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dl |
1.1 |
/* |
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* @test %I% %E% |
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* @bug 4486658 |
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* @compile -source 1.5 TimeoutLockLoops.java |
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* @run main TimeoutLockLoops |
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* @summary Checks for responsiveness of locks to timeouts. |
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* Runs under the assumption that ITERS computations require more than |
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* TIMEOUT msecs to complete, which seems to be a safe assumption for |
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* another decade. |
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*/ |
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import java.util.concurrent.*; |
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import java.util.concurrent.locks.*; |
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import java.util.*; |
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public final class TimeoutLockLoops { |
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static final ExecutorService pool = Executors.newCachedThreadPool(); |
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static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom(); |
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static boolean print = false; |
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static final int ITERS = Integer.MAX_VALUE; |
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static final long TIMEOUT = 100; |
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public static void main(String[] args) throws Exception { |
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int maxThreads = 100; |
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if (args.length > 0) |
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maxThreads = Integer.parseInt(args[0]); |
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print = true; |
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for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) { |
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System.out.print("Threads: " + i); |
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new ReentrantLockLoop(i).test(); |
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// Thread.sleep(10); |
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} |
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pool.shutdown(); |
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} |
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static final class ReentrantLockLoop implements Runnable { |
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private int v = rng.next(); |
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private volatile boolean completed; |
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private volatile int result = 17; |
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private final ReentrantLock lock = new ReentrantLock(); |
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private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); |
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private final CyclicBarrier barrier; |
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private final int nthreads; |
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ReentrantLockLoop(int nthreads) { |
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this.nthreads = nthreads; |
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barrier = new CyclicBarrier(nthreads+1, timer); |
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} |
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final void test() throws Exception { |
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for (int i = 0; i < nthreads; ++i) { |
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lock.lock(); |
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pool.execute(this); |
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lock.unlock(); |
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} |
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barrier.await(); |
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Thread.sleep(TIMEOUT); |
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while (!lock.tryLock()); // Jam lock |
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// lock.lock(); |
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barrier.await(); |
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if (print) { |
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long time = timer.getTime(); |
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double secs = (double)(time) / 1000000000.0; |
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System.out.println("\t " + secs + "s run time"); |
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} |
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if (completed) |
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throw new Error("Some thread completed instead of timing out"); |
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int r = result; |
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if (r == 0) // avoid overoptimization |
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System.out.println("useless result: " + r); |
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} |
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public final void run() { |
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try { |
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barrier.await(); |
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int sum = v; |
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int x = 17; |
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int n = ITERS; |
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final ReentrantLock lock = this.lock; |
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for (;;) { |
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if (x != 0) { |
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if (n-- <= 0) |
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break; |
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} |
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if (!lock.tryLock(TIMEOUT, TimeUnit.MILLISECONDS)) |
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break; |
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try { |
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v = x = LoopHelpers.compute1(v); |
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} |
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finally { |
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lock.unlock(); |
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} |
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sum += LoopHelpers.compute2(x); |
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} |
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if (n <= 0) |
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completed = true; |
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barrier.await(); |
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result += sum; |
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} |
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catch (Exception ex) { |
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ex.printStackTrace(); |
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return; |
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} |
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} |
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} |
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} |
