Why is this code consuming more and more ram?

Question

public partial class Form1 : Form
{
    bool AfterDocumentCompleted = false;
    int steps = 0;

    public Form1()
    {
        InitializeComponent();
        webBrowser1.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(DocCompletedHandlerCopy);
        webBrowser1.ScriptErrorsSuppressed = true;
    }

    private void DocCompletedHandlerCopy(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        if (webBrowser1.ReadyState == WebBrowserReadyState.Complete && e.Url == webBrowser1.Url)
        {
            AfterDocumentCompleted = true;
        }
    }

    private void NavigateAndWait(string urlString)
    {
        AfterDocumentCompleted = false;
        webBrowser1.Navigate(urlString);
        while (AfterDocumentCompleted == false) Application.DoEvents();

        steps += 1;
        label1.Text = string.Format("{0:00000} / {1}MB", steps, Environment.WorkingSet / (1024 * 1024));
    }

    private void button1_Click(object sender, EventArgs e)
    {
        while (true)
        {
            NavigateAndWait("http://www.crucial.com/");
            NavigateAndWait("http://www.google.com/");
            NavigateAndWait("http://www.microsoft.com/");
            NavigateAndWait("http://www.stackoverflow.com/");
            NavigateAndWait("http://www.yahoo.com/");
        }
    }
}

When I click Button1 (so it calls button1_Click) and wait for about 1 hr, the ram consumed according to Task Manager and label1 is about 1000MB (is about 20MB as soon as I click it and the rate of grow is somewhat linear). Is the WebBrowser some kind of alpha version of a browser that is not supposed to be used at all by anyone, or am I doing something wrong. If you wonder why in the world do I want to navigate for ever to those pages, this is just the isolation of a problem I was having (see my other question here).

Edit: About a week ago I installed and uninstalled IE9 beta. I think that might have originated the problem. Just tested it on a Windows Vista IE8 and it didn't grow any bigger than 80-90MB. I'll just reinstall Windows and I hope I don't need to downgrade to Windows Vista.

Edit2: I finally found the cause of the problem. It was not IE9 beta. It was the fact that I set IE not to show any pictures. I thought not showing pictures would make navigation faster and lighter, but apparently it activated some bug and the memory consumed started growing like crazy. Still, with pictures the memory grows but a lot slower.

Answer 1

or am I doing something wrong

Well, this is not going to be a good idea:

while (AfterDocumentCompleted == false) Application.DoEvents();

You're introducing reentrancy and a tight loop in the high priority UI thread. I don't know to what extent that will hamper the garbage collector, but I wouldn't be surprised if it did. Basically you're abusing the UI thread, which is bound to cause oddities. (As Henk says, 200MB in 10 minutes isn't exactly a runaway resource leak anyway.)

This just isn't a good idea. "Isolating" a problem by adding code like this isn't going to help.

You already have a DocumentCompleted handler... why not use that to navigate to the next page, instead of this tight loop?

Answer 2

I'm not sure why it would be unclear why you are using lots of memory; you are reloading web pages over and over again endlessly. Right now my browser is using 140megs of memory, and I'm not reloading pages constantly.

Answer 3

and wait for about 10 minutes, the ram consumed according to Task Manager is about 200MB

• 200 MB is not a lot
• TaskManager is not suitable for measuring memory use

The WebBrowser you use through the control is IE. It will consume quite a bit of memory, mostly to cache content. But you don't really have a problem with memory.

Additional:

I ran your App and changed only this method (add Label1) :

    int counter = 0;

    private void NavigateAndWait(string urlString)
    {
        AfterDocumentCompleted = false;
        webBrowser1.Navigate(urlString);
        while (AfterDocumentCompleted == false) Application.DoEvents();

        counter += 1;
        label1.Text = string.Format("{0:000} {1}", counter, 
           Environment.WorkingSet/ (1024*1024));
    }

When I let it run for a while Memory stabilizes at a 75-85 MB range.

In a comment you mention 1.6 GB, that is a problem. But that was not with this code. So you have a start: look for the differences.

Edit 2

Upgrade your version of IE. I am running this with Vista/32 and IE8 and the WorkingSet won't go over 90MB. (600 pages)