diff --git a/etc/emqx.conf b/etc/emqx.conf
index 3604f2efd..635ccf68c 100644
--- a/etc/emqx.conf
+++ b/etc/emqx.conf
@@ -544,6 +544,12 @@ zone.external.enable_acl = on
 ## Value: on | off
 zone.external.enable_stats = on
 
+## Force MQTT connection/session process GC after this number of
+## messages | bytes passed through.
+##
+## Numbers delimited by `|'. Zero or negative is to disable.
+zone.external.force_gc_policy = 1000|1MB
+
 ## Maximum MQTT packet size allowed.
 ##
 ## Value: Bytes
diff --git a/priv/emqx.schema b/priv/emqx.schema
index 9fcd97376..47ad97293 100644
--- a/priv/emqx.schema
+++ b/priv/emqx.schema
@@ -828,7 +828,7 @@ end}.
 %% messages | bytes passed through.
 %% Numbers delimited by `|'. Zero or negative is to disable.
 {mapping, "zone.$name.force_gc_policy", "emqx.zones", [
-   {default, "0|0"},
+   {default, "0|0KB"},
    {datatype, string}
  ]}.
 
@@ -841,8 +841,13 @@ end}.
                     {mqtt_shared_subscription, Val};
                ("force_gc_policy", Val) ->
                     [Count, Bytes] = string:tokens(Val, "| "),
-                    {force_gc_policy, #{count => list_to_integer(Count),
-                                        bytes => list_to_integer(Bytes)}};
+                    GcPolicy = case cuttlefish_bytesize:parse(Bytes) of
+                                   {error, Reason} ->
+                                       error(Reason);
+                                   Bytes1 ->
+                                       #{bytes => Bytes1, count => list_to_integer(Count)}
+                               end,
+                    {force_gc_policy, GcPolicy};
                (Opt, Val) ->
                     {list_to_atom(Opt), Val}
             end,
diff --git a/src/emqx_gc.erl b/src/emqx_gc.erl
index 65bbccad1..7e98eb37a 100644
--- a/src/emqx_gc.erl
+++ b/src/emqx_gc.erl
@@ -21,8 +21,6 @@
 
 -module(emqx_gc).
 
--author("Feng Lee <feng@emqtt.io>").
-
 -export([init/1, inc/2, reset/0]).
 
 -type st() :: #{ cnt => {integer(), integer()}