Bug 113158 – timeline panel goes crazy when there are too many records

• Component: Web Inspector (Deprecated)
• Status: RESOLVED INVALID

[Ojan Vafai]

This happens reliably for me.

1. Open the inspector to the timeline panel and start recording
2. Go to http://www.whatwg.org/specs/web-apps/current-work/
3. Stop recording when the page is done loading

You can't view most of the records and clicking on any of the records you can view doesn't work. The scrollheight of the records view does seem to grow to the right size and you can scroll, but new content doesn't show up.

Tested on:
Google Chrome	25.0.1364.172 (Official Build 187217) 
OS	Mac OS X 
WebKit	537.22 (@145275)

[Levi Weintraub]

Here's what I see: After a couple seconds, the scroll thumb disappears. Hit testing continues to work but I can't scroll, including with a mouse wheel. Then adjusting the time frame at the top triggers everything to start working again, including selecting the entire time frame.

[Ojan Vafai]

Adjusting the timeframe at the top do anything for me when I'm in this broken case.

[Andrey Kosyakov]

We do limit the timeline window by default -- this is done primarily to avoid updating main window and hence reduce resource contention to the inspected page (it can be pretty bad occasionally -- in particular, on chromium mac this causes animation frame rate to degrade from 60fps to 30fps if DevTools are docked to the inspected window, as browser window updates are apparently v-synced).

So the behavior that you describe sounds as "by design" to me. We could probably improve the usability slightly by making the window more explicit. Are you using Events or Frame mode? Historically, selected window is visualized a bit subtle in Events mode, so I guess this may be the source of confusion.

[Levi Weintraub]

(In reply to comment #3)
> So the behavior that you describe sounds as "by design" to me. We could probably improve the usability slightly by making the window more explicit. Are you using Events or Frame mode? Historically, selected window is visualized a bit subtle in Events mode, so I guess this may be the source of confusion.

The behavior with the scrollbar definitely shouldn't be "by design." The scroll thumb disappears and only comes back when I adjust the Timeline. That doesn't make sense, and it sounds like it's even more broken for Ojan (on Linux I presume? I'm using Mac). For the record, I'm not sure if this is an inspector bug or a WebKit bug.

[Andrey Kosyakov]

(In reply to comment #4)

> The behavior with the scrollbar definitely shouldn't be "by design." The scroll thumb disappears and only comes back when I adjust the Timeline. That doesn't make sense, and it sounds like it's even more broken for Ojan (on Linux I presume? I'm using Mac). For the record, I'm not sure if this is an inspector bug or a WebKit bug.

I think we would be better discussing this with a screenshot at hands. The scroll thumb is not there because we calculate the auto window size so that records fit lower pain without scrolling.

[Levi Weintraub]

(In reply to comment #5)
> I think we would be better discussing this with a screenshot at hands. The scroll thumb is not there because we calculate the auto window size so that records fit lower pain without scrolling.

Alright, but then shouldn't the thumb appear again once I stop recording? What we have is a state where you can't get to the contents of your recording if they're out of the viewport.

[Ojan Vafai]

Turns out my repro steps were wrong. 

1. Open the inspector to the timeline panel
2. Go to http://www.whatwg.org/specs/web-apps/current-work/
3. Start recording
4. Reload the page
3. Stop recording when the page is done loading

I'll add an attachment. It shows that there's right panel is missing a bunch of data. Also, clicking on the couple dropdowns that are visible doesn't do anything.

[Ojan Vafai]

Created attachment 195113 [details]
screenshot