【发布时间】：2013-03-12 16:38:21
【问题描述】：
我正在运行etree.HTML( data )，如下所示，有很多不同的data 内容。但是，对于特定的data 内容，lxml.etree.HTML 不会解析它，而是进入无限循环并消耗 100% 的 CPU。
有谁知道下面这个data 中的确切原因是什么？更重要的是，如何防止这种情况发生在无限数量的随机损坏的data 上？
编辑：原来这是 lxml 2.7.8 及以下版本的错误（在 至少）。更新到 lxml 2.9.0，bug 消失了。
编辑：我知道这构成了一个无限循环，但这并不是我遇到的不良行为。它以健康的data 内容运行良好（作为无限循环）。对于不健康的data 内容，如下所示，循环将停止，RAM 将开始填满，当它满时，所有 CPU 进入等待状态。原始调试请参见this question。
#!/usr/bin/python
# -*- coding: utf-8 -*-
#
import sys
from lxml import etree
data = '''
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:og="http://opengraphprotocol.org/schema/" xmlns:fb="http://www.facebook.com/2008/fbml">
<head>
<meta charset="UTF-8">
<title>The 20 Most Despicable Things Gordon Ramsay Has Said and Done, Ranked -- Grub Street New York</title>
<link rel="alternate" type="application/rss+xml" title="RSS 2.0" href="http://feedproxy.google.com/nymag/grubstreet" />
<meta name="Headline" content="The 20 Most Despicable Things Gordon Ramsay Has Said and Done, Ranked" />
<meta name="keywords" content="april bloomfield, el gordo, frank bruni, gordon ramsay, lawsuits, lists, marcus samuelsson, mario batali, shitlist, spotted pig, sued" />
<meta name="description" content="Racism, fat-shaming, and vegetarian trickery." />
<meta name="Byline" content="Sierra Tishgart" />
<meta name="Type_of_Feature" content="" />
<meta name="Issue_Date" content="March 8, 2013 12:50 PM" />
<meta name="related_stories" content="The 20 Most Despicable Things Gordon Ramsay Has Said and Done, Ranked" />
<meta name="document_type" content="Blog" />
<meta name="category" content="Lists" />
<link rel="image_src" href="http://pixel.nymag.com/imgs/daily/grub/2013/03/08/08-gorgon-ramsay.o.jpg/a_146x97.jpg" />
<link rel="canonical" href="http://newyork.grubstreet.com/2013/03/20-despicable-things-gordon-ramsay.html" id="canonical" />
<script>
var canonicalUrl = "http://newyork.grubstreet.com/2013/03/20-despicable-things-gordon-ramsay.html";
</script>
<meta name="content.tags.primary" content=";network - Grub Street,;city - New York City,;tag - lists" />
<meta name="content.tags" content=";tag - april bloomfield,;tag - el gordo,;tag - frank bruni,;tag - gordon ramsay,;tag - lawsuits,;tag - marcus samuelsson,;tag - mario batali,;tag - shitlist,;tag - spotted pig,;tag - sued" />
<meta name="content.hierarchy" content="New York City:Grub Street" />
<meta name="content.type" content="Blog" />
<meta name="content.subtype" content="Blog Entry" />
<meta property="fb:app_id" content="206283005644" />
<meta property="og:title" content="The 20 Most Despicable Things Gordon Ramsay Has Said and Done, Ranked" />
<meta property="og:description" content="Racism, fat-shaming, and vegetarian trickery." />
<meta property="og:image" content="http://pixel.nymag.com/imgs/daily/grub/2013/03/08/08-gorgon-ramsay.o.jpg/a_146x97.jpg"/>
<meta property="og:url" content="http://newyork.grubstreet.com/2013/03/20-despicable-things-gordon-ramsay.html" />
<meta property="og:type" content="article" />
<meta property="og:site_name" content="Grub Street New York" />
<meta name="viewport" content="width=1020">
<link type="text/css" rel="stylesheet" href="http://cache.nymag.com/css/screen/grubstreet/grubstreet-core.css" media="all" />
<link type="text/css" rel="stylesheet" href="http://cache.nymag.com/css/screen/section/daily/slideshow.css" media="all" />
<link type="text/css" rel="stylesheet" href="http://cache.nymag.com/css/screen/echo.css" media="all" />
<link type="text/css" rel="stylesheet" href="http://cache.nymag.com/css/screen/loginRegister.css" media="all" />
<link rel="stylesheet" href="http://cache.nymag.com/css/screen/advertising.css" media="all" />
<link rel="shortcut icon" href="http://images.nymag.com/gfx/grubst/favicon.ico" />
<style type="text/css">
#adsplashtop,#pushdown {padding:5px 5px;}
#pushdown {border-top:1px solid #737373}
</style>
<!--[if IE 6]>
<link rel="stylesheet" href="http://cache.nymag.com/css/screen/grubstreet/win-ie6.css" type="text/css" media="screen, projection" />
<![endif]-->
<!--[if IE 7]>
<link rel="stylesheet" href="http://cache.nymag.com/css/screen/grubstreet/win-ie7.css" type="text/css" media="screen, projection" />
<![endif]-->
<script type="text/javascript">
var NYM = {};
NYM.config = {};
NYM.config.membership = {
"service":"nym"
};
NYM.config.advertising = {
"sitename":"nym.grubstreet"
};
</script>
<script type="text/javascript">
var date = 'March 12, 2013 12:42:38';
var currDate=new Date(date);
var GRUBST = {};
if (!NYM) {
var NYM = {};
NYM.config = {};
NYM.config.membership = {
"service":"nym"
};
NYM.config.advertising = {
"sitename":"nym.grubstreet"
};
}
</script>
<script type="text/javascript" src="http://cache.nymag.com/scripts/modernizr-1.7.min.js"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" src="http://cache.nymag.com/scripts/jquery-ui-1.8.2.custom.min.js"></script>
<script type="text/javascript" src="http://cache.nymag.com/scripts/ad_manager.js"></script>
<script type="text/javascript" src="http://cache.nymag.com/js/2/global.js"></script>
<script type="text/javascript" src="http://cache.nymag.com/scripts/skinTakeover.js"></script>
<script type="text/javascript" src="http://cache.nymag.com/scripts/grubstreet-controls.js"></scr
'''
n = 0
while True:
n += 1
tree = etree.HTML( data )
m = tree.xpath("//meta[@property]")
print '-', n
for i in m:
print n
#print (i.attrib['property'], i.attrib['content'])
对于快速版本，您可以使用：
import sys
from lxml import etree
print("%-20s: %s" % ('Python', sys.version_info))
print("%-20s: %s" % ('lxml.etree', etree.LXML_VERSION))
print("%-20s: %s" % ('libxml used', etree.LIBXML_VERSION))
print("%-20s: %s" % ('libxml compiled', etree.LIBXML_COMPILED_VERSION))
print("%-20s: %s" % ('libxslt used', etree.LIBXSLT_VERSION))
print("%-20s: %s" % ('libxslt compiled', etree.LIBXSLT_COMPILED_VERSION))
我有：
OS : Ubuntu 12.10 (AWS)
Python : sys.version_info(major=2, minor=7, micro=3, releaselevel='final', serial=0)
lxml.etree : (3, 1, 0, 0)
libxml used : (2, 7, 8)
libxml compiled : (2, 7, 8)
libxslt used : (1, 1, 26)
libxslt compiled : (1, 1, 26)
【问题讨论】：
标签： python html debugging lxml