fix issue 'could not satisfy explicit device' (#3641)

* fix issue 'could not satisfy explicit device'

* remove the line unrelated to fix issue

research/slim/train_image_classifier.py

@@ -552,6 +552,8 @@ def main(_):
     # Merge all summaries together.
     summary_op = tf.summary.merge(list(summaries), name='summary_op')
 
+    # Add config to avoid 'could not satisfy explicit device' problem 
+    sess_config = tf.ConfigProto(allow_soft_placement=True)
 
     ###########################
     # Kicks off the training. #
@@ -567,7 +569,8 @@ def main(_):
         log_every_n_steps=FLAGS.log_every_n_steps,
         save_summaries_secs=FLAGS.save_summaries_secs,
         save_interval_secs=FLAGS.save_interval_secs,
-        sync_optimizer=optimizer if FLAGS.sync_replicas else None)
+        sync_optimizer=optimizer if FLAGS.sync_replicas else None,
+        session_config=sess_config)
 
 
 if __name__ == '__main__':