You're right. A simple and accurate explanation of what's happening
is that the current implementation of no-loop blocks all activations
of a rule during the time that rule is firing. For a single-threaded
system, this is correct, but for a multi-threaded system it's
surprising, to say the least.
Thanks for pointing this out; it should be simple to give Jess 7.1
the expected behavior.
On Jan 17, 2008, at 6:19 AM, Chen, Yixi wrote:
<<JessMultiThreadAssert.java>> <<JessMultipleAssertRun.clp>>
Dear all,
I am working with Jess under multiple threads environment. More
than two threads will assert facts and run the engine at the same
time. The system works well with rules without no-loop declaration.
But if a rule contains no-loop declaration, sometimes it can not
activate and fire correctly with several facts.
I write two files to show what I found. I both attach them and
paste their content in the mail body. The java file open two
threads, EvenThread assert facts with value 2,4,6,8,10; OddThread
assert facts with value 1,3,5,7,9. In my clp file, only one rule
written, so it should fire 10 times for the 10 facts. But actually,
it may fire 8, 9 or 10 times. If I remove the no-loop declaration
(in my sample it is not required, I only use it to explain my
issue), the rule exactly fire 10 times. Why?
My jess version is 7.0.
Thank you
// java file start. My java Class, enable two threads to assert
facts and run engine
public class JessMultiThreadAssert {
public static void main(String[] args) {
Rete rete = new Rete();
OddThread odd = new OddThread(rete);
EvenThread even = new EvenThread(rete);
try{
rete.batch("JessMultipleAssertRun.clp");
}catch (Exception e){
e.printStackTrace();
}
even.start();
odd.start();
}
}
/**
* assert facts with even number, from 2 to 10
* */
class EvenThread extends Thread
{
private Rete rete = null;
public EvenThread(Rete rete){
this.rete = rete;
}
public void run(){
try{
long i=2;
while(i<=10){
rete.eval("(assert (item1 (value "+i
+")))");
rete.run();
i+=2;
}
}catch (Exception e){
e.printStackTrace();
}
}
}
/**
* assert facts with odd number, from 1 to 9
* */
class OddThread extends Thread
{
private Rete rete = null;
public OddThread(Rete rete){
this.rete = rete;
}
public void run(){
try{
long i=1;
while(i<=10){
rete.eval("(assert (item1 (value "+i
+")))");
rete.run();
i+=2;
}
}catch (Exception e){
e.printStackTrace();
}
}
}
// java file end
;;;;;;;;;;; clp file start, my JessMultipleAssertRun.clp file
(defglobal ?*num* = 0)
(deftemplate item1 (slot value (type Long)))
(defrule many-matches
(declare (no-loop TRUE) )
?fact1<-(item1 (value ?a&:(> ?a 0) ))
=>
(modify ?fact1 (value -1))
(bind ?*num* (+ ?*num* 1))
(printout t ?*num* crlf)
)
(reset)
;;;;;;;;;; clp file end
<JessMultiThreadAssert.java><JessMultipleAssertRun.clp>
---------------------------------------------------------
Ernest Friedman-Hill
Informatics & Decision Sciences Phone: (925) 294-2154
Sandia National Labs FAX: (925) 294-2234
PO Box 969, MS 9012 [EMAIL PROTECTED]
Livermore, CA 94550 http://www.jessrules.com
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