What is the purpose of the `highWaterMark` option when creating a readable stream?

0-2 years experience

1. 1You need to read a large file line by line using a readable stream. How would you choose the highWaterMark, and what would happen if you set it too low?
2. 2If you create a readable stream without specifying highWaterMark, what default behavior should you expect when data arrives faster than you consume it?

2-5 years experience

1. 1Your service streams JSON objects from a database to HTTP clients and you start seeing backpressure warnings. How would you adjust highWaterMark to mitigate this, and what trade‑offs are you making?
2. 2During a load test, the memory usage of a Node.js process spikes while streaming video. Explain how highWaterMark could be contributing and how you'd debug it.

5-8 years experience

1. 1Design a streaming pipeline that ingests data from a TCP socket, transforms it, and writes to the file system. Discuss how you would set highWaterMark at each stage to balance throughput and memory under bursty traffic.
2. 2You need to support both low‑latency real‑time analytics and high‑throughput batch processing in the same service. How would you use highWaterMark differently for each path, and what impact does it have on backpressure propagation?

8+ years experience

1. 1Your organization is migrating a legacy monolithic file‑processing service to a microservices architecture that uses Node.js streams across network boundaries. What architectural considerations around highWaterMark would you raise to ensure compatibility, observability, and future scalability?
2. 2When defining a shared streaming library used by multiple teams, how would you expose highWaterMark configuration to balance default safety with the ability for power users to tune performance, and what governance policies would you put in place?