mapred.job.tracker master:54311 The host and port that the MapReduce job tracker runs at. If "local", then jobs are run in-process as a single map and reduce task. mapred.output.compress true mapred.output.compression.type BLOCK mapred.output.compression.codec com.hadoop.compression.lzo.LzoCodec mapred.map.output.compression.codec com.hadoop.compression.lzo.LzoCodec mapred.compress.map.output true mapred.job.reuse.jvm.num.tasks 10 mapred.tasktracker.map.tasks.maximum 4 mapred.tasktracker.reduce.tasks.maximum 2 mapred.reduce.tasks 40 mapred.map.child.java.opts -Xmx512G mapred.reduce.child.java.opts -Xmx1G mapred.reduce.parallel.copies 20