[jira] [Updated] (FLINK-8740) Job-level metrics lost during job re-submission in HA mode

["Aljoscha Krettek (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-8740?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Aljoscha Krettek updated FLINK-8740:
------------------------------------
    Priority: Critical  (was: Blocker)

> Job-level metrics lost during job re-submission in HA mode
> ----------------------------------------------------------
>
>                 Key: FLINK-8740
>                 URL: https://issues.apache.org/jira/browse/FLINK-8740
>             Project: Flink
>          Issue Type: Bug
>          Components: JobManager
>    Affects Versions: 1.4.0
>            Reporter: Joshua DeWald
>            Priority: Critical
>             Fix For: 1.5.0
>
>
> When Flink is running in High Availability and a leader re-election occurs to the same job manager, the job is unable to register the job-level metrics due to a name collision. 
> This may occur even if a different Job Manager is elected, but as it is a local JobManagerMetricsGroup which spits out the error, that is unlikely the case.
>  
> *Expected Behavior*
> When a job is forced to re-submit due to Job Manager re-election, job-level metrics should be available in the new instance of the job (uptime, checkpoints size, checkpoint duration, etc)
> *Actual Behavior*
> When job gets re-submitted, it is unable to register job-level metrics due to collision in the JobManagerMetricGroup, which leads to situation where even though job is running the metrics around checkpoints and uptime are not available
> *Steps to reproduce*
>  # Start up Flink in HA mode using ZooKeeper, single node is fine
>  # Submit a job to the cluster
>  # Stop and restart ZooKeeper
>  # In Job Manager logs you will see the following errors:
>  # 
> {noformat}
> 79043 2018-02-19 21:58:15,928 WARN org.apache.flink.metrics.MetricGroup - Name collision: Group already contains a Metric with the name 'totalNumberOfCheckpoints'. Metric will not be reported....
> 79044 2018-02-19 21:58:15,928 WARN org.apache.flink.metrics.MetricGroup - Name collision: Group already contains a Metric with the name 'numberOfInProgressCheckpoints'. Metric will not be reported....
> 79045 2018-02-19 21:58:15,928 WARN org.apache.flink.metrics.MetricGroup - Name collision: Group already contains a Metric with the name 'numberOfCompletedCheckpoints'. Metric will not be reported....{noformat}
> *Proposed Solution*
> I suspect that there may be other related issues than just the metrics, but a code change that seems to fix the issue is that, during recovery, to remove the existing registered Job Metrics:
> {code:java}
> if (isRecovery) {
>    log.info(s"Removing metrics for $jobId, new will be added during recover")
>    jobManagerMetricGroup.removeJob(jobId)
> }{code}
> I'd be happy to submit this in a PR if that is acceptable to open up the discussion, but I am not sure the consequences of not closing the previous JMMG or perhaps simply not re-registering job-level metrics during recovery. Doing this would seem to entail informing lower levels about the recovery.



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