Pyplot savefig memory leak - alternative?

Question

Is there an alternative to pyplot to plot some graphs in python? I'm having some memory leaks which make my project impossible to complete.

I've tried the usual recommended "solutions" of using plt.close(), plt.clf(), etc with and without a single fig = plt.figure() object, but it did absolutely nothing.

I also tried using a thread but it's the first time I used it in python so I may have done it wrong :

import gc
import psutil
from threading import Thread
import matplotlib.pyplot as plt


def plot_func():
    plt.plot([1,2,3], [1,2,3])
    plt.savefig('plot_test.png')
    plt.close()

gc.collect()
init_mem_tot = psutil.Process().memory_info().rss / 2**20
for i in range(20):
    init_mem = psutil.Process().memory_info().rss / 2**20
    thread = Thread(target=plot_func)
    thread.start()
    thread.join()

    # tried with and without those the two following lines
    del thread
    gc.collect()
    new_mem = psutil.Process().memory_info().rss / 2**20
    print("Memory : %f, previous : %f. (%f difference)" % (new_mem, init_mem, init_mem - new_mem))

final_mem = psutil.Process().memory_info().rss / 2**20
print("Final : %f, Init : %f. (%f tot difference)" % (final_mem, init_mem_tot, final_mem - init_mem_tot))

Result gives :

Memory : 107.441406, previous : 102.687500. (4.753906 difference)
Memory : 108.578125, previous : 107.445312. (1.132812 difference)
Memory : 109.941406, previous : 108.578125. (1.363281 difference)
Memory : 111.281250, previous : 109.941406. (1.339844 difference)
Memory : 112.195312, previous : 111.281250. (0.914062 difference)
Memory : 113.281250, previous : 112.195312. (1.085938 difference)
Memory : 114.535156, previous : 113.281250. (1.253906 difference)
Memory : 115.640625, previous : 114.535156. (1.105469 difference)
Memory : 116.707031, previous : 115.640625. (1.066406 difference)
Memory : 117.843750, previous : 116.707031. (1.136719 difference)
Memory : 119.175781, previous : 117.843750. (1.332031 difference)
Memory : 120.367188, previous : 119.175781. (1.191406 difference)
Memory : 121.507812, previous : 120.367188. (1.140625 difference)
Memory : 122.660156, previous : 121.507812. (1.152344 difference)
Memory : 123.937500, previous : 122.660156. (1.277344 difference)
Memory : 124.828125, previous : 123.937500. (0.890625 difference)
Memory : 126.406250, previous : 124.832031. (1.574219 difference)
Memory : 127.671875, previous : 126.406250. (1.265625 difference)
Memory : 128.585938, previous : 127.671875. (0.914062 difference)
Memory : 129.699219, previous : 128.589844. (1.109375 difference)
Final : 129.699219, Init : 102.687500. (27.011719 tot difference)

If those are all the solutions, is there an other way for me to plot stuff?

Answer 1

If not using threading and not using pyplot, only a very slight memory consumption increase is observed. I do not know where it comes from, but it might be bearable.

import gc
import psutil
from matplotlib.figure import Figure


def plot_func():
    fig = Figure()
    ax = fig.add_subplot()
    ax.plot([1,2,3], [1,2,3])
    fig.savefig('plot_test.png')

init_mem_tot = psutil.Process().memory_info().rss / 2**20
for i in range(100):
    init_mem = psutil.Process().memory_info().rss / 2**20

    plot_func()
    gc.collect()
    new_mem = psutil.Process().memory_info().rss / 2**20
    print("Memory : %f, previous : %f. (%f difference)" % (new_mem, init_mem, init_mem - new_mem))

final_mem = psutil.Process().memory_info().rss / 2**20
print("Final : %f, Init : %f. (%f tot difference)" % (final_mem, init_mem_tot, final_mem - init_mem_tot))

Output: (Note how 95% are by the very first plot)

Memory : 48.113281, previous : 44.140625. (-3.972656 difference)
Memory : 48.152344, previous : 48.113281. (-0.039062 difference)
Memory : 48.195312, previous : 48.152344. (-0.042969 difference)
Memory : 48.199219, previous : 48.195312. (-0.003906 difference)
Memory : 48.199219, previous : 48.199219. (0.000000 difference)
Memory : 48.199219, previous : 48.199219. (0.000000 difference)
Memory : 48.257812, previous : 48.199219. (-0.058594 difference)
Memory : 48.257812, previous : 48.257812. (0.000000 difference)
Memory : 48.265625, previous : 48.257812. (-0.007812 difference)
Memory : 48.265625, previous : 48.265625. (0.000000 difference)
Memory : 48.269531, previous : 48.265625. (-0.003906 difference)
Memory : 48.273438, previous : 48.269531. (-0.003906 difference)
Memory : 48.273438, previous : 48.273438. (0.000000 difference)
Memory : 48.273438, previous : 48.273438. (0.000000 difference)
Memory : 48.273438, previous : 48.273438. (0.000000 difference)
Memory : 48.273438, previous : 48.273438. (0.000000 difference)
Memory : 48.281250, previous : 48.273438. (-0.007812 difference)
Memory : 48.285156, previous : 48.281250. (-0.003906 difference)
Memory : 48.285156, previous : 48.285156. (0.000000 difference)
Memory : 48.312500, previous : 48.285156. (-0.027344 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.312500, previous : 48.312500. (0.000000 difference)
Memory : 48.316406, previous : 48.312500. (-0.003906 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.316406, previous : 48.316406. (0.000000 difference)
Memory : 48.320312, previous : 48.316406. (-0.003906 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Memory : 48.320312, previous : 48.320312. (0.000000 difference)
Final : 48.320312, Init : 44.140625. (4.179688 tot difference)