CODEWITHSUNDEEP
c#multithreadingmutex
Peter PitLock
Peter PitLock

Reputation: 1873

C# Mutex Timespan explained to newbie

I am completely new to Mutex.

I dont understand what this means:

WaitOne(TimeSpan) Blocks the current thread until the current instance receives a signal, using a TimeSpan to specify the time interval. (Inherited from WaitHandle.)

E.g. if I use:

static void Main() 
{
   using(Mutex mutex = new Mutex(false, appGuid))
   {
      if(!mutex.WaitOne(2000, false))
      {
         MessageBox.Show("Instance already running");
         return;
      }

      GC.Collect();                
      Application.Run(new Form1());
   }
}

does it mean that once the line 

if(!mutex.WaitOne(2000, false))

is fired, it waits 2 seconds before it checks if there is a lock on the thread ?

Upvotes: 1

Views: 2089

Answers (1)

Jurgen Camilleri
Jurgen Camilleri

Reputation: 3589

This means that the current thread will block either until someone calls mutex.ReleaseMutex() or the 2000ms timeout has passed. If the timeout is reached, the operation returns false.

More details on the method call are available in this MSDN link.

So the bottom line is it doesn't matter what value you pass as a timeout, a call to mutex.ReleaseMutex() will immediately release the thread anyway - the timeout is there so that the call does not wait infinitely in case the mutex is never release or released at a period considered late by the application's circumstances.

Upvotes: 3

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