# 502错误

### php7.0+nginx+mysql+centos7.0

#### 排查步骤一： 查看nginx日志

* 若日志没有报什么错，一切正常，显然不是nginx出的问题；跳过此

```bash
# 1、 FastCGI进程是否已经启动
ps aux | grep php

# 2、 FastCGI worker进程数是否不够； 判断是否接近FastCGI进程，接近配置文件中设置的数值，表明worker进程数设置太少；
netstat -anpo | grep “php-cgi” | wc -l


# 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、 其它原因， CPU和内存爆满接近100%， 优化 || 升级配置
```

#### 排查步骤一： 查看php日志

nginx 502 Bad Gateway出现的原因：

> WARNING: \[pool www] server reached pm.max\_children setting (5), consider raising it 解决方法

```bash
# 设置子进程最大数值; 原是 5 个进程
pm.max_children = 30 
```

> php-fpm.conf 配置 性能优化 参数详解

```bash
[global]
pid = /usr/local/php/var/run/php-fpm.pid
error_log = /usr/ local/php/var/log/php-fpm.error.log
log_level = notice

[www]
listen = /tmp/php-cgi.sock
listen.backlog = -l
listen.allowed_clients = 127.o.o.1
listen.owner = www
listen.group = www
listen.mode = 0666
user = www
group = www
pm = dynamic               ; 或 pm = static 表示使用哪种进程数量管理方式
pm.max_children = 6        ; 静态方式下开启的php-fpm进程数量
pm.start_servers = 4       ; 动态方式下的起始php-fpm进程数量
pm.min_spare_servers = 4   ; 动态方式下的最小php-fpm进程数量
pm.max_spare_servers = 6   ; 动态方式下的最大php-fpm进程数量
request_terminate_timeout = 100
request_slowlog_timeout = 10s ;配置php慢日志时间
slowlog = var/log/slow.log    ;配置php慢日志文件
rlimit_files = 1024           ;配置php-fpm进程可打开的最大文件句柄数,默认1024
```

总结：内存小的建议用动态（pm = dynamic），内存大的建议用静态（pm = static）。


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