Gunicorn for production serving in Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What happens when you run Gunicorn with multiple workers?

You start a Flask app using Gunicorn with the command gunicorn -w 4 app:app. What is the main effect of specifying -w 4?

A Gunicorn runs 4 worker processes to handle requests concurrently.

B Gunicorn runs 1 worker process but limits requests to 4 per second.

C Gunicorn runs 4 threads inside a single process to handle requests.

D Gunicorn runs 4 instances of the Flask app in the same process.

💡 Hint

Think about how Gunicorn manages multiple requests in production.

Gunicorn uses multiple worker processes to handle requests in parallel. The -w 4 option starts 4 separate worker processes.

📝 Syntax

intermediate

Identify the correct Gunicorn command to serve a Flask app on port 8080

You want to serve your Flask app using Gunicorn on port 8080. Which command is correct?

A gunicorn -p 8080 app:app

B gunicorn --port 8080 app:app

C gunicorn --host 0.0.0.0 --port 8080 app:app

D gunicorn --bind 0.0.0.0:8080 app:app

💡 Hint

Check Gunicorn's option for binding to an address and port.

The --bind option specifies the address and port Gunicorn listens on. The correct syntax is --bind 0.0.0.0:8080.

🔧 Debug

advanced

Why does Gunicorn fail to start with this command?

You run gunicorn app.py to start your Flask app but Gunicorn fails with an error. What is the likely cause?

A Gunicorn cannot run Flask apps without a <code>run()</code> call.

B Gunicorn requires the <code>--bind</code> option to specify a port.

C Gunicorn expects the app as <code>module:app</code>, not a filename.

D Gunicorn needs the app to be named <code>application</code> instead of <code>app</code>.

💡 Hint

Consider how Gunicorn imports the Flask app.

Gunicorn requires the app to be specified as module_name:app_variable. Using a filename alone causes an import error.

❓ state_output

advanced

What is the effect of setting the --timeout option in Gunicorn?

You run Gunicorn with --timeout 30. What happens if a worker takes longer than 30 seconds to respond?

A Gunicorn queues the request until the worker finishes.

B Gunicorn kills the worker and restarts it to free resources.

C Gunicorn ignores the timeout and waits indefinitely.

D Gunicorn logs a warning but keeps the worker running.

💡 Hint

Think about how Gunicorn handles stuck or slow workers.

The --timeout option sets the max time a worker can take. If exceeded, Gunicorn kills and restarts the worker to keep the app responsive.

🧠 Conceptual

expert

Why is Gunicorn preferred over Flask's built-in server in production?

Choose the best reason why Gunicorn is used to serve Flask apps in production instead of Flask's built-in server.

A Gunicorn handles multiple requests concurrently with worker processes, improving performance and reliability.

B Flask's built-in server does not support Python 3.12 and newer versions.

C Gunicorn automatically converts Flask apps to asynchronous code for faster execution.

D Flask's built-in server requires a database connection, while Gunicorn does not.

💡 Hint

Consider concurrency and stability in production environments.

Flask's built-in server is single-threaded and not designed for production. Gunicorn uses multiple worker processes to handle many requests safely and efficiently.