On the Linear Speedup of the Push-Pull Method for Decentralized Optimization over Digraphs

Fuente: arXiv
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Autori principali: Liang, Liyuan, Luo, Gan, Yuan, Kun
Natura: Preprint
Pubblicazione: 2025
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author Liang, Liyuan
Luo, Gan
Yuan, Kun
author_facet Liang, Liyuan
Luo, Gan
Yuan, Kun
contents The linear speedup property is essential for demonstrating the advantage of distributed algorithms over their single-node counterparts. In this paper, we study the stochastic Push-Pull method, a widely adopted decentralized optimization algorithm over directed graphs (digraphs). Unlike methods that rely solely on row-stochastic or column-stochastic mixing matrices, Push-Pull avoids nonlinear correction and has shown superior empirical performance across a variety of settings. However, its theoretical analysis remains challenging, and the linear speedup property has not been generally establishe--revealing a significant gap between empirical success and limited theoretical understanding. To bridge this gap, we propose a novel analysis framework and prove that Push-Pull achieves linear speedup over arbitrary strongly connected digraphs. Our results provide the comprehensive theoretical understanding for stochastic Push-Pull, aligning its theory with empirical performance. Code: https://github.com/pkumelon/PushPull.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18075
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Linear Speedup of the Push-Pull Method for Decentralized Optimization over Digraphs
Liang, Liyuan
Luo, Gan
Yuan, Kun
Optimization and Control
The linear speedup property is essential for demonstrating the advantage of distributed algorithms over their single-node counterparts. In this paper, we study the stochastic Push-Pull method, a widely adopted decentralized optimization algorithm over directed graphs (digraphs). Unlike methods that rely solely on row-stochastic or column-stochastic mixing matrices, Push-Pull avoids nonlinear correction and has shown superior empirical performance across a variety of settings. However, its theoretical analysis remains challenging, and the linear speedup property has not been generally establishe--revealing a significant gap between empirical success and limited theoretical understanding. To bridge this gap, we propose a novel analysis framework and prove that Push-Pull achieves linear speedup over arbitrary strongly connected digraphs. Our results provide the comprehensive theoretical understanding for stochastic Push-Pull, aligning its theory with empirical performance. Code: https://github.com/pkumelon/PushPull.
title On the Linear Speedup of the Push-Pull Method for Decentralized Optimization over Digraphs
topic Optimization and Control
url https://arxiv.org/abs/2506.18075