1896896 - Child processes on Android have pointless telemetry timers and IPCs

Status: RESOLVED FIXED

(Toolkit :: Telemetry, defect, P1)

Description

[Florian Quèze [:florian]]

While profiling Fenix, I noticed
TelemetryIPCAccumulator::IPCTimerFired 2s timers and PContent::Msg_AccumulateChildHistograms, PContent::Msg_AccumulateChildKeyedHistograms and PContent::Msg_RecordDiscardedData IPCs sent to the parent process.

Chutten confirmed in #glean that these are not wanted anymore on Android.

Comment 1

[Florian Quèze [:florian]]

Profile showing these IPCs happening 13 times in 30s, including 9 times when Fenix was not even on screen: https://share.firefox.dev/3WFxoA4

Comment 2

[Chris H-C :chutten|PTO (back March 23)]

Telemetry IPC batches and transports instrumentation actions on histograms, keyed histograms, scalars, keyed scalars, and events.

Since bug 1877576, none of those actions result in any data collection on Android.

We can definitely no-op the Accumulator and 0-size its storage... but we may be able to do even more by, say, no-op-ing for Android the surface Legacy Telemetry APIs that call into the IPC accumulator.

This bug will be about:

• Doing a quick scan to see how far "up" we can stop processing android Legacy Telemetry actions
• Excluding from compile any implementation we can
• Turning off Legacy Telemetry tests in Android that depend on those APIs

Comment 3

[Chris H-C :chutten|PTO (back March 23)]

Attachment: Bug 1896896 - Stop compiling the Telemetry IPC impl for Android or iOS r?janerik!,florian!

Comment 4

[Chris H-C :chutten|PTO (back March 23)]

Stuck to the minimal implementation this time around due to time pressures, but if and when needed we could stub all implementations of all exported telemetry headers on builds heading for mobile platforms.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b2af60ce4a6e
Stop compiling the Telemetry IPC impl for Android or iOS r=janerik,florian

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/b2af60ce4a6e