Leveraging Background Tasks in FastAPI: Enhancing Performance and Responsiveness

TLDR;

Utilizing FastAPI’s BackgroundTasks feature allows for the efficient management of long-running processes. By moving these tasks to the background, applications can maintain responsiveness and provide a seamless user experience, all without compromising performance or scalability.

Introduction

FastAPI, a leading-edge web framework for crafting APIs in Python, boasts superior speed, user-friendly attributes, and outstanding asynchronous capabilities. Among these, a standout feature is FastAPI’s BackgroundTasks — an innovative tool engineered for managing long-running, time-consuming tasks without inhibiting the primary application operations.

In this blog post, we will dig deep into FastAPI’s BackgroundTasks, shedding light on how they can significantly improve application performance and responsiveness. We’ll chronicle this journey through a step-by-step enhancement of a simple FastAPI application, demonstrating the transformation when long-running tasks are meticulously offloaded to the background.

Creating Simple FastAPI application

In our given Python code snippet, we showcase a basic FastAPI application with a key challenge — handling a long-running operation, simulated by very_long_task(). This function introduces a delay, demonstrating how a time-consuming task can block an application.

import time
import uvicorn
from fastapi import FastAPI

app = FastAPI()

def very_long_task():
   print("Starting very long task")
   time.sleep(5)
   print("Ending very long task")

@app.post("/long_task")
def long_task_endpoint():
   print("Entering endpoint ")
   very_long_task()
   print("Exiting endpoint ")
   return {"status": "very_long_task ended"}

if __name__ == "__main__":
   uvicorn.run("app:app", host="0.0.0.0", port=8000, reload=True)

When calling the long_task endpoint, you'll observe the following log sequence:

Entering endpoint
Starting very long task
Ending very long task
Exiting endpoint

The snag in this implementation is that the connection to our application hangs during the execution of very_long_task. Keeping…