Resolving asyncpg Error: cannot perform operation: another operation is in progress

In this guide, we'll discuss the common `asyncpg` error and provide a clear solution to fix the issue of running multiple operations concurrently on the same database connection.
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Understanding the Problem

When working with asynchronous database operations in Python, particularly with the asyncpg library, you may encounter the following error:

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

This error typically arises when multiple tasks attempt to use the same database connection at the same time. In this guide, we'll delve into why this issue occurs and how to resolve it effectively.

Why Does the Error Occur?

The root cause of this error is related to how database connections work with asyncpg. Connections are stateful, meaning that they cannot handle multiple operations simultaneously. If you assign the same connection to multiple coroutines, you'll face a conflict when one coroutine tries to use the connection while another is already using it.

Solution: Use Local Variables Instead of Instance Variables

Updated fetch_item Code

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

Key Changes Made:

Releasing the Connection: After executing the query, the connection is safely released back to the pool, maintaining the efficiency of connection reuse.

Conclusion

By implementing this simple yet crucial modification in your code, you can effectively solve the asyncpg error of trying to perform multiple operations on a single connection. Employing local connection variables instead of instance variables allows each coroutine to work independently without conflict.

This adjustment will enhance the stability of your asynchronous operations in a FastAPI context and improve efficiency when interacting with your database. If you continue to encounter issues, ensure all other parts of your asynchronous code are designed to handle connections correctly, following similar principles.

Now you can enjoy smooth, error-free database operations with your asyncpg implementation. Happy coding!