[jira] Commented: (DIRMINA-183) Use of "Double-Checked Locking" in ThreadPoolFilter

["Trustin Lee (JIRA)" <ji...@apache.org>]

    [ http://issues.apache.org/jira/browse/DIRMINA-183?page=comments#action_12368972 ] 

Trustin Lee commented on DIRMINA-183:
-------------------------------------

I know this issue.  I did it intentionally because I've never seen any 1.4 VM which produces a problem with DCL.  If you have a concern against this issue, let's just fix it! :)

> Use of "Double-Checked Locking" in ThreadPoolFilter
> ---------------------------------------------------
>
>          Key: DIRMINA-183
>          URL: http://issues.apache.org/jira/browse/DIRMINA-183
>      Project: Directory MINA
>         Type: Bug
>     Reporter: peter royal

>
> In ThreadPoolFilter, the Double-Checked Locking pattern is used:
>         SessionBuffer buf = ( SessionBuffer ) buffers.get( session );
>         if( buf == null )
>         {
>             synchronized( buffers )
>             {
>                 buf = ( SessionBuffer ) buffers.get( session );
>                 if( buf == null )
>                 {
>                     buf = new SessionBuffer( session );
>                     buffers.put( session, buf );
>                 }
>             }
>         }
> .. this could lead to problems on multi-CPU systems (http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html)

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