gistfile1.java

import com.github.krukow.clj_ds.PersistentMap;
import com.github.krukow.clj_ds.Persistents;
import org.junit.Test;
import org.junit.Ignore;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;

public class MapTests {
    Random random = new Random();
    private Long randomLong() {
        Long x = random.nextLong();
        while(x < 0) x = random.nextLong();
        return x;
    }

    @Test
    public void test() {
        long start = System.nanoTime();
        PersistentMap<Long,Integer> pmap = Persistents.hashMap();
        for(int i=0; i<10000; i++) {
            pmap = pmap.plus(randomLong(),i);
        }
        long end = System.nanoTime();
        System.out.println(end-start);
    }

    @Test
    @Ignore
    public void testMut() {
        long start = System.nanoTime();
        Map<Long,Integer> map = new HashMap<Long, Integer>();
        for(int i=0; i<10000; i++) {
            map.put(randomLong(),i);
        }
        long end = System.nanoTime();
        System.out.println(end-start);
    }

    @Test
    public void testConc() {
        long start = System.nanoTime();
        Map<Long,Integer> map = new ConcurrentHashMap<Long, Integer>();
        for(int i=0; i<10000; i++) {
            map.put(randomLong(), i);
        }
        long end = System.nanoTime();
        System.out.println(end-start);
    }

    @Test
    public void testSync() {
        long start = System.nanoTime();
        Map<Long,Integer> map = Collections.synchronizedMap(new HashMap<Long, Integer>());
        for(int i=0; i<10000; i++) {
            map.put(randomLong(),i);
        }
        long end = System.nanoTime();
        System.out.println(end-start);
    }
}

/*
I think the github project has them. 
Single threaded write up: https://gist.github.com/danboykis/8420057

Immutable: 101324000
Mutable:   19731000
Conc:      33547000
Sync:      21788000
*/