001    /*
002     * Copyright (C) 2008-2010 by Holger Arndt
003     *
004     * This file is part of the Universal Java Matrix Package (UJMP).
005     * See the NOTICE file distributed with this work for additional
006     * information regarding copyright ownership and licensing.
007     *
008     * UJMP is free software; you can redistribute it and/or modify
009     * it under the terms of the GNU Lesser General Public License as
010     * published by the Free Software Foundation; either version 2
011     * of the License, or (at your option) any later version.
012     *
013     * UJMP is distributed in the hope that it will be useful,
014     * but WITHOUT ANY WARRANTY; without even the implied warranty of
015     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
016     * GNU Lesser General Public License for more details.
017     *
018     * You should have received a copy of the GNU Lesser General Public
019     * License along with UJMP; if not, write to the
020     * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
021     * Boston, MA  02110-1301  USA
022     */
023    
024    package org.ujmp.core.util;
025    
026    public abstract class GCUtil {
027    
028            private static final Runtime runtime = Runtime.getRuntime();
029    
030            private static final long maxMemory = runtime.maxMemory();
031    
032            public static void gc() {
033                    try {
034                            long tmpIsFree = runtime.freeMemory();
035                            long tmpWasFree;
036    
037                            do {
038                                    tmpWasFree = tmpIsFree;
039                                    runtime.runFinalization();
040                                    runtime.gc();
041                                    Thread.sleep(10);
042                                    tmpIsFree = runtime.freeMemory();
043                            } while (tmpIsFree > tmpWasFree);
044    
045                            runtime.runFinalization();
046                    } catch (Exception e) {
047                            e.printStackTrace();
048                    }
049            }
050    
051            public static void purgeMemory() {
052                    try {
053                            long tmpIsFree = runtime.freeMemory();
054                            long tmpWasFree;
055                            byte[] a1 = null;
056                            byte[] a2 = null;
057                            byte[] a3 = null;
058                            byte[] a4 = null;
059                            byte[] a5 = null;
060                            byte[] a6 = null;
061                            byte[] a7 = null;
062                            byte[] a8 = null;
063                            byte[] a9 = null;
064                            try {
065                                    a1 = new byte[(int) (maxMemory * 0.1)];
066                                    a2 = new byte[(int) (maxMemory * 0.1)];
067                                    a3 = new byte[(int) (maxMemory * 0.1)];
068                                    a4 = new byte[(int) (maxMemory * 0.1)];
069                                    a5 = new byte[(int) (maxMemory * 0.1)];
070                                    a6 = new byte[(int) (maxMemory * 0.1)];
071                                    a7 = new byte[(int) (maxMemory * 0.1)];
072                                    a8 = new byte[(int) (maxMemory * 0.1)];
073                                    a9 = new byte[(int) (maxMemory * 0.1)];
074                            } catch (Throwable t1) {
075                            }
076                            runtime.runFinalization();
077                            runtime.gc();
078                            Thread.sleep(10);
079                            a1 = a1 == null ? null : null;
080                            a2 = a2 == null ? null : null;
081                            a3 = a3 == null ? null : null;
082                            a4 = a4 == null ? null : null;
083                            a5 = a5 == null ? null : null;
084                            a6 = a6 == null ? null : null;
085                            a7 = a7 == null ? null : null;
086                            a8 = a8 == null ? null : null;
087                            a9 = a9 == null ? null : null;
088                            do {
089                                    tmpWasFree = tmpIsFree;
090                                    runtime.runFinalization();
091                                    runtime.gc();
092                                    Thread.sleep(10);
093                                    tmpIsFree = runtime.freeMemory();
094                            } while (tmpIsFree > tmpWasFree);
095                            runtime.runFinalization();
096                    } catch (Exception e) {
097                            e.printStackTrace();
098                    }
099            }
100    }