Switch to pickle by default. In Python3 pickle is as fast as msgpack.

tensorpack/dataflow/parallel.py

@@ -19,7 +19,7 @@ from ..utils import logger
 from ..utils.develop import log_deprecated
 from ..utils.concurrency import (
     StoppableThread, enable_death_signal, ensure_proc_terminate, start_proc_mask_signal)
-from ..utils.serialize import dumps, loads
+from ..utils.serialize import dumps_once as dumps, loads_once as loads
 from .base import DataFlow, DataFlowReentrantGuard, DataFlowTerminated, ProxyDataFlow
 
 __all__ = ['PrefetchData', 'MultiProcessPrefetchData',

tensorpack/dataflow/parallel_map.py

@@ -9,7 +9,7 @@ import zmq
 from six.moves import queue
 
 from ..utils.concurrency import StoppableThread, enable_death_signal
-from ..utils.serialize import dumps, loads
+from ..utils.serialize import dumps_once as dumps, loads_once as loads
 from ..utils.develop import log_deprecated
 from .base import DataFlow, DataFlowReentrantGuard, ProxyDataFlow
 from .common import RepeatedData, BatchData

tensorpack/utils/serialize.py

@@ -94,7 +94,7 @@ class PickleSerializer(object):
 
 
 # Define the default serializer to be used that dumps data to bytes
-_DEFAULT_S = os.environ.get('TENSORPACK_SERIALIZE', 'msgpack')
+_DEFAULT_S = os.environ.get('TENSORPACK_SERIALIZE', 'pickle')
 
 if _DEFAULT_S == "pyarrow":
     dumps = PyarrowSerializer.dumps_bytes