Small class to test GC performance

gistfile1.txt

import java.lang.management.GarbageCollectorMXBean;
import java.lang.management.ManagementFactory;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Benjamin Stopford - 11/09/13
 */
public class GCInvestigation {
    public static void main(String[] args) throws InterruptedException {

        new GCInvestigation();
    }

    public GCInvestigation() throws InterruptedException {
        long start = System.currentTimeMillis();
        Map map = new HashMap();
        int size = 3500000;
        int count = 0;
        while (count++ <3) {
            try {
                //allocate 1GB of heap;
                for (int i = 0; i < size; i++) {
                    map.put(i, new byte[1024]);
                }
                System.out.format("Created 1 %,dMB of garbage.\n", map.size());

                System.out.println("Should have failed");
                Thread.sleep(1000);
            } finally {
                System.out.println("size of map " + map.size());
            }
            System.out.println("Took "+(System.currentTimeMillis() - start));
        printGcinfo();
            map.clear();
        }
    }

    private void printGcinfo(){
        List<GarbageCollectorMXBean> gcList = ManagementFactory.getGarbageCollectorMXBeans();
        for(GarbageCollectorMXBean tmpGC : gcList){
            System.out.println(tmpGC.getName() + " time "+ tmpGC.getCollectionTime());
        }
    }

    /**
     -Xmx5g -Xms5g -XX:NewSize=4g -XX:ParallelGCThreads=12
     Took 19849
     PS Scavenge time 7938
     PS MarkSweep time 5987

     -Xmx5g -Xms5g -XX:NewSize=3g :
     Took 12032
     PS Scavenge time 641
     PS MarkSweep time 5600

     -Xmx5g -Xms5g -XX:NewSize=3g -XX:ParallelGCThreads=12
     Took 12264
     PS Scavenge time 752
     PS MarkSweep time 5795

     -Xmx5g -Xms5g -XX:NewSize=1g  :
     Took 14560
     PS Scavenge time 2544
     PS MarkSweep time 6463

     -Xmx5g -Xms5g -XX:NewSize=1g   -XX:ParallelGCThreads=12
     Took 14527
     PS Scavenge time 2450
     PS MarkSweep time 6545

     */
}