Multiple problems when app is running in the background for long periods of time

[willbattel]

I'm not sure if this is a bug or not. If you'd rather I close this and discuss on Discord I can, but there are so many simultaneous discussions on Discord that sometimes it is hard to get answers.

Issue

All Firebase modules are working flawlessly when app is in the foreground, and for some time while in the background. After some time passes, we have trouble logging events and getting user auth tokens.

For example, we're having trouble with both of these:

Firebase.auth().currentUser.getIdToken(true).then((token) => {
    doSomethingWithToken(token);
});

Firebase.analytics().logEvent('some_event', {
    parameter1: 1,
    parameter2: 'B'
});

After some period of time we can't seem to get any new tokens, so our app starts to send expired tokens with it's requests to Cloud Functions, resulting in 403 errors. When we can't get any new tokens, the analytics events also stop logging.

For example, we sent roughly 230,000 HTTP requests to Cloud Functions with auth tokens attached in the past 30 days. Roughly 55,000 of those failed from expired tokens. We log an analytic event on the client every time a request is sent, and we only received roughly 175,000 analytic events. Call me crazy but thats one hell of a coincidence.

Environment

1. Application Target Platform: iOS (we target both but have not tested on Android)

2. Development Operating System: macOS High Sierra

3. Build Tools: Xcode 9.2, iOS 10.0 through 11.3

4. React Native version: 0.54.4

5. RNFirebase Version: 3.3.1

6. Firebase Module: Only noticed on Authentication and Analytics but it likely isn't just those

This was my conversation with the author of react-native-background-geolocation while I was trying to determine if it was that plugin or this one that was choking. It may or may not be helpful but I thought I'd link it just in case.

Any ideas? Thanks.

[chrisbianca]

@wbattel4607 Can I just clarify, when you say that it works for some time in the background, does that mean that the app remains in the background when these issues are happening? Or is the app in the foreground when the issues start?

[willbattel]

From what I can tell, and I am not 100% sure, the issues are starting some time after the app enters and remains in the background (but not terminated/suspended). They don't seem to happen immediately- nor predictably for that matter. But it seems to occur eventually when the app is in the background state.

[chrisbianca]

If the app comes back into the foreground, does it start working again?

[willbattel]

We think that is the case. Due to its unpredictability, we're having difficulty troubleshooting this to confirm exactly when the problems start and stop. We're not seeing any issues when the app is in the foreground, including when returning from the background where these issues had occurred.

[willbattel]

I'm thinking this could be related to my previous issue with AdMob (#442). In that issue I had noticed AdMob had to be re-initialized every time the app returned from the background. Perhaps other Firebase modules are de-initializing when he app moves to the background like AdMob does? Except, unlike AdMob, these modules are functioning correctly on returning to the foreground.

Just food for thought. I have no idea what's going on. 🙃

[chrisbianca]

It certainly sounds like in the background the app is somehow being restricted.

Out of interest, what exactly are you trying to do whilst the app is in the background?

[willbattel]

Our app is location-based, so we have to update the user's location when they move. For 90% of those location updates, the app is in the background.

Every time the app registers a location update, it logs an Analytic event and sends an HTTP POST request to Cloud Functions with the location information and user auth token for our system to update the database, send notifications, etc....

After each HTTP request, we forceRefresh an auth token from Firebase and update the URL and HTTP Headers for the next request.

The HTTP requests are coming through no problem, but Firebase fails to keep the user auth token up to date and log the analytic events.

[willbattel]

We're also running into another problem with authentication that may or may not be related in terms of the cause. I'm going to open a separate issue for it because it's a separate problem.

[Salakar]

A very random shot in the dark but this question on SO seems slightly similar and am wondering if the solution in the first answer holds any bias, no harm trying it: https://stackoverflow.com/questions/41177624/firebase-unity-sdk-100-hang-on-ios-when-the-application-resumes - the info plist thing

On our end though I'm not even sure where we could begin to debug this, seems hard to consistantly reproduce, I'll have a look through the auth/analytics code tomorrow and see if anything sparks an idea.