More bugs in the server-less multi-connection mode have been fixed.

h2/src/main/org/h2/constant/SysProperties.java

@@ -463,13 +463,13 @@ public class SysProperties {
     public static final boolean RECOMPILE_ALWAYS = getBooleanSetting("h2.recompileAlways", false);
 
     /**
-     * System property <code>h2.reconnectCheckDelay</code> (default: 250).<br />
+     * System property <code>h2.reconnectCheckDelay</code> (default: 100).<br />
      * Check the .lock.db file every this many milliseconds to detect that the
      * database was changed. The process writing to the database must first
      * notify a change in the .lock.db file, then wait twice this many
      * milliseconds before updating the database.
      */
-    public static final int RECONNECT_CHECK_DELAY = getIntSetting("h2.reconnectCheckDelay", 250);
+    public static final int RECONNECT_CHECK_DELAY = getIntSetting("h2.reconnectCheckDelay", 100);
 
     /**
      * System property <code>h2.redoBufferSize</code> (default: 262144).<br />

h2/src/main/org/h2/engine/Session.java

@@ -634,7 +634,6 @@ public class Session extends SessionWithState {
                 Message.throwInternalError();
             }
         }
-        database.afterWriting();
         if (locks.size() > 0) {
             synchronized (database) {
                 for (int i = 0; i < locks.size(); i++) {
@@ -1112,8 +1111,20 @@ public class Session extends SessionWithState {
         return modificationId;
     }
 
-    public boolean isReconnectNeeded() {
-        return database.isReconnectNeeded();
+    public boolean isReconnectNeeded(boolean write) {
+        while (true) {
+            boolean reconnect = database.isReconnectNeeded();
+            if (reconnect) {
+                return true;
+            }
+            if (write) {
+                if (database.beforeWriting()) {
+                    return false;
+                }
+            } else {
+                return false;
+            }
+        }
     }
 
     public SessionInterface reconnect() throws SQLException {

h2/src/main/org/h2/engine/SessionInterface.java

@@ -76,9 +76,10 @@ public interface SessionInterface {
     /**
      * Check if the database changed and therefore reconnecting is required.
      *
+     * @param write if the next operation may be writing
      * @return true if reconnecting is required
      */
-    boolean isReconnectNeeded();
+    boolean isReconnectNeeded(boolean write);
 
     /**
      * Close the connection and open a new connection.

h2/src/main/org/h2/engine/SessionRemote.java

@@ -652,7 +652,7 @@ public class SessionRemote extends SessionWithState implements SessionFactory, D
         return TempFileDeleter.getInstance();
     }
 
-    public boolean isReconnectNeeded() {
+    public boolean isReconnectNeeded(boolean write) {
         return false;
     }
 

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

@@ -400,7 +400,7 @@ public class JdbcConnection extends TraceObject implements Connection {
     public synchronized void commit() throws SQLException {
         try {
             debugCodeCall("commit");
-            checkClosed();
+            checkClosedForWrite();
             commit = prepareCommand("COMMIT", commit);
             commit.executeUpdate();
         } catch (Exception e) {
@@ -418,7 +418,7 @@ public class JdbcConnection extends TraceObject implements Connection {
     public synchronized void rollback() throws SQLException {
         try {
             debugCodeCall("rollback");
-            checkClosed();
+            checkClosedForWrite();
             rollbackInternal();
         } catch (Exception e) {
             throw logAndConvert(e);
@@ -641,6 +641,8 @@ public class JdbcConnection extends TraceObject implements Connection {
      */
     public void setQueryTimeout(int seconds) throws SQLException {
         try {
+            debugCodeCall("setQueryTimeout", seconds);
+            checkClosed();
             setQueryTimeout = prepareCommand("SET QUERY_TIMEOUT ?", setQueryTimeout);
             ((ParameterInterface) setQueryTimeout.getParameters().get(0)).setValue(ValueInt.get(seconds * 1000), false);
             setQueryTimeout.executeUpdate();
@@ -654,6 +656,8 @@ public class JdbcConnection extends TraceObject implements Connection {
      */
     public int getQueryTimeout() throws SQLException {
         try {
+            debugCodeCall("getQueryTimeout");
+            checkClosed();
             getQueryTimeout = prepareCommand("SELECT VALUE FROM INFORMATION_SCHEMA.SETTINGS WHERE NAME=?", getQueryTimeout);
             ((ParameterInterface) getQueryTimeout.getParameters().get(0)).setValue(ValueString.get("QUERY_TIMEOUT"), false);
             ResultInterface result = getQueryTimeout.executeQuery(0, false);
@@ -668,7 +672,6 @@ public class JdbcConnection extends TraceObject implements Connection {
         } catch (Exception e) {
             throw logAndConvert(e);
         }
-
     }
 
     /**
@@ -903,7 +906,7 @@ public class JdbcConnection extends TraceObject implements Connection {
         try {
             JdbcSavepoint sp = convertSavepoint(savepoint);
             debugCode("rollback(" + sp.getTraceObjectName() + ");");
-            checkClosed();
+            checkClosedForWrite();
             sp.rollback();
         } catch (Exception e) {
             throw logAndConvert(e);
@@ -1249,20 +1252,43 @@ public class JdbcConnection extends TraceObject implements Connection {
     }
 
     /**
-     * INTERNAL
      * Check if this connection is closed.
+     * The next operation is a read request.
      *
      * @return true if the session was re-connected
      * @throws SQLException if the connection or session is closed
      */
     protected boolean checkClosed() throws SQLException {
+        return checkClosed(false);
+    }
+
+    /**
+     * Check if this connection is closed.
+     * The next operation may be a write request.
+     *
+     * @return true if the session was re-connected
+     * @throws SQLException if the connection or session is closed
+     */
+    private boolean checkClosedForWrite() throws SQLException {
+        return checkClosed(true);
+    }
+
+    /**
+     * INTERNAL
+     * Check if this connection is closed.
+     *
+     * @param write if the next operation is possibly writing
+     * @return true if the session was re-connected
+     * @throws SQLException if the connection or session is closed
+     */
+    protected boolean checkClosed(boolean write) throws SQLException {
         if (session == null) {
             throw Message.getSQLException(ErrorCode.OBJECT_CLOSED);
         }
         if (session.isClosed()) {
             throw Message.getSQLException(ErrorCode.DATABASE_CALLED_AT_SHUTDOWN);
         }
-        if (session.isReconnectNeeded()) {
+        if (session.isReconnectNeeded(write)) {
             trace.debug("reconnect");
             session = session.reconnect();
             setTrace(session.getTrace());
@@ -1340,7 +1366,7 @@ public class JdbcConnection extends TraceObject implements Connection {
         try {
             int id = getNextId(TraceObject.CLOB);
             debugCodeAssign("Clob", TraceObject.CLOB, id, "createClob()");
-            checkClosed();
+            checkClosedForWrite();
             ValueLob v = ValueLob.createSmallLob(Value.CLOB, new byte[0]);
             return new JdbcClob(this, v, id);
         } catch (Exception e) {
@@ -1357,7 +1383,7 @@ public class JdbcConnection extends TraceObject implements Connection {
         try {
             int id = getNextId(TraceObject.BLOB);
             debugCodeAssign("Blob", TraceObject.BLOB, id, "createClob()");
-            checkClosed();
+            checkClosedForWrite();
             ValueLob v = ValueLob.createSmallLob(Value.BLOB, new byte[0]);
             return new JdbcBlob(this, v, id);
         } catch (Exception e) {
@@ -1375,7 +1401,7 @@ public class JdbcConnection extends TraceObject implements Connection {
         try {
             int id = getNextId(TraceObject.CLOB);
             debugCodeAssign("NClob", TraceObject.CLOB, id, "createNClob()");
-            checkClosed();
+            checkClosedForWrite();
             ValueLob v = ValueLob.createSmallLob(Value.CLOB, new byte[0]);
             return new JdbcClob(this, v, id);
         } catch (Exception e) {

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

@@ -124,7 +124,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
     public int executeUpdate() throws SQLException {
         try {
             debugCodeCall("executeUpdate");
-            checkClosed();
+            checkClosedForWrite();
             return executeUpdateInternal();
         } catch (Exception e) {
             throw logAndConvert(e);
@@ -159,7 +159,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCodeCall("execute");
             }
-            checkClosed();
+            checkClosedForWrite();
             closeOldResultSet();
             boolean returnsResultSet;
             synchronized (conn.getSession()) {
@@ -703,7 +703,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setBlob("+parameterIndex+", x);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v;
             if (x == null) {
                 v = ValueNull.INSTANCE;
@@ -728,7 +728,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setBlob("+parameterIndex+", x);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createBlob(x, -1);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -748,7 +748,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setClob("+parameterIndex+", x);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v;
             if (x == null) {
                 v = ValueNull.INSTANCE;
@@ -773,7 +773,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setClob("+parameterIndex+", x);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v;
             if (x == null) {
                 v = ValueNull.INSTANCE;
@@ -832,7 +832,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setBinaryStream("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createBlob(x, length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -888,7 +888,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setAsciiStream("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createClob(IOUtils.getAsciiReader(x), length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -943,7 +943,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setCharacterStream("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createClob(x, length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -1031,7 +1031,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
     public int[] executeBatch() throws SQLException {
         try {
             debugCodeCall("executeBatch");
-            checkClosed();
+            checkClosedForWrite();
             if (batchParameters == null) {
                 // TODO batch: check what other database do if no parameters are set
                 batchParameters = new ObjectArray();
@@ -1081,7 +1081,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
     public void addBatch() throws SQLException {
         try {
             debugCodeCall("addBatch");
-            checkClosed();
+            checkClosedForWrite();
             ObjectArray parameters = command.getParameters();
             Value[] set = new Value[parameters.size()];
             for (int i = 0; i < parameters.size(); i++) {
@@ -1271,7 +1271,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setNCharacterStream("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createClob(x, length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -1303,7 +1303,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setNClob("+parameterIndex+", x);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v;
             if (x == null) {
                 v = ValueNull.INSTANCE;
@@ -1329,7 +1329,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setNClob("+parameterIndex+", x);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createClob(x, -1);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -1349,7 +1349,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setClob("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createClob(x, length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -1369,7 +1369,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setBlob("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createBlob(x, length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -1389,7 +1389,7 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
             if (isDebugEnabled()) {
                 debugCode("setNClob("+parameterIndex+", x, "+length+"L);");
             }
-            checkClosed();
+            checkClosedForWrite();
             Value v = conn.createClob(x, length);
             setParameter(parameterIndex, v);
         } catch (Exception e) {
@@ -1413,10 +1413,20 @@ public class JdbcPreparedStatement extends JdbcStatement implements PreparedStat
         return getTraceObjectName() + ": " + command;
     }
 
-    boolean checkClosed() throws SQLException {
-        if (super.checkClosed()) {
+    protected boolean checkClosed(boolean write) throws SQLException {
+        if (super.checkClosed(write)) {
             // if the session was re-connected, re-prepare the statement
+            ObjectArray oldParams = command.getParameters();
             command = conn.prepareCommand(sql, fetchSize);
+            ObjectArray newParams = command.getParameters();
+            for (int i = 0; i < oldParams.size(); i++) {
+                ParameterInterface old = (ParameterInterface) oldParams.get(i);
+                Value value = old.getParamValue();
+                if (value != null) {
+                    ParameterInterface n = (ParameterInterface) newParams.get(i);
+                    n.setValue(value, false);
+                }
+            }
             return true;
         }
         return false;

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

@@ -105,7 +105,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     public int executeUpdate(String sql) throws SQLException {
         try {
             debugCodeCall("executeUpdate", sql);
-            checkClosed();
+            checkClosedForWrite();
             closeOldResultSet();
             if (escapeProcessing) {
                 sql = conn.translateSQL(sql);
@@ -144,7 +144,7 @@ public class JdbcStatement extends TraceObject implements Statement {
             if (isDebugEnabled()) {
                 debugCodeCall("execute", sql);
             }
-            checkClosed();
+            checkClosedForWrite();
             closeOldResultSet();
             if (escapeProcessing) {
                 sql = conn.translateSQL(sql);
@@ -610,7 +610,7 @@ public class JdbcStatement extends TraceObject implements Statement {
     public int[] executeBatch() throws SQLException {
         try {
             debugCodeCall("executeBatch");
-            checkClosed();
+            checkClosedForWrite();
             if (batchCommands == null) {
                 // TODO batch: check what other database do if no commands are set
                 batchCommands = new ObjectArray();
@@ -843,23 +843,48 @@ public class JdbcStatement extends TraceObject implements Statement {
 
     // =============================================================
 
+    /**
+     * Check if this connection is closed.
+     * The next operation is a read request.
+     *
+     * @return true if the session was re-connected
+     * @throws SQLException if the connection or session is closed
+     */
+    boolean checkClosed() throws SQLException {
+        return checkClosed(false);
+    }
+
+    /**
+     * Check if this connection is closed.
+     * The next operation may be a write request.
+     *
+     * @return true if the session was re-connected
+     * @throws SQLException if the connection or session is closed
+     */
+    boolean checkClosedForWrite() throws SQLException {
+        return checkClosed(true);
+    }
+
     /**
      * Check if the statement is closed.
      *
+     * @param write if the next operation is possibly writing
      * @return true if a reconnect was required
      * @throws SQLException if it is closed
      */
-    boolean checkClosed() throws SQLException {
+    protected boolean checkClosed(boolean write) throws SQLException {
         if (conn == null) {
             throw Message.getSQLException(ErrorCode.OBJECT_CLOSED);
         }
-        if (conn.checkClosed()) {
+        if (!conn.checkClosed(write)) {
+            return false;
+        }
+        do {
             session = conn.getSession();
             setTrace(session.getTrace());
+        } while (conn.checkClosed(write));
         return true;
     }
-        return false;
-    }
 
     /**
      * Close and old result set if there is still one open.

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

@@ -494,11 +494,11 @@ implements XAConnection, XAResource
             return isClosed || super.isClosed();
         }
 
-        protected synchronized boolean checkClosed() throws SQLException {
+        protected synchronized boolean checkClosed(boolean write) throws SQLException {
             if (isClosed) {
                 throw Message.getSQLException(ErrorCode.OBJECT_CLOSED);
             }
-            return super.checkClosed();
+            return super.checkClosed(write);
         }
 
     }

h2/src/main/org/h2/log/LogSystem.java

@@ -240,14 +240,16 @@ public class LogSystem {
     /**
      * Roll back any uncommitted transactions if required, and apply committed
      * changed to the data files.
+     *
+     * @return if recovery was needed
      */
-    public void recover() throws SQLException {
+    public boolean recover() throws SQLException {
         if (database == null) {
-            return;
+            return false;
         }
         synchronized (database) {
             if (closed) {
-                return;
+                return false;
             }
             undo = new ObjectArray();
             for (int i = 0; i < activeLogs.size(); i++) {
@@ -282,7 +284,7 @@ public class LogSystem {
             if (!readOnly && fileChanged && !containsInDoubtTransactions()) {
                 checkpoint();
             }
-            return;
+            return fileChanged;
         }
     }
 
@@ -514,7 +516,6 @@ public class LogSystem {
                 return;
             }
             database.checkWritingAllowed();
-            database.beforeWriting();
             if (!file.isDataFile()) {
                 storageId = -storageId;
             }
@@ -541,7 +542,6 @@ public class LogSystem {
                 return;
             }
             database.checkWritingAllowed();
-            database.beforeWriting();
             int storageId = record.getStorageId();
             if (!file.isDataFile()) {
                 storageId = -storageId;
@@ -569,6 +569,7 @@ public class LogSystem {
             if (closed || disabled) {
                 return;
             }
+            database.checkWritingAllowed();
             flushAndCloseUnused();
             currentLog = new LogFile(this, currentLog.getId() + 1, fileNamePrefix);
             activeLogs.add(currentLog);
@@ -668,7 +669,7 @@ public class LogSystem {
      *
      * @param readOnly the new value
      */
-    void setReadOnly(boolean readOnly) {
+    public void setReadOnly(boolean readOnly) {
         this.readOnly = readOnly;
     }
 
@@ -706,4 +707,13 @@ public class LogSystem {
         return accessMode;
     }
 
+    /**
+     * Get the write position.
+     *
+     * @return the write position
+     */
+    public String getWritePos() {
+        return currentLog.getId() + "/" + currentLog.getPos();
+    }
+
 }

h2/src/main/org/h2/store/FileLock.java

@@ -200,8 +200,10 @@ public class FileLock {
 
     /**
      * Save the lock file.
+     *
+     * @return the saved properties
      */
-    public void save() throws SQLException {
+    public Properties save() throws SQLException {
         try {
             OutputStream out = fs.openFileOutputStream(fileName, false);
             try {
@@ -213,6 +215,7 @@ public class FileLock {
             if (trace.isDebugEnabled()) {
                 trace.debug("save " + properties);
             }
+            return properties;
         } catch (IOException e) {
             throw getExceptionFatal("Could not save properties " + fileName, e);
         }
@@ -301,9 +304,21 @@ public class FileLock {
 
     private void lockSerialized() throws SQLException {
         method = SERIALIZED;
+        if (fs.createNewFile(fileName)) {
             properties = new SortedProperties();
             properties.setProperty("method", String.valueOf(method));
             setUniqueId();
+            save();
+        } else {
+            while (true) {
+                try {
+                    properties = load();
+                } catch (SQLException e) {
+                    // ignore
+                }
+                return;
+            }
+        }
     }
 
     private void lockFile() throws SQLException {

h2/src/main/org/h2/store/WriterThread.java

@@ -8,18 +8,13 @@ package org.h2.store;
 
 import java.lang.ref.WeakReference;
 import java.sql.SQLException;
-
 import org.h2.constant.SysProperties;
 import org.h2.engine.Constants;
 import org.h2.engine.Database;
-import org.h2.engine.DbObject;
-import org.h2.index.BtreeIndex;
 import org.h2.log.LogSystem;
 import org.h2.message.Trace;
 import org.h2.message.TraceSystem;
-import org.h2.table.Table;
 import org.h2.util.FileUtils;
-import org.h2.util.ObjectArray;
 
 /**
  * The writer thread is responsible to flush the transaction log file from time
@@ -91,35 +86,12 @@ public class WriterThread implements Runnable {
         return log;
     }
 
-    private void flushIndexes(Database database) {
+    private void flushIndexesIfRequired(Database database) {
         long time = System.currentTimeMillis();
         if (lastIndexFlush + Constants.FLUSH_INDEX_DELAY > time) {
             return;
         }
-        synchronized (database) {
-            ObjectArray array = database.getAllSchemaObjects(DbObject.INDEX);
-            for (int i = 0; i < array.size(); i++) {
-                DbObject obj = (DbObject) array.get(i);
-                if (obj instanceof BtreeIndex) {
-                    BtreeIndex idx = (BtreeIndex) obj;
-                    if (idx.getLastChange() == 0) {
-                        continue;
-                    }
-                    Table tab = idx.getTable();
-                    if (tab.isLockedExclusively()) {
-                        continue;
-                    }
-                    if (idx.getLastChange() + Constants.FLUSH_INDEX_DELAY > time) {
-                        continue;
-                    }
-                    try {
-                        idx.flush(database.getSystemSession());
-                    } catch (SQLException e) {
-                        database.getTrace(Trace.DATABASE).error("flush index " + idx.getName(), e);
-                    }
-                }
-            }
-        }
+        database.flushIndexes(time - Constants.FLUSH_INDEX_DELAY);
         lastIndexFlush = time;
     }
 
@@ -141,7 +113,7 @@ public class WriterThread implements Runnable {
                 break;
             }
             if (Constants.FLUSH_INDEX_DELAY != 0) {
-                flushIndexes(database);
+                flushIndexesIfRequired(database);
             }
 
             // checkpoint if required

h2/src/test/org/h2/test/unit/TestFileLockSerialized.java

@@ -34,6 +34,8 @@ public class TestFileLockSerialized extends TestBase {
 
     public void test() throws Exception {
         Class.forName("org.h2.Driver");
+        testThreeMostlyReaders(true);
+        testThreeMostlyReaders(false);
         testTwoReaders();
         testTwoWriters();
         testPendingWrite();
@@ -41,6 +43,55 @@ public class TestFileLockSerialized extends TestBase {
         testConcurrentReadWrite();
     }
 
+    private void testThreeMostlyReaders(final boolean write) throws Exception {
+        deleteDb("fileLockSerialized");
+        String url = "jdbc:h2:" + baseDir + "/fileLockSerialized;FILE_LOCK=SERIALIZED;OPEN_NEW=TRUE";
+        int len = 3;
+        final Exception[] ex = new Exception[1];
+        final Connection[] conn = new Connection[len];
+        final boolean[] stop = new boolean[1];
+        Thread[] threads = new Thread[len];
+        for (int i = 0; i < len; i++) {
+            final Connection c = DriverManager.getConnection(url);
+            conn[i] = c;
+            if (i == 0) {
+                conn[i].createStatement().execute("create table test(id int) as select 1");
+            }
+            Thread t = new Thread(new Runnable() {
+                public void run() {
+                    try {
+                        PreparedStatement p = c.prepareStatement("select * from test where id = ?");
+                        while (!stop[0]) {
+                            if (write) {
+                                if (Math.random() > 0.9) {
+                                    c.createStatement().execute("update test set id = id");
+                                }
+                            }
+                            p.setInt(1, 1);
+                            Thread.sleep(10);
+                            p.executeQuery();
+                            p.clearParameters();
+                        }
+                        c.close();
+                    } catch (Exception e) {
+                        ex[0] = e;
+                    }
+                }
+            });
+            t.start();
+            threads[i] = t;
+        }
+        Thread.sleep(1000);
+        stop[0] = true;
+        for (int i = 0; i < len; i++) {
+            threads[i].join();
+        }
+        if (ex[0] != null) {
+            throw ex[0];
+        }
+        DriverManager.getConnection(url).close();
+    }
+
     private void testTwoReaders() throws Exception {
         deleteDb("fileLockSerialized");
         String url = "jdbc:h2:" + baseDir + "/fileLockSerialized;FILE_LOCK=SERIALIZED;OPEN_NEW=TRUE";