CODEWITHSUNDEEP
vb.netsynchronizationtask
DavidTheDev
DavidTheDev

Reputation: 406

Tasks Basics: Tasks Vs Multiple Instance of a applications

I have a legacy app that is suddenly important. It needs to be faster. There are many pieces of code that would be candidates for parallel processing, such as unzipping large files and downloading multiple files instead of one at a time. It also processes data files, and I think this could be done with a thread per file, but I've had trouble with that.

I see two possible solutions.

Solution 1) Create a task for each _file in FilesToProcess and use Task.Run(Tasks.ToArray()).

Solution 2) Add a handle to the main app that taked in a parameter of string and pass the _fileToProcess. Then process the file normally. In this approach, i'm simply launching a new process of the existing application to process a single file, but I launch as many as I need.

My code isn't thread safe. Will I really have to rewrite the code so that all my sub processes are sync locked or await on any problem area I.E. MethodCall1 passing byref? Is there a simpler solution?

If so, solution 2 seems like it will be a much easier approach, even at the loss of transparency.

Below is a pseudo code example of how it's written now.

Public Sub Main()
  Dim Foo, Bar
  Dim FilesToProcess =   DownloadFiles()
   For Each _file as string in FilesToProcess
  UnzipFile(_file)
  MethodCall1(Foo,Bar)
  MethodCall2SqlIdentityInsert()
  MethodCall2SqlUpdate()
 Next
End Sub

Public Sub MethodCall1(ByRef Foo, ByRef Bar)
   Foo = Something
   bar = SomethingElse
End Sub

pseudo Code Sol1 

Public Sub Main()
   Dim tasks As List(Of Task) = New List(Of Task)()

  Dim FilesToProcess =   DownloadFiles()
   For Each _file as string in FilesToProcess
   tasks.Add(Task.RunSub()
   Dim Foo, Bar
  UnzipFile(_file)
  MethodCall1(Foo,Bar)
  MethodCall2SqlIdentityInsert()
  MethodCall2SqlUpdate()
 End Sub)
 Next
Task.WaitAll(tasks.ToArray())
End Sub

Public Sub MethodCall1(ByRef Foo, ByRef Bar)
   Foo = Something
   bar = SomethingElse
End Sub

Upvotes: 1

Views: 40

Answers (1)

PavlinII
PavlinII

Reputation: 1083

I would prefere Solution 1) IF you can isolate instances to make it thread safe.

That means something like

Public Class IsolatedWorker

    private fFileName As String
    Private fFoo, fBar As Object

    Public Sub New(FileName)
        fFileName=FileName
    End New

    Public Sub Process()
        UnzipFile
        MethodCall1()
        MethodCall2SqlIdentityInsert()
        MethodCall2SqlUpdate()
    End Sub

    Private sub UnzipFile()
    End Sub

    Private sub MethodCall1()
        fFoo = Somehting
        fBar = SomethingElse
    End Sub

    Private sub MethodCall2SqlIdentityInsert()
    End Sub

    Private sub MethodCall2SqlUpdate()
    End Sub

End Class

If you can avoid all global variables and persist your state inside IsolatedWorker, than you'll get it thread safe.

Upvotes: 1

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