private void setByte(long offset, byte value) {
    // No checks, the caller must ensure the offsets are correct.
    writeBuffers.get(getBufferIndex(offset))[getOffset(offset)] = value;
  }
THIS METHOD IS NOT THREAD-SAFE. Use only at load time (or be mindful of thread safety).
serde/src/java/org/apache/hadoop/hive/serde2/WriteBuffers.java