graceful handling of application:which_applications() timeoutbug25571

6 files changed, 17 insertions, 6 deletions

diff --git a/src/app_utils.erl b/src/app_utils.erl
index 8da436c0..b102ce75 100644
--- a/src/app_utils.erl
+++ b/src/app_utils.erl
@@ -93,7 +93,7 @@ app_dependency_order(RootApps, StripUnreachable) ->
 %% Private API
 
 wait_for_application(Application) ->
-    case lists:keymember(Application, 1, application:which_applications()) of
+    case lists:keymember(Application, 1, rabbit_misc:which_applications()) of
          true  -> ok;
          false -> timer:sleep(1000),
                   wait_for_application(Application)
diff --git a/src/rabbit.erl b/src/rabbit.erl
index 37ed5ae0..450a7f32 100644
--- a/src/rabbit.erl
+++ b/src/rabbit.erl
@@ -393,7 +393,7 @@ await_startup() ->
 
 status() ->
     S1 = [{pid,                  list_to_integer(os:getpid())},
-          {running_applications, catch application:which_applications()},
+          {running_applications, rabbit_misc:which_applications()},
           {os,                   os:type()},
           {erlang_version,       erlang:system_info(system_version)},
           {memory,               rabbit_vm:memory()}],
diff --git a/src/rabbit_misc.erl b/src/rabbit_misc.erl
index c36fb147..a1e95fd5 100644
--- a/src/rabbit_misc.erl
+++ b/src/rabbit_misc.erl
@@ -61,7 +61,7 @@
 -export([multi_call/2]).
 -export([os_cmd/1]).
 -export([gb_sets_difference/2]).
--export([version/0]).
+-export([version/0, which_applications/0]).
 -export([sequence_error/1]).
 -export([json_encode/1, json_decode/1, json_to_term/1, term_to_json/1]).
 -export([check_expiry/1]).
@@ -232,6 +232,7 @@
 -spec(os_cmd/1 :: (string()) -> string()).
 -spec(gb_sets_difference/2 :: (gb_set(), gb_set()) -> gb_set()).
 -spec(version/0 :: () -> string()).
+-spec(which_applications/0 :: () -> [{atom(), string(), string()}]).
 -spec(sequence_error/1 :: ([({'error', any()} | any())])
                        -> {'error', any()} | any()).
 -spec(json_encode/1 :: (any()) -> {'ok', string()} | {'error', any()}).
@@ -985,6 +986,16 @@ version() ->
     {ok, VSN} = application:get_key(rabbit, vsn),
     VSN.
 
+%% application:which_applications(infinity) is dangerous, since it can
+%% cause deadlocks on shutdown. So we have to use a timeout variant,
+%% but w/o creating spurious timeout errors.
+which_applications() ->
+    try
+        application:which_applications()
+    catch
+        exit:{timeout, _} -> []
+    end.
+
 sequence_error([T])                      -> T;
 sequence_error([{error, _} = Error | _]) -> Error;
 sequence_error([_ | Rest])               -> sequence_error(Rest).
diff --git a/src/rabbit_nodes.erl b/src/rabbit_nodes.erl
index b52d36e3..b85646d2 100644
--- a/src/rabbit_nodes.erl
+++ b/src/rabbit_nodes.erl
@@ -96,7 +96,7 @@ cookie_hash() ->
     base64:encode_to_string(erlang:md5(atom_to_list(erlang:get_cookie()))).
 
 is_running(Node, Application) ->
-    case rpc:call(Node, application, which_applications, []) of
+    case rpc:call(Node, rabbit_misc, which_applications, []) of
         {badrpc, _} -> false;
         Apps        -> proplists:is_defined(Application, Apps)
     end.
diff --git a/src/rabbit_plugins.erl b/src/rabbit_plugins.erl
index 58c906eb..6f6515b0 100644
--- a/src/rabbit_plugins.erl
+++ b/src/rabbit_plugins.erl
@@ -47,7 +47,7 @@ setup() ->
 active() ->
     {ok, ExpandDir} = application:get_env(rabbit, plugins_expand_dir),
     InstalledPlugins = [ P#plugin.name || P <- list(ExpandDir) ],
-    [App || {App, _, _} <- application:which_applications(),
+    [App || {App, _, _} <- rabbit_misc:which_applications(),
             lists:member(App, InstalledPlugins)].
 
 %% @doc Get the list of plugins which are ready to be enabled.
diff --git a/src/rabbit_vm.erl b/src/rabbit_vm.erl
index c28b0cd5..e97824b9 100644
--- a/src/rabbit_vm.erl
+++ b/src/rabbit_vm.erl
@@ -99,7 +99,7 @@ bytes(Words) ->  Words * erlang:system_info(wordsize).
 
 plugin_sups() ->
     lists:append([plugin_sup(App) ||
-                     {App, _, _} <- application:which_applications(),
+                     {App, _, _} <- rabbit_misc:which_applications(),
                      is_plugin(atom_to_list(App))]).
 
 plugin_sup(App) ->