Multiprocessing causes Python to crash and gives an error may have been in progress in another thread when fork() was called

Question

I am relatively new to Python and trying to implement a Multiprocessing module for my for loop.

I have an array of Image url\'s stored in img_urls which I need to do

Answer 1

This error occurs because of added security to restrict multithreading in Mac OS High Sierra. I know this answer is a bit late, but I solved the problem using the following method:

Set an environment variable .bash_profile to allow multithreading applications or scripts under the new Mac OS High Sierra security rules.

Open a terminal:

$ nano .bash_profile

Add the following line to the end of the file:

export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES

Save, exit, close terminal and re-open the terminal. Check to see that the environment variable is now set:

$ env

You will see output similar to:

TERM_PROGRAM=Apple_Terminal
SHELL=/bin/bash
TERM=xterm-256color
TMPDIR=/var/folders/pn/vasdlj3ojO#OOas4dasdffJq/T/
Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.E7qLFJDSo/Render
TERM_PROGRAM_VERSION=404
TERM_SESSION_ID=NONE
OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES

You should now be able to run your python script with multithreading.