Question

我有以下线程代码（我认为）表单，带有一个启动和取消按钮以及一个多行文本框，注释部分（//）来自工作单线程版本，下面我试图改进多线程任务.factory部分，但它似乎启动powershell命令很好（在任务管理器中显示）但程序完成而不等待每个“heavyOperation”的结果。

想法是同时启动所有四个HeavyOperation任务（ish）并等待每个任务返回结果并将结果附加到文本框

public partial class Form1 : Form
{
    Progress<string> progressReporter = new Progress<string>();
    CancellationTokenSource cancelSource;

    public Form1()
    {
        InitializeComponent();
        progressReporter.ProgressChanged += progressManager_ProgressChanged;
    }

    async private void btnStart_Click(object sender, EventArgs e)
    {
        btnStart.Enabled = false;
        btnCancel.Enabled = true;
        cancelSource = new CancellationTokenSource();
        //textBox1.Text = await Task.Run(() => PerfromTaskAction(cancelSource.Token));
        await Task.Run(() => PerfromTaskAction(cancelSource.Token));
        lblStatus.Text = "Completed.";           btnStart.Enabled = true;
        btnCancel.Enabled = false;
    }
    //private string PerfromTaskAction(CancellationToken ct)
    static void PerfromTaskAction(CancellationToken ct)
    {
        //StringBuilder sb = new StringBuilder();

        object[] arrObjects = new object[] { "SERVER1", "SERVER2", "SERVER3", "SERVER4" };

        foreach(object i in arrObjects)
        {
            //if (ct.IsCancellationRequested) break;
            //sb.Append(string.Format("{0}: {1}\r\n", HeavyOperation(i.ToString()),i));
            //((IProgress<string>)progressReporter).Report(string.Format("Now Checking: {0}...", i));
            Task.Factory.StartNew(() => HeavyOperation(i.ToString()));
        }
        //return sb.ToString();
    }
    void progressManager_ProgressChanged(object sender, string e)
    {          
        lblStatus.Invoke((Action)(() => lblStatus.Text = e));
    }
    //private string HeavyOperation(string i)
    public static void HeavyOperation(string i)
    {
        PowerShell ps = PowerShell.Create();
        ps.AddCommand("invoke-command");
        ps.AddParameter("computername", i);
        ps.AddParameter("scriptblock", ScriptBlock.Create("get-vmreplication | select State"));
        Collection<PSObject> result = ps.Invoke();
        //return result[0].Properties["State"].Value.ToString();
        Console.Write(result[0].Properties["State"].Value.ToString());
    }
    private void btnCancel_Click(object sender, EventArgs e)
    {
        cancelSource.Cancel();
    }

}

感谢您寻找

Answer 1

您还需要等待HeavyOperation完成。

您可以将Task.WhenAll用于此目的。以下是async的{{1}}版本，使用PerformTaskAction

我考虑过 Scott Chamberlain 的建议：

将不安全（在Task.WhenAll上下文中）async-await更改为Task.Factory.StartNew()
在调用Task.Run()

await

在外部PerformTaskAction()电话
中传递了丢失的CancellationToken
static async Task PerfromTaskAction（CancellationToken ct）{ // StringBuilder sb = new StringBuilder（）;
```
Task.Run()
```

~~现在PerformTaskAction是异步的，你还需要等待它。~~

最后你调用PerformTaskAction，确保你也传递了CancellationToken。

     object[] arrObjects = new object[] { "SERVER1", "SERVER2", "SERVER3", "SERVER4" };
     IList<Task> tasks = new List<Task>(); // collect all tasks in single collection
     foreach( object i in arrObjects ) {
        //if (ct.IsCancellationRequested) break;
        //sb.Append(string.Format("{0}: {1}\r\n", HeavyOperation(i.ToString()),i));
        //((IProgress<string>)progressReporter).Report(string.Format("Now Checking: {0}...", i));
        tasks.Add(Task.Run(() => HeavyOperation(i.ToString())));
     }

     await Task.WhenAll(tasks).ConfigureAwait(false); // wait asynchronously for all tasks to complete
  }

将线程转换为多线程代码？（任务工厂？）

1 个答案:

将线程转换为多线程代码？ （任务工厂？）

1 个答案:

将线程转换为多线程代码？（任务工厂？）