java、go、node.js 对于递归程序(如麻将胡牌算法)并发性能对比测试

1)java

package Demo07_recursive;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Main {
    public static int f(int i) {
        if (i <= 1) {
            return 1;
        }

        return f(i - 1) + f(i - 2);
    }

    public static void main(String[] args) {
        ExecutorService executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 2);

        long start = System.currentTimeMillis();

        for (int i = 0; i <= 20; i++) {
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    int ret = f(45);
                    System.out.println(ret);

                    long end = System.currentTimeMillis();
                    System.out.println((end - start) * 1.0 / 1000);
                }
            });
        }

        executorService.shutdown();
    }
}

/*
1836311903
9.371
1836311903
10.513
1836311903
10.843
1836311903
12.747
1836311903
14.847
1836311903
15.208
1836311903
15.256
1836311903
15.34
1836311903
15.437
1836311903
15.917
1836311903
16.116
1836311903
17.115
1836311903
17.237
1836311903
17.762
1836311903
17.806
1836311903
17.851
1836311903
18.009
1836311903
19.597
1836311903
19.864
1836311903
20.803
1836311903
21.367
 */

从第9s开始有响应,然后直到21s结束

2)go

package main

import (
	"fmt"
	"runtime"
	"time"
)

func f(i int) int {
	if i <= 1 {
		return 1
	}
	return f(i-1) + f(i-2)
}

func main() {
	num := runtime.NumCPU()
	fmt.Println("核心数:", num)
	runtime.GOMAXPROCS(num)

	start := time.Now().Second()

	for i := 0; i <= 20; i++ {
		go func() {
			fmt.Println(f(45))

			end := time.Now().Second()

			fmt.Println(start, end, end - start)
		}()
	}

	time.Sleep(time.Second * 100)
}

/*
核心数: 8
1836311903
0 36 36
1836311903
0 37 37
1836311903
0 37 37
1836311903
0 37 37
1836311903
0 37 37
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
1836311903
0 38 38
*/

go则是大约38s左右才全部完成

3)node.js

function f(i){
    if (i <= 1){
        return 1
    }

    return f(i-1) + f(i-2)
}
var start = new Date().getTime()

for(var i = 0; i <= 20; i++){
    console.log(f(45))

    var end = new Date().getTime()
    console.log((end-start)/1000)
}

/*
1836311903
14.514
1836311903
28.959
1836311903
43.368
1836311903
57.752
1836311903
72.262
1836311903
87.003
1836311903
101.464
1836311903
115.844
1836311903
130.212
1836311903
144.57
1836311903
158.946
1836311903
173.294
1836311903
187.673
1836311903
202.04
1836311903
216.435
1836311903
230.807
1836311903
245.184
1836311903
259.594
1836311903
273.993
1836311903
288.358
1836311903
302.695
*/

总结:

go是用户级别的线程, java则是内核级别的线程，任务少时真正实现多线程调度。时间更短。go则是由go专门调度器调度，无法控制。

node.js除非开多进程,否则单线程只能顺序执行

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java、go、node.js 对于递归程序(如麻将胡牌算法)并发性能对比测试

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