From acd0bb39df5c9ca486e49ec55ae34538242ce071 Mon Sep 17 00:00:00 2001
From: Florian Apolloner <florian@apolloner.eu>
Date: Sat, 18 May 2013 17:36:31 +0200
Subject: [PATCH] Fixed #14894 -- Ensure that activating a translation doesn't
 run into threading issues.

Thanks to maxbublis for the report and sergeykolosov for the patch.
---
 django/utils/translation/trans_real.py |  2 +-
 tests/i18n/tests.py                    | 30 ++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/django/utils/translation/trans_real.py b/django/utils/translation/trans_real.py
index f7b15240854..26be0ed729c 100644
--- a/django/utils/translation/trans_real.py
+++ b/django/utils/translation/trans_real.py
@@ -140,7 +140,7 @@ def translation(language):
         # doesn't affect en-gb), even though they will both use the core "en"
         # translation. So we have to subvert Python's internal gettext caching.
         base_lang = lambda x: x.split('-', 1)[0]
-        if base_lang(lang) in [base_lang(trans) for trans in _translations]:
+        if base_lang(lang) in [base_lang(trans) for trans in list(_translations)]:
             res._info = res._info.copy()
             res._catalog = res._catalog.copy()
 
diff --git a/tests/i18n/tests.py b/tests/i18n/tests.py
index 29223e5add2..1b15720c168 100644
--- a/tests/i18n/tests.py
+++ b/tests/i18n/tests.py
@@ -334,6 +334,36 @@ class TranslationTests(TestCase):
             self.assertEqual(rendered, 'My other name is James.')
 
 
+class TranslationThreadSafetyTests(TestCase):
+    def setUp(self):
+        self._old_language = get_language()
+        self._translations = trans_real._translations
+
+        # here we rely on .split() being called inside the _fetch()
+        # in trans_real.translation()
+        class sideeffect_str(str):
+            def split(self, *args, **kwargs):
+                res = str.split(self, *args, **kwargs)
+                trans_real._translations['en-YY'] = None
+                return res
+
+        trans_real._translations = {sideeffect_str('en-XX'): None}
+
+    def tearDown(self):
+        trans_real._translations = self._translations
+        activate(self._old_language)
+
+    def test_bug14894_translation_activate_thread_safety(self):
+        translation_count = len(trans_real._translations)
+        try:
+            translation.activate('pl')
+        except RuntimeError:
+            self.fail('translation.activate() is not thread-safe')
+
+        # make sure sideeffect_str actually added a new translation
+        self.assertLess(translation_count, len(trans_real._translations))
+
+
 @override_settings(USE_L10N=True)
 class FormattingTests(TestCase):