setTimeout executes callback immediately when Remote JS Debugging is enabled

🐛 Bug Report

Environment

Expo CLI 2.17.1 environment info: System: OS: Windows 10 Binaries: Yarn: 1.15.2 - C:\Program Files (x86)\Yarn\bin\yarn.CMD npm: 6.4.1 - C:\Program Files (x86)\nodejs\npm.CMD

Target: Android and iOS

Steps to Reproduce

1. Create a new expo app with expo init, using the blank template.
2. Add the following function to App.js and invoke the function from componentDidMount()

function loop() {
    console.log(new Date().getSeconds())
    setTimeout(loop, 1000)
}

1. expo start and open the app on an iOS or Android device. Tested on iOS 12.2 and Android 7.1.1.
2. By default, remote JS debugging is disabled. The log messages in the expo console window will show the expected behavior: “1, 2, 3, 4, 5, …”
3. On the mobile device, enable remote JS debugging from the developer menu. The log messages in the Expo console windows will be “4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, …”. I.e. the loop is executing very rapidly.

Expected Behavior

The console.log() messages show each second exactly once while Remote JS Debugging is enabled:

1
2
3
4
5
6
...

Actual Behavior

console.log() is called rapidly and each second displays many times, e.g.:

1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
...

Reproducible Demo

https://github.com/srmagura/expo-settimeout-repro

[srmagura]

I was able to reproduce it in bare React Native and found that there is already an issue for it in the React Native repo, #26828. 😁

Turns out it occurs when the iPhone’s time and the PC’s time don’t match. My iPhone’s clock has been 10+ minutes in the future this whole time (possibly because it is lacking a SIM card), so that explains it!

[sandinosaso]

This is still an Issue I can confirm, in the latest expo version 0.40.0

expo@~40.0.0:
  version "40.0.0"
  resolved "https://registry.yarnpkg.com/expo/-/expo-40.0.0.tgz#6caf03587532cd18b482991332a8b75eeca2fcb7"

It was hard for me to figure out what was going on, I literally expended hours thinking my Hooks logic was wrong, then I doubted the Snackbar component from ‘react-native-paper’ (internally uses setTimeout for the duration it uses to show the snackbar) was not working ok, till I figured out that it was this issue.

This also happens when you go to https://snack.expo.io/ and Choose Android as Device (so I assume that it using debug mode on).

Try for example: SnackBar Expo Example