maintainer-feedback requested: [Bug 260901] www/firefox dom.ipc.processCount 8 but maybe more than eight such processes

Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-gecko (Nobody)
<gecko@FreeBSD.org> for maintainer-feedback:
Bug 260901: www/firefox dom.ipc.processCount 8 but maybe more than eight such
processes
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=260901



--- Description ---
dom.ipc.processCount is 8 (the default) however, as far as I can tell:

* many more than eight such processes may become apparent 
  in e.g. htop(1)

* if excesses are not apparent at start time, after Firefox completes 
  its reopening of previous windows and tabs, then they may become 
  apparent when (for example) I begin to load tabs that were reopened

  -- maybe only if no favicon is apparent before the click to load.

about:support currently shows an isolated web content count: 

  13

– although I don't know whether this bears any relationship to
dom.ipc.processCount – and htop shows a number greater than 13 
for firefox processes matching: 

  -isForBrowser

At a glance, the number visible in htop _might_ equal the 
sum of the five types of remote process in about:support. 


Environment
===========

% pkg info -x firefox
firefox-95.0.2,2
% pkg -vv | grep -e url -e enabled
    url 	    : "http://pkg0.pkt.freebsd.org/FreeBSD:14:amd64/latest",
    enabled	    : yes,
    url 	    :
"https://alpha.pkgbase.live/current/FreeBSD:14:amd64/latest",
    enabled	    : no,
    url 	    : "file:///usr/local/poudriere/data/packages/main-default",
    enabled	    : yes,
% freebsd-version -kru
14.0-CURRENT
14.0-CURRENT
14.0-CURRENT
% uname -aKU
FreeBSD mowa219-gjp4-8570p-freebsd 14.0-CURRENT FreeBSD 14.0-CURRENT #118
main-n251923-4bae154fe8c: Sat Dec 25 08:03:37 GMT 2021	  
root@mowa219-gjp4-8570p-freebsd:/usr/obj/usr/src/amd64.amd64/sys/GENERIC-NODEBU
G
 amd64 1400045 1400045
% 


Early thoughts
==============

Ultimately: this might be not a bug, or a bug upstream. 

For now: after observing symptoms for a few days, my gut feeling is 
that the behaviours might be specific to the (Tier-3) port to FreeBSD. 

Certainly: with the port to FreeBSD, it's relatively easy (compared to 
e.g. Linux) to view the number of firefox processes with utilities 
such as htop. 

Qualitatively: sometimes I do feel that recommended performance settings are no
longer as effective as they were, say, a few weeks ago.