Thanks for the response. Due to the 500-character limit, I’m providing my answer to the question below

There’s a requirement for our app: the iOS client must send a keep-alive packet every second. based on our stress test logs, we’ve observed that DispatchSourceTimer gets suspended for 30 seconds to 1 minute during screen lock.

I’m able to reproduce the issue both when the app is in the background and in the foreground — but only when the device screen is locked.

sorry , it's typo , should be iOS app