Another data point: The affected FF process has two defunct "Socket
Process"es,
the working FF-esr doesn't.
594571 ? Sl 14:00 \_ /usr/bin/firefox.real
-ProfileManager
594630 ? Z 0:00 | \_ [Socket Process] <defunct>
594753 ? Z 0:00 | \_ [Socket Process] <defunct>
Probably related, every now and then a tab (any URLs) hangs on loading
with a spinning symbol in the tab; copying the URL to another tab
doesn't help, unless the hanging tab gets closed, then the new tab
loads.
So I guess some thread hangs in the background - and so doesn't return
random numbers nor collects the child processes.
I can't make "rr" work to find out why;
"gdb" also has problems, I guess because of the large number of symbols.
Any ideas how to debug this are welcome!
