> 183605:1 futex(0x7f17981e79d0, FUTEX_WAIT, 271, NULL <unfinished ...>
I think this is caused by a "pthread_join", most probably the one in "stop_finalization_thread" that is called right before forking a new process. The fact that we hang here probably means that the finalizer thread itself is hanging, not sure why. It looks like what was reported by Ludo here: https://issues.guix.info/31925. Thanks, Mathieu