test.php

<?php
$number_of_workers = 5;
$children = array();
$pair = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_DGRAM, STREAM_IPPROTO_IP);
stream_set_blocking($pair[0], 0);
stream_set_blocking($pair[1], 0);

function do_work($fd) {
    $pid = getmypid();
    for ($i = 0; $i < 10; $i++) {
        if ($i % 3 == 0)
            fwrite($fd, "$pid;fizz");
        if ($i % 5 == 0)
            fwrite($fd, "$pid;buzz");
        sleep(mt_rand(10, 500) / 100);
    }
}

for ($i = 0; $i < $number_of_workers; $i++) {
    if (($pid = pcntl_fork()) == 0) {
        fclose($pair[0]);
        do_work($pair[1]);
        exit();
    } else {
        echo "Launched child (pid=$pid)\n";
        $children[] = $pid;
    }
}

while (pcntl_waitpid(-1, $status, WNOHANG) == 0) {
    $rfds = array($pair[0]);
    $nfds = stream_select($rfds, $wfds = null, $efds = null, 1);
    foreach ($rfds as $rfd) {
        var_dump(fread($rfd, 1024));
    }
}