From: Serhiy Storchaka <storchaka@gmail.com>
Date: Thu, 12 Jan 2017 17:42:20 +0000 (+0200)
Subject: Issue #28969: Fixed race condition in C implementation of functools.lru_cache.
X-Git-Tag: v3.7.0a1~1576
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=617c7753ce010617b45ae3bfa53a90c07b51510a;p=python

Issue #28969: Fixed race condition in C implementation of functools.lru_cache.
KeyError could be raised when cached function with full cache was
simultaneously called from differen threads with the same uncached arguments.
---

617c7753ce010617b45ae3bfa53a90c07b51510a
diff --cc Lib/test/test_functools.py
index eeb3a227a2,824549b803..63fe83e5db
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@@ -7,8 -7,8 +7,9 @@@ import pickl
  from random import choice
  import sys
  from test import support
+ import time
  import unittest
 +import unittest.mock
  from weakref import proxy
  import contextlib
  try:
diff --cc Misc/NEWS
index db9243fa3c,3b84dd7791..892471291e
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@@ -212,9 -44,10 +212,13 @@@ Core and Builtin
  Library
  -------
  
+ - Issue #28969: Fixed race condition in C implementation of functools.lru_cache.
+   KeyError could be raised when cached function with full cache was
+   simultaneously called from differen threads with the same uncached arguments.
+ 
 +- Issue #20804: The unittest.mock.sentinel attributes now preserve their
 +  identity when they are copied or pickled.
 +
  - Issue #29142: In urllib.request, suffixes in no_proxy environment variable with
    leading dots could match related hostnames again (e.g. .b.c matches a.b.c).
    Patch by Milan Oberkirch.
diff --cc Objects/dictobject.c
index baef589427,a7b403bcec..9950f50896
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@@ -1836,16 -1848,10 +1835,10 @@@ _PyDict_Pop_KnownHash(PyObject *dict, P
          _PyErr_SetKeyError(key);
          return NULL;
      }
-     if (!PyUnicode_CheckExact(key) ||
-         (hash = ((PyASCIIObject *) key)->hash) == -1) {
-         hash = PyObject_Hash(key);
-         if (hash == -1)
-             return NULL;
-     }
 -    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &value_addr, &hashpos);
 +    ix = (mp->ma_keys->dk_lookup)(mp, key, hash, &old_value, &hashpos);
      if (ix == DKIX_ERROR)
          return NULL;
 -    if (ix == DKIX_EMPTY || *value_addr == NULL) {
 +    if (ix == DKIX_EMPTY || old_value == NULL) {
          if (deflt) {
              Py_INCREF(deflt);
              return deflt;