Firefox image shenanigans

[esllou]

I spent a lot of last week pulling my hair out about the state of my vBulletin forum.

All the little images seem to be getting messed around and changed. The edit post icon would be a smilie. The quick reply icon would be an "indent more" icon and so on.

I took all my mods out and went back to pure vanilla style but the problem persisted but seemed to be better so I just left it and put it on my "to do" list.

then today, I was looking at a page on my site which has about 50 small gif images and noticed they were messed up a little. Pressed refresh and they went back to how they should have been. Odd.

closed FF and went back to page and saw about 4 of the images were changed around again. Went into page source and saw that where 1.gif should have been, 7.gif had loaded.

Pressed refresh. All back to normal again.

Now:

is this a FF problem?
a pc problem?
a server problem?
a poltergeist problem?

:-)

[MatthewHSE]

Did you try other browsers, or just Firefox? I've seen this before cross-browser when images or image references have been stored in MySQL databases. I don't know if that's the case here - I've never run a vBulletin board to know how it works - but it might be worth a check.

[tedster]

Went into page source and saw that where 1.gif should have been, 7.gif had loaded.

Do you mean the page source actually said "7.gif" -- or that it said "1.gif" but the browser loaded "7.gif" instead.

[dmjw01]

I have seen this problem before on one or two sites. I suspect it's related to poor server-side support for pipelining.

I don't know the details, but it seems as if the local Firefox cache gets confused - in other words, the cache contains "7.gif" but the cache index says that the image is "1.gif". Hence when the browser renders the page using cached data, images appear in the wrong place. It only happens on certain websites.

Clearing your cache and doing a refresh on the page might solve the problem immediately, but it'll come back sooner or later.

Turning pipelining off in Firefox seems to help. If that works, then the ideal solution would be to upgrade your webserver to one that supports pipelining properly. It would be nice if FF allowed you to turn pipelining off selectively for different servers.
__
David

[MatthewHSE]

It would be nice if FF allowed you to turn pipelining off selectively for different servers.

I don't know much about HTTP headers, but doesn't the server report its name, software, etc., before any HTML is sent to the browser? If so, it should be trivial (for someone who knows how) to write a Firefox extension to automatically turn off pipelining for servers that don't support it, particularly since IIS is probably about the only thing out there in any kind of significant numbers that doesn't properly support pipelining by now.

[esllou]

I want to thank everyone for responding to this issue. To the person who asked about the source code, yes..the code says 1.gif and is fine but 7.gif gets loaded in its place.

so it sounds as if it's a problem with FF which is about 8% of my audience of this particular site. Is it worth taking this issue to my hosts, who are an expensive "quality" host?

the problem really only arises on pages where there are multiple images and only sometimes. And it may be that my particular set of circumstances worsens the problem and other FF users may not be seeing what I see.

[tedster]

It certainly might be specific to your machine and your installation of FireFox.

If those are the real names of your images and not just shorthand versions for the sake of this thread, then it also might be worth the effort to give these images a name that is more than one character long -- since apparently it is the Firefox cache that is getting confused, this might give the internal code more of a fighting chance.

I doubt that your host can do much with this -- since the source code is leaving the server in perfect shape.

[Mr Bo Jangles]

have you changed the config of Firefox at all? Modded it, applied plugins?
I had done all of above and was getting images in FF screwed up and this was only resolved when I started over again with FF - and the critical part was ditching the Profile FF file.

[esllou]

I have only two plugins...mouse gestures and edit css.

I have changed maybe two things in the config but have had those altered for a year and really only noticed this in last couple of weeks.

Blimey, to think of the time I wasted on my vBulletin forum and starting support tickets over at vbulletin.com as I was sure it was the sparkly new 3.5.0 forum that was causing the errors....

[dmjw01]

so it sounds as if it's a problem with FF

Not really.

Assuming the pipelining thing is the cause of the problem (which would need further testing to prove or disprove it - don't just take my word for it!) then the problem is with the server, not Firefox.

Also, you should find that pipelining is turned off by default in Firefox when you first install it. If you type "about:config" into the address line of FF, and search for "network.http.pipelining", is it set to true on your copy of Firefox? If so then you, or someone else, has modified that setting; if it's set to false then pipelining is obviously not the source of your difficulty. As far as I know, pipelining cannot be turned on or off through the normal configuration dialogs.

[esllou]

it was set to true as it was one of the things I changed when I first moved over to FF about a year ago. A suggestion I picked up on this forum actually.

But it seems my host's server has a problem with this setting so I am going to get in touch with them about it now.

[esllou]

I have followed this up with my host and they have been aware of the problem for some time. It's not that there is a "problem" with the server, just that they are protecting themselves.

Allowing pipelining may be all the rage with those wanting to "optimise" FF but can be damaging to a busy server. In particular:

We do not condone the pipelining technique as server resources are finite... There are at most 255 connection slots, per Apache, each of which is serving roughly 50 sites... This is a fine balance between a multitude of various resources like file handles, TCP connections, memory, etc etc etc etc...If we find someone that has consumed all available connection slots on an Apache, we will firewall them from our network, as we consider that to be abusive behavior and causes a DoS against our Apache engines...

[dmjw01]

A slightly over-dramatic response from your ISP, I think.

I must confess that I'm no expert in HTTP pipelining, but I was under the impression that it couldn't be described as "abusive" or an over-use of server resources.

What they're talking about is consuming extra connection resources on the server, but I thought pipelining actually avoids using extra connections by making several file requests in a single HTTP request - thus consuming fewer server connections.

Can someone tell me whether this is a reasonably correct understanding of what pipelining is doing?

[dmjw01]

I've done a little reading about pipelining now, and I'm even more convinced that the person at your ISP who wrote that response has no idea what they're talking about.

Pipelining should make things better for the server, because the connection is used more efficiently. When the browser wants to retrieve files A, B and C, the server can fulfill the requests immediately instead of waiting for the next request. The connection therefore lasts less time, thus freeing up server resources for other users.

I think it looks like nonsense to suggest that pipelining is "abusive". What do others think?

[borninblood]

You might want to consider installing the extension for FireFox that allows you to view a page as if you were running Internet Explorer.

It can be found here..

[addons.mozilla.org...]

I had a VBulletin forum a good while back and changed because it was being an ass.