[Nginx] 博客园出现了502错误该怎么追查原因

博客园从今天上午就开始报502错误 , 他的原因还不知道 , 暂时先说下我们遇到502的排查情况

最大的可能性就是后端的服务不能支撑前端过来的tcp请求连接,包括连接数据库服务时的连接数问题

1. php-fpm的进程是否启动 ,没启动肯定报这个错误

2. tcp连接数超过了fpm的进程数

netstat -altupn|grep EST|grep php|wc -l

查看当前tcp连接 , 比较自己fpm的进程数

修改配置文件中的进程数部分:

/etc/php-fpm.d/www.conf 

; Note: This value is mandatory.
pm = dynamic

; The number of child processes to be created when pm is set to 'static' and the
; maximum number of child processes to be created when pm is set to 'dynamic'.
; This value sets the limit on the number of simultaneous requests that will be
; served. Equivalent to the ApacheMaxClients directive with mpm_prefork.
; Equivalent to the PHP_FCGI_CHILDREN environment variable in the original PHP
; CGI.
; Note: Used when pm is set to either 'static' or 'dynamic'
; Note: This value is mandatory.
pm.max_children = 200

; The number of child processes created on startup.
; Note: Used only when pm is set to 'dynamic'
; Default Value: min_spare_servers + (max_spare_servers - min_spare_servers) / 2
pm.start_servers = 30

; The desired minimum number of idle server processes.
; Note: Used only when pm is set to 'dynamic'
; Note: Mandatory when pm is set to 'dynamic'
pm.min_spare_servers = 10

; The desired maximum number of idle server processes.
; Note: Used only when pm is set to 'dynamic'
; Note: Mandatory when pm is set to 'dynamic'
pm.max_spare_servers = 50

3.FastCGI执行时间过长

根据实际情况调高以下参数值
fastcgi_connect_timeout 300;
fastcgi_send_timeout 300;
fastcgi_read_timeout 300;

4.FastCGI Buffer不够
nginx和apache一样，有前端缓冲限制，可以调整缓冲参数
fastcgi_buffer_size 32k;
fastcgi_buffers 8 32k;

5.Proxy Buffer不够
如果你用了Proxying，调整
proxy_buffer_size 16k;
proxy_buffers 4 16k;

代码中有连接数据库等的错误 , 导致执行时间过长了 , 检查代码等