[
https://issues.apache.org/jira/browse/KAFKA-6106?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16215564#comment-16215564
]
Matthias J. Sax commented on KAFKA-6106:
----------------------------------------
IMHO, both scenarios (block all processing to speed up restoration as well as
start partial processing asap) are valuable and we should give a user a config
to choose between both behaviors. This would require a KIP.
> Postpone normal processing of tasks within a thread until restoration of all
> tasks have completed
> -------------------------------------------------------------------------------------------------
>
> Key: KAFKA-6106
> URL: https://issues.apache.org/jira/browse/KAFKA-6106
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Affects Versions: 0.11.0.1, 1.0.0
> Reporter: Guozhang Wang
> Assignee: Guozhang Wang
>
> Let's say a stream thread hosts multiple tasks, A and B. At the very
> beginning when A and B are assigned to the thread, the thread state is
> {{TASKS_ASSIGNED}}, and the thread start restoring these two tasks during
> this state using the restore consumer while using normal consumer for
> heartbeating.
> If task A's restoration has completed earlier than task B, then the thread
> will start processing A immediately even when it is still in the
> {{TASKS_ASSIGNED}} phase. But processing task A will slow down restoration of
> task B since it is single-thread. So the thread's transition to {{RUNNING}}
> when all of its assigned tasks have completed restoring and now can be
> processed will be delayed.
> Note that the streams instance's state will only transit to {{RUNNING}} when
> all of its threads have transit to {{RUNNING}}, so the instance's transition
> will also be delayed by this scenario.
> We'd better to not start processing ready tasks immediately, but instead
> focus on restoration during the {{TASKS_ASSIGNED}} state to shorten the
> overall time of the instance's state transition.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
