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https://issues.apache.org/jira/browse/YARN-140?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13472551#comment-13472551
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Ahmed Radwan commented on YARN-140:
-----------------------------------
Thanks Tucu,
Yes Tucu, I already had it like that in rev4 of the patch, but after a second
thought I changed it in the latest patch. It is true that the capacity of root
should be always 100, or otherwise an exception will be thrown, see
ParentQueue.java:116:
{code}
if (rootQueue &&
(rawCapacity != CapacitySchedulerConfiguration.MAXIMUM_CAPACITY_VALUE))
{
throw new IllegalArgumentException("Illegal " +
"capacity of " + rawCapacity + " for queue " + queueName +
". Must be " + CapacitySchedulerConfiguration.MAXIMUM_CAPACITY_VALUE);
}
{code}
However, I think we shouldn't overwrite a configuration given by the user, we
can just provide the correct default if it is missing.
Overwriting a configuration can have a negative consequence of having a
configuration file contents which contradicts what is really used by the
scheduler, which is problematic.
Using the latest patch, if the user sets the root capacity to a wrong value,
then the system will throw an Exception, and the user will know it is wrong and
correct it. But if the user misses it, the default will be picked. This is why
I changed to {{&&}}. What do you think?
> Add capacity-scheduler-default.xml to provide a default set of configurations
> for the capacity scheduler.
> ---------------------------------------------------------------------------------------------------------
>
> Key: YARN-140
> URL: https://issues.apache.org/jira/browse/YARN-140
> Project: Hadoop YARN
> Issue Type: Bug
> Components: capacityscheduler
> Reporter: Ahmed Radwan
> Assignee: Ahmed Radwan
> Attachments: YARN-140.patch, YARN-140_rev2.patch,
> YARN-140_rev3.patch, YARN-140_rev4.patch, YARN-140_rev5_onlyForJenkins.patch,
> YARN-140_rev5.patch, YARN-140_rev5_svn_mv.patch
>
>
> When setting up the capacity scheduler users are faced with problems like:
> {code}
> FATAL org.apache.hadoop.yarn.server.resourcemanager.ResourceManager: Error
> starting ResourceManager
> java.lang.IllegalArgumentException: Illegal capacity of -1 for queue root
> {code}
> Which basically arises from missing basic configurations, which in many
> cases, there is no need to explicitly provide, and a default configuration
> will be sufficient. For example, to address the error above, the user need to
> add a capacity of 100 to the root queue.
> So, we need to add a capacity-scheduler-default.xml, this will be helpful to
> provide the basic set of default configurations required to run the capacity
> scheduler. The user can still override existing configurations or provide new
> ones in capacity-scheduler.xml. This is similar to *-default.xml vs
> *-site.xml for yarn, core, mapred, hdfs, etc.
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