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The "HadoopJavaVersions" page has been changed by EliCollins: http://wiki.apache.org/hadoop/HadoopJavaVersions?action=diff&rev1=14&rev2=15 Hadoop is built and tested on Oracle JDKs. Here are the known JDKs in use or have been tested and their status: ||'''Version''' ||'''Status''' ||'''Reported By''' || - ||1.6.0_16 ||Good ||Cloudera || + ||1.6.0_16 ||Good (*)||Cloudera || ||1.6.0_18 ||Avoid ||Many || ||1.6.0_19 ||Avoid ||Many || ||1.6.0_20 ||Good ||LinkedIn, Cloudera || ||[[http://www.oracle.com/technetwork/java/javase/downloads/jdk6-jsp-136632.html|1.6.0_21]] ||Good ||Yahoo!, Cloudera || ||1.6.0_24 ||No known issues ||Cloudera || + + * Hadoop works well with update 16 however there is a bug in JDK versions before update 19 that has been seen on HBase. See [[https://issues.apache.org/jira/browse/HBASE-4367|HBASE-4367]] for details. The Sun JVM has 32-bit and 64-bit modes. In a large cluster the NameNode and JobTracker need to run in 64-bit mode to keep all their data structures in memory. The workers can be set up for either 32-bit or 64-bit operation, depending upon preferences and how much memory the individual tasks need.
