1 /*
   2  * Copyright (c) 2016, 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 
  26 
  27 /*
  28  * @test
  29  * @bug 8159244
  30  * @summary Verifies that no partially initialized String object escapes from
  31  *          C2's String concat optimization in a highly concurrent setting.
  32  *          This test triggers the bug in about 1 out of 10 runs.
  33  * @requires vm.gc == "Parallel" | vm.gc == "null"
  34  *
  35  * @compile -XDstringConcat=inline TestStringObjectInitialization.java
  36  * @run main/othervm/timeout=300 -XX:+IgnoreUnrecognizedVMOptions -XX:-UseCompressedOops -XX:-CompactStrings
  37  *                               -XX:-UseG1GC -XX:+UseParallelGC
  38  *                               compiler.stringopts.TestStringObjectInitialization
  39  */
  40 
  41 package compiler.stringopts;
  42 
  43 import java.util.Arrays;
  44 
  45 public class TestStringObjectInitialization {
  46 
  47     String myString;
  48 
  49     public static void main(String[] args) throws Exception {
  50         TestStringObjectInitialization t = new TestStringObjectInitialization();
  51         // Create some threads that concurrently update 'myString'
  52         for (int i = 0; i < 100; ++i) {
  53             (new Thread(new Runner(t))).start();
  54         }
  55         Thread last = new Thread(new Runner(t));
  56         last.start();
  57         last.join();
  58     }
  59 
  60     private void add(String message) {
  61         // String escapes to other threads here
  62         myString += message;
  63     }
  64 
  65     public void run(String s, String[] sArray) {
  66         // Trigger C2's string concatenation optimization
  67         add(s + Arrays.toString(sArray) + " const ");
  68     }
  69 
  70     private static class Runner implements Runnable {
  71         private TestStringObjectInitialization test;
  72 
  73         public Runner(TestStringObjectInitialization t) {
  74             test = t;
  75         }
  76 
  77         public void run() {
  78             String[] array = {"a", "b", "c"};
  79             for (int i = 0; i < 10000; ++i) {
  80                 test.run("a", array);
  81             }
  82         }
  83     }
  84 }
  85