protected void createThread(ReplicaThread replicaThread, boolean startThread) {
    if (startThread) {
      Thread thread = Utils.newThread(replicaThread.getName(), replicaThread, false);
      thread.start();
      logger.info("Started replica thread {}", thread.getName());
    }
  }
Create thread pool for a datacenter.
@param datacenter The datacenter String.
@param numberOfThreads Number of threads to create for the thread pool.
@param startThread If thread needs to be started when create.
ambry-replication/src/main/java/com/github/ambry/replication/ReplicationEngine.java