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<DIV><FONT color=#0000ff face=Verdana size=2><SPAN class=175012121-22032010>It
will be 1 trillion activations unless there is an index on the "id" property of
the classes. If the right index is used, it should scan all objects of one
class, and through indexes figure out the corresponding related objects of other
classes. I am not sure if we can somehow tell rete to create indexes on certain
attributes. I read a nice article on indexing in drools, which mentioned
about Rete Beta node indexing. I am not sure if this is what drools is doing
internally. Any suggestions/ideas?</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Verdana size=2><SPAN class=175012121-22032010></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Verdana size=2><SPAN class=175012121-22032010><A href="http://blog.decaresystems.ie/index.php/2008/02/24/rete-nodes-indexing-in-drools/">http://blog.decaresystems.ie/index.php/2008/02/24/rete-nodes-indexing-in-drools/</A></SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Verdana size=2><SPAN class=175012121-22032010></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Verdana size=2><SPAN class=175012121-22032010>Thanks,</SPAN></FONT></DIV>
<DIV><SPAN class=175012121-22032010><FONT color=#0000ff face=Verdana size=2>Malay</FONT></SPAN></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> rules-users-bounces@lists.jboss.org
[mailto:rules-users-bounces@lists.jboss.org] <B>On Behalf Of </B>Wolfgang
Laun<BR><B>Sent:</B> Monday, March 22, 2010 3:17 PM<BR><B>To:</B> Rules Users
List<BR><B>Subject:</B> Re: [rules-users] Drools stateless session
question<BR></FONT><BR></DIV>
<DIV></DIV>You have calculated it correctly: 10000 A's * 10000 B's * 10000 C's
results in 1,000.000,000.000 activations, which is (almost) a mind-boggling
figure. I can't imagine what benefit this trillion of activations is going to
have for your application. Even if you have the memory for all that, assuming
that firing of one of these activations and processing of the RHS statements can
be done in one microsecond, this is going to take days to complete, and it'll
create a huge data set of A/B/C combinations for just this one rule.<BR><BR>Are
you sure that you are on the right track?!<BR><BR>-W<BR><BR><BR>
<DIV class=gmail_quote>On Mon, Mar 22, 2010 at 7:46 PM, Shah, Malay <SPAN dir=ltr><<A href="mailto:Malay.Shah@morganstanley.com">Malay.Shah@morganstanley.com</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE class=gmail_quote style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">Thanks
W. Let me give you a rule that is causing us issues. Lets say we have
classes:<BR><BR>class A<BR>{<BR> int a;<BR>
String id;<BR>}<BR>Class B<BR>{<BR>
int b;<BR> String id;<BR>}<BR>Class
C<BR>{<BR> int c;<BR>
String id;<BR>}<BR><BR>and we have 12000 objects each. These objects are
connected using "id" property.<BR>If the rule is something like:<BR><BR>Rule
"ABC"<BR>When<BR> Obj_A: A(a!=1)
//10000 object "A" instances
have a!=1<BR> Obj_B: B(b!=2,Obj_A.id = id)
//10000 object "B" instances have
b!=2<BR> Obj_C: C(c!=3,Obj_B.id = id)
//10000 object "C" instances have
c!=3<BR>Then<BR> System.out.println("Rule
fired");<BR>End<BR><BR>This means there would be a join between A, B and C
objects (10000 A's * 10000 B's * 10000 C's) to evaluate the rule. In such
cases, we see very high org.drools.reteoo.LeftTuple object count while
profiling the app. Is there a way to make the rete algo perform this
evaluation serially, or in batches, or use some object swapping mechanism to
limit creation of intermediate LeftTuple objects? Would the rete algo use
indexes in this case? That would potentially decrease these intermediate
objects. Currently, we use 5G heap and that is not enough for evaluating this
rule.<BR><BR>Regards,<BR>Malay<BR><BR>-----Original Message-----<BR>From: <A href="mailto:rules-users-bounces@lists.jboss.org">rules-users-bounces@lists.jboss.org</A>
[mailto:<A href="mailto:rules-users-bounces@lists.jboss.org">rules-users-bounces@lists.jboss.org</A>]
On Behalf Of Wolfgang Laun<BR>Sent: Monday, March 22, 2010 12:39 PM<BR>To:
Rules Users List<BR>Subject: Re: [rules-users] Drools stateless session
question<BR><BR>You have misunderstood the documentation. All eight items in
the enumeration you cite from are steps performed internally by the Drools
engine. The only thing you have to do is request sequential
mode.<BR><BR>Without an idea about the rule set you are using it's difficult
to advise how to reduce memory consumption.<BR><BR>-W<BR><BR><BR>2010/3/22
Shah, Malay <<A href="mailto:Malay.Shah@morganstanley.com">Malay.Shah@morganstanley.com</A>>:<BR>>
Hi All,<BR>><BR>> We have an application that uses drools stateless
session over a set<BR>> of 35000 objects (taking about 40 MB heap) of
different types. During<BR>> profiling, I saw that for rules that perform
joins between two huge<BR>> object types data sets, lots of
org.drools.reteoo.LeftTuple objects<BR>> causing out of memory errors. We
are using 5G heap, and have set<BR>> property drools.sequential=true too.
Is there any way we can decrease<BR>> the memory usage while applying these
rules? Drools documentation<BR>> mentions for sequential mode, we
should do the following, some of<BR>> them I am not sure how to
set:<BR>><BR>><BR>> Turn off all node memories, except the
right-input Object memory.<BR>><BR>> Disconnect the LeftInputAdapterNode
propagation, and have the Object<BR>> plus the Node referenced in a Command
object, which is added to a list<BR>> on the WorkingMemory for later
execution.<BR>><BR>> Assert all objects, when all assertions are
finished and thus<BR>> right-input node memories are populated check the
Command list and execute each in turn.<BR>><BR>> <A href="http://downloads.jboss.com/drools/docs/4.0.7.19894.GA/html_single/inde" target=_blank>http://downloads.jboss.com/drools/docs/4.0.7.19894.GA/html_single/inde</A><BR>>
x.html#d0e1295<BR>><BR>> Do we need to set some properties in
RuleBaseConfiguration to make<BR>> sure node memories are switched off? It
would be great if we can<BR>> somehow decrease the memory usage for
stateless sessions? Has anybody<BR>> come across such memory issues before?
Correct me if I am wrong, but I<BR>> think 35000 objects is not a lot of
data for causing such issues.<BR>><BR>> Thanks<BR>> Malay<BR>>
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