Added PyForwardFromTo and PyBackwardFromTo to Net, for releasing GIL …

Makefile

@@ -397,6 +397,10 @@ LIBRARY_DIRS += $(BLAS_LIB)
 
 LIBRARY_DIRS += $(LIB_BUILD_DIR)
 
+#for linking to the libpython2.7 for releasing scope in pycaffe 
+#(however should be linked even if pycaffe disabled)
+LIBRARIES += python2.7
+
 # Automatic dependency generation (nvcc is handled separately)
 CXXFLAGS += -MMD -MP
 
@@ -593,19 +597,19 @@ $(TEST_ALL_BIN): $(TEST_MAIN_SRC) $(TEST_OBJS) $(GTEST_OBJ) \
 		| $(DYNAMIC_NAME) $(TEST_BIN_DIR)
 	@ echo CXX/LD -o $@ $<
 	$(Q)$(CXX) $(TEST_MAIN_SRC) $(TEST_OBJS) $(GTEST_OBJ) \
-		-o $@ $(LINKFLAGS) $(LDFLAGS) -l$(LIBRARY_NAME) -Wl,-rpath,$(ORIGIN)/../lib
+		-o $@ $(LINKFLAGS) -l$(LIBRARY_NAME)  $(LDFLAGS) -Wl,-rpath,$(ORIGIN)/../lib
 
 $(TEST_CU_BINS): $(TEST_BIN_DIR)/%.testbin: $(TEST_CU_BUILD_DIR)/%.o \
 	$(GTEST_OBJ) | $(DYNAMIC_NAME) $(TEST_BIN_DIR)
 	@ echo LD $<
 	$(Q)$(CXX) $(TEST_MAIN_SRC) $< $(GTEST_OBJ) \
-		-o $@ $(LINKFLAGS) $(LDFLAGS) -l$(LIBRARY_NAME) -Wl,-rpath,$(ORIGIN)/../lib
+		-o $@ $(LINKFLAGS) -l$(LIBRARY_NAME) $(LDFLAGS) -Wl,-rpath,$(ORIGIN)/../lib
 
 $(TEST_CXX_BINS): $(TEST_BIN_DIR)/%.testbin: $(TEST_CXX_BUILD_DIR)/%.o \
 	$(GTEST_OBJ) | $(DYNAMIC_NAME) $(TEST_BIN_DIR)
 	@ echo LD $<
 	$(Q)$(CXX) $(TEST_MAIN_SRC) $< $(GTEST_OBJ) \
-		-o $@ $(LINKFLAGS) $(LDFLAGS) -l$(LIBRARY_NAME) -Wl,-rpath,$(ORIGIN)/../lib
+		-o $@ $(LINKFLAGS) -l$(LIBRARY_NAME) $(LDFLAGS) -Wl,-rpath,$(ORIGIN)/../lib
 
 # Target for extension-less symlinks to tool binaries with extension '*.bin'.
 $(TOOL_BUILD_DIR)/%: $(TOOL_BUILD_DIR)/%.bin | $(TOOL_BUILD_DIR)

include/caffe/common.hpp

@@ -181,7 +181,6 @@ class Caffe {
 
   DISABLE_COPY_AND_ASSIGN(Caffe);
 };
-
 }  // namespace caffe
 
 #endif  // CAFFE_COMMON_HPP_

include/caffe/net.hpp

@@ -12,6 +12,8 @@
 #include "caffe/layer.hpp"
 #include "caffe/proto/caffe.pb.h"
 
+#include "Python.h"
+
 namespace caffe {
 
 /**
@@ -52,6 +54,19 @@ class Net {
    * included.
    */
   Dtype ForwardFromTo(int start, int end);
+  /**
+   * Basically, a ForwardFromTo, that release Python GIL, so that pycaffe
+   * can make multithreaded predictions. This is exposed to python-boost interface
+   * instead of ForwardFromTo
+   */
+  Dtype PyForwardFromTo(int start, int end) {
+    // Release GIL
+    m_thread_state = PyEval_SaveThread();
+    Dtype result = ForwardFromTo(start, end);
+    PyEval_RestoreThread(m_thread_state);
+    m_thread_state = NULL;
+    return result;
+  }
   Dtype ForwardFrom(int start);
   Dtype ForwardTo(int end);
   /// @brief DEPRECATED; set input blobs then use Forward() instead.
@@ -71,6 +86,18 @@ class Net {
    */
   void Backward();
   void BackwardFromTo(int start, int end);
+  /**
+   * Basically, a BackwardFromTo, that release Python GIL, so that pycaffe
+   * can make multithreaded predictions. This is exposed to python-boost interface
+   * instead of BackwardFromTo.
+   **/
+  void PyBackwardFromTo(int start, int end) {
+    // Release GIL
+    m_thread_state = PyEval_SaveThread();
+    BackwardFromTo(start, end);
+    PyEval_RestoreThread(m_thread_state);
+    m_thread_state = NULL;
+  }
   void BackwardFrom(int start);
   void BackwardTo(int end);
 
@@ -308,6 +335,9 @@ class Net {
   /// The root net that actually holds the shared layers in data parallelism
   const Net* const root_net_;
   DISABLE_COPY_AND_ASSIGN(Net);
+
+  // For releasing/reacquiring GIL with pycaffe
+  PyThreadState * m_thread_state;
 };
 
 

python/caffe/_caffe.cpp

@@ -268,8 +268,11 @@ BOOST_PYTHON_MODULE(_caffe) {
     bp::no_init)
     .def("__init__", bp::make_constructor(&Net_Init))
     .def("__init__", bp::make_constructor(&Net_Init_Load))
-    .def("_forward", &Net<Dtype>::ForwardFromTo)
-    .def("_backward", &Net<Dtype>::BackwardFromTo)
+    // Instead of ForwardFromTo and BackwardFromTo,
+    // expose PyForwardFromTo and PyBackwardFromTo,
+    // basically the same thing but with GIL release
+    .def("_forward", &Net<Dtype>::PyForwardFromTo)
+    .def("_backward", &Net<Dtype>::PyBackwardFromTo)
     .def("reshape", &Net<Dtype>::Reshape)
     // The cast is to select a particular overload.
     .def("copy_from", static_cast<void (Net<Dtype>::*)(const string)>(

python/caffe/test/test_python_layer.py

@@ -5,7 +5,6 @@
 
 import caffe
 
-
 class SimpleLayer(caffe.Layer):
     """A layer that just multiplies by ten"""
 
@@ -97,8 +96,8 @@ def phase_net_file():
         return f.name
 
 
-@unittest.skipIf('Python' not in caffe.layer_type_list(),
-    'Caffe built without Python layer support')
+#@unittest.skipIf('Python' not in caffe.layer_type_list(),
+#    'Caffe built without Python layer support')
 class TestPythonLayer(unittest.TestCase):
     def setUp(self):
         net_file = python_net_file()

src/caffe/net.cpp

@@ -1,4 +1,5 @@
 #include <algorithm>
+#include <cstring>
 #include <map>
 #include <set>
 #include <string>
@@ -19,6 +20,8 @@
 
 #include "caffe/test/test_caffe_main.hpp"
 
+#include "Python.h"
+
 namespace caffe {
 
 template <typename Dtype>
@@ -536,9 +539,17 @@ Dtype Net<Dtype>::ForwardFromTo(int start, int end) {
   CHECK_GE(start, 0);
   CHECK_LT(end, layers_.size());
   Dtype loss = 0;
+  bool is_python;
   for (int i = start; i <= end; ++i) {
     // LOG(ERROR) << "Forwarding " << layer_names_[i];
+    is_python = strcmp(layers_[i]->type(), "Python") == 0;
+    if (is_python) {
+        PyEval_RestoreThread(m_thread_state);
+        m_thread_state = NULL;
+    }
     Dtype layer_loss = layers_[i]->Forward(bottom_vecs_[i], top_vecs_[i]);
+    if (is_python)
+        m_thread_state = PyEval_SaveThread();
     loss += layer_loss;
     if (debug_info_) { ForwardDebugInfo(i); }
   }
@@ -581,10 +592,16 @@ template <typename Dtype>
 void Net<Dtype>::BackwardFromTo(int start, int end) {
   CHECK_GE(end, 0);
   CHECK_LT(start, layers_.size());
+  bool is_python;
   for (int i = start; i >= end; --i) {
     if (layer_need_backward_[i]) {
+      is_python = strcmp(layers_[i]->type(), "Python") == 0;
+      if (is_python)
+          PyEval_RestoreThread(m_thread_state);
       layers_[i]->Backward(
           top_vecs_[i], bottom_need_backward_[i], bottom_vecs_[i]);
+      if (is_python)
+          m_thread_state = PyEval_SaveThread();
       if (debug_info_) { BackwardDebugInfo(i); }
     }
   }