我用Python自帶的Multi-processing模塊做了一個并發(fā)的Async的系統(tǒng)。只有2個任務，一快一慢，并發(fā)執(zhí)行，快的等慢的。

import sys, os, time, datetime
from timeit import timeit
import threading
import multiprocessing
from multiprocessing import Pool

def multiprocessor_hack(instance, name, args=(), kwargs=None):
    if kwargs is None:
        kwargs = {}
    return getattr(instance, name)(*args, **kwargs)

class Controller:
    request = "Whatever"
    def task1(self, request):
        print ("Now starting task1 at {}.\n".format(datetime.datetime.now()))
        time.sleep(3)
        print ("Now finished task1 at {}.\n".format(datetime.datetime.now()))
        return "111111"
    def task2(self, request):
        print ("Now starting task2 at {}.\n".format(datetime.datetime.now()))
        time.sleep(10)
        print ("Now finished task2 at {}.\n".format(datetime.datetime.now()))
        return "222222"

    def moderate(self, request):
        pool = multiprocessing.Pool(processes = 2)
        results = [pool.apply_async(multiprocessor_hack, args = (self, task1', (request,))), pool.apply_async(multiprocessor_hack, args = (self, 'task2', (request,)))]
        pool.close()
        map (multiprocessing.pool.ApplyResult.wait, results)
        response = [r.get() for r in results]
        return response


if "__main__" == __name__:
    ctrl = Controller()
    print ("\nThe pool starts at {}.\n".format(datetime.datetime.now()))
    response = ctrl.moderate("Whatever")
    print ("\nResponse emerges at {}.".format(datetime.datetime.now()))
    print ("\nThe pool ends at {}.".format(datetime.datetime.now()))

運行結果是：

The pool starts at 2018-03-23 15:03:51.187000.
Now starting task1 at 2018-03-23 15:03:51.522000.  # 延遲？
Now starting task2 at 2018-03-23 15:03:51.522000.  # 延遲？
Now finished the task1 at 2018-03-23 15:03:54.524000.
Now finished the task2 at 2018-03-23 15:04:01.524000.
Response emerges at 2018-03-23 15:04:01.526000.
The pool ends at 2018-03-23 15:04:01.528000.

這里，pool在下午三點 15:03:51.187 開始運行，但是2個任務直到 15:03:51.522 才開始執(zhí)行！… 請問這里為什么會延遲0.4秒呢？有沒有什么辦法減小這個延遲？

謝謝了先！