Frank Sifei Luan

Frank Sifei Luan

I am a member of technical staff at xAI. I work across pretraining data, data infra, batch inference, and agentic search.

I obtained my Ph.D. in computer science from the University of California, Berkeley in 2024. I was advised by Professor Ion Stoica. My dissertation is on An Extensible Architecture for Distributed Heterogeneous Processing. Before that, I worked at Facebook from 2017 to 2019. I obtained my bachelor's degrees in computer science and statistics from the University of Chicago in 2017.

I am an instrument-rated private pilot with over 500 hours of flight experience.

2025–now

xAI

Member of Technical Staff

2024–2025

Anthropic

Member of Technical Staff

2023–2024

Wayo

Co-founder & CTO

2020–2024

UC Berkeley

Ph.D. in Computer Science

2017–2019

Facebook

Research Engineer

2014–2015

SketchMe

Co-founder & CTO

2013–2017

University of Chicago

B.S. in Computer Science & B.A. in Statistics

Publications

Exoshuffle: An Extensible Shuffle Architecture

Sifei Luan, Samyukta Yagati, Stephanie Wang, Sean Kim, Kenneth Lien, Isaac Ong, Tony Hong, SangBin Cho, Eric Liang, Ion Stoica

SIGCOMM 2023 (Sep 2023)

An extensible shuffle architecture that offers competitive performance and scalability as well as greater flexibility than monolithic shuffle systems.

Exoshuffle-CloudSort: The 2022 CloudSort Benchmark Winner

Sifei Luan, Samyukta Yagati, Stephanie Wang, Sean Kim, Kenneth Lien, Isaac Ong, Tony Hong, SangBin Cho, Eric Liang, Ion Stoica

arXiv (Jan 2023)

Winner of the 2022 CloudSort Benchmark (Indy category) for sorting 100TB data at $0.97/TB.

Balsa: Learning a Query Optimizer Without Expert Demonstrations

Zongheng Yang, Wei-Lin Chiang, Sifei Luan, Gautam Mittal, Michael Luo, Ion Stoica

SIGMOD 2022 (Jun 2022)

A query optimizer built by deep reinforcement learning.

Ownership: A Distributed Futures System for Fine-Grained Tasks

Stephanie Wang, Eric Liang, Edward Oakes, Ben Hindman, Sifei Luan, Audrey Cheng, Ion Stoica

NSDI 2021 (Apr 2021)

A decentralized object metadata ownership system for fine-grained distributed tasks.

AI in Software Engineering at Facebook

Johannes Bader, Sonia Seohyun Kim, Sifei Luan, Satish Chandra, Erik Meijer

IEEE Software (Feb 2021)

Three productivity tools that learn patterns from software artifacts that we deployed at Facebook.

🏆 2021 IEEE Computer Society IEEE Software Magazine Best Paper Award

NeuroCard: One Cardinality Estimator for All Tables

Zongheng Yang, Amog Kamsetty, Sifei Luan, Eric Liang, Yan Duan, Xi Chen, Ion Stoica

VLDB 2020 (Jun 2020)

A join cardinality estimator that builds a single neural density estimator over an entire database.

Aroma: Code Recommendation via Structural Code Search

Sifei Luan, Di Yang, Celeste Barnaby, Koushik Sen, Satish Chandra

OOPSLA 2019 (Oct 2019)

A code recommendation tool for big code corpora to improve developer productivity.

🏆 2019 ACM SIGPLAN Distinguished Paper Award

Retrieval on Source Code: A Neural Code Search

Saksham Sachdev, Hongyu Li, Sifei Luan, Seohyun Kim, Koushik Sen, Satish Chandra

MAPL 2018 (Jun 2018)

A natural language code search tool for big codebases.

Talks

Curry On 2019: Using ML for Code Discovery at Facebook

Sifei Luan, Celeste Barnaby

Jul 2019

We created two techniques that apply machine learning to code discovery problems: Neural Code Search (NCS) and Aroma.

F8 2019: Using Machine Learning for Developer Productivity

Johannes Bader, Satish Chandra, Sonia Seohyun Kim, Sifei Luan

May 2019

At Facebook, we use machine learning to discover patterns in code and build tools that improve developer productivity.

Posts

Posts coming soon.