Run multiple processes concurrently with amphp/process and coroutines

amp-process.php

<?php

declare(strict_types=1);

use Amp\ByteStream\Message;
use Amp\Loop;
use Amp\Process\Process;
use function Amp\coroutine;
use function Amp\Promise\all;

require 'vendor/autoload.php';

define('STOP_ON_ERROR', false);

Loop::run(function() {

    $totalStart = microtime(true);
  
    $processes = [
        'foobar' => new Process("sleep 3 && echo this is foobar"),
        'barbaz' => new Process("sleep 2 && echo this is barbaz"),
        'batman' => new Process("sleep 1 && echo this is batman && exit 1")
    ];

    $runProcess = coroutine(function(Process $process, string $name): iterable {
        $start = microtime(true);

        $process->start();
        $exitCode = yield $process->join();
        $elapsed  = number_format(microtime(true) - $start, 3);

        $stdout = trim(yield new Message($process->getStdout()));

        if ($exitCode > 0 && STOP_ON_ERROR) {
            throw new Exception("Process $name exited after {$elapsed}s with code $exitCode and this output: \n$stdout");
        }

        return compact('name', 'exitCode', 'stdout', 'elapsed');
    });

    // magic happens: mappa una coroutine per processo, e le attende tutte concorrenzialmente
    $outputs = yield all(array_map($runProcess, $processes, array_keys($processes)));

    var_dump($outputs);

    $totalElapsed = microtime(true) - $totalStart;

    echo PHP_EOL , "Total elapsed time: $totalElapsed" , PHP_EOL;
});

composer.json

{
    "require": {
        "php": "^7.1",
        "amphp/process": "^0.2.1"
    }
}