Access violation Issue in MultiThreading

**Description:** The Access violation Issue in MultiThreading

Language: VB .NET 2005

Description:

We are creating an instance of webbrowser control object internally in the code, and assign an html text to its “DocumentText?? property. When the [login to view URL] = [login to view URL], we are accessing the parsed html Document object and using it for some operations.

The Webbrowser control is not in the GUI , it is created dynamically and never displayed.

## Deliverables

**Description:** The Access violation Issue in MultiThreading

Language: VB .NET 2005

Description:

We are creating an instance of webbrowser control object internally in the code, and assign an html text to its “DocumentText?? property. When the [login to view URL] = [login to view URL], we are accessing the parsed html Document object and using it for some operations.

The Webbrowser control is not in the GUI , it is created dynamically and never displayed.

We are using multithreading and every thread created does the above process. These threads work independently , and their appartment state is STA ([login to view URL]).

The process in the thread reads HTML tags and parse them using the webbrowser object created.

Problem:

The threads gets created and starts fine. After a few iterations we gets the error

“Attempted to read or write protected memory. This is often an indication that other memory is corrupt.??

And the StackTrace of the Exception was

[login to view URL]()

at System.Windows.Forms.WebBrowser.get_Document()

at System.Windows.Forms.WebBrowser.get_ReadyState()

Tried Fixes:

[login to view URL] the webbrowser object

Shared wbAds As WebBrowser

2. Called [login to view URL]() after every iterations

[login to view URL] the Thread Sleep interval.

This fixes didn’t sloved the problem

Our Code model with threading

Private sub subThreadCaller()

Dim trdAnalysis() as Thread

Dim i,j as int16

J=5

Redim trdAnalysis(j)

For i = 0 To j

trdAnalysis(i) = New Thread(New ThreadStart (AddressOf subProcWeb))

trdAnalysis(i).SetApartmentState([login to view URL])

trdAnalysis(i).Name = "Thread" & i

trdAnalysis(i).IsBackground = True

trdAnalysis(i).Start()

[login to view URL](50)

Next i

End Sub

Private Sub subProcWeb()

Dim wbo As WebBrowser

Dim htmlDoc As HtmlDocument

Dim strHtm as string

Dim i, j as int32

J=1000

For i = 0 to j

strHtml =

wbo = new WebBrowser

[login to view URL] = strHtml

[login to view URL] = True

While Not [login to view URL] = [login to view URL]

[login to view URL]()

[login to view URL](1000)

End While

While [login to view URL] = True

[login to view URL]()

[login to view URL](1000)

End While

htmlDoc= [login to view URL]

... Processing follows...

[login to view URL]()

[login to view URL](100)

Next i

End Sub

Our Requirement is to check our web pages for a certain condition .

For this we read the HTML source of the page and assigin it to a webbrowser object.

Then check the parsed htmldocument.

Since analysising the HTML Document object was most suited for our need than using regular expression on the html source file.

Thanks

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