313895 - Render Mode changes betweet quirks and standards compliant irregularly

Status: RESOLVED DUPLICATE of bug 261892

(Core :: DOM: HTML Parser, defect)

Description

[Lev Povalahev]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.12) Gecko/20050915 Firefox/1.0.7
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.12) Gecko/20050915 Firefox/1.0.7

Press Reload several times, sometimes the page is rendered in quirks mode instead of standards compliant mode. It happens very irregularly. Tested with the nightly build of Deer park as of 26.10.05, the problem occurs there too.

Reproducible: Sometimes

Steps to Reproduce:

Comment 1

[Lev Povalahev]

Very strangely, the problem does not occur when accessing html file:
http://pstoever.de/test.html

The only difference between the files is that in the php file the xhtml header is being written with php.

Comment 2

[Dave Townsend [:mossop]]

WFM, consistently CSS1Compat mode. Please try retesting with the latest firefox beta.

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a1) Gecko/20051026 Firefox/1.6a1 ID:2005102605

Comment 3

[Lev Povalahev]

Installed firefox beta 2 ans still getting the problem. 
Here's an automated test:
http://pstoever.de/test2.php

Comment 4

[Lev Povalahev]

The numbers from this automated test vary greatly.

Now I'm getting
CSS1: 136 BackCompat: 219

Comment 5

[Dave Townsend [:mossop]]

Left this for a while:

rendering mode: CSS1Compat countingCSS1Compat: 428 BackCompat:

I suggest you test in firefox's safe mode. Also please give the build ID of the beta you are testing with.

Comment 6

[Uri Bernstein]

I'm seeing this with a latest trunk build:
Mozilla/5.0 (Macintosh; U; PPC Mac OS X Mach-O; en-US; rv:1.9a1) Gecko/20051026 Firefox/1.6a1 ID:2005102604

Comment 7

[Lev Povalahev]

tested it with fresh profile and this build:
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a1) Gecko/20051026 Firefox/1.6a1

problem persists

Comment 8

[philip stöver]

CSS1Compat: 2293 BackCompat: 432

on

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.12) Gecko/20050915 Firefox/1.0.7

Comment 9

[Dave Townsend [:mossop]]

Tested in latest branch too:

rendering mode: CSS1Compat countingCSS1Compat: 630 BackCompat:

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8) Gecko/20051026 Firefox/1.5 ID:2005102603

Comment 10

[Uri Bernstein]

The problem here seems to be that the code for locating and parsing the DOCTYPE is  sometimes called before the line containing the DOCTYPE was read from the socket. I assume this helps with the PHP but not with a static file is that the PHP flushes the socket after the XML declaration (the first line).

I'm pretty sure I saw a similar bug report before. I'll look for it.

Comment 11

[Uri Bernstein]

See bug 268442 (which uses JavaScript to create the same kind of problem) , especially bug 268442 comment #2 (which says "this bug can be reproduced with network packets too" - presumably the case with the current example).

BZ, mrbkap - should this be dupe of 268442, or do you want it as a separate bug?

Comment 12

[Boris Zbarsky [:bzbarsky]]

Probably worth keeping as a separate bug.

Comment 13

[Uri Bernstein]

Bug 261892 seems to describe this exact issue. marking duplicate.

*** This bug has been marked as a duplicate of 261892 ***