Problem starting tasktracker in hadoop under windows

Question

I am trying to use hadoop under windows and I am running into a problem when I want to start tasktracker. For example:

$bin/start-all.sh

th

Answer 1

This issue was raised on the Apache Hadoop user mailing list. It appears to be a problem in some release versions of Hadoop and not others.

A simple solution is to download a different version of Hadoop (assuming you do not require a specific Hadoop version for some other reason).

I encountered this exact issue with version 1.0.0 (beta).

I then tried 0.23.0 but got a fatal ClassNotFoundException:

log4j:ERROR Could not find value for key log4j.appender.NullAppender
log4j:ERROR Could not instantiate appender named "NullAppender".
Exception in thread "main" java.lang.ClassNotFoundException: hadoop-mapreduce-examples-0.23.0.jar
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:264)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:182)

Finally I tried version 0.22.0 and that worked without error. Therefore I recommend you try downloading and installing version 0.22.0: http://hadoop.apache.org/common/releases.html#10+December%2C+2011%3A+release+0.22.0+available