anchor.diff:  
   -behaviour(application).
   -export([start/2, prep_stop/1, stop/1]).
  +-export([check_kv_health/1]).
   
   -define(SERVICES, [{riak_kv_pb_object, 3, 6}, %% ClientID stuff
                      {riak_kv_pb_object, 9, 14}, %% Object requests
  
positive.code:             %% synchronously.
              riak_core:register(riak_kv, [
                  {vnode_module, riak_kv_vnode},
                  {bucket_validator, riak_kv_bucket},
                  {stat_mod, riak_kv_stat}
              ]),
  
negative.code:                 "but your system says the epoch is ~p", [Epoch]),
              ok
      end.
  
  check_kv_health(_Pid) ->
      VNodes = riak_core_vnode_manager:all_index_pid(riak_kv_vnode),
      Threshold = app_helper:get_env(riak_kv, vnode_mailbox_limit, 5000),
      SlowVNs =
          [{Idx,Len} || {Idx, Pid} <- VNodes,
                        {message_queue_len, Len} <- process_info(Pid, [message_queue_len]),
                        Len > Threshold],
      SlowVNs =:= [].
  