C# 中父進(jìn)程終止對(duì)子進(jìn)程終止的影響

在軟件開發(fā)中，處理父進(jìn)程終止時(shí)子進(jìn)程的行為對(duì)于維護(hù)系統(tǒng)穩(wěn)定性至關(guān)重要。當(dāng)多個(gè)子進(jìn)程由父進(jìn)程生成時(shí)，確保它們與父進(jìn)程一起終止非常重要。本文討論了一個(gè)常見問題：使用 System.Diagnostics.Process 類生成的子進(jìn)程即使在主應(yīng)用程序崩潰或通過任務(wù)管理器強(qiáng)制終止時(shí)仍然存在。

作業(yè)對(duì)象：解決父子進(jìn)程層次結(jié)構(gòu)的方案

為了建立子進(jìn)程和父進(jìn)程之間的依賴關(guān)系，可以使用稱為“作業(yè)對(duì)象”的功能。作業(yè)對(duì)象允許在進(jìn)程之間創(chuàng)建層次關(guān)系，其中父作業(yè)對(duì)象的終止也會(huì)導(dǎo)致所有關(guān)聯(lián)的子進(jìn)程終止。

以下代碼演示了如何使用作業(yè)對(duì)象來管理子進(jìn)程依賴關(guān)系：

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

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, uint cbJobObjectInfoLength);

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

    private IntPtr _handle;
    private bool _disposed = false;

    public Job()
    {
        _handle = CreateJobObject(IntPtr.Zero, null);

        JOBOBJECT_BASIC_LIMIT_INFORMATION info = new JOBOBJECT_BASIC_LIMIT_INFORMATION();
        info.LimitFlags = 0x2000; // JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE

        JOBOBJECT_EXTENDED_LIMIT_INFORMATION extendedInfo = new JOBOBJECT_EXTENDED_LIMIT_INFORMATION();
        extendedInfo.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($"無法設(shè)置信息。錯(cuò)誤：{Marshal.GetLastWin32Error()}");

        Marshal.FreeHGlobal(extendedInfoPtr);
    }


    public void AddProcess(Process process)
    {
        if (!AssignProcessToJobObject(_handle, process.Handle))
            throw new Exception($"無法將進(jìn)程分配到作業(yè)對(duì)象。錯(cuò)誤：{Marshal.GetLastWin32Error()}");
    }

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

    protected virtual void Dispose(bool disposing)
    {
        if (_disposed)
            return;

        if (disposing) { }

        Close();
        _disposed = true;
    }

    public void Close()
    {
        if (_handle != IntPtr.Zero)
        {
            Win32.CloseHandle(_handle);
            _handle = IntPtr.Zero;
        }
    }
}

internal static class Win32
{
    [DllImport("kernel32.dll")]
    internal static extern bool CloseHandle(IntPtr hObject);
}

//  必要的結(jié)構(gòu)體定義  (根據(jù)需要補(bǔ)充完整)
enum JobObjectInfoType
{
    ExtendedLimitInformation = 9
}

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

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

[StructLayout(LayoutKind.Sequential)]
internal struct JOBOBJECT_EXTENDED_LIMIT_INFORMATION
{
    public JOBOBJECT_BASIC_LIMIT_INFORMATION BasicLimitInformation;
    public IO_COUNTERS IoInfo;
    public UInt64 ProcessMemoryLimit;
    public UInt64 JobMemoryLimit;
    public UInt64 PeakProcessMemoryUsed;
    public UInt64 PeakJobMemoryUsed;
}

在創(chuàng)建子進(jìn)程后，調(diào)用 AddProcess() 方法將其與已建立的作業(yè)對(duì)象關(guān)聯(lián)。 注意代碼中添加了必要的結(jié)構(gòu)體定義和IDisposable接口的實(shí)現(xiàn)，以及對(duì)資源的正確釋放。

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