[php-src] Issue #14911: php-fpm process: SQLSTATE[HY000] [2002] Connection timed out with database

Issue: https://github.com/php/php-src/issues/14911 Author: thanhtc-kozocom ### Description I have a problem with upgrading a server from Centos to Ubuntu (both use Nginx, php, laravel application) ### OS version: - Centos: CentOS Linux release 7.9.2009 (Core) - Ubuntu: Ubuntu 22.04.4 LTS ### Nginx version: - Centos: nginx/1.20.1 - Ubuntu: nginx/1.18.0 (Ubuntu) ### PHP version: - Centos: PHP 8.1.29 (cli) - Ubuntu: PHP 8.1.29 (cli) ### php-fpm config is the same for both servers, command check php-fpm8.1 -tt ``` pm = dynamic pm.max_children = 500 pm.start_servers = 50 pm.min_spare_servers = 50 pm.max_spare_servers = 350 pm.max_spawn_rate = 32 pm.process_idle_timeout = 10 pm.max_requests = 0 ``` When the number of requests is large, the Centos server will operate normally, but the Ubuntu server will have some requests with connection timeout errors as follows: ``` SQLSTATE[HY000] [2002] Connection timed out {"exception":"[object] (PDOException(code: 2002): SQLSTATE[HY000] [2002] Connection timed out at /vendor/laravel/framework/src/Illuminate/Database /Connectors/Connector.php:70) ``` Could you please share more knowledge about this issue? Thank you 🙇 ### PHP Version PHP 8.1.29 ### Operating System Ubuntu 22.04.4 LTS