Juncheng Yang

Assistant Professor (Starting Fall 2025)

School of Engineering and Applied Science, Harvard University

juncheng # g.harvard.edu

150 Western Ave, Allston, MA, 02134

I am an Assistant Professor in the Computer Science Division in School of Applied Science and Engineering at Harvard University.

I am broadly interested in storage systems, data management and machine learning systems with particular interests on workload analysis, efficient storage, and sustainable system design. I like in-depth measurement and analysis to get deep understanding of systems and algorithms in the real world.

My works have received best-paper awards at NSDI'24, NSDI'21, SOSP'21, and SYSTOR'16 and have been deployed in production at Google, VMware, Twitter, Redpanda, Momento with many open-source libraries contributed by the community. My research has been sponsored by Meta, Google Cloud, and AWS. I am a 2020 Meta Fellow, a 2023 Google Cloud Research Innovator, and a 2023 Rising Star in Machine Learning and Systems.

I am looking for self-motivated Ph.D. students and Postdocs starting Fall 2025. I will also host two undergraduate students. If you are interested in working with me, please send me an email with your transcript and CV.

News [all news]

04/2024 - SIEVE received a community award at NSDI'24, was featured on TLDR newletter and discussed in a a blog post by Marc. Many open-source libraries (in more than 12 languges) are available on GitHub.
12/2023 - S3-FIFO was discussed in Aleksey's Online Reading Group, it has been covered by blogs in English, Chinese, Korean, and Japanese, used in course reading materials at UIUC CS525, and implemented at Google, VMware, Redpanda and in many open-source libraries and systems.
08/2023 - Recognized as a Rising Star in machine learning and systems.
08/2023 - 10/2023 Invited to talk about S3-FIFO at Cloudflare, Alluxio, VMware, Kuaishou, MSRA, USTC, Tsinghua University, WOS conference.
05/2023 - Honored to be a Google Cloud Research Innovator with funding from Google Cloud.
10/2022 - 02/2023 - Invited to talk about LESSCache at VMware, Meta and Oracle.
10/2022 - Invited speaker to talk about ubiquitous caching at QCon SF .
09/2020 - Gave a keynote talk together with Yao Yue at SNIA SDC on using PMEM for caching

Research Areas and Interests

Storage systems and machine learning systems with a focus on efficiency, scalability and robustness:

Efficient and scalable cache management systems

Measurement studies [OSDI'20, TOS'21][HotOS'23]
New cache system designs [NSDI'21][SOSP'21, TOS'22][EuroSys'23]
New replacement algorithm designs [SOSP'23][NSDI'24]

Robust and reliable cache/storage management and machine learning systems [OSDI'20][NSDI'22][VLDB'23]
New approaches to make machine learning practical for storage systems (machine learning for systems) [FAST'23][SOCC'17]
Performance optimization and sustainability of microservices and serverless architecture [SOCC'23]
Reliable large model inference on wimpy hardware (system for machine learning)

Research Highlights

SIEVE (NSDI'24): the first cache eviction algorithm simpler than LRU but yet more effective than state-of-the-art algorithms for web caches. Implemented in many open-source libraries, e.g., Golang, Python, JavaScript, Rust, Java, Swift, Ruby, Nim, and Zig.
S3-FIFO (SOSP'23): a simple and scalable cache eviction algorithm composed of only FIFO queues. Implemented or deployed at companies including Google, VMware and Redpanda, and open-source libraries, including otter, quick-cache, and spica.
GL-Cache (FAST'23): my exploration on bringing low-overhead machine learning to caching.
Segcache (NSDI'21) received a best-paper award, and deployed at Twitter and Momento.
Kangaroo (SOSP'21) received a best-paper award at SOSP'21.

Ph.D. Students

Master Students

Frank Chen (2023 Carnegie Mellon University): won the second place in ACM student research competition

Undergraduate Students

Bob Chen (2023-2024 Carnegie Mellon University)
Helen Wang (2024 Carnegie Mellon University)

Alumni

Jonathan Chiu (2021-2023 Carnegie Mellon University)
Ziming Mao (2022 Yale University): published a paper at FAST'23
Emily Zhang (2023 Carnegie Mellon University)
YiYan Zhai (2023 Carnegie Mellon University)
Parinay Chauhan (2023 IIT)

Selected Publications [Google Scholar]

SIEVE: Cache eviction can be simple, effective, and scalable.
Juncheng Yang, Yazhuo Zhang, Yao Yue, Ymir Vigfusson, K. V. Rashmi.
USENIX ;login: , 2024
SIEVE is Simpler than LRU: an Efficient Turn-Key Eviction Algorithm for Web Caches. [website] [blog] [pdf] [slides]
Yazhuo Zhang*, Juncheng Yang* (corresponding author), Yao Yue, Ymir Vigfusson, K. V. Rashmi.
The 20th USENIX Symposium on Networked Systems Design and Implementation (NSDI), 2024
SIEVE receives the community (best paper) award
Featured on TLDR newletter, blog coverage: Marc from AWS, blog post in Korean.
Independent implementations and evaluation: golang-fifo, use in DNSCrypt.
Open-source libraries (not an extensive list): Golang, Python, JavaScript, Rust, Java, Swift, Ruby, Nim, Zig.
FIFO queues are all you need for cache eviction. [website] [blog] [pdf] [slides] [video]
Juncheng Yang, Yazhuo Zhang, Ziyue Qiu, Yao Yue, K. V. Rashmi.
The 29th ACM Symposium on Operating Systems Principles (SOSP), 2023
Will be discussed in Aleksey's Online Reading Group. Covered in blog [1], [2], [3] in Korean, [4] in Chinese, [5] in Japanese, newsletters [1], [2] .
Open-source libraries (not an extensive list): Rust, Golang, JavaScript, Python, C++.
FIFO Can be Better than LRU: the Power of Lazy Promotion and Quick Demotion. [pdf] [slides]
Juncheng Yang, Ziyue Qiu, Yazhuo Zhang, Yao Yue, K. V. Rashmi.
The 19th Workshop on Hot Topics in Operating Systems (HotOS), 2023
GL-Cache: Group-level learning for efficient and high-performance caching. [pdf] [slides]
Juncheng Yang, Ziming Mao, Yao Yue, K. V. Rashmi.
The 21st USENIX Conference on File and Storage Technologies (FAST), 2023
FrozenHot Cache: Rethinking Cache Management for Modern Hardware. [pdf] [slides]
Ziyue Qiu, Juncheng Yang, Juncheng Zhang, Cheng Li, Xiaosong Ma, Qi Chen, Mao Yang, Yinlong Xu.
The European Conference on Computer Systems (EuroSys), 2023
Efficient Fault Tolerance for Recommendation Model Training via Erasure Coding. [pdf]
Tianyu Zhang, Kaige Liu, Jack Kosaian, Juncheng Yang, K. V. Rashmi.
49th International Conference on Very Large Databases (VLDB), 2023
Latenseer: Causal Modeling of End-to-End Latency Distributions by Harnessing Distributed Tracing. [pdf]
Yazhuo Zhang, Rebecca Isaacs, Yao Yue, Juncheng Yang, Lei Zhang, Ymir Vigfusson.
ACM Symposium on Cloud Computing (SoCC), 2023
C2DN: How to Harness Erasure Codes at the Edge for Efficient Content Delivery. [pdf] [slides]
Juncheng Yang, Anirudh Sabnis, Daniel S. Berger, K. V. Rashmi, Ramesh K. Sitaraman
The 19th USENIX Symposium on Networked Systems Design and Implementation (NSDI), 2022
Segcache: memory-efficient and high-throughput DRAM cache for small objects. [pdf] [slides]
Juncheng Yang, Yao Yue, K. V. Rashmi.
The 18th USENIX Symposium on Networked Systems Design and Implementation (NSDI), 2021
Segcache receives the community award (one of the best papers)
This work has been adopted for production at Twitter. See a short summary of the work.
Open-source systems and libraries: Pelikan, Rust crate,
Kangaroo: Caching Billions of Tiny Objects on Flash. [pdf] [slides]
Sara McAllister, Benjamin Berg, Julian Tutuncu-Macias, Juncheng Yang, Sathya Gunasekar, Jimmy Lu, Nathan Beckmann, Gregory R. Ganger.
28th ACM Symposium on Operating Systems Principles (SOSP), 2021
Extended version (invited submission) - ACM Transaction on storage (TOS) 2022
Kangaroo receives the best paper award
A Large Scale Analysis of Hundreds of In-memory Cache Clusters at Twitter. [pdf] [slides]
Juncheng Yang, Yao Yue, K. V. Rashmi.
The 14th USENIX Symposium on Operating Systems Design and Implementation (OSDI), 2020
Recognized as one of the best storage papers and invited for submission to ACM Transactions on Storage.
Discussed in Aleksey's Online Reading Group.
PACEMAKER: Avoiding HeART Attacks in Storage Clusters with Disk-adaptive Redundancy. [pdf][slides]
Saurabh Kadekodi, Francisco Maturana, Suhas Jayaram Subramanya, Juncheng Yang, K. V. Rashmi, Gregory R. Ganger.
14th USENIX Symposium on Operating Systems Design and Implementation (OSDI), 2020
Mutant: Balancing Storage Cost and Latency in LSM-Tree Data Stores. [pdf]
Hobin Yoon, Juncheng Yang, Sveinn F. Kristjansson, Steinn E. Sigurdarson, Ymir Vigfusson, Ada Gavrilovska.
ACM Symposium on Cloud Computing (SoCC), 2018
Skyline Diagram: Finding the Voronoi Counterpart for kyline Queries [pdf]
Jinfei Liu, Juncheng Yang, Li Xiong, Jian Pei, Jun Luo.
IEEE International Conference on Data Engineering (ICDE), 2018.
Extended version - IEEE Transactions on Knowledge and Data Engineering (TKDE), 2019
MITHRIL: Mining Sporadic Associations for Cache Prefetching. [pdf]
Juncheng Yang, Reza Karimi, Trausti Saemundsson, Avani Wildani, Ymir Vigfusson.
ACM Symposium on Cloud Computing (SoCC), 2017
Secure Skyline Queries on Cloud Platform [pdf]
Jinfei Liu, Juncheng Yang, Li Xiong, Jian Pei.
IEEE International Conference on Data Engineering (ICDE), 2017.
Extended version - IEEE Transactions on Knowledge and Data Engineering (TKDE), 2018.
Enabling Space Elasticity in Storage Systems. [pdf]
Helgi Sigurbjarnarson, Petur Orri Ragnarsson, Juncheng Yang, Ymir Vigfusson, Mahesh Balakrishnan.
ACM International Systems and Storage Conference (SYSTOR), 2016
Best student paper

Teaching

2022, 2023 Guest lecturer for 15613 Introduction to Computer Systems
2022 Guest lecturer for Advanced Operating Systems and Distributed Systems
2022 TA 15712 Advanced Operating Systems and Distributed Systems
2020 TA 18746 Storage Systems
2017 Guest lecturer for CS584 Advanced Computer System
2017 Teaching assistant CS453 Computer Security

Services

Conference

FAST Artifact Evaluation Chair: 2025
FAST Reivewer: 2025
MLSys Reviewer: 2025

Journal review

ACM Transactions on Storage (TOS): 2023
IEEE Transactions on Cloud Computing (TCC): 2023
IEEE ACCESS: 2023
IEEE Transactions on Parallel and Distributed Systems (TPDS): 2023
IEEE Transactions on Mobile Computing (TMC): 2023
IEEE Transactions on Knowledge and Data Engineering (TKDE): 2023

Awards

2023 Machine learning and System Rising Star
2023 Google Cloud Innovator
2020-22, Facebook Fellowship
2018, AWS research grant
2013, Emerson Fellowship
2013, Best Thesis Award (5/3000)
2012, "Person of the Year" Nomination
2012, Third Place in Green Tech International Competition, Taiwan
2009, First Award in National Chemistry Olympiad

Talks

Simple Scalable Caching with Three Static FIFO Queues.
- [11/2023] WOS conference
- [09/2023] VMware
- [09/2023] Kuaishou
- [09/2023] Microsoft Research Asia
- [09/2023] Tsinghua University
- [08/2023] Cloudflare
- [08/2023] USTC
- [07/2023] Alluxio
LESSCache: LEarned Segment-Structured Cache
- [02/2023] Meta
- [10/2022] VMware vSAN and VMware Research
Ubiquitous Caching: A Journey of Building Efficient Distributed and Process Caches.
- [10/2022] QCon SF
- [08/2022] Alluxio
Segcache: a memory-efficient and scalable in-memory key-value cache for small objects
- [01/2023] Oracle
- [2022] Shopify

Open-source Software & Data

Bio

Juncheng Yang is an Assistant Professor in the School of Engineering and Applied Science at Harvard University. He received his Ph.D. in Computer Science from Carnegie Mellon University in 2024, His research interests broadly cover the efficiency, performance, reliability, and sustainability of large-scale data systems.

Juncheng's works have received best paper awards at NSDI'24, NSDI'21, SOSP'21, and SYSTOR'16. His OSDI'20 paper was recognized as one of the best storage papers at the conference and invited to ACM TOS'21. Juncheng received a Facebook Ph.D. Fellowship in 2020, was recognized as a Rising Star in machine learning and systems in 2023, and a Google Cloud Research Innovator in 2023.

His work, Segcache, has been adopted for production at Twitter and Momento. The two eviction algorithms he designed (S3-FIFO, SIEVE) have been adopted for production at Google, VMware, Redpanda, and several others, with over 20 open-source libraries available on GitHub. Moreover, the open-source cache simulation library he created, libCacheSim, has been used by almost 100 research institutes and companies.