On Wed, Mar 05, 2008 at 01:47:23PM +0100, Landry Breuil wrote: | On Wed, Mar 5, 2008 at 1:18 PM, Mayuresh Kathe <[EMAIL PROTECTED]> wrote: | > | > On Wed, Mar 5, 2008 at 5:46 PM, Karl Sjodahl - dunceor | > <[EMAIL PROTECTED]> wrote: | > > | > > On Wed, Mar 5, 2008 at 12:59 PM, Mayuresh Kathe | > > <[EMAIL PROTECTED]> wrote: | > > > Hi, | > > > | > > > There's a strange incident that's repeatable on my system (4.2). | > > > | > > > Open up Firefox, make it load "www.dilbert.com", then open another tab | > > > and visit any other website, then do the same for 2~3 more tabs. | > > > | > > > The first (dilbert) tab takes a long time to load during which the | > > > other tabs too show nothing, they get stuck at "Looking up..." | > > > | > > > Is it a Firefox problem or something to do with the system? | > > > | > > > Best, | > > > | > > > ~Mayuresh | > > > | > > > | > > | > > I have seen this on both Windows and OpenBSD. The later firefox | > > releases (like from 2.0.0.3-2.0.0.5 something) I have seen problems | > > with having more tabs open. | > > I used to have a lot of tabs but now I have restricted myself to 3-4 | > > or firefox is not useable. | > | > I forgot to mention, my Firefox version is 2.0.0.6 | > Also I've only got a total of 3~4 tabs open while performing the Dilbert test. | > Taking your cue, I tried an experiment, I opened up 10 tabs, but | > without the Dilbert site and all of them opened up in parallel. | | Seems like an ipv6-dns-resolution problem to me.
A bit of background here : Firefox can do AAAA lookups (for IPv6 addresses) by default for websites you visit. Some DNS servers don't like this sort of query and, in stead of saying "hey, I dont understand what you want", they ignore you in the hope that you go away. Things time out on your end, your system will do a A lookup and from there you can continue browsing the website. In the case of the dilbert site, this doesn't seem to be the case. Apparantly, one of the NS'en is not responding to queries at all (nor ICMP Echo Requests - it's probably down or disconnected from the net temporarily). Your caching NS may be trying to contact this one nameserver. It'll wait for the timeout and then try one of the other NS'en. The problem is exacerbated by the fact that www.dilbert.com has a TTL of 300 seconds, so your caching NS doesn't keep this record in memory too long. The problem is that the resolver in OpenBSD isn't reentrant. If it's doing nameresolution, it'll not do another one in parallel. So while you wait for www.dilbert.com to get resolved (which takes long because of this timeout), you open a new tab, enter an address and your machine will have to resolve that too, which gets queued up (doesn't get handled in parallel), so the other tab also waits on www.dilbert.com to get resolved. You can test this hypothesis by going to a website by its IP address. Try visiting http://129.128.5.191/ (http://www.openbsd.org/) while you're waiting for www.dilbert.com to load. Visiting by IP should work (as it doesn't require a DNS lookup). Cheers, Paul 'WEiRD' de Weerd -- >++++++++[<++++++++++>-]<+++++++.>+++[<------>-]<.>+++[<+ +++++++++++>-]<.>++[<------------>-]<+.--------------.[-] http://www.weirdnet.nl/
