多线程测试有重复序列号 about snowflake HOT 5 CLOSED

package com.example.demo.utils;

import java.util.HashSet;
import java.util.Set;

class SnowFlakeKeyTest {
    private static Set keys = new HashSet();

    public static void main(String[] args) {
        long start = System.currentTimeMillis();

        for (int i = 0; i < 31; i++) {
            for (int j = 0; j < 31; j++) {
                SnowFlakeKeyTest.GetKey runner = new SnowFlakeKeyTest().new GetKey(i, j);
                new Thread(runner).start();
            }
        }

        long end = System.currentTimeMillis();
        System.out.println(keys.size() + " unique ids have been generated in " + (end - start) + "ms!\n" + keys);

    }

    class GetKey implements Runnable {

        private final int datacenterId;
        private final int machineId;

        public GetKey(int datacenterId, int machineId) {
            this.datacenterId = datacenterId;
            this.machineId = machineId;
        }

        @Override
        public void run() {
            SnowFlake key = new SnowFlake(datacenterId, machineId);
            long k = key.nextId();
            if (!keys.contains(k)) {
                keys.add(k);
            } else {
                System.out.println("重复:" + k);
            }
        }
    }
}

import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;

class SnowFlakeKeyTest {
    private static Set keys = Collections.synchronizedSet(new HashSet(9610000));
    private static AtomicInteger x = new AtomicInteger(0);

    public static void main(String[] args) {
        long start = System.currentTimeMillis();

        List<Thread> threads = new ArrayList<>(961);
        for (int i = 0; i < 31; i++) {
            for (int j = 0; j < 31; j++) {
                SnowFlakeKeyTest.GetKey runner = new SnowFlakeKeyTest().new GetKey(i, j);
                Thread thread = new Thread(runner);
                thread.start();
                threads.add(thread);
            }
        }

        System.out.println(threads.size() + " threads have been started...");

        try {
            System.out.println("Waiting for threads to finish...");
            for (Thread thread: threads) {
                thread.join();
            }
            long end = System.currentTimeMillis();
            System.out.println(keys.size() + " unique ids (should: " + x + ") have been generated in " + (end - start) + "ms!");
        } catch (InterruptedException e) {
            System.out.println("Main thread Interrupted");
        }
    }

    class GetKey implements Runnable {

        private final int datacenterId;
        private final int machineId;

        public GetKey(int datacenterId, int machineId) {
            this.datacenterId = datacenterId;
            this.machineId = machineId;
        }

        @Override
        public void run() {
            SnowFlake key = new SnowFlake(datacenterId, machineId);

            for (int i = 0; i < 10000; i++) {
                long k = key.nextId();
                if (!keys.add(k)) {
                    System.out.println("duplicate:" + k);
                }
                x.incrementAndGet();
            }
        }
    }
}

961 threads have been started...
Waiting for threads to finish...
9610000 unique ids (should: 9610000) have been generated in 3757ms!