[arp242]

To be honest, that seems a lot. Even today a lot of code is single-threaded, and this performance hit will also affect a lot of code running in parallel today.

There have been patches to remove the GIL going back to the 90s and Python 1.5 or thereabouts. But the performance impact has always been the show-stopper.

[ngoldbaum]

It’s an experimental release in 3.13. Another example: objects that will have deffered reference counts in 3.14 are made immortal in 3.13 to avoid scaling issues from reference count thrashing. This wasn’t originally the plan but deferred reference counting didn’t land in time for 3.13. It will be several years before free-threading becomes the default, at that point there will no longer be any single-threaded performance drop. Of course that assumes everything shakes out as planned, we’ll see.

This post is a call to ask people to “kick the tires”, experiment, and report issues they run into, not announcing that all work is done.