ThreadLocal内存泄漏

JAVA8中，ThreadLocal的实现是每一个Thread对象维护一个ThreadLocalMap，每个Entry都是一个弱引用，而一个对象只有弱引用时会被回收,线程结束后，这个变量就没有强引用了，自然会被回收；

但是，在使用线程池的时候，由于线程池内线程是复用的，所以会导致内存泄漏；
测试代码：

public class ThreadTest {
    private static ThreadLocal<User> userResource = new ThreadLocal<User>();

    public static class User{}

    public static void main(String[] args) throws InterruptedException {
        Set<Integer> hashRecord= ConcurrentHashMap.newKeySet();
        ThreadPoolExecutor executor=new ThreadPoolExecutor(10,10,100, TimeUnit.MINUTES,new LinkedBlockingQueue());
        CountDownLatch countDownLatch=new CountDownLatch(100);
        for(int i=0;i<100;i++) {
            executor.submit(() -> {
                try {
                    if (null == ThreadTest.userResource.get()) {
                        ThreadTest.userResource.set(new User());
                    }
                    System.out.println(ThreadTest.userResource.get());
                    hashRecord.add(ThreadTest.userResource.get().hashCode());
                }finally {
                    //ThreadTest.userResource.remove();
                    countDownLatch.countDown();
                }
            });
        }
        countDownLatch.await();
        System.out.println(hashRecord.size());
    }
}

com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@233f585c
com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@731f7d35
com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@24e0614d
com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@68abf112
com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@e71df55
com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@3cc49e81
10

可以看到一共只创建了10个User对象

放开//ThreadTest.userResource.remove();
可以看到：

com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@5d63e601
com.dianping.orderdish.queue.shop.bas.service.ThreadTest$User@2f9891a9
100

一共创建了100个User对象