While trying to figure out how to synchronize access between my ScheduledAgent and my main program, I started to investigate how Mutex objects behave.
Normally on Windows, when a Mutex is abandoned, an exception is raised when the Mutex is next acquired. After searching online, I failed to find a description of what happens, particularly if you are holding a Mutex when WP7 decides to kill your process.
Here’s my sample I dropped onto a phone page:
private void OnLoaded(object sender, RoutedEventArgs e)
m = new Mutex(false, "KeepOff");
bgw = new Thread(new ThreadStart(bgw_DoWork));
catch (Exception ex)
Surprisingly, when the thread exits, the Mutex is acquired by the code in the try block, and no exception is raised. I also tested the behavior in my ScheduledAgent, and in that circumstance, the Mutex is also released when the thread is terminated.
Eventually, I did find a reference to the behavior on the phone, but rather than being on WaitOne where I thought it belonged, it’s here: ReleaseMutex Method
Now , I wouldn’t recommend being this sloppy with your Mutex objects, but it looks like for now at least we can assume WP7 will clean up after us.
Peter Torr points out WaitOne might be dangerous, particularly in light of FAS (Fast Application Switching) if it doesn’t include a timeout. I’ll look into that more in another post.