This addresses issue #7699 where FoundationDB filer store had low throughput
(~400-500 obj/s) due to each write operation creating a separate transaction.
Changes:
- Add writeBatcher that collects multiple writes into batched transactions
- New config options: batch_size (default: 100), batch_interval (default: 5ms)
- Batching provides ~5.7x throughput improvement (from ~456 to ~2600 obj/s)
Benchmark results with different batch sizes:
- batch_size=1: ~456 obj/s (baseline, no batching)
- batch_size=10: ~2621 obj/s (5.7x improvement)
- batch_size=16: ~2514 obj/s (5.5x improvement)
- batch_size=100: ~2617 obj/s (5.7x improvement)
- batch_size=1000: ~2593 obj/s (5.7x improvement)
The batch_interval timer (5ms) ensures writes are flushed promptly even
when batch is not full, providing good latency characteristics.
Addressed review feedback:
- Changed wait=false to wait=true in UpdateEntry/DeleteEntry to properly
propagate errors to callers
- Fixed timer reset race condition by stopping and draining before reset
Fixes#7699
c153420022