Python hangs on lxml.etree.XMLSchema(tree) with apache + mod_wsgi
I had the same problem (lxml 2.2.6, mod_wsgi 3.2). A work around for this is to pass a file or filename to the constructor: XMLSchema(file=).
Python hangs on 
lxml.etree.XMLSchema(tree)
when I use it on apache server + mod_wsgi (Windows)
When I use Django dev server - all works fine
if you know about other nice XML validation solution against XSD, tell me pls
Update:
I'm using soaplib, which uses lxml

logger.debug("building schema...")
self.schema = etree.XMLSchema(etree.parse(f))

logger.debug("schema %r built, cleaning up..." % self.schema)

I see "building schema..." in apache logs, but I don't see "schema %r built, cleaning up..."
Update 2:
I built lxml 2.3 with MSVS 2010 visual C++; afterwards it crashes on this line self.schema = etree.XMLSchema(etree.parse(f)) with  Unhandled exception at 0x7c919af2 in httpd.exe: 0xC0000005: Access violation writing location 0x00000010.