Hi, It doesn’t consider where the map’s ran to schedule the reducers because reducers need to contact all the mappers for the map o/p’s. It schedules reducers wherever the slots available.
Thanks Devaraj k From: Felix.徐 [mailto:ygnhz...@gmail.com] Sent: 16 July 2013 09:25 To: user@hadoop.apache.org Subject: Policies for placing a reducer Hi all, What is the policy of choosing a node for a reducer in mapreduce (Hadoop v1.2.0)? For example, If a cluster has 5 slaves, each slave can serve 2 maps and 2 reduces , there is a job who occupies 5 mappers and 3 reducers , how does the jobtracker assign reducers to these nodes (choosing free slaves or placing reducers close to mappers)? Thanks.
