With 4 million elements you are nowhere near the 32 but integer limit of 2B or 32Gb of memory.
See the https://petsc.org/main/docs/manualpages/Mat/MatView You should go to binary format when doing large matrices. Mark On Fri, Aug 12, 2022 at 1:00 PM Alfredo Jaramillo <[email protected]> wrote: > Hello Mark, > Thank you, I added the lines that you sent. > This only happens when running the code with more than 1 process. With > only 1 MPI process the matrix is printed out. > With 2 processes or more I observed the program begins to allocate RAM > until it exceeds the computer capacity (32GB) so I wasn't able to get the > stack trace. > > However, I was able to reproduce the problem by compiling > src/ksp/ksp/tutorials/ex54.c.html > <https://petsc.org/release/src/ksp/ksp/tutorials/ex54.c.html> (modifying > line 144) and running it with > > mpirun -np 2 ex54 -ne 1000 > > This gives a sparse matrix of order ~1 million. When running ex54 with > only one MPI process I don't observe this excessive allocation and the > matrix is printed out. > > Thanks, > Alfredo > > > > On Fri, Aug 12, 2022 at 10:02 AM Mark Adams <[email protected]> wrote: > >> You also want: >> >> PetscCall(PetscViewerPopFormat(viewer)); >> PetscCall(PetscViewerDestroy(&viewer)); >> >> This should not be a problem. >> If this is a segv and you configure it with '--with-debugging=1', you >> should get a stack trace, which would help immensely. >> Or run in a debugger to get a stack trace. >> >> Thanks, >> Mark >> >> >> >> On Fri, Aug 12, 2022 at 11:26 AM Alfredo Jaramillo < >> [email protected]> wrote: >> >>> Dear developers, >>> >>> I'm writing a sparse matrix into a file by doing >>> >>> if (dump_mat) { >>> PetscViewer viewer; >>> PetscViewerASCIIOpen(PETSC_COMM_WORLD,"mat-par-aux.m",&viewer); >>> PetscViewerPushFormat(viewer, PETSC_VIEWER_ASCII_MATLAB); >>> MatView(A,viewer); >>> } >>> >>> This works perfectly for small cases. >>> The program crashes for a case where the matrix A is of order 1 million >>> but with only 4 million non-zero elements. >>> >>> Maybe at some point petsc is full-sizing A? >>> >>> Thank you, >>> Alfredo >>> >>
