Question

在我的应用程序中，每次使用Groovy都不能自动装箱吗？

以下代码......

public class SumTest {
    public static void main(String[] args) {
        long[] longs = new long[100000000];

        long nanoStart = System.nanoTime();
        long counter = 1;
        for (int i = 0; i < longs.length; i++) {
            longs[i] = counter++;
        }

        double msPop = (System.nanoTime() - nanoStart) / 1000000d;
        System.out.println("Time taken, population: " + msPop + "ms.");

        nanoStart = System.nanoTime();
        long sum = 0;
        for (int i = 0; i < longs.length; i++) {
            sum += longs[i];
        }
        double msSum = (System.nanoTime() - nanoStart) / 1000000d;
        System.out.println("Time taken, sum: " + msSum + "ms, total: " + (msPop + msSum) + "ms");
        System.out.println(" (sum: " + sum + ")");
    }
}

...从'.java'重命名为'.groovy'时展示了截然不同的运行时间：

爪哇：

Time taken, population: 94.793746ms.
Time taken, sum: 65.172605ms, total: 159.966351ms
 (sum: 5000000050000000)

Groovy的：

Time taken, population: 2233.995965ms.
Time taken, sum: 2203.64302ms, total: 4437.638985ms
 (sum: 5000000050000000)

..这是一个~30倍的差异。

当我在一个对象内部长时间（就像在我的真实代码中的情况一样）时，情况变得复杂：

public class SumTest {
    static class Holder {
        long l;
        Holder(long l) { this.l = l; }
        long getL() { return l; }
    }

    public static void main(String[] args) {
        Holder[] longs = new Holder[100000000];

        long nanoStart = System.nanoTime();
        long counter = 1;
        for (int i = 0; i < longs.length; i++) {
            longs[i] = new Holder(counter++);
        }

        double msPop = (System.nanoTime() - nanoStart) / 1000000d;
        System.out.println("Time taken, population: " + msPop + "ms.");

        nanoStart = System.nanoTime();
        long sum = 0;
        for (int i = 0; i < longs.length; i++) {
            sum += longs[i].getL();
        }
        double msSum = (System.nanoTime() - nanoStart) / 1000000d;
        System.out.println("Time taken, sum: " + msSum + "ms, total: " + (msPop + msSum) + "ms");
        System.out.println(" (sum: " + sum + ")");
    }
}

运行时间（注意我在这里使用-Xms16384M -Xmx16384M运行）：

爪哇

Time taken, population: 1083.784927ms.
Time taken, sum: 180.518991ms, total: 1264.3039179999998ms
 (sum: 5000000050000000)

Groovy的：

Time taken, population: 9816.007447ms.
Time taken, sum: 8685.506864ms, total: 18501.514311ms
 (sum: 5000000050000000)

..总共快了约15倍，但最重要的区别在于实际使用这些对象（用求和表示）：~50x。

能以某种方式解决这个问题吗？当问题仅涉及原语和原语操作时，我是否可以哄骗Groovy不对每个涉及原语的操作进行自动操作？

Answer 1

（哇！奇怪，如何彻底地制定问题几乎立即导致答案？！）

修复：在课堂上写下@CompileStatic。

Time taken, population: 1562.978726ms.
Time taken, sum: 183.388353ms, total: 1746.367079ms
 (sum: 5000000050000000)

Groovy在原语上非常慢

1 个答案: