Thanks Bruno. I'm +1 on the KIP. On Mon, Sep 21, 2020 at 2:49 AM Bruno Cadonna <br...@confluent.io> wrote:
> Hi, > > I would like to restart from zero the voting on KIP-663 that proposes to > add methods to the Kafka Streams client to add and remove stream threads > during execution. > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-663%3A+API+to+Start+and+Shut+Down+Stream+Threads > > Matthias, if you are still +1, please vote again. > > Best, > Bruno > > On 04.09.20 23:12, John Roesler wrote: > > Hi Sophie, > > > > Uh, oh, it's never a good sign when the discussion moves > > into the vote thread :) > > > > I agree with you, it seems like a good touch for > > removeStreamThread() to return the name of the thread that > > got removed, rather than a boolean flag. Maybe the return > > value would be `null` if there is no thread to remove. > > > > If we go that way, I'd suggest that addStreamThread() also > > return the name of the newly created thread, or null if no > > thread can be created right now. > > > > I'm not completely sure if I think that callers of this > > method would know exactly how many threads there are. Sure, > > if a human being is sitting there looking at the metrics or > > logs and decides to call the method, it would work out, but > > I'd expect this kind of method to find its way into > > automated tooling that reacts to things like current system > > load or resource saturation. Those kinds of toolchains often > > are part of a distributed system, and it's probably not that > > easy to guarantee that the thread count they observe is > > fully consistent with the number of threads that are > > actually running. Therefore, an in-situ `int > > numStreamThreads()` method might not be a bad idea. Then > > again, it seems sort of optional. A caller can catch an > > exception or react to a `null` return value just the same > > either way. Having both add/remove methods behave similarly > > is probably more valuable. > > > > Thanks, > > -John > > > > > > On Thu, 2020-09-03 at 12:15 -0700, Sophie Blee-Goldman > > wrote: > >> Hey, sorry for the late reply, I just have one minor suggestion. Since > we > >> don't > >> make any guarantees about which thread gets removed or allow the user to > >> specify, I think we should return either the index or full name of the > >> thread > >> that does get removed by removeThread(). > >> > >> I know you just updated the KIP to return true/false if there > are/aren't any > >> threads to be removed, but I think this would be more appropriate as an > >> exception than as a return type. I think it's reasonable to expect > users to > >> have some sense to how many threads are remaining, and not try to remove > >> a thread when there is none left. To me, that indicates something wrong > >> with the user application code and should be treated as an exceptional > case. > >> I don't think the same code clarify argument applies here as to the > >> addStreamThread() case, as there's no reason for an application to be > >> looping and retrying removeStreamThread() since if that fails, it's > because > >> there are no threads left and thus it will continue to always fail. And > if > >> the > >> user actually wants to shut down all threads, they should just close the > >> whole application rather than call removeStreamThread() in a loop. > >> > >> While I generally think it should be straightforward for users to track > how > >> many stream threads they have running, maybe it would be nice to add > >> a small utility method that does this for them. Something like > >> > >> // Returns the number of currently alive threads > >> boolean runningStreamThreads(); > >> > >> On Thu, Sep 3, 2020 at 7:41 AM Matthias J. Sax <mj...@apache.org> > wrote: > >> > >>> +1 (binding) > >>> > >>> On 9/3/20 6:16 AM, Bruno Cadonna wrote: > >>>> Hi, > >>>> > >>>> I would like to start the voting on KIP-663 that proposes to add > methods > >>>> to the Kafka Streams client to add and remove stream threads during > >>>> execution. > >>>> > >>>> > >>> > https://cwiki.apache.org/confluence/display/KAFKA/KIP-663%3A+API+to+Start+and+Shut+Down+Stream+Threads > >>>> > >>>> Best, > >>>> Bruno > > > -- -- Guozhang
