add message for debug

Author: Han Wang

dpgen/dispatcher/LazyLocalContext.py

@@ -121,13 +121,16 @@ def check_finish(self, proc):
     def get_return(self, proc):
         ret = proc.poll()
         if ret is None:
+            print('---------------- proc is None ----------------')
             return None, None, None
         else :
             try:
                 o, e = proc.communicate()
+                print('---------------- communicate finishes ----------------')
                 stdout = SPRetObj(o)
                 stderr = SPRetObj(e)
             except ValueError:
+                print('---------------- communicate failed ----------------')
                 stdout = None
                 stderr = None
         return ret, stdout, stderr