(process) why do we need Thread.sleep after Runtime.getRuntime().exec(cmd)?

on solaris:

test case at: (test.java also attached in this bugreport)

http://web-east.east/~ngthomas/exec_bug/

with java 1.4:

test.java suppose to launch netscape with Runtime.getRuntime().exec()

However netscape will only be launch if there is Thread.sleep after exec()

try:

java test -> nothing happens

java test sleep -> netscape launches

why?

if you change netscape to dtterm, it will work even if thread.sleep is not called. but since runtime.exec suppose to run the command in a separate process, it should not matter how long does it take for the application to launch right?