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https://issues.apache.org/jira/browse/ZOOKEEPER-1476?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14051982#comment-14051982
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Flavio Junqueira commented on ZOOKEEPER-1476:
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hi [~jillesvangurp], it is better if you upload repro code as attachments to
the jira rather than posting as a comment, just a hint. given that you spotted
the culprit, I was wondering if you want to propose a patch.
> ipv6 reverse dns related timeouts on OSX connecting to localhost
> ----------------------------------------------------------------
>
> Key: ZOOKEEPER-1476
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1476
> Project: ZooKeeper
> Issue Type: Bug
> Reporter: Jilles van Gurp
> Priority: Minor
>
> We observed a weird, random issue trying to create zookeeper client
> connections on osx. Sometimes it would work and sometimes it would fail. Also
> it is randomly very slow. It turns out both issues have the same cause.
> My hosts file on osx (which is an unmodified default one), lists three
> entries for localhost:
> 127.0.0.1 localhost
> ::1 localhost
> fe80::1%lo0 localhost
> We saw zookeeper trying to connect to fe80:0:0:0:0:0:0:1%1 sometimes, which
> is not listed (actually one in four times, it seems to round robin over the
> addresses).
> Whenever that happens, it sometimes works and sometimes fails. In both cases
> it's very slow. Reason: the reverse lookup for fe80:0:0:0:0:0:0:1%1 can't be
> resolved using the hosts file and it falls back to actually using the dns.
> Sometimes it actually works but other times it fails/times out after about 5
> seconds. Probably a platform specific settings with dns setup hide this
> problem on linux.
> As a workaround, we preresolve localhost now:
> Inet4Address.getByName("localhost"). This always resolves to 127.0.0.1 on my
> machine and works fast.
> This fixes the issue for us. We're not sure where the fe80:0:0:0:0:0:0:1%1
> address comes from though. I don't recall having this issue with other server
> side software so this might be a mix of platform setup, osx specific
> defaults, and zookeeper behavior.
> I've seen one ticket that relates to ipv6 in zookeeper that might be related:
> ZOOKEEPER-667. Perhaps the workaround for that ticket introduced this
> problem?
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