How to Manage Processes and Control Resources Using CreateJobObject and SetInformationJobObject in .NET?

How to Use CreateJobObject and SetInformationJobObject with P/Invoke in .NET

CreateJobObject and SetInformationJobObject are Win32 functions that allow you to manipulate job objects. Job objects are a mechanism for managing groups of processes and controlling their resources. They can be used to create a variety of effects, such as preventing processes from terminating each other or limiting their access to resources.

To use CreateJobObject and SetInformationJobObject with P/Invoke in .NET, you will need to declare the following functions and structures:

[DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
static extern IntPtr CreateJobObject(IntPtr a, string lpName);

[DllImport("kernel32.dll")]
static extern bool SetInformationJobObject(IntPtr hJob, JobObjectInfoType infoType, IntPtr lpJobObjectInfo, UInt32 cbJobObjectInfoLength);

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool AssignProcessToJobObject(IntPtr job, IntPtr process);

[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool CloseHandle(IntPtr hObject);

private IntPtr handle;
private bool disposed;

The CreateJobObject function creates a new job object. The SetInformationJobObject function sets information for a job object. The AssignProcessToJobObject function assigns a process to a job object. The CloseHandle function closes a handle to a job object.

The following code sample shows you how to use these functions to create a job object, set its information, and assign a process to it:

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

namespace JobManagement
{
    public class Job : IDisposable
    {
        public Job()
        {
            handle = CreateJobObject(IntPtr.Zero, null);

            var info = new JOBOBJECT_BASIC_LIMIT_INFORMATION
            {
                LimitFlags = 0x2000
            };

            var extendedInfo = new JOBOBJECT_EXTENDED_LIMIT_INFORMATION
            {
                BasicLimitInformation = info
            };

            int length = Marshal.SizeOf(typeof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION));
            IntPtr extendedInfoPtr = Marshal.AllocHGlobal(length);
            Marshal.StructureToPtr(extendedInfo, extendedInfoPtr, false);

            if (!SetInformationJobObject(handle, JobObjectInfoType.ExtendedLimitInformation, extendedInfoPtr, (uint)length))
                throw new Exception(string.Format("Unable to set information.  Error: {0}", Marshal.GetLastWin32Error()));
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        private void Dispose(bool disposing)
        {
            if (disposed)
                return;

            if (disposing) { }

            Close();
            disposed = true;
        }

        public void Close()
        {
            CloseHandle(handle);
            handle = IntPtr.Zero;
        }

        public bool AddProcess(IntPtr processHandle)
        {
            return AssignProcessToJobObject(handle, processHandle);
        }

        public bool AddProcess(int processId)
        {
            return AddProcess(Process.GetProcessById(processId).Handle);
        }

    }

    #region Helper classes

    [StructLayout(LayoutKind.Sequential)]
    struct IO_COUNTERS
    {
        public UInt64 ReadOperationCount;
        public UInt64 WriteOperationCount;
        public UInt64 OtherOperationCount;
        public UInt64 ReadTransferCount;
        public UInt64 WriteTransferCount;
        public UInt64 OtherTransferCount;
    }


    [StructLayout(LayoutKind.Sequential)]
    struct JOBOBJECT_BASIC_LIMIT_INFORMATION
    {
        public Int64 PerProcessUserTimeLimit;
        public Int64 PerJobUserTimeLimit;
        public UInt32 LimitFlags;
        public UIntPtr MinimumWorkingSetSize;
        public UIntPtr MaximumWorkingSetSize;
        public UInt32 ActiveProcessLimit;
        public UIntPtr Affinity;
        public UInt32 PriorityClass;
        public UInt32 SchedulingClass;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct SECURITY_ATTRIBUTES
    {
        public UInt32 nLength;
        public IntPtr lpSecurityDescriptor;
        public Int32 bInheritHandle;
    }

    [StructLayout(LayoutKind.Sequential)]
    struct JOBOBJECT_EXTENDED_LIMIT_INFORMATION
    {
        public JOBOBJECT_BASIC_LIMIT_INFORMATION BasicLimitInformation;
        public IO_COUNTERS IoInfo;
        public UIntPtr ProcessMemoryLimit;
        public UIntPtr JobMemoryLimit;
        public UIntPtr PeakProcessMemoryUsed;
        public UIntPtr PeakJobMemoryUsed;
    }

    public enum JobObjectInfoType
    {
        AssociateCompletionPortInformation = 7,
        BasicLimitInformation = 2,
        BasicUIRestrictions = 4,
        EndOfJobTimeInformation = 6,
        ExtendedLimitInformation = 9,
        SecurityLimitInformation = 5,
        GroupInformation = 11
    }

    #endregion

}

This code sample creates a job object, sets its information to prevent processes from terminating each other, and assigns the current process to the job object.

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