From 6b969c5c84ea223d33d1a63a681e5bb014418c99 Mon Sep 17 00:00:00 2001 From: Thales Macedo Garitezi Date: Mon, 25 Apr 2022 18:22:07 -0300 Subject: [PATCH 1/3] fix(emqx_conf): avoid crash/deadlock depending on node startup order Depending on the order that a cluster of core nodes might be stopped and then restarted, there might be a deadlock or crash during the configuration loading. The nodes try to check with each other which has the latest cluster overrides and copy that info. However, in some cases, Mnesia on node A might still think that it needs to consult another node C that is still down, so that this node proceeds with its boot sequence but `mnesia:wait_for_tables` in `emqx_cluster_rpc` is stuck. Meanwhile, a node B can come up, try to copy from the sole online node A, and fail because it's not ready yet. --- apps/emqx_conf/src/emqx_cluster_rpc.erl | 25 +++ apps/emqx_conf/src/emqx_conf_app.erl | 166 ++++++++++----- apps/emqx_conf/test/emqx_conf_app_SUITE.erl | 222 ++++++++++++++++++++ 3 files changed, 355 insertions(+), 58 deletions(-) create mode 100644 apps/emqx_conf/test/emqx_conf_app_SUITE.erl diff --git a/apps/emqx_conf/src/emqx_cluster_rpc.erl b/apps/emqx_conf/src/emqx_cluster_rpc.erl index e3b824d75..5be474601 100644 --- a/apps/emqx_conf/src/emqx_cluster_rpc.erl +++ b/apps/emqx_conf/src/emqx_cluster_rpc.erl @@ -42,6 +42,8 @@ code_change/3 ]). +-export([get_tables_status/0]). + -export_type([txn_id/0, succeed_num/0, multicall_return/1, multicall_return/0]). -ifdef(TEST). @@ -172,6 +174,29 @@ get_node_tnx_id(Node) -> [#cluster_rpc_commit{tnx_id = TnxId}] -> TnxId end. +%% Checks whether the Mnesia tables used by this module are waiting to +%% be loaded and from where. +-spec get_tables_status() -> #{atom() => {waiting, [node()]} | {disc | network, node()}}. +get_tables_status() -> + maps:from_list([ + {Tab, do_get_tables_status(Tab)} + || Tab <- [?CLUSTER_COMMIT, ?CLUSTER_MFA] + ]). + +do_get_tables_status(Tab) -> + Props = mnesia:table_info(Tab, all), + TabNodes = proplists:get_value(all_nodes, Props), + KnownDown = mnesia_recover:get_mnesia_downs(), + LocalNode = node(), + case proplists:get_value(load_node, Props) of + unknown -> + {waiting, TabNodes -- [LocalNode | KnownDown]}; + LocalNode -> + {disc, LocalNode}; + Node -> + {network, Node} + end. + %% Regardless of what MFA is returned, consider it a success), %% then move to the next tnxId. %% if the next TnxId failed, need call the function again to skip. diff --git a/apps/emqx_conf/src/emqx_conf_app.erl b/apps/emqx_conf/src/emqx_conf_app.erl index 81d0481df..2115bc617 100644 --- a/apps/emqx_conf/src/emqx_conf_app.erl +++ b/apps/emqx_conf/src/emqx_conf_app.erl @@ -31,64 +31,6 @@ start(_StartType, _StartArgs) -> stop(_State) -> ok. -%% internal functions -init_conf() -> - {ok, TnxId} = copy_override_conf_from_core_node(), - emqx_app:set_init_tnx_id(TnxId), - emqx_config:init_load(emqx_conf:schema_module()), - emqx_app:set_init_config_load_done(). - -copy_override_conf_from_core_node() -> - case mria_mnesia:running_nodes() -- [node()] of - %% The first core nodes is self. - [] -> - ?SLOG(debug, #{msg => "skip_copy_overide_conf_from_core_node"}), - {ok, -1}; - Nodes -> - {Results, Failed} = emqx_conf_proto_v1:get_override_config_file(Nodes), - {Ready, NotReady0} = lists:partition(fun(Res) -> element(1, Res) =:= ok end, Results), - NotReady = lists:filter(fun(Res) -> element(1, Res) =:= error end, NotReady0), - case (Failed =/= [] orelse NotReady =/= []) andalso Ready =/= [] of - true -> - Warning = #{ - nodes => Nodes, - failed => Failed, - not_ready => NotReady, - msg => "ignored_bad_nodes_when_copy_init_config" - }, - ?SLOG(warning, Warning); - false -> - ok - end, - case Ready of - [] -> - %% Other core nodes running but no one replicated it successfully. - ?SLOG(error, #{ - msg => "copy_overide_conf_from_core_node_failed", - nodes => Nodes, - failed => Failed, - not_ready => NotReady - }), - {error, "core node not ready"}; - _ -> - SortFun = fun( - {ok, #{wall_clock := W1}}, - {ok, #{wall_clock := W2}} - ) -> - W1 > W2 - end, - [{ok, Info} | _] = lists:sort(SortFun, Ready), - #{node := Node, conf := RawOverrideConf, tnx_id := TnxId} = Info, - Msg = #{msg => "copy_overide_conf_from_core_node_success", node => Node}, - ?SLOG(debug, Msg), - ok = emqx_config:save_to_override_conf( - RawOverrideConf, - #{override_to => cluster} - ), - {ok, TnxId} - end - end. - get_override_config_file() -> Node = node(), Role = mria_rlog:role(), @@ -114,3 +56,111 @@ get_override_config_file() -> true when Role =:= replicant -> {ignore, #{node => Node}} end. + +%% ------------------------------------------------------------------------------ +%% Internal functions +%% ------------------------------------------------------------------------------ + +init_conf() -> + {ok, TnxId} = copy_override_conf_from_core_node(), + emqx_app:set_init_tnx_id(TnxId), + emqx_config:init_load(emqx_conf:schema_module()), + emqx_app:set_init_config_load_done(). + +cluster_nodes() -> + maps:get(running_nodes, ekka_cluster:info()) -- [node()]. + +copy_override_conf_from_core_node() -> + case cluster_nodes() of + %% The first core nodes is self. + [] -> + ?SLOG(debug, #{msg => "skip_copy_overide_conf_from_core_node"}), + {ok, ?DEFAULT_INIT_TXN_ID}; + Nodes -> + {Results, Failed} = emqx_conf_proto_v1:get_override_config_file(Nodes), + {Ready, NotReady0} = lists:partition(fun(Res) -> element(1, Res) =:= ok end, Results), + NotReady = lists:filter(fun(Res) -> element(1, Res) =:= error end, NotReady0), + case (Failed =/= [] orelse NotReady =/= []) andalso Ready =/= [] of + true -> + Warning = #{ + nodes => Nodes, + failed => Failed, + not_ready => NotReady, + msg => "ignored_bad_nodes_when_copy_init_config" + }, + ?SLOG(warning, Warning); + false -> + ok + end, + case Ready of + [] -> + %% Other core nodes running but no one replicated it successfully. + ?SLOG(error, #{ + msg => "copy_override_conf_from_core_node_failed", + nodes => Nodes, + failed => Failed, + not_ready => NotReady + }), + + case should_proceed_with_boot() of + true -> + %% Act as if this node is alone, so it can + %% finish the boot sequence and load the + %% config for other nodes to copy it. + ?SLOG(info, #{ + msg => "skip_copy_overide_conf_from_core_node", + loading_from_disk => true, + nodes => Nodes, + failed => Failed, + not_ready => NotReady + }), + {ok, ?DEFAULT_INIT_TXN_ID}; + false -> + %% retry in some time + Jitter = rand:uniform(2_000), + Timeout = 10_000 + Jitter, + ?SLOG(info, #{ + msg => "copy_overide_conf_from_core_node_retry", + timeout => Timeout, + nodes => Nodes, + failed => Failed, + not_ready => NotReady + }), + timer:sleep(Timeout), + copy_override_conf_from_core_node() + end; + _ -> + SortFun = fun( + {ok, #{wall_clock := W1}}, + {ok, #{wall_clock := W2}} + ) -> + W1 > W2 + end, + [{ok, Info} | _] = lists:sort(SortFun, Ready), + #{node := Node, conf := RawOverrideConf, tnx_id := TnxId} = Info, + Msg = #{ + msg => "copy_overide_conf_from_core_node_success", + node => Node + }, + ?SLOG(debug, Msg), + ok = emqx_config:save_to_override_conf( + RawOverrideConf, + #{override_to => cluster} + ), + {ok, TnxId} + end + end. + +should_proceed_with_boot() -> + TablesStatus = emqx_cluster_rpc:get_tables_status(), + LocalNode = node(), + case maps:get(?CLUSTER_COMMIT, TablesStatus) of + {disc, LocalNode} -> + %% Loading locally; let this node finish its boot sequence + %% so others can copy the config from this one. + true; + _ -> + %% Loading from another node or still waiting for nodes to + %% be up. Try again. + false + end. diff --git a/apps/emqx_conf/test/emqx_conf_app_SUITE.erl b/apps/emqx_conf/test/emqx_conf_app_SUITE.erl new file mode 100644 index 000000000..29b1404e8 --- /dev/null +++ b/apps/emqx_conf/test/emqx_conf_app_SUITE.erl @@ -0,0 +1,222 @@ +%%-------------------------------------------------------------------- +%% Copyright (c) 2022 EMQ Technologies Co., Ltd. All Rights Reserved. +%% +%% Licensed under the Apache License, Version 2.0 (the "License"); +%% you may not use this file except in compliance with the License. +%% You may obtain a copy of the License at +%% +%% http://www.apache.org/licenses/LICENSE-2.0 +%% +%% Unless required by applicable law or agreed to in writing, software +%% distributed under the License is distributed on an "AS IS" BASIS, +%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +%% See the License for the specific language governing permissions and +%% limitations under the License. +%%-------------------------------------------------------------------- + +-module(emqx_conf_app_SUITE). + +-compile(export_all). +-compile(nowarn_export_all). + +-include("emqx_conf.hrl"). +-include_lib("eunit/include/eunit.hrl"). +-include_lib("common_test/include/ct.hrl"). +-include_lib("snabbkaffe/include/snabbkaffe.hrl"). + +all() -> + emqx_common_test_helpers:all(?MODULE). + +t_copy_conf_override_on_restarts(_Config) -> + ct:timetrap({seconds, 120}), + snabbkaffe:fix_ct_logging(), + Cluster = cluster([core, core, core]), + try + %% 1. Start all nodes + Nodes = start_cluster(Cluster), + [join_cluster(Spec) || Spec <- Cluster], + assert_config_load_done(Nodes), + + %% 2. Stop each in order. + lists:foreach(fun stop_slave/1, Nodes), + + %% 3. Restart nodes in the same order. This should not + %% crash and eventually all nodes should be ready. + start_cluster_async(Cluster), + + timer:sleep(15_000), + + assert_config_load_done(Nodes), + + ok + after + teardown_cluster(Cluster) + end. + +%%------------------------------------------------------------------------------ +%% Helper functions +%%------------------------------------------------------------------------------ + +assert_config_load_done(Nodes) -> + lists:foreach( + fun(Node) -> + Done = rpc:call(Node, emqx_app, get_init_config_load_done, []), + ?assert(Done, #{node => Node}) + end, + Nodes + ). + +start_cluster(Specs) -> + [start_slave(I) || I <- Specs]. + +start_cluster_async(Specs) -> + [ + begin + spawn_link(fun() -> start_slave(I) end), + timer:sleep(7_000) + end + || I <- Specs + ]. + +cluster(Specs) -> + cluster(Specs, []). + +cluster(Specs0, CommonEnv) -> + Specs1 = lists:zip(Specs0, lists:seq(1, length(Specs0))), + Specs = expand_node_specs(Specs1, CommonEnv), + CoreNodes = [node_id(Name) || {{core, Name, _}, _} <- Specs], + %% Assign grpc ports: + BaseGenRpcPort = 9000, + GenRpcPorts = maps:from_list([ + {node_id(Name), {tcp, BaseGenRpcPort + Num}} + || {{_, Name, _}, Num} <- Specs + ]), + %% Set the default node of the cluster: + JoinTo = + case CoreNodes of + [First | _] -> #{join_to => First}; + _ -> #{} + end, + [ + JoinTo#{ + name => Name, + node => node_id(Name), + env => [ + {mria, core_nodes, CoreNodes}, + {mria, node_role, Role}, + {gen_rpc, tcp_server_port, BaseGenRpcPort + Number}, + {gen_rpc, client_config_per_node, {internal, GenRpcPorts}} + | Env + ], + number => Number, + role => Role + } + || {{Role, Name, Env}, Number} <- Specs + ]. + +start_apps(Node) -> + Handler = fun + (emqx) -> + application:set_env(emqx, boot_modules, []), + ok; + (_) -> + ok + end, + {Node, ok} = + {Node, rpc:call(Node, emqx_common_test_helpers, start_apps, [[emqx_conf], Handler])}, + ok. + +stop_apps(Node) -> + ok = rpc:call(Node, emqx_common_test_helpers, stop_apps, [[emqx_conf]]). + +join_cluster(#{node := Node, join_to := JoinTo}) -> + case rpc:call(Node, ekka, join, [JoinTo]) of + ok -> ok; + ignore -> ok; + Err -> error({failed_to_join_cluster, #{node => Node, error => Err}}) + end. + +start_slave(#{node := Node, env := Env}) -> + %% We want VMs to only occupy a single core + CommonBeamOpts = + "+S 1:1 " ++ + %% redirect logs to the master test node + " -master " ++ atom_to_list(node()) ++ " ", + %% We use `ct_slave' instead of `slave' because, in + %% `t_copy_conf_override_on_restarts', the nodes might be stuck + %% some time during boot up, and `slave' has a hard-coded boot + %% timeout. + {ok, Node} = ct_slave:start( + Node, + [ + {erl_flags, CommonBeamOpts ++ ebin_path()}, + {kill_if_fail, true}, + {monitor_master, true}, + {init_timeout, 30_000}, + {startup_timeout, 30_000} + ] + ), + + %% Load apps before setting the enviroment variables to avoid + %% overriding the environment during app start: + [rpc:call(Node, application, load, [App]) || App <- [gen_rpc]], + %% Disable gen_rpc listener by default: + Env1 = [{gen_rpc, tcp_server_port, false} | Env], + setenv(Node, Env1), + ok = start_apps(Node), + Node. + +expand_node_specs(Specs, CommonEnv) -> + lists:map( + fun({Spec, Num}) -> + { + case Spec of + core -> + {core, gen_node_name(Num), CommonEnv}; + replicant -> + {replicant, gen_node_name(Num), CommonEnv}; + {Role, Name} when is_atom(Name) -> + {Role, Name, CommonEnv}; + {Role, Env} when is_list(Env) -> + {Role, gen_node_name(Num), CommonEnv ++ Env}; + {Role, Name, Env} -> + {Role, Name, CommonEnv ++ Env} + end, + Num + } + end, + Specs + ). + +setenv(Node, Env) -> + [rpc:call(Node, application, set_env, [App, Key, Val]) || {App, Key, Val} <- Env]. + +teardown_cluster(Specs) -> + Nodes = [I || #{node := I} <- Specs], + [rpc:call(I, emqx_common_test_helpers, stop_apps, [emqx_conf]) || I <- Nodes], + [stop_slave(I) || I <- Nodes], + ok. + +stop_slave(Node) -> + ct_slave:stop(Node). + +host() -> + [_, Host] = string:tokens(atom_to_list(node()), "@"), + Host. + +node_id(Name) -> + list_to_atom(lists:concat([Name, "@", host()])). + +gen_node_name(N) -> + list_to_atom("n" ++ integer_to_list(N)). + +ebin_path() -> + string:join(["-pa" | paths()], " "). + +paths() -> + [ + Path + || Path <- code:get_path(), + string:prefix(Path, code:lib_dir()) =:= nomatch, + string:str(Path, "_build/default/plugins") =:= 0 + ]. From 8519948742f7d3af5b571389531441bc39d54499 Mon Sep 17 00:00:00 2001 From: Thales Macedo Garitezi Date: Mon, 25 Apr 2022 09:09:45 -0300 Subject: [PATCH 2/3] refactor: use macro to denote initial transaction id --- apps/emqx_conf/src/emqx_conf_app.erl | 2 ++ 1 file changed, 2 insertions(+) diff --git a/apps/emqx_conf/src/emqx_conf_app.erl b/apps/emqx_conf/src/emqx_conf_app.erl index 2115bc617..8b2b81cb4 100644 --- a/apps/emqx_conf/src/emqx_conf_app.erl +++ b/apps/emqx_conf/src/emqx_conf_app.erl @@ -24,6 +24,8 @@ -include_lib("emqx/include/logger.hrl"). -include("emqx_conf.hrl"). +-define(DEFAULT_INIT_TXN_ID, -1). + start(_StartType, _StartArgs) -> init_conf(), emqx_conf_sup:start_link(). From 67ed7ba7b8f7e0ce0437e9ad2d44e591c3ddf27b Mon Sep 17 00:00:00 2001 From: Thales Macedo Garitezi Date: Tue, 26 Apr 2022 12:14:38 -0300 Subject: [PATCH 3/3] refactor: do not differentiate node roles --- apps/emqx_conf/src/emqx_conf_app.erl | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/apps/emqx_conf/src/emqx_conf_app.erl b/apps/emqx_conf/src/emqx_conf_app.erl index 8b2b81cb4..1ad460043 100644 --- a/apps/emqx_conf/src/emqx_conf_app.erl +++ b/apps/emqx_conf/src/emqx_conf_app.erl @@ -35,11 +35,10 @@ stop(_State) -> get_override_config_file() -> Node = node(), - Role = mria_rlog:role(), case emqx_app:get_init_config_load_done() of false -> {error, #{node => Node, msg => "init_conf_load_not_done"}}; - true when Role =:= core -> + true -> case erlang:whereis(emqx_config_handler) of undefined -> {error, #{node => Node, msg => "emqx_config_handler_not_ready"}}; @@ -54,9 +53,7 @@ get_override_config_file() -> {atomic, Res} -> {ok, Res}; {aborted, Reason} -> {error, #{node => Node, msg => Reason}} end - end; - true when Role =:= replicant -> - {ignore, #{node => Node}} + end end. %% ------------------------------------------------------------------------------