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https://issues.apache.org/jira/browse/GROOVY-11775?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18038457#comment-18038457
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ASF GitHub Bot commented on GROOVY-11775:
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eric-milles opened a new pull request, #2335:
URL: https://github.com/apache/groovy/pull/2335
`MixinInMetaClass` used `super.equals()` and `super.hashCode()` which
resulted in identity-only differentiation. Implement equals and hashCode in
terms of `mixinClass` and `emc`. I chose to keep the hash code simple; MMC
instances will bucket up according to their mixin class.
> Stateful runtime mixins sometimes do not work properly
> ------------------------------------------------------
>
> Key: GROOVY-11775
> URL: https://issues.apache.org/jira/browse/GROOVY-11775
> Project: Groovy
> Issue Type: Bug
> Affects Versions: 4.0.26
> Reporter: Björn Kautler
> Assignee: Eric Milles
> Priority: Major
>
> I have class {{A}} and class {{B}}.
> I {{mixin}} {{A}} to {{B}} using {{B.mixin(A)}}.
> {{A}} has a property {{X}}.
> Now I have a method {{M}} in a subclass of {{B}} which first calls a method
> {{N}} of {{A}}, then another method {{O}} of {{A}}.
> Both calls happen linearly, both happen on the same thread, yet occasionally
> the call to {{O}} hits a different instance of {{A}} than the call to {{N}}
> and thus {{N}} and {{O}} work on a different instance of the field in {{A}}.
> From a quick look at the code and debug, the problem might maybe be, that the
> {{MixinInMetaClass#managedIdentityConcurrentMap}} holds the {{B}} instances
> that serve as key in soft references. So maybe if the heap gets exhausted
> between calling {{N}} and {{O}}, the map entry is nuked by the garbage
> collector and thus the {{O}} call creates a new {{A}} instance.
> If this is the case (or actually whatever else causes what I see), stateful
> runtime mixins are quite flaky and should not be used unless this is fixed,
> as you cannot rely on the state. Actually, I was not able to knit an MCVE by
> intentionally triggering two OOME between the calls to {{N}} and {{O}}, so my
> suspicion about the cause might not be correct.
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