Re: InetAddress.getLocalHost() returns different values in different threads

From:

Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 25 Oct 2007 14:28:26 -0700

Message-ID:

<4M-dne5PXLPil7zanZ2dnUVZ_qXinZ2d@wavecable.com>

ociardhp wrote:

Hi

I've come across an unusual situation where a thread started in the
init method of an applet returns a particular value for
InetAddress.getLocalHost() whereas threads started at a later point in
time return a different value.

The output I see in my logs is as follows:
INFO: 17:41:39 com.cominded.diag.UpstreamProxy@6131844: Thread started
in init running on MSIE6/10.0.1.185
INFO: 17:41:47 com.cominded.diag.UpstreamProxy@6131844: New thread
running on localhost/127.0.0.1
INFO: 17:41:49 com.cominded.diag.UpstreamProxy@6131844: Thread started
in init running on MSIE6/10.0.1.185

This has been a pain to deal with as the applet acts as an RMI server
and client and so connections created by the new thread result in an
AccessControlException. Invoking
System.setProperty("java.rmi.server.hostname", "localhost"); before
taking any RMI action works on OSX/Firefox, but sadly not on Vista/
Firefox. Regardless, I assume creating a thread pool will solve the
problem.

Mostly I'd be interested in an explanation of why InetAddress exhibits
this behaviour. Many thanks to anyone who provides one.

Paul

Two IP address can have the same hostname, and two hostnames can share
an IP address. Generally its up to the DNS server to decide how to
differentiate these. Some DNS servers are designed to round-robin the
IP address in order to better load balance requests.

HTH,
Daniel.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>