1872982 - A demo spends ~2minutes completely around GC (GCMinor?)

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task)

Description

[Mayank Bansal]

Go to https://davidsaltacc.github.io/pages/generative-art/fractals-v1
QUICKLY slide the first slider "size" all the way to the right

AR: https://share.firefox.dev/48K1p4J (1m40s spend completely around GC)
ER: maybe something to improve here?

Edit: Profile from Chrome is https://share.firefox.dev/4aN3G0w

Comment 1

[André Bargull [:anba]]

From reading the profile, it seems that the code is creating many TypedArrays using TypedArray.prototype.subarray. TypedArray.prototype.subarray creates a new TypedArray, but shares the ArrayBuffer with the source TypedArray. This leads to registering the ArrayBuffer in InnerViewTable. And the profile seems to spend most of the time cleaning up these InnerViewTable entries.

Comment 2

[Jon Coppeard (:jonco)]

This page creates millions of long lived views for a single ArrayBuffer. Currently these are all swept on minor GC to clean up nursery allocated ones, but this ends up being very inefficient when most of them are not in the nursery.

Comment 3

[Jon Coppeard (:jonco)]

Attachment: Bug 1872982 - Part 1: Use more sepecific types in InnerViewTable r?jandem

To make it clearer what's going on this replaces JSObject with
ArrayBufferObject and ArrayBufferViewObject where possible and does some other
tidy ups.

Comment 4

[Jon Coppeard (:jonco)]

Attachment: Bug 1872982 - Part 2: Partition inner view vector based on whether the view is in the nursery r?jandem

This patch changes the inner view vector to store all nursery views at the end,
and records the index of the first nursery view. This allows us to sweep only
the nursery views after minor GC.

For the page in question this reduces the proportion of time spent in GC from
100% to around 35%.

Depends on D197775

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ab95bea5cab2
Part 1: Use more sepecific types in InnerViewTable r=jandem
https://hg.mozilla.org/integration/autoland/rev/009227ccd93a
Part 2: Partition inner view vector based on whether the view is in the nursery r=jandem

Comment 6

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/ab95bea5cab2
https://hg.mozilla.org/mozilla-central/rev/009227ccd93a

Comment 7

[Mayank Bansal]

This now takes 3.5 seconds, which is a pretty drastic improvement!
https://share.firefox.dev/3vs9gFG