Re: Semaphores and .NET

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"William Stacey [MVP]" <staceyw@xxxxxxxx> wrote in message
news:%23DoaYNEqFHA.3720@xxxxxxxxxxxxxxxxxxxxxxx
> As I said, he could modify it pretty easy. Instead of monitor, use a
named
> mutex and shared file to hold the count or mem mapped file, etc. Mind
> sharing what deadlock problem there is? I would be happy to fix it. TIA.
>
> --
> William Stacey [MVP]

As stated in the discussion under your article:
(http://www.codeproject.com/csharp/DijkstraCountingSemaphore.asp#xx1185086xx
)

public bool Acquire(int millisecondsTimeout)
{
lock(syncLock)
{
...snip...
Monitor.Wait(syncLock, millisecondsTimeout)
...snip...
}
}
public void Release(int releaseCount)
{
...snip...
lock(syncLock)
{
...snip...
Monitor.PulseAll(syncLock);
...snip...
}
}



To aquire a lock on the semaphore, you need to obtain syncLock (which is
released the moment you leave the function). If there are no slots
available, you block at the Monitor.Wait() call, INSIDE the lock statement.
When a different thread finishes up and tries to release, it attempts to
aquire the exclusive lock on syncLock. Since there is a thread blocking on
Monitor.Wait() inside the lock, this won't release.



.

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