be compatible with the old version of alltoall (#42007)

python/paddle/distributed/collective.py

@@ -860,9 +860,12 @@ def all_gather(tensor_list, tensor, group=None, use_calc_stream=True):
 
     if in_dygraph_mode():
         group = _get_default_group() if group is None else group
+        if len(tensor_list) == 0:
             tensor_shape = list(tensor.shape)
             tensor_shape[0] *= group.nranks
             out = paddle.empty(tensor_shape, tensor.dtype)
+        else:
+            out = paddle.concat(tensor_list, axis=0)
         task = group.process_group.all_gather(tensor, out)
         task.wait()
         tensor_list.clear()
@@ -1783,6 +1786,11 @@ def alltoall(in_tensor_list, out_tensor_list, group=None, use_calc_stream=True):
     temp = paddle.concat(in_tensor_list, axis=0)
     nranks = len(in_tensor_list)
     if in_dygraph_mode():
+        if len(out_tensor_list) == 0:
+            tensor_shape = list(in_tensor_list[0].shape)
+            tensor_shape[0] *= nranks
+            out = paddle.empty(tensor_shape, in_tensor_list[0].dtype)
+        else:
             out = paddle.concat(out_tensor_list, axis=0)
         task = group.process_group.alltoall(temp, out)
         task.wait()

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

@@ -185,6 +185,24 @@ class TestProcessGroupFp32(unittest.TestCase):
             assert np.array_equal(tensor_y, out_2)
             print("test allgather api ok\n")
 
+            if pg.rank() == 0:
+                task = pg.all_gather(tensor_x, tensor_out)
+                task.wait()
+                paddle.device.cuda.synchronize()
+            # rank 1
+            else:
+                tensor_out_list = []
+                task = dist.all_gather(
+                    tensor_out_list, tensor_y, use_calc_stream=False)
+                paddle.device.cuda.synchronize()
+                tensor_out = paddle.concat(tensor_out_list)
+            out_1 = paddle.slice(tensor_out, [0], [0], [out_shape[0] // 2])
+            out_2 = paddle.slice(tensor_out, [0], [out_shape[0] // 2],
+                                 [out_shape[0]])
+            assert np.array_equal(tensor_x, out_1)
+            assert np.array_equal(tensor_y, out_2)
+            print("test allgather api2 ok\n")
+
             # test alltoall
             # rank 0
             x = np.random.random(self.shape).astype(self.dtype)
@@ -219,6 +237,38 @@ class TestProcessGroupFp32(unittest.TestCase):
                 assert np.array_equal(out2_1, raw_tensor_x_2)
             print("test alltoall api ok\n")
 
+            x = np.random.random(self.shape).astype(self.dtype)
+            y = np.random.random(self.shape).astype(self.dtype)
+            out1 = np.random.random(self.shape).astype(self.dtype)
+            out2 = np.random.random(self.shape).astype(self.dtype)
+            tensor_x = paddle.to_tensor(x)
+            tensor_y = paddle.to_tensor(y)
+            tensor_out1 = paddle.to_tensor(out1)
+            tensor_out2 = paddle.to_tensor(out2)
+            raw_tensor_x_2 = paddle.slice(tensor_x, [0], [self.shape[0] // 2],
+                                          [self.shape[0]])
+            raw_tensor_y_1 = paddle.slice(tensor_y, [0], [0],
+                                          [self.shape[0] // 2])
+            if pg.rank() == 0:
+                task = pg.alltoall(tensor_x, tensor_out1)
+                task.wait()
+            # rank 1
+            else:
+                in_1, in_2 = paddle.split(tensor_y, 2)
+                out_1, out_2 = paddle.split(tensor_out2, 2)
+                out_tensor_list = []
+                task = dist.alltoall([in_1, in_2], out_tensor_list)
+                paddle.device.cuda.synchronize()
+                tensor_out2 = paddle.concat(out_tensor_list)
+            out1_2 = paddle.slice(tensor_out1, [0], [self.shape[0] // 2],
+                                  [self.shape[0]])
+            out2_1 = paddle.slice(tensor_out2, [0], [0], [self.shape[0] // 2])
+            if pg.rank() == 0:
+                assert np.array_equal(out1_2.numpy(), raw_tensor_y_1.numpy())
+            else:
+                assert np.array_equal(out2_1, raw_tensor_x_2)
+            print("test alltoall api2 ok\n")
+
             # test Reduce
             # rank 0
             x = np.random.random(self.shape).astype(self.dtype)