The difference between fpm and swoole

PHP-FPM

Early versions of PHP did not have a built-in WEB server, but provided SAPI (Server API) Connect with third parties. The now very popular php-fpm handles the communication between PHP and third-party WEB servers through the FastCGI protocol. (Recommended learning: swoole video tutorial)

For example, the combination of Nginx php-fpm. The fpm running in this way is Master/Worker mode, and a Master process is started to listen from Nginx request, and then fork multiple Worker processes to handle the request. Each Worker process can only handle one request. The life cycle of a single process is roughly as follows:

Initialization module.

Initialization request. The request here means requesting PHP to execute code, not an HTTP request.

Execute PHP script.

End the request.

Close the module.

Swoole also adopts the Master/Worker mode. The difference is that the Master process has multiple Reactor threads. The Master is just an event generator, responsible for monitoring event changes in the Socket handle. Worker runs in a multi-process manner, receives requests from Reactor threads, and executes callback functions (written in PHP). The process of starting the Master process is roughly:

Initialization module.

Initialization request. Because swoole needs to be run through the cli, PHP's global variables, such as $_SERVER, $_POST, $_GET, etc., will not be initialized when the request is initialized.

Execute PHP script. Including lexical and syntactic analysis, initialization of variables, functions, classes, etc., the Master enters the listening state and will not end the process.

The principle of Swoole acceleration

The Reactor (epoll's IO reuse method) is responsible for monitoring the event changes of the Socket handle and solving high concurrency problems.

Save the time of PHP code initialization through memory resident. When using bulky frameworks, the acceleration effect of using swoole is very obvious.

Compare the differences

PHP-FPM

Master main process / Worker multi-process mode.

Start the Master and listen for requests transmitted from Nginx through the FastCGI protocol.

Each Worker process corresponds to only one connection, which is used to execute complete PHP code.

After the PHP code is executed, all the memory occupied will be destroyed, and the next request needs to be re-initialized and other tedious operations.

Only for HTTP Server.

Swoole

Master main process (composed of multiple Reactor threads)/Worker multi-process (or multi-thread) mode

Start Master, initializes the PHP code, and the Reactor monitors the event changes of the Socket handle.

The main thread of Reactor is responsible for the balancing of multi-threads, and the Manager process manages multiple Worker processes, including TaskWorker processes.

Each Worker accepts requests from Reactor and only needs to execute the PHP code in the callback function part.

The PHP initialization code is only executed once when the Master starts. The Master enters the listening state and does not end the process.

It can not only be used for HTTP Server, but also can establish TCP connection and WebSocket connection.

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