From 039d783db5ed14a5eabadb3177c800697afec39d Mon Sep 17 00:00:00 2001
From: Qiao Longfei <qiaolongfei@baidu.com>
Date: Mon, 18 Mar 2019 13:35:37 +0800
Subject: [PATCH] change communicator_recv_wait_ms to
 communicator_max_send_grad_num_before_recv

---
 .../operators/distributed/communicator.cc     | 23 ++++++++++++++-----
 .../operators/distributed/communicator.h      |  2 ++
 python/paddle/fluid/__init__.py               |  2 +-
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/paddle/fluid/operators/distributed/communicator.cc b/paddle/fluid/operators/distributed/communicator.cc
index 3661c2763..eba18c677 100644
--- a/paddle/fluid/operators/distributed/communicator.cc
+++ b/paddle/fluid/operators/distributed/communicator.cc
@@ -29,7 +29,8 @@ DEFINE_bool(communicator_independent_recv_thread, true,
             "use an independent to recv vars from parameter server");
 DEFINE_int32(communicator_send_queue_size, 20,
              "queue size to recv gradient before send");
-DEFINE_int32(communicator_recv_wait_ms, 200, "wait time between each recv");
+DEFINE_int32(communicator_max_send_grad_num_before_recv, 20,
+             "max grad num to send before recv parameters");
 DEFINE_int32(communicator_thread_pool_size, 5, "thread num to do send or recv");
 DEFINE_int32(communicator_max_merge_var_num, 20,
              "max var num to merge and send");
@@ -60,7 +61,8 @@ Communicator::Communicator(const RpcCtxMap &send_varname_to_ctx,
           << FLAGS_communicator_independent_recv_thread;
   VLOG(0) << "communicator_send_queue_size: "
           << FLAGS_communicator_send_queue_size;
-  VLOG(0) << "communicator_recv_wait_ms: " << FLAGS_communicator_recv_wait_ms;
+  VLOG(0) << "communicator_max_send_grad_num_before_recv: "
+          << FLAGS_communicator_max_send_grad_num_before_recv;
   VLOG(0) << "communicator_thread_pool_size: "
           << FLAGS_communicator_thread_pool_size;
   VLOG(0) << "communicator_max_merge_var_num: "
@@ -102,6 +104,10 @@ void Communicator::SendThread() {
           while (var_queue->Size() > 0 &&
                  merged_var_num < FLAGS_communicator_max_merge_var_num) {
             vars.push_back(var_queue->Pop());
+            // only count the send number of the first var
+            if (var_name == send_varname_to_queue_.begin()->first) {
+              grad_num_.fetch_add(1, std::memory_order_relaxed);
+            }
             merged_var_num++;
           }
           auto before_merge = GetCurrentUS();
@@ -129,7 +135,7 @@ void Communicator::SendThread() {
     }
     auto after_run_send_graph = GetCurrentUS();
     auto send_graph_use_time = after_run_send_graph - before_run_send_graph;
-    if (send_graph_use_time > 10) {
+    if (send_graph_use_time > 100) {
       VLOG(1) << "run send graph use time "
               << after_run_send_graph - before_run_send_graph;
     }
@@ -165,9 +171,14 @@ void Communicator::RecvAll() {
 void Communicator::RecvThread() {
   VLOG(3) << "RecvThread start!";
   while (running_) {
-    RecvAll();
-    std::this_thread::sleep_for(
-        std::chrono::milliseconds(FLAGS_communicator_recv_wait_ms));
+    auto grad_num = grad_num_.load();
+    if (grad_num > FLAGS_communicator_max_send_grad_num_before_recv) {
+      VLOG(1) << "current grad num " << grad_num;
+      RecvAll();
+      grad_num_.store(0);
+    } else {
+      std::this_thread::sleep_for(std::chrono::milliseconds(10));
+    }
   }
 }
 
diff --git a/paddle/fluid/operators/distributed/communicator.h b/paddle/fluid/operators/distributed/communicator.h
index 3fe2a2123..859c0a7f5 100644
--- a/paddle/fluid/operators/distributed/communicator.h
+++ b/paddle/fluid/operators/distributed/communicator.h
@@ -14,6 +14,7 @@ limitations under the License. */
 
 #pragma once
 
+#include <atomic>
 #include <deque>
 #include <memory>
 #include <string>
@@ -184,6 +185,7 @@ class Communicator {
   std::unique_ptr<Scope> send_scope_;  // an independent scope
   std::unique_ptr<::ThreadPool> send_threadpool_{nullptr};
   std::unique_ptr<::ThreadPool> recv_threadpool_{nullptr};
+  std::atomic_uint grad_num_{0};  // the num of gradient sent since last recv
 
   // the following code is for initialize the commnunicator
  public:
diff --git a/python/paddle/fluid/__init__.py b/python/paddle/fluid/__init__.py
index c478c8cee..97ac7fd97 100644
--- a/python/paddle/fluid/__init__.py
+++ b/python/paddle/fluid/__init__.py
@@ -155,7 +155,7 @@ def __bootstrap__():
         # env for communicator
         read_env_flags.append('communicator_independent_recv_thread')
         read_env_flags.append('communicator_send_queue_size')
-        read_env_flags.append('communicator_recv_wait_ms')
+        read_env_flags.append('communicator_max_send_grad_num_before_recv')
         read_env_flags.append('communicator_thread_pool_size')
         read_env_flags.append('communicator_max_merge_var_num')
         read_env_flags.append('communicator_fake_rpc')
-- 
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