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https://issues.apache.org/jira/browse/OWB-1013?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14185337#comment-14185337
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Tobias Stoeckmann commented on OWB-1013:
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The stack looks like a temporary unit to me. It's filled with InjectionPoints
during the creation phase, and cleared afterwards. This happens in a
try-finally-construct "most of the times."
So I considered a ThreadLocal to be a safe and faster version than a total sync.
> Race condition in Instance injection
> ------------------------------------
>
> Key: OWB-1013
> URL: https://issues.apache.org/jira/browse/OWB-1013
> Project: OpenWebBeans
> Issue Type: Bug
> Components: Injection and Lookup
> Affects Versions: 1.2.6
> Reporter: Tobias Stoeckmann
> Assignee: Arne Limburg
> Attachments: instance-race.zip, race.diff
>
>
> OpenWebBeans is prone to flip instances of javax.enterprise.inject.Instance
> in multi-threaded environments.
> It is possible for multiple threads to access InstanceProducer at the same
> time with the same creational context. If that happens, it is not verified
> that these threads get the correct injectionPoint out of the injectionPoints
> stack in the shared CreationalContextImpl.
> Please see attached example source (with comments included). It'll require a
> debugger because it's quite tricky to get the threads into proper timing.
> Start main method of class de.cewe.race.Main. It constructs a simple SE
> container and executes two threads which will trigger the issue.
> Set breakpoints at:
> - de.cewe.race.CDIMain, line 46 (System.out.println)
> - org.apache.webbeans.portable.InstanceProducer, line 65 (getInjectionPoint)
> Wait until threads "RunnableA" and "RunnableB" reached the second breakpoint.
> Then let RunnableA finish. It will trigger a ClassCastException. For your own
> convenience, activate the second breakpoint after first one is reached. It
> reduces debugger noise during startup.
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