python Pool常用的函数有哪些

#coding: utf-8
import multiprocessing
import time
 
 
def func(msg):
    print("msg:", msg)
    time.sleep(3)
    print("end")
 
 
if __name__ == "__main__":
    cores = multiprocessing.cpu_count()
    pool = multiprocessing.Pool(processes=cores)
    print("Adding tasks...")
    for i in range(cores):
        msg = "hello %d" %(i)
        pool.apply_async(func, (msg, ))   #维持执行的进程总数为processes，当一个进程执行完毕后会添加新的进程进去
    print("Starting tasks...")
    pool.close()
    pool.join()   #调用join之前，先调用close函数，否则会出错。执行完close后不会有新的进程加入到pool,join函数等待所有子进程结束
    print("Sub-process(es) done.")