642053 - Firefox GUI hangs when running V8 javascript test

Status: RESOLVED WONTFIX

(Firefox :: General, defect)

Description

[zz]

User-Agent:       Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0

Attempting to run the V8 test renders Firefox GUI unresponsive until test completes. You are unable to do anything while this test is running. 

It should be quite evident that Firefox needs core optimizations such as multi-threading.

Reproducible: Always

Steps to Reproduce:
1. Go to: http://v8.googlecode.com/svn/data/benchmarks/v6/run.html
2. While test is running notice how GUI is unresponsive
3. While test is running try to switch tabs, scroll, etc
Actual Results:  
While test is running the GUI becomes unresponsive.

Expected Results:  
While test is running I should beable to flawlessly switch tabs, scroll, etc.

Comment 1

[Wayne Mery (:wsmwk)]

Did it run OK in version 3?
Can you reproduce this behavior using FF 5 or6 ?

I see some slight delay, but otherwise runs fine on my i7 machine using FF 5.0a2

Comment 2

[Mike Conley (:mconley) (:⚙️) (PTO Dec 22 - Jan 2)]

I see the same stutters in Google Chrome. I think this is just the consequence of those tests doing heavy operations in Javascript and not using things like web-workers. And of course they're not using web-workers - I think v8bench *wants* to test the execution on the main thread, since that's where most Javascript is executed anyhow.

As Javascript engines get better, this problem will decrease. And as e10s happens, I can see tab-switching becoming easier. But the very nature of these tests means that there'll be some main-thread blocking while we compute things. I don't think there's much we're going to do here.