The reserve heap memory is no longer used.

h2/src/main/org/h2/command/Command.java

@@ -16,7 +16,6 @@ import org.h2.message.Message;
 import org.h2.message.Trace;
 import org.h2.message.TraceObject;
 import org.h2.result.ResultInterface;
-import org.h2.util.MemoryUtils;
 import org.h2.util.ObjectArray;
 
 /**
@@ -186,7 +185,6 @@ public abstract class Command implements CommandInterface {
     public int executeUpdate() throws SQLException {
         long start = startTime = System.currentTimeMillis();
         Database database = session.getDatabase();
-        MemoryUtils.allocateReserveMemory();
         Object sync = database.isMultiThreaded() ? (Object) session : (Object) database;
         session.waitIfExclusiveModeEnabled();
         boolean callStop = true;

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

@@ -60,7 +60,6 @@ import org.h2.util.BitField;
 import org.h2.util.ByteUtils;
 import org.h2.util.ClassUtils;
 import org.h2.util.FileUtils;
-import org.h2.util.MemoryUtils;
 import org.h2.util.NetUtils;
 import org.h2.util.New;
 import org.h2.util.ObjectArray;
@@ -224,7 +223,6 @@ public class Database implements DataHandler {
 
     private void openDatabase(int traceLevelFile, int traceLevelSystemOut, boolean closeAtVmShutdown) throws SQLException {
         try {
-            MemoryUtils.allocateReserveMemory();
             open(traceLevelFile, traceLevelSystemOut);
             if (closeAtVmShutdown) {
                 try {
@@ -242,7 +240,6 @@ public class Database implements DataHandler {
             }
         } catch (Throwable e) {
             if (e instanceof OutOfMemoryError) {
-                MemoryUtils.freeReserveMemory();
                 e.fillInStackTrace();
             }
             if (traceSystem != null) {

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

@@ -16,7 +16,6 @@ import java.util.Properties;
 import java.util.Map.Entry;
 import org.h2.constant.ErrorCode;
 import org.h2.jdbc.JdbcSQLException;
-import org.h2.util.MemoryUtils;
 import org.h2.util.Resources;
 import org.h2.util.StringUtils;
 
@@ -299,10 +298,7 @@ public class Message {
      */
     public static SQLException convertThrowable(Throwable e) {
         if (e instanceof OutOfMemoryError) {
-            if (MemoryUtils.freeReserveMemory()) {
-                return getSQLException(ErrorCode.OUT_OF_MEMORY, e);
-            }
-            throw (OutOfMemoryError) e;
+            return getSQLException(ErrorCode.OUT_OF_MEMORY, e);
         } else if (e instanceof StackOverflowError || e instanceof LinkageError) {
             return getSQLException(ErrorCode.GENERAL_ERROR_1, e, e.toString());
         } else if (e instanceof Error) {

h2/src/main/org/h2/util/MemoryUtils.java

@@ -6,7 +6,6 @@
  */
 package org.h2.util;
 
-import org.h2.constant.SysProperties;
 
 /**
  * This is a utility class with functions to measure the free and used memory.
@@ -31,7 +30,6 @@ public class MemoryUtils {
     private static long lastGC;
     private static final int GC_DELAY = 50;
     private static final int MAX_GC = 8;
-    private static volatile byte[] reserveMemory;
 
     private MemoryUtils() {
         // utility class
@@ -78,29 +76,6 @@ public class MemoryUtils {
         }
     }
 
-    /**
-     * Allocate a little main memory that is freed up when if no memory is
-     * available, so that rolling back a large transaction is easier.
-     */
-    public static void allocateReserveMemory() {
-        if (reserveMemory == null) {
-            reserveMemory = new byte[SysProperties.RESERVE_MEMORY];
-        }
-    }
-
-    /**
-     * Free up the reserve memory.
-     *
-     * @return if memory could be freed up.
-     */
-    public static boolean freeReserveMemory() {
-        if (reserveMemory == null) {
-            return false;
-        }
-        reserveMemory = null;
-        return true;
-    }
-
     /**
      * Create an array of bytes with the given size. If this is not possible
      * because not enough memory is available, an OutOfMemoryError with the