Question

我正在使用VB.Net 2010.我有一个函数检查数据库中的请求，一些请求可能需要几分钟才能完成。我不希望它在处理请求时排队，所以我想动态创建新线程来运行每个新请求，以便它们可以同时运行。我不确定我是否应该使用线程，线程池，后台工作者或其他东西。任何建议和示例代码都会很棒。我可以用一个简单的例子。这就是我到目前为止所做的一切。

谢谢。

Imports System.Threading
Module Module1
Private trd As Thread
Sub Main()
    'START THREAD
    trd = New Thread(AddressOf command_loop)
    trd.IsBackground = True
    trd.Start()

    Console.ReadLine()
End Sub
Function command_loop()
       'CREATE EXPORT FILE
    Try
        Dim f As FileInfo
        Dim export As System.IO.StreamWriter
        Dim arr_comment

        'DELETE OLD EXPORT FILE
        If File.Exists(export_path) Then
            File.Delete(export_path)
        End If

        'VERIFY OLD EXPORT FILE WAS DELETED
        If File.Exists(export_path) Then
            writeToLog("ERROR: Old export file for " & username & " was not able to be deleted")
        End If

        'GET USER FOLDER CRC
        Dim di As New DirectoryInfo(user_folder)
        Dim fiArr As FileInfo() = di.GetFiles()
        export = My.Computer.FileSystem.OpenTextFileWriter(export_path, True)
        export.WriteLine("filepath, size, esize, date_mod_timestamp, timestamp, remote_filename, filestatus")

        For Each f In fiArr
            Try
                Using zip As ZipFile = ZipFile.Read(user_folder & "\" & f.Name)
                    For Each e As ZipEntry In zip
                        If (zip.Comment IsNot Nothing) AndAlso (zip.Comment <> "") Then
                            arr_comment = Split(zip.Comment, ":")
                        End If

                        If arr_comment.length <> 3 Then
                            'FILE HAS AN INVALID COMMENT, SO DELETE IT.
                            zip.Dispose()

                            Try
                                writeToLog("Invalid zip file comment, deleting file " & user_folder & "\" & f.Name)
                                File.Delete(user_folder & "\" & f.Name)
                                writeToLog("Zip file successfully deleted")
                            Catch exx As Exception
                                writeToLog("Unable to delete invalid zip file")
                                writeToLog(exx.Message)
                            End Try
                            Continue For
                        End If

                        'CORRECT FILE PATH
                        Dim filepath = Replace(e.FileName, "/", "\\")

                        export.WriteLine(Chr(34) & filepath & Chr(34) & "," & e.UncompressedSize & "," & e.CompressedSize & "," & arr_comment(1) & "," & arr_comment(2) & "," & f.Name & "," & arr_comment(0))
                        Exit For
                    Next
                End Using
            Catch ex As IOException
                Console.WriteLine(ex.Message)
            Catch ex As ZipException
                Console.WriteLine(ex.Message)
                Try
                    writeToLog("Invalid zip file, deleting file " & user_folder & "\" & f.Name)
                    File.Delete(user_folder & "\" & f.Name)
                    writeToLog("Zip file successfully delete")
                Catch e As Exception
                    writeToLog("Unable to delete invalid zip file")
                    writeToLog(e.Message)
                End Try
            End Try
        Next f
        export.Close()
    Catch ex As Exception
        Console.WriteLine(ex.Message)
    End Try

End Function
End Module

Answer 1

我将线程池用于此类任务。它比产生新线程的重量轻得多，后台工作者只支持每个工作线程一个线程。

Private Class MyArgs
    'add things for cancellation / storing results in here
End Class

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim args As New MyArgs()
    Threading.ThreadPool.QueueUserWorkItem(AddressOf DoThisSingleThing, New MyArgs)
End Sub

Private Sub DoThisSingleThing(state As Object)
    Dim args = CType(state, MyArgs)

    While Not args.Cancel

    End While

    args.Result = ...

    'If you need to update the UI afterward then invoke onto its thread.
    Me.BeginInvoke(Sub() OnComplete(args))
End Sub


Private Sub OnComplete(args As MyArgs)

End Sub

需要帮助在VB.Net中动态创建线程

1 个答案: