C / C++ / MFC

using System.Diagnostics;
using System.Runtime.InteropServices;

namespace CsJobObjectSandbox
{
    internal class Program
    {
        [StructLayout(LayoutKind.Explicit, Size = 8)]
        public struct JobObject_CPU_Rate_Control_Information
        {
            [FieldOffset(0)]
            public uint ControlFlags;

            [FieldOffset(4)]
            public uint CpuRate;
            [FieldOffset(4)]
            public uint Weight;

            [FieldOffset(4)]
            public ushort MinRate;
            [FieldOffset(6)]
            public ushort MaxRate;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct SECURITY_ATTRIBUTES
        {
            public int nLength;
            public IntPtr lpSecurityDescriptor;
            public int bInheritHandle;
        }

        public enum JobObject_Info_Class
        {
            BasicLimitInformation = 2,
            BasicUiRestrictions = 4,
            SecurityLimitInformation = 5,
            EndOfJobItmeInformation = 6,
            AssociateCompletionPortInformation = 7,
            ExtendedLimitInformation = 9,
            GroupInformation = 11,
            NoticiationLimitInformation = 12,
            GroupInformationEx = 14,
            CpuRateControlInformation = 15,
            NetRateControlinformation = 32,
            NotificationLimitInformation = 33,
            LimitViolationInformation2 = 34
        }

        private const uint JOBOBJECT_CPU_RATE_CONTROL_ENABLE = 0x1;
        private const uint JOBOBJECT_CPU_RATE_CONTROL_WEIGHT_BASED = 0x2;
        private const uint JOBOBJECT_CPU_RATE_CONTROL_HARD_CAP = 0x4;
        private const uint JOBOBJECT_CPU_RATE_CONTROL_NOTIFY = 0x8;
        private const uint JOBOBJECT_CPU_RATE_CONTROL_MIN_MAX_RATE = 0x10;

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        static extern IntPtr CreateJobObject([In] ref SECURITY_ATTRIBUTES lpJobAttributes, string lpName);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        static extern bool SetInformationJobObject([In] IntPtr hJob, [In] JobObject_Info_Class jobObjectInfoClass, IntPtr lpJobObjectInfo, int cbJobObjectInfoLength);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        static extern IntPtr AssignProcessToJobObject([In] IntPtr hJob, [In] IntPtr hprocess);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        static extern bool CloseHandle([In] IntPtr hObject);

        
        static void Main(string[] args)
        {
            // Setup security for the job object. In this case, use the defaults;
            SECURITY_ATTRIBUTES attributes = new();
            attributes.nLength = Marshal.SizeOf(attributes);
            attributes.lpSecurityDescriptor = IntPtr.Zero;
            attributes.bInheritHandle = 0;

            // Create a new job object and set it up for limiting CPU usage to 20%.
            IntPtr jobHandle = CreateJobObject(ref attributes, "SandboxJobObject");
            JobObject_CPU_Rate_Control_Information cpuLimitInfo = new()
            {
                ControlFlags = JOBOBJECT_CPU_RATE_CONTROL_ENABLE | JOBOBJECT_CPU_RATE_CONTROL_HARD_CAP,
                CpuRate = 2000
            };

            // Copy the managed structure we used for setup to a block of unmanaged memory.
            int size = Marshal.SizeOf(typeof(JobObject_CPU_Rate_Control_Information));
            IntPtr infoPointer = Marshal.AllocHGlobal(size);
            Marshal.StructureToPtr(cpuLimitInfo, infoPointer, false);

            // Make the call to set the job object to limit CPU usage...
            bool result = SetInformationJobObject(jobHandle, JobObject_Info_Class.CpuRateControlInformation, infoPointer, size);

            // Did it work?
            if (result)
            {
                // Yep! free the unmanaged block of memory. We don't need it anymore.
                Marshal.FreeHGlobal(infoPointer);

                // Grab the process handle for this process.
                IntPtr processHandle = Process.GetCurrentProcess().Handle;

                // Assign this process to use the job object we created.
                _ = AssignProcessToJobObject(jobHandle, processHandle);

                // Go do some work to test if this worked!
                Task task = TestMethodAsync();
                task.Wait();
            }

            // Oh, when we're done with the job object, make sure to free it!
            CloseHandle(jobHandle);
        }

        // Some long running work that uses all avaialable cores.
        static Task TestMethodAsync()
        {
            return Task.Factory.StartNew(() =>
            {
                long y = 0;

                Parallel.For((long)0, (long)10000000000, (x) =>
                {
                    y = x++ * 2;
                });
            });
        }
    }
}