Re: Terminating a thread when program exits.

"vjg" <>
23 Jan 2007 10:38:43 -0800
Ian Wilson wrote:

Sun's developer online training website has an example of a JDBC
connection pool.

One of the things it does is start a "reaper" thread that watches for
stale connections (see below).

If I run my test program from Eclipse, this reaper thread keeps running
when my program has otherwise finished. I didn't notice this to start
with and so after a few test runs Eclipse started reporting that the VM
was out of memory.

I think I need to replace "while(true") below with "while(poolExists)"
and set poolExists to false somehow when my program wants to exit.

The JDCConnectionPool is instantiated by the constructor of
JDCConnectionDriver which I instantiate in my application start-up.

Because the pool is written as a JDBC driver wrapper, there's not much
leverage for the app to force a clean up.

I suppose I could add a finalize() to JDCConnectionDriver and some
methods in JDBCConnectionPool and ConnectionReaper to set poolExists false.

I'm not sure if this is a good way to go about this, ideas?

I'd just set the reaper thread to be a daemon thread before starting
it. That way it will die a natural death when the JVM shuts down (i.e.
when your application closes down normally).

Also the sleep() lasts 5 mins, I'd prefer some way to force a quicker
interruption of this sleep() - Thread.interrupt()?

---------------- from JDCConnectionPool -----------------------
class ConnectionReaper extends Thread {

     private JDCConnectionPool pool;
     private final long delay=300000;

     ConnectionReaper(JDCConnectionPool pool) {

     public void run() {
         while(true) {
            try {
            } catch( InterruptedException e) { }

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