Servlet“has started a thread but failed to stop it”- Tomcat中的内存泄漏

Apache Tomcat多次表示：

Web应用程序[/MyServlet]似乎已启动了一个名为[pool-61-thread-2]的线程，但未能停止它。这很可能会导致内存泄漏。

这是否危险？该servlet应该能够处理每天10,000个请求。

如何在线程完成后关闭它们？

class Worker {
        private final CountDownLatch startSignal;
        private final CountDownLatch doneSignal;
        private final int threadNumber;
        Worker(
                CountDownLatch startSignal,
                CountDownLatch doneSignal,
                int threadNumber
        ){
            this.startSignal = startSignal;
            this.doneSignal = doneSignal;
            this.threadNumber = threadNumber;
        }
        public String[][] getSomeStrArrArr() {
            String[][] isRs = new String[8][20];
            String[][] inRs = new String[8][20];
            String[][] iwRs = new String[8][20];
            try {
                startSignal.await();
                if (threadNumber == 1) {
                    // 获取线程1的String[][]结果
                    isRs = getIS(erg1, erg2, request);
                }
                if (threadNumber == 2) {
                    // 获取线程2的String[][]结果
                    inRs = getIN(search_plz, request);
                }
                if (threadNumber == 3) {
                    // 获取线程3的String[][]结果
                    iwRs = getIW(erg1, erg2, request);
                }
                doneSignal.countDown();
            } catch (InterruptedException ex) {
                System.out.println(
                        "线程"+threadNumber+"已被中断。"
                );
            }
            if (threadNumber == 1) {
                return isRs;
            }
            if (threadNumber == 2) {
                return inRs;
            }
            if (threadNumber == 3) {
                return iwRs;
            }
            return null;
        }
        public Callable getSomeCallableStrArrArr(){
            return new Callable() {
                public String[][] call() throws Exception {
                    return getSomeStrArrArr();
                }
            };
        }
    }
    ExecutorService pool = Executors.newFixedThreadPool(3);
    Set> set = new HashSet>();
    CountDownLatch startSignal = new CountDownLatch(1);
    CountDownLatch doneSignal = new CountDownLatch(3);
    for (int i=1;i<=3;i++) {
        Worker worker = new Worker(startSignal,doneSignal,i);
        Callable callable =
                worker.getSomeCallableStrArrArr();
        Future future = pool.submit(callable);
        set.add(future);
    }
    startSignal.countDown();
    try {
        doneSignal.await();