fix invalid context when run mxnet and nbench (#1047)

src/ngraph/runtime/gpu/gpu_cuda_context_manager.cpp

@@ -21,7 +21,7 @@
 
 using namespace ngraph;
 
-runtime::gpu::CudaContextManager& runtime::gpu::CudaContextManager::instance()
+runtime::gpu::CudaContextManager& runtime::gpu::CudaContextManager::Instance()
 {
     static CudaContextManager manager;
     return manager;
@@ -32,7 +32,6 @@ runtime::gpu::CudaContextManager::CudaContextManager()
     CUDA_SAFE_CALL(cuInit(0));
     CUDA_SAFE_CALL(cuDeviceGet(&m_device, 0));
     CUDA_SAFE_CALL(cuDevicePrimaryCtxRetain(&m_context, m_device));
-    m_context_ptr = std::make_shared<CUcontext>(m_context);
 }
 
 runtime::gpu::CudaContextManager::~CudaContextManager()

src/ngraph/runtime/gpu/gpu_cuda_context_manager.hpp

@@ -30,19 +30,19 @@ namespace ngraph
             class CudaContextManager
             {
             public:
-                static CudaContextManager& instance();
+                static CudaContextManager& Instance();
                 CudaContextManager(CudaContextManager const&) = delete;
                 CudaContextManager(CudaContextManager&&) = delete;
                 CudaContextManager& operator=(CudaContextManager const&) = delete;
                 CudaContextManager& operator=(CudaContextManager&&) = delete;
 
-                std::shared_ptr<CUcontext> get_context() { return m_context_ptr; }
+                CUcontext GetContext() { return m_context; }
+                void SetContextCurrent() { cuCtxSetCurrent(m_context); }
             protected:
                 CudaContextManager();
                 ~CudaContextManager();
                 CUdevice m_device;
                 CUcontext m_context;
-                std::shared_ptr<CUcontext> m_context_ptr;
             };
         }
     }

src/ngraph/runtime/gpu/gpu_external_function.cpp

@@ -259,7 +259,7 @@ runtime::gpu::GPU_ExternalFunction::GPU_ExternalFunction(
     // Create context use driver API and make it current, the runtime call will pickup the context
     // http://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html
     // #interoperability-between-runtime-and-driver-apis
-    ngraph::runtime::gpu::CudaContextManager::instance();
+    ngraph::runtime::gpu::CudaContextManager::Instance().SetContextCurrent();
     m_ctx->compiled_kernel_pool = new CudaFunctionPool;
 }