1681771 - Perma [tier2] tests/jit-test/jit-test/tests/gc/pretenuring.js | /data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9 Error: Assertion failed: got true, expected false (code 3, args "") [0.5 s]

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect, P5)

Description

[Treeherder Bug Filer]

Filed by: abutkovits [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=324156015&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/Ez8jlak4SESdoXV-xy1n-w/runs/0/artifacts/public/logs/live_backing.log

---

[task 2020-12-10T15:02:24.870Z] 15:02:23     INFO -  TEST-PASS | tests/jit-test/jit-test/tests/gc/oomInWeakMap.js | Success (code 59, args "--baseline-eager") [0.4 s]
[task 2020-12-10T15:02:24.870Z] 15:02:23     INFO -  TEST-PASS | tests/jit-test/jit-test/tests/gc/oomInWeakMap.js | Success (code 59, args "--no-blinterp --no-baseline --no-ion --more-compartments") [0.3 s]
[task 2020-12-10T15:02:24.870Z] 15:02:23     INFO -  TEST-PASS | tests/jit-test/jit-test/tests/gc/oomInWeakMap.js | Success (code 59, args "--blinterp-eager") [0.4 s]
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  /data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9 Error: Assertion failed: got true, expected false
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  Stack:
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -    @/data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9/data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9 Error: Assertion failed: got true, expected false
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  Stack:
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -    @/data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9Exit code: 3
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  FAIL - gc/pretenuring.js
[task 2020-12-10T15:02:24.870Z] 15:02:24  WARNING -  TEST-UNEXPECTED-FAIL | tests/jit-test/jit-test/tests/gc/pretenuring.js | /data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9 Error: Assertion failed: got true, expected false (code 3, args "") [0.5 s]
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  INFO exit-status     : 3
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  INFO timed-out       : False
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  INFO stdout          > /data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9 Error: Assertion failed: got true, expected false
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  INFO stdout          > Stack:
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  INFO stdout          > @/data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9
[task 2020-12-10T15:02:24.870Z] 15:02:24     INFO -  INFO stderr         2> /data/local/tmp/test_root/tests/tests/tests/gc/pretenuring.js:32:9 Error: Assertion failed: got true, expected false```

Comment 1

[Cosmin Sabou [:CosminS]]

Jon please have a look over this tier2 permafailure from https://hg.mozilla.org/mozilla-central/rev/4d7255296684f147ec51578703f725fc242a24a6
Thank you.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1681693

Comment 3

[Intermittent Failures Robot]

17 failures in 705 pushes (0.024 failures/push) were associated with this bug yesterday.

Repository breakdown:

• autoland: 11
• mozilla-central: 6

Platform breakdown:

• android-hw-p2-8-0-android-aarch64: 13
• android-hw-p2-8-0-android-aarch64-shippable: 3
• linux64: 1

For more details, see:
https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1681771&startday=2020-12-11&endday=2020-12-11&tree=all

Comment 4

[Intermittent Failures Robot]

37 failures in 4060 pushes (0.009 failures/push) were associated with this bug in the last 7 days.

This is the #25 most frequent failure this week.

** This failure happened more than 30 times this week! Resolving this bug is a high priority. **

** Try to resolve this bug as soon as possible. If unresolved for 2 weeks, the affected test(s) may be disabled. **

Repository breakdown:

• autoland: 27
• mozilla-central: 10

Platform breakdown:

• android-hw-p2-8-0-android-aarch64: 31
• android-hw-p2-8-0-android-aarch64-shippable: 5
• linux64: 1

For more details, see:
https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1681771&startday=2020-12-07&endday=2020-12-13&tree=all

Comment 5

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

The test fails on Android because of :

1. the validForTenuring is false.
   https://searchfox.org/mozilla-central/rev/97dd1934d16cada69dbf68e9cda9e9a017459e9e/js/src/gc/Nursery.cpp#756

The value from used/capacity is roughly 0.87

2. nursery.usedBytes is smaller than 4MB
   https://searchfox.org/mozilla-central/rev/97dd1934d16cada69dbf68e9cda9e9a017459e9e/js/src/gc/Nursery.cpp#1196

The 4MB value is from https://bugzilla.mozilla.org/show_bug.cgi?id=1497873#c10
But on Android the max nursery bytes is at most 4MB as well
https://searchfox.org/mozilla-central/rev/97dd1934d16cada69dbf68e9cda9e9a017459e9e/modules/libpref/init/all.js#1148

Comment 6

[Intermittent Failures Robot]

34 failures in 724 pushes (0.047 failures/push) were associated with this bug yesterday.

Repository breakdown:

• autoland: 27
• mozilla-central: 6
• try: 1

Platform breakdown:

• android-hw-p2-8-0-android-aarch64: 21
• android-hw-p2-8-0-android-aarch64-shippable: 2
• linux64: 8
• windows2012-64: 3

For more details, see:
https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1681771&startday=2020-12-15&endday=2020-12-15&tree=all

Comment 7

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Attachment: Bug 1681771 - Part 1: Lower validForTenuring to 0.87.

Comment 8

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Attachment: Bug 1681771 - Update nursery used bytes threshold to 3MB.

Comment 9

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

talos:
https://treeherder.mozilla.org/perfherder/compare?originalProject=mozilla-central&originalRevision=91a89ecd1d3a9f83a61549a1aaaf469b4746f301&newProject=try&newRevision=ac47e1b3ad53137a724c60bf0cba193ddf162a16&framework=1

Comment 10

[Intermittent Failures Robot]

17 failures in 719 pushes (0.024 failures/push) were associated with this bug yesterday.

Repository breakdown:

• autoland: 11
• mozilla-central: 4
• try: 1
• mozilla-beta: 1

Platform breakdown:

• android-hw-p2-8-0-android-aarch64: 12
• android-hw-p2-8-0-android-aarch64-shippable: 3
• linux64: 1
• windows2012-64: 1

For more details, see:
https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1681771&startday=2020-12-16&endday=2020-12-16&tree=all

Comment 11

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

It turns out changing the validForPretenuring is unnecessary.

The last minor GC is triggered by the test itself, and the nursery is not full yet (explained below), so validForPretenuring doesn't become true.
But it should have disabled nursery strings earlier, it failed to do so because of the 4MB limit of nursery used bytes.
https://searchfox.org/mozilla-central/rev/c7cf087b6e1384608ca3989f042f12f7cabd0a5f/js/src/gc/Nursery.cpp#1196

And the reason why the nursery isn't full, is the tests has 500,000 strings.
The nursery starts with 0x40000 capacity, which holds 7836 strings
then increase the capacity to 0x80000, which holds 16382 strings.
then 0x100000 capacity, -> 32764 strings
0x20000 capacity, 65528 strings
0x40000 capacity, 131056 strings
0x40000 capacity (already hits the max nursery size), 131056 strings.
7836 + 16382 + 32764 + 65528 + 131056 + 131056 = 384622.

The next round of minor Gc will hold (500000 - 384622) around 115000 strings, each string takes 32 bytes => 3680000 bytes, (0x382700 bytes) which are around 87% of the nursery capacity(0x400000).

But if we change the 4MB limit to 3MB(https://phabricator.services.mozilla.com/D99868), the string pretenuring could happen in the 5th round of minor GC.

Talos link: (doesn't include the -qr platforms as it takes longer to run)
https://treeherder.mozilla.org/perfherder/compare?originalProject=mozilla-central&originalRevision=91a89ecd1d3a9f83a61549a1aaaf469b4746f301&newProject=try&newRevision=7dd176e18f17da133e55a13d4a1c7665d0755f64+&framework=1

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/39dae0dc3fd4
Update nursery used bytes threshold to 3MB. r=jonco

Comment 13

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/39dae0dc3fd4

Comment 14

[Ryan VanderMeulen [:RyanVM]]

Please nominate this for beta approval when you get a chance.

Comment 15

[Intermittent Failures Robot]

69 failures in 3421 pushes (0.02 failures/push) were associated with this bug in the last 7 days.

This is the #9 most frequent failure this week.

** This failure happened more than 30 times this week! Resolving this bug is a high priority. **

** Try to resolve this bug as soon as possible. If unresolved for 2 weeks, the affected test(s) may be disabled. **

Repository breakdown:

• autoland: 52
• mozilla-beta: 2
• mozilla-central: 12
• try: 3

Platform breakdown:

• android-hw-p2-8-0-android-aarch64: 47
• android-hw-p2-8-0-android-aarch64-shippable: 8
• linux64: 9
• windows2012-64: 5

For more details, see:
https://treeherder.mozilla.org/intermittent-failures/bugdetails?bug=1681771&startday=2020-12-14&endday=2020-12-20&tree=all

Comment 16

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

will try to nominate to beta once got some ideas about bug 1683454. (keeping the ni)

Comment 17

[Yoshi Cheng-Hao Huang [:allstars.chh][:allstarschh][:yoshi]]

Comment on attachment 9193430 [details]
Bug 1681771 - Update nursery used bytes threshold to 3MB.

Beta/Release Uplift Approval Request

• User impact if declined: No, this patch shouldn't have any impact on users. However this is related to performance or benchmark results.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This is not risky because it is just lowering the threshold for string pretenuring to help the pretenuring result on Android.
• String changes made/needed:

Comment 19

[Julien Cristau [:jcristau]]

Comment on attachment 9193430 [details]
Bug 1681771 - Update nursery used bytes threshold to 3MB.

approved for 85.0b5

Comment 20

[Julien Cristau [:jcristau]]

https://hg.mozilla.org/releases/mozilla-beta/rev/2cb1f32c4145