The server has 4 cores and 8G memory, cpu (30-50%), memory (40-50%). 502 appears several times every day.
Checked netstat -anpo | grep "php-cgi" | wc -l
is 3

The following is the content of my /usr/local/php/etc/php-fpm.conf

[global] pid = /usr/local/php/var/run/php-fpm.pid error_log = /data/logs/php-fpm-error.log log_level = notice [www] listen = /tmp/php-cgi.sock listen.backlog = -1 listen.allowed_clients = 127.0.0.1 listen.owner = www listen.group = www listen.mode = 0777 user = www group = www pm = dynamic pm.max_children = 400 pm.start_servers = 80 pm.min_spare_servers = 40 pm.max_spare_servers = 240 request_terminate_timeout = 100 request_slowlog_timeout = 3 slowlog = /data/logs/php_slow.log

nginx error There are many
fastcgi request record is too big errors in the log. What is the reason?

Please help my friends on how to deal with my 502 problem, thank you!