title: Training neural network in Google Colab CPU - second epoch does not start
body: <p>I am training a neural network on Google Colab CPU (I cannot use a GPU regarding another issue: <a href="https://stackoverflow.com/questions/62468830/filenotfounderror-no-such-file-error-occuring-only-on-gpu-not-on-cpu">FileNotFoundError: No such file: -&gt; Error occuring only on GPU, not on CPU</a>) with the <code>fit_generator</code> method.</p>
  
  <pre><code>model.fit_generator(generator=training_generator,
                      validation_data=validation_generator,
                      steps_per_epoch = num_train_samples // 128,
                      validation_steps = num_val_samples // 128,
                      epochs = 10,
                      use_multiprocessing=True,
                      workers=6)
  </code></pre>
  
  <p>The training for the first epoch seems to run fine, but the second does not start. The notebook does not break down or the iteration does not stop. However, the second epoch is not starting...</p>
  
  <p>Is there something wrong with my code?</p>