线程锁和进程间的通信

模拟死锁  （解死锁两种方法 timeout 超时  互斥锁）   多线程是为了提高效率

多线程中的一个线程卡死，会影响其他线程的运行。

import threading

import time

def work1(num):

#加定时器锁，增加锁超时

lock.acquire(timeout=1)

#time.sleep(1)

lock1.acquire(timeout=1) #要timeout就不需要解锁

# global sum

# for i in range(num):

# sum+=i

# lock1.release()

# lock.release()

 

def work2(num):

lock1.acquire(timeout=1)

#time.sleep(1)

lock.acquire(timeout=1)

# global sum

# for i in range(num):

# sum += i

# lock1.release()

# lock.release()

#建立锁对象，复现死锁

lock=threading.Lock()

lock1=threading.Lock()

 

t1=threading.Thread(target=work1,args=(10000000000,))

t1.start()

 

t2=threading.Thread(target=work2,args=(10000000000,))

t2.start()

 

print(sum)

 

 

进程间的通信 Queue

 

 

#进程池

import multiprocessing

import os,time

def work1(msg):

    print("%s开始,进程号是%s"%(msg,os.getpid()))

    time.sleep(1)

if __name__ == '__main__':

    po=multiprocessing.Pool(2)

    for i in range(5):

    po.apply_async(work1,(i,))

 

    po.close()

    po.join()