Getting multiple send commands using mpi4py

Question

How can I change the following code (adapted from http://materials.jeremybejarano.com/MPIwithPython/pointToPoint.html ) so that each instance is comm.Sendreceived root = 0and the output is printed. At the moment, only the first send command is accepted.

#passRandomDraw.py
import numpy
from mpi4py import MPI
from mpi4py.MPI import ANY_SOURCE
import numpy as np

comm = MPI.COMM_WORLD
rank = comm.Get_rank()

if rank == 0:
    randNum = numpy.zeros(1)
    print "Process before receiving random numbers"


else:
    for i in range(0,np.random.randint(1,10),1):
        randNum = numpy.zeros(1)
        randNum = numpy.random.random_sample(1)
        print "Process", rank, "iteration", i, "drew the number", randNum[0]
        comm.Send(randNum, dest=0)


if rank == 0:
   comm.Recv(randNum, ANY_SOURCE)
   print "Process", rank, "received the number", randNum[0]

Answer 1

, , , . , . , probe, ,

tag_data = 42
tag_end = 23

if rank == 0:
    randNum = numpy.zeros(1)
    print "Process before receiving random numbers"
else:
    for i in range(0,np.random.randint(1,10),1):
        randNum = numpy.zeros(1)
        randNum = numpy.random.random_sample(1)
        print "Process", rank, "iteration", i, "drew the number", randNum[0]
        comm.Send(randNum, dest=0, tag=tag_data)
    # send the termination message. Using the lower-case interface is simpler
    comm.send(None, dest=0, tag=tag_end)

if rank == 0:
    # For debugging it might be better to use a list of still active procsses
    remaining = comm.Get_size() - 1
    while remaining > 0:
        s = MPI.Status()
        comm.Probe(status=s)
        # make sure we post the right kind of message
        if s.tag == tag_data:
            comm.Recv(randNum, s.source, tag=tag_data)
            print "Process ", s.source, " received the number", randNum[0]
        elif s.tag == tag_end:
            # don't need the result here
            print "Process ", rank, " is done"
            comm.recv(source=s.source, tag=tag_end)
            remaining -= 1

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Answer 2

, :

1) , . , . , comm.reduce(...)

2) 0.

, , . mpirun -np 4 python main.py

#passRandomDraw.py
import numpy
from mpi4py import MPI
from mpi4py.MPI import ANY_SOURCE
import numpy as np

comm = MPI.COMM_WORLD
rank = comm.Get_rank()
size = comm.Get_size()

#just in case, if numpy.random is seed with 
np.random.seed(np.random.randint(np.iinfo(np.uint32).min,np.iinfo(np.uint32).max)+rank)

if rank == 0:
    randNum = numpy.zeros(1)
    print "Process before receiving random numbers"
    nb=np.empty((1,),dtype=int)
    nb0=np.zeros((1,),dtype=int)
    comm.Reduce([nb0, MPI.INT],[nb, MPI.INT],op=MPI.SUM, root=0)  #sums the total number of random number from every process on rank 0, in nb.
    #print "rank"+str(rank)+" nb "+str(nb)
else:
    nb=np.empty((1,),dtype=int)
    nb[0]=np.random.randint(1,10)
    #print "rank"+str(rank)+" nb "+str(nb)
    comm.Reduce([nb, MPI.INT],None,op=MPI.SUM, root=0)
    for i in range(0,nb[0],1):
        randNum = numpy.zeros(1)
        randNum = numpy.random.random_sample(1)
        print "Process", rank, "iteration", i, "drew the number", randNum[0]
        comm.Send(randNum, dest=0)



if rank == 0:
   for i in range(nb[0]): #receives nb message, each one with its int.
       comm.Recv(randNum, ANY_SOURCE)
       print "Process", rank, "received the number", randNum[0]

numpy.random() Mersenne Twister , /dev/urandom ( Windows), , . , . , :

np.random.seed(np.random.randint(np.iinfo(np.uint32).min,np.iinfo(np.uint32).max)+rank)