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From "Zhenzhong Xu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-7844) Fine Grained Recovery triggers checkpoint timeout failure
Date Mon, 16 Oct 2017 17:46:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-7844?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16206280#comment-16206280

Zhenzhong Xu commented on FLINK-7844:

[~till.rohrmann] We have a use case where Task Managers will be migrated in a rolling fashion
(with minimum interval in-between). Would this approach allow checkpoint to continue as soon
as fine grained recovery is performed?

IMHO, I think the maybe a more appropriate longer-term fix is allowing checkpoint to be committed
individually for each parallel task in an embarrassingly parallel DAG, that way we can truly
achieve no dependencies between the parallel tasks. Thoughts?

> Fine Grained Recovery triggers checkpoint timeout failure
> ---------------------------------------------------------
>                 Key: FLINK-7844
>                 URL: https://issues.apache.org/jira/browse/FLINK-7844
>             Project: Flink
>          Issue Type: Bug
>          Components: State Backends, Checkpointing
>    Affects Versions: 1.4.0, 1.3.2
>            Reporter: Zhenzhong Xu
>            Assignee: Zhenzhong Xu
>         Attachments: screenshot-1.png
> Context: 
> We are using "individual" failover (fine-grained) recovery strategy for our embarrassingly
parallel router use case. The topic has over 2000 partitions, and parallelism is set to ~180
that dispatched to over 20 task managers with around 180 slots.
> Observations:
> We've noticed after one task manager termination, even though the individual recovery
happens correctly, that the workload was re-dispatched to a new available task manager instance.
However, the checkpoint would take 10 mins to eventually timeout, causing all other task managers
not able to commit checkpoints. In a worst-case scenario, if job got restarted for other reasons
(i.e. job manager termination), that would cause more messages to be re-processed/duplicates
compared to the job without fine-grained recovery enabled.
> I am suspecting that uber checkpoint was waiting for a previous checkpoint that initiated
by the old task manager and thus taking a long time to time out.
> Two questions:
> 1. Is there a configuration that controls this checkpoint timeout?
> 2. Is there any reason that when Job Manager realizes that Task Manager is gone and workload
is redispatched, it still need to wait for the checkpoint initiated by the old task manager?
> Checkpoint screenshot in attachments.

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