[SPARK-48586][SS][3.5] Remove lock acquisition in doMaintenance() by making a deep copy of file mappings in RocksDBFileManager in load() #47130
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…making a deep copy of file mappings in RocksDBFileManager in load() Backports apache#46942 to 3.5 When change log checkpointing is enabled, the lock of the **RocksDB** state store is acquired when uploading the snapshot inside maintenance tasks, which causes lock contention between query processing tasks and state maintenance thread. This PR fixes lock contention issue introduced by apache#45724. The changes include: 1. Removing lock acquisition in `doMaintenance()` 2. Adding a `copyFileMappings()` method to **RocksDBFileManager**, and using this method to deep copy the file manager state, specifically the file mappings `versionToRocksDBFiles` and `localFilesToDfsFiles`, in `load()` 3. Capture the reference to the file mappings in `commit()`. We want to eliminate lock contention to decrease latency of streaming queries so lock acquisition inside maintenance tasks should be avoided. This can introduce race conditions between task and maintenance threads. By making a deep copy of `versionToRocksDBFiles` and `localFilesToDfsFiles` in **RocksDBFileManager**, we can ensure that the file manager state is not updated by task thread when background snapshot uploading tasks attempt to upload a snapshot. No Added unit test cases. No Closes apache#46942 from riyaverm-db/remove-lock-contention-between-maintenance-and-task. Authored-by: Riya Verma <[email protected]> Signed-off-by: Jungtaek Lim <[email protected]>
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Looks like the CI failed with infra side issue. I'll merge once the build without tests is passing, as I would have done that if there wasn't merge conflict. |
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Locally verified the build pass. Thanks! Merging to 3.5! |
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…making a deep copy of file mappings in RocksDBFileManager in load() Backports #46942 to 3.5 ### What changes were proposed in this pull request? When change log checkpointing is enabled, the lock of the **RocksDB** state store is acquired when uploading the snapshot inside maintenance tasks, which causes lock contention between query processing tasks and state maintenance thread. This PR fixes lock contention issue introduced by #45724. The changes include: 1. Removing lock acquisition in `doMaintenance()` 2. Adding a `copyFileMappings()` method to **RocksDBFileManager**, and using this method to deep copy the file manager state, specifically the file mappings `versionToRocksDBFiles` and `localFilesToDfsFiles`, in `load()` 3. Capture the reference to the file mappings in `commit()`. ### Why are the changes needed? We want to eliminate lock contention to decrease latency of streaming queries so lock acquisition inside maintenance tasks should be avoided. This can introduce race conditions between task and maintenance threads. By making a deep copy of `versionToRocksDBFiles` and `localFilesToDfsFiles` in **RocksDBFileManager**, we can ensure that the file manager state is not updated by task thread when background snapshot uploading tasks attempt to upload a snapshot. ### Does this PR introduce _any_ user-facing change? No ### How was this patch tested? Added unit test cases. ### Was this patch authored or co-authored using generative AI tooling? No Closes #47130 from riyaverm-db/remove-lock-contention-between-maintenance-and-task-3.5. Lead-authored-by: Riya Verma <[email protected]> Co-authored-by: Riya Verma <[email protected]> Signed-off-by: Jungtaek Lim <[email protected]>
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Backports #46942 to 3.5
What changes were proposed in this pull request?
When change log checkpointing is enabled, the lock of the RocksDB state store is acquired when uploading the snapshot inside maintenance tasks, which causes lock contention between query processing tasks and state maintenance thread. This PR fixes lock contention issue introduced by #45724.
The changes include:
doMaintenance()copyFileMappings()method to RocksDBFileManager, and using this method to deep copy the file manager state, specifically the file mappingsversionToRocksDBFilesandlocalFilesToDfsFiles, inload()commit().Why are the changes needed?
We want to eliminate lock contention to decrease latency of streaming queries so lock acquisition inside maintenance tasks should be avoided. This can introduce race conditions between task and maintenance threads. By making a deep copy of
versionToRocksDBFilesandlocalFilesToDfsFilesin RocksDBFileManager, we can ensure that the file manager state is not updated by task thread when background snapshot uploading tasks attempt to upload a snapshot.Does this PR introduce any user-facing change?
No
How was this patch tested?
Added unit test cases.
Was this patch authored or co-authored using generative AI tooling?
No