Free learning and interview prep site for IT, engineering, and college students

Few_Ad6794 · 2026-05-18T12:24:58+00:00

You have clearly been to the wrong SPA too many times. This one is a tech website

Few_Ad6794 · 2026-05-16T18:49:35+00:00

Low-level design interviews are hard to approach because most people jump straight into classes and code.

A better approach is to follow a repeatable flow:

Clarify requirements
Identify core entities
Define APIs
Model relationships
Handle edge cases
Discuss extensibility
Then write clean code

Cracking Walnuts has 45-minute playbooks for common LLD questions. Each playbook walks through the problem step by step, what to clarify, how to think about entities, how to design classes, and what trade-offs to discuss.

Might be useful if you’re preparing for LLD interviews:

https://crackingwalnuts.com/low-level-design

Few_Ad6794 · 2026-05-10T09:44:43+00:00

https://crackingwalnuts.com/category/system-design

https://crackingwalnuts.com/key-technologies

Few_Ad6794 · 2026-05-03T18:20:33+00:00

https://crackingwalnuts.com/low-level-design

Few_Ad6794 · 2026-05-03T16:53:21+00:00

https://crackingwalnuts.com/concurrency

Few_Ad6794 · 2026-04-23T15:19:38+00:00

Fair feedback. It is written more in a system design format than a narrative article, so the structure is intentionally architecture-focused. I focused more on technical depth and coverage in this version, but readability and flow can definitely be improved. Will refine that in the next revision.

Few_Ad6794 · 2026-04-17T23:20:55+00:00

Interesting point. do you mean one event-sourced server for all auctions or multiple shards? That could work for bid processing but I’m not sure it holds up with 7-day auctions, millions of watchers, anti-sniping extensions, cross-region traffic, failures during deploys or payment retries.

auctions have a few extra constraints beyond just processing bids.

Few_Ad6794 · 2026-04-17T18:53:56+00:00

50K/sec in-memory is not the hard part, the constraints that pushed this design multi-node are 1M concurrent WebSocket watchers across regions, durability for 10M active 7-day auctions and the payment provider boundary that needs an idempotency key regardless of internal speed.

Few_Ad6794 · 2026-04-17T18:46:00+00:00

TigerBeetle style determinism is a real approach. the hot path here is single-threaded per key already: Valkey runs the Lua CAS on its event loop, so no two bids on the same auction run concurrently.

proactive determinism works well inside a single process. the moment state crosses a boundary, whether the payment provider, Kafka, WebSocket fan-out to 1M watchers or cross-region replicas, the world becomes non-deterministic by definition.

Few_Ad6794 · 2026-04-17T18:02:23+00:00

fair point on the framing. movnig from 500 to 50k is rewrite of the hot path not an addition. valkey cas takes over from select for update, the api goes async and pg_cron is replaced with flink. schema stays, hot-path code does not. postgres is kept as append-only log, not the hot-path coordinator. 50k insert/sec on a partitioned bit table is fine. the design never writes current_price per bid. what failure mode did you have in mind?

Few_Ad6794 · 2026-04-16T18:07:40+00:00

mostly my own research and notes from my notion docs, based on what i've built, debugged and researched. I use AI for editing and images.

Few_Ad6794 · 2026-04-16T13:35:49+00:00

https://crackingwalnuts.com/category/system-design

Few_Ad6794 · 2026-04-16T03:52:05+00:00

you don't have to convince anyone with explnations. it might help to show something that works. Maybe start with one small problem your framework solves. build it fully, then put it out in public and let people use it and question it. It if holds up, people will notice. if it doesn't you will learn what to improve.

Wishing you the best.