Load balancing PHP built-in server?
<p>My development environment consists of the single-threaded built-in PHP server. Works great: </p>

<pre><code>APP_ENV=dev php -S localhost:8080 -c php.ini web/index.php
</code></pre>

<p>One issue with this is that the built-in server is single-threaded. This makes lots of parallel XHRs resolve sequentially. Worst of all, it doesn't mimic our production environment very well. Some front-end issues with concurrency simply don't exist in this set up.</p>

<h3>My question:</h3>

<p>What's an existing solution that I could leverage that would proxy requests asynchronously to multiple instances of the same PHP built-in server?</p>

<p>For example, I'd have a few terminal sessions running the built-in server on different ports, then each request is routed to a different one of those instances. In other words, I want multiple instances of my application running in parallel using the simplest possible set up (no Apache or Nginx if possible).</p>