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

📝 Title: Multiprocessing in Python Causing Crashes? Here's the Solution!

🔥 Introduction: Hey there, Python enthusiasts! Are you new to Python and trying to implement the Multiprocessing module for a smooth-running for loop? Well, you might have encountered a frustrating issue that causes Python to crash and gives you an error message about another thread being in progress when calling fork().

But worry not, as we've got you covered! In this blog post, we'll address common issues related to multiprocessing in Python and provide you with easy solutions to resolve them. So, let's dive in and get your multiprocessing code back on track! 😄

🤷‍♀️ The Problem: Our reader, who is new to Python, shared their code snippet where they are using the Multiprocessing module to download images from a list of URLs and apply some Google vision. However, when running the code, they encounter a warning message, and Python crashes.

🔍 Understanding the Issue: The warning message states that [__NSPlaceholderDate initialize] may have been in progress in another thread when fork() was called. This issue arises due to a conflict between the Multiprocessing module and certain parts of the Objective-C framework used in macOS.

📋 The Solution: To resolve this issue and prevent Python from crashing, you can follow these steps:

1️⃣ Import the os module at the top of your Python script:

import os

2️⃣ Inside your if __name__ == '__main__': block, add the following code to set an environment variable:

os.environ['OBJC_DISABLE_INITIALIZE_FORK_SAFETY'] = 'YES'

3️⃣ That's it! By adding this code, you disable the Objective-C fork safety initialization, mitigating the conflict and preventing the crash.

💡 Example: Here's how your updated code will look:

if __name__ == '__main__':
    import os
    os.environ['OBJC_DISABLE_INITIALIZE_FORK_SAFETY'] = 'YES'

    img_urls = [ALL_MY_Image_URLS]
    runAll(img_urls)
    print("--- %s seconds ---" % (time.time() - start_time))

💥 Problem Solved! By adding the provided code to your script, you'll be able to successfully run your multiprocessing code without experiencing crashes caused by the conflicting Objective-C framework.

🔔 Engage with Us! We hope this blog post helped you resolve the multiprocessing crash issue in Python. If you found it useful, don't forget to share it with your fellow Pythonistas! 🙌

📢 Call-to-Action: Have you encountered any other Python-related issues that you need help with? Let us know in the comments below! Our community of tech enthusiasts and experts are here to assist you. Happy coding! 😄💻