[Zope-DB] ZODB question

[Dieter Maurer]

Bo M. Maryniuck wrote at 2003-10-14 13:09 +0200:
 > This is ZODB question. Since this is also DB, therefore this is not OT. ;-)
 > 
 > I found in my log's this:
 > 
 > --------------------
 > 2003-10-14T12:15:07 ERROR(200) ZODB Shouldn't load state for 
 > '\x00\x00\x00\x00\x00\x19\xc2\xc1' when the connec
 > closed.
 > --------------------
 > 
 > What it does mean? In .../ZODB/Connection.py it causes when self._storage is 
 > empty and _storage is a usually FileStorage instance. Who can tell me why it 
 > wants to load state (?) on closed storage for an object and what might be 
 > wrong with that object?

Because you use a persistent object in a way you should not...

A persistent object has a hidden reference to the connection
which loaded the object from the storage ("_p_jar").
The connection is closed when the request finished.
Therefore, you must not use a persistent object outside the request
that loaded it. Apparently, you do just that.

Prominent examples for such wrong-doing are:

  *  storing persistent objects in a cache (other than the connection's
     own ZODB cache)

  *  passing a persistent object to a separate thread.


Dieter