【爬虫】python 多线程知识

第一段代码：

__author__ = 'Administrator'

import threading
import time

index = 0

class MyThread(threading.Thread):
    def __init__(self, threadname, counter):
        super(MyThread, self).__init__()
        self.threadname = threadname
        self.counter = counter

    def run(self):
        global index
        print "starting " + self.threadname
        while self.counter:
            time.sleep(1)
            index += 1
            print "threadname: %s	index:%d	time: %s
"%(self.threadname, index, time.ctime())
            self.counter -= 1

def main():
    print '=======================BEGIN==========================='
    thread1 = MyThread('thread1', 10)
    thread2 = MyThread('thread2', 5)
    thread1.start()
    thread2.start()

    thread1.join()
    thread2.join()

    print '========================END============================'

if __name__ == '__main__':
    main()

第二段代码：

# -*- coding: gbk -*-
__author__ = 'Administrator'

import threading
import random, time, Queue


# 缓冲队列大小为5
MAX_SIZE = 5
# 模拟队列
SHARE_Q = []
# 条件变量
CONDITION = threading.Condition()


class Producer(threading.Thread):
    def run(self):
        products = range(5)
        global SHARE_Q
        while True:
            # 获得锁
            CONDITION.acquire()
            # 队列如果满了，则等待资源释放
            if len(SHARE_Q) == 5:
                print "Queue is full..."
                CONDITION.wait()
                print "Consumer have consumed something"
            product = random.choice(products)
            SHARE_Q.append(product)
            print "Producer : ", product
            CONDITION.notify()
            CONDITION.release()
            time.sleep(3)


class Consumer(threading.Thread):
    def run(self):
        global SHARE_Q
        while True:
            CONDITION.acquire()
            # 队列为空，消费者不能进行消费
            if not SHARE_Q:
                print "Queue is Empty..."
                CONDITION.wait()
                print "Producer have produced something"
            product = SHARE_Q.pop(0)
            print "Consumer: ", product
            CONDITION.notify()
            CONDITION.release()
            time.sleep(2)


def main():
    producer = Producer()
    consumer = Consumer()
    producer.start()
    consumer.start()


if __name__ == '__main__':
    main()