Потоки

-module(main).
-import(io,[fwrite/1]).
-export([start/0]).
 
start() ->
   fwrite("Hello, world!\n").
-module(main).
-export([star/2]).
 
-module(parent_children).
-export([start/1, send_to_child/2, stop/0]).
 
start(N) ->
    ParentPid = spawn_link(fun parent/0),
    Pids = [spawn_link(fun() -> child(ParentPid) end) || _ <- lists:seq(1, N)],
    ParentPid ! {init, Pids},
    ParentPid.
 
parent() ->
    receive
        {init, Pids} ->
            parent_loop(Pids)
    end.
 
parent_loop(Pids) ->
    receive
        {send_to_child, Index, Msg} ->
            case lists:nth(Index, Pids) of
                undefined ->
                    io:format("Invalid child index: ~p~n", [Index]);
                ChildPid ->
                    ChildPid ! Msg
            end,
            parent_loop(Pids);
        stop ->
            [Pid ! stop || Pid <- Pids];
        {'EXIT', ChildPid, _Reason} ->
            NewChildPid = spawn_link(fun() -> child(self()) end),
            NewPids = lists:keyreplace(ChildPid, 1, Pids, NewChildPid),
            io:format("Child process ~p exited. Restarted as ~p.~n", [ChildPid, NewChildPid]),
            parent_loop(NewPids)
    end.
 
child(Parent) ->
    process_flag(trap_exit, true),
    Parent ! {register, self()},
    child_loop().
 
child_loop() ->
    receive
        stop ->
            exit(normal);
        die ->
            exit({error, "Child process died"});
        Msg ->
            io:format("Child received message: ~p~n", [Msg]),
            child_loop()
    end.
 
send_to_child(ParentPid, Index, Msg) ->
    ParentPid ! {send_to_child, Index, Msg}.
 
stop(ParentPid) ->
    ParentPid ! stop.