AnupTechTips - Designing Scalable Systems and AI Architecture

Exactly-Once Is a Myth: Idempotent Consumers in Practice

Last Updated on: November 4, 2026 by Anup Das

Exactly-once is a myth: an idempotent consumer in Python, killed 100 times, 0 duplicate credits

Kafka’s exactly-once stops at Kafka’s edge, so here’s a Python idempotent consumer with an inbox table, hard-killed 100 times mid-stream to count duplicates and losses.

Transactional Outbox Pattern in Python: Never Lose an Event

Published on: November 4, 2026 by Anup Das

Transactional outbox pattern in Python: an outbox table feeding three SKIP LOCKED relay workers and Kafka

Your order saved, but the event never reached Kafka. Build the transactional outbox pattern in Python and Postgres: a SKIP LOCKED relay that’s safe on several workers, fixes for ordering and cleanup, and lessons from seven teams that hit the dual write.

LLM Gateway Architecture: Routing, Caching, Fallbacks and Budgets

Last Updated on: October 15, 2026 by Anup Das

LLM gateway architecture: routing, fallbacks and budgets

An LLM gateway is failure handling on one request path: routing, retries, a circuit breaker, streaming fallbacks and per-tenant budgets, with a FastAPI gateway you can run and the numbers its tests measured.

Rate Limiting Algorithms: Token Bucket vs Sliding Window

Last Updated on: October 16, 2026 by Anup Das

Six rate limiting algorithms run through the same 100-a-minute limit and the same traffic, with what each let through, what it costs in Redis, and atomic Lua code for Python.

Idempotency Keys: How to Make Retries Safe in Distributed Systems

Last Updated on: November 4, 2026 by Anup Das

Idempotency keys: a POST and its retry with the same key produce one 201 response

A timeout can’t tell you whether the card was charged, so an idempotency key lets the retry get the original result back instead of charging twice.

px.imshow Heatmap Squashed? Fix the Aspect Ratio in One Line

Last Updated on: September 30, 2026 by Anup Das

px.imshow aspect ratio: a squashed heatmap strip with aspect equal becomes a full heatmap with aspect auto

px.imshow keeps every cell square by default, so a wide matrix becomes a thin strip. One argument fixes it, and here is what else to know about size, zoom and go.Heatmap.