1 Hadoop Map-Reduce – Tuning and Debugging Arun C Murthy acmurthy@apache.org Yahoo! CCDI 2 Topical Matters… • Who doesn’t know Map-Reduce?! • Peek inside your MR application… • Tuning • Debug (god forbid!) Counters … • Often MR applications have countable ‘events’ • For e.g. the Map-Reduce framework ‘counts’ the bytes read/write on HDFS and the local filesystem • To define your own: – sta