[Zope-dev] session concurrency

[santi at zetadb.com]

> I have never seen disappearing sessions -- but I must admit
> that we use our own session implementation - deriving from
> Zope's session but getting rid of the over-complex session
> management code.

I've not explained very well.  Session object doesn't disappears, just
some data in session object does it.

> (they occur non-deterministically, they are
> extremely difficult to reproduce and analyse).

> As said: The advertised behaviour when several requests modify
> the same session object is that all but the first committing request get
> a "ConflictError" and are retried. Everything else is a bug.
>

I'm agree that, if it works fine, the retrieing request method is a good
solution.  My problem is quasi deterministic, it crashes most of times :-(
 I will try to provide a example.zexp when entering the bug so it could be
easier to reproduce.

> Another note: it is known (though we do not yet fully understand why)
> that sessions behave non-deterministically (disappear, revert to old
> values) when they are read/written in "standard_error_message" (Zope's
> error handling hook for failing requests).
>

I'm not using SESSION in standard_error_message, but symptoms are very
similar.

Santi Camps