Multi Step Processes easy
A user uploads a large video file that needs to be transcoded (converted), which takes 5 minutes. Why is it bad practice to keep the HTTP connection open while the server processes the video?
- A HTTP cannot transfer large files.
- B The browser or network intermediaries (like Load Balancers) will likely timeout and drop the connection.
- C It consumes too much database storage.
- D Users prefer to stare at a loading spinner.
Answer: B. The browser or network intermediaries (like Load Balancers) will likely timeout and drop the connection.
Network connections are fragile. Keeping a synchronous connection open for minutes invites timeouts and failures. Ideally, the server accepts the upload, returns '202 Accepted', and processes the video in the background.
One system design question a day, with spaced repetition so the ones you miss come back.
Get the appRelated questions
- A user registration process involves two steps: inserting a row into the 'Users' database table and inserting a row into the 'Profiles' table. If the first insert succeeds but the second fails, the database is left in an inconsistent state. What mechanism prevents this?
- In a multi-step workflow across different services (Order Service -> Payment Service), you cannot use a single database transaction. If the Payment fails after the Order was created, how do you fix the Order state?
- You are writing a script to process 10,000 images. The script runs on a server that might restart unexpectedly. To ensure you don't have to start over from image #1 after a crash, what should you implement?
- A client app sends a 'Pay $50' request to your API. The server processes the payment but the network response is lost. The client automatically retries the request. What prevents the user from being charged $100?
- How does CDC (reading the database transaction log) solve the 'Dual Write' problem better than the Application-level Outbox pattern?
- A user reports an error in a process that spans 3 different microservices. The logs are scattered across different servers. What is the standard way to link these logs together?