[
https://issues.apache.org/jira/browse/HADOOP-12878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15322700#comment-15322700
]
Steve Loughran commented on HADOOP-12878:
-----------------------------------------
"*" is certainly something that is used in resource requests...I'd don't see it
being used in any filesystem block location status calls. I suspect that any
long-lived application will be doing hostname matching on the blocks that come
back for locality —and may not work with a "*" (it's not a hostname after all),
or not treat it that well.
Assuming the hostname was configurable: you'd give it a list, it'd return a
random subset of them, people could experiment with "*" and
"offsite.example.org" to see what worked well.
> Impersonate hosts in s3a for better data locality handling
> ----------------------------------------------------------
>
> Key: HADOOP-12878
> URL: https://issues.apache.org/jira/browse/HADOOP-12878
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.8.0
> Reporter: Thomas Demoor
> Assignee: Thomas Demoor
>
> Currently, {{localhost}} is passed as locality for each block, causing all
> blocks involved in job to initially target the same node (RM), before being
> moved by the scheduler (to a rack-local node). This reduces parallelism for
> jobs (with short-lived mappers).
> We should mimic Azures implementation: a config setting
> {{fs.s3a.block.location.impersonatedhost}} where the user can enter the list
> of hostnames in the cluster to return to {{getFileBlockLocations}}.
> Possible optimization: for larger systems, it might be better to return N
> (5?) random hostnames to prevent passing a huge array (the downstream code
> assumes size = O(3)).
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
