840112 - javascript causes spinlock/unresponsive after window is maximized due to js::array_concat

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Wyatt Miler]

Attachment: 31_84_sec_lock.txt

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:20.0) Gecko/20130210 Firefox/20.0
Build ID: 20130210042017

Steps to reproduce:

Minimized window previous evening, expanded window back to normal. 


Actual results:

Browser opens up, and immediately goes into spinlock/unresponsiveness.

Comment 1

[[:Aleksej]]

Which JavaScript?

Comment 2

[Wyatt Miler]

(In reply to Aleksej [:Aleksej] from comment #1)
> Which JavaScript?

What ever is compiled into the Aurora (20 branch)?
Otherwise I don't understand your question.

Comment 3

[Paul Silaghi, QA [:pauly]]

Have you experienced this again since the first time ?

Comment 4

[Wyatt Miler]

I'm thinking this is related to https://bugzilla.mozilla.org/show_bug.cgi?id=778599
 
The particular point at which it hangs has moved over to js::NewDenseCopiedArray which is within the above mentioned bug.

Comment 5

[Andrew McCreight [:mccr8]]

Yeah, that does look similar.  Do you leave Facebook open for long periods of time?  For me, reloading the FB tab would make the problem go away.

Comment 6

[Jeff Walden [:Waldo]]

As I said in the other bug:

If the concat's spinning on NewDenseCopiedArray a lot, that's because (window[x] || []) has a very large dense initialized length, which means window[x] is likely a very large array.  Smells like a TE bug to me, that whatever's being fed in there isn't being cleared out correctly over time or something.  The value of |x| in that case would probably be informative to a FB engineer.

Comment 7

[Paul Silaghi, QA [:pauly]]

Left Firefox minimized for couple of hours on Facebook - didn't see any issues, the CPU usge was low.
nightly 2013-06-04, mac os x 10.8.3

Comment 8

[Pablo]

set as resolved incomplete as the user is disabled.