c# 主进程异常退出时子进程自动退出

通过Windows内核提供的JobObject机制实现的跨进程管理方案，能处理主进程正常退出和异常崩溃两种场景。
内核级管理，即使主进程崩溃也会触发子进程终止，无需编写额外清理代码。

帮助类如下

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace JobManagement
{
    #region Helper classes
    /// <summary>
    ///  作业对象，主要用于子进程管理。
    ///  目前版本是只支持作业销毁拥有的子进程退出
    ///  通常可以定义一个全局静态变量使用
    /// </summary>
    public class Job : IDisposable
    {
        [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;
        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()));
        }
        /// <summary>
        /// 进程加入到作业对象中
        /// </summary>
        /// <param name="processHandle">进程句柄</param>
        /// <returns></returns>
        public bool AddProcess(IntPtr processHandle)
        {
            return AssignProcessToJobObject(handle, processHandle);
        }

        /// <summary>
        /// 进程加入到作业对象中
        /// </summary>
        /// <param name="processId">进程Id</param>
        /// <returns></returns>
        public bool AddProcess(int processId)
        {
            return AddProcess(Process.GetProcessById(processId).Handle);
        }
        /// <summary>
        /// 销毁作业对象，手动调用则其拥有的所有进程都会退出
        /// </summary>
        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }
        /// <summary>
        /// 销毁作业对象，手动调用则其拥有的所有进程都会退出
        /// </summary>
        public void Close()
        {
            CloseHandle(handle);
            handle = IntPtr.Zero;
        }
        private void Dispose(bool disposing)
        {
            if (disposed)
                return;
            if (disposing) { }
            Close();
            disposed = true;
        }
    }

    [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
}

调用

     //创建作业对象
     Job _job = new Job();
     //打开记事本程序
     var ps = new Process();
     ps.StartInfo.FileName = "notepad.exe";
     ps.Start();
     //记事本程序进程加入到作业对象
     _job.AddProcess(ps.Handle);

[参考]
C# 实现子进程跟随主进程关闭