Got 100% CPU Load on a production server with huge parallel load
Hello,

I am getting 100% CPU Load almost instantly (after 10-15 seconds of run) on a production server with a lot of parallel usage (~500 users in parallel opens WebSocket and send some data).

Trying to figure out the bottleneck I have ended up with an absolutely empty code that causes a 100% CPU usage. Xdebug suggests that the issue is in react/event-loop. 
I have tried StreamSelectLoop (the default one) and ExtEventLoop (this one selected automatically when php-pecl-event enabled. I have php-pecl-event 2.2.1 and libevent 2.0.22 installed) - both make 100% CPU Load.

CacheGrind files:
ExtEventLoop: https://www.dropbox.com/s/s5lmg9ey5lyxrf5/cachegrind_ExtEventLoop.zip
StreamSelectLoop: https://www.dropbox.com/s/q61kbzy1y7cpxg3/cachegrind_StreamSelectLoop.zip

Sample code:

```
<?php
  require __DIR__ . '/vendor/autoload.php';
  use Ratchet\ConnectionInterface;

  class EmptyClass implements Ratchet\MessageComponentInterface {
    public function onMessage(ConnectionInterface $from, $msg) {
    }
    public function onOpen(ConnectionInterface $conn) {
    }
    public function onClose(ConnectionInterface $conn) {
    }
    public function onError(ConnectionInterface $conn, \Exception $e) {
    }
  }

  $webServer = Ratchet\Server\IoServer::factory(
          new EmptyClass(),
    8080
  );
  $webServer->run();
?>

```

composer show -i:
```
cboden/ratchet            v0.3.5 PHP WebSocket library
evenement/evenement       v2.0.0 Événement is a very simple event dispatching library for PHP
guzzle/common             v3.9.2 Common libraries used by Guzzle
guzzle/http               v3.9.2 HTTP libraries used by Guzzle
guzzle/parser             v3.9.2 Interchangeable parsers used by Guzzle
guzzle/stream             v3.9.2 Guzzle stream wrapper component
guzzlehttp/psr7           1.3.1  PSR-7 message implementation
psr/http-message          1.0.1  Common interface for HTTP messages
ratchet/pawl              v0.2.2 Asynchronous WebSocket client
ratchet/rfc6455           v0.2.1 RFC6455 WebSocket protocol handler
react/cache               v0.4.1 Async caching.
react/dns                 v0.4.3 Async DNS resolver.
react/event-loop          v0.4.2 Event loop abstraction layer that libraries can use for evented I/O.
react/promise             v2.4.1 A lightweight implementation of CommonJS Promises/A for PHP
react/promise-timer       v1.1.0 Trivial timeout implementation for Promises
react/socket              v0.4.3 Library for building an evented socket server.
react/socket-client       v0.5.1 Async connector to open TCP/IP and SSL/TLS based connections.
react/stream              v0.4.5 Basic readable and writable stream interfaces that support piping.
react/zmq                 v0.3.0 ZeroMQ bindings for React.
symfony/event-dispatcher  v3.1.7 Symfony EventDispatcher Component
symfony/http-foundation   v3.1.7 Symfony HttpFoundation Component
symfony/polyfill-mbstring v1.3.0 Symfony polyfill for the Mbstring extension
symfony/routing           v3.1.7 Symfony Routing Component
```

php -v
```
PHP 7.0.13 (cli) (built: Nov  8 2016 20:28:51) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.13, Copyright (c) 1999-2016, by Zend Technologies
    with Xdebug v2.4.1, Copyright (c) 2002-2016, by Derick Rethans
```

Any help is highly appreciated!