title: Creating pandas.DataFrame from generator?
body: <p>I'm tring to create dataframe from &lt;generator object _chain_from_iterable_of_lists at ...&gt;</p>
  <p>but throws an error :</p>
  <pre><code>concurrent.futures.process.BrokenProcessPool: A process in the process pool was terminated abruptly while the future was running or pending.
  </code></pre>
  <p>The generator is returned from below function.</p>
  <pre><code>def calc_func(a):
     .........
     return array.item(), index_name
  
  res = []
  with ProcessPoolExecutor(max_workers=num_workers) as executor:
      res = executor.map(calc_func, a)
  res = pd.DataFrame(res) &lt;---- error occurred here
  </code></pre>
  <p>The files I want to use are so big. I tried decreasing num_workers.</p>
  <p><strong>Question</strong></p>
  <ol>
  <li>Why did this problem occur ?</li>
  <li>How to create dataframe from generator in using ProcessPoolExecutor ?</li>
  </ol>