Python网络编程（进程通信、信号、线程锁、多线程）

from signal import * 
import time 

def handler(sig,frame):  # 自定义处理信号
    if sig == SIGALRM:  # 判断信号类型
        print("收到时钟信号")
    elif sig == SIGINT:
        print("就不结束 略略略~")

alarm(5)  # 设置5秒时钟信号

signal(SIGALRM,handler)
signal(SIGINT,handler)  #  Ctrl + C

while True:
    print("Waiting for a signal")
    time.sleep(2)

from multiprocessing import Process,Event 
from time import sleep

def wait_event(file):
    print("准备操作临界资源")
    e.wait()  # 等待主进程执行结束后set
    print("开始操作临界资源",e.is_set())
    fw = open(‘1.jpg‘,‘wb‘)
    with open(file,‘rb‘) as f:  # 复制图片
        fw.write(f.read())

def wait_event_timeout(file):
    print("也想操作临界资源")
    e.wait(2)  # 等待主进程执行set并进行2秒超时检测
    if e.is_set():
        print("也开始操作临界资源")
        fw = open(‘2.jpg‘,‘wb‘)
        with open(file,‘rb‘) as f:  # 复制图片
            fw.write(f.read())
    else:
        print("等不了了，不等了")
# 创建事件
e = Event()
path = "/home/tarena/file.jpg"
file = ‘file.jpg‘

# 创建两个进程分别复制两个图片
p1 = Process(target = wait_event,args = (file,))
p2 = Process(target = wait_event_timeout,args = (file,))

p1.start()
p2.start()

# 主进程先复制图片 让子进程进入wait状态
print("主进程在操作临界资源")
sleep(3)
fw = open(file,‘wb‘)
with open(path,‘rb‘) as f:
    fw.write(f.read())
fw.close()
e.set()  # 子进程set
print("主进程操作完毕")


p1.join()
p2.join()

from  multiprocessing import Process,Lock 
import sys 
from time import sleep 

#sys.stdout作为标准输出流是多个进程共有的资源

def writer1():
    lock.acquire()  #上锁
    for i in range(5):
        sleep(1)
        sys.stdout.write("writer1输出\n")
    lock.release() #解锁
# 虽然都sleep1秒但是 若不加锁会每1秒打印两次
# 由于上锁原因 w1执行完临界区w2才能被执行 一秒一次
def writer2():
    with lock:
        for i in range(5):
            sleep(1)
            sys.stdout.write("writer2输出\n")

#创建锁
lock = Lock()

w1 = Process(target = writer1)
w2 = Process(target = writer2)

w1.start()
w2.start()

w1.join()
w2.join()

from threading import Thread 
from time import sleep, ctime

# 创建一个MyThread类继承Thread
class MyThread(Thread):
    def __init__(self, target, name = "Tedu", args = (), kwargs = {}):
        super().__init__()  # 重新加载父类的__init__初始化方法
        self.target = target 
        self.name = name
        self.args = args
        self.kwargs = kwargs

    def run(self):  # 在创建对象时自动调用run方法
# 在调用run时调分支线程要执行的线程函数  以*元组和**字典的方式接收万能传参
        self.target(*self.args, **self.kwargs)


#线程函数
def player(song,sec):
    for i in range(2):
        print("Playing %s : %s"%(song, ctime()))
        sleep(sec)

# 用自定义类创建线程并执行
t = MyThread(target = player, args = ("卡路里", 3))
t.start()
t.join()