PATTERN Cited by 1 source
Adaptive rate control¶
A pattern for background work (migrations, compaction, replication) that must coexist with latency-sensitive foreground traffic on the same cluster. The controller dynamically adjusts throughput based on real-time signals (rejections, backpressure, latency) rather than using fixed rate limits.
Variants in AOSC¶
| Controller | Strategy | Use case |
|---|---|---|
| Fixed | Static batch size + concurrency | Offline migrations where max speed is desired |
| Adaptive batch (default) | AIMD on batch size; reacts to backpressure/admission-control rejections | Safe default for live clusters |
| Adaptive | Gradient2 tuning of both batch size and concurrency | Aggressive but cluster-aware; maximize throughput within headroom |
Design Principles¶
- Start slow, converge to capacity. Additive increase ensures gradual ramp-up; multiplicative decrease (AIMD) ensures fast back-off on overload.
- React to system signals, not wall-clock estimates. Admission-control rejections and HTTP 429s/503s are direct evidence of overload.
- Separate control per phase. Backfill (bulk, sequential) and replay (streaming, incremental) may need different rate profiles.
Seen In¶
- systems/opensearch-aosc — pluggable rate controllers for backfill and replay phases
- sources/2026-07-24-atlassian-online-index-migration-and-shard-scaling-in-opensearch-with-aosc
(Source: sources/2026-07-24-atlassian-online-index-migration-and-shard-scaling-in-opensearch-with-aosc)