FULL PRODUCT VERSION :
java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)
ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Versione 5.1.2600]
EXTRA RELEVANT SYSTEM CONFIGURATION :
Internet Explorer 7 or Firefox 2.0
A DESCRIPTION OF THE PROBLEM :
The SingleInstanceService does not work correctly on JRE version 1.6.0_03, while it worked fine with previous versions of the JRE, including JRE version 1.6.0_02.
Launching multiple times the JNLP of a Java Web Start application which register itself as a SingleInstanceListener causes multiple instances of that application to be launched. This is an incorrect behavior. The correct behavior would be that subsequent calls to the JNLP file of a "single instance application" shall cause the existing instance to be notified through a call to the newActivation(...) method, instead of opening a new instance.
With JRE version 1.6.0_03, the correct behavior can be obtained only in rare "random" occasions.
The same "single instance" application always works correctly if run with JRE version 1.6.0_02: in this case, a single instance of the application exists, and that instance is notified in case of several calls to the JNLP file.
STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
On a machine where JRE v1.6.0_03 is installed, try loading several times the following URL through your web browser (I used both IE 7 and Firefox 2.0, with the same result):
EXPECTED VERSUS ACTUAL BEHAVIOR :
Only a single instance of the Java Web Start application should be open, and it shall get notified when subsequent calls to the JNLP are made.
Most often, multiple instances of the test Java Web Start application get opened.
This bug can be reproduced often.
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Source code by Andrew Thompson.
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CUSTOMER SUBMITTED WORKAROUND :
Use an older JRE version.
For instance, JRE version 1.6.0_02 is working fine from this point of view.
Release Regression From : 6u2
The above release value was the last known release where this
bug was not reproducible. Since then there has been a regression.