502
1、查看nginx错误日志
tailf /data/log/nginx/error.log
2017/03/23 09:47:35 [error] 16154#0: *460 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 14.23.168.226, server: localhost, request: "GET /index.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "zjdan.com"
原因：php-fpm.conf里面设置了php-cgi进程最大执行时间为5秒，超过则终止并断开nginx
vim /data/server/php/etc/php-fpm.conf
request_terminate_timeout = 5
tailf /data/log/nginx/error.log
2017/03/28 18:21:32 [error] 28965#0: *544 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.9.206, server: weixin-develop.com, request: "GET /accept.php HTTP/1.1", upstream: "fastcgi://unix:/tmp/php-fcgi.sock:", host: "weixin-develop.com"
原因：php超过了最大的执行时间