[BEAM-10515] Failure / flake in MemoryMonitorTest > detectGCThrashing

• Type: Bug
• Status: Resolved
• Priority: P1
• Resolution: Cannot Reproduce
• Fix Version/s: Not applicable
• Component/s: runner-dataflow
• Labels: flake
• Assignee: Kenneth Knowles
• Reporter: Kenneth Knowles
• Created: 16/Jul/20 18:08
• Updated: 24/Jul/20 19:53
• Resolved: 16/Jul/20 18:27

Description

https://ci-beam.apache.org/job/beam_PreCommit_Java_Commit/12409/testReport/junit/org.apache.beam.runners.dataflow.worker.util/MemoryMonitorTest/detectGCThrashing/

java.lang.AssertionError
	at org.junit.Assert.fail(Assert.java:87)
	at org.junit.Assert.assertTrue(Assert.java:42)
	at org.junit.Assert.assertTrue(Assert.java:53)
	at org.apache.beam.runners.dataflow.worker.util.MemoryMonitorTest.detectGCThrashing(MemoryMonitorTest.java:93)

This is a bad assertion, as one must read the code to learn anything.

The code snippet is:

    provider.inGCThrashingState.set(false);
    monitor.waitForThrashingState(false);
    assertTrue(s.tryAcquire(100, TimeUnit.MILLISECONDS));

This is a timeout acquiring a lock in 100 milliseconds.