nickva commented on a change in pull request #761: Add a debugging utilities
for listing processes
URL: https://github.com/apache/couchdb/pull/761#discussion_r134807095
##########
File path: src/couch/src/couch_debug.erl
##########
@@ -50,3 +233,299 @@ opened_files_contains(FileNameFragment) ->
lists:filter(fun({_Port, _Pid, _Fd, Path}) ->
string:str(Path, FileNameFragment) > 0
end, couch_debug:opened_files()).
+
+process_name(Pid) ->
+ case process_info(Pid, registered_name) of
+ {registered_name, Name} ->
+ iolist_to_list(io_lib:format("~s[~p]", [Name, Pid]));
+ _ ->
+ {dictionary, Dict} = process_info(Pid, dictionary),
+ case proplists:get_value('$initial_call', Dict) of
+ undefined ->
+ {initial_call, {M, F, A}} = process_info(Pid,
initial_call),
+ iolist_to_list(io_lib:format("~p:~p/~p[~p]", [M, F, A,
Pid]));
+ {M, F, A} ->
+ iolist_to_list(io_lib:format("~p:~p/~p[~p]", [M, F, A,
Pid]))
+ end
+ end.
+
+iolist_to_list(List) ->
+ binary_to_list(iolist_to_binary(List)).
+
+link_tree(RootPid) ->
+ link_tree(RootPid, []).
+
+link_tree(RootPid, Info) ->
+ link_tree(RootPid, Info, fun(_, Props) -> Props end).
+
+link_tree(RootPid, Info, Fun) ->
+ {_, Result} = link_tree(
+ RootPid, [links | Info], gb_trees:empty(), 0, [RootPid], Fun),
+ Result.
+
+link_tree(RootPid, Info, Visited0, Pos, [Pid | Rest], Fun) ->
+ case gb_trees:lookup(Pid, Visited0) of
+ {value, Props} ->
+ {Visited0, [{Pos, {Pid, Fun(Pid, Props), []}}]};
+ none when RootPid =< Pid ->
+ Props = info(Pid, Info),
+ Visited1 = gb_trees:insert(Pid, Props, Visited0),
+ {links, Children} = lists:keyfind(links, 1, Props),
+ {Visited2, NewTree} = link_tree(
+ RootPid, Info, Visited1, Pos + 1, Children, Fun),
+ {Visited3, Result} = link_tree(
+ RootPid, Info, Visited2, Pos, Rest, Fun),
+ {Visited3, [{Pos, {Pid, Fun(Pid, Props), NewTree}}] ++ Result};
+ none ->
+ Props = info(Pid, Info),
+ Visited1 = gb_trees:insert(Pid, Props, Visited0),
+ {Visited2, Result} = link_tree(
+ RootPid, Info, Visited1, Pos, Rest, Fun),
+ {Visited2, [{Pos, {Pid, Fun(Pid, Props), []}}] ++ Result}
+ end;
+link_tree(_RootPid, _Info, Visited, _Pos, [], _Fun) ->
+ {Visited, []}.
+
+
+info(Pid, Info) when is_pid(Pid) ->
+ ValidProps = [
+ backtrace,
+ binary,
+ catchlevel,
+ current_function,
+ current_location,
+ current_stacktrace,
+ dictionary,
+ error_handler,
+ garbage_collection,
+ garbage_collection_info,
+ group_leader,
+ heap_size,
+ initial_call,
+ links,
+ last_calls,
+ memory,
+ message_queue_len,
+ messages,
+ min_heap_size,
+ min_bin_vheap_size,
+ monitored_by,
+ monitors,
+ message_queue_data,
+ priority,
+ reductions,
+ registered_name,
+ sequential_trace_token,
+ stack_size,
+ status,
+ suspending,
+ total_heap_size,
+ trace,
+ trap_exit
+ ],
+ Validated = lists:filter(fun(P) -> lists:member(P, ValidProps) end, Info),
+ process_info(Pid, lists:usort(Validated));
+info(Port, Info) when is_port(Port) ->
+ ValidProps = [
+ registered_name,
+ id,
+ connected,
+ links,
+ name,
+ input,
+ output,
+ os_pid
+ ],
+ Validated = lists:filter(fun(P) -> lists:member(P, ValidProps) end, Info),
+ erlang:port_info(Port, lists:usort(Validated)).
+
+mapfold_tree([], Acc, _Fun) ->
+ {[], Acc};
+mapfold_tree([{Pos, {Key, Value0, SubTree0}} | Rest0], Acc0, Fun) ->
+ {Value1, Acc1} = Fun(Key, Value0, Pos, Acc0),
+ {SubTree1, Acc2} = mapfold_tree(SubTree0, Acc1, Fun),
+ {Rest1, Acc3} = mapfold_tree(Rest0, Acc2, Fun),
+ {[{Pos, {Key, Value1, SubTree1}} | Rest1], Acc3}.
+
+map_tree(Tree, Fun) ->
+ {Result, _} = mapfold_tree(Tree, nil, fun(Key, Value, Pos, Acc) ->
+ {Fun(Key, Value, Pos), Acc}
+ end),
+ Result.
+
+fold_tree(Tree, Acc, Fun) ->
+ {_, Result} = mapfold_tree(Tree, Acc, fun(Key, Value, Pos, AccIn) ->
+ {Value, Fun(Key, Value, Pos, AccIn)}
+ end),
+ Result.
+
+linked_processes_info(Pid, Info) ->
+ link_tree(Pid, Info, fun(P, Props) -> {process_name(P), Props} end).
+
+print_linked_processes(couch_index_server) ->
+ print_couch_index_server_processes();
+print_linked_processes(Name) when is_atom(Name) ->
+ case whereis(Name) of
+ undefined -> {error, {unknown, Name}};
+ Pid -> print_linked_processes(Pid)
+ end;
+print_linked_processes(Pid) when is_pid(Pid) ->
+ Info = [reductions, message_queue_len, memory],
+ TableSpec = [
+ {50, left, name}, {12, centre, reductions},
+ {19, centre, message_queue_len}, {10, centre, memory}
+ ],
+ Tree = linked_processes_info(Pid, Info),
+ print_tree(Tree, TableSpec).
+
+id("couch_file:init" ++ _, Pid, _Props) ->
+ case couch_file:process_info(Pid) of
+ {{file_descriptor, prim_file, {Port, Fd}}, FilePath} ->
+ term2str([
+ term2str(Fd), ":",
+ term2str(Port), ":",
+ shorten_path(FilePath)]);
+ undefined ->
+ ""
+ end;
+id(_IdStr, _Pid, _Props) ->
+ "".
+
+print_couch_index_server_processes() ->
+ Info = [reductions, message_queue_len, memory],
+ TableSpec = [
+ {50, left, name}, {12, centre, reductions},
+ {19, centre, message_queue_len}, {14, centre, memory}, {id}
+ ],
+
+ Tree = link_tree(whereis(couch_index_server), Info, fun(P, Props) ->
+ IdStr = process_name(P),
+ {IdStr, [{id, id(IdStr, P, Props)} | Props]}
+ end),
+ print_tree(Tree, TableSpec).
+
+shorten_path(Path) ->
+ ViewDir = list_to_binary(config:get("couchdb", "view_index_dir")),
+ DatabaseDir = list_to_binary(config:get("couchdb", "database_dir")),
+ File = list_to_binary(Path),
+ Len = max(
+ binary:longest_common_prefix([File, DatabaseDir]),
+ binary:longest_common_prefix([File, ViewDir])
+ ),
+ <<_:Len/binary, Rest/binary>> = File,
+ binary_to_list(Rest).
+
+%% Pretty print functions
+
+%% Limmitations:
+%% - The first column has to be specified as {Width, left, Something}
+print_tree(Tree, TableSpec) ->
+ io:format("~s~n", [format(TableSpec)]),
+ map_tree(Tree, fun(_, {Id, Props}, Pos) ->
+ io:format("~s~n", [table_row(Id, Pos * 2, Props, TableSpec)])
+ end),
+ ok.
+
+format(Spec) ->
+ Fields = [format_value(Format) || Format <- Spec],
+ string:join(Fields, "|").
+
+format_value({Value}) -> term2str(Value);
+format_value({Width, Align, Value}) -> string:Align(term2str(Value), Width).
+
+bind_value({K}, Props) when is_list(Props) ->
+ {element(2, lists:keyfind(K, 1, Props))};
+bind_value({Width, Align, K}, Props) when is_list(Props) ->
+ {Width, Align, element(2, lists:keyfind(K, 1, Props))}.
+
+term2str(Atom) when is_atom(Atom) -> atom_to_list(Atom);
+term2str(Binary) when is_binary(Binary) -> binary_to_list(Binary);
+term2str(Integer) when is_integer(Integer) -> integer_to_list(Integer);
+term2str(Float) when is_float(Float) -> float_to_list(Float);
+term2str(String) when is_list(String) -> lists:flatten(String);
+term2str(Term) -> iolist_to_list(io_lib:format("~p", [Term])).
+
+table_row(Key, Indent, Props, [{KeyWidth, Align, _} | Spec]) ->
+ Values = [bind_value(Format, Props) || Format <- Spec],
+ KeyStr = string:Align(term2str(Key), KeyWidth - Indent),
+ [string:copies(" ", Indent), KeyStr, "|" | format(Values)].
+
+-ifdef(TEST).
+-include_lib("couch/include/couch_eunit.hrl").
+
+random_processes() ->
+ random_processes([], 50).
+
+random_processes(Pids, 0) ->
+ Pids;
+random_processes(Acc, Left) ->
+ Pid = case oneof([spawn_monitor, spawn, spawn_link]) of
+ spawn_monitor ->
+ {P, _} = spawn_monitor(fun process_fun/0),
+ P;
+ spawn ->
+ spawn(fun process_fun/0);
+ spawn_link ->
+ spawn(fun process_fun/0)
Review comment:
spawn_link there? Or specifically didn't want to link to avoid crashing the
test process?
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