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Posted to dev@mina.apache.org by "David M. Lloyd (JIRA)" <ji...@apache.org> on 2007/12/14 17:20:43 UTC

[jira] Updated: (DIRMINA-497) Thread safety issue: incorrect usage of Collections.synchronizedMap in DefaultIoSessionDataStructureFactory.DefaultIoSessionAttributeMap

     [ https://issues.apache.org/jira/browse/DIRMINA-497?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

David M. Lloyd updated DIRMINA-497:
-----------------------------------

    Attachment: DIRMINA-497-1.patch

A patch that uses regular synchronization instead of Collections.synchronizedMap().

> Thread safety issue: incorrect usage of Collections.synchronizedMap in DefaultIoSessionDataStructureFactory.DefaultIoSessionAttributeMap
> ----------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DIRMINA-497
>                 URL: https://issues.apache.org/jira/browse/DIRMINA-497
>             Project: MINA
>          Issue Type: Bug
>          Components: Core
>            Reporter: David M. Lloyd
>         Attachments: DIRMINA-497-1.patch
>
>
> In trunk, the DefaultIoSessionAttributeMap.setAttributeIfAbsent() synchronizes on the attributes map in order to synchronize access with the other get/setAttribute methods. However, Collections.synchronizedMap does NOT synchronize on the map itself, but rather an internal object!  So, setAttributeIfAbsent() still contains a race condition.
> A good solution for 2.x would be to simply use a ConcurrentMap, which has putIfAbsent().  For 1.0.x, which has to run on JDK 1.4 (correct?), I'd recommend to just drop Collections.synchronizedMap() and synchronize directly on the Map reference itself.

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