Understanding asyncio Behavior in Jupyter vs. Script Execution

Explore why `asyncio` code runs smoothly in Jupyter notebooks but encounters errors in script files. Learn how to fix the `SyntaxError` for seamless execution.
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Understanding asyncio Behavior in Jupyter vs. Script Execution

As a Python programmer, you may have noticed that asyncio code behaves differently when executed in a Jupyter notebook compared to running it from a standalone script. If you've experienced the frustrating SyntaxError: 'await' outside function message while trying to run asynchronous code from a .py file, you're not alone. In this post, we will break down the causes behind this issue and provide a solution that allows your asynchronous functions to run smoothly in any environment.

The Problem

Imagine you have a piece of code designed to fetch data from multiple URLs concurrently. In this scenario, the code works perfectly inside a Jupyter notebook, allowing you to use await without issues. However, executing the same code from a script leads to an error, as the Python interpreter raises a SyntaxError. This inconsistency can be confusing and frustrating, especially when you want your code to run seamlessly in all environments.

Example Code That Causes the Issue

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

You might encounter an error such as:

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

Understanding the Cause

The root of the issue lies in the way the event loop is being instantiated and utilized. In Jupyter notebooks, the event loop runs in the background, allowing you to directly await tasks. However, this is not the case in a standalone script. Here’s where the problem arises:

Attempting to use await at the top level in a script is not allowed by Python’s syntax rules.

Solution: Refactoring Your Code

Here’s the updated code:

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

Key Changes Made

Removed Loop Parameter in ClientSession: Instead of passing the loop object, we let asyncio handle it automatically.

Conclusion