Resolviendo ejercicios de MPI (y tambien en erlang) Parte 2

enunciado del ejercicio 2

Write a program that reads an integer value from the terminal and distributes the value to all of the MPI processes. Each process should print out its rank and the value it received. Values should be read until a negative integer is given as input.

lo resolvi ahi nomas con MPI, lo corri y todo andaba bien excepto que los procesos no imprimian (excepto el rank 0), pelee, toque, agregue fflush(stdout) y printf's por todos lados (clasica estrategia de debugger artesanal de C :D) y nada, copie el ejercicio resuelto de la pagina y le pasa lo mismo, asi que asumo que es algo relacionado con que mi notebook no es un cluster y encima tiene un solo core. aunque no sirva de mucho, aca esta la resolucion en C:

#include <stdio.h>
#include <mpi.h>

int main (int argc, char** argv) {
int rank, size, value, i;
MPI_Status status;

MPI_Init (&argc, &argv);   /* starts MPI */
MPI_Comm_rank (MPI_COMM_WORLD, &rank);        /* get current process id */
MPI_Comm_size (MPI_COMM_WORLD, &size);        /* get number of processes */
printf("process %d of %d\n", rank, size);

do {
if(rank == 0) {
printf("give me a value: ");
scanf("%d", &value);
MPI_Bcast(&value, 1, MPI_INT, 0, MPI_COMM_WORLD);
}
else {
MPI_Recv(&value, 1, MPI_INT, 0, 1, MPI_COMM_WORLD, &status);
printf("process %d received %d\n", rank, value);
fflush(stdout);
}
} while(value >= 0);
printf("negative value, closing\n");

MPI_Finalize();
return 0;
}

-module(ej2).
-export([run/1]).

run(Total) ->
Pids = spawn_listeners(Total),
get_values(Pids).

spawn_listeners(Count) -> spawn_listeners(Count, []).

spawn_listeners(0, Pids) -> Pids;
spawn_listeners(Count, Pids) ->
Pid = spawn(fun() -> listener() end),
spawn_listeners(Count - 1, [Pid|Pids]).

listener() ->
receive
Number ->
io:format("process ~p received ~p~n", [self(), Number]),
if
Number >= 0 -> listener();
true ->
io:format("negative value, closing ~p~n", [self()])
end
end.

get_values(Pids) ->
case io:get_line("give me a value (negative to quit): ") of
{error, Reason} ->
io:format("error reading value (~p)~n", [Reason]);
eof ->
io:format("error reading value~n");
Value ->
case string:to_integer(Value) of
{error, Reason} ->
io:format("invalid value (~p)~n", [Reason]),
get_values(Pids);
{IntValue, _Rest} ->
send_values(IntValue, Pids),
if
IntValue >= 0 -> get_values(Pids);
true -> io:format("negative value, closing~n")
end
end
end.

send_values(Value, Pids) ->
lists:foreach(fun(Pid) -> Pid ! Value end, Pids).

• Si es la ultima sentencia de una funcion va con punto (a excepcion de que este haciendo pattern matching en cuyo caso todos menos la ultima son con punto y coma)
• Si es una sentencia comun dentro de una funcion termina en coma, a excepcion de que sea la ultima de la funcion (en cuyo caso punto o punto y coma como vimos arriba) pero tambien a excepcion de que sea la ultima de un if, case, receive en cuyo caso es ;, pero no si es la ultima del ultimo statement en cuyo caso no lleva nada.

$ erl
Erlang (BEAM) emulator version 5.6.5 [source] [async-threads:0] [kernel-poll:false]

Eshell V5.6.5  (abort with ^G)
1> c(ej2).
{ok,ej2}
2> ej2:run(4).
give me a value (negative to quit): 42
process  received 42
process  received 42
process  received 42
process  received 42
give me a value (negative to quit): 7
process  received 7
process  received 7
process  received 7
process  received 7
give me a value (negative to quit): -1
negative value, closing
process  received -1
process  received -1
process  received -1
process  received -1
negative value, closing 
negative value, closing 
negative value, closing 
negative value, closing 
ok
3> ej2:run(4).
give me a value (negative to quit): asd
invalid value (no_integer)
give me a value (negative to quit): -1
negative value, closing
process  received -1
process  received -1
process  received -1
process  received -1
negative value, closing 
negative value, closing 
negative value, closing 
negative value, closing 
ok
4>