Question

我正在尝试在C＃中实现一组cmdlet，用于创建和管理外部资源，其模式与New-PSSession，Get-PSSession，Remove-PSSession类似。

创建的对象需要在自己的线程上工作，这是可以取消的。

如果我明确Dispose（）每个对象，它工作正常。但是如果我创建了一些对象，然后在没有Disposing的情况下退出Powershell ISE，powershell_ise.exe进程会一直挂起，直到我在任务管理器中将其终止。

我可以通过在Powershell ISE中调用Register-EngineEvent来解决这个问题，但这有点像黑客，因为DLL无法封装自己的清理工作。

我尝试了两种方法：

添加DomainUnload事件处理程序
使用RunspaceInvoke

下面的代码重现了这个问题：

namespace Test
{
    /// <summary>
    /// An class which encapsulates some asynchronous work in a background thread.
    /// Implements IDisposable to cancel the work and cleanup.
    /// </summary>
    public class Thing : IDisposable
    {
        #region private fields

        private readonly Thread _thread;
        private readonly CancellationTokenSource _cancellationTokenSource;
        private bool _disposed;

        #endregion

        #region static fields (for on-exit cleanup)

        private static List<Thing> _allThings = new List<Thing>();
        private static bool _registeredDisposeAll;

        #endregion

        #region public fields

        /// <summary>
        /// Simple counter to see asynchronous work happening
        /// </summary>
        public int Counter { set; get; }

        #endregion

        #region Constructor

        public Thing()
        {
            if (!_registeredDisposeAll)
            {
                // The first time this is called, register an on-exit handler
                // Neither of these work :-(

                // Attempt 1:
                // Register a DomainUnload handler
                AppDomain.CurrentDomain.DomainUnload += (o,a) => DisposeAll();

                // Attempt 2:
                // use RunspaceInvoke to call Register-EngineEvent
                using (var ri = new RunspaceInvoke())
                {
                    string script =
                        "Register-EngineEvent -sourceIdentifier ([System.Management.Automation.PsEngineEvent]::Exiting) -Action { [Test.Thing]::DisposeAll() }";

                    ri.Invoke(script);
                }

                _registeredDisposeAll = true;
            }

            // add this to a static registry of running Things
            _allThings.Add(this);

            // and start some asynchronous work in a thread
            _cancellationTokenSource = new CancellationTokenSource();
            var cancel = _cancellationTokenSource.Token;
            Counter = 0;
            _thread = new Thread(() =>
            {
                while (!cancel.IsCancellationRequested)
                {
                    Thread.Sleep(1000);
                    ++Counter;
                }
            });
            _thread.Start();
        }

        #endregion

        #region IDisposable

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

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

            if (disposing)
            {
                _cancellationTokenSource.Cancel();
                _thread.Join();
                _cancellationTokenSource.Dispose();
            }
            _disposed = true;
        }

        /// <summary>
        /// Callback to destroy any remaining things        
        /// If this doesn't get called, powershell won't exit properly
        /// </summary>
        public static void DisposeAll()
        {
            foreach (var thing in _allThings)
            {
                thing.Dispose();
            }
            _allThings.Clear();
        }

        #endregion

    }

    /// <summary>
    /// A Cmdlet to create a new Thing, similar to New-PSSession or New-PSJob
    /// </summary>
    [Cmdlet(VerbsCommon.New, "Thing")]
    public class NewThing : Cmdlet
    {
        protected override void ProcessRecord()
        {
            WriteObject(new Thing());
        }
    }
}

要查看此操作，请编译为Test.dll，运行powershell_ise.exe，然后运行...

import-module Test.dll

$thing = New-Thing

exit

Powershell ISE窗口将关闭，但由于Thing仍在运行，因此进程仍然存在。这只发生在ISE上，而不是常规的powershell.exe（当它退出时可能更残酷？）。

如果在退出之前执行以下操作，那么它可以正常工作。

Register-EngineEvent -sourceIdentifier ([System.Management.Automation.PsEngineEvent]::Exiting) -Action { [Test.Thing]::DisposeAll() }

如何让DLL注册自己的清理？

我使用的是带有.NET 4.5和Powershell 3.0的Windows 7 x64

Answer 1

您可以将线程设置为后台线程，并且应该允许ISE退出，尽管您的线程将被停止 - 而不是正常关闭IIRC。另一种选择是为你的班级添加终结者。请注意，除非您有终结器，否则您不需要拨打GC.SuppressFinalize(this);，所以也许你确实有一个，但它没有在上面列出？

当Powershell ISE退出时如何清理DLL中的资源 - 比如New-PSSession和New-PSJob

1 个答案: