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From Ted Dunning <tdunn...@veoh.com>
Subject Re: using hadoop within the Tomcat
Date Fri, 23 Nov 2007 19:55:24 GMT

The hadoop startup script just makes sure that the classpath has the right
jars in it and that the right environment variables point to the right
configuration files.

The easiest way to understand what is happening is to edit the hadoop
script, go to the line that runs java, duplicate that line and put an echo
at the beginning of the first copy.  This will tell you what command is
actually run.  You can then replicate that environment inside tomcat.

Adding a -x option to the # line at the beginning of the file will have
similar effect but will produce lots of garbage output as well.


On 11/23/07 11:50 AM, "bofh@redwerk.com" <bofh@redwerk.com> wrote:

> On Fri, Nov 23, 2007 at 11:37:49AM -0800, Ted Dunning wrote:
>> 
>> Any java process that can access the machines in the cluster can start a
>> job.
>> 
>> That means that any thread in the tomcat in, say, a servlet could start a
>> job.  This would be no different than any of the standard examples such as
>> word count.
> 
> Sorry, I probably missing something - but the examples are started using
> hadoop startup script? Or do you mean I can just provide the
> configuration for the hadoop cluster(s) and start jobs in the same
> manner using some of internal Hadoop classes which are doing the job
> started from scripts?


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