{error,{stream_error,{closed,{error,closed}}}} after 200 code

[Vkutovoy92]

Hello!
My issue is: after

GunRes = gun:await(ConnPid, StreamRef, ?TIMEOUT),
case GunRes of
    {response, nofin, HttpCode = 200,  _Headers} ->
      case gun:await_body(ConnPid, StreamRef, ?TIMEOUT) of

I get from time to time
{error,{stream_error,{closed,{error,closed}}}}

Options for connecting are:

  Opts = #{
    connect_timeout => 5000,
    http2_opts => #{
      keepalive => 60 * 1000,
      initial_connection_window_size => 65535,
      initial_stream_window_size => 65535
    },
    protocols => [http2],
    retry => 100,
    retry_timeout => 1000 % 1s
  },

Both applications in the same AWS accounts, on the dashboard it looks as

[essen]

The error means the socket was closed. You can trace Gun to figure out why (#{trace => true} in options).

[Vkutovoy92]

The error means the socket was closed. You can trace Gun to figure out why (#{trace => true} in options).

And where can I get the result of tracing after?

[essen]

It's printed in the shell.

Note that you won't get the reason but that this will help figure out what Gun was doing before the socket was closed. Alternatively wireshark also provides insight.

Gun unfortunately doesn't have the reason because the connection was closed abruptly. If it did you would have received it in the message.

[Vkutovoy92]

I guess error is connected with
initial_connection_window_size => 65535,
initial_stream_window_size => 65535

Because I removed this option on another application which had the same error and error has disappeared, on this service if I remove this option response time grows really high.

[essen]

Maybe the server you connect to doesn't like to receive WINDOW_UPDATE frames on connect, but that's not expected to be a problem. What server do you connect to?

[Vkutovoy92]

Maybe the server you connect to doesn't like to receive WINDOW_UPDATE frames on connect, but that's not expected to be a problem. What server do you connect to?

It's all in AWS structure and between application's is ALB, application which serves requests is Erlang + Cowboy.
It's pretty interesting how these 2 options affect to response time.

[essen]

The options should only impact response time of the first request, it's only to preemptively request more data than the default. After that the other window options take effect.