[jira] [Commented] (NIFI-7438) Controller Service UI hangs since controller service doesn't handle reconnections properly

["Christian Danner (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-7438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17123668#comment-17123668 ] 

Christian Danner commented on NIFI-7438:
----------------------------------------

Thanks [~mattyb149], it seems it solved our issue.
We didn't consider a query check but a "show databases" to query metastore is good enough. 
We have applied it to all Non-HA Databases and DEV Environments.

The generall problem I described that we had for all controller services seems to be gone too. 
For instance we had the AzureStorageCredential Controller and Lookup Service that had also multiple entries and doesn't offer such functionality. Nevertheless since we have the query check in place, all controller services seem to work just fine.

> Controller Service UI hangs since controller service doesn't handle reconnections properly
> ------------------------------------------------------------------------------------------
>
>                 Key: NIFI-7438
>                 URL: https://issues.apache.org/jira/browse/NIFI-7438
>             Project: Apache NiFi
>          Issue Type: Bug
>          Components: Configuration, Core Framework
>    Affects Versions: 1.11.1, 1.11.2, 1.11.3, 1.11.4
>         Environment: RHEL 7.6
> NiFi on Docker
>            Reporter: Christian Danner
>            Priority: Major
>         Attachments: image-2020-05-11-13-38-30-457.png
>
>
> We encounter Problems in showing and managing Controller Services on NiFi Servers that run longer than connected systems we use to connect via Controller Services. Viewing such Controller Services takes about 1 minute to open the view and then shows multiple instances of it (see screenshot).
> e.g. A "DBCPConnectionPool 1.11.4" shows multiple "Supported Controller Services" all the "DBCPService 1.11.4 from org.apache.nifi - nifi-standard-services-api-nar" (19 occurances) as well as shows multiple Groups of "Processors" {color:#172b4d}(19 occurances){color} with the same instances (9 processor instances).
>  
> In this specific case we have a connection to a database server that is shutdown during the night (DEV environment). NiFi Server continues to run while database is not reachable.
>  We suspect that when the database comes available again, it will load the controller service completely while not unloading old sessions. Disabling and re-enabling the controller service doesn't solve the issue, only a complete NiFI Server restart fixes this issue.
> All related processors also fail to execute defined "ExecuteSQL" Processors until we restarted the Controller Services at least. We get a "SocketException" since it tries to make an attempt on the old connection which is not active anymore. For us it is important to have a "Infinite Connection" while interacting with the database ({color:#262626}Max Connection Lifetime{color:#003000} = -1).{color}{color}



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