/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import java.lang.reflect.Field;
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import java.util.Map;
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public class Main implements Runnable {
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static final int numberOfThreads = 5;
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static final int totalOperations = 1000;
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public static void main(String[] args) throws Exception {
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final Thread[] threads = new Thread[numberOfThreads];
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for (int t = 0; t < threads.length; t++) {
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threads[t] = new Thread(new Main());
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threads[t].start();
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}
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for (Thread t : threads) {
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t.join();
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}
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// Do this test after the other part to leave some time for the heap task daemon to start
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// up.
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test_getStackTraces();
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System.out.println("Finishing");
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}
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static Thread getHeapTaskDaemon() throws Exception {
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Field f = ThreadGroup.class.getDeclaredField("systemThreadGroup");
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f.setAccessible(true);
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ThreadGroup systemThreadGroup = (ThreadGroup) f.get(null);
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while (true) {
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int activeCount = systemThreadGroup.activeCount();
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Thread[] array = new Thread[activeCount];
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systemThreadGroup.enumerate(array);
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for (Thread thread : array) {
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if (thread.getName().equals("HeapTaskDaemon") &&
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thread.getState() != Thread.State.NEW) {
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return thread;
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}
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}
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// Yield to eventually get the daemon started.
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Thread.sleep(10);
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}
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}
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static void test_getStackTraces() throws Exception {
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Thread heapDaemon = getHeapTaskDaemon();
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// Force a GC to ensure the daemon truly started.
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Runtime.getRuntime().gc();
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// Check all the current threads for positive IDs.
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Map<Thread, StackTraceElement[]> map = Thread.getAllStackTraces();
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for (Map.Entry<Thread, StackTraceElement[]> pair : map.entrySet()) {
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Thread thread = pair.getKey();
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// Expect empty stack trace since we do not support suspending the GC thread for
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// obtaining stack traces. See b/28261069.
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if (thread == heapDaemon) {
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System.out.println(thread.getName() + " depth " + pair.getValue().length);
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}
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}
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}
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public void test_getId() {
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if (Thread.currentThread().getId() <= 0) {
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System.out.println("current thread's ID is not positive");
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}
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// Check all the current threads for positive IDs.
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Map<Thread, StackTraceElement[]> stMap = Thread.getAllStackTraces();
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for (Thread thread : stMap.keySet()) {
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if (thread.getId() <= 0) {
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System.out.println("thread's ID is not positive: " + thread.getName());
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}
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}
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}
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public void run() {
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for (int i = 0; i < totalOperations; ++i) {
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test_getId();
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}
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}
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}
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