Hi all,
I've pointed out before that another alternative is to use just one
Rete object and make sure that all the session-specific facts contain
a session-identifying slot. Then this one Rete can simultaneously
reason about all the clients' data.
The 12 megabytes of Rete network consists mostly of complex indexed
data structures used to collect partial pattern matches (and probably
the matches themselves, too.) These would of course all need to be
duplicated for each thread in Bob's proposed solution (in which
session-specific information would be made thread-local.)
Note that you can reduce the size of the Rete data structures,
possibly at the expense of some speed, using either the
set-node-index-hash function or the node-index-value defrule
declaration. These can reduce the size of some fixed arrays used in
each Rete join node. Try small prime values like 7 or 11 to see what
impact this has for you. it will have the largest impact on a system
with many rules and few partiual matches.
In any case, using fairly generous numbers for sizes, assuming three
CEs per rule, ten tests per CE, 200 rules, I get about 1.4 MB for the
Rete network and about 25K for the Rete object itself. I think Bob's 12
MB figure must include partial matches as well, which obviously would
need to be session-specific.
I'll do a bit more investigating myself just to make sure there isn't
some massive memory hogging going on that I don't understand.
I think Bob Johnson wrote:
>
> Alan is correct. However, each of these instances is likely to be quite large.
> In our case, rule sets on the order of 100-200 rules,
> each Rete is roughly 12 megabytes each. Not to mention the time it takes to
> load the rules. I believe a threading solution is necessary for Jess to be
> practical in the (inter|intra)net server environment.
>
> What fraction of the Jess population intends to deploy in this configuration?
> Is this an urgent issue?
>
> Bob
>
>
> Alan Moore wrote:
>
> > Well, you should be able to detect a new session (see Session documentation)
> > and create a hashtable of Rete instances indexed by sessionId.
> >
> > > -----Original Message-----
> > > From: Fang Liu [mailto:[EMAIL PROTECTED]]
> > >
> > > HI, All:
> > > I have a servlet with one Rete instance on the server side.
> > > The problem
> > > is: usually there is one servlet instance per registered
> > > servlet name,
> > > which results in that all the clients have to share one Rete engine,
> > > which is not what I want. So I am considering to use thread or
> > > implement javax.http.SingleThreadModel to solve this problem.
> > > Does anybody know how to do that? Any comments or examples
> > > will be very
> > > appreciated.
---------------------------------------------------------
Ernest Friedman-Hill
Distributed Systems Research Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
Org. 8920, MS 9012 [EMAIL PROTECTED]
PO Box 969 http://herzberg.ca.sandia.gov
Livermore, CA 94550
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