# Parallel Sparse Tensor Decomposition in Chapel

## TL;DR

This paper demonstrates that Chapel can effectively implement parallel sparse tensor decomposition, achieving near state-of-the-art performance and scalability comparable to C/OpenMP implementations.

## Contribution

The work ports a leading sparse tensor decomposition tool from C/OpenMP to Chapel, analyzing performance bottlenecks and scalability in the new environment.

## Key findings

- Chapel code achieves 83%-96% of C/OpenMP performance.
- Near linear scalability up to 32 cores.
- Identifies Chapel features beneficial for tensor computations.

## Abstract

In big-data analytics, using tensor decomposition to extract patterns from large, sparse multivariate data is a popular technique. Many challenges exist for designing parallel, high performance tensor decomposition algorithms due to irregular data accesses and the growing size of tensors that are processed. There have been many efforts at implementing shared-memory algorithms for tensor decomposition, most of which have focused on the traditional C/C++ with OpenMP framework. However, Chapel is becoming an increasingly popular programing language due to its expressiveness and simplicity for writing scalable parallel programs. In this work, we port a state of the art C/OpenMP parallel sparse tensor decomposition tool, SPLATT, to Chapel. We present a performance study that investigates bottlenecks in our Chapel code and discusses approaches for improving its performance. Also, we discuss features in Chapel that would have been beneficial to our porting effort. We demonstrate that our Chapel code is competitive with the C/OpenMP code for both runtime and scalability, achieving 83%-96% performance of the original code and near linear scalability up to 32 cores.