Mac OS X, Hadoop 0.19.1, and Java 1.6

If you're excited, like I am, about Amazon's recent announcement that they are now offering Elastic Map Reduce you probably want to try a quick Hadoop MapReduce application to test the waters. I found out quickly that if you are on a Mac (as I am) you'll need to perform a few quick configurations before things work correctly. Below is what I needed to do to get Hadoop running on my Mac with Java 1.6.

This post assumes you are running the latest Mac OS X 10.5 with all updates applied.

Enable Java 1.6 Support

To enable Java 1.6, open up the Java Preferences application. This can be found in /Applications/Utilities/Java Preferences.

You will need to drag Java 1.6 up and place at the top of both the applet and application versions.

Open up a terminal and type java -version and you should see something like the following:

java version "1.6.0_07"
Java(TM) SE Runtime Environment (build 1.6.0_07-b06-153)
Java HotSpot(TM) 64-Bit Server VM (build 1.6.0_07-b06-57, mixed mode)

Configure JAVA_HOME

This was the tough part. Once you have Java 1.6 as the default runtime, you need to configure your JAVA_HOME environment variable to reflect this as well. Hadoop wants JAVA_HOME set before it will run correctly, otherwise you'll see:

Exception in thread "main" java.lang.UnsupportedClassVersionError: Bad version number in .class file

This assumes you are using the standard bash shell. Open up ~/.bash_profile (or create it if it doesn't exist) and add this line:

export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home

Save the file. Return to the terminal and type . ~/.bash_profile which will set your JAVA_HOME correctly. To verify, you can type: echo $JAVA_HOME.

While you are in .bash_profile you might as well add a HADOOP_HOME variable, which will make running hadoop from the command line much easier. Below is my full .bash_profile:

export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home
export HADOOP_HOME=~sethladd/Development/hadoop-0.19.1


Note that I also placed $HADOOP_HOME/bin into my path, so now I can type hadoop from anywhere.

Now that you are all setup, try the simple WordCount Hadoop Tutorial.

Popular posts from this blog

Converting Array to List in Scala

Lists and arrays in Dart

Null-aware operators in Dart