[MAPREDUCE-987] Exposing MiniDFS and MiniMR clusters as a single process command-line

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.2.0, 2.0.2-alpha
• Fix Version/s: 1.2.0, 2.0.2-alpha
• Component/s: build, test
• Hadoop Flags: Reviewed
• Assignee: Ahmed Radwan
• Reporter: Philip Martin
• Created: 15/Sep/09 21:31
• Updated: 11/Oct/12 17:48
• Resolved: 23/Jul/12 23:58

Description

It's hard to test non-Java programs that rely on significant mapreduce functionality. The patch I'm proposing shortly will let you just type "bin/hadoop jar hadoop-hdfs-hdfswithmr-test.jar minicluster" to start a cluster (internally, it's using Mini

{MR,HDFS}

Cluster) with a specified number of daemons, etc. A test that checks how some external process interacts with Hadoop might start minicluster as a subprocess, run through its thing, and then simply kill the java subprocess.

I've been using just such a system for a couple of weeks, and I like it. It's significantly easier than developing a lot of scripts to start a pseudo-distributed cluster, and then clean up after it. I figure others might find it useful as well.

I'm at a bit of a loss as to where to put it in 0.21. hdfs-with-mr tests have all the required libraries, so I've put it there. I could conceivably split this into "minimr" and "minihdfs", but it's specifically the fact that they're configured to talk to each other that I like about having them together. And one JVM is better than two for my test programs.

Issue Links

• is blocked by: MAPREDUCE-4406 Users should be able to specify the MiniCluster ResourceManager and JobHistoryServer ports
• is blocked by: MAPREDUCE-4407 Add hadoop-yarn-server-tests-<version>-tests.jar to hadoop dist package
• relates to: HDFS-3167 CLI-based driver for MiniDFSCluster