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https://issues.apache.org/jira/browse/YARN-2495?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14354362#comment-14354362
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Naganarasimha G R commented on YARN-2495:
-----------------------------------------

Hi [~wangda],
1) IMO method name was not readable when it was {{setAreNodeLabelsSet}} but i 
have changed it to {{setAreNodeLabelsSetInReq}} i feel this is sufficient. 
setAreNodeLabelsUpdated is same as earlier for which Craig had commented (which 
i also feel valid) 
{quote}
 I would go with areNodeLablesSet (all "isNodeLabels" => "areNodeLabels" 
wherever it appears, actually) - wrt "Set" vs "Updated" - this is primarily a 
workaround for the null/empty ambiguity and I think this name better reflects 
what is really going on (am I sending a value to act on or not), but I also 
think that this is a better contract, the receiver (rm) shouldn't really care 
about the logic the nm side is using to decide whether or not to set it's 
labels (freshness, "updatedness", whatever), so all that should be communicated 
in the api is whether or not the value is set, not whether it's an 
update/whether it's checking freshness, etc. that's a nit, but I think it's a 
clearer name.
{quote}
 Yes true lets finalize the name this time after that will start working on the 
patch if not it will be a wasted effort
5) 
{quote}
It will be problematic to ask admins make NM/RM configuration keep 
synchronized, so I don't want (and also not necessary) NM depends on RM's 
configuration.
So I suggest to make a changes: In NodeManager.java: when user doesn't 
configure provider, it should be null. In your patch, you can return a null 
directly, and YARN-2729 will implement the logic of instancing provider from 
config. In NodeStatusUpdaterImpl: avoid using isDistributedNodeLabelsConf, 
since we will not have "distributedNodeLabelConf" in NM side if you agree on 
previously comment, instead, it will check null of provider.
{quote}
Well modifications side is clear to me but is it good to allow the 
configurations being different from NM and RM ? Infact i wanted to discuss 
regarding whether to send shutdown during register if NM is configured 
differently from RM, but waited for the base changes to go in before discussing 
new stuff.

8) ??You can add an additional comments in line 626 for this.?? Ok will add a 
comment in LabelProvider.getLabels , Idea is LabelProvider is expected to give 
same Labels continiously untill there is a change and if null or empty is 
returned then No label is assumed

10) {{updateNodeLabelsInNodeLabelsManager -> updateNodeLabelsFromNMReport}} : 
will take care in next patch
{{LOG.info(... accepted from RM, use LOG.debug and check isDebugEnabled.}} : I 
feel better to Log this as "Error" as we are sending the labels only in case of 
any change and there has to be some way to identify if labels for a given NM 
and also currently we are sending out shutdown signal too.

??Make errorMessage clear: indicate 1# this is node labels reported from NM, 
and 2# it's failed to be put to RM instead of "not properly configured".??
i think i have captured first point, but any way will reframe it as {{"Node 
Labels <labels> reported from the NM with id <nodeID> were rejected from RM  
with exception message as <exceptionMsg>.}}

??Another thing we should do is, when distributed node label configuration is 
set, any direct modify node to labels mapping from RMAdminCLI should be 
rejected (like -replaceNodeToLabels).?? Will work on this once 2495 and 2729 
are done ..

Thanks [~vinodkv] & [~cwelch] for reviewing it 
??configuration.type -> configuration-type?? will take care in next patch
{quote}
Should RegisterNodeManagerRequestProto.nodeLabels be a set instead? 
Do we really need NodeHeartbeatRequest.areNodeLabelsSetInReq()? Why not just 
look at the set as mentioned in the previous comment?
{quote}
Well as craig informed, RegisterNodeManagerRequestProto.nodeLabels  is already 
a set but as by default empty set is provided by protoc, its req to inform 
whether labels are set as part of request hence areNodeLabelsSetInReq is 
required.
??RegisterNodeManagerRequest is getting changed. It will be interesting to 
reason about rolling-upgrades in this scenario.??
Well though i am not much aware of Rolling upgrades, i don't see any problems 
in a normal case because RM tries to read the labels from NM's req only when 
its distributed conf and also {{areNodeLabelsSetInReq}} is by default false. 
But I had queries when some existing setup they want to modify to distributed 
conf setup 
# Whether we need to send shutdown during register if NM is configured 
differently from RM ?
# Will the new configurations be added in NM and RM and then Rolling upgrade 
will be done ? or we do rolling upgrade first and then reconfigure & restart 
RM's and NM's

??How about we simply things? Instead of accepting labels on both registration 
and heartbeat, why not restrict it to be just during registration??
Well i have the same opinion of Wangda's on this point i feel both the flows we 
should take the same decision.

??We should not even accept a node's registration when it reports invalid 
labels??
Well i am little confused here, As per wangda's earlier comment i understand 
that it was your comment to send shutdown (which i felt correct in terms of 
maintenance)
{quote}
One more suggestion (as per suggested by Vinod Kumar Vavilapalli), when there's 
anything wrong with node label reported from NM, we should fail NM (ask it to 
shutdown and give it proper diagnostic message). This is because if NM report a 
label but rejected, even if RM tell NM this, NM cannot handle it properly 
except print some error messages (we don't have smart logic now). Which will 
lead to problems in debugging (A NM reported some label to RM but scheduler 
failed allocating containers on the NM). To avoid it, a simple way is to 
shutdown the NM and admin can take a look at what happened.
{quote}


> Allow admin specify labels from each NM (Distributed configuration)
> -------------------------------------------------------------------
>
>                 Key: YARN-2495
>                 URL: https://issues.apache.org/jira/browse/YARN-2495
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: resourcemanager
>            Reporter: Wangda Tan
>            Assignee: Naganarasimha G R
>         Attachments: YARN-2495.20141023-1.patch, YARN-2495.20141024-1.patch, 
> YARN-2495.20141030-1.patch, YARN-2495.20141031-1.patch, 
> YARN-2495.20141119-1.patch, YARN-2495.20141126-1.patch, 
> YARN-2495.20141204-1.patch, YARN-2495.20141208-1.patch, 
> YARN-2495.20150305-1.patch, YARN-2495.20150309-1.patch, 
> YARN-2495_20141022.1.patch
>
>
> Target of this JIRA is to allow admin specify labels in each NM, this covers
> - User can set labels in each NM (by setting yarn-site.xml (YARN-2923) or 
> using script suggested by [~aw] (YARN-2729) )
> - NM will send labels to RM via ResourceTracker API
> - RM will set labels in NodeLabelManager when NM register/update labels



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