从Django信号接收器调用Channels AsyncWebsocketConsumer函数无效

• 已多次排查调试，信号接收器内代码执行正常，但消费者的new_ticket函数始终未被调用，网页无更新。
• 将group_send代码移到消费者的connect函数中（替换async_to_sync为await），new_ticket可正常触发。
• 使用InMemoryChannelLayer，语法已确认无误，查阅大量示例仍未解决问题。

相关代码 #

signals.py #

# signals.py
@receiver(post_save, sender=Ticket)
def new_ticket(sender, instance, created, **kwargs):
    print("in receiver")
    if created:
        print("in created")
        channel_layer = get_channel_layer()
        print(channel_layer)
        async_to_sync(channel_layer.group_send(
        'tickets_updates_group',
        {
            'type': 'new_ticket',
            'subject': "from receiver"
        }))
        print("after async_to_sync")

信号接收器中所有打印语句均正常执行。

consumers.py #

# consumers.py
class Tickets(AsyncWebsocketConsumer):
    async def connect(self):
        await self.channel_layer.group_add('tickets_updates_group', self.channel_name)
        await self.accept()
    
    async def disconnect(self, close_code):
        await self.channel_layer.group_discard('tickets_updates_group', self.channel_name)
        await self.close()

    async def new_ticket(self, event):
        print('in consumer.new_ticket')
        subject = event['subject']
        print("subject: " + subject)
        await self.send(text_data=json.dumps({
            'subject': subject
        }))
        print("after send")

settings.py #

# settings.py
CHANNEL_LAYERS = {
    "default": {
        "BACKEND": "channels.layers.InMemoryChannelLayer"
    }
}

内容的提问来源于stack exchange，提问作者Filip Kowalczyk