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https://issues.apache.org/jira/browse/TINKERPOP-2759?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Stephen Mallette closed TINKERPOP-2759.
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Fix Version/s: (was: 3.6.0)
Resolution: Duplicate
> gremlinpython gives error "RuntimeError: Cannot run the event loop while
> another loop is running".
> --------------------------------------------------------------------------------------------------
>
> Key: TINKERPOP-2759
> URL: https://issues.apache.org/jira/browse/TINKERPOP-2759
> Project: TinkerPop
> Issue Type: Bug
> Components: python
> Affects Versions: 3.6.0
> Environment: I am running the code inside Docker with Python 3.9 on
> Ubuntu 20.04 with relevant package versions as follows:
> gremlinpython==3.6.0
> uvicorn==0.17.6
> fastapi==0.78.0
> Reporter: Gavin Aten
> Priority: Major
>
> Im not sure if this is the correct place to post an issue. If not, I can
> redirect this elsewhere.
> I am trying to run a fastapi app with uvicorn but am struggling to run a
> gremlinpython query (run over AWS Neptune DB) inside. It seems like
> gremlinpython tries to start up a new event loop while one is already
> running. Is it possible to get gremlinpython to use the current event loop if
> there is one running?
> The following code snippet works when running with python3 but fails when
> running with uvicorn:
>
> {code:java}
> from gremlin_python.structure.graph import Graph
> from gremlin_python.driver.driver_remote_connection import
> DriverRemoteConnection
> from fastapi import FastAPI
> def run_query(conn_string, vertex_id):
> graph = Graph()
> remoteConn = DriverRemoteConnection(conn_string, 'g')
> g = graph.traversal().withRemote(remoteConn)
> details = g.V(vertex_id).valueMap(True).toList()
> print(details)
> remoteConn.close()
> return FastAPI()
> conn_string = '<conn_string>'
> vertex_id = '<vertex_id>'
> app = run_query(conn_string, vertex_id)
> # running with:
> # uvicorn {file_name}:app{code}
>
>
> The error when running with uvicorn is as follows:
>
> {{File "/code/./app/main2.py", line 20, in <module>}}
> {{ app = run_query(conn_string, vertex_id)}}
> {{ File "/code/./app/main2.py", line 11, in run_query}}
> {{ details = g.V(vertex_id).valueMap(True).toList()}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/process/traversal.py",
> line 62, in toList}}
> {{ return self.to_list()}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/process/traversal.py",
> line 65, in to_list}}
> {{ return list(iter(self))}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/process/traversal.py",
> line 48, in {_}{{_}}next{{_}}{_}}}
> {{ self.traversal_strategies.apply_strategies(self)}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/process/traversal.py",
> line 682, in apply_strategies}}
> {{ traversal_strategy.apply(traversal)}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/remote_connection.py",
> line 78, in apply}}
> {{ remote_traversal = self.remote_connection.submit(traversal.bytecode)}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/driver_remote_connection.py",
> line 102, in submit}}
> {{ result_set = self._client.submit(bytecode,
> request_options=self._extract_request_options(bytecode))}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/client.py",
> line 148, in submit}}
> {{ return self.submit_async(message, bindings=bindings,
> request_options=request_options).result()}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/client.py",
> line 180, in submit_async}}
> {{ return conn.write(message)}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/connection.py",
> line 55, in write}}
> {{ self.connect()}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/connection.py",
> line 45, in connect}}
> {{ self._transport.connect(self._url, self._headers)}}
> {{ File
> "/usr/local/lib/python3.9/dist-packages/gremlin_python/driver/aiohttp/transport.py",
> line 80, in connect}}
> {{ self._loop.run_until_complete(async_connect())}}
> {{ File "uvloop/loop.pyx", line 1495, in
> uvloop.loop.Loop.run_until_complete}}
> {{ File "uvloop/loop.pyx", line 1488, in
> uvloop.loop.Loop.run_until_complete}}
> {{ File "uvloop/loop.pyx", line 1377, in uvloop.loop.Loop.run_forever}}
> {{ File "uvloop/loop.pyx", line 515, in uvloop.loop.Loop._run}}
> {{RuntimeError: Cannot run the event loop while another loop is running}}
>
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