Rick, I re-read the MPI standard and was unable to figure out if sensorgroup is MPI_GROUP_EMPTY or a group with task 1 on tasks except task 1 (A group that does not contain the current task makes little sense to me, but I do not see any reason why this group have to be MPI_GROUP_EMPTY)
Regardless, sensorComm will be MPI_COMM_NULL except on task 1, so MPI_Barrier will fail. Cheers, Gilles On Monday, October 17, 2016, Marlborough, Rick <rmarlboro...@aaccorp.com> wrote: > Designation: Non-Export Controlled Content > > George; > > Thanks for your response. Your second sentence is a little > confusing. If my world group is P0,P1, visible on both processes, why > wouldn’t the sensorList contain P1 on both processes? > > > > Rick > > > > > > *From:* users [mailto:users-boun...@lists.open-mpi.org > <javascript:_e(%7B%7D,'cvml','users-boun...@lists.open-mpi.org');>] *On > Behalf Of *George Bosilca > *Sent:* Friday, October 14, 2016 5:44 PM > *To:* Open MPI Users > *Subject:* Re: [OMPI users] communications groups > > > > Rick, > > > > Let's assume that you have started 2 processes, and that your sensorList > is {1}. The worldgroup will then be {P0, P1}, which trimmed via the > sensorList will give the sensorgroup {MPI_GROUP_EMPTY} on P0 and the > sensorgroup {P1} on P1. As a result on P0 you will create a > MPI_COMM_NULL communicator, while on P1 you will have a valid communicator > sensorComm (which will only contain P1). You cannot do a Barrier on an > MPI_COMM_NULL communicator, which might explain the "invalid communicator" > error you are getting. > > > > George. > > > > > > On Fri, Oct 14, 2016 at 5:33 PM, Marlborough, Rick < > rmarlboro...@aaccorp.com > <javascript:_e(%7B%7D,'cvml','rmarlboro...@aaccorp.com');>> wrote: > > Designation: Non-Export Controlled Content > > Folks; > > I have the following code setup. The sensorList is an > array of ints of size 1. The value it contains is 1. My comm world size is > 5. The call to MPI_Barrier fails every time with error “invalid > communicator”. This code is pretty much copied out of a text book. I must > be doing something wrong. I just don’t see it. Can anyone else spot my > error? I am using v2.01 on red hat 6.5. > > > > Thanks > > Rick > > > > > > MPI_Comm_group(MPI_COMM_WORLD, &worldgroup); > > MPI_Group_incl(worldgroup, 1, sensorList, &sensorgroup); > > MPI_Comm_create(MPI_COMM_WORLD, sensorgroup, &sensorComm); > > MPI_Barrier(sensorComm); > > 3.1.1001 > > > _______________________________________________ > users mailing list > users@lists.open-mpi.org > <javascript:_e(%7B%7D,'cvml','users@lists.open-mpi.org');> > https://rfd.newmexicoconsortium.org/mailman/listinfo/users > > > > 3.1.1001 >
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