643145 - Corrupted Extjs apparently cached in xpc.mfl xul.mfl

Status: RESOLVED WONTFIX

(Core :: General, defect)

Description

[Pat Tressel]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Firefox/3.6.15 ( .NET CLR 3.5.30729)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Firefox/3.6.15 ( .NET CLR 3.5.30729)

Infrequently, and apparently at random, a page that includes the Ext files ext-all.js and/or ext-all-debug.js will fail.  If firebug is installed, there will be an odd syntax error in Ext.  Once this happens, the error will persist, and affect other pages that use those files.  Clearing cache does not get rid of the error, but finding and deleting xpc.mfl and xul.mfl does.  This is not WinXP specific -- has been seen on Windows 7.

Comparing the copy of ext-all-debug.js that the browser has with the original shows a chunk missing out of the middle.  These files are very large, so it may not be specific to Ext, just due to the size.

I work on a FOSS project that uses Ext -- another developer on the project has also seen this error, and has seen posts about it elsewhere.  Since both of us have firebug installed and used that to diagnose it, we can't be sure firebug isn't involved.  But a web search turns up posts that report problems in pages that use Ext that sound similar.  Given how infrequently this happens, the best way to find it might be a stress test that loads a page with one of these files repeatedly.

Regardless of how the problem happens, it would be nice if clearing the cache could get rid of the corrupted copy of Ext.  What about having "clear the cache" also delete xpc.mfl and xul.mfl?  That way people who encounter this won't have to do surgery on their profiles.

Reproducible: Sometimes

Steps to Reproduce:
1. Install firebug.
2. Open a page that uses ext-all-debug.js or ext-all.js
3. Keep doing 2. over and over.
4. Eventually, get an odd syntax error in ext-all{-debug}.js on some line that does not appear to have an error.
5. Extract the copy of ext-all-debug.js that the browser has (e.g. via firebug).  Compare with original -- notice some lines missing out of the middle.
6. Clear cache -- error is still there.
7. Exit the browser, find and delete xpc.mfl xul.mfl , restart -- error is gone.
Actual Results:  
After many successful uses of Ext, with no change in Ext itself, it gets an odd syntax error.  Ext file appears corrupted.  Clearing cache, restarting, don't fix it.  Deleting xpc.mfl and xul.mfl does.

Expected Results:  
No corruption to Ext.  But if there is, clearing cache should be able to fix it, e.g. should clear xpc.mfl and xul.mfl as well as Cache directory contents.

Comment 1

[Sylvestre Ledru [:Sylvestre]]

No activity for a while and probably fixed/not needed anymore. Closing.