1469146 - [meta] Review performance Telemetry

Status: NEW

(Toolkit :: Telemetry, enhancement, P3)

Description

[Georg Fritzsche [:gfritzsche]]

From the historic Telemetry roots, we still have a fair bit of code & main ping data that we're not sure is used and who owns it.

Specific examples include:
- payload.lateWrites
- payload.fileIOReports
- payload.chromeHangs
- payload.threadHangstats
...

See the main ping review doc for details:
https://docs.google.com/spreadsheets/d/1y5gbtHibpEcZMObKDt1AXSXM4wLtw4vwXkN10OKV7H0/

And the documentation:
https://firefox-source-docs.mozilla.org/toolkit/components/telemetry/telemetry/data/main-ping.html


We should figure out:
- which parts can simply be removed
- for the remainders, who owns them and where to move the code so ownership is clear

Comment 1

[Georg Fritzsche [:gfritzsche]]

The set of data might touch the teams of: mconley, vchin, past.

Comment 2

[Georg Fritzsche [:gfritzsche]]

Code-wise i'm looking at:
- CombinedStacks.h/.cpp
- HangReports.h/.cpp
- ProcessedStack.h/.cpp
- TelemetryIOInterposeObserver.h/.cpp

They're all in here:
https://dxr.mozilla.org/mozilla-central/source/toolkit/components/telemetry

Also, specific locations in Telemetry core code:
- late writes: https://dxr.mozilla.org/mozilla-central/search?q=file%3ATelemetry.cpp+latewrite&redirect=false
- shutdown time tracking: https://dxr.mozilla.org/mozilla-central/search?q=file%3ATelemetry.cpp+shutdown&redirect=false
- failed profile lock counts: https://dxr.mozilla.org/mozilla-central/search?q=file%3ATelemetry.cpp+failedprofilelock&redirect=false
- chromehangs: https://dxr.mozilla.org/mozilla-central/search?q=file%3ATelemetry.cpp+chromehang&redirect=false

Comment 3

[Georg Fritzsche [:gfritzsche]]

There also quite a few timestamps in payload.simpleMeasurements that we should check through:
https://docs.google.com/spreadsheets/d/1y5gbtHibpEcZMObKDt1AXSXM4wLtw4vwXkN10OKV7H0/

Comment 4

[Georg Fritzsche [:gfritzsche]]

ni?me to reach out with some specific actionable questions.

Comment 5

[Georg Fritzsche [:gfritzsche]]

Redirecting this to the current owner.

Comment 6

[Chris H-C :chutten]

I'll take this meta for now as a reminder to evaluate where to fit this in the 2020 plan.