submit(fn,*args,**kwargs)　　# 非同步提交任務

map(fn,iterable)　　# 拿不到返回值

shutdown()　　# 相當於pool.close()加pool.join() 操作

result()　　# 取得結果

add_done_callback()　　# 回撥函式

import time
from concurrent.futures import ThreadPoolExecutor

def func(n):
    time.sleep(2)
    print(n)
    return n*n

def callback(m):
    print('結果是%s'%m.result())

tpool = ThreadPoolExecutor(max_workers=5)
t_lst = []
for i in range(20):
    t = tpool(func,i).add_done_callback(callback)
    t_lst.append(t)

tpool.shutdown()
print('主執行緒')
for i in t_lst:
    print('***'+i.result())