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https://issues.apache.org/jira/browse/YARN-3025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14292973#comment-14292973
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Tsuyoshi OZAWA commented on YARN-3025:
--------------------------------------

{quote}
Lets say 1000 AMs pinging every 1 sec.
{quote}

I expected that we only synchronize the state only when RM detect the the 
difference of blacklists before and after the heartbeat. I thought probability 
to mark nodes as blacklist is not so high. What do you think?

{quote}
Yes. But that would mean that the RM cannot provide the latest updates.
{quote}

I think it can be acceptable for many cases if the blacklist node are updated 
within 1 min or some minutes e.g. for admin's knowing cluster information. In 
this case, we should also document it explicitly to know the trade off of the 
sync interval.

> Provide API for retrieving blacklisted nodes
> --------------------------------------------
>
>                 Key: YARN-3025
>                 URL: https://issues.apache.org/jira/browse/YARN-3025
>             Project: Hadoop YARN
>          Issue Type: Improvement
>            Reporter: Ted Yu
>
> We have the following method which updates blacklist:
> {code}
>   public synchronized void updateBlacklist(List<String> blacklistAdditions,
>       List<String> blacklistRemovals) {
> {code}
> Upon AM failover, there should be an API which returns the blacklisted nodes 
> so that the new AM can make consistent decisions.
> The new API can be:
> {code}
>   public synchronized List<String> getBlacklistedNodes()
> {code}



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