Re: new Date(), System.currentTimeMillis() and system clock accuracy

Daniel Pitts <>
Sat, 05 Jul 2008 17:25:55 -0700
Numeron wrote:

jonbbbb wrote:

Looks like it only handles 10ms on Windows Xp:

Thanks for the speedy reply that was only posted like 10 minutes
ago :)

It seems then that on this machine the problem is unsolvable without
trying to simulate ~1ms in a busy method. Something which is not only
difficult, but really bad programming practice (busy methods are the
devil on many computers). Not cool. I see that the Thread class has a
sleep(millis) method. Is there any way to query how long a thread has
been sleeping (I dont see anything obvious in the api), and if so is
this any more accurate than the system clock?


Thread.sleep() is also constrained by the system clock resolution, as
well as by arbitrary scheduling algorithms. The truth is that
Thread.sleep() gives up control for at *least* n milliseconds.

If you really need more precise timing, you may have to find/write some
JNI code that creates a low-level timer with more resolution than the OS
defaults. This code is likely to be extremely system specific.

I don't think there is any way to do what you want to do in pure Java.

Daniel Pitts' Tech Blog: <>

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