FULL PRODUCT VERSION :
java version "1.6.0_23"
Java(TM) SE Runtime Environment (build 1.6.0_23-b05)
Java HotSpot(TM) 64-Bit Server VM (build 19.0-b09, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Linux bud8 2.6.18-194.17.1.el5 #1 SMP Wed Sep 29 12:50:31 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
If you use render text from multiple threads, you seem to be guaranteed to get a NullPointerException eventually.

Three other users report similar symptoms in comments at the end of bug 6359722, but that bug (a) appears to have originated as a different issue, and (b) is already closed.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the attached test case. It may take some minutes, but will inevitably throw an NPE similar to the one below.


ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NullPointerException
at sun.font.FileFontStrike.getCachedGlyphPtr(FileFontStrike.java:470)
at sun.font.FileFontStrike.getSlot0GlyphImagePtrs(FileFontStrike.java:436)
at sun.font.CompositeStrike.getGlyphImagePtrs(CompositeStrike.java:97)
at sun.font.GlyphList.mapChars(GlyphList.java:254)
at sun.font.GlyphList.setFromString(GlyphList.java:226)
at sun.java2d.pipe.GlyphListPipe.drawString(GlyphListPipe.java:53)
at sun.java2d.pipe.ValidatePipe.drawString(ValidatePipe.java:147)
at sun.java2d.SunGraphics2D.drawString(SunGraphics2D.java:2753)
at com.test.FileFontStrikeNPE.renderText(FileFontStrikeNPE.java:47)
at com.test.FileFontStrikeNPE.run(FileFontStrikeNPE.java:20)
at java.lang.Thread.run(Thread.java:662)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;

public class FileFontStrikeNPE implements Runnable {

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            new Thread(new FileFontStrikeNPE(), "Thread_" + i).start();
        }
    }

    public void run() {
        try {
            renderText();
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

    private void renderText() {
        BufferedImage image = new BufferedImage(200, 200, BufferedImage.TYPE_INT_ARGB);
        Graphics2D graphics = image.createGraphics();
        int fontSize = (int) (Math.random() * 20) + 1;
        graphics.setFont(new Font(Font.SANS_SERIF, Font.PLAIN, fontSize));
        graphics.translate(100, 100);

        double rotation = 0.0;
        String label = "Hello world!";

        while (rotation < 100000) {
            FontMetrics fontMetrics = graphics.getFontMetrics(graphics.getFont());
            int width = fontMetrics.stringWidth(label);
            int y = fontMetrics.getAscent() / 2;

            AffineTransform originalTransform = graphics.getTransform();
            Shape originalClip = graphics.getClip();

            graphics.rotate(rotation);
            graphics.translate(-width / 2, y);
            graphics.drawString(label, 0, 0);
            graphics.setTransform(originalTransform);
            graphics.setClip(originalClip);
            rotation += 1.0;
        }
    }
}
---------- END SOURCE ----------