Sometimes blocking about test_microphone.py

Using this python script to test microphone connecting to websocket server.
https://github.com/alphacep/vosk-server/blob/master/websocket/test_microphone.py
There is blocking (as following) if server side doesn't return response at each data chunk.
while True:
data = await audio_queue.get()
await websocket.send(data)
print (await websocket.recv()) # blocking here waiting for message.

It happened when VAD is applied at server side and no response if data chunk is silent.