title: Are there different priority in otp gen_server's info, call, cast message queue?
body: <p>When writing codes, I ask myself which type of message should use <code>call</code>, which type of message should use <code>info</code>?</p>
  
  <p>Below this question, there is another long-time doubt whether there is priority difference between <code>info, cast, call</code> message? whether these 3 type of messages share the same queue?</p>