Update async_executor.md

doc/fluid/design/async_executor/async_executor.md

@@ -39,16 +39,16 @@ Why we use multiple queues for data reader? a experimental result page needs to
 ## Main Interface of Async Executor
 We have RunFromFiles interface which is an execution interface for users to call. Every time a user calls RunFromFiles, a main_program should be provided and it is running in the global scope previously defined. A list of file names and corresponding Dataset should be provided. Inside the RunFromFiles interface, readers will be created through Dataset configurations. Files will be fed into created readers. 
 ``` c++
-void AsyncExecutor::RunFromFiles(
+std::vector<float> AsyncExecutor::RunFromFile(
     const ProgramDesc& main_program,
-    const DataFeedDesc& data_feed_desc,
-    const std::vector<std::string> & files,
-    const int thread_num) {
-  // todo: remove fluid related interface
-  root_scope_->DropKids();
+    const std::string& data_feed_desc_str,
+    const std::vector<std::string>& filelist,
+    const int thread_num,
+    const std::vector<std::string>& fetch_var_names) {
   std::vector<std::thread> threads;
-  threads.resize(thread_num);
 
+  DataFeedDesc data_feed_desc;
+  google::protobuf::TextFormat::ParseFromString(data_feed_desc_str, &data_feed_desc);
   /*
     readerDesc: protobuf description for reader initlization
     argument: class_name, batch_size, use_slot, queue_size, buffer_size, padding_index
@@ -59,23 +59,10 @@ void AsyncExecutor::RunFromFiles(
     2) each reader has a Next() iterface, that can fetch an instance
     from the input queue
    */
+  // todo: should be factory method for creating datafeed
   std::vector<std::shared_ptr<DataFeed> > readers;
-  readers.resize(thread_num);
-  for (int i = 0; i < readers.size(); ++i) {
-    readers[i] = DataFeedFactory::CreateDataFeed(data_feed_desc.name());
-  }
-
-  // todo(dongdaxiang): add the following code for worker generalization
-  /*
-  std::vector<std::shared_ptr<ExecutorStrategy> > workers;
-  workers.resize(thread_num);
-  std::string str_name = strategy_.name;
-  for (auto& worker : workers) {
-    worker.reset(
-        ExecutorStrategyFactory::CreateExecutorStrategy(str_name));
-  }
-  */
-
+  PrepareReaders(readers, thread_num, data_feed_desc, filelist);
+  
   std::vector<std::shared_ptr<ExecutorThreadWorker> > workers;
   workers.resize(thread_num);
   for (auto& worker : workers) {
@@ -85,10 +72,11 @@ void AsyncExecutor::RunFromFiles(
   // prepare thread resource here
   for (int thidx = 0; thidx < thread_num; ++thidx) {
     CreateThreads(workers[thidx].get(), main_program,
-                  readers[thidx].get(), root_scope_, thidx);
+                  readers[thidx], fetch_var_names, root_scope_, thidx);
   }
+
   // start executing ops in multiple threads
-  for (int thidx = 0; thidx < thread_num_; ++thidx) {
+  for (int thidx = 0; thidx < thread_num; ++thidx) {
     threads.push_back(std::thread(&ExecutorThreadWorker::TrainFiles,
                                   workers[thidx].get()));
   }
@@ -96,22 +84,44 @@ void AsyncExecutor::RunFromFiles(
   for (auto& th : threads) {
     th.join();
   }
-  // fetch variables in scope 0, and return, to be added
+
+  std::vector<float> fetch_values;
+  fetch_values.resize(fetch_var_names.size(), 0);
+
+  std::vector<std::vector<float>*> fetch_value_vectors;
+  fetch_value_vectors.resize(thread_num);
+  for (int i = 0; i < thread_num; ++i) {
+    fetch_value_vectors[i] = &workers[i]->GetFetchValues();
+  }
+
+  for (unsigned int i = 0; i < fetch_var_names.size(); ++i) {
+    float value = 0.0;
+    for (int j = 0; j < thread_num; ++j) {
+      value += fetch_value_vectors[j]->at(i);
+    }
+    value /= thread_num;
+    fetch_values[i] = value;
+  }
+
+  return fetch_values;
 }
 
 ```
 Inside the function ```CreateThreads```, 
 ``` c++
-void AsyncExecutor::CreateThreads(const ExecutorThreadWorker* worker,
-                                  const ProgramDesc& main_program,
-                                  const DataFeed& reader,
-                                  const Scope& root_scope,
-                                  const int thread_index) {
-  worker->SetThreadid(thread_index);
+void AsyncExecutor::CreateThreads(
+    ExecutorThreadWorker* worker,
+    const ProgramDesc& main_program,
+    const std::shared_ptr<DataFeed>& reader,
+    const std::vector<std::string>& fetch_var_names,
+    Scope& root_scope,
+    const int thread_index) {
+  worker->SetThreadId(thread_index);
+  worker->SetRootScope(&root_scope);
   worker->CreateThreadResource(main_program, place_);
   worker->SetDataFeed(reader);
-  worker->BindingDataFeedMemory(reader);
-  worker->SetRootScope(root_scope);
+  worker->SetFetchVarNames(fetch_var_names);
+  worker->BindingDataFeedMemory();
 }
 
 ```
@@ -120,20 +130,44 @@ Inside the function ```Trainfiles```,
 void ExecutorThreadWorker::TrainFiles() {
   // todo: configurable
   SetDevice();
-  thread_reader_->Start(); // start reading thread within reader
-  while (int cur_batch = thread_reader_->Next()) {
+
+  int fetch_var_num = fetch_var_names_.size();
+  fetch_values_.clear();
+  fetch_values_.resize(fetch_var_num, 0);
+
+  thread_reader_->Start();
+
+  int cur_batch;
+  int batch_cnt = 0;
+  while ((cur_batch = thread_reader_->Next()) > 0) {
     // executor run here
     for (auto& op : ops_) {
       op->Run(*thread_scope_, place_);
     }
+
+    float avg_inspect = 0.0;
+    for (int i = 0; i < fetch_var_num; ++i) {
+      avg_inspect = thread_scope_->FindVar(fetch_var_names_[i])
+                                 ->GetMutable<LoDTensor>()
+                                 ->data<float>()[0];
+      fetch_values_[i] += avg_inspect;
+    }
+
+    ++batch_cnt;
     thread_scope_->DropKids();
   }
-}
+
+  if (batch_cnt) {
+    // when the number of files is less than the number of threads
+    for (int i = 0; i < fetch_var_num; ++i) {
+      fetch_values_[i] = fetch_values_[i] / batch_cnt;
+    }
+  }
 
 ```
 
 ## How to print variable information during execution
-Inside async_executor, no information is printed. Variable can be fetched through an execution of async_executor. The fetched variables can be printed through python. 
+Inside async_executor, no information is printed. Variable can be fetched through an execution of async_executor. The fetched variables can be printed through python. Since we train several files of instances within async_executor, the fetched variables are not accurate. In this version of design, we only fetch variables of the last iteration for each thread and we average the fetched variables by batch_size * thread_num. 
 
 ## How to save models
 Models can be saved between execution of async_executor through io.save method. 
@@ -144,11 +178,6 @@ Models can be saved between execution of async_executor through io.save method.
 * data preparation
 * performance and accuracy
 
-### Text Matching
-* network configuration
-* data preparation
-* performance and accuracy
-
 ## references
 1. [Sentiment Analysis](https://arxiv.org/pdf/1801.07883.pdf)
 2. [Word2Vec](https://arxiv.org/abs/1301.3781)