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https://issues.apache.org/jira/browse/HADOOP-9150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13555597#comment-13555597
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Todd Lipcon commented on HADOOP-9150:
-------------------------------------
Hey Daryn.
I'm looking at implementing your #1 option above. Another issue, though, is
that checkPath() hard-codes {{NetUtils.getCanonicalUri}}. I don't really want
to have to make all of HDFS,HFTP,HSFTP,WebHDFS re-implement that code.
How does the following sound?
- Add {{protected FileSystem.canonicalizeUri(uri)}}. Default implementation
would add getDefaultPort() if the given URI has no port set, and if
getDefaultPort() > 0
- Make the default implementation of {{FileSystem.getCanonicalUri()}} call
{{canonicalizeUri(getUri())}}
- Change {{checkPath}} to call {{canonicalizeUri}}
- In all of the FileSystems which use real hostnames as their authority,
override {{canoncalizeUri}} to call {{NetUtils.canonicalizeUri}}
> 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, 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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