Re: [CZT-Users] [CZT-Devel] ZLive limitations and problem buildn with maven

[Pablo R. M. <rod...@gm...>]

Hi Mark,

I am back again to tell you about a new problem I am facing using ZLive. I
attempted to use ZLive intensively, running a number of threads that iterate
and call the evalPred() method over approximately 500 predicates. Since each
thread creates a new ZLive object, and each ZLive object consumes a
considerable amount of memory, I had to run my java app with a "-Xmx500m"
parameter, or someone similar, in order to give more memory to the JVM (Java
Virtual Machine).

Anyway, some executions finish well but others crash my JVM:

java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)



I have reproduced the problem with the following program, which try to
evaluate the same predicate 500 times in 12 threads:



//**************************************************
package pruebas;

import java.io.*;
import java.util.*;

import net.sourceforge.czt.z.ast.Pred;
import net.sourceforge.czt.animation.eval.*;
import net.sourceforge.czt.typecheck.z.*;


public class EvalTest{
    public static void main(String[] args) {

        for(int i=0; i<12; i++){
            (new ThreadTest(i)).start();
        }
    }
}


class ThreadTest extends Thread{

    private int threadNumber;
     private ZLive zLive = new ZLive();

    public ThreadTest(int threadNumber){
        this.threadNumber = threadNumber;
    }

    public void run(){
        try{
             TextUI textUI = new TextUI(zLive, new PrintWriter(System.out,
true));

            String string = "0 \\in \\dom \\{ ( 1 , \\negate 1 ) , ( 2 ,
\\negate 1 ) \\} \\land 1 > 0 \\land 1";
            string += " \\leq \\{ ( 1 , \\negate 1 ) , ( 2 , \\negate 1 )
\\} 1 \\land";
            string += "\\{ ( 1 , \\negate 1 ) , ( 2 , \\negate 1 ) \\} 0 >
10000";


            Pred pred = (Pred) textUI.parseTerm(string, new
PrintWriter(System.out, true));
            List<? extends ErrorAnn> errors =
                TypeCheckUtils.typecheck(pred, zLive.getSectionManager(),
false, zLive.getCurrentSection());
             if(errors.size() >0)
                return;

            for(int i=0; i<500; i++){
                System.out.println("Thread: " + threadNumber + " Iteración:
" + i) ;
                zLive.evalPred(pred);
            }

        }
        catch(Exception e){
            e.printStackTrace();
        }
    }
}

//**************************************************






In most executions, after printing a number of lines the JVM crashes and the
error report is:


#
# An unexpected error has been detected by Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x06302f07, pid=7736, tid=3047447440
#
# Java VM: Java HotSpot(TM) Client VM (1.6.0_03-b05 mixed mode, sharing)
# Problematic frame:
# V  [libjvm.so+0x302f07]
#
# An error report file with more information is saved as hs_err_pid7736.log
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
#
Cancelado (core dumped)


I have attached hs_err_pid7736.log.


I believe it could be a JVM bug. What do you think?


Cheers,

Pablo