1488462 - Big slowdown happening every x minutes

Status: RESOLVED FIXED

(Firefox :: New Tab Page, defect, P1)

Description

[Julien Wajsberg [:julienw]]

Since recently I found that I got a big slowdown every some minutes.

I took this profile:

https://perfht.ml/2LWxzyX
(sorry, it's a bit big to load, but I zoomed in the interesting part and toggled the "inverted tree" setting)

This points to the direction of ActivityStream that maybe calls toHash a bit too much.

Florian pointed me to this code [1]. Maybe this code could be converted to a for loop where the the filtering operation could happen just the right amount of time to get numItems items, and break early.

[1] https://searchfox.org/mozilla-central/rev/c3fef66a5b211ea8038c1c132706d02db408093a/toolkit/modules/NewTabUtils.jsm#826-838

Comment 1

[Julien Wajsberg [:julienw]]

Discussing with Florian more, I realized that today I did a lot of screenshots through the devtools to review a patch, and because screenshots are data URL (so, big URLs), that's likely the reason. So maybe data-url should be handled differently too.

Comment 2

[Florian Quèze [:florian]]

70% of the time here https://perfht.ml/2PBSnOn is spent in the hashing function called by BlockedLinks_isBlocked https://searchfox.org/mozilla-central/rev/c3fef66a5b211ea8038c1c132706d02db408093a/toolkit/modules/NewTabUtils.jsm#504

BlockedLinks_isBlocked should probably return early for data: urls.

Is it expected that _processHighlights is called 15 times here? It seems to be in reaction to a 'messsage' DOM event, do we know what message this is?

Comment 3

[Pascal Chevrel:pascalc]

Ed, this is marked as a P1 bug affecting the 63 release, do you have a status update on this one? Will you request an uplift to beta? Thanks

Comment 4

[Ed Lee :Mardak]

This was regressed by bug 1433230 when downloads were added to highlights

Comment 5

[GitHub Bugzilla PR Linker]

Attachment: Link to GitHub pull-request: https://github.com/mozilla/activity-stream/pull/4459

Comment 6

[[github robot]]

Commit pushed to master at https://github.com/mozilla/activity-stream

https://github.com/mozilla/activity-stream/commit/eb19a91c737463777b6ebcb9a0f1481b20c8335f
Fix Bug 1488462 - Big slowdown happening every x minutes (#4459)

Directly pick the first download result and add a type without calling processHighlights, which checks blocked links.

Comment 7

[Ed Lee :Mardak]

https://hg.mozilla.org/mozilla-central/rev/60fed71d173f

Comment 8

[Ed Lee :Mardak]

julienw, do you still have the profile that this was happening with (and was it still causing slowdown) to test with nightly 20181003223518 or newer?

Comment 9

[Pascal Chevrel:pascalc]

Kate, this is a tracked regression for 63, we'll need the fix to be uplifted to Beta, thanks!

Comment 10

[Kate Hudson :k88hudson]

Attachment: Bug 1488462 - Big slowdown happening every x minutes

Comment 11

[Kate Hudson :k88hudson]

Comment on attachment 9014851 [details]
Bug 1488462 - Big slowdown happening every x minutes

[Beta/Release Uplift Approval Request]

Feature/Bug causing the regression: Bug 1488462

User impact if declined: Significant performance regression for users

Is this code covered by automated tests?: Yes

Has the fix been verified in Nightly?: Yes

Needs manual test from QE?: No

If yes, steps to reproduce: 

List of other uplifts needed: None

Risk to taking this patch: Low

Why is the change risky/not risky? (and alternatives if risky): Small code change

String changes made/needed: no

Comment 12

[GitHub Bugzilla PR Linker]

Attachment: Link to GitHub pull-request: https://github.com/mozilla/activity-stream/pull/4471

Comment 13

[Pascal Chevrel:pascalc]

Comment on attachment 9014851 [details]
Bug 1488462 - Big slowdown happening every x minutes

Trivial patch fixing a major performance hit in Firefox 63, uplift approved for 63 beta 13, thanks.

Comment 14

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/78a37fe71fc5

Comment 15

[Ed Lee :Mardak]

This was uplifted

Comment 16

[Julien Wajsberg [:julienw]]

(In reply to Ed Lee :Mardak (PTO Sep 15 - Oct 7) from comment #8)
> julienw, do you still have the profile that this was happening with (and was
> it still causing slowdown) to test with nightly 20181003223518 or newer?

yes, that's my main profile. I just opened some data-URLs and I'll report if I see anything suspicious.