Thanks for the clarification! By default the meterview measures for 1 minute sounds good to me!
+1 for this proposal. Best, Rui On Wed, Sep 6, 2023 at 1:27 PM Gyula Fóra <gyula.f...@gmail.com> wrote: > Thanks for the feedback Rui, > > The rates would be computed using the MeterView class (like for any other > rate metric), just because we report the value per second it doesn't mean > that we measure in a second granularity. > By default the meterview measures for 1 minute and then we calculate the > per second rates, but we can increase the timespan if necessary. > > So I don't think we run into this problem in practice and we can keep the > metric aligned with other time rate metrics like busyTimeMsPerSec etc. > > Cheers, > Gyula > > On Wed, Sep 6, 2023 at 4:55 AM Rui Fan <1996fan...@gmail.com> wrote: > > > Hi Gyula, > > > > +1 for this proposal. The current GC metric is really unfriendly. > > > > I have a concern with your proposed rate metric: the rate is perSecond > > instead of per minute. I'm unsure whether it's suitable for GC metric. > > > > There are two reasons why I suspect perSecond may not be well > > compatible with GC metric: > > > > 1. GCs are usually infrequent and may only occur for a small number > > of time periods within a minute. > > > > Metrics are collected periodically, for example, reported every minute. > > If the result reported by the GC metric is 1s/perSecond, it does not > > mean that the GC of the TM is serious, because there may be no GC > > in the remaining 59s. > > > > On the contrary, the GC metric reports 0s/perSecond, which does not > > mean that the GC of the TM is not serious, and the GC may be very > > serious in the remaining 59s. > > > > 2. Stop-the-world may cause the metric to fail(delay) to report > > > > The TM will stop the world during GC, especially full GC. It means > > the metric cannot be collected or reported during full GC. > > > > So the collected GC metric may never be 1s/perSecond. This metric > > may always be good because the metric will only be reported when > > the GC is not severe. > > > > > > If these concerns make sense, how about updating the GC rate > > at minute level? > > > > We can define the type to Gauge for TimeMsPerMiunte, and updating > > this Gauge every second, it is: > > GC Total.Time of current time - GC total time of one miunte ago. > > > > Best, > > Rui > > > > On Tue, Sep 5, 2023 at 11:05 PM Maximilian Michels <m...@apache.org> > wrote: > > > > > Hi Gyula, > > > > > > +1 The proposed changes make sense and are in line with what is > > > available for other metrics, e.g. number of records processed. > > > > > > -Max > > > > > > On Tue, Sep 5, 2023 at 2:43 PM Gyula Fóra <gyula.f...@gmail.com> > wrote: > > > > > > > > Hi Devs, > > > > > > > > I would like to start a discussion on FLIP-361: Improve GC Metrics > [1]. > > > > > > > > The current Flink GC metrics [2] are not very useful for monitoring > > > > purposes as they require post processing logic that is also dependent > > on > > > > the current runtime environment. > > > > > > > > Problems: > > > > - Total time is not very relevant for long running applications, > only > > > the > > > > rate of change (msPerSec) > > > > - In most cases it's best to simply aggregate the time/count across > > the > > > > different GabrageCollectors, however the specific collectors are > > > dependent > > > > on the current Java runtime > > > > > > > > We propose to improve the current situation by: > > > > - Exposing rate metrics per GarbageCollector > > > > - Exposing aggregated Total time/count/rate metrics > > > > > > > > These new metrics are all derived from the existing ones with minimal > > > > overhead. > > > > > > > > Looking forward to your feedback. > > > > > > > > Cheers, > > > > Gyula > > > > > > > > [1] > > > > > > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-361%3A+Improve+GC+Metrics > > > > [2] > > > > > > > > > > https://nightlies.apache.org/flink/flink-docs-master/docs/ops/metrics/#garbagecollection > > > > > >
