asyncpg - 无法执行操作:正在进行另一个操作

如何解决asyncpg - 无法执行操作:正在进行另一个操作

我正在尝试解决以下错误

asyncpg.exceptions._base.InterfaceError: cannot perform operation: another operation is in progress

这里是完整的回溯:

Traceback (most recent call last):

  File "<string>",line 1,in <module>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/spawn.py",line 116,in spawn_main
    exitcode = _main(fd,parent_sentinel)
               │     │   └ 4
               │     └ 7
               └ <function _main at 0x109c8aca0>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/spawn.py",line 129,in _main
    return self._bootstrap(parent_sentinel)
           │    │          └ 4
           │    └ <function BaseProcess._bootstrap at 0x109b1f8b0>
           └ <SpawnProcess name='SpawnProcess-4' parent=36604 started>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/process.py",line 315,in _bootstrap
    self.run()
    │    └ <function BaseProcess.run at 0x109b18ee0>
    └ <SpawnProcess name='SpawnProcess-4' parent=36604 started>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/multiprocessing/process.py",line 108,in run
    self._target(*self._args,**self._kwargs)
    │    │        │    │        │    └ {'config': <uvicorn.config.Config object at 0x109cd55b0>,'target': <bound method Server.run of <uvicorn.server.Server object...
    │    │        │    │        └ <SpawnProcess name='SpawnProcess-4' parent=36604 started>
    │    │        │    └ ()
    │    │        └ <SpawnProcess name='SpawnProcess-4' parent=36604 started>
    │    └ <function subprocess_started at 0x10a4aca60>
    └ <SpawnProcess name='SpawnProcess-4' parent=36604 started>
  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/uvicorn/subprocess.py",line 61,in subprocess_started
    target(sockets=sockets)
    │              └ [<socket.socket fd=3,family=AddressFamily.AF_INET,type=SocketKind.soCK_STREAM,proto=0,laddr=('0.0.0.0',80)>]
    └ <bound method Server.run of <uvicorn.server.Server object at 0x109cd56a0>>
  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/uvicorn/server.py",line 48,in run
    loop.run_until_complete(self.serve(sockets=sockets))
    │    │                  │    │             └ [<socket.socket fd=3,80)>]
    │    │                  │    └ <function Server.serve at 0x10a4abca0>
    │    │                  └ <uvicorn.server.Server object at 0x109cd56a0>
    │    └ <function BaseEventLoop.run_until_complete at 0x10a205820>
    └ <_UnixSelectorEventLoop running=True closed=False debug=False>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/base_events.py",line 603,in run_until_complete
    self.run_forever()
    │    └ <function BaseEventLoop.run_forever at 0x10a205790>
    └ <_UnixSelectorEventLoop running=True closed=False debug=False>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/base_events.py",line 570,in run_forever
    self._run_once()
    │    └ <function BaseEventLoop._run_once at 0x10a209310>
    └ <_UnixSelectorEventLoop running=True closed=False debug=False>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/base_events.py",line 1859,in _run_once
    handle._run()
    │      └ <function Handle._run at 0x10a13ed30>
    └ <Handle <TaskWakeupMethWrapper object at 0x10bb75a60>(<_GatheringFu...in progress')>)>
  File "/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/events.py",line 81,in _run
    self._context.run(self._callback,*self._args)
    │    │            │    │           │    └ <member '_args' of 'Handle' objects>
    │    │            │    │           └ <Handle <TaskWakeupMethWrapper object at 0x10bb75a60>(<_GatheringFu...in progress')>)>
    │    │            │    └ <member '_callback' of 'Handle' objects>
    │    │            └ <Handle <TaskWakeupMethWrapper object at 0x10bb75a60>(<_GatheringFu...in progress')>)>
    │    └ <member '_context' of 'Handle' objects>
    └ <Handle <TaskWakeupMethWrapper object at 0x10bb75a60>(<_GatheringFu...in progress')>)>

> File "./xxx/xxx/xxx.py",line 144,in get_disclosure_data
    hh_json,db_json = await asyncio.gather(*coroutines)
                             │       │       └ [<coroutine object xxxx at 0x10bb2cb40>,<coroutine object db_call at 0x10bb2cc40>]
                             │       └ <function gather at 0x10a1fad30>
                             └ <module 'asyncio' from '/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/__init__.py'>

  File "./xxx/xxx/xxx.py",line 52,in db_call
    db_json = await asyncio.gather(*coroutines,loop=asyncio.get_event_loop())
                    │       │       │                │       └ <built-in function get_event_loop>
                    │       │       │                └ <module 'asyncio' from '/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/__init__.py'>
                    │       │       └ [<coroutine object DBConnectionManager.fetch_item at 0x10bb434c0>,<coroutine object DBConnectionManager.fetch_item at 0x10bb...
                    │       └ <function gather at 0x10a1fad30>
                    └ <module 'asyncio' from '/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/__init__.py'>

  File "./xxx/xxx/xx.py",line 97,in fetch_item
    await self._connection_pool.release(self.con)
          │    │                │       │    └ <PoolConnectionProxy [released] 0x10bbc9cd0>
          │    │                │       └ <chd_api.data.db.DBConnectionManager object at 0x10b946a30>
          │    │                └ <function Pool.release at 0x10b956a60>
          │    └ <asyncpg.pool.Pool object at 0x10bb131e0>
          └ <chd_api.data.db.DBConnectionManager object at 0x10b946a30>

  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/asyncpg/pool.py",line 666,in release
    return await asyncio.shield(ch.release(timeout))
                 │       │      │  │       └ None
                 │       │      │  └ <function PoolConnectionHolder.release at 0x10b952e50>
                 │       │      └ <asyncpg.pool.PoolConnectionHolder object at 0x10bb2a5c0>
                 │       └ <function shield at 0x10a1faee0>
                 └ <module 'asyncio' from '/Users/ddd/.pyenv/versions/3.8.6/lib/python3.8/asyncio/__init__.py'>
  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/asyncpg/pool.py",line 218,in release
    raise ex
  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/asyncpg/pool.py",line 208,in release
    await self._con.reset(timeout=budget)
          │    │                  └ None
          │    └ <member '_con' of 'PoolConnectionHolder' objects>
          └ <asyncpg.pool.PoolConnectionHolder object at 0x10bb2a5c0>
  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/asyncpg/connection.py",line 1311,in reset
    await self.execute(reset_query,timeout=timeout)
          │    │       │                    └ None
          │    │       └ 'SELECT pg_advisory_unlock_all();\nCLOSE ALL;\nUNLISTEN *;\nRESET ALL;'
          │    └ <function Connection.execute at 0x10b93f3a0>
          └ <asyncpg.connection.Connection object at 0x10bc34120>
  File "/Users/ddd/Desktop/repos/xxx/.venv/lib/python3.8/site-packages/asyncpg/connection.py",line 297,in execute
    return await self._protocol.query(query,timeout)
                 │    │               │      └ None
                 │    │               └ 'SELECT pg_advisory_unlock_all();\nCLOSE ALL;\nUNLISTEN *;\nRESET ALL;'
                 │    └ <member '_protocol' of 'Connection' objects>
                 └ <asyncpg.connection.Connection object at 0x10bc34120>
  File "asyncpg/protocol/protocol.pyx",line 321,in query
    self._check_state()
  File "asyncpg/protocol/protocol.pyx",line 684,in asyncpg.protocol.protocol.BaseProtocol._check_state
    raise apg_exc.InterfaceError(
          │       └ <class 'asyncpg.exceptions._base.InterfaceError'>
          └ <module 'asyncpg.exceptions' from '/Users/ddd/Desktop/repos/chd-api/.venv/lib/python3.8/site-packages/asyncpg/exception...

asyncpg.exceptions._base.InterfaceError: cannot perform operation: another operation is in progress

我有以下代码来设置连接池并使用池中的连接执行查询

class DBConnectionManager(object):
    """ Class for setting up and tearing down db connection """

    def __init__(self):
        self.host = SETTINGS.db_host
        self.database = SETTINGS.db_name
        self.user = SETTINGS.db_user
        self.password = SETTINGS.db_password
        self.port = "5432"

        self._connection_pool = None
        self.con = None

    async def connect(self):
        if not self._connection_pool:
            try:
                self._connection_pool = await asyncpg.create_pool(
                    host=self.host,database=self.database,user=self.user,password=self.password,port=self.port,min_size=50,max_size=100,)
                logger.info("Database pool connection opened")

            except Exception as e:
                logger.exception(e)

    async def fetch_item(self,query: str,*args):
        if not self._connection_pool:
            await self.connect()
        else:
            self.con = await self._connection_pool.acquire()
            try:
                result = await self.con.fetch(query,*args)
                return result
            except Exception as e:
                logger.exception(e)
            finally:
                await self._connection_pool.release(self.con)

    async def close(self):
        if not self._connection_pool:
            try:
                await self._connection_pool.close()
                logger.info("Database pool connection closed")
            except Exception as e:
                logger.exception(e)

并且我正在尝试使用以下方法执行大约 22 个数据库调用

async def db_call(db,lat,lng):
    """
    Performs the necessary db calls given a lat,lng

    required Input:
        lat::float a latitude in decimal degrees. Must be specified with `lng` (i.e. 39.2994)
        lng::float a longitude in decimal degrees. Must be specified with `lat` (i.e. -122.33)

    Returns:
        dict
    """
    coroutines = []
    for table in db_map:

        # sql columns
        db_fields = ",".join(
            [
                f"{col} AS {db_map[table]['fields'][col]}"
                for col in db_map[table]["fields"]
            ]
        )

        # Output names
        api_fields = [db_map[table]["fields"][col] for col in db_map[table]["fields"]]

        if db_map[table]["query_type"] == "pip":
            limit = db_map[table]["options"]["LIMIT"]
            query = f"SELECT {db_fields} from {table} WHERE (ST_Covers(geom,GeomFromEWKT('SRID=4326;POINT({lng} {lat})'))) LIMIT {limit};"

        else:
            distance = db_map[table]["options"]["disTANCE"]
            geo2geo = f"geom::geography,GeomFromEWKT('SRID=4326;POINT({lng} {lat})')::geography"
            query = (
                f"SELECT {db_fields},ST_distance({geo2geo})"
                f"from {table} WHERE (ST_DWithin({geo2geo},{distance}))"
                f"ORDER BY ST_distance({geo2geo}) LIMIT 1;"
            )

        coroutines.append(db.fetch_item(query))

    db_res = await asyncio.gather(*coroutines)
    
    .... code for processing results

我已经检查了 asyncpg github 上有关此错误的几个问题,但仍未找到合适的解决方案。另请注意,此调用是在 FastAPI 中执行的。任何有关为什么会发生此错误/解决错误的步骤的指导将不胜感激。

解决方法

self.con 中对 fetch_item 的赋值导致多个协程共享同一个连接。虽然您确实希望它们共享连接池,但共享相同的连接没有意义,因为连接是有状态的。

要解决此问题,请将 self.con 的用法替换为局部变量 con

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