358387 - Synchronous XHR + DOMContentLoaded + big document = dead lock

Status: RESOLVED FIXED

(Core :: Networking: HTTP, defect)

Description

[Adam L. Peller]

This was reported as a problem against the Dojo 0.4 release which employs synchronous XHRs and uses DOMContentLoaded instead of window.onload to speed up page loading.
http://trac.dojotoolkit.org/ticket/1640

Ths problem can be reproduced at this URL, which uses synch XHRs in the Dojo bootstrap:
http://dojotoolkit.org/~jburke/dj4/dojo/tests/hang/hang.html

Or by using the sample non-Dojo snippet included in Dojo ticket #1640 submitted by [e-mail]:

<html> <head> <script src="dojo/dojo.js.uncompressed.js"></script> <script> function docLoaded() { var http = dojo.hostenv.getXmlhttpObject(); http.open('GET',"document.xml", false);

alert("Calling sync XMLHttpRequest - it's gonna freeze ..."); http.send(null); alert("Well, i guess they've fixed it, response (first fragment ) is " + http.responseText.substring(0, 255)); }

if (document.addEventListener) document.addEventListener("DOMContentLoaded", docLoaded, false);

</script> </head> <body> <img src="img/Sunset.jpg" width="100" /> <img src="img/Sunset1.jpg" width="100" /> <img src="img/Sunset2.jpg" width="100" /> <img src="img/Sunset3.jpg" width="100" /> <img src="img/Sunset4.jpg" width="100" /> </body> </html>

The workarounds are ugly - one proposed workaround was to prevent images from loading by removing src attributes from img during loading and put them back after loading.

Comment 1

[Darin Fisher]

This sounds like a duplicate bug of one that was fixed by thread manager.  Synchronous XHR is nearly useless in Gecko 1.8 and earlier.  Have you tested trunk builds?  This should be far less of an issue since thread manager landed.

Comment 2

[Ronald Tilby]

Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a1) Gecko/20061027 Minefield/3.0a1 ID:2006102704 [cairo]

URL WFM on current trunk nightly.

Comment 3

[Adam L. Peller]

Hey Darin.  Looks terrific in the trunk!  How can we get this code into 2.0?  (I won't even try to ask for 1.5, eh? :-)

Comment 4

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

The code to fix this was too big a change to port to the 2.0 branch. Don't worry, there's life after 2.0 too.

Comment 5

[James Burke]

There is a new URL to use for testing this bug (the URL listed above it no longer available):

http://download.dojotoolkit.org/release-0.4.0/dojo-0.4.0-ajax/tests/loader/1640/hang.html

Comment 6

[James Burke]

Using this URL to test:
http://download.dojotoolkit.org/release-0.4.0/dojo-0.4.0-ajax/tests/loader/1640/hang.html

This appears to be fixed in Firefox 3 beta 3. Tested with:
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9b3) Gecko/2008020511 Firefox/3.0b3

Comment 7

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

Marking fixed per above comments.

Comment 8

[Jason Bassford]

No bug / patch referenced as the fix.

-> WORKSFORME

Comment 9

[Jonas Sicking (:sicking) No longer reading bugmail consistently]

As mentioned in comment 1, this was fixed by bug 326273