nginx 502 504

For when the stress test, 502 504 interface problems arise, modify conf

1.upstream 添加 keepalive 256;
        upstream streamonwxyd {
                zone zoneonfile 64k;
                server wxyd.site.crias.com:8081  max_fails=1 fail_timeout=3s;

                 keepalive 256;
        }
2.location ：添加
    proxy_set_header Connection "Keep-Alive";
    
        修改时间
  proxy_read_timeout 256s;

Following address, explain very detailed

https://xiezefan.me/2017/09/27/nginx-502-bug-trace/