fix(test): add missing unlock in TestPersistLFDiscardStats #1924
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joshua-goldstein
requested review from
akon-dey,
billprovince and
skrdgraph
as code owners
| @@ -531,14 +531,15 @@ func TestPersistLFDiscardStats(t *testing.T) { | |||
| persistedMap[fid] = val | |||
| }) | |||
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| db.vlog.discardStats.Unlock() | |||
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I find it odd that we were acquiring the lock before and not calling unlock. Could you elaborate more on this?
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I also found that very odd. I have no insight into why it was like this. Probably an oversight.
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Seems like db variable is re-assigned and hence calling Lock again without Unlock is not a problem. But this is better.
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@joshua-goldstein could you explain why would there be a deadlock if we don't put sleep altogether? |
mangalaman93
approved these changes
May 4, 2023
joshua-goldstein
changed the title
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Description
TestPersistLFDiscardStatsis currently flaky. E.g., 1, 2, 3 (but this goes back further). To reproduce the problem:From the stack traces in the logs, this looks like a deadlock. The test currently sleeps for 2 seconds to allow for compaction to complete. Assuming compaction does not complete in this time, and we make the call to
db.vlog.discardStats.Lock(), seems to be enough to put us into this deadlock. This is supported experimentally; running the above test command with this change no longer produces the deadlock.There is another sleep in the test to give discardStats a chance to be populated by the newly generated discardStats. We have not seen this issue in CI, but when running this test at very high frequencies (i.e. with
-count=160), we start to see this failure as well. This is mitigated by increasing the sleep.