> On 31 Jan 2024, at 11:31 AM, Alain O' Miniussi <alain.miniu...@oca.eu> wrote: > > Hi, > > It is indicated in: > https://petsc.org/release/manualpages/Sys/PetscInitialize/ > that the init function will call MPI_Init. > > What if MPI_Init was already called (as it is the case in my application) and > what about MPI_Init_thread.
Then, MPI_Init() is not called, see the call to MPI_Initialized() in https://petsc.org/release/src/sys/objects/pinit.c.html#PetscInitialize. > Wouldn't it be more convenient to have a Petsc init function taking a already > initialized communicator as argument ? > > Also, that initialization seems to imply that it is not possible to have > multiple instance of PETSc on different communicators. Is that the case ? No, you can initialize MPI yourself and then set PETSC_COMM_WORLD to whatever you need before calling PetscInitialize(). Thanks, Pierre > Thanks > > ---- > Alain Miniussi > DSI, Pôles Calcul et Genie Log. > Observatoire de la Côte d'Azur > Tél. : +33609650665
