sample fork with shared memory

fork.php

#!/usr/bin/php
<?php 
ini_set("error_reporting",E_ALL);
ini_set("display_errors",1);

printf("%s MAIN %s\n\n", getmypid(), date("H:i:s"));

$shm_id = shm_attach(1);

$main_process_id = getmypid();
while(1){
    $pid = pcntl_fork();
    $status = "STARTED CHILD 1"; 

    if(getmypid() == $main_process_id){
        child_1($pid, $status);
    }
    
    if ($pid) {
         // we are the parent
        pcntl_wait($fork_status); //Protect against Zombie children

        printf("%s PARENT($pid) %s\n\n", getmypid(), date("H:i:s"));

    } else { // we are the child
        child_2($status);
        exit();
    }
    
}

printf("======== %s ========\n", date("H:i:s"));

function child_1($sibling_pid, &$status){
    global $shm_id;
    shm_put_var($shm_id, 0, $status);

    sleep(2);
    printf("  %s CHILD 1 %s\n", getmypid(), date("H:i:s"));
    
    $status = "WOKE UP " . time();
    shm_put_var($shm_id, 0, $status);
    
    sleep(2);
    posix_kill($sibling_pid, SIGKILL);
}

function child_2(){
    global $shm_id;
    
    while(1){
        sleep(1);
        $status = shm_get_var($shm_id, 0);
        echo "[$status] ";
        
    }
}




?>