server.php

<?php

use Amp\Iterator;
use Amp\Cluster\Listener;
use Psr\Log\LoggerInterface as PsrLogger;

Amp\Loop::run(function () {
    if (Amp\Cluster::isWorker()) {
        $socket = yield Amp\Cluster::listen("tcp://0.0.0.0:8080");
        $logger = Amp\Cluster::getLogger();
    } else {
        $socket = Amp\Socket\listen("tcp://0.0.0.0:8080");
        $logger = new StdLogger;
    }
    
    $logger->info("Listening on " . $server->getAddress());
    
    \Amp\asyncCall(function () use ($server) {
        /** @var \Amp\Socket\ClientSocket $client */
        while ($client = yield $server->accept()) {
            $client->write(\sprintf("Hello from PID %s!\n", \getmypid()));
            $client->close();
        }
    });
    
    // Registers a SIGINT / SIGTERM signal handler
    // Maybe also some special IPC command for Windows
    Amp\Cluster::onTerminateRequest(function () use ($server) {
        $server->close();
    });
};