Fly-Style opened a new pull request, #19655: URL: https://github.com/apache/druid/pull/19655
## Summary Adds a two-tier "critical lag" fast path to the cost-based Kafka/Kinesis supervisor autoscaler, so an operator-configured SLA threshold can trigger a faster scale-up reaction than the normal cost-minimization loop provides. `CostBasedAutoScalerConfig` gains an optional `criticalLagThreshold` (aggregate/global lag across all partitions, not per-partition). When set, `CostMetrics#getAggregateLag()` is compared against it on every evaluation: - **Tier 1 (≥75% of threshold):** the lag-amplification multiplier used in the cost function's lag-recovery-time term maxes out at `6.0` (vs. the default `0.3`), and the scale-up candidate search bypasses its usual boundary cap (`useTaskCountBoundariesOnScaleUp`), letting the argmin search the full candidate range instead of being capped to +2 steps above the current task count. - **Tier 2 (≥95% of threshold):** cost minimization is skipped entirely — the autoscaler jumps straight to the maximum valid task count, regardless of configured weights or idle ratio. `criticalLagThreshold` is `null` by default, which leaves existing behavior unchanged. The 75%/95% fractions and the 6.0 multiplier are fixed algorithm constants (`WeightedCostFunction.CRITICAL_LAG_TIER1_FRACTION`, `CRITICAL_LAG_TIER2_FRACTION`, `CRITICAL_LAG_AMPLIFICATION_MULTIPLIER`), not separately configurable. This PR has: - [ ] been self-reviewed. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
