title: What's difference between select{} and for{} in golang?
body: <p>I find a similar question: <a href="https://stackoverflow.com/questions/18661602/what-does-an-empty-select-do">What does an empty select do?</a></p>
  
  <p><code>for{}</code> will cover 100% cpu usage.</p>
  
  <p><code>select{}</code> ask the channel case can read or write or not. But no case in the select. <code>select{}</code> will use 0% cpu usage? Or just like the <code>for{}</code>?</p>