How to use gstreamer to output rtsp stream for multiple clients to access

Question

I used the solution of< https://stackoverflow.com/questions/47396372/write-opencv-frames-into-gstreamer-rtsp-server-pipeline/60580247#60580247>, but when I use multiple clients to access the rtsp stream , The error of Assertion fctx->async_lock failed at libavcodec/pthread_frame.c:155 appeared. I am new to gstreamer, Here is the complete Python code (copied from WisdomPill's answer):

import cv2
import gi

gi.require_version('Gst', '1.0')
gi.require_version('GstRtspServer', '1.0')
from gi.repository import Gst, GstRtspServer, GObject, GLib

class SensorFactory(GstRtspServer.RTSPMediaFactory):
    def __init__(self, **properties):
        super(SensorFactory, self).__init__(**properties)
        self.cap = cv2.VideoCapture("http://192.168.2.153/video/mjpg.cgi")
        self.number_frames = 0
        self.fps = 10
        self.duration = 1 / self.fps * Gst.SECOND  # duration of a frame in nanoseconds
        self.launch_string = 'appsrc name=source is-live=true block=true format=GST_FORMAT_TIME ' \
                             'caps=video/x-raw,format=BGR,width=640,height=480,framerate={}/1 ' \
                             '! videoconvert ! video/x-raw,format=I420 ' \
                             '! x264enc speed-preset=ultrafast tune=zerolatency ' \
                             '! rtph264pay config-interval=1 name=pay0 pt=96'.format(self.fps)

    def on_need_data(self, src, lenght):
        if self.cap.isOpened():
            ret, frame = self.cap.read()
            if ret:
                data = frame.tobytes()
                buf = Gst.Buffer.new_allocate(None, len(data), None)
                buf.fill(0, data)
                buf.duration = self.duration
                timestamp = self.number_frames * self.duration
                buf.pts = buf.dts = int(timestamp)
                buf.offset = timestamp
                self.number_frames += 1
                retval = src.emit('push-buffer', buf)

                print ('pushed buffer, frame {}, duration {} ns, durations {} s'.format(self.number_frames, self.duration, self.duration / Gst.SECOND))

                if retval != Gst.FlowReturn.OK:
                    print(retval)

    def do_create_element(self, url):
        return Gst.parse_launch(self.launch_string)

    def do_configure(self, rtsp_media):
        self.number_frames = 0
        appsrc = rtsp_media.get_element().get_child_by_name('source')
        appsrc.connect('need-data', self.on_need_data)


class GstServer(GstRtspServer.RTSPServer):
    def __init__(self, **properties):
        super(GstServer, self).__init__(**properties)
        self.factory = SensorFactory()
        self.factory.set_shared(True)
        self.get_mount_points().add_factory("/test", self.factory)
        self.set_service('9999')
        self.attach(None)

Gst.init(None)
server = GstServer()
loop = GLib.MainLoop()
loop.run()

if you have any suggestions, I would appreciate it