1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17import java.util.ArrayList;
18import java.util.List;
19import java.util.concurrent.atomic.AtomicInteger;
20import java.util.concurrent.CyclicBarrier;
21
22public class Main implements Runnable {
23
24    // Timeout in minutes. Make it larger than the run-test timeout to get a native thread dump by
25    // ART on timeout when running on the host.
26    private final static long TIMEOUT_VALUE = 7;
27
28    private final static long MAX_SIZE = 1000;  // Maximum size of array-list to allocate.
29
30    private final static int THREAD_COUNT = 16;
31
32    // Use a couple of different forms of synchronizing to test some of these...
33    private final static AtomicInteger counter = new AtomicInteger();
34    private final static Object gate = new Object();
35    private volatile static int waitCount = 0;
36
37    public static void main(String[] args) throws Exception {
38        Thread[] threads = new Thread[THREAD_COUNT];
39
40        // This barrier is used to synchronize the threads starting to allocate.
41        // Note: Even though a barrier is not allocation-free, this one is fine, as it will be used
42        //       before filling the heap.
43        CyclicBarrier startBarrier = new CyclicBarrier(threads.length);
44
45        for (int i = 0; i < threads.length; i++) {
46            threads[i] = new Thread(new Main(startBarrier));
47            threads[i].start();
48        }
49
50        // Wait for the threads to finish.
51        for (Thread thread : threads) {
52            thread.join();
53        }
54
55        // Allocate objects to definitely run GC before quitting.
56        allocateObjectsToRunGc();
57
58        new ArrayList<Object>(50);
59    }
60
61    private static void allocateObjectsToRunGc() {
62      ArrayList<Object> l = new ArrayList<Object>();
63      try {
64          for (int i = 0; i < 100000; i++) {
65              l.add(new ArrayList<Object>(i));
66          }
67      } catch (OutOfMemoryError oom) {
68      }
69    }
70
71    private Main(CyclicBarrier startBarrier) {
72        this.startBarrier = startBarrier;
73    }
74
75    private ArrayList<Object> store;
76    private CyclicBarrier startBarrier;
77
78    public void run() {
79        try {
80            work();
81        } catch (Throwable t) {
82            // Any exception or error getting here is bad.
83            try {
84                // May need allocations...
85                t.printStackTrace(System.out);
86            } catch (Throwable tInner) {
87            }
88            System.exit(1);
89        }
90    }
91
92    private void work() throws Exception {
93        // Any exceptions except an OOME in the allocation loop are bad and handed off to the
94        // caller which should abort the whole runtime.
95
96        ArrayList<Object> l = new ArrayList<Object>();
97        store = l;  // Keep it alive.
98
99        // Wait for the start signal.
100        startBarrier.await(TIMEOUT_VALUE, java.util.concurrent.TimeUnit.MINUTES);
101
102        // Allocate.
103        try {
104            for (int i = 0; i < MAX_SIZE; i++) {
105                l.add(new ArrayList<Object>(i));
106            }
107        } catch (OutOfMemoryError oome) {
108            // Fine, we're done.
109        }
110
111        // Atomically increment the counter and check whether we were last.
112        int number = counter.incrementAndGet();
113
114        if (number < THREAD_COUNT) {
115            // Not last.
116            synchronized (gate) {
117                // Increment the wait counter.
118                waitCount++;
119                gate.wait(TIMEOUT_VALUE * 1000 * 60);
120            }
121        } else {
122            // Last. Wait until waitCount == THREAD_COUNT - 1.
123            for (int loops = 0; ; loops++) {
124                synchronized (gate) {
125                    if (waitCount == THREAD_COUNT - 1) {
126                        // OK, everyone's waiting. Notify and break out.
127                        gate.notifyAll();
128                        break;
129                    } else if (loops > 40) {
130                        // 1s wait, too many tries.
131                        System.out.println("Waited too long for the last thread.");
132                        System.exit(1);
133                    }
134                }
135                // Wait a bit.
136                Thread.sleep(25);
137            }
138        }
139
140        store = null;  // Allow GC to reclaim it.
141    }
142}
143