protected RpcHandler getHandler(final String name, final double handlerFailureThreshhold,
    final int handlerCount, final BlockingQueue<CallRunner> q,
    final AtomicInteger activeHandlerCount, final AtomicInteger failedHandlerCount,
    final Abortable abortable) {
    return new RpcHandler(name, handlerFailureThreshhold, handlerCount, q, activeHandlerCount,
      failedHandlerCount, abortable);
  }
Override if providing alternate Handler implementation.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcExecutor.java