[
https://issues.apache.org/jira/browse/YARN-4287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14970026#comment-14970026
]
Wangda Tan commented on YARN-4287:
----------------------------------
Some suggestions
1) RACK_LOCALITY_EXTRA_DELAY -> RACK_LOCALITY_DELAY, same as configuration
property name (rack-locality-delay)
2) Do you think if is it a good idea to separate old rack-locality-delay
computation (using getLocalityWaitFactor) and new rack-locality-delay config?
Now rack-locality-delay = min(old-computed-delay, new-specified-delay), since
the getLocalityWaitFactor has some flaws, I think we can make this configurable
so user can choose to use specified or computed.
Pseudo code may look like:
{code}
if type is OFF_SWITCH:
if rack-locality-delay specified:
delay = rack-locality-delay
else:
delay = computed-locality-delay
else if type is RACK_LOCAL:
delay = min(node-locality-delay, computed-or-specified-rack-locality-delay)
{code}
3)
bq. When we're getting rackLocal assignments, subsequent rackLocal assignments
should not be delayed
+1 to the fix, since this is a behavior change, do you think if we need to make
this configurable? This change could lead to #node-local container allocation
decreasing in some cases.
Thanks,
Wangda
> Capacity Scheduler: Rack Locality improvement
> ---------------------------------------------
>
> Key: YARN-4287
> URL: https://issues.apache.org/jira/browse/YARN-4287
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: capacityscheduler
> Affects Versions: 2.7.1
> Reporter: Nathan Roberts
> Assignee: Nathan Roberts
> Attachments: YARN-4287-v2.patch, YARN-4287.patch
>
>
> YARN-4189 does an excellent job describing the issues with the current delay
> scheduling algorithms within the capacity scheduler. The design proposal also
> seems like a good direction.
> This jira proposes a simple interim solution to the key issue we've been
> experiencing on a regular basis:
> - rackLocal assignments trickle out due to nodeLocalityDelay. This can have
> significant impact on things like CombineFileInputFormat which targets very
> specific nodes in its split calculations.
> I'm not sure when YARN-4189 will become reality so I thought a simple interim
> patch might make sense. The basic idea is simple:
> 1) Separate delays for rackLocal, and OffSwitch (today there is only 1)
> 2) When we're getting rackLocal assignments, subsequent rackLocal assignments
> should not be delayed
> Patch will be uploaded shortly. No big deal if the consensus is to go
> straight to YARN-4189.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
