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From "Pascal Schumacher (JIRA)" <>
Subject [jira] [Closed] (LANG-1229) Performance regression due to cyclic hashCode guard
Date Wed, 08 Jun 2016 20:35:21 GMT


Pascal Schumacher closed LANG-1229.
       Resolution: Fixed
         Assignee: Pascal Schumacher
    Fix Version/s: 3.5

> Performance regression due to cyclic hashCode guard
> ---------------------------------------------------
>                 Key: LANG-1229
>                 URL:
>             Project: Commons Lang
>          Issue Type: Bug
>          Components: lang.builder.*
>    Affects Versions: 3.5
>            Reporter: Philippe Marschall
>            Assignee: Pascal Schumacher
>             Fix For: 3.5
> We observed a severe performance regression in HashCodeBuilder in 3.5 trunk compared
to 3.4 release. We get about 20% of the throughput in 3.5 trunk for common cases compared
to 3.4 release. Previously there was no noticeable overhead of using HashCodeBuilder. Investigating
we found the performance degradation was caused by the fix for LANG-456. It causes the method
to be too large to be inlined and escape analysis to fail (see LANG-1218 for a related discussion).
> We currently do not see a way to keep the 3.4 performance and support cyclic graphs.
The append methods have not supported cycles for so long we feel it's de facto part of the
contract by now. Since neither the JDK nor the Guava hashCode helper methods support cyclic
graphs we don't believe this is an unreasonable assumption. In addition EqualsBuilder#append(Object,Object)
doesn't support cycles.
> If supporting cycles is a requirement we propose the introduction of new #appendRecursive
(or named differently) methods to both HashCodeBuilder and EqualsBuilder that add cycle guards.
If that is an acceptable compromise we would be willing to provide patches.

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