Fatal Python error: could not acquire lock for <_io.BufferedReader name=8> at interpreter shutdown, possibly due to daemon threads

Possibly related to #174

I’ve posted this on Stack Overflow (link) but can’t figure if it’s more suited for here. So apologies for double-posting.

Running the following:

import imageio

class vidrdf:
    def __init__(self, vidfile):
        self.vid = imageio.get_reader(vidfile,  'ffmpeg')
        
vidfile = 'movie.mov'
rdfobj = vidrdf(vidfile)

I get:

Fatal Python error: could not acquire lock for <_io.BufferedReader name=8> at interpreter shutdown, possibly due to daemon threads

Thread 0x00007fd2dc2a8700 (most recent call first):
  File “/path/miniconda3/envs/flower/lib/python3.7/site-packages/imageio_ffmpeg/_parsing.py", line 61 in run
  File "miniconda3/envs/flower/lib/python3.7/threading.py", line 926 in _bootstrap_inner
  File “/path/miniconda3/envs/flower/lib/python3.7/threading.py", line 890 in _bootstrap

Current thread 0x00007fd2f0bb9700 (most recent call first):
  File “/path/miniconda3/envs/flower/lib/python3.7/subprocess.py", line 1704 in _communicate
  File “/path/miniconda3/envs/flower/lib/python3.7/subprocess.py", line 939 in communicate
  File “/path/miniconda3/envs/flower/lib/python3.7/site-packages/imageio_ffmpeg/_io.py", line 193 in read_frames
  File “/path/miniconda3/envs/flower/lib/python3.7/site-packages/imageio/plugins/ffmpeg.py", line 342 in _close
  File “/path/miniconda3/envs/flower/lib/python3.7/site-packages/imageio/core/format.py", line 252 in close
  File “/path/miniconda3/envs/flower/lib/python3.7/site-packages/imageio/core/format.py", line 241 in __del__
Aborted (core dumped)

For some reason this happens when running the code as a script, but not when run in a Jupyter notebook. It also happens in Python interactive environment only once Python is exited.

This also doesn’t happen when I replace self.vid=... with vid=... or replace rdfobj = vidrdf(vidfile) with just vidrdf(vidfile). So this seems to be an issue with copying the object (probably while daemon thread related to ffmpeg is closed?). Is there any resolution to this?

-Thanks