Loading ...
Sorry, an error occurred while loading the content.
 

Re: Apache::Session::Store::Postgres FOR UPDATE problems [OT]

Expand Messages
  • Kjetil Kjernsmo
    ... Thank you all for the follow-up! Indeed the problem here is that we re not destroying the object properly. It is the classical untie trap that we re in,
    Message 1 of 6 , May 2, 2005
      On tirsdag 03 mai 2005, 00:40, Michael Schout wrote:
      > Jeffrey W. Baker wrote:
      > > It is possible that the FOR UPDATE is spurious.  It signals to the
      > > database system that this transaction intends to write that row.
      > >  With PostgreSQL's MVCC transaction isolation system, it's probably
      > > not necessary and may be causing problems.
      >
      > It definately *is* necessary if you want to ensure that only one
      > process has access to your session data at a time.  MVCC will prevent
      > a second client from WRITING to the same row, but it will not block
      > it from reading the row.

      Thank you all for the follow-up!

      Indeed the problem here is that we're not destroying the object
      properly. It is the classical untie trap that we're in, described in
      the Camel Book. However, neither of us has sufficient understanding of
      the code, and of tied hashes, I suppose, to really track down the
      issue. There really isn't any $foo = \%session in there, but we're
      calling the handler from the invalidate method, which is most likely
      the source of the problem.

      It sort of works, with a few quirks, with DB_File as backend store, but
      unsurprisingly, it doesn't with Pg. So, for now, I have filed a bug
      against my own package, so that at least my users will have a fair
      chance to understand what's going on:
      http://rt.cpan.org/NoAuth/Bug.html?id=12473

      If anyone wants to have a look, it is certainly appreciated, otherwise,
      we'll just have to return to it $later.

      Cheers,

      Kjetil
      --
      Kjetil Kjernsmo
      Programmer/Astrophysicist/Skeptic/Ski-orienteer/Orienteer/Mountaineer
      kjetil@... webmaster@... editor@...
      Homepage: http://www.kjetil.kjernsmo.net/ OpenPGP KeyID: 6A6A0BBC
    Your message has been successfully submitted and would be delivered to recipients shortly.