From 70797194ab678d53bb1c24536354aa1acc4db467 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sat, 25 Jun 2011 17:20:21 +0200
Subject: Issue 11802:  filecmp cache was growing without bound.

---
 Lib/filecmp.py | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index e5983cd..f5cea1d 100644
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -48,11 +48,12 @@ def cmp(f1, f2, shallow=True):
     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):
-- 
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