plt.close('all') 没有摆脱“太多数字”警告

Question

I have a script that runs repeatedly and in the process it saves a figure into a folder. After a while I start getting warnings about too many open figures in memory.

I checked other questions on the topic, for example, this one and added plt.close('all') to my code so now it looks like this:

fig, ax = plt.subplots(figsize=(17,8))
plt.hist(results_df['Diff'], bins=100, density=True, histtype='step')
plt.savefig(f'backtester_results/figures/rf_model_{n_days}_data_and_{lag}_lag.png',
                format='png')
plt.close('all')

And yet I keep getting figures piled up in memory and warnings after a while. Where did I go wrong?

Here's the warning:

RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (matplotlib.pyplot.figure) are retained until explicitly closed and may consume too much memory.

Answer 1

When reading in the official documentation I would assume that plt.close('all') only closes the windows without removing the figures ( https://matplotlib.org/1.3.0/api/pyplot_api.html#matplotlib.pyplot.close ).

As I understand you would need to clear the figure as follows:

fig.clf()
plt.close()

Source: ( How can I release memory after creating matplotlib figures )