hadoop-common-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HADOOP-12878) Impersonate hosts in s3a for better data locality handling
Date Thu, 09 Jun 2016 19:48:21 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-12878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15322700#comment-15322700
] 

Steve Loughran edited comment on HADOOP-12878 at 6/9/16 7:47 PM:
-----------------------------------------------------------------

the star symbol 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.


was (Author: stevel@apache.org):
"*" 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: common-issues-unsubscribe@hadoop.apache.org
For additional commands, e-mail: common-issues-help@hadoop.apache.org


Mime
View raw message