test/hotspot/jtreg/vmTestbase/gc/memory/Array/SampleMe/SampleMe.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/*
 * @test
 * @key gc
 *
 * @summary converted from VM Testbase gc/memory/Array/SampleMe.
 * VM Testbase keywords: [gc]
 * VM Testbase readme:
 * ## This test is a basic implementation of the thoughts below.
 * Create an object: Cell
 * which contains an array of bytes, the size of
 * which is determined in the ctor call
 * You could then have varying sizes of these objects.
 * You could then store them in an array. Then delete
 * a subset and garbage collect:
 * Basically, you are looking at the holes and the
 * remaining cells, their numbers and their locations:
 * small/medium/large sized chunks
 * small/medium/large sized holes
 * contiguous/mixed/discontiguous
 * none, few, some, many, all
 * The key here is to provide a broad spectrum of
 * various GC scenarios. eventually, you will want
 * to take into account generational effects by making
 * sure that various portions of the chunks and holes
 * are created before or after certain generational
 * boundaries (1 Megabyte of allocs, for example).
 *
 * @library /vmTestbase
 *          /test/lib
 * @run driver jdk.test.lib.FileInstaller . .
 * @run main/othervm gc.memory.Array.SampleMe.SampleMe
 */

package gc.memory.Array.SampleMe;

//SampleMe.java
// import SampleClass;

public class SampleMe
{
        public static void main(String args[])
        {
                int arraySize = 2000;
                long before;
                long after;

                SampleClass array[] = new SampleClass[arraySize];
                for (int i= 0; i < arraySize; i++)
                {
                        array[i] = new SampleClass();
                        if ((i % (arraySize / 10)) == 0)
                        {
                                System.out.println(i);
                        }
                }
                System.gc();
                System.out.println("Erasing objects");
                for (int i = 0; i < arraySize /2; i ++)
                {
                        array[i*2] = null;
                }
                System.out.println("ready to GC");
                before = System.currentTimeMillis();
                System.gc();
                after = System.currentTimeMillis();
                System.out.println(after - before);

                for (int i = 0; i < arraySize /3; i ++)
                {
                        array[i*2 + 1] = null;
                }
                before = System.currentTimeMillis();
                System.gc();
                after = System.currentTimeMillis();
                System.out.println(after - before);

                for (int i = 0; i < arraySize; i ++)
                {
                        array[i] = null;
                }
        }
}