WeakReferenceEvilTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package gc.gctests.WeakReference;

import java.util.Random;
import java.util.ArrayList;
import java.lang.ref.WeakReference;
import nsk.share.TestFailure;
import nsk.share.gc.GC;
import nsk.share.gc.GCTestBase;

/**
 * Original description from JRockit test:
 * Tests for the WeakReference handling in JRockit (in a more evil way :)).
 *
 * This test must be run with a mx value set, as well as with
 * -XXfullsystemgc, to ensure Runtime.maxMemory() doesn't return 0
 * and that System.gc() gets run when called from Java.
 */
public class WeakReferenceEvilTest extends GCTestBase {

    /**
     * Test the WeakReference handling in a more evil way. In this test,
     * it will only keep every Xth object, thus causing more fragmentation
     * and fill the heap with unused objects. This test should not
     * throw any OOME during the test execution.
     *
     * @return success if all WeakReferences are NULL after
     * the test has run
     */
    public void run() {
        long seed;
        int minSize;
        int maxSize;
        int keepEveryXthObject;
        double memPercentToFill;
        long counter = 0;
        long totalMemAlloced = 0;
        long memToAlloc = 0;
        Runtime r = Runtime.getRuntime();

        seed = runParams.getSeed();
        minSize = 2048;
        maxSize = 32768;
        memPercentToFill =  0.45;
        keepEveryXthObject = 5;

        memToAlloc = (long) (r.maxMemory() * memPercentToFill);

        Random rndGenerator = new Random(seed);
        long multiplier = maxSize - minSize;
        ArrayList arrWeakRefs = new ArrayList();

        try {
            while (totalMemAlloced < memToAlloc) {
                int allocationSize = ((int) (rndGenerator.nextDouble()
                        * multiplier)) + minSize;
                byte[] tmp = new byte[allocationSize];

                if (counter % keepEveryXthObject == 0) {
                    arrWeakRefs.add(new WeakReference(tmp));
                    totalMemAlloced += allocationSize;
                }

                // Make sure the temporary object is dereferenced
                tmp = null;

                counter++;
                if (counter == Long.MAX_VALUE) {
                    counter = 0;
                }
            }

            System.gc();

            long numberOfNotNulledObjects = 0;

            for (int i = 0; i < arrWeakRefs.size(); i++) {
                WeakReference wr = (WeakReference) arrWeakRefs.get(i);
                Object o = wr.get();

                if (o != null) {
                    numberOfNotNulledObjects++;
                }
            }

            if (numberOfNotNulledObjects > 0) {
                throw new TestFailure(numberOfNotNulledObjects + " out of "
                        + arrWeakRefs.size() + " WeakReferences was not "
                        + "null after the GC had run");
            }

            log.info("All WeakReferences was cleared after the "
                    + "GC had run");
        } catch (OutOfMemoryError oome) {
            throw new TestFailure("OutOfMemoryException was thrown. This should "
                + "not happen during the execution of this test.");
        } finally {
            arrWeakRefs = null;
        }
    }
     public static void main(String[] args) {
        GC.runTest(new WeakReferenceEvilTest(), args);
    }
}