classworlds-1.1: Launcher main method (System.exit)

[Fernando Lindner Ramos]

Hello there,

I've developed an application using the Classworlds framework, and I'd like to discuss the Thread behavior inside it.

Since release 1.1, the 'System.exit' invocation inside Launcher.main method is ending any Thread started in the target class main method.

Dan Diephouse suggested me a shutdown hook as shown here:
http://svn.plexus.codehaus.org/trunk/plexus-containers/plexus-container-default/src/main/java/org/codehaus/plexus/PlexusContainerHost.java?rev=1750&view=auto

Unfortunately, this solution didn't work for us.
We're using junit.swingui.TestRunner main method inside our class, and its Swing window gets closed when the addShutdownHook is invoked, even though the thread is still alive.

I would like to propose you a solution, that won't remove the original 'exit code', but will include a Thread support.
It's a simple loop that checks for the existence of any active threads other than the main thread (please see code below):
---------------------------------------------------------
    public static void main( String[] args )
    {
        try
        {
            int initialActiveCount = Thread.activeCount();
           
            int exitCode = mainWithExitCode( args );
           
            // wait for main target Threads
            while ( Thread.activeCount() > initialActiveCount )
            {
                try
                {
                    Thread.sleep( 100 );
                }
                catch ( InterruptedException ignored )
                {
                    // ignore
                }           
            }
           
            System.exit( exitCode );
        }
        catch ( Exception e )
        {
            e.printStackTrace();
            System.exit( 100 );
        }
    }
-----------------------------------------------

Thanks!

Best Regards,
Fernando Lindner