如下代码是否正确？

class RunnerA implements Runnable {
    private list list;
    private buffer buffer;
    
    ///重写run
    public void run() {
        synchronized(list) {
            //操作 list
        }
        synchronized(list) {
            //操作 buffer
        }
        synchronized(list) {
             synchronized(list) {
                //操作 buffer 和 buffer
            }
        }
    }
    
    ..........
    setter
    getter
}

class RunnerB implements Runnable {
    private RunnerA a;

    public RunnerB  (RunnerA a) {
        this.a = a;
    }
    
    ///重写run
    public void run() {
        synchronized(list) {
             synchronized(list) {
                //操作 buffer 和 buffer
                a.getter
                a.setter
            }
        }
    }
    ..........
    setter
    getter
}

//main 函数
{
    //线程池
    ExecutorService executorA = Executors.newCachedThreadPool();
    ExecutorService executorB = Executors.newCachedThreadPool();
    
    for(int i = 0;i < 3; i++) {
        RunnerA a = new RunnerA();
        executorA.submit(a);
        executorB.submit(new RunnerB(a));
    }
}

也就是一共三组线程

每一组由一个RunnerA 和 RunnerB，且每组的RunnerB可以操作RunnerA 中的变量
这样是否能保证，list和buffer线程安全？