title: MySQL Process List - locked issue
body: <p>In the MySQL Process List, it is showing a few <code>SELECT</code> query has been locked. Time of locked show over 4000</p>
  
  <pre><code>|   24 | user | localhost | database | Query   | 4725 | Locked   | SELECT * FROM data  
  |   25 | user | localhost | database | Query   | 4725 | Locked   | SELECT * FROM data
  |   26 | user | localhost | database | Query   | 4725 | Locked   | SELECT * FROM data
  </code></pre>
  
  <p>PHP Script has been executed a few time but then <code>SELECT</code> became in Locked state.  How to solve this problem?</p>
  
  <pre><code>$SQL = "SELECT * FROM data";
  $query = $db-&gt;prepare($SQL);
  $query-&gt;execute();
  while ($row = $query-&gt;fetch(PDO::FETCH_ASSOC)) {
      //Do something
      sleep(2);
  }
  </code></pre>
  
  <p>Is mySQL server limiting SELECT query to run once at the time? can this be changed?</p>