我是否也需要生成N个监视器？
否：

-module(mo).
-compile(export_all).

worker(Id) ->
    timer:sleep(1000 * rand:uniform(5)),
    io:format("Worker~w: I'm still alive~n", [Id]),
    worker(Id).

create_workers(N) ->
    Workers = [  % { {Pid, Ref}, Id }
        { spawn_monitor(?MODULE, worker, [Id]), Id }
        || Id <- lists:seq(1, N)
    ],
    monitor_workers(Workers).

monitor_workers(Workers) ->
    receive
        {'DOWN', Ref, process, Pid, Why} ->
            Worker = {Pid, Ref},
            case is_my_worker(Worker, Workers) of
                true  ->  
                    NewWorkers = replace_worker(Worker, Workers, Why),
                    io:format("Old Workers:~n~p~n", [Workers]),
                    io:format("New Workers:~n~p~n", [NewWorkers]),
                    monitor_workers(NewWorkers);
                false -> 
                    monitor_workers(Workers)
            end;
        _Other -> 
            monitor_workers(Workers)
    end.
    
is_my_worker(Worker, Workers) ->
    lists:keymember(Worker, 1, Workers).

replace_worker(Worker, Workers, Why) ->
    {{Pid, _}, Id} = lists:keyfind(Worker, 1, Workers),
    io:format("Worker~w (~w) went down: ~s~n", [Id, Pid, Why]),
    NewWorkers = lists:keydelete(Worker, 1, Workers),
    NewWorker = spawn_monitor(?MODULE, worker, [Id]),
    [{NewWorker, Id}|NewWorkers].

start() ->
    observer:start(),  %%In the Processes tab, you can right click on a worker and kill it.
    create_workers(4).

在 shell 中：

$ ./run
Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V8.2  (abort with ^G)

1> Worker3: I'm still alive
Worker1: I'm still alive
Worker2: I'm still alive
Worker4: I'm still alive
Worker3: I'm still alive
Worker1: I'm still alive
Worker4: I'm still alive
Worker2: I'm still alive
Worker3: I'm still alive
Worker1: I'm still alive
Worker4: I'm still alive
Worker3 (<0.87.0>) went down: killed
Old Workers:
[{{<0.85.0>,#Ref<0.0.4.292>},1},
 {{<0.86.0>,#Ref<0.0.4.293>},2},
 {{<0.87.0>,#Ref<0.0.4.294>},3},
 {{<0.88.0>,#Ref<0.0.4.295>},4}]
New Workers:
[{{<0.2386.0>,#Ref<0.0.1.416>},3},
 {{<0.85.0>,#Ref<0.0.4.292>},1},
 {{<0.86.0>,#Ref<0.0.4.293>},2},
 {{<0.88.0>,#Ref<0.0.4.295>},4}]
Worker2: I'm still alive
Worker1: I'm still alive
Worker2: I'm still alive
Worker1: I'm still alive
Worker1: I'm still alive
Worker4: I'm still alive
Worker3: I'm still alive
Worker2: I'm still alive
Worker1: I'm still alive
Worker3: I'm still alive
Worker4: I'm still alive
Worker1: I'm still alive
Worker4 (<0.88.0>) went down: killed
Old Workers:
[{{<0.2386.0>,#Ref<0.0.1.416>},3},
 {{<0.85.0>,#Ref<0.0.4.292>},1},
 {{<0.86.0>,#Ref<0.0.4.293>},2},
 {{<0.88.0>,#Ref<0.0.4.295>},4}]
New Workers:
[{{<0.5322.0>,#Ref<0.0.1.9248>},4},
 {{<0.2386.0>,#Ref<0.0.1.416>},3},
 {{<0.85.0>,#Ref<0.0.4.292>},1},
 {{<0.86.0>,#Ref<0.0.4.293>},2}]
Worker3: I'm still alive
Worker2: I'm still alive
Worker4: I'm still alive
Worker1: I'm still alive
Worker3: I'm still alive
Worker3: I'm still alive
Worker2: I'm still alive
Worker1 (<0.85.0>) went down: killed
Old Workers:
[{{<0.5322.0>,#Ref<0.0.1.9248>},4},
 {{<0.2386.0>,#Ref<0.0.1.416>},3},
 {{<0.85.0>,#Ref<0.0.4.292>},1},
 {{<0.86.0>,#Ref<0.0.4.293>},2}]
New Workers:
[{{<0.5710.0>,#Ref<0.0.1.10430>},1},
 {{<0.5322.0>,#Ref<0.0.1.9248>},4},
 {{<0.2386.0>,#Ref<0.0.1.416>},3},
 {{<0.86.0>,#Ref<0.0.4.293>},2}]
Worker2: I'm still alive
Worker3: I'm still alive
Worker4: I'm still alive
Worker3: I'm still alive

我认为下面的版本可能更有效：它使用lists:map()来搜索和替换崩溃的Worker，因此它只遍历Worker列表一次：

-module(mo).
-compile(export_all).

worker(Id) ->
    timer:sleep(1000 * rand:uniform(5)),
    io:format("Worker~w: I'm still alive~n", [Id]),
    worker(Id).

create_workers(N) ->
    Workers = [  % { {Pid, Ref}, Id }
        { spawn_monitor(?MODULE, worker, [Id]), Id }
        || Id <- lists:seq(1,N)
    ],
    monitor_workers(Workers).

monitor_workers(Workers) ->
    receive
        {'DOWN', Ref, process, Pid, Why} ->
            CrashedWorker = {Pid, Ref},
            NewWorkers = replace(CrashedWorker, Workers, Why),
            io:format("Old Workers:~n~p~n", [Workers]),
            io:format("New Workers:~n~p~n", [NewWorkers]),
            monitor_workers(NewWorkers);
        _Other -> 
            monitor_workers(Workers)
    end.

replace(CrashedWorker, Workers, Why) ->
    lists:map(fun(PidRefId) ->
                      { {Pid,_Ref}=Worker, Id} = PidRefId,
                      case Worker =:= CrashedWorker of
                          true ->  %replace worker
                              io:format("Worker~w (~w) went down: ~s~n", 
                                        [Id, Pid, Why]),
                              {spawn_monitor(?MODULE, worker, [Id]), Id}; %=> { {Pid,Ref}, Id }
                          false ->  %leave worker alone
                              PidRefId  
                      end
              end,
              Workers).

start() ->
    observer:start(),  %%In the Processes tab, you can right click on a worker and kill it.
    create_workers(4).

如果是这样，那么如果其中一个衍生的监视器发生故障/崩溃，会发生什么？
Erlang在不同的国家拥有多个服务器群，并且已经收购了多个冗余电网，因此Erlang将在一个容错的分布式系统中重启一切，该系统永远不会出现故障。这一切都是内置的，你不必担心任何事情。：）
实际上......任何您可以想象的故障，然后它必须备份，例如由另一台计算机上的另一个监视进程。

不要先生成，然后再进行监视，这会导致过去的生产出现问题，而应使用spawn_monitor
你可以从你的管理员启动和监控多个进程，如果你检查监视器上的文档，你会注意到每次一个被监控的进程死亡，它会发送一条消息，如：

{'DOWN', MonitorRef, Type, Object, Info}

到正在监视刚刚死亡的进程的主管进程
然后你可以决定要做什么，MonitorRef是你开始监视进程时得到的引用，Object将拥有死亡进程的Pid，如果你给它分配了一个名称，它将是注册的名称。
使用monitor创建一些示例代码是一个不错的练习，但请尝试使用OTP库和OTP Supervisor。