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/*

 * @test TestEagerReclaimHumongousRegionsClearMarkBits

 * @bug 8051973

 * @summary Test to make sure that eager reclaim of humongous objects correctly clears

 * mark bitmaps at reclaim.

 * @key gc

 * @library /testlibrary

 * @modules java.base/sun.misc

 *          java.management

 */

import java.util.ArrayList;

import java.util.LinkedList;

import java.util.Random;

import jdk.test.lib.OutputAnalyzer;

import jdk.test.lib.ProcessTools;

// An object that has a few references to other instances to slow down marking.

class ObjectWithSomeRefs {

    public ObjectWithSomeRefs other1;

    public ObjectWithSomeRefs other2;

    public ObjectWithSomeRefs other3;

    public ObjectWithSomeRefs other4;

}

class ReclaimRegionFast {

    public static final long MAX_MILLIS_FOR_RUN = 50 * 1000; // The maximum runtime for the actual test.

    public static final int M = 1024*1024;

    public static LinkedList<Object> garbageList = new LinkedList<Object>();

    public static void genGarbage(Object large) {

        for (int i = 0; i < 64*1024; i++) {

            Object[] garbage = new Object[50];

            garbage[0] = large;

            garbageList.add(garbage);

        }

        garbageList.clear();

    }

    public static ArrayList<ObjectWithSomeRefs> longList = new ArrayList<ObjectWithSomeRefs>();

    public static void main(String[] args) {

        for (int i = 0; i < 16*1024; i++) {

             longList.add(new ObjectWithSomeRefs());

        }

        Random rnd = new Random();

        for (int i = 0; i < longList.size(); i++) {

             int len = longList.size();

             longList.get(i).other1 = longList.get(rnd.nextInt(len));

             longList.get(i).other2 = longList.get(rnd.nextInt(len));

             longList.get(i).other3 = longList.get(rnd.nextInt(len));

             longList.get(i).other4 = longList.get(rnd.nextInt(len));

        }

        int[] large1 = new int[M];

        int[] large2 = null;

        int[] large3 = null;

        int[] large4 = null;

        Object ref_from_stack = large1;

        long start_millis = System.currentTimeMillis();

        for (int i = 0; i < 20; i++) {

            long current_millis = System.currentTimeMillis();

            if ((current_millis - start_millis) > MAX_MILLIS_FOR_RUN) {

              System.out.println("Finishing test because maximum runtime exceeded");

              break;

            }

            // A set of large objects that will be reclaimed eagerly - and hopefully marked.

            large1 = new int[M - 20];

            large2 = new int[M - 20];

            large3 = new int[M - 20];

            large4 = new int[M - 20];

            genGarbage(large1);

            // Make sure that the compiler cannot completely remove

            // the allocation of the large object until here.

            System.out.println(large1 + " " + large2 + " " + large3 + " " + large4);

        }

        // Keep the reference to the first object alive.

        System.out.println(ref_from_stack);

    }

}

public class TestEagerReclaimHumongousRegionsClearMarkBits {

    public static void main(String[] args) throws Exception {

        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(

            "-XX:+UseG1GC",

            "-Xms128M",

            "-Xmx128M",

            "-Xmn2M",

            "-XX:G1HeapRegionSize=1M",

            "-XX:InitiatingHeapOccupancyPercent=0", // Want to have as much as possible initial marks.

            "-XX:+UnlockDiagnosticVMOptions",

            "-XX:+VerifyAfterGC",

            "-XX:ConcGCThreads=1", // Want to make marking as slow as possible.

            "-XX:+IgnoreUnrecognizedVMOptions", // G1VerifyBitmaps is develop only.

            "-XX:+G1VerifyBitmaps",

            ReclaimRegionFast.class.getName());

        OutputAnalyzer output = new OutputAnalyzer(pb.start());

        output.shouldHaveExitValue(0);

    }

}