Acquire semaphore gives error Code = 0

Question

I have incorporated a semaphore into our software.  The semaphore protection works fine for a little while then gives a mysterious error code = 0.  From that point on, no semaphore operations will work correctly.  Has anyone ever seen this error?  Any clue what it might mean.  There is no message included with the error.
During Debugging I incorporated a mechanism to destroy that semaphore and get a new one.  I found that I can create a new semaphore but when the new semaphore is used, the reference is invalid.  I am using unique named semaphores.  I'm thinking that once the error occurs, the semaphore core is somehow corrupted.
This is occurring in built code running on windows server 2003.
Jim West
Summitek Instruments

Answer 1

I'm not following the reasoning that there is a race condition. It seems to me that if the semaphore works as advertised... meaning that the "Test and Set" action is correct.  There can never be a race condition of the kind that multiple processes lock the same semaphore.
In my webserver, there are two pieces to the puzzle.  The server that creates/destroys the semaphore and the processes that acquire/release the semaphore.
The main server, which is always running, creates a named semaphore.  Places that reference in a global.  Let's called it REF.  On shutdown, the semaphore is destroyed.
When running, a user requests a web page which then spawns off another handler process using a VI template (VIT).  Within this vi instance, the REF is used to Acquire the semaphore, do the protected action, and release the semaphore.  This will happen hundreds of times with no error.  Then, at some point an acquire is called and the acquire semaphore times out.  You can be sure that I have instrumented the code in such a way to tell me if a release failed or some other error.
One possibility is that the VIT instance spontaneously exits after the semaphore is acquired.  I don't believe that this is happening but there would not be any way to 'log' that behaviour.
It is possible that multiple VITs will attempt to acquire the semaphore using REF.  But that is why I am using the semaphore, to stack up the acquires in a methodology similar to stacking on non-reentrant vis.
Jim West