title: Does Django run in single thread by default？
body: <p>By reading the code, I found it seems that Django run in single thread by default.</p>
  <p>However, when I use sleep(15) in my view function and open two web to request my function. They return the response almost at the same time!</p>
  <p>so, I do not know why does it happened……</p>
  <p>my Django version is 1.9</p>