C# 多线程

我正在开发一个应用程序（用C#）。这基本上是一个文件上传/下载应用程序（就像filezila）

但有一个特殊功能（文件下载）：-

我们可以将一个文件分成不同的部分（最多100个）。并且可以通过不同的周期重复这个过程（意味着我们可以将一个文件分成不同的段，并且可以同时重复这个过程多次（通过周期）

在应用程序中有一些进度条和标签显示上传/下载状态

我的问题是：-

如果我对更多号码执行此过程（下载），例如：-

100次循环和（循环可以超过100次）

100段

这意味着我们将一个文件分为100个部分（段），相同的过程将工作100次（周期）

意味着100*100=10000个文件将通过相同的过程同时下载

但我面临的问题是，若我为这项任务接受了大量的数据，那个么就会有更多的线程打开

如果有100个TCP端口/线程同时运行，应用程序将挂起

我为此做了很多尝试，但还没有成功-

异步委托、线程池等

我在更新进度条和标签时面临一个主要问题（因为当前的功能与异步委托一起工作）

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请为我提供一些解决此问题的方法。

因为所有这些线程都希望向UI线程传递数据以显示进度，UI线程正在成为应用程序的瓶颈

您可以添加一个计时器，使UI线程时不时地检查作业的进度

这样，UI线程不是由大量线程驱动的，而是由时间驱动的

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如果您需要更多详细信息，请发布一些代码。

你好，Erno为了更好地理解，我将发送一些代码：-

这是下载功能：

Public Sub FileDownload()

    txtBytesToDownload.Text = totalBytesToDownload.ToString("N", nfi)  'set textbox with total file size

    del = New MyDelegate(AddressOf DownloadDataInRange)

    callback = New AsyncCallback(AddressOf CalcCallback)


    TotalBytesToDownloadForEachCycle = totalBytesToDownload
    downloadedBytes = 0
    dlStopWatch = Stopwatch.StartNew()

    Dim flag As Integer = 0

    Dim segment As Integer = nuSegment.Value          'total segments
    Dim cyl = cycleNumericUpDown.Value                'total cycles

    'ServicePointManager.DefaultConnectionLimit = segment

    If UtilityFunctions.CheckRangeSupported(dlUrlHttpTextBox.Text) Then

        Dim segmentSize As Integer = 0
        segmentSize = TotalBytesToDownloadForEachCycle / segment

        ' For cy As Integer = 0 To (cyl - 1)

        For ctr As Integer = 0 To (segment - 1)        'loop for total Segments

            GC.Collect()
            flag += 1

            Dim fileValues As New FileValues()

            If ctr = 0 Then
                fileValues.StartPoint = 0               'starting point of each segment (in bytes)
            Else
                fileValues.StartPoint = segmentSize * ctr + 1
            End If

            fileValues.EndPoint = fileValues.StartPoint + segmentSize   'end point of each segment (in bytes)

            If (ctr = (segment - 1)) Then
                fileValues.EndPoint += TotalBytesToDownloadForEachCycle Mod segment
            End If

            fileValues.URL = dlUrlHttpTextBox.Text                         'downloading file url
            Dim str As String = ctr.ToString() + "_" + flag.ToString()

            ' del.BeginInvoke(fileValues, callback, Nothing)


            newThread = New System.Threading.Thread(AddressOf DownloadBytes)      'Thread starts here
            newThread.Priority = ThreadPriority.Highest
            newThread.IsBackground = True
            newThread.Start(fileValues)

            'ThreadPool.QueueUserWorkItem(AddressOf DownloadBytes, fileValues)

            fileValues = Nothing

        Next

        ' ProgressBarTotal.Value += 1

        ' Next

    Else
        Dim fileValues As New FileValues()
        fileValues.StartPoint = 0
        fileValues.EndPoint = TotalBytesToDownloadForEachCycle
        fileValues.URL = dlUrlHttpTextBox.Text
        Dim newThread As New System.Threading.Thread(AddressOf DownloadBytes)
        newThread.Name = "Thread1"
        newThread.Start(fileValues)
        'ThreadPool.QueueUserWorkItem(AddressOf DownloadBytes, fileValues)
        fileValues = Nothing

    End If

    Console.WriteLine("Http Downloload End")
    Debug.Print("thread List 1 count =" + _threadsList1.Count.ToString() + ", thread list 2 count =" + _threadsList2.Count.ToString() + ", thread list 3 count =" + _threadsList3.Count.ToString())

    'MessageBox.Show("finished - flag=" + flag.ToString())

    'After all Cycles Complete 
    'startButton.Enabled = True
    'abortButton.Enabled = False
    'skipButton.Enabled = False
    'DataGridViewDLOrPing.Enabled = True
    'DataGridViewUL.Enabled = True

    'protocolComboBox.Enabled = True
    'modelComboBox.Enabled = True
    'testTypeComboBox.Enabled = True
    'measurementComboBox.Enabled = True
    'cycleNumericUpDown.Enabled = True
    'DelayNumericUpDown.Enabled = True
    'InputBoxPrivilege()

End Sub

这是线程将调用以读取字节的函数：

Public Sub DownloadBytes(ByVal p_fileValues As FileValues)

    Dim httpWebRequest As HttpWebRequest
    Dim httpWebResponse As HttpWebResponse
    Dim responseStream As Stream

    Dim threadName = threadID

    Try
        Console.WriteLine("Start " + Thread.CurrentThread.Name)
        httpWebRequest = DirectCast(WebRequest.Create(p_fileValues.URL), HttpWebRequest)
        'httpWebRequest.ProtocolVersion = HttpVersion.Version11
        httpWebRequest.KeepAlive = False
        httpWebRequest.AddRange(p_fileValues.StartPoint, p_fileValues.EndPoint)
        httpWebRequest.Credentials = CredentialCache.DefaultCredentials
        httpWebRequest.Proxy = WebRequest.DefaultWebProxy
        httpWebResponse = CType(httpWebRequest.GetResponse(), HttpWebResponse)
        responseStream = httpWebResponse.GetResponseStream()

        Dim bytesSize As Integer = 0
        ' A buffer for storing and writing the data retrieved from the server
        Dim downBuffer As Byte() = New Byte(2047) {}
        Dim bytesAlreadyDownloaded As Int64 = p_fileValues.StartPoint

        ' Loop through the buffer until the buffer is empty
        While (True)

            'end while loop if the Abort button is clicked
            If (isActionAborted = True) Then
                Exit While
            End If

            'currentCycle is > total Cycles ,then end while
            If (currentCycleDownload > cycleNumericUpDown.Value) Then
                Exit While
            End If

            bytesSize = responseStream.Read(downBuffer, 0, downBuffer.Length)

            bytesAlreadyDownloaded += bytesSize

            'speedtimer.Start()

            If (bytesSize <= 0) Then
                If (downloadedBytes < totalBytesToDownload) Then
                    Me.Invoke(New UploadProgressCallback(AddressOf Me.UpdateDownloadProgress), New Object() {(totalBytesToDownload - downloadedBytes), totalBytesToDownload})
                End If

                Exit While
            End If

            ' Invoke the method that updates the form's label and progress bar
            Me.Invoke(New DownloadProgressCallback(AddressOf Me.UpdateDownloadProgress), New Object() {bytesSize, TotalBytesToDownloadForEachCycle})

            If (bytesAlreadyDownloaded > p_fileValues.EndPoint) Then
                'Console.WriteLine("Downloading part files Exit " + p_fileValues.StartPoint.ToString() + "," + p_fileValues.EndPoint.ToString())
                Exit While
            End If

        End While

        responseStream.Flush()
        responseStream.Close()
        httpWebResponse.Close()
        responseStream.Dispose()
        responseStream = Nothing
        httpWebResponse = Nothing
        Console.WriteLine("End " + Thread.CurrentThread.Name)

        'ProgressDownload.Value = Convert.ToInt32((downloadedBytes * 100) / totalBytesToDownload)
        ' downloadedBytesTextBox.Text = downloadedBytes.ToString("N", nfi)

    Catch ex As Exception

        Console.WriteLine("Error " + Thread.CurrentThread.Name)
        Console.WriteLine(ex)

    Finally
        Console.WriteLine("Finally " + Thread.CurrentThread.Name)

        GC.Collect()

        ' GC.WaitForPendingFinalizers()
        'newThread.Abort()


        'Try
        'Thread.CurrentThread.Abort()

        'Catch ex1 As Exception

        'End Try
    End Try

    'Return 1

End Sub

公共子下载字节（ByVal p_fileValues作为fileValues）
将httpWebRequest设置为httpWebRequest
将httpWebResponse设置为httpWebResponse
暗淡的反应像溪流一样
Dim threadName=threadID
尝试
Console.WriteLine（“开始”+Thread.CurrentThread.Name）
httpWebRequest=DirectCast（WebRequest.Create（p_fileValues.URL），httpWebRequest）
'httpWebRequest.ProtocolVersion=HttpVersion.Version11
httpWebRequest.KeepAlive=False
httpWebRequest.AddRange（p_fileValues.StartPoint，p_fileValues.EndPoint）
httpWebRequest.Credentials=CredentialCache.DefaultCredentials
httpWebRequest.Proxy=WebRequest.DefaultWebProxy
httpWebResponse=CType（httpWebRequest.GetResponse（），httpWebResponse）
responseStream=httpWebResponse.GetResponseStream（）
Dim bytesSize为整数=0
'用于存储和写入从服务器检索的数据的缓冲区
Dim downBuffer As Byte（）=新字节（2047）{}
Dim BytesalReadyDownload为Int64=p_fileValues.StartPoint
'循环通过缓冲区，直到缓冲区为空
While（True）
'单击中止按钮时结束循环
如果（isActionAborted=True），则
退出时
如果结束
'当前周期>总周期，然后在
如果（currentCycleDownload>cycleNumericUpDown.Value），则
退出时
如果结束
bytesSize=responseStream.Read（downBuffer，0，downBuffer.Length）
bytesAlreadyDownloaded+=ByteSize
'speedtimer.Start（）
如果（通过细化p_fileValues.EndPoint），则
'Console.WriteLine（“下载部件文件退出”+p_fileValues.StartPoint.ToString（）+”，“+p_fileValues.EndPoint.ToString（））
退出时
如果结束
结束时
responseStream.Flush（）
responseStream.Close（）
httpWebResponse.Close（）
responseStream.Dispose（）
responseStream=无
httpWebResponse=无
Console.WriteLine（“End”+Thread.CurrentThread.Name）
'ProgressDownload.Value=Convert.ToInt32（（downloadedBytes*100）/totalBytesToDownload）
'downloadedBytesTextBox.Text=downloadedBytes.ToString（“N”，nfi）
特例
Console.WriteLine（“错误”+Thread.CurrentThread.Name）
控制台写入线（ex）
最后
Console.WriteLine（“Finally”+Thread.CurrentThread.Name）
GC.Collect（）
'GC.WaitForPendingFinalizers（）
'newThread.Abort（）
“试试看
'Thread.CurrentThread.Abort（）
'捕获ex1作为异常
“结束尝试
结束尝试
'返回1
端接头

此功能将更新表单上的进度条和其他标签：

Private Sub UpdateDownloadProgress(ByVal BytesRead As Int64, ByVal TotalBytes As Int64)
    If Not swDL Is Nothing AndAlso swDL.IsRunning Then
        swDL.Stop()
        If swDL.ElapsedMilliseconds > 0 Then
            resultGrid.Rows.Item(HandoverGridCounter - 1).Cells(4).Value &= "DL: " & swDL.ElapsedMilliseconds & " ms"
        End If
        swDL = Nothing
    End If


    If (dlCurrentspeed > 0) Then
        'txtCurrentSpeedDL.Text = Math.Round((dlCurrentspeed / 1024), 0) & " KB/s"
    End If


    downloadedBytes += BytesRead
    If downloadedBytes >= totalBytesToDownload Then
        downloadedBytes = totalBytesToDownload
    End If

    ProgressDownload.Value = Convert.ToInt32((downloadedBytes * 100) / TotalBytes)
    downloadedBytesTextBox.Text = downloadedBytes.ToString("N", nfi)  ' & " bytes"

    If totalBytesToDownload = 0 Then
        totalBytesToDownload = TotalBytes
        txtBytesToDownload.Text = totalBytesToDownload.ToString("N", nfi)
    End If

    If downloadedBytes >= totalBytesToDownload Then
        dlCurrentspeed = 0
        dlStopWatch.Stop()

        testEndTickDownload = My.Computer.Clock.TickCount
        testDeltaDownload = (testEndTickDownload - testStartTickDownload) / 1000
        If DLtimedOut = True Then
            DownloadCompleted(TestStatus.Cancelled.ToString(), "")
        Else
            DownloadCompleted(TestStatus.Completed.ToString(), "")
        End If
        If currentCycleDownload <= cycleNumericUpDown.Value Then
            If protocolComboBox.Text = "HTTP" Then
                StartHttpDownload()
            Else
                StartFtpDownload()
            End If
        End If
    End If
End Sub

Private Sub UpdateDownloadProgress（ByVal BytesRead为Int64，ByVal TotalBytes为Int64）
如果不是swDL什么都不是，也就是swDL.IsRunning，那么
swDL.Stop（）
如果swDL.elapsedmillisons>0，则
resultGrid.Rows.Item（HandoverGridCounter-1）.单元格（4）.值&=“DL:”&swDL.elapsedmillesons&“ms”
如果结束
swDL=无
如果结束
如果（dlCurrentspeed>0），则
'txtCurrentSpeedDL.Text=Math.Round（（dlCurrentspeed/1024），0）和'KB/s'
如果结束
downloadedBytes+=字节读取
如果downloadedBytes>=TotalByTestToDownload，则
downloadedBytes=TotalByTestToDownload
如果结束
ProgressDownload.Value=Convert.ToInt32（（下载字节*100）/TotalBytes）
downloadedBytesTextBox.Text=downloadedBytes.ToString（“N”，nfi）&“bytes”
如果TotalByTestToDownload=0，则
TotalByTestToDownload=TotalBytes
txtBytesToDownload.Text=totalBytesToDownload.ToString（“N”，nfi）
如果结束
如果downloadedBytes>=TotalByTestToDownload，则
dlCurrentspeed=0