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From Robert Krüger (JIRA) <>
Subject [jira] [Commented] (SOLR-7884) Omit reverse lookups in SystemInfoHandler
Date Mon, 17 Aug 2015 08:18:45 GMT


Robert Krüger commented on SOLR-7884:

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)

It's more complicated than this. The problem we encounter is not DNS generally not working
but reverse lookup for local VPN addresses in some cases not working. Our application does
need DNS lookups in some places, so disabling that does not solve the problem.

> Omit reverse lookups in SystemInfoHandler
> -----------------------------------------
>                 Key: SOLR-7884
>                 URL:
>             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,
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

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