Python 问题：无法在单独的线程或事件循环中运行连接 aiohttp 服务器

Question

I have been unable to get a connexion server using aiohttp into the background so that the main thread isn't hung when I start my webserver.

I think I probably could by using asyncio and create a task for everything else, but I'm writing a library that is going to be reused by other people and companies and I don't have the ability to enforce that kind of design pattern unilaterally and universally.

I have gotten this working(from https://newbedev.com/how-to-run-an-aiohttp-server-in-a-thread ):

import asyncio
import threading
from aiohttp import web


def aiohttp_server():
    def say_hello(request):
        return web.Response(text='Hello, world')

    app = web.Application(debug=True)
    app.add_routes([web.get('/', say_hello)])
    handler = app.make_handler()
    return handler


def run_server(handler):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    server = loop.create_server(handler, host='127.0.0.1', port=8089)
    loop.run_until_complete(server)
    loop.run_forever()


t = threading.Thread(target=run_server, args=(aiohttp_server(),))
t.start()

for i in range(50000):
   print('Hi from Main Thread')
   time.sleep(5)

This leaves the server up and running and then allows the main thread to keep going.

However, when I try to take this code and make it work with starting up the connexion server using the following code, I can't get things up and running and I'm on day 2 and I have got to get moving. I'm hoping someone sees the dumb thing I've done or misunderstood and can tell me how to fix it.

def initializeServerTest():

    app = connexion.AioHttpApp(__name__, 
        port=8080, 
        specification_dir='openAPISpecs/',
        # https://github.com/OpenAPITools/openapi-generator/issues/1322
        only_one_api=True
        )
   
    app.add_api('openAPISpec.json', 
        arguments={'title': 'Instrument and HUB API'}, 
        pythonic_params=True, 
        validate_responses=True
        )

    # Configure default CORS settings.
    cors = aiohttp_cors.setup(app.app, defaults={
            "*": aiohttp_cors.ResourceOptions(allow_credentials=True,
                                            expose_headers="*",
                                            allow_headers="*", 
                                            allow_methods=["GET", "POST", "PUT"]
                                            )
    })

    # Configure CORS on every route
    for route in list(app.app.router.routes()):
        cors.add(route)
    
    # now create a runner we will start later
    runner = web.AppRunner(app.create_app())

    return runner

def run_server(runner):
    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(runner.setup())
    site = web.TCPSite(runner, 'localhost', 8080)
    loop.run_until_complete(site.start())
    loop.run_forever()

def StartServerInBackground():
    t = threading.Thread(target=run_server, args=(initializeServerTest(),))
    t.start()

When I execute this I get my main thread back, but the web server does not respond to any requests.

Any help would be much appreciated

Answer 1

Alright, so here was the solution I came up with:

import connexion
from aiohttp import web
from aiohttp_cors
import threading

app = {}
apprunner = {}

def _initializeServer():

    # use module level app
    global app

    app = connexion.AioHttpApp(__name__, 
        port=8080, 
        specification_dir='openAPISpecs/',
        # https://github.com/OpenAPITools/openapi-generator/issues/1322
        only_one_api=True
        )

    app.add_api('openAPISpec.json', 
        arguments={'title': 'Analyzer and HUB API'}, 
        pythonic_params=True, 
        validate_responses=True,
        # doesn't always work with JSON bodies: https://github.com/zalando/connexion/issues/837
        strict_validation=True
        )

    # Configure default CORS settings.
    cors = aiohttp_cors.setup(app.app, defaults={
            "*": aiohttp_cors.ResourceOptions(allow_credentials=True,
                                            expose_headers="*",
                                            allow_headers="*", 
                                            allow_methods=["GET", "POST", "PUT", "DELETE"]
                                        )
    })

    # Configure CORS on every route
    for route in list(app.app.router.routes()):
        cors.add(route)

def _startServer_NonBlocking(runner):
    #store runner at module level for use later
    global apprunner
    apprunner = runner

    loop = asyncio.new_event_loop()
    asyncio.set_event_loop(loop)
    loop.run_until_complete(runner.setup())

    site = web.TCPSite(runner, 'localhost', 8080)
    loop.run_until_complete(site.start())
    loop.run_forever()

def startServer_NonBlocking():
    # grab module level serverRunning for comparison in next line
    global serverRunning

    # if the server isn't already running
    if(serverRunning == False):
        # configure new thread and start it
        newThread = threading.Thread(target=_startServer_NonBlocking, args=(_initializeServer_NonBlocking(),))
        newThread.start()

        # set flag that the server is running so we don't ever try to start it again
        serverRunning = True

The secret sauce was in finding that you had to use app.app to get the runner and then you could use that later on to do the setup per the cookbook on the connexion documentation.