Sample code sharing explained by php-fpm

Agree several directories

• /usr/local/php/sbin/php-fpm

• /usr/local/php/etc/php-fpm.conf

• /usr/local/php/etc/php.ini

1. Startup parameters of php-fpm

#测试php-fpm配置/usr/local/php/sbin/php-fpm -t
/usr/local/php/sbin/php-fpm -c 
/usr/local/php/etc/php.ini -y 
/usr/local/php/etc/php-fpm.conf -t
#启动
php-fpm/usr/local/php/sbin/php-fpm
/usr/local/php/sbin/php-fpm -c 
/usr/local/php/etc/php.ini -y 
/usr/local/php/etc/php-fpm.conf
#关闭
php-fpmkill -INT `cat 
/usr/local/php/var/run/php-fpm.pid`
#重启
php-fpmkill -USR2 `cat 
/usr/local/php/var/run/php-fpm.pid`

2. Detailed explanation of important parameters of php-fpm.conf

pid = run/php-fpm.pid
#pid设置，默认在安装目录中的var/run/php-fpm.pid，建议开启

error_log = log/php-fpm.log
#错误日志，默认在安装目录中的var/log/php-fpm.log

log_level = notice
#错误级别. 可用级别为: alert（必须立即处理）, error（错误情况）, warning（警告情况）, notice（一般重要信息）, debug（调试信息）. 默认: notice.

emergency_restart_threshold = 60
emergency_restart_interval = 60s
#表示在emergency_restart_interval所设值内出现SIGSEGV或者SIGBUS错误的php-cgi进程数如果超过 emergency_restart_threshold个，
php-fpm就会优雅重启。这两个选项一般保持默认值。

process_control_timeout = 0
#设置子进程接受主进程复用信号的超时时间. 可用单位: s(秒), m(分), h(小时), 或者 d(天) 默认单位: s(秒). 默认值: 0.

daemonize = yes
#后台执行fpm,默认值为yes，如果为了调试可以改为no。在FPM中，可以使用不同的设置来运行多个进程池。 这些设置可以针对每个进程池单独设置。

listen = 127.0.0.1:9000
#fpm监听端口，即nginx中php处理的地址，一般默认值即可。可用格式为: 'ip:port', 'port', '/path/to/unix/socket'. 每个进程池都需要设置.

listen.backlog = -1
#backlog数，-1表示无限制，由操作系统决定，此行注释掉就行。backlog含义参考：http://www.3gyou.cc/?p=41

listen.allowed_clients = 127.0.0.1
#允许访问FastCGI进程的IP，设置any为不限制IP，如果要设置其他主机的nginx也能访问这台FPM进程，listen处要设置成本地可被访问的IP。默认值是any。
每个地址是用逗号分隔. 如果没有设置或者为空，则允许任何服务器请求连接

listen.owner = www
listen.group = www
listen.mode = 0666
#unix socket设置选项，如果使用tcp方式访问，这里注释即可。

user = www
group = www
#启动进程的帐户和组

pm = dynamic #对于专用服务器，pm可以设置为static。
#如何控制子进程，选项有static和dynamic。如果选择static，则由pm.max_children指定固定的子进程数。如果选择dynamic，则由下开参数决定：
pm.max_children #，子进程最大数
pm.start_servers #，启动时的进程数
pm.min_spare_servers #，保证空闲进程数最小值，如果空闲进程小于此值，则创建新的子进程
pm.max_spare_servers #，保证空闲进程数最大值，如果空闲进程大于此值，此进行清理

pm.max_requests = 1000
#设置每个子进程重生之前服务的请求数. 对于可能存在内存泄漏的第三方模块来说是非常有用的. 
如果设置为 '0' 则一直接受请求. 等同于 PHP_FCGI_MAX_REQUESTS 环境变量. 默认值: 0.

pm.status_path = /status
#FPM状态页面的网址. 如果没有设置, 则无法访问状态页面. 默认值: none. munin监控会使用到

ping.path = /ping
#FPM监控页面的ping网址. 如果没有设置, 则无法访问ping页面. 该页面用于外部检测FPM是否存活并且可以响应请求. 请注意必须以斜线开头 (/)。

ping.response = pong
#用于定义ping请求的返回相应. 返回为 HTTP 200 的 text/plain 格式文本. 默认值: pong.

request_terminate_timeout = 0
#设置单个请求的超时中止时间. 该选项可能会对php.ini设置中的'max_execution_time'因为某些特殊原因没有中止运行的脚本有用. 

request_slowlog_timeout = 10s
#当一个请求该设置的超时时间后，就会将对应的PHP调用堆栈信息完整写入到慢日志中. 设置为 '0' 表示 'Off'

slowlog = log/$pool.log.slow
#慢请求的记录日志,配合request_slowlog_timeout使用

rlimit_files = 1024
#设置文件打开描述符的rlimit限制. 默认值: 系统定义值默认可打开句柄是1024，可使用 ulimit -n查看，ulimit -n 2048修改。

rlimit_core = 0
#设置核心rlimit最大限制值. 可用值: 'unlimited' 、0或者正整数. 默认值: 系统定义值.

chroot =
#启动时的Chroot目录. 所定义的目录需要是绝对路径. 如果没有设置, 则chroot不被使用.

chdir =
#设置启动目录，启动时会自动Chdir到该目录. 所定义的目录需要是绝对路径. 默认值: 当前目录，或者/目录（chroot时）

catch_workers_output = yes
#重定向运行过程中的stdout和stderr到主要的错误日志文件中. 如果没有设置, stdout 和 stderr 将会根据FastCGI的规则被重定向到 /dev/null . 默认值: 空.

3 ,Common errorsand solutions

1,Resource problems caused by request_terminate_timeout

If the value of request_terminate_timeout is set to 0 or too long , may cause resource problems with file_get_contents.

If the remote resource requested by file_get_contents responds too slowly, file_get_contents will always be stuck there without timing out. We know that max_execution_time in php.ini can set the maximum execution time of PHP scripts, but in php-cgi (php-fpm), this parameter will not take effect. What can really control the maximum execution time of PHP scripts is the request_terminate_timeout parameter in the php-fpm.conf configuration file.

The default value of request_terminate_timeout is 0 seconds, which means that the PHP script will continue to execute. In this way, when all php-cgi processes are stuck in file_get_contents() Function, this Nginx+PHP WebServer can no longer process new PHP requests, and Nginx will return "502 Bad Gateway" to the user. ". Modifying this parameter is necessary to set the maximum execution time of a PHP script, but it only treats the symptoms rather than the root cause. For example, if it is changed to 30s, if file_get_contents() is slow to obtain web page content, this means that 150 php-cgi processes can only handle 5 requests per second, and it is also difficult for WebServer to avoid "502 Bad Gateway".
The solution is to set request_terminate_timeout to 10s or a reasonable value, or add a timeout parameter to file_get_contents.

$ctx = stream_context_create(array(    
'http' => array(       
'timeout' => 10    
//设置一个超时时间，单位为秒
    )
));
file_get_contents($str, 0, $ctx);

2, Improper configuration of the max_requests parameter may cause intermittent 502 errors:

pm.max_requests = 1000

Set the number of requests served before each child process is reborn. For the first time that there may be a memory leak It is very useful for third-party modules. If set to '0', requests will always be accepted. Equivalent to the PHP_FCGI_MAX_REQUESTS environment variable. Default value: 0.
This configuration means that when a PHP-CGI process handles a request After the number accumulates to 500, the process will be automatically restarted.
But why do we need to restart the process?
Generally in projects, we will use some third-party libraries of PHP to some extent. These third-party libraries often have memory leak problems. If the PHP-CGI process is not restarted regularly, it will inevitably cause continuous memory usage. increase. Therefore, PHP-FPM, as the manager of PHP-CGI, provides such a monitoring function to restart the PHP-CGI process that has requested a specified number of times to ensure that the memory usage does not increase.

It is precisely because of this mechanism that 502 errors are often caused in highly concurrent sites. I guess the reason is that PHP-FPM does not handle the request queue coming from NGINX well. However, I am still using PHP 5.3.2. I don’t know if this problem still exists in PHP 5.3.3.

Our current solution is to set this value as large as possible to reduce the number of times PHP-CGI re-SPAWNs as much as possible, and at the same time improve overall performance. In our own actual production environment, we found that the memory leak was not obvious, so we set this value very large (204800). Everyone should set this value according to their actual situation and cannot blindly increase it.

Having said that, the purpose of this mechanism is only to ensure that PHP-CGI does not occupy excessive memory. Why not deal with it by detecting memory? I very much agree with what Gao Chunhui said, restarting the PHP-CGI process by setting the peak intrinsic usage of the process would be a better solution.

3, php-fpm's slow log, debug and exception troubleshooting artifact:
request_slowlog_timeout sets a timeout parameter, slowlog sets the storage location of the slow log

tail -f /var/log/www.slow.log

The above command can see the php process that is executed too slowly.
You can see the common problems of network reading exceeding and MySQLquerying being too slow. If you follow the prompt information to troubleshoot the problem, you will have a clear direction.

php-fpm 5.3+ How to shut down and restart?

php-fpm under php 5.3+ no longer supports commands such as /usr/local/php/sbin/php-fpm (start|stop|reload) that php-fpm previously had. You need to use Signal control:

The master process can understand the following signals

INT, TERM immediately terminate QUIT smoothly terminate USR1 reopen the log file USR2 smoothly reload all worker processes and reload configuration and binary modules

Example:

php-fpm Close:

kill -INT cat /usr/local/php/var/run/php-fpm.pid

php-fpm Restart:

kill -USR2 cat /usr/local/php/var/run/php-fpm.pid

Check the number of php-fpm processes:

ps aux | grep -c php-fpm

8. When executing php from the command line, it prompts that the command cannot be found

-bash: /usr/bin/php: No such file or directory

vi /etc/profile

Add a line of configuration at the bottom of the file
export PATH=/usr/local/php /bin:$PATH

Save and exit

source /etc/profile

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