[jboss-jira] [JBoss JIRA] (JGRP-2043) Improve performance of Message#readHeader

[Bela Ban (JIRA)]

     [ https://issues.jboss.org/browse/JGRP-2043?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban resolved JGRP-2043.
----------------------------
    Resolution: Done


The JMH test showed that average performance of header creation dropped from ~300ns (previous reflection-based approach) to ~25ns with the {{Constructable}} approach. This is almost the same as calling the constructor directly.

> Improve performance of Message#readHeader
> -----------------------------------------
>
>                 Key: JGRP-2043
>                 URL: https://issues.jboss.org/browse/JGRP-2043
>             Project: JGroups
>          Issue Type: Enhancement
>            Reporter: Sanne Grinovero
>            Assignee: Bela Ban
>            Priority: Minor
>             Fix For: 4.0
>
>
> A CPU hot spot highlighed by profiling via JFR:
> {noformat}Stack Trace	Sample Count	Percentage(%)
> java.lang.reflect.Constructor.newInstance(Object[])	71	2.392
>    java.lang.Class.newInstance()	71	2.392
>       org.jgroups.Message.readHeader(DataInput)	71	2.392
> {noformat}
> I'd have expected the reflective constructor to perform well on a recent JVM, but apparently it's not in this case. A theory is that the {{Class}} type being unknown makes this code harder to optimise; needs to be looked into.
> It might be possible to patch the {{ClassConfigurator}} to provide instances of the required {{Header}} type rather than returning the class, and optimise that instead.



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