How to calculate OS memory size in java?

I want to calculate free memory size , when I tried by Runtime class
like this Runtime.getRuntime().freeMemory() it gives JVS free memory size
But I want OS free memory size
If anybody know then plz reply me ASAP

Since the question was asked the last time (yesterday afternoon), I don't think Java has changed much, so the answer is still: you can't do it with Java.

Similar Messages

How to read system memory size, processor speed of a system

Hi all,
How to read system memory size, processor speed of a system and how to read how much of it are in use in a running system. (using java)
any help would be great.
-thanks

How to read system memory size, processor speed of a
system and how to read how much of it are in use in a
running system. (using java)Using Java: not at all. You'll need JNI.

How to calculate 4 GB size,

Dear All,
How to calculate 4 GB size. i mean including (apex,system,sys,sysaux) or excluding (apex,system,sys,sysaux)
with thanks and regards
Sivakumar.G

Hi,
I did read your other posts so I assume you talking about Oracle XE storage limit ?
You calculate limit without system and sysaux tablespace
Here is similar post from XE forum
Limitation Detail of Oracle 10g XE Database
Br, Jari

How to extend RAM memory size in Mac Book pro.

Sir,
I have Mac Book Pro.This system have 4 GB RAM only.but I need 8 GB RAM for install Window OS purpose.So How to extend RAM memory size in Mac Book Pro.
Regards,
M.Muthukumar

http://support.apple.com/kb/HT1270

How can i increase a size of java plugin window in developer10g form?

Dear Friends,
I made a master detail form in developer10g form. In the form i m unable to see all the fields in java plugin window bcoz its small.
how can i increase the size of java plugin window?
Thanks in advance.
Regards,
Kamran

Hi Kamran
Just modify width and height values to 100% in the forms\server\formsweb.cfg file:
# Forms applet parameter
width=100%
# Forms applet parameter
height=100%
After this restart OC4J instance.
Hope this helps
Regards
Carlos

How to change heap memory size for general java applications (not applets)

Hi. I made a java class which manipulates images and I sometimes get an out of memory error when the files are large. In these cases I can run it successfully from the command line using:
java -Xms32m -Xmx128m myappbut as I run this class from a firefox extension, I can't use this technique.
Could some one tell me how to set this globally? I've found a lot of info on setting it for applets in the control panel but that's it. I also tried editing my deployment.properties file by adding:
deployment.javapi.jre.1.6.0_11-b03.args=-Xmx128mbut none of these options seem to work.
Thanks for any help.

Also you can use use [JAVA_TOOL_OPTIONS|http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#tooloptions], with more documentation here. JAVA_TOOLS_OPTIONS is available since 1.5. There is no direct documentation on [_JAVA_OPTIONS|http://java.sun.com/j2se/1.5.0/docs/guide/2d/flags.html] but was made available since at least 1.3.
The recent existing forum thread [Java Programming - How to change the default memory limits for java.|http://forums.sun.com/thread.jspa?threadID=5368323&messageID=10615245&start=36] has a long discussion on the issue.
You specified you are not using applets, but if you do, I would also suggest you use the next Generation Plug-in (since 1.6.0_10) that allows you specify the max memory in the applet without having to instruct the user how to make the change. See [JAVA_ARGUMENTS|https://jdk6.dev.java.net/plugin2/#JAVA_ARGUMENTS] for applets. Java Webstart uses resources.

How to find out memory of a java card

is there anyone could tell me that how can we check the size of the memory of a card? thank you in advance:D

If the card is a Java Card 2.2.1, create an applet that returns
JCSystem.getAvailableMemory(), install and queryit.
Some other ideas for getting the free memory on card were presented in the thread "Java Forums - Free memory on card"
http://forum.java.sun.com/thread.jspa?threadID=647894&tstart=30
Jan

How to get free memory size of a card with javax.smartcardio

Hi,
How can I find how much memory of a card is free with javax.smartcardio?
Please your advice.
Thank in advance.

gizmo wrote:
I wanted to read the free memory size with a card reader and javax.smartcardio.
Is it possible to send a APDU Command to select the root 3F00 and read the properties?There is no built-in smartcardio funationality to do this. What you can do is send an APDU and get the memory by calling the code mentioned already.

How to calculate the row size

Hi,
I am having a table of 4 column. First column is varchar2(10), Second column is Number(5), Third column is char(10) and Fourth column is Number(12,2).
Now how to calculate the size of each row. I want to know how much space it will take for each row.
Thanx & Regards,
Swarup

For a complete discussion of storage requirements for different datatypes see the Oracle 8i Concepts manual.
All Oracle documentation is available on-line via the 'Documentation' link on the OTN home page.
Your Col2 NUMBER(5) will take 4 bytes if it holds a 5 digit positive or negative number.
Your Col4 NUMBER(12,2) will take 7 bytes if it holds a number with 12 digits that is positive and will take 8 bytes if it holds a number with 12 digits that is negative.
The following is from the Concepts manual Chapter 12 (Copyright by Oracle)
Built-In Datatypes 12-9
Internal Numeric Format
Oracle stores numeric data in variable-length format. Each value is stored in
scientific notation, with one byte used to store the exponent and up to 20 bytes to
store the mantissa. The resulting value is limited to 38 digits of precision. Oracle
does not store leading and trailing zeros. For example, the number 412 is stored in a
format similar to 4.12 x 10 2 , with one byte used to store the exponent (2) and two
bytes used to store the three significant digits of the mantissa (4, 1, 2). Negative
numbers include the sign in their length.
Taking this into account, the column size in bytes for a particular numeric data
value NUMBER ( p), where p is the precision of a given value, can be calculated
using the following formula:
ROUND((length( p)+ s)/2))+1
where s equals zero if the number is positive and s equals 1 if the number is
negative.
Zero and positive and negative infinity (only generated on import from Version 5
Oracle databases) are stored using unique representations. Zero and negative
infinity each require one byte; positive infinity requires two bytes.
null

How to specify maximum memory usage for Java VM in Tomcat?

Does any one know how to setup memory usage for Java VM, such as "-Xmx256m" parameter, in Tomcat?
I'm using Tomcat 3.x in Apache web server on Sun Solaris platform. I already tried to add the following line into tomcat.properties, like:
wrapper.bin.parameters=-Xmx512m
However, it seems to me that this doesn't work. So, how about if my servlet will consume a large amount of memory that exceeds the default 64M memory boundary of Java VM?
Any idea will be appreciated.
Haohua

With some help we found the fix. You have to set the -Xms and -Xmx at installation time when you install Tomcat 4.x as a service. Services do not read system variables. Go to the command prompt in windows, and in the directory where tomcat.exe resides, type "tomcat.exe /?". You will see jvm_options as part of the installation. Put the -Xms and -Xmx variables in the proper place during the install and it will work.
If you can't uninstall and reinstall, you can apply this registry hack that dfortae sent to me on another thread.
=-=-=-=-=-=
You can change the parameters in the Windows registry. If your service name is "Apache Tomcat" The location is:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Apache Tomcat\Parameters
Change the JVM Option Count value to the new value with the number of parameters it will now have. In my case, I added two parameters -Xms100m and -Xmx256m and it was 3 before so I bumped it to 5.
Then I created two more String values. I called the first one I added 'JVM Option Number 4' and the second 'JVM Option Number 5'. Then I set the value inside each. The first one I set to '-Xms100m' and the second I set to '-Xmx256m'. Then I restarted Tomcat and observed when I did big processing the memory limit was now 256 MB, so it worked. Hope this helps!
=-=-=-=-=
I tried this and it worked. I did not want to have to go through the whole reinstallation process, so this was best for me.
Thanks to all who helped on this.

How solaris calculate virtual Memory ?

Hi,
I am using Solaris 10 on both sparc and x86 server.
I am still unable to comprehend how solaris calculate Total Virtual Memory.
We can check the Virtual Memory in system by SMC tool and by #swap -s command.
swap -s
total: 6071888k bytes allocated + 1010404k reserved = 7082292k used, 52134560k availableAbove output shows that total virtual memory is = 7082292k used, 52134560k available = 57829 MB
Sun documents says that solaris calculate Virutal Memory by combining the available RAM with total swap space
System swap is 32773 MB
And availabe RAM righ now is 22506
# vmstat 1 3
kthr memory page disk faults cpu
r b w swap free re mf pi po fr de sr s2 -- -- -- in sy cs us sy id
0 0 0 55999408 25906620 579 106 1410 2 2 0 0 69 0 0 0 3919 13684 6331 3 2 95
1 0 0 52134492 23046320 9 56 0 0 0 0 0 4 0 0 0 1391 4097 2257 0 1 99
0 0 0 52134372 23046196 0 6 0 0 0 0 0 5 0 0 0 1511 4367 2474 0 1 99So combining them becomes 55279 MB which is not the same as displaying by SMC and swap -s
Does any body know how solaris exactly calculate the virtual memory which it indicates in SMC and swap -s ?

If you look at the man page it shows for the -s flag:
available The total swap space in
bytes that is currently
available for future reser-
vation and allocation.
That means if swap has been allocated it wont be shown in this total, Solaris has a funny way of dealing with memory, it will only free physical memory when it needs to reuse it. If you want to tell if a system is paging the best way is to use sar with the -g flag e.g
sar -g 10 10
Or iostat etc

How to Increase the memory size of a File in the Application Server

Hello Abaper's
I have generated a XML file for the data of internal table (with 10 Records). When i download , i can see the XML file for the Entire 10 Records.
But , while transferring the XML file to Applicationserver , it's transferring only upto max 4 Records.I     assume that the memory is insufficient to allocate 10 Records. Can we Increase the Memory size of the File on Application server. OR, is there any error in My Source Code.
Code i used to Transfer the XML File to Application server.
OPEN DATASET FNAME FOR OUTPUT IN BINARY MODE.
IF sy-subrc EQ 0.
   LOOP AT it_xmltab INTO wa_xmltab.
       TRANSFER wa_xmltab TO FNAME.
   ENDLOOP.
ELSE.
MESSAGE e004(zmsg5) WITH 'File FNAME not opened'.
ENDIF.
CLOSE DATASET FNAME.
Regards
Jv

Hi,
DATA : filename TYPE rlgrap-filename.
DATA : doc_name TYPE char30.
DATA : bin_size TYPE i.
SELECT matnr matkl meins
       FROM mara INTO TABLE it_mara
       UP TO 10 ROWS.
CALL FUNCTION 'SAP_CONVERT_TO_XML_FORMAT'
EXPORTING
    i_filename           = filename
    i_xml_doc_name       = doc_name
IMPORTING
    pe_bin_filesize      = bin_size
TABLES
    i_tab_sap_data       = it_mara         " contains 10 Records
CHANGING
    i_tab_converted_data = it_xmltab.
placing XML File in Appl. Server
DATA : FNAME(60) VALUE 'xyz_File'.
DATA : num TYPE i.
DATA : xmldata(256) TYPE x.
For Writing The data in Application Server
OPEN DATASET FNAME FOR OUTPUT IN BINARY MODE. " ENCODING DEFAULT.
IF sy-subrc EQ 0.
LOOP AT it_xmltab INTO wa_xmltab.
    TRANSFER wa_xmltab TO FNAME.
ENDLOOP.
ELSE.
MESSAGE e004(zmsg5) WITH 'File FNAME not opened'.
ENDIF.
CLOSE DATASET FNAME.
For Reading The data in Application Server
OPEN DATASET FNAME FOR INPUT IN BINARY MODE. " ENCODING DEFAULT.
DO.
IF sy-subrc EQ 0.
    READ DATASET fname INTO xmldata.
    WRITE :/ xmldata.
    Clear xmldata.
ELSE.
    EXIT.
ENDIF.
ENDDO.
CLOSE DATASET FNAME.
at runtime i can see
it_mara --> contain 10 records
it_xmltab --> contain 7 lines (Each line size is 255 char). This table have XML format data, (unknow format , with all numeric
                    digits)
it_xmltab is trasferred to application server , but the xml format is generated upto 4 records, and for the remaining records
the XML format is not generated.
the XML data in application server file is
<?xml version="1.0"?><TY_MARA><TY_MARA><MATNR Datatype="C" Length="36">0-BUY1</MATNR><MATKL Datatype="C" Length="18">012</MATKL><MEINS Datatype="C" Length="6">PC
</MEINS>
</TY_MARA><TY_MARA><MATNR Datatype="C" Length="36">0-BUY2</MATNR><MATKL Datatype="C" Length="18">012</MATKL><MEINS Datatype="C" Length="6">
PC </MEINS>
</TY_MARA><TY_MARA><MATNR Datatype="C" Length="36">000000000000000001</MATNR><MEINS Datatype="C" Length="6">EA</MEINS>
</TY_MARA><TY_MARA><MATNR Datatype="C" Length="36">000000000000000002</MATNR
Regards
JV

How to determine the Memory size of my computer?

I need to find a way to determine how much computer RAM i have left. I was suggested to use System class methods like "Runtime.getRuntime().getFreeMemory()", and I need to determine how much Memory I need to use when I launch Java VM with Xmx option.
I wonder if there is more detail I need to know at this moment? If this question is more suitable in Java VM forum, please let me know.

This is a slightly messed version of the one in the J2D Demo, use JFrame.add(new MemoryMonitor());
I'm not entirely sure if it'll work straight off since I messed with it but it should, all the memory stuff is hidden away there somewhere even if it won't.
Shish
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.Date;
import javax.swing.*;
import javax.swing.border.EtchedBorder;
import javax.swing.border.TitledBorder;
public class MemoryMonitor extends JPanel {
    static JCheckBox dateStampCB = new JCheckBox("Output Date Stamp");
    public Surface surf;
    JPanel controls;
    boolean doControls;
    JTextField tf;
    public MemoryMonitor() {
     note=n;
        setLayout(new BorderLayout());
        setBorder(new TitledBorder(new EtchedBorder(), "Memory Monitor"));
        add(surf = new Surface());
        controls = new JPanel();
        controls.setPreferredSize(new Dimension(135,80));
        Font font = new Font("serif", Font.PLAIN, 10);
        JLabel label = new JLabel("Sample Rate");
        label.setFont(font);
        label.setForeground(Color.black);
        controls.add(label);
        tf = new JTextField("1000");
        tf.setPreferredSize(new Dimension(45,20));
        controls.add(tf);
        controls.add(label = new JLabel("ms"));
        label.setFont(font);
        label.setForeground(Color.black);
        controls.add(dateStampCB);
        dateStampCB.setFont(font);
        addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent e) {
               removeAll();
               if ((doControls = !doControls)) {
                   surf.stop();
                   add(controls);
               } else {
                   try {
                       surf.sleepAmount = Long.parseLong(tf.getText().trim());
                   } catch (Exception ex) {note.alert(ex);}
                   surf.start();
                   add(surf);
               validate();
               repaint();
    public void start() {
     surf.start();
    public class Surface extends JPanel implements Runnable {
        public Thread thread;
        public long sleepAmount = 1000;
        private int w, h;
        private BufferedImage bimg;
        private Graphics2D big;
        private Font font = new Font("Times New Roman", Font.PLAIN, 11);
        private Runtime r = Runtime.getRuntime();
        private int columnInc;
        private int pts[];
        private int ptNum;
        private int ascent, descent;
        private float freeMemory, totalMemory;
        private Rectangle graphOutlineRect = new Rectangle();
        private Rectangle2D mfRect = new Rectangle2D.Float();
        private Rectangle2D muRect = new Rectangle2D.Float();
        private Line2D graphLine = new Line2D.Float();
        private Color graphColor = new Color(46, 139, 87);
        private Color mfColor = new Color(0, 100, 0);
        private String usedStr;
        public Surface() {
            setBackground(Color.black);
            addMouseListener(new MouseAdapter() {
                public void mouseClicked(MouseEvent e) {
                    if (thread == null) start(); else stop();
        public Dimension getMinimumSize() {
            return getPreferredSize();
        public Dimension getMaximumSize() {
            return getPreferredSize();
        public Dimension getPreferredSize() {
            return new Dimension(135,80);
        public void paint(Graphics g) {
            if (big == null) {
                return;
            big.setBackground(getBackground());
            big.clearRect(0,0,w,h);
            float freeMemory = (float) r.freeMemory();
            float totalMemory = (float) r.totalMemory();
            // .. Draw allocated and used strings ..
            big.setColor(Color.green);
            big.drawString(String.valueOf((int) totalMemory/1024) + "K allocated", 4.0f, (float) ascent+0.5f);
            usedStr = String.valueOf(((int) (totalMemory - freeMemory))/1024)
                + "K used";
            big.drawString(usedStr, 4, h-descent);
            // Calculate remaining size
            float ssH = ascent + descent;
            float remainingHeight = (float) (h - (ssH*2) - 0.5f);
            float blockHeight = remainingHeight/10;
            float blockWidth = 20.0f;
            float remainingWidth = (float) (w - blockWidth - 10);
            // .. Memory Free ..
            big.setColor(mfColor);
            int MemUsage = (int) ((freeMemory / totalMemory) * 10);
            int i = 0;
            for ( ; i < MemUsage ; i++) {
                mfRect.setRect(5,(float) ssH+i*blockHeight,
                                blockWidth,(float) blockHeight-1);
                big.fill(mfRect);
            // .. Memory Used ..
            big.setColor(Color.green);
            for ( ; i < 10; i++) {
                muRect.setRect(5,(float) ssH+i*blockHeight,
                                blockWidth,(float) blockHeight-1);
                big.fill(muRect);
            // .. Draw History Graph ..
            big.setColor(graphColor);
            int graphX = 30;
            int graphY = (int) ssH;
            int graphW = w - graphX - 5;
            int graphH = (int) remainingHeight;
            graphOutlineRect.setRect(graphX, graphY, graphW, graphH);
            big.draw(graphOutlineRect);
            int graphRow = graphH/10;
            // .. Draw row ..
            for (int j = graphY; j <= graphH+graphY; j += graphRow) {
                graphLine.setLine(graphX,j,graphX+graphW,j);
                big.draw(graphLine);
            // .. Draw animated column movement ..
            int graphColumn = graphW/15;
            if (columnInc == 0) {
                columnInc = graphColumn;
            for (int j = graphX+columnInc; j < graphW+graphX; j+=graphColumn) {
                graphLine.setLine(j,graphY,j,graphY+graphH);
                big.draw(graphLine);
            --columnInc;
            if (pts == null) {
                pts = new int[graphW];
                ptNum = 0;
            } else if (pts.length != graphW) {
                int tmp[] = null;
                if (ptNum < graphW) {
                    tmp = new int[ptNum];
                    System.arraycopy(pts, 0, tmp, 0, tmp.length);
                } else {
                    tmp = new int[graphW];
                    System.arraycopy(pts, pts.length-tmp.length, tmp, 0, tmp.length);
                    ptNum = tmp.length - 2;
                pts = new int[graphW];
                System.arraycopy(tmp, 0, pts, 0, tmp.length);
            } else {
                big.setColor(Color.yellow);
                pts[ptNum] = (int)(graphY+graphH*(freeMemory/totalMemory));
                for (int j=graphX+graphW-ptNum, k=0;k < ptNum; k++, j++) {
                    if (k != 0) {
                        if (pts[k] != pts[k-1]) {
                            big.drawLine(j-1, pts[k-1], j, pts[k]);
                        } else {
                            big.fillRect(j, pts[k], 1, 1);
                if (ptNum+2 == pts.length) {
                    // throw out oldest point
                    for (int j = 1;j < ptNum; j++) {
                        pts[j-1] = pts[j];
                    --ptNum;
                } else {
                    ptNum++;
            g.drawImage(bimg, 0, 0, this);
        public void start() {
            thread = new Thread(this);
            thread.setPriority(Thread.MIN_PRIORITY);
            thread.setName("MemoryMonitor");
            thread.start();
        public synchronized void stop() {
            thread = null;
            notify();
        public void run() {
            Thread me = Thread.currentThread();
            while (thread == me && !isShowing() || getSize().width == 0) {
                try {
                    thread.sleep(500);
                } catch (InterruptedException e) { return; }
            while (thread == me && isShowing()) {
                Dimension d = getSize();
                if (d.width != w || d.height != h) {
                    w = d.width;
                    h = d.height;
                    bimg = (BufferedImage) createImage(w, h);
                    big = bimg.createGraphics();
                    big.setFont(font);
                    FontMetrics fm = big.getFontMetrics(font);
                    ascent = (int) fm.getAscent();
                    descent = (int) fm.getDescent();
                repaint();
                try {
                    thread.sleep(sleepAmount);
                } catch (InterruptedException e) { break; }
                if (MemoryMonitor.dateStampCB.isSelected()) {
                     System.out.println(new Date().toString() + " " + usedStr);
            thread = null;
public static void main(String s[]) {
        final MemoryMonitor demo = new MemoryMonitor();
        WindowListener l = new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
            public void windowDeiconified(WindowEvent e) { demo.surf.start(); }
            public void windowIconified(WindowEvent e) { demo.surf.stop(); }
        JFrame f = new JFrame("Java2D Demo - MemoryMonitor");
        f.addWindowListener(l);
        f.getContentPane().add("Center", demo);
        f.pack();
        f.setSize(new Dimension(200,200));
        f.setVisible(true);
        demo.surf.start();

How to set the Heap size for JAVA

I am facing the memory out of space problem:
Exception in thread "AWT-EventQueue-0" java.lang.OutOfMemoryError: Java heap space
Could anyone suggest me a solution to solve the problem ?
increase the heap size ?
anyway to increase the heap size in the program by default without additional setup?
Thank you.

How to determine the program must handled with increase heap size ?
could I know any method to know whether the program is memory leaking or need large memory heap size?

How to root out memory leak with Java JNI & Native BDB 11g ?

We are testing a web application using the 32-bit compiled native 11g version of BDB (with replication) under 32-bit IBM 1.5 JVM via JNI under 64-bit RedHat Linux. We are experiencing what appears to be a memory leak without a commensurate increase in Java heap size. Basically the process size continues to grow until the max 32-process size is reached (4Gb) and eventually stops running (no core). Java heap is set to 2Gb min/max. GCs are nominal, so the leak appears to be native and outside Java bytecode.
We need to determine whether there is a memory leak in BDB, or the IBM JVM or simply a mis-use of BDB in the Java code. What tools/instrumentation/db statistic should be used to help get to root cause? Do you recommend using System Tap (with some particular text command script)? What DB stats should we capture to get to the bottom of this memory leak? What troubleshooting steps can you recommend?
Thanks ahead of time.
JE.
Edited by: 787930 on Aug 12, 2010 5:42 PM

That's troublesome... DB itself doesn't have stats that track VM in any useful way. I am not familiar with SystemTap but a quick look at it seems to imply that it's better for kernel monitoring than user space. It's pretty hard to get DB to leak significant amounts of memory. The reason is that it mostly uses shared memory carved from the environment. Also if you are neglecting to close or delete some object DB generally complains about it somewhere.
I don't see how pmap would help if it's a heap leak but maybe I'm missing something.
One way to rule DB out is to replace its internal memory allocation functions with your own that are instrumented to track how much VM has been allocated (and freed). This is very easy to do using the interfaces:
db_env_set_func_malloc()
db_env_set_func_free()
These are global to your process and your functions will be used where DB would otherwise call malloc() and free(). How you get usage information out of the system is an exercise left to the reader :-) If it turns out DB is the culprit then there is more thinking to do to isolate the problem.
Other ideas that can provide information if not actual smoking guns:
-- accelerate reproduction of the problem by allocating nearly all of the VM to the JVM and the DB cache (or otherwise limit the allowable VM in your process)
-- change the VM allocated to the JVM in various ways
Regards,
George

How to calculate OS memory size in java?

Similar Messages

Maybe you are looking for