You are right Uwe, Kafka Streams won't leave group no matter dynamic or static membership. If you want to have fast scale down, consider trying static membership and use the admin command `removeMemberFromGroup` when you need to rescale.
Boyang On Thu, Aug 12, 2021 at 4:37 PM Lerh Chuan Low <lerhch...@gmail.com> wrote: > I think you may have stumbled upon this: > https://issues.apache.org/jira/browse/KAFKA-4881. 1 thing that you could > try is using static membership - we have yet to try that though so can't > comment yet on how that might work out. > > On Thu, Aug 12, 2021 at 11:29 PM c...@uweeisele.eu <c...@uweeisele.eu> > wrote: > > > Hello all, > > > > I have a question about the Group Membership lifecycle of Kafka Streams, > > or more specific about when Kafka Streams does leave the consumer group > (in > > case of dynamic membership). > > > > My expectation was, that a call to the method KafkaStreams.close() also > > sends a LeaveGroup request to the coordination (if dynamic membership is > > used). However, its seems that this is not the case (at least in my case > > the request was not send). Only if I explicitly call > > KafkaStreams.removeStreamThread() a LeaveGroup request is sent to the > > coordinator. I used the WordCount example located in > > https://github.com/confluentinc/kafka-streams-examples to evaluate this. > > > > Is this how Kafka Streams is intended to work and if yes, what do you > > recommend to achieve that Kafka Streams leaves the group when shutting > down > > the application? For example, one situation where I don't want to wait > for > > the session timeout is when downscaling an application. > > > > Thanks. > > > > Best Regards, > > Uwe >
