Fly-Style commented on code in PR #19286:
URL: https://github.com/apache/druid/pull/19286#discussion_r3116050475
##########
indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java:
##########
@@ -513,45 +537,59 @@ public void handle()
dataSource,
list
);
- if (desiredTaskCount > 0) {
- emitter.emit(event.setDimension(
- AUTOSCALER_SKIP_REASON_DIMENSION,
- "There are tasks pending completion"
- )
- .setMetric(AUTOSCALER_REQUIRED_TASKS_METRIC,
desiredTaskCount));
- }
+ emitter.emit(event.setDimension(
+ AUTOSCALER_SKIP_REASON_DIMENSION,
+ "There are tasks pending completion"
+ )
+ .setMetric(AUTOSCALER_REQUIRED_TASKS_METRIC,
desiredTaskCount));
return;
}
}
- if (nowTime - dynamicTriggerLastRunTime <
autoScalerConfig.getMinTriggerScaleActionFrequencyMillis()) {
+
+ // 3) Make sure we are not breaching any scaling cooldown limits.
+ // Scaling operations are disruptive — scale-down in particular can
leave the supervisor
+ // under-resourced while it recovers from lag induced by the scale
event, so callers may
+ // configure a longer cooldown for scale-down than for scale-up.
Both directions are measured against the same
+ // last-scale timestamp so that a rapid up/down oscillation is still
subject to the appropriate cooldown,
+ // regardless of which direction triggered last.
+ final ScaleDirection scaleDirection;
+ final long cooldownMillis;
+
+ if (desiredTaskCount > currentTaskCount) {
+ scaleDirection = ScaleDirection.SCALE_UP;
+ cooldownMillis = autoScalerConfig.getMinScaleUpDelay().getMillis();
+ } else { // desiredTaskCount < currentTaskCount
+ scaleDirection = ScaleDirection.SCALE_DOWN;
+ cooldownMillis =
autoScalerConfig.getMinScaleDownDelay().getMillis();
+ }
Review Comment:
Unfortunately, the invariant with the fallback to
`minTriggerScaleActionFrequencyMillis` is not present.
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