title: What to do when Jupyter suddenly hangs?
body: <p>I'm using Jupyter notebook 4.0.6 on OSX El Capitan. </p>
  
  <p>Once in a while I'll start running a notebook and the cell will simply hang, with a <code>[ * ]</code> next to it and no output.</p>
  
  <p>When this happens, I find that only killing Jupyter at the command line and restarting it solves the problem. Relaunching the kernel doesn't help. </p>
  
  <p>Has anyone else had this problem? If so, any tips?</p>