private void logRange(DiskRange range, int currentOffset) {
    log[currentOffset] = range.getOffset();
    log[currentOffset + 1] = range.getEnd();
    log[currentOffset + 2] = range.hasData() ? System.identityHashCode(range.getData()) : 0;
  }
Single threaded IO trace.
Note: this can be made MTT merely by using an AtomicInteger, and storing a thread ID.
ql/src/java/org/apache/hadoop/hive/ql/io/orc/encoded/IoTrace.java