RE: [Webware-discuss] dealing with expensive resources and thread -safety

[Geoffrey T. <gta...@na...>]

Ian Bicking wrote:
> Sessions can be accessed from multiple threads, though usually that
> would only happen when a browser was downloading dependent
> files (e.g.,
> images), that were also served off WebKit.  But you still
> don't want to
> put these in the session, because they aren't pickleable, and the
> session persists over restarts by using pickle.


It can also easily happen if someone clicks on a button or link twice, or if
they click on one link and then on another before the first one has
responded.  This is more likely if some of your servlets take a bit of time
to respond.  We've run into an interesting issue where someone requests a
servlet that takes a while to respond, then clicks on our logout button
before the slow servlet has responded.  Our logout code clears the session,
which sometimes causes bugs in the long-running servlet which assumes that
certain values are still in the session.  These bugs can cause tracebacks
that get emailed to the administrator but never show up in the user's
browser.

- Geoff