Create group communicator in mpi (mpi4py)
I am trying to create an MPI group using mpi4py. My current attempt looks like this:
from mpi4py import MPI
comm = MPI.COMM_WORLD
newGroup = comm.group.Excl([0, 1, 2])
print newGroup.size
newComm = comm.Create_group(newGroup)
print newComm
print newComm.Get_size()
The newGroup.size call does return 2 (I started the application with 5 processes) and the newComm variable indicates to be a communicator. But as soon as I try to call Get_size an exception is thrown:
mpi4py.MPI.Exception: MPI_ERR_COMM: invalid communicator
How can I create a new communicator based on a predefined sequence of process IDs?
python mpi mpi4py
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
add a comment |
I am trying to create an MPI group using mpi4py. My current attempt looks like this:
from mpi4py import MPI
comm = MPI.COMM_WORLD
newGroup = comm.group.Excl([0, 1, 2])
print newGroup.size
newComm = comm.Create_group(newGroup)
print newComm
print newComm.Get_size()
The newGroup.size call does return 2 (I started the application with 5 processes) and the newComm variable indicates to be a communicator. But as soon as I try to call Get_size an exception is thrown:
mpi4py.MPI.Exception: MPI_ERR_COMM: invalid communicator
How can I create a new communicator based on a predefined sequence of process IDs?
python mpi mpi4py
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
add a comment |
I am trying to create an MPI group using mpi4py. My current attempt looks like this:
from mpi4py import MPI
comm = MPI.COMM_WORLD
newGroup = comm.group.Excl([0, 1, 2])
print newGroup.size
newComm = comm.Create_group(newGroup)
print newComm
print newComm.Get_size()
The newGroup.size call does return 2 (I started the application with 5 processes) and the newComm variable indicates to be a communicator. But as soon as I try to call Get_size an exception is thrown:
mpi4py.MPI.Exception: MPI_ERR_COMM: invalid communicator
How can I create a new communicator based on a predefined sequence of process IDs?
python mpi mpi4py
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
I am trying to create an MPI group using mpi4py. My current attempt looks like this:
from mpi4py import MPI
comm = MPI.COMM_WORLD
newGroup = comm.group.Excl([0, 1, 2])
print newGroup.size
newComm = comm.Create_group(newGroup)
print newComm
print newComm.Get_size()
The newGroup.size call does return 2 (I started the application with 5 processes) and the newComm variable indicates to be a communicator. But as soon as I try to call Get_size an exception is thrown:
mpi4py.MPI.Exception: MPI_ERR_COMM: invalid communicator
How can I create a new communicator based on a predefined sequence of process IDs?
python mpi mpi4py
python mpi mpi4py
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
asked Nov 20 '18 at 22:05
WoltanWoltan
8,776126285
8,776126285
add a comment |
add a comment |
1 Answer
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newComm is a legit communicator on tasks [3-4], but is MPI_COMM_NULL on tasks [0-2]. The standard does not allow you to invoke MPI_Comm_size(MPI_COMM_NULL, ...), and hence your error.
The solution is to call newComm.Get_size() explicitly on tasks [3-4], or on any tasks where newComm is not MPI_COMM_NULL.
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
newComm is a legit communicator on tasks [3-4], but is MPI_COMM_NULL on tasks [0-2]. The standard does not allow you to invoke MPI_Comm_size(MPI_COMM_NULL, ...), and hence your error.
The solution is to call newComm.Get_size() explicitly on tasks [3-4], or on any tasks where newComm is not MPI_COMM_NULL.
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
add a comment |
newComm is a legit communicator on tasks [3-4], but is MPI_COMM_NULL on tasks [0-2]. The standard does not allow you to invoke MPI_Comm_size(MPI_COMM_NULL, ...), and hence your error.
The solution is to call newComm.Get_size() explicitly on tasks [3-4], or on any tasks where newComm is not MPI_COMM_NULL.
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
add a comment |
newComm is a legit communicator on tasks [3-4], but is MPI_COMM_NULL on tasks [0-2]. The standard does not allow you to invoke MPI_Comm_size(MPI_COMM_NULL, ...), and hence your error.
The solution is to call newComm.Get_size() explicitly on tasks [3-4], or on any tasks where newComm is not MPI_COMM_NULL.
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
newComm is a legit communicator on tasks [3-4], but is MPI_COMM_NULL on tasks [0-2]. The standard does not allow you to invoke MPI_Comm_size(MPI_COMM_NULL, ...), and hence your error.
The solution is to call newComm.Get_size() explicitly on tasks [3-4], or on any tasks where newComm is not MPI_COMM_NULL.
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
answered Nov 21 '18 at 0:04
Gilles GouaillardetGilles Gouaillardet
4,52951323
4,52951323
add a comment |
add a comment |
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