Python - Compare Large XML Files

Question

Python - 2.7.3 I want to compare two xml files (Size approx. - 100 MB) I updated code based on discussion on this thread. Comparing two xml files in python

I used element.iter() instead of GetChildren(). For testing purposes, I edited the xml file and made it really short i.e. 1MB in size.

Following is the code.

import xml.etree.ElementTree as ET
import logging

class XmlTree():

    def __init__(self):
        logging.basicConfig(filename='example.log',level=logging.DEBUG) 

        self.logger = logging.getLogger('xml_compare')      
        self.hdlr = logging.FileHandler('xml-comparison.log')
        self.formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')             
        self.logger.addHandler(self.hdlr)

    @staticmethod
    def convert_string_to_tree( xmlString):

        return ET.fromstring(xmlString)

    def xml_compare(self, x1, x2, excludes=[]):
        """
        Compares two xml etrees
        :param x1: the first tree
        :param x2: the second tree
        :param excludes: list of string of attributes to exclude from comparison
        :return:
            True if both files match
        """

        if x1.tag != x2.tag:
            self.logger.debug('Tags do not match: %s and %s' % (x1.tag, x2.tag))            
            return False
        for name, value in x1.attrib.items():
            if not name in excludes:
                if x2.attrib.get(name) != value:
                    self.logger.debug('Attributes do not match: %s=%r, %s=%r'  % (name, value, name, x2.attrib.get(name)))                  
                    return False
        for name in x2.attrib.keys():
            if not name in excludes:
                if name not in x1.attrib:
                    self.logger.debug('x2 has an attribute x1 is missing: %s' % name)                   
                    return False
        if not self.text_compare(x1.text, x2.text):
            self.logger.debug('text: %r != %r' % (x1.text, x2.text))            
            return False
        if not self.text_compare(x1.tail, x2.tail):
            self.logger.debug('tail: %r != %r' % (x1.tail, x2.tail))
            return False

        cl1 = list(x1.iter())
        cl2 = list(x2.iter())
        if len(cl1) != len(cl2):
            self.logger.debug('children length differs, %i != %i'
                         % (len(cl1), len(cl2)))
            return False
        i = 0
        for c1, c2 in zip(cl1, cl2):
            i += 1
            if not c1.tag in excludes:
                if not self.xml_compare(c1, c2, excludes):
                    self.logger.debug('children %i do not match: %s' % (i, c1.tag))                 
                    return False        
        return True

    def text_compare(self, t1, t2):
        """
        Compare two text strings
        :param t1: text one
        :param t2: text two
        :return:
            True if a match
        """
        if not t1 and not t2:
            return True
        if t1 == '*' or t2 == '*':
            return True
        return (t1 or '').strip() == (t2 or '').strip()

I call it like following

tree1 = ET.parse('A.xml')
tree2 = ET.parse('B.xml')
root1 = tree1.getroot()
root2 = tree2.getroot()
xmlStr1 = ET.tostring(root1,encoding='utf8',method='xml')
xmlStr2 = ET.tostring(root2,encoding='utf8',method='xml')

basetree1 = XmlTree.convert_string_to_tree(xmlStr1)
basetree2 = XmlTree.convert_string_to_tree(xmlStr2)


comparator = XmlTree()

if comparator.xml_compare(basetree1, basetree2, [""]):
    print "XMLs match"
else:
    print "XMLs don't match"

But it is giving me following error

File "<pyshell#3>", line 56, in xml_compare
    if not self.xml_compare(c1, c2, excludes):
  File "<pyshell#3>", line 46, in xml_compare
    cl1 = list(x1.iter())
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 477, in iter
    for e in e.iter(tag):
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 477, in iter
    for e in e.iter(tag):
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 477, in iter
    for e in e.iter(tag):
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 477, in iter
    for e in e.iter(tag):
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 477, in iter
    for e in e.iter(tag):
  File "C:\Python27\lib\xml\etree\ElementTree.py", line 472, in iter
    if tag == "*":
RuntimeError: maximum recursion depth exceeded in cmp

what am I doing wrong? Is Zip function very heavy to loop through? Is there an alternative. While doing XML comparison, I want to compare a)Text B)tag