My upload hangs after 30 kb

Question

Am working with uploading a file from one client to another
client through a server(because of securety reasons) but somehow
only 30kb og data can be uploadet then the application just stops.
No errors are givin it just hangs. If the file is smaller than 30 kb
then the hole file is uploadet without any problems.
Can anyone help me with this? This is my code:
****upload client:
    private void upload(File file){
        System.out.println("Starting UploadClientThread");
        try{
            InputStream is = new FileInputStream(file);
            long fileSize = file.length();
            System.out.println("Filesize is: "+fileSize);
            byte[] b = new byte[1000];
            int n;
            while((n = is.read(b)) >= 0) {
                fileSize = fileSize-n;
                System.out.println("sending: "+n+" left of file: "+fileSize);
                os.write(b, 0, n);
                os.flush();
            System.out.println("Finished sending file");
            os.close();
            is.close();
            socket.close();
        }catch(FileNotFoundException fe){
            fe.printStackTrace();
        }catch(IOException io){
            io.printStackTrace();
*****download client:
    private void download(){
        System.out.println("Starting DownloadClientThread");
        System.out.println("Saving file: "+file.toString());
        try{
            OutputStream os = new FileOutputStream(file);
            byte[] b = new byte[1000];
            int n;
            while((n = is.read(b)) >= 0) {
                System.out.println("receiving "+n);
                os.write(b, 0, n);
            System.out.println("Finished receiving file");
            os.close();
            is.close();
            socket.close();
        }catch(FileNotFoundException fe){
            fe.printStackTrace();
        }catch(IOException io){
            io.printStackTrace();
*****uploadhandler (on server):
        while(true){
            try{
                Socket s = ss.accept();
                clientList.add(s);
                FileThread fileThread = new FileThread(s,this);
                fileThread.start();
            }catch(IOException io){
                io.printStackTrace();
******FileThread (on server):
    public void run(){
        byte[] b = new byte[1000];
        List<Socket> clientList = uh.getClientList();
        try{
            while(true) {              
                int n;
                while((n = is.read(b)) >= 0) {
                    System.out.println("send to clients "+n);
                    for(Socket socket : clientList){
                        if(socket != null && !socket.isClosed()){
                            OutputStream os =  socket.getOutputStream();
                            os.write(b, 0, n);
                   os.flush();     
        }catch(IOException io){
            io.printStackTrace();
    }

Answer 1

This output is from the client who sends the file:
Full thread dump Java HotSpot(TM) Client VM (1.5.0_03-b07 mixed mode, sharing):
"Thread-6" prio=4 tid=0x03e2dbd0 nid=0x914 runnable [0x08adf000..0x08adf9e8]
     at java.net.SocketOutputStream.socketWrite0(Native Method)
     at java.net.SocketOutputStream.socketWrite(Unknown Source)
     at java.net.SocketOutputStream.write(Unknown Source)
     at java.io.BufferedOutputStream.flushBuffer(Unknown Source)
     at java.io.BufferedOutputStream.flush(Unknown Source)
     - locked <0x2166f160> (a java.io.BufferedOutputStream)
     at dk.aslani.chat_client.control.UploadClientThread.upload(UploadClientThread.java:83)
     at dk.aslani.chat_client.control.UploadClientThread.run(UploadClientThread.java:101)
"ConsoleWriterThread" daemon prio=7 tid=0x03f32398 nid=0xce0 in Object.wait() [0x03aff000..0x03affa68]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x2129c250> (a java.lang.Object)
     at java.lang.Object.wait(Unknown Source)
     at com.sun.deploy.util.ConsoleTraceListener$ConsoleWriterThread.run(Unknown Source)
     - locked <0x2129c250> (a java.lang.Object)
"Thread-7" prio=5 tid=0x03f4f2a8 nid=0x2b4 runnable [0x00000000..0x07d7f71c]
"Thread-5" prio=4 tid=0x051a0a80 nid=0xa3c runnable [0x087ff000..0x087ffc68]
     at java.net.SocketInputStream.socketRead0(Native Method)
     at java.net.SocketInputStream.read(Unknown Source)
     at sun.nio.cs.StreamDecoder$CharsetSD.readBytes(Unknown Source)
     at sun.nio.cs.StreamDecoder$CharsetSD.implRead(Unknown Source)
     at sun.nio.cs.StreamDecoder.read(Unknown Source)
     - locked <0x21608510> (a java.io.InputStreamReader)
     at java.io.InputStreamReader.read(Unknown Source)
     at java.io.BufferedReader.fill(Unknown Source)
     at java.io.BufferedReader.readLine(Unknown Source)
     - locked <0x21608510> (a java.io.InputStreamReader)
     at java.io.BufferedReader.readLine(Unknown Source)
     at dk.aslani.chat_client.control.ChatThread.run(ChatThread.java:24)
"AWT-EventQueue-2" prio=4 tid=0x03e919c0 nid=0x5c0 in Object.wait() [0x0827f000..0x0827fd68]
     at java.lang.Object.wait(Native Method)
     at java.lang.Object.wait(Unknown Source)
     at java.awt.EventQueue.getNextEvent(Unknown Source)
     - locked <0x212a7508> (a java.awt.EventQueue)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.run(Unknown Source)
"TimerQueue" daemon prio=4 tid=0x05125300 nid=0x9f0 in Object.wait() [0x07f7f000..0x07f7f9e8]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x215cc9c8> (a javax.swing.TimerQueue)
     at javax.swing.TimerQueue.run(Unknown Source)
     - locked <0x215cc9c8> (a javax.swing.TimerQueue)
     at java.lang.Thread.run(Unknown Source)
"TimerQueue" daemon prio=5 tid=0x05169d40 nid=0x590 in Object.wait() [0x085ff000..0x085ffae8]
     at java.lang.Object.wait(Native Method)
     at javax.swing.TimerQueue.run(Unknown Source)
     - locked <0x213ecc28> (a javax.swing.TimerQueue)
     at java.lang.Thread.run(Unknown Source)
"TimerQueue" daemon prio=5 tid=0x05162b08 nid=0x5b4 in Object.wait() [0x0847f000..0x0847fb68]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x213e7398> (a javax.swing.TimerQueue)
     at javax.swing.TimerQueue.run(Unknown Source)
     - locked <0x213e7398> (a javax.swing.TimerQueue)
     at java.lang.Thread.run(Unknown Source)
"AWT-EventQueue-1" prio=7 tid=0x05156c20 nid=0xa4c waiting on condition [0x0837f000..0x0837fbe8]
     at sun.plugin.JavaRunTime.dumpAllStacks(Native Method)
     at sun.plugin.util.PluginConsoleController.dumpAllStacks(Unknown Source)
     at com.sun.deploy.util.ConsoleWindow$1.actionPerformed(Unknown Source)
     at javax.swing.JComponent$ActionStandin.actionPerformed(Unknown Source)
     at javax.swing.SwingUtilities.notifyAction(Unknown Source)
     at javax.swing.JComponent.processKeyBinding(Unknown Source)
     at javax.swing.KeyboardManager.fireBinding(Unknown Source)
     at javax.swing.KeyboardManager.fireKeyboardAction(Unknown Source)
     at javax.swing.JComponent.processKeyBindingsForAllComponents(Unknown Source)
     at javax.swing.JComponent.processKeyBindings(Unknown Source)
     at javax.swing.JComponent.processKeyEvent(Unknown Source)
     at java.awt.Component.processEvent(Unknown Source)
     at java.awt.Container.processEvent(Unknown Source)
     at java.awt.Component.dispatchEventImpl(Unknown Source)
     at java.awt.Container.dispatchEventImpl(Unknown Source)
     at java.awt.Component.dispatchEvent(Unknown Source)
     at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
     at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
     at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
     at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
     at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
     at java.awt.Component.dispatchEventImpl(Unknown Source)
     at java.awt.Container.dispatchEventImpl(Unknown Source)
     at java.awt.Window.dispatchEventImpl(Unknown Source)
     at java.awt.Component.dispatchEvent(Unknown Source)
     at java.awt.EventQueue.dispatchEvent(Unknown Source)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.run(Unknown Source)
"thread applet-dk.aslani.chat_client.view.AppletForm.class" prio=4 tid=0x03e9fdf0 nid=0xa10 in Object.wait() [0x0807f000..0x0807f9e8]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x2128c538> (a sun.plugin.AppletViewer)
     at java.lang.Object.wait(Unknown Source)
     at sun.applet.AppletPanel.getNextEvent(Unknown Source)
     - locked <0x2128c538> (a sun.plugin.AppletViewer)
     at sun.applet.AppletPanel.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
"AWT-EventQueue-0" prio=7 tid=0x03d6a950 nid=0xcc8 in Object.wait() [0x07e7f000..0x07e7fb68]
     at java.lang.Object.wait(Native Method)
     at java.lang.Object.wait(Unknown Source)
     at java.awt.EventQueue.getNextEvent(Unknown Source)
     - locked <0x212488c8> (a java.awt.EventQueue)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.run(Unknown Source)
"traceMsgQueueThread" daemon prio=5 tid=0x03eba7a0 nid=0x384 in Object.wait() [0x07c7f000..0x07c7fc68]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x21255b28> (a java.util.ArrayList)
     at java.lang.Object.wait(Unknown Source)
     at com.sun.deploy.util.Trace$TraceMsgQueueChecker.run(Unknown Source)
     - locked <0x21255b28> (a java.util.ArrayList)
     at java.lang.Thread.run(Unknown Source)
"AWT-Windows" daemon prio=7 tid=0x03d65860 nid=0xba0 runnable [0x07a7f000..0x07a7fce8]
     at sun.awt.windows.WToolkit.eventLoop(Native Method)
     at sun.awt.windows.WToolkit.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
"AWT-Shutdown" prio=5 tid=0x02ffed78 nid=0xb0 in Object.wait() [0x0797f000..0x0797fd68]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x21254d48> (a java.lang.Object)
     at java.lang.Object.wait(Unknown Source)
     at sun.awt.AWTAutoShutdown.run(Unknown Source)
     - locked <0x21254d48> (a java.lang.Object)
     at java.lang.Thread.run(Unknown Source)
"Java2D Disposer" daemon prio=10 tid=0x02fa6828 nid=0x624 in Object.wait() [0x0787f000..0x0787f9e8]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x21254dd0> (a java.lang.ref.ReferenceQueue$Lock)
     at java.lang.ref.ReferenceQueue.remove(Unknown Source)
     - locked <0x21254dd0> (a java.lang.ref.ReferenceQueue$Lock)
     at java.lang.ref.ReferenceQueue.remove(Unknown Source)
     at sun.java2d.Disposer.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
"Low Memory Detector" daemon prio=5 tid=0x02f8c480 nid=0x1d4 runnable [0x00000000..0x00000000]
"CompilerThread0" daemon prio=10 tid=0x02f8b1e0 nid=0xb98 waiting on condition [0x00000000..0x0757f84c]
"Signal Dispatcher" daemon prio=10 tid=0x02f893a0 nid=0xf80 runnable [0x00000000..0x00000000]
"Finalizer" daemon prio=9 tid=0x02f58008 nid=0x26c in Object.wait() [0x0737f000..0x0737fc68]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x21254f78> (a java.lang.ref.ReferenceQueue$Lock)
     at java.lang.ref.ReferenceQueue.remove(Unknown Source)
     - locked <0x21254f78> (a java.lang.ref.ReferenceQueue$Lock)
     at java.lang.ref.ReferenceQueue.remove(Unknown Source)
     at java.lang.ref.Finalizer$FinalizerThread.run(Unknown Source)
"Reference Handler" daemon prio=10 tid=0x03e10850 nid=0xa64 in Object.wait() [0x04e4f000..0x04e4fce8]
     at java.lang.Object.wait(Native Method)
     - waiting on <0x21254ff8> (a java.lang.ref.Reference$Lock)
     at java.lang.Object.wait(Unknown Source)
     at java.lang.ref.Reference$ReferenceHandler.run(Unknown Source)
     - locked <0x21254ff8> (a java.lang.ref.Reference$Lock)
"main" prio=5 tid=0x03dd9948 nid=0xb80 runnable [0x00000000..0x02cef8dc]
"VM Thread" prio=10 tid=0x02f03158 nid=0xf98 runnable
"VM Periodic Task Thread" prio=10 tid=0x02fc19a8 nid=0xdd4 waiting on condition
Done.