Java Thread Word Tearing

https://docs.oracle.com/javase/specs/jls/se9/html/jls-17.html

Some processors do not provide the ability to write to a single byte. It would be illegal to implement byte array updates on such a processor by simply reading an entire word, updating the appropriate byte, and then writing the entire word back to memory. This problem is sometimes known as word tearing, and on processors that cannot easily update a single byte in isolation some other approach will be required.

// code to detect word-tearing

public class WordTearing extends Thread { static final int LENGTH = 8; static final int ITERS = 1000000; static byte[] counts = new byte[LENGTH]; static Thread[] threads = new Thread[LENGTH]; final int id; WordTearing(int i) { id = i; } public void run() { byte v = 0; for (int i = 0; i < ITERS; i++) { byte v2 = counts[id]; if (v != v2) { System.err.println("Word-Tearing found: " + "counts[" + id + "] = "+ v2 + ", should be " + v); return; } v++; counts[id] = v; } } public static void main(String[] args) { for (int i = 0; i < LENGTH; ++i) (threads[i] = new WordTearing(i)).start(); } }