Connection overflow

[alexvanin]

It seems that neofs-node v0.22.2 does not reuse existing connections and creates new one on each request. At one time there is no enough ulimit to open new connection and we see errors like in #676.

Here the example from one of our storage nodes couple hours after restart.

# ls -l /proc/9758/fd | grep socket  | wc -l
568
# lsof -i -a -p 9758 | grep 199.247.0.222 | wc -l
199

I guess we need to look at client cache. Probably it is related to group address support.

[alexvanin]

How to debug it in neofs-dev-env.

1. Find pid of the storage node

$ docker inspect -f '{{.State.Pid}}' s01
788785

2. See open connections in lsof, e.g.

sudo nsenter -t 788785 -n lsof -i -a -p 788785 2>&1 | grep -- '->s0'