Problem : Application run out of memory while processing image I/O.

Question

Hi,
I have coded an application (utility) for creating scaled (JPEG) images (thumb nails) and writing (saving) them to files. I tried this with both imageio package of jdk1.4 and com.sun.image.codec.jpeg.* classes of earlier version. Application works with both versions but when I execute it for more (say more than 10 images) images, system becomes very slow and application starts throwing a memory related (OutOfMemoryError) error. Is it that objects of java image related classes consume too much memory ? How to solve this problem ? (My system run P4 processor with 256 MB RAM).
Awaiting solution,
Thanx and regards,
IB

Answer 1

So I am not alone in this...
I wrote the jpeg thumbnail generating code over a year ago and now when I am ready to use it in the finished app. I noticed that each process (as monitored using Forte 3's execution window) that instantiates a new ImageIcon object is never killed by the JVM. As more and more processes are started for distinct tasks they build up endlessly. Here's the method which is almost identical to the test code provided in sun's tutorial for generating thumbnails from jpeg and gif image files (http://developer.java.sun.com/developer/TechTips/1999/tt1021.html) :
public boolean createThumbImage(int maxDim) throws EntegraEntityException {
     * Reads an image in a file and creates
     * a thumbnail in another file.
     * @param this.getImagePath() The name of image file.
     * @param thumb The name of thumbnail file. 
     * Will be created if necessary.
     * @param maxDim The width and height of
     * the thumbnail must
     * be maxDim pixels or less.
       String thumbsource =  this.path + this.filename;
       String thumbdest = this.path + "thumbs_" + maxDim + File.separator/*"\\"*/ + Utilities.replaceString(Utilities.replaceString(this.filename," ","_","ALL").trim(),"[.][a-zA-Z]*",".jpg","ALL");
   //  System.out.println("thumbsource in createthumbimage(): " + thumbsource + "\n");
   //  System.out.println("thumbdest in createthumbimage(): " + thumbdest + "\n");
        try {
            // Get the image from a file.
            java.awt.Image inImage = new ImageIcon (thumbsource).getImage();
            // Determine the scale.
         double scale = (double)maxDim/(double)inImage.getHeight(null);
            if (inImage.getWidth(null) > inImage.getHeight(null)) {
                scale = (double)maxDim/(double)inImage.getWidth(null);
            // Determine size of new image.
            //One of them
            // should equal maxDim.
            int scaledW = (int)(scale*inImage.getWidth(null));
            int scaledH = (int)(scale*inImage.getHeight(null));
            // Create an image buffer in
            //which to paint on.
            BufferedImage outImage =
              new BufferedImage(scaledW, scaledH,
                BufferedImage.TYPE_INT_RGB);
            // Set the scale.
            AffineTransform tx =
              new AffineTransform();
            // If the image is smaller than
            //the desired image size,
            // don't bother scaling.
            if (scale < 1.0d) {
                tx.scale(scale, scale);
            // Paint image.
            Graphics2D g2d =
             outImage.createGraphics();
            g2d.drawImage(inImage, tx, null);
            g2d.dispose();
            // JPEG-encode the image
            //and write to file.
            Utilities.fileMakeDirs(this.path + "thumbs_" + maxDim + File.separator/*"\\"*/);
            Utilities.fileMakeFile(thumbdest);
            OutputStream os =
             new FileOutputStream(thumbdest);
            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);
            encoder.encode(outImage);
            os.close();
            return true;
        } catch (IOException e) {
            throw new EntegraEntityException("IO exception creating thumbnail for Image object ID: " + this.getId() + " ::",e);
        } catch (EntegraFileIOException fi) {
            throw new EntegraEntityException("File IO exception creating thumbnail for Image object ID: " + this.getId() + " ::",fi);
    //    return false; //Never reached. Since it doesn't live in the "try" block but must be here to ensure method body gets a return value.
}:During my troubleshooting of the method execution yesterday I discovered that the stuck process only occurs as a consequence of the line shown in bold below :
java.awt.Image inImage = new ImageIcon (thumbsource).getImage();
:this indicates to me that there is something wrong with how either the Image object or the ImageIcon file resources are allocated. At first I tried using the "flush()" method of the java.awt.Image class to release the resources to no avail, later I was able to confirm that the error does not occur for the default constructor of ImageIcon only for the one that specifies the source path (as shown in the line above) this indicates that a fileIO stream is being created and probably not being released inside ImageIcon or Image, but since that stream is probably private to those core classes we can't access it to close() it properly. I sure hope I am wrong on this or there is an alternative to using these classes..
Please let me know if any of you have other ideas on how to quash this bug or can otherwise find flaws in my logic for it's occurance.
Regards,
Sent2null