private void insert(int num) {
    for (int i = 1; i <= num; i++) {
      list.add(i);
    }
  }
This tests concurrent modification of IndexElemArray and to make sure elementData and size are
updated atomically. Ticket# GEODE-106.
geode-core/src/test/java/org/apache/geode/cache/query/internal/index/IndexElemArrayJUnitTest.java