My phoenix application is getting error something after upgrading to OTP 21 and elixir 1.6.6 like this…
[error] Task #PID<0.834.0> started from #PID<0.820.0> terminating
** (stop) exited in: :gen_server.call(#PID<0.599.0>, {:checkout, #Reference<0.650802346.705167363.77758>, true, 15000}, 5000)
** (EXIT) time out
(db_connection) lib/db_connection/poolboy.ex:112: DBConnection.Poolboy.checkout/3
(db_connection) lib/db_connection.ex:928: DBConnection.checkout/2
(db_connection) lib/db_connection.ex:750: DBConnection.run/3
(db_connection) lib/db_connection.ex:644: DBConnection.execute/4
(ecto) lib/ecto/adapters/postgres/connection.ex:98: Ecto.Adapters.Postgres.Connection.execute/4
(ecto) lib/ecto/adapters/sql.ex:256: Ecto.Adapters.SQL.sql_call/6
(ecto) lib/ecto/adapters/sql.ex:436: Ecto.Adapters.SQL.execute_or_reset/7
(ecto) lib/ecto/repo/queryable.ex:133: Ecto.Repo.Queryable.execute/5
(ecto) lib/ecto/repo/queryable.ex:37: Ecto.Repo.Queryable.all/4
(ecto) lib/ecto/repo/preloader.ex:182: Ecto.Repo.Preloader.fetch_query/8
(ecto) lib/ecto/repo/preloader.ex:119: Ecto.Repo.Preloader.preload_assoc/10
(elixir) lib/task/supervised.ex:88: Task.Supervised.do_apply/2
(elixir) lib/task/supervised.ex:38: Task.Supervised.reply/5
(stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
Function: &:erlang.apply/2
Args: [#Function<11.21914290/2 in Ecto.Repo.Preloader.preload_each/4>, [{{:assoc, %Ecto.Association.Has{cardinality: :many, defaults: [], field: :phonebooks, on_cast: nil, on_delete: :nothing, on_replace: :raise, owner: Texting.Account.User, owner_key: :id, queryable: Texting.Contact.Phonebook, related: Texting.Contact.Phonebook, related_key: :user_id, relationship: :child, unique: true}, {0, :user_id}}, nil, nil, []}, [caller: #PID<0.820.0>]]]
[error] Ranch protocol #PID<0.820.0> of listener TextingWeb.Endpoint.HTTP (cowboy_protocol) terminated
** (exit) exited in: :gen_server.call(#PID<0.599.0>, {:checkout, #Reference<0.650802346.705167363.77758>, true, 15000}, 5000)
** (EXIT) time out
while I am browsing my phoenix app, get this error and sometimes works but very slow and keeps getting this error in debug console.