[jira] [Commented] (FLINK-9141) Calling getSideOutput() and split() on one DataStream causes NPE

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-9141?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16463092#comment-16463092 ] 

ASF GitHub Bot commented on FLINK-9141:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/5836#discussion_r185942147
  
    --- Diff: flink-streaming-java/src/test/java/org/apache/flink/streaming/api/datastream/SplitSideOutputTest.java ---
    @@ -0,0 +1,75 @@
    +/*
    + * Licensed to the Apache Software Foundation (ASF) under one
    + * or more contributor license agreements.  See the NOTICE file
    + * distributed with this work for additional information
    + * regarding copyright ownership.  The ASF licenses this file
    + * to you under the Apache License, Version 2.0 (the
    + * "License"); you may not use this file except in compliance
    + * with the License.  You may obtain a copy of the License at
    + *
    + *     http://www.apache.org/licenses/LICENSE-2.0
    + *
    + * Unless required by applicable law or agreed to in writing, software
    + * distributed under the License is distributed on an "AS IS" BASIS,
    + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    + * See the License for the specific language governing permissions and
    + * limitations under the License.
    + */
    +
    +package org.apache.flink.streaming.api.datastream;
    +
    +import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
    +import org.apache.flink.streaming.api.functions.ProcessFunction;
    +import org.apache.flink.util.Collector;
    +import org.apache.flink.util.OutputTag;
    +
    +import org.junit.Test;
    +
    +import java.util.Collections;
    +
    +/**
    + * Tests that verify correct behavior when applying split/getSideOutput operations on one {@link DataStream}.
    + */
    +public class SplitSideOutputTest {
    +
    +	private static final OutputTag<String> outputTag = new OutputTag<String>("outputTag") {};
    +
    +	@Test
    +	public void testSideOutputAfterSelectIsForbidden() {
    +		StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
    +
    +		SingleOutputStreamOperator<String> processInput = env.fromElements("foo")
    +			.process(new DummyProcessFunction());
    +
    +		processInput.split(Collections::singleton);
    +
    +		try {
    +			processInput.getSideOutput(outputTag);
    --- End diff --
    
    add `Assert.fail();` after `processInput.getSideOutput(outputTag);` to ensure that the test fails if no exception is thrown.


> Calling getSideOutput() and split() on one DataStream causes NPE
> ----------------------------------------------------------------
>
>                 Key: FLINK-9141
>                 URL: https://issues.apache.org/jira/browse/FLINK-9141
>             Project: Flink
>          Issue Type: Bug
>          Components: DataStream API
>    Affects Versions: 1.4.0
>            Reporter: Chesnay Schepler
>            Assignee: Chesnay Schepler
>            Priority: Critical
>
> Calling both {{getSideOutput()}} and {{split()}} on one DataStream causes a {{NullPointerException}} to be thrown at runtime.
> As a work-around one can add a no-op map function before the split() call.
> Exception:
> {code}
> Caused by: java.lang.NullPointerException
> 	at org.apache.flink.streaming.api.collector.selector.DirectedOutput.<init>(DirectedOutput.java:79)
> 	at org.apache.flink.streaming.runtime.tasks.OperatorChain.createOutputCollector(OperatorChain.java:326)
> 	at org.apache.flink.streaming.runtime.tasks.OperatorChain.<init>(OperatorChain.java:128)
> 	at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:274)
> 	at org.apache.flink.runtime.taskmanager.Task.run(Task.java:702)
> 	at java.lang.Thread.run(Thread.java:745)
> {code}
> Reproducer:
> {code}
> private static final OutputTag<String> tag = new OutputTag<String>("tag") {};
> public static void main(String[] args) throws Exception {
> 	StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
> 	DataStream<String> dataStream1 = env.fromElements("foo");
> 	SingleOutputStreamOperator<String> processedStream = dataStream1
> 		.process(new ProcessFunction<String, String>() {
> 			@Override
> 			public void processElement(String value, Context ctx, Collector<String> out) {
> 			}
> 		});
> 	processedStream.getSideOutput(tag)
> 		.print();
> 	processedStream
> 		.split(Collections::singletonList)
> 		.select("bar")
> 		.print();
> 	env.execute();
> }
> {code}



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