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Petsc solver updates #3226

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Merged
bendudson merged 4 commits into from
Dec 19, 2025
Merged

Petsc solver updates #3226

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4323aa5
petsc solver: Catch exceptions from run_rhs
bendudson Dec 5, 2025
210ce59
petsc solver: Add diagnostics compatible with snes solver
bendudson Dec 5, 2025
1ddf5b8
Apply clang-format changes
bendudson Dec 5, 2025
50764ef
snes solver: Wrap all run_rhs calls in try...catch
bendudson Dec 19, 2025
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48 changes: 46 additions & 2 deletions src/solver/impls/petsc/petsc.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,39 @@ PetscErrorCode PetscMonitor(TS ts, PetscInt UNUSED(step), PetscReal t, Vec X, vo
PetscFunctionBegin;

auto* s = static_cast<PetscSolver*>(ctx);

if (s->diagnose) {
// Print diagnostic information.
// Using the same format at the SNES solver

SNESConvergedReason reason;
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warning: variable 'reason' is not initialized [cppcoreguidelines-init-variables]

    SNESConvergedReason reason;
                        ^

SNESGetConvergedReason(s->snes, &reason);

PetscReal timestep;
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warning: variable 'timestep' is not initialized [cppcoreguidelines-init-variables]

src/solver/impls/petsc/petsc.cxx:48:

- #include <petsc.h>
+ #include <math.h>
+ #include <petsc.h>
Suggested change
PetscReal timestep;
PetscReal timestep = NAN;

TSGetTimeStep(s->ts, &timestep);

// SNES failure counter is only reset when TSSolve is called
static PetscInt prev_snes_failures = 0;
PetscInt snes_failures;
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warning: variable 'snes_failures' is not initialized [cppcoreguidelines-init-variables]

Suggested change
PetscInt snes_failures;
PetscInt snes_failures = 0;

TSGetSNESFailures(s->ts, &snes_failures);
snes_failures -= prev_snes_failures;
prev_snes_failures += snes_failures;

// Get number of iterations
int nl_its;
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warning: variable 'nl_its' is not initialized [cppcoreguidelines-init-variables]

Suggested change
int nl_its;
int nl_its = 0;

SNESGetIterationNumber(s->snes, &nl_its);
int lin_its;
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warning: variable 'lin_its' is not initialized [cppcoreguidelines-init-variables]

Suggested change
int lin_its;
int lin_its = 0;

SNESGetLinearSolveIterations(s->snes, &lin_its);

output.print("\r"); // Carriage return for printing to screen
output.write("Time: {}, timestep: {}, nl iter: {}, lin iter: {}, reason: {}", t,
timestep, nl_its, lin_its, static_cast<int>(reason));
if (snes_failures > 0) {
output.write(", SNES failures: {}", snes_failures);
}
output.write("\n");
}

if (t < s->next_output) {
// Not reached output time yet => return
PetscFunctionReturn(0);
Expand Down Expand Up @@ -903,8 +936,19 @@ PetscErrorCode PetscSolver::rhs(BoutReal t, Vec udata, Vec dudata, bool linear)
load_vars(const_cast<BoutReal*>(udata_array));
VecRestoreArrayRead(udata, &udata_array);

// Call RHS function
run_rhs(t, linear);
try {
// Call RHS function
run_rhs(t, linear);
} catch (BoutException& e) {
// Simulation might fail, e.g. negative densities
// if timestep too large
output_warn.write("WARNING: BoutException thrown: {}\n", e.what());

// Tell SNES that the input was out of domain
SNESSetFunctionDomainError(snes);
// Note: Returning non-zero error here leaves vectors in locked state
return 0;
}

// Save derivatives to PETSc
BoutReal* dudata_array;
Expand Down
15 changes: 13 additions & 2 deletions src/solver/impls/snes/snes.cxx
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Expand Up @@ -993,7 +993,13 @@ int SNESSolver::run() {
ierr = VecRestoreArrayRead(snes_x, &xdata);
CHKERRQ(ierr);
}
run_rhs(simtime);

try {
run_rhs(simtime);
} catch (BoutException& e) {
output_error.write("ERROR: BoutException thrown: {}\n", e.what());
return 1;
}

// Copy derivatives back
{
Expand Down Expand Up @@ -1168,7 +1174,12 @@ int SNESSolver::run() {
ierr = VecRestoreArrayRead(output_x, &xdata);
CHKERRQ(ierr);
}
run_rhs(target); // Run RHS to calculate auxilliary variables

try {
run_rhs(target); // Run RHS to calculate auxilliary variables
} catch (BoutException& e) {
output_error.write("ERROR: BoutException thrown: {}\n", e.what());
}

if (call_monitors(target, s, getNumberOutputSteps()) != 0) {
break; // User signalled to quit
Expand Down
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