RE: JESS: Run Rete Exception -- was: definstances & undefinstances

[Larner, Dan <[EMAIL PROTECTED]>]

> -----Original Message-----
> From: Ernest Friedman-Hill [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, January 30, 1999 12:26 PM
> To: [EMAIL PROTECTED]
> Subject: Re: JESS: Run Rete Exception -- was: definstances &
> undefinstances 
> 
> Hi Dan,

Hi!  Thanks for the quick response on this!

>...
> So, to fix it, it has to block modifications of the Rete network
> inbetween those two statements.  THis means synchronizing on the
> object returned by Rete.getCompiler(); so change the middle of
> Retract.call() in Funcall.java to look like this:
>...


Rats! Problem still there.

I changed to code to read
                  for (int i=1; i< vv.size(); i++) 
                  {
                          synchronized (engine.getCompiler())
                          {
                                  ValueVector f =
engine.findFactByID(vv.get(i).factIDValue());
                                  if (f == null)
                                          continue;

                                  // Undefinstance, if needed.
...

and also inserted println lines just before the exception throw
in jess/NodeNot2.java i.e. 
        System.out.println(lt);
        System.out.println(rt);

but the problem still occurs.  Here's the output along with a stack dump
and the exception printed.

JESS ABOUT to raise pumping rate of pump MAIN

[Token: size=1;sortcode=86;tag=ADD;negcnt=-1;facts=(tank <Fact-86> "MAIN"
FALSE <External-Address:ja
va.lang.Class> TRUE 197 TRUE <External-Address:jesspumps.Tank>);]

[Token: size=1;sortcode=85;tag=REMOVE;negcnt=0;facts=(warning <Fact-85> (low
"MAIN"));]

Rete Exception in routine NodeNot2::RunTestsVaryLeft.
  Message: Corrupted Negcnt (< 0) .
        at jess/NodeNot2.runTestsVaryLeft (NodeNot2.java:144)
        at jess/NodeNot2.runTestsVaryLeft (NodeNot2.java:120)
        at jess/NodeNot2.runTestsVaryLeft (NodeNot2.java:120)
        at jess/NodeNot2.runTestsVaryLeft (NodeNot2.java:120)
        at jess/NodeNot2.runTestsVaryLeft (NodeNot2.java:120)
        at jess/Node2.callNode (Node2.java:186)
        at jess/Node.passAlong (Node.java:136)
        at jess/Node1MTEQ.callNode (Node1.java:668)
        at jess/Node.passAlong (Node.java:136)
        at jess/Node1MTELN.callNode (Node1.java:708)
        at jess/Node.passAlong (Node.java:136)
        at jess/Node1TECT.callNode (Node1.java:479)
        at jess/Rete.processTokenOneNode (Rete.java:736)
        at jess/Rete.processToken (Rete.java:753)
        at jess/Rete._retract (Rete.java:575)
        at jess/Retract.call (Funcall.java:415)
        at jess/Funcall.simpleExecute (Funcall.java:336)
        at jess/Funcall.execute (Funcall.java:297)
        at jess/Funcall.execute (Funcall.java:196)
        at jess/Defrule.fire (Defrule.java:316)
        at jess/Activation.fire (Activation.java:55)
        at jess/Rete.run (Rete.java:1061)
        at jess/Rete.run (Rete.java:1039)
        at jess/HaltEtc.call (Funcall.java:1439)
        at jess/Funcall.simpleExecute (Funcall.java:336)
        at jess/Funcall.execute (Funcall.java:297)
        at jess/Funcall.execute (Funcall.java:196)
        at jess/Jesp.parseAndExecuteFuncall (Jesp.java:1386)
        at jess/Jesp.parseSexp (Jesp.java:161)
        at jess/Jesp.parse (Jesp.java:61)
        at jess/Rete.executeCommand (Rete.java:1091)
        at jesspumps/MainInJava.main (MainInJava.java:50)

Rete Exception in routine NodeNot2::RunTestsVaryLeft while executing rule
LHS: 
[NodeNot2 ntests=1 [Test2:
test=EQ;tokenIdx=0;leftIdx=2;leftSubIdx=-1;rightIdx=2;rightSubIdx=1]
 ;usecount = 1] while executing defrule raise-rate-if-low.
Message: Corrupted Negcnt (< 0)  at line 0:  ( run ) .


Let me know if there's any more info that would be helpful.


> Re: changes in ReflectFunctions outlines below: I don't think they're
> necessary or warranted. 

Hmmm.  It looked to me like there might be a problem if one
thread was executing Definstance.propertyChange while another thread
was calling Definstance.undefine (e.g. if propertyChange got 
executed right after undefine did its retraction and/or removal.)


-- Dan

Dan Larner, [EMAIL PROTECTED]
Xerox PARC, 3333 Coyote Hill Rd., Palo Alto, CA, USA 94304
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