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http://issues.apache.org/jira/browse/HADOOP-167?page=comments#action_12376520 ] 

Doug Cutting commented on HADOOP-167:
-------------------------------------

Can we stop the extra reads caused by addFinalResource() and 'new 
JobConf(Configuration)' by re-using the hash table instead of re-reading the 
files?  addFinalResource could simply read that single file, rather than 
re-read everything.  And 'new JobConf(Configuration)' could clone the contents 
of the configuration rather than re-reading it, no?  Or even use nested 
Properties...

One feature that's currently supported is that Configuration.write() only 
writes things that differ from the defaults.  This isn't essential, but it's 
nice.  The way it distinguishes is that defaults are always in a nested 
properties and non-defaults are always in the top-level properties.

> reducing the number of Configuration & JobConf objects created
> --------------------------------------------------------------
>
>          Key: HADOOP-167
>          URL: http://issues.apache.org/jira/browse/HADOOP-167
>      Project: Hadoop
>         Type: Improvement

>   Components: conf
>     Versions: 0.1.1
>     Reporter: Owen O'Malley
>     Assignee: Owen O'Malley
>      Fix For: 0.2
>  Attachments: remove-confs.patch
>
> Currently, Configuration and JobConf objects are created many times during 
> executing a job. In particular, the Task Tracker creates a lot of them. They 
> both clutter up the logs and parse the xml config files over and over again.

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