Make data loader threads daemonic

Summary: Make data loader threads daemonic so the main process can exit when an exception is raised.

Reviewed By: ashwinb, newstzpz

Differential Revision: D9478059

fbshipit-source-id: 00bfaab51295b63c2f95ac1be99ae56a0ccf9d94

detectron/roi_data/loader.py

@@ -224,6 +224,7 @@ class RoIDataLoader(object):
 
     def start(self, prefill=False):
         for w in self._workers + self._enqueuers:
+            w.setDaemon(True)
             w.start()
         if prefill:
             logger.info('Pre-filling mini-batch queue...')