gistfile1.php

<?php

function master()
{
    $num_partitions = 10;

    // not every system has this :(
    //setproctitle("Parallel master: {$num_partitions} partitions");

    $workers = [];
    for ($partition = 0; $partition < $num_partitions; ++$partition) {
        $pid = pcntl_fork();
        if ($pid === -1) {
            echo "Fork problems\n";
        } elseif ($pid) {
            // still in the parent process
            $workers[$pid] = "running";
        } else {
            // now in a child process
            worker($partition);
        }
    }

    master_print_scoreboard($workers);

    $worker_errors = count($workers) < $num_partitions;
    for ($num_active_workers = count($workers); $num_active_workers > 0; --$num_active_workers) {
        $status = 0;
        $pid = pcntl_wait($status);
        $returncode = pcntl_wexitstatus($status);
        if ($returncode) {
            $worker_errors = true;
        }
        $workers[$pid] = $returncode
            ? "exited with code {$returncode}"
            : "finished normally";

        master_print_scoreboard($workers);
    }

    exit((int)$worker_errors);
}

function master_print_scoreboard($workers) {
    echo "Master: worker statuses: ";
    var_dump($workers);
    echo "\n";
}

function worker($partition)
{
    // not every system has this :(
    //setproctitle("Parallel worker: partition {$partition}");
    
    try {
        worker_do_work($partition);
        exit(0); // success
    } catch (Exception $e) {
        echo "Worker {$partition} exception: {$e->getMessage()}\n";
        exit(1); // error
    }
}

function worker_do_work($partition)
{
    echo "Worker {$partition} taking a nap\n";
    sleep(10 + rand(0, 5));
    if ($partition === 4) {
        throw new Exception("Being difficult");
    }
    echo "Worker {$partition} waking up\n";
}

master();