Workload isolation: 3 real scaling case studies
3 of the 94 engineering write-ups in our database are tagged with the technique "workload isolation". They come from 3 companies (GitHub, Netflix and OpenAI) and were published in 2026. Stack that shows up most often in these stories: Kubernetes (2). Often combined with caching (2) and read replicas (2). 3 of the 3 state concrete scale numbers, for example "millions of containers launched per week" (Netflix). Each card below links to our short summary and the original post.
Single-tenant Titus: VM-level isolation on a multi-tenant container platform
Titus, Netflix's Kubernetes-based container platform, launches millions of containers a week on tens of thousands of EC2 instances, packing many teams onto shared hosts. cgroups can't fence last-level cache, memory bandwidth or the global lock in HTB network shaping, so a small-packet flood from one container could starve its neighbors, and stateful streaming jobs like Flink would fall behind and need minutes to catch up. After ruling out microVMs (Firecracker, Kata), gVisor and moving teams to plain EC2, Netflix added an allowlisted single-tenant mode: the federation layer tags eligible tasks, the autoscaler launches the smallest instance that fits each one just in time, and anti-affinity, taints, no preemption and no repacking keep it alone on its host, all behind the same Titus API. Flink, streaming connectors and telemetry pipelines now report stable operation, and the shared fleet packs more densely because sensitive workloads no longer need anti-affinity spreading. The cost is slower launches, since every task waits for its own instance, and fixed host overhead that can take tens of percent of a small node.
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.
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.