jtuglu-netflix commented on code in PR #17847:
URL: https://github.com/apache/druid/pull/17847#discussion_r2051631739
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server/src/main/java/org/apache/druid/segment/realtime/SegmentGenerationMetrics.java:
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@@ -105,6 +123,14 @@ public void setSinkCount(long sinkCount)
this.sinkCount.set(sinkCount);
}
+ public void reportMessageGap(final long messageGap)
+ {
+ final long numEvent = this.numMessageGap.incrementAndGet();
+ this.avgMessageGap.getAndUpdate(oldAvg -> oldAvg + ((messageGap - oldAvg)
/ numEvent));
Review Comment:
> Won't it be more efficient to just keep a running sum? Then only calculate
the avg using numEvent when we get the average
In short, given the emission period is variable, we could overflow on the
sum. I figured the simplest solution was taking the performance penalty of
floating pt division. Other offline alternatives seemed a bit more complicated
like sampling/caching the gap values in a ring buffer and moving the avg
calculation to emission-time, etc.
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