Profiling Flask applications - Mini Project: Build & Apply

Profiling Flask applications

📖 Scenario: You are building a small Flask web application to understand how to profile its performance. Profiling helps find slow parts so you can improve your app.

🎯 Goal: Create a simple Flask app with one route, add a configuration variable to enable profiling, use Flask's built-in profiler middleware, and finally run the app with profiling enabled.

📋 What You'll Learn

Create a Flask app instance named app

Add a route / that returns the text 'Hello, Profiling!'

Create a configuration variable PROFILE set to True

Wrap the Flask app with ProfilerMiddleware from werkzeug.middleware.profiler when PROFILE is True

Run the Flask app with app.run()

💡 Why This Matters

🌍 Real World

Profiling helps developers find slow parts of their Flask web apps so they can improve speed and user experience.

💼 Career

Knowing how to profile Flask apps is useful for backend developers to optimize performance and troubleshoot bottlenecks.

1

Create the Flask app and route

Import Flask from flask. Create a Flask app instance called app. Add a route for '/' that returns the string 'Hello, Profiling!'.

Flask

from flask import Flask

# Create the Flask app instance
# Your code here

Need a hint?

Use app = Flask(__name__) to create the app. Use @app.route('/') to define the route. The function should return the exact string.

2

Add a configuration variable to enable profiling

Add a configuration variable called PROFILE to the app.config dictionary and set it to True.

Flask

from flask import Flask

app = Flask(__name__)
app.config['PROFILE'] = True  # Your code here

@app.route('/')
def home():
    return 'Hello, Profiling!'

Need a hint?

Use app.config['PROFILE'] = True to add the config variable.

3

Wrap the app with ProfilerMiddleware when profiling is enabled

Import ProfilerMiddleware from werkzeug.middleware.profiler. If app.config['PROFILE'] is True, wrap app.wsgi_app with ProfilerMiddleware passing app.wsgi_app and stream=None.

Flask

from flask import Flask
from werkzeug.middleware.profiler import ProfilerMiddleware

app = Flask(__name__)
app.config['PROFILE'] = True

# Wrap app.wsgi_app with ProfilerMiddleware if profiling is enabled
# Your code here

@app.route('/')
def home():
    return 'Hello, Profiling!'

Need a hint?

Use an if statement to check app.config['PROFILE']. Wrap app.wsgi_app with ProfilerMiddleware.

4

Run the Flask app

Add the code to run the Flask app by calling app.run() at the bottom of the file.

Flask

from flask import Flask
from werkzeug.middleware.profiler import ProfilerMiddleware

app = Flask(__name__)
app.config['PROFILE'] = True

if app.config['PROFILE']:
    app.wsgi_app = ProfilerMiddleware(app.wsgi_app, stream=None)

@app.route('/')
def home():
    return 'Hello, Profiling!'

# Run the Flask app
# Your code here

Need a hint?

Use the standard Python check if __name__ == '__main__': and call app.run() inside it.