> On May 13, 2015, 5:14 p.m., Jay Kreps wrote: > > clients/src/main/java/org/apache/kafka/common/metrics/stats/Rate.java, line > > 62 > > <https://reviews.apache.org/r/34170/diff/1/?file=958215#file958215line62> > > > > Is this actually right? I agree you'll get discontinuities as the > > measured time shrinks to zero but why is giving back 0 the right answer? In > > the case you guys were testing 0 was safe, but imagine a case where the > > monitoring was checking that the value didn't fall below some threshold. > > Dong Lin wrote: > The question is, when Rate.measure() is called right after > Rate.record(n), what should be the return value? I think there are two > possibilities: 0 and n/config.timeWindowMs(). I didn't find any use case > where these two values make a difference. > > Which value do you think is the best? > > Thank you.
I think returning 0 is reasonable if no time has elapsed (technically). As an alternate solution, what if we assumed that "elapsed" is always 1 (at least). For example: double elapsed = convert(now - stat.oldest(now).lastWindowMs) + 1 In case of seconds, this basically means that you assume the current second is always complete. This is only a problem (for a couple of seconds) when all previous samples have zero activity or when the server is just starting up. - Aditya ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/34170/#review83629 ----------------------------------------------------------- On May 13, 2015, 10:32 p.m., Dong Lin wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/34170/ > ----------------------------------------------------------- > > (Updated May 13, 2015, 10:32 p.m.) > > > Review request for kafka. > > > Bugs: KAFKA-2191 > https://issues.apache.org/jira/browse/KAFKA-2191 > > > Repository: kafka > > > Description > ------- > > KAFKA-2191; Measured rate should not be infinite > > > Diffs > ----- > > clients/src/main/java/org/apache/kafka/common/metrics/stats/Rate.java > 98429da34418f7f1deba1b5e44e2e6025212edb3 > > clients/src/main/java/org/apache/kafka/common/metrics/stats/SampledStat.java > b341b7daaa10204906d78b812fb05fd27bc69373 > > Diff: https://reviews.apache.org/r/34170/diff/ > > > Testing > ------- > > > Thanks, > > Dong Lin > >
