From 0727fa2e5c1ce8633096d4ad7c7f5f40e81d2264 Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Fri, 9 Nov 2018 16:01:58 +0100
Subject: Parallel stress test strong_rand_bytes

---
 lib/crypto/test/crypto_SUITE.erl | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'lib/crypto')

diff --git a/lib/crypto/test/crypto_SUITE.erl b/lib/crypto/test/crypto_SUITE.erl
index 025c46aab0..6b7ed06797 100644
--- a/lib/crypto/test/crypto_SUITE.erl
+++ b/lib/crypto/test/crypto_SUITE.erl
@@ -38,6 +38,7 @@ all() ->
      mod_pow,
      exor,
      rand_uniform,
+     rand_threads,
      rand_plugin,
      rand_plugin_s
     ].
@@ -604,6 +605,25 @@ rand_uniform(Config) when is_list(Config) ->
     rand_uniform_aux_test(10),
     10 = byte_size(crypto:strong_rand_bytes(10)).
 
+%%--------------------------------------------------------------------
+rand_threads() ->
+    [{doc, "strong_rand_bytes in parallel threads"}].
+rand_threads(Config) when is_list(Config) ->
+    %% This will crash the emulator on at least one version of libcrypto
+    %% with buggy multithreading in RAND_bytes().
+    %% The test needs to run at least a few minutes...
+    NofThreads = 4,
+    Fun = fun F() -> crypto:strong_rand_bytes(16), F() end,
+    PidRefs = [spawn_monitor(Fun) || _ <- lists:seq(1, NofThreads)],
+%%% The test case takes too much time to run.
+%%% Keep it around for reference by setting it down to just 10 seconds.
+%%%    receive after 10 * 60 * 1000 -> ok end, % 10 minutes
+    receive after 10 * 1000 -> ok end, % 10 seconds
+    spawn_link(fun () -> receive after 5000 -> exit(timeout) end end),
+    [exit(Pid, stop) || {Pid,_Ref} <- PidRefs],
+    [receive {'DOWN',Ref,_,_,stop} -> ok end || {_Pid,Ref} <- PidRefs],
+    ok.
+
 %%--------------------------------------------------------------------
 rand_plugin() ->
     [{doc, "crypto rand plugin testing (implicit state / process dictionary)"}].
-- 
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