FULL PRODUCT VERSION :
java version "1.6.0_21"
Java(TM) SE Runtime Environment (build 1.6.0_21-b07-288-10M3222)
Java HotSpot(TM) 64-Bit Server VM (build 17.0-b17-288, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Darwin Shadowfax.local 10.4.0 Darwin Kernel Version 10.4.0: Fri Apr 23 18:28:53 PDT 2010; root:xnu-1504.7.4~1/RELEASE_I386 i386

Also happens on Windows XP and Windows 7


A DESCRIPTION OF THE PROBLEM :
Our Applet works fine as long as there is no crossdomain.xml file on the server.

Once we put a crossdomain.xml on the root of the web server - for Flash, not for Java - the Applet started to freeze on load.

The thread dump shows very clearly how a deadlock prevents the Applet from starting. Please fix this, it's terrible.

Here are the relevant parts of the Java thread dump:


"MMX-AppletLoadTracker" daemon prio=4 tid=101998000 nid=0x12f689000 waiting for monitor entry [12f687000]
   java.lang.Thread.State: BLOCKED (on object monitor)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Plugin2ClassLoader.java:160)
- waiting to lock <107ac08a8> (a sun.plugin2.applet.Applet2ClassLoader)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
at javax.xml.parsers.FactoryFinder.getProviderClass(FactoryFinder.java:111)
at javax.xml.parsers.FactoryFinder.newInstance(FactoryFinder.java:146)
at javax.xml.parsers.SAXParserFactory.newInstance(SAXParserFactory.java:176)
at com.sun.deploy.net.CrossDomainXML$2.run(CrossDomainXML.java:364)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.deploy.net.CrossDomainXML.check(CrossDomainXML.java:354)
at com.sun.deploy.net.CrossDomainXML.check(CrossDomainXML.java:148)
- locked <10f935988> (a java.lang.Class for com.sun.deploy.net.CrossDomainXML)
at sun.plugin2.applet.Applet2SecurityManager.checkConnect(Applet2SecurityManager.java:513)
at java.net.InetAddress.getAllByName0(InetAddress.java:1146)
at java.net.InetAddress.getAllByName(InetAddress.java:1084)
at java.net.InetAddress.getAllByName(InetAddress.java:1020)
at java.net.InetAddress.getByName(InetAddress.java:970)
at java.net.URLStreamHandler.getHostAddress(URLStreamHandler.java:420)
- locked <107adcaa0> (a sun.net.www.protocol.http.Handler)
at java.net.URLStreamHandler.hostsEqual(URLStreamHandler.java:439)
at java.net.URLStreamHandler.sameFile(URLStreamHandler.java:396)
at java.net.URLStreamHandler.equals(URLStreamHandler.java:316)
at java.net.URL.equals(URL.java:842)
at sun.plugin2.applet.Plugin2Manager$AppletContextImpl.getApplet(Plugin2Manager.java:2722)
at net.prophet.matrix.c.f.run(f.java:6)


"thread applet-net.prophet.matrix.MarketMatrix.class-1" prio=4 tid=103166800 nid=0x12b8e1000 waiting for monitor entry [12b8de000]
   java.lang.Thread.State: BLOCKED (on object monitor)
at java.net.URLStreamHandler.getHostAddress(URLStreamHandler.java:412)
- waiting to lock <107adcaa0> (a sun.net.www.protocol.http.Handler)
at java.net.URLStreamHandler.hostsEqual(URLStreamHandler.java:439)
at java.net.URLStreamHandler.sameFile(URLStreamHandler.java:396)
at java.net.URLStreamHandler.equals(URLStreamHandler.java:316)
at java.net.URL.equals(URL.java:842)
at java.security.CodeSource.equals(CodeSource.java:135)
at com.sun.deploy.security.CPCallbackHandler.checkPackage(CPCallbackHandler.java:658)
- locked <107b2aae0> (a com.sun.deploy.security.CPCallbackHandler)
at com.sun.deploy.security.CPCallbackHandler.access$1700(CPCallbackHandler.java:82)
at com.sun.deploy.security.CPCallbackHandler$ChildElement.checkResource(CPCallbackHandler.java:486)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.checkResource(DeployURLClassPath.java:790)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.getResource(DeployURLClassPath.java:890)
at com.sun.deploy.security.DeployURLClassPath.getResource(DeployURLClassPath.java:231)
at sun.plugin2.applet.Plugin2ClassLoader$2.run(Plugin2ClassLoader.java:950)
at java.security.AccessController.doPrivileged(Native Method)
at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Plugin2ClassLoader.java:939)
at sun.plugin2.applet.Applet2ClassLoader.findClass(Applet2ClassLoader.java:133)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Plugin2ClassLoader.java:249)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Plugin2ClassLoader.java:179)
- locked <107ac08a8> (a sun.plugin2.applet.Applet2ClassLoader)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Plugin2ClassLoader.java:160)
- locked <107ac08a8> (a sun.plugin2.applet.Applet2ClassLoader)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
at net.prophet.matrix.MarketMatrix.start(MarketMatrix.java:176)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Plugin2Manager.java:1681)
at java.lang.Thread.run(Thread.java:637)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create an Applet which spins a separate thread, and in this separate thread calls AppletContext.getApplet(name) to access the other applets on the same page.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No deadlock
ACTUAL -
deadlock

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Have not found a workaround so far.

I think signing the Applet would work since it would then not load the crossdomain.xml file. But I have so far avoided that since the Applet does not need full access to the user's computer.