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

["David M. Lloyd (JIRA)" <ji...@apache.org>]

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

David M. Lloyd closed DIRMINA-497.
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    Resolution: Invalid

Ah yes, you are correct - I looked a while back and noticed that there is a separate "mutex" object in the SynchronizedMap implementation, but I never noticed that it was initialized to the map itself...

Never mind then ;-)

> 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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