README — Backend notes & system design

Pinned

Headline

#Astro#SSG#MDX

Why I chose Astro for a technical blog

After three rewrites in four years, I finally settled on Astro. Here is why the islands architecture wins for a content-first site, and what I gave up in exchange.

01 / 04

Why I chose Astro for a technical blog

A field guide to Postgres locks

The TCP handshake, one byte at a time

How many shards? A sizing framework for Elasticsearch

Newest first

Latest

BackendPython / FastAPI

Dataclasses vs Pydantic vs attrs — pick one

After using all three in production, here is my decision tree. Short version: it depends on whether the thing crosses a trust boundary.

2026-04-02·9 min read

CS데이터베이스

B-trees vs LSM-trees, visually

Why Postgres picks one and RocksDB picks the other. With diagrams that actually explain the tradeoff instead of repeating the cliche.

2026-03-30·11 min read

DevOps컨테이너 / K8s

Dockerfile caching is not what you think it is

Three subtle ways your Dockerfile invalidates cache and slows every CI run — and the one-line fix for each.

2026-03-28·7 min read

CS시스템 아키텍처

Dijkstra revisited — A* is not always better

When the heuristic is expensive, plain old Dijkstra wins. A benchmark on three real road-network datasets.

2026-03-25·10 min read

CS시스템 아키텍처

Pair-coding with Claude — the three-prompt pattern

Plan → Draft → Review, each with its own system prompt. It turns AI coding from slot-machine into an actual process.

2026-03-20·8 min read

BackendJava / Spring

Virtual threads are not free threads

Project Loom landed, but synchronized blocks still pin. Here is how I instrumented a real service to find pinning hotspots.

2026-03-18·13 min read

Most read

Headline

Why I chose Astro for a technical blog

Latest

Dataclasses vs Pydantic vs attrs — pick one

B-trees vs LSM-trees, visually

Dockerfile caching is not what you think it is

Dijkstra revisited — A* is not always better

Pair-coding with Claude — the three-prompt pattern

Virtual threads are not free threads

Popular

Every race condition I have ever shipped

Indexing 101 — stop guessing, start EXPLAINing

Kafka exactly-once is real, but not free

Head-of-line blocking, from TCP to HTTP/3

Big-O in interviews — what is really being asked

Why I chose Astro for a technical blog