When trying to run the psum.py example on a ipcluster with 4 nodes/engines with the follwing input (compared to the presented example the array a is different on each engine in my case)
view.scatter('a',np.linspace(0.0, 15.0, 16))
px s = psum(a)
view['s'] returns [6.0, 22.0, 38.0, 54.0] instead of the expected output [120,120,120,120]
However, if i run the psum example manually (in the bash with mpirun -np 4 python psum.py ) the output is correct. The psum.py file used for this test contains
from mpi4py import MPI
import numpy as np
def psum(a):
s = np.sum(a)
rcvBuf = np.array(0.0,'d')
MPI.COMM_WORLD.Allreduce([s, MPI.DOUBLE],
[rcvBuf, MPI.DOUBLE],
op=MPI.SUM)
return rcvBuf
if __name__ == '__main__':
rank = MPI.COMM_WORLD.Get_rank()
a = np.linspace(rank*4.0,(rank+1)*4.0-1,4)
print "a:", a
result = psum(a)
print "result:", result
and when run with mpirun it outputs
a: [ 4. 5. 6. 7.]
a: [ 8. 9. 10. 11.]
a: [ 12. 13. 14. 15.]
a: [ 0. 1. 2. 3.]
result: 120.0
result: 120.0
result: 120.0
result: 120.0
Any ideas?
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