worker_connections are not enough, reusing connections with idle workers

[Sergey A. Osokin]

On Tue, Jun 07, 2022 at 01:18:36PM -0700, Roger Fischer wrote:
> 
> We are simulating 1000 clients. Some get cache hits, and some go upstream. So there are more than 1000 connections.
> 
> We have 24 workers running, each configured: events { worker_connections  1024; }
> 
> We are seeing the following errors from nginx:
> [warn] 21151#21151: 1024 worker_connections are not enough, reusing connections
> [crit] 21151#21151: accept4() failed (24: Too many open files)
> [alert] 21151#21151: *15716 socket() failed (24: Too many open files) while connecting to upstream,
> 
> I am assuming the second and third error are for the OS limit. But the first seems to be from a worker process.

That looks like OS or user account limits, so could you share an
output of the followoing commands:

% uname -a
% cat /etc/*release
% ulimit -Hn
% ulimit -Sn
% cat /proc/sys/fs/file-max

Also, it's possible to increase nginx limits with the worker_rlimit_nofile
directive, http://nginx.org/ru/docs/ngx_core_module.html#worker_rlimit_nofile

Thank you.

--
Sergey A. Osokin