I've been evaluating OSCache for use on a project, and have run
across some thread safety issues, that apparently cause
memory "leaks". Attached is a very simple example that illustrates
the problem. It creates multiple threads which each use a single
GeneralCacheAdministrator object to retrieve a cache value.

When run with -verbose:gc, you will notice that memory usage
increases unbounded. The only case where this does not occur is
when the program is run with only a single thread.

This can be reproduced with the latest available version, 1.7.5.
I have been testing this on a Solaris 9, multi-processor machine.

---- Test Case ----

import com.opensymphony.module.oscache.general.*;
import com.opensymphony.module.oscache.base.*;
import com.opensymphony.module.oscache.*;

public class OSGeneralTest implements Runnable {

static GeneralCacheAdministrator admin = null;

static {
        try {
            admin = GeneralCacheAdministrator.getInstance();
        }
        catch (Exception e) {
            e.printStackTrace();
            System.exit(1);
        }
    }

public void run() {
        for (;;) {
            doit();
        }
    }

public void doit() {
        
String myKey = "myKey";
        String myValue;
        int myRefreshPeriod = 60 /*seconds*/ * 1000 /*millis*/;
        
try {
            // Get from the cache
            myValue = (String) admin.getFromCache(myKey, myRefreshPeriod);
        }
        catch (NeedsRefreshException nre) {
            try {
                // Get the value (probably by calling an EJB)
                myValue = "This is the content retrieved.";
                // Store in the cache
                admin.putInCache(myKey, myValue);
                System.err.println("Put in cache");
            }
            catch (Exception ex) {
                // We have the current content if we want fail-over.
                myValue = (String) nre.getCacheContent();
            }
        }
    }

public static void main(String[] args) {
        if (args.length <= 0) {
            System.err.println("usage: java OSGeneralTest <threads>");
            System.exit(1);
        }

for (int idx = 0; idx < Integer.parseInt(args[0]); idx++) {
            OSGeneralTest runner = new OSGeneralTest();
            Thread thread = new Thread(runner);
            thread.start();
        }
    }
}