public void start() {
    Preconditions.checkState(monitorThread == null, "Already started");
    monitorThread = new Thread(new Monitor(), "JvmPauseMonitor");
    monitorThread.setDaemon(true);
    monitorThread.start();
  }
log INFO if we detect a pause longer than this threshold
hbase-server/src/main/java/org/apache/hadoop/hbase/util/JvmPauseMonitor.java