參考地址   https://serverfault.com/questions/543999/nginx-errors-recv-failed-104-connection-reset-by-peer-while-reading-respon/544106

網站登入的時候今天突然報出nginx m502的錯誤 ，  平均請求3次就有一次這種情況 ，檢視錯誤日誌

2017/09/15 09:59:46 [error] 15644#0:
*112680 recv() failed (104: Connection reset by peer) while reading response header from upstream,
 client: 172.18.19.201, server: bmp-mgmt-liusen.dianhua.cn,
 request: "GET /System/Auth/validate.html?ticket=b3b0acbd91fb70c155dbf7d9e6e74729 HTTP/1.1",
 upstream: "fastcgi://127.0.0.1:9000", host: "bmp-mgmt-liusen.dianhua.cn",
 referrer: "http://bmp-mgmt-liusen.dianhua.cn/System/Auth/login.html?from=%2FHome%2FIndex%2Findex.html

.nginx 沒有收到請求

recv() failed 
    -> nginx failed

(104: Connection reset by peer) while reading response header from upstream, 
    -> no complete answer, or no answer at all
upstream: "fastcgi://127.0.0.1:9000", 
    -> who is he, who failed???

重啟  php-fpm 之後 就ok 了 ，後續繼續觀察