vlki / react-native-asyncstorage-setitem-memory-problem-demo

Sample project demonstrating React Native app increasing its memory usage when periodically saving long string via AsyncStorage.setItem, eventually getting killed by system, because it hits the limits.

The app gets killed only when running on device, when running in simulator the memory gets freed periodically as seen on XCode's memory usage screenshots below. Device used: iPad Mini 2 ME800SL/A with iOS 11.0.3. Simulator used: iPad Pro (9.7-inch) with iOS 11.0.1.

App on device and in simulator was built with Release build configuration.

Project is ejected create-react-native-app with react-native updated to latest version 0.49.3.

App.js code to reproduce:

import React from 'react'
import { AsyncStorage, Text, View } from 'react-native'

const FIXED_STRING_LENGTH = 150 * 1000 * 1000
const SAVE_STRING_LENGTH = 10 * 1000 * 1000

export default class App extends React.Component {
  constructor(props) {
    super(props)

    this.fixedString = 'a'.repeat(FIXED_STRING_LENGTH)
  }

  componentDidMount() {
    setTimeout(this.saveString, 5000)
  }

  saveString = () => {
    AsyncStorage.setItem('foo', 'a'.repeat(SAVE_STRING_LENGTH)).then(() => {
      setTimeout(this.saveString, 2000)
    })
  }

  render() {
    return (
      <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
        <Text>
          This app saves long string via AsyncStorage.setItem every 2 seconds,
          gradually increases its memory usage and eventually gets killed by
          iOS because it wants too much memory when running on device
          (iPad Mini 2 ME800SL/A).
        </Text>
      </View>
    )
  }
}

XCode memory usage when running on device (iPad Mini 2 ME800SL/A with iOS 11.0.3), just seconds before it gets killed by system:

XCode memory usage when running in simulator (iPad Pro (9.7-inch) with iOS 11.0.1):

$ react-native info

Environment:
  OS:  macOS High Sierra 10.13
  Node:  8.8.1
  Yarn:  1.2.1
  npm:  5.4.2
  Watchman:  4.9.0
  Xcode:  Xcode 9.0.1 Build version 9A1004
  Android Studio:  Not Found

Packages: (wanted => installed)
  react: 16.0.0 => 16.0.0
  react-native: 0.49.3 => 0.49.3

Check yourself

• Clone repository, go to the cloned repo directory
• Fetch node modules by npm install
• In XCode open the ios directory
• Connect your iOS device to computer
• Edit your Run scheme and make sure have Build configuration Release and Debug executable checked
• Run on your iOS device
• See the memory usage in XCode's Debug Navigator