@Override
  public void enforceMutex(boolean enableMutex) {
    this.shouldUseMutex = enableMutex;
  }
A class to initiate compactions.  This will run in a separate thread.
It's critical that there exactly 1 of these in a given warehouse.
ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/Initiator.java