Dieter Maurer dieter at handshake.de
Wed Oct 29 15:46:54 EST 2003

Bo M. Maryniuck wrote at 2003-10-28 20:35 +0200:
 > I think this is no OT, but maybe...

<mailto:zope at zope.org> would be better because ChrisM (session author)
listens there...

 > The question is: can SESSION crash because of ZODB read conflict errors?

When it could then you would use "crash" in a very strange way.

Zope's core "SESSION" feature uses the ZODB and therefore can
face "ReadConflictError"s. In versions before 2.6.1, sessions
used a so called "low conflict connection". Such a connection
ignores "ReadConflictError". It lead to inconsistencies in
the session maintenance data. Therefore, in Zope 2.6 and above,
a standard ZODB connection is used and session access can cause
a "ReadConflictError".

However, a "ConflictError" ("ReadConflictError" by extension)
"crashes" the request (it is aborted and automatically restarted)
but *not* the object that caused the conflict.
Therefore, a "ReadConflictError" does never crash a session.

 > NOTE: I had mounted SESSION to the TempFolder and just to the ZODB

??? What ????

 . So in both 
 > cases it sometimes just disappears and browser id changes. I haven't stored 
 > into the session things like huge objects or so. If anybody experienced the 
 > same problem, plese let me know how to fight this.

This looks like normal session behaviour.
They are timed out (and deleted) after a (configurable) inactivity

Please read the "session" section in the Zope Book (2.6 edition),
for details.


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