Classpath Construction

Describes how the MapReduce classpath is constructed.

The classpath that is used to run a MapReduce program is constructed based on how the program is submitted.

When you submit a job or application from the command line, the classpath used to process the program is based on the following items in this order of priority:

  1. JARs in the program’s classpath, such as the hadoop 1.x, hadoop 2.x, or yarn classpath.
  2. JARs specified with the -libjar parameter which can be appended to hadoop jar or yarn jar commands.

If an external application submits the job or application, the classpath that is used to process the jar file is based on the following items in this order of priority:

  1. JARs in the classpath of the external application.
  2. JARs in the program’s classpath, such as the hadoop 1.x, hadoop 2.x, or yarn classpath.
  3. JARs specified with -libjar parameter which can be appended to hadoop jar or yarn jar commands.