BAEL-4686: Review comments implemented
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parent
2a1baae599
commit
074d016b64
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@ -15,7 +15,11 @@
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</parent>
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<dependencies>
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<dependency>
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<groupId>org.openjdk.jmh</groupId>
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<artifactId>jmh-core</artifactId>
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<version>${jmh-core.version}</version>
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</dependency>
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</dependencies>
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<properties>
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package com.baeldung.map.concurrenthashmap;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.TimeUnit;
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import org.openjdk.jmh.annotations.Benchmark;
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import org.openjdk.jmh.annotations.BenchmarkMode;
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import org.openjdk.jmh.annotations.Fork;
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import org.openjdk.jmh.annotations.Mode;
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import org.openjdk.jmh.annotations.OutputTimeUnit;
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import org.openjdk.jmh.annotations.Scope;
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import org.openjdk.jmh.annotations.Setup;
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import org.openjdk.jmh.annotations.State;
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import org.openjdk.jmh.annotations.Threads;
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import org.openjdk.jmh.annotations.Warmup;
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@Fork(5)
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@Threads(10)
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@Warmup(iterations = 5)
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@State(Scope.Benchmark)
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@BenchmarkMode(Mode.AverageTime)
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@OutputTimeUnit(TimeUnit.NANOSECONDS)
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public class MapPerformanceComparison {
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private int TEST_NO_ITEMS;
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public static void main(String[] args) throws Exception {
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org.openjdk.jmh.Main.main(args);
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}
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@Setup
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public void setup() {
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TEST_NO_ITEMS = 1000;
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}
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@Benchmark
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public void randomReadAndWriteSynchronizedMap() {
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Map<String, Integer> map = Collections.synchronizedMap(new HashMap<String, Integer>());
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performReadAndWriteTest(map);
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}
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@Benchmark
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public void randomReadAndWriteConcurrentHashMap() {
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Map<String, Integer> map = new ConcurrentHashMap<>();
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performReadAndWriteTest(map);
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}
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private void performReadAndWriteTest(final Map<String, Integer> map) {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.get(String.valueOf(randNumber));
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map.put(String.valueOf(randNumber), randNumber);
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}
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}
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@Benchmark
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public void randomWriteSynchronizedMap() {
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Map<String, Integer> map = Collections.synchronizedMap(new HashMap<String, Integer>());
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performWriteTest(map);
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}
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@Benchmark
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public void randomWriteConcurrentHashMap() {
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Map<String, Integer> map = new ConcurrentHashMap<>();
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performWriteTest(map);
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}
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private void performWriteTest(final Map<String, Integer> map) {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.put(String.valueOf(randNumber), randNumber);
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}
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}
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@Benchmark
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public void randomReadSynchronizedMap() {
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Map<String, Integer> map = Collections.synchronizedMap(new HashMap<String, Integer>());
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performReadTest(map);
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}
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@Benchmark
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public void randomReadConcurrentHashMap() {
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Map<String, Integer> map = new ConcurrentHashMap<>();
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performReadTest(map);
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}
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private void performReadTest(final Map<String, Integer> map) {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.get(String.valueOf(randNumber));
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}
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}
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}
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@ -1,41 +0,0 @@
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package com.baeldung.map.concurrenthashmap;
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import java.util.Collections;
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import java.util.ConcurrentModificationException;
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import java.util.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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import java.util.Map.Entry;
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import java.util.concurrent.ConcurrentHashMap;
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import org.junit.Assert;
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import org.junit.Test;
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public class ConcurrentModificationErrorTest {
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@Test(expected = ConcurrentModificationException.class)
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public void whenRemoveAndAddOnHashMap_thenConcurrentModificationError() {
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Map<Integer, String> map = new HashMap<>();
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map.put(1, "baeldung");
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map.put(2, "HashMap");
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Map<Integer, String> synchronizedMap = Collections.synchronizedMap(map);
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Iterator<Entry<Integer, String>> iterator = synchronizedMap.entrySet().iterator();
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while (iterator.hasNext()) {
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synchronizedMap.put(4, "Modification");
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iterator.next();
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}
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}
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public void whenRemoveAndAddOnConcurrentHashMap_thenNoError() {
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Map<Integer, String> map = new ConcurrentHashMap<>();
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map.put(1, "baeldung");
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map.put(2, "HashMap");
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Iterator<Entry<Integer, String>> iterator = map.entrySet().iterator();
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while (iterator.hasNext()) {
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map.put(4, "Modification");
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iterator.next();
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}
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Assert.assertEquals(4, map.size());
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}
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}
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@ -1,27 +0,0 @@
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package com.baeldung.map.concurrenthashmap;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.concurrent.ConcurrentHashMap;
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import org.junit.Assert;
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import org.junit.Test;
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public class NullAllowInMapTest {
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@Test
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public void allowOnlyNull_In_SynchronizedMap() {
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Map<String, Integer> map = Collections
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.synchronizedMap(new HashMap<String, Integer>());
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map.put(null, 1);
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Assert.assertTrue(map.get(null).equals(1));
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}
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@Test(expected = NullPointerException.class)
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public void allowOnlyNull_In_ConcurrentHasMap() {
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Map<String, Integer> map = new ConcurrentHashMap<>();
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map.put(null, 1);
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}
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}
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@ -1,158 +0,0 @@
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package com.baeldung.map.concurrenthashmap;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.TimeUnit;
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import org.junit.Assert;
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import org.junit.Test;
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public class PerformanceTest {
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public final static int THREAD_POOL_SIZE = 5;
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public final static int TEST_ITERATIONS = 5;
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public final static int TEST_NO_ITEMS = 10000;
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@Test
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public void randomReadAndWritePerformaceTest_ConcurrentHashMap_faster()
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throws InterruptedException {
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// For synchronizedMap
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Long totalTimeForSynchronizedMap = 0l;
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Map<String, Integer> slowerMap = Collections
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.synchronizedMap(new HashMap<String, Integer>());
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for (int i = 0; i < TEST_ITERATIONS; i++) {
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totalTimeForSynchronizedMap += performReadAndWriteTest(slowerMap);
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}
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Long avgTimeForSynchronizedMap = totalTimeForSynchronizedMap / TEST_ITERATIONS;
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// For ConcurrentHashMap Object
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Long totalTimeForConcurrentHashMap = 0l;
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Map<String, Integer> fasterMap = new ConcurrentHashMap<>();
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for (int i = 0; i < TEST_ITERATIONS; i++) {
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totalTimeForConcurrentHashMap += performReadAndWriteTest(fasterMap);
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}
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Long avgTimeForConcurrentHashMap = totalTimeForConcurrentHashMap / TEST_ITERATIONS;
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Assert.assertTrue(avgTimeForSynchronizedMap > avgTimeForConcurrentHashMap);
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}
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private long performReadAndWriteTest(final Map<String, Integer> map)
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throws InterruptedException {
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long startTime = System.nanoTime();
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ExecutorService exectures = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
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for (int j = 0; j < THREAD_POOL_SIZE; j++) {
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exectures.execute(new Runnable() {
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@Override
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public void run() {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.get(String.valueOf(randNumber));
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map.put(String.valueOf(randNumber), randNumber);
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}
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}
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});
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}
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exectures.shutdown();
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exectures.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
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long entTime = System.nanoTime();
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return (entTime - startTime) / 1000000L;
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}
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@Test
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public void randomWritePerformaceTest_ConcurrentHashMap_faster() throws InterruptedException {
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// For synchronizedMap
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Long totalTimeForSynchronizedMap = 0l;
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Map<String, Integer> slowerMap = Collections
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.synchronizedMap(new HashMap<String, Integer>());
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for (int i = 0; i < TEST_ITERATIONS; i++) {
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totalTimeForSynchronizedMap += performWriteTest(slowerMap);
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}
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Long avgTimeForSynchronizedMap = totalTimeForSynchronizedMap / TEST_ITERATIONS;
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// For ConcurrentHashMap Object
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Long totalTimeForConcurrentHashMap = 0l;
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Map<String, Integer> fasterMap = new ConcurrentHashMap<>();
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for (int i = 0; i < TEST_ITERATIONS; i++) {
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totalTimeForConcurrentHashMap += performWriteTest(fasterMap);
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}
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Long avgTimeForConcurrentHashMap = totalTimeForConcurrentHashMap / TEST_ITERATIONS;
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Assert.assertTrue(avgTimeForSynchronizedMap > avgTimeForConcurrentHashMap);
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}
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private long performWriteTest(final Map<String, Integer> map) throws InterruptedException {
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long startTime = System.nanoTime();
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ExecutorService exectures = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
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for (int j = 0; j < THREAD_POOL_SIZE; j++) {
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exectures.execute(new Runnable() {
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@Override
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public void run() {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.put(String.valueOf(randNumber), randNumber);
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}
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}
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});
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}
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exectures.shutdown();
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exectures.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
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long entTime = System.nanoTime();
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return (entTime - startTime) / 1000000L;
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}
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@Test
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public void randomReadPerformaceTest_ConcurrentHashMap_faster() throws InterruptedException {
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Map<String, Integer> slowerMap = Collections
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.synchronizedMap(addItems(new HashMap<String, Integer>()));
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// For synchronizedMap
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Long totalTimeForSynchronizedMap = 0l;
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for (int i = 0; i < TEST_ITERATIONS; i++) {
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totalTimeForSynchronizedMap += performReadTest(slowerMap);
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}
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Long avgTimeForSynchronizedMap = totalTimeForSynchronizedMap / TEST_ITERATIONS;
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Map<String, Integer> fasterMap = addItems(new ConcurrentHashMap<String, Integer>());
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// For ConcurrentHashMap Object
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Long totalTimeForConcurrentHashMap = 0l;
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new ConcurrentHashMap<>();
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for (int i = 0; i < TEST_ITERATIONS; i++) {
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totalTimeForConcurrentHashMap += performReadTest(fasterMap);
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}
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Long avgTimeForConcurrentHashMap = totalTimeForConcurrentHashMap / TEST_ITERATIONS;
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Assert.assertTrue(avgTimeForSynchronizedMap > avgTimeForConcurrentHashMap);
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}
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private Map<String, Integer> addItems(Map<String, Integer> map) {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.put(String.valueOf(randNumber), randNumber);
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}
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return map;
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}
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private long performReadTest(final Map<String, Integer> map) throws InterruptedException {
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long startTime = System.nanoTime();
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ExecutorService exectures = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
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for (int j = 0; j < THREAD_POOL_SIZE; j++) {
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exectures.execute(new Runnable() {
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@Override
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public void run() {
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for (int i = 0; i < TEST_NO_ITEMS; i++) {
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Integer randNumber = (int) Math.ceil(Math.random() * TEST_NO_ITEMS);
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map.get(String.valueOf(randNumber));
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}
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}
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});
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}
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exectures.shutdown();
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exectures.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS);
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long entTime = System.nanoTime();
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return (entTime - startTime) / 1000000L;
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}
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}
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