HI Zaiming, I think the problem is not that commit requests aren't considered as effective as heartbeats (they are), but that you can't rejoin the group using only commits/heartbeats. Every time the group rebalances, all members must rejoin the group by sending a JoinGroup request. Once a rebalance has begun (e.g. because a new consumer has been started), then each member must send the JoinGroup before expiration of the session timeout. If not, then they will be kicked out of the group even if they are still sending heartbeats. Does that make sense?
-Jason On Wed, Mar 23, 2016 at 10:03 AM, Zaiming Shi <zmst...@gmail.com> wrote: > Hi there! > > We have noticed that when committing requests are sent intensively, we > receive IllegalGenerationId. > Here is the settings we had problem with: session-timeout: 30 sec, > heartbeat-rate: 3 sec. > Problem resolved by increasing the session timeout to 180 sec. > > So I suppose, due to whatever reason (either the client didn't send > heartbeat, or the broker didn't process the heartbeats in time), the > session was considered dead in group coordinator. > > My question is: why commit requests can't be taken as an indicator of > member being alive? hence not to kill the session. > > Regards > -Zaiming >
