pooler - An OTP Process Pool Application

Authors: Seth Falcon (seth@userprimary.net).

The pooler application allows you to manage pools of OTP behaviors such as gen_servers, gen_fsms, or supervisors, and provide consumers with exclusive access to pool members using pooler:take_member.

See the README.org file for a good introduction to what pooler is all about.

Pooler Configuration

Pool configuration is specified in the pooler application's environment. This can be provided in a config file using -config or set at startup using application:set_env(pooler, pools, Pools). Here's an example config file that creates three pools of Riak pb clients each talking to a different node in a local cluster:

% pooler.config
% Start Erlang as: erl -config pooler
% -*- mode: erlang -*-
% pooler app config
[
 {pooler, [
         {pools, [
                  [{name, "rc8081"},
                   {max_count, 5},
                   {init_count, 2},
                   {start_mfa,
                    {riakc_pb_socket, start_link, ["localhost", 8081]}}],

                  [{name, "rc8082"},
                   {max_count, 5},
                   {init_count, 2},
                   {start_mfa,
                    {riakc_pb_socket, start_link, ["localhost", 8082]}}],

                  [{name, "rc8083"},
                   {max_count, 5},
                   {init_count, 2},
                   {start_mfa,
                    {riakc_pb_socket, start_link, ["localhost", 8083]}}]
                 ]}
        ]}
].

Using pooler

Here's an example session:

application:start(pooler).
P = pooler:take_member(),
% use P
pooler:return_member(P, ok).

Once started, the main interaction you will have with pooler is through two functions, take_member/0 and return_member/2.

Call pooler:take_member() to obtain a member from a randomly selected pool. When you are done with it, return it to the pool using pooler:return_member(Pid, ok). If you encountered an error using the member, you can pass fail as the second argument. In this case, pooler will permanently remove that member from the pool and start a new member to replace it. If your process is short lived, you can omit the call to return_member. In this case, pooler will detect the normal exit of the consumer and reclaim the member.

Generated by EDoc, Apr 17 2011, 16:02:59.