| 1 |
/* |
| 2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
| 3 |
* Expert Group and released to the public domain, as explained at |
| 4 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
| 5 |
*/ |
| 6 |
|
| 7 |
import java.util.concurrent.Phaser; |
| 8 |
import java.util.concurrent.ExecutorService; |
| 9 |
import java.util.concurrent.Executors; |
| 10 |
import java.util.concurrent.atomic.AtomicLong; |
| 11 |
//import java.util.concurrent.atomic.LongAdder; |
| 12 |
import jsr166e.LongAdder; |
| 13 |
|
| 14 |
public class LongAdderDemo { |
| 15 |
static final int INCS_PER_THREAD = 10000000; |
| 16 |
static final int NCPU = Runtime.getRuntime().availableProcessors(); |
| 17 |
static final ExecutorService pool = Executors.newCachedThreadPool(); |
| 18 |
|
| 19 |
public static void main(String[] args) { |
| 20 |
System.out.println("Warmup..."); |
| 21 |
int half = NCPU > 1 ? NCPU / 2 : 1; |
| 22 |
// casTest(half, 1000); |
| 23 |
adderTest(half, 1000); |
| 24 |
|
| 25 |
for (int reps = 0; reps < 2; ++reps) { |
| 26 |
System.out.println("Running..."); |
| 27 |
for (int i = 1; i <= NCPU * 2; i <<= 1) { |
| 28 |
// casTest(i, INCS_PER_THREAD); |
| 29 |
adderTest(i, INCS_PER_THREAD); |
| 30 |
} |
| 31 |
} |
| 32 |
pool.shutdown(); |
| 33 |
} |
| 34 |
|
| 35 |
static void casTest(int nthreads, int incs) { |
| 36 |
System.out.print("AtomicLong "); |
| 37 |
Phaser phaser = new Phaser(nthreads + 1); |
| 38 |
AtomicLong a = new AtomicLong(); |
| 39 |
for (int i = 0; i < nthreads; ++i) |
| 40 |
pool.execute(new CasTask(a, phaser, incs)); |
| 41 |
report(nthreads, incs, timeTasks(phaser), a.get()); |
| 42 |
} |
| 43 |
|
| 44 |
static void adderTest(int nthreads, int incs) { |
| 45 |
System.out.print("LongAdder "); |
| 46 |
Phaser phaser = new Phaser(nthreads + 1); |
| 47 |
LongAdder a = new LongAdder(); |
| 48 |
for (int i = 0; i < nthreads; ++i) |
| 49 |
pool.execute(new AdderTask(a, phaser, incs)); |
| 50 |
report(nthreads, incs, timeTasks(phaser), a.sum()); |
| 51 |
} |
| 52 |
|
| 53 |
static void report(int nthreads, int incs, long time, long sum) { |
| 54 |
long total = (long)nthreads * incs; |
| 55 |
if (sum != total) |
| 56 |
throw new Error(sum + " != " + total); |
| 57 |
double secs = (double)time / (1000L * 1000 * 1000); |
| 58 |
long rate = total * (1000L) / time; |
| 59 |
System.out.printf("threads:%3d Time: %7.3fsec Incs per microsec: %4d\n", |
| 60 |
nthreads, secs, rate); |
| 61 |
} |
| 62 |
|
| 63 |
static long timeTasks(Phaser phaser) { |
| 64 |
phaser.arriveAndAwaitAdvance(); |
| 65 |
long start = System.nanoTime(); |
| 66 |
phaser.arriveAndAwaitAdvance(); |
| 67 |
phaser.arriveAndAwaitAdvance(); |
| 68 |
return System.nanoTime() - start; |
| 69 |
} |
| 70 |
|
| 71 |
static final class AdderTask implements Runnable { |
| 72 |
final LongAdder adder; |
| 73 |
final Phaser phaser; |
| 74 |
final int incs; |
| 75 |
volatile long result; |
| 76 |
AdderTask(LongAdder adder, Phaser phaser, int incs) { |
| 77 |
this.adder = adder; |
| 78 |
this.phaser = phaser; |
| 79 |
this.incs = incs; |
| 80 |
} |
| 81 |
|
| 82 |
public void run() { |
| 83 |
phaser.arriveAndAwaitAdvance(); |
| 84 |
phaser.arriveAndAwaitAdvance(); |
| 85 |
LongAdder a = adder; |
| 86 |
for (int i = 0; i < incs; ++i) |
| 87 |
a.increment(); |
| 88 |
result = a.sum(); |
| 89 |
phaser.arrive(); |
| 90 |
} |
| 91 |
} |
| 92 |
|
| 93 |
static final class CasTask implements Runnable { |
| 94 |
final AtomicLong adder; |
| 95 |
final Phaser phaser; |
| 96 |
final int incs; |
| 97 |
volatile long result; |
| 98 |
CasTask(AtomicLong adder, Phaser phaser, int incs) { |
| 99 |
this.adder = adder; |
| 100 |
this.phaser = phaser; |
| 101 |
this.incs = incs; |
| 102 |
} |
| 103 |
|
| 104 |
public void run() { |
| 105 |
phaser.arriveAndAwaitAdvance(); |
| 106 |
phaser.arriveAndAwaitAdvance(); |
| 107 |
AtomicLong a = adder; |
| 108 |
for (int i = 0; i < incs; ++i) |
| 109 |
a.getAndIncrement(); |
| 110 |
result = a.get(); |
| 111 |
phaser.arrive(); |
| 112 |
} |
| 113 |
} |
| 114 |
|
| 115 |
} |
