omsn

final class MyFinalClass {
 
  private final Map<Long, Object> cache; 
 
  public MyClassFixed() {
    cache = new HashMap<>();
  }
 
  // final method
  public Object get(long id) {

omsn

class MyClassOptimized {
 
  private final Map<Long, Object> cache; 
 
  public MyClassFixed() {
    cache = new HashMap<>();
  }
 
  // non-virtual method
  public final Object get(long id) {

omsn

class MyClassFixed {
 
  private final Map<Long, Object> cache; 

  public MyClassFixed() {
    // won't compile without this line
    cache = new HashMap<>();
  }
 
  public Object get(long id) {

omsn

class MyClass {

  private Map<Long, Object> cache;

  public Object get(long id) {
    return cache.get(id);
  }
}

omsn

import os

for d in ["configure", "Makefile", "lib.so"]:
    os.system("touch " + d)

omsn

LIB = my-lib
 
all: $(LIB)/lib.so
 
$(LIB)/lib.so: $(LIB)/Makefile
    @cd $(LIB); make;
 
$(LIB)/Makefile: $(LIB)/configure
    @cd $(LIB); ./configure
 

omsn

double[] array = new double[LEN];
for (int j = 0; j < array.length; j++) {
    array[j] = Math.log(j);
}

omsn

public void test() {
	final int ROUNDS = 10;
	long a1 = 0, a2 = 0, a3 = 0, t;
	
	double[] array = new double[8388608];
	
	for (int i = 0; i < ROUNDS; i++) {
		t = System.currentTimeMillis();
		attempt1(array);
		a1 += System.currentTimeMillis() - t;

omsn

class ForEach extends RecursiveAction {

	private double[] array;
	private int from;
	private int to;

	// you can fine-tune this,
	// should be sth between 100 and 10000
	public final static int TASK_LEN = 5000;

omsn

public void attempt2(final double[] array) {
	ExecutorService exec = Executors.newFixedThreadPool(NTHREADS - 1);
	final int segmentLen = array.length / NTHREADS;
	int offset = 0;
	for (int i = 0; i < NTHREADS - 1; i++) {
		final int from = offset;
		final int to = offset + segmentLen;
		exec.execute(new Runnable() {

			@Override