[TINKERPOP-2752] `AiohttpTransport` malfunctions in an eventlet monkey patched app

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Won't Do
• Affects Version/s: 3.6.0, 3.5.2
• Component/s: python
• Environment: python 3.8, running both natively on macOS, and within a Docker container hosted on macOS
• Assignee: Unassigned
• Reporter: Steve Kieffer
• Created: 10/Jun/22 14:15
• Updated: 25/Aug/22 10:51
• Resolved: 25/Aug/22 10:51

Description

I'm running an eventlet-based Flask web app, that starts out with a call to

eventlet.monkey_patch()

and has view functions that use gremlin-python to connect to a gremlin server.

I've found that if the browser issues several requests in rapid succession, it can provoke the

RuntimeError: Cannot run the event loop while another loop is running

error. Passing

call_from_event_loop=True

when constructing the DriverRemoteConnection just leads to a different type of error, because the problem is transient, not consistent.

I've developed a minimal example that demonstrates the issue, and can share a link to that if it would be helpful.

Possible solution:

How about supplying another transport, besides the AiohttpTransport class, which uses the websocket-client python package, instead of aiohttp?

I've made one which is very rudimentary but, in testing so far, works fine and solves this issue:

from gremlin_python.driver.transport import AbstractBaseTransport
import websocket


class WebsocketTransport(AbstractBaseTransport):

    def __init__(self, **kwargs):
        self.ws = websocket.WebSocket(**kwargs)

    def connect(self, url, headers=None):
        headers = headers or []
        self.ws.connect(url, header=headers)

    def write(self, message):
        self.ws.send_binary(message)

    def read(self):
        return self.ws.recv()

    def close(self):
        self.ws.close()

    @property
    def closed(self):
        return not self.ws.connected


def transport_factory():
    return WebsocketTransport()

Happy to open this as a PR, if it seems like a good idea.