[Galene] Re: Greedy Galene :) -- file descriptors

[Juliusz Chroboczek <jch@irif.fr>]

> Galene needs a relatively large number of file descriptors (and will
> complain in the log about the current, 13k, limit*.

Yes, we use a distinct socket for every WebRTC peer connection, plus one
for every WebSocket, and another bunch for NAT probing.  I'm planning to
reduce that at some point, but the functionality will remain optional
unless I can show it doesn't harm performance.

> Now I did notice that galene has a value check for 65k:
> 
> 	https://github.com/jech/galene/blob/c465157eb5e31405daf3f33b8456e8c89aa51430/galene.go#L110
> 
> What is the reason for this ? What is a `normal' number for say up to
> a 1000 users ?n

File descriptors are cheap (they cost a few hundred bytes each, including
the associated i-node).  The 1024 limit is a historical artefact, due to
limitations of the select system call on older BSD systems.

I recommend that you just set the limit to 64k and never think about it
again.  At worst, it will allow an attacker to use up a few tens of kB of
kernel memory.

-- Juliusz