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    <p>In general yes this will work. However the devil is in the details.</p> <p>Firstly you want to close the mutex in a <code>finally</code> block. Otherwise your process could abruptly terminate and leave it in a signaled state, like an exception. That would make it so that future process instances would not be able to start up. </p> <p>Unfortunately though, even with a <code>finally</code> block you must deal with the potential that a process will be terminated without freeing up the mutex. This can happen for instance if a user kills the process through TaskManager. There is a race condition in your code that would allow for a second process to get an <code>AbandonedMutexException</code> in the <code>WaitOne</code> call. You'll need a recovery strategy for this. </p> <p>I encourage you to read up on <a href="http://msdn.microsoft.com/en-us/library/system.threading.mutex.aspx" rel="noreferrer">the details of the Mutex class</a>. Using it is not always simple.</p> <hr> <p>Expanding upon the race condition possibility:</p> <p>The following sequence of events can occur which would cause a second instance of the application to throw:</p> <ol> <li>Normal process startup.</li> <li>Second process starts up and aquires a handle to the mutex but is switched out before the <code>WaitOne</code> call.</li> <li>Process #1 is abruptly terminated. The mutex is not destroyed because process #2 has a handle. It is instead set to an abandoned state.</li> <li>The second process starts running again and gets an <code>AbanonedMutexException</code>.</li> </ol>
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    1. POIs using a Mutex to prevent multiple instances of the same program from running safe?
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    1. POIs using a Mutex to prevent multiple instances of the same program from running safe?
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    1. COIf his code is the only one creating the mutex, it will be destroyed when the process terminates, hence the create + waitOne will succeed.
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    2. CO@Michael, if the mutex is not explicitly released it will be put into an abandoned state
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    3. CO@Michael: No, it will be set as abandoned.
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