循环完成前退出Dowork的背景工人

Question

我有一个发送ping对象的程序，它会发送ping请求，每个ping对象重复（有8个），等待1000ms，然后重复此操作，但用户指定了很多秒。

当告诉程序以2-3秒的时间运行时间较低时，循环按预期工作。成功输出成功的ping的量（如果它运行了2秒，那么我希望每个ping对象都有2个成功的ping），

这是我收到的意外行为的示例，就是我将秒数设置为运行为10，因此它应该循环遍历8个ping对象中的每个对象，请等待一秒钟，然后重复此for count＆gt; 10

我正在调试，循环按预期工作，但随后在6秒后突然退出。我可以看到count = 10，而i是6，但是工人退出和runworkerCompleted方法被调用。

我可以想到线程的问题（？），但我不确定。

这是背景工人dowork方法：

private async void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    try
    {
        // Create background worker 
        BackgroundWorker worker = (BackgroundWorker)sender;

        // Write to log file
        await file.WriteAsync("Starting job...\n");
        await file.WriteAsync("Requested amount of pings: " + count + "\n");
        // Create date object for logs
        DateTime localDate = DateTime.Now;

        for (int i = 0; i < count; i++)
        {
            // Create ping objects
            System.Net.NetworkInformation.Ping pinger = new System.Net.NetworkInformation.Ping();
            PingReply pingReply;

            foreach (Ping pingObj in pings)
            {
                try
                {
                    pingReply = pinger.Send(pingObj.IpAddress);
                    // Write log file
                    await file.WriteLineAsync(localDate.TimeOfDay + " | Friendly Name " + pingObj.FriendlyName + " | Ping: " + pingReply.Address + " | Status " + pingReply.Status + " | Time: " + pingReply.RoundtripTime);
                    if (pingReply.Status.ToString().Contains("Success"))
                    {
                        pingObj.SuccessfulPings += 1;
                    }
                    else // Unsuccessful ping has been sent
                    {
                        pingObj.FailedPings += 1;
                    }
                }
                catch (Exception ex)
                {
                    Debug.WriteLine(ex.ToString());
                }
            }
            wait(1000);
        }
    }
    catch (Exception a)
    {
        Debug.WriteLine(a.ToString());
    }
}

这是我开始使用一个按钮的方法：

private void Ping_Btn_Click(object sender, EventArgs e)
{
    int counter = 1;
    if (backgroundWorker1.IsBusy != true)
    {
        // For every ping object    
        foreach (Ping pinger in pings)
        {
            // Set the appropriate UI element properties
            // Create initial control object
            // Finds controls in which their name matches the string
            Control? ctl = this.Controls.Find("greenBox" + counter, true).FirstOrDefault() as Control;
            if (ctl != null)
            {
                ctl.Visible = false;
            }
            ctl = this.Controls.Find("orangeBox" + counter, true).FirstOrDefault() as Control;
            if (ctl != null)
            {
                ctl.Visible = false;
            }
            ctl = this.Controls.Find("redBox" + counter, true).FirstOrDefault() as Control;
            if (ctl != null)
            {
                ctl.Visible = true;
            }
            ctl = this.Controls.Find("status_Lbl" + counter, true).FirstOrDefault() as Control;
            if (ctl != null)
            {
                ctl.Text = "Initiated...";
            }

            counter++;
        }
        // Take input from text box
        count = Convert.ToInt32(pingSeconds_TxtBox.Text);
        // Start operation
        backgroundWorker1.RunWorkerAsync();
    }
}

这是等待1000毫秒的方法，

public void wait(int milliseconds)
{
    var timer1 = new System.Windows.Forms.Timer();
    if (milliseconds == 0 || milliseconds < 0) return;

    timer1.Interval = milliseconds;
    timer1.Enabled = true;
    timer1.Start();

    timer1.Tick += (s, e) =>
    {
        timer1.Enabled = false;
        timer1.Stop();
    };

    while (timer1.Enabled)
    {
        Application.DoEvents();
    }
}

它循环的次数似乎是随机的，我只是对其进行了测试删除线后，以防.doevents（）；线正在干扰背景工作者。

while (timer1.Enabled)
{
    Application.DoEvents();
}

用count = 10像往常一样运行它，这是两次，并且第一次运行一次，第二次跑了7次。

任何帮助都将不胜感激

答案 删除了背景工人并实施了async/等待

• Charlieface提供的答案

Answer 1

您不能混合async void和backgroundworker.dowork，因为一旦您击中第一个等待 ，dowork 处理程序已向工人出现。

我建议您完全删除backgroundworker，只需使用等待即可。

示例代码似乎缺少信息：什么是pings count和文件？我试图猜测它是如何工作的，但是看来您正在为这些使用某种缓存字段，至少在file的情况下）可能是不可接受的。

SemaphoreSlim _sem = new SemaphoreSlim(1, 1);

private void Ping_Btn_Click(object sender, EventArgs e)
{
    if (!await _sem.WaitAsync(0))  // bail-out if already executing
        return;
    try
    {
        int counter = 1;
        // For every ping object    
        foreach (Ping pinger in pings)
        {
            // Set the appropriate UI element properties
            // Create initial control object
            // Finds controls in which their name matches the string
            (this.Controls.Find("greenBox" + counter, true).FirstOrDefault() as Control)?.Visible = false;
            (this.Controls.Find("orangeBox" + counter, true).FirstOrDefault() as Control)?.Visible = false;
            (this.Controls.Find("redBox" + counter, true).FirstOrDefault() as Control)?.Visible = true;
            (this.Controls.Find("status_Lbl" + counter, true).FirstOrDefault() as Control)?.Text = "Initiated...";
            counter++;
        }
        // Take input from text box
        count = Convert.ToInt32(pingSeconds_TxtBox.Text);
        // Start operation
        await DoPing();
    }
    finally
    {
        // release lock
        _sem.Release();
    }
}

private async Task DoPing()
{
    try
    {
        // Write to log file
        await file.WriteAsync("Starting job...\n");
        await file.WriteAsync("Requested amount of pings: " + count + "\n");
        // Create date object for logs
        DateTime localDate = DateTime.Now;

        using (System.Net.NetworkInformation.Ping pinger = new System.Net.NetworkInformation.Ping())
        {
            for (int i = 0; i < count; i++)
            {
                foreach (Ping pingObj in pings)
                {
                    try
                    {
                        var pingReply = await pinger.SendAsync(pingObj.IpAddress);
                        // Write log file
                        await file.WriteLineAsync(localDate.TimeOfDay + " | Friendly Name " + pingObj.FriendlyName + " | Ping: " + pingReply.Address + " | Status " + pingReply.Status + " | Time: " + pingReply.RoundtripTime);
                        if (pingReply.Status == IPStatus.Success)
                        {
                            pingObj.SuccessfulPings += 1;
                        }
                        else // Unsuccessful ping has been sent
                        {
                            pingObj.FailedPings += 1;
                        }
                    }
                    catch (Exception ex)
                    {
                        Debug.WriteLine(ex.ToString());
                    }
                }
                await Task.Delay(1000);
            }
        }
    }
    catch (Exception a)
    {
        Debug.WriteLine(a.ToString());
    }
}