[rules-users] Drools fusion memory management

[Chris Richmond]

Hello,

 

I wanted to ask this question in a separate email so as to keep each email
to one topic for easier thread following.  Let me know if you prefer
multiple questions per email next time.

 


I am using Drools fusion basically with some success where I am at this
point only running some aggregates and calling some java functions when a
running average over the last 1 minute or so drops below a certain value.   

 

The sources for those values come from objects I am injecting into memory
space, but I am not specifically calling retraction code since it is my
understanding that I can set the policy in the rule file for how long to
hold objects in memory.  So for example I have this rule which simpoly
outputs to out when the average goes above 100 for the last 10 items(you can
tell I created mine based on the stock ticker).  It seems to be working, but
I have some questions to ensure I understand before moving forward.

 

 

So below the "declare MyObject" with assigning it role event with a default
expiration of 2 minutes.  Is my undertanding correct that fusion will
disregard thos objects that are injected without me having to take any other
action?  

 

Also, in my "show averages" rule below, if I did ont have the "declare
MyObject" delcaration with expiration policy set, would fusion automatially
throw away MyObjects older than the last 10  based on my rule no longer
needing them?    If it would, then which takes priority, the expires
declaration for MyObject or the no longer needed by my aggregate rule below.
I am assuming that the rule would keep them beyond 2 minutes it it was
necessary, but is this correct?  If the rule as written would not
automatically remove objects from memory space, then is there something I
could do to tell the rule to do so when it is no longer needed by my
aggregate?

 

Thanks,


Chris

 

 

 

 

 

 

<imports removed>

 

 

# default dialect for the semantic code will be MVEL

dialect "mvel"

 

# tells the engine that a object instance will assume the

# role (semantics) of events and that the default retention 

# policy will be 2 minutes 

declare MyObject

    @role( event )

    @expires( 2m )

end 

 

 

rule "show averages"

when

 

      $n : Number( doubleValue > 100 ) from accumulate (

 

            

      

            $stat:MyObject($bc: byteCount, srcIPAddress == "10.5.0.4") over
window:length(10) from entry-point "MyObject stream",

 

            average( $bc )

            

        ) 

        

        

then

 

    System.err.println("average: " + $n)

end 

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