Re: Seeing is believing?

"Richard Maher" <>
Thu, 4 Nov 2010 18:00:54 +0800
Hi Daniel,

"Daniel Pitts" <> wrote in message

On 11/3/2010 7:03 AM, Richard Maher wrote:


Do you not see the same thread being used from init() [up until the code
that calls JSObject.getWindow(this)] then isAuthorized receives control
the very same thread, and when that finishes the rest of init() gets

So, the problem appears to be that JSObject.getWindow(this) actually cedes
control back to the JS engine parser.

No, I/we can put up with this wierdness; what I cannot countenance is Chrome
*and specifically/uniquely Chrome* draining-the-queue via the same bloody
Thread that init() is running in!

If someone could just postulate on (a) How the JS-Java upcall gets allocated
to a Thread, (b) How such swinger Threads make their availability known to
Chrome, and/or (c) How a Java Thread unilaterally assigns itself available
work, then I'm more than willing to hear it!

My theory is that, on the 2nd applet instance, the timing is such that the
isAuthorized() Applet call arrives before Chrome has had a chance to set the
There's-Tricky-LiveConnect-Crap-Here flag and the method gets executed on
the natural choice of the standard applet thread rather than the LiveConnect
worker thread. But someone with knowledge of A, B, or C from above would be
in a far better place to answer that question.

Perhaps you should avoid calling JSObject.getWindow(this) in init().

Yes, yes, yes. As with your first reply, the "if (firstTimeFlag = "Y")
doInit();" should work, but it's bloody inconvenient writing off everything
that Applet.init() is contracted to do and is just bollocks in my opinion.
Having said that, pragmatism leads me in that direction :-(

Again, this is only Chrome. (BTW for IE>7 you have to set the registry
setting TabProcGrowth < 2)

Is currentThread() stooging me? Is there something there that I don't
understand? Or is it you that won't see what's in front of our faces?

Yes, there is a lot you don't understand, like how to put together an
SSCCE which could show this problem ;-).

Look the crying shame (and imho more evidence of the exception/bug) is that
I can't reproduce it without the several thousand complex lines of Java that
goes with it :-( Having said that, please see below for a "working" version
that happily engages the LiveConnect Worker Thread for isDone() every time.

If anyone is willing to play around with this in order to reproduce the
described behaviour then compile and in to a JAR
called Sleeper2.jar then stick that in your web root directory with
dyntest.html and give it a go. Turn the Java Console on to see what's

Anyway, the solution is to avoid calling getWindow(this) in init(), or at
least waiting until the rest of your initialization is complete.


Cheers Richard Maher

import java.applet.Applet;
import netscape.javascript.JSObject;
//import netscape.javascript.JSException;
//import java.lang.InterruptedException;
import java.util.ArrayList;

public class Sleeper extends Applet {
    private int myNum = 0;
    private JSObject browser;
    private volatile static int appletIndex = 0;
    private static OutThread writer;
    private boolean initFlag = false;
    private volatile static ArrayList<JSObject> windows = new

    public synchronized void init() {
       Thread curr = Thread.currentThread();
       System.out.println(" In Init() " + curr.getName() +
         curr + " hash " + Integer.toHexString(curr.hashCode()));
       try {
           browser = JSObject.getWindow(this); }
       catch (netscape.javascript.JSException e) {
           e.printStackTrace(); }
       catch (Exception e) {
           e.printStackTrace(); }


        if (writer == null){
         writer = new OutThread("Fred", windows);
        System.out.println("Before sleep call");
        try {
        catch (InterruptedException e){
        System.out.println("After sleep call");
        myNum = 33;
        initFlag = true;

    public synchronized boolean isDone() {
        Thread curr = Thread.currentThread();
        System.out.println(" In isDone() " + curr.getName() +
          curr + " hash " + Integer.toHexString(curr.hashCode()));
     return initFlag;

    public synchronized int getNum(String caller){
        int i = myNum++;
        Thread curr = Thread.currentThread();
        System.out.println("in getNum() " + myNum + " caller " + caller + "
Thread " +
          curr.getName() +
          curr + " hash " + Integer.toHexString(curr.hashCode()));
        return i;

   public synchronized void destroy ()
       System.out.println("Checked - out");

import netscape.javascript.JSObject;
import java.util.ArrayList;

class OutThread extends Thread {
 ArrayList<JSObject> windows;

    public OutThread(String name, ArrayList<JSObject> windows) {
     System.out.println("Thread constructor");
     this.setDaemon(true); = windows;

    public void run() {
     int sel = -1;
     JSObject browser;
     while (true) {
             if (sel == windows.size()){
              sel = 0;
             browser = windows.get(sel);
      try {
       sleep((int)(Math.random() * 1000));"tickOver", null);
      } catch (InterruptedException e) {break;}


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"




    background-color: aliceblue;
    color: black;
    font-family: Georgia;
    font-size: 12px;
    margin-left: 5px;
    margin-right: 5px;
    margin-top: 1px;
    padding: 0;


    <script type="text/javascript">

    var cntr = 0;
    var chan;

    function load()
      var objectTag = "<object classid=";

      if (/Internet Explorer/.test(navigator.appName)) {
        objectTag = objectTag +
            '"clsid:8AD9C840-044E-11D1-B3E9-00805F499D93" ';
      } else {
        objectTag = objectTag +
            '"java:Sleeper.class" type="application/x-java-applet" ' +
            'archive="" ';

      objectTag = objectTag +
          'width= "0" height= "0" name="TestApp" id="TestApp">' +
          '<param name="archive" value="Sleeper2.jar">' +
          '<param name="codebase" value="">' +
          '<param name="code" value="Sleeper">' +
          '<param name="java_version" value="1.6+">' +
          '<param name="mayscript" value="true">' +
          '<param name="scriptable" value="true">' +
          '<param name="codebase_lookup" value="false">' +

      var appletDiv = document.createElement("div");
      appletDiv.innerHTML = objectTag;

      try {
        chan = document.getElementById("TestApp");
      catch(err) {
          alert("Tier3 unable to load applet: -\n" +
          chan = null;

      if (chan == null) {
        throw new Error("Tier3 was unable to initialize the applet");
      } else {
        try {
            if (!chan.isDone())
        catch(err) {
            chan = null;
            throw new Error("Tier3 unable to load applet: -\n" +

    function tickOver(){

    function fred(){


  <body id="torso" onload="load()">
    <form name="mfForm">
               style="font-size: 11px";


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