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8371164: ArrayList.addAll() optimizations

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Reviewed-by: smarks, ogillespie
This commit is contained in:
John Engebretson 2025-11-18 23:37:06 +00:00 committed by Stuart Marks
parent 256a9beffc
commit aeea849756
4 changed files with 178 additions and 4 deletions
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14
src/java.base/share/classes/java/util/ArrayList.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1997, 2025, 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
@ -750,9 +750,17 @@ public class ArrayList<E> extends AbstractList<E>
* @throws NullPointerException if the specified collection is null
*/
public boolean addAll(Collection<? extends E> c) {
Object[] a = c.toArray();
Object[] a;
int numNew;
if (c.getClass() == ArrayList.class) {
ArrayList<?> src = (ArrayList<?>) c;
a = src.elementData;
numNew = src.size;
} else {
a = c.toArray();
numNew = a.length;
}
modCount++;
int numNew = a.length;
if (numNew == 0)
return false;
Object[] elementData;

14
src/java.base/share/classes/java/util/Collections.java
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@ -5253,6 +5253,20 @@ public final class Collections {
public int hashCode() {
return Objects.hashCode(element);
}
@Override
public Object[] toArray() {
return new Object[] {element};
}
@Override
@SuppressWarnings("unchecked")
public <T> T[] toArray(T[] a) {
if (a.length < 1)
a = (T[])Array.newInstance(a.getClass().getComponentType(), 1);
a[0] = (T)element;
if (a.length > 1)
a[1] = null;
return a;
}
}
/**

26
test/jdk/java/util/Collection/MOAT.java
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@ -26,7 +26,7 @@
* @bug 6207984 6272521 6192552 6269713 6197726 6260652 5073546 4137464
* 4155650 4216399 4294891 6282555 6318622 6355327 6383475 6420753
* 6431845 4802633 6570566 6570575 6570631 6570924 6691185 6691215
* 4802647 7123424 8024709 8193128 8327858 8368178
* 4802647 7123424 8024709 8193128 8327858 8368178 8371164
* @summary Run many tests on many Collection and Map implementations
* @author Martin Buchholz
* @modules java.base/java.util:open
@ -887,6 +887,28 @@ public class MOAT {
catch (Throwable t) { unexpected(t); }
}
private static void testAddAll(Collection<Integer> c) {
clear(c);
// Test ArrayList source
ArrayList<Integer> arrayListSource = new ArrayList<>();
arrayListSource.add(42);
arrayListSource.add(99);
check(c.addAll(arrayListSource));
equal(c.size(), arrayListSource.size());
check(c.containsAll(arrayListSource));
clear(c);
// Test non-ArrayList source
LinkedList<Integer> linkedListSource = new LinkedList<>();
linkedListSource.add(77);
linkedListSource.add(88);
check(c.addAll(linkedListSource));
equal(c.size(), linkedListSource.size());
check(c.containsAll(linkedListSource));
}
private static void testConcurrentCollection(Collection<Integer> c) {
try {
c.add(1);
@ -1294,6 +1316,8 @@ public class MOAT {
clear(c); testStringElement(c);
oneElement(c); testStringElement(c);
testAddAll(c);
if (c.getClass().getName().matches(".*concurrent.*"))
testConcurrentCollection(c);

128
test/micro/org/openjdk/bench/java/util/ArrayListBulkOpsBenchmark.java Normal file
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@ -0,0 +1,128 @@
/*
* Copyright Amazon.com Inc. 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.
*/
package org.openjdk.bench.java.util;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import java.util.WeakHashMap;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
/**
* Benchmark measuring ArrayList addAll() performance.
*
* Tests the performance of ArrayList.addAll() when copying from another ArrayList.
*/
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
@Warmup(iterations = 3, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(value = 1, jvmArgs = { "-XX:+UseParallelGC", "-Xmx3g" })
public class ArrayListBulkOpsBenchmark {
@Param({"0", "1", "5", "75"})
int size;
@Param({"ArrayList", "LinkedList"})
String type;
List<String> source;
@Setup(Level.Trial)
public void setup() {
switch (type) {
case "ArrayList" -> source = new ArrayList<>(size);
case "LinkedList" -> source = new LinkedList<>();
}
for (int i = 0; i < size; i++) source.add("key" + i);
}
@Benchmark
public ArrayList<String> addAll() {
ArrayList<String> result = new ArrayList<>(size);
result.addAll(source);
return result;
}
static void poisonCallSites() {
HashMap<String, String> hashMapSource = new HashMap<>();
TreeSet<String> treeSetSource = new TreeSet<>();
WeakHashMap<String, String> weakHashMapSource = new WeakHashMap<>();
for (int i = 0; i < 75; i++) {
hashMapSource.put("key" + i, "value" + i);
treeSetSource.add("key" + i);
weakHashMapSource.put("key" + i, "value" + i);
}
// Poison ArrayList.addAll() with different Collection types
for (int i = 0; i < 40_000; i++) {
ArrayList<Object> temp = new ArrayList<>();
temp.addAll(hashMapSource.entrySet());
temp.addAll(treeSetSource);
temp.addAll(weakHashMapSource.keySet());
}
}
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
@Warmup(iterations = 3, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(value = 1, jvmArgs = { "-XX:+UseParallelGC", "-Xmx3g" })
public static class SingletonSet {
Set<String> singletonSetSource = Collections.singleton("key");
@Param({ "false", "true" })
private boolean poison;
@Setup(Level.Trial)
public void setup() {
if (poison) poisonCallSites();
}
@Benchmark
public ArrayList<String> addAllSingletonSet() {
ArrayList<String> result = new ArrayList<>(1);
result.addAll(singletonSetSource);
return result;
}
}
}