Created attachment 138784 [details]
lsof on Firefox

(In reply to Michel Dänzer from comment #26)
> FWIW, I've never noticed such issues with the default limit of 1024. My main
> firefox process (which has been running for days, with lots of activity in a
> large number of tabs) currently has 222 open file descriptors, the helper
> processes less than 60 each.

I attach output of lsof runned against Firefox PIDs (even if it does not
describe exactly Firefox file descriptors).
If you have any suggestion about retrieving useful infos about file descriptors
used by Firefox, please let me know