python Pool常用函數(shù)用法總結(jié)

#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, ))   #維持執(zhí)行的進(jìn)程總數(shù)為processes，當(dāng)一個(gè)進(jìn)程執(zhí)行完畢后會(huì)添加新的進(jìn)程進(jìn)去
    print("Starting tasks...")
    pool.close()
    pool.join()   #調(diào)用join之前，先調(diào)用close函數(shù)，否則會(huì)出錯(cuò)。執(zhí)行完close后不會(huì)有新的進(jìn)程加入到pool,join函數(shù)等待所有子進(jìn)程結(jié)束
    print("Sub-process(es) done.")

# -*- coding:utf-8 -*-
from multiprocessing import Pool
import os, time, random
def worker(msg):
  t_start = time.time()
  print("%s開始執(zhí)行,進(jìn)程號(hào)為%d" % (msg,os.getpid()))
  # random.random()隨機(jī)生成0~1之間的浮點(diǎn)數(shù)
  time.sleep(random.random()*2) 
  t_stop = time.time()
  print(msg,"執(zhí)行完畢，耗時(shí)%0.2f" % (t_stop-t_start))
po = Pool(3) # 定義一個(gè)進(jìn)程池，最大進(jìn)程數(shù)3
for i in range(0,10):
  # Pool().apply_async(要調(diào)用的目標(biāo),(傳遞給目標(biāo)的參數(shù)元祖,))
  # 每次循環(huán)將會(huì)用空閑出來的子進(jìn)程去調(diào)用目標(biāo)
  po.apply_async(worker,(i,))
print("----start----")
po.close() # 關(guān)閉進(jìn)程池，關(guān)閉后po不再接收新的請(qǐng)求
po.join() # 等待po中所有子進(jìn)程執(zhí)行完成，必須放在close語句之后
print("-----end-----")