Sam Lijin

Experience

Proposed, designed, and led a team of 3 to build a web experience for Check (both a web-only onboarding flow and SaaS offerings)
Proposed and built vulnerability scanning into Check, enabling it to compete with security products such as Snyk
Helped grow Check from <1K users to 90K+ users by focusing on product-led growth

Designed an incremental key rotation system to limit the global outage risk to Google SSO
Discovered and severed an undocumented Gmail serving dependency on Identity-internal systems

Metadata TTL system: backlog of XX trillion records, sustained 1M ops/sec, peaking at 3M ops/sec
- Designed and implemented a logging system with novel observability and privacy requirements
- Designed and implemented Jepsen-style testing to validate correctness guarantees
Datastore Migration: zero downtime, xM RPS and xxPB of data over xM customers and 36 datacenters
- Designed composite index migration, queue processing migration, progressive rollout, fast rollback, and disk stockout mitigations; implemented transaction log replay, state transitions, and dark launch process
- Designed and implemented end-to-end correctness and performance testing
Velocity improvements for 60-eng org
- Proposed and implemented automated rollbacks: got us out of a 3-month release freeze and prevented 5 outages over the next 6 months
- Proposed and implemented new development and release environments spanning 30+ microservices
Incident response for API proxy rollback affecting every Google Cloud service

Proposed and led execution of test coverage improvement strategy for a new control plane: reduced rollbacks and ensured strong consistency of a distributed cache serving xxM QPS
Designed and implemented automated performance regression testing for two critical serving paths
- Used to validate Google-wide rollout of AMD CPUs, by proving a 50p latency delta of <10µs
- Implemented on shared Borg (i.e. vulnerable to noisy neighbors) with <12% variance

Redesigned the Noogler training on Google-internal storage technologies & trained 2500+ Nooglers
Landed multiple google3-wide refactorings, each spanning xxK files (e.g. SWIG to CLIF)

Vanderbilt University (Nashville, TN) | May 2017 | B.S. in Computer Science, Mathematics, and Political Science

Stuyvesant HS (New York, NY) | 2013

C++, Java, Typescript, Javascript, Python, Bash; light experience with Rust, Golang, Scheme
gRPC, Bazel, React, Linux
Hobbies: climbing, skiing, photography