1684982 - XRE_mainRun holds autorelease objects indefinitely

Status: RESOLVED FIXED

(Core :: Widget: Cocoa, defect)

Description

[Brad Werth [:bradwerth]]

XRE_mainRun makes many calls before invoking appStartup->Run() and entering the event loop. Failing to individually account for these objects leads to memory bloat like we see in Bug 1684903. We could avoid holding this memory if this function creates and drains its own autorelease pool before entering the event loop.

Comment 1

[Brad Werth [:bradwerth]]

Attachment: Bug 1684982 Part 1: Add a MacAutoreleasePool::Drain method.

This method is useful for cases when the pool is filled up within a long-
lasting scope.

Comment 2

[Brad Werth [:bradwerth]]

Attachment: Bug 1684982 Part 2: Make XRE_mainRun create then destroy a macOS autorelease pool before entering the event loop.

The scoped MacAutoreleasePool object will also behave as intended for any
early exits in this function, though none currently exist for macOS code.

Depends on D100733

Comment 3

[Brad Werth [:bradwerth]]

Attachment: Bug 1684982 Part 2: Re-apply clang-format to nsAppRunner.cpp.

Comment 4

[Brad Werth [:bradwerth]]

Attachment: Bug 1684982 Part 1: Add a scope to XRE_mainRun.

This scope will support later functional changes that are conditionally
compiled. This part is standalone to help with blame-tracking.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/877461dd6c4f
Part 1: Add a scope to XRE_mainRun. r=jrmuizel
https://hg.mozilla.org/integration/autoland/rev/7dc6ee63d69a
Part 2: Make XRE_mainRun create then destroy a macOS autorelease pool before entering the event loop. r=jrmuizel

Comment 6

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/877461dd6c4f
https://hg.mozilla.org/mozilla-central/rev/7dc6ee63d69a

Comment 7

[Alexandru Ionescu (needinfo me) [:alexandrui]]

== Change summary for alert #28345 (as of Thu, 07 Jan 2021 09:06:57 GMT) ==

Improvements:

Ratio	Suite	Test	Platform	Options	Absolute values (old vs new)
6%	startup_about_home_paint	startup_about_home_paint	windows10-64-shippable	e10s stylo	687.42 -> 647.58

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=28345