Is it possible to run multiple asyncio in the same time in python?

问题

Based on the solution that i got: Running multiple sockets using asyncio in python

i tried to add also the computation part using asyncio

Setup: Python 3.7.4

import msgpack
import threading
import os
import asyncio
import concurrent.futures
import functools
import nest_asyncio
nest_asyncio.apply()

class ThreadSafeElem(bytes):
  def __init__(self, * p_arg, ** n_arg):
     self._lock = threading.Lock()
  def __enter__(self):
     self._lock.acquire()
     return self
  def __exit__(self, type, value, traceback):
     self._lock.release()

elem = ThreadSafeElem()

async def serialize(data):
   return msgpack.packb(data, use_bin_type=True)
async def serialize1(data1):
   return msgpack.packb(data1, use_bin_type=True)

async def process_data(data,data1):
   loop = asyncio.get_event_loop()
   future = await loop.run_in_executor(None, functools.partial(serialize, data))
   future1 = await loop.run_in_executor(None, functools.partial(serialize1, data1))
   return   await asyncio.gather(future,future1)

 ################ Calculation#############################
def calculate_data():
  global elem
  while True:
      try:
          ... data is calculated (some dictionary))...
          elem, elem1= asyncio.run(process_data(data, data1))
      except:
          pass
#####################################################################
def get_data():
  return elem
def get_data1():
  return elem1
########### START SERVER AND get data contionusly ################
async def client_thread(reader, writer):
  while True:
    try:
        bytes_received = await reader.read(100) 
        package_type = np.frombuffer(bytes_received, dtype=np.int8)
        if package_type ==1 :
           nn_output = get_data1()
        if package_type ==2 :
           nn_output = get_data()               
        writer.write(nn_output)
        await writer.drain()
    except:
        pass

async def start_servers(host, port):
  server = await asyncio.start_server(client_thread, host, port)
  await server.serve_forever()

async def start_calculate():
  await asyncio.run(calculate_data())

def enable_sockets():
 try:
    host = '127.0.0.1'
    port = 60000
    sockets_number = 6
    loop = asyncio.get_event_loop()
    for i in range(sockets_number):
        loop.create_task(start_servers(host,port+i))
    loop.create_task(start_calculate())
    loop.run_forever()
except:
    print("weird exceptions")
##############################################################################

enable_sockets()   

The issue is that when i make a call from client, the server does not give me anything.

I tested the program with dummy data and no asyncio on calculation part so without this loop.create_task(start_calculate()) and the server responded correctly.

I also run the calculate data without adding it in the enable sockets and it worked. It also working with this implementation, but the problem is the server is not returning anything.

I did it like this cos i need the calculate part to run continuously and when one of the clients is calling to return the data at that point.

回答1:

An asyncio event loop cannot be nested inside another, and there is no point in doing so: asyncio.run (and similar) blocks the current thread until done. This does not increase parallelism, and merely disables any outer event loop.

If you want to nest another asyncio task, directly run it in the current event loop. If you want to run a non-cooperative, blocking task, run it in the event loop executor.

async def start_calculate():
    loop = asyncio.get_running_loop()
    await loop.run_in_executor(None, calculate_data)

The default executor uses threads – this allows running blocking tasks, but does not increase parallelism. Use a custom ProcessPoolExecutor to use additional cores:

import concurrent.futures

async def start_calculate():
    loop = asyncio.get_running_loop()
    with concurrent.futures.ProcessPoolExecutor() as pool:
        await loop.run_in_executor(pool, calculate_data)

回答2:

Why do you call asyncio.run() multiple times?

This function always creates a new event loop and closes it at the end. It should be used as a main entry point for asyncio programs, and should ideally >only be called once.

I would advise you to read the docs

来源：https://stackoverflow.com/questions/62703083/is-it-possible-to-run-multiple-asyncio-in-the-same-time-in-python