hotspot/test/gc/g1/TestG1TraceEagerReclaimHumongousObjects.java

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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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/*
 * @test TestG1TraceEagerReclaimHumongousObjects
 * @bug 8058801 8048179
 * @summary Ensure that the output for a G1TraceEagerReclaimHumongousObjects
 * includes the expected necessary messages.
 * @key gc
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 *          java.management
 */

import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import java.util.LinkedList;

public class TestG1TraceEagerReclaimHumongousObjects {
  public static void main(String[] args) throws Exception {
    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-XX:+UseG1GC",
                                               "-Xms128M",
                                               "-Xmx128M",
                                               "-Xmn16M",
                                               "-XX:G1HeapRegionSize=1M",
                                               "-Xlog:gc+phases=trace,gc+humongous=trace",
                                               "-XX:+UnlockExperimentalVMOptions",
                                               GCWithHumongousObjectTest.class.getName());

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

    // As G1ReclaimDeadHumongousObjectsAtYoungGC is set(default), below logs should be displayed.
    output.shouldContain("Humongous Reclaim");
    output.shouldContain("Humongous Total");
    output.shouldContain("Humongous Candidate");
    output.shouldContain("Humongous Reclaimed");

    // As G1TraceReclaimDeadHumongousObjectsAtYoungGC is set and GCWithHumongousObjectTest has humongous objects,
    // these logs should be displayed.
    output.shouldContain("Live humongous");
    output.shouldContain("Dead humongous region");
    output.shouldHaveExitValue(0);
  }

  static class GCWithHumongousObjectTest {

    public static final int M = 1024*1024;
    public static LinkedList<Object> garbageList = new LinkedList<Object>();
    // A large object referenced by a static.
    static int[] filler = new int[10 * M];

    public static void genGarbage() {
      for (int i = 0; i < 32*1024; i++) {
        garbageList.add(new int[100]);
      }
      garbageList.clear();
    }

    public static void main(String[] args) {

      int[] large = new int[M];
      Object ref = large;

      System.out.println("Creating garbage");
      for (int i = 0; i < 100; i++) {
        // A large object that will be reclaimed eagerly.
        large = new int[6*M];
        genGarbage();
        // Make sure that the compiler cannot completely remove
        // the allocation of the large object until here.
        System.out.println(large);
      }

      // Keep the reference to the first object alive.
      System.out.println(ref);
      System.out.println("Done");
    }
  }
}