Improved traceback from PETSc errors

[stefanozampini]

Description

There is no need to maintain obsolete CHKERR and SETERR implementations in Firedrake.

PETSc management of tracebacks from Cython/Python was improved one year ago in https://gitlab.com/petsc/petsc/-/merge_requests/7938, and now we can get valuable information from catching errors.

Needs CHKERRMPI exposed in https://gitlab.com/petsc/petsc/-/merge_requests/8758

For example, adding mixing INSERT and ADD values will trigger an error in the PETSc C code that will be forwarded appropriately (through PETSC_ERR_PYTHON) to the Python runtime (the patch is for the code in this PR)

diff --git a/pyop2/sparsity.pyx b/pyop2/sparsity.pyx
index 5914bacc8..f4dcd4d8f 100644
--- a/pyop2/sparsity.pyx
+++ b/pyop2/sparsity.pyx
@@ -50,6 +50,7 @@ cdef extern from "petsc.h":
         PETSC_TRUE, PETSC_FALSE
     ctypedef enum PetscInsertMode "InsertMode":
         PETSC_INSERT_VALUES "INSERT_VALUES"
+        PETSC_ADD_VALUES "ADD_VALUES"
     ctypedef enum PetscErrorCode:
         PETSC_SUCCESS

@@ -200,6 +201,7 @@ def fill_with_zeros(PETSc.Mat mat not None, dims, maps, iteration_regions, set_d
         for i in range(nrow // rdim):
             if i < ncol  // cdim:
                 CHKERR(MatSetValuesBlockedLocal(mat.mat, 1, &i, 1, &i, diag_values, PETSC_INSERT_VALUES))
+                CHKERR(MatSetValuesBlockedLocal(mat.mat, 1, &i, 1, &i, diag_values, PETSC_ADD_VALUES))
         CHKERR(PetscFree(diag_values))
     if len(maps) == 0:
         return

With the current firedrake code, we get

pyop2/sparsity.pyx:163: in pyop2.sparsity.build_sparsity
    fill_with_zeros(preallocator, (1, 1),
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   CHKERR(MatSetValuesBlockedLocal(mat.mat, 1, &i, 1, &i, diag_values, PETSC_ADD_VALUES))
E   RuntimeError: 73

pyop2/sparsity.pyx:220: RuntimeError

while with the code in this PR

pyop2/sparsity.pyx:147: in pyop2.sparsity.build_sparsity
    fill_with_zeros(preallocator, (1, 1),
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

>   CHKERR(MatSetValuesBlockedLocal(mat.mat, 1, &i, 1, &i, diag_values, PETSC_ADD_VALUES))
E   petsc4py.PETSc.Error: error code 73
E   [0] MatSetValuesBlockedLocal() at /Users/zampins/Devel/petsc/src/mat/interface/matrix.c:2585
E   [0] Object is in wrong state
E   [0] Cannot mix add values and insert values

pyop2/sparsity.pyx:204: Error

[connorjward]

This is great. Thanks!

Note that this won't be merge-able until PETSc release 3.24.1 because our release branch follows released PETSc versions.

[stefanozampini]

That's the reason I opened the firedrake PR for main. The PETSc fix will be in main soon

…

On Fri, Oct 3, 2025, 17:50 Connor Ward ***@***.***> wrote: ***@***.**** commented on this pull request. This is great. Thanks! Note that this won't be merge-able until PETSc release 3.24.1 because our release branch follows released PETSc versions. — Reply to this email directly, view it on GitHub <#4616 (review)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABHCKAJYH6OEPQXGAL6E2WD3V2EJZAVCNFSM6AAAAACIDKK3ECVHI2DSMVQWIX3LMV43YUDVNRWFEZLROVSXG5CSMV3GSZLXHMZTEOJZGQYTEMZUGU> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[stefanozampini]

@connorjward Tests pass

[connorjward]

@stefanozampini thanks!