Weird Firefox Problem

Once again, I find myself turning to this wonderful series of tubes for help on a weird problem.

I have Firefox (Iceweasel) on all the computers I regularly use. One of these computers has had a persistent problem.

After using it for awhile, it takes a really long time to look up hostnames in DNS. And after upgrading to Firefox 3, it got much worse. Not only did name resolution get slow, but sometimes page loads would get exceptionally slow as well. I could have 5 tabs open, and all of a sudden at the magic moment, nothing would load on any tab. It was as if I was being hit by 75% packet loss. And new pages wouldn’t load, either.

tcpdump showed Firefox not even sending out packets at these times. After a few minutes, it might be back to normal. But I could always quit and restart and it would be fine.

Now, here’s the weird thing: I’ve eliminated every possible difference I can think of between this one machine and the others I use Firefox on. My plugins and extensions are the same set with the same versions. My configuration is the same. When this problem is happening, other network-related programs (even other web browsers) on the same machine are working fine. Nobody else here seems to be having this problem.

Any ideas?

17 thoughts on “Weird Firefox Problem

  1. Faulty NIC, maybe?

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    John Goerzen Reply:

    Maybe, but probably not. tcpdump on the local machine doesn’t show problems, plus even while Firefox is having its little fit, I can use Konqeuror without any problem.

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  2. Not the old issue of DNS requestsbeing forced to be resolved sequentially?

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    John Goerzen Reply:

    Not familiar with that one. Got a URL where I could read about it?

    Thanks!

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  3. I had this bug recently as well, I _think_ it first appeared when I tried switching to a beta of FF3. The only way I managed to get rid of it was copy my out-of-date (by a few months) profile from an old machine and try and install all the add-ons I’d installed since then :s

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  4. Is one system 64 bit versus the other being 32 by any chance? I have issues on my 64 bit system with firefox hanging as you describe with nspluginwrapper (sometimes) when visiting sites with flash adverts.

    Regardless, if you can catch it in action (or, in inaction, I suppose), try a strace -p `pidof firefox` and see what it’s stuck on.

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    Clifford W. Hansen Reply:

    I am running only 32bit and sometimes have this same issue, and I also believe it to be flash related.

    It is happening less often since installing Flash block, but unfortunately you need to load flash for some sites…

    Then again it could also be caused by rouge js…

    @ray thanks for the strace tip will try that next time it happens and try confirm some of what I rambled ;)

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  5. fsync() can be an issue if there’s heavy disk I/O from other processes.

    Another major problem now is the limit of 2 connections per host(name), in conjunction with use of long-lived connections for “AJAX” applications.

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  6. fsync() was a good guess. But I don’t think it’s the right one in this case. The problem continues for 2-3 minutes when it happens, happens with the machine is otherwise mostly idle, and doesn’t coincide with slowness in any other apps.

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