1811188 - JS demo (https://www.fxhash.xyz/generative/23090) appears to spend ~200ms in GC/CC each time you refresh it

Status: NEW

(Core :: Cycle Collector, defect, P3)

Description

[Mayank Bansal]

Go to https://www.fxhash.xyz/generative/23090
Click on the "Run" button
After the demo renders, you can click on the "Variations" button a couple of times

Nightly: https://share.firefox.dev/3XzhLaQ
Chrome: https://share.firefox.dev/3krP9BY

No idea if this is the expected behaviour or if the demo is written poorly, or if this particular scenario is not worth optimizing for.

Comment 1

[Mayank Bansal]

It also looks like that total time spent in GC is fairly high while the demo is rendering/running

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

Seems like the test is using lots and lots ImageData objects and from cycle collector side hold/drop JS objects calls are heavy because of the hashtable usage.
Hashtable operations shows up also on JS side when doing minor GCs.

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

The testcase is pretty artificial, but I think I've seen holdJsObject calls a bit in speedometer.

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

Looks like clicking "Run" triggers creating about 650000 ImageData objects.

Comment 5

[Olli Pettay [:smaug][[e-mail]]]

But speedometer doesn't trigger these code paths too much, removing dependency after all.