PHP Linux script development experience sharing: using multiple processes to achieve concurrent processing

PHP Linux script development experience sharing: using multiple processes to achieve concurrent processing

When developing PHP scripts, we often encounter the need to process a large amount of data or execute the time-consuming process operating conditions. If processed in a traditional serial manner, the entire process will be very time-consuming and affect performance. In order to improve processing efficiency, we can use Linux's multi-process capabilities to achieve concurrent processing.

Below I will share some of my experience in PHP Linux script development and provide some specific code examples for your reference.

1. Use the fork function to create a child process

In Linux, the fork function can help us create a child process. The child process is an exact copy of the parent process and continues code execution from where the fork function returns. We can take advantage of this feature to distribute a large number of tasks to sub-processes for parallel processing, thereby increasing the overall processing speed.

The following is a simple sample code:

<?php
$pid = pcntl_fork();

if ($pid == -1) {
    // 创建子进程失败处理代码
    exit('创建子进程失败');
} elseif ($pid) {
    // 父进程代码
    // 父进程可以继续执行其他任务
} else {
    // 子进程代码
    // 子进程用来处理具体任务
    exit('子进程处理完成');
}

In this example, we use the pcntl_fork() function to create a child process. Both the parent process and the child process can continue to execute subsequent code, but their process IDs will be different after the fork. In the child process, we can write specific task processing logic. After the child process completes the task, it can use the exit() function to exit.

2. Inter-process communication

In multi-process concurrent processing, inter-process communication is very important. Linux provides a variety of inter-process communication methods, including pipes, message queues, shared memory, etc.

The following is a sample code that uses message queues for inter-process communication:

<?php
// 创建消息队列
$queueKey = ftok(__FILE__, 'a'); // 生成唯一的key
$queue = msg_get_queue($queueKey, 0666);

$pid = pcntl_fork();

if ($pid == -1) {
    // 创建子进程失败处理代码
    exit('创建子进程失败');
} elseif ($pid) {
    // 父进程代码
    // 发送消息到消息队列
    $message = 'Hello, child process!';
    msg_send($queue, 1, $message, true); // 第一个参数为队列ID，第二个参数为消息类型，第三个参数为消息内容，第四个参数为是否阻塞
} else {
    // 子进程代码
    // 从消息队列接收消息
    msg_receive($queue, 1, $messageType, 1024, $message, true, MSG_IPC_NOWAIT);
    echo $message;
    exit('子进程处理完成');
}

In this example, we use the ftok function to generate a unique key, and use the msg_get_queue function to create a message queue. The parent process sends messages to the message queue through the msg_send function, and the child process receives messages from the message queue through the msg_receive function. After processing is completed, the child process exits using the exit function.

3. Control the number of concurrencies

In actual concurrent processing, we often need to control the number of concurrencies to avoid occupying too many system resources. We can use semaphores to control the amount of concurrency.

The following is a sample code that uses a semaphore to control the number of concurrencies:

<?php
// 创建信号量
$semKey = ftok(__FILE__, 'b');
$semId = sem_get($semKey, 1);

$pid = pcntl_fork();

if ($pid == -1) {
    // 创建子进程失败处理代码
    exit('创建子进程失败');
} elseif ($pid) {
    // 父进程代码
    // 父进程可以继续执行其他任务
} else {
    // 子进程代码
    // 获取信号量
    sem_acquire($semId);

    // 子进程用来处理具体任务
    sleep(5);

    // 释放信号量
    sem_release($semId);
    exit('子进程处理完成');
}

In this example, we use the sem_get function to create a semaphore, and use the sem_acquire and sem_release functions to acquire and release signal. The child process acquires the semaphore before processing the task and releases the semaphore after processing. By controlling the number of semaphores, the effect of controlling the number of concurrency can be achieved.

Summary:

By taking advantage of the multi-process capability of Linux, we can use the fork function to create child processes and use inter-process communication for data exchange. By controlling the number of concurrencies, the execution efficiency of PHP scripts can be improved and concurrent processing can be achieved.

Of course, there are also some challenges and precautions in multi-process programming, such as synchronization and mutual exclusion between processes, rational utilization of resources, etc. In actual development, it is recommended to choose an appropriate concurrency processing method based on specific business scenarios and system configurations. I hope the above experience and sample code will be helpful to everyone's PHP Linux script development.

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