Add ability to handle infeasible models when optimizations are turned…

… off.
erdos-project · Dec 2, 2023 · bd13518 · bd13518
1 parent 2ee2250
commit bd13518
Show file tree

Hide file tree

Showing 5 changed files with 37 additions and 11 deletions.
diff --git a/schedulers/tetrisched/include/tetrisched/Solver.hpp b/schedulers/tetrisched/include/tetrisched/Solver.hpp
@@ -47,6 +47,12 @@ struct SolverSolution {
   /// The time taken by the solver to find the solution (in microseconds).
   uint64_t solverTimeMicroseconds;
 
+  /// Check if the solution was valid.
+  bool isValid() const {
+    return solutionType == SolutionType::FEASIBLE ||
+           solutionType == SolutionType::OPTIMAL;
+  }
+
   /// Get a string representation of the Solver's type.
   std::string getSolutionTypeStr() const {
     switch (solutionType) {

diff --git a/schedulers/tetrisched/python/Backends.cpp b/schedulers/tetrisched/python/Backends.cpp
@@ -41,6 +41,8 @@ void defineSolverSolution(py::module_& tetrisched_m) {
                              [](const tetrisched::SolverSolution& solution) {
                                return solution.solverTimeMicroseconds;
                              })
+      .def("isValid", &tetrisched::SolverSolution::isValid,
+           "Check if the solution was valid.")
       .def("__str__", [](const tetrisched::SolverSolution& solution) {
         return "SolverSolution<type=" + solution.getSolutionTypeStr() +
                ", objectiveValue=" +

diff --git a/schedulers/tetrisched/src/GurobiSolver.cpp b/schedulers/tetrisched/src/GurobiSolver.cpp
@@ -1,8 +1,8 @@
 #include "tetrisched/GurobiSolver.hpp"
 
 #include <chrono>
-#include <thread>
 #include <cmath>
+#include <thread>
 
 namespace tetrisched {
 GurobiSolver::GurobiSolver()
@@ -241,16 +241,16 @@ SolverSolutionPtr GurobiSolver::solveModel() {
       break;
     case GRB_INFEASIBLE:
       solverSolution->solutionType = SolutionType::INFEASIBLE;
-      break;
+      return solverSolution;
     case GRB_INF_OR_UNBD:
     case GRB_UNBOUNDED:
       solverSolution->solutionType = SolutionType::UNBOUNDED;
-      break;
+      return solverSolution;
     default:
       solverSolution->solutionType = SolutionType::UNKNOWN;
       TETRISCHED_DEBUG("The Gurobi solver returned the value: "
                        << gurobiModel->get(GRB_IntAttr_Status));
-      break;
+      return solverSolution;
   }
   TETRISCHED_DEBUG("The Gurobi solver took "
                    << solverSolution->solverTimeMicroseconds << " microseconds "

diff --git a/schedulers/tetrisched/src/Scheduler.cpp b/schedulers/tetrisched/src/Scheduler.cpp
@@ -116,7 +116,9 @@ void Scheduler::schedule(Time currentTime) {
   solverSolution = this->solver->solveModel();
 
   // Populate the results from the solver into the expression tree.
-  this->expression.value()->populateResults(solverModel);
+  if (solverSolution.has_value() && solverSolution.value()->isValid()) {
+    this->expression.value()->populateResults(solverModel);
+  }
 }
 
 SolverSolutionPtr Scheduler::getLastSolverSolution() const {

diff --git a/schedulers/tetrisched_scheduler.py b/schedulers/tetrisched_scheduler.py
@@ -337,6 +337,21 @@ def schedule(
                 )
                 raise e
 
+            # If the solver could not solve the model, log an error.
+            if not self._scheduler.getLastSolverSolution().isValid():
+                self._logger.error(
+                    f"[{sim_time.time}] The solver failed to find a solution for "
+                    f"the STRL expression. Dumping the model to "
+                    f"tetrisched_error_{sim_time.time}.lp and STRL expression to "
+                    f"tetrisched_error_{sim_time.time}.dot."
+                )
+                objective_strl.exportToDot(
+                    os.path.join(self._log_dir, f"tetrisched_error_{sim_time.time}.dot")
+                )
+                self._scheduler.exportLastSolverModel(
+                    os.path.join(self._log_dir, f"tetrisched_error_{sim_time.time}.lp")
+                )
+
             # If requested, log the model to a file.
             if self._log_to_file or sim_time.time in self._log_times:
                 self._scheduler.exportLastSolverModel(
@@ -353,12 +368,13 @@ def schedule(
 
             # Retrieve the solution and check if we were able to schedule anything.
             solverSolution = objective_strl.getSolution()
-            self._logger.info(
-                f"[{sim_time.time}] Solver returned utility of {solverSolution.utility}"
-                f" and took {solver_time} to solve. The solution result "
-                f"was {self._scheduler.getLastSolverSolution()}."
-            )
-            if solverSolution.utility > 0:
+            if solverSolution is not None and solverSolution.utility > 0:
+                self._logger.info(
+                    f"[{sim_time.time}] Solver returned utility of "
+                    f"{solverSolution.utility} and took {solver_time} to solve. The "
+                    f"solution result was {self._scheduler.getLastSolverSolution()}."
+                )
+
                 # Retrieve the Placements for each task.
                 for task in tasks_to_be_scheduled:
                     task_placement = solverSolution.getPlacement(task.unique_name)