Avoid error with “too many open files”. It happens when the Swoole master process spawned so many child processes that open so many files, that it stops working.

sudo nano /etc/systemd/system.conf

DefaultLimitNOFILE=16384:524288

Apply Changes:

sudo systemctl daemon-reexec

Or restart the server.

/etc/nginx/nginx.conf

events {
    worker_connections 4096;  # Increase from default 768
}

Sources:

https://www.howtogeek.com/805629/too-many-open-files-linux/

https://www.baeldung.com/linux/error-too-many-open-files (Old)