Bug 41219

Sometimes stacktraces of the exceptions seem to mysteriously disappear. After 
invesigation I noticed thatThrowableInformation.VectorWriter looks potentially 
unrobust, since it's making strong assumptions of what methods of the 
PrintWriter API Throwable is using for printing its' stacktrace.

For example, if Throwable uses some "write(int)" method then stacktrace goes 
appearently into /dev/null.

It's completely possible that some sub-class of Throwable overrides 
printStackTrace() -logic, so API shouldn't make assumptions based into 
implementation details inside Throwable (Throwable itself could change also 
logic, like has happened earlier).

This issue reduces reliability of Log4J considerably.

PROOF:
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package org.kari;

import java.io.PrintWriter;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Logger;

public class ThrowableTest {
    
    public static final class ThrowableFail extends Throwable {

        @Override
        public void printStackTrace(PrintWriter s)
        {
            super.printStackTrace(s);
            s.println("LOST-START");
            // Following output is lost
            for (int i= 0; i < 100; i++) {
                s.print('a');
            }
            s.println("LOST-END");
        }
        
    }
    
    public static void main(String[] args) {
        BasicConfigurator.configure();
        Logger LOG = Logger.getLogger(ThrowableTest.class);
        LOG.info("Test", new ThrowableFail());
    }

}
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