[jboss-jira] [JBoss JIRA] (WFLY-5890) Default mod_cluster load metric cpu (AverageSystemLoadMetric) is not supported on Windows

[Radoslav Husar (JIRA)]

    [ https://issues.jboss.org/browse/WFLY-5890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13143848#comment-13143848 ] 

Radoslav Husar commented on WFLY-5890:
--------------------------------------

I agree, we need a metric that works by default everywhere. 

The other reason for why cpu might not be an ideal metric is that in the typical virtualized deployment, the cpu might be reflecting the virtualized hardware, which can be far from reality to what was actually available to the VM.

Also let me remind that the reason why business metric went away was switch to undertow which no longer has 1 client = 1 thread concept that made this metric easy to use.

> Default mod_cluster load metric cpu (AverageSystemLoadMetric) is not supported on Windows
> -----------------------------------------------------------------------------------------
>
>                 Key: WFLY-5890
>                 URL: https://issues.jboss.org/browse/WFLY-5890
>             Project: WildFly
>          Issue Type: Bug
>          Components: Clustering
>    Affects Versions: 10.0.0.CR5
>            Reporter: Michal Karm Babacek
>            Assignee: Radoslav Husar
>              Labels: ux
>
> h3. Problem
> Wildfly 10's default load metric changed from *busyness* to *cpu*. Although otherwise fine, this change has a one major drawback: It doesn't work on Windows JDKs: MODCLUSTER-234. This fact has been known and acknowledged since 2011.
> {code}
> <subsystem xmlns="urn:jboss:domain:modcluster:2.0">
>     <mod-cluster-config advertise-socket="modcluster" connector="ajp">
>         <dynamic-load-provider>
>             <load-metric type="cpu"/>
>         </dynamic-load-provider>
>     </mod-cluster-config>
> </subsystem>
> {code}
> Instead of a valid Load value, subsystem returns 0 and prints: {{MODCLUSTER000045: AverageSystemLoadMetric is not supported on this system and will be disabled.}}
> h3. Example
> {code}
> C:\Users\Administrator>groovy https://gist.githubusercontent.com/Karm/be36292ae52ded419b46/raw/addd6abff5e0d63ed1ec9bee5f23e7106ea12cac/SystemLoadAverage.goovy
> load: -1.0
> avail. processors: 4
> {code}
> {code}
> mbabacek at localhost:~$ groovy https://gist.githubusercontent.com/Karm/be36292ae52ded419b46/raw/addd6abff5e0d63ed1ec9bee5f23e7106ea12cac/SystemLoadAverage.goovy
> load: 0.67
> avail. processors: 4
> {code}
> h3. Call to action
> IMHO, this is a Major user experience failure, the default should provide meaningful values on all major platforms.



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