Home | About | Sematext search-lucene.com search-hadoop.com
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB
 Search Hadoop and all its subprojects:

Switch to Threaded View
MapReduce >> mail # user >> One mapper/reducer runs on a single JVM


Copy link to this message
-
One mapper/reducer runs on a single JVM
Hello Hadoop experts,

I have a question in my mind for a long time. Supposing I am developing M-R
program, and it is Java based (Java UDF, implements mapper or reducer
interface). My question is, in this scenario, whether a mapper or a reducer
is a separate JVM process? E.g. supposing on a machine, there are 4
mappers, they are 4 individual processes? I am also wondering whether the
processes on a single machine will impact each other when each JVM wants to
get more memory to run faster?

thanks in advance,
Lin
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB