test/hotspot/jtreg/vmTestbase/gc/gctests/WeakReference/WeakReferenceTest/WeakReferenceTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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.
 *
 * 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 WeakReferenceTest extends GCTestBase {

    /**
     * Test that all WeakReferences has been cleared after
     * the GC has run. This test should not throw an OOME
     * during the test execution.
     *
     */
    @Override
    public void run() {
        long seed;
        int minSize;
        int maxSize;
        double memPercentToFill;
        long totalMemAlloced = 0;
        long memToAlloc = 0;
        Runtime r = Runtime.getRuntime();

        seed = runParams.getSeed();
        minSize = 2048;
        maxSize = 32768;

        memPercentToFill = 0.45;

        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];

                arrWeakRefs.add(new WeakReference(tmp));
                totalMemAlloced += allocationSize;

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

            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 WeakReferenceTest(), args);
    }
}