Excessive allocations in Firebase Trace.incrementMetric

[stari4ek]

[READ] Step 1: Are you in the right place?

yep

[REQUIRED] Step 2: Describe your environment

• Android Studio version: AS 4.1 RC1
• Firebase Component: Performance
• Component version: 19.0.8

[REQUIRED] Step 3: Describe the problem

Steps to reproduce:

1. Build app with firebase_performance_logcat_enabled = false
2. Create + start Firebase Trace in the app
3. Use Trace.incrementMetric() 1k+ times
4. Observe lots of allocations made by logging inside Trace.incrementMetric even when logging is disabled

Relevant Code:

Current implementation of successive path in Trace.incrementMetric:

this.zzai.zzm(String.format(Locale.ENGLISH, "Incrementing metric '%s' to %d on trace '%s'", var1, var5.getCount(), this.name));

Every time when metric is increased, there are allocations in String.format, Long.valueOf for each call, even if logging is disabled (=production/release build)

Since Firebase Performance is for performance measuring, no need to add extra excessive overhead

[melissaelopez]

Hi Michael,

Thanks for the information. To get more context, is there more detail you can provide on the impact this is having? For example, was this a recent observation, did it come to your attention due to impact on users of your app, etc.

Thank you!

[stari4ek]

I've found out it while profiling my app recently.
Lots of unnecessary allocations if metric is increased multiple times per frame.
It's hard to tell if shrinked and optimized build will drop this path, but it's there when profiling debuggable build.

I'd expect that framework/library targeting performance measuring would not affect performance itself.
Wrapping it to own AtomicLong which accumulates metrics changes and setMetric only once when trace is stopped - fixes the issue.

[melissaelopez]

note: this issue is being tracked internally at b/168017204