Classes called from mapper and reducer.

[Ilya Vishnevsky <Il...@e-legion.com>]

For example my application contains some class SomeClass. And this
application uses hadoop mapreduce. What will be if Mapper in it's map
function calls a method of SomeClass? 
 If I understand correct mapper is running on child nodes. For that
parent sends mapper and JobConf to childs. Will it send SomeClass too in
our case? And what if SomeClass needs for example property files, saved
in the local file system, not in distributed FS? Will child apply for
such file to parent?
 Maybe I ask stupid questions. I still don't have clear idea of how
hadoop works and especially how it realize parallelization.

RE: Classes called from mapper and reducer.

[Richard Yang <ri...@richardyang.net>]

Hello Ilya,

I only know one way to run one's program on Hadoop. That is to jar all your
classes into a .jar and when using, specify the entry point of execution. 
http://lucene.apache.org/hadoop/hdfs_design.html
should give you a clear concept upon Hadoop Map/Reduce. 

Best Regards
 
Richard Yang
richardyang@richardyang.net
kusanagiyang@gmail.com
 
 

-----Original Message-----
From: Ilya Vishnevsky [mailto:Ilya.Vishnevsky@e-legion.com] 
Sent: Friday, March 23, 2007 2:34 AM
To: hadoop-user@lucene.apache.org
Subject: Classes called from mapper and reducer.

For example my application contains some class SomeClass. And this
application uses hadoop mapreduce. What will be if Mapper in it's map
function calls a method of SomeClass? 
 If I understand correct mapper is running on child nodes. For that
parent sends mapper and JobConf to childs. Will it send SomeClass too in
our case? And what if SomeClass needs for example property files, saved
in the local file system, not in distributed FS? Will child apply for
such file to parent?
 Maybe I ask stupid questions. I still don't have clear idea of how
hadoop works and especially how it realize parallelization.