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https://issues.apache.org/jira/browse/HADOOP-9150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13553256#comment-13553256
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Todd Lipcon commented on HADOOP-9150:
-------------------------------------
Hey Daryn. How's this patch look to you? Hoping to get this in for 2.0.3 since
it can cause a big (and unfortunately silent) perf regression for HA on
clusters with borked DNS.
> Unnecessary DNS resolution attempts for logical URIs
> ----------------------------------------------------
>
> Key: HADOOP-9150
> URL: https://issues.apache.org/jira/browse/HADOOP-9150
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs/s3, ha, performance, viewfs
> Affects Versions: 3.0.0, 2.0.2-alpha
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Critical
> Attachments: hadoop-9150.txt, hadoop-9150.txt, hadoop-9150.txt,
> log.txt, tracing-resolver.tgz
>
>
> In the FileSystem code, we accidentally try to DNS-resolve the logical name
> before it is converted to an actual domain name. In some DNS setups, this can
> cause a big slowdown - eg in one misconfigured cluster we saw a 2-3x drop in
> terasort throughput, since every task wasted a lot of time waiting for slow
> "not found" responses from DNS.
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