I am a Ph.D. student in
the
Computer
Science Department at Carnegie Mellon University. I am fortunate
to be advised by
Guy Blelloch. I am also fortunate to be supported
by
a
Facebook Graduate Fellowship for 2013-2014. I
obtained my bachelor's degree in Computer Science from UC Berkeley.
Research Interests
I am interested in all aspects of parallel
computing, especially parallel graph processing frameworks,
algorithms, data structures and tools for deterministic parallel
programming. Below is a description of my recent projects.
(For certain papers, the authors are listed alphabetically,
following the convention in mathematics and theoretical computer
science, and others are listed by contribution.)
Large-scale Graph Processing
I am very interested in
developing algorithms for large-scale graph processing. Graph
algorithms have many applications, ranging from analyzing social
networks to finding patterns in biological networks.
I have developed
Ligra, a lightweight graph
processing framework for shared memory. The project was motivated by
the fact that the largest publicly available real-world graphs all fit
in shared memory. When graphs fit in shared-memory, processing them
using Ligra can give performance improvements of up to orders of
magnitude compared to distributed-memory graph processing systems. As
an extension, I am currently working on supporting graph compression
techniques in Ligra, so that it can support large graphs with less
memory.
I have also developed practical algorithms with strong theoretical
guarantees for many fundamental graph algorithms, such as connected
components, minimum spanning forest, triangle computations, maximal
independent set and maximal matching. I have implemented these
algorithms for the shared memory multicore setting and also for
external memory.
Parallel String/Text Algorithms and Data Structures
I have
developed practical algorithms with theoretical guarantees for several
important algorithms and data structures in string/text
processing. These have important applications in bioinformatics, data
compression, information retrieval among many others.
- Julian Shun.
Parallel Wavelet Tree Construction
To appear in Proceedings of the IEEE Data Compression Conference (DCC), 2015.
- Julian Shun.
Fast Parallel
Computation of Longest Common Prefixes
Proceedings of the ACM/IEEE International Conference for High
Performance Computing, Networking, Storage and Analysis (SC),
pp. 387-398, 2014.
- Julian Shun and Guy Blelloch.
A Simple Parallel
Cartesian Tree Algorithm and its Application to Parallel Suffix Tree
Construction
ACM Transactions on Parallel Computing (TOPC), Vol. 1 Issue 1,
Article No. 8, 2014. (Earlier version appears in ALENEX 2011.)
Source code
- Julian Shun and Fuyao Zhao (joint first author).
Practical Parallel
Lempel-Ziv Factorization
Proceedings of the IEEE Data Compression Conference (DCC),
pp. 123-132, 2013.
Source code
Deterministic Parallel Programming
I am interested in
developing tools that many it easier for others to do parallel
programming. In particular, I have developed algorithms, data
structures and tools for deterministic parallel
programming. Determinism is very important in parallel programming as
it allows for ease of debugging, reasoning about correctness and
performance.
- Julian Shun, Yan Gu, Guy Blelloch, Jeremy Fineman and Phillip Gibbons.
Sequential Random
Permutation, List Contraction and Tree Contraction are Highly
Parallel
To appear in Proceedings of the ACM-SIAM Symposium on Discrete
Algorithms (SODA), 2015.
- Julian Shun and Guy Blelloch.
Phase-concurrent Hash
Tables for Determinism
Proceedings of the ACM Symposium on Parallelism in Algorithms and
Architectures (SPAA), pp. 96-107, 2014.
- Julian Shun, Guy Blelloch, Jeremy Fineman and
Phillip Gibbons.
Reducing Contention
Through Priority Updates
Proceedings of the ACM Symposium on Parallelism in Algorithms and
Architectures (SPAA), pp. 152-163, 2013.
- (by alphabetical order) Guy Blelloch, Jeremy Fineman and Julian
Shun.
Greedy Sequential Maximal
Independent Set and Matching are Parallel on Average
Proceedings of the ACM Symposium on Parallelism in Algorithms and
Architectures (SPAA), pp. 308-317, 2012.
- (by alphabetical order) Guy Blelloch, Jeremy Fineman,
Phillip Gibbons and Julian Shun.
Internally
Deterministic Parallel Algorithms Can Be Fast
Proceedings of the ACM SIGPLAN Symposium on Principles and
Practice of Parallel Programming (PPoPP), pp. 181-192, 2012.
Problem Based Benchmark Suite (PBBS)
I have developed
a benchmark
suite of fundamental problems along with parallel algorithms for
solving them. The benchmarks are solely defined by the problem
specification and input/output formats, without any reference to the
algorithm, programming language or machine used. Please contribute
your own implementations to the benchmark suite by sending them to me!
The following papers contain descriptions of the benchmarks and
experiments using them: