Comparison of PHP-FPM and Swoole

I saw a few articles about swoole a few days ago, and I’m here to join in the fun today. My level is limited and my understanding of details may not be in place. I welcome everyone to help me add and correct.

PHP-FPM

Early versions of PHP did not have a built-in WEB server, but provided SAPI (Server API) for third-party connection. The now very popular php-fpm handles the communication between PHP and third-party WEB servers through the FastCGI protocol. For example, the combination of Nginx php-fpm, fpm running in this way is Master/Worker mode, starting a Master process to monitor requests from Nginx, and then forking multiple Worker processes to handle the requests. Each Worker process can only handle one request. The life cycle of a single process is roughly as follows:

1. Initialization module.

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

3. Execute PHP script.

4. End the request.

5. Close the module.

The multi-process model relies on the number of processes to solve concurrency problems. One process can only handle one connection. When a large number of processes are started, process scheduling consumption may account for dozens or even 100% of the CPU, such as the C10K problem. , the multi-process model is insufficient.

Swoole

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 Socket handles. changes in events. 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:

1. Initialize the module.

2. 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.

3. 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

● Reactor (epoll’s IO reuse method) is responsible for monitoring event changes of Socket handles to solve high concurrency problems.

● Save time on 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 will require re-initialization 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 , initialize 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.

The above is mainly for comparison of core operating machines. The differences listed are just these points that come to mind for the time being. If there are any missed points, please feel free to help me add them~

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