Caching: 8 real scaling case studies
8 of the 73 engineering write-ups in our database are tagged with the technique "caching". They come from 8 companies (Canva, Discord, Figma, GitHub, Meta and 3 more) and were published between 2013 and 2026. Stack that shows up most often in these stories: Java (2), Kubernetes (2), MySQL (2) and PostgreSQL (2). Often combined with read replicas (2) and workload isolation (2). 5 of the 8 state concrete scale numbers, for example "473.3 billion Git events/month" (GitHub). Each card below links to our short summary and the original post.
Building Git infrastructure for agent-scale development
GitHub explains why agent workloads strain Spokes, which keeps five durable copies of each repo on fileserver disks, so every added read replica slows writes. The new design coordinates only the ref update, moves compaction and GC to separate workers, and separates storage from compute: Azure Blob Storage holds the authoritative data while lightweight caching workers serve reads.
Session revocations at scale
Canva keeps 12 hours of session revocations in memory on every gateway, but hundreds of pods each loading over a million revocations from MySQL on deploy caused a stampede on the database. A worker now packs revocations into sorted 16-byte records in 30-minute chunks on S3, using conditional PUTs for optimistic concurrency and ZooKeeper leader election to avoid conflicts, and reaches over 2,000 revocations per second. Gateways binary-search the downloaded bytes directly and poll with conditional GETs, which shrank the cache by 87.5% and cut the revocation database down to two read replicas kept for redundancy.
Client-Side Load Balancing at a Million Requests Per Second
Zalando moved the internal fan-out of its Product Read API off the shared Skipper ingress into an in-process JVM load balancer that rebuilds the same xxHash64 consistent-hash ring. They added N-ring fade-in so new pods warm only the products they will keep, bounded load based on occupancy (Little's Law) weighted by latency, and a capped ring walk. Pods ran more evenly, the autoscaler target rose from 50% to 65% CPU, and the fleet shrank by over 25%.
Scaling PostgreSQL to power 800 million ChatGPT users
OpenAI runs ChatGPT on a single-primary Postgres with nearly 50 global read replicas. Reads are offloaded, write-heavy shardable workloads move to Cosmos DB, and PgBouncer, cache leasing and multi-layer rate limits keep the primary safe.
LiveGraph: real-time data fetching at Figma
Figma built LiveGraph, which tails the Postgres replication log so its UI can subscribe to live query results.
Why Discord is switching from Go to Rust
Discord rewrote its Read States service from Go to Rust to get rid of garbage-collection latency spikes in a large in-memory cache.
Stack Overflow: The Architecture - 2016 Edition
A tour of how Stack Overflow serves a huge site from a small number of powerful servers with heavy caching.
TAO: The power of the graph
TAO is Facebook's geo-distributed graph cache over sharded MySQL, serving the social graph at more than a billion reads per second.