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https://issues.apache.org/jira/browse/HDDS-14768?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated HDDS-14768:
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Labels: pull-request-available (was: )
> Fix lock leak on SnapshotCache cleanup and handle eviction race appropriately
> -----------------------------------------------------------------------------
>
> Key: HDDS-14768
> URL: https://issues.apache.org/jira/browse/HDDS-14768
> Project: Apache Ozone
> Issue Type: Bug
> Components: OM
> Reporter: Saketa Chalamchala
> Assignee: Saketa Chalamchala
> Priority: Major
> Labels: pull-request-available
>
> 1. SnapshotCache cleanup might be unnecessarily strict.
> The cleanup throws an `IllegalStateException` when it finds stale entries in
> `pendingEvictionQueue` for snapshots that have already been removed from
> dbMap (say SnapshotPurge invalidates the entry right before the last thread
> with a reference to the snapshot just closes adding the snapshotID back to
> the evictionQueue).
> It might be better for cleanup to log the stale entry proceed without
> throwing since this is not a correctness bug.
> 2. `invalidate` should also remove the entry from `pendingEvictionQueue` to
> be more consistent with bookkeeping.
> 3. Snapshot close failure during cleanup removes the snapshotID from eviction
> queue and throws an exception. This causes the snapshot to remain in cache
> even is refCount = 0 unless some other thread explicitly invalidates it which
> maybe unlikely. This means `SnapshotCache.lock()` during this time cannot
> cannot hold the write lock because `lock()` expects the cache to be drained.
> Cleanup should be best-effort for all snapshots pending eviction and any
> snapshots close failures should be retried the next time cleanup runs so that
> `lock()` can have a chance at acquiring the lock after the retry.
> 4. Fix write lock leak in SnapshotCache. If the cache drain `cleanup(true)`
> throws an exception writeLock is not released the lock.
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