JMH入門

package com.jmh;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class PS {

	static List<Integer> nums = new ArrayList<>();
	static {
		Random r = new Random();
		for (int i = 0; i < 1000; i++) nums.add(1000000 + r.nextInt(1000000));
	}
	static void foreach() {
		nums.forEach(v->isPrime(v));
	}
	static void parallel() {
		nums.parallelStream().forEach(PS::isPrime);
	}
	static boolean isPrime(int num) {
		for(int i=2; i<=num/2; i++) {
			if(num % i == 0) return false;
		}
		return true;
	}
}

package com.jmh;
import org.openjdk.jmh.annotations.*;
import static org.junit.jupiter.api.Assertions.*;
//com.mashibing.jmh.PSTest.testForEach
public class PSTest {
    @Benchmark
    @Warmup(iterations = 1, time = 3)
    @Fork(5)
    @BenchmarkMode(Mode.Throughput)
    @Measurement(iterations = 1, time = 3)
    public void testForEach() {
        PS.foreach();
    }
}

 在.idea/workspace.xml中修改如下：

對以上方法做性能測試。