A detailed explanation of php-fpm optimization methods

php-fpm optimization method

There are two ways for php-fpm. One is to directly start the specified number of php-fpm processes without increasing or decreasing;
The other is to start A certain number of php-fpm processes are opened at any time. When the request volume becomes large, the number of php-fpm processes is dynamically increased to the upper limit. When idle, the number of idle processes is automatically released to a lower limit.
These two different execution methods can be adjusted according to the actual needs of the server.

Some parameters to be used are pm, pm.max_children, pm.start_servers, pm.min_spare_servers and pm.max_spare_servers.

pm indicates which method to use. There are two values ​​to choose from, namely static (static) or dynamic (dynamic).

The meanings of the following four parameters are:

pm.max_children: The number of php-fpm processes opened in static mode. In dynamic mode, it limits php- The maximum number of fpm processes (note here that the value of pm.max_spare_servers can only be less than or equal to pm.max_children)
pm.start_servers: The number of starting php-fpm processes in dynamic mode.
pm.min_spare_servers: The minimum number of php-fpm processes in idle state in dynamic mode.
pm.max_spare_servers: The maximum number of php-fpm processes in idle state in dynamic mode.

If dm is set to static, only the pm.max_children parameter will take effect. The system will open the set number of php-fpm processes.

If dm is set to dynamic, all four parameters will take effect. The system will start pm.start_servers php-fpm processes when php-fpm starts running, and then dynamically adjust the number of php-fpm processes between pm.min_spare_servers and pm.max_spare_servers according to the needs of the system.

So, which execution method is better for the server? In fact, like Apache, the running PHP program will more or less have memory leaks after execution. This is also the reason why a php-fpm process only occupies about 3M of memory at the beginning, and it will increase to 20-30M after running for a period of time. (www. Script School)

Therefore, because the dynamic method will end redundant processes and can recycle and release some memory, it is recommended to be used on servers or VPS with less memory. The specific maximum amount is obtained based on memory/20M.
For example, for a 512M VPS, it is recommended that pm.max_spare_servers be set to 20 (512*0.8/20). As for pm.min_spare_servers, it is recommended to set it according to the load of the server. A more suitable value is between 5 and 10.

And for servers with relatively large memory, setting it to static will improve efficiency.
Because frequent switching of the php-fpm process will cause lag, so if the memory is large enough, the static effect will be better. The quantity can also be obtained according to memory/30M.
For example, a server with 2GB memory can be set to 50; a server with 4GB memory can be set to 100, etc.

For example, if it is a 512M vps, the set parameters are as follows:

Code example:

pm=dynamic
pm.max_children=20
pm.start_servers=5
pm.min_spare_servers=5
pm.max_spare_servers=20

can save memory and improve execution efficiency to the greatest extent.

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