与Java相比，为什么此C 代码执行速度如此慢

我最近在Java中编写了一种计算密集型算法，然后将其转换为C 。令我惊讶的是，C 执行速度较慢。现在，我编写了一个短得多的Java测试程序和一个相应的C 程序 - 见下文。我的原始代码和测试代码都有很多数组访问。C 执行时间需要更长的5.5倍(请参阅每个程序末尾的注释(。

1 ^st 21评论以下结论...

测试代码：

1. g++ -o ... Java更快5.5倍
2. g++ -O3 -o ... Java 2.9倍更快
3. g++ -fprofile-generate -march=native -O3 -o ...(运行，然后是g++ -fprofile-use等(Java 1.07倍。

我的原始项目(比测试代码复杂得多(：

1. Java更快1.8倍
2. C 1.9倍更快
3. C 2倍

Software environment:
    Ubuntu 16.04 (64 bit).
    Netbeans 8.2 / jdk 8u121 (java code executed inside netbeans)
    g++ (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609
    Compilation: g++ -o cpp_test cpp_test.cpp

Java代码：

public class JavaTest {
    public static void main(String[] args) {
        final int ARRAY_LENGTH = 100;
        final int FINISH_TRIGGER = 100000000;
        int[] intArray = new int[ARRAY_LENGTH];
        for (int i = 0; i < ARRAY_LENGTH; i++) intArray[i] = 1;
        int i = 0;
        boolean finished = false;
        long loopCount = 0;
        System.out.println("Start");
        long startTime = System.nanoTime();
        while (!finished) {
            loopCount++;
            intArray[i]++;
            if (intArray[i] >= FINISH_TRIGGER) finished = true;
            else if (i <(ARRAY_LENGTH - 1)) i++;
            else i = 0;
        }
        System.out.println("Finish: " + loopCount + " loops; " +
            ((System.nanoTime() - startTime)/1e9) + " secs");
        // 5 executions in range 5.98 - 6.17 secs (each 9999999801 loops)
    }
}

C 代码：

//cpp_test.cpp:
#include <iostream>
#include <sys/time.h>
int main() {
    const int ARRAY_LENGTH = 100;
    const int FINISH_TRIGGER = 100000000;
    int *intArray = new int[ARRAY_LENGTH];
    for (int i = 0; i < ARRAY_LENGTH; i++) intArray[i] = 1;
    int i = 0;
    bool finished = false;
    long long loopCount = 0;
    std::cout << "Startn";
    timespec ts;
    clock_gettime(CLOCK_REALTIME, &ts);
    long long startTime = (1000000000*ts.tv_sec) + ts.tv_nsec;
    while (!finished) {
        loopCount++;
        intArray[i]++;
        if (intArray[i] >= FINISH_TRIGGER) finished = true;
        else if (i < (ARRAY_LENGTH - 1)) i++;
        else i = 0;
    }
    clock_gettime(CLOCK_REALTIME, &ts);
    double elapsedTime =
        ((1000000000*ts.tv_sec) + ts.tv_nsec - startTime)/1e9;
    std::cout << "Finish: " << loopCount << " loops; ";
    std::cout << elapsedTime << " secsn";
    // 5 executions in range 33.07 - 33.45 secs (each 9999999801 loops)
}