Python多线程同步

Posted 2020-11-21 bongem

对Python多线程实现同步机制及其遇到的一些问题。本文给出了样例代码 ，主要包括Condition,Event and Queue三种机制

1. 锁机制

threading的Lock类，用该类的acquire函数进行加锁，用realease函数进行解锁，当一个线程调用锁的acquire()方法获得锁时，锁就进入“locked”状态。每次只有一个线程可以获得锁。如果此时另一个线程试图获得这个锁，该线程就会变为“blocked”状态，称为“同步阻塞”

在此没有给出样例后面条件

 

2.条件 Contidion

代码段：

class Reader(threading.Thread):

    def __init__(self, condition, data):

        threading.Thread.__init__(self)

        self.condition = condition

        self.data = data

        pass

 

    def run(self):

        while True:

            with self.condition:

                print("waiting...")

                self.condition.wait()

                msg = self.data.pop()

                if "exit" == str(msg).lower():

                    print ("exit")

                    break

                print("read date:{}".format(msg))

 

def test_condition():

    condition = threading.Condition()

    dl=[]

 

    reader = Reader(condition, dl)

    reader.daemon = True

    reader.start()

 

    while True:

        with condition:

            msg = input("输入：")

            dl.append(msg)

            print("notify...")

            condition.notifyAll()

            if "exit" == msg.lower():

                break

        time.sleep(0.012)

 

2.事件 Event

代码段：

class Reader2(threading.Thread):

    def __init__(self, event, data):

        threading.Thread.__init__(self)

        self.event = event 

        self.data = data

        pass

    def run(self):

        while True:

            print("waiting...")

            self.event.wait()

            msg = self.data.pop()

            if "exit" == str(msg).lower():

                print ("exit")

                break

            print("read date:{}".format(msg))

def test_event():

    event = threading.Event()

    dl=[]

    reader2 = Reader2(event, dl)

    reader2.daemon = True

    reader2.start()

    while True:

        msg = input("输入：")

        dl.append(msg)

        print("notify...")

        event.set()

        event.clear()

        if "exit" == msg.lower():

            break

        time.sleep(0.012)

    pass

 

2.队列 Queue

代码段：

class Reader3(threading.Thread):

    def __init__(self, queue):

        threading.Thread.__init__(self)

        self.queue = queue

    

    def run(self):

        while True:

            print("waiting...")

            msg = self.queue.get()

            print("read data: {}".format(msg))

            if "exit" == msg.lower():

                break

            self.queue.task_done()

        pass

def test_queue():

    q = queue.Queue()

    reader3 = Reader3(q)

    reader3.daemon = True

    reader3.start()

    while True:

        msg = input("输入：")

        q.put(msg)

        print("notify...")

        time.sleep(0.01)

        if "exit" == msg.lower():

            break

    pass

参考文档：https://zhuanlan.zhihu.com/p/27963810