[jira] [Commented] (YARN-673) Remove yarn-default.xml

["Karthik Kambatla (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-673?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13655073#comment-13655073 ] 

Karthik Kambatla commented on YARN-673:
---------------------------------------

While I understand that having two different default values in the default.xml and code could be error-prone, I believe we should be careful about removing yarn-default.xml altogether. Particularly because moving it further from the code would make it even harder to ensure the documentation reflects the same default as the code. Also, it is a lot easier to grep through default.xml for defaults than documentation.
                
> Remove yarn-default.xml
> -----------------------
>
>                 Key: YARN-673
>                 URL: https://issues.apache.org/jira/browse/YARN-673
>             Project: Hadoop YARN
>          Issue Type: Improvement
>            Reporter: Siddharth Seth
>
> The default configuration files serve 2 purposes
> 1. Documenting available config parameters, and their default values.
> 2. Specifying default values for these parameters.
> An xml file hidden inside a jar is not necessarily the best way to document parameters. This could be moved into the documentation itself.
> Default values already exist in code for most parameters. There's no need to specify them in two places. We need to make sure defaults exist for all parameters before attempting this.
> Having default configuration files just bloats job conf files; over 450 parameters, out of which <20 are likely job specific params. JobConf files end up being rather big, and the memory footprint of the conf object is large (>300KB last I checked).

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