Скачать или смотреть Resolving the Issue of Python Script Stops in the Middle of Execution Without Errors

Discover how to fix your Python script that halts unexpectedly during execution. This guide provides a step-by-step solution for handling large recursion using multithreading.
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Why Does My Python Script Stop in the Middle of Execution?

If you've ever found yourself staring at a terminal where a Python script you're running suddenly stops without any errors or warnings, you're not alone. Many developers encounter this frustrating issue, especially when working with recursive functions, which tend to push Python's limits.

In this guide, we will dissect a common scenario involving a depth-first search (DFS) script that transitions an image into a binary style graphic, resembling islands and water. The code runs flawlessly for a while, then unexpectedly halts. Let's explore the reasons behind this behavior and how to solve it effectively.

Understanding the Problem

The primary issue stems from Python's inherent limitations with recursion. Python is not a functional programming language and has a default recursion limit set to 10,000 to avoid stack overflow—this limit is not arbitrary but due to a small stack size.

Key Symptoms of the Problem:

The script works up to a certain point before stopping.

No output or error messages appear when the execution is halted.

The exit message registered with atexit is never printed.

Now let's dive into the solution for this problematic situation.

Solution: Handling Large Recursion with Multithreading

The key to overcoming Python's recursion depth limitation lies in leveraging multithreading and adjusting the stack size. By executing your recursive function in a thread with a larger stack size, you can allow for deeper recursions without crashing.

Step-by-Step Guide

Step 1: Adjust Recursion and Stack Limits

At the very start of your script, you will need to import the necessary modules and set your limits as follows:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Wrap the Recursive Function

To facilitate running the recursive function in a thread, you need to wrap it in a new parent function. This allows you to call it appropriately from a new thread.

Step 3: Run the Parent Function in a Thread

At the end of your script, use the following command to start your thread with the parent function:

[[See Video to Reveal this Text or Code Snippet]]

Replace <your_parent_function> with the actual name of your parent function.

Final Code Example

Here’s a complete code snippet incorporating these changes:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the steps outlined above, you can successfully address the issue of Python scripts that stop executing unexpectedly when faced with large recursions. Utilizing multithreading allows your program to keep running even when it reaches the limit of standard recursion depth.

As you work on complex Python projects in the future, keep this approach in mind, especially when dealing with recursive functionalities. Happy coding!