Laravel.io
<?php
use Spatie\Async\Pool;
use Illuminate\Support\Facades\Artisan;

require_once 'vendor/autoload.php';

$tasks = [
    'some:command',
    'other:command'
];

$pool = Pool::create();
foreach ($tasks as $task) {
    $pool->add(function () use($task) {
        Artisan::call($task);
        return true;
    })->then(function ($output) {
        return $output;
    });
}

$data = $pool->wait();
dd($data);

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