first test

[Bryce McKinlay]

Andrew Haley wrote:

>This isn't a test of the compiler, because it spends almost of of its
>time inside the library calls.  It's really a test of the performance
>of the different Java runtime libraries.
>
>However, I get 3860 ms for the JIT compiler and 4613 ms for gcj.  That
>means that gcj's implementation of strings and/or memory allocation is
>slightly slower.
>  
>

Actually this test isn't really fair, because a JIT compiler can inline 
the String.valueOf() call and discover that the whole loop is a no-op. 
GCJ could eventually do this too if String.valueOf() doesn't cross a 
binary boundary. Typically, however, programmers don't write code that 
doesn't do anything, so this benchmark is not a valid test of real 
application performance.

Here's a better variant:

public class Loop {

   static final int N = 2500000;
   public static String[] sa = new String[N];

    public static void main(String[] args) {
        long before = System.currentTimeMillis();
        for (int i=0; i < N; i++){
            int a = 27 + 3 * i;
            sa[i] = String.valueOf(a) + "hello";
        }
        long after = System.currentTimeMillis();
        System.out.println("time: " + (after-before));
    }
}

For this case, I get 3203ms for "gcj -O2" and 5013ms for Sun Java 1.5 beta.

Regards

Bryce