Summary:
This PR adds flush observability for debugging write stalls and flush bottlenecks.
Changes include:
- Add flush reason tickers for physical flush jobs:
- rocksdb.flush.reason.write_buffer_full
- rocksdb.flush.reason.write_buffer_manager
- rocksdb.flush.reason.memtable_max_range_deletions
- Add flush memtable size histograms:
- rocksdb.flush.memtable.memory.bytes
- rocksdb.flush.memtable.total.data.size.bytes
- rocksdb.flush.write_buffer_full.memtable.memory.bytes
- rocksdb.flush.write_buffer_manager.memtable.memory.bytes
- Add FlushReason::kMemtableMaxRangeDeletions and propagate it from memtables when memtable_max_range_deletions triggers a flush.
- Preserve atomic flush as a single request-level reason. For atomic flush, the reason is derived only from CFs that scheduled the flush, not every CF selected into the atomic flush cut.
- Add atomic flush request-level counters:
- rocksdb.atomic_flush.request.reason.write_buffer_full
- rocksdb.atomic_flush.request.reason.write_buffer_manager
- rocksdb.atomic_flush.request.reason.memtable_max_range_deletions
- rocksdb.atomic_flush.request.reason.other
- Keep existing per-CF flush job reason counters unchanged. Under atomic flush, rocksdb.flush.reason.* still counts physical CF flush jobs, while rocksdb.atomic_flush.request.reason.* counts one logical atomic flush request.
- Wire the new flush reason, ticker, and histogram types through Java and JNI bindings.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/14898
Test Plan: CI
Reviewed By: anand1976
Differential Revision: D110214337
Pulled By: xingbowang
fbshipit-source-id: 4a445c4175d2e09ff5edbe66fde81fa00bb9e8da
Xingbo Wang
de7b8e8f7d