DataChan send file fail

[changtsing]

Hello.
My program is running on the macOS system and sends files to the peer (app) through Datachan. Datachan is set to send files sequentially.
The general logic of the code is as follows:

while (read file) {
    std::cout << "bufferedAmount ....." << dc->bufferedAmount() << std::endl;
    while (dc->bufferedAmount()!= 0) {
        std::cout << "bufferedAmount wait....." << dc->bufferedAmount() << std::endl;
        std::this_thread::sleep_for(std::chrono::milliseconds(500));
    }
    dc->send(data);
}

At the beginning, the peer could receive messages. However, after a period of time, the peer couldn't receive any messages. Then I added a waiting mechanism for the condition that bufferedAmount!= 0, and I found that there was a situation where bufferedAmount didn't decrease.
I don't know what happened and I'm looking forward to your suggestions.

iperf3 test results