GNOME 40 Will Now Handle XWayland On-Demand By Default

Back in 2019 support was added to GNOME 3.34 to allow starting XWayland on-demand. With this opt-in feature, XWayland support would only be started up when needed (on-demand) for running X11 clients. That support has now matured enough where for the upcoming GNOME 40 it will be enabled by default.

As of today in Mutter 40 is the enabling by default of the XWayland on-demand handling. This comes following a more robust check for helping to ensure X11 clients are no longer active prior to terminating XWayland. That plus other work now allows it to be enabled by default.

The latest code is deemed good enough to make XWayland on-demand by default so that XWayland will only be fired up when needed. But while the start-up will be on-demand, for terminating XWayland when clients are no longer active will be left up to an opt-in (experimental) feature... The "autoclose-xwayland" option will need to be enabled if you want XWayland to shutdown when it believes there are no longer any X11 clients active.

Red Hat's Olivier Fourdan who spearheaded the work explained of the autoclose-xwayland need, "Closing automatically Xwayland once all relevant X11 clients are gone is inherently racy, if a new client comes along right at the time we're killing Xwayland. Fixing the possible race conditions between mutter, Xwayland and the X11 clients may take some time."

GNOME 40 is shaping up to be a big release due out in March.