Poor interaction with threads (python 2.7)

[melancholy]

the interaction between this library, graphql-core, and promise appears to allow execution to hop threads especially (only?) when using a middleware and nested resolvers. this is inconsistent with flasks threading model and the ability to access the request/g thread locals

with the attached (very contrived) example, when submitting the query with concurrent requests the requests frequently fail because the key created in get_context doesn't exist on the threadlocal flask.g object in the resolvers. This happens when a thread accesses the promise.async_instance which isn't thread local, and resolves a promise that was created on a different thread.
query.txt

from flask import Flask
from flask_graphql import GraphQLView


app = Flask(__name__)

import graphene
import threading
import time
from flask import g

def get_user(info):
    return g.get(info.context['key']) 

class User(graphene.ObjectType):
    id = graphene.ID()
    name = graphene.String()
    friend = graphene.Field(lambda: User)
    age = graphene.Int()
    apple = graphene.String()

    @classmethod
    def resolve_friend(cls, root, info):
        time.sleep(.1)
        x = get_user(info)
        return User(id=id(root), name=':'.join([x.name, threading.current_thread().name]))
    
    @classmethod
    def resolve_age(cls, root, info):
        time.sleep(.1)
	return 5

    @classmethod
    def resolve_apple(cls, root, info):
        time.sleep(.1)
        return "Apple"

class Query(graphene.ObjectType):
    me = graphene.Field(User)

    def resolve_me(self, info):
        time.sleep(.1)
        return get_user(info)

schema = graphene.Schema(query=Query)

ahh = {}
def dummy_middleware(next, root, info, **args):
    return_value = next(root, info, **args)
    return return_value

import random
random.seed()

class TestQLView(GraphQLView):
    def get_context(self, request):
	# set a random key in g to be used by resolvers
        key = str(random.randint(0,50))
	name = threading.current_thread().name
        user = User(id=key, name=name)
        setattr(g, key, user)
	return {
	    'key': key
        }

app.add_url_rule('/graphql', view_func=TestQLView.as_view('graphql', schema=schema, graphiql=True, middleware=[dummy_middleware]))

[leebenson]

I tested this with 2.7.15 and 3.7 - here are my query results:

2.7.15:

3.7:

Are you seeing something different, @melancholy ?

[melancholy]

Yes. With concurrent requests I would frequently see errors in the logs. This only occurs when threading is on and requests are concurrent, so a single screenshot of a result won't reflect a proper step for reproduction.

I also ended up tracking this down and working around it. It turns out the promise library isn't thread safe. I mentioned it in an issue for the promise library and described my workarounds.

here's the issue: syrusakbary/promise#57

[jimzer]

Any news on how to access context in resolvers with the ThreadExecutor ?
I keep getting "Working outside of request context" when accessing "info.context" in resolver when I use the ThreadExecutor