Gary Poster wrote at 2007-6-13 17:12 -0400:
>2) The second problem is less serious, but still evidenced in our
>production apps, and representative of a class of problems I've
>wanted to address for awhile. zope.app.session writes to a session
>if it is accessed
>seconds after a session data was last updated, to indicate that the
>session is still active. It scribbles time.time(). The default
>resolution is 50 minutes.
>Given a page that makes several requests, it is very easy (speaking
>as an observer of server logs) to generate conflict errors in a
>modern browser that parallelizes requests for resources on a page,
>once the time comes to update.
>I'd like to make a module that contains two very simple classes,
>similar to BTrees.Length, that are persistent objects that hold a
>single value, and have simple resolution policies. One would always
>prefer the greater or equal value of the two new values, and the
>other would prefer the lesser or equal value of the two new options.
>The session code, as well as other similar expiration-based use
>cases, could use these classes to store the time.time() float--the
>session code would use the max variant.
I doubt that this will help you much (we use such an implementation
for many years and still see quite often session related conflicts).
Sessions are often in a temporary storage and this has a very
For conflict resolution, a sufficiently large history is
necessary (long enough to load the old state again).
Very often, the available history is not long enough to
resolve a conflict.
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