Rizk, Amr , Poloczek, Felix and Ciucu, Florin (2016) Stochastic bounds in fork-join queueing systems under full and partial mapping. Queueing Systems, 83 (3). pp. 261-291.

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Abstract

In a Fork-Join (FJ) queueing system an upstream fork station splits
incoming jobs into N tasks to be further processed by N parallel servers, each with its own queue; the response time of one job is determined, at a downstream join station, by the maximum of the corresponding tasks’ response times. This queueing system is useful to the modelling of multi-service systems subject to synchronization constraints, such as MapReduce clusters or multipath routing. Despite their apparent simplicity, FJ systems are hard to analyze. This paper provides the first computable stochastic bounds on the waiting and response time distributions in FJ systems under full (bijective) and partial (injective) mapping of tasks to servers. We consider four practical scenarios by combining 1a) renewal and 1b) non-renewal arrivals, and 2a) non-blocking and 2b) blocking servers. In the case of non-blocking servers we prove that delays scale as O(log N), a law which is known for first moments under renewal input only. In the case of blocking servers, we prove that the same factor of log N dictates the stability region of the system. Simulation results indicate that our bounds are tight, especially at high utilizations, in all four scenarios. A remarkable insight gained from our results is that, at moderate to high utilizations, multipath routing “makes sense” from a queueing perspective for two paths only, i.e., response times drop the most when N = 2; the technical explanation is that the resequencing (delay) price starts to quickly dominate the tempting gain due to multipath transmissions.

Item Type:	Journal Article
Subjects:	Q Science > QA Mathematics > QA76 Electronic computers. Computer science. Computer software
Divisions:	Faculty of Science > Computer Science
Library of Congress Subject Headings (LCSH):	Web servers -- Evaluation -- Stochastic models, Queuing theory
Journal or Publication Title:	Queueing Systems
Publisher:	Spring New York LLC
ISSN:	0257-0130
Official Date:	24 June 2016
Dates:	Date Event 24 June 2016 Available 28 May 2016 Accepted
Date of first compliant deposit:	6 June 2016
Volume:	83
Number:	3
Page Range:	pp. 261-291
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access

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