335705 - hang while loading (lots of) images

Status: VERIFIED DUPLICATE of bug 335715

(Core :: Graphics: ImageLib, defect)

Description

[Shawn Carnell]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.2) Gecko/20060308 Firefox/1.5.0.2
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.2) Gecko/20060308 Firefox/1.5.0.2

We have several folks witnessing firefox.exe hang when they visit a page
we're developing.  We are seeing this happen in our dev environment but
you can see pretty much the exact page at
http://imakealpha.com/.pages/edit.jsp (free login needed, (apologies)).

The facts: 

    * This doesn't happen in IE.
    * FF becomes unresponsive to UI and doesn't redraw.
    * When hung, FF consumes up to 50% of the CPU depending on the
      client box.
    * The hang appears to be related to the request/response ordering.
          o The problem only happens on identical dev hosts and not on
            our qa or prod hosts (yet).
          o If i perturb the request/response ordering by starting
            Charles on my client, things work.
            (http://xk72.com/charles/index.php)
    * The hang appears to be related to image processing.
          o The hang happens while loading images, often at about the
            same image even for different users.
          o The stack for FF consistently shows that it's looping
            in/around jpeg_idct_islow
            (http://lxr.mozilla.org/mozilla1.8/ident?i=jpeg_idct_islow)
                + For me, FF is making about 300 context switches per
                  second for jpeg_idct_islow.
          o Ironically, once when FF hung for me, Thunderbird froze,
            too, in jpeg_free_large.  (Hasn't repro'ed.  Red herring?)
    * If i debug firefox.exe, VS.NET reports that "The process appears
      to be deadlocked (or is not running any user-mode code)."
    * Ethereal consistently notes that 16-17 image responses have
      malformed packets (always the same images) but there appears to be
      nothing wrong with the images.

I really need to get more visibility into what's going on inside FF.  I
can't find a debug build of it online.  Even if i built one, turning on
debugging/logging might perturb the system enough to mask the bug.

Any ideas on what the problem could be or on how to go about diagnosing it? 

Reproducible: Always

Steps to Reproduce:
1. Just visit the URL and witness FF start to load but then hang.  

Unfortunately, this only manifests on an internal server but the external URL above is essentially the same page.  I think it's a timing issue.

Actual Results:  
FF hangs, waiting, consume some CPU in jpeg_idct_islow.

Expected Results:  
FF should just load the page.

Please feel free to reach out to me.  I'm actively debugging this and i'm eager to supply any additional information that folks need me to dig up.

Comment 1

[Mike Shaver (:shaver emeritus)]

Can you get a fuller stack or profile with Shark or Activity Monitor on the Mac, and attach the relevant part of that?

Comment 2

[Jesse Ruderman]

Looks like this was accidentally submitted twice.

*** This bug has been marked as a duplicate of 335715 ***