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Multithreading in VB.NET

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  10 years ago

  by Developer Fusion Bot

  Developer Fusion Bot

  , United Kingdom

  Joined 3 years ago

  This thread is for discussions of Multithreading in VB.NET.

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  3 years ago

  by skeet

  Jon Skeet

  Reading, England, United Kingdom

  Joined 4 years ago

  Volatility means a lot more than is described in the article. It doesn't just affect the variable which has the volatile modifed; it affects the whole memory model for sections of code involving access to that variable.
  

  
  I agree that there's no use of volatile which can't be semantically achieved using locks, and indeed I generally prefer to use locks myself. However, there is a speed difference between acquiring a lock and just using a volatile variable - in a very few cases it might be significant. I'm surprised VB.NET doesn't have any way of specifying this.
  

  
  See the volatility page of my C# threading article for more information.
  

  
  Jon Skeet
  

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  3 years ago

  by jspano

  John Spano

  SC, United States

  Joined 3 years ago

  Yes, but I decided not to go into detail since it's a vb.net article and you can't use it

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  2 years ago

  by stixoffire

  stixoffire

  USA, United States

  Joined 4 years ago

  As somewhat of an advanced "newbie" I have read many articles on Multithreading, and am at a loss

  Do I need to have a delegate and call the delegate when I am using threading ?

   

  Lets say I have a datatable with 5 million rows and I need to iterate through each row - grab some info , process that info (translate it) and then save it somewhere else. For example insert it inot a completely different database (and maybe even RDBMS - Architectur)

  Now I currently for each row - but that takes a lot of time.

  I would like to spawn a (Flexible Number of threads) to do the row processing - Will my For each move on as each thread runs. So I start Thread(1) will the next trigger, and I have a new row and can start thread(2) and so on. Also my Subroutine, must

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  1 year ago

  by momo200k

  momo200k

  , United States

  Joined 1 year ago

  Bundle of thanks to the author, it is very help full
   

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  4 months ago

  by catchsyed

  syed nizamuddin

  Bangalore, India

  Joined 4 months ago

  I need to lock the Log file once someone is using it and second person shouldn't able to write in log file. The code is shown below :

  Imports System Imports System.IO

  Module FileTransfer

  Sub Main()
      Dim dtStart As Date = Now(), dtEnd As Date = Now()
      Dim intNoofFiles As Integer = 0
      Dim strLogFileName As String = "C:\Log\FileTransferLog_" + dtStart.Year.ToString().PadLeft(4, "0") + dtStart.Month.ToString().PadLeft(2, "0") + dtStart.Day.ToString().PadLeft(2, "0") + ".txt"
      Dim oWrite As StreamWriter = File.AppendText(strLogFileName)
  
  
      oWrite.WriteLine("=================================================================================================")
      oWrite.WriteLine("Starting PRESTO File Transfer Job. Start Date: " + dtStart.ToString())
      oWrite.WriteLine("=================================================================================================")
  
      ' Call main job 
      subMoveFiles("C:\Presto\Inbound\", "c:\PRESTO_FILES\", oWrite, intNoofFiles)
  
      dtEnd = Now()
      oWrite.WriteLine("=================================================================================================")
      oWrite.WriteLine("Completed PRESTO File Transfer Job. End Date: " + dtEnd.ToString())
      oWrite.WriteLine("Total number of files transferred: " + intNoofFiles.ToString())
      oWrite.WriteLine("=================================================================================================")
  
      oWrite.Close()
  End Sub
  
  Public Sub subMoveFiles(ByVal strSrcDirectory As String, ByVal strDstDirectory As String, ByRef oWrite As StreamWriter, ByRef intNoofFiles As Integer)
      If strDstDirectory(strDstDirectory.Length - 1) <> Path.DirectorySeparatorChar Then
          strDstDirectory += Path.DirectorySeparatorChar
      End If
  
      If Not Directory.Exists(strDstDirectory) Then
          Directory.CreateDirectory(strDstDirectory)
      End If
  
      Dim strFileSystemEntries As String() = Directory.GetFileSystemEntries(strSrcDirectory)
      Dim strFileSystemEntry As String = ""
      For Each strFileSystemEntry In strFileSystemEntries
          If (Directory.Exists(strFileSystemEntry)) Then
              'Sub directories
              subMoveFiles(strFileSystemEntry, strDstDirectory + Path.GetFileName(strFileSystemEntry), oWrite, intNoofFiles)
          Else
              ' get the created date / last written date
              If DateAdd(DateInterval.Minute, 5, File.GetLastWriteTime(strFileSystemEntry)) < Now() Then
                  oWrite.WriteLine("Transferring File: " + strFileSystemEntry)
                  ' First Copy the file to the destination and then Delete
                  File.Copy(strFileSystemEntry, strDstDirectory + Path.GetFileName(strFileSystemEntry), True)
                  File.Delete(strFileSystemEntry)
                  intNoofFiles = intNoofFiles + 1
                  oWrite.WriteLine("Completed Transferring File: " + strFileSystemEntry)
              End If
          End If
      Next
  End Sub
  

  End Module

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