Erlang Connection/Client Pool Library
Erlang Makefile
Latest commit c637a98 Apr 12, 2016 @emqplus emqplus 0.2.1
Failed to load latest commit information.
src Spec Syntax Apr 12, 2016
test unit test Jan 2, 2016
.gitignore first commit Jan 1, 2016
CHANGES 0.2.1 Apr 12, 2016
LICENSE Initial commit Dec 30, 2015
Makefile first commit Jan 1, 2016 round_robin Jan 21, 2016
TODO first commit Jan 1, 2016
rebar first commit Jan 1, 2016
rebar.config first commit Jan 1, 2016

Erlang Connection/Client Pool

ecpool is different with worker-pool libraries in that it is designed to pool connection/clients to server or database.

ecpool tries to avoid the erlang application crash when the server or database going down.


A pool worker to manage/monitor the client to server or database:

PoolWorker -> Client -> DB

Use client:

ecpool:with_client(Pool, fun(Client) -> call(Client) end).


Start the pool

ecpool:start_pool(Pool, Mod, Opts).

For example:

PgOpts = [%% Pool Size
          {pool_size, 10},
          %% Pool Type: round_robin | random | hash
          {pool_type, round_robin},
          %% Auto reconnect
          {auto_reconnect, 3},

          %% epgsql opts
          {host, "localhost"},
          {port, 5432},
          {username, "feng"},
          {password, ""},
          {database, "mqtt"},
          {encoding,  utf8}],

ecpool:start_pool(epgsql_pool, epgsql_pool_client, PgOpts)

The Callback Module

Pool Worker Callback:

-callback connect(ConnOpts :: list()) -> {ok, pid()} | {error, any()}.

For example, epgsql_pool_client module:



connect(Opts) ->
    Host = proplists:get_value(host, Opts),
    Username = proplists:get_value(username, Opts),
    Password = proplists:get_value(password, Opts),
    epgsql:connect(Host, Username, Password, conn_opts(Opts)).

squery(Pool, Sql) ->
    ecpool:with_client(Pool, fun(Client) -> epgsql:squery(Client, Sql) end).


The ecpool supervisor tree:

pool_sup[one_for_all supervisor]
    worker_sup[one_for_one supervisor]
        worker1 -> connection1
        worker2 -> connection1


Feng Lee


The MIT License (MIT)