[jboss-jira] [JBoss JIRA] (JBJCA-1305) Performance degradation using fair semaphores in heavily contended workloads

[Tom Jenkinson (JIRA)]

    [ https://issues.jboss.org/browse/JBJCA-1305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13138250#comment-13138250 ] 

Tom Jenkinson commented on JBJCA-1305:
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One scenario to consider would be where the same datasource is used for multiple applications. In that case a server under heavy load may see certain applications not making progress in an orderly manner.

> Performance degradation using fair semaphores in heavily contended workloads
> ----------------------------------------------------------------------------
>
>                 Key: JBJCA-1305
>                 URL: https://issues.jboss.org/browse/JBJCA-1305
>             Project: IronJacamar
>          Issue Type: Enhancement
>          Components: Core
>    Affects Versions: WildFly/IronJacamar 1.3.1.Final
>            Reporter: John O'Hara
>            Assignee: Jesper Pedersen
>
> Under heavy contention, a fair semaphore causes performance degradation for threads trying to acquire a permit from the semaphore.  Changing the semaphore to not fair alleviates the performance degradation under heavy contention.



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