JDK-6393921 : JVM hang when multiple applets are loaded and simultaneous window refocus actions
  • Type: Bug
  • Component: deploy
  • Sub-Component: plugin
  • Affected Version: 1.4.2_08
  • Priority: P1
  • Status: Resolved
  • Resolution: Fixed
  • OS: windows
  • CPU: x86
  • Submitted: 2006-03-03
  • Updated: 2010-05-10
  • Resolved: 2006-04-11
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Other JDK 6 JDK 7
1.4.2_12 b02Fixed 6-poolResolved 7Resolved
Related Reports
Relates :  
This problem is reported by customer Merrill Lynch,
the following testcase is submitted by customer to demonstrate the problem.

1. Run on a dual cpu machine, or a single cpu with hyperthreading turned on
2. Run IE, load SmallApplet.html from /net/cores.central/cores/64930555/Mar03/LargerApplet.d
3. SmallApplet.htmi invokes SmallApplet multiple times, 
   while it is still loading, move some other
   windows around and on top of the browser,  
   the browser will hang at that point

Note that this ia an intermittent problem.
I found it easier to reproduce with the following sequence of events:

- enable java console
- load URL
- when IE prompt for:
"To help protect your security, IE has restricted this file from showing active content..."
- select "allow Blocked content"
- when the security popup appears, click "yes" and quickly move mouse
  over to the area where the java console window will appear and click on it
- the browser is now hang, java console overlapped with browser window at this point.

I have captured stack trace with windbg in /net/cores.central/cores/64930555/Mar03/LargerApplet.d/windows.stacktrace 

I am not sure if this is a plugin, awt, or browser interaction issue at this point.
java stack trace in

EVALUATION The main thread of Java plugin is blocked and no message loop to dispatch windows messages.