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package optjava;

// tag::CACHE_EFFECT[]

public class Caching {

private final int ARR_SIZE = 10 * 1024 * 1024;

private final int[] testData = new int[ARR_SIZE];

private void run() {

for (int i = 0; i < 10_000; i++) {

touchEveryLine();

touchEveryItem();

}

System.out.println("Item Line");

for (int i = 0; i < 100; i++) {

long t0 = System.nanoTime();

touchEveryLine();

long t1 = System.nanoTime();

touchEveryItem();

long t2 = System.nanoTime();

long elEvery = t1 - t0;

long elLine = t2 - t1;

System.out.println(elEvery + " " + elLine);

}

}

private void touchEveryItem() {

for (int i = 0; i < testData.length; i++)

testData[i]++;

}

private void touchEveryLine() {

for (int i = 0; i < testData.length; i += 16)

testData[i]++;

}

public static void main(String[] args) {

Caching c = new Caching();

c.run();

}

}

// end::CACHE_EFFECT[]