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authorSverker Eriksson <[email protected]>2018-04-12 11:54:47 +0200
committerSverker Eriksson <[email protected]>2018-04-13 17:38:25 +0200
commitbf0b86ea8e71d05331ef36c472f4dee646b22c38 (patch)
treedcc32b8ed1d262a0c29136b5e4c03cb245efc6d4 /lib/kernel
parenta7a70269a56d3fe651efcfa5a1139bfec2c8b1c0 (diff)
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erts: Add erts_debug:lc_graph/0
Run debug VM or config with --enable-lock-checking. Exercise VM and then run erts_debug:lc_graph(). to create a file "lc_graph.<pid>" in current working directory.
Diffstat (limited to 'lib/kernel')
-rw-r--r--lib/kernel/src/erts_debug.erl90
1 files changed, 89 insertions, 1 deletions
diff --git a/lib/kernel/src/erts_debug.erl b/lib/kernel/src/erts_debug.erl
index 6f248626ca..1270de4144 100644
--- a/lib/kernel/src/erts_debug.erl
+++ b/lib/kernel/src/erts_debug.erl
@@ -35,7 +35,8 @@
flat_size/1, get_internal_state/1, instructions/0,
map_info/1, same/2, set_internal_state/2,
size_shared/1, copy_shared/1, dirty_cpu/2, dirty_io/2, dirty/3,
- lcnt_control/1, lcnt_control/2, lcnt_collect/0, lcnt_clear/0]).
+ lcnt_control/1, lcnt_control/2, lcnt_collect/0, lcnt_clear/0,
+ lc_graph/0, lc_graph_to_dot/2, lc_graph_merge/2]).
-spec breakpoint(MFA, Flag) -> non_neg_integer() when
MFA :: {Module :: module(),
@@ -407,3 +408,90 @@ cont_dis(_, {_,_,_}, _) -> ok.
map_info(_) ->
erlang:nif_error(undef).
+
+%% Create file "lc_graph.<pid>" with all actual lock dependencies
+%% recorded so far by the VM.
+%% Needs debug VM or --enable-lock-checking config, returns 'notsup' otherwise.
+lc_graph() ->
+ erts_debug:set_internal_state(available_internal_state, true),
+ erts_debug:get_internal_state(lc_graph).
+
+%% Convert "lc_graph.<pid>" file to https://www.graphviz.org dot format.
+lc_graph_to_dot(OutFile, InFile) ->
+ {ok, [LL0]} = file:consult(InFile),
+
+ [{"NO LOCK",0} | LL] = LL0,
+ Map = maps:from_list([{Id, Name} || {Name, Id, _, _} <- LL]),
+
+ case file:open(OutFile, [exclusive]) of
+ {ok, Out} ->
+ ok = file:write(Out, "digraph G {\n"),
+
+ [dot_print_lock(Out, Lck, Map) || Lck <- LL],
+
+ ok = file:write(Out, "}\n"),
+ ok = file:close(Out);
+
+ {error,eexist} ->
+ {"File already exists", OutFile}
+ end.
+
+dot_print_lock(Out, {_Name, Id, Lst, _}, Map) ->
+ [dot_print_edge(Out, From, Id, Map) || From <- Lst],
+ ok.
+
+dot_print_edge(_, 0, _, _) ->
+ ignore; % "NO LOCK"
+dot_print_edge(Out, From, To, Map) ->
+ io:format(Out, "~p -> ~p;\n", [maps:get(From,Map), maps:get(To,Map)]).
+
+
+%% Merge several "lc_graph" files into one file.
+lc_graph_merge(OutFile, InFiles) ->
+ LLs = lists:map(fun(InFile) ->
+ {ok, [LL]} = file:consult(InFile),
+ LL
+ end,
+ InFiles),
+
+ Res = lists:foldl(fun(A, B) -> lcg_merge(A, B) end,
+ hd(LLs),
+ tl(LLs)),
+ case file:open(OutFile, [exclusive]) of
+ {ok, Out} ->
+ try
+ lcg_print(Out, Res)
+ after
+ file:close(Out)
+ end,
+ ok;
+ {error, eexist} ->
+ {"File already exists", OutFile}
+ end.
+
+lcg_merge(A, B) ->
+ lists:zipwith(fun(LA, LB) -> lcg_merge_locks(LA, LB) end,
+ A, B).
+
+lcg_merge_locks(L, L) ->
+ L;
+lcg_merge_locks({Name, Id, DA, IA}, {Name, Id, DB, IB}) ->
+ Direct = lists:umerge(DA, DB),
+ Indirect = lists:umerge(IA, IB),
+ {Name, Id, Direct, Indirect -- Direct}.
+
+
+lcg_print(Out, LL) ->
+ io:format(Out, "[", []),
+ lcg_print_locks(Out, LL),
+ io:format(Out, "].\n", []),
+ ok.
+
+lcg_print_locks(Out, [{_,_}=NoLock | Rest]) ->
+ io:format(Out, "~p,\n", [NoLock]),
+ lcg_print_locks(Out, Rest);
+lcg_print_locks(Out, [LastLock]) ->
+ io:format(Out, "~w", [LastLock]);
+lcg_print_locks(Out, [Lock | Rest]) ->
+ io:format(Out, "~w,\n", [Lock]),
+ lcg_print_locks(Out, Rest).