1526328 - Disable all Telemetry Recording in FUZZING builds

Status: RESOLVED FIXED

(Toolkit :: Telemetry, enhancement, P1)

Description

[Christian Holler (:decoder)]

Similar to bug 1207696, we have reasons to disable Telemetry in fuzzing builds. In particular, this code is even active when running single gtest-like targets with libFuzzer and causes a lot of intermittent coverage noise when running (any code running in a non-deterministic fashion in the background hurts coverage-guided fuzzing).

I will make a patch to disable any Telemetry recording in FUZZING_INTERFACE builds for now. We do have our own build-time switches for fuzzing, so this won't affect normal builds at all.

Alternatively, we could also disable it for all FUZZING builds, but that would mean that we don't test/exercise this code anymore in full browser fuzzing. The advantage would be less non-deterministic action going on in the background, the disadvantage would be missing potential bugs in the Telemetry code.

Jesse, what do you think?

Comment 1

[Christian Holler (:decoder)]

I just realized that FUZZING_INTERFACES will also be defined in fuzzing builds for full-browser fuzzing, so we can't use that to disable Telemetry just for command line fuzzing.

Essentially we have two options:

1. Disable the Telemetry code at build-time for all fuzzing

or

2. Use a runtime check (e.g. getenv("FUZZER") != null) to detect that we are in a command line fuzzing setup that uses the fuzzing interface.

Comment 2

[Jesse Schwartzentruber (:truber)]

To be clear, we're talking about telemetry collection only, since we disable non-local network access while browser fuzzing.

I'd rather see it disabled for browser too. Any bugs we find in telemetry while fuzzing will likely be coincidental, and could just as easily be found while running the test suite.

Comment 3

[Christian Holler (:decoder)]

Attachment: Bug 1526328 - Disable Telemetry recording in FUZZING builds. r?janerik

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/442a1725c992
Disable Telemetry recording in FUZZING builds. r=janerik

Comment 5

[Narcis Beleuzu [:NarcisB]]

Backed out for build bustages on Telemetry.cpp

Backout link: https://hg.mozilla.org/integration/autoland/rev/68e3ee13edd9b8c8fa36c3a77491950f485cbadf
Push link: https://hg.mozilla.org/integration/autoland/rev/442a1725c992f43393f4b0dcee1d6fbacf0963c1
Log link: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=227630467&repo=autoland&lineNumber=23863

Comment 6

[Christian Holler (:decoder)]

Fuzzing builds are happy now with the revised patch:

https://treeherder.mozilla.org/#/jobs?repo=try&revision=cf7247ccd9af6545d93c3bba1cdc07691221adb7

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4441e86d56b9
Disable Telemetry recording in FUZZING builds. r=janerik

Comment 8

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/4441e86d56b9