Environment.Exit() causes the application to hang

[jamespearce2006]

My WPF application catches unhandled dispatcher exceptions, notifies the user, logs the stack trace, then calls Environment.Exit() to shut the application down immediately.

Unfortunately, with CefSharp, calling Environment.Exit() causes the application to totally lockup. In fact, it locks up so badly that I cannot attach a debugger. Calling it with the debugger attached also causes Visual Studio to lock up.

The same issue affects the WpfExample.

Calling Environment.FailFast works, but unfortunately shows Microsoft's own exception dialog.
The only solution I can think of is to kill the current process, but this seems messy.

[amaitland]

Are you calling Cef.Shutdown()?

[jankurianski]

Hi James, there are a bunch of things for you to check and try here: #800 (comment)

Having used Environment.Exit() myself, I believe the answer is calling Shutdown() manually.

[jankurianski]

@amaitland Too quick 😄

[amaitland]

@jankurianski Yours is a more detailed answer 😄

[amaitland]

@jamespearce2006 Can you confirm which version your using?

The same issue affects the WpfExample.

Can you provide the updated example for demo purposes?

[jamespearce2006]

The problem with calling Cef.Shutdown is that the area of code that catches the unhandled exception is not one that should know about Cef, or Web browsers in general. In fact, I would say I shouldn't need to do any cleanup before calling Environment.Exit - I've already decided my app is in a bad state, and I want to quit as quickly as possible.

It's trivially easy to modify the CefSharp.Wpf.Example.
Modify BrowserTabViewModel.cs, and replace the line in the constructor thusly:

//HomeCommand = new DelegateCommand(() => AddressEditable = Address = CefExample.DefaultUrl);
HomeCommand = new DelegateCommand(() => Environment.Exit(-1));

Compile, and run, and click the "Home" button, and observe the app hang permanently.

James

[amaitland]

In fact, I would say I shouldn't need to do any cleanup before calling Environment.Exit - I've already decided my app is in a bad state, and I want to quit as quickly as possible.

Any how exactly do you expect Cef to shutdown gracefully if you don't tell it?

Calling Environment.Exit() is nasty, it's like killing off the process, the default exit handling CefSharp uses is bypassed. If you can use Application.Current.Shutdown();

[amaitland]

(We are spending our free time trying to help you, so a little less attitude would also go a long way).

[jamespearce2006]

Huh? No attitude here - just want to get it working... Apologies if my text is terse. The CefSharp project is great - I just want to make it better :-)

I completely agree that Environment.Exit isn't the way to gracefully shutdown my app. However...

When I call Environment.Exit, I don't particularly care if it shuts down gracefully - I just want to quit with maximum prejudice. My app is already in a bad place - I don't really know what state it's in, I just want to put it out of its misery.

Regardless, I would say blocking Environment.Exit from completing is probably not good form.

[amaitland]

Regardless, I would say blocking Environment.Exit from completing is probably not good form.

It's more complicated than just exiting your single application, there are sub processes that need to be notified.

If Cef.Initialize() is called, then at some stage Cef.Shutdown() must be called.

[rassilon]

In WinForms I used Application.Exit instead of Environment.Exit and that did the correct thing for simple test unhandled exceptions. Does WPF have something equivalent?

[jamespearce2006]

I understand there are other processes, but what happens if the main process crashes? Surely they clean themselves up at some point anyway... What I'm really attempting to do is something equivalent to an app crash without the annoying Microsoft "Looking for solutions..." dialog.

Calling Environment.Exit() does actually call Cef::Shutdown anyway, it seems. I see ParentProcessExitHandler in Cef.h getting called before my app hangs.

Calling Cef.Shutdown before Environment.Exit() does work in normal conditions, however from a DispatcherUnhandlerException handler, calling Cef.Shutdown throws a Corrupted State Exception, wierdly...

[amaitland]

Calling Cef.Shutdown before Environment.Exit() does work in normal conditions, however from a DispatcherUnhandlerException handler, calling Cef.Shutdown throws a Corrupted State Exception, wierdly...

In an attempt to cleanup unmanaged resources the Cef class keeps an instance of every active ChromiumWebBrowser, if there are instances still alive when Shutdown is called it will attempt to dispose them.