test.edu.umd.cloud9.util.benchmark.Benchmark1HashMapStringInt Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of cloud9 Show documentation

University of Maryland's Hadoop Library

There is a newer version: 2.0.1

package edu.umd.cloud9.util.benchmark;

import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import edu.umd.cloud9.debug.MemoryUsageUtils;

public class Benchmark1HashMapStringInt {

	public static void main(String[] args) {
		int size = 5000000;
		long startTime;
		long duration;
		Random r = new Random();
		int[] ints = new int[size];

		long usedMemory1 = MemoryUsageUtils.getUsedMemory();

		System.out.println("Benchmarking HashMap...");
		Map map = new HashMap();

		startTime = System.currentTimeMillis();
		for (int i = 0; i < size; i++) {
			int k = r.nextInt(size);
			map.put("" + i, k);
			ints[i] = k;
		}
		duration = System.currentTimeMillis() - startTime;
		System.out.println(" Inserting " + size + " random entries: " + duration + " ms");

		startTime = System.currentTimeMillis();
		for (int i = 0; i < size; i++) {
			int v = map.get("" + i);

			if (v != ints[i])
				throw new RuntimeException("Values don't match!");
		}
		duration = System.currentTimeMillis() - startTime;
		System.out.println(" Accessing " + size + " random entries: " + duration + " ms");

		long usedMemory2 = MemoryUsageUtils.getUsedMemory();

		System.out.println("Used memory before: " + usedMemory1);
		System.out.println("Used memory after: " + usedMemory2);
		System.out.println("Total memory usage: " + (usedMemory2 - usedMemory1));
		System.out.println("Memory usage per map entry: "
				+ ((float) (usedMemory2 - usedMemory1) / size));

	}
}