Java Plug-in 1.3.0_01(and upwards) hangs using a background loading thread

Customer Problem Description:
-----------------------------

java version "1.3.0_01"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0_01)
Java HotSpot(TM) Client VM (build 1.3.0_01, mixed mode)

=======

A change in the 1.3.0_01 plugin prevents our application from creating our
applet's UI on a separate thread of execution. On multiple WinNT systems, the
plugin deadlocks in the separate thread when it attempts to load the first user
defined class. This technique has worked correctly in all previous releases of
the plugin. Our threading approach is simple, standard and sound.

We have seen this problem on a WinNT SP5 600 Mghz/256 RAM/IE 5.5 and a WinNT
SP4 400 Mghz/128 RAM/IE 5.5.



DESCRIPTIONEND
TESTCASEBEGIN
I can send source code separately if you need it. The three critical classes are
KronosApplet, DemoGUIBuildApplet, and BuilderThread:

// BASE APPLET CLASS

abstract public class KronosApplet extends JApplet
implements BuildTask {

/**
* Code here executes as quickly as possible to
* show a white status screen. Time consuming
* code initialization is done in the background
* thread.
*/
public final void init() {
getContentPane().setLayout(new BorderLayout());

// disable the UI while we load
getGlassPane().addMouseListener(new MouseAdapter() {});
enableUI(false);

// show a wait screen immediately:
showWaitMessage();

// let a background thread create the real display.
                // Triggers the call to runBackgroundTask(), onLoad()
startBuildTask(this);
}

public void startBuildTask(BuildTask task) {
if (task == null)
throw new IllegalArgumentException(
"No BuildTask supplied");
BuilderThread builder = new BuilderThread(task);
builder.start();
}

/**
* As per BuildTask. This executes on a user
* created thread.
*/
public final void runBackgroundTask() {
// Requests subclass to create its
// display. Time consuming work is done here.
onLoad();
}

/**
* As per BuildTask. This executes on
* the AWT Event Queue thread.
*/
public final void finishTask() {
swapRoot(_waitPanel, _rootPanel, true);
_waitPanel = null;
enableUI(true);
}

/**
* Subclass builds its UI starting with
* this method.
*/
abstract public void onLoad();

protected void setRootPanel(KronosRootPanel root) {
checkLayout();
if (null == root)
throw new IllegalArgumentException(
"No root panel supplied");
_rootPanel = root;
}

private void showWaitMessage() {
_waitPanel = new WaitPanel();
swapRoot(_rootPanel, _waitPanel, false);
}

private void swapRoot(Container oldRoot, Container newRoot,
boolean validate) {
if (oldRoot != null)
getContentPane().remove(oldRoot);
getContentPane().add(newRoot, BorderLayout.CENTER);
_rootPanel = newRoot;
if (validate) {
getRootPane().revalidate();
getRootPane().repaint();
}
}

  // etc....
}


// DERIVED CLASS

public class DemoGUIBuildApplet extends KronosApplet {

public void onLoad() {
// What happens right before we load the first class seems
// to impact the problem. Removing this System.out call
// prevents the hang from happening on some systems.
System.out.println("In onLoad");

// This is the first user defined class loaded in this
// thread. IF PLUGIN HANGS, IT WILL HANG HERE.
new DummyClass(); <---- wedges here

setRootPanel(new DemoGUIBuildRootPanel(this));
}

// etc....
}


// BACKGROUND THREAD

public class BuilderThread extends Thread {
private BuildTask _task;

public BuilderThread(BuildTask task) {
_task = task;
setPriority(Thread.MIN_PRIORITY);
}

public void run() {
_task.runBackgroundTask();
SwingUtilities.invokeLater(new Runnable() {
public void run() {
_task.finishTask();
}
});
}
}

We have been able to reproduce this problem on more than one applet. When it
fails, IT CONSISTENTLY FAILS WHEN LOADING THE FIRST USER DEFINED CLASS FROM A
USER DEFINED THREAD.

===============

Here's the output of the console trace:

Java(TM) Plug-in: Version 1.3.0_01
Using JRE version 1.3.0_01 Java HotSpot(TM) Client VM
  User home directory = C:\WINNT\Profiles\pfarwell


Proxy Configuration: no proxy





Dump system properties ...
---------------------------------------------------
application.home = C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0
awt.toolkit = sun.awt.windows.WToolkit
bridge.home = C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0
file.encoding = Cp1252
file.encoding.pkg = sun.io
file.separator = java.awt.fonts =
java.awt.graphicsenv = sun.awt.Win32GraphicsEnvironment
java.awt.printerjob = sun.awt.windows.WPrinterJob
java.class.path = .
java.class.version = 47.0
java.ext.dirs = C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0\lib\ext
java.home = C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0
java.io.tmpdir = C:\TEMPjava.library.path = C:\Program Files\Plus!\Microsoft
Internet;.;C:\WINNT\System32;C:\WINNT;C:\PROGRA~1\Plus!\MICROS~1
\;;C:\WINNT\system32;C:\WINNT;D:\batch;D:\OptimizeIt\OptimizeIt31\lib;D:\MSSQL7
\BINN;d:\Kronos\wfc\properties
java.runtime.name = Java(TM) 2 Runtime Environment, Standard Edition
java.runtime.version = 1.3.0_01
java.specification.name = Java Platform API Specification
java.specification.vendor = Sun Microsystems Inc.
java.specification.version = 1.3
java.vendor = Sun Microsystems Inc.
java.vendor.url = http://java.sun.com/
java.vendor.url.bug = http://java.sun.com/cgi-bin/bugreport.cgi
java.version = 1.3.0_01
java.vm.info = mixed mode
java.vm.name = Java HotSpot(TM) Client VM
java.vm.specification.name = Java Virtual Machine Specification
java.vm.specification.vendor = Sun Microsystems Inc.
java.vm.specification.version = 1.0
java.vm.vendor = Sun Microsystems Inc.
java.vm.version = 1.3.0_01
javaplugin.maxHeapSize = 128m
javaplugin.nodotversion = 130_01
javaplugin.trace = true
javaplugin.trace.option = basic|net|security|ext|liveconnect
javaplugin.version = 1.3.0_01
line.separator = \r\n
os.arch = x86
os.name = Windows NT
os.version = 4.0
path.separator = ;
sun.boot.class.path = C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0
\lib\rt.jar;C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0\lib\i18n.jar;C:\PROGRA~1
\JavaSoft\JRE\13C255~1.0_0\lib\sunrsasign.jar;C:\PROGRA~1
\JavaSoft\JRE\13C255~1.0_0\classes;C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0
\lib\jaws.jar;C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0\lib\tools.jar;C:\PROGRA~1
\JavaSoft\JRE\13C255~1.0_0\lib\plugprov.jar;C:\PROGRA~1
\JavaSoft\JRE\13C255~1.0_0\lib\sunrsasign.jar
sun.boot.library.path = C:\PROGRA~1\JavaSoft\JRE\13C255~1.0_0\bin
sun.cpu.endian = little
sun.cpu.isalist = pentium_pro+mmx pentium_pro pentium+mmx pentium i486 i386
sun.io.unicode.encoding = UnicodeLittle
trustProxy = true
user.dir = C:\WINNT\Profiles\pfarwell\Desktop
user.home = C:\WINNT\Profiles\pfarwell
user.language = en
user.name = pfarwell
user.region = US
user.timezone =
---------------------------------------------------
Done.


----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
l: dump classloader list
m: print memory usage
q: hide console
s: dump system properties
t: dump thread list
x: clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------


Registered modality listener


Referencing classloader: sun.plugin.ClassLoaderInfo@72e449, refcount=1


Added trace listener: sun.plugin.ocx.ActiveXAppletViewer
[com/kronos/wfc/applets/appletdemo/DemoGUIBuildApplet,0,0,737x419,invalid,layout
=java.awt.BorderLayout]


Sending events to applet. LOAD


Sending events to applet. INIT


Sending events to applet. START


Determine if the applet requests to install any HTML page


HTML Installation finished.


Determine if the applet requests to install any JAR


Jar cache option: null
Jar archive(s): null
Jar cache version(s): null


Applet Installation finished.


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/applets/appletdemo/DemoGUIBuildAppl
et.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\DemoGUIBuildApplet[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/baseapplet/KronosAp
plet.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\KronosApplet[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/utility/BuildTask.c
lass


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\BuildTask[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/baseapplet/KronosAp
plet$WaitPanel.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\KronosApplet$WaitPanel[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/utility/BuilderThre
ad.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\BuilderThread[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/baseapplet/KronosRo
otPanel.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\WJYV2PQF\KronosRootPanel[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/component/KronosPan
el.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\KronosPanel[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/applets/appletdemo/DemoGUIBuildRoot
Panel.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\WJYV2PQF\DemoGUIBuildRootPanel[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/wfp/uiframework/baseapplet/KronosAp
plet$1.class


Cache filename: C:\WINNT\Profiles\pfarwell\Temporary Internet Files\Content.IE5
\QB0PKX6H\KronosApplet$1[1].class


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/applets/appletdemo/DemoGUIBuildAppl
etBeanInfo.class


Connecting
http://pfarwellnt/scratch/lib/com/kronos/wfc/applets/appletdemo/DemoGUIBuildAppl
etBeanInfo.class with no proxy


In onLoad


Opening
http://pfarwellnt/scratch/lib/com/kronos/wfc/applets/appletdemo/DummyClass.class
 <-- WEDGES HERE


Removed trace listener: sun.plugin.ocx.ActiveXAppletViewer
[com/kronos/wfc/applets/appletdemo/DemoGUIBuildApplet,0,0,737x419,layout=java.aw
t.BorderLayout]
workaround: None found.