Issuing Advisory Lock

还没有人认领这个 Issue。

* **asyncpg version**: 0.25.0
* **PostgreSQL version**: 12.11
* **Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
the issue with a local PostgreSQL install?**:
* **Python version**: 3.9
* **Platform**: Linux
* **Do you use pgbouncer?**: No
* **Did you install asyncpg with pip?**: yes
* **If you built asyncpg locally, which version of Cython did you use?**: No
* **Can the issue be reproduced under both asyncio and
[uvloop](https://github.com/magicstack/uvloop)?**: NA

Receiving this error
```
asyncio.exceptions.TimeoutError
[View similar errors](https://link.datadoghq.com/apm/error-tracking?issueId=...471-da7ad0900002)

Traceback (most recent call last):
File /usr/local/lib/python3.9/site-packages/ddtrace/contrib/asyncpg/patch.py, line 89, in _traced_query
return await method(*args, **kwargs)
File asyncpg/protocol/protocol.pyx, line 338, in query
asyncio.exceptions.TimeoutError
```
Due to internal query call:
`SELECT pg_advisory_unlock_all ( ) CLOSE ALL UNLISTEN * RESET ALL`

Happening quite frequently

从 asyncpg/protocol/protocol.pyx 中的 traceback 入口点以及包含 SELECT pg_advisory_unlock_all()、CLOSE ALL、UNLISTEN * 和 RESET ALL 的内部查询序列开始。使用 asyncpg 0.25.0 和 PostgreSQL 12.11 重现报告的超时，然后确定预期行为，并验证 advisory lock 清理不再超时。

由索引模型根据 Issue 内容生成。