fix reader exit error (#2108)

* fix reader exit error
* fix commet

dygraph/ppdet/data/reader.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 import copy
 import traceback
 import six
@@ -32,6 +33,8 @@ from . import transform
 from ppdet.utils.logger import setup_logger
 logger = setup_logger('reader')
 
+MAIN_PID = os.getpid()
+
 
 class Compose(object):
     def __init__(self, transforms, num_classes=81):
@@ -73,6 +76,15 @@ class BatchCompose(Compose):
                             format(f, e, str(stack_info)))
                 raise e
 
+        # accessing ListProxy in main process (no worker subprocess)
+        # may incur errors in some enviroments, ListProxy back to
+        # list if no worker process start, while this `__call__`
+        # will be called in main process
+        global MAIN_PID
+        if os.getpid() == MAIN_PID and \
+            isinstance(self.output_fields, mp.managers.ListProxy):
+            self.output_fields = []
+
         # parse output fields by first sample
         # **this shoule be fixed if paddle.io.DataLoader support**
         # For paddle.io.DataLoader not support dict currently,

dygraph/ppdet/modeling/backbones/vgg.py

@@ -4,7 +4,7 @@ import paddle
 import paddle.nn as nn
 import paddle.nn.functional as F
 from paddle import ParamAttr
-from paddle.fluid.regularizer import L2Decay
+from paddle.regularizer import L2Decay
 from paddle.nn import Conv2D, MaxPool2D
 from ppdet.core.workspace import register, serializable