Unexpected "undefined" error

[cboos]

While stress-testing Trac, I sometimes get weird Genshi errors, using a fairly recent build (0.5dev-r766, well, that's the latest even).

KeyError: <Undefined 'name'>

and the one line backtrace is:

 File "...\trunk\trac\ticket\templates\query_results.html", line 48, in  <Suite u'name = header.name; value = result[name]'>  

The actual line content is:

 <py:with vars="name = header.name; value = result[name]">

The data section shows the following for header (with less truncation than usual in order to get the full representation):

header  	{'href': '/devel/query?group=status&order=owner&milestone=This+is+a+stupid+milestone', 'name': 'owner', 'label': 'Owner'}

As you can see, there's an entry for 'name' here.

Needless to say, when reloading the page after the error, it displays just fine, so it's really a transient error triggered by the testing conditions and probably due to some race condition.

Just another thought: line 47 is

<py:for each="idx, header in enumerate(headers)" py:choose="">

so perhaps it's a bug in enumerate... but that would be scary as well!

How to reproduce

Start tracd, in a new firefox window, open something like twenty tabs, half of them custom query views. Restart tracd. "Load all tabs". If you're lucky, one of the custom query view will show the above backtrace.

[cboos]

Correction:

How to reproduce ...

Restart tracd. "Load all tabs".

The "restart" is actually not needed in order to reproduce the problem.

[cboos]

This makes the problem go away:

genshi/template/eval.py

@@ -73 +73 @@
             lookup = LenientLookup
         elif isinstance(lookup, basestring):
             lookup = {'lenient': LenientLookup, 'strict': StrictLookup}[lookup]
-        self._globals = lookup.globals()
+        self._globals = lookup.globals
 
     def __eq__(self, other):
         return (type(other) == type(self)) and (self.code == other.code)
@@ -139 +139 @@
         :return: the result of the evaluation
         """
         __traceback_hide__ = 'before_and_this'
-        _globals = self._globals
+        _globals = self._globals()
         _globals['data'] = data
         return eval(self.code, _globals, {'data': data})
 
@@ -161 +161 @@
         :param data: a mapping containing the data to execute in
         """
         __traceback_hide__ = 'before_and_this'
-        _globals = self._globals
+        _globals = self._globals()
         _globals['data'] = data
         exec self.code in _globals, data
 

Now the real challenge would be to write a unit-test for that ;-)

[cmlenz]

Applied in [770]. Thanks!