CallVoidMethod blocks when it shouldn't be

Question

I am having a preformance problem when calling a java method from C. Here is the java method I am calling:
public void broadcastProgress() {
        //tell the server of our progress so it can tell all the clients
        Thread broadcastThread = new Thread() {
            public void run() {
                StorageRmiProxy.updateProgress(StorageDeviceImpl.this,
                                        fileName, fileProgress, totalProgress);
        broadcastThread.start();
    }and here is how I am calling it from C:
I already have the MethodID for it, so i'm just calling it.
(*jenv)->CallVoidMethod(jenv, this, broadcastMid);
And most of the time, the call blocks and waits for a while. Now, I think that it should return immediately from this call becuase everything in that method is run in a thread, so it should start the thread and return. Am I missing somthing here? If any one can help I would greately appreicate it!
Thanks
Andrew

Answer 1

And most of the time, the call blocks and waits for a
while.What is "a while"?
Is this a multi-cpu box?
Is it different than if you do the same thing but don't do anything in the run() method? Or if you don't do anything in the native method but sleep?