Shutdown issue

[mohdimas]

Hi guys,
I can't seems to call the Shutdown, I think this case is similar with this one #2.
So the problem is I can't close my app because when I called Shutdown the thread stuck there, and the app just continue running.

CefSharp/CefSharp.Core/Cef.h

Line 357 in 12f9c29

static void Shutdown()

[jornh]

I just found https://code.google.com/p/chromiumembedded/issues/detail?id=421 so if you are trying to implement #574 (comment) it looks unlikely it will work.

If you are just looking for a single shutdown at application exit have you made sure to dispose all ChromiumWebBrowser instances first (search the CefSharp WPF related code). #2 has a hint on some refcounting.

[mohdimas]

No this one is just to shutdown when exiting the app. Ok thanks I'll try it and see how it turns out.

[amaitland]

@myrnazhou Do you know what line it hands on? Does it enter into the lock?

[bjarteskogoy]

I had this problem on WPF + cef later than 1750. The problem was related to initlizing Cef on another thread than the Dispatcher. It got stuck when disposing.

[mohdimas]

@bjarteskogoy
So did you manage to get the shutdown working?

[bjarteskogoy]

@myrnazhou Yes. Had to initialize it in the Dispatcher thread. Fixed it for me.

[mohdimas]

I got this popup after I call the shutdown, I think it's related.

[Bodekaer]

I see the same popup as @myrnazhou when closing the application, and running CEF Shutdown.
It's happening randomly, and hard to reproduce.

@myrnazhou did you try @jornh's suggestion to first dispose all browsers before calling shutdown?

[amaitland]

@Bodekaer Has the issue occurred since you updated to the latest version of Cef 2171?

Possibly useful links

• http://stackoverflow.com/questions/99552/where-do-pure-virtual-function-call-crashes-come-from/100555#100555
• http://www.artima.com/cppsource/pure_virtual.html
• http://www.lenholgate.com/blog/2006/01/purecall.html

[Bodekaer]

Update:
I tried the suggestion from #2 to dispose all browsers and call GC.Collect() and it appears to have solved it!
Thanks a lot for the tips.

I believe the main cause was that we sometimes store browsers in memory without displaying them (for faster re-load times when displaying new browsers).
I simply added a script to dispose all those browsers before calling Shutdown().

Wonderful! :) This was one that's been worrying me for a while, and yet it was so easy to fix :) hehe

[amaitland]

@Bodekaer Excellent! Is it worth implementing the changes in CefSharp?

[Bodekaer]

Yeah I guess it would. Although I'm not so happy with my implementation yet, so wouldn't feel too good about putting it into CefSharp :)
Anyways, here is the simple quick solution:

 public class ChromiumWebBrowser

     private static readonly List<WebControl> _instances = new List<ChromiumWebBrowser>();

     public ChromiumWebBrowser(){
           _instances.Add(this);
     }

    protected override void Dispose(bool isdisposing)
    {
        _instances.Remove(this);
        base.Dispose(isdisposing);
    }

    public static void DisposeAllInstances()
    {
        // Loop through all instances and remove.
        while (_instances.Count > 0)
        {
            _instances[0].Dispose();
        }
    }

}

And then I just call ChromiumWebBrowser.DisposeAllInstances() before calling Cef.Shutdown().
I'm sure this can be done 100x better, just haven't had time to look more into it yet.
:)

[amaitland]

Interesting! I'm surprised that's nessicary. See
https://github.com/cefsharp/CefSharp/blob/cef/2171/CefSharp.Core/Cef.h#L330

Already does something very similar.

[Bodekaer]

Haha yes that is strange :)
Well it seems like it doesn't call the Dispose() here, which may be the cause, as we have certain event handlers that are unsubscribed in the Disposing(bool isDisposing) method of our extended ChromiumWebBrowser.

Could that be the reason?

[amaitland]

Well it seems like it doesn't call the Dispose() here, which may be the cause, as we have certain event handlers that are unsubscribed in the Disposing(bool isDisposing) method of our extended ChromiumWebBrowser

Quite possible, probably worth looking into 👍

[amaitland]

@Bodekaer Happy to close this?

[Bodekaer]

I actually just experienced this again yesterday.
It seems to still happen in very rare cases, but I think it's more related to cases where the JS execution somehow timed out, which seems to cause the dispose calls to freeze.

Let's close this issue though, as once I have a way to reproduce this other rare case, then I'll just open a new issue.
Since I've only experienced this new scenario once, it might also just be caused by something else and not be CefSharp related.

[amaitland]

Let's close this issue though, as once I have a way to reproduce this other rare case, then I'll just open a new issue.

Works for me 😄