Merge pull request #279 from optimas-org/handle_exception_during_exploration_run

Handle exception during exploration run

Author: RemiLehe

optimas/explorations/base.py

@@ -208,26 +208,32 @@ def run(self, n_evals: Optional[int] = None) -> None:
         # Save exploration parameters to json file.
         self._save_exploration_parameters()
 
-        # Launch exploration with libEnsemble.
-        history, persis_info, flag = libE(
-            sim_specs,
-            gen_specs,
-            exit_criteria,
-            persis_info,
-            self.alloc_specs,
-            self.libE_specs,
-            H0=self._libe_history.H,
-        )
+        try:
+            # Launch exploration with libEnsemble.
+            history, persis_info, flag = libE(
+                sim_specs,
+                gen_specs,
+                exit_criteria,
+                persis_info,
+                self.alloc_specs,
+                self.libE_specs,
+                H0=self._libe_history.H,
+            )
 
-        # Update history.
-        self._libe_history.H = history
+            # Update history.
+            self._libe_history.H = history
 
-        # Update number of evaluation in this exploration.
-        n_evals_final = self.generator.n_evaluated_trials
-        self._n_evals += n_evals_final - n_evals_initial
+            # Update number of evaluation in this exploration.
+            n_evals_final = self.generator.n_evaluated_trials
+            self._n_evals += n_evals_final - n_evals_initial
 
-        # Reset `cwd` to initial value before `libE` was called.
-        os.chdir(cwd)
+        except Exception as e:
+            logger.error(
+                "Exploration stopped due to an exception: {}".format(e)
+            )
+        finally:
+            # Reset `cwd` to initial value before `libE` was called.
+            os.chdir(cwd)
 
     def attach_trials(
         self,

tests/test_exploration_run_exception.py

@@ -0,0 +1,53 @@
+import os
+
+from optimas.explorations import Exploration
+from optimas.generators import RandomSamplingGenerator
+from optimas.evaluators import FunctionEvaluator
+from optimas.core import VaryingParameter, Objective
+
+
+def eval_func(input_params, output_params):
+    raise ValueError("Exception to break exploration")
+
+
+def test_exception_during_exploration_run():
+    """Test that the Exploration handles exceptions during the run correctly.
+
+    When using `create_evaluation_dirs=True`, the current working directory
+    will change during exploration and should be restored when `.run` finishes,
+    even if an exception occurs.
+    """
+    # Define variables and objectives.
+    var1 = VaryingParameter("x0", -50.0, 5.0)
+    var2 = VaryingParameter("x1", -5.0, 15.0)
+    obj = Objective("f", minimize=False)
+
+    # Create generator.
+    gen = RandomSamplingGenerator(
+        varying_parameters=[var1, var2],
+        objectives=[obj],
+    )
+
+    # Create function evaluator.
+    ev = FunctionEvaluator(function=eval_func, create_evaluation_dirs=True)
+
+    # Create exploration.
+    exploration = Exploration(
+        generator=gen,
+        evaluator=ev,
+        max_evals=10,
+        sim_workers=2,
+        exploration_dir_path="./tests_output/test_exception_during_run",
+    )
+
+    cwd = os.getcwd()
+
+    # Run exploration without raising an exception.
+    exploration.run()
+
+    # Check that the cwd remains unchanged after a failed run.
+    assert os.getcwd() == cwd
+
+
+if __name__ == "__main__":
+    test_exception_during_exploration_run()