What is the reason for “while(true) { Thread.Sleep }”?

Question

I sometimes encounter code in the following form:

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

I was wondering if this is considered

Answer 1

If you see code like this...

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

It's most likely using Sleep() as a means of waiting for some event to occur — something like user input/interaction, a change in the file system (such as a file being created or modified in a folder, network or device event, etc. That would suggest using more appropriate tools:

• If the code is waiting for a change in the file system, use a FileSystemWatcher.
• If the code is waiting for a thread or process to complete, or a network event to occur, use the appropriate synchronization primitive and WaitOne(), WaitAny() or WaitAll() as appropriate. If you use an overload with a timeout in a loop, it gives you cancelability as well.

But without knowing the actual context, it's rather hard to say categorically that it's either good, bad or indifferent. If you've got a daemon running that has to poll on a regular basis (say an NTP client), a loop like that would make perfect sense (though the daemon would need some logic to monitor for shutdown events occuring.) And even with something like that, you could replace it with a scheduled task: a different, but not necessarily better, design.