案例要求参考上一个糗事百科单进程案例
Queue（队列对象）
Queue是python中的标准库，可以直接import Queue引用;队列是线程间最常用的交换数据的形式
python下多线程的思考
对于资源，加锁是个重要的环节。因为python原生的list,dict等，都是not thread safe的。而Queue，是线程安全的，因此在满足使用条件下，建议使用队列
初始化： class Queue.Queue(maxsize) FIFO 先进先出
包中的常用方法:
Queue.qsize() 返回队列的大小
Queue.empty() 如果队列为空，返回True,反之False
Queue.full() 如果队列满了，返回True,反之False
Queue.full 与 maxsize 大小对应
Queue.get([block[, timeout]])获取队列，timeout等待时间
创建一个“队列”对象
import Queue
myqueue = Queue.Queue(maxsize = 10)
将一个值放入队列中
myqueue.put(10)
将一个值从队列中取出
myqueue.get()
多线程示意图
# -*- coding:utf-8 -*-
import requests
from lxml import etree
from Queue import Queue
import threading
import time
import json
class thread_crawl(threading.Thread):
'''
抓取线程类
'''
def __init__(self, threadID, q):
threading.Thread.__init__(self)
self.threadID = threadID
self.q = q
def run(self):
print "Starting " + self.threadID
self.qiushi_spider()
print "Exiting ", self.threadID
def qiushi_spider(self):
# page = 1
while True:
if self.q.empty():
break
else:
page = self.q.get()
print 'qiushi_spider=', self.threadID, ',page=', str(page)
url = 'http://www.qiushibaike.com/8hr/page/' + str(page) + '/'
headers = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.116 Safari/537.36',
'Accept-Language': 'zh-CN,zh;q=0.8'}
# 多次尝试失败结束、防止死循环
timeout = 4
while timeout > 0:
timeout -= 1
try:
content = requests.get(url, headers=headers)
data_queue.put(content.text)
break
except Exception, e:
print 'qiushi_spider', e
if timeout < 0:
print 'timeout', url
class Thread_Parser(threading.Thread):
'''
页面解析类；
'''
def __init__(self, threadID, queue, lock, f):
threading.Thread.__init__(self)
self.threadID = threadID
self.queue = queue
self.lock = lock
self.f = f
def run(self):
print 'starting ', self.threadID
global total, exitFlag_Parser
while not exitFlag_Parser:
try:
'''
调用队列对象的get()方法从队头删除并返回一个项目。可选参数为block，默认为True。
如果队列为空且block为True，get()就使调用线程暂停，直至有项目可用。
如果队列为空且block为False，队列将引发Empty异常。
'''
item = self.queue.get(False)
if not item:
pass
self.parse_data(item)
self.queue.task_done()
print 'Thread_Parser=', self.threadID, ',total=', total
except:
pass
print 'Exiting ', self.threadID
def parse_data(self, item):
'''
解析网页函数
:param item: 网页内容
:return:
'''
global total
try:
html = etree.HTML(item)
result = html.xpath('//div[contains(@id,"qiushi_tag")]')
for site in result:
try:
imgUrl = site.xpath('.//img/@src')[0]
title = site.xpath('.//h2')[0].text
content = site.xpath('.//div[@class="content"]/span')[0].text.strip()
vote = None
comments = None
try:
vote = site.xpath('.//i')[0].text
comments = site.xpath('.//i')[1].text
except:
pass
result = {
'imgUrl': imgUrl,
'title': title,
'content': content,
'vote': vote,
'comments': comments,
}
with self.lock:
# print 'write %s' % json.dumps(result)
self.f.write(json.dumps(result, ensure_ascii=False).encode('utf-8') + "\n")
except Exception, e:
print 'site in result', e
except Exception, e:
print 'parse_data', e
with self.lock:
total += 1
data_queue = Queue()
exitFlag_Parser = False
lock = threading.Lock()
total = 0
def main():
output = open('qiushibaike.json', 'a')
#初始化网页页码page从1-10个页面
pageQueue = Queue(50)
for page in range(1, 11):
pageQueue.put(page)
#初始化采集线程
crawlthreads = []
crawlList = ["crawl-1", "crawl-2", "crawl-3"]
for threadID in crawlList:
thread = thread_crawl(threadID, pageQueue)
thread.start()
crawlthreads.append(thread)
#初始化解析线程parserList
parserthreads = []
parserList = ["parser-1", "parser-2", "parser-3"]
#分别启动parserList
for threadID in parserList:
thread = Thread_Parser(threadID, data_queue, lock, output)
thread.start()
parserthreads.append(thread)
# 等待队列清空
while not pageQueue.empty():
pass
# 等待所有线程完成
for t in crawlthreads:
t.join()
while not data_queue.empty():
pass
# 通知线程是时候退出
global exitFlag_Parser
exitFlag_Parser = True
for t in parserthreads:
t.join()
print "Exiting Main Thread"
with lock:
output.close()
if __name__ == '__main__':
main()
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# 使用了线程库
import threading
# 队列
from Queue import Queue
# 解析库
from lxml import etree
# 请求处理
import requests
# json处理
import json
import time
class ThreadCrawl(threading.Thread):
def __init__(self, threadName, pageQueue, dataQueue):
#threading.Thread.__init__(self)
# 调用父类初始化方法
super(ThreadCrawl, self).__init__()
# 线程名
self.threadName = threadName
# 页码队列
self.pageQueue = pageQueue
# 数据队列
self.dataQueue = dataQueue
# 请求报头
self.headers = {"User-Agent" : "Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0;"}
def run(self):
print "启动 " + self.threadName
while not CRAWL_EXIT:
try:
# 取出一个数字，先进先出
# 可选参数block，默认值为True
#1. 如果对列为空，block为True的话，不会结束，会进入阻塞状态，直到队列有新的数据
#2. 如果队列为空，block为False的话，就弹出一个Queue.empty()异常，
page = self.pageQueue.get(False)
url = "http://www.qiushibaike.com/8hr/page/" + str(page) +"/"
#print url
content = requests.get(url, headers = self.headers).text
time.sleep(1)
self.dataQueue.put(content)
#print len(content)
except:
pass
print "结束 " + self.threadName
class ThreadParse(threading.Thread):
def __init__(self, threadName, dataQueue, filename, lock):
super(ThreadParse, self).__init__()
# 线程名
self.threadName = threadName
# 数据队列
self.dataQueue = dataQueue
# 保存解析后数据的文件名
self.filename = filename
# 锁
self.lock = lock
def run(self):
print "启动" + self.threadName
while not PARSE_EXIT:
try:
html = self.dataQueue.get(False)
self.parse(html)
except:
pass
print "退出" + self.threadName
def parse(self, html):
# 解析为HTML DOM
html = etree.HTML(html)
node_list = html.xpath('//div[contains(@id, "qiushi_tag")]')
for node in node_list:
# xpath返回的列表，这个列表就这一个参数，用索引方式取出来，用户名
username = node.xpath('./div/a/@title')[0]
# 图片连接
image = node.xpath('.//div[@class="thumb"]//@src')#[0]
# 取出标签下的内容,段子内容
content = node.xpath('.//div[@class="content"]/span')[0].text
# 取出标签里包含的内容，点赞
zan = node.xpath('.//i')[0].text
# 评论
comments = node.xpath('.//i')[1].text
items = {
"username" : username,
"image" : image,
"content" : content,
"zan" : zan,
"comments" : comments
}
# with 后面有两个必须执行的操作：__enter__ 和 _exit__
# 不管里面的操作结果如何，都会执行打开、关闭
# 打开锁、处理内容、释放锁
with self.lock:
# 写入存储的解析后的数据
self.filename.write(json.dumps(items, ensure_ascii = False).encode("utf-8") + "\n")
CRAWL_EXIT = False
PARSE_EXIT = False
def main():
# 页码的队列，表示20个页面
pageQueue = Queue(20)
# 放入1~10的数字，先进先出
for i in range(1, 21):
pageQueue.put(i)
# 采集结果(每页的HTML源码)的数据队列，参数为空表示不限制
dataQueue = Queue()
filename = open("duanzi.json", "a")
# 创建锁
lock = threading.Lock()
# 三个采集线程的名字
crawlList = ["采集线程1号", "采集线程2号", "采集线程3号"]
# 存储三个采集线程的列表集合
threadcrawl = []
for threadName in crawlList:
thread = ThreadCrawl(threadName, pageQueue, dataQueue)
thread.start()
threadcrawl.append(thread)
# 三个解析线程的名字
parseList = ["解析线程1号","解析线程2号","解析线程3号"]
# 存储三个解析线程
threadparse = []
for threadName in parseList:
thread = ThreadParse(threadName, dataQueue, filename, lock)
thread.start()
threadparse.append(thread)
# 等待pageQueue队列为空，也就是等待之前的操作执行完毕
while not pageQueue.empty():
pass
# 如果pageQueue为空，采集线程退出循环
global CRAWL_EXIT
CRAWL_EXIT = True
print "pageQueue为空"
for thread in threadcrawl:
thread.join()
print "1"
while not dataQueue.empty():
pass
global PARSE_EXIT
PARSE_EXIT = True
for thread in threadparse:
thread.join()
print "2"
with lock:
# 关闭文件
filename.close()
print "谢谢使用！"
if __name__ == "__main__":
main()
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