Comment #36 on issue 12754 by ben.rowland: "Resolving host" takes forever; disabling prefetching helps http://code.google.com/p/chromium/issues/detail?id=12754
@jar: Thanks for your comments. I haven't got to the bottom of this yet, but more results are in. I have www.google.com as my homepage, which seems to redirect to www.google.co.uk at some point. The histograms I sent were collected immediately upon startup, as soon as the problem was first observed. I am away from home at the moment, but will try the same tests against google's public DNS servers when I get back. I tried running nslookup against www.google.com a number of times, and could not reproduce the delay. I'm not sure where the resolution is being done, but I guess by my ISP. I recompiled chrome with some printfs, and isolated the delay to be within the call to the syscall getaddrinfo(), in host_resolver_proc.cc. So it's probably happening outside of chrome, excepting any strange thread-scheduling issues which seem unlikely. The delays I recorded through this method follow an interesting pattern. It always seems to be either ~30ms (normal), or a multiple of 5 seconds + ~30ms, so e.g. 5037, 10027, 15045ms. It varies up and down, but gives me a feeling that the delay gets worse as the load piles up. This looks to me like a well-defined 5-second timeout is happening somewhere, rather than just general slowness. I wrote a little test program which recreates the call to getaddrinfo (where the slowness was seen) with the same parameters. But the problem hostnames was resolved in an instant. Wish it were as simple as that. I'll try some load-testing once I get back to recreate the conditions of the prefetching on chrome startup - if I can reproduce it outside of chrome that would be interesting. The fact that this problem only appears during prefetching is interesting - it's as if it's the heavy load of rapid DNS requests which triggers it. If it turns out to be a problem with my ISP or LAN, it would be useful for other chrome users to know the resolution, as prefetching seems to set up some unique conditions. -- You received this message because you are listed in the owner or CC fields of this issue, or because you starred this issue. You may adjust your issue notification preferences at: http://code.google.com/hosting/settings -- Automated mail from issue updates at http://crbug.com/ Subscription options: http://groups.google.com/group/chromium-bugs
