MongoDB Motor Deadlock

motor_deadlock.py

import json
import random

import motor
from tornado import gen, ioloop, web

@gen.coroutine
def get_data():
    cur1 = _client.test.testcol1.find()
    cur2 = _client.test.testcol2.find()
        
    data1, data2 = yield [cur1.to_list(length=None), cur2.to_list(length=None)]
    
    raise gen.Return((data1, data2))

class MainHandler(web.RequestHandler):
    @gen.coroutine
    def get(self):
        #If I run the code directly in this method this it works fine
#         cur1 = _client.test.testcol1.find()
#         cur2 = _client.test.testcol2.find()
#         
#         data1, data2 = yield [cur1.to_list(length=None), cur2.to_list(length=None)]

        yield get_data()
        
        self.write("done")
        
class InsertHandler(web.RequestHandler):
    @gen.coroutine
    def get(self):
        for _ in range(1000):
            docs = []
            
            for _ in range(1000):
                docs.append({"v": random.random(), "t": random.randint(0, 2**31-1)})
                
            yield _client.test.testcol1.insert(docs)
            yield _client.test.testcol2.insert(docs)
        
        self.write("done")

if __name__ == "__main__":
    #http://code.activestate.com/recipes/577334-how-to-debug-deadlocked-multi-threaded-programs/
    import stacktracer
    stacktracer.trace_start("trace.html")
    
    settings = {
                "debug": True,
                "autoreload": True
                }
    
    with open("credentials.json") as f:
        creds = json.load(f)
    
    _client = motor.MotorReplicaSetClient(creds["mongodb_uri"])
    
    application = web.Application([(r"/", MainHandler),
                                   (r"/doinsert", InsertHandler)],
                                  **settings)
    application.listen(8888)
    ioloop.IOLoop.instance().start()