python之系统编程 --线程

###########使用线程完成多任务################

from threading import Thread
import time

#1. 如果多个线程执行的都是同一个函数的话，各自之间不会有影响，各是个的
def test():
    print("----昨晚喝多了，下次少喝点---")
    time.sleep(1)

for i in range(5):
    t = Thread(target=test)
    t.start()

#############使用类的方式创建线程完成任务###########

import threading
import time

class MyThread(threading.Thread):
    def run(self):
        for i in range(3):
            time.sleep(1)
            msg = "I'm "+self.name+' @ '+str(i) #name属性中保存的是当前线程的名字
            print(msg)

if __name__ == '__main__':
    t = MyThread()
    t.start()

执行结果：

[root@master process]# python3 09-thread.py
I'm Thread-1 @ 0
I'm Thread-1 @ 1
I'm Thread-1 @ 2

###############线程之间共享全局变量#########

from threading import Thread
import time

#线程之间共享全局变量
g_num = 100

def work1():
    global g_num
    for i in range(3):
        g_num += 1

    print("----in work1, g_num is %d---"%g_num)

def work2():
    global g_num
    print("----in work2, g_num is %d---"%g_num)

print("---线程创建之前g_num is %d---"%g_num)

t1 = Thread(target=work1)
t1.start()

#延时一会，保证t1线程中的事情做完
time.sleep(1)

t2 = Thread(target=work2)
t2.start()

############线程之间共享全局变量带来的问题############

from threading import Thread
import time

g_num = 0

def test1():
    global g_num
    for i in range(1000000):
        g_num += 1

    print("---test1---g_num=%d"%g_num)

def test2():
    global g_num
    for i in range(1000000):
        g_num += 1

    print("---test2---g_num=%d"%g_num)

p1 = Thread(target=test1)
p1.start()

#time.sleep(3) #取消屏蔽之后 再次运行程序，结果会不一样，，，为啥呢？

p2 = Thread(target=test2)
p2.start()

print("---g_num=%d---"%g_num)

############把列表当做参数传递给线程############

from threading import Thread
import time

def work1(nums):
    nums.append(44)
    print("----in work1---",nums)

def work2(nums):
    #延时一会，保证t1线程中的事情做完
    time.sleep(1)
    print("----in work2---",nums)

g_nums = [11,22,33]

t1 = Thread(target=work1, args=(g_nums,))
t1.start()

t2 = Thread(target=work2, args=(g_nums,))
t2.start()

###############避免多线程对共享数据出错的方式###########

from threading import Thread
import time

g_num = 0
g_flag = 1

def test1():
    global g_num
    global g_flag
    if g_flag == 1:
        for i in range(1000000):
            g_num += 1

        g_flag = 0

    print("---test1---g_num=%d"%g_num)

def test2():
    global g_num
    #轮询
    while True:
        if g_flag != 1:
            for i in range(1000000):
                g_num += 1
            break

    print("---test2---g_num=%d"%g_num)

p1 = Thread(target=test1)
p1.start()

#time.sleep(3) #取消屏蔽之后 再次运行程序，结果会不一样，，，为啥呢？

p2 = Thread(target=test2)
p2.start()

print("---g_num=%d---"%g_num)

##############使用互斥锁解决共享数据出错问题##################

代码例子：

from threading import Thread, Lock
import time

g_num = 0

def test1():
    global g_num
    #这个线程和ｔｅｓｔ2线程都在抢着　对这个锁　进行上锁，如果有１方成功的上锁，那么导致另外
    #一方会堵塞（一直等待）到这个锁被解开为止
    mutex.acquire()
    for i in range(1000000):
        g_num += 1
    mutex.release()#用来对mutex指向的这个锁　进行解锁，，，只要开了锁，那么接下来会让所有因为
                    #这个锁　被上了锁　而堵塞的线程　进行抢着上锁

    print("---test1---g_num=%d"%g_num)

def test2():
    global g_num
    mutex.acquire()
    for i in range(1000000):
        g_num += 1
    mutex.release()

    print("---test2---g_num=%d"%g_num)

#创建一把互斥锁，这个锁默认是没有上锁的
mutex = Lock()

p1 = Thread(target=test1)
p1.start()

#time.sleep(3) #取消屏蔽之后 再次运行程序，结果会不一样，，，为啥呢？

p2 = Thread(target=test2)
p2.start()

print("---g_num=%d---"%g_num)

#############多线程使用非共享变量################

from threading import Thread
import threading
import time

def test1():
    #注意：
    #   1. 全局变量在多个线程中　共享，为了保证正确运行需要锁
    #   2. 非全局变量在每个线程中　各有一份，不会共享，当然了不需要加锁
    name = threading.current_thread().name
    print("----thread name is %s ----"%name)
    g_num = 100
    if name == "Thread-1":
        g_num += 1
    else:
        time.sleep(2)
    print("--thread is %s----g_num=%d"%(name,g_num))

#def test2():
#    time.sleep(1)
#    g_num = 100
#    print("---test2---g_num=%d"%g_num)

p1 = Thread(target=test1)
p1.start()

p2 = Thread(target=test1)
p2.start()

执行结果：

###################同步#################

同步的应用：

from threading import Thread,Lock
from time import sleep

class Task1(Thread):
    def run(self):
        while True:
            if lock1.acquire():
                print("------Task 1 -----")
                sleep(0.5)
                lock2.release()

class Task2(Thread):
    def run(self):
        while True:
            if lock2.acquire():
                print("------Task 2 -----")
                sleep(0.5)
                lock3.release()

class Task3(Thread):
    def run(self):
        while True:
            if lock3.acquire():
                print("------Task 3 -----")
                sleep(0.5)
                lock1.release()

#使用Lock创建出的锁默认没有“锁上”
lock1 = Lock()
#创建另外一把锁，并且“锁上”
lock2 = Lock()
lock2.acquire()
#创建另外一把锁，并且“锁上”
lock3 = Lock()
lock3.acquire()

t1 = Task1()
t2 = Task2()
t3 = Task3()

t1.start()
t2.start()
t3.start()

############生产者与消费者##########

#encoding=utf-8
import threading
import time

#python2中
#from Queue import Queue

#python3中
from queue import Queue

class Producer(threading.Thread):
    def run(self):
        global queue
        count = 0
        while True:
            if queue.qsize() < 1000:
                for i in range(100):
                    count = count +1
                    msg = '生成产品'+str(count)
                    queue.put(msg)
                    print(msg)
            time.sleep(0.5)

class Consumer(threading.Thread):
    def run(self):
        global queue
        while True:
            if queue.qsize() > 100:
                for i in range(3):
                    msg = self.name + '消费了 '+queue.get()
                    print(msg)
            time.sleep(1)

if __name__ == '__main__':
    queue = Queue()

    for i in range(500):
        queue.put('初始产品'+str(i))
    for i in range(2):
        p = Producer()
        p.start()
    for i in range(5):
        c = Consumer()
        c.start()

#########TheadLocal###############

Theadlocal的作用：不用传参数，用一个全局变量能够完成线程里面所有的数据传递，不会因为下一个线程调用该变量而改变该值
import threading

# 创建全局ThreadLocal对象:
local_school = threading.local()

def process_student():
    # 获取当前线程关联的student:
    std = local_school.student
    print('Hello, %s (in %s)' % (std, threading.current_thread().name))

def process_thread(name):
    # 绑定ThreadLocal的student:
    local_school.student = name
    process_student()

t1 = threading.Thread(target= process_thread, args=('dongGe',), name='Thread-A')
t2 = threading.Thread(target= process_thread, args=('老王',), name='Thread-B')
t1.start()
t2.start()

############异步的实现######################

from multiprocessing import Pool
import time
import os

def test():
    print("---进程池中的进程---pid=%d,ppid=%d--"%(os.getpid(),os.getppid()))
    for i in range(3):
        print("----%d---"%i)
        time.sleep(1)
    return "hahah"

def test2(args):
    print("---callback func--pid=%d"%os.getpid())
    print("---callback func--args=%s"%args)

pool = Pool(3)
pool.apply_async(func=test,callback=test2)

#异步的理解：主进程正在做某件事情，突然　来了一件更需要立刻去做的事情，
#那么这种，在父进程去做某件事情的时候　并不知道是什么时候去做，的模式　就称为异步
while True:
    time.sleep(1)
    print("----主进程-pid=%d----"%os.getpid())