837136 - Very noticeable content slowdowns when debugger is open in some circumstances

Status: RESOLVED WORKSFORME

(DevTools :: Debugger, defect, P2)

Description

[Victor Porof [:vporof][:vp]]

STR:

1. Go to http://mrdoob.github.com/three.js/examples/webgl_lensflares.html
I'm getting high framerates, ~60fps.

2. Open debugger
Major slowdowns: 4fps! Nothing unusual in stdout or the error console, and no apparent protocol pipe load. However, if I open up the WebConsole:

DBG-SERVER: Got: {
  "from": "conn3.console10",
  "type": "pageError",
  "pageError": {
    "message": "[JavaScript Warning: \"Error in parsing value for 'height'.  Declaration dropped.\" {file: \"http://mrdoob.github.com/three.js/examples/webgl_lensflares.html\" line: 0 column: 0 source: \"-24.449999999999996px\"}]",
    "errorMessage": "Error in parsing value for 'height'.  Declaration dropped.",
    "sourceName": "http://mrdoob.github.com/three.js/examples/webgl_lensflares.html",
    "lineText": "-24.449999999999996px",
    "lineNumber": 0,
    "columnNumber": 0,
    "category": "CSS Parser",
    "timeStamp": 1359733761695,
    "warning": true,
    "error": false,
    "exception": false,
    "strict": false
  }
}

The WebConsole alone doesn't seem to affect the actual content responsiveness, but such pageErrors are spewed to stdout several times a second.

IIRC, this wasn't the case a few weeks ago when I recorded this demo: https://dl.dropbox.com/u/2388316/dbg-jump-to-definition.webm

Comment 1

[Victor Porof [:vporof][:vp]]

(In reply to Victor Porof [:vp] from comment #0)
> IIRC, this wasn't the case a few weeks ago when I recorded this demo:
> https://dl.dropbox.com/u/2388316/dbg-jump-to-definition.webm

Yup, doesn't happen in Aurora.

Comment 2

[Rob Campbell [:rc] (:robcee)]

(In reply to Victor Porof [:vp] from comment #1)
> (In reply to Victor Porof [:vp] from comment #0)
> > IIRC, this wasn't the case a few weeks ago when I recorded this demo:
> > https://dl.dropbox.com/u/2388316/dbg-jump-to-definition.webm
> 
> Yup, doesn't happen in Aurora.

Which version of Aurora was this? (3 months ago).

We need some regression hunting to figure out when this slow-down occurred. Some suspicions include the LongStringActor inclusion.

Comment 3

[Maria Grazia Alastra [:mga]]

So, I've made a lot of tests and:

- I can still see the issue. I'm on Windows 7, 64 bits, and currently I can reproduce the bug on Firefox 20.0.1, on Aurora 22.0 and on Nightly 23.0.

- On 1st February the Aurora version was 20.0, while the Firefox release was 18.0.2.

- I am able to reproduce this bug (web console error and slowdown when I open the debugger) from the current release to the 18.0, Aurora included. Before that, the demo wasn't viewable, probably due to lack of webgl support at that time.

However the parsing height error is not related to this bug, since it's related, instead, to the CSS on that page. If I select any other example from the three.js site I get the exact same error. 
In fact, this seems not to be something new, since there are a lot of bugs about it, here (I'm including a few bug examples in the section "see also").

Now, talking about the slowdowns, I never get to the 4fps point. Yes, I can see a slowdown, but from 40 or 50fps (I get also 60 but that's rare), when the debugger is open I get minimum 16fps, more often 20fps or even 25. I get this 20/30fps slowdown also with other three.js examples, such as: 
- http://threejs.org/examples/webgl_custom_attributes.html
- http://threejs.org/examples/webgl_geometry_hierarchy2.html

But not with:
- http://threejs.org/examples/webgl_geometry_colors.html
- http://threejs.org/examples/webgl_geometry_colors_blender.html

I'm not able to find a regression window, since on my computer any Firefox version on which I can view that animation gives the same results.

My guess is that some animations, which are heavier, are also easier to slow down, and because of that the debugger gets a bit in the way with the framerate. Just a guess!

I hope my results can help you someway :)

(I'm not removing the "qawanted" and "regressionwindow-wanted" keywords, just in case you need more tests.)

Comment 4

[Maria Grazia Alastra [:mga]]

Oh, and by the way I couldn't test with the other demo specified by Victor Porof (https://dl.dropbox.com/u/2388316/dbg-jump-to-definition.webm), because right now it's unavailable (404 error).

While I'm here, my user agent with Firefox 20.0.1, just in case: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:20.0) Gecko/20100101 Firefox/20.0.

User agent for Aurora 18.0 from 1st November 2012 (the first Aurora version I tested in which the animation is viewable): Mozilla/5.0 (Windows NT 6.1; WOW64; rv:18.0) Gecko/18.0 Firefox/18.0, Build ID: 20121101042011.

Comment 5

[Victor Porof [:vporof][:vp]]

This doesn't seem to be happening anymore in Nightly, so I'm closing this for now. But let's keep an eye on it, we don't want any sudden performance regressions.