Got predictability?: experiences with fault-tolerant middleware

Unpredictability in COTS-based systems often manifests as occasional instances of uncontrollably-high response times. A particular category of COTS systems, fault-tolerant (FT) middleware, is used in critical enterprise and embedded applications where predictability is of paramount importance. Our prior empirical study, which used a clientserver microbenchmark, suggested that hard bounds for the maximum latency are hard to establish a priori, but that the unpredictability may be confined to less than 1% of the requests. In this paper, we present empirical data, from 7 different three-tier, FT-middleware applications, that shows strong evidence supporting this “magical 1%” hypothesis. We conducted a controlled experiment with 7 teams of students from a graduate-level course at Carnegie Mellon University. Each team, starting from a common three-tier architecture, independently implemented and evaluated an original application using middleware (either CORBA or EJB) and a custom-impl...

• Type: Conference
• Year: 2007
• Where: MIDDLEWARE
• Authors: Tudor Dumitras, Priya Narasimhan
• Keywords: MIDDLEWARE 2007, Prior Empirical Study, Random Latency Outliers, Unpredictability