[jboss-jira] [JBoss JIRA] (DROOLS-2361) Use of System.identityHashCode in org.drools.core.common.DefaultFactHandle

[Mario Fusco (JIRA)]

     [ https://issues.jboss.org/browse/DROOLS-2361?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Mario Fusco resolved DROOLS-2361.
---------------------------------
    Resolution: Won't Do


That performance problem is only related with the client compiler which is in charge only for a limited amount of time and when the method is not "hot" enough. This is in contrast with the definition of "serious workload" because in that case the server compiler should kick in and optimize that call properly.

That said I don't see any reasonable workaround to this problem without polluting our public API and, for the reasons I wrote above, this issue is not relevant enough to justify such change.



> Use of System.identityHashCode in org.drools.core.common.DefaultFactHandle
> --------------------------------------------------------------------------
>
>                 Key: DROOLS-2361
>                 URL: https://issues.jboss.org/browse/DROOLS-2361
>             Project: Drools
>          Issue Type: Enhancement
>          Components: core engine
>    Affects Versions: 7.6.0.Final
>            Reporter: Sidi Mohamed EL AATIFI
>            Assignee: Mario Fusco
>              Labels: performance
>         Attachments: before.png
>
>
> This is a JVM https://bugs.openjdk.java.net/browse/JDK-6378256 bug has been fixed in JDK 9 
> It's not a bug in Drools but will be affected severely if using Drools for serious workloads.
> in my case 40% of CPU usage was to
> _java.lang.System.identityHashCode_ used by org.drools.core.common.DefaultFactHandle#determineIdentityHashCode
> !before.png|thumbnail! 
> UPDATE:
> One possible solution is to introduce new (optional) interface for identityHashCode that can be implemented by user facts and internal facts. 
> and provide identityHashCode backed by native (fast) hashCode  



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