[python-win32] Apache & mod_python & win32com

[Mike Driscoll]

Dominique.Holzwarth at ch.delarue.com wrote:
> Hello everyone
>
> I'm developing a web application using mod_python and the apache web server. That application has to handle xml files and for that I'm using win32com with with MSXML.
>
> My problem is, that apache spawns a new process / thread (not sure wether ist a process or thread. I think it's a thread) per http request. So when multiple users generated requests "at the same time" (new request before the first one is returned) I have multiple threads running. And that's where my win32com code is crashing...
>
> Currently, for every request my code does the following (as an example):
>
> return win32com.client.Dispatch("Msxml2.DOMDocument.6.0")
>
> To get an empty MSXSML DOM object.
>
> For multiple requests at the same time I get the following error:
>
>  File "C:\Program Files\Apache Software Foundation\Apache2.2\TCRExceptionManagerData\database_library\database.py", line 24, in __init__
>     self.__configFileSchema =elf.__XSDSchemaCache()
>
>   File "C:\Program Files\Apache Software Foundation\Apache2.2\TCRExceptionManagerData\database_library\database.py", line 1774, in __XSDSchemaCache
>     return win32com.client.Dispatch("MSXML2.XMLSchemaCache.6.0")
>
>   File "C:\Program Files\Python25\lib\site-packages\win32com\client\__init__.py", line 95, in Dispatch
>     dispatch, userName =ynamic._GetGoodDispatchAndUserName(dispatch,userName,clsctx)
>
>   File "C:\Program Files\Python25\lib\site-packages\win32com\client\dynamic.py", line 98, in _GetGoodDispatchAndUserName
>     return (_GetGoodDispatch(IDispatch, clsctx), userName)
>
>   File "C:\Program Files\Python25\lib\site-packages\win32com\client\dynamic.py", line 78, in _GetGoodDispatch
>     IDispatch =ythoncom.CoCreateInstance(IDispatch, None, clsctx, pythoncom.IID_IDispatch)
>
> com_error: (-2147221008, 'CoInitialize has not been called.', None, None)
>
> I've read already a bit in this mailing list and someone mentioned that one need to call pythoncom.CoInitialize() and pythoncom.CoUninitialize(). But I don't know where exactly i should call those functions and wether that'll solve my problem... Also, when I do a 'import win32com.pythoncom' I get an error that the module 'pythoncom' does not exist!
>
> I would be really happy if someone could help me and tell me how to make my win32com work for multiple threads!
>
> Greetings
> Dominique
>
>
>   
I had this issue when I was using WMI in a thread. I basically just 
ended up calling CoInitialize() before I called my WMI object (or 
function) and then CoUninitialize() when the object/function returned.

However, if you're messing with XML, I would recommend one of the many 
excellent XML parsing libraries in Python. I've used the included DOM 
interface as well as lxml, which is more object-oriented. I've even used 
pyparsing in one of my scripts...it's pretty new, but the developer for 
it is very responsive and has good examples and even a small e-book on it.

Just some ideas...

Mike