FirebaseApp.configure() - ~100% CPU usage

[iwwwh]

Description

Hi,

Calling FirebaseApp.configure() leads to extremely high CPU usage (90–100%) for about 10 seconds immediately after invocation.

I spent some time profiling and isolating this behavior, and I’ve traced the CPU spike specifically to the FirebaseApp.configure() call.

Products used in the app: Analytics, Auth, Crashlytics, Database, Firestore, Functions, Messaging, AdMob.

• AdMob installed via GoogleMobileAdsSDK package 12.6.0 and is linked with Firebase
• Messaging swizzling disabled

Commenting out FirebaseApp.configure() helps to fix the issue. I’m not sure how to debug it further to provide more details.

Reproducing the issue

Add the products listed above to the new Xcode project, run FirebaseApp.configure() in appDidFinishLaunching.

Note: tested only on real device.

Firebase SDK Version

11.15.0

Xcode Version

16.3

Installation Method

Swift Package Manager

Firebase Product(s)

All

Targeted Platforms

iOS

Relevant Log Output

If using Swift Package Manager, the project's Package.resolved

Expand Package.resolved snippet

Replace this line with the contents of your Package.resolved.

If using CocoaPods, the project's Podfile.lock

Expand Podfile.lock snippet

Replace this line with the contents of your Podfile.lock!

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[ncooke3]

Hi @iwwwh, thanks for the descriptive writeup and apologies for the trouble. Were you able to capture a profiled breakdown of where in the FirebaseApp.configure() call are things bogging down?

[iwwwh]

Hi @ncooke3 ,

Thanks for your reply.

To be honest, I’m not very familiar with debugging that kind of issues. However, it shouldn’t be very hard to reproduce, since it does not require any Firebase product usage at all, just FirebaseApp.configure().

If you need any additional info from me, please feel free to give me some instructions and I’ll be happy to share with you.