Question

I often use this code in winforms applications to wait for events, without using threads.

while(checkSomething()){
    Application.DoEvents();
}

The program and pc is still responsive while the loop run, however if I look cpu usage in task managart, it usage is reported as 100% .
Do you know why this happens?

Answer 1

When you add this:

while(checkSomething()){
    Application.DoEvents();
}

You’re basically saying to have the program process windows messages, as fast as possible, without anything stopping it until “checkSomething” returns true.

There are a lot of reasons to avoid DoEvents – that being said, if you really plan to do this, you should try to give up some processing time in your loop:

while(checkSomething()){
    Application.DoEvents();
    Thread.Sleep(10); // Sleep a tiny amount... 
}