[jira] [Created] (FLINK-16234) Use LinkedHashSet in StreamGraph.java

[Shang Yuanchun (Jira)]

cpugputpu created FLINK-16234:
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             Summary: Use LinkedHashSet in StreamGraph.java
                 Key: FLINK-16234
                 URL: https://issues.apache.org/jira/browse/FLINK-16234
             Project: Flink
          Issue Type: Bug
            Reporter: cpugputpu


The test in _org.apache.flink.streaming.api.graph.StreamingJobGraphGeneratorTest#testSlotSharingOnAllVerticesInSameSlotSharingGroupByDefaultDisabled_ will cause the following failure:

java.lang.AssertionError: expected:<SlotSharingGroup feca28aff5a3958840bee985ee7de4d3> but was:<SlotSharingGroup 798f7268aeb5fde00858b7c9723d65f1>
at org.apache.flink.streaming.api.graph.StreamingJobGraphGeneratorTest.assertSameSlotSharingGroup(StreamingJobGraphGeneratorTest.java:843)
at org.apache.flink.streaming.api.graph.StreamingJobGraphGeneratorTest.testSlotSharingOnAllVerticesInSameSlotSharingGroupByDefaultDisabled(StreamingJobGraphGeneratorTest.java:814)

I analyze the assertion failure and find that the root cause of it lies in the clear() method in StreamGraph.java, where the variable _sources_ is initialized as a HashSet. Because the iteration order of HashSet is non-deterministic, so the test becomes flaky. 

The fix is to change _HashSet_ to _LinkedHashSet_ and then the failure above is removed. 

 

The stacktrace information is presented as follows for your reference:

java.util.HashSet.iterator(HashSet.java:173)
org.apache.flink.streaming.api.graph.StreamingJobGraphGenerator.setChaining(StreamingJobGraphGenerator.java:251)
org.apache.flink.streaming.api.graph.StreamingJobGraphGenerator.createJobGraph(StreamingJobGraphGenerator.java:166)
org.apache.flink.streaming.api.graph.StreamingJobGraphGenerator.createJobGraph(StreamingJobGraphGenerator.java:104)
org.apache.flink.streaming.api.graph.StreamingJobGraphGenerator.createJobGraph(StreamingJobGraphGenerator.java:100)
org.apache.flink.streaming.api.graph.StreamingJobGraphGeneratorTest.testSlotSharingOnAllVerticesInSameSlotSharingGroupByDefaultDisabled(StreamingJobGraphGeneratorTest.java:803)

 

 



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