1 /*
   2  * Copyright (c) 2018, Google 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 package MyPackage;
  25 
  26 /**
  27  * @test
  28  * @build Frame HeapMonitor
  29  * @summary Verifies the JVMTI Heap Monitor Thread sanity
  30  * @compile HeapMonitorThreadTest.java
  31  * @run main/othervm/native -agentlib:HeapMonitor MyPackage.HeapMonitorThreadTest
  32  */
  33 
  34 import java.util.ArrayList;
  35 import java.util.List;
  36 
  37 public class HeapMonitorThreadTest {
  38   private native static boolean checkSamples(int numThreads);
  39 
  40   public static void main(String[] args) {
  41     final int numThreads = 24;
  42     ArrayList<Thread> list = new ArrayList<>();
  43 
  44     // Remember a lot of garbage to have space for all thread samples.
  45     HeapMonitor.enableSamplingEvents();
  46 
  47     for (int i = 0 ; i < numThreads; i++) {
  48       Thread thread = new Thread(new Allocator(i), "Allocator" + i);
  49       thread.start();
  50       list.add(thread);
  51     }
  52 
  53     for (Thread elem : list) {
  54       try {
  55         elem.join();
  56       } catch(InterruptedException e) {
  57         throw new RuntimeException("Thread got interrupted...");
  58       }
  59     }
  60 
  61     if (!checkSamples(numThreads)) {
  62       throw new RuntimeException("Problem with checkSamples...");
  63     }
  64   }
  65 }
  66 
  67 class Allocator implements Runnable {
  68   private int depth;
  69   private List<int[]> currentList;
  70 
  71   public Allocator(int depth) {
  72     this.depth = depth;
  73   }
  74 
  75   private void helper() {
  76     List<int[]> newList = new ArrayList<>();
  77     // Let us assume that the array is 24 bytes of memory, by default we sample at 512k, keep in
  78     // memory at least 2MB without counting the link-list itself, which adds to this.
  79     int iterations = (1 << 21) / 24;
  80     for (int i = 0; i < iterations; i++) {
  81       int newTmp[] = new int[1];
  82       // Force it to be kept.
  83       newList.add(newTmp);
  84     }
  85 
  86     // Replace old list with new list, which provokes two things:
  87     //  Old list will get GC'd at some point.
  88     //  New list forces that this thread has some allocations still sampled.
  89     currentList = newList;
  90   }
  91 
  92   private void recursiveWrapper(int depth) {
  93     if (depth > 0) {
  94       recursiveWrapper(depth - 1);
  95     }
  96     helper();
  97   }
  98 
  99   public void run() {
 100     for (int j = 0; j < 50; j++) {
 101       recursiveWrapper(depth);
 102     }
 103   }
 104 }