@Override
  protected void deleteFiles() {
    for (int i = 0; i < 4; i++) {
      File[] files = dirs[i].listFiles();
      for (final File file : files) {
        file.delete();
      }
    }
  }
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