Red Hat Bugzilla – Bug 126663
Resolver delays on unconnected laptop
Last modified: 2007-11-30 17:07:02 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.4.2) Gecko/20040301 Description of problem: On an unconnected laptop, trying to look up using the resolver takes a considerable delay. Connecting a laptop to a network makes can make it change its name to something which is only remotely resolvable. After disconnecting it again, apparently unrelated programs like emacs takes long to start since they wait for a resolver timeout. Version-Release number of selected component (if applicable): glibc-2.3.2-95.20 How reproducible: Always Steps to Reproduce: 1. Start a laptop without any network 2. Run "emacs". 3. Connect laptop to network 4. Run "emacs". 5. Take the network interface down again 6. Run "emacs". Actual Results: The third emacs invocation has a significantly slower startup. Additional info: Emacs apparently wants to look up the local hostname. Initially, this is "localhost". When connecting the laptop, it sets its hostname. This hostname is not known locally, but requires a DNS lookup. When disconnecting again, the host name remains the one found out with DHCP during connection. But now, this name can no longer be looked up. Doing an strace of a command reveals it is doing a sendmsg call to the DNS server, and then waits for a reply. However, the return code for the sendmsg call is an error (ENETUNREACH). It seems it would make sense to return immediately in this case; if the question could not be sent, there is not much point in waiting for an answer. Would this be hard to do? I tried to take a look in the resolver code, but I get lost among all the defines.
Internal RFE bug #129472 entered; will be considered for future releases.
This bug is filed against RHEL 3, which is in maintenance phase. During the maintenance phase, only security errata and select mission critical bug fixes will be released for enterprise products. Since this bug does not meet that criteria, it is now being closed. For more information of the RHEL errata support policy, please visit: http://www.redhat.com/security/updates/errata/ If you feel this bug is indeed mission critical, please contact your support representative. You may be asked to provide detailed information on how this bug is affecting you.