FastAPI Asynchronous Tasks: Handling Time-Consuming Operations with BackgroundTasks

In web development, directly handling time-consuming operations (such as sending emails and generating reports) in API endpoints will block user waiting and affect experience. FastAPI's `BackgroundTasks` can execute such tasks asynchronously after the request response, avoiding blocking. `BackgroundTasks` is a class provided by FastAPI that automatically executes background tasks after the request processing is completed without blocking the interface response. It only requires three steps: import `BackgroundTasks`, declare the `bg` parameter in the route function, and register the time-consuming function and parameters through `bg.add_task()`. Example: Simulating the generation of a large file (taking 5 seconds). After the user submits the request, the interface immediately returns success, and the file generation is completed asynchronously in the background. Key points: Tasks are executed after the response, support positional/keyword parameters and sequential execution, suitable for I/O-intensive tasks (such as file reading/writing), not suitable for CPU-intensive tasks; exceptions are not caught, and task failures need to be handled by oneself; unexecuted tasks will be lost when the application restarts or crashes, so it is not suitable for persistent tasks. `BackgroundTasks` is lightweight and easy to use, improving user experience through quick responses, and is suitable for non-critical path time-consuming operations.