【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\tindex:%d\ttime: %s\n"%(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()