From: Raymond Hettinger <python@rcn.com>
Date: Sat, 25 Jun 2011 15:14:53 +0000 (+0200)
Subject: Issue 11802:  filecmp cache was growing without bound.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=2c316a3e298b072f1f017cd3ba197905c43af926;p=python

Issue 11802:  filecmp cache was growing without bound.
---

diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index 89a48359a2..4728317fce 100644
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -48,11 +48,12 @@ def cmp(f1, f2, shallow=1):
     if s1[1] != s2[1]:
         return False
 
-    result = _cache.get((f1, f2))
-    if result and (s1, s2) == result[:2]:
-        return result[2]
-    outcome = _do_cmp(f1, f2)
-    _cache[f1, f2] = s1, s2, outcome
+    outcome = _cache.get((f1, f2, s1, s2))
+    if outcome is None:
+        outcome = _do_cmp(f1, f2)
+        if len(_cache) > 100:      # limit the maximum size of the cache
+            _cache.clear()
+        _cache[f1, f2, s1, s2] = outcome
     return outcome
 
 def _sig(st):
diff --git a/Misc/NEWS b/Misc/NEWS
index bddddfa29c..9e0b8f4b8f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -16,6 +16,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #11802:  The cache in filecmp now has a maximum size of 100 so that
+  it won't grow without bound.
+
 - Issue #12404: Remove C89 incompatible code from mmap module. Patch by Akira
   Kitada.