On Wed, Mar 5, 2008 at 6:50 PM, Paul de Weerd <[EMAIL PROTECTED]> wrote: > > 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).
Paul, I tried your idea of starting up www.dilbert.com and then visiting http://129.128.5.191/ (the openbsd website). It worked as you'd predicted. So I guess its the problem with the OpenBSD resolver.
