What is the role of hadoop-core-*.jar?

[Yoonmin Nam <ro...@dgist.ac.kr>]

Hello, everyone!

 

As you can see in the title, I am curious about the exact role of the
hadoop-core-*.jar file.

 

At first I thought it contains every compiled hadoop source files, so It is
necessary for starting every component of Hadoop such as DataNode and
TaskTracker.

 

However, even I deleted all hadoop-core-*.jar file in the hadoop home
folder, the script "start-all.sh" runs successfully.

 

It is strongly related to the classpath, but I am not sure about that.

 

In addition, when I distributed newly packaged hadoop-core-*.jar file which
contains changed source codes for doing some experiments, the changed
contents are not effected.

This means original, unmodified compiled contents are working in the
cluster.

So, I cannot see from the one line of log to the some logic to improve HDFS.

 

Why this issues happens to me?

Is there anyone who let me know about this issue?

 

Thank you!

Re: What is the role of hadoop-core-*.jar?

[Steve Loughran <st...@hortonworks.com>]

Grab the source from SVN/git and import it into your chosen IDE -it'll show
you whats in the JAR and what's not


On 28 January 2014 09:00, Yoonmin Nam <ro...@dgist.ac.kr> wrote:

> Hello, everyone!
>
>
>
> As you can see in the title, I am curious about the exact role of the
> hadoop-core-*.jar file.
>
>
>
> At first I thought it contains every compiled hadoop source files, so It is
> necessary for starting every component of Hadoop such as DataNode and
> TaskTracker.
>
>
>
> However, even I deleted all hadoop-core-*.jar file in the hadoop home
> folder, the script "start-all.sh" runs successfully.
>
>
>
> It is strongly related to the classpath, but I am not sure about that.
>
>
>
> In addition, when I distributed newly packaged hadoop-core-*.jar file which
> contains changed source codes for doing some experiments, the changed
> contents are not effected.
>
> This means original, unmodified compiled contents are working in the
> cluster.
>
> So, I cannot see from the one line of log to the some logic to improve
> HDFS.
>
>
>
> Why this issues happens to me?
>
> Is there anyone who let me know about this issue?
>
>
>
> Thank you!
>
>

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