2022844 - Enable the JS Tracer on nightly

Status: RESOLVED FIXED

(DevTools :: Debugger, task)

Description

[Alexandre Poirot [:ochameau]]

For now, until you enable devtools.debugger.features.javascript-tracing preference, the JS Tracer is completely invisible in DevTools, even in devtools settings panel.

Mozilla contributors (esp engineers working on web compat) are a bit bugged by it being completely hidden.

While I'm not sure the tracer is ready for a wide audience, we may:

• enable it by default, but only on nightly
• at least show the preffed-off open in devtools settings panel and could start doing so only in nightly.

I'm still anxious is enabling it by default on release as it would display the tracer icon in a very visible spot (top right toolbox corner), which may get more visibility than expected. This icon, may be painful if the tool isn't used/well understood.

Comment 1

[Alexandre Poirot [:ochameau]]

Attachment: Bug 2022844 - [devtools] Expose tracer settings in Nightly by default. r=#devtools

"devtools.debugger.features.javascript-tracing" is still relevant on
other channels and fully enable the tracer (toolbox button and
keyshortcuts automatically enabled).

Otherwise the tracer is rather controlled by
"devtools.command-button-jstracer.enabled" preference, which typically
requires user's action to enable to button from the settings panel.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/3e57e5e7bb19
https://hg.mozilla.org/integration/autoland/rev/29569796e43d
[devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/6e644cc715d3
https://hg.mozilla.org/integration/autoland/rev/3041bb6177e1
Revert "Bug 2022844 - [devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe" for causing talos damp failures.

Comment 4

[Cosmin Sabou [:CosminS]]

Backed out for causing talos damp failures.

Push with failures

Failure log

Backout link

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/75c3971083e6
https://hg.mozilla.org/integration/autoland/rev/017c4721b1e7
[devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/fa7e4e4a199f
https://hg.mozilla.org/integration/autoland/rev/245814fe2cbf
Revert "Bug 2022844 - [devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky" for causing failures at browser_toolbox_options_disable_buttons.js.

Comment 7

[Atila Butkovits]

Backed out for causing failures at browser_toolbox_options_disable_buttons.js.

Backout link: https://hg.mozilla.org/integration/autoland/rev/245814fe2cbf

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&selectedTaskRun=Vn4vYln9SCaBX0f7woisfA.0&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=017c4721b1e75b99157d50e8038032528a66fcf8

Failure log: https://treeherder.mozilla.org/logviewer?job_id=557629815&repo=autoland&task=Vn4vYln9SCaBX0f7woisfA.0&lineNumber=10375

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/8630553a1835
https://hg.mozilla.org/integration/autoland/rev/e77a7659bacf
[devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/08184c935209
https://hg.mozilla.org/integration/autoland/rev/78e6400f2304
Revert "Bug 2022844 - [devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky" for causing dt failures @ browser_toolbox_toolbar_overflow_button_visibility

Comment 10

[amarc]

Backed out for causing dt failures

• Backout link
• Push with failures
• Failure Log

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9886e3b9364d
https://hg.mozilla.org/integration/autoland/rev/7058226581c5
[devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky

Comment 12

[Serban Stanca [:SerbanS]]

https://hg.mozilla.org/mozilla-central/rev/7058226581c5

Comment 13

[BMO Github Automation]

Authored by https://github.com/ochameau
https://github.com/mozilla/enterprise-firefox/commit/9886e3b9364d86811f53e3060d8144d3a38ecc7f
[enterprise-main] Bug 2022844 - [devtools] Expose tracer settings in Nightly by default. r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky

Comment 14

[Donal Meehan [:dmeehan]]

Could you consider nominating this for a release note? (Process info)
We could include it in the nightly only release notes.

Comment 15

[Alex Finder]

(In reply to Pulsebot from comment #11)

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9886e3b9364d
https://hg.mozilla.org/integration/autoland/rev/7058226581c5
[devtools] Expose tracer settings in Nightly by default.
r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky

Perfherder has detected a devtools performance change from push 7058226581c535f50cae954f07c25263096c79d1.

No action is required from the author; this comment is provided for informational purposes only.

Improvement	Test	Platform	Options	Absolute values [old vs new]
100%	reload-inspector:parent-process objects-with-stacks	linux2404-64		50.31 -> 0.00
100%	reload-inspector:parent-process objects-with-stacks	linux2404-64-shippable		46.08 -> 0.00

Need Help or Information?

If you have any questions, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

Comment 16

[Julian Descottes [:jdescottes]]

(In reply to Alex Finder|PTO, back on April 14th from comment #15)

(In reply to Pulsebot from comment #11)

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9886e3b9364d
https://hg.mozilla.org/integration/autoland/rev/7058226581c5
[devtools] Expose tracer settings in Nightly by default.
r=devtools-reviewers,nchevobbe,perftest-reviewers,sparky

Perfherder has detected a devtools performance change from push 7058226581c535f50cae954f07c25263096c79d1.

No action is required from the author; this comment is provided for informational purposes only.

Improvement	Test	Platform	Options	Absolute values [old vs new]
100%	reload-inspector:parent-process objects-with-stacks	linux2404-64		50.31 -> 0.00
100%	reload-inspector:parent-process objects-with-stacks	linux2404-64-shippable		46.08 -> 0.00

Need Help or Information?

If you have any questions, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

FWIW This improvement should be linked to Bug 2027837, if you zoom in the alert, the pushlog where this improvement was detected is https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=7206f176ea5115687c23ff2f89c0454a04dfd7bb&tochange=a9aa80d13829fbaa21c56747ac840fe3d40d6803

Comment 17

[Alexandre Poirot [:ochameau]]

Release Note Request (optional, but appreciated)
[Why is this notable]:
This is a brand new feature, with many visualizations (debugger, profiler, web console, stdout), that AFAIK doesn't exists in other browsers.
While it has been mostly meant to help firefox contributors to debug web compat issues, it can be an interesting tool for web developers debugging JS codebases.

[Affects Firefox for Android]:
Not really, but you can trace javascript running from android by using about:debugging

[Suggested wording]:
The new JavaScript Tracer for now only available in Firefox Nightly can be enabled from DevTools Settings panel.
It enables tracing all JavaScript function calls. Compared to the performance profiler, this isn't recording sample, but instead trace all function calls.
(if that's relevant explaining how to use it:)
You can start tracing via the new circle button displayed at the top end of the toolbox. (this button's context menu exposes some useful settings)
Various output are available: live in a side panel of the debugger, in the web console, or stdout. Or recorded via the profiler pipeline and UI.

Comment 18

[Donal Meehan [:dmeehan]]

Added to the Fx151 nightly release notes, please allow 30 minutes for the site to update.
The nightly-only note will be removed after three cycles or when it is enabled by default, whichever comes earlier.