content: /*
   * Copyright (C) 2016 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import java.lang.ref.WeakReference;
  
  public class Main {
      static final int numWeakReferences = 16 * 1024;
      static WeakReference[] weakReferences = new WeakReference[numWeakReferences];
      static volatile boolean done = false;
      static Object keepAlive;
  
      public static void main(String[] args) throws Exception {
          // Try to call Reference.get repeatedly while the GC is running.
          Thread gcThread = new GcThread();
          Thread[] readerThread = new ReaderThread[4];
          for (int i = 0; i < readerThread.length; ++i) {
              readerThread[i] = new ReaderThread();
          }
          gcThread.start();
          for (int i = 0; i < readerThread.length; ++i) {
              readerThread[i].start();
          }
          gcThread.join();
          for (int i = 0; i < readerThread.length; ++i) {
              readerThread[i].join();
          }
          System.out.println("PASS");
      }
  
      static class GcThread extends Thread {
          GcThread() {
              Object temp = new Object();
              for (int j = 0; j < weakReferences.length; ++j) {
                  weakReferences[j] = new WeakReference(temp);
              }
          }
          public void run() {
              for (int i = 0; i < 1000; ++i) {
                  Object o = new Object();
                  for (int j = 0; j < weakReferences.length; ++j) {
                      weakReferences[j] = new WeakReference(o);
                  }
              }
              done = true;
          }
      }
  
      static class ReaderThread extends Thread {
          public void run() {
              while (!done) {
                  for (int j = 0; j < weakReferences.length; ++j) {
                      keepAlive = weakReferences[j].get();
                  }
                  for (int j = 0; j < weakReferences.length; ++j) {
                      weakReferences[j].clear();
                  }
              }
          }
      }
  }
  