Detecting the number of processors

Question

How do you detect the number of physical processors/cores in .net?

Answer 1

While Environment.ProcessorCount will indeed get you the number of virtual processors in the system, that may not be the number of processors available to your process. I whipped up a quick little static class/property to get exactly that:

using System;
using System.Diagnostics;

/// 

/// Provides a single property which gets the number of processor threads
/// available to the currently executing process.
/// 
internal static class ProcessInfo
{
    /// 

    /// Gets the number of processors.
    /// 
    /// The number of processors.
    internal static uint NumberOfProcessorThreads
    {
        get
        {
            uint processAffinityMask;

            using (var currentProcess = Process.GetCurrentProcess())
            {
                processAffinityMask = (uint)currentProcess.ProcessorAffinity;
            }

            const uint BitsPerByte = 8;
            var loop = BitsPerByte * sizeof(uint);
            uint result = 0;

            while (--loop > 0)
            {
                result += processAffinityMask & 1;
                processAffinityMask >>= 1;
            }

            return (result == 0) ? 1 : result;
        }
    }
}