[hadoop]MAPREDUCE-4123 Report

1. Symptom

./mapred groups gives NoClassDefFoundError

1.1 Severity


1.2 Was there exception thrown?


Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/mapred/tools/GetGroups

1.2.1 Were there multiple exceptions?


1.3 Scope of the failure

Single request

2. How to reproduce this failure

2.0 Version

2.0.0-alpha, 3.0.0

2.1 Configuration

1 job client

2.2 Reproduction procedure

1. Run mapreduce job request commandline (feature start)

2.2.1 Timing order


2.2.2 Events order externally controllable?


2.3 Can the logs tell how to reproduce the failure?


2.4 How many machines needed?


3. Diagnosis procedure

3.1 Detailed Symptom (where you start)

When running command line “./mapred groups” it throws NoClassDefFoundError exception.

3.2 Backward inference

The group feature has been eliminated so running the command line will not works.

In the startup script it forgot to handle this exception.

4. Root cause

Script is inconsistent after the group feature is removed

4.1 Category:

Incorrect exception handling

5. Fix

5.1 How?

Add groups to the the error handling part of the script