[erlang-questions] (ArgumentError) argument error :erlang.binary_to_term

Sat Jan 28 01:55:51 CET 2017

Hi,

I am using Elixir to send data using :gen_tcp. The syntax presented here
may be elementary Elixir syntax, however the issue is specifically related
to the usage of term_to_binary and binary_to_term conversions over gen_tcp.

This is the command I used on the client side:

> :gen_tcp.send(client_socket, :erlang.term_to_binary(data))

This is the command I use on the server side:

>   defp handle_data(data) do
>     data
>     |> :erlang.binary_to_term
>   end

When my data gets received on the server side, it seems that at a certain
size threshold that it errors out like this:

pry(6)> [error] GenServer #PID<0.502.0> terminating

** (ArgumentError) argument error

 :erlang.binary_to_term(<<131, 116, 0, 0, 0, 28, 109, 0, 0, 0, 5, 66, 49,
> 95, 81, 49, 108, 0, 0, 0, 1, 116, 0, 0, 0, 1, 109, 0, 0, 0, 4, 116, 101,
> 120, 116, 109, 0, 0, 0, 11, 84, 69, 88, 84, 32, 65, 78, 83, 87, 69, ...>>)

(stdlib) gen_server.erl:601: :gen_server.try_dispatch/4

(stdlib) gen_server.erl:667: :gen_server.handle_msg/5

(stdlib) proc_lib.erl:247: :proc_lib.init_p_do_apply/3

Last message: {:tcp, #Port<0.10115>, <<131, 116, 0, 0, 0, 28, 109, 0, 0, 0,
> 5, 66, 49, 95, 81, 49, 108, 0, 0, 0, 1, 116, 0, 0, 0, 1, 109, 0, 0, 0, 4,
> 116, 101, 120, 116, 109, 0, 0, 0, 11, 84, 69, 88, 84, 32, 65, 78, 83,
> ...>>}

Here is some example data that will just pass fine:
%{"B2_Q18" => [%{"choice_id" => "B2_Q18_C1"}], "B3_B9_Q1" => [%{"choice_id"
=> "B3_B9_Q1_C1"}], "B2_Q7" => [%{"choice_id" => "B2_Q7_C1"}], "B5_B1_Q8"
=> [%{"choice_id" => "B5_B1_Q8_C1"}], "B3_B6_Q1" => [%{"choice_id" =>
"B3_B6_Q1_C1"}], "B5_B2_Q5" => [%{"choice_id" => "B5_B2_Q5_C1"},
%{"choice_id" => "B5_B2_Q5_C2"}], "B3_B7_Q1" => [%{"choice_id" =>
"B3_B7_Q1_C1"}], "B3_B4_Q1" => [%{"choice_id" => "B3_B4_Q1_C1"}], "B2_Q16"
=> [%{"choice_id" => "B2_Q16_C1"}], "B2_Q20" => [%{"choice_id" =>
"B2_Q20_C1"}], "B2_Q5" => [%{"choice_id" => "B2_Q5_C1"}], "B2_Q9" =>
[%{"choice_id" => "B2_Q9_C1"}], "B2_Q17" => [%{"choice_id" =>
"B2_Q17_C1"}], "B3_B2_Q1" => [%{"choice_id" => "B3_B2_Q1_C1"}], "B5_B2_Q3"
=> [%{"choice_id" => "B5_B2_Q3_C1"}], "B3_B3_Q1" => [%{"choice_id" =>
"B3_B3_Q1_C1"}], "B5_B1_Q1" => [%{"text" => "TEXT ANSWER"}], "B2_Q14" =>
[%{"choice_id" => "B2_Q14_C1"}], "B5_B1_Q3" => [%{"choice_id" =>
"B5_B1_Q3_C22"}], "B5_B2_Q2" => [%{"choice_id" => "B5_B2_Q2_C1"}], "B2_Q4"
=> [%{"choice_id" => "B2_Q4_C1"}], "B2_Q10" => [%{"choice_id" =>
"B2_Q10_C1"}], "B4_Q1" => [%{"choice_id" => "B4_Q1_C1"}, %{"choice_id" =>
"B4_Q1_C10"}], "B5_B1_Q6" => [%{"choice_id" => "B5_B1_Q6_C1"}], "B2_Q6" =>
[%{"choice_id" => "B2_Q6_C1"}], "B2_Q2" => [%{"choice_id" => "B2_Q2_C1"}],
"B2_Q1" => [%{"choice_id" => "B2_Q1_C1"}]}

The moment I make it slightly longer, by like appending an extra key "a" =>
"b" it will give me the above error.

It seems to be that the size of the keys plays an issue here, because if I
convert all the above "choice_id" keys to a mere "c", then even with the
extra entry "a" => "b" included like following below will work just fine:
%{"B2_Q18" => [%{"c" => "B2_Q18_C1"}], "B3_B9_Q1" => [%{"c" =>
"B3_B9_Q1_C1"}], "B2_Q7" => [%{"c" => "B2_Q7_C1"}], "B5_B1_Q8" => [%{"c" =>
"B5_B1_Q8_C1"}], "B3_B6_Q1" => [%{"c" => "B3_B6_Q1_C1"}], "B5_B2_Q5" =>
[%{"c" => "B5_B2_Q5_C1"}, %{"c" => "B5_B2_Q5_C2"}], "B3_B7_Q1" => [%{"c" =>
"B3_B7_Q1_C1"}], "B3_B4_Q1" => [%{"c" => "B3_B4_Q1_C1"}], "B2_Q16" =>
[%{"c" => "B2_Q16_C1"}], "B2_Q20" => [%{"c" => "B2_Q20_C1"}], "B2_Q5" =>
[%{"c" => "B2_Q5_C1"}], "B2_Q9" => [%{"c" => "B2_Q9_C1"}], "B2_Q17" =>
[%{"c" => "B2_Q17_C1"}], "B3_B2_Q1" => [%{"c" => "B3_B2_Q1_C1"}],
"B5_B2_Q3" => [%{"c" => "B5_B2_Q3_C1"}], "B3_B3_Q1" => [%{"c" =>
"B3_B3_Q1_C1"}], "B5_B1_Q1" => [%{"text" => "TEXT ANSWER"}], "B2_Q14" =>
[%{"c" => "B2_Q14_C1"}], "B5_B1_Q3" => [%{"c" => "B5_B1_Q3_C22"}],
"B5_B2_Q2" => [%{"c" => "B5_B2_Q2_C1"}], "B2_Q4" => [%{"c" => "B2_Q4_C1"}],
"B2_Q10" => [%{"c" => "B2_Q10_C1"}], "B4_Q1" => [%{"c" => "B4_Q1_C1"},
%{"c" => "B4_Q1_C10"}], "B5_B1_Q6" => [%{"c" => "B5_B1_Q6_C1"}], "B2_Q6" =>
[%{"c" => "B2_Q6_C1"}], "B2_Q2" => [%{"c" => "B2_Q2_C1"}], "B2_Q1" =>
[%{"c" => "B2_Q1_C1"}], "a" => "b"}

The following on the other hand will just fail:
data =
%{"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
=> "q",
"bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb"
=> "q",
"ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc"
=> "q"}
:gen_tcp.send(client_socket, :erlang.term_to_binary(data))

The only issue that I was able to track down here is a conjunction of two
things:
1) A limit to the size of total key length inside a map/hash
2) sending that hash as a binary over tcp and converting back to term

In all of the above cases, a direct conversion of :erlang.term_to_binary
followed by :erlang.binary_to_term works just fine without any issues. The
issue only comes about after that binary was send over tcp and then
:erlang.binary_to_term is attempted.

I would greatly appreciate if anyone can provide me guidance in this
matter, point out to me any relevant documentation that officially states
any of these constraints if they are in fact constraints, and if they are
not supposed to be constraints then kindly instruct me what additional
information may be needed for me to get to the bottom of this.

Thank you.
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