protected void push(final Procedure procedure, final boolean addFront, final boolean notify) {
    schedLock();
    try {
      enqueue(procedure, addFront);
      if (notify) {
        schedWaitCond.signal();
      }
    } finally {
      schedUnlock();
    }
  }
Add the procedure to the queue. NOTE: this method is called with the sched lock held.
@param procedure the Procedure to add
@param addFront  true if the item should be added to the front of the queue
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/AbstractProcedureScheduler.java