[erlang-questions] Diagnosing gen_server call timeouts

[Roger Lipscombe]

Er, so I neglected to mention that the gen_server is remote (same
host, different node), so process_info doesn't work :(

On Fri, 20 Sep 2019 at 01:45, Max Lapshin <max.lapshin@REDACTED> wrote:
>
> Copy paste from our video_frame.erl:
>
>
> send_frame(Stream, #video_frame{content = Content, codec = Codec, flavor = Flavor, dts = DTS} = Frame, SourceTag) when is_pid(Stream) ->
>   Frame1 = case SourceTag of
>     undefined -> Frame;
>     _ -> Frame#video_frame{source = SourceTag}
>   end,
>   try gen_server:call(Stream, Frame1)
>   catch
>     exit:{normal, _} ->
>       {error, stopped};
>     exit:{noproc, _} ->
>       {error, stopped};
>     exit:{shutdown, _} ->
>       {error, stopped};
>     exit:{timeout, _}:Stack ->
>       Dict = case process_info(Stream, dictionary) of
>         {dictionary, Dict_} -> Dict_;
>         undefined -> []
>       end,
>       RemoteStack = process_info(Stream, current_stacktrace),
>       Name = case proplists:get_value(name, Dict, <<"dead stream">>) of
>         N when is_binary(N) -> N;
>         N when is_atom(N) -> N;
>         N -> iolist_to_binary(io_lib:format("~p", [N]))
>       end,
>       Status = proplists:get_value(status, Dict),
>       case Status of
>         S when S == starting_transcoder -> ok;
>         _ -> events:error("failed to send frame ~p,~p,~p,~p, source_tag=~p to ~s (~p) in status ~p\n~p\nremote stack:\n~p", [
>                          Content, Codec, Flavor, round(DTS), Frame1#video_frame.source,
>                          Name, Stream, Status, Stack, RemoteStack])
>       end,
>       % [io:format("~10.. s: ~p~n", [K,V]) || {K,V} <- process_info(Stream)]
>       {error, timeout}
>   end.
>
>
>
> this code is helping us for years.  You should remove video specific stuff.