Merge pull request #3383 from reverendbedford/reuse_preconditioner_edge_cases

Fix edge cases in preconditioner reuse

Author: roystgnr

include/solvers/nonlinear_solver.h

@@ -365,14 +365,19 @@ class NonlinearSolver : public ReferenceCountedObject<NonlinearSolver<T>>,
   virtual void set_reuse_preconditioner(bool reuse);
 
   /**
-   *  Get the reuse_preconditioner_max_its parameter
+   *  Get the reuse_preconditioner_max_linear_its parameter
    */
-  virtual unsigned int reuse_preconditioner_max_its() const;
+  virtual unsigned int reuse_preconditioner_max_linear_its() const;
 
   /**
-   *  Set the reuse_preconditioner_max_its parameter
+   *  Set the reuse_preconditioner_max_linear_its parameter
    */
-  virtual void set_reuse_preconditioner_max_its(unsigned int i);
+  virtual void set_reuse_preconditioner_max_linear_its(unsigned int i);
+
+  /**
+   * Immediately force a new preconditioner
+   */
+  virtual void force_new_preconditioner() {};
 
 
 protected:
@@ -384,7 +389,7 @@ class NonlinearSolver : public ReferenceCountedObject<NonlinearSolver<T>>,
   /**
    * Number of linear iterations to retain the preconditioner
    */
-  unsigned int _reuse_preconditioner_max_its;
+  unsigned int _reuse_preconditioner_max_linear_its;
 
   /**
    * A reference to the system we are solving.
@@ -447,7 +452,7 @@ NonlinearSolver<T>::NonlinearSolver (sys_type & s) :
   minimum_linear_tolerance(0),
   converged(false),
   _reuse_preconditioner(false),
-  _reuse_preconditioner_max_its(0),
+  _reuse_preconditioner_max_linear_its(0),
   _system(s),
   _is_initialized (false),
   _preconditioner (nullptr),

include/solvers/petsc_nonlinear_solver.h

@@ -215,7 +215,12 @@ class PetscNonlinearSolver : public NonlinearSolver<T>
   /**
    *  Getter for the maximum iterations flag for preconditioner reuse
    */
-  virtual unsigned int reuse_preconditioner_max_its() const override;
+  virtual unsigned int reuse_preconditioner_max_linear_its() const override;
+
+  /**
+   *  Immediately force a new preconditioner, even if reuse is set
+   */
+  virtual void force_new_preconditioner() override;
 
 protected:
 

src/solvers/nonlinear_solver.C

@@ -97,15 +97,15 @@ void NonlinearSolver<T>::set_reuse_preconditioner(bool reuse)
 }
 
 template <typename T>
-unsigned int NonlinearSolver<T>::reuse_preconditioner_max_its() const
+unsigned int NonlinearSolver<T>::reuse_preconditioner_max_linear_its() const
 {
   libmesh_not_implemented();
 }
 
 template <typename T>
-void NonlinearSolver<T>::set_reuse_preconditioner_max_its(unsigned int i)
+void NonlinearSolver<T>::set_reuse_preconditioner_max_linear_its(unsigned int i)
 {
-  _reuse_preconditioner_max_its = i;
+  _reuse_preconditioner_max_linear_its = i;
 }
 
 //------------------------------------------------------------------

src/solvers/petsc_nonlinear_solver.C

@@ -126,7 +126,7 @@ extern "C"
     ierr = KSPGetIterationNumber(ksp, &niter);
     LIBMESH_CHKERR2(solver->comm(),ierr);
 
-    if (niter > cast_int<PetscInt>(solver->reuse_preconditioner_max_its()))
+    if (niter > cast_int<PetscInt>(solver->reuse_preconditioner_max_linear_its()))
     {
       // -2 is a magic number for "recalculate next time you need it
       // and then not again"
@@ -682,8 +682,6 @@ void PetscNonlinearSolver<T>::clear ()
     }
 }
 
-
-
 template <typename T>
 void PetscNonlinearSolver<T>::init (const char * name)
 {
@@ -855,7 +853,6 @@ PetscNonlinearSolver<T>::solve (SparseMatrix<T> &  pre_in,  // System Preconditi
   LOG_SCOPE("solve()", "PetscNonlinearSolver");
   this->init ();
 
-
   // Make sure the data passed in are really of Petsc types
   PetscMatrix<T> * pre = cast_ptr<PetscMatrix<T> *>(&pre_in);
   PetscVector<T> * x   = cast_ptr<PetscVector<T> *>(&x_in);
@@ -878,7 +875,7 @@ PetscNonlinearSolver<T>::solve (SparseMatrix<T> &  pre_in,  // System Preconditi
       ierr = SNESSetLagPreconditioner(_snes, -2);
       LIBMESH_CHKERR(ierr);
       // Add in our callback which will trigger recalculating
-      // the preconditioner when we hit reuse_preconditioner_max_its
+      // the preconditioner when we hit reuse_preconditioner_max_linear_its
       ierr = SNESMonitorSet(_snes, &libmesh_petsc_recalculate_monitor,
                             this,
                             NULL);
@@ -1129,11 +1126,19 @@ bool PetscNonlinearSolver<T>::reuse_preconditioner() const
 }
 
 template <typename T>
-unsigned int PetscNonlinearSolver<T>::reuse_preconditioner_max_its() const
+unsigned int PetscNonlinearSolver<T>::reuse_preconditioner_max_linear_its() const
 {
-  return this->_reuse_preconditioner_max_its;
+  return this->_reuse_preconditioner_max_linear_its;
 }
 
+template <typename T>
+void PetscNonlinearSolver<T>::force_new_preconditioner()
+{
+  // Easiest way is just to clear everything out
+  this->_is_initialized = false;
+  _snes.destroy();
+  _setup_reuse = false;
+}
 
 //------------------------------------------------------------------
 // Explicit instantiations

src/systems/nonlinear_implicit_system.C

@@ -54,7 +54,7 @@ NonlinearImplicitSystem::NonlinearImplicitSystem (EquationSystems & es,
   es.parameters.set<Real>("nonlinear solver relative step tolerance") = 1e-8;
 
   es.parameters.set<bool>("reuse preconditioner") = false;
-  es.parameters.set<unsigned int>("reuse preconditioner maximum iterations") = 1;
+  es.parameters.set<unsigned int>("reuse preconditioner maximum linear iterations") = 1;
 }
 
 
@@ -82,6 +82,10 @@ void NonlinearImplicitSystem::reinit ()
   // re-initialize the nonlinear solver interface
   nonlinear_solver->clear();
 
+  // force the solver to get a new preconditioner, in
+  // case reuse was set
+  nonlinear_solver->force_new_preconditioner();
+
   // FIXME - this is necessary for petsc_auto_fieldsplit
   // nonlinear_solver->init_names(*this);
 
@@ -134,8 +138,8 @@ void NonlinearImplicitSystem::set_solver_parameters ()
 
   const bool reuse_preconditioner =
       es.parameters.get<bool>("reuse preconditioner");
-  const unsigned int reuse_preconditioner_max_its =
-      es.parameters.get<unsigned int>("reuse preconditioner maximum iterations");
+  const unsigned int reuse_preconditioner_max_linear_its =
+      es.parameters.get<unsigned int>("reuse preconditioner maximum linear iterations");
 
   // Set all the parameters on the NonlinearSolver
   nonlinear_solver->max_nonlinear_iterations = maxits;
@@ -149,7 +153,7 @@ void NonlinearImplicitSystem::set_solver_parameters ()
   nonlinear_solver->initial_linear_tolerance = linear_tol;
   nonlinear_solver->minimum_linear_tolerance = linear_min_tol;
   nonlinear_solver->set_reuse_preconditioner(reuse_preconditioner);
-  nonlinear_solver->set_reuse_preconditioner_max_its(reuse_preconditioner_max_its);
+  nonlinear_solver->set_reuse_preconditioner_max_linear_its(reuse_preconditioner_max_linear_its);
 
   if (diff_solver.get())
     {