From 0725fe8296204a61f3dbc57142bfd458a45dd547 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 13 Jun 2017 07:10:39 +0200
Subject: Add informational test case z_SUITE:leaked_processes/1

Add z_SUITE:leaked_processes/1 to print the process information for
all new processes created during execution of the emulator test
suite. Test cases are not supposed leak processes, because that
could disturb later test cases.
---
 erts/emulator/test/a_SUITE.erl | 48 ++++++++++++++++++++++++++++++++++--------
 erts/emulator/test/z_SUITE.erl | 33 +++++++++++++++++++++++++++--
 2 files changed, 70 insertions(+), 11 deletions(-)

(limited to 'erts/emulator')

diff --git a/erts/emulator/test/a_SUITE.erl b/erts/emulator/test/a_SUITE.erl
index 880c5a5821..07922f9942 100644
--- a/erts/emulator/test/a_SUITE.erl
+++ b/erts/emulator/test/a_SUITE.erl
@@ -29,25 +29,55 @@
 
 -include_lib("common_test/include/ct.hrl").
 
--export([all/0, suite/0,
-	 long_timers/1, pollset_size/1]).
+-export([all/0, suite/0, init_per_suite/1, end_per_suite/1,
+	 leaked_processes/1, long_timers/1, pollset_size/1]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]}].
 
-all() -> 
-    [long_timers, pollset_size].
+all() ->
+    [leaked_processes, long_timers, pollset_size].
+
+%% Start some system servers now to avoid having them
+%% reported as leaks.
+
+init_per_suite(Config) when is_list(Config) ->
+    %% Ensure inet_gethost_native port program started, in order to
+    %% allow other suites to use it...
+    inet_gethost_native:gethostbyname("localhost"),
+
+    %% Start the timer server.
+    timer:start(),
+
+    Config.
+
+end_per_suite(Config) when is_list(Config) ->
+    Config.
+
+leaked_processes(Config) when is_list(Config) ->
+    Parent = self(),
+    Go = make_ref(),
+    spawn(fun () ->
+                  Name = leaked_processes__process_holder,
+                  true = register(Name, self()),
+                  Ps = processes(),
+                  Parent ! Go,
+                  receive
+                      {get_initial_processes, Pid} ->
+                          Pid ! {initial_processes, Ps}
+                  end
+          end),
+    receive Go -> ok end,
+    {comment, "Testcase started! This test will run in parallel with the "
+     "erts testsuite and ends in the z_SUITE:leaked_processes/1 testcase."}.
 
 long_timers(Config) when is_list(Config) ->
     Dir = proplists:get_value(data_dir, Config),
     long_timers_test:start(Dir),
     {comment, "Testcase started! This test will run in parallel with the "
-              "erts testsuite and ends in the z_SUITE:long_timers testcase."}.
+     "erts testsuite and ends in the z_SUITE:long_timers/1 testcase."}.
 
 pollset_size(Config) when is_list(Config) ->
-    %% Ensure inet_gethost_native port program started, in order to
-    %% allow other suites to use it...
-    inet_gethost_native:gethostbyname("localhost"),
     Parent = self(),
     Go = make_ref(),
     spawn(fun () ->
@@ -63,7 +93,7 @@ pollset_size(Config) when is_list(Config) ->
           end),
     receive Go -> ok end,
     {comment, "Testcase started! This test will run in parallel with the "
-              "erts testsuite and ends in the z_SUITE:pollset_size testcase."}.
+     "erts testsuite and ends in the z_SUITE:pollset_size/1 testcase."}.
 
 %%
 %% Internal functions...
diff --git a/erts/emulator/test/z_SUITE.erl b/erts/emulator/test/z_SUITE.erl
index a2b267543f..feea7432a9 100644
--- a/erts/emulator/test/z_SUITE.erl
+++ b/erts/emulator/test/z_SUITE.erl
@@ -36,7 +36,8 @@
 
 -export([schedulers_alive/1, node_container_refc_check/1,
 	 long_timers/1, pollset_size/1,
-	 check_io_debug/1, get_check_io_info/0]).
+	 check_io_debug/1, get_check_io_info/0,
+         leaked_processes/1]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]},
@@ -44,7 +45,10 @@ suite() ->
 
 all() -> 
     [schedulers_alive, node_container_refc_check,
-     long_timers, pollset_size, check_io_debug].
+     long_timers, pollset_size, check_io_debug,
+     %% Make sure that the leaked_processes/1 is always
+     %% run last.
+     leaked_processes].
 
 %%%
 %%% The test cases -------------------------------------------------------------
@@ -285,6 +289,31 @@ has_gethost([P|T]) ->
 has_gethost([]) ->
     false.
 
+leaked_processes(Config) when is_list(Config) ->
+    %% Replace the defualt timetrap with a timetrap with
+    %% known pid.
+    test_server:timetrap_cancel(),
+    Dog = test_server:timetrap(test_server:minutes(5)),
+
+    Name = leaked_processes__process_holder,
+    Name ! {get_initial_processes, self()},
+    receive
+        {initial_processes, Initial0} -> ok
+    end,
+    Initial = ordsets:from_list(Initial0),
+
+    KnownPids = ordsets:from_list([self(),Dog]),
+    Now0 = ordsets:from_list(processes()),
+    Now = ordsets:subtract(Now0, KnownPids),
+    Leaked = ordsets:subtract(Now, Initial),
+
+    _ = [begin
+             Info = process_info(P) ++ process_info(P, [current_stacktrace]),
+             io:format("~p: ~p\n", [P,Info])
+         end || P <- Leaked],
+    Comment = lists:flatten(io_lib:format("~p process(es)",
+                                          [length(Leaked)])),
+    {comment, Comment}.
 
 %%
 %% Internal functions...
-- 
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