1 /*

     2  * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 import sun.hotspot.WhiteBox;

    26 

    27 public class HelloStringGC {

    28     public static String[] array01 = new String[1000];

    29     public static String[] array02 = new String[1000];

    30 

    31     public static void main(String args[]) throws RuntimeException {

    32         String testString1 = "shared_test_string_unique_14325";

    33         String testString2 = "test123";

    34 

    35         WhiteBox wb = WhiteBox.getWhiteBox();

    36         if (!wb.isShared(testString1) && !wb.areSharedStringsIgnored()) {

    37             throw new RuntimeException("testString1 is not shared");

    38         }

    39 

    40         for (int i=0; i<5; i++) {

    41             allocSomeStrings(testString1, testString2);

    42             array01 = null;

    43             array02 = null;

    44             System.gc();

    45             sleep(300);

    46             array01 = new String[1000];

    47             array02 = new String[1000];

    48         }

    49 

    50         wb.fullGC();

    51 

    52         System.out.println("HelloStringGC: PASS");

    53     }

    54 

    55     private static void allocSomeStrings(String s1, String s2) {

    56         for (int i = 0; i < 1000; i ++) {

    57             array01[i] = new String(s1);

    58             array02[i] = new String(s2);

    59         }

    60     }

    61 

    62     private static void sleep(int ms) {

    63         try {

    64             Thread.sleep(ms);

    65         } catch (InterruptedException e) {

    66         }

    67     }

    68 

    69 }