Re: How to allow a specific number of Instances of my app?

"Ralph" <nt_consulting64@xxxxxxxxx> wrote in message
news:GfKdnR6EFKZm69jYnZ2dnUVZ_sidnZ2d@xxxxxxxxxxxxxxx
I doubt that VB implements App.PrevInstance using a Mutex/Semaphore as it
is
so easily fooled. That's why the 'work-around', a Mutex, is often
suggested
as a more reliable mechanism.

The reason App.PrevInstance can be easily fooled is that the user can make a
copy of the EXE, rename it or put it into a different folder and run the EXE
twice. Under the hood, VB6 uses the current EXE fully qualified path as a
mutex/semaphore, so if the user renamed the EXE, a different mutex/semaphore
is created. In this case, App.PrevInstance is fooled, so the solution is to
make a mutex that is not dependant on the file name.

One must also use the "Global\" prefix in certain OS'es(after checking the
version number) to prevent the user from running a second copy of the app in
another terminal server session, or a second session in XP fast user
switching. I think if not specified, it's considered local to the session by
default.



.

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