Description
Large-scale distributed systems, like MapReduce, are increasingly being used, but debugging such systems is still very difficult. In this paper, we propose D3, a new debugging system that answers diverse debugging queries by processing logs formally and efficiently. D3 specifies queries concisely in a declarative language and executes the queries in a distributed fashion, thereby lowering debugging overhead and bandwidth consumed. We demonstrate the effectiveness of our D3 design on a local cluster with Hadoop, an open-source MapReduce framework.