Vb.net parallel foreach

Question

0.00/5 (No votes)

See more:

Hello,

Recently I discovered Parallel ForEach because I was still using VB 2010. In my application I open a hundred files to retrieve information and it takes a lot of time. I would like to succeed in using Parallel ForEach but I can't do it at all, I've been looking everywhere on google for 3 days ...
Could someone help me convert my little piece of code?

VB

Lv1.Items.Clear()
        Dim DirInv As DirectoryInfo
        Dim CheminFichierIni As String 'Path of my file of configuration
        If Debugger.IsAttached Then
            DirInv = New DirectoryInfo("\\w11900100akf\Mnt_CPAM\Inventaire\Log")
        Else
            DirInv = New DirectoryInfo(Path.Combine(Application.StartupPath, "Log"))
        End If
        ' Get a reference to each file in that directory.
        Dim FilInv As FileInfo() = DirInv.GetFiles()
        ' Display the names of the files.

        For Each FileInfoInv As FileInfo In FilInv 'Here i want to use Parallel For Each
            CheminFichierIni = FileInfoInv.FullName 'For each file, i read information
            Dim LstVItem As New ListViewItem(LireINI("PMF", "NetBios", CheminFichierIni))
            LstVItem.SubItems.Add(LireINI("PMF", "Owner", CheminFichierIni))
            LstVItem.SubItems.Add(... ...

Thank you

What I have tried:

a lot of code found on the internet but it doesn't lead to what I'm trying to do ...

Posted 23-Mar-21 5:27am

DX90

Updated 25-Mar-21 0:36am

Add a Solution

Comments

CHill60 23-Mar-21 11:40am

So what happens when you replace that For Each with Parallel.ForEach?

2 solutions

Solution 3

Hello,

You're right, when reading a file it doesn't change much
Thank you for your help

Posted 25-Mar-21 0:36am

DX90

Comments

Richard Deeming 25-Mar-21 8:56am

If you want to reply to a solution, click the "Have a Question or Comment?" button under that solution and post a comment.

Do not post your comment as a new solution.

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2021-03-23T06:18:00

As Chill60 has said: try replacing For Each with Parallel.ForEach:

VB

Parallel.ForEach(FileInv, Sub(FileInfoInv)
                          CheminFichierIni = FileInfoInv.FullName
                          ...    
                          End Sub)

But ... threading and parallelism isn't a "magic bullet" that will make your code 100 times faster: each object in the collection requires it's own thread, and to run that thread needs a free processor core. If no core is available, the thread goes into a wait state waiting for one to be free. So the number of cores in your system and the load on the system outside your app will decide how much faster you app will be. It is entirely possible that creating too many threads will cause your whole app to slow down rather than speed up as all the threads are "fighting" to get a core and the threading process plus switching threads adds overhead to the processor. I would not recommend 100 threads at all - and there is a very good chance that your app will crash as well given that ListView is not thread safe, and you are accessing UI controls from a non-UI thread ...