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

Question

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)

It doesn't happen if I try:

import imageio

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

vidfile = 'movie.mov'
vidrdf(vidfile)

or

import imageio

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

vidfile = 'movie.mov'
rdfobj = vidrdf(vidfile)

So this is clearly an issue with copying the object. I've searched about daemon threads, but since I'm using imageio directly I can't figure out why and how to resolve it. I would appreciate any recommendations.

score -1 · Answer 1 · answered Oct 03 '19 at 19:41

The following seems to work, although I don't know why:

import imageio
import copy

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


vidfile = 'movie.mov'
rdfobj = vidrdf(vidfile)

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

1 Answers1