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MacOSXFsEventsDiffAwarenessTest is flaky #10776
//src/test/java/com/google/devtools/build/lib/skyframe:SkyframeTests has been failing on CI recently due to MacOSXFsEventsDiffAwarenessTest being flaky. The current theory is that the test fails when the machine is under high load.
When we looked at the test initially, it seemed quite obvious why it would be flaky - it did some changes to the filesystem, waited 200ms and then checked that FSEvents reported them correctly. It's conceivable that this might not be the case under load.
@jmmv kindly fixed the test and added logic to retry up to 60 seconds, however the test is still flaky (although apparently less than before):
This is bad, because it might indicate that our
I'll disable the test for now, but we should look into this.
@jmmv It's very hard to say. We upgraded the production fleet to macOS Catalina on 2020-01-29 (but on testing CI already much earlier, I think since the beta), and the test worked fine until yesterday. I remember seeing the same failure occasionally during a presubmit of my CL in the testing org, but that was a completely unrelated change, then it went away a few days later and I was able to submit it.
Maybe it's a bug in macOS Catalina, but it's not clear what triggers it :|
Alright, I think I know what happens. The test starts by doing:
View view1 = underTest.getCurrentView(watchFsEnabledProvider);
which in turn calls
Trivial to expose this by adding a sleep right before the call to