onRenderProcessGone(WebView view, RenderProcessGoneDetail detail) example

Question

Below I posted my current onRenderProcessGone.

1. In the if (!detail.didCrash()) {} the instance variable "view" is guaranteed to be null, it's safe to reinitialize it. Should I myself reinitialize it or system will do it?

2. Could you specify the example of logic for how the app can continue executing? How to handle the crash more gracefully?

       @TargetApi(Build.VERSION_CODES.O)
       @Override
       public boolean onRenderProcessGone(WebView view, RenderProcessGoneDetail detail) {
           // WebViewClient.onRenderProcessGone was added in O.
           if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
               return false;
           }
           super.onRenderProcessGone(view, detail);
   
           if (!detail.didCrash()) {
               // Renderer was killed because the system ran out of memory.
               // The app can recover gracefully by creating a new WebView instance
               // in the foreground.
               Log.e("MY_APP", "System killed the WebView rendering process " +
                       "to reclaim memory. Recreating...");
   
               if (view != null) {
                   ((ViewGroup)view.getParent()).removeView(view);
                   view.destroy();
                   view = null;
               }
   
               // By this point, the instance variable "view" is guaranteed
               // to be null, so it's safe to reinitialize it.
   
               return true; // The app continues executing.
           }
   
           // Renderer crashed because of an internal error, such as a memory
           // access violation.
           Log.e("MY_APP", "The WebView rendering process crashed!");
   
           // In this example, the app itself crashes after detecting that the
           // renderer crashed. If you choose to handle the crash more gracefully
           // and allow your app to continue executing, you should 1) destroy the
           // current WebView instance, 2) specify logic for how the app can
           // continue executing, and 3) return "true" instead.
           return false;
       }
   

Answer 1

I have implemented this method and do not make a distinction between the renderer crashing or being killed by the system. As far as the app is concerned the result is the same - the webview is unusable, and if this method returns false the app will also be killed.

I maintain a reference to the WebView and two the layout root view in the Fragment (or Activity) that is initialised during the Fragment/Activity creation.

        m_homeWebSwipe = v.findViewById(R.id.homeWebViewSwipe);
        m_homeWebView = v.findViewById(R.id.homeWebView);
        initializeWebView(m_homeWebView);

My WebView is the child of a SwipeRefreshLayout. The layout XML is not critical, but for reference it is:

<?xml version="1.0" encoding="utf-8"?>
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/homeWebViewSwipe"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <WebView
        android:id="@+id/homeWebView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </WebView>
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

The key here is the WebView is contained in a Layout container at the root of the view.

On receiving the onRenderProcessGone event, the goal is to recreate a functional view containing a new WebView (which will have a new renderer process associated with it).

            @Override
            public boolean onRenderProcessGone(final WebView view, RenderProcessGoneDetail detail) {
                // Renderer was killed or died, recreate the webview
                Log.e("HomeWebView", "web content rendering process killed - resetting WebView: " + view.hashCode());

                // Only handle our WebView
                if (m_homeWebView.equals(view)) {
                    // Get the parent container of the inflated layout
                    ViewGroup container = (ViewGroup) m_homeWebSwipe.getParent();
                    ViewGroup.LayoutParams params = container.getLayoutParams();
                    // Remove the inflated view from the container and cleanup
                    // the dead webview specifically (if it is not GC'ed it will cause
                    // problems later, the next time the renderer dies)
                    container.removeView(m_homeWebSwipe);
                    m_homeWebSwipe = null;
                    m_homeWebView = null;
                    view.destroy();
                    // Reinflate the view layout and add it back into the container
                    View v = getLayoutInflater().inflate(R.layout.home_webview_screen, container, false);
                    m_homeWebSwipe = v.findViewById(R.id.homeWebViewSwipe);
                    m_homeWebView = v.findViewById(R.id.homeWebView);
                    // Initialise webview here, same as when it was originally created                    
                    initializeWebView(m_homeWebView);
                    assert(getActivity() != null);
                    getActivity().setContentView(v, params);
                    // reload the displayed page, or load a new page here
                    reloadPage();
                    return true; // The app continues executing.
                }
                return false; // the app is killed
            }

You can test the code in the onRenderProcessGone method by arranging for the WebView to load the URL chrome://crash