CefRequestContext leaks

[lavv17]

Hello!

I have a problem with memory leak, if I create CefRequestContext like this:

Code: Select all

context = CefRequestContext::CreateContext( CefRequestContext::GetGlobalContext(), handler );


I use the context for creating a browser. The problem is that the handler is never released until CefShutdown(), even when the browser is destroyed (OnBeforeClose is called normally).

[ndesktop]

I'm using a sequence like:
(initialization)

Code: Select all

CefRefPtr<CefRequestContext> m_SharedRequestContext; // declaration

// browser creation: m_Handler is my implementation of client handler class, called ClientHandler
void MainWindow::CreateBrowser()
{
...
   return CefBrowserHost::CreateBrowser(
        info,
        static_cast<CefRefPtr<CefClient>>(m_Handler),
        url,
        settings,
        GetRequestContext(m_Handler.get()) // <== GetRequestContext
    );
}

CefRefPtr<CefRequestContext> MainWindow::GetRequestContext(ClientHandler* client_handler)
{
    DCHECK(CefCurrentlyOn(TID_UI));
    return client_handler->GetRequestContext(client_handler);
}

...

CefRefPtr<CefRequestContext> ClientHandler::GetRequestContext(ClientHandler* client_handler)
{
...
    if(m_SharedRequestContext.get() == nullptr)
    {
        m_SharedRequestContext =
            CefRequestContext::CreateContext(
                CefRequestContext::GetGlobalContext(),
                new ClientRequestContextHandler(this)
            );
    }
    DCHECK(m_SharedRequestContext.get());
    return m_SharedRequestContext;
}


Obviously, I am using a shared context among all browser.

The cleanup is done when a WM_CLOSE is posted to my main window class (my app is a single main window with multiple tabs)

It looks something like this:

Code: Select all

BOOL MainWindow::_DoClose()
{
...
        //  signal handler as closing
        m_ClientHandler->setClosing(true);
...
}

void ClientHandler::setClosing(bool v)
{
    ...
    m_SharedRequestContext = nullptr;
}


ClientHandler::setClosing place m_SharedRequestContext on nullptr and thus releasing the shared context.

[lavv17]

In my case I need a separate CefRequestContext for separate CefCookieManager for each window, thus I have to create a new helper each time and it does not get reseased

[ndesktop]

Then perhaps store the contexts in a map[browserID]=CefRefPtr<context> and release them all in the same manner.
When a browser is released (ClientHandler::DoClose(CefRefPtr<CefBrowser> browser)) remove the context from the map.

[lavv17]

I don't hold any reference to the context at all, and yet it is not released along with the browser.

[lavv17]

Here is the place in code which prevents the handler release:
https://bitbucket.org/chromiumembedded/ ... mpl.cc-653
So it is released only when the global context is destroyed.

[ndesktop]

Then maybe this is by design? Is there a DCHECK, DebugObjCt or whatever which appears on shutdown?
Does the cefclient shows the same issue?

[Czarek]

Related issue? https://bitbucket.org/chromiumembedded/ ... rom-global

The solution is to keep the object until browser is destroyed and call object.Release() manually. This way you can force to release reference acquired by other code. Check that there is only one reference count by calling object.HasOneRef() to make sure that the object will be destroyed.

[lavv17]

Won't it crash after Release() if there is a reference left somewhere in the global context?

[Czarek]

The CEF code usually checks if reference pointers hold actual objects by calling refptr.get(), but you won't know until you test it.