Segmentation fault

[dongshimou]

pi@raspberrypi:~/pistreaming $ python3 server.py
Initializing camera
Initializing websockets server on port 8084
Initializing HTTP server on port 8082
Initializing broadcast thread
Spawning background conversion process
Starting recording
Starting websockets thread
Starting HTTP server thread
Starting broadcast thread
Segmentation fault.

raspberry pi 4b.
std camera.

[dongshimou]

python version: Python 3.7.3
pip3 version: pip 18.1 from /usr/lib/python3/dist-packages/pip (python 3.7)

when i install python3-ws4py.

Breaks: python3-ws4py (<= 0.4.2+dfsg1-2) but 0.4.2+dfsg1-2 is to be installed

so, i try to pip install.

pip3 install ws4py

Successfully installed ws4py-0.5.1