Re: [Cgi-session-user] performance enhancement request

[Mark S. <ma...@su...>]

On Mon, 2007-05-14 at 15:21 +0200, Rhesa Rozendaal wrote:
> Hi,
> 
> Gearing up for a big upcoming event, where we expect many millions of new 
> visitors in the space of a few hours, I've been working on making our web app 
> as lean as possible.

Rhesa,

I like this idea and would welcome a patch to put update_atime() into
its own method. 

   Mark
> 
> It quickly became obvious that CGI::Session was choking our database, and the 
> reason for that is that it insists on flushing the session on every single 
> request (to store the new ATIME). That makes any attempt at caching futile, so 
> I've patched my local install to only accept changes to the ATIME once every 
> minute or so. As a result, the load on the master database has dropped 
> dramatically. It now also makes sense to use caching (in the form of 
> CGI::Session::Driver::memcached_mysql, in my case), so reads are spread over 
> many machines.
> 
> I'd like to see code for this included in the main distribution though, as 
> hacks like this have a tendency to break with upgrades. What I think is needed 
> for this, is to decouple the ATIME code at the end of load(), and put that in 
> its own method for easy overriding. Right now, load() is rather monolithic.
> 
> Attached is my hack, in case it helps anyone.
> 
> Rhesa
> 
> =pod
> 
> =head1 NAME
> 
> CGI::Session::LessAtime - Stops flush() on every request
> 
> =head1 USAGE
> 
>      use CGI::Session;
>      use CGI::Session::LessAtime;
>      # normal session code follows
> 
> =head1 LIMITATIONS
> 
> Only works with the default serializer.
> 
> =cut
> 
> package CGI::Session::LessAtime;
> 
> use strict;
> my $interval = 60; #seconds
> 
> use CGI::Session;
> use CGI::Session::Serialize::default;
> 
> {
>      no strict 'refs';
>      my $thaw_orig = \&CGI::Session::Serialize::default::thaw;
>      *CGI::Session::Serialize::default::thaw = sub {
>          my $ret = $thaw_orig->(@_);
>          $ret->{__SESSION_ORIG_ATIME} = $ret->{_SESSION_ATIME};
>          return $ret;
>      };
> 
>      my $load_orig = \&CGI::Session::load;
>      *CGI::Session::load = sub {
>          my $ret = $load_orig->(@_);
> 
>          if( defined $ret and _elapsed( $ret ) < $interval ) {
>             $ret->_unset_status( CGI::Session::STATUS_MODIFIED );
>          }
>          return $ret;
>      };
> 
>      sub _elapsed {
>          my $ret = shift;
>          return
>              $ret->{_DATA}{_SESSION_ATIME}
>              - $ret->{_DATA}{__SESSION_ORIG_ATIME}
>          ;
>      }
> }
> 
> 1;
> 
> 
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   Mark Stosberg            Principal Developer
   ma...@su...     Summersault, LLC
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