[Zope] conflicts, sessions, and programming best practices guidelines

[Chris McDonough]

On Nov 17, 2005, at 4:46 AM, Dennis Allison wrote:

>
> Thank Chris, good pointsB.
>
> The session variable timeout is currently several hours as requird  
> by our
> application. The timeout resolution remains at its default value.

Making the resolution higher has been observed to reduce conflicts  
(see dunny's chart).

> I have
> not dorked with disabling the inband housekeeping.  I don't see how it
> would impact on our problem.  Am I missing something?

Turning off inband housekeeping has the potential to reduce the  
numnber of conflicts because less work is done during normal  
sessioning operations.  Instead of doing the work to figure out  
whether it needs to clean up after itself during "normal" operations  
it relies on an external process.
>

> I suppose I could do a custom p_resolveConflict since the vast  
> majority
> of conflicts are are non-conflicting and actual conflicts are fairly
> easy to identify.

I couldn't know one way or another, but if you believe so...

>
> Still, on the whole, I think we have to refactor our programs to  
> minimize
> the opportunities for conflicts as well as tuning the mechanism. As a
> temporary workaround, I'm backing out of the shared temporary  
> storage in
> favor of a local temp storage.  That should make things a bit better.

Good idea...

- C


>
>
> On Wed, 16 Nov 2005, Chris McDonough wrote:
>
>> Changing the architecture will likely get you the most bang but note
>> also that there are a few knobs that you can turn on the transient
>> object container UI that may limit the number of conflicts (in the
>> temp_folder/session_data_container):
>>
>> - "Data object timeout value" -- the timeout value in minutes.. make
>> this higher.
>>
>> - "Timeout resolution" -- the timeout resolution in seconds.. make
>> this higher.
>>
>> You can also turn off "inband housekeeping" of session data by
>> calling the method "disableInbandHousekeeping" on a transient object
>> container.  At that point, sessions will continue to work properly
>> but "old" session data won't be garbage collected and you will need
>> to do this every so often by calling the "housekeep" method on  TOC.
>>
>> See this written by dunny about conflicts and sessions (although this
>> was written before MVCC):
>>
>> http://www.plope.com/Members/dunny/conflicts/view
>>
>> HTH,
>>
>> - C