How can you handle cleanup operations when working with streams?

0-2 years experience

1. 1You need to read a large file line by line using a readable stream and write each line to another file. How would you ensure the file descriptors are closed properly even if an error occurs while processing?
2. 2When you pipe a readable stream into a writable stream, what steps do you take to clean up the streams if the client disconnects before the transfer finishes?

2-5 years experience

1. 1We have a microservice that processes incoming HTTP request bodies as streams and forwards them to a downstream service. Yesterday the service started leaking file descriptors. Walk me through how you would investigate and fix the cleanup logic.
2. 2Explain why calling stream.destroy() in an error handler might be necessary, and what additional cleanup you might need to perform for a Transform stream that holds a timer.

5-8 years experience

1. 1Our real-time analytics pipeline uses a chain of Transform streams that run in a cluster of Node processes. At high load we see occasional memory bloat due to streams not being reclaimed. How would you redesign the cleanup strategy to be robust at scale?
2. 2When integrating with a third‑party library that returns a custom stream, you need to guarantee that all underlying resources (e.g., sockets, file handles) are released when the stream ends or errors. What patterns would you use to enforce this across many such integrations?

8+ years experience

1. 1We are migrating a legacy monolith that uses many ad‑hoc file streams to a new event‑driven architecture built on Node streams and a message broker. What architectural guidelines would you set to ensure consistent cleanup and avoid resource leaks across teams?
2. 2Consider a multi‑tenant SaaS platform where each tenant's data is streamed from S3 through a Node service into a processing pipeline. How would you design a global cleanup policy that handles tenant‑specific failures, back‑pressure, and ensures no dangling resources remain after a tenant is de‑provisioned?