Detecting bottlenecks in parallel DAG-based data flow programs

In recent years, several frameworks have been introduced to facilitate massively-parallel data processing on shared-nothing architectures like compute clouds. While these frameworks generally offer good support in terms of task deployment and fault tolerance, they only provide poor assistance in finding reasonable degrees of parallelization for the tasks to be executed. However, as billing models of clouds enable the utilization of many resources for a short period of time for the same cost as utilizing few resources for a long time, proper levels of parallelization are crucial to achieve short processing times while maintaining good resource utilization and therefore good cost efficiency. In this paper, we present and evaluate a solution for detecting CPU and I/O bottlenecks in parallel DAG-based data flow programs assuming capacity constrained communication channels. The detection of bottlenecks represents an important foundation for manually or automatically scaling out and tuning parallel data flow programs in order to increase performance and cost efficiency.