The null(zero) values of snapshot are useless for problem analysing, because it is impossible to distinguishing case when there are no events from case when events were dispatched too slow. I do not see any criminal to return 999-th percentile as 3h when histogram configured with 3h max and any latency is 4h.
Best regards, Bukhtoyarov Vladimir email jseco...@mail.ru skype live:fanat-tdd Github: https://github.com/vladimir-bukhtoyarov mobile +79618096798 >Среда, 19 октября 2016, 20:17 +03:00 от Ken Hancock <ken.hanc...@schange.com>: > >I would suggest metrics should return null values instead of false values. > >On Wed, Oct 19, 2016 at 12:21 PM, Владимир Бухтояров < >jseco...@mail.ru.invalid > wrote: > >> >> Hi to all, >> >> I want to fix https://issues.apache.org/jira/browse/CASSANDRA-11063 >> This issue is very ugly for me, because when something works slow then it >> is impossible to capture metrics and save it to monitoring database for >> future investigation. Moreover when one histogram throw exception then many >> metrics-exporters are unable to export metrics for whole MetricRegistry(for >> example MetricsServlet), so when overflow happen in one histogram then I >> have no history data at all. >> >> I propose to implement the following changes: >> 1. The DecayingEstimatedHistogramReservoir and EstimatedHistogram will >> return maximum trackable value instead of Long.MAX_VALUE >> 2. The DecayingEstimatedHistogramReservoir and EstimatedHistogram will >> never throw IllegalStateException, instead, it will use maximum trackable >> value as regular value in percentile and average calculation. >> 3. If anybody want to save old behavior(prefer to crash instead of >> inaccurate reporting) then I can add configuration parameter to save >> previous behavior, moreover I can leave old behavior as default, for my >> needs it will be enough to have some option to avoid crashes. >> >> >> Best regards, >> Bukhtoyarov Vladimir >> email jseco...@mail.ru >> skype live:fanat-tdd >> Github: https://github.com/vladimir-bukhtoyarov >>
