text: Title: why does my gevent run slowly than the normal program ? 
  Body: Python Version  : 3.7.3
  IDE : pycharm 
  problems : 
  I make a speed testing. I am trying to read the local file whihc are more then 2000 ,  it took for 6.5 seconds when i use the gevent moulde, another took for 2.8 seconds when normally i used 'for in'. 
  I want to know why does not gevent raise efficiency for I/O. 
  
  