Create a multi-process program

function

pcntl_fork creates a new process
pcntl_waitpid waits or returns the child process status of fork
posix_getpid returns the current process id
posix_getppid obtains the parent process id

note

pcntl_fork is called once and returns two values; the child process gets 0, and the parent process gets the child process id.

View all running php processes

ps -ef |grep php

Instance

<?php

echo "Master process id=".posix_getpid().PHP_EOL;
$pid = pcntl_fork();

switch ($pid){
    
    
    case -1:
        die('Create failed');
    case 0:
        //Child
        echo "Child process id = ".posix_getpid().PHP_EOL;
        sleep(2);
        echo "I will exit";
        break;
    default:
        //等待子进程退出,后之心父进程的退出
        if($exit_id = pcntl_waitpid($pid, $status, WUNTRACED)){
    
    
            echo "Child({
      
      $exit_id}) exited\n";
        }
        //Parent
        echo "Parent process id = ".posix_getpid().PHP_EOL;
        break;
}
sleep(18);