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Posted to issues@flink.apache.org by "Till Rohrmann (Jira)" <ji...@apache.org> on 2021/01/05 10:46:00 UTC

[jira] [Closed] (FLINK-19773) Exponential backoff restart strategy

     [ https://issues.apache.org/jira/browse/FLINK-19773?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Till Rohrmann closed FLINK-19773.
---------------------------------
    Fix Version/s: 1.13.0
       Resolution: Fixed

Fixed via 13b7b3e6050ee716d01c9d3d74d08702f93953a8

> Exponential backoff restart strategy
> ------------------------------------
>
>                 Key: FLINK-19773
>                 URL: https://issues.apache.org/jira/browse/FLINK-19773
>             Project: Flink
>          Issue Type: Improvement
>          Components: Runtime / Coordination
>    Affects Versions: 1.11.2
>            Reporter: Levi Ramsey
>            Priority: Minor
>              Labels: pull-request-available, starter
>             Fix For: 1.13.0
>
>
> There are situations where the current restart strategies (fixed-delay and failure-rate) seem to be suboptimal.  For example, in HDFS sinks, a delay between restarts shorter than the lease expiration time in HDFS is going to result in many restart attempts which fail, putting somewhat pointless stress on a cluster.  On the other hand, setting a delay of close to the lease expiration time will mean far more downtime than necessary when the cause of failure is something that works itself out quickly.
>  
> An exponential backoff restart strategy would address this.  For example a backoff strategy where the jobs are contending for a lease on a shared resource that terminates after 1200 seconds of inactivity might have successive delays of 1, 2, 4, 8, 16... 1024 seconds (after which a cumulative delay of more than 1200 seconds has passed).
> While not intrinsically tied to exponential backoff (it's more of an example of variable delay), in the case of many jobs failing due to an infrastructure failure, a thundering herd scenario can be mitigated by adding jitter to the delays, e.g. 0 -> 1 -> 2 -> 3/4/5 -> 5/6/7/8/9/10/11 seconds.  With this jitter, eventually a set of jobs competing to restart will spread out.
> (logging the ticket more to start a discussion and perhaps get context around if this had been considered and rejected, etc.)



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