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8210280: Unnecessary reallocation when invoking HashMap.putAll()

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Co-authored-by: Michal Vala <mvala@redhat.com>
Co-authored-by: Martin Buchholz <martinrb@google.com>
Reviewed-by: martin, mvala, igerasim, chegar, rriggs
This commit is contained in:
Doug Lea 2019-02-08 13:39:22 -08:00
parent 1f230335e2
commit f0807ebc18
6 changed files with 343 additions and 2 deletions
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103
test/micro/org/openjdk/bench/java/util/HashMapBench.java Normal file
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/*
* Copyright (c) 2018, Red Hat, Inc. All rights reserved.
*
* 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 org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
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 java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;
import java.util.stream.IntStream;
import static java.util.stream.Collectors.toMap;
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
@State(Scope.Thread)
public class HashMapBench {
private Supplier<Map<Integer, Integer>> mapSupplier;
private Map<Integer, Integer> bigMapToAdd;
@Param("1000000")
private int size;
@Param
private MapType mapType;
public enum MapType {
HASH_MAP,
LINKED_HASH_MAP,
}
@Setup
public void setup() {
switch (mapType) {
case HASH_MAP:
mapSupplier = () -> new HashMap<>();
break;
case LINKED_HASH_MAP:
mapSupplier = () -> new LinkedHashMap<>();
break;
default:
throw new AssertionError();
}
ThreadLocalRandom rnd = ThreadLocalRandom.current();
this.bigMapToAdd = IntStream.range(0, size).boxed()
.collect(toMap(i -> 7 + i * 128, i -> rnd.nextInt()));
}
@Benchmark
public int putAllWithBigMapToNonEmptyMap() {
Map<Integer, Integer> map = mapSupplier.get();
map.put(-1, -1);
map.putAll(bigMapToAdd);
return map.size();
}
@Benchmark
public int putAllWithBigMapToEmptyMap() {
Map<Integer, Integer> map = mapSupplier.get();
map.putAll(bigMapToAdd);
return map.size();
}
@Benchmark
public int put() {
Map<Integer, Integer> map = mapSupplier.get();
for (int k : bigMapToAdd.keySet()) {
map.put(k, bigMapToAdd.get(k));
}
return map.size();
}
}