2015-10-08 17:19 GMT+02:00 singh.janmejay <[email protected]>: > Did you mean it's not atomic across different metrics? That I think should > be acceptable. A single metric however should get swapped losslessly with > atomic-swap. Either an increment of m should be applied before swap (making > the reading n + m, or after it leaving the accumulator at m and reading at > n). But it should not be lost. > > Am I misunderstanding something?
No, I haven't been precise enough. Usually, we have a set of counters which interdepend. And so you never get them really consistent. Rainer > > -- > Regards, > Janmejay > > PS: Please blame the typos in this mail on my phone's uncivilized soft > keyboard sporting it's not-so-smart-assist technology. > > On Oct 8, 2015 12:33 PM, "Rainer Gerhards" <[email protected]> wrote: > >> 2015-10-08 8:30 GMT+02:00 singh.janmejay <[email protected]>: >> >> Similarly, when one thread goes to output the stats, you need to lock >> > them so that there isn't a lost increment between the time that you read >> > the stat and the time you zero it. >> > >> > No, this involves the same shared (uncontended) lock, except >> > atomic-increment is replaced by atomic-swap with 0. >> > >> >> Just FYI: this is what the current stats system also does. It is also >> where some inaccuracy stems from. Reporting stats is not atomic >> without looks, so a stats counter may be read with value n, then m >> atomic increments happen to it on another thread, then value n is >> being reported (but we are really at n+m) and then the stats counter >> is reset to 0 via an atomic swap. So m updates are lost. IMHO this is >> perfectly acceptable, because otherwise we would lose almost all >> concurrency. >> >> Rainer >> _______________________________________________ >> rsyslog mailing list >> http://lists.adiscon.net/mailman/listinfo/rsyslog >> http://www.rsyslog.com/professional-services/ >> What's up with rsyslog? Follow https://twitter.com/rgerhards >> NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad >> of sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you >> DON'T LIKE THAT. >> > _______________________________________________ > rsyslog mailing list > http://lists.adiscon.net/mailman/listinfo/rsyslog > http://www.rsyslog.com/professional-services/ > What's up with rsyslog? Follow https://twitter.com/rgerhards > NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of > sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T > LIKE THAT. _______________________________________________ rsyslog mailing list http://lists.adiscon.net/mailman/listinfo/rsyslog http://www.rsyslog.com/professional-services/ What's up with rsyslog? Follow https://twitter.com/rgerhards NOTE WELL: This is a PUBLIC mailing list, posts are ARCHIVED by a myriad of sites beyond our control. PLEASE UNSUBSCRIBE and DO NOT POST if you DON'T LIKE THAT.
