java並發編程（5）並發程式測試，java並發

java並發編程（5）並發程式測試，java並發
並發程式測試 一、正確性測試

　　如：對一個自訂緩衝的測試

//自訂的緩衝public class SemaphoreBoundedBuffer <E> {    private final Semaphore availableItems, availableSpaces;    private final E[] items;    private int putPosition = 0, takePosition = 0;    public SemaphoreBoundedBuffer(int capacity) {        if (capacity <= 0)            throw new IllegalArgumentException();        availableItems = new Semaphore(0);        availableSpaces = new Semaphore(capacity);        items = (E[]) new Object[capacity];    }    public boolean isEmpty() {        return availableItems.availablePermits() == 0;    }    public boolean isFull() {        return availableSpaces.availablePermits() == 0;    }    public void put(E x) throws InterruptedException {        availableSpaces.acquire();        doInsert(x);        availableItems.release();    }    public E take() throws InterruptedException {        availableItems.acquire();        E item = doExtract();        availableSpaces.release();        return item;    }    private synchronized void doInsert(E x) {        int i = putPosition;        items[i] = x;        putPosition = (++i == items.length) ? 0 : i;    }    private synchronized E doExtract() {        int i = takePosition;        E x = items[i];        items[i] = null;        takePosition = (++i == items.length) ? 0 : i;        return x;    }}//無需比較每次 生產者和消費者取出的值；只需要最終比較和即可public class PutTakeTest extends TestCase {    protected static final ExecutorService pool = Executors.newCachedThreadPool();    protected CyclicBarrier barrier;    protected final SemaphoreBoundedBuffer<Integer> bb;    protected final int nTrials, nPairs;    protected final AtomicInteger putSum = new AtomicInteger(0);    protected final AtomicInteger takeSum = new AtomicInteger(0);    public static void main(String[] args) throws Exception {        new PutTakeTest(10, 10, 100000).test(); // sample parameters        pool.shutdown();    }    public PutTakeTest(int capacity, int npairs, int ntrials) {        this.bb = new SemaphoreBoundedBuffer<Integer>(capacity);        this.nTrials = ntrials;        this.nPairs = npairs;        this.barrier = new CyclicBarrier(npairs * 2 + 1);   //初始化為 線程數量*2 + 1：生產者+消費者+主線程    }    void test() {        try {            for (int i = 0; i < nPairs; i++) {                pool.execute(new Producer());                pool.execute(new Consumer());            }            barrier.await(); // 等待所有線程初始化完成，完成後複位柵欄            barrier.await(); // 等待所有線程執行完成            assertEquals(putSum.get(), takeSum.get());      //執行比較，判斷執行緒安全性能        } catch (Exception e) {            throw new RuntimeException(e);        }    }    static int xorShift(int y) {    //產生隨機數        y ^= (y << 6);        y ^= (y >>> 21);        y ^= (y << 7);        return y;    }    class Producer implements Runnable {        public void run() {            try {                int seed = (this.hashCode() ^ (int) System.nanoTime());                int sum = 0;                barrier.await();                        //等待所有線程初始化完成                for (int i = nTrials; i > 0; --i) {                    bb.put(seed);                    sum += seed;                    seed = xorShift(seed);                }                putSum.getAndAdd(sum);                barrier.await();                        //等待所有線程執行完成            } catch (Exception e) {                throw new RuntimeException(e);            }        }    }    class Consumer implements Runnable {        public void run() {            try {                barrier.await();                        //等待所有線程初始化完成                int sum = 0;                for (int i = nTrials; i > 0; --i) {                    sum += bb.take();                }                takeSum.getAndAdd(sum);                barrier.await();                        //等待所有線程執行完成            } catch (Exception e) {                throw new RuntimeException(e);            }        }    }}