Listview is not responding by Parallel.Forech loop

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Hi Everyone.....

I have a list view , where i want to show a collection of data recursively ..., I use back ground worker to keep my user interface active .., i also use Parallel.ForEach to load the data in list view at a time .

My code is:

C#

public void bg_DoWork(object sender, DoWorkEventArgs e)
{

     Parallel.ForEach(this.listView1.Items.Cast<ListViewItem>(), list =>;
             {
                Function_ABCD(list);
             });
}

In my "Function_ABCD", i update my listview by adding huge number of listviewitem . my problem is that listview freezes when execution is going on.other function is running smoothly means i can minimize or maximize the form ,stop the execution etc....

how can i update the listview ?

Thanking You..

Posted 25-Feb-13 21:49pm

krushna chandra jena

Updated 25-Feb-13 22:01pm

Joezer BH

v2

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Jegan Thiyagesan · Answer 1 · 2013-02-25T23:37:00

Hi,
You are trying to access a control in other threads that was created in main thread. The exception you will get from your code is the Cross-thread exception.

Try the code below:

C#

delegate void SetListviewItemsCallback(ListView.ListViewItemCollection listViewItems);

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    ProcessListView(listView1.Items);
}

public void ProcessListView(ListView.ListViewItemCollection listViewItems)
{
    if (listView1.InvokeRequired)
    {
        SetListviewItemsCallback d = new SetListviewItemsCallback(ProcessListView);
        this.Invoke(d, new object[] { listViewItems });
    }
    else
    {
        ListView.ListViewItemCollection items = listViewItems;
        Parallel.ForEach<ListViewItem>(items.Cast<ListViewItem>(), list =>
         {
             Function_ABCD(list);
         });
    }
}

This will get you out of cross thread exception when you are extracting the items from listView1, however, you have to do similar thing when you add the items into your

C#

Function_ABCD(ListViewItem item)

. You will be accessing the "Function_ABCD" through multiple of thread, there will be cross thread exception as well as race condition; this will result in one item being added multiple of times which will cause an Argument exception.

I hope this helps.

Regards
Jegan