Add fetch metrics

python/paddle/fluid/tests/book/high-level-api/recognize_digits/test_recognize_digits_conv.py

@@ -97,7 +97,8 @@ def train(use_cuda, save_dirname):
             #     if math.isnan(float(avg_cost)):
             #         sys.exit("got NaN loss, training failed.")
         elif isinstance(event, fluid.EndStepEvent):
-            print("Step {0}, Epoch {1}".format(event.step, event.epoch))
+            print("Step {0}, Epoch {1} Metrics {2}".format(
+                event.step, event.epoch, map(numpy.array, event.metrics)))
 
     train_reader = paddle.batch(
         paddle.reader.shuffle(

python/paddle/fluid/trainer.py

@@ -49,12 +49,14 @@ class BeginStepEvent(object):
     def __init__(self, epoch_id, step_id):
         self.epoch = epoch_id
         self.step = step_id
+        self.fetch_metrics = True
 
 
 class EndStepEvent(object):
-    def __init__(self, epoch_id, step_id):
+    def __init__(self, epoch_id, step_id, metrics):
         self.epoch = epoch_id
         self.step = step_id
+        self.metrics = metrics
 
 
 def check_and_get_place(place):
@@ -259,12 +261,24 @@ class Trainer(object):
             feeder = data_feeder.DataFeeder(
                 feed_list=feed_var_list, place=self.place)
             exe = executor.Executor(self.place)
+            reader = feeder.decorate_reader(reader, multi_devices=False)
+            self._train_by_any_executor(event_handler, exe, num_epochs, reader)
+
+    def _train_by_any_executor(self, event_handler, exe, num_epochs, reader):
         for epoch_id in range(num_epochs):
             event_handler(BeginEpochEvent(epoch_id))
             for step_id, data in enumerate(reader()):
-                    event_handler(BeginStepEvent(epoch_id, step_id))
-                    exe.run(feed=feeder.feed(data), fetch_list=[])
-                    event_handler(EndStepEvent(epoch_id, step_id))
+                begin_event = BeginStepEvent(epoch_id, step_id)
+                event_handler(begin_event)
+                if begin_event.fetch_metrics:
+                    metrics = exe.run(feed=data,
+                                      fetch_list=[
+                                          var.name
+                                          for var in self.train_func_outputs
+                                      ])
+                else:
+                    metrics = exe.run(feed=data, fetch_list=[])
+                event_handler(EndStepEvent(epoch_id, step_id, metrics))
             event_handler(EndEpochEvent(epoch_id))
 
     def _test_by_executor(self, reader, feed_order, fetch_list):
@@ -293,17 +307,8 @@ class Trainer(object):
                 feed_list=feed_var_list, place=self.place)
             reader = feeder.decorate_reader(reader, multi_devices=True)
             for epoch_id in range(num_epochs):
-                event_handler(BeginEpochEvent(epoch_id=epoch_id))
-                for step_id, data in enumerate(reader()):
-                    event_handler(
-                        BeginStepEvent(
-                            epoch_id=epoch_id, step_id=step_id))
-                    pe.run(feed=data, fetch_list=[])
-                    event_handler(
-                        EndStepEvent(
-                            epoch_id=epoch_id, step_id=step_id))
-
-                event_handler(EndEpochEvent(epoch_id=epoch_id))
+                self._train_by_any_executor(event_handler, pe, num_epochs,
+                                            reader)
 
     def _get_parallel_executor(self):
         return getattr(self, 'parallel_executor', None)