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Java example source code file (IteratorMicroBenchmark.java)
This example Java source code file (IteratorMicroBenchmark.java) is included in the alvinalexander.com
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The IteratorMicroBenchmark.java Java example source code
/*
* Copyright (c) 2007, 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.
*/
/*
* This is not a regression test, but a micro-benchmark.
* Be patient; this runs for half an hour!
*
* I have run this as follows:
*
* for f in -client -server; do mergeBench dolphin . jr -dsa -da $f IteratorMicroBenchmark.java; done
*
*
* @author Martin Buchholz
*/
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.Pattern;
public class IteratorMicroBenchmark {
abstract static class Job {
private final String name;
public Job(String name) { this.name = name; }
public String name() { return name; }
public abstract void work() throws Throwable;
}
private static void collectAllGarbage() {
final java.util.concurrent.CountDownLatch drained
= new java.util.concurrent.CountDownLatch(1);
try {
System.gc(); // enqueue finalizable objects
new Object() { protected void finalize() {
drained.countDown(); }};
System.gc(); // enqueue detector
drained.await(); // wait for finalizer queue to drain
System.gc(); // cleanup finalized objects
} catch (InterruptedException e) { throw new Error(e); }
}
/**
* Runs each job for long enough that all the runtime compilers
* have had plenty of time to warm up, i.e. get around to
* compiling everything worth compiling.
* Returns array of average times per job per run.
*/
private static long[] time0(Job ... jobs) throws Throwable {
final long warmupNanos = 10L * 1000L * 1000L * 1000L;
long[] nanoss = new long[jobs.length];
for (int i = 0; i < jobs.length; i++) {
collectAllGarbage();
long t0 = System.nanoTime();
long t;
int j = 0;
do { jobs[i].work(); j++; }
while ((t = System.nanoTime() - t0) < warmupNanos);
nanoss[i] = t/j;
}
return nanoss;
}
private static void time(Job ... jobs) throws Throwable {
long[] warmup = time0(jobs); // Warm up run
long[] nanoss = time0(jobs); // Real timing run
long[] milliss = new long[jobs.length];
double[] ratios = new double[jobs.length];
final String nameHeader = "Method";
final String millisHeader = "Millis";
final String ratioHeader = "Ratio";
int nameWidth = nameHeader.length();
int millisWidth = millisHeader.length();
int ratioWidth = ratioHeader.length();
for (int i = 0; i < jobs.length; i++) {
nameWidth = Math.max(nameWidth, jobs[i].name().length());
milliss[i] = nanoss[i]/(1000L * 1000L);
millisWidth = Math.max(millisWidth,
String.format("%d", milliss[i]).length());
ratios[i] = (double) nanoss[i] / (double) nanoss[0];
ratioWidth = Math.max(ratioWidth,
String.format("%.3f", ratios[i]).length());
}
String format = String.format("%%-%ds %%%dd %%%d.3f%%n",
nameWidth, millisWidth, ratioWidth);
String headerFormat = String.format("%%-%ds %%%ds %%%ds%%n",
nameWidth, millisWidth, ratioWidth);
System.out.printf(headerFormat, "Method", "Millis", "Ratio");
// Print out absolute and relative times, calibrated against first job
for (int i = 0; i < jobs.length; i++)
System.out.printf(format, jobs[i].name(), milliss[i], ratios[i]);
}
private static String keywordValue(String[] args, String keyword) {
for (String arg : args)
if (arg.startsWith(keyword))
return arg.substring(keyword.length() + 1);
return null;
}
private static int intArg(String[] args, String keyword, int defaultValue) {
String val = keywordValue(args, keyword);
return val == null ? defaultValue : Integer.parseInt(val);
}
private static Pattern patternArg(String[] args, String keyword) {
String val = keywordValue(args, keyword);
return val == null ? null : Pattern.compile(val);
}
private static Job[] filter(Pattern filter, Job[] jobs) {
if (filter == null) return jobs;
Job[] newJobs = new Job[jobs.length];
int n = 0;
for (Job job : jobs)
if (filter.matcher(job.name()).find())
newJobs[n++] = job;
// Arrays.copyOf not available in JDK 5
Job[] ret = new Job[n];
System.arraycopy(newJobs, 0, ret, 0, n);
return ret;
}
private static void deoptimize(int sum) {
if (sum == 42)
System.out.println("the answer");
}
private static <T> List asSubList(List list) {
return list.subList(0, list.size());
}
private static <T> Iterable backwards(final List list) {
return new Iterable<T>() {
public Iterator<T> iterator() {
return new Iterator<T>() {
final ListIterator<T> it = list.listIterator(list.size());
public boolean hasNext() { return it.hasPrevious(); }
public T next() { return it.previous(); }
public void remove() { it.remove(); }};}};
}
/**
* Usage: [iterations=N] [size=N] [filter=REGEXP]
*/
public static void main(String[] args) throws Throwable {
final int iterations = intArg(args, "iterations", 100000);
final int size = intArg(args, "size", 1000);
final Pattern filter = patternArg(args, "filter");
final ConcurrentSkipListMap<Integer,Integer> m
= new ConcurrentSkipListMap<Integer,Integer>();
final Vector<Integer> v = new Vector(size);
final ArrayList<Integer> al = new ArrayList(size);
// Populate collections with random data
final Random rnd = new Random();
for (int i = 0; i < size; i++) {
m.put(rnd.nextInt(size), rnd.nextInt(size));
v.add(rnd.nextInt(size));
}
al.addAll(v);
// Also test "short" collections
final int shortSize = 5;
final Vector<Integer> sv = new Vector(v.subList(0, shortSize));
final ArrayList<Integer> sal = new ArrayList(sv);
// Checks for correctness *and* prevents loop optimizations
class Check {
private int sum;
public void sum(int sum) {
if (this.sum == 0)
this.sum = sum;
if (this.sum != sum)
throw new AssertionError("Sum mismatch");
}
}
final Check check = new Check();
final Check shortCheck = new Check();
Job[] jobs = {
// new Job("Vector iterate desugared") {
// public void work() throws Throwable {
// for (int i = 0; i < iterations; i++) {
// int sum = 0;
// for (Iterator<Integer> it = v.iterator(); it.hasNext();)
// sum += it.next();
// check.sum(sum);}}},
new Job("array loop") {
public void work() throws Throwable {
Integer[] a = al.toArray(new Integer[0]);
for (int i = 0; i < iterations; i++) {
int sum = 0;
int size = a.length;
for (int j = 0; j < size; ++j)
sum += a[j];
check.sum(sum);}}},
new Job("Vector get loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
int size = v.size();
for (int j = 0; j < size; ++j)
sum += v.get(j);
check.sum(sum);}}},
new Job("Vector iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : v)
sum += n;
check.sum(sum);}}},
new Job("Vector descending listIterator loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
ListIterator<Integer> it = v.listIterator(al.size());
while (it.hasPrevious())
sum += it.previous();
check.sum(sum);}}},
new Job("Vector Enumeration loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
Enumeration<Integer> it = v.elements();
while (it.hasMoreElements())
sum += it.nextElement();
check.sum(sum);}}},
new Job("Vector subList iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : asSubList(v))
sum += n;
check.sum(sum);}}},
new Job("Vector subList subList subList iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : asSubList(asSubList(asSubList(v))))
sum += n;
check.sum(sum);}}},
new Job("Vector backwards wrapper ListIterator for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : backwards(v))
sum += n;
check.sum(sum);}}},
new Job("Vector backwards wrapper subList ListIterator for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : backwards(asSubList(v)))
sum += n;
check.sum(sum);}}},
// new Job("Vector iterate for loop invokeinterface") {
// public void work() throws Throwable {
// final List<Integer> l = v;
// for (int i = 0; i < iterations; i++) {
// int sum = 0;
// for (Integer n : l)
// sum += n;
// check.sum(sum);}}},
// new Job("Vector subList iterate for loop invokeinterface") {
// public void work() throws Throwable {
// final List<Integer> l = v;
// for (int i = 0; i < iterations; i++) {
// int sum = 0;
// for (Integer n : asSubList(l))
// sum += n;
// check.sum(sum);}}},
new Job("Short Vector get loop") {
public void work() throws Throwable {
for (int i = 0; i < (iterations * size / shortSize); i++) {
int sum = 0;
int size = sv.size();
for (int j = 0; j < size; ++j)
sum += sv.get(j);
shortCheck.sum(sum);}}},
new Job("Short Vector iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < (iterations * size / shortSize); i++) {
int sum = 0;
for (Integer n : sv)
sum += n;
shortCheck.sum(sum);}}},
new Job("Short Vector sublist iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < (iterations * size / shortSize); i++) {
int sum = 0;
for (Integer n : asSubList(sv))
sum += n;
shortCheck.sum(sum);}}},
new Job("ArrayList get loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
int size = al.size();
for (int j = 0; j < size; ++j)
sum += al.get(j);
check.sum(sum);}}},
new Job("ArrayList iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : al)
sum += n;
check.sum(sum);}}},
new Job("ArrayList descending listIterator loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
ListIterator<Integer> it = al.listIterator(al.size());
while (it.hasPrevious())
sum += it.previous();
check.sum(sum);}}},
new Job("ArrayList listIterator loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
ListIterator<Integer> it = al.listIterator();
while (it.hasNext())
sum += it.next();
check.sum(sum);}}},
new Job("ArrayList subList get loop") {
public void work() throws Throwable {
List<Integer> sl = asSubList(al);
for (int i = 0; i < iterations; i++) {
int sum = 0;
int size = sl.size();
for (int j = 0; j < size; ++j)
sum += sl.get(j);
check.sum(sum);}}},
new Job("ArrayList subList iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : asSubList(al))
sum += n;
check.sum(sum);}}},
new Job("ArrayList subList subList subList iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : asSubList(asSubList(asSubList(al))))
sum += n;
check.sum(sum);}}},
new Job("ArrayList backwards wrapper ListIterator for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : backwards(al))
sum += n;
check.sum(sum);}}},
new Job("ArrayList backwards wrapper subList ListIterator for loop") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Integer n : backwards(asSubList(al)))
sum += n;
check.sum(sum);}}},
// new Job("ArrayList iterate desugared") {
// public void work() throws Throwable {
// for (int i = 0; i < iterations; i++) {
// int sum = 0;
// for (Iterator<Integer> it = al.iterator(); it.hasNext();)
// sum += it.next();
// check.sum(sum);}}},
new Job("Short ArrayList get loop") {
public void work() throws Throwable {
for (int i = 0; i < (iterations * size / shortSize); i++) {
int sum = 0;
int size = sal.size();
for (int j = 0; j < size; ++j)
sum += sal.get(j);
shortCheck.sum(sum);}}},
new Job("Short ArrayList iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < (iterations * size / shortSize); i++) {
int sum = 0;
for (Integer n : sal)
sum += n;
shortCheck.sum(sum);}}},
new Job("Short ArrayList sublist iterate for loop") {
public void work() throws Throwable {
for (int i = 0; i < (iterations * size / shortSize); i++) {
int sum = 0;
for (Integer n : asSubList(sal))
sum += n;
shortCheck.sum(sum);}}},
new Job("Vector ArrayList alternating iteration") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
Iterator<Integer> it1 = v.iterator();
Iterator<Integer> it2 = al.iterator();
while (it1.hasNext())
sum += it1.next() + it2.next();
check.sum(sum/2);}}},
new Job("Vector ArrayList alternating invokeVirtual iteration") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
List<Iterator its
= new ArrayList<Iterator(2);
its.add(v.iterator());
its.add(al.iterator());
for (int k = 0; its.get(k).hasNext(); k = (k == 0) ? 1 : 0)
sum += its.get(k).next();
check.sum(sum/2);}}},
new Job("ConcurrentSkipListMap entrySet iterate") {
public void work() throws Throwable {
for (int i = 0; i < iterations; i++) {
int sum = 0;
for (Map.Entry<Integer,Integer> e : m.entrySet())
sum += e.getKey();
deoptimize(sum);}}}
};
time(filter(filter, jobs));
}
}
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