Erlang - 进程太多了

Question

这是我在Erlang中的第一步,很抱歉这个新手问题:)我正在为每个Redis请求产生一个新的Erlang进程,这不是我想要的(32k Erlang进程中的"太多进程")但是如何限制例如最大的过程量 16？

-module(queue_manager).
-export([add_ids/0, add_id/2]).

add_ids() ->
    {ok, Client} = eredis:start_link(),
    do_spawn(Client, lists:seq(1,100000)).

do_spawn(Client, [H|T]) ->
    Pid = spawn(?MODULE, add_id, [Client, H]),
    do_spawn(Client, T);

do_spawn(_, []) -> none.

add_id(C, Id) ->
    {ok, _} = eredis:q(C, ["SADD", "todo_queue", Id]).

Answer 1

尝试使用Erlang pg2模块.它允许您轻松创建进程组并提供API以获取组中"最接近"(或随机)的PID.

以下是eredis客户端进程组的示例:

-module(redis_pg).

-export([create/1,
         add_connections/1, 
         connection/0,
         connections/0,
         q/1]).

create(Count) ->
    % create process group using the module name as the reference
    pg2:create(?MODULE),
    add_connections(Count).

% recursive helper for adding +Count+ connections
add_connections(Count) when Count > 0 ->
    ok = add_connection(),
    add_connections(Count - 1);
add_connections(_Count) -> 
    ok.

add_connection() ->
    % start redis client connection
    {ok, RedisPid} = eredis:start_link(),
    % join the redis connection PID to the process group
    pg2:join(?MODULE, RedisPid).

connection() ->
    % get a random redis connection PID
    pg2:get_closest_pid(?MODULE).

connections() ->
    % get all redis connection PIDs in the group
    pg2:get_members(?MODULE).

q(Argv) ->
    % execute redis command +Argv+ using random connection
    eredis:q(connection(), Argv).

以下是上述模块的示例:

1> redis_pg:create(16).
ok
2> redis_pg:connection().
<0.68.0>
3> redis_pg:connection().
<0.69.0>
4> redis_pg:connections().
[<0.53.0>,<0.56.0>,<0.57.0>,<0.58.0>,<0.59.0>,<0.60.0>,
 <0.61.0>,<0.62.0>,<0.63.0>,<0.64.0>,<0.65.0>,<0.66.0>,
 <0.67.0>,<0.68.0>,<0.69.0>,<0.70.0>]
5> redis_pg:q(["PING"]).  
{ok,<<"PONG">>}