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https://issues.apache.org/jira/browse/HADOOP-785?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12518355
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Owen O'Malley commented on HADOOP-785:
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I think Arun's proposal looks good, except for having explicit context. I'd
much rather have that either in xml comments or in the description.
I think the ParameterName proposal would be too much complexity for the
payback, especially given that we make getter/setter methods for most of the
properties anyways and thus there shouldn't be duplicate strings running around.
On a side note, I would prefer if the xml looked more like:
<propery name="foo" value="bar"/>
with description being an optional subelement. That however would break the
config files even more than the current proposal. One of the advantages to
using attributes rather than subelements is that it is pretty clear that:
<property name=" foo" value="bar"/>
is wrong, while:
<property><name> foo</name><value>bar</value></property>
looks right. (The spaces are much more obvious (to programers at least!) when
enclosed in quotes.
> Divide the server and client configurations
> -------------------------------------------
>
> Key: HADOOP-785
> URL: https://issues.apache.org/jira/browse/HADOOP-785
> Project: Hadoop
> Issue Type: Improvement
> Components: conf
> Affects Versions: 0.9.0
> Reporter: Owen O'Malley
> Assignee: Arun C Murthy
> Fix For: 0.15.0
>
>
> The configuration system is easy to misconfigure and I think we need to
> strongly divide the server from client configs.
> An example of the problem was a configuration where the task tracker has a
> hadoop-site.xml that set mapred.reduce.tasks to 1. Therefore, the job tracker
> had the right number of reduces, but the map task thought there was a single
> reduce. This lead to a hard to find diagnose failure.
> Therefore, I propose separating out the configuration types as:
> class Configuration;
> // reads site-default.xml, hadoop-default.xml
> class ServerConf extends Configuration;
> // reads hadoop-server.xml, $super
> class DfsServerConf extends ServerConf;
> // reads dfs-server.xml, $super
> class MapRedServerConf extends ServerConf;
> // reads mapred-server.xml, $super
> class ClientConf extends Configuration;
> // reads hadoop-client.xml, $super
> class JobConf extends ClientConf;
> // reads job.xml, $super
> Note in particular, that nothing corresponds to hadoop-site.xml, which
> overrides both client and server configs. Furthermore, the properties from
> the *-default.xml files should never be saved into the job.xml.
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