Separate instances of Firefox require separate profiles

[Walter Dnes]

  I finally figured out how to run separate instances of Firefox, as
***COMPLETELY SEPARATE PROCESSES***.  Namely, that you need ***A
SEPARATE PROFILE FOR EACH INSTANCE***.  Let's start with 2 profiles
"trusted" and "20140622".  From the command line, I execute the
following commands...

firefox -new-instance -P trusted &
firefox -new-instance -P 20140622 &
ps -ef | grep firefox
kill -3 2827
ps -ef | grep firefox

  You won't need the "&" if you launch from a desktop or window-manager
launcher.  Ignore the "g_slice_set_config: assertion" warning for now.
Here's the screen capture from xterm...

#######################################################################

[d531][waltdnes][~] firefox -new-instance -P trusted &
[2] 2827
[1]   Done                    firefox -new-instance
[d531][waltdnes][~]
(process:2827): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
firefox -new-instance -P 20140622 &
[3] 2860
[d531][waltdnes][~]
(process:2860): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
ps -ef | grep firefox
waltdnes  2827  2740  2 13:31 pts/7    00:00:00 firefox -new-instance -P trusted
waltdnes  2860  2740  6 13:31 pts/7    00:00:01 firefox -new-instance -P 20140622
waltdnes  2902  2740  0 13:32 pts/7    00:00:00 grep --color=auto firefox
[d531][waltdnes][~] kill -3 2827
[d531][waltdnes][~] ps -ef | grep firefox
waltdnes  2860  2740  0 13:31 pts/7    00:00:01 firefox -new-instance -P 20140622
waltdnes  2919  2740  0 13:33 pts/7    00:00:00 grep --color=auto firefox
[2]-  Quit                    firefox -new-instance -P trusted
#######################################################################

  In the above example, I launched 2 instances of Firefox, and verified
their existance by running "ps -ef | grep firefox".  Then I killed one
of the instances, and verified its killing, and that the other one was
still present, with "ps -ef | grep firefox".

  So if you have some sites that you visit regularly, you can have a
separate profile for each one.  This has some advantages...

1) You can have totally different customized setups (including different
add-ons) for each site.

2) Third-party cookies left by trackers when you're on site A using
profile A, will not be readable by the same third-party when you're on
site B, using profile B, making tracking you more difficult and less
reliable... one... two... three... aaaaawwwwwww.

3) If you have a whole bunch of websites open, and one of them crashes
Firefox, or hangs it so you need to kill it, you don't end up taking
down all your browsers.

-- 
Walter Dnes <waltdnes-SLHPyeZ9y/tg9hUCZPvPmw at public.gmane.org>
I don't run "desktop environments"; I run useful applications
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