fix flaky test

[m-trieu]

Removed flaky logic around waiting in tests.

Removed thread.sleep and replaced with triggers via CountDownLatch

R: @scwhittle @Abacn

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[scwhittle]

Do you know how to run a test 100x to verify it isn't flaky? I'm not sure if there is a gradle invocation to do that or not. Maybe @Abacn knows

[Abacn]

Do you know how to run a test 100x to verify it isn't flaky? I'm not sure if there is a gradle invocation to do that or not. Maybe @Abacn knows

It's unit test and the command can be this

first in https://github.com/apache/beam/blob/master/runners/google-cloud-dataflow-java/worker/build.gradle add a line

test.outputs.upToDateWhen {false} 

(ref: https://stackoverflow.com/questions/29427020/how-to-run-gradle-test-when-all-tests-are-up-to-date);

then use a script like

for i in `seq 1 100`; do
./gradlew :runners:google-cloud-dataflow-java:worker:test --tests *someSpecificUnitTest*
done

and see the result.

The problem is the tests with racing condition tends to be more flaky on GitHub Action than on local machines. This may be because the GHA runner has different load each time run, which affects timing, but the local machine do not

[m-trieu]

Thanks! I'll run it and circle back

@Abacn is there anyway I can run it in the same environment as GitHub actions? Or simulate the different loads?

[m-trieu]

running this command locally

:runners:google-cloud-dataflow-java:worker:test --tests "org.apache.beam.runners.dataflow.worker.windmill.client.grpc.StreamingEngineClientTest"

[m-trieu]

:runners:google-cloud-dataflow-java:worker:test --tests "org.apache.beam.runners.dataflow.worker.windmill.client.grpc.StreamingEngineClientTest"

was successful @Abacn