From: Victor Stinner <vstinner@python.org>
Date: Wed, 17 Jun 2020 17:10:47 +0000 (+0200)
Subject: bpo-41006: collections imports lazily heap (GH-20940)
X-Git-Tag: v3.10.0a1~597
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7824cc05bfe7f8181b21848a52007ddaf5612b9b;p=thirdparty%2FPython%2Fcpython.git

bpo-41006: collections imports lazily heap (GH-20940)

The collections module now imports lazily the heapq modules in the
Counter.most_common() method to speedup Python startup time.
---

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index 42d0ec777c3f..5d75501645fc 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -27,7 +27,6 @@ __all__ = [
 ]
 
 import _collections_abc
-import heapq as _heapq
 import sys as _sys
 
 from itertools import chain as _chain
@@ -608,7 +607,10 @@ class Counter(dict):
         # Emulate Bag.sortedByCount from Smalltalk
         if n is None:
             return sorted(self.items(), key=_itemgetter(1), reverse=True)
-        return _heapq.nlargest(n, self.items(), key=_itemgetter(1))
+
+        # Lazy import to speedup Python startup time
+        import heapq
+        return heapq.nlargest(n, self.items(), key=_itemgetter(1))
 
     def elements(self):
         '''Iterator over elements repeating each as many times as its count.