Python网络编程（进程池、进程间的通信）

import os from multiprocessing import Process from time import sleep #获取文件的大小 size = os.path.getsize("./timg.jpeg") # 获取文件的字节数 # f = open("timg.jpeg",'rb') #复制前半部分 def copy1(img): f = open(img,'rb') # 二进制读取要复制的文件 n = size // 2 fw = open('1.jpeg','wb') # 二进制创建文件 while True: if n < 1024: # 判断文件大小是否大于1024字节 如果小于则直接读取写入 data = f.read(n) fw.write(data) break data = f.read(1024) # 否则每次循环读取1024字节并写入 fw.write(data) n -= 1024 f.close() fw.close() #复制后半部分 def copy2(img): f = open(img,'rb') # 读取文件必须要每次读取 如果在父进程中打开文件流对像 # 子进程会通同时调用一个文件流对像 由于文件流对象特性会记录游标 # 如若先执行后半部复制这前半部会导致读取不到数据 fw = open('2.jpeg','wb') f.seek(size // 2,0) while True: data = f.read(1024) if not data: break fw.write(data) fw.close() f.close() p1 = Process(target = copy1,args = ('timg.jpeg',)) # 创建子进程并让子进程分别同时复制 p2 = Process(target = copy2,args = ('timg.jpeg',)) p1.start() p2.start() p1.join() p2.join() 

from multiprocessing import Process import time class ClockProcess(Process): def __init__(self,value): #调用父类init super().__init__() self.value = value #重写run方法 def run(self): for i in range(5): time.sleep(self.value) print("The time is {}".format(time.ctime())) p = ClockProcess(2) #自动执行run p.start() p.join() 

from multiprocessing import Pool from time import sleep,ctime def worker(msg): sleep(2) print(msg) return ctime() #创建进程池对象 pool = Pool(processes = 4) result = [] for i in range(10): msg = "hello %d"%i #将事件放入进程池 r = pool.apply_async(func = worker,args = (msg,)) result.append(r) #同步执行 # pool.apply(func = worker,args = (msg,)) #关闭进程池 pool.close() #回收 pool.join() #获取事件函数返回值 for i in result: print(i.get()) 

from multiprocessing import Pool import time def fun(n): time.sleep(1) print("执行 pool map事件",n) return n ** 2 pool = Pool(4) #在进程池放入6个事件 r = pool.map(fun,range(6)) # map高阶函数 fun和iter执行6次 print("返回值列表:",r) pool.close() pool.join()

from multiprocessing import Process,Value import time import random #创建共享内存 money = Value('i',6000) #存钱 def deposite(): for i in range(100): time.sleep(0.05) #对value的修改就是对共享内存的修改 money.value += random.randint(1,200) #花销 def withdraw(): for i in range(100): time.sleep(0.04) #对value的修改就是对共享内存的修改 money.value -= random.randint(1,200) d = Process(target = deposite) w = Process(target = withdraw) d.start() w.start() d.join() w.join() print(money.value)

from multiprocessing import Process,Array import time #创建共享内存 shm = Array('c',b"hello") #字符类型要求是bytes #开辟5个整形单元的共享内存空间 # shm = Array('i',5) def fun(): for i in shm: print(i) shm[0] = b"H" p = Process(target = fun) p.start() p.join() print(shm.value) #从首地址打印字符串 # for i in shm: # print(i)