How does Windows know when a program is not responding?
In: 1
Each application has a message queue. Every time something happens (mouse moves, key pressed, window needs to be redrawn, timer expires, etc) windows adds a message to the queue for the application. The application needs to handle the message within a few seconds or Windows will think the application is not responding. Once the application starts processing messages again the error goes away.
The answer directly from Microsoft:
> The operating system detects this state by attaching a timer to pending messages in the message queue. If a message has not been retrieved within 5 seconds, the DWM declares the window to be hung.
https://docs.microsoft.com/en-us/windows/win32/win7appqual/preventing-hangs-in-windows-applications
Latest Answers