Name: js151677 Date: 08/19/2004


FULL PRODUCT VERSION :
java version "1.4.2_05"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_05-b04)
Java HotSpot(TM) Client VM (build 1.4.2_05-b04, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows 2000 [Version 5.00.2195]

A DESCRIPTION OF THE PROBLEM :
When displaying a bigger text in a JTextArea, the amount of used memory suddenly jumps up after calling setText().

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Try to load e.g. a 10MB big text file (usual size of our log files) with the attached code using the standard java.exe. Inspect the System.out and especially the memory usage.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Output of "used mem after setText()" should not or just slightly be bigger that output of "used mem before setText(): "
ACTUAL -
Output of "used mem before setText(): " is 10 MB, after adding the StringBuffer (7 MB), "used mem after setText(): " is suddenly 65 MB!
If you started java.exe without increasing memory (i.e. without -Xmx parameter), you probably get an OutOfMemoryError.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
        /**
         * Get text content of a file..
         *
         * @param file File to read text content from.
         * @param textArea JTextArea to set content of <i>file</i> with.
         * @throws IOException
         */
        private void readText(File file, JTextArea textArea) throws IOException {
            if (file != null && textArea != null) {
                BufferedReader br = null;
                ProgressMonitor pm = null;
                try {
                    textArea.setText("");
                    FileInputStream fis = new FileInputStream(file);
                    ProgressMonitorInputStream pmis = new ProgressMonitorInputStream(parent , "Reading " + file.getName(), fis);
                    pm = pmis.getProgressMonitor();
                    pm.setProgress(0);
                    pm.setMillisToDecideToPopup(0);
                    pm.setMillisToPopup(3000);
                    InputStreamReader isr = new InputStreamReader(pmis);
                    br = new BufferedReader(isr);

                    String line = null;
                    boolean first = true;

                    StringBuffer sb = new StringBuffer((int) file.length() + 1000);
                    while ((line = br.readLine()) != null) {
                        if (first) {
                            first = false;
                        } else {
                            sb.append("\n");
                        }
                        sb.append(line);
                    }
System.out.println("sb len: "+sb.length()); //7 MB
System.out.println("used mem before setText(): "+(Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory())); //10 MB
                    textArea.setText(sb.toString());
System.out.println("used mem after setText(): "+(Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory())); //65 MB!!!

                    textArea.setCaretPosition(textArea.getDocument().getLength()); //scroll down
                } catch (InterruptedIOException iioe) {
                    /* user canceled loading */
                    if (pm != null && pm.isCanceled()) {
                        pm.close();
                        Toolkit.getDefaultToolkit().beep();
                        System.err.println("Canceled by user.");
                    }
                } catch (OutOfMemoryError oome) {
                    System.err.println("ERROR Out of memory: "+oome);
                } finally {
                    if (br != null) {
                        br.close();
                    }
                }
            }//else: file unavailable
        }//readText()
---------- END SOURCE ----------
(Incident Review ID: 297578)
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