Internal server error when many request, nginx + node.js + pm2 [duplicate] - node.js

Question

I've a loadbalancer and I get this kind errors:
2017/09/12 11:18:38 [crit] 22348#22348: accept4() failed (24: Too many open files)
2017/09/12 11:18:38 [alert] 22348#22348: *4288962 socket() failed (24: Too many open files) while connecting to upstream, client: x.x.x.x, server: example.com, request: "GET /xxx.jpg HTTP/1.1", upstream: "http://y.y.y.y:80/xxx.jpg", host: "example.com", referrer: "https://example.com/some-page"
2017/09/12 11:18:38 [crit] 22348#22348: *4288962 open() "/usr/local/nginx/html/50x.html" failed (24: Too many open files), client: x.x.x.x, server: example.com, request: "GET /xxx.jpg HTTP/1.1", upstream: "http://y.y.y.y:80/xxx.jpg", host: "example.com", referrer: "https://example.com/some-page"
nginx version: nginx/1.10.1
Os: Debian GNU/Linux 8 (jessie)
The interesting thing is not always get error. Mostly I get a 30-50 lines of errors then nothing in 5-10 minutes. And then once the errors are coming again...
Here is my nginx.conf:
user www-data;
pid /usr/local/nginx/nginx.pid;
worker_processes auto;
error_log /var/log/nginx/error.log;
events {
worker_connections 30000;
}
http {
include mime.types;
default_type application/octet-stream;
fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;
proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;
client_max_body_size 500m;
rewrite_log on;
log_format main '$remote_addr - "$proxy_add_x_forwarded_for" - [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$backend" '
'rt=$request_time uct="$upstream_connect_time" '
'uht="$upstream_header_time" urt="$upstream_response_time"';
access_log /var/log/nginx/access.log main;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
geoip_country /etc/nginx/geodb/GeoIP.dat;
geoip_city /etc/nginx/geodb/GeoLiteCity.dat;
include /etc/nginx/loadbalancer/loadbalancer.conf;
}
And also some info:
$ ulimit -Hn
65536
$ ulimit -Sn
65536
$ sysctl fs.file-nr
fs.file-nr = 2848 0 70000
I don't know if it is worth but this loadbalancer is behind cloudflare.

Answer 1

I've added the following line to the nginx.conf:
worker_rlimit_nofile 20000;
Now it works, I don't get any error since the modification.
I hope it will help someone if have the same problem.