There are several ways to communicate between php processes

There are several ways for PHP to communicate between processes: pipe (Pipe) and named pipe (named pipe), signal (Signal), message (Message) queue (message queue), shared memory, signal Semaphore, Socket.

This article lists one for introduction, that is, through famous pipes.

Pipes are used to carry communication data between abbreviations. To facilitate understanding, a pipe can be compared to a file. Process A writes data to pipe P, and then process B reads data from pipe P.

The pipeline operation API provided by php is basically the same as the API for operating files. Except that the posix_mkfifo function is used to create a pipeline, the read and write operations are the same as the file operation functions.

Of course, you can directly use files to simulate pipelines, but then you will not be able to use the features of pipelines.

The general idea of ​​communicating through a pipe is to first create a pipe, then the child process writes information to the pipe, and the parent process reads the information from the pipe. In this way, the parent and child processes can communicate directly.

<?php
/**
 * author: NickBai
 * createTime: 2016/12/2 0002 上午 11:12
 */
//创建管道
$pipePath = "/tmp/test.pipe";
if( !file_exists( $pipePath ) ){
    if( !posix_mkfifo( $pipePath, 0666 ) ){
        exit(&#39;make pipe false!&#39; . PHP_EOL);
    }
}
//创建进程,子进程写管道，父进程读管道
$pid = pcntl_fork();
if( $pid == 0 ){
    //子进程写管道
    $file = fopen( $pipePath, &#39;w&#39; );
    fwrite( $file, &#39;hello world&#39; );
    sleep(1);
    exit();
}else{
    //父进程读管道
    $file = fopen( $pipePath, &#39;r&#39; );
    //stream_set_blocking( $file, False );  //设置成读取非阻塞
    echo fread( $file, 20 ) . PHP_EOL;
    pcntl_wait($status);  //回收子进程
}

Note: This code can only be run under linux and only in php-cli mode.

Line 7: Specify the path of a pipeline, which is no different from an ordinary file.

Line 9: Create a pipe through the posix_mkfifo function and set the read and write permissions to 0666

Line 15: Create a child process through the pcntl_fork function. Note that from now on, the program will be executed in two processes. The pcntl_fork function is very special. It has multiple return values ​​once called. In the parent process: it returns the ID of the child process. This value is greater than 0. In the child process, it returns 0. When -1 is returned, it indicates that the creation process failed.

Line 17: The two processes enter different branches based on the different $pid values ​​obtained by the current process.

Line 18~22: The child process opens the pipe, writes hello world to it, then enters sleep, and exits after the sleep ends.

Line 25~29: The parent process opens the pipe and reads it, and finally executes the code on line 29 to recycle the child process. There are two places here that are blocked. The first is the default reading place. You have to wait for the child process to issue an exit command before the data can be returned. There is also the pcntl_wait method of recycling the process. Wait until the process exits.

The above is the detailed content of There are several ways to communicate between php processes. For more information, please follow other related articles on the PHP Chinese website!