CODEWITHSUNDEEP
user-interfacedatagridviewbackgroundworkerfreezemaximize
Jhon
Jhon

Reputation: 11

GUI freezing after datagridviews have been updated using backgroundworkers

I have made an application which runs three backgroundworkers simultaneously. It basically updates three datagridviews, which it is doing spot on. My problem is if I press maximizebox button or anywhere in any of the datagridview the program hangs for quite a long time. I am able to use the horizontal scroll but not vertical scrolls. I have tried Backgroundworker_runworkercompleted and it fires as required after threads have updated their respective datagridviews. Is it a normal behaviour or am i doing something wrong any suggestions would be helpful. P.S: I have run the whole program using step method and their is no infinite loop in the code. Thanks in advance Jhon

Upvotes: 1

Views: 3171

Answers (6)

Sérgio Azevedo
Sérgio Azevedo

Reputation: 353

It's too late to answer to @Jhon but it seems like it might help other people. In my case, I was using a BindingSource and the UI only froze if there where so many records that scrollbars had to appear.

When you use a background worker, task or thread to do the work, you have to update your UI controls on the main UI thread. To do that you can Invoke a method in the corresponding thread.

A simple example:

myDataGridView.Invoke((MethodInvoker)delegate { myBindingSource.DataSource = myData; });

But i prefer this solution: InvokeIfRequired

Upvotes: 0

mono código
mono código

Reputation: 405

I had the same problem. When my dataGridViews were being updated from the UI thread, they worked fine. When I tried to add a series of rows to them from the backgroundWorker, they became unresponsive.

To correct this, I added the rows to a dataTable instead. When I kick off the backgroundWorker, I set the .datasource property of the dataGridView to nothing. When the worker completes, I set it back to the dataTable again. This both forces the dataGridView to update itself, and severs the synchronous connection between what it happening in the worker thread, and what is being displayed in the UI, which seems to alleviate the unresponsiveness when the worker completes.

Sample usage:

Private Sub button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click
    If bgWorker1.IsBusy <> True Then
        dataGridView1.DataSource = Nothing

        bgWorker1.RunWorkerAsync()
    End If
End Sub

Private Sub bgWorker_DoWork(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bgWorker1.DoWork
    dataTable1.Rows.Add("data")
End Sub

Private Sub bgWorker_RunWorkerCompleted(ByVal sender As System.Object, ByVal e As RunWorkerCompletedEventArgs) Handles bgWorker1.RunWorkerCompleted
    dataGridView1.DataSource = dataTable1
    dataGridView1.Refresh()
End Sub

Upvotes: 0

Ali Ezzat Odeh
Ali Ezzat Odeh

Reputation: 2163

You have to make sure that you are updating the datagridviews from the UI thread.

Upvotes: 0

Saqib
Saqib

Reputation: 2283

Place this line of code just before when you are calling Backgroundworker1.RunWorkerAsync() to temporarily disable your datagridview scroll bars.

DataGridView1.ScrollBars = ScrollBars.None

Now Re-enable scroll bars of your datagridview by adding this line of code in BackgroundWorker1_RunWorkerCompleted event.

DataGridView1.ScrollBars = ScrollBars.Both

This will never make your application unresponding.

Upvotes: 3

Jhon
Jhon

Reputation: 1

Okay I have found the solution to my problem, while working out sequential elimination of the perceived trouble spots, I called my datagridview outside of the backgroundworker.dowork event and voila that solved the problem. Moral of the story "NEVER UPDATE A DATA GRID VIEW FROM WITHIN THE BACKGROUNDWORKER THREAD" specially when you don't know what are you doing wrong :). I hope it will help someone in future.

Upvotes: 0

Justin Ethier
Justin Ethier

Reputation: 134247

It sounds like you are still blocking the UI thread somehow. It may be helpful for you to post some code snippets. Also, what is the CPU utilization of your process? If the cpu usage is high, you may be starving the UI thread somehow.

Upvotes: 0

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