ValueError при закрытии фигуры пиплота

Question

Я создаю рисунки в нескольких темах.Я видел эту ошибку в моих журналах.plt - это matplotlib.pyplot.Почему фигура не закрывается?

[2018-10-12 21:39:30,474: WARNING/ForkPoolWorker-116] Exception in thread Thread-30:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "/opt/app/jobs/jobs/graphing.py", line 135, in run
    self.data, graph_type, self.batch_name, self.exp_names, filename
  File "/opt/app/jobs/jobs/graphing.py", line 295, in generate_plot
    plt.close(figure)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/pyplot.py", line 675, in close
    _pylab_helpers.Gcf.destroy_fig(arg)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/_pylab_helpers.py", line 69, in destroy_fig
    cls.destroy(num)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/_pylab_helpers.py", line 58, in destroy
    cls._activeQue.remove(manager)
ValueError: list.remove(x): x not in list