GridBot: execution of bags of tasks in multiple grids

We present a holistic approach for efficient execution of bags-of-tasks (BOTs) on multiple grids, clusters, and volunteer computing grids virtualized as a single computing platform. The challenge is twofold: to assemble this compound environment and to employ it for execution of a mixture of throughput- and performance-oriented BOTs, with a dozen to millions of tasks each. Our generic mechanism allows per BOT specification of dynamic arbitrary scheduling and replication policies as a function of the system state, BOT execution state, and BOT priority. We implement our mechanism in the GridBot system and demonstrate its capabilities in a production setup. GridBot has executed hundreds of BOTs with over 9 million jobs during three months alone; these have been invoked on 25,000 hosts, 15,000 from the Superlink@Technion community grid and the rest from the Technion campus grid, local clusters, the Open Science Grid, EGEE, and the UW Madison pool.