[累加器](https://www.freesion.com/arti...)的速度快我用AtomicLong子类模仿累加器，但是速度不行，请问我的代码比累加器差距在哪？我先定义一个子类，用于生成超过缓存行长度的大对象。（其实我也不清楚2个这种对象是否会发生伪共享？就算不子类化，速度也还是差不多）@sun.misc.Contendedpublic class MyAtomicLong extends AtomicLong { private static final long serialVersionUID = 1L; public MyAtomicLong(int initialValue) { super(initialValue); }}然后采用4个线程，每个线程对一个AtomicInteger对象累加public static void main(String[] args) { long start = System.nanoTime(); MyAtomicLong a = new MyAtomicLong(0); MyAtomicLong b = new MyAtomicLong(0); MyAtomicLong c = new MyAtomicLong(0); MyAtomicLong d = new MyAtomicLong(0); ArrayList<Thread> list = new ArrayList<Thread>(); for (int i = 0; i < 4; i++) { int index = i; list.add(new Thread(new Runnable() { @Override public void run() { for (int j = 0; j < 50_0000; j++) { switch (index) { case 0: a.incrementAndGet(); break; case 1: b.incrementAndGet(); break; case 2: c.incrementAndGet(); break; case 3: d.incrementAndGet(); break; default: break; } } } })); } list.forEach(Thread::start); list.forEach(t -> { try { t.join(); } catch (InterruptedException e) { System.out.println(e); } }); Long result = a.get() + b.get() + c.get() + d.get(); System.out.println( (System.nanoTime()-start)/1000_000 + " -- " + result); }为啥这代码需要100+毫秒，而累加器只要个位数？