bug fix in prefecthongpus

tensorpack/dataflow/prefetch.py

@@ -13,7 +13,8 @@ import os
 from .base import ProxyDataFlow
 from ..utils.concurrency import *
 from ..utils.serialize import loads, dumps
-from ..utils import logger, change_env
+from ..utils import logger
+from ..utils.gpu import change_gpu
 
 __all__ = ['PrefetchData', 'BlockParallel']
 try:
@@ -173,8 +174,8 @@ class PrefetchDataZMQ(ProxyDataFlow):
 class PrefetchOnGPUs(PrefetchDataZMQ):
     """ Prefetch with each process having a specific CUDA_VISIBLE_DEVICES"""
     def __init__(self, ds, gpus, pipedir=None):
-        super(PrefetchOnGPUs, self).__init__(ds, len(gpus), pipedir)
         self.gpus = gpus
+        super(PrefetchOnGPUs, self).__init__(ds, len(gpus), pipedir)
 
     def start_processes(self):
         with mask_sigint():