1577161 - Gecko Profiler shouldn't include data-urls in profile strings (for perf reasons)

Status: RESOLVED FIXED

(Core :: JavaScript Engine, task, P1)

Description

[Ted Campbell [:tcampbell]]

When profiling Bug 1576999, we spend an enormous amount of time in the profiler itself cloning strings for data-url filenames.

We can either cap filename lengths here or replace all filenames that start with 'data:' with a placeholder.

Comment 1

[Ted Campbell [:tcampbell]]

Attachment: Bug 1577161 - Limit length of filename saved for profiler. r?jandem

When profiling scripts with large numbers of dynamic Functions and
complex URLs the profiler overhead can severely skew results. This puts
a cap on the filename length we send to profiler to reduce the impact of
this when using data urls.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5e767d6cba5a
Limit length of filename saved for profiler. r=jandem

Comment 3

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/5e767d6cba5a

Comment 4

[Alexandru Michis [:malexandru]]

Backed out changeset 5e767d6cba5a (Bug 1577161) for causing Bug 1579038.

Backout link: https://hg.mozilla.org/integration/autoland/rev/dca9b6dd135f3230cb7f5516003df450efcb06bf

Comment 5

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

Backout merged: https://hg.mozilla.org/mozilla-central/rev/dca9b6dd135f

Comment 6

[Ted Campbell [:tcampbell]]

The issue is that char_traits::find(..) requires length to cover valid memory rather than stopping at first match. On Windows, the SIMD implementation will read beyond null-pointer and touch an unmapped page.

Comment 7

[Jan de Mooij [:jandem]]

Maybe you can use js_strchr_limit?

Comment 8

[BugBot [:suhaib / :marco]]

There's a r+ patch which didn't land and no activity in this bug for 2 weeks.
:tcampbell, could you have a look please?
For more information, please visit auto_nag documentation.

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3b9c45b97423
Limit length of filename saved for profiler. r=jandem

Comment 10

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/3b9c45b97423

Comment 11

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/3b9c45b97423