From fac8702269b2e91891ffccdd684be9d5f91ff31c Mon Sep 17 00:00:00 2001
From: Qiao Longfei <qiaolongfei@baidu.com>
Date: Thu, 13 Dec 2018 22:39:40 +0800
Subject: [PATCH] adam support multithread

---
 paddle/fluid/framework/operator.cc          |  2 ++
 paddle/fluid/framework/operator.h           |  3 +++
 paddle/fluid/operators/optimizers/adam_op.h | 30 ++++++++++++++++++---
 python/paddle/fluid/__init__.py             |  3 ++-
 4 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/paddle/fluid/framework/operator.cc b/paddle/fluid/framework/operator.cc
index 66055e6f1d8..c4ff97948a9 100644
--- a/paddle/fluid/framework/operator.cc
+++ b/paddle/fluid/framework/operator.cc
@@ -30,6 +30,8 @@ DECLARE_bool(benchmark);
 DEFINE_bool(check_nan_inf, false,
             "Checking whether operator produce NAN/INF or not. It will be "
             "extremely slow so please use this flag wisely.");
+DEFINE_int32(inner_op_parallelism, 0, "number of threads for inner op");
+DEFINE_int32(min_param_size_to_use_multithread, 0, "");
 
 namespace paddle {
 namespace framework {
diff --git a/paddle/fluid/framework/operator.h b/paddle/fluid/framework/operator.h
index 0a6a28a5bce..175f7975a36 100644
--- a/paddle/fluid/framework/operator.h
+++ b/paddle/fluid/framework/operator.h
@@ -34,6 +34,9 @@ limitations under the License. */
 #include "paddle/fluid/platform/device_context.h"
 #include "paddle/fluid/platform/variant.h"
 
+DECLARE_int32(inner_op_parallelism);
+DECLARE_int32(min_param_size_to_use_multithread);
+
 namespace paddle {
 namespace framework {
 
diff --git a/paddle/fluid/operators/optimizers/adam_op.h b/paddle/fluid/operators/optimizers/adam_op.h
index 3455d1ee54e..aabb71c556a 100644
--- a/paddle/fluid/operators/optimizers/adam_op.h
+++ b/paddle/fluid/operators/optimizers/adam_op.h
@@ -17,6 +17,7 @@ limitations under the License. */
 #include <Eigen/Dense>
 #include <vector>
 #include "paddle/fluid/framework/op_registry.h"
+#include "paddle/fluid/framework/threadpool.h"
 #include "paddle/fluid/operators/detail/safe_ref.h"
 #include "paddle/fluid/operators/math/algorithm.h"
 #include "paddle/fluid/operators/math/selected_rows_functor.h"
@@ -352,10 +353,31 @@ class AdamOpKernel : public framework::OpKernel<T> {
           lr.template data<T>(), grad_data, param.template data<T>(),
           param_out.template mutable_data<T>(ctx.GetPlace()), rows, row_numel,
           grad_merge.rows().size());
-      platform::ForRange<DeviceContext> for_range(
-          static_cast<const DeviceContext&>(ctx.device_context()),
-          param.numel());
-      for_range(functor);
+      int inner_op_parallelism = FLAGS_inner_op_parallelism;
+      if (inner_op_parallelism > 1 &&
+          FLAGS_min_param_size_to_use_multithread > 0 &&
+          param.numel() > FLAGS_min_param_size_to_use_multithread) {
+        std::vector<std::future<void>> fs;
+        int64_t block_size = param.numel() / inner_op_parallelism;
+        for (int i = 0; i < inner_op_parallelism; ++i) {
+          int64_t start = i * block_size;
+          int64_t end = (i + 1) * block_size;
+          if (end > param.numel()) {
+            end = param.numel();
+          }
+          fs.push_back(framework::Async([&functor, start, end]() {
+            for (int64_t i = start; i < end; ++i) {
+              functor(i);
+            }
+          }));
+        }
+        for (size_t i = 0; i < fs.size(); ++i) fs[i].wait();
+      } else {
+        platform::ForRange<DeviceContext> for_range(
+            static_cast<const DeviceContext&>(ctx.device_context()),
+            param.numel());
+        for_range(functor);
+      }
     } else {
       PADDLE_THROW("Variable type not supported by adam_op");
     }
diff --git a/python/paddle/fluid/__init__.py b/python/paddle/fluid/__init__.py
index e0bb0d1152b..1b24e01c22c 100644
--- a/python/paddle/fluid/__init__.py
+++ b/python/paddle/fluid/__init__.py
@@ -128,7 +128,8 @@ def __bootstrap__():
         'free_idle_memory', 'paddle_num_threads', "dist_threadpool_size",
         'eager_delete_tensor_gb', 'fast_eager_deletion_mode',
         'allocator_strategy', 'reader_queue_speed_test_mode',
-        'print_sub_graph_dir', 'pe_profile_fname'
+        'print_sub_graph_dir', 'pe_profile_fname', 'inner_op_parallelism',
+        'min_param_size_to_use_multithread'
     ]
     if 'Darwin' not in sysstr:
         read_env_flags.append('use_pinned_memory')
-- 
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