Is "while (true)" usually used for a permanent thread?

Question

I'm relatively new to coding; most of my "work" has been just simple GUI apps that only function for one thing, so I haven't had to thread much.

Anyway, one thing I'm wondering about threading is if you want to keep a thread alive forever to do whatever job it's doing (processing, waiting for input, whatever), is it normal to format it like so:

while (true) {
    // do stuff
    Thread.Sleep(1000);
}

(or something along those lines)...? Or is this not safe and should it be avoided if possible?

Answer 1

Yep, that's what you do.

But typically it's like:

bool keepRunning = true;

...

while(keepRunning){
}

Because sometimes you may like to have someone/something else to have the ability to stop you.

Answer 2

To elaborate a bit more, if a thread is sleeping, when the OS comes along to activate the thread, it will just check to see if it's still sleeping and if so, then just yield its timeslice.

If you leave out the Sleep and do something like

while (true)
{
    if (workAvailable)
        {
        doWork();       
        }
}

then even if workAvailable is false it will keep spinning until the OS stops it, taking up its entire slice doing nothing. Obviously that's a little more inefficient.

You can get even more complex as needed with mutexes, semaphores and whatnot, as mentioned above, but things get complex quickly with those, so you might want to use them to solve a particular problem.