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From "Frank Lyaruu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (KAFKA-4311) Multi layer cache eviction causes forwarding to incorrect ProcessorNode
Date Sat, 29 Oct 2016 09:10:58 GMT

    [ https://issues.apache.org/jira/browse/KAFKA-4311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15617788#comment-15617788
] 

Frank Lyaruu commented on KAFKA-4311:
-------------------------------------

I couldn't reproduce the problems from the (pretty slow) networks  while travelling, but now
I'm back and I see the problem again (with the old code)

Your latest changes seem to solve the problem and I don't see the IllegalStateExceptions any
more. So with that I think this issue can be closed!

> Multi layer cache eviction causes forwarding to incorrect ProcessorNode 
> ------------------------------------------------------------------------
>
>                 Key: KAFKA-4311
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4311
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 0.10.1.0
>            Reporter: Damian Guy
>            Assignee: Damian Guy
>             Fix For: 0.10.1.1
>
>
> The two exceptions below were reported by Frank on the dev mailing list. After investigation,
the root cause is multiple cache evictions happening in the same topology. 
> Given a topology like the one below. If a record arriving in `tableOne` causes a cache
eviction, it will trigger the `leftJoin` that will do a `get` from `reducer-store`. If the
key is not currently cached in `reducer-store`, but is in the backing store, it will be put
into the cache, and it may also trigger an eviction. If it does trigger an eviction and the
eldest entry is dirty it will flush the dirty keys. It is at this point that the exception
in the comment happens (ClassCastException). This occurs because the ProcessorContext is still
set to the context of the `leftJoin` and the next child in the topology is `mapValues`.
> We need to set the correct `ProcessorNode`, on the context,  in the `ForwardingCacheFlushListener`
prior to calling `context.forward`. We also need to set remember to reset the `ProcessorNode`
to the previous node once `context.forward` has completed.
> {code}
>         final KTable<String, String> one = builder.table(Serdes.String(), Serdes.String(),
tableOne, tableOne);
>         final KTable<Long, String> two = builder.table(Serdes.Long(), Serdes.String(),
tableTwo, tableTwo);
>         final KTable<String, Long> reduce = two.groupBy(new KeyValueMapper<Long,
String, KeyValue<String, Long>>() {
>             @Override
>             public KeyValue<String, Long> apply(final Long key, final String value)
{
>                 return new KeyValue<>(value, key);
>             }
>         }, Serdes.String(), Serdes.Long())
>                 .reduce(new Reducer<Long>() {
>                     @Override
>                     public Long apply(final Long value1, final Long value2) {
>                         return value1 + value2;
>                     }
>                 }, new Reducer<Long>() {
>                     @Override
>                     public Long apply(final Long value1, final Long value2) {
>                         return value1 - value2;
>                     }
>                 }, "reducer-store");
>     one.leftJoin(reduce, new ValueJoiner<String, Long, String>() {
>             @Override
>             public String apply(final String value1, final Long value2) {
>                 return value1 + ":" + value2;
>             }
>         })
>         .mapValues(new ValueMapper<String, String>() {
>                     @Override
>                     public String apply(final String value) {
>                         return value;
>                     }
>                 });
> {code}
> This exception is actually a symptom of the exception reported below in the comment.
After the first exception is thrown, the StreamThread triggers a shutdown that then throws
this exception.
> [StreamThread-1] ERROR
> org.apache.kafka.streams.processor.internals.StreamThread - stream-thread
> [StreamThread-1] Failed to close state manager for StreamTask 0_0:
> org.apache.kafka.streams.errors.ProcessorStateException: task [0_0] Failed
> to close state store addr-organization
> at
> org.apache.kafka.streams.processor.internals.ProcessorStateManager.close(ProcessorStateManager.java:342)
> at
> org.apache.kafka.streams.processor.internals.AbstractTask.closeStateManager(AbstractTask.java:121)
> at
> org.apache.kafka.streams.processor.internals.StreamThread$2.apply(StreamThread.java:341)
> at
> org.apache.kafka.streams.processor.internals.StreamThread.performOnAllTasks(StreamThread.java:322)
> at
> org.apache.kafka.streams.processor.internals.StreamThread.closeAllStateManagers(StreamThread.java:338)
> at
> org.apache.kafka.streams.processor.internals.StreamThread.shutdownTasksAndState(StreamThread.java:299)
> at
> org.apache.kafka.streams.processor.internals.StreamThread.shutdown(StreamThread.java:262)
> at
> org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:245)
> Caused by: java.lang.IllegalStateException: Key found in dirty key set, but
> entry is null
> at
> org.apache.kafka.streams.state.internals.NamedCache.flush(NamedCache.java:112)
> at
> org.apache.kafka.streams.state.internals.ThreadCache.flush(ThreadCache.java:100)
> at
> org.apache.kafka.streams.state.internals.CachingKeyValueStore.flush(CachingKeyValueStore.java:111)
> at
> org.apache.kafka.streams.state.internals.CachingKeyValueStore.close(CachingKeyValueStore.java:117)
> at
> org.apache.kafka.streams.processor.internals.ProcessorStateManager.close(ProcessorStateManager.java:340)
> ... 7 more



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