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RE: Inter-Process Mutexes
- From: "Dave Korn" <dave dot korn at artimi dot com>
- To: <cygwin at cygwin dot com>
- Date: Wed, 6 Sep 2006 11:26:57 +0100
- Subject: RE: Inter-Process Mutexes
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 VÃclav pointed out, the answer is to set CYGWIN=server in the environment and use the SysV IPC functions.
cheers,
DaveK
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