c# - Java vs .NET performance -

i got myself surprised after wrote small code compare .net 4.5 , java 8 performance in computer:

class arraytest {     public int[][] jagged;      public arraytest(int width, int height)     {         height = height;         width = width;         random rng = new random();         jagged = new int[width][];         (int = 0; < height; i++)         {             jagged[i] = new int[width];             (int j = 0; j < jagged[i][j]; j++)             {                 jagged[i][j] = rng.next(2048);             }         }     }     public int this[int i, int j]     {                 {             return jagged[i][j];         }         set         {             jagged[i][j] = value;         }     }      public void domath(arraytest a)     {         (int = 0; < height; i++)         {             (int j = 0; j < width; j++)             {                 this[i, j] *= a[i, j];             }         }     }      public int height { get; private set; }      public int width { get; private set; } }    class program {     static void main(string[] args)     {         random rng = new random();         const int loop = 10;         int width = 10000,             height = 10000;          arraytest a1 = new arraytest(width, height),             a2 = new arraytest(width, height);           stopwatch sw = new stopwatch();         sw.start();         (int = 0; < loop; i++)         {             a1.domath(a2);         }         sw.stop();          console.writeline("time taken: " + sw.elapsedmilliseconds);          console.readkey();     } } 

here java version:

    public class arraytest {     private int width, height;     private int[][] array;      public arraytest(int width, int height) {         this.width = width;         this.height = height;         array = new int[height][width];         random rng = new random();         (int = 0; < height; i++) {             (int j = 0; j < width; j++) {                 array[i][j] = rng.nextint(2048);             }         }     }      public int getwidth() {         return width;     }     public void setwidth(int width) {         this.width = width;     }     public int getheight() {         return height;     }     public void setheight(int height) {         this.height = height;     }     public int[][] getarray() {         return array;     }      public void domath(arraytest a) {         (int = 0; < height; i++) {             (int j = 0; j < width; j++) {                 array[i][j] *= a.getarray()[i][j];             }         }     }  }  public class main {      public static void main(string[] args) {         // todo auto-generated method stub         final int loops = 10;         int width = 10000, height = 10000;         arraytest a1 = new arraytest(width, height),                 a2 = new arraytest(width, height);          long start, end;           start = java.lang.system.currenttimemillis();         (int = 0; < loops; i++) {             a1.domath(a2);         }         end = java.lang.system.currenttimemillis();         system.out.println("elapsed time: " + (float)(end - start));     }  } 

in computer c# code taking 5200ms run, , java version taking 2800ms(!!!). expecting .net version run faster (or @ least close to) java, got surprised result.

note: ran .net version compiled in release mode, outside visual studio.

can explain result? right? how rewrite code c#.net version gets closer java 1 in execution speed?

[edit]

well, know not valid benchmarking or fair comparison, how rewrite code c#.net version gets closer java 1 in execution speed? tried in forms (manipulating jagged array directly, via getter, etc), test ran slower.

[edit 2]

edited test have width , height = 500, , loop = 5000. 6300ms .net version, , 3700ms java version. ran test multiple times each version, of course.

[edit 3]

just wrote similar test using flat arrays instead of 2d arrays, , time .net version runs equally or faster java. it? c#.net's jagged arrays slower java's multidimensional arrays?

any time kind of benchmarking or performance analysis, need ask lot of questions, , take particular result (to paraphrase tanenbaum), "a metric ton of salt".

however ....

i copied pasted code, , got:

compiler      version   timing --------      -------   ------ msvs 2012     c# 5      4448.0 eclipse luna  jre 1.7    977.0 

so java program ran 4.5x faster c# program.

i ran msvs "profiling wizard":

https://msdn.microsoft.com/en-us/library/dd264959.aspx

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as might able see screenshot, "big pig" in profile arraytest.get_item(int32, int32), consumed nearly half of execution time:

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