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Posted to issues@flink.apache.org by "Seth Wiesman (Jira)" <ji...@apache.org> on 2021/10/06 23:24:00 UTC

[jira] [Created] (FLINK-24464) Metrics sometimes report negative backlog

Seth Wiesman created FLINK-24464:
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             Summary: Metrics sometimes report negative backlog
                 Key: FLINK-24464
                 URL: https://issues.apache.org/jira/browse/FLINK-24464
             Project: Flink
          Issue Type: Improvement
          Components: Stateful Functions
            Reporter: Seth Wiesman


As report [here| [https://stackoverflow.com/questions/69441309/negative-backlog-in-apache-flink-stateful-functions]] the backlog metric sometimes reports a negative value. This is because the current count is stored in an in-memory variable, while the value used to decrement the count as the backlog clears is stored in Flink state. In the case of a job restart, the in-memory variable is reset to zero (it is a new instance) while the numbers in state are retained. 

 

A negative backlog is non-sensical, confusing, and should be prevented. 

 



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