/*
* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
/* Adapted from Dougs CVS test/jsr166e/LongAdderDemo.java
*
* The demo is a micro-benchmark to compare AtomicLong and LongAdder (run
* without any args), this restricted version simply exercises the basic
* functionality of LongAdder, suitable for automated testing (-shortrun).
*/
/*
* @test
* @bug 8005311
* @run main LongAdderDemo -shortrun
* @summary Basic test for LongAdder
*/
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Phaser;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.LongAdder;
public class LongAdderDemo {
static final int INCS_PER_THREAD = 10000000;
static final int NCPU = Runtime.getRuntime().availableProcessors();
static final int SHORT_RUN_MAX_THREADS = NCPU > 1 ? NCPU / 2 : 1;
static final int LONG_RUN_MAX_THREADS = NCPU * 2;
static final ExecutorService pool = Executors.newCachedThreadPool();
public static void main(String[] args) {
boolean shortRun = args.length > 0 && args[0].equals("-shortrun");
int maxNumThreads = shortRun ? SHORT_RUN_MAX_THREADS : LONG_RUN_MAX_THREADS;
System.out.println("Warmup...");
int half = NCPU > 1 ? NCPU / 2 : 1;
if (!shortRun)
casTest(half, 1000);
adderTest(half, 1000);
for (int reps = 0; reps < 2; ++reps) {
System.out.println("Running...");
for (int i = 1; i <= maxNumThreads; i <<= 1) {
if (!shortRun)
casTest(i, INCS_PER_THREAD);
adderTest(i, INCS_PER_THREAD);
}
}
pool.shutdown();
}
static void casTest(int nthreads, int incs) {
System.out.print("AtomicLong ");
Phaser phaser = new Phaser(nthreads + 1);
AtomicLong a = new AtomicLong();
for (int i = 0; i < nthreads; ++i)
pool.execute(new CasTask(a, phaser, incs));
report(nthreads, incs, timeTasks(phaser), a.get());
}
static void adderTest(int nthreads, int incs) {
System.out.print("LongAdder ");
Phaser phaser = new Phaser(nthreads + 1);
LongAdder a = new LongAdder();
for (int i = 0; i < nthreads; ++i)
pool.execute(new AdderTask(a, phaser, incs));
report(nthreads, incs, timeTasks(phaser), a.sum());
}
static void report(int nthreads, int incs, long time, long sum) {
long total = (long)nthreads * incs;
if (sum != total)
throw new Error(sum + " != " + total);
double secs = (double)time / (1000L * 1000 * 1000);
long rate = total * (1000L) / time;
System.out.printf("threads:%3d Time: %7.3fsec Incs per microsec: %4d\n",
nthreads, secs, rate);
}
static long timeTasks(Phaser phaser) {
phaser.arriveAndAwaitAdvance();
long start = System.nanoTime();
phaser.arriveAndAwaitAdvance();
phaser.arriveAndAwaitAdvance();
return System.nanoTime() - start;
}
static final class AdderTask implements Runnable {
final LongAdder adder;
final Phaser phaser;
final int incs;
volatile long result;
AdderTask(LongAdder adder, Phaser phaser, int incs) {
this.adder = adder;
this.phaser = phaser;
this.incs = incs;
}
public void run() {
phaser.arriveAndAwaitAdvance();
phaser.arriveAndAwaitAdvance();
LongAdder a = adder;
for (int i = 0; i < incs; ++i)
a.increment();
result = a.sum();
phaser.arrive();
}
}
static final class CasTask implements Runnable {
final AtomicLong adder;
final Phaser phaser;
final int incs;
volatile long result;
CasTask(AtomicLong adder, Phaser phaser, int incs) {
this.adder = adder;
this.phaser = phaser;
this.incs = incs;
}
public void run() {
phaser.arriveAndAwaitAdvance();
phaser.arriveAndAwaitAdvance();
AtomicLong a = adder;
for (int i = 0; i < incs; ++i)
a.getAndIncrement();
result = a.get();
phaser.arrive();
}
}
}