erlang--echo_server

Server:

-module(echo).
-export([listen/1]).
-define(TCP_OPTIONS, [binary, {packet, 0}, {active, false}, {reuseaddr,true}]).
% Call echo:listen(Port) to start the service.
listen(Port) ->
    {ok, LSocket} = gen_tcp:listen(Port, ?TCP_OPTIONS),
    spawn(fun()->accept1(LSocket) end),
    spawn(fun()->accept2(LSocket) end).
% Wait for incoming connections and spawn the echo loop when we get one.
accept1(LSocket) ->
    {ok, Socket} = gen_tcp:accept(LSocket),
    spawn(fun() -> loop(Socket) end),
    accept1(LSocket).
   
accept2(LSocket) ->
    {ok, Socket} = gen_tcp:accept(LSocket),
    spawn(fun() -> loop(Socket) end),
    accept2(LSocket).   
% Echo back whatever data we receive on Socket.
loop(Socket) ->
    case gen_tcp:recv(Socket, 0) of
        {ok, Data} ->
            %%gen_tcp:send(Socket, Data),
       %io:format("  ~p~n", [Data]),
            loop(Socket);
        {error, closed} ->
            ok
    end.

Client:

-module(stress_test).
-export([start/0]).

start() ->
    tests(7789).

tests(Port) ->
    io:format("starting~n"),
    spawn(fun() -> test(Port) end), 
    spawn(fun() -> test(Port) end),
    spawn(fun() -> test(Port) end),
    spawn(fun() -> test(Port) end).

test(Port) ->
    case gen_tcp:connect("127.0.0.1", Port, [binary, {packet, 0}]) of
        {ok, _} ->
            test(Port);
        _ ->
            test(Port)
    end.