1603276 - `toLocaleTimeString` allocate massive amounts of memory

Status: RESOLVED FIXED

(DevTools :: Netmonitor, defect, P3)

Description

[:Harald Kirschner :digitarald]

Attachment: image.png

Using http://tankanarchy.herokuapp.com/ generating many WS logs leads to massive jank.

Recording with native memory allocation: https://perfht.ml/36mIbSc

In a single hang js::intl_FormatDateTime and toLocaleTimeString allocate about 30 Mb native memory.

Offending line: https://searchfox.org/mozilla-central/source/devtools/client/netmonitor/src/components/websockets/FrameListColumnTime.js#35

Solution is to re-use the same formatter instance: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat/format

Comment 1

[:Harald Kirschner :digitarald]

Attachment: Bug 1603276 - Use cached instance of DateTimeFormat for WS frames r=honza

Comment 2

[:Harald Kirschner :digitarald]

Before/after: https://perfht.ml/34bzvwJ

300ms per new message down to 90ms.

Tested on https://firefox-devtools-debug-ws.glitch.me/ with 500+ messages

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/9019f3ce9559
Use cached instance of DateTimeFormat for WS frames r=Honza

Comment 4

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/9019f3ce9559