Hi there, We're doing some stress testing before rolling some code based on lxml into production and we've been able to reproduce a crash when reusing the same XSLT object repeatedly. I will dump some information here in the hope that anyone can shed a light before I go trying to compile debug versions of everything and the kitchen sink. The test is composed of a rather small XML file, and a rather big and complex XSLT with several <xsl:import /> <xsl:include /> etc. We fire up 10 threads. Each one has it's own parsed XML file and XSLT, they are not being shared across threads. Each thread then goes on a loop, applying the XSLT to the XML file and serializing the result to a string. With a less than 1000 iterations the crash almost never happens. At about 50000 iterations, the crash is pretty much guaranteed to happen. There doesn't seem to be any memory leak or anything, memory usage is quite stable. This is using the 1.2.1 release. This is a static build on Win32, against: libxml2-2.6.26.win32 libxslt-1.1.17.win32 zlib-1.2.3.win32 iconv-1.9.2.win32 The crash information says its an 'access violation' and it happens somewhere in etree.pyd, when I bring up the debugger only etree.pyd and python24.dll are on the stack (which I guess is pretty useless information). I am hoping to make a debug build to get more information. I can try running the same code on Linux and seeing if it happens there too, or I can try a debug build, or hopefully someone will come out and say I'm doing something wrong here or that the version of libxml2 I'm using has known issues. I can also provide the test code + data upon request. -- Sidnei da Silva Enfold Systems http://enfoldsystems.com Fax +1 832 201 8856 Office +1 713 942 2377 Ext 214