Subj : Re: Boss Told Me You Can't Use Semaphore, But I Have To Do Something like It!
To   : comp.programming.threads
From : David Schwartz
Date : Wed Jul 13 2005 12:32 pm


"Chris Friesen" <cfriesen@nortel.com> wrote in message 
news:42D52478.6050501@nortel.com...

> David Schwartz wrote:

>>     By the way, you can always use a file and protect it with file locks. 
>> Otherwise, you'd need something ugly like a process-shared mutex.

> Maybe I'm missing something:  from the original post this is all between 
> processes already, so why is a process-shared mutex uglier than a 
> process-shared semaphore or a sysV semaphore?

    Semaphores were originally designed to be process-shared and do this in 
a natural way. Mutexes were originally designed to be process-local, and 
have process-shared support hacked on. For example, to create a semaphore, 
you just call the semaphore create function. To create a process-shared 
mutex, you have to allocate shared memory and then put the mutex in it.

    It is not that a process-shared mutex is much worse. It just is worse. 
And perhaps it really is much worse, depending upon the reason he can't use 
a semaphore, which we don't know.

    DS

.