Cutting Latency Tail: Analyzing and Validating Replication without Canceling

Zhan Qiu, Juan F. Perez, Robert Birke, Lydia Chen, Peter G. Harrison

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Response time variability in software applications can severely degrade the quality of the user experience. To reduce this variability, request replication emerges as an effective solution by spawning multiple copies of each request and using the result of the first one to complete. Most previous studies have mainly focused on the mean latency for systems implementing replica cancellation, i.e., all replicas of a request are canceled once the first one finishes. Instead, we develop models to obtain the response-time distribution for systems where replica cancellation may be too expensive or infeasible to implement, as in 'fast' systems, such as web services, or in legacy systems. Furthermore, we introduce a novel service model to explicitly consider correlation in the processing times of the request replicas, and design an efficient algorithm to parameterize the model from real data. Extensive evaluations on a MATLAB benchmark and a three-tier web application (MediaWiki) show remarkable accuracy, e.g., 7 (4 percent) average error on the 99th percentile response time for the benchmark (respectively, MediaWiki), the requests of which execute in the order of seconds (respectively, milliseconds). Insights into optimal replication levels are thereby gained from this precise quantitative analysis, under a wide variety of system scenarios.

Translated title of the contributionLatencia de corte de la cola: Análisis y validación de la reproducción sin cancelar
Original languageEnglish (US)
Article number7932099
Pages (from-to)3128-3141
Number of pages14
JournalIEEE Transactions on Parallel and Distributed Systems
Issue number11
StatePublished - Nov 1 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Signal Processing
  • Hardware and Architecture
  • Computational Theory and Mathematics


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