Merge branch 'master' into ebarsoum/ImageHandsOn

Checkin...

Source/1BitSGD

@@ -1 +1 @@
-Subproject commit 26475afc2945db5be61494dfbb542ba058f9b862
+Subproject commit 6535b08760744c890a88e4c934352ae7fb6b6e30

Source/CNTKv2LibraryDll/API/CNTKLibrary.h

@@ -3623,6 +3623,9 @@ namespace CNTK
         // Optionally overridable method to restore state pertaining this distributed training method from a previous checkpoint
         CNTK_API virtual void RestoreFromCheckpoint(const Dictionary& checkpoint) = 0;
 
+        // Return the distributed communicator used in the distributed trainer
+        CNTK_API virtual DistributedCommunicatorPtr GetCommunicator() = 0;
+
         virtual ~DistributedTrainer() {}
     };
 

Source/CNTKv2LibraryDll/DataParallelDistributedTrainer.h

@@ -30,6 +30,11 @@ namespace CNTK
         void RestoreFromCheckpoint(const Dictionary& checkpoint) override;
 
     private:
+        DistributedCommunicatorPtr GetCommunicator() override
+        {
+            return m_communicator;
+        }
+
         DistributedCommunicatorPtr m_communicator;
         bool m_useAsyncBufferedParameterUpdate;
     };

Source/CNTKv2LibraryDll/Trainer.cpp

@@ -223,22 +223,43 @@ namespace CNTK
 
     void Trainer::SaveCheckpoint(const std::wstring& modelFilePath, bool usinglegacyModelFormat)
     {
-        m_combinedTrainingFunction->SaveModel(modelFilePath, usinglegacyModelFormat);
-
-        vector<DictionaryValue> learnerStates;
-
-        for (const auto& learner : m_parameterLearners)
+        bool shouldSave = true;
+        if (m_distributedTrainer != nullptr)
         {
-            // TODO: add DictionaryValue(T&&)
-            learnerStates.push_back(DictionaryValue(learner->Serialize()));
+            // all workers need to sync up before saving model to avoid write-after-read hazard
+            // i.e. one worker is in the middle of reading a checkpoint while another overwrites
+            m_distributedTrainer->GetCommunicator()->Barrier();
+
+            // for distributed training, only save checkpoint at worker 0
+            shouldSave = m_distributedTrainer->GetCommunicator()->CurrentWorker().IsMain();
         }
+    
+        if (shouldSave)
+        {
+            m_combinedTrainingFunction->SaveModel(modelFilePath, usinglegacyModelFormat);
+
+            vector<DictionaryValue> learnerStates;
+
+            for (const auto& learner : m_parameterLearners)
+            {
+                // TODO: add DictionaryValue(T&&)
+                learnerStates.push_back(DictionaryValue(learner->Serialize()));
+            }
         
-        std::wstring trainerStateCheckpointFilePath = GetTrainerStateCheckpointFilePath(modelFilePath);
-        auto ckpStream = GetFstream(trainerStateCheckpointFilePath, false);
-        // TODO: this will create an extra copy of all leaner states, 
-        // add DictionaryValue ctor that takes an rvalue!
-        *ckpStream << DictionaryValue(learnerStates);
-        ckpStream->flush();
+            std::wstring trainerStateCheckpointFilePath = GetTrainerStateCheckpointFilePath(modelFilePath);
+            auto ckpStream = GetFstream(trainerStateCheckpointFilePath, false);
+            // TODO: this will create an extra copy of all leaner states, 
+            // add DictionaryValue ctor that takes an rvalue!
+            *ckpStream << DictionaryValue(learnerStates);
+            ckpStream->flush();
+        }
+
+        if (m_distributedTrainer != nullptr)
+        {
+            // all workers need to sync up after saving model to avoid read-after-write hazard
+            // i.e. one worker is in the middle of write while another tries to read
+            m_distributedTrainer->GetCommunicator()->Barrier();
+        }
     }
 
     void Trainer::RestoreFromCheckpoint(const std::wstring& modelFilePath)

Source/CNTKv2LibraryDll/dllmain.cpp

@@ -49,7 +49,8 @@ BOOL APIENTRY DllMain(HMODULE /*hModule*/,
         }
         break;
     case DLL_PROCESS_DETACH:
-        _CrtSetReportHook2(_CRT_RPTHOOK_REMOVE, HandleDebugAssert);
+        // DLL_PROCESS_DETACH may have race condition with code page unload
+        //_CrtSetReportHook2(_CRT_RPTHOOK_REMOVE, HandleDebugAssert);
         break;
 #else
     case DLL_PROCESS_ATTACH:

Tests/UnitTests/V2LibraryDistributionTests/Main.cpp

@@ -57,15 +57,15 @@ void TrainSimpleDistributedFeedForwardClassifer(const DeviceDescriptor& device,
     std::unordered_map<StreamInformation, std::pair<NDArrayViewPtr, NDArrayViewPtr>> inputMeansAndInvStdDevs = { { featureStreamInfo, { nullptr, nullptr } } };
     ComputeInputPerDimMeansAndInvStdDevs(minibatchSource, inputMeansAndInvStdDevs);
 
-    auto nonLinearity = std::bind(Sigmoid, _1, L"");
+    auto nonLinearity = std::bind(Sigmoid, _1, L"Sigmoid");
     auto input = InputVariable({ inputDim }, DataType::Float, L"features");
     auto normalizedinput = PerDimMeanVarianceNormalize(input, inputMeansAndInvStdDevs[featureStreamInfo].first, inputMeansAndInvStdDevs[featureStreamInfo].second);
-    auto classifierOutput = FullyConnectedDNNLayer(normalizedinput, hiddenLayerDim, device, nonLinearity);
+    auto classifierOutput = FullyConnectedDNNLayer(normalizedinput, hiddenLayerDim, device, nonLinearity, std::wstring(L"FullyConnectedInput") );
     for (size_t i = 1; i < numHiddenLayers; ++i)
-        classifierOutput = FullyConnectedDNNLayer(classifierOutput, hiddenLayerDim, device, nonLinearity);
+        classifierOutput = FullyConnectedDNNLayer(classifierOutput, hiddenLayerDim, device, nonLinearity, std::wstring(L"FullyConnectedHidden"));
 
-    auto outputTimesParam = Parameter(NDArrayView::RandomUniform<float>({ numOutputClasses, hiddenLayerDim }, -0.05, 0.05, 1, device));
-    auto outputBiasParam = Parameter(NDArrayView::RandomUniform<float>({ numOutputClasses }, -0.05, 0.05, 1, device));
+    auto outputTimesParam = Parameter(NDArrayView::RandomUniform<float>({ numOutputClasses, hiddenLayerDim }, -0.05, 0.05, 1, device), L"outputTimesParam");
+    auto outputBiasParam = Parameter(NDArrayView::RandomUniform<float>({ numOutputClasses }, -0.05, 0.05, 1, device), L"outputBiasParam");
     classifierOutput = Plus(outputBiasParam, Times(outputTimesParam, classifierOutput), L"classifierOutput");
 
     auto labels = InputVariable({ numOutputClasses }, DataType::Float, L"labels");

Tests/UnitTests/V2LibraryTests/Common.h

@@ -157,16 +157,16 @@ inline CNTK::FunctionPtr FullyConnectedLinearLayer(CNTK::Variable input, size_t
     assert(input.Shape().Rank() == 1);
     size_t inputDim = input.Shape()[0];
 
-    auto timesParam = CNTK::Parameter({ outputDim, inputDim }, CNTK::DataType::Float, CNTK::GlorotUniformInitializer(), device);
-    auto timesFunction = CNTK::Times(timesParam, input);
+    auto timesParam = CNTK::Parameter({ outputDim, inputDim }, CNTK::DataType::Float, CNTK::GlorotUniformInitializer(), device, L"timesParam");
+    auto timesFunction = CNTK::Times(timesParam, input, L"times");
 
-    auto plusParam = CNTK::Parameter({ outputDim }, 0.0f, device);
+    auto plusParam = CNTK::Parameter({ outputDim }, 0.0f, device, L"plusParam");
     return CNTK::Plus(plusParam, timesFunction, outputName);
 }
 
-inline CNTK::FunctionPtr FullyConnectedDNNLayer(CNTK::Variable input, size_t outputDim, const CNTK::DeviceDescriptor& device, const std::function<CNTK::FunctionPtr(const CNTK::FunctionPtr&)>& nonLinearity)
+inline CNTK::FunctionPtr FullyConnectedDNNLayer(CNTK::Variable input, size_t outputDim, const CNTK::DeviceDescriptor& device, const std::function<CNTK::FunctionPtr(const CNTK::FunctionPtr&)>& nonLinearity, const std::wstring& outputName = L"")
 {
-    return nonLinearity(FullyConnectedLinearLayer(input, outputDim, device));
+    return nonLinearity(FullyConnectedLinearLayer(input, outputDim, device, outputName));
 }
 
 inline CNTK::FunctionPtr FullyConnectedFeedForwardClassifierNet(CNTK::Variable input,

Tests/UnitTests/V2LibraryTests/NDArrayViewTests.cpp

@@ -109,7 +109,6 @@ void TestNDArrayView(size_t numAxes, const DeviceDescriptor& device)
 
     // Test readonliness
     auto errorMsg = "Was incorrectly able to get a writable buffer pointer from a readonly view";
-
     // Should not be able to get the WritableDataBuffer for a read-only view
     VerifyException([&aliasView]() {
         ElementType* aliasViewBuffer = aliasView->WritableDataBuffer<ElementType>();