Making many figures with multiprocessing causes text to be scrambled

Question

I am using matplotlib with multiprocessing to make many figures quickly. The issue is that the text in the title on some figures is messed up.

Some titles are messed up, like this...

And others look correct...

Has anyone else ever had this problem, and is there a way to prevent it from happening?

For reference, I am using the method in this answer to make my figures: https://stackoverflow.com/a/40032128/2383070

def make_plot(d):
    plt.cla()
    plt.clf()

    d1 = np.random.rand(10,10)*d
    d2 = np.random.rand(10,10)*d
    d3 = np.random.rand(10,10)*d

    figs, (ax1, ax2, ax3) = plt.subplots(1,3, figsize=(20,10))

    plt.sca(ax1)
    plt.title('A title for d1')
    plt.pcolormesh(d1, vmin=0, vmax=1)

    plt.sca(ax2)
    plt.title('A title for d2')
    plt.pcolormesh(d2, vmin=0, vmax=1)

    plt.sca(ax3)
    plt.title('A title for d3')
    plt.pcolormesh(d3, vmin=0, vmax=1)

    plt.savefig('./%s' % d)

p = multiprocessing.Pool(10)
p.map(make_plot, range(30))

In order to investigate this problem, one would need to see a [mcve]. — ImportanceOfBeingErnest, Jan 29 '19 at 20:27
Ok, I cannot reproduce though, all figures are correct for me. Just note that if this is on windows you would need to add `multiprocessing.freeze_support()`. Any further information on where and how you run this? — ImportanceOfBeingErnest, Jan 29 '19 at 21:12
Did you try outside a notebook, i.e. running a script from the console? — ImportanceOfBeingErnest, Jan 29 '19 at 21:20
Interesting. There is no problem when running as a script. Guess I'll have to switch out of notebooks for this task. — blaylockbk, Jan 29 '19 at 21:41
Not sure if it’s your problem, but I wouldn’t use the implicit pyplot plotting interface if I was running multiple threads. Create print and destroy each figure inside the function. — Jody Klymak, Jan 30 '19 at 03:30

Making many figures with multiprocessing causes text to be scrambled

0 Answers0