An Efficient and Balanced Platform for Data-Parallel Subsampling Workloads

Abstract

With the advent of internet services, data started growing faster than it can be processed. To personalize user experience, this enormous data has to be processed in real time, in interactive fashion. In order to achieve faster data processing often a statistical method called subsampling. Subsampling workloads compute statistics from a random subset of sample data (i.e., a subsample). Data-parallel platforms group these samples into tasks; each task subsamples its data in parallel. Current, state-of-the-art platforms such as Hadoop are built for large tasks that run for long periods of time, but applications with smaller average task sizes suffer large overheads on these platforms. Tasks in subsampling workloads are sized to minimize the number of overall cache misses, and these tasks can complete in seconds. This technique can reduce the overall length of a map-reduce job, but only when the savings from the cache miss rate reduction are not eclipsed by the platform overhead of task creation and data distribution. In this thesis, we propose a data-parallel platform with an efficient data distribution component that breaks data-parallel subsampling workloads into compute clusters with tiny tasks. Each tiny task completes in few hundreds of milliseconds to seconds. Tiny tasks reduce processor cache misses caused by random subsampling, which speeds up per-task running time. However, they cause significant scheduling overheads and data distribution challenges. We propose a task knee-pointing algorithm and a dynamic scheduler that schedules the tasks to worker nodes based on the availability and response times of the data nodes. We compare our framework against various configurations of BashReduce and Hadoop. A detailed discussion of tiny task approach on two workloads, EAGLET and Netflix movie rating is presented.