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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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|
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import java.util.Arrays; |
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import java.util.Collections; |
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import java.util.Random; |
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import java.util.concurrent.BrokenBarrierException; |
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import java.util.concurrent.CyclicBarrier; |
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import java.util.concurrent.locks.ReentrantLock; |
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|
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public final class CancelledLockLoops { |
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static final Random rng = new Random(); |
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static boolean print = false; |
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static final int ITERS = 10000000; |
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static final long TIMEOUT = 100; |
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|
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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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|
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print = true; |
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|
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for (int i = 2; i <= maxThreads; i += (i+1) >>> 1) { |
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System.out.print("Threads: " + i); |
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try { |
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new ReentrantLockLoop(i).test(); |
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} |
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catch (BrokenBarrierException bb) { |
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// OK, ignore |
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} |
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} |
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} |
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|
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static final class ReentrantLockLoop implements Runnable { |
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private int v = rng.nextInt(); |
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private int 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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|
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final void test() throws Exception { |
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Thread[] threads = new Thread[nthreads]; |
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for (int i = 0; i < threads.length; ++i) |
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threads[i] = new Thread(this); |
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for (int i = 0; i < threads.length; ++i) |
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threads[i].start(); |
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Thread[] cancels = threads.clone(); |
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Collections.shuffle(Arrays.asList(cancels), rng); |
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barrier.await(); |
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Thread.sleep(TIMEOUT); |
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for (int i = 0; i < cancels.length-2; ++i) { |
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cancels[i].interrupt(); |
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// make sure all OK even when cancellations spaced out |
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if ( (i & 3) == 0) |
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Thread.sleep(1 + rng.nextInt(10)); |
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} |
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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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|
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int c; |
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lock.lock(); |
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try { |
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c = completed; |
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} |
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finally { |
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lock.unlock(); |
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} |
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if (c != 2) |
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throw new Error("Completed != 2"); |
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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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|
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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 = 0; |
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int n = ITERS; |
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boolean done = false; |
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do { |
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try { |
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lock.lockInterruptibly(); |
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} |
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catch (InterruptedException ie) { |
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break; |
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} |
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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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} while (n-- > 0); |
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if (n <= 0) { |
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lock.lock(); |
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try { |
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++completed; |
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} |
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finally { |
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lock.unlock(); |
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} |
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} |
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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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|
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} |
