[jira] [Updated] (BEAM-12118) QueuingBeamFnDataClient adds polling latency to completing bundle processing

["Kenneth Knowles (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/BEAM-12118?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kenneth Knowles updated BEAM-12118:
-----------------------------------
    Status: Open  (was: Triage Needed)

> QueuingBeamFnDataClient adds polling latency to completing bundle processing
> ----------------------------------------------------------------------------
>
>                 Key: BEAM-12118
>                 URL: https://issues.apache.org/jira/browse/BEAM-12118
>             Project: Beam
>          Issue Type: Bug
>          Components: java-fn-execution
>            Reporter: Sam Whittle
>            Assignee: Sam Whittle
>            Priority: P2
>
> Currently the inboundDataClients are registered with recieve, and they add data to a queue. There is no explicit indication from the clients that they are no longer going to add values to the queue.
> Within QueueingBeamFnDataClient.drainAndBlock the queue is therefore polled and if nothing is present all clients are polled to see if they are complete.
> This design makes for unfortunate tradeoffs on poll timeout:
> - cpu wasted with small timeout
> - additional latency in noticing we have completed with larger timeout
> With the existing InboundDataClient interface, we could have a separate thread call awaitCompletion on all of the clients and then shutdown the queue (adding a poison pill perhaps)
> Or we could modify InboundDataClient interface to allow registering iterest in when the client is done producing elements.  The existing clients all seem based upon futures which allow that.



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