[ https://issues.apache.org/jira/browse/KAFKA-2400?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14660896#comment-14660896 ]
Onur Karaman commented on KAFKA-2400: ------------------------------------- It seems that this change could increase the chances for a consumer to hammer the coordinator with heartbeats now. Previously, the heartbeat interval was tied to the session timeouts, so the coordinator's min and max session timeouts would in a way limit the heartbeat interval. With this patch dissociating the heartbeat interval from session timeout, the coordinator's min and max session timeouts no longer help shield against this. Is this a concern? > Expose heartbeat frequency in new consumer configuration > -------------------------------------------------------- > > Key: KAFKA-2400 > URL: https://issues.apache.org/jira/browse/KAFKA-2400 > Project: Kafka > Issue Type: Sub-task > Reporter: Jason Gustafson > Assignee: Jason Gustafson > Priority: Minor > Fix For: 0.8.3 > > > The consumer coordinator communicates the need to rebalance through responses > to heartbeat requests sent from each member of the consumer group. The > heartbeat frequency therefore controls how long normal rebalances will take. > Currently, the frequency is hard-coded to 3 heartbeats per the configured > session timeout, but it would be nice to expose this setting so that the user > can control the impact from rebalancing. > Since the consumer is currently single-threaded and heartbeats are sent in > poll(), we cannot guarantee that the heartbeats will actually be sent at the > configured frequency. In practice, the user may have to adjust their fetch > size to ensure that poll() is called often enough to get the desired > heartbeat frequency. For most users, the consumption rate is probably fast > enough for this not to matter, but we should make the documentation clear on > this point. In any case, we expect that most users will accept the default > value. -- This message was sent by Atlassian JIRA (v6.3.4#6332)