Is php dynamic or static?

The number of processes of php-fpm can be divided into dynamic and static according to the settings.

Static: Start the specified number of php-fpm processes directly without increasing or decreasing; (Recommended learning: PHP video tutorial)

Dynamic: Start a certain number of php-fpm processes at the beginning. When the request becomes larger, dynamically increase the number of php-fpm processes to the upper limit, and automatically release the number of idle processes when they are idle. a lower limit.

These two different execution methods can be adjusted according to the actual needs of the server.

Here are the parameters involved in this. They are

pm\pm.max_children\pm.start_servers\pm.min_spare_servers和pm.max_spare_servers。

pm indicates which method to use. There are two values ​​to choose from, which is static Static or dynamic. In older versions, dynamic is also called apache-like. Please pay attention to the instructions given in the configuration file.

The meaning of the following four parameters are:

#php-fpm process number opened in static mode of pm.max_children;

pm.start_serversThe starting number of php-fpm processes in dynamic mode

The minimum number of php-fpm processes in pm.min_spare_servers dynamic mode;

pm.max_spare_serversDynamic mode The maximum number of php-fpm processes.

If dm is set to static, then 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, the pm.max_children parameter will be invalid, and the next three 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 system requirements.

So, which execution method is better for our server?

The fact is that like Apache, the PHP program we run 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 will increase to 20 to 30M after running for a period of time. Therefore, the dynamic method will end redundant processes and can recycle and release some memory, so it is recommended to be used on servers with less memory.

The specific maximum number is obtained by dividing the total physical memory size by 20M. For example, for a 512M VPS, it is recommended that the pm.max_spare_servers value be set to 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.

For servers with larger 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 number can be obtained by dividing the total physical memory size by 30M. For example, a server with 2GB memory can be set to 50; a server with 4GB memory can be set to 100, etc.

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