set dim[0] to -1 if dim[0] < 0 during compiling for c_allgather op (#21402)

* set dim[0] to -1 if dim[0] < 0 and remove assertion to runtime, test=develop

* modify ENFORCE message, test=develop

* add validation for x.shape[0] > 0, test=develop

* add ut, test=develop

paddle/fluid/operators/collective/c_allgather_op.cc

@@ -29,6 +29,7 @@ class CAllGatherOp : public framework::OperatorWithKernel {
     PADDLE_ENFORCE_GE(nranks, 2, "nranks should be >=2");
     framework::DDim dim = ctx->GetInputDim("X");
     dim[0] = dim[0] * nranks;
+    if (dim[0] < 0) dim[0] = -1;
     ctx->SetOutputDim("Out", dim);
   }
 };

paddle/fluid/operators/collective/c_reducescatter_op.cu.cc

@@ -36,6 +36,11 @@ class CReduceScatterOpCUDAKernel : public framework::OpKernel<T> {
     int nranks = comm->nranks();
 
     auto out_dims = in->dims();
+    PADDLE_ENFORCE_EQ(out_dims[0] % nranks, 0,
+                      platform::errors::InvalidArgument(
+                          "The input tensor X's "
+                          "dim[0] (%d) should be divisible by nranks(%d)",
+                          out_dims[0], nranks));
     out_dims[0] = out_dims[0] / nranks;
     out->mutable_data<T>(out_dims, place);
 

python/paddle/fluid/layers/collective.py

@@ -134,7 +134,7 @@ def _c_reducescatter(x, nranks, ring_id=0, use_calc_stream=False):
     if not isinstance(x, Variable):
         raise TypeError('x must be a Variable')
 
-    if x.shape[0] % nranks != 0:
+    if x.shape[0] > 0 and x.shape[0] % nranks != 0:
         raise ValueError('x.shape[0](%d) cannot be evenly divided by nranks(%d)'
                          % (x.shape[0], nranks))
 

python/paddle/fluid/tests/unittests/CMakeLists.txt

@@ -29,6 +29,7 @@ if(NOT WITH_GPU OR WIN32)
     LIST(REMOVE_ITEM TEST_OPS test_allreduce)
     LIST(REMOVE_ITEM TEST_OPS test_broadcast)
     LIST(REMOVE_ITEM TEST_OPS test_reducescatter)
+    LIST(REMOVE_ITEM TEST_OPS test_reducescatter_api)
 endif()
 
 if(WIN32)

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

@@ -0,0 +1,53 @@
+# Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import numpy as np
+import argparse
+import os
+import sys
+import signal
+import time
+from contextlib import closing
+from six import string_types
+import math
+import paddle
+import paddle.fluid as fluid
+import paddle.fluid.profiler as profiler
+import paddle.fluid.unique_name as nameGen
+from paddle.fluid import core
+import unittest
+from multiprocessing import Process
+import paddle.fluid.layers as layers
+from functools import reduce
+from test_collective_base import TestCollectiveRunnerBase, runtime_main
+
+
+class TestCollectiveReduceScatter(TestCollectiveRunnerBase):
+    def __init__(self):
+        self.global_ring_id = 0
+
+    def get_model(self, main_prog, startup_program):
+        ring_id = 0
+        nranks = 2
+        with fluid.program_guard(main_prog, startup_program):
+            tindata = layers.data(
+                name="tindata", shape=[10, 1000], dtype='float32')
+            toutdata = fluid.layers.collective._c_reducescatter(tindata, nranks)
+            return toutdata
+
+
+if __name__ == "__main__":
+    runtime_main(TestCollectiveReduceScatter, "reducescatter", 0)

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

@@ -0,0 +1,40 @@
+#   Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+import unittest
+import numpy as np
+import paddle.fluid as fluid
+
+from test_collective_base import TestDistBase
+
+
+class TestReduceScatterAPI(TestDistBase):
+    def _setup_config(self):
+        pass
+
+    def test_reducescatter(self, col_type="reduce_scatter"):
+        self.check_with_place("collective_reducescatter.py", col_type)
+
+    def test_reducescatter_with_error(self):
+        nranks = 2
+        tindata = fluid.data(name="tindata", shape=[5, 1000], dtype='float32')
+        try:
+            toutdata = fluid.layers.collective._c_reducescatter(tindata, nranks)
+        except ValueError:
+            pass
+
+
+if __name__ == '__main__':
+    unittest.main()