7026304: Fork-Join sample
Summary: Implement a merge-sort sample using Fork-Join
Reviewed-by: hosterda, chegar, dholmes
--- a/jdk/make/mksample/Makefile Tue Apr 12 09:04:57 2011 +0200
+++ b/jdk/make/mksample/Makefile Tue Apr 12 13:14:05 2011 +0200
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2004, 2011, 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
@@ -38,7 +38,7 @@
endif
SUBDIRS =
-SUBDIRS_misc = nio scripting nbproject
+SUBDIRS_misc = nio scripting nbproject forkjoin
SUBDIRS_enterprise = $(WEBSERVICES_SUBDIR)
SUBDIRS_management = jmx
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/make/mksample/forkjoin/Makefile Tue Apr 12 13:14:05 2011 +0200
@@ -0,0 +1,41 @@
+#
+# Copyright (c) 2011, 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. Oracle designates this
+# particular file as subject to the "Classpath" exception as provided
+# by Oracle in the LICENSE file that accompanied this code.
+#
+# 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.
+#
+
+#
+# Makefile for building all the samples under the forkjoin subdirectory.
+#
+
+BUILDDIR = ../..
+PRODUCT = java
+include $(BUILDDIR)/common/Defs.gmk
+
+SUBDIRS = mergesort
+include $(BUILDDIR)/common/Subdirs.gmk
+
+all build clean clobber::
+ $(SUBDIRS-loop)
+
+clobber clean ::
+ $(RM) -r $(SAMPLEDIR)/forkjoin
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/make/mksample/forkjoin/mergesort/Makefile Tue Apr 12 13:14:05 2011 +0200
@@ -0,0 +1,51 @@
+#
+# Copyright (c) 2011, 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. Oracle designates this
+# particular file as subject to the "Classpath" exception as provided
+# by Oracle in the LICENSE file that accompanied this code.
+#
+# 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.
+#
+
+#
+# Makefile for the forkjoin/mergesort sample code
+#
+
+BUILDDIR = ../../..
+
+PRODUCT = java
+
+include $(BUILDDIR)/common/Defs.gmk
+
+SAMPLE_SRC_DIR = $(SHARE_SRC)/sample/forkjoin/mergesort
+SAMPLE_DST_DIR = $(SAMPLEDIR)/forkjoin/mergesort
+
+SAMPLE_FILES = \
+ $(SAMPLE_DST_DIR)/MergeDemo.java \
+ $(SAMPLE_DST_DIR)/MergeSort.java
+
+all build: $(SAMPLE_FILES)
+
+$(SAMPLE_DST_DIR)/%: $(SAMPLE_SRC_DIR)/%
+ $(install-file)
+
+clean clobber:
+ $(RM) -r $(SAMPLE_DST_DIR)
+
+.PHONY: all build clean clobber
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/sample/forkjoin/mergesort/MergeDemo.java Tue Apr 12 13:14:05 2011 +0200
@@ -0,0 +1,287 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of Oracle nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import java.util.Arrays;
+import java.util.Random;
+
+import static java.lang.Integer.parseInt;
+
+/**
+ * MergeExample is a class that runs a demo benchmark of the {@code ForkJoin} framework
+ * by benchmarking a {@link MergeSort} algorithm that is implemented using
+ * {@link java.util.concurrent.RecursiveAction}.
+ * The {@code ForkJoin} framework is setup with different parallelism levels
+ * and the sort is executed with arrays of different sizes to see the
+ * trade offs by using multiple threads for different sizes of the array.
+ */
+public class MergeDemo {
+ // Use a fixed seed to always get the same random values back
+ private final Random random = new Random(759123751834L);
+ private static final int ITERATIONS = 10;
+
+ /**
+ * Represents the formula {@code f(n) = start + (step * n)} for n = 0 & n < iterations
+ */
+ private static class Range {
+ private final int start;
+ private final int step;
+ private final int iterations;
+
+ private Range(int start, int step, int iterations) {
+ this.start = start;
+ this.step = step;
+ this.iterations = iterations;
+ }
+
+ /**
+ * Parses start, step and iterations from args
+ * @param args the string array containing the arguments
+ * @param start which element to start the start argument from
+ * @return the constructed range
+ */
+ public static Range parse(String[] args, int start) {
+ if (args.length < start + 3) {
+ throw new IllegalArgumentException("Too few elements in array");
+ }
+ return new Range(parseInt(args[start]), parseInt(args[start + 1]), parseInt(args[start + 2]));
+ }
+
+ public int get(int iteration) {
+ return start + (step * iteration);
+ }
+
+ public int getIterations() {
+ return iterations;
+ }
+
+ @Override
+ public String toString() {
+ StringBuilder builder = new StringBuilder();
+ builder.append(start).append(" ").append(step).append(" ").append(iterations);
+ return builder.toString();
+ }
+ }
+
+ /**
+ * Wraps the different parameters that is used when running the MergeExample.
+ * {@code sizes} represents the different array sizes
+ * {@code parallelism} represents the different parallelism levels
+ */
+ private static class Configuration {
+ private final Range sizes;
+ private final Range parallelism;
+
+ private final static Configuration defaultConfig = new Configuration(new Range(20000, 20000, 10),
+ new Range(2, 2, 10));
+
+ private Configuration(Range sizes, Range parallelism) {
+ this.sizes = sizes;
+ this.parallelism = parallelism;
+ }
+
+ /**
+ * Parses the arguments and attempts to create a configuration containing the
+ * parameters for creating the array sizes and parallelism sizes
+ * @param args the input arguments
+ * @return the configuration
+ */
+ public static Configuration parse(String[] args) {
+ if (args.length == 0) {
+ return defaultConfig;
+ } else {
+ try {
+ if (args.length == 6) {
+ return new Configuration(Range.parse(args, 0), Range.parse(args, 3));
+ }
+ } catch (NumberFormatException e) {
+ System.err.println("MergeExample: error: Argument was not a number.");
+ }
+ System.err.println("MergeExample <size start> <size step> <size steps> <parallel start> <parallel step>" +
+ " <parallel steps>");
+ System.err.println("example: MergeExample 20000 10000 3 1 1 4");
+ System.err.println("example: will run with arrays of sizes 20000, 30000, 40000" +
+ " and parallelism: 1, 2, 3, 4");
+ return null;
+ }
+ }
+
+ /**
+ * Creates an array for reporting the test result time in
+ * @return an array containing {@code sizes.iterations * parallelism.iterations} elements
+ */
+ private long[][] createTimesArray() {
+ return new long[sizes.getIterations()][parallelism.getIterations()];
+ }
+
+ @Override
+ public String toString() {
+ StringBuilder builder = new StringBuilder("");
+ if (this == defaultConfig) {
+ builder.append("Default configuration. ");
+ }
+ builder.append("Running with parameters: ");
+ builder.append(sizes);
+ builder.append(" ");
+ builder.append(parallelism);
+ return builder.toString();
+ }
+ }
+
+ /**
+ * Generates an array of {@code elements} random elements
+ * @param elements the number of elements requested in the array
+ * @return an array of {@code elements} random elements
+ */
+ private int[] generateArray(int elements) {
+ int[] array = new int[elements];
+ for (int i = 0; i < elements; ++i) {
+ array[i] = random.nextInt();
+ }
+ return array;
+ }
+
+ /**
+ * Runs the test
+ * @param config contains the settings for the test
+ */
+ private void run(Configuration config) {
+ Range sizes = config.sizes;
+ Range parallelism = config.parallelism;
+
+ // Run a couple of sorts to make the JIT compile / optimize the code
+ // which should produce somewhat more fair times
+ warmup();
+
+ long[][] times = config.createTimesArray();
+
+ for (int size = 0; size < sizes.getIterations(); size++) {
+ runForSize(parallelism, sizes.get(size), times, size);
+ }
+
+ printResults(sizes, parallelism, times);
+ }
+
+ /**
+ * Prints the results as a table
+ * @param sizes the different sizes of the arrays
+ * @param parallelism the different parallelism levels used
+ * @param times the median times for the different sizes / parallelism
+ */
+ private void printResults(Range sizes, Range parallelism, long[][] times) {
+ System.out.println("Time in milliseconds. Y-axis: number of elements. X-axis parallelism used.");
+ long[] sums = new long[times[0].length];
+ System.out.format("%8s ", "");
+ for (int i = 0; i < times[0].length; i++) {
+ System.out.format("%4d ", parallelism.get(i));
+ }
+ System.out.println("");
+ for (int size = 0; size < sizes.getIterations(); size++) {
+ System.out.format("%8d: ", sizes.get(size));
+ for (int i = 0; i < times[size].length; i++) {
+ sums[i] += times[size][i];
+ System.out.format("%4d ", times[size][i]);
+ }
+ System.out.println("");
+ }
+ System.out.format("%8s: ", "Total");
+ for (long sum : sums) {
+ System.out.format("%4d ", sum);
+ }
+ System.out.println("");
+ }
+
+ private void runForSize(Range parallelism, int elements, long[][] times, int size) {
+ for (int step = 0; step < parallelism.getIterations(); step++) {
+ long time = runForParallelism(ITERATIONS, elements, parallelism.get(step));
+ times[size][step] = time;
+ }
+ }
+
+ /**
+ * Runs <i>iterations</i> number of test sorts of a random array of <i>element</i> length
+ * @param iterations number of iterations
+ * @param elements number of elements in the random array
+ * @param parallelism parallelism for the ForkJoin framework
+ * @return the median time of runs
+ */
+ private long runForParallelism(int iterations, int elements, int parallelism) {
+ MergeSort mergeSort = new MergeSort(parallelism);
+ long[] times = new long[iterations];
+
+ for (int i = 0; i < iterations; i++) {
+ // Suggest the VM to run a garbage collection to reduce the risk of getting one
+ // while running the test run
+ System.gc();
+ long start = System.currentTimeMillis();
+ mergeSort.sort(generateArray(elements));
+ times[i] = System.currentTimeMillis() - start;
+ }
+
+ return medianValue(times);
+ }
+
+ /**
+ * Calculates the median value of the array
+ * @param times array of times
+ * @return the median value
+ */
+ private long medianValue(long[] times) {
+ if (times.length == 0) {
+ throw new IllegalArgumentException("Empty array");
+ }
+ // Make a copy of times to avoid having side effects on the parameter value
+ Arrays.sort(times.clone());
+ long median = times[times.length / 2];
+ if (times.length > 1 && times.length % 2 != 0) {
+ median = (median + times[times.length / 2 + 1]) / 2;
+ }
+ return median;
+ }
+
+ /**
+ * Generates 1000 arrays of 1000 elements and sorts them as a warmup
+ */
+ private void warmup() {
+ MergeSort mergeSort = new MergeSort(Runtime.getRuntime().availableProcessors());
+ for (int i = 0; i < 1000; i++) {
+ mergeSort.sort(generateArray(1000));
+ }
+ }
+
+ public static void main(String[] args) {
+ Configuration configuration = Configuration.parse(args);
+ if (configuration == null) {
+ System.exit(1);
+ }
+ System.out.println(configuration);
+ new MergeDemo().run(configuration);
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/sample/forkjoin/mergesort/MergeSort.java Tue Apr 12 13:14:05 2011 +0200
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of Oracle nor the names of its
+ * contributors may be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import java.util.Arrays;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.ForkJoinTask;
+import java.util.concurrent.RecursiveAction;
+
+/**
+ * A class for sorting an array of {@code ints} in parallel.
+ * A {@code ForkJoinPool} is used for the parallelism, using the merge sort
+ * algorithm the array is split into halves and a new sub task is created
+ * for each part. Each sub task is dispatched to the {@code ForkJoinPool}
+ * which will schedule the task to a {@code Thread}.
+ * This happens until the size of the array is at most 2
+ * elements long. At this point the array is sorted using a simple compare
+ * and possibly a swap. The tasks then finish by using insert sort to
+ * merge the two just sorted arrays.
+ *
+ * The idea of this class is to demonstrate the usage of RecursiveAction not
+ * to implement the best possible parallel merge sort. This version creates
+ * a small array for each merge (creating a lot of objects), this could
+ * be avoided by keeping a single array.
+ */
+public class MergeSort {
+ private final ForkJoinPool pool;
+
+ private static class MergeSortTask extends RecursiveAction {
+ private final int[] array;
+ private final int low;
+ private final int high;
+ private static final int THRESHOLD = 8;
+
+ /**
+ * Creates a {@code MergeSortTask} containing the array and the bounds of the array
+ *
+ * @param array the array to sort
+ * @param low the lower element to start sorting at
+ * @param high the non-inclusive high element to sort to
+ */
+ protected MergeSortTask(int[] array, int low, int high) {
+ this.array = array;
+ this.low = low;
+ this.high = high;
+ }
+
+ @Override
+ protected void compute() {
+ if (high - low <= THRESHOLD) {
+ Arrays.sort(array, low, high);
+ } else {
+ int middle = low + ((high - low) >> 1);
+ // Execute the sub tasks and wait for them to finish
+ invokeAll(new MergeSortTask(array, low, middle), new MergeSortTask(array, middle, high));
+ // Then merge the results
+ merge(middle);
+ }
+ }
+
+ /**
+ * Merges the two sorted arrays this.low, middle - 1 and middle, this.high - 1
+ * @param middle the index in the array where the second sorted list begins
+ */
+ private void merge(int middle) {
+ if (array[middle - 1] < array[middle]) {
+ return; // the arrays are already correctly sorted, so we can skip the merge
+ }
+ int[] copy = new int[high - low];
+ System.arraycopy(array, low, copy, 0, copy.length);
+ int copyLow = 0;
+ int copyHigh = high - low;
+ int copyMiddle = middle - low;
+
+ for (int i = low, p = copyLow, q = copyMiddle; i < high; i++) {
+ if (q >= copyHigh || (p < copyMiddle && copy[p] < copy[q]) ) {
+ array[i] = copy[p++];
+ } else {
+ array[i] = copy[q++];
+ }
+ }
+ }
+ }
+
+ /**
+ * Creates a {@code MergeSort} containing a ForkJoinPool with the indicated parallelism level
+ * @param parallelism the parallelism level used
+ */
+ public MergeSort(int parallelism) {
+ pool = new ForkJoinPool(parallelism);
+ }
+
+ /**
+ * Sorts all the elements of the given array using the ForkJoin framework
+ * @param array the array to sort
+ */
+ public void sort(int[] array) {
+ ForkJoinTask<Void> job = pool.submit(new MergeSortTask(array, 0, array.length));
+ job.join();
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/sample/mergesort/MergeSortTest.java Tue Apr 12 13:14:05 2011 +0200
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2011 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.
+ */
+
+
+/* @test
+ * @summary Test MergeSort
+ *
+ * @library ../../../src/share/sample/forkjoin/mergesort
+ * @build MergeSortTest MergeDemo MergeSort
+ * @run main MergeSortTest
+ */
+
+import java.util.Arrays;
+import java.util.Random;
+
+public class MergeSortTest {
+ private Random random;
+ private MergeSort target;
+
+ public MergeSortTest(Random random, MergeSort target) {
+ this.random = random;
+ this.target = target;
+ }
+
+ public static void main(String[] args) {
+ MergeSortTest test = new MergeSortTest(new Random(), new MergeSort(Runtime.getRuntime().availableProcessors() * 4));
+ test.run();
+ }
+
+ private int[] generateArray(int elements) {
+ int[] array = new int[elements];
+ for (int i = 0; i < array.length; ++i) {
+ array[i] = random.nextInt(10);
+ }
+ return array;
+ }
+
+ private void run() {
+ testSort();
+ testSortSingle();
+ testSortEmpty();
+ testLong();
+ }
+
+ public void testLong() {
+ for (int i = 0; i < 1000; ++i) {
+ int elements = 1 + i * 100;
+
+ int[] array = generateArray(elements);
+ int[] copy = Arrays.copyOf(array, array.length);
+ Arrays.sort(copy);
+ target.sort(array);
+ assertEqual(copy, array);
+ }
+ }
+
+ private void testSortEmpty() {
+ int[] array = { };
+ target.sort(array);
+ assertEqual(new int[] { }, array);
+ }
+
+ private void testSortSingle() {
+ int[] array = { 1 };
+ target.sort(array);
+ assertEqual(new int[] { 1 }, array);
+ }
+
+ private void testSort() {
+ int[] array = { 7, 3, 9, 0, -6, 12, 54, 3, -6, 88, 1412};
+ target.sort(array);
+ assertEqual(new int[] { -6, -6, 0, 3, 3, 7, 9, 12, 54, 88, 1412 }, array);
+ }
+
+ private void assertEqual(int[] expected, int[] array) {
+ if (!Arrays.equals(expected, array)) {
+ throw new RuntimeException("Invalid sorted array!");
+ }
+ }
+
+
+}