Re: counting file descriptors with a cgroup controller

[Tejun Heo]

Hello,

On Fri, Feb 17, 2017 at 12:37:11PM +0100, Krzysztof Opasiak wrote:
> > We need to limit and monitor the number of file descriptors processes
> > keep open. If a process exceeds certain limit we'd like to terminate it
> > and restart it or reboot the whole system. Currently the RLIMIT API
> > allows limiting the number of file descriptors but to achieve our goals
> > we'd need to make sure all programmes we run handle EMFILE errno
> > properly. That is why we consider developing a cgroup controller that
> > limits the number of open file descriptors of its members (similar to
> >  memory controler).
> > 
> > Any comments? Is there any alternative that:
> > 
> > + does not require modifications of user-land code,
> > + enables other process (e.g. init) to be notified and apply policy.

Hmm... I'm not quite sure fds qualify as an independent system-wide
resource.  We did that for pids because pids are globally limited and
can run out way earlier than memory backing it.  I don't think we have
similar restructions for fds, do we?

Thanks.

-- 
tejun