[jboss-jira] [JBoss JIRA] (WFLY-12601) Eliminate StabilityMonitor usages in clustering subsystem

[Paul Ferraro (Jira)]

    [ https://issues.jboss.org/browse/WFLY-12601?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13790480#comment-13790480 ] 

Paul Ferraro commented on WFLY-12601:
-------------------------------------

[~ropalka] Thanks for the documentation.  I think I understand the crux of the issue now.
There are 2 clustering constructs that currently use StabilityMonitor:
1. ActiveServiceSupplier/PassiveServiceSupplier - essentially, a given metric value needs to be computed within the start() method of the Service that depends on the service that supplies the source of a given metric.
2. ServiceLifecycle - this object is responsible for starting/stopping a given service in response to a change in cluster membership.  There is no attempt to obtain service values, so I believe this class should not be affected by the race conditions you described above.  Do the modifications to this class in the attached PR look OK to you?



> Eliminate StabilityMonitor usages in clustering subsystem
> ---------------------------------------------------------
>
>                 Key: WFLY-12601
>                 URL: https://issues.jboss.org/browse/WFLY-12601
>             Project: WildFly
>          Issue Type: Bug
>          Components: Clustering
>            Reporter: Richard Opalka
>            Assignee: Paul Ferraro
>            Priority: Major
>             Fix For: 19.0.0.Beta1
>
>         Attachments: ServiceSupplier.png
>
>
> Clustering needs to eliminate usages of StabilityMonitor because SM is not reliable.
> It is possible that SM will prematurely inform about achieved stability even if it is not true.
> The reason is SM is not propagated up the dependencies chain and thus it may report
> about achieved stability even in case dependencies chain didn't finish its processing yet
> and 'real' stability wasn't achieved yet.



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