On iPhone App Restart: File Descriptors Exhausted & Failed HTTP Requests

BEHAVIOR

• App runs great on first install.
• If I close the app and reopen, many times the network requests fail, most likely due to too many open files.
• If I restart the app 4 times, everything seems to load fine (until next time). A fresh install works as well.

APP

• Flutter app. Utilizes flutter map package, which displays map tile layers. Otherwise, pulls JSON/API data every so often.

• Heavy/frequent pulling of tile images (typically ~1000 during a single pan).

PROBLEM DEVICES:

• Issues ONLY happens on physical iPhones (tested on 11 and 15).
• iOS simulators work fine.
• Androids work fine
• On the Androids or simulator, I can pan the map and pull 3000+ tile images, and overlay data, with no issues.

TESTING

• I have inspected disposal methods, closing network clients, even tried "exit(0)" in various places. Have tried app lifecycle widgets on paused, detached, resumed. Nothing changes the behavior.

• At one point, I thought I had the issue fixed when I changed my DNS from 1.1.1.1 to automatic, since all the working devices seemed to have router-defined DNS and my test device had manual IP. But then the problem came back again.

COMMON ERRORS (upon restart)

• SocketException: Connection failed (OS Error: Too many open files, errno = 24)
• SocketException: Failed host lookup: 'site.com' (OS Error: nodename nor servname provided, or not known, errno = 8)
• Sometimes failed to load assets as well (icons, etc).

QUESTIONS

• What is being "fixed" by reopening the app 4 times in a row on the iOS side?
• Is there anything I can do in the native code, so that the app always restarts fresh, and doesn't "hang on" to anything that may be causing the OS Errors?
• Could it be an IPv4 / IPv6 issue?

REFERENCES

• I did recently find this dart thread as well, not sure if it is fully the same issue: https://github.com/dart-lang/http/issues/197

• Flutter Map Repo for Tile Layers: https://github.com/fleaflet/flutter_map/tree/7632ccc6d95cf4b0d02760f6d259495e7a1d09d0/lib/src/layer/tile_layer

• DIO Package: https://pub.dev/packages/dio