Question

I have a WP7 app that sometimes has to make a long (5-25 sec) processing.

With Mango, when the app is set to Dormant state while it was processing (ex: the user presses the Windows button or locks the screen), when the user comes back, the app crashes.

I tried on the emulator and on my device, same behavior.

If I reproduce it in debug mode on Visual Studio, it doesn’t crash so it’s hard to find what is really happening.

To reproduce it, start a new Windows Phone project, add a button on MainPage.xaml & add an event handler on the click event that executes an infinite loop:

while (true)
{
    System.Threading.Thread.Sleep(100);
}

My question is: What is really happening? Why does it crash? Isn’t fast app switching supposed to just pause the app process and resume it?

EDIT:
Another thing I noticed is that when running the heavy process, the deactivated & activated events do not seem to be raised when I get out/in the app.

Answer 1

Found the answer on the official Windows Phone forum (link). Here it is:

Why it crashes:

From the time the app is deactivated, it has exactly ten seconds to
finish up what it is doing. If the code takes more than ten seconds,
the OS will terminate the app.

Why the deactivated & activated events are not raised when I get out/in the app:

If the process is blocking the UI thread this also blocks the message
dispatch loop so I suspect that this is the reason why your app never
gets a chance to detect and handle the events.