[ZODB-Dev] Re: BTrees strangeness (was [Zope-dev] Zope 2.X BIG Session problems - blocker - our site dies - need help of experience Zope developer, please)

[michael]

On 11/03/2004, at 1:07 PM, Chris McDonough wrote:

> On Wed, 2004-03-10 at 18:30, michael wrote:
>> On closer inspection I have another small detail - I'm only seeing
>> these KeyError's for sessions that have had a chance to expire and  
>> when
>> trying to access the session from standard_error_message.
>
> Can you provide a complete traceback for the error message?  I'm
> guessing that it happens during session garbage collection but I can't
> be sure without the traceback.

hmmm... continuing to refine what I think I'm seeing :-O

I don't get a KeyError thrown until *after* at least one rendering of  
standard_error_message that includes an access to a session variable.  
And I'm only getting KeyError's for sessions that have had a chance to  
expire. And that KeyError will be thrown whenever any access is made  
for the session. (Previously I thought I was *only* seeing KeyError's  
being thrown from standard_error_message.) I can't yet say from what  
I'm seeing if the session accessed in standard_error_message which  
somehow corrupts the consistency of transience is the same session for  
which the KeyError is thrown further down the track.

Here is an example traceback when the KeyError is thrown from a Script  
(Python) that reads the session variable. Followed by a similar  
traceback thrown when Zope tries to read that same sesssion variable in  
my standard_error_message:

2004-03-11T16:13:03 ERROR(200) SiteError http://localhost:8080/test/read
Traceback (most recent call last):
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/Publish.py",  
line 101, in publish
     request, bind=1)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/mapply.py",  
line 88, in mapply
     if debug is not None: return debug(object,args,context)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/Publish.py",  
line 41, in call_object
     result=apply(object,args) # Type s<cr> to step into published  
object.
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Shared/DC/Scripts/ 
Bindings.py", line 306, in __call__
     return self._bindAndExec(args, kw, None)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Shared/DC/Scripts/ 
Bindings.py", line 343, in _bindAndExec
     return self._exec(bound_data, args, kw)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/PythonScripts/ 
PythonScript.py", line 318, in _exec
     result = f(*args, **kw)
   File "Script (Python)", line 2, in read
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/ 
HTTPRequest.py", line 1218, in __getattr__
     v = self.get(key, default, returnTaints=returnTaints)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/ 
HTTPRequest.py", line 1178, in get
     if callable(v): v = v()
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Sessions/ 
SessionDataManager.py", line 93, in getSessionData
     return self._getSessionDataObject(key)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Sessions/ 
SessionDataManager.py", line 180, in _getSessionDataObject
     ob = container.new_or_existing(key)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Transience/ 
Transience.py", line 176, in new_or_existing
     item  = self.get(key, notfound)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Transience/ 
Transience.py", line 809, in get
     v = self._data[b].get(k, notfound)
KeyError: 1078974700
------
2004-03-11T16:13:04 BLATHER(-100) OFS Exception while rendering an  
error message
Traceback (most recent call last):
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/OFS/SimpleItem.py", line  
204, in raise_standardErrorMessage
     v = s(**kwargs)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Shared/DC/Scripts/ 
Bindings.py", line 306, in __call__
     return self._bindAndExec(args, kw, None)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Shared/DC/Scripts/ 
Bindings.py", line 343, in _bindAndExec
     return self._exec(bound_data, args, kw)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/PythonScripts/ 
PythonScript.py", line 318, in _exec
     result = f(*args, **kw)
   File "Script (Python)", line 12, in standard_error_message
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/ 
HTTPRequest.py", line 1218, in __getattr__
     v = self.get(key, default, returnTaints=returnTaints)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/ZPublisher/ 
HTTPRequest.py", line 1178, in get
     if callable(v): v = v()
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Sessions/ 
SessionDataManager.py", line 93, in getSessionData
     return self._getSessionDataObject(key)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Sessions/ 
SessionDataManager.py", line 180, in _getSessionDataObject
     ob = container.new_or_existing(key)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Transience/ 
Transience.py", line 176, in new_or_existing
     item  = self.get(key, notfound)
   File  
"/Users/michael/Desktop/Zope-2.7.0/lib/python/Products/Transience/ 
Transience.py", line 809, in get
     v = self._data[b].get(k, notfound)
KeyError: 1078974700

And the Python (Script) 'read' looks like:

request = container.REQUEST
session = request.SESSION
count = session.get('count',0)
return str(count)

Michael