http1_request_header() error: asyncio.exceptions.CancelledError

[niudi]

There is one error in my app server:

File "/usr/local/lib/python3.8/site-packages/sanic/http/http1.py", line 123, in http1
await self.http1_request_header()
File "http1_request_header", line 18, in http1_request_header
ServiceUnavailable,
File "/usr/local/lib/python3.8/site-packages/sanic/server/protocols/base_protocol.py", line 82, in receive_more
await self._data_received.wait()
File "/usr/local/lib/python3.8/asyncio/locks.py", line 309, in wait
await fut
asyncio.exceptions.CancelledError

server environment:

• sanic: 22.6.2
• python: 3.8.5
• linux os:
  LSB Version: core-11.1.0ubuntu4-noarch:security-11.1.0ubuntu4-noarch
  Distributor ID: Ubuntu
  Description: Ubuntu 22.04.1 LTS
  Release: 22.04

log screenshot: