If a pooled connection was not closed but garbage collected, a NullPointerException could occur.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,8 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>Fulltext search: a NullPointerException was thrown when updating a value that
+<ul><li>If a pooled connection was not closed but garbage collected, a NullPointerException could occur.
+</li><li>Fulltext search: a NullPointerException was thrown when updating a value that
     was NULL previously.
 </li><li>The Recover tool did not work with .data.db files of the wrong size.
 </li><li>Triggers: if there was an exception when initializing a trigger, this exception could be hidden,

h2/src/main/org/h2/jdbc/JdbcConnection.java

@@ -59,6 +59,12 @@ import java.sql.SQLClientInfoException;
  * </p>
  */
 public class JdbcConnection extends TraceObject implements Connection {
+
+    /**
+     * The stack trace of when the connection was created.
+     */
+    protected Exception openStackTrace;
+
     private String url;
     private String user;
 
@@ -71,7 +77,6 @@ public class JdbcConnection extends TraceObject implements Connection {
     private CommandInterface getReadOnly, getGeneratedKeys;
     private CommandInterface setLockMode, getLockMode;
     private CommandInterface setQueryTimeout, getQueryTimeout;
-    private Exception openStackTrace;
 
     //## Java 1.4 begin ##
     private int savepointId;
@@ -285,6 +290,7 @@ public class JdbcConnection extends TraceObject implements Connection {
     public synchronized void close() throws SQLException {
         try {
             debugCodeCall("close");
+            openStackTrace = null;
             if (executingStatement != null) {
                 executingStatement.cancel();
             }
@@ -1320,7 +1326,7 @@ public class JdbcConnection extends TraceObject implements Connection {
         if (isInternal) {
             return;
         }
-        if (session != null) {
+        if (session != null && openStackTrace != null) {
             trace.error("Connection not closed", openStackTrace);
             try {
                 close();

h2/src/main/org/h2/jdbcx/JdbcXAConnection.java

@@ -20,6 +20,7 @@ import javax.transaction.xa.XAException;
 import javax.transaction.xa.XAResource;
 import javax.transaction.xa.Xid;
 import org.h2.constant.ErrorCode;
+import org.h2.constant.SysProperties;
 import org.h2.jdbc.JdbcConnection;
 import org.h2.util.ByteUtils;
 import org.h2.util.JdbcUtils;
@@ -28,6 +29,7 @@ import org.h2.util.StringUtils;
 //## Java 1.4 end ##
 
 import org.h2.message.Message;
+import org.h2.message.Trace;
 import org.h2.message.TraceObject;
 
 /*## Java 1.6 begin ##
@@ -94,6 +96,7 @@ implements XAConnection, XAResource
     public void close() throws SQLException {
         debugCodeCall("close");
         if (handleConn != null) {
+            listeners.clear();
             handleConn.close();
         }
         if (physicalConn != null) {
@@ -479,6 +482,7 @@ implements XAConnection, XAResource
 
         public PooledJdbcConnection(JdbcConnection conn) {
             super(conn);
+            openStackTrace = new Exception("Stack Trace");
         }
 
         public synchronized void close() throws SQLException {
@@ -501,6 +505,21 @@ implements XAConnection, XAResource
             super.checkClosed(write);
         }
 
+        protected void finalize() {
+            if (!SysProperties.runFinalize) {
+                return;
+            }
+            Trace trace = getTrace();
+            try {
+                if (!isClosed()) {
+                    trace.error("Pooled connection not closed", openStackTrace);
+                    JdbcXAConnection.this.close();
+                }
+            } catch (SQLException e) {
+                trace.debug("finalize", e);
+            }
+        }
+
     }
 
 }

h2/src/main/org/h2/message/TraceObject.java

@@ -131,7 +131,7 @@ public class TraceObject {
     }
 
     /**
-     * Update the trace.
+     * Update the trace object.
      *
      * @param trace the trace object
      */
@@ -139,6 +139,15 @@ public class TraceObject {
         this.trace = trace;
     }
 
+    /**
+     * Get the trace object.
+     *
+     * @return the trace object
+     */
+    protected Trace getTrace() {
+        return trace;
+    }
+
     /**
      * INTERNAL
      */