[FLINK-10380] Check if key is not nul before assign to group in KeyedStream

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Abandoned
• Affects Version/s: 1.6.0
• Component/s: API / DataStream
• Labels: pull-request-available
• Assignee: Unassigned
• Reporter: Sayat Satybaldiyev
• Created: 20/Sep/18 14:33
• Updated: 27/Apr/21 18:06
• Resolved: 09/Jul/20 12:23

Description

If a user creates a KeyedStream and partition by key which might be null, Flink job throws NullPointerExceptoin at runtime. However, NPE that Flink throws hard to debug and understand as it doesn't refer to place in Flink job.

Suggestion:

Add precondition that checks if the key is not null and throw a descriptive error if it's a null.

 

Job Example:

 

DataStream<String> stream = env.fromCollection(Arrays.asList("aaa", "bbb"))
 .map(x -> (String)null)
 .keyBy(x -> x);

 

 

An error that is thrown:

 

Exception in thread "main" org.apache.flink.runtime.client.JobExecutionException: java.lang.RuntimeException
 at org.apache.flink.runtime.minicluster.MiniCluster.executeJobBlocking(MiniCluster.java:623)
 at org.apache.flink.streaming.api.environment.LocalStreamEnvironment.execute(LocalStreamEnvironment.java:123)
 at org.myorg.quickstart.BuggyKeyedStream.main(BuggyKeyedStream.java:61)
Caused by: java.lang.RuntimeException
 at org.apache.flink.streaming.runtime.io.RecordWriterOutput.pushToRecordWriter(RecordWriterOutput.java:110)
 at org.apache.flink.streaming.runtime.io.RecordWriterOutput.collect(RecordWriterOutput.java:89)16:26:43,110 INFO org.apache.flink.runtime.rpc.akka.AkkaRpcService - Stopped Akka RPC service.
at org.apache.flink.streaming.runtime.io.RecordWriterOutput.collect(RecordWriterOutput.java:45)
 at org.apache.flink.streaming.api.operators.AbstractStreamOperator$CountingOutput.collect(AbstractStreamOperator.java:689)
 at org.apache.flink.streaming.api.operators.AbstractStreamOperator$CountingOutput.collect(AbstractStreamOperator.java:667)
 at org.apache.flink.streaming.api.operators.StreamMap.processElement(StreamMap.java:41)
 at org.apache.flink.streaming.runtime.io.StreamInputProcessor.processInput(StreamInputProcessor.java:202)
 at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask.run(OneInputStreamTask.java:105)
 at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:300)
 at org.apache.flink.runtime.taskmanager.Task.run(Task.java:711)
 at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException
 at org.apache.flink.runtime.state.KeyGroupRangeAssignment.assignToKeyGroup(KeyGroupRangeAssignment.java:59)
 at org.apache.flink.runtime.state.KeyGroupRangeAssignment.assignKeyToParallelOperator(KeyGroupRangeAssignment.java:48)
 at org.apache.flink.streaming.runtime.partitioner.KeyGroupStreamPartitioner.selectChannels(KeyGroupStreamPartitioner.java:63)
 at org.apache.flink.streaming.runtime.partitioner.KeyGroupStreamPartitioner.selectChannels(KeyGroupStreamPartitioner.java:32)
 at org.apache.flink.runtime.io.network.api.writer.RecordWriter.emit(RecordWriter.java:104)
 at org.apache.flink.streaming.runtime.io.StreamRecordWriter.emit(StreamRecordWriter.java:81)
 at org.apache.flink.streaming.runtime.io.RecordWriterOutput.pushToRecordWriter(RecordWriterOutput.java:107)

... 10 more

Issue Links

• links to: GitHub Pull Request #6724