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From: "Dave Korn" <dave DOT korn AT artimi DOT com>
To: <cygwin AT cygwin DOT com>
Subject: RE: Inter-Process Mutexes
Date: Wed, 6 Sep 2006 11:26:57 +0100
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On 06 September 2006 10:58, Samuel Thibault wrote:

> Hi,
> 
> Drake Baker, le Mon 04 Sep 2006 01:49:25 -0500, a  crit :
>> I have seen conflicting information on the web concerning inter-process
>> mutexes in CYGWIN.  I have seen outright statements that it is not
>> supported, and I have seen statements that ALL mutexes are inter-process by
>> default.  Obviously, only one statement is currently correct.
> 
> Both are true :)
> 
> Windows provides inter-process mutexes (you just need to give a name to
> CreateMutex ; every process that give the same name will get the same
> mutex).  But cygwin doesn't provide a pthread interface for it.  PTW.

  The underlying pthread implementation uses win32 CreateSemaphore, as it happens.  See pthread_mutex::pthread_mutex in thread.cc.  The pthread functions are not supposed to be inter-process, they are within-process only.  As Václav pointed out, the answer is to set CYGWIN=server in the environment and use the SysV IPC functions.


    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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