[jira] [Commented] (NIFI-11388) Backpressure queue settings loosely followed

["Joe Witt (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-11388?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17709030#comment-17709030 ] 

Joe Witt commented on NIFI-11388:
---------------------------------

Hello

This is true and by design.  It was never meant as a hard limit.  The core reason is that we use this to prevent a processor from being scheduled if any possible destination is already full by default but we dont want to prevent it from completing its work once given threads/having a session.

I am pretty sure our documentation also speaks about this.



> Backpressure queue settings loosely followed
> --------------------------------------------
>
>                 Key: NIFI-11388
>                 URL: https://issues.apache.org/jira/browse/NIFI-11388
>             Project: Apache NiFi
>          Issue Type: Improvement
>            Reporter: Nissim Shiman
>            Priority: Major
>
> The backpressure settings on connections between processors are only loosely followed.  More flowfiles can end up on queues than configured via backpressure setting.
> For example, set up flow:
> GenerateFlowFile -> UpdateAttribute -> (some processor)
> where 
> GenerateFlowFile has _Custom Text_ set to be _hello_
> and Run Schedule is set to be _0 min_
> and 
> the connection following UpdateAttribute has _Back Pressure Object Threshold_ set to be _100_
> Start GenerateFlowFile.
> Wait a few moments until outgoing connection fills up.
> Start UpdateAttribute
> OutGoing conection will have more than 100 flowfiles on it
> (I had over 1000 on mine when running these steps) 



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