Скачать или смотреть How to Properly Pass Arguments to Threads in Python

Learn how to fix common threading errors in Python, specifically when passing arguments to a thread with practical examples and solutions.
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Understanding Thread Arguments in Python

If you're diving into multithreading with Python, you've likely encountered some bumps along the way. One common issue you'll face when trying to create threads is how to properly pass arguments to the functions that threads will execute. Today, we'll be exploring the common errors associated with this and how to fix them.

The Problem

Let's examine a situation where an error arises when you attempt to pass arguments to a thread. Below is an example code snippet that demonstrates the problem:

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

When you run this code, you might encounter an error similar to this:

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What's Going Wrong?

The primary issue here is the way the target argument is being defined. Instead of passing the reference to the function (get_controller), you're actually calling the function immediately by adding parentheses (). This means that the function is executed right away rather than being set up as the target for the thread, resulting in the error since it's missing the required argument q.

The Solution

To resolve this issue, we need to set the target to the function itself without calling it. Here's how you can fix the code:

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

Breakdown of the Solution

Correct Target Setting: Instead of target=get_controller(), you should use target=get_controller. This tells Python that you're passing a reference to the function, not calling it right away.

Arguments with args: The args parameter should still contain a tuple of arguments that will be passed to the target function when the thread starts. In this case, args=(q,) is perfect as you're only passing one argument, which is the queue q.

Starting the Thread: Don’t forget to start your thread after you create it with the start() method:

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

Complete Example

Here’s a complete, corrected version of the code:

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

Conclusion

In summary, when working with threading in Python, it’s essential to understand how to properly pass functions and arguments. Always remember to set the target to the function's reference without parentheses, ensuring to pass any additional arguments correctly through the args parameter.

By following these guidelines, you can create more reliable multithreaded applications using Python! If you encounter any other threading challenges, feel free to share, and we can help explore solutions together.