mapcomparisons.java

《Thinking in Java 4th Edition》 Source Code

//: concurrency/MapComparisons.java
// {Args: 1 10 10} (Fast verification check during build)
// Rough comparison of thread-safe Map performance.
import java.util.concurrent.*;
import java.util.*;
import net.mindview.util.*;

abstract class MapTest
extends Tester<Map<Integer,Integer>> {
  MapTest(String testId, int nReaders, int nWriters) {
    super(testId, nReaders, nWriters);
  }
  class Reader extends TestTask {
    long result = 0;
    void test() {
      for(long i = 0; i < testCycles; i++)
        for(int index = 0; index < containerSize; index++)
          result += testContainer.get(index);
    }
    void putResults() {
      readResult += result;
      readTime += duration;
    }
  }
  class Writer extends TestTask {
    void test() {
      for(long i = 0; i < testCycles; i++)
        for(int index = 0; index < containerSize; index++)
          testContainer.put(index, writeData[index]);
    }
    void putResults() {
      writeTime += duration;
    }
  }
  void startReadersAndWriters() {
    for(int i = 0; i < nReaders; i++)
      exec.execute(new Reader());
    for(int i = 0; i < nWriters; i++)
      exec.execute(new Writer());
  }
}

class SynchronizedHashMapTest extends MapTest {
  Map<Integer,Integer> containerInitializer() {
    return Collections.synchronizedMap(
      new HashMap<Integer,Integer>(
        MapData.map(
          new CountingGenerator.Integer(),
          new CountingGenerator.Integer(),
          containerSize)));
  }
  SynchronizedHashMapTest(int nReaders, int nWriters) {
    super("Synched HashMap", nReaders, nWriters);
  }
}

class ConcurrentHashMapTest extends MapTest {
  Map<Integer,Integer> containerInitializer() {
    return new ConcurrentHashMap<Integer,Integer>(
      MapData.map(
        new CountingGenerator.Integer(),
        new CountingGenerator.Integer(), containerSize));
  }
  ConcurrentHashMapTest(int nReaders, int nWriters) {
    super("ConcurrentHashMap", nReaders, nWriters);
  }
}

public class MapComparisons {
  public static void main(String[] args) {
    Tester.initMain(args);
    new SynchronizedHashMapTest(10, 0);
    new SynchronizedHashMapTest(9, 1);
    new SynchronizedHashMapTest(5, 5);
    new ConcurrentHashMapTest(10, 0);
    new ConcurrentHashMapTest(9, 1);
    new ConcurrentHashMapTest(5, 5);
    Tester.exec.shutdown();
  }
} /* Output: (Sample)
Type                             Read time     Write time
Synched HashMap 10r 0w        306052025049              0
Synched HashMap 9r 1w         428319156207    47697347568
readTime + writeTime =        476016503775
Synched HashMap 5r 5w         243956877760   244012003202
readTime + writeTime =        487968880962
ConcurrentHashMap 10r 0w       23352654318              0
ConcurrentHashMap 9r 1w        18833089400     1541853224
readTime + writeTime =         20374942624
ConcurrentHashMap 5r 5w        12037625732    11850489099
readTime + writeTime =         23888114831
*///:~