Python多线程错误

源代码

# coding=utf-8
'''
Created on 2017年8月16日
@author: Lihhz
'''
from spider.url_manager import UrlManager
from spider.html_downloader import HtmlDownloader
from spider.html_parser import HtmlParser
import logging
import thread
logging.basicConfig(level=logging.DEBUG,
                format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s',
                datefmt='%a, %d %b %Y %H:%M:%S',
                filename='myapp.log',
                filemode='w')
urlManager = UrlManager();
htmlDownloader = HtmlDownloader('d:/test1')
htmlParser = HtmlParser()
url = 'http://image.baidu.com/search/flip?tn=baiduimage&ie=utf-8&word=周杰伦&pn=%s&gsm=&ct=&ic=0&lm=-1&width=0&height=0'
class Main(object):

    def __init__(self,rootUrl):
        self.rootUrl = rootUrl

    def download(self,u):
        htmlContent = htmlDownloader.downloadHtml(u)
        imageUrls = htmlParser.parseHtml('',htmlContent)
        htmlDownloader.downloadImage(imageUrls)

    def craw(self):
        for i in range(0,100):#[::-1]:
            u = url % (i*20)
            logging.info('======%s' % (u))
            thread.start_new_thread(self.download, (u,))
if __name__ == '__main__':
    main = Main('http://image.baidu.com/search/flip?tn=baiduimage&ie=utf-8&word=周杰伦&pn=0&gsm=50&ct=&ic=0&lm=-1&width=0&height=0')
    main.craw()

错误信息

pydev debugger: starting (pid: 10112)
Traceback (most recent call last):
Traceback (most recent call last):
Traceback (most recent call last):
  File "_pydevd_bundlepydevd_cython_win32_27_32.pyx", line 918, in _pydevd_bundle.pydevd_cython_win32_27_32.ThreadTracer.__call__ (_pydevd_bundle/pydevd_cython_win32_27_32.c:15143)
Traceback (most recent call last):
  File "_pydevd_bundlepydevd_cython_win32_27_32.pyx", line 918, in _pydevd_bundle.pydevd_cython_win32_27_32.ThreadTracer.__call__ (_pydevd_bundle/pydevd_cython_win32_27_32.c:15143)
  File "_pydevd_bundlepydevd_cython_win32_27_32.pyx", line 918, in _pydevd_bundle.pydevd_cython_win32_27_32.ThreadTracer.__call__ (_pydevd_bundle/pydevd_cython_win32_27_32.c:15143)
  File "_pydevd_bundlepydevd_cython_win32_27_32.pyx", line 918, in _pydevd_bundle.pydevd_cython_win32_27_32.ThreadTracer.__call__ (_pydevd_bundle/pydevd_cython_win32_27_32.c:15143)
Unhandled exception in thread started by 
sys.excepthook is missing
lost sys.stderr
Unhandled exception in thread started by 
sys.excepthook is missing
lost sys.stderr
Unhandled exception in thread started by 
sys.excepthook is missing
lost sys.stderr

原因分析

• 在craw中,thread.start_new_thread开启了若干个子线程,然而子线程尚未结束,main线程就结束了.导致main线程提前退出

解决办法

• 为每个子线程加锁.在main线程中判断每一个子线程是否结束,若全部结束则退出,否则不退出

# coding=utf-8
'''
Created on 2017年8月16日
@author: Lihhz
'''
from spider.url_manager import UrlManager
from spider.html_downloader import HtmlDownloader
from spider.html_parser import HtmlParser
import logging
import thread
logging.basicConfig(level=logging.DEBUG,
                format='%(asctime)s %(filename)s[line:%(lineno)d] %(levelname)s %(message)s',
                datefmt='%a, %d %b %Y %H:%M:%S',
                filename='myapp.log',
                filemode='w')
urlManager = UrlManager();
htmlDownloader = HtmlDownloader('d:/test1')
htmlParser = HtmlParser()
url = 'http://image.baidu.com/search/flip?tn=baiduimage&ie=utf-8&word=周杰伦&pn=%s&gsm=&ct=&ic=0&lm=-1&width=0&height=0'
class Main(object):

    def __init__(self,rootUrl):
        self.rootUrl = rootUrl

    def download(self,u,lock):
        htmlContent = htmlDownloader.downloadHtml(u)
        imageUrls = htmlParser.parseHtml('',htmlContent)
#                     urlManager.add_new_urls(notImageUrls)
        htmlDownloader.downloadImage(imageUrls)
        lock.release()#在子线程中释放锁

    def craw(self):
        locks = [];
        for i in range(0,100):#[::-1]:
            u = url % (i*20)
            logging.info('======%s' % (u))
            # 设计子线程的锁
            lock = thread.allocate_lock() # 分配锁
            lock.acquire()#获取锁
            locks.append(lock)
            thread.start_new_thread(self.download, (u,lock,))

        #在主线程中判断是否所有的锁都已释放
        for lock in locks:
            while lock.locked():
                pass
if __name__ == '__main__':
    main = Main('http://image.baidu.com/search/flip?tn=baiduimage&ie=utf-8&word=周杰伦&pn=0&gsm=50&ct=&ic=0&lm=-1&width=0&height=0')
    main.craw()

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