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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * This code is free software; you can redistribute it and/or modify it

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  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 /*

  * @test TestGreyReclaimedHumongousObjects.java

  * @bug 8069367

  * @requires vm.gc == "G1" | vm.gc == "null"

  * @summary Test handling of marked but unscanned reclaimed humongous objects.

  * @key gc

  * @run main/othervm -XX:+UseG1GC -Xss32m -Xmx128m -XX:G1HeapRegionSize=1m

  *      -XX:+UnlockExperimentalVMOptions

  *          -XX:+G1EagerReclaimHumongousObjects

  *          -XX:+G1EagerReclaimHumongousObjectsWithStaleRefs

  *      TestGreyReclaimedHumongousObjects 1048576 90

  */

 // This test spawns a bunch of threads, each of them rapidly

 // allocating large objects and storing them into a circular buffer

 // associated with the thread.  The circular buffer results in these

 // objects becoming dead in fairly short order.

 //

 // The situation we're trying to provoke is

 //

 // (1) A humongous object H is marked and added to the mark stack.

 //

 // (2) An evacuation pause determines H is no longer live, and

 // reclaims it.  This occurs before concurrent marking has gotten

 // around to processing the mark stack entry for H.

 //

 // (3) Concurrent marking processes the mark stack entry for H.  The

 // bug is that it would attempt to scan the now dead object.

 //

 // Unfortunately, this test is *very* sensitive to configuration.

 // Among the parameters that affect whether / how often we'll get into

 // the desired situation within a reasonable amount of time are:

 //

 // - THREAD_COUNT: The number of allocating threads.

 //

 // - OLD_COUNT: The number of objects each thread keeps.

 //

 // - MAX_MEMORY: The maximum heap size.

 //

 // - G1HeapRegionSize

 //

 // - The size of the objects being allocated.

 //

 // The parameter values specified here:

 //

 // - THREAD_COUNT = 12

 // - OLD_COUNT == 4

 // - MAX_MEMORY == 128m

 // - G1HeapRegionSize = 1m

 // - Object size = 1048576 (2 regions after header overhead and roundup)

 //

 // seems to work well at provoking the desired state fairly quickly.

 // Even relatively small perturbations may change that.  The key

 // factors seem to be keeping the heap mostly full of live objects but

 // having them become dead fairly quickly.

 import java.util.Date;

 import java.util.concurrent.ExecutorService;

 import java.util.concurrent.Executors;

 import java.util.concurrent.ThreadFactory;

 import java.util.concurrent.TimeUnit;

 import sun.management.ManagementFactoryHelper;

 import com.sun.management.HotSpotDiagnosticMXBean;

 import com.sun.management.VMOption;

 public class TestGreyReclaimedHumongousObjects {

     static class NamedThreadFactory implements ThreadFactory {

        private int threadNum = 0;

        @Override

        public Thread newThread(Runnable r) {

          return new Thread(r, THREAD_NAME + (threadNum++));

        }

     }

     static class Runner extends Thread {

         private final Date startDate = new Date();

         private final int obj_size;

         private final Object[] old_garbage;

         private int old_index = 0;

         public Runner(int obj_size) {

             this.obj_size = obj_size;

             old_garbage = new Object[OLD_COUNT];

         }

         private void allocate_garbage() {

             byte[] garbage = new byte[obj_size];

             old_garbage[Math.abs(++old_index % OLD_COUNT)] = garbage;

         }

         @Override

         public void run() {

             try {

                 while (!isInterrupted()) {

                     allocate_garbage();

                     Thread.sleep(0); // Yield, to ensure interruptable.

                 }

             } catch (InterruptedException e) {

                 System.out.println("Aborted after "

                                    + (new Date().getTime() - startDate.getTime())

                                    + " ms");

                 interrupt();

             }

         }

     }

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

         HotSpotDiagnosticMXBean diagnostic = ManagementFactoryHelper.getDiagnosticMXBean();

         System.out.println("Max memory= " + MAX_MEMORY + " bytes");

         int obj_size = 0;

         long seconds_to_run = 0;

         if (args.length != 2) {

             throw new RuntimeException("Object size argument must be supplied");

         } else {

             obj_size = Integer.parseInt(args[0]);

             seconds_to_run = Integer.parseInt(args[1]);

         }

         System.out.println("Objects size= " + obj_size + " bytes");

         System.out.println("Seconds to run=" + seconds_to_run);

         int region_size =

             Integer.parseInt(diagnostic.getVMOption("G1HeapRegionSize").getValue());

         if (obj_size < (region_size / 2)) {

             throw new RuntimeException("Object size " + obj_size +

                                        " is not humongous with region size " + region_size);

         }

         ExecutorService executor =

             Executors.newFixedThreadPool(THREAD_COUNT, new NamedThreadFactory());

         System.out.println("Starting " + THREAD_COUNT + " threads");

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

             executor.execute(new Runner(obj_size));

         }

         Thread.sleep(seconds_to_run * 1000);

         executor.shutdownNow();

         if (!executor.awaitTermination(10, TimeUnit.SECONDS)) {

             System.err.println("Thread pool did not terminate after 10 seconds after shutdown");

         }

     }

     private static final long MAX_MEMORY = Runtime.getRuntime().maxMemory();

     private static final int OLD_COUNT = 4;

     private static final int THREAD_COUNT = 12;

     private static final String THREAD_NAME = "TestGreyRH-";

 }