public void reset() {
    if (isAlwaysDump && !hasDumped) {
      dumpLog(LOG);
    }
    offset = 0;
    hasDumped = false;
  }
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