Weird timing issue with Thread.sleep

[Steven Schveighoffer]

On Wed, 03 Aug 2011 13:14:50 -0400, Andrej Mitrovic  
<andrej.mitrovich at gmail.com> wrote:

> Take a look at this:
>
> import std.stdio;
> import core.thread;
>
> void main()
> {
>     foreach (x; 0 .. 1000)
>     {
>         Thread.sleep(dur!("usecs")(999));
>         writeln(x);
>     }
>
>     foreach (x; 0 .. 1000)
>     {
>         Thread.sleep(dur!("usecs")(1000));
>         writeln(x);
>     }
> }
>
> Compile and run it. The first foreach loop ends in an instant, while
> the second one takes much much longer to finish, which is puzzling
> since I've only increased the sleep while for a single microsecond.
> What's going on?

I can only imagine that the cause is the implementation is using an OS  
function that only supports millisecond sleep resolution.  So essentially  
it's like sleeping for 0 or 1 millisecond.  However, without knowing your  
OS, it's hard to say what's going on.  On my linux install, the timing  
seems equivalent.

-Steve