React Native Android App consumes 30mA per hour even though app is in background

Question

Performed current drain test on sample (Welcome to React Native) app when the app was in background for an hour and the results are as follows:

Sample application with RN version 34 : 31.54mA Sample application with RN version 22 : 24.60mA 

Where as the sample native android app only consumes about 10mA in the same scenario.

Tools Used :

Power monitor (H/w) Power tool (S/w) 

1) Can anybody confirm the above test and explain the reason behind high current drain ?

2) Is it normal for react native apps to have higher current drain values as compared to the native android app?

React Native version: RN 0.22 and RN 0.34 Platform : Android 

Answer 1

While I do not know the internals, I believe the following statement is a good hypothesis;

Even when you have installed the application in release mode (in other words, there is no npm server and the app uses local .jsbundle) React Native has to keep two things working;

1. A native thread to respond to whatever our JS code required (draw this, get geolocation etc.)
2. A Javascript VM to interpret our code. (.jsbundle file included with the APK)

I believe, due to this added load, a react native app should consume more power, assuming everything else is equal.