My application needs to time some realtime events down to the
millisecond range. It seems that Thread.Sleep only gives a
10-millisecond resolution. I also believe that DateTime.Now() only
returns the time to the nearest 10-millisecond boundary -- despite the
documentation that indicates DateTime records an instant in time down to
the Tick level. This does not appear to be a problem with
System.Windows.Forms.Timer, as I can produce accurate delays with it.
The following test code snippet demonstrates the Thread.Sleep problem:
Dim I As Integer, Sample(20) As DateTime
For I = 0 To UBound(Sample)
System.Threading.Thread.Sleep(I * 3)
Sample(I) = DateTime.Now()
Next
For I = 1 To UBound(Sample)
Console.WriteLine("Sample({0}) = {1}, Interval = {2} ms", _
I, Format(Sample(I), "hh:mm:ss.fffff"),
Sample(I).Subtract(Sample(I - 1)).TotalMilliseconds)
Next
The output is:
Sample(1) = 11:59:50.34376, Interval = 10.0144 ms
Sample(2) = 11:59:50.35378, Interval = 10.0144 ms
Sample(3) = 11:59:50.36379, Interval = 10.0144 ms
Sample(4) = 11:59:50.38382, Interval = 20.0288 ms
Sample(5) = 11:59:50.40385, Interval = 20.0288 ms
Sample(6) = 11:59:50.42388, Interval = 20.0288 ms
Sample(7) = 11:59:50.45392, Interval = 30.0432 ms
Sample(8) = 11:59:50.48396, Interval = 30.0432 ms
Sample(9) = 11:59:50.51401, Interval = 30.0432 ms
Sample(10) = 11:59:50.54405, Interval = 30.0432 ms
Sample(11) = 11:59:50.58411, Interval = 40.0576 ms
Sample(12) = 11:59:50.62417, Interval = 40.0576 ms
Sample(13) = 11:59:50.66422, Interval = 40.0576 ms
Sample(14) = 11:59:50.71430, Interval = 50.072 ms
Sample(15) = 11:59:50.76437, Interval = 50.072 ms
Sample(16) = 11:59:50.81444, Interval = 50.072 ms
Sample(17) = 11:59:50.87453, Interval = 60.0864 ms
Sample(18) = 11:59:50.93461, Interval = 60.0864 ms
Sample(19) = 11:59:50.99470, Interval = 60.0864 ms
Sample(20) = 11:59:51.05479, Interval = 60.0864 ms
Can anybody shed some light on this problem? Thanks.
Richard J. Kucia
Owner, Kucia Associates
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