Index: C:/home/holger/Projects/h2oWorkspace/commons-pool/src/java/org/apache/commons/pool/impl/GenericKeyedObjectPool.java
===================================================================
--- C:/home/holger/Projects/h2oWorkspace/commons-pool/src/java/org/apache/commons/pool/impl/GenericKeyedObjectPool.java	(revision 474163)
+++ C:/home/holger/Projects/h2oWorkspace/commons-pool/src/java/org/apache/commons/pool/impl/GenericKeyedObjectPool.java	(working copy)
@@ -1032,8 +1032,7 @@
         return pool != null ? pool.queue.size() : 0;
     }
 
-    public synchronized void returnObject(Object key, Object obj) throws Exception {
-
+    public void returnObject(Object key, Object obj) throws Exception {
         // if we need to validate this object, do so
         boolean success = true; // whether or not this object passed validation
         if(_testOnReturn && !_factory.validateObject(key, obj)) {
@@ -1061,23 +1060,26 @@
         }
 
         boolean shouldDestroy = false;
-        // grab the pool (list) of objects associated with the given key
-        ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
-        // if it doesn't exist, create it
-        if(null == pool) {
-            pool = new ObjectQueue();
-            _poolMap.put(key, pool);
+        
+        synchronized (this) {
+            // grab the pool (list) of objects associated with the given key
+            ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
+            // if it doesn't exist, create it
+            if(null == pool) {
+                pool = new ObjectQueue();
+                _poolMap.put(key, pool);
+            }
+            pool.decrementActiveCount();
+            // if there's no space in the pool, flag the object for destruction
+            // else if we passivated succesfully, return it to the pool
+            if(_maxIdle >= 0 && (pool.queue.size() >= _maxIdle)) {
+                shouldDestroy = true;
+            } else if(success) {
+                pool.queue.addLast(new ObjectTimestampPair(obj));
+                _totalIdle++;
+            }
+            notifyAll();
         }
-        pool.decrementActiveCount();
-        // if there's no space in the pool, flag the object for destruction
-        // else if we passivated succesfully, return it to the pool
-        if(_maxIdle >= 0 && (pool.queue.size() >= _maxIdle)) {
-            shouldDestroy = true;
-        } else if(success) {
-            pool.queue.addLast(new ObjectTimestampPair(obj));
-            _totalIdle++;
-        }
-        notifyAll();
 
         if(shouldDestroy) {
             try {
@@ -1088,19 +1090,21 @@
         }
     }
 
-    public synchronized void invalidateObject(Object key, Object obj) throws Exception {
+    public void invalidateObject(Object key, Object obj) throws Exception {
         try {
             _factory.destroyObject(key, obj);
         } catch (Exception e) {
             // swallowed
         } finally {
-            ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
-            if(null == pool) {
-                pool = new ObjectQueue();
-                _poolMap.put(key, pool);
+            synchronized (this) {
+                ObjectQueue pool = (ObjectQueue) (_poolMap.get(key));
+                if(null == pool) {
+                    pool = new ObjectQueue();
+                    _poolMap.put(key, pool);
+                }
+                pool.decrementActiveCount();
+                notifyAll(); // _totalActive has changed
             }
-            pool.decrementActiveCount();
-            notifyAll(); // _totalActive has changed
         }
     }