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-rw-r--r--erts/emulator/test/map_SUITE.erl96
1 files changed, 96 insertions, 0 deletions
diff --git a/erts/emulator/test/map_SUITE.erl b/erts/emulator/test/map_SUITE.erl
index 886ae7d516..1b9758c23e 100644
--- a/erts/emulator/test/map_SUITE.erl
+++ b/erts/emulator/test/map_SUITE.erl
@@ -58,6 +58,7 @@
%% erlang
t_erlang_hash/1,
t_map_encode_decode/1,
+ t_gc_rare_map_overflow/1,
%% non specific BIF related
t_bif_build_and_check/1,
@@ -121,6 +122,7 @@ all() -> [
%% erlang
t_erlang_hash, t_map_encode_decode,
+ t_gc_rare_map_overflow,
t_map_size, t_is_map,
%% non specific BIF related
@@ -2966,3 +2968,97 @@ do_badmap_17(Config) ->
%% Use this function to avoid compile-time evaluation of an expression.
id(I) -> I.
+
+
+%% OTP-13146
+%% Provoke major GC with a lot of "fat" maps on external format in msg queue
+%% causing heap fragments to be allocated.
+t_gc_rare_map_overflow(Config) ->
+ Pa = filename:dirname(code:which(?MODULE)),
+ {ok, Node} = test_server:start_node(gc_rare_map_overflow, slave, [{args, "-pa \""++Pa++"\""}]),
+ Echo = spawn_link(Node, fun Loop() -> receive {From,Msg} -> From ! Msg
+ end,
+ Loop()
+ end),
+ FatMap = fatmap(34),
+ false = (flatmap =:= erts_internal:map_type(FatMap)),
+
+ t_gc_rare_map_overflow_do(Echo, FatMap, fun() -> erlang:garbage_collect() end),
+
+ % Repeat test for minor gc:
+ minor_collect(), % need this to make the next gc really be a minor
+ t_gc_rare_map_overflow_do(Echo, FatMap, fun() -> true = minor_collect() end),
+
+ unlink(Echo),
+ test_server:stop_node(Node).
+
+t_gc_rare_map_overflow_do(Echo, FatMap, GcFun) ->
+ Master = self(),
+ true = receive M -> false after 0 -> true end, % assert empty msg queue
+ Echo ! {Master, token},
+ repeat(1000, fun(_) -> Echo ! {Master, FatMap} end, void),
+
+ timer:sleep(100), % Wait for maps to arrive in our msg queue
+ token = receive Tok -> Tok end, % and provoke move from outer to inner msg queue
+
+ %% Do GC that will "overflow" and create heap frags due to all the fat maps
+ GcFun(),
+
+ %% Now check that all maps in msg queueu are intact
+ %% Will crash emulator in OTP-18.1
+ repeat(1000, fun(_) -> FatMap = receive FM -> FM end end, void),
+ ok.
+
+minor_collect() ->
+ minor_collect(minor_gcs()).
+
+minor_collect(Before) ->
+ After = minor_gcs(),
+ case After of
+ _ when After > Before -> true;
+ _ when After =:= Before -> minor_collect(Before);
+ 0 -> false
+ end.
+
+minor_gcs() ->
+ {garbage_collection, Info} = process_info(self(), garbage_collection),
+ {minor_gcs, GCS} = lists:keyfind(minor_gcs, 1, Info),
+ GCS.
+
+%% Generate a map with N (or N+1) keys that has an abnormal heap demand.
+%% Done by finding keys that collide in the first 32-bit hash.
+fatmap(N) ->
+ erts_debug:set_internal_state(available_internal_state, true),
+ Table = ets:new(void, [bag, private]),
+
+ Seed0 = rand:seed_s(exsplus, {4711, 3141592, 2718281}),
+ Seed1 = fatmap_populate(Table, Seed0, (1 bsl 16)),
+ Keys = fatmap_generate(Table, Seed1, N, []),
+ ets:delete(Table),
+ maps:from_list([{K,K} || K <- Keys]).
+
+fatmap_populate(_, Seed, 0) -> Seed;
+fatmap_populate(Table, Seed, N) ->
+ {I, NextSeed} = rand:uniform_s(1 bsl 48, Seed),
+ Hash = internal_hash(I),
+ ets:insert(Table, [{Hash, I}]),
+ fatmap_populate(Table, NextSeed, N-1).
+
+
+fatmap_generate(_, _, N, Acc) when N =< 0 ->
+ Acc;
+fatmap_generate(Table, Seed, N0, Acc0) ->
+ {I, NextSeed} = rand:uniform_s(1 bsl 48, Seed),
+ Hash = internal_hash(I),
+ case ets:member(Table, Hash) of
+ true ->
+ NewKeys = [I | ets:lookup_element(Table, Hash, 2)],
+ Acc1 = lists:usort(Acc0 ++ NewKeys),
+ N1 = N0 - (length(Acc1) - length(Acc0)),
+ fatmap_generate(Table, NextSeed, N1, Acc1);
+ false ->
+ fatmap_generate(Table, NextSeed, N0, Acc0)
+ end.
+
+internal_hash(Term) ->
+ erts_debug:get_internal_state({internal_hash, Term}).