Parallel Server - Is it better to spawn a new per-connection handler, or spawn a new accepting process?...





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I'm reading the "Using TCP" chapter of "Software for a Concurrent World", and the parallel TCP server confuses me.



Rather than looping and spawning a new handler process for each connection, it spawns a new acceptor process – i.e. it continuously spawns copies of itself.



%% Parallel TCP Server (From the book)

par_start(Port) ->
{ok, Sock} = gen_tcp:listen(Port, [{packet, line}]),
spawn(fun() -> par_connect(Sock) end).

par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).

handle(Conn) ->
receive
{tcp, Socket, Bin} ->
io:format("Data: ~p~n", [Bin]),
gen_tcp:send(Socket, Bin),
handle(Conn);
{error, closed} ->
io:format("Connection closed: ~p~n", [Conn])
end.


I find this bit confusing:



par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).


Is there a benefit to handling the connection in the process that accepts it, rather than spawning a new handler for each connection?



Spawning new handler for each connection:



connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Handle connection in different process
Handler = spawn(fun() -> handle(Conn) end),
gen_tcp:controlling_process(Conn, Handler),
% Loop to accept more connections
connect(Sock).


It does avoid a call to gen_tcp:controlling_process(..). Is it faster to skip this, and instead spawn a new process?










share|improve this question


















  • 1





    Yes, it is. you're right.

    – Pouriya
    Nov 17 '18 at 12:32


















1















I'm reading the "Using TCP" chapter of "Software for a Concurrent World", and the parallel TCP server confuses me.



Rather than looping and spawning a new handler process for each connection, it spawns a new acceptor process – i.e. it continuously spawns copies of itself.



%% Parallel TCP Server (From the book)

par_start(Port) ->
{ok, Sock} = gen_tcp:listen(Port, [{packet, line}]),
spawn(fun() -> par_connect(Sock) end).

par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).

handle(Conn) ->
receive
{tcp, Socket, Bin} ->
io:format("Data: ~p~n", [Bin]),
gen_tcp:send(Socket, Bin),
handle(Conn);
{error, closed} ->
io:format("Connection closed: ~p~n", [Conn])
end.


I find this bit confusing:



par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).


Is there a benefit to handling the connection in the process that accepts it, rather than spawning a new handler for each connection?



Spawning new handler for each connection:



connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Handle connection in different process
Handler = spawn(fun() -> handle(Conn) end),
gen_tcp:controlling_process(Conn, Handler),
% Loop to accept more connections
connect(Sock).


It does avoid a call to gen_tcp:controlling_process(..). Is it faster to skip this, and instead spawn a new process?










share|improve this question


















  • 1





    Yes, it is. you're right.

    – Pouriya
    Nov 17 '18 at 12:32














1












1








1








I'm reading the "Using TCP" chapter of "Software for a Concurrent World", and the parallel TCP server confuses me.



Rather than looping and spawning a new handler process for each connection, it spawns a new acceptor process – i.e. it continuously spawns copies of itself.



%% Parallel TCP Server (From the book)

par_start(Port) ->
{ok, Sock} = gen_tcp:listen(Port, [{packet, line}]),
spawn(fun() -> par_connect(Sock) end).

par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).

handle(Conn) ->
receive
{tcp, Socket, Bin} ->
io:format("Data: ~p~n", [Bin]),
gen_tcp:send(Socket, Bin),
handle(Conn);
{error, closed} ->
io:format("Connection closed: ~p~n", [Conn])
end.


I find this bit confusing:



par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).


Is there a benefit to handling the connection in the process that accepts it, rather than spawning a new handler for each connection?



Spawning new handler for each connection:



connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Handle connection in different process
Handler = spawn(fun() -> handle(Conn) end),
gen_tcp:controlling_process(Conn, Handler),
% Loop to accept more connections
connect(Sock).


It does avoid a call to gen_tcp:controlling_process(..). Is it faster to skip this, and instead spawn a new process?










share|improve this question














I'm reading the "Using TCP" chapter of "Software for a Concurrent World", and the parallel TCP server confuses me.



Rather than looping and spawning a new handler process for each connection, it spawns a new acceptor process – i.e. it continuously spawns copies of itself.



%% Parallel TCP Server (From the book)

par_start(Port) ->
{ok, Sock} = gen_tcp:listen(Port, [{packet, line}]),
spawn(fun() -> par_connect(Sock) end).

par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).

handle(Conn) ->
receive
{tcp, Socket, Bin} ->
io:format("Data: ~p~n", [Bin]),
gen_tcp:send(Socket, Bin),
handle(Conn);
{error, closed} ->
io:format("Connection closed: ~p~n", [Conn])
end.


I find this bit confusing:



par_connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Spawn a new process to accept more connections
spawn(fun() -> par_connect(Sock) end),
handle(Conn).


Is there a benefit to handling the connection in the process that accepts it, rather than spawning a new handler for each connection?



Spawning new handler for each connection:



connect(Sock) ->
{ok, Conn} = gen_tcp:accept(Sock),
% Handle connection in different process
Handler = spawn(fun() -> handle(Conn) end),
gen_tcp:controlling_process(Conn, Handler),
% Loop to accept more connections
connect(Sock).


It does avoid a call to gen_tcp:controlling_process(..). Is it faster to skip this, and instead spawn a new process?







tcp server erlang






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asked Nov 17 '18 at 2:58









hazhaz

385423




385423








  • 1





    Yes, it is. you're right.

    – Pouriya
    Nov 17 '18 at 12:32














  • 1





    Yes, it is. you're right.

    – Pouriya
    Nov 17 '18 at 12:32








1




1





Yes, it is. you're right.

– Pouriya
Nov 17 '18 at 12:32





Yes, it is. you're right.

– Pouriya
Nov 17 '18 at 12:32












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