private int allocateWithExpand(MemoryBuffer[] dest, int destIx,
      int freeListIx, int allocSize, int arenaCount) {
    for (int arenaIx = arenaCount; arenaIx < arenas.length; ++arenaIx) {
      destIx = arenas[arenaIx].allocateWithExpand(
          arenaIx, freeListIx, dest, destIx, allocSize);
      if (destIx == dest.length) return destIx;
    }
    return destIx;
  }
Tries to allocate destCount - destIx blocks by allocating new arenas, if needed. Same args
as allocateFast, except the allocations start at arenaCount (the first unallocated arena).
llap-server/src/java/org/apache/hadoop/hive/llap/cache/BuddyAllocator.java