Apache Hadoop 3.2.0 Release Notes

These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.

This change updates the Microsoft Windows build directions to be more flexible with regards to Visual Studio compiler versions:

Additionally, Snappy and ISA-L that use bin as the location of the DLL will now be recognized without having to set their respective lib paths if the prefix is set.

Note to contributors:

It is very important that solutions for any patches remain at the VS 2010-level.

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Environment variables for MapReduce tasks can now be specified as separate properties, e.g.: mapreduce.map.env.VARNAME=value mapreduce.reduce.env.VARNAME=value yarn.app.mapreduce.am.env.VARNAME=value yarn.app.mapreduce.am.admin.user.env.VARNAME=value This form of specifying environment variables is useful when the value of an environment variable contains commas.

WASB: Bug fix to support non-sequential page blob reads. Required for HBASE replication.

New command is added to dfsadmin. hdfs dfsadmin [-upgrade [query | finalize] 1. -upgrade query gives the upgradeStatus 2. -upgrade finalize is equivalent to -finalizeUpgrade.

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If HADOOP_CLIENT_SKIP_UNJAR environment variable is set to true, Apache Hadoop RunJar skips unjar the provided jar.

WASB: Fix Spark process hang at shutdown due to use of non-daemon threads by updating Azure Storage Java SDK to 7.0

Mover could have fail after 20+ minutes if a block move was enqueued for this long, between two DataNodes due to an internal constant that was introduced for Balancer, but affected Mover as well. The internal constant can be configured with the dfs.balancer.max-iteration-time parameter after the patch, and affects only the Balancer. Default is 20 minutes.

commons-lang version 2.6 was removed from Apache Hadoop. If you are using commons-lang 2.6 as transitive dependency of Hadoop, you need to add the dependency directly. Note: this also means it is absent from share/hadoop/common/lib/

FUSE lib now recognize the change of the Kerberos ticket cache path if it was changed between two file system access in the same local user session via the KRB5CCNAME environment variable.

Restore the KMS accept queue size to 500 in Hadoop 3.x, making it the same as in Hadoop 2.x.