[webkit-gtk] Memory leaks creating and removing webviews

Carlos Garcia Campos cgarcia at igalia.com
Wed Jun 12 23:51:08 PDT 2013

El mié, 12-06-2013 a las 14:49 -0400, Josh Rickmar escribió:
> This issue may have already been beaten to death, but I am seeing
> pretty bad memory leaks when creating, showing and, and then deleting
> WebKitWebView widgets.  I've written and attached a very small test
> browser that will open tabs to Google's homepage, with a button on
> each tab to remove the tab and free everything in that notebook's
> page's container.  From what I can observe with top, I lose roughly 3
> MB per each tab open and close.
> From what I can tell based on the GTK and WebKitGtk docs, I am
> managing all the memory correctly even with this small test browser.
> If I am doing anything incorrect that may help with the leaks, please
> let me know.  Otherwise, what parts of the Webkit or WebKitGtk code
> should be examined first for leaks?

> void
> new_tab(GtkNotebook *nb)
> {
>         GtkWidget       *b;
>         GtkWidget       *close_btn;
>         GtkWidget       *wv;
>         close_btn_args  *args;
>         wv = webkit_web_view_new();
>         webkit_web_view_load_uri(WEBKIT_WEB_VIEW(wv),
>             "https://www.google.com/");
>         g_object_ref_sink(G_OBJECT(wv));

This is wrong, and it's leaking the view. GtkWidgets are created with a
floating reference that is consumed by the container widget when it's
added to a container. In this case here you are converting the floating
reference into a hard reference, the ref counter is 1. When the view is
added to the GtkNotebook, ref_sink is called again, but when ref_sink is
called on a GObject with a hard reference, it's reference counter is
increased, so it will be 2. When the tab is destroyed the notebook page
releases its reference, but the web view still has 1 and it's not

>         close_btn = gtk_button_new();
>         gtk_button_set_image(GTK_BUTTON(close_btn),
> gtk_image_new_from_stock
>         args = g_malloc0(sizeof *args);
>         args->nb = nb;
>         args->child = wv;
>         g_signal_connect(close_btn, "clicked",
> G_CALLBACK(close_btn_cb), args);
>         b = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, 1);
>         gtk_box_pack_start(GTK_BOX(b), close_btn, FALSE, FALSE, 0);
>         gtk_box_pack_start(GTK_BOX(b), gtk_label_new("Tab Label"),
>             FALSE, 0);
>         gtk_widget_show_all(b);
>         gtk_notebook_append_page(nb, wv, b);
>         gtk_widget_show_all(GTK_WIDGET(nb));
> }

Carlos Garcia Campos
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