Thread stopping

Question

HI, I have a question regarding the use of threads in my program.
I have 4 classes which I have implemented as Runnable. Each class uses it's run method to call methods which carry out queries on a database. I have a thread t which I use to run the methods.
public void run()
        setTotalIncoming();
        getTotalOutbound();
        setTotalLostCalls();
        setTotalCallsSentToVoicemail();
        getOutOfHoursVoicemail();
        setPercentAnswered();
        getTotalPhoneTime();
        getTotalTalkTime();
        setAverageAnswerTime();
        setLostRingingTime();
        setVoicemailRingingTime();
        getOutOfHoursRingingTime();
     }The problem is that periodically (unspecified time periods), my program calls the refresh() method in my program which re-assigns my thread t. Shown here:
public void refresh()
        while(isRunning){
            // wait for thread to finish
        t = new Thread(this);
     t.start();
    }Now, the problem is that, currently, my program could re-assign t, whilst the run() method wasn't finished executing all it's methods. I think this is causing some unexpected behaviour in my code.
I am noticing this in my ConnectionPool class, which I know is sound, as it is a very similar adaptation on code found in a well known book. Basically my program manages to open more connections that the Maximum no. of connections is set to in the ConnectionPool.
Does anyone have any ideas:
1. How I can ensure that all my methods have finished executing, before I allow the refresh() method to re-assign t.
2. If this problem could cause my connection pool to open more connections than i have set the maximum to.
Thanks in advance for your time, I hope someone can help me!

Answer 1

public void refresh()
while(isRunning){
// wait for thread to finish
t = new Thread(this);
Now, the problem is that, currently, my program could
re-assign t, whilst the run() method wasn't finished
executing all it's methods. Well, you could change the above loop to while (t.isAlive())
some unexpected behaviour in my code.
1. How I can ensure that all my methods have finished
executing, before I allow the refresh() method to
re-assign t.You could use a java.util.concurrent.CountDownLatch so that your loop would wait on a latch (released at the end of the run() method) before re-assigning t. Or even just synchronize on some common object - let me know if you need an example.
2. If this problem could cause my connection pool to
open more connections than i have set the maximum
to.Well, it certainly is bad logic and so may well be the reason that you are opening more connections than you're closing