多任务-线程

1. 线程是最小的执行单位。

2. 线程间共享全局变量。

3. 线程间存在资源竞争（全局变量）的问题。

import time
import threading


def sing():
    """唱歌 5秒钟"""
    for i in range(5):
        print("----正在唱:菊花茶----")
        time.sleep(1)


def dance():
    """跳舞 5秒钟"""
    for i in range(5):
        print("----正在跳舞----")
        time.sleep(1)


def main():
    t1 = threading.Thread(target=sing)
    t2 = threading.Thread(target=dance)
    t1.start()
    t2.start()


if __name__ == "__main__":
    main()

import time
import threading


def sing():
    """唱歌 5秒钟"""
    for i in range(5):
        print("----正在唱:菊花茶----")
        time.sleep(1)


def dance():
    """跳舞 5秒钟"""
    for i in range(5):
        print("----正在跳舞----")
        time.sleep(1)


def main():
    t1 = threading.Thread(target=sing)
    t2 = threading.Thread(target=dance)
    t1.start()
    t2.start()


if __name__ == "__main__":
    main()

import threading
import time


def test1():
    for i in range(5):
        print("-----test1---%d---" % i)
        time.sleep(1)

    # 如果创建Thread时执行的函数，运行结束那么意味着 这个子线程结束了....


def test2():
    for i in range(10):
        print("-----test2---%d---" % i)
        time.sleep(1)


def main():
    t1 = threading.Thread(target=test1)
    t2 = threading.Thread(target=test2)

    t1.start()
    t2.start()

    while True:
        # 查看运行的线程数
        print(threading.enumerate())
        if len(threading.enumerate())<=1:
            break
        time.sleep(1)


if __name__ == "__main__":
    main()

import threading
import time

# 定义一个全局变量
g_num = 0


def test1(num):
    global g_num
    for i in range(num):
        g_num += 1
    print("-----in test1 g_num=%d----" % g_num)


def test2(num):
    global g_num
    for i in range(num):
        g_num += 1
    print("-----in test2 g_num=%d=----" % g_num)


def main():
    # target指定将来 这个线程去哪个函数执行代码
    # args指定将来调用 函数的时候 
    t1 = threading.Thread(target=test1, args=(1000000,))
    t2 = threading.Thread(target=test2, args=(1000000,))

    t1.start()
    t2.start()

    # 等待上面的2个线程执行完毕....
    time.sleep(5)

    print("-----in main Thread g_num = %d---" % g_num)

if __name__ == "__main__":
    main()

import threading
import time

# 定义一个全局变量
g_num = 0


def test1(num):
    global g_num
    # 上锁的区域越小越好
    for i in range(num):
        mutex.acquire()  # 上锁
        g_num += 1
        mutex.release()  # 解锁
    print("-----in test1 g_num=%d----" % g_num)


def test2(num):
    global g_num
    for i in range(num):
        mutex.acquire()  # 上锁
        g_num += 1
        mutex.release()  # 解锁
    print("-----in test2 g_num=%d=----" % g_num)


# 创建一个互斥锁，默认是没有上锁的
mutex = threading.Lock()


def main():
    t1 = threading.Thread(target=test1, args=(1000000,))
    t2 = threading.Thread(target=test2, args=(1000000,))

    t1.start()
    t2.start()

    # 等待上面的2个线程执行完毕....
    time.sleep(2)

    print("-----in main Thread g_num = %d---" % g_num)

if __name__ == "__main__":
    main()

import socket
import threading


def recv_msg(udp_socket):
    """接收数据并显示"""

    # 接收数据
    while True:
        recv_data = udp_socket.recvfrom(1024)
        print(recv_data)


def send_msg(udp_socket, dest_ip, dest_port):
    """发送数据"""
    # 发送数据
    while True:
        send_data = input("输入要发送的数据:")
        udp_socket.sendto(send_data.encode("utf-8"), (dest_ip, dest_port))


def main():
    """完成udp聊天器的整体控制"""

    # 1. 创建套接字
    udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

    # 2. 绑定本地信息
    udp_socket.bind(("", 7890))

    # 3. 获取对方的ip
    dest_ip = input("请输入对方的ip:")
    dest_port = int(input("请输入对方的port:"))

    # 4. 创建2个线程，去执行相应的功能
    t_recv = threading.Thread(target=recv_msg, args=(udp_socket,))
    t_send = threading.Thread(target=send_msg, args=(udp_socket, dest_ip, dest_port))

    t_recv.start()
    t_send.start()


if __name__ == "__main__":
    main()

import threading
import time

# 定义一个全局变量
g_num = 0


def test1(num):
    global g_num
    # 上锁，如果之前没有被上锁，那么此时 上锁成功
    # 如果上锁之前 已经被上锁了（创建的互斥锁被上锁了），那么此时会堵塞在这里，直到 这个锁被解开位置
    mutex.acquire()
    for i in range(num):
        g_num += 1
    # 解锁
    mutex.release()
    print("-----in test1 g_num=%d----" % g_num)


def test2(num):
    global g_num
    mutex.acquire()
    for i in range(num):
        g_num += 1
    mutex.release()
    print("-----in test2 g_num=%d=----" % g_num)


# 创建一个互斥锁，默认是没有上锁的
mutex = threading.Lock()


def main():
    t1 = threading.Thread(target=test1, args=(1000000,))
    t2 = threading.Thread(target=test2, args=(1000000,))

    t1.start()
    t2.start()

    # 等待上面的2个线程执行完毕....
    time.sleep(2)

    print("-----in main Thread g_num = %d---" % g_num)

if __name__ == "__main__":
    main()