leekeiabstraction opened a new pull request, #28271:
URL: https://github.com/apache/flink/pull/28271
Backport of #28251 to `release-1.20`.
## What is the purpose of the change
Fixes a native memory leak in the RocksDB SST merge `Compactor`.
`ColumnFamilyHandle.getDescriptor()` copies the column family's options across
JNI and returns a fresh native `ColumnFamilyOptions` on every call.
`Compactor.compact()` read `numLevels()` from it but never closed it, so the
native object leaked on every compaction. Because the leaked options retain a
reference to the shared block cache (via `BlockBasedTableFactory` ->
`BlockBasedTableOptions` -> `LRUCache`), the cache's `shared_ptr` is never
released, preventing the block cache from being freed even after all tasks
stop. This causes task manager RSS to grow and eventually OOM.
## Brief change log
- Wrap `cfName.getDescriptor().getOptions()` in a try-with-resources block
in `Compactor.compact()` so the native `ColumnFamilyOptions` is closed after
`numLevels()` is read.
## Verifying this change
The leak and the fix were verified with jemalloc profiling (`jeprof`),
running Flink in session mode and repeatedly starting/stopping jobs to trigger
the compactor while tracking the `rocksdb::BlockFetcher::ReadBlockContents`
call stack that dominates block-cache allocations. The configured block cache
capacity was 833MB.
- **Before the fix:** after jobs were stopped and resubmitted,
`ReadBlockContents` grew to ~1.54GB, far exceeding the 833MB cache capacity;
the jemalloc heap profile reported a total of 2,280,777,636 bytes.
- **After the fix:** the task manager with the highest RSS held ~800MB in
`ReadBlockContents`, consistent with the 833MB capacity; the jemalloc heap
profile reported a total of 1,416,132,765 bytes.
This is a ~37% reduction in native memory usage and eliminates the
cache-capacity overage, confirming the `LRUCache` leak caused by the unclosed
`ColumnFamilyOptions` is resolved. The behavior (output level computation) is
unchanged and is covered by existing tests; only the previously-leaked native
handle is now closed.
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? no
- If yes, how is the feature documented? not applicable
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