kv: fix lock ordering in Replica.applySnapshot #60504
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Fixes cockroachdb#60479. ad78116 was a nice improvement that avoided a number of tricky questions about exposing an inconsistent in-memory replica state during a snapshot. However, it appears to have introduced a deadlock due to lock ordering issues (see referenced issue). This commit fixes that issue by locking the Store mutex before the Replica mutex in `Replica.applySnapshot`'s combined critical section. Release note: None
This operation is expensive as it reads from disk multiple times, so it is better to do it under a read lock to avoid disrupting in-flight requests. Release note: None
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Friendly ping on this. |
tbg
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Feb 16, 2021
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Reviewed 1 of 1 files at r1, 7 of 7 files at r2.
Reviewable status:complete! 0 of 0 LGTMs obtained
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Fixes #60479.
ad78116 was a nice improvement that avoided a number of tricky questions about exposing an inconsistent in-memory replica state during a snapshot. However, it appears to have introduced a deadlock due to lock ordering issues (see referenced issue).
This commit fixes that issue by locking the Store mutex before the Replica mutex in
Replica.applySnapshot's combined critical section.Release note: None