[KAFKA-14961] DefaultBackgroundThreadTest.testStartupAndTearDown test is flasky

• Type: Test
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.5.0
• Assignee: Manyanda Chitimbo
• Reporter: Manyanda Chitimbo
• Created: 03/May/23 11:39
• Updated: 20/Sep/23 04:09
• Resolved: 26/May/23 13:33

Description

When running the test suite locally I noticed the following error

org.opentest4j.AssertionFailedError: expected: <true> but was: <false>
	at app//org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
	at app//org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
	at app//org.junit.jupiter.api.AssertTrue.failNotTrue(AssertTrue.java:63)
	at app//org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:36)
	at app//org.junit.jupiter.api.AssertTrue.assertTrue(AssertTrue.java:31)
	at app//org.junit.jupiter.api.Assertions.assertTrue(Assertions.java:180)
	at app//org.apache.kafka.clients.consumer.internals.DefaultBackgroundThreadTest.testStartupAndTearDown(DefaultBackgroundThreadTest.java:95) 

which happened only once and I could reproduce it again. 

I further noticed some NPE in debug logs in the form of

 ERROR The background thread failed due to unexpected error (org.apache.kafka.clients.consumer.internals.DefaultBackgroundThread:166)
java.lang.NullPointerException
    at org.apache.kafka.clients.consumer.internals.DefaultBackgroundThread.handlePollResult(DefaultBackgroundThread.java:200)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195)
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
    at java.base/java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1675)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:553)
    at org.apache.kafka.clients.consumer.internals.DefaultBackgroundThread.runOnce(DefaultBackgroundThread.java:187)
    at org.apache.kafka.clients.consumer.internals.DefaultBackgroundThread.run(DefaultBackgroundThread.java:159)
 

which is due to missing stubs.

Issue Links

• links to: GitHub Pull Request #13664