title: _pickle in python3 doesn't work for large data saving
body: <p>I am trying to apply <code>_pickle</code> to save data onto disk. But when calling <code>_pickle.dump</code>, I got an error</p>
  
  <pre><code>OverflowError: cannot serialize a bytes object larger than 4 GiB
  </code></pre>
  
  <p>Is this a hard limitation to use <code>_pickle</code>? (<code>cPickle</code> for python2)</p>