Update Worker.php

Worker.php

@@ -453,8 +453,9 @@ class Worker
      */
     protected static $_availableEventLoops = array(
         'libevent' => '\Workerman\Events\Libevent',
-        'event'    => '\Workerman\Events\Event',
-        'swoole'   => '\Workerman\Events\Swoole'
+        'event'    => '\Workerman\Events\Event'
+        // Temporarily removed swoole because it is not stable enough  
+        //'swoole'   => '\Workerman\Events\Swoole'
     );
 
     /**
@@ -1194,7 +1195,7 @@ class Worker
             return static::$eventLoopClass;
         }
 
-        if (!class_exists('\Swoole\Event')) {
+        if (!class_exists('\Swoole\Event', false)) {
             unset(static::$_availableEventLoops['swoole']);
         }