同一个线程池,不使用volatile，某些任务修改一个共享变量,某些任务读取共享变量,变量的可见性能保证吗?

测试无法复现,是同一个线程池不用volatile就可以保证可见还是不可见时间太短了？

public class TestClass {
    public int num = 0;
}

import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class Main {
    private static final AtomicInteger threadNumber = new AtomicInteger(1);
    static  Executor executor = new ThreadPoolExecutor(100, 100, 300, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(),
            new ThreadFactory() {
                @Override
                public Thread newThread(Runnable r) {
                    Thread thread = new Thread(r);
                    thread.setName("test" + threadNumber.getAndAdd(1));
                    return thread;
                }
            });

    public static void main(String[] args) {
        TestClass testClass = new TestClass();
        executor.execute(new Runnable() {
            @Override
            public void run() {
                testClass.num = 10;
                
            }
        });
        for(int i = 1;i<1000000000000L;i++)
        executor.execute(new Runnable() {
            @Override
            public void run() {
                if(testClass.num != 10) {
                    System.out.println(testClass.num);
                }
            }
        });
    }
}