System.gc() Versus Runtime.getRunTime().gc

Question

Hi Guys,
Which one is better System.gc or Runtime.getRuntime().gc()
Because currently i am encounter out of memory Exception because i process a very large dataset..
I test System.gc() on my system and it seems doesnt free up the memory while the Runtime.getRuntime().gc will free up the memory..
I M just wondering why a lot of articles tell to use System.gc()
Thanks.

Answer 1

Hi
System.gc doesnt really work fine for me..
Here is my code
import java.util.*;
public class GCTest {
final int NELEMS = 50000;
public static Vector ve;
public static Vector ve2;
void eatMemory() {
     ve = new Vector();
ve2= new Vector();
     for(long i=0;i<100000;i++)
               ve.add("String");
               String a="a";
               if(i==90000)
     Runtime runtime = Runtime.getRuntime();
     //runtime.gc();
                    System.out.println ("Free memory after 90000 Record : " + runtime.freeMemory() );
public static void main (String[] args) {
GCTest gct = new GCTest();
// Step 1: get a Runtime object
Runtime r = Runtime.getRuntime();
// Step 2: determine the current amount of free memory
long freeMem = r.freeMemory();
System.out.println("free memory before creating array: " + freeMem);
// Step 3: consume some memory
gct.eatMemory();
// Step 4: determine amount of memory left after consumption
freeMem = r.freeMemory();
System.out.println("free memory after creating array: " + freeMem);
// Step 5: run the garbage collector, then check freeMemory
//r.gc();
freeMem = r.freeMemory();
System.gc();
System.out.println("free memory after running gc(): " + freeMem);
System.out.println(" Vector size = "+GCTest.ve.size());
If u Run using System.gc , you will be able to see that the Free Memory is not increase