Use LRU cache when getting POS tagger to avoid loading weights each time pos_tag() is called.

Author: strangetom

nltk/tag/__init__.py

@@ -65,6 +65,8 @@
 isort:skip_file
 """
 
+import functools
+
 from nltk.tag.api import TaggerI
 from nltk.tag.util import str2tuple, tuple2str, untag
 from nltk.tag.sequential import (
@@ -100,6 +102,7 @@
 }
 
 
+@functools.lru_cache
 def _get_tagger(lang=None):
     if lang == "rus":
         tagger = PerceptronTagger(lang=lang)