ProcessingScheduleServiceTest.shouldScheduleOnFixedRate is flaky

[lenaschoenburg]

Summary

Try to answer the following as best as possible

• How often does the test fail? Twice in the last two days
• Does it block your work? No
• Do we suspect that it is a real failure? No

Failures

Outline known failure cases, e.g. a failed assertion and its stacktrace obtained from Jenkins

Example assertion failure

Warning:  Flakes: 
Warning:  io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceTest.shouldScheduleOnFixedRate
Error:    Run 1: ProcessingScheduleServiceTest.shouldScheduleOnFixedRate:291 
dummyTask.execute();
Wanted 5 times:
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceTest$DummyTask.execute(ProcessingScheduleServiceTest.java:383)
But was 145 times:
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)
-> at io.camunda.zeebe.streamprocessor.ProcessingScheduleServiceImpl.lambda$runAtFixedRate$1(ProcessingScheduleServiceImpl.java:65)

Hypotheses

If the test thread is blocked (e.g. by gc), the task can be executed more than 5 times. The verification is too strict.