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From "Hoss Man (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SOLR-7884) Omit reverse lookups in SystemInfoHandler
Date Mon, 10 Aug 2015 20:59:45 GMT

    [ https://issues.apache.org/jira/browse/SOLR-7884?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14680752#comment-14680752
] 

Hoss Man commented on SOLR-7884:
--------------------------------

bq. The suggested fix for this is to replace the call to getCanonicalHostName by one to getHostName()
...

Hmmm.... I'm not convinced this is a good idea ... Just because that's what other libraries
use doesn’t mean it's a good fit in this context.  The intent of this information is to
inform clients what the _canonical_ hostname is for communicating with Solr.  If the local
hostname/DNS is missconfigured we don't want to lie to the user.

In my opinion, the approach discussed in SOLR-5043 would be a better method for dealing with
this.

(allthough in addition to that, updating SystemInfoHandler.init to pay attention to when the
node is operating in cloud mode and use the same "host" configuration option from CloudConfig
that the rest of Solr uses, and only do getCanonicalHostName as a fallback option.  -- At
least that way the only misconfiguration that can lead us to lying to the user is an explicit
misconfiguration of Solr, something the user running Solr is guaranteed to have control of)

----

bq. As Solr is shipped bundled with a desktop application, there is currently no workaround
because the user network configuration is beyond our reach.

I'm not sure i follow this reasoning -- even if you can't ensure the DNS/network of the machine
Solr is being deployed to is reliable, can't you specify SecurityManager settings to prevent
the process from doing DNS lookups? (in which case Solr should happily continue to function,
with or w/o correctly function DNS, w/o any delays)



> Omit reverse lookups in SystemInfoHandler
> -----------------------------------------
>
>                 Key: SOLR-7884
>                 URL: https://issues.apache.org/jira/browse/SOLR-7884
>             Project: Solr
>          Issue Type: Improvement
>    Affects Versions: 5.2.1
>            Reporter: Robert Krüger
>         Attachments: SOLR-7884.patch
>
>
> The method SystemInfoHandler.init contains this code:
> {code:java}
>   try {
>       InetAddress addr = InetAddress.getLocalHost();
>       hostname = addr.getCanonicalHostName();
>     } catch (UnknownHostException e) {
>       //default to null
>     }
>   }
> {code}
> The call to getCanonicalHostName triggers a DNS reverse lookup, that on Mac OSX times
out after 30 seconds if the current network setup has a problem with reverse lookup and then
returns the IP address as host name. In our product this leads to a hang of 2x30 seconds (one
for the SystemInfoHandler of the container and another one for that of the core) during startup
under these conditions. Unfortunately I have found no way to make this reproducible by simulating
it as it depends on local network config, os and whatever else.
> As Solr is shipped bundled with a desktop application, there is currently no workaround
because the user network configuration is beyond our reach.
> The suggested fix for this is to replace the call to getCanonicalHostName by one to getHostName(),
which is done for exactly this purpose (obtaining a host string for logging) in the popular
Logback framework (see http://logback.qos.ch/xref/ch/qos/logback/core/util/ContextUtil.html,
how they do it).
> Otherwise Solr has been working perfectly in this setup (bundled with a desktop app)
for a long time and it would be great to remove that last obstacle to make it a nicer citizen
bundlingwise.



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