[jira] [Commented] (NIFI-8207) Counters in the Wait/Notify pattern do not work as expected

["Peter Gyori (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-8207?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17416649#comment-17416649 ] 

Peter Gyori commented on NIFI-8207:
-----------------------------------

Fixing counter behavior in the Wait/Notify pattern turned out to require:
 * first *specifying the requirements* in cases that are not working with the current implementation
 * then *rewriting* the WaitNotifyProtocol *from scratch.*

Creating a correct releasableCount and reducedSignalCount calculation apparently requires a complete redesign of the current implementation. It may not be worth investing such effort into this as there are other patterns already implemented in NiFi for similar use-cases.

> Counters in the Wait/Notify pattern do not work as expected
> -----------------------------------------------------------
>
>                 Key: NIFI-8207
>                 URL: https://issues.apache.org/jira/browse/NIFI-8207
>             Project: Apache NiFi
>          Issue Type: Bug
>          Components: Extensions
>            Reporter: Peter Gyori
>            Assignee: Peter Gyori
>            Priority: Major
>              Labels: Wait/Notify
>
> The counters in the Wait/Notify pattern do not work as expected, the way counters are decremented seems to be wrong.
> A simple example to reproduce the issue:
> Let's use only one cache, identified by Release Signal ID "A".
> 1) Send 2 signals to cache "A", both with counter named "counter_1".
> 2) Also send 1 signal to cache "A" with counter named "counter_2".
> At this state, the cache looks like this:
> counter_1 -> 2
> counter_2 -> 1
> If we send 1 flowfile to the corresponding Wait processor, that looks for "counter_1" in cache "A", after the flowfile passes the Wait processor, the value of "counter_1" gets decremented to 0 instead of 1.
> It can be checked in debug mode. It can also be checked on the UI by sending another flowfile to the Wait processor and checking the value of the counter attributes that get appended to it.
> The problem seems to come from this line in the WaitNotifyProtocol class:
> {color:#000080}final long {color}reducedSignalCount = signalCount % requiredCountForPass;



--
This message was sent by Atlassian Jira
(v8.3.4#803005)