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/* |
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* @test |
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* @summary checks to make sure a pipeline of exchangers passes data. |
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*/ |
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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. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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*/ |
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|
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import java.util.concurrent.*; |
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|
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public class ExchangeLoops { |
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static final ExecutorService pool = Executors.newCachedThreadPool(); |
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static boolean print = false; |
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|
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static class Int { |
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public int value; |
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Int(int i) { value = i; } |
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} |
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|
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|
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public static void main(String[] args) throws Exception { |
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int maxStages = 100; |
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int iters = 100000; |
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|
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if (args.length > 0) |
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maxStages = Integer.parseInt(args[0]); |
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|
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print = false; |
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System.out.println("Warmup..."); |
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oneRun(2, 100000); |
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print = true; |
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|
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for (int i = 2; i <= maxStages; i += (i+1) >>> 1) { |
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System.out.print("Threads: " + i + "\t: "); |
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oneRun(i, iters); |
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} |
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pool.shutdown(); |
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} |
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|
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static class Stage implements Runnable { |
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final int iters; |
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final Exchanger<Int> left; |
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final Exchanger<Int> right; |
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final CyclicBarrier barrier; |
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volatile int result; |
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Stage (Exchanger<Int> left, |
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Exchanger<Int> right, |
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CyclicBarrier b, int iters) { |
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this.left = left; |
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this.right = right; |
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barrier = b; |
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this.iters = iters; |
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} |
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|
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public void run() { |
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try { |
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barrier.await(); |
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Int item = new Int(hashCode()); |
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for (int i = 0; i < iters; ++i) { |
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if (left != null) { |
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item.value = LoopHelpers.compute1(item.value); |
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Int other = left.exchange(item); |
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if (other == item || other == null) |
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throw new Error("Failed Exchange"); |
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item = other; |
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|
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} |
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if (right != null) { |
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item.value = LoopHelpers.compute2(item.value); |
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Int other = right.exchange(item); |
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if (other == item || other == null) |
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throw new Error("Failed Exchange"); |
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item = other; |
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} |
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} |
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barrier.await(); |
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|
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} |
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catch (Exception ie) { |
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ie.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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static void oneRun(int nthreads, int iters) throws Exception { |
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LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); |
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CyclicBarrier barrier = new CyclicBarrier(nthreads + 1, timer); |
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Exchanger<Int> l = null; |
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Exchanger<Int> r = new Exchanger<Int>(); |
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for (int i = 0; i < nthreads; ++i) { |
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pool.execute(new Stage(l, r, barrier, iters)); |
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l = r; |
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r = (i+2 < nthreads) ? new Exchanger<Int>() : null; |
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} |
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barrier.await(); |
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barrier.await(); |
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long time = timer.getTime(); |
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if (print) |
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System.out.println(LoopHelpers.rightJustify(time / (iters * nthreads + iters * (nthreads-2))) + " ns per transfer"); |
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} |
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|
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} |
