@Override
  public void postCreateTable(ObserverContext<MasterCoprocessorEnvironment> ctx,
    TableDescriptor desc, RegionInfo[] regions) throws IOException {
    if (this.createTableStartTime > 0) {
      long time = EnvironmentEdgeManager.currentTime() - this.createTableStartTime;
      LOG.info("Create table took: " + time);

      // Update the timer metric for the create table operation duration.
      createTableTimer.updateMillis(time);
    }
  }
Returns the max memory of the process. We will use this to define a gauge metric
hbase-examples/src/main/java/org/apache/hadoop/hbase/coprocessor/example/ExampleMasterObserverWithMetrics.java