问题
I am developing an application that try to read log file stored in S3 bucks and parse it using Elastic MapReduce. Current the log file has following format
-------------------------------
COLOR=Black
Date=1349719200
PID=23898
Program=Java
EOE
-------------------------------
COLOR=White
Date=1349719234
PID=23828
Program=Python
EOE
So I try to load the file into my Pig script, but the build-in Pig Loader doesn't seems be able to load my data, so I have to create my own UDF. Since I am pretty new to Pig and Hadoop, I want to try script that written by others before I write my own, just to get a teast of how UDF works. I found one from here http://pig.apache.org/docs/r0.10.0/udf.html, there is a SimpleTextLoader. In order to compile this SimpleTextLoader, I have to add a few imports, as
import java.io.IOException;
import java.util.ArrayList;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.InputFormat;
import org.apache.hadoop.mapreduce.RecordReader;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigSplit;
import org.apache.pig.backend.executionengine.ExecException;
import org.apache.pig.data.Tuple;
import org.apache.pig.data.TupleFactory;
import org.apache.pig.data.DataByteArray;
import org.apache.pig.PigException;
import org.apache.pig.LoadFunc;
Then, I found out I need to compile this file. I have to download svn and pig running
sudo apt-get install subversion
svn co http://svn.apache.org/repos/asf/pig/trunk
ant
Now i have a pig.jar file, then I try to compile this file.
javac -cp ./trunk/pig.jar SimpleTextLoader.java
jar -cf SimpleTextLoader.jar SimpleTextLoader.class
It compiles successful, and i type in Pig entering grunt, in grunt i try to load the file, using
grunt> register file:/home/hadoop/myudfs.jar
grunt> raw = LOAD 's3://mys3bucket/samplelogs/applog.log' USING myudfs.SimpleTextLoader('=') AS (key:chararray, value:chararray);
2012-12-05 00:08:26,737 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 2998: Unhandled internal error. org/apache/pig/LoadFunc Details at logfile: /home/hadoop/pig_1354666051892.log
Inside the pig_1354666051892.log, it has
Pig Stack Trace
---------------
ERROR 2998: Unhandled internal error. org/apache/pig/LoadFunc
java.lang.NoClassDefFoundError: org/apache/pig/LoadFunc
I also try to use another UDF (UPPER.java) from http://wiki.apache.org/pig/UDFManual, and I am still get the same error by try to use UPPER method. Can you please help me out, what's the problem here? Much thanks!
UPDATE: I did try EMR build-in Pig.jar at /home/hadoop/lib/pig/pig.jar, and get the same problem.
回答1:
Put the UDF jar in the /home/hadoop/lib/pig directory or copy the pig-*-amzn.jar file to /home/hadoop/lib and it will work.
You would probably use a bootstrap action to do either of these.
回答2:
Most of the Hadoop ecosystem tools like pig and hive look up $HADOOP_HOME/conf/hadoop-env.sh for environment variables.
I was able to resolve this issue by adding pig-0.13.0-h1.jar (it contains all the classes required by the UDF) to the HADOOP_CLASSPATH:
export HADOOP_CLASSPATH=/home/hadoop/pig-0.13.0/pig-0.13.0-h1.jar:$HADOOP_CLASSPATH
pig-0.13.0-h1.jar is available in the Pig home directory.
来源：https://stackoverflow.com/questions/13714800/pig-udf-running-on-aws-emr-with-java-lang-noclassdeffounderror-org-apache-pig-l