Swoole Advanced: How to use multi-process to improve PHP processing capabilities

With the development of the Internet, the requirements for Web application performance and concurrent processing capabilities are becoming higher and higher. For PHP language applications, due to its single-threaded nature, performance bottlenecks are prone to occur in high-concurrency scenarios. As a high-performance asynchronous network communication framework, Swoole can effectively improve the processing capabilities of PHP applications, allowing it to perform well in high-concurrency scenarios.

In Swoole's official documentation, we can find that it supports multi-process programming. This method allows us to evenly distribute a large task to multiple processes for execution, thus improving the processing capabilities of PHP applications to a certain extent. At the same time, multi-process based programming can also achieve more flexible process management and resource scheduling, effectively improving the stability and reliability of the program. Below, we will introduce in detail how to use Swoole's multi-process programming method to improve PHP processing capabilities.

What is multi-process?

Simply put, a process is a running program. Multi-process means that a program is divided into multiple processes for execution.

In Unix/Linux systems, each process has a unique process ID, through which different processes can be distinguished. The essence of multi-process programming is to divide a program into multiple processes for execution. Each process has independent address space, data stack, instruction counter and other resources. Communication between processes can be achieved through message queues, pipes, shared memory, etc.

Why use multiple processes?

Using multi-process programming can bring the following benefits:

1. Improve processing capabilities: Multi-process programming can evenly distribute a large task to multiple processes for execution, thereby improving The processing power and concurrency performance of the program.
2. Stability and reliability: Multi-process programming can improve the stability and reliability of the program through process management and resource scheduling.
3. Parallel computing: Multi-process programming allows different processes to perform computing tasks at the same time, thereby achieving parallel computing.

How to use multi-process in Swoole?

The following introduces the multi-process programming method based on Swoole to help us improve the processing capabilities of PHP applications.

Create subprocess

In Swoole, we can use the swoole_process class to create a subprocess. Many methods are provided in swoole_process, including creating subprocesses, sending messages to subprocesses, reading stdout and stderr of subprocesses, and so on.

The following code demonstrates how to use swoole_process to create a subprocess:

$process = new swoole_process(function(swoole_process $process) {
    // 这里是子进程的逻辑处理代码
    $process->write("Hello from child process
");
});

$process->start();
swoole_event_wait();

In the above code, we create a new subprocess through new swoole_process(), and the parameters passed in are An anonymous function that contains the processing logic of the child process. The $process->start() method can start a child process. The swoole_event_wait() method is used to wait for the child process to complete execution. We can understand that it will block the current process until the child process ends.

Father-child process communication

In a standard Unix/Linux system, communication between processes can be through pipes, message queues, shared memory, Signal (signal) and other methods to achieve. In Swoole, we can also use these methods to achieve communication between parent and child processes.

The following code demonstrates how to communicate through pipes between parent and child processes:

$process = new swoole_process(function(swoole_process $process) {
    // 子进程：从父进程管道中读取消息
    $msg = $process->read();
    echo "Message from parent process: $msg
";
    $process->exit();
});

$process->start();

// 父进程：向子进程管道中写入消息
$process->write("Hello from parent process");

// 等待子进程结束
swoole_process::wait();

In the above code, we call the $process->read() method in the child process from the parent Read the message from the process pipe and print it out through echo. In the parent process, we write messages to the child process pipe through the $process->write() method.

Process Pool

If we need to start multiple sub-processes to handle tasks, it is troublesome to create and manage each sub-process separately. For this situation, Swoole provides the swoole_process::pool() method to implement the concept of process pool. The process pool can realize the reuse of multiple sub-processes, thereby optimizing process management and resource scheduling.

The following code demonstrates how to use the process pool to create multiple sub-processes to handle tasks:

$pool = new swoole_process_pool(2, SWOOLE_IPC_UNIXSOCK, 0, true);

// 设置进程池启动回调函数
$pool->on("workerStart", function(swoole_process_pool $pool, $worker_id) {
    echo "Worker $worker_id started
";
});

// 设置进程池任务处理函数
$pool->on("message", function(swoole_process_pool $pool, $task) {
    echo "Task received: $task
";
});

// 启动进程池
$pool->start();

// 往进程池中投递任务
$pool->write("Hello");

// 等待任务执行完毕
$pool->shutdown();

In the above code, we create a process pool through the swoole_process_pool class, where parameter 2 indicates the use UNIX domain socket communication, parameter 0 means to use all CPU cores without restrictions, parameter true means to automatically restart dead child processes. After setting the process pool startup callback function and task processing function, we start the process pool through the $pool->start() method. After delivering the task, we wait for the task to be completed through the $pool->shutdown() method.

Summary

By using the multi-process programming method in Swoole, we can effectively improve the processing power and concurrency performance of PHP applications. Using multi-process optimization methods can achieve more flexible process management and resource scheduling, and improve the stability and reliability of the program. In actual development, we need to choose the appropriate number of processes and optimization methods based on our own business needs and system resources to achieve better performance and reliability.

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