Packages
rabbit_common
4.2.0
4.2.1
4.2.0
retired
4.2.0-rc.1
retired
4.1.6
4.1.5
retired
4.1.5-rc.2
retired
4.1.5-rc.1
4.0.3
4.0.3-rc.1
4.0.2
4.0.2-rc.2
4.0.2-rc.1
4.0.1
4.0.0
4.0.0-rc.2
4.0.0-rc.1
3.13.7
3.13.6
3.13.5
3.13.4
3.13.3
3.13.2
3.13.2-rc.1
3.13.1
3.13.0
3.13.0-rc.6
3.13.0-rc.5
3.13.0-rc.4
3.13.0-rc.3
3.13.0-rc.2
3.13.0-rc.1
3.12.14
3.12.13
3.12.12
3.12.11
3.12.10
3.12.9
3.12.8
3.12.7
3.12.6
3.12.5
3.12.4
3.12.3
3.12.2
3.12.1
3.12.0
3.12.0-rc.4
3.12.0-rc.3
3.12.0-rc.2
3.12.0-rc.1
3.11.28
3.11.27
3.11.26
3.11.25
3.11.24
3.11.23
3.11.22
3.11.21
3.11.20
3.11.19
3.11.18
3.11.17
3.11.16
3.11.15
3.11.14
3.11.13
3.11.12
3.11.11
3.11.10
3.11.9
3.11.8
3.11.7
3.11.6
3.11.5
3.11.4
3.11.3
3.11.2
3.11.1
3.11.0
3.11.0-rc.2
3.11.0-rc.1
3.11.0-1
3.10.25
3.10.24
3.10.23
3.10.22
3.10.21
3.10.20
3.10.19
3.10.18
3.10.17
3.10.16
3.10.15
3.10.14
3.10.13
3.10.12
3.10.11
3.10.10
3.10.9
3.10.8
3.10.7
3.10.6
3.10.5
3.10.4
3.10.3
3.10.2
3.10.1
3.10.0
3.10.0-rc.6
3.10.0-rc.5
3.9.29
3.9.28
3.9.27
3.9.26
3.9.25
3.9.24
3.9.23
3.9.22
3.9.21
3.9.20
3.9.19
3.9.18
3.9.17
3.9.16
3.9.15
3.9.11
3.9.10
3.9.9
3.9.8
3.9.7
3.9.6
3.9.5
3.9.4
3.9.3
3.9.2
3.9.1
3.8.35
3.8.34
3.8.33
3.8.32
3.8.31
3.8.30
3.8.26
3.8.25
3.8.24
3.8.23
3.8.22
3.8.21
3.8.20
3.8.19
3.8.14
3.8.12-rc.3
3.8.12-rc.2
3.8.12-rc.1
3.8.11
3.8.10
3.8.10-rc.6
3.8.10-rc.5
3.8.10-rc.1
3.8.9
3.8.8
3.8.7
3.8.6
3.8.6-rc.2
3.8.6-rc.1
3.8.5
3.8.5-rc.2
3.8.5-rc.1
3.8.4
3.8.4-rc.3
3.8.4-rc.1
3.8.3
3.8.3-rc.2
3.8.3-rc.1
3.8.2
3.8.2-rc.1
3.8.1
3.8.1-rc.1
3.8.0
3.8.0-rc.3
3.8.0-rc.2
3.8.0-rc.1
3.7.28
3.7.27
3.7.27-rc.2
3.7.27-rc.1
3.7.26
3.7.25
3.7.25-rc.1
3.7.24
3.7.24-rc.2
3.7.24-rc.1
3.7.23
3.7.23-rc.1
3.7.22
3.7.22-rc.2
3.7.22-rc.1
3.7.21
3.7.20
3.7.20-rc.2
3.7.20-rc.1
3.7.19
3.7.18
3.7.18-rc.1
3.7.17
3.7.17-rc.3
3.7.17-rc.2
3.7.17-rc.1
retired
3.7.16
retired
3.7.16-rc.4
retired
3.7.16-rc.3
retired
3.7.16-rc.2
retired
3.7.16-rc.1
retired
3.7.16-beta.1
3.7.15
3.7.14
3.7.14-rc.2
3.7.14-rc.1
3.7.13
3.7.13-rc.2
3.7.13-rc.1
3.7.12
3.7.12-rc.2
3.7.12-rc.1
3.7.11
3.7.11-rc.2
3.7.11-rc.1
3.7.10-rc.4
3.7.10-rc.3
3.7.10-rc.2
3.7.10-rc.1
3.7.9
3.7.9-rc.3
3.7.9-rc.2
3.7.8
3.7.8-rc.4
3.7.8-rc.3
3.7.8-rc.2
3.7.8-rc.1
3.7.7
3.7.7-rc.2
3.7.7-rc.1
3.7.6
3.7.6-rc.2
3.7.6-rc.1
3.7.5
3.7.5-rc.1
3.7.4
3.7.4-rc.4
3.7.4-rc.3
3.7.4-rc.2
3.7.4-rc.1
3.7.3
3.7.3-rc.2
3.7.3-rc.1
3.7.2
3.7.1
3.7.0-rc.2
3.7.0-alpha.544
3.7.0-alpha.542
3.6.16
3.6.16-rc.1
3.6.15
3.6.15-rc.1
3.6.14
3.6.13
3.6.12
3.6.11
3.6.10
3.6.9
3.6.8
3.6.7
3.6.7-pre.1
3.5.6
3.5.0
3.4.0
3.3.5
3.0.2
0.0.0-rc.1
Modules shared by rabbitmq-server and rabbitmq-erlang-client
Retired package: Release invalid - invalid
Current section
Files
Jump to
Current section
Files
src/worker_pool.erl
%% This Source Code Form is subject to the terms of the Mozilla Public
%% License, v. 2.0. If a copy of the MPL was not distributed with this
%% file, You can obtain one at https://mozilla.org/MPL/2.0/.
%%
%% Copyright (c) 2007-2025 Broadcom. All Rights Reserved. The term “Broadcom” refers to Broadcom Inc. and/or its subsidiaries. All rights reserved.
%%
-module(worker_pool).
%% Generic worker pool manager.
%%
%% Submitted jobs are functions. They can be executed synchronously
%% (using worker_pool:submit/1, worker_pool:submit/2) or asynchronously
%% (using worker_pool:submit_async/1).
%%
%% We typically use the worker pool if we want to limit the maximum
%% parallelism of some job. We are not trying to dodge the cost of
%% creating Erlang processes.
%%
%% Supports nested submission of jobs and two execution modes:
%% 'single' and 'reuse'. Jobs executed in 'single' mode are invoked in
%% a one-off process. Those executed in 'reuse' mode are invoked in a
%% worker process out of the pool. Nested jobs are always executed
%% immediately in current worker process.
%%
%% 'single' mode is offered to work around a bug in Mnesia: after
%% network partitions reply messages for prior failed requests can be
%% sent to Mnesia clients - a reused worker pool process can crash on
%% receiving one.
%%
%% Caller submissions are enqueued internally. When the next worker
%% process is available, it communicates it to the pool and is
%% assigned a job to execute. If job execution fails with an error, no
%% response is returned to the caller.
%%
%% Worker processes prioritise certain command-and-control messages
%% from the pool.
%%
%% Future improvement points: job prioritisation.
-behaviour(gen_server2).
-export([start_link/1,
submit/1, submit/2, submit/3,
submit_async/1, submit_async/2,
dispatch_sync/1, dispatch_sync/2,
ready/2,
idle/2,
default_pool/0]).
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
%%----------------------------------------------------------------------------
-type mfargs() :: {atom(), atom(), [any()]}.
-spec start_link(atom()) -> {'ok', pid()} | {'error', any()}.
-spec submit(fun (() -> A) | mfargs()) -> A.
-spec submit(fun (() -> A) | mfargs(), 'reuse' | 'single') -> A.
-spec submit(atom(), fun (() -> A) | mfargs(), 'reuse' | 'single') -> A.
-spec submit_async(fun (() -> any()) | mfargs()) -> 'ok'.
-spec dispatch_sync(fun(() -> any()) | mfargs()) -> 'ok'.
-spec ready(atom(), pid()) -> 'ok'.
-spec idle(atom(), pid()) -> 'ok'.
-spec default_pool() -> atom().
%%----------------------------------------------------------------------------
-define(DEFAULT_POOL, ?MODULE).
-define(HIBERNATE_AFTER_MIN, 1000).
-define(DESIRED_HIBERNATE, 10000).
-record(state, { available, pending }).
%%----------------------------------------------------------------------------
start_link(Name) -> gen_server2:start_link({local, Name}, ?MODULE, [],
[{timeout, infinity}]).
submit(Fun) ->
submit(?DEFAULT_POOL, Fun, reuse).
%% ProcessModel =:= single is for working around the mnesia_locker bug.
submit(Fun, ProcessModel) ->
submit(?DEFAULT_POOL, Fun, ProcessModel).
submit(Server, Fun, ProcessModel) ->
case get(worker_pool_worker) of
true -> worker_pool_worker:run(Fun);
_ -> Pid = gen_server2:call(Server, {next_free, self()}, infinity),
worker_pool_worker:submit(Pid, Fun, ProcessModel)
end.
submit_async(Fun) -> submit_async(?DEFAULT_POOL, Fun).
submit_async(Server, Fun) -> gen_server2:cast(Server, {run_async, Fun}).
dispatch_sync(Fun) ->
dispatch_sync(?DEFAULT_POOL, Fun).
dispatch_sync(Server, Fun) ->
Pid = gen_server2:call(Server, {next_free, self()}, infinity),
worker_pool_worker:submit_async(Pid, Fun).
ready(Server, WPid) -> gen_server2:cast(Server, {ready, WPid}).
idle(Server, WPid) -> gen_server2:cast(Server, {idle, WPid}).
default_pool() -> ?DEFAULT_POOL.
%%----------------------------------------------------------------------------
init([]) ->
{ok, #state { pending = queue:new(), available = ordsets:new() }, hibernate,
{backoff, ?HIBERNATE_AFTER_MIN, ?HIBERNATE_AFTER_MIN, ?DESIRED_HIBERNATE}}.
handle_call({next_free, CPid}, From, State = #state { available = [],
pending = Pending }) ->
{noreply, State#state{pending = queue:in({next_free, From, CPid}, Pending)},
hibernate};
handle_call({next_free, CPid}, _From, State = #state { available =
[WPid | Avail1] }) ->
worker_pool_worker:next_job_from(WPid, CPid),
{reply, WPid, State #state { available = Avail1 }, hibernate};
handle_call(Msg, _From, State) ->
{stop, {unexpected_call, Msg}, State}.
handle_cast({ready, WPid}, State) ->
erlang:monitor(process, WPid),
handle_cast({idle, WPid}, State);
handle_cast({idle, WPid}, State = #state { available = Avail,
pending = Pending }) ->
{noreply,
case queue:out(Pending) of
{empty, _Pending} ->
State #state { available = ordsets:add_element(WPid, Avail) };
{{value, {next_free, From, CPid}}, Pending1} ->
worker_pool_worker:next_job_from(WPid, CPid),
gen_server2:reply(From, WPid),
State #state { pending = Pending1 };
{{value, {run_async, Fun}}, Pending1} ->
worker_pool_worker:submit_async(WPid, Fun),
State #state { pending = Pending1 }
end, hibernate};
handle_cast({run_async, Fun}, State = #state { available = [],
pending = Pending }) ->
{noreply, State #state { pending = queue:in({run_async, Fun}, Pending)},
hibernate};
handle_cast({run_async, Fun}, State = #state { available = [WPid | Avail1] }) ->
worker_pool_worker:submit_async(WPid, Fun),
{noreply, State #state { available = Avail1 }, hibernate};
handle_cast(Msg, State) ->
{stop, {unexpected_cast, Msg}, State}.
handle_info({'DOWN', _MRef, process, WPid, _Reason},
State = #state { available = Avail }) ->
{noreply, State #state { available = ordsets:del_element(WPid, Avail) },
hibernate};
handle_info(Msg, State) ->
{stop, {unexpected_info, Msg}, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
terminate(_Reason, State) ->
State.