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• enhancement (feature request)
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Reproducible in:

slackclient version: 2.1.0

python version: 3.7

I created a Slack app (using Flask) using version 1.3.1 and it could handle simultaneous Slack API calls without any issue. Since then, I've tried upgrading to slackclient==2.1.0 and see that when simultaneous calls are made, one of them will fail with the a RunTimeError that the This event loop is already running.

In order to further investigate, I created a simple Flask app which can handle simultaneous calls. The code below works without any issue however if I try to move the loop and slack WebClient initialization outside of the entry() method, simultaneous calls fail. Do these variables need to be reinitialized on each request or is there another way to only initialize them once yet be able to handle concurrent requests?

from flask_api import status
import asyncio
import slack

app = Flask(__name__)
bot_slack_token = 'xoxb-xxxxxxxxxx'

response_headers = {
    'Content-Type': 'application/json'
}

async def send_async_message(channel, text, client):
    response = await client.chat_postMessage(channel=channel, text=text)

    assert response["ok"]
    assert response["message"]["text"] == "ok"


@app.route("/")
def entry():
    asyncio.set_event_loop(asyncio.new_event_loop())
    loop = asyncio.get_event_loop()

    client = slack.WebClient(
        token=bot_slack_token,
        run_async=True
    )

    loop.run_until_complete(send_async_message(channel='#hello', text="ok", client=client)) 

    return make_response("", status.HTTP_200_OK, response_headers)


if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')