public void populateData0to60k() {
    final byte[] value = new byte[ENTRY_SIZE];
    Arrays.fill(value, (byte) 77);
    for (int i = 0; i < 60000; i++) {
      region.put("" + i, value);
      // System.out.println(i);
    }
    System.out.println(" done with putting first 60k entries");
  }
OP_COUNT can be increased/decrease as per the requirement. If required to be set as higher
value such as 1000000, one needs to set the VM heap size accordingly. (For example:Default
setting in build.xml is <jvmarg value="-Xmx256M"/>
geode-core/src/integrationTest/java/org/apache/geode/internal/cache/diskPerf/DiskRegionRollOpLogJUnitPerformanceTest.java