Fast API – Gunicorn vs Uvicorn
What is FastAPI?
FastAPI is a modern web framework specifically crafted for Python 3.8 and newer versions, leveraging standard Python-type hints for API creation. It is constructed upon the robust bases of Starlette and Pydantic, offering a range of notable advantages. The key features of FastAPI include:
- Very high performance.
- Faster to code.
- Fewer bugs.
- Easier to learn and use.
- Takes less time to read the docs.
What is Uvicorn?
Uvicorn is the recommended lightweight ASGI server for FastAPI, optimized for asynchronous programming. Known for its exceptional performance in handling asynchronous code, it’s favored by FastAPI users for its user-friendly design suitable for both development and production environments. Uvicorn also offers a convenient –reload option, automatically restarting the server upon detecting code changes, proving particularly valuable in the development phase.
Example:
Python3
import uvicorn from fastapi import FastAPI app = FastAPI() @app .get( "/" ) async def index(): return { "message" : "Hello World" } |
run the below command in terminal
uvicorn main:app --reload
Output:
Message: Hello World!!!!
What is Gunicorn ?
Gunicorn, a WSGI server, can be used alongside Uvicorn to serve FastAPI applications, despite not being specifically designed for ASGI. Commonly paired with frameworks like Flask and Django, Gunicorn boasts a mature ecosystem and is favored for production deployments. However, its synchronous nature, processing one request at a time per worker process, necessitates combining it with Uvicorn for optimal utilization of asynchronous programming in FastAPI.
Example:
Python3
import uvicorn from fastapi import FastAPI app = FastAPI() @app .get( "/" ) async def index(): return { "message" : "Hello World" } |
run the below command
gunicorn main:app --reload --log-level info --workers 3 --bind 0.0.0.0:8000
Output:
Note: Gunicorn works in docker or linux os systems, in windows it might not work.
Message: Hello World!!!!
Difference between Gunicorn vs Uvicorn
Here are the differences based on some features between uvicorn and Gunicorn.
Features |
Uvicorn |
Gunicorn |
---|---|---|
Server Type |
ASGI (Asynchronous Server Gateway Interface) |
WSGI (Web Server Gateway Interface) |
Suitable For |
Asynchronous web applications (AsyncIO) |
Synchronous web applications (Flask, Django) |
Development |
Often used during development and testing |
Typically used in production deployments |
Auto-reload |
Can auto-reload application on code changes |
Not designed for auto-reloading in development |
Concurrency |
Single-process server by default |
Can spawn multiple worker processes |
Production Use |
Not ideal for high-traffic production |
Designed for production with multiple workers |
Frameworks |
FastAPI, Starlette, etc. |
Flask, Django, Pyramid, etc. |
Deployment |
May require a reverse proxy in production |
Suitable for directly serving web applications |
Scalability |
Limited in handling concurrent connections |
Efficient at handling a large number of connections |
Adaptability |
Can run WSGI applications with adapter |
Designed specifically for WSGI applications |
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