Merge pull request #37 from greevex/greevex-issue-36

Fixes issue #36

Author: cboden

src/StreamSelectLoop.php

@@ -255,7 +255,7 @@ protected function streamSelect(array &$read, array &$write, $timeout)
             return stream_select($read, $write, $except, $timeout === null ? null : 0, $timeout);
         }
 
-        usleep($timeout);
+        $timeout && usleep($timeout);
 
         return 0;
     }