test/hotspot/jtreg/gc/g1/TestOneEdenRegionAfterGC.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
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 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * 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).
 *
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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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 */

package gc.g1;

/*
 * @test
 * @bug 8297186
 * @requires vm.gc.G1
 * @library /test/lib
 * @run driver gc.g1.TestOneEdenRegionAfterGC
 * @summary Test that on a very small heap g1 with very little data (smaller than region size)
 *          will use at least one eden region after gc to avoid full gcs.
 */

import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;

public class TestOneEdenRegionAfterGC {
  private static long YoungGenSize = 32 * 1024 * 1024;

  private static OutputAnalyzer run() throws Exception {
    return ProcessTools.executeLimitedTestJava(
      "-Xbootclasspath/a:.",
      "-Xmn" + YoungGenSize,
      "-Xmx512M",
      "-Xms512M",
      "-XX:G1HeapRegionSize=32M",
      "-XX:+UseG1GC",
      "-Xlog:gc,gc+ergo*=trace",
      TestOneEdenRegionAfterGC.Allocate.class.getName(),
      "" + YoungGenSize);
  }

  public static void main(String args[]) throws Exception {
    OutputAnalyzer out = run();

    out.shouldMatch(".*Pause Young \\(Normal\\).*");
    out.shouldNotMatch(".*Pause Full.*");
  }

  public static class Allocate {
    public static Object dummy;

    public static void main(String [] args) throws Exception {
      if (args.length != 1) {
        throw new IllegalArgumentException("Usage: <YoungGenSize>");
      }

      long youngGenSize = Long.parseLong(args[0]);
      triggerYoungGCs(youngGenSize);
    }

    public static void triggerYoungGCs(long youngGenSize) {
      long approxAllocSize = 32 * 1024;
      long numAllocations  = 2 * youngGenSize / approxAllocSize;

      for (long i = 0; i < numAllocations; i++) {
        dummy = new byte[(int)approxAllocSize];
      }
    }
  }
}