Running a batch process (via thread) in java

Question

Friends I have gone thru 2 books of java and everywhere it says
that
1) the main thread is the one from which other child threads will
be spawned.
2)Main thread must be the last thread to finish execution.When the main thread stops,your program terminates.
Then I am wondering how it works in my case (albeit with little unpredictably !)
I have this JSP and java application.I throw this JSP and pressing a Submit button I execute a java method in Myclass.java.
If the book is true then this should not work.But it works.
Note that I am using Apache server.
please help.
Myjsp.jsp
processSubmission(true)
class Myclass implements runnable
public void processSubmission(boolean background) throws Exception
if (background) {
Thread oThread = new Thread(this);
oThread.setDaemon(false);
oThread.start();
message = "submission being processed in the background";
return;
my huge batch processing java codes.
public void run()
try
processSubmission(false);
catch(Exception e)

Answer 1

Friends I have gone thru 2 books of java and
everywhere it says
that
1) the main thread is the one from which other child
threads will
be spawned.
2)Main thread must be the last thread to finish
execution.When the main thread stops,your program
terminates.
No.
Your program stops when all of the non-daemon threads exit or if the application is explicitly exited - via System.exit().
Even if you substitute daemon for 'child' in the above it still does not apply.
From the java docs
The Java Virtual Machine exits when the only threads running are all daemon threads.
It doesn't say anything about a 'main' thread. And specifically it is likely that all of your threads will be done before the daemon threads have stopped. So it is much more likely that any 'main' threads will stop first and then the daemon threads stop (I can't see it happening any other way.)
Even so I would not rely on execution ordering threads for any purpose. If you need execution ordering then you must explicitly provide for it in your code.