Mailman 3 November 2012 - lxml - The Python XML Toolkit

[lxml-dev] lxml has its page on launchpad
by Stefan Behnel 11 Apr '23

11 Apr '23

Hi all, I added the lxml project to launchpad, the Ubuntu Bug-Tracker. It also has a FAQ engine and a couple of other goodies. https://launchpad.net/lxml It's easy to sign up for launchpad, BTW, no 90%-footnotes-contract. Have fun, Stefan

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[lxml-dev] Checking whether a node is a comment/element
by Geoffrey Sneddon 10 Apr '23

10 Apr '23

Hi, What's the best way to check whether a given node is a comment or an element? For the former, I'm currently using isinstance(node, etree._Comment), which is rather obviously sub-optimal. -- Geoffrey Sneddon <http://gsnedders.com/>

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[lxml-dev] Reparenting a node
by Lawrence Oluyede 30 Jan '23

30 Jan '23

I have a doc A and a doc B, I'd like to put a node extracted from A in the document B but I always get a ValueError: ValueError: Element is not a child of this node. I didn't find any "setparent" in the API. How can I do this? -- Lawrence, oluyede.org - neropercaso.it "It is difficult to get a man to understand something when his salary depends on not understanding it" - Upton Sinclair

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[lxml-dev] lxml 2.0.5 released
by Stefan Behnel 11 Jan '23

11 Jan '23

Hi all, lxml 2.0.5 is on PyPI. This is a bug-fix-only release of the stable 2.0 series. Have fun, Stefan 2.0.5 (2008-05-01) Bugs fixed * Resolving to a filename in custom resolvers didn't work. * lxml did not honour libxslt's second error state "STOPPED", which let some XSLT errors pass silently. * Memory leak in Schematron with libxml2 >= 2.6.31.

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[lxml-dev] Building LXML Trunk
by Sidnei da Silva 31 Aug '22

31 Aug '22

Hi, I've tried to build lxml from trunk today, on Win32. Got the following error: src\lxml\etree.c(880) : error C2059: syntax error : ')' src\lxml\etree.c(881) : error C2059: syntax error : ')' src\lxml\etree.c(882) : error C2059: syntax error : ')' src\lxml\etree.c(883) : error C2059: syntax error : ')' Any clue? Smells like a Pyrex issue? -- Sidnei da Silva Enfold Systems http://enfoldsystems.com Fax +1 832 201 8856 Office +1 713 942 2377 Ext 214

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Memory leak when parsing XML files in sequence?
by Maarten van Gompel (proycon) 03 May '13

03 May '13

Hi, I stumbled across what I think it a memory leak within the lxml module. I am parsing literally millions of mostly small XML files, in sequence. In the following, simplified, fashion: index = glob.glob('/path/to/dir/with/huge/number/of/xml/files/*xml') for f in index: d = lxml.etree.parse(f) The problem is that (almost) every iteration, memory usage is increased. But note that d gets overwritten everytime and the reference to the previous document should be lost (I don't reference it anywhere else). Even an explicit 'del d' and gc.collect() within the loop doesn't help to clear up the extra memory. I used objgraph to debug a bit and the Python reference counts remain unchanged as I would expect, leaving me to conclude that this is a memory leak problem in the lxml module. This becomes problematic quickly when dealing with millions of XML files. I attach a short log excerpt in which I extracted resident memory usage from ps after each iteration and measure the increase. Note that I only parse the documents, to be overwritten each time, I don't do anything else with them in this test case. Is this a known problem? Is there anything else I explicitly need to do to free the memory used? The problem does not reproduce if I reload the same document over and over again. Memory usage remains constant then. It only happens when new documents are loaded, and even then in some rare cases the problem dos not occur for some or several iterations, most notably at the start of the log. I also attach an example of an XML file. Python 2.7.2 (ubuntu 11.10, x86_64) lxml.etree : (2, 3, 0, 0) libxml used : (2, 7, 8) libxml compiled : (2, 7, 8) libxslt used : (1, 1, 26) libxslt compiled : (1, 1, 26) Regards, -- Maarten van Gompel (Proycon) E-mail: proycon(a)anaproy.nl Homepage: http://proycon.anaproy.nl Google+: https://plus.google.com/105334152965507305708 Facebook: http://facebook.com/proycon Twitter: http://twitter.com/proycon

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Apache2 crashes
by Brieuc SCHAFF 12 Feb '13

12 Feb '13

Hi, We are using lxml in several of our applications with Python 2.6 and from time to time, the application stops responding after a segmentation fault error, and this kind of backtrace: *Jul 1 15:35:01 server4 httpd: *** glibc detected *** /usr/sbin/apache2: malloc(): smallbin double linked list corrupted: 0x00007f583a03f500 **** *Jul 1 15:35:01 server4 httpd: ======= Backtrace: =========* *Jul 1 15:35:01 server4 httpd: /lib/libc.so.6(+0x77806)[0x7f58376c2806]* *Jul 1 15:35:01 server4 httpd: /lib/libc.so.6(+0x7bb39)[0x7f58376c6b39]* *Jul 1 15:35:01 server4 httpd: /lib/libc.so.6(__libc_malloc+0x6e)[0x7f58376c77de]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libxml2.so.2(xmlInitParserCtxt+0x317)[0x7f58343f2887]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libxml2.so.2(xmlNewParserCtxt+0x2c)[0x7f58343f2acc]* *Jul 1 15:35:01 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0x54eda)[0x7f5818db6eda]* *Jul 1 15:35:01 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0xddcf3)[0x7f5818e3fcf3]* *Jul 1 15:35:01 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0xab5ee)[0x7f5818e0d5ee]* *Jul 1 15:35:01 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0xb7d8e)[0x7f5818e19d8e]* *Jul 1 15:35:01 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0xb827e)[0x7f5818e1a27e]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalFrameEx+0x51a0)[0x7f582face030]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalFrameEx+0x5a98)[0x7f582face928]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalCodeEx+0x920)[0x7f582facfd60]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0x7dd60)[0x7f582fa55d60]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f582fa282e3]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalFrameEx+0x3adf)[0x7f582facc96f]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalCodeEx+0x920)[0x7f582facfd60]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0x7dd60)[0x7f582fa55d60]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f582fa282e3]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0x61cef)[0x7f582fa39cef]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f582fa282e3]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0xb66dc)[0x7f582fa8e6dc]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f582fa282e3]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_CallObjectWithKeywords+0x43)[0x7f582fac8193] * *Jul 1 15:35:01 server4 httpd: /usr/lib/apache2/modules/mod_wsgi.so(+0x12fdb)[0x7f582fe9bfdb]* *Jul 1 15:35:01 server4 httpd: /usr/lib/apache2/modules/mod_wsgi.so(+0x17eed)[0x7f582fea0eed]* *Jul 1 15:35:01 server4 httpd: /usr/lib/libapr-1.so.0(+0x29eb3)[0x7f5837c14eb3]* *Jul 1 15:35:01 server4 httpd: /lib/libpthread.so.0(+0x69ca)[0x7f58379d49ca]* *Jul 1 15:35:01 server4 httpd: /lib/libc.so.6(clone+0x6d)[0x7f5837731cdd]* ----------------- *Jul 11 10:44:48 server4 httpd: *** glibc detected *** /usr/sbin/apache2: munmap_chunk(): invalid pointer: 0x00007f3968b8cb68 **** *Jul 11 10:44:48 server4 httpd: ======= Backtrace: =========* *Jul 11 10:44:48 server4 httpd: /lib/libc.so.6(+0x77806)[0x7f39789dd806]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(xmlResetError+0x22)[0x7f39755038e2]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(__xmlRaiseError+0x237)[0x7f3975504e07]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(__xmlSimpleError+0x6b)[0x7f397550543b]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(xmlParserInputBufferGrow+0x16b)[0x7f397553271b]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(xmlParserInputGrow+0x4c)[0x7f397550739c]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(+0x3bd52)[0x7f397550bd52]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(xmlParseDocument+0x4b8)[0x7f39755204c8]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libxml2.so.2(+0x505c5)[0x7f39755205c5]* *Jul 11 10:44:48 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0x8fab0)[0x7f3958ad8ab0]* *Jul 11 10:44:48 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0x2daa0)[0x7f3958a76aa0]* *Jul 11 10:44:48 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0x2ddc9)[0x7f3958a76dc9]* *Jul 11 10:44:48 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0xc26f0)[0x7f3958b0b6f0]* *Jul 11 10:44:48 server4 httpd: /usr/lib/python2.6/dist-packages/lxml/etree.so(+0xc431e)[0x7f3958b0d31e]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalFrameEx+0x51a0)[0x7f397063b030]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalCodeEx+0x920)[0x7f397063cd60]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0x7dd60)[0x7f39705c2d60]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f39705952e3]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalFrameEx+0x3adf)[0x7f397063996f]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_EvalCodeEx+0x920)[0x7f397063cd60]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0x7dd60)[0x7f39705c2d60]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f39705952e3]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0x61cef)[0x7f39705a6cef]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f39705952e3]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(+0xb66dc)[0x7f39705fb6dc]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyObject_Call+0x53)[0x7f39705952e3]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libpython2.6.so.1.0(PyEval_CallObjectWithKeywords+0x43)[0x7f3970635193] * *Jul 11 10:44:48 server4 httpd: /usr/lib/apache2/modules/mod_wsgi.so(+0x12fdb)[0x7f3970a08fdb]* *Jul 11 10:44:48 server4 httpd: /usr/lib/apache2/modules/mod_wsgi.so(+0x17eed)[0x7f3970a0deed]* *Jul 11 10:44:48 server4 httpd: /usr/lib/libapr-1.so.0(+0x29eb3)[0x7f3978f2feb3]* *Jul 11 10:44:48 server4 httpd: /lib/libpthread.so.0(+0x69ca)[0x7f3978cef9ca]* *Jul 11 10:44:48 server4 httpd: /lib/libc.so.6(clone+0x6d)[0x7f3978a4ccdd]* Stopping apache and restarting it fix the issue, but we have no idea why this is happening. We use Unbuntu 10.10's package of lxml, which is version 2.2.4. *>>> print("%-20s: %s" % ('Python', sys.version_info))* *Python : (2, 6, 5, 'final', 0)* *>>> print("%-20s: %s" % ('lxml.etree', etree.LXML_VERSION))* *lxml.etree : (2, 2, 4, 0)* *>>> print("%-20s: %s" % ('libxml used', etree.LIBXML_VERSION))* *libxml used : (2, 7, 6)* *>>> print("%-20s: %s" % ('libxml compiled', etree.LIBXML_COMPILED_VERSION))* *libxml compiled : (2, 7, 6)* *>>> print("%-20s: %s" % ('libxslt used', etree.LIBXSLT_VERSION))* *libxslt used : (1, 1, 26)* *>>> print("%-20s: %s" % ('libxslt compiled', etree.LIBXSLT_COMPILED_VERSION))* *libxslt compiled : (1, 1, 26)* * * Do you have any idea of what could cause these issues ? I wonder if upgrading to a newer version of the library could change anything. Thanks in advance for any answer you could provide. Regards, B. _____________________ Brieuc SCHAFF +33609898260 _____________________

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lxml without libxslt
by Andriy Kornatskyy 02 Dec '12

02 Dec '12

Is it possible to build lxml without libxslt installed? Thanks. Andriy Kornatskyy

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Baffled by documentation of namespace in XPath
by Martin Mueller 30 Nov '12

30 Nov '12

I have always found it difficult to wrap my head around the details of namespaces in XML processing, but I am completely baffled by the discussion and examples of namespaces in the XPath section. Consider the following minimal TEI document: <?xml version="1.0" encoding="UTF-8"?> <?xml-model href="http://www.tei-c.org/release/xml/tei/custom/schema/relaxng/tei_bare.r ng" schematypens="http://relaxng.org/ns/structure/1.0"?> <TEI xmlns="http://www.tei-c.org/ns/1.0"> <teiHeader> <fileDesc> <titleStmt> <title>A minimal TEI document</title> </titleStmt> <publicationStmt> <p>unpublished</p> </publicationStmt> <sourceDesc> <p>born digital</p> </sourceDesc> </fileDesc> </teiHeader> <text> <front> <div><head>Preface</head> <p>This is the preface</p></div> </front> <body> <div><head>Chapter 1</head> <div><head>Subsection 1.1</head><p>The text of 1.1</p></div> <div><head>Subsection 1.2</head><p>The text of 1.2</p></div> </div> </body> </text> </TEI> If I process this with xquery, I need to have a namespace declaration of the type declare namespace tei = "http://www.tei-c.org/ns/1.0"; The miniscript xquery version "1.0"; declare namespace tei = "http://www.tei-c.org/ns/1.0"; let $text := doc('/users/martin/dropbox/learnpython.txt/bareguineapig.xml') return $text/tei:TEI//tei:front//tei:p will return <?xml version="1.0" encoding="UTF-8"?> <p xmlns="http://www.tei-c.org/ns/1.0">This is the preface</p> What is the equivalent for this normal case of an XML document? The documentation gives the following XML fragment <a:foo xmlns:a="http://codespeak.net/ns/test1"... xmlns:b="http://codespeak.net/ns/test2"> <b:bar>Text</b:bar> </a:foo> I've never seen XML documents that use namespace prefixes in the closing tags, and I can't figure out how to apply the information from the documentation to my case. I know how to process the document without a namespace. For instance f = '/users/martin/dropbox/learnpython.txt/bareguineapignonamespace.xml' tree = etree.parse(f) r = tree.xpath('/TEI/text/front') for element in r[0].iter('p'): print element.text will print out "This is the preface." But what do I need to do to get the same result when the TEI root element contains the tei namespace? I also wonder whether there is an error in this code: r = doc.xpath('/t:foo/b:bar', namespaces={'t': 'http://codespeak.net/ns/test1', 'b': 'http://codespeak.net/ns/test2'} Shouldn't the 't' be 'a'? It doesn't seem to affect the way the code works, though . Martin Mueller Professor of English and Classics Northwestern University

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Possible bug in getpath
by Ahmed 26 Nov '12

26 Nov '12

Hi All, I'm trying to use getpath() to get the absolute xpath for an element in a tree. This works fine when all namespaces have consistent prefixes in the document. However when I deal with a document in which the same namespace can have multiple prefixes I get wrong path. I wrote this little script to re-produce the error. #!/usr/bin/env python from lxml import etree from StringIO import StringIO def generate_sample_tree_with_multiple_prefixes(): root = etree.Element('root', nsmap={'a': 'http://a.b/c'}) for x in range(10): ns = "http://ns.org/ns/" prefix = 'l_%s' % x node = etree.SubElement(root, "{%s}l1" % ns, nsmap={prefix: ns}) node.set('id', 'id_%s' % x) return etree.parse(StringIO(etree.tostring(root))) def generate_sample_tree_with_single_prefixes(): root = etree.Element('root', nsmap={'a': 'http://a.b/c'}) for x in range(10): ns = "http://ns.org/ns/" prefix = 'ns' node = etree.SubElement(root, "{%s}l1" % ns, nsmap={prefix: ns}) node.set('id', 'id_%s' % x) return etree.parse(StringIO(etree.tostring(root))) def test_multiple(): tree = generate_sample_tree_with_multiple_prefixes() r = tree.getroot() for l1 in r.iterchildren(): path = tree.getpath(l1) ret = tree.xpath(path, namespaces=l1.nsmap) assert len(ret) == 1, "Multiple elements returned: %s" % ret assert l1 == ret[0], "It's not the same" def test_single(): tree = generate_sample_tree_with_single_prefixes() r = tree.getroot() for l1 in r.iterchildren(): path = tree.getpath(l1) ret = tree.xpath(path, namespaces=l1.nsmap) assert len(ret) == 1, "Multiple elements returned" assert l1 == ret[0], "It's not the same" if __name__ == '__main__': test_single() test_multiple() thanks -- -Ahmed

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