Fixes race condition that caused unneeded user compactions to run#4554
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The following is an example of the problem this change fixes
1. Thread 1: A user compaction is currently running for a tablet
2. Thread 2: Tablet server receives a compaction request RPC from manager and it
checks to see if the compaction is needed for the same tablet. If finds it is needed.
3. Thread 1: completes user compaction, so a compaction is no longer
needed for the tablet
4. Thread 2: Initiates a user compaction of the tablet because its
check in step 2 passed.
This change adds a second check in step 4 above that should prevent this race
condition because the check is done at a point when its known no
concurrent user compaction is running. The original check was left as a
fail fast check, but a comment was added explaining its not sufficient
for correctness.
matthpeterson
approved these changes
May 13, 2024
dlmarion
approved these changes
May 13, 2024
dlmarion
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dlmarion
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Looks good to me. I looked at the existing code and this seems ok.
alerman
approved these changes
May 13, 2024
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The following is an example of the problem this change fixes
This change adds a second check in step 4 above that should prevent this race condition because the check is done at a point when its known no concurrent user compaction is running. The original check was left as a fail fast check, but a comment was added explaining its not sufficient for correctness.