What happens when millis() overflows?

I'm developing opens source project to sustentable agriculture.
I want to know what happens when millis() overflows...

If I need to remove all threads -> reset millis() -> addition all threads back to ThreadController in main code.

Thank you and congratulation for awesome library.

The issue names no files or tests. Start by locating the ArduinoThread timing code and its uses of millis(), then check the Arduino millis() overflow behavior; document the observed behavior and any required guidance for managing threads around overflow.

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