Name: boT120536 Date: 01/22/2001


java version "1.2.2"
Classic VM (build JDK-1.2.2-W, native threads, symcjit)



I have a static instance of SimpleDateFormat, and I have 2 threads, each
using private clones of this instance. One thread uses the parse() method to
convert a String to a Date, the other uses the format method to convert a Date
to a String. Even though each thread has a clone of the SimpleDateFormat
instance, the results of the parse and/or format are corrupted after a few
seconds due to apparent concurrent conflicts. The following code demonstrates
the problem:

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

public class SDFClone {

    static boolean stopped_ = false;
    static final String TIME_STRING = "2000/11/18 00:01:00";
    static final String TIME_STRING_FULL = "11/18/2000 00:01:00 PST";
    static final long UTC_LONG = 974534460000L;
    static SimpleDateFormat sdf_ = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

    public SDFClone(String[] args) {
        stopped_ = false;
        DateParseThread d1 = new DateParseThread();
        DateFormatThread d2 = new DateFormatThread();
        d1.start();
        d2.start();
        try { Thread.sleep(100000); } catch (Exception e) {}
        stopped_ = true;
    }

    class DateParseThread extends Thread {
        public void run () {
            SimpleDateFormat sdf = (SimpleDateFormat)SDFClone.sdf_.clone();
            
            try {
                int i = 0;
                while (! SDFClone.stopped_) {
                    Date date =sdf.parse(SDFClone.TIME_STRING);
                    long t = date.getTime();
                    i++;
                    if (t != SDFClone.UTC_LONG ) {
                        throw new ParseException("Error: " + i + " (" +sdf.format(date) + ") " + t + " != " + SDFClone.UTC_LONG, 0);
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
    }
    class DateFormatThread extends Thread {
        public void run () {
            SimpleDateFormat sdf = (SimpleDateFormat)SDFClone.sdf_.clone();
            int i = 0;
            while (! SDFClone.stopped_) {
                i++;
                String s = sdf.format(new Date(974534460000L));
                if (!s.equals(SDFClone.TIME_STRING)) {
                    System.err.println("Date Error: " + i + " " + s + " != " +SDFClone.TIME_STRING_FULL);
                    System.exit(1);
                }
            }
        }
    }

    public static void main (String[] args) {
        new SDFClone(args);
    }
}

This defect caused corruption in parsed input dates in an accounting product.
The result was that incorrect resource usage was attributed to users - very bad
for an accounting product!!!
(Review ID: 115583)
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