fix(buffer_worker): change the default `resume_interval` value and expose it as hidden config

Also removes the previously added alarm for request timeout.

There are situations where having a short request timeout and a long
health check interval make sense, so we don't want to alarm the user
for those situations.  Instead, we automatically attempt to set a
reasonable `resume_interval` value.

apps/emqx_resource/i18n/emqx_resource_schema_i18n.conf

@@ -45,6 +45,17 @@ For bridges only have ingress direction data flow, it can be set to 0 otherwise
     }
   }
 
+  resume_interval {
+    desc {
+      en: """The interval at which a resource will retry inflight requests."""
+      zh: """资源重试机内请求的间隔时间。"""
+    }
+    label {
+      en: """Resume Interval"""
+      zh: """复职时间间隔"""
+    }
+  }
+
   start_after_created {
     desc {
       en: """Whether start the resource right after created."""
@@ -102,8 +113,8 @@ For bridges only have ingress direction data flow, it can be set to 0 otherwise
 
   request_timeout {
     desc {
-      en: """Starting from the moment when the request enters the buffer, if the request remains in the buffer for the specified time or is sent but does not receive a response or acknowledgement in time, the request is considered expired.  We recommend setting this timeout to be at least twice the health check interval, so that the buffer has the chance to recover if too many requests get enqueued."""
-      zh: """从请求进入缓冲区开始计时，如果请求在规定的时间内仍停留在缓冲区内或者已发送但未能及时收到响应或确认，该请求将被视为过期。我们建议将这个超时设置为健康检查间隔的至少两倍，这样，如果有太多的请求被排队，缓冲区就有机会恢复。"""
+      en: """Starting from the moment when the request enters the buffer, if the request remains in the buffer for the specified time or is sent but does not receive a response or acknowledgement in time, the request is considered expired."""
+      zh: """从请求进入缓冲区开始计时，如果请求在规定的时间内仍停留在缓冲区内或者已发送但未能及时收到响应或确认，该请求将被视为过期。"""
     }
     label {
       en: """Request Expiry"""

apps/emqx_resource/include/emqx_resource.hrl

@@ -91,10 +91,7 @@
 -define(DEFAULT_QUEUE_SIZE, 100 * 1024 * 1024).
 -define(DEFAULT_QUEUE_SIZE_RAW, <<"100MB">>).
 
-%% Note: this should be greater than the health check timeout;
-%% otherwise, if the buffer worker is ever blocked, than all queued
-%% requests will basically fail without being attempted.
--define(DEFAULT_REQUEST_TIMEOUT, timer:seconds(30)).
+-define(DEFAULT_REQUEST_TIMEOUT, timer:seconds(15)).
 
 %% count
 -define(DEFAULT_BATCH_SIZE, 1).

apps/emqx_resource/src/emqx_resource_buffer_worker.erl

@@ -56,8 +56,6 @@
 
 -export([clear_disk_queue_dir/2]).
 
--export([deactivate_bad_request_timeout_alarm/1]).
-
 -elvis([{elvis_style, dont_repeat_yourself, disable}]).
 
 -define(COLLECT_REQ_LIMIT, 1000).
@@ -203,7 +201,8 @@ init({Id, Index, Opts}) ->
     RequestTimeout = maps:get(request_timeout, Opts, ?DEFAULT_REQUEST_TIMEOUT),
     BatchTime0 = maps:get(batch_time, Opts, ?DEFAULT_BATCH_TIME),
     BatchTime = adjust_batch_time(Id, RequestTimeout, BatchTime0),
-    maybe_toggle_bad_request_timeout_alarm(Id, RequestTimeout, HealthCheckInterval),
+    DefaultResumeInterval = default_resume_interval(RequestTimeout, HealthCheckInterval),
+    ResumeInterval = maps:get(resume_interval, Opts, DefaultResumeInterval),
     Data = #{
         id => Id,
         index => Index,
@@ -212,7 +211,7 @@ init({Id, Index, Opts}) ->
         batch_size => BatchSize,
         batch_time => BatchTime,
         queue => Queue,
-        resume_interval => maps:get(resume_interval, Opts, HealthCheckInterval),
+        resume_interval => ResumeInterval,
         tref => undefined
     },
     ?tp(buffer_worker_init, #{id => Id, index => Index}),
@@ -1684,38 +1683,16 @@ adjust_batch_time(Id, RequestTimeout, BatchTime0) ->
     end,
     BatchTime.
 
-%% The request timeout should be greater than the health check
-%% timeout, health timeout defines how often the buffer worker tries
-%% to unblock. If request timeout is <= health check timeout and the
-%% buffer worker is ever blocked, than all queued requests will
-%% basically fail without being attempted.
--spec maybe_toggle_bad_request_timeout_alarm(
-    resource_id(), request_timeout(), health_check_interval()
-) -> ok.
-maybe_toggle_bad_request_timeout_alarm(Id, _RequestTimeout = infinity, _HealthCheckInterval) ->
-    deactivate_bad_request_timeout_alarm(Id),
-    ok;
-maybe_toggle_bad_request_timeout_alarm(Id, RequestTimeout, HealthCheckInterval) ->
-    case RequestTimeout > HealthCheckInterval of
-        true ->
-            deactivate_bad_request_timeout_alarm(Id),
-            ok;
-        false ->
-            _ = emqx_alarm:activate(
-                bad_request_timeout_alarm_id(Id),
-                #{resource_id => Id, reason => bad_request_timeout},
-                <<"Request timeout should be greater than health check timeout: ", Id/binary>>
-            ),
-            ok
-    end.
-
--spec deactivate_bad_request_timeout_alarm(resource_id()) -> ok.
-deactivate_bad_request_timeout_alarm(Id) ->
-    _ = emqx_alarm:ensure_deactivated(bad_request_timeout_alarm_id(Id)),
-    ok.
-
-bad_request_timeout_alarm_id(Id) ->
-    <<"bad_request_timeout:", Id/binary>>.
+%% The request timeout should be greater than the resume interval, as
+%% it defines how often the buffer worker tries to unblock. If request
+%% timeout is <= resume interval and the buffer worker is ever
+%% blocked, than all queued requests will basically fail without being
+%% attempted.
+-spec default_resume_interval(request_timeout(), health_check_interval()) -> timer:time().
+default_resume_interval(_RequestTimeout = infinity, HealthCheckInterval) ->
+    max(1, HealthCheckInterval);
+default_resume_interval(RequestTimeout, HealthCheckInterval) ->
+    max(1, min(HealthCheckInterval, RequestTimeout div 3)).
 
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").

apps/emqx_resource/src/emqx_resource_manager.erl

@@ -506,7 +506,6 @@ handle_remove_event(From, ClearMetrics, Data) ->
         true -> ok = emqx_metrics_worker:clear_metrics(?RES_METRICS, Data#data.id);
         false -> ok
     end,
-    emqx_resource_buffer_worker:deactivate_bad_request_timeout_alarm(Data#data.id),
     {stop_and_reply, {shutdown, removed}, [{reply, From, ok}]}.
 
 start_resource(Data, From) ->

apps/emqx_resource/src/schema/emqx_resource_schema.erl

@@ -55,6 +55,7 @@ fields("creation_opts") ->
     [
         {worker_pool_size, fun worker_pool_size/1},
         {health_check_interval, fun health_check_interval/1},
+        {resume_interval, fun resume_interval/1},
         {start_after_created, fun start_after_created/1},
         {start_timeout, fun start_timeout/1},
         {auto_restart_interval, fun auto_restart_interval/1},
@@ -81,6 +82,12 @@ worker_pool_size(default) -> ?WORKER_POOL_SIZE;
 worker_pool_size(required) -> false;
 worker_pool_size(_) -> undefined.
 
+resume_interval(type) -> emqx_schema:duration_ms();
+resume_interval(hidden) -> true;
+resume_interval(desc) -> ?DESC("resume_interval");
+resume_interval(required) -> false;
+resume_interval(_) -> undefined.
+
 health_check_interval(type) -> emqx_schema:duration_ms();
 health_check_interval(desc) -> ?DESC("health_check_interval");
 health_check_interval(default) -> ?HEALTHCHECK_INTERVAL_RAW;

apps/emqx_resource/test/emqx_resource_SUITE.erl

@@ -2554,132 +2554,6 @@ do_t_recursive_flush() ->
     ),
     ok.
 
-%% Check that we raise an alarm if a bad request timeout config is
-%% issued.  Request timeout should be greater than health check
-%% timeout.
-t_bad_request_timeout_alarm(_Config) ->
-    emqx_connector_demo:set_callback_mode(async_if_possible),
-
-    %% 1) Same values.
-    {ok, _} = emqx_resource:create(
-        ?ID,
-        ?DEFAULT_RESOURCE_GROUP,
-        ?TEST_RESOURCE,
-        #{name => test_resource},
-        #{
-            query_mode => async,
-            request_timeout => 1_000,
-            health_check_interval => 1_000,
-            worker_pool_size => 2
-        }
-    ),
-    ExpectedMessage =
-        <<"Request timeout should be greater than health check timeout: ", ?ID/binary>>,
-    ?assertMatch(
-        [
-            #{
-                message := ExpectedMessage,
-                details := #{reason := bad_request_timeout, resource_id := ?ID},
-                deactivate_at := infinity
-            }
-        ],
-        emqx_alarm:get_alarms(activated)
-    ),
-    %% The unexpected termination of one of the buffer workers should
-    %% not turn the alarm off.
-    [Pid, _ | _] = emqx_resource_buffer_worker_sup:worker_pids(?ID),
-    MRef = monitor(process, Pid),
-    exit(Pid, kill),
-    receive
-        {'DOWN', MRef, process, Pid, _} ->
-            ok
-    after 300 ->
-        ct:fail("buffer worker didn't die")
-    end,
-    ?assertMatch(
-        [
-            #{
-                message := ExpectedMessage,
-                details := #{reason := bad_request_timeout, resource_id := ?ID},
-                deactivate_at := infinity
-            }
-        ],
-        emqx_alarm:get_alarms(activated)
-    ),
-    ok = emqx_resource:remove_local(?ID),
-    ?assertEqual([], emqx_alarm:get_alarms(activated)),
-
-    %% 2) Request timeout < health check interval.
-    {ok, _} = emqx_resource:create(
-        ?ID,
-        ?DEFAULT_RESOURCE_GROUP,
-        ?TEST_RESOURCE,
-        #{name => test_resource},
-        #{
-            query_mode => async,
-            request_timeout => 999,
-            health_check_interval => 1_000,
-            worker_pool_size => 2
-        }
-    ),
-    ?assertMatch(
-        [
-            #{
-                message := ExpectedMessage,
-                details := #{reason := bad_request_timeout, resource_id := ?ID},
-                deactivate_at := infinity
-            }
-        ],
-        emqx_alarm:get_alarms(activated)
-    ),
-    ok = emqx_resource:remove_local(?ID),
-    ?assertEqual([], emqx_alarm:get_alarms(activated)),
-
-    %% 2) Request timeout < health check interval.
-    {ok, _} = emqx_resource:create(
-        ?ID,
-        ?DEFAULT_RESOURCE_GROUP,
-        ?TEST_RESOURCE,
-        #{name => test_resource},
-        #{
-            query_mode => async,
-            request_timeout => 999,
-            health_check_interval => 1_000,
-            worker_pool_size => 2
-        }
-    ),
-    ?assertMatch(
-        [
-            #{
-                message := ExpectedMessage,
-                details := #{reason := bad_request_timeout, resource_id := ?ID},
-                deactivate_at := infinity
-            }
-        ],
-        emqx_alarm:get_alarms(activated)
-    ),
-    ok = emqx_resource:remove_local(?ID),
-    ?assertEqual([], emqx_alarm:get_alarms(activated)),
-
-    %% 3) Request timeout > health check interval.
-    {ok, _} = emqx_resource:create(
-        ?ID,
-        ?DEFAULT_RESOURCE_GROUP,
-        ?TEST_RESOURCE,
-        #{name => test_resource},
-        #{
-            query_mode => async,
-            request_timeout => 1_001,
-            health_check_interval => 1_000,
-            worker_pool_size => 2
-        }
-    ),
-    ?assertEqual([], emqx_alarm:get_alarms(activated)),
-    ok = emqx_resource:remove_local(?ID),
-    ?assertEqual([], emqx_alarm:get_alarms(activated)),
-
-    ok.
-
 %%------------------------------------------------------------------------------
 %% Helpers
 %%------------------------------------------------------------------------------

changes/ce/fix-10154.en.md

@@ -1,7 +1,8 @@
-Change the default `request_timeout` for bridges and connectors to be
-twice the default `health_check_interval`.
+Change the default `resume_interval` for bridges and connectors to be
+the minimum of `health_check_interval` and `request_timeout / 3`.
+Also exposes it as a hidden configuration to allow fine tuning.
 
-Before this change, the default values for those two options meant
+Before this change, the default values for `resume_interval` meant
 that, if a buffer ever got blocked due to resource errors or high
 message volumes, then, by the time the buffer would try to resume its
 normal operations, almost all requests would have timed out.

lib-ee/emqx_ee_bridge/test/emqx_ee_bridge_gcp_pubsub_SUITE.erl

@@ -520,6 +520,7 @@ wait_until_gauge_is(GaugeName, ExpectedValue, Timeout) ->
         #{measurements := #{gauge_set := ExpectedValue}} ->
             ok;
         #{measurements := #{gauge_set := Value}} ->
+            ct:pal("events: ~p", [Events]),
             ct:fail(
                 "gauge ~p didn't reach expected value ~p; last value: ~p",
                 [GaugeName, ExpectedValue, Value]
@@ -972,7 +973,13 @@ t_publish_econnrefused(Config) ->
     ResourceId = ?config(resource_id, Config),
     %% set pipelining to 1 so that one of the 2 requests is `pending'
     %% in ehttpc.
-    {ok, _} = create_bridge(Config, #{<<"pipelining">> => 1}),
+    {ok, _} = create_bridge(
+        Config,
+        #{
+            <<"pipelining">> => 1,
+            <<"resource_opts">> => #{<<"resume_interval">> => <<"15s">>}
+        }
+    ),
     {ok, #{<<"id">> := RuleId}} = create_rule_and_action_http(Config),
     on_exit(fun() -> ok = emqx_rule_engine:delete_rule(RuleId) end),
     assert_empty_metrics(ResourceId),
@@ -986,7 +993,10 @@ t_publish_timeout(Config) ->
     %% requests are done separately.
     {ok, _} = create_bridge(Config, #{
         <<"pipelining">> => 1,
-        <<"resource_opts">> => #{<<"batch_size">> => 1}
+        <<"resource_opts">> => #{
+            <<"batch_size">> => 1,
+            <<"resume_interval">> => <<"15s">>
+        }
     }),
     {ok, #{<<"id">> := RuleId}} = create_rule_and_action_http(Config),
     on_exit(fun() -> ok = emqx_rule_engine:delete_rule(RuleId) end),