[KAFKA-4300] NamedCache throws an NPE when evict is called and the cache is empty

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.10.1.0
• Fix Version/s: 0.10.1.0
• Component/s: streams
• Assignee: Damian Guy
• Reporter: Damian Guy
• Created: 13/Oct/16 17:00
• Updated: 13/Oct/16 20:18
• Resolved: 13/Oct/16 20:18

Description

evict can be called on a NamedCache even though it is empty. This is due to the shared nature of the outer ThreadCache. Currently if evict is called on an empty NamedCache it will throw a NullPointerException.

From the original email:

I'm joining a bunch of Kafka Topics using Kafka Streams, with the Kafka
0.10.1 release candidate.

It runs ok for a few thousand of messages, and then it dies with the
following exception:

Exception in thread "StreamThread-1" java.lang.NullPointerException
at
org.apache.kafka.streams.state.internals.NamedCache.evict(NamedCache.java:194)
at
org.apache.kafka.streams.state.internals.ThreadCache.maybeEvict(ThreadCache.java:190)
at
org.apache.kafka.streams.state.internals.ThreadCache.put(ThreadCache.java:121)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore.get(CachingKeyValueStore.java:147)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore.get(CachingKeyValueStore.java:134)
at
org.apache.kafka.streams.kstream.internals.KTableReduce$KTableAggregateValueGetter.get(KTableReduce.java:121)
at
org.apache.kafka.streams.kstream.internals.KTableKTableLeftJoin$KTableKTableLeftJoinProcessor.process(KTableKTableLeftJoin.java:77)
at
org.apache.kafka.streams.kstream.internals.KTableKTableLeftJoin$KTableKTableLeftJoinProcessor.process(KTableKTableLeftJoin.java:48)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:82)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:204)
at
org.apache.kafka.streams.kstream.internals.KTableFilter$KTableFilterProcessor.process(KTableFilter.java:83)
at
org.apache.kafka.streams.kstream.internals.KTableFilter$KTableFilterProcessor.process(KTableFilter.java:73)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:82)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:204)
at
org.apache.kafka.streams.kstream.internals.KTableFilter$KTableFilterProcessor.process(KTableFilter.java:83)
at
org.apache.kafka.streams.kstream.internals.KTableFilter$KTableFilterProcessor.process(KTableFilter.java:73)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:82)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:204)
at
org.apache.kafka.streams.kstream.internals.KTableKTableJoinMerger$KTableKTableJoinMergeProcessor.process(KTableKTableJoinMerger.java:52)
at
org.apache.kafka.streams.kstream.internals.KTableKTableJoinMerger$KTableKTableJoinMergeProcessor.process(KTableKTableJoinMerger.java:49)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:82)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:204)
at
org.apache.kafka.streams.kstream.internals.KTableKTableRightJoin$KTableKTableRightJoinProcessor.process(KTableKTableRightJoin.java:83)
at
org.apache.kafka.streams.kstream.internals.KTableKTableRightJoin$KTableKTableRightJoinProcessor.process(KTableKTableRightJoin.java:49)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:82)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:204)
at
org.apache.kafka.streams.kstream.internals.ForwardingCacheFlushListener.apply(ForwardingCacheFlushListener.java:35)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore.maybeForward(CachingKeyValueStore.java:97)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore.access$000(CachingKeyValueStore.java:34)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore$1.apply(CachingKeyValueStore.java:84)
at
org.apache.kafka.streams.state.internals.NamedCache.flush(NamedCache.java:117)
at
org.apache.kafka.streams.state.internals.NamedCache.evict(NamedCache.java:196)
at
org.apache.kafka.streams.state.internals.ThreadCache.maybeEvict(ThreadCache.java:190)
at
org.apache.kafka.streams.state.internals.ThreadCache.put(ThreadCache.java:121)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore.put(CachingKeyValueStore.java:187)
at
org.apache.kafka.streams.state.internals.CachingKeyValueStore.put(CachingKeyValueStore.java:182)
at
org.apache.kafka.streams.kstream.internals.KTableReduce$KTableReduceProcessor.process(KTableReduce.java:92)
at
org.apache.kafka.streams.kstream.internals.KTableReduce$KTableReduceProcessor.process(KTableReduce.java:52)
at
org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:82)
at
org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:204)
at
org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:66)
at
org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:177)
at
org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:427)
at
org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:235)

Issue Links

• links to: GitHub Pull Request #2024