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From Rahul Sood <rs...@yahoo-inc.com>
Subject Java inputformat for pipes job
Date Tue, 08 Apr 2008 09:29:51 GMT
Hi,

I implemented a customized input format in Java for a Map Reduce job.
The mapper and reducer classes are implemented in C++, using the Hadoop
Pipes API. 

The package documentation for org.apache.hadoop.mapred.pipes states that
"The job may consist of any combination of Java and C++ RecordReaders,
Mappers, Paritioner, Combiner, Reducer, and RecordWriter"

I packaged the input format class in a jar file and ran the job
invocation command:

hadoop pipes -jar mytest.jar -inputformat mytest.PriceInputFormat -conf
conf/mytest.xml -input mgr/in -output mgr/out -program mgr/bin/TestMgr

It keeps failing with error ClassNotFoundException
Although I've specified the jar file name with the -jar parameter, the
input format class still cannot be located. Is there any other means to
specify the input format class, or the job jar file, for a Pipes job ?

Stack trace:

Exception in thread "main" java.lang.ClassNotFoundException:
mytest.PriceInputFormat
        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:276)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:247)
        at
org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:524)
        at
org.apache.hadoop.mapred.pipes.Submitter.getClass(Submitter.java:309)
        at
org.apache.hadoop.mapred.pipes.Submitter.main(Submitter.java:357)

Thanks,

Rahul Sood
rsood@yahoo-inc.com



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