question about the Twenty Newsgroup example

[Mishari Almishari]

Hi,
I am new to Mahout and i am facing the following problem in the Twenty
Newsgroup example:
When I try to run the test command over hadoop

HADOOP_HOME/bin/hadoop \
    jar \
    $MAHOUT_HOME/examples/ .....


I got the following error: "java.lang.OutOfMemoryError: Java heap space"

you know how i fix the problem?