Re: [rules-users] Drools stateless session question
Thanks W. Let me give you a rule that is causing us issues. Lets say we have classes:
class A
{
int a;
String id;
}
Class B
{
int b;
String id;
}
Class C
{
int c;
String id;
}
and we have 12000 objects each. These objects are connected using "id"
property.
If the rule is something like:
Rule "ABC"
When
Obj_A: A(a!=1) //10000 object "A" instances have a!=1
Obj_B: B(b!=2,Obj_A.id = id) //10000 object "B" instances have b!=2
Obj_C: C(c!=3,Obj_B.id = id) //10000 object "C" instances have c!=3
Then
System.out.println("Rule fired");
End
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.
Regards,
Malay
-----Original Message-----
From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On
Behalf Of Wolfgang Laun
Sent: Monday, March 22, 2010 12:39 PM
To: Rules Users List
Subject: Re: [rules-users] Drools stateless session question
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.
Without an idea about the rule set you are using it's difficult to advise how to
reduce memory consumption.
-W
2010/3/22 Shah, Malay <Malay.Shah(a)morganstanley.com>:
Hi All,
We have an application that uses drools stateless session over a set
of 35000 objects (taking about 40 MB heap) of different types. During
profiling, I saw that for rules that perform joins between two huge
object types data sets, lots of org.drools.reteoo.LeftTuple objects
causing out of memory errors. We are using 5G heap, and have set
property drools.sequential=true too. Is there any way we can decrease
the memory usage while applying these rules? Drools documentation
mentions for sequential mode, we should do the following, some of
them I am not sure how to set:
Turn off all node memories, except the right-input Object memory.
Disconnect the LeftInputAdapterNode propagation, and have the Object
plus the Node referenced in a Command object, which is added to a list
on the WorkingMemory for later execution.
Assert all objects, when all assertions are finished and thus
right-input node memories are populated check the Command list and execute each in turn.
http://downloads.jboss.com/drools/docs/4.0.7.19894.GA/html_single/inde
x.html#d0e1295
Do we need to set some properties in RuleBaseConfiguration to make
sure node memories are switched off? It would be great if we can
somehow decrease the memory usage for stateless sessions? Has anybody
come across such memory issues before? Correct me if I am wrong, but I
think 35000 objects is not a lot of data for causing such issues.
Thanks
Malay
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