink.api.scala.typeutils.CaseClassSerializer.copy(CaseClassSerializer.scala:101)
>>>         at org.apache.flink.api.scala.typeutils.CaseClassSerializer.copy(CaseClassSerializer.scala:32)
>>>         at org.apache.flink.api.scala.typeutils.CaseClassSerializer.copy(CaseClassSerializer.scala:101)
>>>         at org.apache.flink.api.scala.typeutils.CaseClassSerializer.copy(CaseClassSerializer.scala:32)
>>>         at org.apache.flink.runtime.state.heap.CopyOnWriteStateTable.ge <http://heap.copyonwritestatetable.ge/>t(CopyOnWriteStateTable.java:279)
>>>         at org.apache.flink.runtime.state.heap.CopyOnWriteStateTable.ge <http://heap.copyonwritestatetable.ge/>t(CopyOnWriteStateTable.java:296)
>>>         at org.apache.flink.runtime.state.heap.HeapReducingState.get(HeapReducingState.java:68)
>>>         at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator.onEventTime(WindowOperator.java:498)
>>>         at org.apache.flink.streaming.api.operators.HeapInternalTimerService.advanceWatermark(HeapInternalTimerService.java:275)
>>>         at org.apache.flink.streaming.api.operators.InternalTimeServiceManager.advanceWatermark(InternalTimeServiceManager.java:107)
>>>         at org.apache.flink.streaming.api.operators.AbstractStreamOperator.processWatermark(AbstractStreamOperator.java:946)
>>>         at org.apache.flink.streaming.runtime.io <http://runtime.io/>.StreamInputProcessor$ForwardingValveOutputHandler.handleWatermark(StreamInputProcessor.java:286)
>>>         at org.apache.flink.streaming.runtime.io <http://runtime.io/>.StreamInputProcessor$ForwardingValveOutputHandler.handleWatermark(StreamInputProcessor.java:289)
>>>         at org.apache.flink.streaming.runtime.streamstatus.StatusWatermarkValve.findAndOutputNewMinWatermarkAcrossAlignedChannels(StatusWatermarkValve.java:173)
>>>         at org.apache.flink.streaming.runtime.streamstatus.StatusWatermarkValve.inputWatermark(StatusWatermarkValve.java:108)
>>>         at org.apache.flink.streaming.runtime.io <http://runtime.io/>.StreamInputProcessor.processInput(StreamInputProcessor.java:188)
>>>         at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:69)
>>>         at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:263)
>>>         at org.apache.flink.runtime.taskmanager.Task.run(Task.java:702)
>>>         at java.lang.Thread.run(Thread.java:748)
>>> 
>>> I don't know why now the stacktrace is getting output only for the first parts
(handleWatermark and HeapReducingState).
>>> 
>>> So, it looks like something that has to do with the KryoSerializer. As a KryoSerializer
I'm using JodaDateTimeSerializer, registered as follows:
>>> 
>>> env.getConfig.addDefaultKryoSerializer(classOf[DateTime], classOf[JodaDateTimeSerializer])
>>> 
>>> I hope this could help.
>>> 
>>> Regards,
>>> Federico
>>> 
>>> 2017-09-29 15:54 GMT+02:00 Federico D'Ambrosio <federico.dambrosio@smartlab.ws
<mailto:federico.dambrosio@smartlab.ws>>:
>>> Hi Gordon,
>>> 
>>> I'm currently using Flink 1.3.2 in local mode.
>>> 
>>> If it's any help I realized from the log that the complete task which is failing
is:
>>> 
>>> 2017-09-29 14:17:20,354 INFO  org.apache.flink.runtime.taskmanager.Task     
               - latest_time -> (map_active_stream, map_history_stream) (1/1) (5a6c9f187326f678701f939665db6685)
switched from RUNNING to FAILED.
>>> 
>>> val events = keyedStreamByID 
>>>   .window(TumblingEventTimeWindows.of(Time.seconds(20)))
>>>   .maxBy("time").name("latest_time").uid("latest_time")
>>> 
>>> 
>>> val activeStream = events
>>>   //Serialization to JsValue
>>>   .map(event => event.toMongoActiveJsValue).name("map_active_stream").uid("map_active_stream")
>>>   //Global windowing, the cause of exception should be above
>>>   .timeWindowAll(Time.seconds(10))
>>>   .apply(new MongoWindow(MongoWritingType.UPDATE)).name("active_stream_window").uid("active_stream_window")
>>> 
>>> val historyStream = airtrafficEvents
>>>   //Serialization to JsValue
>>>   .map(event => event.toMongoHistoryJsValue).name("map_history_stream").uid("map_history_stream")
>>>   //Global windowing, the cause of exception should be above
>>>   .timeWindowAll(Time.seconds(10))
>>>   .apply(new MongoWindow(MongoWritingType.UPDATE)).name("history_stream_window").uid("history_stream_window")
>>> 
>>> 
>>> 
>>> Regards,
>>> Federico
>>> 
>>> 2017-09-29 15:38 GMT+02:00 Tzu-Li (Gordon) Tai <tzulitai@apache.org <mailto:tzulitai@apache.org>>:
>>> Hi,
>>> 
>>> I’m looking into this. Could you let us know the Flink version in which the
exceptions occurred?
>>> 
>>> Cheers,
>>> Gordon
>>> 
>>> 
>>> On 29 September 2017 at 3:11:30 PM, Federico D'Ambrosio (federico.dambrosio@smartlab.ws
<mailto:federico.dambrosio@smartlab.ws>) wrote:
>>> 
>>>> Hi, I'm coming across these Exceptions while running a pretty simple flink
job.
>>>> First one:
>>>> java.lang.RuntimeException: Exception occurred while processing valve output
watermark:   
>>>>         at org.apache.flink.streaming.runtime.io <http://runtime.io/>.StreamInputProcessor$ForwardingValveOutputHandler.handleWatermark(StreamInputProcessor.java:289)
>>>>         at org.apache.flink.streaming.runtime.streamstatus.StatusWatermarkValve.findAndOutputNewMinWatermarkAcrossAlignedChannels(StatusWatermarkValve.java:173)
>>>>         at org.apache.flink.streaming.runtime.streamstatus.StatusWatermarkValve.inputWatermark(StatusWatermarkValve.java:108)
>>>>         at org.apache.flink.streaming.runtime.io <http://runtime.io/>.StreamInputProcessor.processInput(StreamInputProcessor.java:188)
>>>>         at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:69)
>>>>         at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:263)
>>>>         at org.apache.flink.runtime.taskmanager.Task.run(Task.java:702)
>>>>         at java.lang.Thread.run(Thread.java:748)
>>>> Caused by: java.lang.ArrayIndexOutOfBoundsException
>>>> 
>>>> The second one:
>>>> java.io.IOException: Exception while applying ReduceFunction in reducing
state
>>>>         at org.apache.flink.runtime.state.heap.HeapReducingState.add(HeapReducingState.java:82)
>>>>         at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator.processElement(WindowOperator.java:442)
>>>>         at org.apache.flink.streaming.runtime.io <http://runtime.io/>.StreamInputProcessor.processInput(StreamInputProcessor.java:206)
>>>>         at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:69)
>>>>         at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:263)
>>>>         at org.apache.flink.runtime.taskmanager.Task.run(Task.java:702)
>>>>         at java.lang.Thread.run(Thread.java:748)
>>>> Caused by: java.lang.ArrayIndexOutOfBoundsException
>>>> 
>>>> 
>>>> Since it looks like something is wrong in Watermark processing, in my case
Watermarks are generated in my KafkaSource:
>>>> 
>>>> val stream = env.addSource(
>>>>   new FlinkKafkaConsumer010[Event](topic, new JSONDeserializationSchema(),
consumerConfig)
>>>>     .setStartFromLatest()
>>>>     .assignTimestampsAndWatermarks(
>>>>       new BoundedOutOfOrdernessTimestampExtractor[Event](Time.seconds(10))
{
>>>>         def extractTimestamp(element: AirTrafficEvent): Long =
>>>>           element.instantValues.time.getMillis
>>>>       })
>>>> )
>>>> These exceptions aren't really that informative per se and, from what I see,
the task triggering these exceptions is the following operator:
>>>> 
>>>> val events = keyedStreamByID
>>>>   .window(TumblingEventTimeWindows.of(Time.seconds(20)))
>>>>   .maxBy("timestamp").name("latest_time").uid("latest_time")
>>>> 
>>>> What could be the problem here in your opinion? It's not emitting watermarks
correctly? I'm not even how I could reproduce this exceptions, since it looks like they happen
pretty much randomly.
>>>> 
>>>> Thank you all,
>>>> Federico D'Ambrosio
>>> 
>>> 
>>> 
>>> --
>>> Federico D'Ambrosio
>>> 
>>> 
>>> 
>>> --
>>> Federico D'Ambrosio
>> 
>> 
>> 
>> -- 
>> Federico D'Ambrosio
>> 
>> 
>> 
>> -- 
>> Federico D'Ambrosio
> 
> 
> 
> 
> -- 
> Federico D'Ambrosio


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