Java 如何在这个非线程安全的arraylist类上引发争用条件？

我正在尝试构建一个线程安全的arraylist类

import java.util.stream.*;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class LongArrayListUnsafe {
public static void main(String[] args) {
LongArrayList dal1 = LongArrayList.withElements();

ExecutorService executorService =  Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

for (int i=0; i<1000; i++) {
executorService.execute(new Runnable() {
  public void run() {
    for (int i=0; i<10; i++)
      dal1.add(i);
  }
 });}
System.out.println("Using toString(): " + dal1);


for (int i=0; i<dal1.size(); i++)
  System.out.println(dal1.get(i));

System.out.println(dal1.size());} }

class LongArrayList {

private long[] items;
private int size;

public LongArrayList() {
   reset();
}

public static LongArrayList withElements(long... initialValues){
   LongArrayList list = new LongArrayList();
   for (long l : initialValues) list.add( l );
   return list;
}

// reset me to initial 
public void reset(){
  items = new long[2];
  size = 0;
}

// Number of items in the double list
public int size() {
  return size;
}

// Return item number i
public long get(int i) {
  if (0 <= i && i < size) 
   return items[i];
  else 
    throw new IndexOutOfBoundsException(String.valueOf(i));
   }

   // Replace item number i, if any, with x
   public long set(int i, long x) {
   if (0 <= i && i < size) {
    long old = items[i];
    items[i] = x;
    return old;
   } else 
     throw new IndexOutOfBoundsException(String.valueOf(i));}

   // Add item x to end of list
   public LongArrayList add(long x) {
   if (size == items.length) {
   long[] newItems = new long[items.length * 2];
   for (int i=0; i<items.length; i++)
       newItems[i] = items[i];
  items = newItems;
}
items[size] = x;
size++;
return this;
}

public String toString() {
  return Arrays.stream(items, 0,size)
  .mapToObj( Long::toString )
  .collect(Collectors.joining(", ", "[", "]"));
}
}

import java.util.stream.*；
导入java.util.array；
导入java.util.Random；
导入java.util.concurrent.ExecutorService；
导入java.util.concurrent.ExecutorService；
导入java.util.concurrent.Executors；
公共类Longarray保险柜{
公共静态void main（字符串[]args）{
LongArrayList dal1=LongArrayList.withElements（）；
ExecutorService ExecutorService=Executors.newFixedThreadPool（Runtime.getRuntime（）.availableProcessors（））；
for（int i=0；iRace条件永远不能保证出现。通常，类的线程安全性是不可测试的。公平地说，这并不完全正确。您可以使用类似项目来检测线程不安全的竞争条件。