Problem with HSSF POI

Hi ,
Following is the normal code that i am using to read excel file:
HSSFSheet sheet = workbook.getSheetAt(0);
     for (Iterator rit = sheet.rowIterator(); rit.hasNext(); ) {
          HSSFRow row = (HSSFRow)rit.next();
int rowIndex= row.getRowNum();
          for (Iterator cit = row.cellIterator(); cit.hasNext(); ) {
               HSSFCell cell = (HSSFCell)cit.next();
               short cellIndex= cell.getCellNum();
For the very first row it correctly gives me rowIndex=0 , but when inside 0th row it should give me cellIndex=0 for the first time , but its giving mr cellIndex=1.
That way it is skipping 0th column. Its not picking 0th column in 0th row...its directly picking 1st column in 0th row.
Can anybody please tell me why this is happening???
thanx in advance

It appears the cell order you see in the excel document is not the order the POI reads them.
Here is a link I found describing it and the work around:
http://forum.java.sun.com/thread.jspa?threadID=656009&messageID=4405384
For your own future reference: I found this link by searching google for unique words 'HSSFSheet' and 'celliterator'

Similar Messages

Format float value with HSSF POI

I have a class that generates an excell workbook using the library HSSF POI from apache. I write some float values into some page cells but I want to show only two digits after the decimal point. How can I do that?
Thanks in advance
Rosa

Or create an HSSFCellStyle object with the format you want and apply that to the cell. Choose your format from the static members of HSSFDataFormat.

Struts \ POI \ Javascript Problem with IE 7

Alright folks, I'm having a problem migrating my application from IE 6 to IE 7. We have search functionality in the app that triggers off of javascript calls when a button is pressed in the search. Once the data is retrieved, an export button becomes enabled that allows the user to export those results to Excel using POI. On the back end, we're using struts running in WAS 6. When the results are exported, the action class manually writes the excel workbook to the output stream as below:
     protected void print(HSSFWorkbook a_wb, HttpServletResponse a_response)
          throws IOException, ServletException {
          // generate output
          a_response.setContentType("application/vnd.ms-excel");
          ServletOutputStream out = a_response.getOutputStream();
          a_wb.write(out);
Then the action returns null to signify to struts that the response has already been handled manually.
Everything works perfectly in IE 6. In IE 7, however, everything is not so great. The search works to retrieve the results and I can export them to Excel. The problem is that after I export them to Excel, all the Javascript on my page ceases to work. Basically, what I've been able to determine is that upon receiving the Excel document response something is causing the document Javascript variable to become undefined. This causes all my javascript -- things like:
document.getElementById('actionIndicator').value ="Clear";
to completely fail because document is undefined. Mind you, the page is still sitting there rendered in IE, and I can do things like window.frames and programmatically see a list of the frames defined on the page -- but the document variable is completely gone.
At this point I'm kind of at a loss as to what to check or test next, so I'm open to any suggestions. Thanks!

Hey Gina
we have not seen broken images like you did, but have seen dramatic reduction in respose time with IE 7 (~20 times slower than normal). A bunch of IT folks tried various settings and configurations, with no success. Finally, we figured that different versions of IE 7 acd differently. Version 5700 was running fine. Version 5713 (or something like that, the latest one) was slooooow.
Our Office of Information Resources does not "support" any other browser than IE. So, in addition to problems with Office 2007 I described previously, we may get a double whammy from Microsoft. Don't get me started.
Vojin

Generating execl dynamically using HSSF POI API

I am dynamically generating an excel report from a java servlet using the hssf poi api. However, unless I manually close a previoulsy generated excel window, the excel report content is not updated with new data when a new report is run. The previously generated data remains in the excel window. Does any one know how I can either shut down the open excel application window programmatically or ensure that the data is updated with each report run. Thanks.

That's native OS problem. Once excel opened a file(even for reading) you can't write to it using other program like your servlet. So close the file before writing, or simply write to different file name.

Java and Excel sheet (hssf poi) creating back up please help!!

Dear friends , i have a problem i saved some data into some excel file using HSSF POI . after raeching some lines say a maximum of 1000 lines ) i have to save the EXCEL sheet as backupfile with the extention .bak and then delete the original Excel file . did any body have some idea about this . i know you guyz are gurus so please give some advise
thanks in advance
cheers
harsha

you would actually have a counter to count the number of rows you inserted into the spreadsheet..once counter hits 1000, just save it as .bak extension?

Some problems with 3 counters on PCI 6601

Good afternoon,
after a lot of time i'm here yet.
The problem with the PCI 6601 aren't finished in sense that i have tried a lot of solution but my sistem crashed after some acquisition.
The code that had write on Visual Basic 6 are :
'Inizializzo la scheda PCI-6601
Public Sub init_6601(NumSens As Integer)
Dim edge As DAQmxEdge1
On Error GoTo ErrorHandler
    MyChannel(NumSens) = "My Channel" & NumSens            'Definisce il nome per il canale (optional)
    'Creo i tre task che servono per il funzionamento del programma
    DAQmxErrChk DAQmxCreateTask("", taskHandle(NumSens))
    'Questa funzione serve a creare il canale dalla quale poi viene effettuata la misura
    If (NumSens = 0) Then
        DAQmxErrChk DAQmxCreateCIPulseWidthChan(taskHandle(NumSens), "Dev1/ctr1", MyChannel(NumSens), 0.00001, _
        0.0009, DAQmx_Val_TimeUnits3_Seconds, DAQmx_Val_Edge1_Rising, "") ' DAQmx_Val_TimeUnits3_Ticks, DAQmx_Val_Edge1_Rising, "")
    ElseIf (NumSens = 1) Then
        DAQmxErrChk DAQmxCreateCIPulseWidthChan(taskHandle(NumSens), "Dev1/ctr2", MyChannel(NumSens), 0.00001, _
        0.0009, DAQmx_Val_TimeUnits3_Ticks, DAQmx_Val_Edge1_Rising, "") 'DAQmx_Val_TimeUnits3_Seconds, DAQmx_Val_Edge1_Rising, "")
    Else
        DAQmxErrChk DAQmxCreateCIPulseWidthChan(taskHandle(NumSens), "Dev1/ctr3", MyChannel(NumSens), 0.00001, _
        0.0009, DAQmx_Val_TimeUnits3_Seconds, DAQmx_Val_Edge1_Rising, "")
    End If
    DAQmxErrChk DAQmxSetReadReadAllAvailSamp(taskHandle(NumSens), False)
    'Con questa funzione si sincronizza il timebase della scheda con il segnale da leggere
    DAQmxErrChk DAQmxSetCIPulseWidthDigSyncEnable(taskHandle(NumSens), MyChannel(NumSens), True)
    'DAQmxErrChk DAQmxSetReadOverWrite(taskHandle(NumSens), DAQmx_Val_OverwriteMode1_OverwriteUnreadSamps)
    'DAQmxErrChk DAQmxCfgSampClkTiming(taskHandle(NumSens), "", 100000, DAQmx_Val_Rising, DAQmx_Val_AcquisitionType_ContSamps, 10000)
    'provare queste due funzioni per aspettare che il campione sia realmente disponibile.
    'La seconda èdovrebbe essere quella che da il migliore compromesso tra uso CPU e velocità.
    'DAQmxErrChk DAQmxSetReadWaitMode(taskHandle(NumSens), DAQmx_Val_WaitMode_WaitForInterrupt)
    'DAQmxErrChk DAQmxSetReadWaitMode(taskHandle(NumSens), DAQmx_Val_WaitMode_Yield)
    'Setta il numero di campioni da acquisire ogni volta che va in lettura e
    'il modo di lettura. Si è impostato "contsamps" per avere la lettura continua
    'La dimensione del buffer è determinata da quel 10000 che va messo così secondo le specifiche del daqmx
    DAQmxErrChk DAQmxCfgImplicitTiming(taskHandle(NumSens), DAQmx_Val_AcquisitionType_ContSamps, 10000) 'DAQmx_Val_AcquisitionType_ContSamps
    'La scheda NI PCI 6601 ha soltanto un canale per il DMA (Direct Memory Access) quindi non riesco a leggere
    'contemporaneamente tre task per volta. Quindi devo attivare un meccanismo diverso per la lettura
    'basato sugli interrupt, ogni volta che ho una lettura automaticamente leggo il dato
    DAQmxErrChk DAQmxSetCIDataXferMech(taskHandle(NumSens), MyChannel(NumSens), DAQmx_Val_DataTransferMechanism_Interrupts)
    'La funzione di seguito serve semplicemente per leggere il campione più recente generato
    DAQmxErrChk DAQmxSetReadRelativeTo(taskHandle(NumSens), DAQmx_Val_ReadRelativeTo_MostRecentSamp)
    'La seguente funzione è complementare ad una utilizzata nell'inizializzazione e serve per impostare la lettura
    'sull'ultimo campione generato
    DAQmxErrChk DAQmxSetReadOffset(taskHandle(NumSens), -1)
    DAQmxStartTask taskHandle(NumSens)
    taskIsRunning(NumSens) = True
Exit Sub
ErrorHandler:
    For i = 0 To 2
        If taskIsRunning(i) = True Then
            DAQmxStopTask taskHandle(i)
            DAQmxClearTask taskHandle(i)
            taskIsRunning(i) = False
        End If
    Next i
    MsgBox "Error: " & Err.number & " " & Err.Description, , "Error"
End Sub
For the reading i use :
        DAQmxErrChk DAQmxReadCounterF64(taskHandle(NumSens), -1, 0.5, temp(NumSens, 0), 10000, ReadSamp(NumSens), ByVal &O0)
Well, my problem are very simple, I want an continuos acquisition on three channel and the input signal's frequency that i have to measure is 1 kHz .
when i try to keep 2 channel after some cycles appears the error -200141 (buffer overwriting). Why?
The read function is called some times every ms and evry time keep out an different value, even if that are impossible because the input signal is at 1 kHz, and why the buffer fill up? What is wrong in my code?
Thanks in advance for your help
Have a nice day!!
Igor Piero Prato

HI Igor84,
Error 200141 occurs when the data acquisition device acquires data faster than the computer can read it from the FIFO (first-in-first-out) input buffer.
You can see this document:
Error 200141 Occurs When Doing Buffered Event Counting
http://digital.ni.com/public.nsf/allkb/83656593DCF1FB0F862570B6004D7222?OpenDocument
and this forum :
Buffer Overflow -200141
http://forums.ni.com/t5/Measurement-Studio-for-VC/Buffer-Overflow-200141/m-p/607234
I hope that these links can help you.
Regards

Problem with decode!!!

Hi guys,
I have a problem with "decode"!
How can I tell the decode expression
that if a rowset don't exists --> then doing something.
I've tried that with "NULL" but that don't works.
here my code:
I wanted that if tx.text doesn't exists then
it returns fs.anlageschwerpunkt_lang, and otherwise
it returns tx.Text.
select
decode(tx.Text,NULL,fs.anlageschwerpunkt_lang,tx.Text) Anlageschwerpunkt_1 from
POI.Fondsstamm fs,
Texte tx,
Texttypstamm txy
where
tx.match='amfcomm'
and tx.match=rtrim(fs.match)
and tx.TEXTTYPID=txy.TEXTTYPID
and txy.BEREICHSID=14
and txy.texttyp='Marketingstrategie'
I hope somebody of you can help me
thanxx
Schoeib

I read Schoeibs question differently; no ROWS are being returned. In that case you cannot expect DECODE or any other function to do anything. Assuming that rows always exist in fs and txy and are only missing in tx, then you need an outer join. Note that the join of tx.match = rtrim(fs.match) has been altered to avoid outer joining to more than one table. As mentioned before, although the decode is OK, NVL could be used instead.
select
decode(tx.Text,NULL,fs.anlageschwerpunkt_lang,tx.Text) Anlageschwerpunkt_1 from
POI.Fondsstamm fs,
Texte tx,
Texttypstamm txy
where
tx.match(+)='amfcomm'
and rtrim(fs.match) = 'amfcomm'
and tx.TEXTTYPID(+)=txy.TEXTTYPID
and txy.BEREICHSID=14
and txy.texttyp='Marketingstrategie'

Number Formatting in Excel using HSSF POI

Hi,
I am downloading some data into the Excel file using hssf poi and I do my number formatting(either rounded,unrounded or general etc.) in java. The problem is that after the Excel file is created, the values in it behave like text though it shows the format as number. I am not able to plot any graphs or do any mathematical calculations using it. I need to convert it using "=VALUE(data)" before I do so.Is there anyway I can rectify this in the API itself?
Your suggestions will be very helpful.
Thanks.

http://jakarta.apache.org/poi/hssf/quick-guide.html#CellTypes ?
Otherwise, Apache POI has a mailing list...

A problem with threads

I am trying to implement some kind of a server listening for requests. The listener part of the app, is a daemon thread that listens for connections and instantiates a handling daemon thread once it gets some. However, my problem is that i must be able to kill the listening thread at the user's will (say via a sto button). I have done this via the Sun's proposed way, by testing a boolean flag in the loop, which is set to false when i wish to kill the thread. The problem with this thing is the following...
Once the thread starts excecuting, it will test the flag, find it true and enter the loop. At some point it will LOCK on the server socket waiting for connection. Unless some client actually connects, it will keep on listening indefinatelly whithought ever bothering to check for the flag again (no matter how many times you set the damn thing to false).
My question is this: Is there any real, non-theoretical, applied way to stop thread in java safely?
Thank you in advance,
Lefty

This was one solution from the socket programming forum, have you tried this??
public Thread MyThread extends Thread{
     boolean active = true;
     public void run(){
          ss.setSoTimeout(90);
          while (active){
               try{
                    serverSocket = ss.accept();
               catch (SocketTimeoutException ste){
               // do nothing
     // interrupt thread
     public void deactivate(){
          active = false;
          // you gotta sleep for a time longer than the
          // accept() timeout to make sure that timeout is finished.
          try{
               sleep(91);
          }catch (InterruptedException ie){
          interrupt();
}

Problem with Threads and a static variable

I have a problem with the code below. I am yet to make sure that I understand the problem. Correct me if I am wrong please.
Code functionality:
A timer calls SetState every second. It sets the state and sets boolean variable "changed" to true. Then notifies a main process thread to check if the state changed to send a message.
The problem as far I understand is:
Assume the timer Thread calls SetState twice before the main process Thread runs. As a result, "changed" is set to true twice. However, since the main process is blocked twice during the two calls to SetState, when it runs it would have the two SetState timer threads blocked on its synchronized body. It will pass the first one, send the message and set "changed" to false since it was true. Now, it will pass the second thread, but here is the problem, "changed" is already set to false. As a result, it won't send the message even though it is supposed to.
Would you please let me know if my understanding is correct? If so, what would you propose to resolve the problem? Should I call wait some other or should I notify in a different way?
Thanks,
B.D.
Code:
private static volatile boolean bChanged = false;
private static Thread objMainProcess;
   protected static void Init(){
        objMainProcess = new Thread() {
            public void run() {
                while( objMainProcess == Thread.currentThread() ) {
                   GetState();
        objMainProcess.setDaemon( true );
        objMainProcess.start();
    public static void initStatusTimer(){
        if(objTimer == null)
             objTimer = new javax.swing.Timer( 1000, new java.awt.event.ActionListener(){
                public void actionPerformed( java.awt.event.ActionEvent evt){
                          SetState();
    private static void SetState(){
        if( objMainProcess == null ) return;
        synchronized( objMainProcess ) {
            bChanged = true;
            try{
                objMainProcess.notify();
            }catch( IllegalMonitorStateException e ) {}
    private static boolean GetState() {
        if( objMainProcess == null ) return false;
        synchronized( objMainProcess ) {
            if( bChanged) {
                SendMessage();
                bChanged = false;
                return true;
            try {
                objMainProcess.wait();
            }catch( InterruptedException e ) {}
            return false;
    }

Thanks DrClap for your reply. Everything you said is right. It is not easy to make them alternate since SetState() could be called from different places where the state could be anything else but a status message. Like a GREETING message for example. It is a handshaking message but not a status message.
Again as you said, There is a reason I can't call sendMessage() inside setState().
The only way I was able to do it is by having a counter of the number of notifies that have been called. Every time notify() is called a counter is incremented. Now instead of just checking if "changed" flag is true, I also check if notify counter is greater than zero. If both true, I send the message. If "changed" flag is false, I check again if the notify counter is greater than zero, I send the message. This way it works, but it is kind of a patch than a good design fix. I am yet to find a good solution.
Thanks,
B.D.

Problem with threads running javaw

Hi,
Having a problem with multi thread programming using client server sockets. The program works find when starting the the application in a console using java muti.java , but when using javaw multi.java the program doesnt die and have to kill it in the task manager. The program doesnt display any of my gui error messages either when the server disconnect the client. all works find in a console. any advice on this as I havent been able to understand why this is happening? any comment would be appreciated.
troy.

troy,
Try and post a minimum code sample of your app which
does not work.
When using javaw, make sure you redirect the standard
error and standard output streams to file.
Graeme.Hi Graeme,
I dont understand what you mean by redirection to file? some of my code below.
The code works fine under a console, code is supposed to exit when the client (the other server )disconnects. the problem is that but the clientworker side of the code still works. which under console it doesnt.
public class Server{
ServerSocket aServerSocket;
Socket dianosticsSocket;
Socket nPortExpress;
ClientListener aClientListener;
LinkedList queue = new LinkedList();
int port = 0;
int clientPort = 0;
String clientName = null;
boolean serverAlive = true;
* Server constructor generates a server
* Socket and then starts a client threads.
* @param aPort      socket port of local machine.
public Server(int aPort, String aClientName, int aClientPort){
port = aPort;
clientName = aClientName;
clientPort = aClientPort;
try{
// create a new thread
aServerSocket = new ServerSocket(port) ;
// connect to the nPortExpress
aClientListener = new ClientListener(InetAddress.getByName(clientName), clientPort, queue,this);
// aClientListener.setDaemon(true);
aClientListener.start();
// start a dianostic port
DiagnosticsServer aDiagnosticsServer = new DiagnosticsServer(port,queue,aClientListener);
// System.out.println("Server is running on port " + port + "...");
// System.out.println("Connect to nPort");
catch(Exception e)
// System.out.println("ERROR: Server port " + port + " not available");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Server port " + port + " not available", JOptionPane.ERROR_MESSAGE);
serverAlive = false;
System.exit(1);
while(serverAlive&&aClientListener.hostSocket.isConnected()){
try{
// connect the client
Socket aClient = aServerSocket.accept();
//System.out.println("open client connection");
//System.out.println("client local: "+ aClient.getLocalAddress().toString());
// System.out.println("client localport: "+ aClient.getLocalPort());
// System.out.println("client : "+ aClient.getInetAddress().toString());
// System.out.println("client port: "+ aClient.getLocalPort());
// make a new client thread
ClientWorker clientThread = new ClientWorker(aClient, queue, aClientListener, false);
// start thread
clientThread.start();
catch(Exception e)
//System.out.println("ERROR: Client connection failure");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Client connection failure", JOptionPane.ERROR_MESSAGE);
}// end while
} // end constructor Server
void serverExit(){
     JOptionPane.showMessageDialog(null, "Server ","ERROR: nPort Failure", JOptionPane.ERROR_MESSAGE);
     System.exit(1);
}// end class Server
*** connect to another server
public class ClientListener extends Thread{
InetAddress hostName;
int hostPort;
Socket hostSocket;
BufferedReader in;
PrintWriter out;
boolean loggedIn;
LinkedList queue;      // reference to Server queue
Server serverRef; // reference to main server
* ClientListener connects to the host server.
* @param aHostName is the name of the host eg server name or IP address.
* @param aHostPort is a port number of the host.
* @param aLoginName is the users login name.
public ClientListener(InetAddress aHostName, int aHostPort,LinkedList aQueue,Server aServer)      // reference to Server queue)
hostName = aHostName;
hostPort = aHostPort;
queue = aQueue;
serverRef = aServer;
// connect to the server
try{
hostSocket = new Socket(hostName, hostPort);
catch(IOException e){
//System.out.println("ERROR: Connection Host Failed");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Connection to nPort Failed", JOptionPane.ERROR_MESSAGE);
System.exit(0);
} // end constructor ClientListener
** multi client connection server
ClientWorker(Socket aSocket,LinkedList aQueue, ClientListener aClientListener, boolean diagnostics){
queue = aQueue;
addToQueue(this);
client = aSocket;
clientRef = aClientListener;
aDiagnostic = diagnostics;
} // end constructor ClientWorker
* run method is the main loop of the server program
* in change of handle new client connection as well
* as handle all messages and errors.
public void run(){
boolean alive = true;
String aSubString = "";
in = null;
out = null;
loginName = "";
loggedIn = false;
while (alive && client.isConnected()&& clientRef.hostSocket.isConnected()){
try{
in = new BufferedReader(new InputStreamReader(client.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(client.getOutputStream()));
if(aDiagnostic){
out.println("WELCOME to diagnostics");
broadCastDia("Connect : diagnostics "+client.getInetAddress().toString());
out.flush();
else {
out.println("WELCOME to Troy's Server");
broadCastDia("Connect : client "+client.getInetAddress().toString());
     out.flush();
String line;
while(((line = in.readLine())!= null)){
StringTokenizer aStringToken = new StringTokenizer(line, " ");
if(!aDiagnostic){
broadCastDia(line);
clientRef.sendMessage(line); // send mesage out to netExpress
out.println(line);
out.flush();
else{
if(line.equals("GETIPS"))
getIPs();
else{
clientRef.sendMessage(line); // send mesage out to netExpress
out.println(line);
out.flush();
} // end while
catch(Exception e){
// System.out.println("ERROR:Client Connection reset");
                         JOptionPane.showMessageDialog(null, (e.toString()),"ERROR:Client Connection reset", JOptionPane.ERROR_MESSAGE);
try{
if(aDiagnostic){
broadCastDia("Disconnect : diagnostics "+client.getInetAddress().toString());
out.flush();
else {
broadCastDia("Disconnect : client "+client.getInetAddress().toString());
     out.flush();
// close the buffers and connection;
in.close();
out.close();
client.close();
// System.out.println("out");
// remove from list
removeThreadQueue(this);
alive = false;
catch(Exception e){
// System.out.println("ERROR: Client Connection reset failure");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Client Connection reset failure", JOptionPane.ERROR_MESSAGE);
}// end while
} // end method run
* method run - Generates io stream for communicating with the server and
* starts the client gui. Run also parses the input commands from the server.
public void run(){
boolean alive = true;
try{
// begin to life the gui
// aGuiClient = new ClientGui(hostName.getHostName(), hostPort, loginName, this);
// aGuiClient.show();
in = new BufferedReader(new InputStreamReader(hostSocket.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(hostSocket.getOutputStream()));
while (alive && hostSocket.isConnected()){
String line;
while(((line = in.readLine())!= null)){
System.out.println(line);
broadCast(line);
} // end while
} // end while
catch(Exception e){
//     System.out.println("ERRORa Connection to host reset");
JOptionPane.showMessageDialog(null, (e.toString()),"ERROR: Connection to nPort reset", JOptionPane.ERROR_MESSAGE);
try{
hostSocket.close();
     }catch(Exception a){
     JOptionPane.showMessageDialog(null, (a.toString()),"ERROR: Exception", JOptionPane.ERROR_MESSAGE);
alive = false;
System.exit(1);
} // end method run

Problem with threads and camera.

Hi everybody!
I've a problem with taking snapshot.
I would like to display a loading screen after it take snapshot ( sometimes i
have to wait few seconds after i took snapshot. Propably photo is being taken in time where i have to wait).
I was trying to use threads but i didn't succeed.
I made this code:
display.setCurrent(perform);
        new Thread(new Runnable(){
            public void run() {
                while((!performing.isShown()) && (backgroundCamera.isShown())){
                    Thread.yield();
                notifyAll();
        }).start();
        new Thread(new Runnable(){
            public void run() {
                try {
                    this.wait();
                } catch(Exception e) {
                    exceptionHandler(e);
                photo = camera.snapshot();
                display.setCurrent(displayPhoto);
        }).start();This code is sometimes showing performing screen but sometimes no.
I don't know why. In my opinion performing.isShown() method isn't working correctly.
Does anyone have some idea how to use threads here?

Hi,
I've finally managed to work this fine.
The code:
       Object o = new Object();
       display.setCurrent(perform);
        new Thread(new Runnable(){
            public void run() {
                while(!performing.isShown()){
                    Thread.yield();
               synchronized(o) {
                  o.notify();
        }).start();
        new Thread(new Runnable(){
            public void run() {
                try {
                    synchronized(o) {
                       o.wait(1);
                } catch(Exception e) {
                    exceptionHandler(e);
                photo = camera.snapshot();
                display.setCurrent(displayPhoto);
        }).start();

Problem with threads hanging

We have a problem where our application stops responding after a few days of usage. Things will for fine for a day or two, and then pretty quickly threads will start getting hung up, usually in places where they are allocating memory
We are running WebLogic 8.1 SP2 on Sun JDK 1.4.2_04 on Solaris 8 using the alternate threading model and the -server hotspot vm. We are running pretty much the same code that we had no problems with under WebLogic 6.1 SP4 and Sun JDK 1.3.1.
A thread dump usually shows that some or all of our execute threads are in the state "waiting for monitor entry" even though they are not currently waiting on any java locks. Here is a sample thread from the thread dump (we have ~120 threads so I don't want to post the full dump).
=============================================================================================
"ExecuteThread: '8' for queue: 'itgCrmWarExecutionQueue'" daemon prio=5 tid=0x005941d0 nid=0x2c waiting for monitor entry [c807f000..c807fc28]
at java.lang.String.substring(String.java:1446)
at java.lang.String.substring(String.java:1411)
at weblogic.servlet.internal.ServletRequestImpl.getRelativeUri(ServletRequestImpl.java:1872)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:3492)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2585)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:197)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:170)
=============================================================================================
String.java line 1446 for this jdk allocates a new String object, and all the other threads in this state also are creating new objects or arrays, etc.
We've done a pstack on this process when it's in this state, and the threads that are in the "waiting for monitor entry" that look like they're allocating memory are all waiting on the same lwp_mutex_lock with some allocation method that's calling into the native TwoGenerationCollectorPolicy.mem_allocate_work (see pstack output below for the same thread as in the thread dump above)
=============================================================================================
----------------- lwp# 44 / thread# 44 --------------------
ff31f364 lwp_mutex_lock (e3d70)
fee92384 __1cNObjectMonitorGenter26MpnGThread__v_ (5000, 525c, 5000, 50dc, 4800, 4af0) + 2d8
fee324d4 __1cSObjectSynchronizerKfast_enter6FnGHandle_pnJBasicLock_pnGThread__v_ (c807f65c, c807f7d4, 5941d0, 0, 35d654, fee328ec) + 68
fee32954 __1cQinstanceRefKlassZacquire_pending_list_lock6FpnJBasicLock__v_ (c807f7d4, ff170000, d4680000, 4491d4, fee1bc2c,
0) + 78
fee3167c __1cPVM_GC_OperationNdoit_prologue6M_i_ (c807f7bc, 4400, ff170000, 2d2b8, 4a6268, c807fa18) + 38
fee2e0b0 __1cIVMThreadHexecute6FpnMVM_Operation__v_ (c807f7bc, 963a8, 0, 0, 1, 0) + 90
fed2c2a4 __1cbCTwoGenerationCollectorPolicyRmem_allocate_work6MIii_pnIHeapWord__ (962c0, ff1c29ec, ff1c297c, ff131a26, 4800, 4998) + 160
fed22940 __1cNinstanceKlassRallocate_instance6MpnGThread__pnPinstanceOopDesc__ (ee009020, 5941d0, 15ca581, 3647f0, 4a6268, c807f8c8) + 180
fed34928 __1cLOptoRuntimeFnew_C6FpnMklassOopDesc_pnKJavaThread__v_ (ee009018, 5941d0, 0, 0, 0, 0) + 28
fa435a58 ???????? (ee009018, e86de, 15ca4de, 50dc, 5941d0, c807f9c8)
fb36f9a4 ???????? (0, d412ccd8, ee046c28, ff170000, 0, 0)
fad8b278 ???????? (ee046c28, d6000c90, ee046530, 8, db8e8450, c807f9e8)
fad62abc ???????? (d412ccd8, ee046530, d6000c90, ee3bfa38, 8, c807fa18)
fa4b3c38 ???????? (c807fb9c, 0, f2134700, fa415e50, 8, c807faa8)
fa40010c ???????? (c807fc28, c807fe90, a, ee9e1e20, 4, c807fb40)
fed5d48c __1cJJavaCallsLcall_helper6FpnJJavaValue_pnMmethodHandle_pnRJavaCallArguments_pnGThread__v_ (c807fe88, c807fcf0, c807fda8, 5941d0, 5941d0, c807fd00) + 27c
fee4b784 __1cJJavaCallsMcall_virtual6FpnJJavaValue_nLKlassHandle_nMsymbolHandle_4pnRJavaCallArguments_pnGThread__v_ (ff170000, 594778, c807fd9c, c807fd98, c807fda8, 5941d0) + 164
fee5e8dc __1cJJavaCallsMcall_virtual6FpnJJavaValue_nGHandle_nLKlassHandle_nMsymbolHandle_5pnGThread__v_ (c807fe88, c807fe84, c807fe7c, c807fe74, c807fe6c, 5941d0) + 6c
fee6fc74 __1cMthread_entry6FpnKJavaThread_pnGThread__v_ (5941d0, 5941d0, 838588, 594778, 306d10, fee69254) + 128
fee6927c __1cKJavaThreadDrun6M_v_ (5941d0, 2c, 40, 0, 40, 0) + 284
fee6575c _start   (5941d0, fa1a1600, 0, 0, 0, 0) + 134
ff3758c0 lwpstart (0, 0, 0, 0, 0, 0)
=============================================================================================
Also when it's having this problem, the "VM Thread" is always using a lot of processor time. We did a couple of pstacks today while it was having this problem, and this thread was stuck in the ONMethodSweeper.sweep for over 15 minutes when we finally killed the server.
From the thread dump:
"VM Thread" prio=5 tid=0x000e2d20 nid=0x2 runnable
From the first pstack:
=============================================================================================
----------------- lwp# 2 / thread# 2 --------------------
fed40c04 __1cXvirtual_call_RelocationIparse_ic6FrpnICodeBlob_rpC5rppnHoopDesc_pi_nNRelocIterator__ (42a2f4, fa5fa46d, ffffffff, fc4ffcb8, 42a2f4, 42a324) + 124
fed46318 __1cKCompiledIC2t5B6MpnKRelocation__v_ (42a2f0, fc4ffd24, fc4ffd4c, e802, 0, 6) + 38
fed90c38 __1cHnmethodVcleanup_inline_caches6M_v_ (fa5f7f88, fa608940, 1, 0, fa400000, 6) + 1ac
fede18b4 __1cONMethodSweeperFsweep6F_v_ (2cf38, 0, ffffffff, ff1cf1fc, ff1c66e8, fede1d44) + 1b0
fede1e6c __1cUSafepointSynchronizeFbegin6F_v_ (2cf38, ff1ba138, 5000, 50dc, 5000, 525c) + 248
feef1fd4 __1cIVMThreadEloop6M_v_ (4400, 4000, 4324, 4000, 42b0, 3800) + 3d4
feef1ae4 __1cIVMThreadDrun6M_v_ (e2d20, 2, 40, 0, 40, 0) + 8c
fee6575c _start   (e2d20, ff270200, 0, 0, 0, 0) + 134
ff3758c0 lwpstart (0, 0, 0, 0, 0, 0)
=============================================================================================
Second pstack
=============================================================================================
----------------- lwp# 2 / thread# 2 --------------------
fed41180 __1cXvirtual_call_RelocationIparse_ic6FrpnICodeBlob_rpC5rppnHoopDesc_pi_nNRelocIterator__ (0, ff1b9664, ffffffff, fc4ffcb8, a6f2cc, fc4ffbd0) + 6a0
fed46318 __1cKCompiledIC2t5B6MpnKRelocation__v_ (a6f2c8, fc4ffd24, fc4ffd4c, e802, 0, 6) + 38
fed90c38 __1cHnmethodVcleanup_inline_caches6M_v_ (faded4c8, fadf2c80, 1, 0, fa400000, 6) + 1ac
fede18b4 __1cONMethodSweeperFsweep6F_v_ (2cf38, 0, ffffffff, ff1cf1fc, ff1c66e8, fede1d44) + 1b0
fede1e6c __1cUSafepointSynchronizeFbegin6F_v_ (2cf38, ff1ba138, 5000, 50dc, 5000, 525c) + 248
feef1fd4 __1cIVMThreadEloop6M_v_ (4400, 4000, 4324, 4000, 42b0, 3800) + 3d4
feef1ae4 __1cIVMThreadDrun6M_v_ (e2d20, 2, 40, 0, 40, 0) + 8c
fee6575c _start   (e2d20, ff270200, 0, 0, 0, 0) + 134
ff3758c0 lwpstart (0, 0, 0, 0, 0, 0)
=============================================================================================
Has anyone ever seen anything like this? I'm trying to figure out if this is caused by something we're doing, or something relating to our environment and jvm options. Any ideas?

Thanks for the reply - I'm testing our app with the +UseConcMarkSweepGC now in our test environment to make sure it doesn't cause any problems there. Unfortunately the only place we've had this problem is on the production server, so it's extra difficult debugging this.
We're using the following memory options:
-ms512m -mx512m -XX:NewSize=128m -XX:PermSize=192m -XX:MaxNewSize=128m -XX:MaxPermSize=192m -XX:SurvivorRatio=8and the following debugging options, as we've also been seeing OutOfMemoryErrors ( see http://forum.java.sun.com/thread.jsp?forum=37&thread=522354&tstart=45&trange=15 )
-verbosegc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintHeapAtGCBTW, which c++filt version and options are you using? Our Solaris boxes only seem to have the GNU version installed. I was trying to run that on some of the other stack traces and wasn't getting anywhere, and didn't know if because it was GNU version wouldn't work on something compiled with the Sun compiler.
Thanks!
--Andy

Problem with threads and ProgressMonitor

Dear Friends:
I have a little problem with a thread and a ProgressMonitor. I have a long time process that runs in a thread (the thread is in an separate class). The thread has a ProgressMonitor that works fine and shows the tasks progress.
But I need deactivate the main class(the main class is the user interface) until the thread ends.
I use something like this:
LongTask myTask=new LongTask();
myTask.start();
myTask.join();
Now, the main class waits for the task to end, but the progress monitor don`t works fine: it shows only the dialog but not the progress bar.
What's wrong?

Is the dialog a modal dialog? This can block other UI updates.
In general, you should make sure that it isn't modal, and that your workThread has a fairly low priority so that the UI can do its updating

Problem with threads and/or memory

I'm developing an application where there are 3 threads. One of them sends a request to the other, and if the 2nd can't answer it, it sends it to the 3rd (similar to CPU -> CACHE -> MEMORY). When i run the program with 1000-10.000 requests, no problem occurs. When i run it with 300.000-1.000.000 requests, it sometimes hangs. Is this a problem with the garbage collector, or should it be related to the threads mecanism.
(note: eache thread is in execution using a finite state machine)

i had been running the program inside Netbeans.
Running the jar using the command line outside
Netbeans i have no more problems... Does Netbeans use
it's own JVM?Depends how you set it up, but look under the options. There are settings for the compiler and jvm that it uses.

Problem with HSSF POI

Similar Messages

Maybe you are looking for