I'm not sure why server reached max_children very fast. About 2-5 mins after restart php-fmp My server: 4 vCPU, 8GB Ram

FPM log

[19-Mar-2020 11:01:11] WARNING: [pool www] child 6984, script '/home/forge/example.com/public/index.php' (request: "GET /index.php") execution timed out (72.300251 sec), terminating
[19-Mar-2020 11:01:11] WARNING: [pool www] child 6847, script '/home/forge/example.com/public/index.php' (request: "GET /index.php") execution timed out (60.922255 sec), terminating
[19-Mar-2020 11:01:11] WARNING: [pool www] child 6841, script '/home/forge/example.com/public/index.php' (request: "GET /index.php") execution timed out (78.432021 sec), terminating
[19-Mar-2020 11:01:11] WARNING: [pool www] child 6828, script '/home/forge/example.com/public/index.php' (request: "POST /index.php") execution timed out (71.056632 sec), terminating

FPM conf

pm = dynamic
pm.max_childrent = 120
pm.max_requests = 500
pm.max_spare_servers = 72
pm.min_spare_servers = 24

Nginx conf

location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/run/php/php7.4-fpm.sock;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_read_timeout 300;
        fastcgi_buffer_size 4k;
        fastcgi_buffers 32 4k;
    }