python-opencv set cv2.VideoCapture connection timeout

I used **opencv-python** to capture snapshot from hundreds of thousands rtsp urls,I used gevent coroutine to accelerate capturing snapshot,But It seemed no use. and I found there no way to set rtsp connection timeout argument, it seems rtsp default connection timeout is **30s**.Can anyone help me or give some way to faster capturing snapshot from massive rtsp urls? 2018-12-04 09:44:47,285 [INFO] start 2018-12-04 09:45:17,354 [ERROR] can't open stream 2018-12-04 09:45:17,354 [INFO] end