func main() {
var message int
var tag int = 201
mpi.Init()
defer mpi.Finalize()
rank := mpi.Comm_rank(mpi.COMM_WORLD)
size := mpi.Comm_size(mpi.COMM_WORLD)
/* Calculate the rank of the next process in the ring. Use the
modulus operator so that the last process "wraps around" to
rank zero. */
next := (rank + 1) % size
prev := (rank + size - 1) % size
/* If we are the "master" process (i.e., MPI_COMM_WORLD rank 0),
put the number of times to go around the ring in the
message. */
if 0 == rank {
message = 10
fmt.Printf("Process 0 sending %d to %d, tag %d (%d processes in ring)\n",
message, next, tag, size)
mpi.Send(&message, 1, mpi.INT, next, tag, mpi.COMM_WORLD)
fmt.Printf("Process 0 sent to %d\n", next)
}
/* Pass the message around the ring. The exit mechanism works as
follows: the message (a positive integer) is passed around the
ring. Each time it passes rank 0, it is decremented. When
each processes receives a message containing a 0 value, it
passes the message on to the next process and then quits. By
passing the 0 message first, every process gets the 0 message
and can quit normally. */
for true {
mpi.Recv(&message, 1, mpi.INT, prev, tag, mpi.COMM_WORLD, mpi.STATUS_IGNORE)
if 0 == rank {
message--
fmt.Printf("Process 0 decremented value: %d\n", message)
}
mpi.Send(&message, 1, mpi.INT, next, tag, mpi.COMM_WORLD)
if 0 == message {
fmt.Printf("Process %d exiting\n", rank)
break
}
}
/* The last process does one extra send to process 0, which needs
to be received before the program can exit */
if 0 == rank {
mpi.Recv(&message, 1, mpi.INT, prev, tag, mpi.COMM_WORLD, mpi.STATUS_IGNORE)
}
}
func main() {
mpi.Init()
defer mpi.Finalize()
rank := mpi.Comm_rank(mpi.COMM_WORLD)
size := mpi.Comm_size(mpi.COMM_WORLD)
var message int
if rank == 0 {
message = 60
for i := 1; i < size; i++ {
fmt.Printf("root sending message to %d\n", i)
mpi.Send(&message, 1, mpi.INT, i, 10, mpi.COMM_WORLD)
}
} else {
mpi.Recv(&message, 1, mpi.INT, 0, 10, mpi.COMM_WORLD, mpi.STATUS_IGNORE)
}
mpi.Barrier(mpi.COMM_WORLD)
}