Matplotlib Calls in MultiProcess/Threads

[SorooshMani-NOAA]

ocsmesh uses matplotlib for contour level calculations. These operations are usually done in parallel and using multi processing and multi threading. This can cause issues due to interactive backends of matplotlib. We cannot blindly set agg backend to resolve this, because ocsmesh has plotting methods as well.

The current solution is for the user to force non-interactive backend in the sections of the client code which doesn't need interactive backend (and no actual plots are created). This is done by matplotlib.use('agg').

The issue that might arise in case backend is interactive is:

Exception ignored in: <function Image.__del__ at 0x7f745970cdc0>
Traceback (most recent call last):
  File "/home/smani/miniconda3/envs/meshdev/lib/python3.10/tkinter/__init__.py", line 4056, in __del__
    self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
...