 
Summary: Compositional Competitiveness for Distributed
Algorithms
James Aspnes
Orli Waarts
June 14, 2004
Abstract
We define a measure of competitive performance for distributed al
gorithms based on throughput, the number of tasks that an algorithm
can carry out in a fixed amount of work. This new measure com
plements the latency measure of Ajtai et al. [3], which measures how
quickly an algorithm can finish tasks that start at specified times. The
novel feature of the throughput measure, which distinguishes it from
the latency measure, is that it is compositional: it supports a notion of
algorithms that are competitive relative to a class of subroutines, with
the property that an algorithm that is kcompetitive relative to a class
of subroutines, combined with an competitive member of that class,
gives a combined algorithm that is kcompetitive.
In particular, we prove the throughputcompetitiveness of a class of
algorithms for collect operations, in which each of a group of n processes
obtains all values stored in an array of n registers. Collects are a funda
