Sorry - I was going down the wrong path.. Sure MPI_COMM_WORLD vs PETSC_COMM_WORLD shouldn't make a difference [except for a couple of extra mpi_comm_dup() calls.]
Satish On Tue, 3 Apr 2018, Derek Gaston wrote: > I’m working with Fande on this and I would like to add a bit more. There > are many circumstances where we aren’t working on COMM_WORLD at all (e.g. > working on a sub-communicator) but PETSc was initialized using > MPI_COMM_WORLD (think multi-level solves)… and we need to create > arbitrarily many PETSc vecs/mats/solvers/preconditioners and solve. We > definitely can’t rely on using PETSC_COMM_WORLD to avoid triggering > duplication. > > Can you explain why PETSc needs to duplicate the communicator so much? > > Thanks for your help in tracking this down! > > Derek > > On Mon, Apr 2, 2018 at 5:44 PM Kong, Fande <[email protected]> wrote: > > > Why we do not use user-level MPI communicators directly? What are > > potential risks here? > > > > > > Fande, > > > > On Mon, Apr 2, 2018 at 5:08 PM, Satish Balay <[email protected]> wrote: > > > >> PETSC_COMM_WORLD [via PetscCommDuplicate()] attempts to minimize calls to > >> MPI_Comm_dup() - thus potentially avoiding such errors > >> > >> > >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mcs.anl.gov_petsc_petsc-2Dcurrent_docs_manualpages_Sys_PetscCommDuplicate.html&d=DwIBAg&c=54IZrppPQZKX9mLzcGdPfFD1hxrcB__aEkJFOKJFd00&r=DUUt3SRGI0_JgtNaS3udV68GRkgV4ts7XKfj2opmiCY&m=jgv7gpZ3K52d_FWMgkK9yEScbLA7pkrWydFuJnYflsU&s=_zpWRcyk3kHuEHoq02NDqYExnXIohXpNnjyabYnnDjU&e= > > > > > >> > >> Satish > >> > >> On Mon, 2 Apr 2018, Kong, Fande wrote: > >> > >> > On Mon, Apr 2, 2018 at 4:23 PM, Satish Balay <[email protected]> wrote: > >> > > >> > > Does this 'standard test' use MPI_COMM_WORLD' to crate PETSc objects? > >> > > > >> > > If so - you could try changing to PETSC_COMM_WORLD > >> > > > >> > > >> > > >> > I do not think we are using PETSC_COMM_WORLD when creating PETSc > >> objects. > >> > Why we can not use MPI_COMM_WORLD? > >> > > >> > > >> > Fande, > >> > > >> > > >> > > > >> > > Satish > >> > > > >> > > > >> > > On Mon, 2 Apr 2018, Kong, Fande wrote: > >> > > > >> > > > Hi All, > >> > > > > >> > > > I am trying to upgrade PETSc from 3.7.6 to 3.8.3 for MOOSE and its > >> > > > applications. I have a error message for a standard test: > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > *preconditioners/pbp.lots_of_variables: MPI had an > >> > > > errorpreconditioners/pbp.lots_of_variables: > >> > > > ------------------------------------------------ > >> > > preconditioners/pbp.lots_of_variables: > >> > > > Other MPI error, error stack:preconditioners/pbp.lots_of_variables: > >> > > > PMPI_Comm_dup(177)..................: MPI_Comm_dup(comm=0x84000001, > >> > > > new_comm=0x97d1068) failedpreconditioners/pbp.lots_of_variables: > >> > > > PMPI_Comm_dup(162)..................: > >> > > > preconditioners/pbp.lots_of_variables: > >> > > > MPIR_Comm_dup_impl(57)..............: > >> > > > preconditioners/pbp.lots_of_variables: > >> > > > MPIR_Comm_copy(739).................: > >> > > > preconditioners/pbp.lots_of_variables: > >> > > > MPIR_Get_contextid_sparse_group(614): Too many communicators (0/2048 > >> > > free > >> > > > on this process; ignore_id=0)* > >> > > > > >> > > > > >> > > > I did "git bisect', and the following commit introduces this issue: > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > > >> > > > *commit 49a781f5cee36db85e8d5b951eec29f10ac13593Author: Stefano > >> Zampini > >> > > > <[email protected] <[email protected]>>Date: Sat > >> Nov 5 > >> > > > 20:15:19 2016 +0300 PCHYPRE: use internal Mat of type MatHYPRE > >> > > > hpmat already stores two HYPRE vectors* > >> > > > > >> > > > Before I debug line-by-line, anyone has a clue on this? > >> > > > > >> > > > > >> > > > Fande, > >> > > > > >> > > > >> > > > >> > > >> > >> >
