zuoye

Posted 2021-01-29 huweitao

from threading  import  Thread
from threading  import Lock
lock = Lock ()
def pl():
    lock.acquire()
    with open(‘jkl‘,mode= ‘r+‘) as ff:

        k = ff.read()

        k = int(k)
        k += 1
        print(‘zhege%s‘%k)
        pp = str(k)
    with open(‘jkl‘,mode = ‘r+‘) as ff:
        ff.write(pp)
    lock.release()
list2 = []
if __name__ == ‘__main__‘:
    for i in range(20):
        obj = Thread (target= pl)
        list2.append(obj)
    for i in list2:
        i.start()

1.创建一个文件，文件的第一行写入0，再创建20个任务线程，他们同时打开文件并将文件第一行读出来，加1写回去（将文件原有值覆盖掉）请保证20个任务线程完成后，文件中的第一行一定是20！

from threading  import  Thread
from threading  import Lock


def issushu(i):
    for j in range(2,i):
        if i % j == 0:
            return False
    else:
        return True

def worker(aa):
    while True :
        try:
            x = next(aa)
        except :
            break
        else:
            if issushu(x):
                print(x)

num = iter(range(100,301))
lista = []
for i in range(4):
    t = Thread (target= worker,args = (num,))
    lista.append(t)

for t in lista:
    t.start()

for t in lista :
    t.join()

yield 是生成器关键字，能有效节省系统空间。

def fun():
for i in range(20):
    x=yield i
    print(‘good‘,x)

if __name__ == ‘__main__‘:
a=fun()
a.__next__()
x=a.send(5)
print(x)