11

When I try to compile my program in Hadoop with this command

bin/hadoop com.sun.tools.javac.Main WordCounter.java

from Hadoop folder, it says

Error: Could not find or load main class com.sun.tools.javac.Main

I looked in similar threads where people suggested to check if JAVA_HOME is properly stated. So in etc/hadoop/hadoop-env.shI added this line

export JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64

then checked if tools.pack is properly unpacked in /usr/lib/jvm/java-7-openjdk-amd64/lib and it was. Then I tried javac -version which gave 

javac 1.7.0_65

I tried to reinstall Java but it didn't solve the problem.

kuporific
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Kudayar Pirimbaev
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3 Answers3

16

Try to set HADOOP_CLASSPATH environment variable

export HADOOP_CLASSPATH=$JAVA_HOME/lib/tools.jar
ponkin
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0

The error means you don't use a JDK to start Hadoop. The main difference between the JRE (pure runtime) and the JDK is the Java compiler javac. To see if you have a Java compiler, you need to check two places: There should be a javac in the $JAVA_HOME/bin folder plus there must be a file $JAVA_HOME/lib/tools.jar.

In your case, the first one (the binary to start the compiler) can be missing but you absolutely need the tools.jar.

You say that you have a tools.pack but I haven't heard about this one before. Use your package manager to search for openjdk and then look for a package in the result list which says jdk. On my system, that would be openjdk-7-jdk. Install this package and the error should go away.

Aaron Digulla
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    tools.jar exists as well as javac – Kudayar Pirimbaev Dec 05 '14 at 12:33
  • also there is openjdk-7-jdk installed when i searched – Kudayar Pirimbaev Dec 05 '14 at 12:34
  • In that case, your setting is getting ignored. If `bin/hadoop` is a script, then try `bash -x bin/hadoop ...` to see which commands are executed and what variables are set. To redirect the output to a file, use `|& tee hadoop.log`. You can then search for `hadoop-env.sh` and `JAVA_HOME` in `hadoop.log`. – Aaron Digulla Dec 05 '14 at 12:56
0

I had to downgrade Hadoop to 2.9.2 and it's working.

I also had these in my environment:

export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk
export PATH=${JAVA_HOME}/bin:${PATH}
export HADOOP_CLASSPATH=${JAVA_HOME}/lib/tools.jar
William Laszlo
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