1149379 - Force GC/CC button

Status: REOPENED

(DevTools :: Memory, enhancement, P3)

Comment 1

[Nick Fitzgerald [:fitzgen] [⏰PST; UTC-8]]

Not sure this is actually useful? Our APIs only deal with retained memory in the heap graph, not allocated-but-no-longer-retained memory. As such, you should see the exact same heap graph after every GC. The exception to prove the rule is generated JIT code, some of which is thrown away on certain GCs.

Comment 2

[Nick Fitzgerald [:fitzgen] [⏰PST; UTC-8]]

See comment 1.

Comment 3

[Nick Fitzgerald [:fitzgen] [⏰PST; UTC-8]]

Talked to some folks, and this could be useful in certain circumstances.

Comment 4

[Julien Wajsberg [:julienw]]

From ochameau, various implementations of memory collection:

GC in DAMP (Devtools' Talos performance regression tests), based on about:memory:
[1] https://searchfox.org/mozilla-central/source/testing/talos/talos/tests/devtools/addon/content/damp.js#77-91

Another GC in tests, slightly different, with an interesting comment:
[2] https://searchfox.org/mozilla-central/source/testing/specialpowers/content/specialpowersAPI.js#1580-1600

GC in mochitests, used before leak check:
[3] https://searchfox.org/mozilla-central/source/testing/mochitest/browser-test.js#952-961

GC used in devtools' memory-aware mochitests:
[4] https://searchfox.org/mozilla-central/source/devtools/client/framework/test/allocations/browser_allocations_target.js#22-32

The DAMP code has been reused here:
[5] https://searchfox.org/mozilla-central/source/toolkit/components/extensions/test/xpcshell/test_ext_contexts_gc.js#31-44

An experiment from ochameau where he ran GC until memory increases, which proved quite stable but also time-consuming:
[6] https://hg.mozilla.org/try/rev/ce1b333bc173e724b06c57bb0e308868690ce447#l1.89

Bug 1407826 has a lot of information, especially bug 1407826 comment 13 compared the different ways to GC.

Comment 5

[Julien Wajsberg [:julienw]]

From ochameau still, he seems to think that a GC/CC is useful before capturing. I'd like to prove that with a manual test before doing any work here.