Bug summary

I'm running Python3.8 on a Ubuntu 18.04.6 LTS (32-bit) box.
Tried different Matplotlib releases, even back to version 3.0.3, always the same issue. CPU goes to 100%, empty Window pops up (in case of show) and Python freezes up; have to kill it manually.

Code for reproduction

# Example 1
import matplotlib.pyplot as plt
plt.plot([1,2,3],[3,0,3])
plt.show()

# Example 2
import matplotlib.pyplot as plt
plt.plot([1,2,3],[3,0,3])
plt.savefig("test.png")

Actual outcome

Freeze

Expected outcome

Plot as pop-up / file on disk

Additional information

No response

Operating system

Ubuntu 18.04.6 LTS

Matplotlib Version

3.0.3 up to 3.7.0

Matplotlib Backend

TkAgg

Python version

Python 3.8.0

Jupyter version

No response

Installation

pip