多个线程启动 ，等待全部执行完毕再搜集数据

前几天在公司的项目上有个同事使用了多线程统计数据，当时出现了一个用户一直使用服务器首次登录信息作为查询信息。找了半天才发现，线程池资源同步了。后面手动将数据set进去的。

等待线程全部执行完毕，这里使用的是减法计数器，也可而已用加法计数器：CyclicBarrier

package com.quxiao.controller;


import java.util.*;
import java.util.concurrent.*;
import java.util.stream.Collectors;

/**
 * @program: package1
 * @author: quxiao
 * @create: 2023-09-27 15:22
 **/
public class t3 {
    static final ExecutorService service = Executors.newFixedThreadPool(10);

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(4);
        FutureTask task1 = new FutureTask<>(new t(2, countDownLatch));
        FutureTask task2 = new FutureTask<>(new t(3, countDownLatch));
        FutureTask task3 = new FutureTask<>(new t(4, countDownLatch));
        FutureTask task4 = new FutureTask<>(new t(5, countDownLatch));
        service.execute(task1);
        service.execute(task2);
        service.execute(task3);
        service.execute(task4);
        countDownLatch.await();
        System.out.println(task1.get());
        System.out.println(task2.get());
        System.out.println(task3.get());
        System.out.println(task4.get());
//        service.shutdown();
    }


    static class t implements Callable> {
        List list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9);
        int sum = 0;
        CountDownLatch countDownLatch;

        public t(int sum, CountDownLatch countDownLatch) {
            this.sum = sum;
            this.countDownLatch = countDownLatch;
        }

        @Override
        public List call() throws Exception {
            TimeUnit.SECONDS.sleep(1L);
            List returnList = list.stream().filter(x -> x >= sum).collect(Collectors.toList());
            countDownLatch.countDown();
            return returnList;
        }
    }
}

限流操作，限制人数访问，超过预定值就等待：

package com.quxiao.controller;


import java.util.*;
import java.util.concurrent.*;
import java.util.stream.Collectors;

/**
 * @program: package1
 * @author: quxiao
 * @create: 2023-09-27 15:22
 **/
public class t3 {
    static final ExecutorService service = Executors.newFixedThreadPool(10);

    public static void main(String[] args) throws ExecutionException, InterruptedException {
        Semaphore semaphore = new Semaphore(3);
        for (int i = 0; i < 9; i++) {
            final int t = i;
            new Thread(() -> {
                try {
                    semaphore.acquire();
                    TimeUnit.SECONDS.sleep(5L);
                    System.out.println(Thread.currentThread().getName() + "进来了");
                    System.out.println(Thread.currentThread().getName() + "出去了");
                    System.out.println();
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                } finally {
                    semaphore.release();
                }
            }, "" + i).start();
        }
    }
}