9.2 线程同步 --- python    作者:xieaotian发表于2009-06-05 16:53:59

	   

	   9.2.1 简单的线程同步



# -*- coding:utf-8 -*-

# file: syn.py

#

import threading

import time

class mythread(threading.Thread):                            #通过继承创建类

   def __init__(self, threadname):                           #初始化方法

      threading.Thread.__init__(self, name = threadname)     #调用父类的初始化方法

   def run(self):                                            #重载run

      global x

      lock.acquire()                                        #调用lock的acquire方法

      for i in range(3):

         x = x + 1

      time.sleep(2)                                         #调用sleep函数，让线程休眠2s

      print x

      lock.release()                                        #调用lock的release方法

lock = threading.RLock()                                    #生成RLock对象

tl = []

for i in range(10):

   t = mythread(str(i))                                      #类实例化

   tl.append(t)                                              #将类对象添加到列表中



x=0

for i in tl:

   i.start()                                                 #依次运行线程



1）有LOCK的时候   



>>> 3

6

9

12

15

18

21

24

27

30

>>> 30303030303030303030        #删除掉LOCK



>>> 3                                             #删除掉LOCK 和sleep(2)

6

9

12

15

18

21

24

27

30



9.2.2 使用条件变量保持线程同步



# -*- coding:utf-8 -*-

#file: P_C.py

#

import threading

class Producer(threading.Thread):

    def __init__(self,threadname):

        threading.Thread.__init__(self, name = threadname)

    def run(self):

        global x

        print 'Producer'

        con.acquire()

        if x == 1000000:

            print "Producer con.wait()"

            con.wait()

            pass

        else:

            for i in range(1000000):

                x = x + 1

            print "Producer con.notify()"

            con.notify()

        print x

        con.release()

class Consumer(threading.Thread):

    def __init__(self, threadname):

        threading.Thread.__init__(self, name = threadname)

    def run(self):

        global x

        print 'Consumer'

        con.acquire()

        if x == 0:

            print "Consumer con.wait()"

            con.wait()

            pass

        else:

            for i in range(1000000):

                x = x - 1

            print "Consumer con.notify()"

            con.notify()

        print x

        con.release()

con = threading.Condition()

x = 0

p = Producer('Producer')

c = Consumer('Consumer')

#c.start()

p.start()

c.start()

#c.join()

p.join()

c.join()

print x



1）先c.start()



c.start()

p.start()

c.join()

p.join()



2）先p.start()

p.start()

c.start()

p.join()

c.join()



>>> Consumer

Consumer con.wait()

Producer

Producer con.notify()

1000000

1000000

1000000

>>> Producer

Consumer

Producer con.notify()

1000000

Consumer con.notify()

0

0