Thread Safe List Efficiency Test

List common classes and their respective advantages and disadvantages can refer to https://blog.csdn.net/weixin_39883065/article/details/111197724

local environment

java version: 1.8.0_161
window information:

test code

The following code tests the List thread-safe class Vector, Collections.synchronizedList(List list), CopyOnWriteArrayList

The test adds 100 million data, opens 100 threads, and inserts 1 million data per thread

public class TestList {
    
    
    public static void main(String[] args) throws InterruptedException {
    
    
        long startTime = System.currentTimeMillis();
        // 线程不安全
        // List<Integer> list = new ArrayList<>();
        // 线程安全 100000000 耗时 27357
        // List<Integer> list = new Vector<>();
        // 线程安全 100000000 耗时 22023
         List<Integer> list = Collections.synchronizedList(new ArrayList<>());
        // 线程安全 100000000 耗时
        //List<Integer> list =new CopyOnWriteArrayList<>();
        int threadNum = 100;
        CountDownLatch countDownLatch = new CountDownLatch(threadNum);
        for (int i = 0; i < threadNum; i++) {
    
    
            Thread thread = new Thread(() -> {
    
    
                for (int j = 0; j < 1000000; j++) {
    
    
                    list.add(j);
                }
                countDownLatch.countDown();
            });
            thread.start();
        }
        countDownLatch.await();
        long endTime = System.currentTimeMillis();
        System.out.println(list.size());
        System.out.println(list.getClass()+"耗时：          "+(endTime-startTime));
    }
}

ArrayList Result

Collections.synchronizedList(List list) Result

Vector Result

CopyOnWriteArrayList Result, no result yet, run for more than 20 minutes, give up the test

Summarize

• In the case of more reads and less writes, it is recommended to use the CopyOnWriteArrayList method
• In the case of less reading and more writing, it is recommended to use Collections.synchronizedList() and Vector. There is not much difference