578333 - Composing in gmail eats up CPU when there is network trouble

Status: RESOLVED WORKSFORME

(Core :: General, defect)

Description

[tama]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:2.0b1) Gecko/20100630 Firefox/4.0b1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:2.0b1) Gecko/20100630 Firefox/4.0b1

When composing an email in Gmail and there is trouble with the network connection, firefox takes over 50% of CPU time and feels quite unresponsive.

I'm not sure of the exact conditions for this to reproduce, but I can say that it's happened to me using https Gmail with a clean profile and while I'm having network problems: latency seems high and messaging programs such as skype or Gtalk over jabber often get desconnected.

It could be a Gmail problem, but I believe FF shouldn't feel unresponsive.

Reproducible: Sometimes

Steps to Reproduce:
1. Open and log into https://mail.google.com
2. Reply to any conversation
3. Watch CPU usage rising while you write in the message file. FF gets slow.
Actual Results:  
Characters display in window slower than you type them and CPU usage rises.

Expected Results:  
Firefox should always feel responsive and not eat up CPU.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Hmm.  Do you have a dual-core machine?  That is, is 50% of your CPU just a fully pegged core?

Bobby, is the load blocking stuff we looked at at the summit enabled by default in b1?  Or is this likely to be something else?

Comment 2

[Bobby Holley (:bholley)]

(In reply to comment #1)
> Hmm.  Do you have a dual-core machine?  That is, is 50% of your CPU just a
> fully pegged core?
> 
> Bobby, is the load blocking stuff we looked at at the summit enabled by default
> in b1?  Or is this likely to be something else?

The onload blocking is enabled, but the discarding that triggered it is not. But given that the issue we saw looked like it was broader than discarding, it's possible that it's the same thing.

Joe's got a record-and-replay box set up that he's using right now for another bug. When he's done (hopefully by tomorrow), I'll try to reproduce bug 576615.

Comment 3

[tama]

(In reply to comment #1)
> Hmm.  Do you have a dual-core machine?  That is, is 50% of your CPU just a
> fully pegged core?

Yes, it's a dual core.

Comment 4

[Bobby Holley (:bholley)]

tama - I have reason the believe that this problem might be fixed on recent nightlies. Can you still reproduce it?

Comment 5

[Benjamin Smedberg]

Can you try to reproduce again with a nightly? Now that retained layers have landed, I'm told this might have gone away. Please renominate for blocking2.0 if you can still reproduce the issue.

Comment 6

[tama]

The truth is I don't know how to reproduce this issue.

I'm running now F4b4 and when typing fast in the Gmail reply box, I can get CPU load as high as 50%, but it does feel responsive.

Comment 7

[Bobby Holley (:bholley)]

(In reply to comment #6)
> The truth is I don't know how to reproduce this issue.
> 
> I'm running now F4b4 and when typing fast in the Gmail reply box, I can get CPU
> load as high as 50%, but it does feel responsive.

The issue that I'd know about would be case of the spiking to 50% and then staying there forever, even if you stop interacting with the browser. If that's not happening, then I don't have any particular leads.

Comment 8

[Petruta Horea [:phorea], Desktop Test Engineering]

This issue was initially reported on Win XP which is no longer supported.
Newer OS's and latest Firefox versions do not exhibit this kind of behavior, so I'm closing it as WFM. If that's not the case please reopen and add more details. Thank you!