Index: src/main/java/org/apache/jackrabbit/core/data/GarbageCollector.java
===================================================================
--- src/main/java/org/apache/jackrabbit/core/data/GarbageCollector.java	(revision 777387)
+++ src/main/java/org/apache/jackrabbit/core/data/GarbageCollector.java	(working copy)
@@ -34,6 +34,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import javax.jcr.Item;
 import javax.jcr.Node;
@@ -84,9 +85,12 @@
     private final IterablePersistenceManager[] pmList;
 
     private final Session[] sessionList;
+    private final SessionListener sessionListener;
 
     private boolean persistenceManagerScan;
 
+    private AtomicBoolean closed = new AtomicBoolean();
+
     // TODO It should be possible to stop and restart a garbage collection scan.
 
     /**
@@ -96,23 +100,42 @@
      *
      * @param list the persistence managers
      */
-    public GarbageCollector(final SessionImpl session, IterablePersistenceManager[] list, final Session[] sessionList) {
+    public GarbageCollector(SessionImpl session, IterablePersistenceManager[] list, Session[] sessionList) {
         RepositoryImpl rep = (RepositoryImpl) session.getRepository();
         store = rep.getDataStore();
         this.pmList = list;
         this.persistenceManagerScan = list != null;
         this.sessionList = sessionList;
-        
-        // log out each session as soon as the main session logs out
-        session.addListener(new SessionListener() {
+
+        // Auto-close if the main session logs out
+        this.sessionListener = new SessionListener() {
             public void loggedOut(SessionImpl session) {
-                for (Session s: sessionList) {
-                    s.logout();
-                }
             }
             public void loggingOut(SessionImpl session) {
+            	close();
+            }
+        };
+        session.addListener(this.sessionListener);
+    }
+
+    /**
+     * Cleanup resources used internally by this instance 
+     */
+    public void close() {
+    	if (!closed.getAndSet(true)) {
+            for (Session s: sessionList) {
+                s.logout();
             }
-        });
+    	}
+    }
+
+    /**
+     * Auto-close in case the application didn't call it explicitly 
+     */
+    @Override
+    protected void finalize() throws Throwable {
+    	close();
+    	super.finalize();
     }
 
     /**