Key error when rendering under load

[Ksenia]

Hi,

I am testing my home-made WSGI app with ab. To increase performance
I've added module_directory parameters and filesystem_checks to
TemplateLookup. It works great, the rendering is much faster, but with
module_directory parameter added, 1 or 2 of 100 requests fail. On the
debug page I can see a traceback:
(copy-paste from Weberror page)
[...]
Module page_html:24 in _mako_inherit view
>> return runtime._inherit_from(context, 'master.html', _template_uri)
Module mako.runtime:297 in _inherit_from view
>> template = _lookup_template(context, uri, calling_uri)
Module mako.runtime:322 in _lookup_template view
>> return lookup.get_template(uri)
Module mako.lookup:85 in get_template view
>> return self.__load(srcfile, uri)
Module mako.lookup:127 in __load view
>> self.__collection[uri] = Template(uri=uri, filename=posixpath.normpath(filename), lookup=self, module_filename=(self.modulename_callable is not None and self.modulename_callable(filename, uri) or None), **self.template_args)
Module mako.template:84 in __init__ view
>> del sys.modules[self.module_id]
KeyError: 'master_html'

Is this something in environment that brings Mako down? I can imagine
that my home-grown WSGI app / framework is not as reliable as some
well-tested frameworks. Or is this due to some OS limitations? (OSX
10.5)

Thanks
Ksenia

[Michael Bayer]

that error suggests that multiple Template objects of the same path are
loading into memory at the same time, which shouldn't be possible because
the __load() method of TemplateLookup is mutexed. So would need to know
what "I've added module_directory parameters and filesystem_checks to
TemplateLookup" means - if you modified your TL, then yeah it looks like
you've broken its thread-safety.

[Ksenia]

Michael, thank you for a quick answer! After checking the code twice
I've found the problem - the global instance of TemplateLookup was by
mistake instantiated on every request instead of only once during
application startup. After fixing it everything works as expected.

Ksenia