kafka-jira mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Andy Bryant (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (KAFKA-6378) NullPointerException on KStream-GlobalKTable leftJoin when KeyValueMapper returns null
Date Wed, 10 Jan 2018 23:54:04 GMT

    [ https://issues.apache.org/jira/browse/KAFKA-6378?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16321374#comment-16321374
] 

Andy Bryant commented on KAFKA-6378:
------------------------------------

A sentinel value is ok where only a subset of the available values for a type are valid, but
it does seem messy to have to convert {{null}} values to the sentinel before the join then
back to {{null}} again in the merge function afterwards.

Also it doesn't cater for the case where you can't pick a sentinel because all values of a
type are valid.

Since as Matthias pointed out {{null}} can never be a valid key explicitly calling it out
as indicating no match in the docs and updated the code so it doesn't crash (a two line change
by the looks) seems like a nice clean approach to me.


> NullPointerException on KStream-GlobalKTable leftJoin when KeyValueMapper returns null
> --------------------------------------------------------------------------------------
>
>                 Key: KAFKA-6378
>                 URL: https://issues.apache.org/jira/browse/KAFKA-6378
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 1.0.0
>            Reporter: Andy Bryant
>
> On a Stream->GlobalKTable leftJoin if the KeyValueMapper returns null, the stream
fails with a NullPointerException (see stacktrace below). On Kafka 0.11.0.0 the stream processes
this successfully, calling the ValueJoiner with the table value set to null.
> The use-case for this is joining a stream to a table containing reference data where
the stream foreign key may be null. There is no straight-forward workaround in this case with
Kafka 1.0.0 without having to resort to either generating a key that will never match or branching
the stream for records that don't have the foreign key.
> Exception in thread "workshop-simple-example-client-StreamThread-1" java.lang.NullPointerException
> 	at java.base/java.util.Objects.requireNonNull(Objects.java:221)
> 	at org.apache.kafka.streams.state.internals.CachingKeyValueStore.get(CachingKeyValueStore.java:136)
> 	at org.apache.kafka.streams.state.internals.CachingKeyValueStore.get(CachingKeyValueStore.java:35)
> 	at org.apache.kafka.streams.state.internals.InnerMeteredKeyValueStore.get(InnerMeteredKeyValueStore.java:184)
> 	at org.apache.kafka.streams.state.internals.MeteredKeyValueBytesStore.get(MeteredKeyValueBytesStore.java:116)
> 	at org.apache.kafka.streams.kstream.internals.KTableSourceValueGetterSupplier$KTableSourceValueGetter.get(KTableSourceValueGetterSupplier.java:49)
> 	at org.apache.kafka.streams.kstream.internals.KStreamKTableJoinProcessor.process(KStreamKTableJoinProcessor.java:56)
> 	at org.apache.kafka.streams.processor.internals.ProcessorNode$1.run(ProcessorNode.java:46)
> 	at org.apache.kafka.streams.processor.internals.StreamsMetricsImpl.measureLatencyNs(StreamsMetricsImpl.java:208)
> 	at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:124)
> 	at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:85)
> 	at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:80)
> 	at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:216)
> 	at org.apache.kafka.streams.processor.internals.AssignedTasks.process(AssignedTasks.java:403)
> 	at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:317)
> 	at org.apache.kafka.streams.processor.internals.StreamThread.processAndMaybeCommit(StreamThread.java:942)
> 	at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:822)
> 	at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:774)
> 	at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:744)



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)

Mime
View raw message