Estimating the progress of MapReduce pipelines

In parallel query-processing environments, accurate, time-oriented progress indicators could provide much utility given that inter- and intra-query execution times can have high variance. However, none of the techniques used by existing tools or available in the literature provide non-trivial progress estimation for parallel queries. In this paper, we introduce Parallax, the first such indicator. While several parallel data processing systems exist, the work in this paper targets environments where queries consist of a series of MapReduce jobs. Parallax builds on recently-developed techniques for estimating the progress of single-site SQL queries, but focuses on the challenges related to parallelism and variable execution speeds. We have implemented our estimator in the Pig system and demonstrate its performance through experiments with the PigMix benchmark and other queries running in a real, small-scale cluster.