I think it would be better to have the client retrieve the default
configuration.  Not all configuration settings are simple overrides.   Some
are read-modify-write operations.

This also fits the current code better.


On 5/19/08 6:38 AM, "Steve Loughran" <[EMAIL PROTECTED]> wrote:

> Alejandro Abdelnur wrote:
>> A while ago I've opened an issue related to this topic
>> 
>>   https://issues.apache.org/jira/browse/HADOOP-3287
>> 
>> My take is a little different, when submitting a job, the clients
>> should only send to the jobtracker the configuration they explicitly
>> set, then the job tracker would apply the defaults for all the other
>> configuration.
>> 
>> By doing this the cluster admin can modify things at any time and
>> changes on default values take effect for all clients without having
>> to distribute a new configuration to all clients.
>> 
>> IMO, this approach was the intended behavior at some point, according
>> to the Configuration.write(OutputStream) javadocs ' Writes non-default
>> properties in this configuration.'. But as the write method is writing
>> default properties this is not happening.
> 
> I'll keep an eye on that issue. I think a key problem right now is that
> clients take their config from the configuration file in the core jar,
> and from their own settings, You need to keep the settings in sync
> somehow, and have to take what the core jar provides.
> 
> 
>> This approach would also get rid of the separate mechanism (zookeeper,
>> svn, etc) to keep clients synchronized as there would be no need to do
>> so.
> 
> zookeeper and similar are to keep the cluster alive; they shouldnt be
> needed for clients, which should only need some URL of a job tracker to
> talk to.

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