gen_tcp:send and file:sendfile

Slava Yurin <[email protected]>
Newsgroups gmane.comp.lang.erlang.bugs
Message-ID <[email protected]> 
Hi all.

I have error behavior of gen_tcp:send/2 + file:sendfile/5.

If data for send falls into buffer in port and happen file:sendfile/5 call, then

buffer not flushed and data from file send. After that any call gen_tcp:send/2

only append data to buffer and not send anything. And if not set send_timeout

option gen_tcp:send will hang after exceed size of buffer. This is my guess.

I attach test file and log of it usage.

Have reproducible error only when [{delay_send, true}, {nodelay, false}], but in

real usage see same behavior without this options. Can't reproduce it on

localhost and 1 file.

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send_file_test.erl (application/octet-stream, 1.2 KB) - not displayed
shell1.log (text/plain, 4.2 KB) 
v.yurin@hell:~$ uname -a
Linux hell 3.17.3-1-ARCH #1 SMP PREEMPT Fri Nov 14 23:13:48 CET 2014 x86_64 GNU/Linux
v.yurin@hell:~/test$ erl
Erlang/OTP 17 [erts-6.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V6.2  (abort with ^G)
1> L = send_file_test:start().
Listen on 59690
#Port<0.563>
2> send_file_test:one_client(L, [], 1).
ok
Send file 1
3> send_file_test:one_client(L, [{delay_send, true}, {nodelay, false}], 1). 
ok
Send file 1
4> send_file_test:one_client(L, [{delay_send, true}, {nodelay, false}, {send_timeout, 1000}], 200).                                                        
ok
Send file 200
Send file 199
Send file 198
Send file 197
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5> 
=ERROR REPORT==== 10-Dec-2014::12:45:28 ===
Error in process <0.40.0> with exit value: {{badmatch,{error,timeout}},[{send_file_test,loop,3,[{file,"send_file_test.erl"},{line,37}]}]}

5> send_file_test:one_client(L, [{delay_send, true}, {nodelay, false}], 200).       ok             
Send file 200
Send file 199
Send file 198
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6> now().
{1418,194038,215600}
7> now().
{1418,194077,282560}
8> "send hang ...".
shell2.log (text/plain, 5.4 KB) 
v.yurin@hell:~$ telnet 127.0.0.1 59690
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
start
Some data before file
File 1:
%% @author Slava Yurin <[email protected]>
%% @doc Test Sendfile
-module(send_file_test).

-export([one_client/3]).
-export([start/0]).

start() ->
	{ok, Listen} = gen_tcp:listen(0, [{active, false}, {ip, {127, 0, 0, 1}}]),
	{ok, Port} = inet:port(Listen),
	io:format("Listen on ~p~n", [Port]),
	Listen.

one_client(Listen, Opt, FileCount) ->
	{ok, Client} = gen_tcp:accept(Listen),
	%Opt = [{delay_send, false}, {nodelay, true}],
	%Opt = [{delay_send, true}, {nodelay, false}],
	ok = inet:setopts(Client, [binary, {packet, line}, {active, false} | Opt]),
	Pid = spawn(fun() -> loop(Client, FileCount) end),
	ok = gen_tcp:controlling_process(Client, Pid),
	Pid ! start,
	ok.

loop(Client, FileCount) ->
	receive start -> ok end,
	{ok, <<"start\r\n">>} = gen_tcp:recv(Client, 0),
	{ok, FD} = file:open("send_file_test.erl", [raw, read, binary]),
	loop(Client, FD, FileCount).

loop(_, _, 0) ->
	ok;
loop(Client, FD, Pos) ->
	io:format("Send file ~p~n", [Pos]),
	ok = gen_tcp:send(Client,
		["Some data before file\r\nFile ", integer_to_list(Pos), ":\r\n"]),
	{ok, _} = file:sendfile(FD, Client, 0, 0, []),
	ok = gen_tcp:send(Client, ["File ", integer_to_list(Pos), " end\r\nSome data after file\r\n"]),
	loop(Client, FD, Pos - 1).
File 1 end
Some data after file
Connection closed by foreign host.
v.yurin@hell:~$ telnet 127.0.0.1 59690
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
start
%% @author Slava Yurin <[email protected]>
%% @doc Test Sendfile
-module(send_file_test).

-export([one_client/3]).
-export([start/0]).

start() ->
	{ok, Listen} = gen_tcp:listen(0, [{active, false}, {ip, {127, 0, 0, 1}}]),
	{ok, Port} = inet:port(Listen),
	io:format("Listen on ~p~n", [Port]),
	Listen.

one_client(Listen, Opt, FileCount) ->
	{ok, Client} = gen_tcp:accept(Listen),
	%Opt = [{delay_send, false}, {nodelay, true}],
	%Opt = [{delay_send, true}, {nodelay, false}],
	ok = inet:setopts(Client, [binary, {packet, line}, {active, false} | Opt]),
	Pid = spawn(fun() -> loop(Client, FileCount) end),
	ok = gen_tcp:controlling_process(Client, Pid),
	Pid ! start,
	ok.

loop(Client, FileCount) ->
	receive start -> ok end,
	{ok, <<"start\r\n">>} = gen_tcp:recv(Client, 0),
	{ok, FD} = file:open("send_file_test.erl", [raw, read, binary]),
	loop(Client, FD, FileCount).

loop(_, _, 0) ->
	ok;
loop(Client, FD, Pos) ->
	io:format("Send file ~p~n", [Pos]),
	ok = gen_tcp:send(Client,
		["Some data before file\r\nFile ", integer_to_list(Pos), ":\r\n"]),
	{ok, _} = file:sendfile(FD, Client, 0, 0, []),
	ok = gen_tcp:send(Client, ["File ", integer_to_list(Pos), " end\r\nSome data after file\r\n"]),
	loop(Client, FD, Pos - 1).
Connection closed by foreign host.
v.yurin@hell:~$ telnet 127.0.0.1 59690
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
start


[ ... skip ... ]


%% @author Slava Yurin <[email protected]>
%% @doc Test Sendfile
-module(send_file_test).

-export([one_client/3]).
-export([start/0]).

start() ->
	{ok, Listen} = gen_tcp:listen(0, [{active, false}, {ip, {127, 0, 0, 1}}]),
	{ok, Port} = inet:port(Listen),
	io:format("Listen on ~p~n", [Port]),
	Listen.

one_client(Listen, Opt, FileCount) ->
	{ok, Client} = gen_tcp:accept(Listen),
	%Opt = [{delay_send, false}, {nodelay, true}],
	%Opt = [{delay_send, true}, {nodelay, false}],
	ok = inet:setopts(Client, [binary, {packet, line}, {active, false} | Opt]),
	Pid = spawn(fun() -> loop(Client, FileCount) end),
	ok = gen_tcp:controlling_process(Client, Pid),
	Pid ! start,
	ok.

loop(Client, FileCount) ->
	receive start -> ok end,
	{ok, <<"start\r\n">>} = gen_tcp:recv(Client, 0),
	{ok, FD} = file:open("send_file_test.erl", [raw, read, binary]),
	loop(Client, FD, FileCount).

loop(_, _, 0) ->
	ok;
loop(Client, FD, Pos) ->
	io:format("Send file ~p~n", [Pos]),
	ok = gen_tcp:send(Client,
		["Some data before file\r\nFile ", integer_to_list(Pos), ":\r\n"]),
	{ok, _} = file:sendfile(FD, Client, 0, 0, []),
	ok = gen_tcp:send(Client, ["File ", integer_to_list(Pos), " end\r\nSome data after file\r\n"]),
	loop(Client, FD, Pos - 1).
Connection closed by foreign host.
v.yurin@hell:~$ telnet 127.0.0.1 59690
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
start


[ ... skip ... ]


%% @author Slava Yurin <[email protected]>
%% @doc Test Sendfile
-module(send_file_test).

-export([one_client/3]).
-export([start/0]).

start() ->
	{ok, Listen} = gen_tcp:listen(0, [{active, false}, {ip, {127, 0, 0, 1}}]),
	{ok, Port} = inet:port(Listen),
	io:format("Listen on ~p~n", [Port]),
	Listen.

one_client(Listen, Opt, FileCount) ->
	{ok, Client} = gen_tcp:accept(Listen),
	%Opt = [{delay_send, false}, {nodelay, true}],
	%Opt = [{delay_send, true}, {nodelay, false}],
	ok = inet:setopts(Client, [binary, {packet, line}, {active, false} | Opt]),
	Pid = spawn(fun() -> loop(Client, FileCount) end),
	ok = gen_tcp:controlling_process(Client, Pid),
	Pid ! start,
	ok.

loop(Client, FileCount) ->
	receive start -> ok end,
	{ok, <<"start\r\n">>} = gen_tcp:recv(Client, 0),
	{ok, FD} = file:open("send_file_test.erl", [raw, read, binary]),
	loop(Client, FD, FileCount).

loop(_, _, 0) ->
	ok;
loop(Client, FD, Pos) ->
	io:format("Send file ~p~n", [Pos]),
	ok = gen_tcp:send(Client,
		["Some data before file\r\nFile ", integer_to_list(Pos), ":\r\n"]),
	{ok, _} = file:sendfile(FD, Client, 0, 0, []),
	ok = gen_tcp:send(Client, ["File ", integer_to_list(Pos), " end\r\nSome data after file\r\n"]),
	loop(Client, FD, Pos - 1).
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