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https://issues.apache.org/jira/browse/HADOOP-9150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13560759#comment-13560759
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Daryn Sharp commented on HADOOP-9150:
-------------------------------------
I'm also kind of leaning towards a final on {{getCanonicalUri()}}. If someone
overrides it then there would be an inconsistency in calling
{{getCanonicalUri()}} and {{getCanonicalUri(getUri())}}.
I think the comparison {{getDefaultPort() != 0}} should be {{getDefaultPort() >
0}} since -1 signifies no port to URI. I find it very odd that the default
impl returns 0 instead of -1. Perhaps that should be changed? If so, maybe it
should be {{getDefaultPort() != -1}}.
Very minor, but I'd consider renaming {{canonicalizeUri(URI)}} to
{{getCanonicalUri(URI)}}. If you disagree, that's ok.
> 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,
> hadoop-9150.txt, 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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