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https://issues.apache.org/jira/browse/NIFI-6068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16775144#comment-16775144
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Mark Payne commented on NIFI-6068:
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Thanks for reporting this [~devriesb]. I think your suggestion makes sense. I
would probably limit it to something like 1,000 or 10K FlowFiles rather than
100K. 10K is the number of FlowFiles in a single swap file, when swapping is
active, so using 100,000 could potentially hold that thread for quite a long
time as well. It is interesting that LocalPort does not loop at all, only
funnels. It probably makes sense to give them both the same logic, since their
intent is really to just move FlowFiles from an incoming queue to an outgoing
queue.
> StandardFunnel looping excessively
> ----------------------------------
>
> Key: NIFI-6068
> URL: https://issues.apache.org/jira/browse/NIFI-6068
> Project: Apache NiFi
> Issue Type: Bug
> Components: Core Framework
> Affects Versions: 1.9.0
> Reporter: Brandon DeVries
> Priority: Major
>
> The StandardFunnel, when triggered, reads up to 100 FlowFiles at a time and
> writes them to the outgoing relationship. It does this inside of a loop,
> with the only exit conditions being:
> # No FlowFiles read (input queue empty)
> # No Available relationships to transfer to
> It does this using a thread from the timer driven thread pool.
> Unfortunately, this means that a flow can be created such that a constant
> trickle of data will prevent processors from running, as all threads are in
> use by funnels which will never let them go.
> To fix this, I'd suggest adding 2 checks. First, if session.get(100) returns
> fewer than 100 FlowFiles, transfer those files and then return. Essentially,
> while more files may subsequently come in, at that point the queue had been
> emptied.
> Second, put a cap on the number of FlowFiles transferred per call to
> onTrigger. While there may still be files to move downstream, after you've
> transferred 100K or so it might be time to give up the thread.
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