clear 'BasicEngine' when an exception occurs in the backward. (#32546)

* clear 'BasicEngine' when an exception occurs in the backward.

* deal with conflict.

* deal with conflict.

paddle/fluid/imperative/basic_engine.cc

@@ -470,12 +470,20 @@ void BasicEngine::Execute() {
 
       {
         VLOG(3) << "Start to execute grad op " << cur_op.Type();
-        if (tmp_ins_ptr == nullptr) {
-          OpBase::Run(cur_op.InnerOp(), bwd_ins, tmp_outs, cur_op.Attrs(),
-                      cur_op.place());
-        } else {
-          OpBase::Run(cur_op.InnerOp(), *tmp_ins_ptr, tmp_outs, cur_op.Attrs(),
-                      cur_op.place());
+        try {
+          if (tmp_ins_ptr == nullptr) {
+            OpBase::Run(cur_op.InnerOp(), bwd_ins, tmp_outs, cur_op.Attrs(),
+                        cur_op.place());
+          } else {
+            OpBase::Run(cur_op.InnerOp(), *tmp_ins_ptr, tmp_outs,
+                        cur_op.Attrs(), cur_op.place());
+          }
+        } catch (platform::EnforceNotMet& exception) {
+          Clear();
+          throw std::move(exception);
+        } catch (std::exception& ex) {
+          Clear();
+          PADDLE_THROW(platform::errors::External("%s", ex.what()));
         }
       }
 

python/paddle/fluid/tests/unittests/test_pylayer_op.py

@@ -234,8 +234,7 @@ class TestPyLayer(unittest.TestCase):
         z = Layer_bk_none1.apply(input2)
 
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z.sum().backward()
+            z.sum().backward()
 
         class Layer_bk_none2(PyLayer):
             @staticmethod
@@ -249,9 +248,9 @@ class TestPyLayer(unittest.TestCase):
         input1 = paddle.randn([2, 3]).astype("float64")
         input1.stop_gradient = False
         z = Layer_bk_none2.apply(input1, input1)
+
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z.mean().backward()
+            z.mean().backward()
 
         class Layer_bk_one1(PyLayer):
             @staticmethod
@@ -265,9 +264,9 @@ class TestPyLayer(unittest.TestCase):
         input1 = paddle.randn([2, 3]).astype("float64")
         input1.stop_gradient = False
         z = Layer_bk_one1.apply(input1)
+
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z.mean().backward()
+            z.mean().backward()
 
         class Layer_bk_one2(PyLayer):
             @staticmethod
@@ -280,11 +279,11 @@ class TestPyLayer(unittest.TestCase):
 
         input1 = paddle.randn([2, 3]).astype("float64")
         input1.stop_gradient = False
+
         y = Layer_bk_one2.apply(input1, input1)
         z = y[0] + y[1]
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z.mean().backward()
+            z.mean().backward()
 
         class Layer_no_bk(PyLayer):
             @staticmethod
@@ -295,10 +294,9 @@ class TestPyLayer(unittest.TestCase):
         input1.stop_gradient = False
         z = Layer_no_bk.apply(input1)
 
-        with self.assertRaises(NotImplementedError):
-            with paddle.fluid.dygraph.guard():
-                z = z[0] + z[1]
-                z.mean().backward()
+        with self.assertRaises(OSError):
+            z = z[0] + z[1]
+            z.mean().backward()
 
         class Layer_bk_match(PyLayer):
             @staticmethod
@@ -313,9 +311,8 @@ class TestPyLayer(unittest.TestCase):
         input1.stop_gradient = False
         z = Layer_bk_match.apply(input1)
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z = z[0] + z[1]
-                z.mean().backward()
+            z = z[0] + z[1]
+            z.mean().backward()
 
     def test_pylayer_bk_return_none(self):
         class Layer_bk_none1(PyLayer):
@@ -334,8 +331,7 @@ class TestPyLayer(unittest.TestCase):
         z = Layer_bk_none1.apply(input1, input2)
 
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z.mean().backward()
+            z.mean().backward()
 
         class Layer_bk_none2(PyLayer):
             @staticmethod
@@ -353,8 +349,7 @@ class TestPyLayer(unittest.TestCase):
         z = Layer_bk_none2.apply(input1, input2)
         z = z[0] + z[1]
         with self.assertRaises(ValueError):
-            with paddle.fluid.dygraph.guard():
-                z.mean().backward()
+            z.mean().backward()
 
     def test_pylayer_inplace(self):
         class cus_tanh(PyLayer):