Fix Sequential double execution bug (#10393)

test/nn/test_sequential.py

@@ -174,3 +174,31 @@ def test_sequential_to_hetero():
     assert isinstance(out_dict, dict) and len(out_dict) == 2
     assert out_dict['paper'].size() == (100, 64)
     assert out_dict['author'].size() == (100, 64)
+
+
+def test_sequential_no_double_execution():
+    # Test for issue #10393: Sequential should not cause double execution
+    # when initialized from a script with a valid Python identifier name
+    execution_count = [0]
+
+    def increment_counter(x):
+        execution_count[0] += 1
+        return x
+
+    x = torch.randn(4, 16)
+
+    # Create Sequential model - should not execute forward pass
+    model = Sequential('x', [(increment_counter, 'x -> y')])
+
+    # Counter should not be incremented during initialization
+    assert execution_count[0] == 0
+
+    # Execute forward pass
+    output = model(x)
+    assert execution_count[0] == 1
+    assert output.shape == x.shape
+
+    # Execute again to verify it works correctly
+    output = model(x)
+    assert execution_count[0] == 2
+    assert output.shape == x.shape

torch_geometric/nn/sequential.py

@@ -246,12 +246,21 @@ def _set_jittable_template(self, raise_on_error: bool = False) -> None:
             root_dir = osp.dirname(osp.realpath(__file__))
             uid = '%06x' % random.randrange(16**6)
             jinja_prefix = f'{self.__module__}_{self.__class__.__name__}_{uid}'
+
+            # Filter out modules that would cause re-execution:
+            # - '__main__' is the script being executed
+            # - Modules not in sys.modules would be imported first time
+            modules_to_import = []
+            if (self._caller_module != '__main__'
+                    and self._caller_module in sys.modules):
+                modules_to_import.append(self._caller_module)
+
             module = module_from_template(
                 module_name=jinja_prefix,
                 template_path=osp.join(root_dir, 'sequential.jinja'),
                 tmp_dirname='sequential',
                 # Keyword arguments:
-                modules=[self._caller_module],
+                modules=modules_to_import,
                 signature=self.signature,
                 children=self._children,
             )