diff options
Diffstat (limited to 'erts')
| -rw-r--r-- | erts/emulator/beam/erl_gc.c | 36 | ||||
| -rw-r--r-- | erts/emulator/test/map_SUITE.erl | 96 |
2 files changed, 124 insertions, 8 deletions
diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c index d2604f1595..2f21111a2e 100644 --- a/erts/emulator/beam/erl_gc.c +++ b/erts/emulator/beam/erl_gc.c @@ -1237,6 +1237,7 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) Uint oh_size = (char *) OLD_HTOP(p) - oh; Uint n; Uint new_sz; + int done; /* * Do a fullsweep GC. First figure out the size of the heap @@ -1440,6 +1441,8 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) *recl += size_before - (HEAP_TOP(p) - HEAP_START(p)); + remove_message_buffers(p); + { ErlMessage *msgp; @@ -1458,15 +1461,21 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl) } } - adjust_after_fullsweep(p, need, objv, nobj); - -#ifdef HARDDEBUG - disallow_heap_frag_ref_in_heap(p); -#endif - remove_message_buffers(p); + if (MBUF(p)) { + /* This is a very rare case when distributed messages copied above + * contained maps so big they did not fit on the heap causing the + * factory to create heap frags. + * Solution: Trigger a minor gc (without tenuring) + */ + HIGH_WATER(p) = HEAP_START(p); + done = 0; + } else { + adjust_after_fullsweep(p, need, objv, nobj); + done = 1; + } ErtsGcQuickSanityCheck(p); - return 1; /* We are done. */ + return done; } static void @@ -1955,7 +1964,18 @@ collect_heap_frags(Process* p, Eterm* n_hstart, Eterm* n_htop, if (p->dictionary != NULL) { disallow_heap_frag_ref(p, n_htop, p->dictionary->data, p->dictionary->used); } - disallow_heap_frag_ref_in_heap(p); + /* OTP-18: Actually we do allow references from heap to heap fragments now. + This can happen when doing "binary_to_term" with a "fat" map contained + in another term. A "fat" map is a hashmap with higher heap demand than + first estimated by "binary_to_term" causing the factory to allocate + additional heap (fragments) for the hashmap tree nodes. + Run map_SUITE:t_gc_rare_map_overflow to provoke this. + + Inverted references like this does not matter however. The copy done + below by move_one_area() with move markers in the fragments and the + sweeping done later by the GC should make everything ok in the end. + */ + /***disallow_heap_frag_ref_in_heap(p);***/ #endif /* 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}). |